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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.
21

Programação da descarga de navios graneleiros de carvão: um estudo de caso na Companhia Siderúrgica do Pecém. / Schedule for coal bulk carriers discharge: a case study at Companhia Siderúrgica do Pecém.

Carlos Henrique Azevedo Duarte 30 May 2018 (has links)
De acordo com Babu et al. (2015), o carvão mineral é um importante recurso natural devido à sua aplicação em várias atividades econômicas, como geração de energia, produção de aço, fabricação de cimento e produção de combustível líquido. Em função do custo e da baixa qualidade do carvão brasileiro (não coqueificável, na maioria das reservas, com elevado teor de cinzas e baixo poder calorífico), como apontado por Süffert (1997), as empresas brasileiras dos setores siderúrgico e termoelétrico necessitam importar este insumo, por via marítima. O desafio no planejamento da logística de suprimento desta matéria prima é garantir o abastecimento ao mínimo custo de estoque e de espera dos navios. A garantia de abastecimento passa por uma programação adequada da chegada e descarga dos navios. Quando a descarga de navios é uma operação gargalo, é necessário maior cuidado com a programação de recebimento, de maneira com que não haja atrasos, que causem a falta de produto, nem em muita antecipação, que podem significar excessivos tempo de fila para recebimento do material por falta de área para estocagem. Com o objetivo de se programar adequadamente a chegada de navios, de forma a evitar filas muito grandes e desabastecimento foi proposto um modelo de programação de chegada de navios, com base nos dados do complexo de Pecém. Este modelo proposto utilizou um buffer de tempo pré-determinado, que foi testado e validado através de simulação, com objetivo de minimizar os atrasos, de forma que possam ser absorvidos por um estoque de segurança, e as antecipações, de forma que não haja risco de falta de área de estocagem. / According to Babu et al. (2015), coal is an important natural resource due to its application in various economic activities, such as power generation, steel production, cement manufacturing and liquid fuel production. Due to the cost and low quality of Brazilian coal (not coking, in most reserves, with high ash content and low calorific value), as pointed out by Süffert (1997), Brazilian companies in the steel and thermoelectric sectors need to import this input, by sea. The challenge in planning the logistics of supply of this raw material is to guarantee the supply at the minimum cost of inventory and waiting of the ships. The supply guarantee is subject to adequate scheduling of arrival and unloading of ships. When ship unloading is a bottleneck operation, greater care is required with the scheduling of receipt, so that there are no delays, which cause the lack of product, or in much anticipation, that can mean excessive queue time for receiving the shipment material for lack of storage area. In order to properly program, the arrival of ships, in order to avoid very large queues and shortage, a model for the arrival of ships was proposed, based on data from the Pecém complex. This proposed model used a pre-determined time buffer, which was tested and validated through simulation, in order to minimize the delays, so that they can be absorved by a security stock, and the anticipations, so that there is no risk lack of storage area.
22

Studie operativního řízení výroby ve vybrané firmě / The Study of Operational Production Management in Selected Firm

Polívka, Pavel January 2012 (has links)
This thesis deals with operative production management in a chosen company. In the theoretical part of the study are explained the terms of production, production management, operative production management and production planning. This is followed by a brief description and characteristics of a chosen entrepreneurial subject that deals with production of automatic door systems for rail vehicles. The next part of the thesis is aimed at evaluation of operative production management of door leaves current condition with focus on manufacturing programme, production system and production process organisation. Because of the most severe lack of current condition there is an up-to-date analysis in the field of production planning and material flow in time. Based on this analysis there is a sketch of three theoretical approaches to solutions. In the final part of the thesis a brief evaluation of assets and conditions of solutions realization is carried out and there is a recommendation for production management of the company.
23

THE PHOTONIC APPLICATIONS OF FOCUSED ION BEAM MICROMACHINGING ON GaN

CHYR, YEONG-NING 11 October 2001 (has links)
No description available.
24

Organische Photosensoren mit spektraler Anpassung

Jahnel, Matthias Stephan 10 January 2018 (has links) (PDF)
Der Schwerpunkt dieser Arbeit liegt auf der Simulation, Entwicklung und Realisierung organischer Halbleiterbauelemente für Anwendungen im Bereich der Sensorik. Unter dem Gesichtspunkt der Fertigung sollen die organischen lichtemittierenden Dioden (OLEDs) und die organischen Photodioden (OPDs) einfach konzeptioniert sein. Je nach Bauelementetyp stehen für die Herstellung der organischen Schichten die Vakuumtechnologie oder lösungsmittelbasierte Prozesse zur Verfügung. Eine Besonderheit der Arbeit ist die Integration der OLEDs bzw. der OPDs auf Silizium-Substraten. Zudem wird die Integration von optischen Filtern für die OLEDs sowie die Etablierung einer Dünnschichtverkapselung für die OLEDs und OPDs gezeigt. Im ersten Teil der Arbeit wird anhand von Simulationen der Dünnschichtoptik erarbeitet, welche Möglichkeiten vorhanden sind, die Charakteristik der OLEDEmission bzw. die Absorptionseigenschaften der OPDs zu beeinflussen. Die Besonderheit der OLEDs für die Sensorikanwendungen liegt hierbei in der Licht-Emission mit geringen Halbwertsbreiten. Es wird anhand von Fluoreszenzmarkern (Rhodamin 6G und Nah-IR Alzheimer Farbstoff-4) und einem Chromoprotein (PAS-GAF-64) verdeutlicht, welche Möglichkeiten für die Sensorik durch die Anregung mit der OLED bestehen. Für die OPDs hingegen wird gezeigt, welche Möglichkeiten es für das Rodamin 6G gibt, mit dielektrischen Spiegeln die Absorptionseigenschaften so zu beeinflussen, dass die gewünschten spektralen Bereiche des Lichtes absorbiert bzw. reflektiert werden. Der zweite Teil widmet sich der Entwicklung der OLEDs anhand der Integrationsmöglichkeiten der dielektrischen Filter sowie deren Optimierung. Es wird am Beispiel des Rhodamin 6G gezeigt, dass für die OLED-Emission eine Halbwertsbreite von 18 nm beim Maximum von 530 nm hat. Durch die Verwendung von Entlastungsschichten zwischen OLED und dielektrischem Spiegel können die Kennwerte der OLED positiv beeinflusst werden und weiterhin werden das Temperaturverhalten der OLEDs sowie die Verspannungseigenschaften der dielektrischen Schichten betrachtet. Darüber hinaus steht im dritten Teil die Entwicklung der organischen Photodioden im Fokus. Hierbei wurden OPDs auf Glas- und Siliziumsubstraten gefertigt. Inhalt der Entwicklung auf Glassubstraten ist die Variation der absorbierenden Schicht und deren Einfluss auf die elektro-optischen Eigenschaften. Die Entwicklung der OPDs auf Siliziumsubstraten basiert auf der Integration sowie der Optimierung verschiedener Absorbersysteme, einer alternativen Anode und Kathode sowie der Integration einer Dünnschichtverkapselung. Im Ergebnis wurden OPDs entwickelt, die ohne Dünnschichtverkapselung einen Photonen-zu-Elektron-Umwandlungs-wirkungsgrad (IPCE) von ca. 37 % bei 550 nm haben. Der IPCE konnte zudem durch die Modifikation des Kathodenaufbaus um 4 % gesteigert werden. Die OPD-Bauelemente mit integrierter Dünnschichtverkapselung zeigen einen IPCE von ca. 33 % bei 550 nm. Weiterhin wurde die Methode der orthogonalen Photolithographie zur Strukturierung der OPDs verwendet und es erfolgte der Übertrag der OPD-Technologie auf 8-Zoll-Halbleitersubstrate. In diesem Zusammenhang sind zur Bewertung von Einflüssen, wie Wasser oder Sauerstoff, Untersuchungen zur Lebensdauer der OPDs durchgeführt worden. Die Kenntnis über den Einfluss der orthogonalen Photolithographie auf die Kennwerte der OPDs sowie der Einfluss der Dünnschichtverkapselung auf die Eigenschaften der OPDs und OLEDs sind essentiell für weitere Entwicklungen und zur Fertigung von Sensoranwendungen. / This work focuses on the simulation, development and implementation of organic semiconductor devices for applications in the field of sensor technology. From the viewpoint of manufacturing, organic light emitting diodes (OLEDs) as well as organic photodiodes (OPD) should be designed simply. Depending on the type of device vacuum technology or solvent-based processes are available for producing organic layer. A special feature of OLED- and OPD-devices is the integration on silicon substrates. In addition, the integration of optical filters for OLED-devices and the thin-film encapsulation of OLEDs and OPDs is shown. The first part of the work elaborates on simulations of thin film optics, describing options to control the characteristics of the OLED-emission or the absorption properties of the OPD. A special characteristic of OLEDs is the light emission with a small full with half maximum for sensor applications. By using of fluorescent markers Rhodamine 6G and near-IR dye Alzheimer-4 or the Chromoproteins (PAS-GAF-64) clarifies the possibilities for sensors by excitation with the OLED. In contrast, for the OPD is shown which solutions are available, to influence the absorption properties of Rhodamin 6G with dielectric mirrors so that desired spectral ranges of light are absorbed or reflected. The second part is dedicated to the development of OLEDs based on integration of dielectric filters and their optimization. It is shown by the example of Rhodamine 6G that the OLED emission represents a full with at half maximum of 18 nm at 530 nm. Furthermore, the temperature behavior of the OLEDs and the strain properties of the dielectric layers are considered. Organic photodiodes are in the focus of the third part of the development. These OPDs were made on glass and silicon substrates. The main objective of the development on glass substrates is the variation of the absorption layer and its influence to the electro-optical properties to increase the spectral sensitivity of the OPD. The development of OPD on silicon substrates deals with the integration and optimization of different absorber systems, an alternative anode and cathode as well as the integration of a thin-film encapsulation. As a result, the OPDs without a thin-film encapsulation have an incident photon-to-electron conversion efficiency (IPCE) of about 37 % at 550 nm. The IPCE was increased to 4 % by modifying the cathode structure. The OPD devices with integrated thin-film encapsulation showed an IPCE of about 33 % at 550 nm. Furthermore, the method of orthogonal photolithography was used to pattern the OPD and an upscaling of the OPD technology to 8-inch semiconductor substrates have been realized. In this context studies have been carried out to evaluate the influence of process and encapsulation to the lifetime of OPDs. The knowledge about the influence of the orthogonal photolithography to the characteristics of OPDs and the influence of the thin-film encapsulation on the properties of OPD and OLEDs is essential for further development and for the manufacturing of sensor applications.
25

Performance Evaluation of Opportunistic Routing Protocols for Multi-hop Wireless Networks

Guercin, Sergio Rolando 15 March 2019 (has links)
Nowadays, Opportunistic Routing (OR) is widely considered to be the most important paradigm for Multi-hop wireless networks (MWNs). It exploits the broadcast nature of wireless medium to propagate information from one point to another within the network. In OR scheme, when a node has new information to share, it rst needs to set its forwarding list which include the IDs and/or any relevant information to its best suited neighboring nodes. This operation is supported by the use of appropriate metrics. Then, it executes a coordination algorithm allowing transmission reliability and high throughput among the next-hop forwarders. In this paper, we provide a comprehensive guide to understand the characteristics and challenges faced in the area of opportunistic routing protocols in MWNs. Moreover, since the planet we live on is largely covered by water, OR protocols have gained much attention during the last decade in real-time aquatic applications, such as oil/chemical spill monitoring, ocean resource management, anti-submarine missions and so on. One of the major problems in Underwater Wireless Sensor Network (UWSNs) is determining an e cient and reliable routing methodology between the source node and the destination node. Therefore, designing e cient and robust routing protocols for UWSNs became an attractive topic for researchers. This paper seeks to address in detail the key factors of underwater sensor network. Furthermore, it calls into question 5 state-of-the-art routing protocols proposed for UWSN: The Depth-Based Routing protocol (DBR), the Energy-E cient Depth-Based Routing protocol (EEDBR), the Hydraulic-pressure-based anycast routing protocol (Hydrocast), the Geographic and opportunistic routing protocol with Depth Adjustment for mobile underwater sensor networks (GEDAR), and the Void- Aware Pressure Routing for underwater sensor networks (VAPR). Finally, it covers the performance of those protocol through the use of the R programming language.
26

Long-Wavelength Vertical-Cavity Lasers : Materials and Device Analysis

Mogg, Sebastian January 2003 (has links)
Vertical-cavity lasers (VCLs) are of great interest as lightsources for fiber-optic communication systems. Such deviceshave a number of advantages over traditional in-plane laserdiodes, including low power consumption, efficient fibercoupling, on-chip testability, as well as potential low-costfabrication and packaging. To date, GaAs-based VCLs operatingat 850 nm are the technology of choice for short-distance,high-speed data transmission over multimode fiber. Forlong-distance communication networks, long-wavelength (LW) VCLsoperating in the 1.3 and 1.55-&#956m transmission windowsof standard singlemode fibers are desired. However, despiteconsiderable worldwide development efforts, the commercialbreakthrough of such devices has still to be achieved. This ismainly due to shortcomings of the intrinsic material propertiesof InP-based material systems, traditionally employed in LWlaser diodes. While LW quantum well (QW) active regions basedon InP are well established, efficient distributed Braggreflectors (DBRs) are better built up in the AlGaAs/GaAsmaterial system. Therefore, earlier work on LW VCLs has focusedon hybrid techniques such as bonding between InP-based QWs andAlGaAs/GaAs DBRs using waferfusion. More recently, however, themain interest in this field has shifted towards all-epitaxialGaAs-based devices employing novel 1.3-&#956m activematerials with strained GaInNAs QWs as one of the mostpromising candidates. The main focus of this thesis is on the characterization andanalysis of LW VCLs and building blocks thereof, based on bothInP and GaAs substrates. This includes a theoretical study on1.3-&#956m InGaAsP/InP multiple QW active regions, as wellas an experimental investigation of novel, highly strained1.2-&#956m InGaAs/GaAs single QWs. Two high-accuracyabsolute reflectance measurement setups were built for thecharacterization of various DBRs. Reflectance measurementsrevealed that n-type doping is much more detrimental to theperformance of AlGaAs/GaAs DBRs than previously anticipated.Near-room temperature operation of a single-fused1.55-&#956m VCL with an InP/InGaAsP bottom DBR wasobtained. A thermal analysis of this device structure clearlyindicated its limited capabilities in terms of high-temperatureoperation. As a result, further efforts were directed towardsall-epitaxial GaAs-based VCLs. Record-long emission wavelengthsto above 1260 nm were obtained from InGaAs VCLs based on anextensive gain–cavity detuning. These devices showed verypromising performance characteristics in terms of thresholdcurrent and light output power, indicating good potential forbeing a viable alternative to GaInNAs-based VCLs.
27

Long-Wavelength Vertical-Cavity Lasers : Materials and Device Analysis

Mogg, Sebastian January 2003 (has links)
<p>Vertical-cavity lasers (VCLs) are of great interest as lightsources for fiber-optic communication systems. Such deviceshave a number of advantages over traditional in-plane laserdiodes, including low power consumption, efficient fibercoupling, on-chip testability, as well as potential low-costfabrication and packaging. To date, GaAs-based VCLs operatingat 850 nm are the technology of choice for short-distance,high-speed data transmission over multimode fiber. Forlong-distance communication networks, long-wavelength (LW) VCLsoperating in the 1.3 and 1.55-&#956m transmission windowsof standard singlemode fibers are desired. However, despiteconsiderable worldwide development efforts, the commercialbreakthrough of such devices has still to be achieved. This ismainly due to shortcomings of the intrinsic material propertiesof InP-based material systems, traditionally employed in LWlaser diodes. While LW quantum well (QW) active regions basedon InP are well established, efficient distributed Braggreflectors (DBRs) are better built up in the AlGaAs/GaAsmaterial system. Therefore, earlier work on LW VCLs has focusedon hybrid techniques such as bonding between InP-based QWs andAlGaAs/GaAs DBRs using waferfusion. More recently, however, themain interest in this field has shifted towards all-epitaxialGaAs-based devices employing novel 1.3-&#956m activematerials with strained GaInNAs QWs as one of the mostpromising candidates.</p><p>The main focus of this thesis is on the characterization andanalysis of LW VCLs and building blocks thereof, based on bothInP and GaAs substrates. This includes a theoretical study on1.3-&#956m InGaAsP/InP multiple QW active regions, as wellas an experimental investigation of novel, highly strained1.2-&#956m InGaAs/GaAs single QWs. Two high-accuracyabsolute reflectance measurement setups were built for thecharacterization of various DBRs. Reflectance measurementsrevealed that n-type doping is much more detrimental to theperformance of AlGaAs/GaAs DBRs than previously anticipated.Near-room temperature operation of a single-fused1.55-&#956m VCL with an InP/InGaAsP bottom DBR wasobtained. A thermal analysis of this device structure clearlyindicated its limited capabilities in terms of high-temperatureoperation. As a result, further efforts were directed towardsall-epitaxial GaAs-based VCLs. Record-long emission wavelengthsto above 1260 nm were obtained from InGaAs VCLs based on anextensive gain–cavity detuning. These devices showed verypromising performance characteristics in terms of thresholdcurrent and light output power, indicating good potential forbeing a viable alternative to GaInNAs-based VCLs.</p>
28

Avaliando a heurística de sequenciamento da produção dos métodos Tambor-Pulmão-Corda simplificado e gerenciamento do pulmão em um ambiente de produção para estoque / Evaluating the production sequencing heuristics of the simplified Drum-Buffer-Rope methods and buffer management in a make-to-stock environment

Jorge, Tiago da Cunha 30 November 2017 (has links)
Submitted by TIAGO DA CUNHA JORGE null (tiago.jorge1984@gmail.com) on 2018-01-09T15:54:47Z No. of bitstreams: 1 Dissertacao Final Tiago da Cunha Jorge.pdf: 4224244 bytes, checksum: a8bc587a448d3ec8a242dfd59cfc9591 (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-01-10T13:10:39Z (GMT) No. of bitstreams: 1 jorge_tc_me_bauru.pdf: 4224244 bytes, checksum: a8bc587a448d3ec8a242dfd59cfc9591 (MD5) / Made available in DSpace on 2018-01-10T13:10:39Z (GMT). No. of bitstreams: 1 jorge_tc_me_bauru.pdf: 4224244 bytes, checksum: a8bc587a448d3ec8a242dfd59cfc9591 (MD5) Previous issue date: 2017-11-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente trabalho tem como objetivo avaliar, por meio de simulação computacional, a regra de sequenciamento de ordens de produção recomendada pelo método Tambor-Pulmão-Corda Simplificado/Gerenciamento do Pulmão (Simplified Drum-Buffer-Rope / Buffer Management - S-DBR/BM) aplicado em ambientes de produção para estoque. Esta aplicação recebe o nome de Make to Availability (MTA), pois visa a um compromisso de atendimento da demanda baseado na pronta-entrega de produtos acabados. Para tanto, tal regra será comparada com as regras de sequenciamento da produção SPT (Shortest Processing Time), FIFO (First in First Out) e random. Para cumprir tal objetivo, será simulada uma fábrica real de manufatura contendo diferentes níveis de demanda e diferentes níveis de coeficiente de variação (CV) da demanda. A variável dependente utilizada para comparação dos desempenhos é o fill rate, que mensura o atendimento da demanda a partir do estoque de produtos acabados. Os resultados indicam que a regra S-DBR/MTA supera os demais métodos em todos os cenários simulados e também que cenários com menor CV da demanda apresentaram melhor fill rate médio que aqueles com maior CV. / This dissertation evaluated by computer simulation the production order sequencing rule recommended by the Simplified Drum-Buffer-Rope (S-DBR) applied in make-to-stock environments, called Make to Availability (MTA). MTA method aims at a commitment to meet demand based on the finished products prompt delivery. For this purpose, we compared it with SPT (Shortest Processing Time) sequencing heuristic, FIFO (First In First Out) and random sequencing rules, through demand patterns variations of a real factory. Fill rate was the dependent variable used to compare performances, which is the percentage of demand that is fulfilled directly out of the finished product stock. We show that S-DBR / MTA sequencing rule overcame all other sequencing rules and SPT had the worst fill rate.
29

Crafting a meso practice course using elements of authentic learning for undergraduate social work students in South Africa

Pillay, Roshini January 2017 (has links)
Philosophiae Doctor - PhD / Many teaching and learning practices in higher education, including social work education in South Africa, tend to be characterised by a transmission mode of instruction, whereby knowledge moves from the expert educator to the student. This study investigates the extent to which an authentic learning framework can be used to improve the teaching of meso practice in social work to a class of 80 second-year students at the University of the Witwatersrand, South Africa. A modified version of educational design-based research, was deployed which created a set of guidelines to inform future research and course design. Design-based research includes an iterative process, however, and the four-phased modified version of design-based research used in this study deploys just one roll-out of a redesigned course on meso practice, using the elements of authentic learning (Herrington, Reeves & Oliver, 2010). Phase 1 consisted of a review of the literature on meso practice education and the authentic learning framework. Phase 2 involved an analysis of practical problems identified by six educators and four field instruction supervisors, based on the way they teach and supervise students in the area of meso practice intervention. In Phase 3 the course was implemented and evaluated qualitatively and quantitatively by the student participants and four field instruction supervisors. Phase 4 consisted of a reflection on the entire process, to produce design guidelines using the elements of authentic learning and the inclusion of affect in course design. Mixed-methods research was undertaken, incorporating primarily qualitative data with quantitative data from a survey conducted with the students. Findings from this study have led to an augmented list of authentic learning elements, which includes the use of affect in meso practice and the development of guidelines for educators which have the potential to be relevant and applicable in other courses, contexts and disciplines. / NRF / Pillay, R. (2017). Crafting a meso practice course using elements of authentic learning for undergraduate social work students in South Africa. PhD thesis. University of the Western Cape
30

Studie průběhu zakázky ve výrobním podniku / The Study During the Engagement in the Manufacturing Company

Kubíček, Filip January 2014 (has links)
This master thesis is aimed at optimalization of chosen processes of manufacture of the company DH DEKOR Spol. s r.o. which is engaged in production of impregnated paper and laminated boards. On the basis of the results of processes in storehouse and manufacture of impregnated paper there are given proposals and possible measurments whitch leads to minimalization of time and financal losses.

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