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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Optimizing Logistic Operations: exploring diverse approaches to order point dynamics / Optimera logistiska operationer: utforska olika tillvägagångssätt för beställningspunktsdynamik

Ezzalden, Aziz, Momin, Zain January 2024 (has links)
ABSTRACT Date:                           02 June 2024 Level:                          Master thesis in Product and Process Development, advanced level, 30                                       credits. Institution:                 School of Innovation, Design and Engineering, Mälardalen University Author:                       Aziz EzzAlden                        Zain Momin    20th November 1998  10th August 1998                                Title:                           Optimizing Logistic Operations: exploring diverse approaches to order                                         point  dynamics  Tutor:                         Ebba Bengtsson, Organisation                                     Yuji Yamamoto, Mälardalen University Keywords:                  RFID, Kanban; Push; Pull; Just In Time; internal logistics; Signals;                                      Material flow; Order point Purpose:                     The aim of the study was to investigate the impact of order points on                                           logistics operations and how smart inventory technologies address the                                                 challenges of order  point management. By utilizing a framework that                                                                  aligns with logistics operations and smart inventory practices.  Research  questions:  1. How does order point affect the logistic operations and their                                              performance?                           2. How can smart inventory address the challenges related to order                           points?  Method:                      This study adopts an abductive approach, facilitating a dynamic                                      interaction between theoretical frameworks and empirical findings.                                       The theoretical framework is based on scientific articles. The study                                      focuses on a singular main case organisation, supplemented by                                                    comparative analyses involving three additional organisations,                                       forming a case study design. Empirical data allocation used multiple                                       semi-structured interviews, unstructured interviews, and observations                                       to gather data.  Conclusion:                The study indicated that efficient order point systems are crucial for                                        ensuring timely material replenishment and optimizing material flow.                                        Additionally, smart inventory technologies offer effective solutions,                                        including real-time monitoring and automated reordering, which                                        minimize errors and enhance efficiency in logistical operations. / SAMMANFATTNING Datum:                        02 juni 2024 Nivå:                            Examensarbete i produkt- och processutveckling avancerad nivå, 30 hp.                                     Institution:                  Akademin för Innovation. Design och Teknik. IDT, Mälardalens                                                 universitet  Författare:                  Aziz EzzAlden                        Zain Momin     20 November 1998   10 Augusti 1998                                Titel:                            Optimering av logistik operationer: utforska olika tillvägagångssätt för                                        order punkts dynamik. Handledare:               Ebba Bengtsson, Organisation                                     Yuji Yamamoto, Mälardalens universitet Nyckelord:                  RFID, Kanban; Push, Pull; Just In Time; instant logistics; Signaler,                                       Materialflöde; Order Punkt Syfte:                          Syftet med studien var att undersöka hur orderpunkter påverkar                                      logistik operationer och hur smarta lager teknologier hanterar                                      utmaningarna med orderpunkt hantering. Detta genom att använda en                                    ram som överensstämmer med logistikoperationer och smarta                                    lagerpraxis. Frågeställningar:       1. Hur påverkar order punkten logistikoperationer och deras prestanda?                                      2. Hur kan smarta lager hantera utmaningarna relaterade till                                                                order punkter? Metod:                          Denna studie antar ett abduktivt tillvägagångssätt som underlättar en                                         dynamisk interaktion mellan teoretiska ramverk och empiriska resultat.                                        Det teoretiska ramverket är baserat på vetenskapliga artiklar. Studien                                           fokuserar på en enda huvudorganisation, kompletterad med jämförande                                          analyser som involverar tre ytterligare organisationer, vilket bildar en                                         fallstudiedesign. Empiriska datainsamlingen använde sig av flera                                          semi-strukturerade intervjuer, ostrukturerade intervjuer och                                                observationer för att samla in data. Slutsats:                       Studien indikerade att effektiva orderpunkt system är avgörande för att                                        säkerställa att material återfylls i rätt tid och för att optimera                                       materialflödet. Dessutom erbjuder smarta lager teknologier effektiva                                       lösningar, inklusive realtidsövervakning och automatisk ombeställning,                                        vilket minimerar fel och ökar effektiviteten i logistikoperationer.
102

Dispersão Raman de um sistema doador-aceptor em diferentes solventes / Raman dispersion of a donor-acceptor system in different solvents

Carli, Fernanda Pereira 16 August 2016 (has links)
Sistemas push-pull são caracterizados pela presença de uma transição eletrônica de transferência de carga, o que justifica a grande diferença de polaridade entre os estados fundamental e excitado. Isso os torna sondas moleculares promissoras para a obtenção de informações espectroscópicas sobre a fase condensada. Alguns desses sistemas apresentam modos vibracionais cuja frequência depende da energia de excitação nos espectros Raman. Neste estudo, através de uma sonda molecular push-pull, objetivou-se analisar as características do meio que definem tal dependência. A sonda utilizada, 4-dimetilamino-β-nitroestireno apresentou deslocamento batocrômico no espectro de absorção eletrônico e a dependência da largura de banda com o solvente, o que mostrou sua sensibilidade ao meio, juntamente com uma dependência do modo de estiramento simétrico do grupo nitro com o solvente. Através do modelo do estado de solvatação seletivo, variando a energia de excitação do laser, foi possível observar a dependência do número de onda do modo de estiramento simétrico do NO2. Essa dependência foi, no entanto, mais significativa em solventes próticos polares, os quais apresentam os maiores valores de tempo de relaxação do solvente. Alguns solventes polares apróticos também apresentaram, mas com menor deslocamento, o que poderia estar relacionado com o tempo de relaxação. Solventes com dinâmicas de solvatação mais lentas e com forte interação, provocando uma diminuição na energia de transição eletrônica, são os principais fatores para ocorrência da dispersão Raman em sistemas push-pull. / The push-pulls systems are characcterized by the presence of a charge transfer electronic transition, it explain the large difference in polarity between the ground and excited states. They are promising molecular probes to obtain spectroscopic information on the condensed phase because of that characteristic. Some of these systems have vibrational modes whose frequency depends on the excitation energy in the resonant Raman spectra. The objective of this study was to analyze the vibrational frequency dependence of the molecular probe caused by environment. The 4-dimethylamino-β-nitrostyrene as a probe was sensitive to the medium showing bathochromic shift on electronic spectrum and bandwidth dependence with the solvent as well as the dependency of the nitro symmetric stretching mode in the vibrational spectrum. Based on the selective solvation state model, the laser excitation energy was varied and the dependence of the wave number of the symmetric stretching mode NO2 was observed. This dependency is, however, more significant in polar protic solvents which have the highest relaxation time values of the solvent. Some aprotic polar solvents presented that characteristic with less degree, which may be related to the relaxation time. The main factor for the occurrence of Raman scattering in push-pull solvation systems is the slower solvation dynamics and strong interaction that are capable to diminishing the energy electronic transition. The main factors for the occurrence of Raman dispersion in push-pull solvation systems are the slower solvation dynamics and strong probe/solvent interaction that are capable to diminishing the electronic transition energy.
103

Functional Reactive Musical Performers

Phillips, Justin M 01 December 2010 (has links)
Computers have been assisting in recording, sound synthesis and other fields of music production for quite some time. The actual performance of music continues to be an area in which human players are chosen over computer performers. Musical performance is an area in which personalization is more important than consistency. Human players play with each other, reacting to phrases and ideas created by the players that they are playing with. Computer performers lack the ability to react to the changes in the performance that humans perceive naturally, giving the human players an advantage over the computer performers. This thesis creates a framework for describing unique musical performers that can play along in realtime with human players. FrTime, a reactive programming language, is used to constantly create new musical phrases. Musical phrases are constructed by unique user programmed performers and by chord changes that the framework provides. The reactive language creates multiple musical phrases for each point in time. A simple module which chooses musical phrases to be performed at the time of performance is created.
104

陸生來台就讀大學院校之拉力因素分析 / The analysis of the pull factors of Taiwan higher educational institutes of students from mainland China

陳治堯, Chen, Chih Yao Unknown Date (has links)
本研究旨在探討影響國際學生流動的拉力因素構面,並找出台灣大學院校對大陸學生的主要拉力因素為何,以做為未來政策制定和大學院校招生之參考。經過文獻探討之後發現國際學生流動的拉力因素有八個構面,分別是學校機構、留學政策、國際競爭力、地理環境、經濟、社會文化、家庭與體制因素。研究方法的部分,利用專家問卷進行問卷試題的適切性評估,再使用因素分析與信度分析法,確立問卷各因素構面試題並取得良好的信度,並利用網路問卷調查法進行正式問卷施測,共計386位填答者,有效填答有286位。研究分析使用描述性統計、獨立樣本t考驗和單因子變異數分析,來探討我國大學院校對於大陸學生的拉力因素排序情形與不同背景變項間的差異程度。根據分析結果,歸納出本研究之結論如下: 一、留學政策的制定是台灣吸引陸生的最主要拉力。 二、台灣的文化與大學特色是吸引陸生的重要拉力。 三、男性在留學政策因素上認同度高。 四、商業管理的學生在留學政策因素上的認同度較農業及醫藥學的學生高。 五、有來台經驗的學生在學校機構與體制因素上的認同度較高。 六、經濟因素會因學生是本科生或研究生而有所差異。 最後,根據本研究之結論,對於台灣大學院校、教育行政主管機關和未來研究提出建議,以制定相關招生策略、政策規定或是未來研究方向。 / The purpose of this study is to explore the dimension of the pull factors of international student mobility, and discover the main pull factors of Taiwan higher educational institutes, in order to make proper future policies and strategies for recruiting students from mainland China. Through literature review, this study finds that there are eight dimensions of pull factors which are dimension of educational institutes, dimension of study-abroad policy, dimension of international competitiveness, dimension of environment, dimension of economics, dimension of socio-culture, dimension of family, and dimension of national system. As for research methods, using expert questionnaire, factor analysis and reliability analysis to ensure all questions are well-stated and get good degree of reliability, and then using web-based questionnaire to do the survey. In this study, there are 386 respondents, and 286 of them are valid. By means of descriptive statistics, independent t-test and one-way ANOVA, the order of the pull factor and the differences between every background variables are found. According to the results, the main conclusions are as follows: 1.The making of study-abroad policy is the main pull factor of Taiwan for students from mainland China. 2.The characteristics of Taiwanese culture and universities are important pull factors. 3.Male shows higher degree of agreement in the dimension of study-abroad policy factors. 4.Students of business and management show higher degree of agreement in the dimension of study-abroad policy factors than students of agriculture and medical science. 5.Students who have experiences in Taiwan show higher degree of agreement in the dimension of educational institutes and national system factors. 6.Undergraduate students and graduate students show different degree of agreement in the dimension of economics factors. In the end, based on the conclusion of this study, some suggestions had been proposed to Taiwan educational institutes, educational administration authority and future research, in order to make appropriate policies, strategies, or research direction.
105

Resonant Transition Topologies For Push-Pull And Half-Bridge DC-DC Converters

Swaminathan, B 05 1900 (has links)
Switched mode power supplies (SMPS) are being extensively used in most power conversion processes. The analysis, design and modeling processes of hard-switched converters are mature, where the switching frequency was limited to a few 10's of kHz. The present direction of evolution m SMPS is towards higher efficiency and higher power density. These twin objectives demand high switching frequency and low overall losses. Soft switching results in practically zero switching losses and extends the switching frequency to 100's of kHz and beyond. This thesis presents novel variants of push-pull and half-bridge DC-DC converters with soft switching properties. The proposed topology uses two additional switches and two diodes. The additional switches introduce freewheeling intervals m the circuit and enable loss-less switching. Switch stress, control and small signal model are similar to hard-switched PWM converter. Synchronous rectifiers are used in the ZVS push-pull converter to achieve high efficiency. It is interesting to see that the drives for the synchronous rectifier device are practically the same as the additional switches. The contributions made in this thesis are 1) Idealized analysis and design methodology for the proposed converters. 2) Validation of the design through circuit simulation as well as prototypes - a 300kHz, 200W push-pull converter and a 300kHz, 640W half-bridge converter. 3) Closed loop control design for desired bandwidth and accuracy Verification of loop gain through network analyzer instrumental for the same The loop gain bandwidth achieved is about 30kHz for the push-pull converter and 20kHz for half-bridge converter. An appendix has been devoted to explain the use of network analyzer. Characterization of coil, transformer and capacitor are explained in detail. Measurement techniques for measuring the small signal parameters of power supply are also explained in the appendix.
106

Characterization and Simulation of Material Distribution and Fiber Orientation in Sandwich Injection Molded Parts

Patcharaphun, Somjate 09 October 2006 (has links) (PDF)
In this work, the material distribution, structure of fiber orientation and fiber attrition in sandwich and push-pull injection molded short fiber composites are investigated, regarding the effect of fiber content and processing parameters, given its direct relevance to mechanical properties. The prediction of the tensile strength of conventional, sandwich and push-pull injection molded short fiber composites are derived by an analytical method of modified rule of mixtures as a function of the area fraction between skin and core layers. The effects of fiber length and fiber orientation on the tensile strength are studied in detail. Modeling of the specialized injection molding processes have been developed and performed with the simulation program in order to predict the material distribution and the fiber orientation state. The secondorder orientation tensor (a11) approach is used to describe and calculate the local fiber orientation state. The accuracy of the model prediction is verified by comparing with corresponding experimental measurements to gain a further basic understanding of the melt flow induced fiber orientation during sandwich and push-pull injection molding processes.
107

”Jag söker ett land, där jag med arbete kan hjälpa mig och de mina” : Vad hade amerikaemigranterna (1840-1914) för uttalade anledningar för sin utvandring? / “I seek a land where I through my work can help myself and mine” : What reasons did the America emigrants (1840-1914) state for their exodus from Sweden?

Armblad, Robert January 2014 (has links)
This Bachelor thesis aims to uncover the main reasons the Swedish emigrants stated for migration during the mass migration to North America during 1840 to 1914. The research material used for this thesis is a mix of Swedish emigrant letters, letters to the Swedish government’s report on migration (Emigrationsutredningen) and letters to the editor of the Chicago based Swedish-American newspaper Svenska Amerikanaren. By using quantitative content analysis I got results that are presented in this paper through different categories of stated reasons. The distribution of the categories in the different kinds of material and how the distribution of stated reasons changed over time is presented through charts. Results show that the by far most stated main reason for migration during all the periods of the mass migration was to improve the economic situation of the Swedish emigrant. The results also show that the stated reasons for migration confirms a lot of the ideas and research presented by earlier studies on the subject of the Swedish migration to North America during 1840-1914.
108

Estudo sobre a estrutura eletrônica de ftalocianinas metaladas para aplicação em células solares sensibilizadas por corante

Gomes, Weverson Rodrigues 16 February 2012 (has links)
Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The electronic properties of push-pull substituted, zinc(II) (ZnPc), aluminum(III) (AlPc), and ruthenium(II) (RuPc), metal-phthalocyanine derivatives, presenting two electron donating groups (diethylamine) and two electron withdrawing groups (carboxylic) was studied using the Density Functional Theory (DFT) with B3LYP exchange-correlation functional in the vacuum and under the presence of solvent (DMSO), aiming their application in dye-sensitized solar cells (DSSC). For the excited states, the time-dependent approach of DFT (TD-DFT) was applied. In the transition for the excited state it was evidenced a charge transfer from donor to acceptor groups which results in large electronic rearrangement inducing the bathochromism when adding DMSO (a polar solvent). This electronic transfer is directed to the acceptor groups (benzoic groups), mainly in RuPc molecule, which enables bigger probability in the electronic injection into the semiconductor s conduction band. HOMO s energy to the ZnPc and AlPc are sufficiently below the redox potential of the electrolyte and LUMO s energy, in all compounds, is above the conduction band of the oxide. Those push-pull molecules present panchromism, important for the application of these compounds in DSSC since they can absorb photons in a large range of energies. NBO analysis suggests that the ruthenium presents strong coordination with the nitrogen atoms of the macrocycle, which allows a larger participation of this metal in the electronic transition. The ionization energy and electron affinity were calculated aiming to quantify the energetic barrier in the electron gain / loss. / As propriedades eletrônicas de derivados de ftalocianinas metaladas push-pull de zinco(II) (FtZn), alumínio(III) (FtAl) e rutênio(II) (FtRu) apresentando dois grupos doadores de elétrons (N,N-dietilanilina) e dois grupos retiradores de elétrons (ácido benzóico), foram estudadas usando a teoria do funcional de densidade (DFT) com o funcional híbrido B3LYP na presença do solvente (DMSO) e no vácuo, visando sua aplicação em células solares sensibilizadas por corante (CSSC). Para a descrição dos estados excitados usou-se a extensão dependente do tempo da DFT (TD-DFT). Na transição para o estado excitado destes compostos há uma transferência de carga dos grupos doadores para os grupos aceptores, que resulta em rearranjo eletrônico induzindo o efeito batocrômico observado com a adição de DMSO. Essa transferência eletrônica está direcionada para o grupo aceptor (grupo benzóico), principalmente na FtRu, que possibilita uma maior probabilidade na injeção eletrônica na banda de condução do semicondutor. A energia do HOMO para a FtZn e FtAl estão suficientemente abaixo do potencial redox do eletrólito e o LUMO, em todos os compostos, está acima da banda de condução do TiO2. Essas moléculas push-pull apresentam pancromismo, importante para a aplicação destes compostos em CSSC uma vez que podem absorver fótons de diferentes energias. Análises NBO sugerem que o rutênio apresenta forte coordenação com os nitrogênios do macrociclo que possibilita grande participação deste metal nestas transições eletrônicas. As energias de ionização e eletroafinidades foram calculadas com o objetivo de quantificar a barreira energética no ganho/perda de um elétron. / Mestre em Química
109

Sistema Fotovoltaico de Pequeno Porte Interligado à Rede ElÃtrica / A Low Power, Grid-Connected Photovoltaic System

Eldin Mario Miranda TerÃn 02 March 2012 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A necessidade de obter uma matriz energÃtica menos poluente e em harmonia com o meio ambiente à um tÃpico muito importante no sÃculo XXI. Este trabalho apresenta um conversor cc-ca de dois estÃgios para injetar a energia de um arranjo de painÃis fotovoltaicos à rede elÃtrica. O primeiro estÃgio à um conversor elevador, isolado, baseado na CÃlula de ComutaÃÃo de TrÃs Estados (CCTE), responsÃvel por elevar a tensÃo dos painÃis fotovoltaicos de 48 Vcc para 400 Vcc e de extrair a mÃxima potÃncia disponÃvel deles. O segundo estÃgio consiste em um conversor monofÃsico cc-ca, ponte completa, responsÃvel por injetar a energia na rede elÃtrica de baixa tensÃo (220 Vca, 60 Hz). SÃo apresentados estudos teÃricos e exemplos de projeto dos circuitos de potÃncia e controle para ambos os estÃgios e, com o objetivo de validar a anÃlise, sÃo apresentados resultados de simulaÃÃo computacional, complementados com resultados experimentais, correspondentes a um protÃtipo de laboratÃrio de 850 W. O rendimento global obtido experimentalmente à aproximadamente 86,5% enquanto que a distorÃÃo harmÃnica total da corrente entregue à rede elÃtrica obtida via simulaÃÃo computacional à 3,8% a plena carga. / In the 21st century, the need of a more clean and environment friendly power matrix has become a very important issue. Therefore this work presents a two stage cc-ac converter for connecting a photovoltaic array to the electrical grid. The 1st stage itâs an isolated boost converter, based in the Three Stage Switching Cell (TSSC), in charge of boosting the photovoltaic array voltage from 48 Vcc to 400 Vcc and to track its maximum power point. The 2nd stage is a single-phase cc-ac Full-Bridge converter responsible of injecting the photovoltaic power into the low voltage power grid (220 Vac, 60 Hz). Both, theoretical analysis and designs examples of power and control circuits are presented for the two stages and, in order to validate the analysis, simulation results complemented with experimental results from an 850 W laboratory prototype are presented. The overall efficiency obtained from the prototype was 86.5% while the total harmonic distortion of the current obtained via simulation was 3.8% at full load.
110

Dispersão Raman de um sistema doador-aceptor em diferentes solventes / Raman dispersion of a donor-acceptor system in different solvents

Fernanda Pereira Carli 16 August 2016 (has links)
Sistemas push-pull são caracterizados pela presença de uma transição eletrônica de transferência de carga, o que justifica a grande diferença de polaridade entre os estados fundamental e excitado. Isso os torna sondas moleculares promissoras para a obtenção de informações espectroscópicas sobre a fase condensada. Alguns desses sistemas apresentam modos vibracionais cuja frequência depende da energia de excitação nos espectros Raman. Neste estudo, através de uma sonda molecular push-pull, objetivou-se analisar as características do meio que definem tal dependência. A sonda utilizada, 4-dimetilamino-β-nitroestireno apresentou deslocamento batocrômico no espectro de absorção eletrônico e a dependência da largura de banda com o solvente, o que mostrou sua sensibilidade ao meio, juntamente com uma dependência do modo de estiramento simétrico do grupo nitro com o solvente. Através do modelo do estado de solvatação seletivo, variando a energia de excitação do laser, foi possível observar a dependência do número de onda do modo de estiramento simétrico do NO2. Essa dependência foi, no entanto, mais significativa em solventes próticos polares, os quais apresentam os maiores valores de tempo de relaxação do solvente. Alguns solventes polares apróticos também apresentaram, mas com menor deslocamento, o que poderia estar relacionado com o tempo de relaxação. Solventes com dinâmicas de solvatação mais lentas e com forte interação, provocando uma diminuição na energia de transição eletrônica, são os principais fatores para ocorrência da dispersão Raman em sistemas push-pull. / The push-pulls systems are characcterized by the presence of a charge transfer electronic transition, it explain the large difference in polarity between the ground and excited states. They are promising molecular probes to obtain spectroscopic information on the condensed phase because of that characteristic. Some of these systems have vibrational modes whose frequency depends on the excitation energy in the resonant Raman spectra. The objective of this study was to analyze the vibrational frequency dependence of the molecular probe caused by environment. The 4-dimethylamino-β-nitrostyrene as a probe was sensitive to the medium showing bathochromic shift on electronic spectrum and bandwidth dependence with the solvent as well as the dependency of the nitro symmetric stretching mode in the vibrational spectrum. Based on the selective solvation state model, the laser excitation energy was varied and the dependence of the wave number of the symmetric stretching mode NO2 was observed. This dependency is, however, more significant in polar protic solvents which have the highest relaxation time values of the solvent. Some aprotic polar solvents presented that characteristic with less degree, which may be related to the relaxation time. The main factor for the occurrence of Raman scattering in push-pull solvation systems is the slower solvation dynamics and strong interaction that are capable to diminishing the energy electronic transition. The main factors for the occurrence of Raman dispersion in push-pull solvation systems are the slower solvation dynamics and strong probe/solvent interaction that are capable to diminishing the electronic transition energy.

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