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  • 51.
    Fridberg, Marie
    et al.
    Högskolan Kristianstad, Forskningsmiljön Learning in Science and Mathematics (LISMA). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap.
    Redfors, Andreas
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Learning in Science and Mathematics (LISMA).
    Children’s collaborative learning in science scaffolded by tablets2017Inngår i: Digital Childhoods: technologies and children's everyday lives / [ed] Susan Jill Danby, Marilyn Fleer, Christina Davidson, Maria Hatzigianni, Singapore: Springer, 2017Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 52. Glantz, Maria
    et al.
    Håkansson, Andreas
    Lunds universitet.
    Lindmark Månsson, Helena
    Paulsson, Marie
    Nilsson, Lars
    Revealing the Size, Conformation, and Shape of Casein Micelles and Aggregates with Asymmetrical Flow Field-Flow Fractionation and Multiangle Light Scattering2010Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, nr 15, s. 12585-12591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Casein (CN) micelles are naturally occurring colloidal protein aggregates present in a dispersed state in milk. In this paper we aim to obtain a detailed description of physicochemical properties of CN micelles over the entire size distribution using asymmetrical flow field-flow fractionation (AsFlFFF) connected to multiangle light scattering (MALS) and refractive index (RI) detection. Conclusions are drawn on the colloidal level regarding shape and conformation by comparison with models of colloidal particles. By using AsFlFFF-MALS-RI, it is concluded that the CN micelles are highly polydisperse with an average rms radius and hydrodynamic radius of 177 and 116 nm, respectively. The results show that the majority of CN micelles have a spherical shape, whereas a low concentration exists of larger and elongated aggregates. By comparison with models of aggregates of colloidal particles, the aggregates are shown to be anisotropic, e.g., aggregating linearly (threadlike) or in a sheet, rather than forming randomly spherical clusters. The results show that the characterization of colloidal dispersions with AsFlFFF-MALS-RI and the comparison with theoretical models are of a general character and, thus, of fundamental importance for colloidal dispersions.

  • 53.
    Hedström, Marita
    et al.
    Högskolan Kristianstad, Fakulteten för ekonomi, Avdelningen för design.
    Åkerlund, Linda
    Högskolan Kristianstad, Fakulteten för ekonomi, Avdelningen för design.
    Att skapa användarupplevelser genom digitalisering med AI: en studie av faktorer för interaktion som påverkar användarupplevelser vid digitalisering med AI hos BUP2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

     I den här studien har vi undersökt vilka faktorer för interaktion som påverkar användarupplevelser vid digitalisering med AI (Artificiell Intelligens). Det vår analys och slutsats pekar på är faktorer som: otydlighet, inkonsekvens i interaktioner, brist på feedback och information men även personliga samtal och väntetider. Våra empiriska undersökningar visar på att dessa faktorer påverkar upplevelserna på olika sätt, både negativt och positivt. Genom att beakta dessa faktorer samt även möjligheterna som digitalisering med AI ger, kan detta bidra till att skapa önskvärda användarupplevelser. Våra studier har resulterat i ett designförslag där vi föreslår att AI används för rutinuppgifter, bedömningar och för att stödja dokumentation.

    Studien är relevant i och med att vi har identifierat att det finns luckor i tidigare forskning om just kopplingen mellan användarupplevelse, digitalisering och AI.

    Vi har använt kvalitativa metoder för de empiriska undersökningarna: observation och intervjuer. Vi har även genomfört en workshop för att undersöka det designförslag vi kommit fram till.

    Vi vill peka på att resultatet av våra undersökningar är relevant för de digitaliseringsprojekt som pågår idag, men vi ser även att det krävs vidare studier i form av att en utveckling av den föreslagna lösningen genomförs och testas, samt att man undersöker användarupplevelse vid digitalisering med AI vidare med flera fall.

  • 54.
    Hellström, Line
    Högskolan Kristianstad, Fakulteten för naturvetenskap.
    Framställning och vidareympning av gårdskultur: Vad skiljer en yoghurt fermenterad av gårdens egen bakterieflora från industriell och traditionell yoghurt?2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Bakgrund: Med industrialiseringen har de traditionella yoghurtkulturerna med en mångfald av samverkande mjölksyrabakterier fått ge plats åt de mer standardiserade. En gårdskultur framställs genom att obehandlad mjölk spontanfermenteras av gårdens egen bakterieflora och får därigenom en unik karaktär. Bakteriekulturen kan sedan ympas vidare för tillverkning av yoghurt.Syfte: Syftet med studien är framställning och vidareympning samt sensorisk och mikrobiologisk karaktärisering av termofil gårdskultur från obehandlad mjölk. Vidareympningen avser framställning av yoghurt fermenterad av gårdens egen bakterieflora.Metod: Gårdskulturen framställdes och ympades till yoghurt. Yoghurten undersöktes genom mikrobiologisk karaktärisering, antibiotikaresistens och sensorisk profilering samt jämfördes med industriell kultur och en traditionell heirloomkultur.Resultat: Resultatet visade att gårdskulturen skiljde sig både mikrobiologisk och sensoriskt. Gårdskulturen innehöll stammar av enterokocker vilka inte visade på resistens mot analyserade antibiotika.Slutsats: Det är möjligt att framställa en gårdskultur av godtagbar mikrobiologisk och sensorisk kvalitet. Gårdskulturen ger en differentierad mikrobiologisk och sensorisk karaktär i jämförelse med en industriell kultur och en traditionell heirloomkultur Metoden kan vara riskfylld och kulturen bör analyseras med avseende på patogen tillväxt. En unik gårdsyoghurt kan vara en metod för gårdsmejerister att i sitt varumärke bygga på terroir och platsens unicitet.

  • 55. Hiller, Carolina
    et al.
    Wendin, Karin
    Nilsson Tengelin, Maria
    Utveckling och tillämpning av sensoriska metoder för objektiva belysningsbedömningar, del I2017Rapport (Annet vitenskapelig)
    Abstract [sv]

    I dag finns tekniska belysningsstandarder som inkluderar parameterar så som ljusstyrka, jämnhet och luminans. Det som saknas är krav som grundar sig på människors upplevelser av belysning och ljusmiljöer. Att få med den upplevelsebaserade dimensionen skulle betyda ett helhetstänk som förmodligen skulle gynna både ljuskomforten och än mer energieffektiva ljusmiljöer och produkter. Att beskriva upplevda belysningsparametrar har hittills visat sig inte vara helt enkelt, och här saknas både kunskap och en gemensam begreppsvärld inom branschen; något som hämmar fastighetsägare att ställa lämpliga krav vid en upphandling liksom belysningstillverkare att utveckla produkter för nya marknader och tillämpningar. Det övergripande syftet med detta forskningsprojekt är att utveckla och tillämpa sensoriska metoder på belysning. Till skillnad från tidigare metoder möjliggör sensoriska metoder objektiva bedömningar av upplevda belysningsparametrar. Syftet med försöken som redovisas i denna delrapport är att vidareutveckla och testa metoden ytterligare. Detta görs genom att nya armaturer testas liksom att försök utförs i en ny verklig kontext (kontorsmiljö). Försöken bygger vidare på resultat från tidigare försök som har rapporterats om i (Boork et al, 2017).En analytisk panel bestående av åtta personer, som uppfyllde särskilda urvalskriterier, har tidigare rekryterats och dessa personer tränades nu för detta specifika delprojekt för att bedöma belysningsprodukter i ett multisensoriskt laboratorium på RISE Research Institutes of Sweden i Borås. Metodutvecklingen fokuserade särskilt på en effektiv träningsprocedur, hantering av ögats adaption, samt bedömning av färg och skuggningar. Förutom laboratorieförsök undersöktes möjligheten att genomföra analytiska bedömningar i en verklig kontext med samma försöksuppställning och panel.Resultaten visade att det är möjligt att använda sensorisk metodik för att genomföra objektiva belysningsbedömningar även för de testade belysningsprodukterna, dvs mindre LED-spotlights. Signifikanta skillnader identifierades mellan de olika armaturerna och som i tidigare försök spelade färgtemperaturen en stor roll för flera av de bedömda egenskaperna; inte minst förstås för ljuskällans gulhet och för läsbarhet (textkontrasten). Liksom i tidigare försök fanns det samband mellan de fysikaliska mätningarna och sensoriska bedömningarna, men inte för alla egenskaper, vilket visar att fysikaliska och sensoriska mätningar ger kompletterande information om belysning. Vidare visade bedömningsförsök i en verklig kontext att likvärdiga resultat uppnåddes som i laboratoriet, om ändock något spretigare och inte heller lika entydiga i jämförelse med verklig kontext i tidigare försök.Den genererade kunskapen väntas på sikt bidra till utveckling av verktyg som stödjer kommunikationen mellan olika professioner inom ljusdesign och planering och på så vis främja mer önskvärda och energieffektiva ljusmiljöer.

  • 56.
    Hiltunen, Jonna
    Högskolan Kristianstad, Sektionen för Lärarutbildning.
    Mekanisk slamavvattning: vid Sibbhults avloppsreningsverk2010Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Detta examensarbete behandlar slamhanteringen på Sibbhults avloppsreningsverk (Sarv).

    I denna rapport tas det upp hur avvattningen och förtjockningen av slammet går till i dagsläget och vilka förändringar som kan göras för att förbättra dessa processer.

    Här visas även vilka eventuella vinster som kan fås med förändringar och eventuella investeringar i en avvattningsapplikation. Redan med små medel kan förtjockningen av slammet förändras, även om det inte införskaffas en mekanisk avvattnare, som t ex med inblandning av polymerer i avloppsvattnet.

    För att finna olika fungerande alternativ har information insamlats från flera företag som tillhandahåller applikationer för slamavvattnare. Information har även införskaffats genom egen erfarenhet under min verksamhetsförlagda utbildnings (VFU) period på SArv, och vid diskussion med personal som arbetar vid vatten- och avloppsreningsverken i Östra Göinge kommun.

  • 57.
    Huang, Qian
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Yin, Qin
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Study on Electronic Health Record and its Implementation2012Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This degree project deals with electronic health record (EHR). The report is divided into two main sections; literature study on electronic health record and an EHR system implementation. In the literature study section, EHR background, development history and service condition are introduced. The paper focuses on the sharing of medical information in different users, data safety and privacy. The adjunctions of computer science, technologies are used to solve the medical informatics’ problems. In the implementation section, based on the study of the current EHR systems, the design and implement of a shared EHR system are presented, which can be accessed by different doctors and patients. Access control function and cryptography protections are included in this system. The system test and evaluation are also given.

  • 58.
    Huang, Xin
    et al.
    Department of Computer Science, Institute for the Future of Computing/Oxford Martin School, University of Oxford.
    Chen, Bangdao
    Department of Computer Science, University of Oxford.
    Markham, Andrew
    Department of Computer Science, Institute for the Future of Computing/Oxford Martin School, University of Oxford.
    Wang, Qinghua
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap. Department of Communications and Networking, Aalto University, Espoo.
    Zheng, Yan
    Department of Communications and Networking, Aalto University, Espoo.
    Roscoe, Andrew William
    Department of Computer Science, Institute for the Future of Computing/Oxford Martin School, University of Oxford.
    Human interactive secure key and ID exchange protocols in body sensor networks2013Inngår i: IET Information Security, ISSN 1751-8709, E-ISSN 1751-8717, Vol. 7, nr 1, s. 30-38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A body sensor network (BSN) is typically a wearable wireless sensor network. Security protection is critical to BSNs, since they collect sensitive personal information. Generally speaking, security protection of BSN relies on identity (ID) and key distribution protocols. Most existing protocols are designed to run in general wireless sensor networks, and are not suitable for BSNs. After carefully examining the characteristics of BSNs, the authors propose human interactive empirical channel-based security protocols, which include an elliptic curve Diffie–Hellman version of symmetric hash commitment before knowledge protocol and an elliptic curve Diffie–Hellman version of hash commitment before knowledge protocol. Using these protocols, dynamically distributing keys and IDs become possible. As opposite to present solutions, these protocols do not need any pre-deployment of keys or secrets. Therefore compromised and expired keys or IDs can be easily changed. These protocols exploit human users as temporary trusted third parties. The authors, thus, show that the human interactive channels can help them to design secure BSNs.

  • 59.
    Huang, Xin
    et al.
    Kina.
    Craig, Paul
    Kina.
    Wang, Qinghua
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap.
    Identity-based association protocols for wireless personal area networks2015Inngår i: Proceedings of The 13th IEEE International Conference on Dependable, Autonomic, and Secure Computing, IEEE conference proceedings, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Identity based infrastructure allows the public keyof a user to be derived easily from a predefined aspect of theirknown identity such as a phone number, passport number orother universally unique identifier. Recently, H¨olbl and Welzerhave proposed an identity-based key establishment protocol.However, this protocol is found to be vulnerable to man-inthe-middle attacks and impersonation attacks. In this paper,we propose multi-channel identity based protocols for wirelesspersonal area networks which can eliminate these attacks.These protocols alleviate the certificate overhead by using apublic key infrastructure which is suitable for wireless personalarea networks.

  • 60.
    Hägg, Elizabeth
    et al.
    Lund University.
    Wärja, Magnus
    Lund University.
    Johansson, Lars-Olof
    Högskolan Kristianstad, Sektionen för Hälsa och Samhälle.
    Customer Service process IT-enabled support Fit or misfit?: a real world case2008Inngår i: Asproth, V. (ed), Proceedings of 31th Information Systems Research Seminar in Scandinavia: public systems in the future: possibilities, challenges and pitfalls, Sundsvall: Mittuniversitetet , 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper is a description of a real world case which focuses on a method to define the major gaps between functional requirements and existing support in a traditional ERP system. To identify and define the major gaps the method is using short interviews, existing documentation and graphic process diagrams. The report covers the process Customer Contact – Order Acknowledgement for a global chemicals manufacturer, Perstorp. The group in focus for this study is Customer Service. The results of this case were presented to Perstorp’s Customer Service as well as IT management as background material to assess improvement possibilities for both processes, IT support and for a new ERP strategy. Many other businesses are in similar situations. The aim in publishing this research paper is that these findings can be of practical use to other businesses as well as be an empirical foundation for other papers and possibly further research.

  • 61.
    Håkansson, Andreas
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    An experimental investigation of the probability distribution of turbulent fragmenting stresses in a high-pressure homogenizer2018Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 177, s. 139-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high-pressure homogenizer (HPH) is, together with the rotor–stator mixer (RSM), the standard equipment for emulsification in many fields of chemical processing. Both give rise to intense turbulence which, in turn, gives rise to drop breakup. Previous investigations focus on average turbulent disruptive stress. However, turbulence is a stochastic phenomenon and drop breakup will be characterized by instantaneous stresses, or more specifically by the probability distribution of instantaneous turbulent stresses.

    This study uses high-resolution particle image velocimetry (PIV) data to measure the probability distribution of turbulent stresses in the HPH. It is concluded that stress distributions approximately follow a lognormal model and that the skewness of the distributions decreases with increasing distance from the gap exit until a constant distribution shape is obtained at the position where the turbulence is fully developed. This converged stress distribution is similar to that obtained for RSMs in previous studies, suggesting that stress distribution shape is a general property. Moreover, large differences are observed when comparing these experimental stress distributions to the most widely used expression for describing this stochastic effect in fragmentation rate models. This indicates that the traditionally used fragmentation rate models can be fundamentally flawed, at least in relation to RSM and HPH emulsification.

  • 62.
    Håkansson, Andreas
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för mat- och måltidsvetenskap.
    Error estimation, validity and best practice guidelines for quantifying coalescence frequency during emulsification using the step-down technique2017Inngår i: HELIYON, ISSN 2405-8440, Vol. 3, nr 7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coalescence during emulsification has a significant effect on the outcome of the process, especially for the high volume fractions of disperse phase common in food and pharmaceutical processing. Controlling emulsification requires that the extent of coalescence during different conditions can be quantified. The step-down technique is the most commonly used method for measuring coalescence frequency during emulsification. However, the validity of the method has been questioned. No in-depth theoretical validation or best practice guidelines have been provided for the step-down technique, or for any of the suggested alternative methods. This contribution derives error estimates for three non-idealities present in every step-down experiment: i) limited sampling rate, ii) non-instantaneous step-down and iii) residual fragmentation after the step. It is concluded that all three factors give rise to systematic errors in estimating coalescence rate. However, by carefully choosing experimental settings, the errors can be kept small. The method, thus, remains suitable for many conditions. Best practice guidelines for applying the method are given, both generally, and more specifically for stirred tank oil-in-water emulsification.

  • 63.
    Håkansson, Andreas
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Humanvetenskap. Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL).
    Experimental methods for measuring coalescence during emulsification: a critical review2016Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 178, s. 47-59Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Emulsification is a common process in the production in many non-solid foods. These food-emulsions often have high disperse phase volume fractions and slow emulsifier dynamics, giving rise to substantial coalescence during emulsification. Optimal design and operation of food-emulsification requires experimental methods to study how emulsification in general and coalescence in particular progresses under different conditions. Methods for coalescence quantification during emulsification has been suggested in literature but they are rarely used in food-emulsification research. This contribution offers a critical review of the different methods that have been suggested with special emphasis on their applicability to technical food-emulsification. The methods are critically compared in terms of design limitations, degree of quantification and applicability. A state-of-the-art in the form of two methods is identified and guidelines for their application are suggested. (C) 2016 Elsevier Ltd. All rights reserved.

  • 64.
    Håkansson, Andreas
    Högskolan Kristianstad, Fakulteten för naturvetenskap, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för mat- och måltidsvetenskap. Lund University.
    Rotor-stator mixers: from batch to continuous Mode of Operation—a review2018Inngår i: Processes, ISSN 2227-9717, E-ISSN 1099-5862, Vol. 6, nr 32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although continuous production processes are often desired, many processing industriesstill work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding of similarities and differences between emulsification in turbulent rotor-stator mixers (also known as high-speed mixers) operated in batch and continuous mode. Rotor-stator mixers are found in many chemical processing industries, and are considered the standard tool for mixing and emulsification of high viscosity products. Since the same rotor-stator heads are often used in both modes of operation, it is sometimes assumed that transitioning from batch to continuous rotor-stator mixers is straight-forward. However, this is not always the case, as has been shown in comparative experimental studies. This review summarizes and critically compares the current understanding of differences between these two operating modes, focusing on shaft power draw, pumping power, efficiency in producing a narrow region of high intensity turbulence, and implications for product quality differences when transitioning from batch to continuousrotor-stator mixers.

  • 65.
    Håkansson, Andreas
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap. Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL).
    Scale-down failed: dissimilarities between high-pressure-homogenizers of different scales due to failed mechanistic matching2017Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 195, s. 31-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high-pressure homogenizer (HPH) is used extensively in the processing of non-solid foods. Food researchers and producers use HPHs of different scales, from laboratory-scale (∼10 L/h) to the largest production-scale machines (∼50 000 L/h). Hence, the process design and interpretation of academic findings regarding industrial condition requires an understanding of differences between scales. This contribution uses theoretical calculations to compare the hydrodynamics of the different scales and interpret differences in the mechanism of drop-breakup.

    Results indicate substantial differences between HPHs of different scales. The laboratory-scale HPH operates in the laminar regime whereas the production-scale is in the fully turbulent regime. The smaller scale machines are also less prone to cavitation and differ in their pressure profiles. This suggest that the HPHs of different scales should be seen as principally different emulsification processes. Conclusions on the effect or functionality of a HPH can therefore not readily be translate between scales.

  • 66.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    Andersson, Ronnie
    Chalmers University.
    Mortensen, Hans-Henrik
    Tetra Pak .
    Innings, Fredrik
    Tetra Pak .
    Experimental investigations of turbulent fragmenting stresses in a rotor-stator mixer. Part 2: probability distributions of instantaneous stresses2017Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 171, s. 638-649Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Drop fragmentation in high intensity turbulent emulsification processing equipment-such as rotor-stator mixers (RSMs)-has traditionally been described in terms of a stress balance; between the stabilizing stress of the drop and the time-averaged turbulent stress at the most intense position of the flow. As shown in part 1 of this series, this approach is often a fruitful first approximation. However, the instantaneous local stress experienced by drops differs,from the time-averaged local stress due to hydrodynamics in general and the stochastic nature of a turbulent flow in particular. This study estimates the probability distribution of instantaneous turbulent stresses in an RSM from velocity fields obtained using particle image velocimetry. Results show that regions with low average stress still have a substantial probability of having instantaneously high stresses. This explains why low probability breakup is observed at these positions in visualization experiments. Results also show that the probability distribution of instantaneous stresses is approximately lognormal. The results are compared to two commonly used models for how to take the stochastic variations into account: the exponential decay model, and the multifractal emulsification model. It is concluded that both models predict reasonable distributions shapes but underestimate the width of the stress distribution.

  • 67.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    Arlov, Dragana
    Tetra Pak Proc Syst AB.
    Carlsson, Fredrik
    FS Dynam AB.
    Innings, Fredrik
    Tetra Pak Proc Syst AB & Lund University .
    Hydrodynamic difference between inline and batch operation of a rotor-stator mixer head: a CFD approach2017Inngår i: Canadian Journal of Chemical Engineering, ISSN 0008-4034, E-ISSN 1939-019X, Vol. 95, nr 4, s. 806-816Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rotor-stator mixers (RSMs) can be operated in either batch or inline mode. When operating a rotor-stator geometry in batch mode, it typically experiences an order of magnitude higher volumetric flow through the stator than in inline mode. This is expected to cause differences in the flow and turbulence in the rotor-stator region. This study uses computational fluid dynamics (CFD) to study the hydrodynamic differences in and near the stator hole as a function of volumetric flow rates between those experienced in inline and batch modes of operation. It is concluded that both radial flow profiles and turbulent kinetic energy across a range of rotor speeds and flow rates can be described by a velocity ratio: average tangential fluid velocity in the stator hole divided by the rotor tip speed. Moreover, the position where dissipation of turbulent kinetic energy takes place-and hence the effective region of dispersion or mixing-differs between the two modes of operation. The relative importance of the two regions can be described in terms of the velocity ratio and the transition can be predicted based on the relative power input due to rotational and pumping power of the mixer. This study provides a starting point for understanding differences between emulsification efficiency between inline and batch modes of operation with relevance for both equipment design and process scale-up.

  • 68.
    Håkansson, Andreas
    et al.
    Lunds universitet.
    Fuchs, Laszlo
    Innings, Fredrik
    Revstedt, Johan
    Bergenståhl, Björn
    Trägårdh, Christian
    Visual observations and acoustic measurements of cavitation in an experimental model of a high-pressure homogenizer2010Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 100, nr 3, s. 504-513Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cavitation is common in high-pressure homogenizers, and has severe negative effects such as noise and mechanical wear, but may also have a beneficial effect in promoting fragmentation. Greater knowledge concerning cavitation in the homogenizer valve is thus important in optimizing the design and utilization of emulsification equipment. The aim of this study was to locate the region of cavitation and to study its dependence on operating conditions. The cavitation in a model of a high-pressure homogenizer is examined in detail. A visualization technique, based on the scattering of light from cavitation bubbles in the flow, has been developed, tested and compared to acoustical measurements. Intense light scattering was observed in the gap of the valve, indicating cavitation bubble growth as well as collapse inside the gap. The scattering intensity increased with increasing inlet pressure and decreased with increasing back pressure.

  • 69.
    Håkansson, Andreas
    et al.
    Lundsuniversitet.
    Fuchs, Laszlo
    Innings, Fredrik
    Revstedt, Johan
    Trägårdh, Christian
    Bergenståhl, Björn
    Experimental validation of k–e RANS-CFD on a high-pressure homogenizer valve2012Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 71, s. 264-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Since the emulsification in the High-Pressure Homogenizer (HPH) is controlled by hydrodynamic forces, the turbulent flow field in the valve region is of significant interest. Computational Fluid Dynamics (CFD) simulations have been used for this in many studies. However, there are reasons to question if the utilized turbulence models, with their inherent assumptions and simplifications, could accurately describe the influential aspects of the flow.

    This study compares CFD simulations using the methods from previous studies with experimental measurements in a model HPH valve. The results show that the region upstream of the gap can be described accurately regardless of turbulence model and that the gap region can be captured by using one of the more refined k−ε models. None of the studied turbulence models were able to describe the details of the highly turbulent region downstream of the gap. The obtained results are also discussed in relation to generalizability and limitations in using CFD simulations for understanding the emulsification in the HPH.

  • 70.
    Håkansson, Andreas
    et al.
    Lund University, Department of Food Technology, Engineering and Nutrition.
    Fuchs, Laszlo
    Lund University, Department of Energy Sciences.
    Innings, Fredrik
    Tetra Pak Processing Systems, Lund.
    Revstedt, Johan
    Lund University, Department of Energy Sciences.
    Trägårdh, Christian
    Lund University, Department of Food Technology, Engineering and Nutrition.
    Bergenståhl, Björn
    Lund University, Department of Food Technology, Engineering and Nutrition.
    High resolution experimental measurement of turbulent flow field in a highpressure homogenizer model and its implications on turbulentdrop fragmentation2011Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 66, nr 8, s. 1790-1801Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Particle image velocimetry is performed on a model of a high pressure homogenizer, scaled for qualitative similarity of the one phase turbulent flow field in a production scale homogenizer. Flow fields in gap entrance, gap and gap outlet chamber are obtained with high resolution. The measurements show gap flow development and formation of a turbulent wall adherent jet when exiting into the outlet chamber. Turbulent kinetic energy spectra show how the turbulent energy available for fragmentation is transported over distance along the jet centre axis.

    The high resolution images are also used together with a Kolmogorov-Hinze theory framework for discussing drop fragmentation together with a direct evaluation of disruptive stresses from measurements. For the turbulent inertial mechanism large drops experience high fragmenting force close to eight gap heights downstream of the gap exit where as this occurs closer to 20 gap heights for smaller drops. The turbulent viscous mechanism is most efficient at a downstream distance of eight gap heights into the outlet chamber for all drops sizes.

  • 71.
    Håkansson, Andreas
    et al.
    Lund University.
    Fuchs, Laszlo
    Lund University.
    Innings, Fredrik
    Tetra Pak Processing Systems.
    Revstedt, Johan
    Lund University.
    Trägårdh, Christian
    Lund University.
    Bergenståhl, Björn
    Lund University.
    Velocity measurements of turbulent two-phase flow in a high-pressure homogenizer model2013Inngår i: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 200, nr 1, s. 93-114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of disperse phase volume fraction on the turbulence in a scale model of a high-pressure homogenizer was studied experimentally. Velocity fields of the continuous phase were measured using particle image velocimetry. Refractive index matching combined with digital filtering enabled measurement with disperse phase present. Geometry and physical properties were carefully scaled in order to ensure turbulent flow and disperse phase modulation comparable to that of a technical high-pressure homogenizer. The results show a widening of the jet downstream of the gap and increased Reynolds stresses in the region of high turbulence intensity. This is consistent with previous experiments under similar conditions. Furthermore, the spectra of turbulent kinetic energy were investigated, indicating that the increase in turbulent kinetic energy is mainly due to an increase in energy of eddies of large length scales.

  • 72.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Praktisk-estetiska ämnen.
    Hounslow, Mike
    Simultaneous determination of fragmentation and coalescence rates during pilot-scale high-pressure homogenization2013Inngår i: Journal of Food Engineering, ISSN 0260-8774, E-ISSN 1873-5770, Vol. 116, nr 1, s. 7-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The emulsification process is primarily determined by the rate of fragmentation and coalescence of emulsion drops. However, there is presently no fast, reliable method for measuring these rates for pilot and production scale high pressure homogenizers.

    In this paper a method for simultaneous estimating fragmentation and coalescence is developed and tested based on the work of Hounslow and Ni (2004). Kernel type as well as rate extraction is performed based on the development of the total number of drops when recirculation an emulsion through a high-pressure homogenizer. The method has many advantages such as not requiring any specialty chemicals or complex analytical equipment. All measurements are made using laser diffraction equipment that is already standard for analyzing the effect of homogenization.

    Experiments show fragmentation and coalescence rates close to that seen in previous studies and the scaling of coalescence rate and fragmentation with homogenizing pressure is in accordance with theory.

  • 73.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap. Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL).
    Innings, Fredrik
    Tetra Pak AB & Lund University.
    The dissipation rate of turbulent kinetic energy and its relation to pumping power in inline rotor-stator mixers2017Inngår i: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 115, s. 46-55Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The theoretical understanding of inline rotor-stator mixer (RSM) efficiency, described in terms of the dissipation rate of turbulent kinetic energy as a function of mixer design and operation, is still poor. As opposed to the correlations for shaft power draw, where a substantial amount of experimental support for the suggested correlations exists, the previously suggested correlations for the dissipation rate of turbulent kinetic energy have not been experimentally validated based on primary hydrodynamic measurements. This study uses energy conservation to reformulate the previously suggested dissipation rate correlations in terms of pumping power which allows for empirical testing. The dimensionless pumping power of three investigated geometrically dissimilar inline RSMs were found to be qualitatively similar to that of centrifugal pumps and decrease linearly with the inline RSM flow number. The previously suggested models for turbulent dissipation in inline RSMs are inconsistent with this observation. Using this reformulation approach, the previously suggested correlation for power-draw is extended to a correlation for dissipation. A new model is suggested based on conservation of energy and angular momentum, and the empiric pumping power relationship. The new model compares well to CFD simulations of total dissiaption and show reasonable agreement to emulsification drop size scaling.

  • 74.
    Håkansson, Andreas
    et al.
    Lunds universitet.
    Innings, Fredrik
    Revstedt, Johan
    Trägårdh, Christian
    Bergenståhl, Björn
    Estimation of turbulent fragmenting forces in a high-pressure homogenizer from computational fluid dynamics2012Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 75, s. 309-317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to find models for turbulent fragmenting forces in the high-pressure homogeniser from data available in Computational Fluid Dynamics (CFD) simulations with Reynolds Averaged Navier Stokes (RANS) turbulence models. In addition to the more common RANS k–ε turbulence models, a Multi-scale k–ε model was tested since experimental investigations of the geometry imply large differences in behaviour between turbulent eddies of different length-scales.

    Empiric models for the driving hydrodynamic factors for turbulent fragmentation using the extra information given by multi-scale simulations were developed. These models are shown to give a more reasonable approximation of local fragmentation than models based on the previously used RANS k–ε models when comparing to hydrodynamic measurements in an experimental model.

  • 75.
    Håkansson, Andreas
    et al.
    Lund University.
    Innings, Fredrik
    Tetra Pak Processing Systems.
    Trägårdh, Christian
    Lund University.
    Bergenståhl, Björn
    Lund University.
    A high-pressure homogenization emulsification model: improved emulsifier transport and hydrodynamic coupling2013Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 91, s. 44-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high-pressure homogenizer emulsification modelling framework by Håkansson et al. (2009a, Chemical Engineering Science 64, 2915–2925; 2009b. Food Hydrocolloids 23, 1177–1183), is further developed in this study. The model, including the simultaneous fragmentation of drops, coalescence of drops and kinetic adsorption of macromolecular emulsifiers, is improved with regard to two points. First, the transport of adsorbed emulsifier between drops of different sizes due to the fragmentation and coalescence of drops, is included using bivariate population balances. Second, the coupling of hydrodynamics to the emulsification model is improved using information from recent hydrodynamic investigations. The proposed framework is exemplified using a set of physically reasonable kernels and a production scale high-pressure homogenizer geometry, showing realistic emulsification results.

  • 76.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Praktisk-estetiska ämnen. Lunds universitet.
    Magnusson, Emma
    Bergenståhl, Björn
    Nilsson, Lars
    Hydrodynamic radius determination with asymmetrical flow field-flow fractionation using decaying cross-flows: Part I. A theoretical approach2012Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1253, s. 120-126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct determination of hydrodynamic radius from retention time is an advantage of the field-flow fractionation techniques. However, this is not always completely straight forward since non-idealities exist and assumptions have been made in deriving the retention equations. In this study we investigate the effect on accuracy from two factors: (1) level of sophistication of the equations used to determine channel height from a calibration experiment and (2) the influence of secondary relaxation on the accuracy of hydrodynamic radius determination. A new improved technique for estimating the channel height from calibration experiments is suggested. It is concluded that severe systematic error can arise if the most common channel height equations are used and an alternative more rigorous approach is described. For secondary relaxation it is concluded that this effect increases with the cross-flow decay rate. The secondary relaxation effect is quantified for different conditions. This is part one of two. In the second part the determination of hydrodynamic radius are evaluated experimentally under similar conditions.

  • 77.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    Mortensen, Hans Henrik
    Tetra Pak.
    Andersson, Ronnie
    Chalmers University.
    Innings, Fredrik
    Tetra Pak & Lund University.
    Experimental investigations of turbulent fragmenting stresses in a rotor stator mixer. Part 1.: estimation of turbulent stresses and comparison to breakup visualizations2017Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 171, s. 625-637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite large industrial relevance, the relation between rotor-stator geometry, hydrodynamics and drop breakup is poorly understood, partly since no methods for measuring the fragmenting stresses acting on drops have been established. This study attempts to bridge this gap by developing, applying and evaluating two approaches for estimating local turbulent stresses based on particle image velocimetry data: namely one traditional but indirect approach based on the dissipation rate of turbulent kinetic energy, and another more direct approach based on the spatial turbulent spectrum that has proven useful in other high-intensity emulsification processing. The approaches are evaluated in terms of validity of underlying assumptions, how they compare to breakup visualizations in the same geometry and with regard to the reliability of primary measurables. Results show three consistent regions of high stress in the rotor-stator region: in a plume extending into the stator-hole from the trailing edge, in the shear layers of the jet exiting the hole and in the macroscopic flow structure formed after the rotor blocks a stator hole. Following, a drop travelling along an average velocity flow field, the measurement predict disrupting stresses exceeding the stabilizing stress at the stator hole exit, at approximately the same position where drop breakup is observed in breakup visualizations. Both methods are therefore able to predict the most likely breakup positions. It is also concluded that both methods have limitations, and that average stress alone cannot describe all aspects of the fragmentation process in rotor-stator mixers. (C) 2017 Elsevier Ltd. All rights reserved.

  • 78.
    Håkansson, Andreas
    et al.
    Lund University.
    Trägårdh, Christian
    Lund University.
    Bergenståhl, Björn
    Lund University.
    A method for estimating effective coalescence rates during emulsification from oil transfer experiments2012Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 374, nr 1, s. 25-33Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Oil Transfer Technique (OTT) was developed by Taisne et al. [1] to measure coalescence during emulsification and has been applied since in several studies. One of the main drawbacks of this technique is that it only gives a qualitative measure of coalescence. This paper proposes a new evaluation method of OTT experimental results for estimating qualitative coalescence rates, e.g. for investigating the scaling of coalescence with emulsification parameters (such as homogenizing pressure, and emulsifier concentration).

    The method is based on comparison with simulated OTT experiments using bivariate Population Balance Equation models. Simulations have been performed under a wide variety of conditions in order to investigate the influence of assumptions on coalescence and fragmentation kernels. These investigations show that the scaling of coalescence rates could be determined accurately when the scaling of efficient residence time of drops in the active region of homogenization is known. The proposed evaluation method is also exemplified by analyzing OTT data from two previously published studies.

  • 79.
    Håkansson, Andreas
    et al.
    Lunds universitet.
    Trägårdh, Christian
    Bergenståhl, Björn
    Dynamic simulation of emulsion formation in a high pressure homogenizer2009Inngår i: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 64, nr 12, s. 2915-2925Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simulation model for emulsification in high pressure homogenization (HPH), based on a population balance approach, is developed assuming it to be controlled by three simultaneous processes; fragmentation, coalescence and adsorption of a macromolecular emulsifier. The aim is to investigate the implications of adding a set of models together; studying the effects of dynamics, size effects and process interactions.

    For fragmentation, turbulent inertial and turbulent viscous forces are included using a dynamic model based on the Weber and Capillary number. It was extended to include a deformation time scale.

    The rate of adsorption and coalescence is assumed to be controlled by the collision rate of macromolecular stabilizer and bare interface, modeled using convective and diffusive transport in turbulent flow.

    By comparing simulation results to general trends found in the literature, it can be concluded that the models can reproduce the general HPH process well. By dividing the active region of emulsification in the homogenizing valve into discrete steps, the dynamic process could also be examined, indicating the homogenization process being composed of three stages with coalescence predominantly found in the last one.

  • 80.
    Håkansson, Andreas
    et al.
    Lunds universitet.
    Trägårdh, Christian
    Bergenståhl, Björn
    Studying the effects of adsorption, recoalescence and fragmentation in a high pressure homogenizer using a dynamic simulation model2009Inngår i: Food Hydrocolloids, ISSN 0268-005X, E-ISSN 1873-7137, Vol. 23, s. 1177-1183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The emulsification in a high pressure homogenizer was studied using a dynamic simulation model based on the population balance equation. The model includes fragmentation, recoalescence and adsorption of macromolecular emulsifier and uses a simple flow model in order to link the hydrodynamics in the homogenizer to the three physical processes mentioned above.

    A computer model offers an interesting opportunity to study the effect of model assumptions on the overall outcome of the process. The computer model is also an interesting complement to experiments in this case since internal measurements in the active region of homogenization are very hard to carry out, due to small scales and high forces, and information on the spatial position of the different processes is of great importance in design.

    Based on a set of assumptions, mainly that the turbulent jet responsible for break-up can be described by a one dimensional model and that the macromolecular emulsifiers hindrance of recoalescence can be described by a wall like repulsion, it is shown that the active region of homogenization can be divided into two zones; a narrow zone with fast fragmentation and nearly no recoalescence in the most intense part of the region followed by a recoalescence zone as drop–drop interactions starts to dominate with decreasing turbulence intensity. The effect of operating parameters is seen to be close to the ones found from experiment.

    The results are discussed in relation to a flow field obtained by a simplistic CFD and assumptions made about hydrodynamics and emulsifier behavior.

  • 81.
    Håkansson, Andreas
    et al.
    Department of Food Technology, Engineering and Nutrition, Faculty of Engineering LTH, Lund University.
    Ulmius, Matilda
    Biomedical Nutrition, Pure and Applied Biochemistry, Faculty of Engineering LTH, Lund University.
    Nilsson, Lars
    Department of Food Technology, Engineering and Nutrition, Faculty of Engineering LTH, Lund University.
    Asymmetrical flow field-flow fractionation enables the characterization of molecular and supramolecular properties of cereal beta-glucan dispersions2012Inngår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 87, nr 1, s. 518-523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we study the properties of molecular and supra molecular species in cereal beta-glucan solutions/dispersions by the utilization of asymmetrical flow field-flow fractionation coupled to multi-angle light scattering and refractive index (AsFIFFF-MALS-RI) detectors. The samples were purified barley and oat beta-glucans which were dissolved in aqueous solution using either mild conditions or more harsh treatments with alkali. Dissolution in 0.5 M NaOH was not sufficient to eliminate aggregated structures in barley beta-glucan. The results in this paper show how distinction can possibly be made between molecular and supra molecular species using scaling approaches and conformational parameters obtained from AsFIFFF-MALS-RI over the entire size distribution. Small species in the barley beta-glucan samples display properties ranging from elongated conformation to random coil conformation. Aggregates have low apparent densities and a swollen micro gel structure. Oat beta-glucan displays no properties that can be attributed to a molecularly dissolved beta-glucan showing that dissolution was incomplete. The aggregate properties analyzed were similar between oat and barley beta-glucan.

  • 82.
    Håkansson, Andreas
    et al.
    Högskolan Kristianstad, Forskningsmiljön Food and Meals in Everyday Life (MEAL). Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Mat- och måltidsvetenskap.
    Zishan, Chaudhry
    Tetra Pak Processing Systems AB.
    Fredrik, Innings
    Tetra Pak Processing Systems AB.
    Model emulsions to study the mechanism of industrial mayonnaise emulsification2016Inngår i: Food and Bioproducts Processing, ISSN 0960-3085, E-ISSN 1744-3571, Vol. 98, s. 189-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mechanistic understanding of industrial food-emulsification is necessary for optimal operation and design. Industrial mayonnaise production is yet poorly understood, partly due to a lack of experimental data and partly due to the complexity of the product.

    This study suggests a systematic method for building mechanistic insight, by investigating successively more complex model emulsions in industrial rotor–stator mixers, comparing to idealized theories identifying points of departure. As a first step, a high volume fraction (>50%) and high viscosity (>100 mPa s) model emulsion with a non-ionic surfactant acting as emulsifier is investigated in two industrial-scale mixers (one batch and one continuous inline mixer) at varying rotor tip-speeds.

    The resulting drop diameter to rotor tip-speed scaling suggest turbulent viscous fragmentation of the model emulsion in both mixers despite the high volume fraction of disperse phase which could be expected to lead to significant non-idealities such as extensive coalescence and concentration effect-dominated fragmentation. If the other non-idealities (e.g. egg yolk emulsifying system and non-Newtonian rheology) would not influence the emulsification, this suggests the same mechanism for mayonnaise emulsification. An outline for continued work on successively more complex model-emulsions is discussed in order to further enhance understanding.

  • 83.
    Håkansson, Göran
    Högskolan Kristianstad, Institutionen för ekonomi.
    Databasutformning för ekonomiska tillämpningar2001Bok (Annet (populærvitenskap, debatt, mm))
  • 84.
    Islam, Toriqul
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Khan, Monir Ahmed
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    iDream2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This degree project deals with a website that can help people to save, share and utilize their dreams and wishes. Communication is the most important part of our social life and iDream is

    programmed to take dreams and wishes to a social level by creating better understanding

    between people through dreams and wishes.

    It allows people to create dream/wish blogs, read others blogs through a gallery, subscribing to other people’s blogs and getting automatic feed from subscribed blogs. Popular blogs become a community which can maximize the effect of the dream or wish and finally an option to add family members and see their activities.

    Joomla CMS is the core of the website. The project also includes research on efficient Joomla component creation and 3D website design according to Human-computer interaction principles.

  • 85.
    Jin, Shasha
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Gaoding, Ningcheng
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Signal processing using the wavelet transform and the Karhunen-Loeve transform2012Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This degree project deals with Wavelet transform and Karhunen-Loeve transform. Through the mathematic description to understand and simulation to investigate the denoise ability of WT and the de-correlation ability of KLT. Mainly prove that the new algorithm which is the joint of these two algorithms is feasible.

  • 86.
    Johansson, Michael
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap.
    Wetterstrand, Martin
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap.
    Lundstedt, Rikard
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap.
    E-participation – engaged participation2011Inngår i: Proceedings of ISEA2011 Istanbul, 2011Konferansepaper (Annet vitenskapelig)
  • 87.
    Jovanovic, Aleksandar
    et al.
    Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för datavetenskap.
    Vu, Cong
    Högskolan Kristianstad, Fakulteten för naturvetenskap, Avdelningen för datavetenskap.
    Triggningskriterier i triggningsmodul för trådlösa dataloggern DL141E2018Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [sv]

    Dataloggern DL141E möjliggör kontinuerlig loggnig av mätdata från sensorer på upp till 30k sampel/s, som vidare kan överföras till mobiltelefoner via trådlös kommunikation. Detta är dock för stora datamängder per tidsenhet för mobiltelefoner som är tekniskt begränsade. Därför önskas bara relevant mätdata för att reducerar denna onödiga datamängd. I denna studie föreslås ett tillvägagångssätt där enspecifik mindre samling av diskreta försampel loggas i tur och ordning. Varje samling signalbehandlas genom att ställas mot fördefinierade triggningskriterier för att trigga loggning av en stor uppsättning av sampel på bara intressanta signalavvikelser. Dessa triggningskriterier är en särskild nivåöverskridning och signalriktning i kombination med ett antal sampel i följd. Studien förser en granskning av hur signalberäkningsmetoden ”Lebesgue sampling” kan tillämpas med kriterierna för god träffsäkerhet och en skälig beräkningstid i mobiltelefoner. Detta beaktas med dataloggerns vanligaste signaltyper puls och ramp i en miljö där småbrus och transienter förekommer. Träffsäkerheten och beräkningsbördan beaktasför att bedöma Lebesgue metodens effektivitet och antal nödvändiga försampel per uppsättning. Implementeringen görs i Java Android plattform och integreras därefter i en digital triggningsmodul med Graphical User Interface (GUI).

  • 88.
    Jun, Lu
    et al.
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    Song, Zhang
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    E-health web application framework and platform based on the cloud technology2013Independent thesis Advanced level (degree of Master (One Year)), 10 poäng / 15 hpOppgave
    Abstract [en]

    This project deals with E-health web application framework, cloud platform and responsive web design which aim to adjust the presentation on mobile devices. This work presents the whole development process of the self-care management web-app framework which provides instructive supports for future other E-health field application. The report consists of the following main parts: analysis, design and implementation, and evaluation. Literature review and internet search are main methods for making an investigation on existing systems and related works. A prototype is developed by using .Net, CSS3, Java script and HTML5 technologies. The system test and evaluation is made to show the system’s usability.

  • 89.
    Karlsson, Jonny
    Högskolan Kristianstad, Sektionen för lärande och miljö.
    Desinfektion av kommunalt dricksvatten vid långa distributionsvägar och råvatten från sjön Vättern2011Independent thesis Basic level (university diploma), 5 poäng / 7,5 hpOppgave
    Abstract [sv]

    Rapporten är ett resultat av en undersökning som initierades av att man i Motala kommun ville sluta använda sig av kloramin för dricksvattendesinfektionen vid sitt ytvattenverk i Råssnäs. Man ville utesluta ammoniak vid dricksvattenframställningen och övergå till att enbart desinficera med hypoklorit. Råssnäs tar sitt råvatten från Vättern och det färdiga vattnet distribueras sedan upp till 30 km från verket. I samband med att man ville göra förändringen var man intresserad av att veta hur man utför desinfektion vid andra vattenverk med liknande förutsättningar d.v.s. råvatten från Vättern och långa distributionsvägar. Med utgångspunkt från dessa förutsättningar valdes kommunerna Askersund och Jönköping samt kommunalförbundet Skaraborgsvatten ut för att tillfrågas om hur man där arbetar med sin dricksvattendesinfektion. Undersökningen begränsas av att endast tre kommunala aktörer deltog men dessa bedömdes vara de som bäst uppfyllde de angivna förutsättningarna. Från de avgivna svaren kan man dra slutsatsen att båda metoderna, desinfektion med kloramin eller enbart hypoklorit, används och tycks fungera bra. Problem uppstår i första hand under den varma delen av året då vattnet i ledningarna värms upp vilket kan främja den mikrobiella tillväxten. Åtgärden blir i sådana fall i första hand att utföra stödklorering ute på nätet. Desinfektions metoderna mella kommunerna/kommunalförbundet varierar. I Askersund doseras endast hypoklorit och man har inga erfarenheter från andra metoder. I Jönköping har man i sitt största verk nyligen övergått från kloramin till enbart hypoklorit och fick i samband med detta under den första tiden många klagomål på dålig smak och lukt hos dricksvattnet. Problemen avtog efterhand och efter ett halvår hade klagomålen upphört. Man tror att störningarna uppstod då biofilmen i ledningsnätet regerade på den kraftigare kloreringen för att därefter gradvis anpassa sig till nya förhållanden. Skaraborgsvatten använder sig av både förklorering med hypoklorit samt efterklorering med klor och ammoniak. Halva klormängden bildar då kloramin med ammoniaken medan den andra halvan reagerar med en momentan desinficerande effekt. De erhållna svaren visar också att UV-ljus används, eller planeras att användas, och byggs ut inom verksamheten hos alla de tre tillfrågade dricksvattenproducenterna. Rådet till Motala blir att man provar att avsluta ammoniakdoseringen och övergår till enbart hypoklorit. Dock bör man under en tid efter förändringen, för att undvika att störningar uppstår, utöka kontrollen av vattnet genom extra provtagning på lämpliga platser ute i ledningsnätet och då framförallt efter sommaren då vattnet är som varmast. Det är även lämpligt att förbereda för att kunna stödklorera, förslagsvis ute vid tryckstegringsstaioner, samt att ytterligare bygga ut användningen av UV-ljus ute på nätet vid t.ex. tryckstegringar och reservoarer.

  • 90.
    Khatibi, Erinc
    Högskolan Kristianstad, Sektionen för Hälsa och Samhälle.
    En experimentell studie av vulkaniseringstidens och vulkaniseringshastighetens påverkan av värmeväxlarpackningar2011Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    A two-factor design of experiments done on GGAB for the identification of two selected factors influence on the length of the scattering of heat exchanger gaskets. The work consists of four parts: study, choice of survey method, the performance of investigation and analysis of the results. Chosen factors on the study are considered to be the most effecting of the length distribution of seals during the production of GGAB. The study is the first of its kind both in GGAB and in the rubber industry and has an experimental nature.

  • 91.
    Kihl, Maria
    et al.
    Lunds Universitet.
    Larsson, Robin
    Lunds Universitet.
    Unnervik, Niclas
    Lunds Universitet.
    Haberkamm, Jolina
    Lunds Universitet.
    Arvidsson, Åke
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap. Ericsson AB.
    Aurelius, Andreas
    Acreo.
    Analysis of Facebook content demand patterns2014Inngår i: SaCoNet 2014 / [ed] Said Hoceini, Guang-Jie Ren och Eva Marín-Tordera, IEEE Communications Society, 2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Data volumes in communication networks increase rapidly. Further, usage of social network applications is very wide spread among users, and among these applications, Facebook is the most popular. In this paper, we analyse user demands patterns and content popularity of Facebook generated traffic. The data comes from residential users in two metropolitan access networks in Sweden, and we analyse more than 17 million images downloaded by almost 16,000 Facebook users. We show that the distributions of image popularity and user activity may be described by Zipf distributions which is favourable for many types of caching. We also show that Facebook activity is more evenly spread over the day, compared to more defined peak hours of general Internet usage. Looking at content life time, we show that profile pictures have a relatively constant popularity while for other images there is an initial, short peak of demand, followed by a longer period of significantly lower and quite stable demand. These findings are useful for designing network andQoE optimisation solutions, such as predictive pre-fetching, proxy caching and delay tolerant networking.

  • 92.
    Kreuger, Per
    et al.
    SICS.
    Gillblad, Daniel
    SICS.
    Arvidsson, Åke
    Högskolan Kristianstad, Sektionen för hälsa och samhälle, Avdelningen för Design och datavetenskap. Ericsson AB.
    zCap: a zero configuration adaptive paging and mobility management mechanism2013Inngår i: International Journal of Network Management, ISSN 1055-7148, E-ISSN 1099-1190, Vol. 23, nr 4, s. 235-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Today, cellular networks rely on fixed collections of cells (tracking areas) for user equipment localisation. Locating users within these areas involves broadcast search (paging), which consumes radio bandwidth but reduces the user equipment signalling required for mobility management. Tracking areas are today manually configured, hard to adapt to local mobility and influence the load on several key resources in the network. We propose a decentralised and self-adaptive approach to mobility management based on a probabilistic model of local mobility. By estimating the parameters of this model from observations of user mobility collected online, we obtain a dynamic model from which we construct local neighbourhoods of cells where we are most likely to locate user equipment. We propose to replace the static tracking areas of current systems with neighbourhoods local to each cell. The model is also used to derive a multi-phase paging scheme, where the division of neighbourhood cells into consecutive phases balances response times and paging cost. The complete mechanism requires no manual tracking area configuration and performs localisation efficiently in terms of signalling and response times. Detailed simulations show that significant potential gains in localisation efficiency are possible while eliminating manual configuration of mobility management parameters. Variants of the proposal can be implemented within current (LTE) standards.

  • 93.
    Kreuger, Per
    et al.
    SICS.
    Gillblad, Daniel
    SICS.
    Arvidsson, Åke
    Ericsson AB.
    Zero configuration adaptive paging (zCap)2012Inngår i: VTC Fall 2012 / [ed] Jean-Yves Chouinard, Fabrice Labeau och Alex Stephenne, IEEE Communications Society, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected online using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page

  • 94.
    Krznaric, Anton
    Högskolan Kristianstad, Sektionen för hälsa och samhälle.
    License Management for EBITool2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This degree project deals with license management for EBITool. It´s about providing protection and monitoring for a Java Application via a license server, and the construction of it. An analysis that discusses the approach and other possible courses of action is also included. Additionally, it covers a discussion of a prototype implementation of the model solution from the analysis.

    The prototype is a Java EE application that deploys to JBoss AS7. It´s developed using the JBoss Developer Studio 5.0.0, an Eclipse IDE with JBoss Tools preinstalled. It exposes web services to Java Applications through SOAP via JAX-WS. Using Hibernate, the web service Enterprise Java Beans get access to a PostgreSQL 9.1 database via entity classes mapped to the database through the Java Persistence API.

  • 95.
    Lacoursière, Jean O.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Working together making Hoi An a green city - The CITYBLUES++ research platform...: turning climate adapted EcoCity development into action and business opportunities2013Konferansepaper (Annet vitenskapelig)
  • 96.
    Lacoursière, Jean O.
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Vought, Lena B. M.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Creating citywide water-energy-food nexus opportunities: FSM as driving force2014Inngår i: From faecal sludge to fuel: safe sanitation with business opportunities (workshop), 2014Konferansepaper (Annet vitenskapelig)
  • 97.
    Lacoursière, Jean O.
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Vought, Lena B. M.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Measuring residence time distribution in a vegetated pond2015Konferansepaper (Annet vitenskapelig)
  • 98.
    Lacoursière, Jean O.
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Vought, Lena B. M.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    The challenges of keeping floodplains and wetlands in rapidly growing cities: lessons learnt from 24 years of observing Vientiane, Lao PDR2014Konferansepaper (Annet vitenskapelig)
  • 99.
    Lacoursière, Jean O.
    et al.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Vought, Lena B. M.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Toilets need allies - breaking down silo thinking for decentralized sanitation2015Konferansepaper (Annet vitenskapelig)
  • 100.
    Larsson, Gustav
    et al.
    Lund University.
    Sahlén, Jakob
    Lund University.
    Mårtensson, Lennart
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Khanal, Sanjay Nath
    Nepal.
    A case study of municipal solid waste in Nepal compared to the situation in the European Union and Sweden2010Inngår i: Proceedings Linnaeus ECO-TECH´10, Kalmar,  Sweden, Nov 22-24, 2010, 2010, s. 429-438Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Nepal, situated in the Himalayan belt has a rapidly growing population together with high

    urbanisation rate. These factors are currently causing problems connected to municipal solid

    waste (MSW). E.g. leakage of hazardous substances to soil and surrounding aquatic systems,

    spread of odour and naturally unfamiliar materials to natural biotopes, all of which generate

    environmental damage and health problems. There are certain differences in waste generation

    and waste composition between urban areas of Nepal. In order to retrieve a broad picture of

    the current waste management situation, three population differentiated municipalities in

    different areas of the country were investigated. Studies of the MSW regarding composition

    and generation were conducted. Moreover, waste management in Nepal was compared with

    the basic waste management in the European Union (EU) and Sweden. Landfill sites (LFS) in

    Ghorahi Municipality, Pokhara Sub-metropolitan City and Kathmandu Metropolitan City

    were studied. Our studies show differences in waste composition, generation and management

    between the three locations. The differences are somewhat interconnected with population

    size and tourism. Cities with higher population and more tourism tend to have a higher

    generation and more diverse MSW. Nevertheless, the urban areas of Nepal are very much in

    need of a more structured waste management system, a system more alike the waste

    management of EU. Apart from structural problems, there are attitude and behavioural issues

    that needs to be dealt with. Further studies regarding social patterns, attitude and behaviour,

    as well as the economic flow of MSW, needs to be conducted in order to retrieve an even

    broader picture and understand important underlying issues.

1234 51 - 100 of 171
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