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  • 18151.
    Yang, Tingxiao
    University of Gävle, Faculty of Engineering and Sustainable Development.
    The Algorithms of Speech Recognition: programming and simulating in MATLAB2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this thesis work is to investigate the algorithms of speech recognition. The author programmed and simulated the designed systems for algorithms of speech recognition in MATLAB. There are two systems designed in this thesis. One is based on the shape information of the cross-correlation plotting. The other one is to use the Wiener Filter to realize the speech recognition. The simulations of the programmed systems in MATLAB are accomplished by using the microphone to record the speaking words. After running the program in MATLAB, MATLAB will ask people to record the words three times. The first and second recorded words are different words which will be used as the reference signals in the designed systems. The third recorded word is the same word as the one of the first two recorded words. After recording words, the words will become the signals’ information which will be sampled and stored in MATLAB. Then MATLAB should be able to give the judgment that which word is recorded at the third time compared with the first two reference words according to the algorithms programmed in MATLAB. The author invited different people from different countries to test the designed systems. The results of simulations for both designed systems show that the designed systems both work well when the first two reference recordings and the third time recording are recorded from the same person. But the designed systems all have the defects when the first two reference recordings and the third time recording are recorded from the different people. However, if the testing environment is quiet enough and the speaker is the same person for three time recordings, the successful probability of the speech recognition is approach to 100%. Thus, the designed systems actually work well for the basical speech recognition.

  • 18152.
    Yang, Tingxiao
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Zenteno, Efrain
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics. Royal Institute of Technology, KTH. Signal Processing Laboratory, Stockholm, Sweden .
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Measurement imperfections impact on the performance of digitally predistorted power amplifiers2014In: 2014 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) Proceedings, 2014, p. 230-233Conference paper (Refereed)
    Abstract [en]

    This paper presents an study of the impact of analog to digital converter (ADC) impairments on digital pre-distortion (DPD) techniques when applied to RF power amplifiers (PA). The DPD technique is described by a memory polynomial model while the ADC impairments are modeled by quantization noise, random jitter, and the integral nonlinearity (INL); thus, summarizing systematic and random nature of ADC imperfect measurements. It is observed that increased jitter will have a negative impact on the modeling but not so much on the output performance from the pre-distorted PA. Moreover, the ENOB can be used as metric for both the quantization noise and integral nonlinearity and there is a value of ENOB which, if exceeded, do not improve the DPD performance; in this paper it is about 8 bits.

  • 18153.
    Yang, Xinping
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Navigating/Browsing In 3D with WebGL2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The use of the internet has become very important in our daily life. At present, web pages are mostly shown as two-dimensional content. Three-dimensional web pages are rarely seen on the Internet. In this thesis, the main task is to develop an interactive 3D (three-dimensional) web prototype for the company Interactive TV Arena. This three-dimensional web prototype will be integrated to the OSIA (open server interface architecture) project which is a project in Interactive TV Arena. In order to implement the prototype, three main tasks were addressed: The first is creating the framework of the prototype with XML files. Secondly, a parser framework was built with JavaScript classes. The third task is to render the prototype with WebGL in real time. The prototype can be used to develop the 3D web pages in modern browsers. This thesis has completed most of the aforementioned tasks and the result of it can be used to develop some simple 3D web pages.

  • 18154.
    Yang, Yanqing
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Segmentation of digital urban maps into region2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With the rapid development of urban areas, the areas which may be used for new buildings are becoming smaller and smaller. Cities are divided into different areas based on the activities in these areas, a process called functional zoning. Depending on the functional zone, different kinds of buildings may be built. This thesis consists of two parts. The first part discusses segmentation of functional zones and image pre-processing such as morphological closing. The other part is about finding suitable building areas in Google maps. The thesis also presents an algorithm, implemented in Matlab, which provides a simple and efficient way of finding suitable building areas using Google maps.

  • 18155.
    Yang, Yuchen
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Liang, Jieqiong
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energy Audit for the Gävle University Library2013Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
  • 18156.
    Yangqing, Sun
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Ling, Zou
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Patients’ experiences of living with type Ⅱ diabetes: A descriptive literature review2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18157.
    Yanhan, Jin
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences.
    Yilan, Ling
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences.
    Women’s experience of postpartum depression: : A descriptive literature review2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18158.
    Yao, Li
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    ENERGY AUDIT OF HIG STUDENT HOSTEL2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays in the world, energy usage effectiveness has always been an issue which blocks people’s development. How to effectively use the energy is becoming more and more important. Energy audit can appraise the energy usage condition of a building, and come up with improvement advices through systematic calculation and analysis the existing problems and reasons for energy wastes, in order to bring the object of effective usage of energy into reality.

    HiG student hostel 23 is situated in Gävle, a coastal city in the east of Sweden. There are three floors in Hostel 23, the first and second floor have 18 single rooms, 4 double rooms and 2 communal kitchens and the third floor is storeroom. The aim of this thesis is to explore indoor climate and energy use for this student hostel and find out the reason of the low temperature inside the room, seeking some ways to improve the thermal comfort inside the building during winter conditions.

    First, collect date from every part in energy balance by measurement and interview with administrator, then calculate and analyze the data. At last, the whole energy balance can be estimated. Through analyzing the whole energy balance, the suggestion is to change the window type and design a new ventilation system operating plan. Through the optimization, energy loss is reduced, and about 10% of the energy is preserved. Besides this, the building infiltration loss is too high through this energy audit; it states there still exists some problems. If these problems can be solved, it will be helpful to keep a good thermal comfort inside the building.

  • 18159.
    Yao, Li
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Liao, Xinyan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energy Audit of HiG Examination Building2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Nowadays, energy is becoming more and more important. With the development of society, the demand of energy is also increasing correspondingly. There is 22% of the total energy which is used in building part. A more effective and sustainable energy system becomes necessary due to increasing energy prices and demand. The aim of this thesis is to make an energy survey of this building, evaluating different sources of energy supply and losses in this building. By evaluating, a better thermal comfort is expectedly achieved when having examinations, and a possible saving method is also expected in order to reduce the cost of this system.

     In this project, the building is located in University of Gävle which is surveyed. It has 2 floors. The first floor is underground as a basement. An examination room is included in the second floor. There are a space heating system and heating recovery system ventilation in this examination building.

    At first step of analysis, the data of construction, ventilation, district heating and hot tap water were arranged by Mr. Magnus. Secondly, an energy balance had been done, and it helped to make energy input and output more clearly. In energy supply part, the solar radiation is 22.4MWh, the internal heat from people is 1.95MWh, the internal heat from equipment is 5.63MWh and district heating is 184MWh. In energy losses part, the transmission loss is 165MWh, the mechanical ventilation loss is 38.3MWh, the infiltration loss is 8.38MWh and the hot tap water is 2.09MWh. Thirdly, results of calculations were analyzed. At last, the optimization methods were given to save energy. The optimization methods were changing type of windows and improving indoor temperature which influenced the transmission loss part. Another method was reducing operating time of the ventilation system.

    Through these optimizing methods, the total energy use is reduced from 214MWh to 179MWh, and district heating is reduced from 184MWh to 149MWh. District heating of this building is supplied by Gävle Energi company, which is able to save 20% cost by these optimizing methods. According to the investment analysis, 19thousand SEK energy is saved per annum.

  • 18160.
    Yao, Tianxiang
    University of Gävle, Faculty of Education and Business Studies, Department of Business and Economic Studies.
    Towards an understanding of Human resource management In Furniture Company    2010Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Aim: With today’s rapid economic development, human resource is the only major success in continuing operations. In fact, my parents are engaged in furniture retail industry in south of China, Guangzhou. In the company’s daily operations, we found a lot of issues about human resource management. Employee’s demission and training, and the negative attitude become major obstacles in the way of our company’s development. Through HRM study, I want to understand what factors affect staff movement behavior and loyalty to the company, in order to deal with the staff situation in the company more efficiently.

    Method: In this thesis, the case study approach was used. Case study research is suitable for explanatory, descriptive and exploratory. Our research chooses two in-depth case studies that base on the interviews with human resource managers. The information that we collect is from qualitative interviews. Through loyalty and movement theory, to identify which factors are affecting staff movement behavior and loyalty to company, as well as analyze how to solute the issue in my family company.

    Result & Conclusions: After discussion and analysis, the study found: high wages is not the only way to retain employees. Money as reward can cost a lot, and it’s impersonal. Workplace, leadership style, enterprise potential, training opportunity and promotion space also can affect employee loyalty. According to Motivator-Hygiene Theory, to establish motivation system, exciting staff’s enthusiasm for the work. Let staff realize that the successes of the company are directly connected to their performances; staff have responsibility for company’s successes. This is a powerful way to keep employee motivated. For company development of long standing, organization should command constantly more new technology. Staff as the work of actors, to learn more work skills is essential. Employees and the company’s desire is the same. Companies focus on their own development, but also to enhance staff capacity. For development of the company, it should give staff more training and promotion opportunities.

    Suggestions for future research: It has to note that the limitation of this study is the small number and the limited scope of interviewees.

    Contribution of the thesis: In this study, I mainly find the solutions that the issues in my family company. After discussion and analysis, I am cognizant of the long-term relationship between staff and organization is important for company development. The rewards for the employee are not just money, but also can be other. That effect and help my family firm staff management.

  • 18161.
    Yao, Xiaobai Angela
    et al.
    Department of Geography, University of Georgia, Athens, USA.
    Huang, Haosheng
    Department of Geography, Universitat Zurich Institut fur Geographie, Zurich, Switzerland.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Krisp, Jukka M.
    University of Augsburg, Augsburg, Germany.
    Representation and analytical models for location-based big data2019In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 33, no 4, p. 707-713Article in journal (Refereed)
  • 18162.
    Yao, Xiaobai
    et al.
    University of Georgia, Athens, United States .
    Jiang, Bin
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för samhällsbyggnad.
    Geospatial modeling of urban environments2009In: Environment and Planning, B: Planning and Design, ISSN 0265-8135, E-ISSN 1472-3417, Vol. 36, no 5, p. 769-771Article in journal (Other academic)
  • 18163. Yao, Xiaobai
    et al.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Liu, Yu
    Madden, Marguerite
    New insights gained from location-based social media data: VSI Preface for the special issue on New insights gained from location-based social media data2016In: Computers, Environment and Urban Systems, ISSN 0198-9715, E-ISSN 1873-7587, Vol. 58Article in journal (Refereed)
    Abstract [en]

    In the era of big data, increasingly sizeable datasets come from social media, particularly location-based social media, in the form that is widely known as user-generated contents. Many social media datasets are made available at the finest spatial and temporal scales. The availability of such data creates unprecedented opportunities for researchers to uncover what were previously hidden in the era of small data. What kinds of new research questions may be addressed with the available social media data? What are the social, ethical, and political implications of the wide use of social media platforms and the availability of such data? This special issue responds to the unique research opportunities and challenges from two broad perspectives. First, it looks at the need to develop new theories and data models for the management and analysis of social media data. Secondly, it advocates innovative acquisition and employment of social media data to enhance our understanding of human activities, social and spatial interactions, or the society as a whole. The inspiration for this special issue was the first ever International Conference on Location-based Social Media (ICLSM) held March 5-7, 2015 in Athens, Georgia, USA that brought together researchers from around the globe to discuss geosocial analysis and modeling of social media data. Geographers, GIScientists and social scientists gathered to report on the unique opportunities of collaboration and insights that can be gained from the analysis of location-based social media data collected from sources such as Facebook and Twitter. Participants shared innovative methods for social media data mining, big data analytics, social network analysis, social media data models and representations, human mobility and patterns of interaction.

  • 18164.
    Yao, Zhilei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development.
    He, Yin
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Sustainable Development at University: comparison of students’ knowledge, awareness and actions2010Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    After the Rio United Nations Conference on Enviroment and Development, the need of sustainable development obtained recognition from the vast majority of countries and organization. Human society entered a new development period. More and more people know about sustainable  development. Education for sustainable development is a concern for the world where university can make a  contribution. Students who are the majority in a university, their knowledge, awarenss and action will play an important role to promote sustainable development.  

    The purpose if this thsis is to study if there is any difference in students' knowledge and awareness on sustainable development in university, based on the comparison betweet freshmen and seniors. Through the comparison, this will explore if students' knowledge and awareness is influence  to their action. This thesis does a literature review to understand deeply about sustainable development and explores students' knowledge, awareness and actions of sustainable development through questionnaire. 

    The analysis of data from the questionnaire indicates that their knowledge and awareness influences their actions. The freshmen and seniors have difference in knowledge and awareness. Knowledge of students on sustainable development appears to have increased slightly during years study. However, as the knowledge increased, there is not much difference in their knowledge and awareness of sustainable development. Based on the different degree of knowledge and awareness, seniors appear to do better than freshmen in their actions.

  • 18165.
    Yassin, Hannan
    et al.
    University of Gävle, Faculty of Education and Business Studies, Department of Business and Economic Studies.
    Björklund, Jessica
    University of Gävle, Faculty of Education and Business Studies, Department of Business and Economic Studies.
    Erfarenheter av budgetlös styrning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattning

    Titel:

    Erfarenheter av budgetlös styrning

    Nivå:

    C-uppsats i ämnet företagsekonomi

    Författare:

    Hannan Yassin och Jessica Björklund

    Handledare:

    Tomas Källquist och Stig Sörling

    Datum:

    2015 - Juni

    Syfte:

    Enligt tidigare forskning är det mer än 30 år sedan debatten kring budgetlös styrning började. En del företag valde då att överge budgeten vilket har lett till erfarenheter av den budgetlösa styrningen i praktiken. Syftet med denna studie är att belysa de erfarenheter av budgetlös styrning som finns med avseende på planering, uppföljning och tidsåtgång.

    Metod:

    Studien har utgått från ett hermeneutiskt perspektiv med en abduktiv ansats. Den teoretiska referensramen har byggts upp genom att sammanställa tidigare forskning och det empiriska materialet har samlats in genom en kvalitativ metod där semi-strukturerade intervjuer genomförts. Den teoretiska referensramen och empirin ställdes sedan mot varandra för hitta likheter och skillnader.

    Resultat & slutsats:

    Studien visar att erfarenheterna kring budgetlös styrning har likheter med tidigare forskning. Dock har vi sett att kritiken mot uppföljning i tidigare forskning om budget inte helt stämmer överens med de erfarenheter vi har tagit del av. Erfarenheterna visar även att den budgetlösa styrningen går att kombinera med en budget beroende på vilka egenskaper det är önskvärt att styrningen ska ha.

    Förslag till fortsatt forskning:

    I vår studie har vi fokuserat på budgetlös styrning men vi har sett att det finns aspekter att undersöka i kombinationen mellan styrningar. Vi anser att framtida forskning kan undersöka hur de olika egenskaperna hos styrningskoncepten är kombinerade eller hur de skulle kunna kombineras.

    Uppsatsens bidrag:

    Efter att ha analyserat erfarenheterna kring budgetlös styrning har vi sett att budgetstyrning och budgetlös styrning inte ska ses som en dikotomi. Studien ger ett mer nyanserat perspektiv av styrmedel jämfört med den ensidiga debatten som pågick för över 30 år sedan.

    Nyckelord:

    Budget, budgetering, budgetlös styrning, ekonomistyrning.

  • 18166.
    Yawli, Angelica
    University of Gävle, Faculty of Education and Business Studies, Department of Educational sciences.
    Högläsning i förskolan: En litteraturstudie om högläsningens möjligheter att bidra till barns språkutveckling och förståelse för tryck2015Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta är en studie vars syfte är att sammanställa aktuell forskning angående högläsning i förskolan och dess möjliga inverkan på barns språkutveckling och förståelse för tryck. Detta har gjorts för att det utifrån läroplanen för förskolan (Skolverket, 2010) kan anses som viktigt för lärare i förskolan att få kunskap om ämnet för att på bästa sätt kunna stötta barns språkutveckling och förståelse för tryck. Sökord som jag använt är reading, preschool, read-aloud, shared reading och print. Efter databassökning valde jag ut artiklar som jag ansåg relevanta för mitt ämnesområde för att i nästa steg läsa och analysera innehållet. Det resultat jag kommit fram till tyder på att högläsning i förskolan kan bidra till att utveckla barns språk och förståelse för tryck men att det är flera yttre faktorer som också påverkar. En komponent som återkommande ansågs som viktig var läraren. De val som läraren gjorde både före, under och efter högläsning är något som enligt forskning inverkar positivt på barns språkutveckling och förståelse för tryck. Särskilt viktigt poängteras lärares vidareutbildning med fokus på högläsning vara för att läraren ska ha förmåga att under högläsning bidra till barns språkutveckling samt deras förståelse för tryck.

  • 18167.
    Yazdanfar, Camellia
    et al.
    Department of Geology, University of Golestan, Iran; Department of Geology, University of Uroumieh, Iran.
    Nemati, Majid
    Department of Geology, Faculty of Science and Earthquake Research Center of Shahid Bahonar University of Kerman, Iran.
    Agh Ataby, Maryam
    Department of Geology, University of Golestan, Iran.
    Roustaei, Mahasa
    Geological Survey of Iran, Iran.
    Nilfouroushan, Faramarz
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS. Geodata Division, Lantmäteriet, Gävle, Sweden.
    Stress transfer, aftershocks distribution and InSAR analysis of the 2005 Dahuieh earthquake, SE Iran2018In: Journal of African Earth Sciences, ISSN 0899-5362, Vol. 147, no 86, p. 211-219Article in journal (Refereed)
    Abstract [en]

    In this paper, the authors studied the 2005 Dahuieh Zarand earthquake in SE Iran by combining Coulomb stress changes, InSAR study, locally recorded aftershocks and their spatial correlations, co-seismic slip distributions, Iso-seismal curves, and strong ground motion data. The event (MW 6.4) occurred in Kerman province, SE Iran, on February 22, 2005. The locally recorded aftershocks were used to calculate the Coulomb stress changes and the decay time based on Omori’s law. The decay time of aftershocks calculated by Omori’s law was about 500 days. A great correlation was particularly deduced from the spatial distribution of the aftershocks and areas of increased Coulomb stress for optimal strike slip faults. Moreover, using SAR Interferograms, we determined the postseismic surface deformations. Also, the majority of the coseismic slips occurred in the eastern part, where there was sparsely distributed aftershocks. The deformation maps showed active uplift for at least 300 days after the main shock. We reconciled time decays of the aftershocks with the postseismic uplifts, calculated from InSAR. In our model, which is based on after slip evolution, for one of the postseismic relaxation mechanisms, we found a proper correlation between the aftershock decay time and InSAR displacement maps to define postseismic motions. There is also a reasonable correspondence between the mainshock intensity, the acceleration map, and postseismic ground uplift, estimated by InSAR.

  • 18168.
    Ye, Heshan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Wu, Jiading
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Selection of a Logistics Service Provider Based on Analytic Hierarchy Process (AHP) Approach: A case study of Swedish Coffee Manufacturer—Gevalia2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Logistics outsourcing has been applied in practices by enterprises for decades, but its efficiency is always restricted because logistics service providers (LSPs) often only have a single function such as delivery or warehousing. In the last few years, LSPs have upgraded their capabilities to support some other logistics services including value-added services, materials management, information-related services etc. The purpose of this thesis is to identify the differences between self-built logistics system and outsourcing logistics system by using the Strengths Weaknesses Opportunities Threats (SWOT) strategic analysis; and figure out how to apply the Analytic Hierarchy Process (AHP) to make an appropriate selection among LSPs that based on the single-case study of Gevalia. Both quantitative and qualitative methods have been used in this study, authors expect to describe and explore the application of AHP approach regarding to the case company which implements outsourcing logistics system. Accordingly, it could be a good idea for case company to implement the mixed mode of self-built and outsourcing logistics system after using the SWOT strategic analysis. In addition, the production and logistics manager of case company emphasized that the five selection criteria including “compatibility”, “delivery performance”, “location”, “management” and “cost” should be considered as a priority among other different criterion when he selected a LSP. As a result, it will be efficient and effective for us to simulate a best decision for those industrial manufacturing enterprises to achieve a path regarding to the selection of the best logistics partner that based on the significant AHP approach.

  • 18169.
    Ye, Minghui
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Tao, Jun
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Parents' experience of having premature baby: A literature review2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18170.
    Ye, Zi
    University of Gävle, Faculty of Engineering and Sustainable Development.
    Supply chain risk management on natural disaster: A study of global supply chain influence by2011Tohoku earthquake2011Independent thesis Basic level (degree of Bachelor), 15 credits / 22,5 HE creditsStudent thesis
  • 18171.
    Ye, Ziqiao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Tessellation of the sphere with different compression techniques2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Many kinds of data have a spherical representation, the idea is to tessellate the "sphere" in an efficient way and then decode the data so it can be compressed easily. In this paper, the process of exploration will start from the basic spherical wavelet-like to some new tessellation compression techniques in 3D to decompose the sphere with squares or triangles. The produced tessellation will have more round corners and the artefacts will be less prominent. Earth map will be textured on the sphere to compare the effect of different compression techniques.

  • 18172.
    YEHONG, LUO
    University of Gävle, Faculty of Health and Occupational Studies, Department of Social Work and Psychology.
    Research on the situation of deaf-mute Children of Migrant Workers in Guiyang, China2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is the outcome of a Field Study project. The aim of the study was to findout how the floating deaf-mute children of migrant workers experience psychologicalproblems in Guiyang, China. Bronfenbrenner’s ecological system theory was used asa theoretical frame. Semi-structured interviews were carried out with 4 inner migrantcouples who have deaf-mute children receiving treatment in a Center for disabled inGuiyang. 12 professionals working with treating deaf-mute children are alsointerviewed as well as 5 deaf-mute children. In total together 21 informants areinterviewed. The result of this study shows that three main aspects influence thepsychological problems of floating deaf-mute children with migrant parents most:social welfare policy, family income conditions and the center of treatmentenvironment. This study explored the problems based on Brofenbreener’s ecologicalsystems approach, which for the author had a new perspective to research on thesituation of deaf-mute children of migrant workers in Guiyang, China.

  • 18173.
    Yekkalam Lary, Nazanin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Energy Balance and Temperature Rise Study in Cutting Station at Sandvik AB2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project is a detail study of Energy Balance in cutting line station in Sandvik Mining and construction group.

    The aim of the project is reducing temperature and making a temperature balance inside the cutting line. During the recent years, many changes occur in production line. Existing cooling system cannot supply cutting area temperature below the desired level. Electrical Cables are melting due to high inside temperature. We attempted to study the old drawings and existing cooling system in cutting station to find out solutions to optimize and rebuild the old system. First part of study contains checking of preliminary air and water cooling system drawings. In the second part we looked at the operating cooling system by measuring different available working conditions such as inside temperature, air velocity and cooling water flow rate with different measuring equipment. The study integrate hot and cold stream (cooling air and water system) at different temperature level and in different times through production or non-production hours. Finally results and solutions can give valuable guidance for enterprises on how cooling systems should be expanded, what sizes should the new equipment have, where should the heat recovery exchangers be built, what new pipelines are needed, etc. To find more accurate results, we tried to do all measurements simultaneously, but due to difficult working condition it was not possible to have all input data at the same time. According to the primary data energy consumption during different times and Peak consumption amounts were calculated. Results consider the differences in cooling system effects inside the cutting line and the system which generates more cooling load and needed more improvements.  The summer and winter conditions are different inside the work area. The simultaneous assurance of ventilation, energy reduction and occupant health remains a design challenge. Working area is a unman area; therefore environmental impact are not considered in this research.

  • 18174.
    Yenigun, Cigdem
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences.
    Arbetslöshetens inverkan på nyanlända: En studie om eftergymnasialt utbildade nyanländas upplevelser av arbetslöshet2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study was to examine mental health in relation to unemployment among newly arrived with post-secondary education. This was to get a deeper understanding about their experiences regarding unemployment despite their high education, the focus was on mental health and how they think their future looks like. The method used for the following study was an empirical qualitative method in which the author used the semi-structured interviews. Five participants were interviewed, four men and one woman between the ages 20-64. The results of this study found that newly arrived people with post-secondary education had poor mental health because of worries about the future. They also felt that the education they had received from their country was a waste in Sweden. These people also had a temporary residence permit which brought frustration because their future wasn’t secure. The conclusion of this study was that newly arrived individuals with post-secondary education wanted Psychological help from the society so they could start working. 

  • 18175.
    Yermakova, Irena
    et al.
    International scientific training centre for information technologies and systems.
    Boiko, K
    Bortkiewicz, A
    Hallman, David
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Lyskov, Eugene
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Heart rate, blood pressure and electromyogram in assessment of physical activity fatigue using neural network model2011Conference paper (Refereed)
  • 18176.
    Yi, Fu
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences.
    Qunzhan, Zhang
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences.
    The Effect of life review on depression and depressive symptoms in adults: A descriptive literature review2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18177.
    Yi, Li
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Xieyan, Yu
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Registered nurses' reflections on nursing students' caring for end-of-life patients in a youth volunteer service: An interview study2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18178.
    Yi, Wu
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Xia, Mao
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    How registered nurses can work to support the middle aged and aged adults suffering from sleep disorders2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18179.
    Yi, Xing
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Chen, Zhang
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Patient’s Experiences of Having Lung Cancer: -  A descriptive review2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18180.
    Yi, Xueying
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Solla, Ivette
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Analyzing the Challenges and potential Opportunities for a Swedish Newly Established Firm when entering the Chinese Food Market: a marketing study for BIM in Zhuhai City2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    China has become one of the largest markets for business investments. A great number of foreign companies have showed interest in the Chinese market; even more when they seen how other companies have succeeded in the crossover. However, not everyone has been lucky enough to be successful in the Chinese market; this is especially true for small firms. Small companies have faced big troubles when entering the Chinese market; specifically those who decided to go international after a mere few years. In this study, we will show the challenges and potential opportunities for Swedish newly established firm when entering Chinese market. The company chosen was a Swedish food company called BIM, which also promotes healthy life styles.

       

    The authors begins the paper by briefly introducing the BIM company, background of this study, and some definitions, such as the Chinese concept of networking or Guanxi, the difference that exists between Swedish and Chinese managerial style and negotiating style and how can all of these issues can make a difference in succeeding in China. Next, the authors introduce the theoretical model which is a combination of opportunities; such as: costs of labour, market size and availability of resources; and barriers such as: networking, bureaucracy, culture, managerial and negotiating style. 

     

    Finally, the results show that new established companies that acknowledge the importance of a well establish network will have a bigger chance to succeed while doing business in China. A marketing study and interviews for the company BIM are shown in the appendix to assess opportunities and challenges before and after entering the Chinese market.

  • 18181.
    Yifan, Wang
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Yizhang, Huang
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
    Urban Wind and Thermal Environment Simulation - A Case Study of Gävle, Sweden2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    As urbanization and industrialization progressed during the last decades, Urban Heat Island (UHI) has become a major environmental issue to many cities around the world. The effect of UHI differs from area to area due to varying urban scale, population density, construction of urban surface layer, the level of industrialization and type of climate. Researchers have made great efforts in investigating various approaches to Urban Heat Island studies. Monitoring technologies have been widely used in this field, especially Geographic Information System (GIS) and remote sensing technology. Computational Fluid Dynamics (CFD) simulations are also actively applied in wind engineering, which can provide details of air flow over urban areas. The combined application of these technologies can provide the monitoring and simulation of urban wind corridor and thermal environment that can produce relevant information at a lesser time.A research using GIS, remote sensing technology and CFD simulation was done in this project to obtain a holistic view of the urban thermal environment and wind flow for Gävle City. With GIS and remote sensing the thermal image of the city was presented. The temperature data, which were collected from MODIS satellite were transferred and processed by ArcGIS and Global Mapper. The wind flow above the city was simulated through constructing geometric and mathematical model with OpenFOAM. The outcomes of the modeling and simulation identified that the temperature in the city center could possibly reach 35℃ during summers, which can cause the Urban Heat Island to form. Ventilation was also poorer in the city centre, and neither the river nor the green area in the southwest could help ventilate the city. The study result also suggested that certain sites in the city had relatively high wind flow for urban wind turbines to work.This study had used method of Urban Heat Island study with remote sensing and CFD technologies. The model produced from simulation could also be used to further study Gävle city's thermal and wind environment to produce more accurate results.

  • 18182.
    Yilin, Ding
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Zhou, Zhou
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Women’s experience of living with cervical cancer: – A descriptive  review2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18183.
    Yilun, Xin
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Yinyan, Wang
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Kind of support interventions and effects of them on self-management for patients with hypertension: A descriptive literature review2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18184. Yin, Li
    et al.
    Sundberg, Rolf
    Wang, Xiaoqin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för matematik och statistik.
    Rubin, Donald
    Control of confounding through secondary samples2006In: Statistics in Medicine, ISSN 0277-6715, E-ISSN 1097-0258, Vol. 25, no 22, p. 3814-3825Article in journal (Refereed)
    Abstract [en]

    The control of confounding is essential in many statistical problems, especially in those that attempt to estimate exposure effects. In some cases, in addition to the 'primary' sample, there is another 'secondary' sample which, though having no direct information about the exposure effect, contains information about the confounding factors. The purpose of this article is to study the influence of the secondary sample on likelihood inference for the exposure effect. In particular, we investigate the interplay between the efficiency improvement and the possible bias introduced by the secondary sample as a function of the degree of confounding in the primary sample and the sizes of the primary and secondary samples. In the case of weak confounding, the secondary sample can only little improve estimation of the exposure effect, whereas with strong confounding the secondary sample can be much more useful. On the other hand, it will be more important to consider possible biasing effects in the latter case. For illustration, we use a formal example of a generalized linear model and a real example with sparse data from a case-control study of the association between gastric cancer and HM-CAP/Band 120. Copyright (c) 2006 John Wiley & Sons, Ltd.

  • 18185.
    Yin, Li
    et al.
    Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.
    Wang, Xiaoqin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Mathematics.
    Estimating confidence regions of common measures of the baseline and treatment effect on dichotomous outcome of a population2017In: Communications in statistics. Simulation and computation, ISSN 0361-0918, E-ISSN 1532-4141, Vol. 46, no 4, p. 3034-3049Article in journal (Refereed)
    Abstract [en]

    In this article we estimate confidence regions of the common measures of (baseline, treatment effect) in observational studies, where the measure of a baseline is baseline risk or baseline odds while the measure of a treatment effect is odds ratio, risk difference, risk ratio or attributable fraction, and where confounding is controlled in estimation of both the baseline and treatment effect. We use only one logistic model to generate approximate distributions of the maximum-likelihood estimates of these measures and thus obtain the maximum-likelihood-based confidence regions for these measures. The method is presented via a real medical example.

  • 18186.
    Yin, Li
    et al.
    Karolinska Institute, Department of Epidemiology and Biostatistics.
    Wang, Xiaoqin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Mathematics.
    Measuring and estimating treatment effect on count outcome in randomized trial and observational studies2015In: Communications in Statistics - Theory and Methods, ISSN 0361-0926, E-ISSN 1532-415X, Vol. 44, no 5, p. 1080-1095Article in journal (Refereed)
    Abstract [en]

    When estimating treatment effect on count outcome of given population, one uses different models in different studies, resulting in non-comparable measures of treatment effect. Here we show that the marginal rate differences in these studies are comparable measures of treatment effect. We estimate the marginal rate differences by log-linear models and show that their finite-sample maximum-likelihood estimates are unbiased and highly robust with respect to effects of dispersing covariates on outcome. We get approximate finite-sample distributions of these estimates by using the asymptotic normal distribution of estimates of the log-linear model parameters. This method can be easily applied to practice.

  • 18187.
    Yin, Li
    et al.
    Department of Medical Epidemiology and Biostatistics, Karolinska Institute, .
    Wang, Xiaoqin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Mathematics.
    Parametric Inference of Sequential Causal Effects via Point Effects of Treatments2014In: Electronic Journal of Statistics, ISSN 1935-7524, E-ISSN 1935-7524Article in journal (Refereed)
  • 18188.
    Yin, Li
    et al.
    Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
    Wang, Xiaoqin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Mathematics.
    Ye, Weimin
    Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
    Maximum-likelihood estimation and presentation for the interaction between treatments in observational studies with a dichotomous outcome2017In: Communications in statistics. Simulation and computation, ISSN 0361-0918, E-ISSN 1532-4141, Vol. 46, no 9, p. 7138-7153Article in journal (Refereed)
    Abstract [en]

    In observational studies for the interaction between treatments, one needs to estimate and present both the treatment effects and the interaction to learn the significance of the interaction to the treatment effects. In this article, we estimate the treatment effects and the interaction jointly by using only one logistic model and based on maximum-likelihood. We present the interaction by (1) point estimate and confidence interval of the interaction, (2) point estimate and confidence region of (treatment effect, interaction) and (3) point estimate and confidence interval of the interaction when the maximum-likelihood estimate of one treatment effect falls into specified range.

  • 18189.
    Yin, Li
    et al.
    Department of Medical Epidemiology and Biostatistics, Karolinska Institute, .
    Ye, Weimin
    Department of Medical Epidemiology and Biostatistics, Karolinska Institute, .
    Wang, Xiaoqin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Mathematics.
    Point and interval estimation of exposure effects and interaction between exposures based on logistic model for observational studies2016In: Communications in statistics. Simulation and computation, ISSN 0361-0918, E-ISSN 1532-4141Article in journal (Refereed)
  • 18190.
    Yin, S.
    et al.
    Department of Mechanical Engineering, University of Hong Kong.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Li, Y.
    Department of Mechanical Engineering, University of Hong Kong.
    Water tank investigation of single and multiple buoyant plumes from squared blocks in calm environment2014In: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, p. 295-297Conference paper (Refereed)
  • 18191.
    Yin, Shi
    et al.
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region.
    Fan, Yifan
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region; College of Civil Engineering and Architecture, Zhejiang University, Yuhangtang Road, Hangzhou, China .
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Li, Yuguo
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Special Administrative Region.
    PIV based POD analysis of coherent structures in flow patterns generated by triple interacting buoyant plumes2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 158, p. 165-181Article in journal (Refereed)
    Abstract [en]

    The paper performs an investigation on multi-scale coherent structures that exist in different flow patterns of triple interacting plumes. Time-averaged and turbulent flow characteristics are first obtained by the two-dimensional (2-D) particle image velocimetry (PIV) technique. Proper orthogonal decomposition (POD) method is then applied to extract the dominant coherent structures. Energy contributions, POD modes, and POD coefficients are systematically explored to understand the spatial-temporal characteristics of the coherent structures. The first three POD modes are most important in the turbulent kinetic energy (TKE). Mode 1, as the most dominant mode, can contain about 10% TKE in an average sense. In addition, the first 12–14 POD modes can totally contribute 50% TKE. Hierarchical four-scale flow structures, independent of the flow patterns, are clearly identified when mode number increases, which are successively characterized by main flows (the 1st scale), larger-scale outer-side vortex rings (the 2nd scale), shear-layer vortex shedding (the 3rd scale), and smaller-scale homogeneous turbulent vortices (the 4th scale). Frequency spectra analysis confirms the co-existence of lower-frequency and higher-frequency periodic cycles in one certain POD mode. Dominant frequencies of the first three POD coefficient series (a1–a3) fall into the range of 0.025–0.187 Hz. Probability density analysis has identified negative/positive peak probability densities of the series a1. Cumulative probabilities of negative and positive coefficients are approximately equivalent during the sampling period. 

  • 18192.
    Yin, Shi
    et al.
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
    Li, Yuguo
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
    Fan, Yifan
    Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Experimental investigation of near-field stream-wise flow development and spatial structure in triple buoyant plumes2019In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 149, p. 79-89Article in journal (Refereed)
    Abstract [en]

    This paper presents a systematic experimental study on stream-wise flow development and spatial structure of triple buoyant plumes. Two-dimensional Particle Image Velocimetry (2-D PIV) is employed to resolve velocity fields. Stream-wise axial velocity profiles, flow structure, flow region parameters, and self-similarity properties are analyzed at different configurations that are characterized by spacing ratios S/W (source spacing S divided by source width W). From velocity fields and axial velocity profiles, a similar stream-wise developing trend is identified in different source configurations. When near-field plumes travel downstream, axial velocities increase rapidly, off-center velocity peaks get merged with the central peak, and the number of velocity peaks reduces with the downstream distance. A compact source layout, comparing with the wide one, could enhance the near-field plumes interaction and promote the plumes deflection significantly. Fundamentally, the stream-wise spatial structure of the triple plumes initially consists of a converging region, followed by a merging region, and finally a combined region. By examining the averaged velocity fields, flow recirculation with negative axial velocities is found to scarcely exist in the converging region. Merging level Zm and quasi-combined level Zqc are analyzed quantitatively and statistically. Within the studied S/W range, the normalized Zm shows a linear increase with S/W in the formula of Zm/H=2.007(S/W)+1.173 and the normalized Zqc gives a power law increase with S/W in the formula of Zqc/H=6.035(S/W)0.4959. In addition, triple plumes are found to establish self-similarity approximately at Z = 3H with S/W of 0.2 and at Z = 4.5H with S/W of 0.5.

  • 18193.
    Yin, Shi
    et al.
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
    Li, Yuguo
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
    Fan, Yifan
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Unsteady large-scale flow patterns and dynamic vortex movement in near-field triple buoyant plumes2018In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 142, p. 288-300Article in journal (Refereed)
    Abstract [en]

    Unsteady flow patterns of interacting buoyant plumes are important for buoyant ventilation and particularly influence pollutant and heat transports in indoor and outdoor environments. This study reveals fundamental large-scale flow patterns in triple building plumes, investigates vortex moving trends during the pattern transition processes, and explores possible mechanisms of pattern diversity by two-dimensional (2-D) Particle Image Velocimetry (PIV). Total five tests are studied, including three different heat strengths Q (180, 90, and 30 W) and three source layouts characterized by the ratios of source spacing S to source width W (0.2, 0.5, and 1.0). Streamline distributions and axial velocity profiles clearly reveal three fundamental global flow patterns: a right-slanting asymmetrical flow pattern, a left-slanting asymmetrical flow pattern, and an axisymmetric flow pattern. Correspondingly, it indicates four basic transition processes, i.e., right-to-center, left-to-center, center-to-right, and center-to-left transitions (“center” represents the axisymmetric pattern). A novel vortex tracking method, based on lambda-2 (λ2) criterion and principles of the PIV technique, is developed and successfully applied to qualitatively track the vortex moving trends during the transition processes. The regular vortex moving trends are found to be reasonably consistent with the global pattern transition trends. The flow pattern diversity is speculated to be mainly driven by unstable heat source wall flows and downstream swaying motions in this study. These critical unstable motions are considered to probably relate to unstable lateral entrainment and vortex interaction, particularly beside the central plume. Consistently, the regular vortex moving trends are usually observed in and around the central plume.

  • 18194.
    Yin, Shi
    et al.
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
    Li, Yuguo
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Lam, Kitming
    Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China.
    The effect of building spacing on near-field temporal evolution of triple building plumes2017In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 122, p. 35-49Article in journal (Refereed)
    Abstract [en]

    Building plume is important for ventilation and pollutants dispersion along and above buildings in an urban canopy layer. This study fundamentally explores the merging process and temporal penetration of triple uniformly distributed starting building plumes, with a focus of the spacing effect on near-field flow dynamics. Instantaneous velocity and vorticity distributions, penetrating velocities, and stream-wise penetrated heights are quantitatively examined using 2-D particle image velocimetry (PIV) measurements at spacing ratios S/W (building spacing/building width) of 0.2, 0.5, and 1.0. We identified a four-stage merging progress and captured three main spacing-induced merging features. A compact layout at S/W = 0.2 introduces a strong upward channel flow. The wall flows beside the channel tend to draw together first and the unstable channel flow determines the flow pattern transition. In contrast, wider layouts at S/W = 0.5 and 1.0 exhibit intensive downward flow. The wall flows tend to exhibit self-merging initially and the downstream natural swaying motion dominates the merged pattern variations. Merging effect and buoyancy force jointly determine the temporal penetrating velocities. Temporal series of maximum axial velocities above the middle source fits into a power law profile at S/W = 0.2 but a linear function of time at S/W = 0.5 and 1.0. The normalized penetrated heights at S/W = 1.0 are notably faster than in the other two cases before the normalized time is at 3.00 probably because the weaker entrainment and interaction with neighbors lead to less energy and momentum dissipation, quicker self-merging, and faster penetration.

  • 18195.
    Yin, Shi
    et al.
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
    Sandberg, Mats
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Lam, Kit-Ming
    Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region.
    Li, Yuguo
    Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region.
    Near-field merging and penetration of triple starting plumes from volumetric heat sources in a calm environment2017In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 115, no Part B, p. 1321-1333Article in journal (Refereed)
    Abstract [en]

    This paper investigates the buoyancy effect on near-field evolution of triple equal starting thermal plumes from volumetric heat sources, with a focus on merging process, velocity evolution, and stream-wise penetration. Instantaneous velocity fields and corresponding vorticity distribution, temporal evolution of centerline axial velocities, temporal penetrating rates and heights are examined by 2-D particle image velocimetry (PIV) at three different source heat strengths of 180 W, 90 W, and 30 W. A four-stage merging process is demonstrated to be independent of heat strength. Normalized starting and terminating times of each developing stage are also unified regardless of the heat strength, i.e., t/t∗ = 1.7–2.5 for stage i (relatively isolated development), t/t∗ = 2.5–3.3 for stage ii (bending wall flows), t/t∗ = 3.3–3.9 for stage iii (development after a self-merged state), and t/t∗ > 3.9 for stage iv (evolution with global merging). The axial velocity at a specific centerline point usually involves three distinct developing periods: a “centerline-silent” period ending at a normalized transportation time tt_n when heat is just transported to the measuring points, a fast rising period, and a fluctuating period starting at a normalized endurance time te_n. The buoyancy-independent tt_n is approximately 1.5, 2.2, 3.0, and 3.2 at a normalized downstream distance of 1.5, 2.5, 3.5, and 4.5, respectively. The time te_n, independent of buoyancy and axial height, is about 3.6 for all measuring points in this study. The maximum axial velocity above the middle heat source exhibits three linearly developing periods with different acceleration rates successively: a quicker rate as the wall flow develops, a slower rate due to enhanced lateral interaction, and the fastest rate as the global merging happens. In different periods, the proportional coefficients of linear fitted functions vary from 0.48 to 2.98. The downstream distance where axial velocity is maximum shows similar power-law increasing during t/t∗ = 1.5–3.2 at Q = 180 and 90 W, but exhibits significant fluctuations at Q = 30 W. Normalized overall penetration based on global velocity fields is notably faster and higher at the lowest buoyancy (Q = 30 W) than that at the higher buoyancy (Q = 180 and 90 W), probably due to the weaker lateral interaction and turbulent mixing together with the more dedicated vertical rise at Q = 30 W.

  • 18196.
    Ying, Song
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Energy analysis for a snow-free surface: A technical analysis of the benefits of insulation under the heating pipes2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Snow-free surfaces is needed for parking place, platform, and playground and even in city center square. With energy prices rising, energy saving is becoming a hot topic. Meanwhile environmental problems are becoming more and more serious, thus, the ways to saving energy is becoming an eye-catcher. So burring heating pipes underground has been a popular way to get ice-free surfaces. Using heating pipes for melting snow is much more efficient and more benefit for the environment comparing with using other methods.

     

    In this project, an energy analysis of a football pitch with an area of 5000 m2 is carried out under a series of conditions between insulated and uninsulated construction. All calculations are done with the so-called finite element method (FEM), in the COMSOL. COMSOL is used for simulating and calculating the energy use with outdoor temperatures of -5 ºC and -10 ºC. Top layer materials concrete, grass and stone are also discussed. The ability of XPS and EPS insulation material is compared and noted. The models are divided into two parts, one is with snowfall and the other is without snowfall.

     

    The results in the report shows that adding insulation under the heating pipe has significant energy saving potential. The surface with concrete layer has the best insulated ability, which can prevent more heat losses. The EPS insulated construction has a better performance in keeping more heat in the soil. 

  • 18197.
    Ying, Zhang
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Jamin, Wang
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Registered nurses’ perceptions of nursing bedside handover2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18198.
    Yingjia, Yao
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Sun, Jiaqing
    University of Gävle, Faculty of Health and Occupational Studies, Department of Caring Sciences. Lishui University, China.
    Health literacy among middle-aged and elderly patients with cardiovascular disease in Lishui: - a quantitative study2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18199.
    Yiting, Zhu
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Xinyu, Gong
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Kind of interventions and effects of them on foot ulcers of patients with diabetes: A descriptive literature review2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 18200.
    Yiying, Chen
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Zhulian, Yang
    University of Gävle, Faculty of Health and Occupational Studies, Department of Health and Caring Sciences. Lishui University, China.
    Self-regulated learning ability among undergraduate nursing students: A Cross-sectional study2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
361362363364365366367 18151 - 18200 of 18812
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