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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.
181

Carrier profiling of ZnO nanowire structures by scanning capacitance microscopy and scanning spreading resistance microscopy / Profilage porteur de structures de nanofils ZnO par microscopie à capacité de balayage et microscopie à dispersion

Wang, Lin 28 April 2016 (has links)
Ce travail de thèse porte sur l'application des techniques Scanning Capacitance Microscopy (SCM) et Scanning Spreading Resistance Microscopy (SSRM) pour la caractérisation électrique de nanofils de ZnO avec l'objectif d'en déterminer le dopage par profilage des porteurs libres suite à des essais de dopage de type p. Afin de pouvoir utiliser un référentiel planaire nécessaire à ces mesures par sonde locale, un procédé de remplissage par dip-coating et de polissage a été spécialement développé sur des champs de nanofils quasi-verticaux. De plus, dans le but de parvenir à un étalonnage des mesures SCM et SSRM, nous avons conçu et fait fabriquer des échantillons étalons de dopage de type n, contenant des niveaux de Ga en escalier de densité variable de 2×10^17 à 3×10^20 cm^-3. Les mesures sur des coupes transversales de ces deux de structures multicouches ont permis, pour la première fois sur ZnO d'établir un étalonnage des mesures SCM et SSRM et de déterminer le dopage intrinsèque électriquement actif de couches 2D nanométriques, résultat difficilement atteignable par d'autres techniques d'analyse. Des résultats inattendus de concentration résiduelle de porteur de l'ordre de 2×10^18 et 3×10^18 cm^-3 ont été trouvés sur les nanofils de ZnO crus par MOCVD et par CBD respectivement. Outre la caractérisation électrique microscopique des nanofils par SCM et SSRM, des techniques macroscopiques classiques ont été utilisées pour caractériser des assemblées importantes de nanofils de ZnO. L'origine de la difference entre les résultats de deux genres de technique a été discutée. Nous avons aussi étudié les effets des dopages ex-situ par diffusion du phosphore (procédé SOD) et des dopages in situ par incorporation d'antimoine (Sb) pendant la croissance MOCVD. Les résultats majeurs sont obtenus pour l'antimoine, en utilisant des couches ZnO: Sb 2D et des nanofils cœur-coquille ZnO/ZnO: Sb, ou l'hypothèse d'une compensation partielle du dopage n résiduel par un centre accepteur créé par le dopage Sb semble pouvoir être établie raisonnablement. / Based on atomic force microscope (AFM), scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) have demonstrated high efficiency for two dimensional (2D) electrical characterizations of Si semiconductors at nanoscale and then have been extensively employed in Si-based structures/devices before being extended to the study of some other semiconductor materials. However, ZnO, a representative of the third generation semiconductor material, being considered a promising candidate for future devices in many areas, especially in opto-electronic area, has rarely been addressed. Recently, extensive research interests have been attracted by ZnO NWs for future devices such as LED, UV laser and sensor. Therefore, a good understanding of electrical properties of the NWs is in need. In this context, this thesis work is dedicated to the 2D electrical characterization of ZnO NWs with the focus of carrier profiling on this kind of nanostructure in the effort of their p-type doping. For this purpose, a planarization process has been developed for the NWs structure in order to obtain an appropriate sample surface and perform SCM/SSRM measurements on the top of the NWs. For quantitative analysis, Ga doped ZnO multilayer staircase structures were developed serving as calibration samples. Finally, residual carrier concentrations inside the CBD and MOCVD grown ZnO NWs are determined to be around 3×10^18 cm^-3 and 2×10^18 cm^-3, respectively. The results from SCM/SSRM characterization have been compared with that from macroscopic C-V measurements on collective ZnO NWs and the differences are discussed. In addition to carrier profiling on NWs structure, applications of SCM/SSRM on some other ZnO-based nanostructures are also investigated including ZnO:Sb films, ZnO/ZnO:Sb core-shell NWs structure, ZnO/ZnMgO core-multishell coaxial heterostructures.
182

教科書產業有效導入ERP的成功因素及成效探討--以K公司為例

蔡其修 Unknown Date (has links)
企業要提昇營運管理績效及核心競爭力,除了組織及流程改造外,改變作業管理方式,精進e化管理模式,亦是不可或缺的解決方案之一。而企業導入資訊系統更是為因應這變動劇烈的產業競爭環境必備的條件之一。 K公司因營運範疇急速擴增,事業版圖擴及大陸,卻面臨原來所使用的AS400系統,已無法快速且精確的揭露財務報表,及面臨嚴峻之經營挑戰。為解決此一問題,該公司透過經營管理委員會之投資審議機制,形成導入企業資源規劃(Enterprise Resource Planning,ERP)之決策。ERP系統係將企業內部各事業體、各部門,以資訊科技,企業內部大小系統,整合在一起,將所有的資訊能在線上即時揭露,由於資訊的透明化、即時化,使K公司能達成立即反應規劃的目標,並將所有的營運資訊納為決策資訊。 企業建置ERP系統,將會付出相當可觀的軟體費用和顧問諮詢費用,且在人力成本上,若事先未溝通清楚,而引進新系統,將會使企業內部員工或主管產生抗拒與適應不良,這些有形或無形的成本,身為企業主或高階經營者均必須審慎考量,既然導入成本很高,管理者更應慎思:「ERP系統是否可以提升企業的營運績效與競爭力」。 爰此,K公司在專案導入過程中,從專案評估、籌備、流程設計、系統設定階段、系統上線等五大導入過程,均是環環相扣且是綿密的,以及應用專案管理九大領域之要領,使專案能如期如質成功導入。 本研究主要針對K公司導入SAP/ERP系統,瞭解其成功關鍵因素為: 一、考量最佳流程,而非用舊流程套新系統 是要避免將系統AS400化,亦即不是用SAP做到原來AS400中舊系統的作業流程,而是要學習SAP系統中的流程實務,思考最佳的作業模式。 二、分析系統關連圖,找出完善業務的IT建置。 透過整個資訊的關連圖,需進一步找到更多需整合或開發的細節,讓ERP系統的管理幅度能夠涵蓋所有的企業流程。 三、分階段讓主管受益,降低導入阻礙 為了與使用單位主管溝通,專案經理及關鍵使用者(Key User),對主管簡報與分享經驗,讓主管能感受到系統的預期效益。 四、有系統解決問題,而非見招拆招 系統成功上線後,並非導入已經結束,而是將工作重新從系統建置及導入時程與品質的確保,移轉到ERP系統的調教,並持續推動ERP基礎工程,研討的系統改進。 並就企業導入ERP後,在作業面及人力成本與營運管理之改善成效與成功關鍵因素進行實證研究,研究方法係採用AHP方法來驗證軟(硬)體,顧問團隊之系統評選與人為評選之差異,與個案訪談的方式來進行研究,探討導入ERP系統是否提升企業營運改善成效之差異。 本研究之結論:透過ERP系統導入確實可以使K公司從「印量預測」到「生產交貨」至「財報揭露」改善成效更具體。
183

生質燃料補貼在WTO協定下相關適用之法律問題—以SCM協定與農業協定為中心 / The Legal Analysis of Biofuels Subsidies under the WTO Agreements—in Particular the SCM Agreement and the Agriculture Agreement

羅錦嵐, Lo, Chin-Lan Unknown Date (has links)
自從「京都議定書」在2005年2月16日經160個國家簽署生效後,為兼顧環境保護及經濟發展,各國政府便開始鼓勵其國內能源產業發展生質燃料作為替代燃料,以減少溫室氣體排放。然生質燃料產業起步階段,因技術與市場交易機制均未成熟,故有賴政府的補貼才能順利推廣。是以,目前生質燃料的補貼是否應受到WTO協定之規範仍是備受爭議,而實有討論與研究之必要。 本論文主要研究目的,遂在分析目前德國、美國、巴西等主要生質燃料生產國為鼓勵、推廣生質燃料產業之發展,其獎勵措施所涉及的補貼是否會對未受補貼的國內外競爭者形成不公平待遇,以及是否違反WTO補貼暨平衡稅措施協定及農業協定補貼規範的情形,以政策事實套法律要件的方式,深入討論現階段各國生質燃料補貼措施:市場保證、價格補貼、投資補貼、稅賦優惠四種措施態樣,在和平條款落日後,於生質燃料製程上游、中游、下游的協定管轄情形與適法性,以期對目前生質燃料補貼政策作一完整的評估與建議。 / Since the Kyoto Protocol was signed by 160 countries and entered into forced on 16 Feburauy 2005, the governments of above countries began encouraging their enery industries to develop biofuels as substitute to reduce green house gases in pursuit of environmental protection and economic development. While the technologies and trading mechanisms of biofuel industries were immature at the preliminary stage, the prevalence of the biofuels will be dependent on government subsidies. Therefore, whether biofuels subsidies shall be subject to the rules of WTO Agreements is still a controversial issue and needs to be discussed and studied. The main purpose of the thesis is to analyze the domestic policies and incentives of those key biofuel-producuing countries such as Germany, United States and Brazil, and find if such subsidizing measures constitute unfair treatments to foreign compeitiors and violate the SCM Agreement or Agriculture Agrmment under the WTO. In order to conduct a comprehensive analysis and come up with feasible suggestions, the thesis will take the four main incentives, the so-called“Market Assurance”, “Price Support”, “Investment Support”and “Tax credit”as facts to conduct legal analysis as well as discuss the applicability of agreements when Peace Clause came to an end and analyze the legality of each incentive from upstream to downstream of the biofuel production process.
184

[en] ANALYSIS SCOPE AND GUIDELINES PROPOSAL OF A COLLECTION AND TREATMENT LOGISTIC SYSTEM FOR SOLID WASTE IN SLUMS AREAS IN HARMONY WITH GRSCM PRECEPTS / [pt] ANÁLISE E PROPOSTA DE DIRETRIZES PARA UM SISTEMA LOGÍSTICO DE RECOLHA E BENEFICIAMENTO DOS RESÍDUOS SÓLIDOS PARA ÁREAS DE FAVELA EM SINTONIA COM OS PRECEITOS DO GRSCM

BRUNO DUARTE AZEVEDO 30 August 2010 (has links)
[pt] O gerenciamento de resíduos sólidos tornou-se um tema de preocupação para administradores públicos de todo o mundo. O aumento no nível de consumo, somado ao uso indiscriminado de materiais descartáveis, despertou na opinião pública movimentos que cobram das empresas uma nova postura referente à preservação dos recursos naturais. O Green Supply Chain Management - GrSCM, surge como uma nova forma de gerenciamento da cadeia de suprimentos que leva em conta todo o ciclo de vida do produto, desde a extração de suas matérias-primas, até sua disposição final. Uma vez que a aplicação deste conceito ainda é incipiente, o presente trabalho inicialmente apresenta uma abordagem das principais definições descritas na literatura para os termos ligados ao GrSCM. Em seguida, a partir de um diagnóstico que referencia a situação dos resíduos sólidos na comunidade da Rocinha, uma favela no Município do Rio de Janeiro, propõe diretrizes gerais para um sistema logístico de recolha e beneficiamento destes resíduos (com destaque aos recicláveis) para áreas de favela em geral, buscando medidas práticas de aplicação do conceito de GrSCM em locais de ocupação irregular e pobreza acentuada. As diretrizes foram traçadas sob três perspectivas: a dos empresários geradores dos produtos; a dos moradores e organizações locais e a dos órgãos públicos e instituições responsáveis pela coleta e limpeza da região. Como conclusão, defende-se que para o bom funcionamento de um sistema de gerenciamento de resíduos a partir da aplicação do GrSCM em realidades tão complexas, governo e empresas privadas devem ser parceiros e atuar de forma coordenada. Cabe ainda aos moradores e organizações locais, o dever de cobrar, adotar, fiscalizar e promover ações que visem o bem estar do local onde vivem. / [en] Municipal solid waste management (MSCM) has become a topic of concern for public administrators all over the world. The increase in the level of consumption added to the indiscriminate use of disposables, gave rise to public opinion movements that require new approaches from companies in order to preserve the natural resources. The Green Supply Chain Management (GrSCM) emerges as a new way of managing the supply chain that takes into account the whole life cycle of the product, from the extraction of raw materials to its correct final disposal. Since the application of this concept is still new, this dissertation initially defines the main terms related to the GrSCM described in the literature. Following, based on MSW data obtained on the Rocinha community, in the Rio de Janeiro municipality, general guidelines of a logistic system for the collection and processing of waste (with emphasis on recycling) in slum areas aiming to achieve practical measurements for the application of the GrSCM concept are proposed. These guidelines were drawn from three perspectives: that of the entrepreneurs that generate the goods; that of the residents and local organizations; and that of the public agencies and institutions responsible for collecting and cleaning the area. In conclusion, it is argued that for the proper functioning of a MSW management system in complex neighborhoods based on the application of GrSCM, government and entrepreneurs must be partners and act in a coordinated manner. Besides, the residents and local organizations must adopt, promote and monitor actions that aim the welfare of the local where they live.
185

A Total Cost Approach to Supply Chain Risk Modeling

Saunders, Brian J. 08 December 2011 (has links)
The modern supply chain is long, complex, interconnected and global, and plays a fundamental role in business competitiveness. These conditions, along with various supply chain management trends in recent years have increased risks in supply chains which threaten supply chain performance. Greater impact, especially on cost, from an increased threat of supply disruptions is one area of particular concern. Companies today are struggling to find effective means to manage this increased risk and avoid adverse financial impacts. An approach to managing supply disruption risk in supply chains based on the minimization of the total cost of ownership (TCO) of the supply chain is explored in this thesis. Insights are provided into an appropriate view of supply chain risk and a general four step risk management process to guide the design and evaluation of a new risk management tool based on such an approach. A prototype of the new total cost-based, modeling and simulation tool was created in partnership with ProModel Corporation and a government contractor that requested to remain anonymous. A preliminary assessment of the effectiveness of this tool in minimizing TCO and providing an interface useable by non-modelers is provided. This study also reviews and compares a sample set of current supply chain risk management methods and tools and compares them with the new tool for relevance in aiding users in managing supply disruption risk. Based on literature findings and preliminary feedback from pilot contextual demonstrations of the tool, the total cost approach to risk modeling appears promising, although the execution needs to be improved with further enhancements made to the prototype tool. In this preliminary study and evaluation, sufficient evidence is not available to determine that the new prototype tool is any more effective than other currently available risk management tools to provide necessary information to make supply chain risk management decisions that minimize TCO of a supply chain. Suggestions for further development of the tool, especially for improvement of the total cost approach, are provided as well as a preliminary evaluation procedure and survey instruments for a more robust evaluation of the new tool.
186

半導體產業供應鏈網路資源分配模式之研究 / The Model of Resources Allocation in Supply Chain Network for Semiconductor Industry

徐豐祺, Hsu, Feng-Chi Unknown Date (has links)
半導體生產的流程可分成四階段:晶圓生產(fabrication)、測試分類(sorting)、封裝(assembly)與檢驗(testing)。每個階段都有不同的廠商可提供服務。當晶圓生產廠商接獲訂單,其供應鍊管理者會根據產能、需求量、交貨日、技術水準與成本等考慮因素,決定此訂單應由何晶圓廠區生產、由何測試分類廠做分類、由何封裝廠做封裝與最後由何檢驗廠做檢驗。本研究的主要目的為在各種限制條件下,以最小成本為目標,找出完成客戶訂單的最佳廠商組合。可能的限制包括產能限制、交貨日的滿足、各廠區的技術水準及需求量的大小。本問題可視為產品組合、廠商組合與生產排程的綜合問題,過去常用的解決方法為整數與線性規劃的混合應用,但是由於牽涉的因素太多,常常問題的模式中變數與限制式過多導致無法解決。本研究先以資料的收集與模式的建構為主,利用並修改現有的產品結構樹模型使其變成供應鏈網路模式,並加入半導體產業供應鏈相關特性,建立一個以時間軸為機制的混合整數線性模式。並且以時間成本的概念來衡量整個半導體供應鏈的效能。 混合整數線性模式常會面臨許多問題,由於模式的複雜,變數與限制式過多,造成求解的困難。對電腦資源的需求很大,花費的時間也很長。同時對於問題的規模亦造成制限。於是本研究藉著修改Kim (1995) 的 backward list scheduling 演算法概念,建構一個解決問題的啟發式演算法,可快速求得一組近似最佳解之可行解。 由於供應鏈所面對的是隨機環境,因此必須以模擬的方式對上述模型進行檢驗,確認其有效性及適用的範圍。利用系統模擬方法,確定隨機變數與其分配,以建立模擬模型程式。實際進行模擬,以驗證上述供鏈模型之有效性,並瞭解、分析模型之適用性及應用方式。 對於半導體產業供應鏈廠商指派與資源分配之網路管理方面,提供一數量化的思考邏輯。運用數量化的模式表現出不同的半導體產業供應鏈廠商指派與資源分配之網路管理的問題,並提出解決問題的演算機制。
187

Soft Matter : Routes To Rheochaos, Anomalous Diffusion And Mesh Phases

Ganapathy, Rajesh 09 1900 (has links)
Soft condensed matter (SCM) systems are ubiquitous in nature. SCM systems contain mesoscopic structures in the size range 10 nm to 1 am that are held together by weak entropic forces. These materials are therefore easily perturbed by external fields such as shear, gravity and electric and magnetic fields and are novel systems for studying non-equilibrium phenomena. The elastic constants of these materials are ≈ 109 times smaller than conventional atomic fluids and hence it is possible to measure the viscoelastic response of these materials using commercial instruments such as rheometers. The relaxation time in SCM systems are of the order of milliseconds as compared to atomic systems where relaxation times are of the order of picoseconds. It is easy to study the effect of shear on SCM, as the shear rates attainable by commercial rheometers are of the order of the inverse of their relaxation times. The dynamics of SCM systems and their local rheological properties obtained using the method of probe diffusion can be quantified through dynamic light scattering experiments. The structure of SCM systems can be quantified using diffraction techniques such as small angle x-ray scattering. In this thesis we report experimental studies on the linear and nonlinear rheology and the dynamics of surfactant cetyltrimethylammonium tosylate (CTAT), which forms cylindrical wormlike micelles, studied using bulk rheology and dynamic light scattering (DLS) technique, respectively. We have also studied the phase behaviour of the ternary system formed by cetyltrimethylammonium 3-hydroxy-napthalene 2-carboxylate (CTAHN), sodium bromide (NaBr) and water using small angle x-ray scattering (SAXS). In Chapter 1, we discuss why SCM systems are suitable for studying non-equilibrium phenomena such as the effect of shear on the structure and dynamics of condensed matter. This is followed by a discussion on the chemical structure, phase behaviour and self assembling properties of the amphiphilic molecules in water. We then discuss the intermacromolecular forces such as van der Waals interaction, the screened Coulomb repulsion and hydrophobic and hydration forces. The systems that have been the subject of our experimental studies, viz. CTAT and CTAHN/NaBr/water have also been discussed in detail. This is followed by a theoretical background of linear and nonlinear rheology, dynamic light scattering and small angle x-ray scattering techniques. Next we describe the stress relaxation mechanisms in wormlike micelles. This is followed by a discussion on some standard techniques of nonlinear time series analysis, in particular the evaluation of the delay time L, the embedding dimension m, the correlation dimension ν and the Lyapunov exponent λ. We have also mentioned a few examples of experimental systems where chaos has been observed. We have also discussed in detail the various routes to chaos namely, the period-doubling route, the quasiperiodic route and the intermittency route. The concluding part of this chapter summarises the main results of the thesis. Chapter 2 discusses the experimental apparatus used in our studies. We have discussed the different components of the MCR-300 stress-controlled rheometer (Paar Physica, Germany). The rheo-small angle light scattering experiments and the direct visualisation experiments done using a home-made shear cell are also discussed. Next we describe the various experiments that can be done using a commercial rheometer. The frequency response and flow experiments have been discussed with some examples from our own work on entangled, cylindrical micelles. This is followed by a discussion on the various components of our dynamic light scattering (DLS) setup (Brookhaven Instruments, USA). Particle sizing of submicrometer colloidal spheres using our DLS setup has been discussed with an example of an angle-resolved DLS study of 0.05µm polystyrene colloids. Next we describe the various components of the SAXS setup (Hecus M. Braun, Austria). As an example application of SAXS we have quantified the structure of the lamellar phase formed by the surfactant CTAHN/water. We finally describe the sample preparation methods employed by us for the different experiments. Our nonlinear rheology experiments on viscoelastic gels of surfactant CTAT (cCT AT= 2wt%) in the presence of salt sodium chloride (NaCl) at various concentrations has been discussed in Chapter 3. We observe a plateau in the measured flow curve and this is attributed to a mechanical instability of the shear banding type. The slope of this plateau can be tuned by the addition of salt NaCl. This slope is due to a concentration difference between the shear bands arising from a Helfand-Fredrickson mechanism. This is confirmed by the presence of a “Butterfly” light scattering pattern in SALS experiments performed simultaneously with rheological measurements. We have carried out experiments at six different salt concentrations 10mM < cN aCl<1M, which yield plateau slopes (α) ranging from 0.07 < α < 0.4. We find that a minimum slope of 0.12, corresponding to a salt concentration of 25mM NaCl, is essential to see a “Butterfly” pattern indicating the onset of flow-concentration coupling at this α value. After this we turn our attention to stress/shear rate relaxation experiments. The remainder of this chapter is split in four parts. We show in Part-I that the routes to rheochaos in stress relaxation experiments is via Type-II intermittency. Interestingly in shear rate relaxation, the route is via Type-III intermittency. We also show that flow-concentration coupling is essential to see the route to rheochaos. This section also brings out the crucial role played by orientational ordering of the nematics during rheochaos using SALS measurements performed simultaneously with rheological measurements. In part-II, we study the spatio-temporal dynamics of the shear induced band en route to rheochaos. Our direct visualisation experiments show that the complex dynamics observed in stress/shear rate relaxation measurements during the route to rheochaos is a manifestation of the spatio-temporal dynamics of the high shear band. In part-III, we describe the results of our stress/shear rate relaxation measurements at a fixed shear rate/stress with temperature as the control parameter and thereby control the micellar length. We see the Type-II intermittency route to rheochaos in stress relaxation measurements and the Type-III intermittency route to rheochaos in shear rate relaxation measurements. We conclude this section by showing the results of linear rheology measurements carried out at different temperatures. We estimate the mean micellar length ¯L, reptation time τrepand the breaking time τbreak. We show that L¯ increases by ≈ 58%, as the sample goes through the route to rheochaos. In Part-I of this chapter we had only qualitatively discussed the correlations between the measured time series of stress and the VH scattered intensity during the Type-II intermittency route to rheochaos. In part-IV we have attempted to quantify the correlations between the two time series using the technique of linear and nonlinear Granger causality. We have also studied the phase space dynamics of the two time series using the technique of Cross Recurrence Plots. We show that there exists a causal feedback mechanism between the stress and the VH intensity with the latter having a stronger causal effect. We have also shown that the bivariate time series share similar phase space dynamics using the method of Cross Recurrence Plots. In chapter 4, we have studied the dynamics of wormlike micellar gels of surfactant CTAT using the DLS technique. We report an interesting result in the dynamics of these systems: concentration fluctuations in semidilute wormlike-micelle solutions of the cationic surfactant Cetyltrimethylammonium Tosylate (CTAT) at wavenumber q have a mean decay rate α qz, with z -̃1.8, for a wide range of surfactant concentrations just above the overlap value c∗. The process we are seeing is thus superdiffusive, like a L´evy flight, relaxing on a length scale L in a time of order less than L2 . The rheological behaviour of this system is highly non-Maxwellian and indicates that the micelle-recombination kinetics is diffusion-controlled (DC) (micelles recombine with their original partners). With added salt (100mM NaCl) the rheometric behaviour turns Maxwellian, indicating a crossover to a mean-field (MF) regime (micelles can recombine with any other micellar end). The concentration fluctuations, correspondingly, show normal diffusive behaviour. The stress relaxation time, moreover is about twenty times slower without salt than with 100mM NaCl. Towards the end of this chapter, we propose an explanation of these observations based on the idea that stress due to long-lived orientational order enhances concentration fluctuations in DC regime. In the previous chapter we had studied the dynamics of wormlike micellar gels of pure CTAT 2wt% and found superdiffusive relaxation of concentration fluctuations due to a nonlinear coupling of long-lived stress and orientational fluctuations to the con- centration. In chapter 5 we present results from dynamic light scattering experiments to quantify the diffusive motion of polystyrene (PS) colloids in the same system. This chapter is split in two parts. In Part-I, we discuss dynamics of PS particles of radius 115 nm and 60 nm in CTAT 2wt%. The radius of the colloidal spheres is comparable to the mesh size ξ = 80 nm of the wormlike micellar network and hence we are probing the network dynamics. We find that ∆r2(t) is wavevector independent at small and large lag times. However at intermediate times, we find an anomalous wavevector dependence which we believe arises from the rapid restructuring of the gel network. This anomalous wavevector dependence of ∆r2(t) disappears as the temperature is increased. In Part-II we discuss the dynamics of PS particles of radius 25 nm and 10 nm, smaller than ξ, in CTAT 1wt% & 2wt%. We once again find an anomalous wavevector dependence of ∆r2(t) at intermediate times for the 2wt% sample. Surprisingly, at large times the particle motion is not diffusive, rather ∆r2(t) saturates. We do not have a clear understanding of this as yet. Also for the 10 nm particle, the motion at small lag times is superdiffusive. The motion of these particles is probably influenced by the superdiffusion of concentration fluctuations observed in pure CTAT 2wt% system (chapter 4). In chapter 6, we report the observation of an intermediate mesh phase with rhom- bohedral symmetry, corresponding to the space group R¯3m, in the ternary system consisting of CTAHN/NaBr/water. It occurs at lower temperatures between a random mesh phase (LDα ) and a lamellar phase (Lα) on increasing the surfactant concentration φs. The micellar aggregates, both in the intermediate and random mesh phases, are found to be made up of a two-dimensional network of rod-like segments, with three rods meeting at each node. SAXS studies also show the presence of small angle peaks corresponding to ad−spacing of 25 nm. Freeze fracture electron microscopy results shows that this peak may correspond to the presence of nodule like structures with no long-range correlations. The thesis concludes with a summary of main results and a brief discussion of the scope for future work in Chapter 7.
188

The impact of a real-time IT-Logistics solution : Implementation effects and consequences

Abdiu, Daniel, Strandberg, Mikael, Stridsberg, Martin January 2005 (has links)
<p>Today’s business market is highly competitive, therefore companies need to be constantly updated and change the way they operate their business, in order to survive and remain competitive. The situation on today’s market requires that companies have the ability to quickly respond to market changes and new customer demands within short product lifecycles. In order to deal with this new market situation, companies need to improve the integration with other companies within their business. This integration facilitates the companies’ ability to quickly adapt to new market situations and survive on a fast changing market. One of the main underlying concepts of this collaborative commerce is Supply Chain Management (SCM) which integrates and coordinates a company’s processes both internally and externally. Information Technology (IT) could improve the effectiveness of SCM. IT-solutions make the business processes more effective and improves the integration with other actors within the supply chain. The purpose with this thesis is to describe and explain the effects for businesses and the consequences for its processes when implementing a real-time IT-Logistics solution together with identifying the critical success factors. The thesis has been conducted by studying theory regarding supply chain management, business renewal and implementation effects. Further, a case study has been conducted where three actors have been interviewed; a manufacturer (Volvo Powertrain), a subcontractor (Metallfabriken Ljunghäll AB) and a system developer (PipeChain). The analysis of the theoretical framework and the empirical research has contributed with an identification of major effects and consequences when implementing a real-time IT-Logistics solution. Some of the effects are: inventory reduction, higher delivery accuracy, improved relations and increased flexibility. Examples of consequences these effects have caused are: more accurate planning and production, effective production processes as well as an improved delivery process. Additionally, success factors for an implementation have been identified such as mutual trust, understanding of change and evaluation.</p> / <p>Konkurrensen är stor inom dagens affärsmarknad vilket medför att företag ständigt måste vara uppdaterade och förändra deras affärsverksamhet för att kunna överleva och vara konkurrenskraftiga på marknaden. Dagens marknadssituation erfodrar att företag snabbt kan reagera på marknadsförändringar och nya kundkrav vid allt kortare produktlivscyklar. För att företag skall kunna hantera denna nya marknadssituation måste företagen bli integrerade med varandra inom deras affärsområde. Denna integrering underlättar företagens förmåga att snabbt kunna anpassa sig till nya marknadssituationer och överleva på en snabbt föränderlig marknad. Ett utav de största grundläggande koncepten för denna integrering är flödeshantering (Supply Chain Management). Flödeshanteringen integrerar och koordinerar företagets processer både internt som externt. Informationsteknologi (IT) kan förbättra effektiviteten av flödeshanteringen. IT-lösningar skapar effektivare affärsprocesser och förbättrar integrationen med andra aktörer inom företagets försörjningskedja. Syftet med uppsatsen är att beskriva och förklara effekter för affärsverksamheten samt konsekvenser för dess affärsprocesser, vid en implementering av en realtidslogistiklösning. Uppsatsen syftar vidare till att identifiera framgångsfaktorer vid en sådan implementering. Uppsatsarbetet har genomförts genom en litteraturstudie där teori om flödeshantering, affärsförändring och implementationseffekter har behandlats. En fallstudie i uppsatsen har använts där tre aktörer har blivit intervjuade; en tillverkare (Volvo Powertrain), en underleverantör (Metallfabriken Ljunghäll) och en systemutvecklare (PipeChain). Analysen av litteraturstudien och den empiriska undersökningen har bidragit till en identifiering av huvudeffekter samt konsekvenser vid en implementering av en IT-logistiklösning. Några av dessa effekter är: lagerreducering, högre leveranssäkerhet, förbättrade relationer samt ökad flexibilitet. Exempel på konsekvenser dessa effekter har orsakat är: precisare planering och produktion, effektivare produktionsprocesser samt förbättrad leveransprocess. Vidare så har framgångsfaktorer för lyckad implementering identifierats så som ömsesidig tillit, förståelse för förändring samt utvärdering.</p>
189

[en] DESIGN OF THE HYDROGEN SUPPLY CHAIN: A METHODOLOGY FOR PLANNING UNDER UNCERTAINTY / [pt] PROJETO DA CADEIA DE SUPRIMENTOS DE HIDROGÊNIO: UMA METODOLOGIA PARA O PLANEJAMENTO SOB INCERTEZA

PAULA MAURICIO NUNES 13 September 2018 (has links)
[pt] Os combustíveis de baixo impacto ambiental estão em destaque na mídia e na sociedade, atualmente. Neste contexto, o hidrogênio, fonte de energia limpa, tem um grande potencial. Entretanto, ainda não existe uma infraestrutura adequada para sua comercialização. O crescimento da demanda por hidrogênio é de difícil previsão, gerando um alto grau de incerteza na definição das necessidades de capacidades futuras de sua rede logística. Esta dissertação propõe uma metodologia para o planejamento do projeto da cadeia de suprimentos de hidrogênio para uso em transporte. Para representar o problema e avaliar diferentes alternativas de investimentos em infraestrutura logística foi desenvolvido um modelo matemático estocástico de dois estágios utilizando programação linear inteira mista (PLIM). O elevado nível de incerteza desta cadeia aumenta a complexidade do modelo, requerendo uma grande quantidade de cenários, inviabilizando sua otimização. Para contornar esta dificuldade, foi utilizada a técnica de aproximação por média amostral (SAA). Esta abordagem gera soluções, cuja qualidade pode ser estatisticamente avaliada utilizando-se um número reduzido de cenários. A metodologia proposta foi aplicada em um estudo de caso com dados reais da cadeia de suprimentos de hidrogênio líquido da Grã-Bretanha. Os gaps de otimalidade gerados nestes testes foram inferiores a 1 por cento, demonstrando a adequação do método desenvolvido. Mesmo com o alto nível de incerteza do problema, o SAA possibilitou definir como, quando, e onde investir. Os resultados obtidos devem contribuir para proporcionar avanços na criação de uma infraestrutura apropriada para a comercialização do hidrogênio. / [en] Nowadays, fuels with low environmental impact are highlighted in media and society. In this context, hydrogen, as a clean energy source, has a great potential. However, there is still no appropriate infrastructure for its commercialization. The prediction of demand for hydrogen is difficult, generating a high degree of uncertainty in the definition of capacity needs in the future for its logistics network. This work proposes a methodology for the design of the hydrogen supply chain for use in transportation. To represent the problem and evaluate alternatives to invest in logistics infrastructure, a two-stage stochastic mixed-integer programming was developed. The high degree of uncertainty in this chain increases the complexity of the mathematical model, requiring a huge number of scenarios which makes its optimization impossible. To overcome this difficulty, the technique of sample average approximation (SAA) is used. This approach generates solutions, whose quality can be statistically evaluated using a reduced number of scenarios. The proposed methodology was tested in a study case with real data from Great Britain s liquid hydrogen supply chain. The optimal gaps generated in these tests were below 1 percent, demonstrating the adequacy of the developed methodology. Even with the high level of uncertainty of the problem, the propose methodology using SAA technique can define how, when, and where to invest. The results should be helpful in advancing the creation of an appropriate infrastructure for hydrogen commercialization.
190

As atividades logísticas no contexto da Gestão da Cadeia de Suprimentos (SCM)

Marchesini, Márcia Maria Penteado 23 February 2011 (has links)
Made available in DSpace on 2016-06-02T19:50:10Z (GMT). No. of bitstreams: 1 3532.pdf: 2375674 bytes, checksum: 8220f9b2a43401bf9ab683fd67209099 (MD5) Previous issue date: 2011-02-23 / Financiadora de Estudos e Projetos / From the Supply Chain Management (SCM), the logistic function expands its scope within the company, going to exert or support the management and operation of key business processes. Its performance leaves to reduce only the functional sphere ( silo or vertical area ), passing to reach horizontal sphere in such processes. Various sources of literature indicate changes in the logistic function but not characterize precisely or discuss the changes in its scope within the company. In particular, the benefits generated by the involvement of the logistic function on key business processes of SCM have been identified in the literature, but were not identified logistic activities that must execute in each of the processes so that these benefits are achieved. In front of this theoretical gap, the objective of this doctorate thesis was to propose logistic activities necessary for the efficacious operation of key business processes of SCM, generating a conceptual framework that assists in implementing these activities. Such a framework is a guide that can help companies identify, characterize and select the activities that the logistic function can develop in their key business processes. More specifically, this conceptual framework presents, besides the own logistics activities, a way of characterizing these activities, according to four criterions: a) obligatoriness of existence in the company (basic or optional), b) impact on the generation of value (efficiency, efficacy and/or differentiation), c) impact on the dimension of logistic service, d) the integration and coordination with other areas or processes. This thesis used the approach of qualitative research, of descriptive character, of exploratory nature and with experimental study of field. The research method was the multi-case study and the mechanism of data collection was the personal interview realized by a semi-structured questionnaire. This research is also of theoretical-conceptual nature, because it developed a conceptual framework generated from the theoretical review. In three case studies realized, observed consistency in the proposed logistic activities and in its form of characterization. Among the 25 proposed activities, the Company 1 realizes 21 of them, the Company 2 realizes 23 activities and the Company 3 realizes all 25 activities, and all interviewed declared that the set of these proposed activities was complete and consistent. / A partir da Gestão da Cadeia de Suprimentos (Supply Chain Management, SCM), a função logística expande seu escopo dentro da empresa, passando a exercer ou dar apoio à gestão e operação dos processos-chave de negócio. Sua atuação deixa de se reduzir somente à esfera funcional ( silo ou área vertical ), passando a alcançar também a esfera horizontal de tais processos. Várias fontes da literatura apontam mudanças na função logística mas não as caracterizam precisamente nem discutem as modificações no seu escopo dentro das empresas. Em particular, os benefícios gerados pelo envolvimento da função logística nos processoschave de negócio da SCM já foram levantados na literatura, mas não foram identificadas as atividades que a logística deve executar em cada um dos processos para que esses benefícios sejam alcançados. Diante desta lacuna teórica, o objetivo desta tese de doutorado foi de propor atividades logísticas necessárias à operação eficaz dos processos-chave de negócio da SCM, gerando uma estrutura conceitual que auxilia na implementação destas atividades. Tal estrutura é um guia que pode auxiliar as empresas na identificação, caracterização e seleção das atividades que a função logística pode desenvolver nos seus processos-chave de negócio. Mais especificamente, esta estrutura conceitual apresenta, além das próprias atividades logísticas, uma forma de caracterização destas atividades, de acordo com quatro critérios: a) obrigatoriedade de existência na empresa (básica ou opcional), b) impacto na geração de valor (eficiência, eficácia e/ou diferenciação), c) impacto na dimensão do serviço logístico prestado, d) integração e coordenação com outras áreas ou processos. Esta tese utilizou a abordagem de pesquisa qualitativa, de caráter descritivo, de natureza exploratória e com estudo experimental de campo. O método de pesquisa foi o estudo multi-caso e o mecanismo de coleta de dados foi a entrevista pessoal realizada por meio de um questionário semi-estruturado. Esta pesquisa também é de natureza teórico-conceitual, pois desenvolveu uma estrutura conceitual gerada a partir de revisão teórica. Nos três estudos de caso realizados, observou-se consistência nas atividades logísticas e na sua forma de caracterização propostas. Dentre as 25 atividades propostas, a Empresa 1 realiza 21 delas, a Empresa 2, 23 atividades e a Empresa 3, todas as 25 atividades, sendo que todos os entrevistados declararam que estava completo e consistente o conjunto proposto dessas atividades.

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