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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.
1

Design of multi-channel radio-frequency front-end for 200mhz parallel magnetic resonance imaging

Liu, Xiaoqun 15 May 2009 (has links)
The increasing demands for improving magnetic resonance imaging (MRI) quality, especially reducing the imaging time have been driving the channel number of parallel magnetic resonance imaging (Parallel MRI) to increase. When the channel number increases to 64 or even 128, the traditional method of stacking the same number of radio-frequency (RF) receivers with very low level of integration becomes expensive and cumbersome. However, the cost, size, power consumption of the Parallel MRI receivers can be dramatically reduced by designing a whole receiver front-end even multiple receiver front-ends on a single chip using CMOS technology, and multiplexing the output signal of each receiver front-end into one channel so that as much hardware resource can be shared by as many channels as possible, especially the digitizer. The main object of this research is focused on the analysis and design of fully integrated multi-channel RF receiver and multiplexing technology. First, different architectures of RF receiver and different multiplexing method are analyzed. After comparing the advantages and the disadvantages of these architectures, an architecture of receiver front-end which is most suitable for fully on-chip multi-channel design is proposed and a multiplexing method is selected. According to this proposed architecture, a four-channel receiver front-end was designed and fabricated using TSMC 0.18μm technology on a single chip and methods of testing in the MRI system using parallel planar coil array and phase coil array respectively as target coils were presented. Each channel of the receiver front-end includes an ultra low noise amplifier (LNA), a quadrature image rejection down-converter, a buffer, and a low-pass filter (LPF) which also acts as a variable gain amplifier (VGA). The quadrature image rejection downconverter consists of a quadrature generator, a passive mixer with a transimpedance amplifier which converts the output current signal of the passive mixer into voltage signal while acts as a LPF, and a polyphase filter after the TIA. The receiver has an over NF of 0.935dB, variable gain from about 80dB to 90dB, power consumption of 30.8mW, and chip area of 6mm2. Next, a prototype of 4-channel RF receiver with Time Domain Multiplexing (TDM) on a single printed circuit board (PCB) was designed and bench-tested. Then Parallel MRI experiment was carried out and images were acquired using this prototype. The testing results verify the proposed concepts.
2

The effectiveness of document ranking and relevance feedback techniques in a thesaurus-based search intermediary system

Smith, Martin Philip January 1995 (has links)
No description available.
3

En demonstrationswebbplats skapad i WM3 för WM3 / A demo site created with WM3 for WM3

Erika, Krauser January 2016 (has links)
In order to recruit customers to WM3, the sellers of HL Design have for a while been wishing for a demonstration site. Therefore, this thesis and projekt goal have been to create such a site in WM3. WM3 is a CMS created by HL design and includes eleven different modules and features like; live editing, articles and calendars. The site will therefore include these modules that WM3 offers in except for two; the webshop and statistics-module. The site will also be user friendly, responsive, accessible, and it will be easy to navigate in it. Interest in WM3 has grown and grown during the project. The reason has been the ease and userfriendliness of WM3, both for developers and potential customers. As manager and developer of this thesis and projekt the tasks consisted of devoloping the site accourding to a plan and creating the plan to; demonstrate how the site should look like in terms of design, how the modules should be presented and how the structure of the website should look like. The result of this projekt and theises is a complete demonstration site for a fictitious law firm where all modules except the webshop and statistics, are used and presented. / För att rekrytera kunder till WM3 har säljarna på HL Design länge önskar sig en demonstrationswebbplats. Därför har detta examensarbetet gått ut på att skapa en sådan webbplats i WM3. WM3 är ett CMS skapat av HL design och innehåller elva olika moduler och funktioner som liveredigering, artiklar och kalendrar. Webbplatsen ska därför innehålla modulerna som WM3 erbjuder förutom två; webbshop och statistik-modulen. Den ska även vara användarvänlig, responsiv, tillgänglig och det ska vara enkelt att navigera i den. Intresset för WM3 har växt och växt under projektets gång. Anledningen har varit lättheten och användarvänligheten som WM3 har, både för utvecklare och potentiella kunder. Som ansvarig och utvecklare i detta examensarbete har arbetsuppgifterna bestått av att utveckla webbplatsen enligt en plan samt att skapa denna plan; för hur demonstrationswebbplatsen ska se ut designmässigt, hur modulerna ska presenteras och hur strukturen för webbplatsen ska se ut, samt utveckla webbplatsen efter planen. Resultatet av arbetet är en färdig demonstrations-webbplats för en fiktiv advokatbyrå där alla moduler, förutom Webbshop och Statistik, används
4

Front-end of innovation: roles and integration mechanisms / Front-end da inovação: papéis e mecanismos de integração

Schreiner, Lilian Cristina 08 May 2018 (has links)
The Front End of Innovation (FEI) is the early phase of the Product Development Process, responsible for the concept generation and an important driver of innovation success. The FEI is characterized by roles\' dynamism, ambiguity, and uncertainty. Several authors divide the FEI into other sub-phases in order to organize its activities, roles, and understand the function of each role. Despite the growing research about the FEI in recent years, there is a need for further research on the theme to better understand the dynamics and help to reduce the uncertainty in the critical concept phase. The formal processes designed for the front end are insufficient, the rules and roles are not fully described, and it is necessary to balance the interactions between the activities in the FEI to get a better-structured New Product Development - NPD - later. The main FEI models developed at the literature have discussed some key roles such marketing, engineering, customers, but they do not discussed the role of design, which is critical in creative activities which, in turn, are the nature of the new product development process. The literature also has not discussed the external integration in the FEI, that is, how the Brand Owners integrate the partners, especially the suppliers and design agencies, in this critical and uncertain phase. To tackle this issue, this research aims to examine the FEI in a dynamic industry, examining the integration of roles in an iterative process. The objective of this research is to identify the roles that play in the Front End of Innovation and the mechanisms of integration, whether internal through cross-functional teams; or external through interfirms integration. The main question that guided this research is \"What roles are involved in each FEI activity and what are the mechanism that integrate these roles in the FEI?\". This is qualitative and exploratory research, based on multiple-cases-studies. For this study, the packaging industry was selected because of its value chain in the concept phase, which has a complex set of relationships among its parties, Brand Owner, Design Agencies and Packaging Producers. The consumers buy the product by the performance of the same and also by the packaging. Packaging is considered a second product at the point of sale and a vital buying decision factor. Brand Owners understand that they need to integrate suppliers into the FEI to assist them in identifying opportunities, ideation, and conceptualization. Five brand owners were interviewed, and the FEI has been divided into five activities: Opportunity Identifications and Analysis, Idea Generation, Idea Enrichment, Idea Selection, and Concept Development. / O Front End de Inovação (FEI) é a fase inicial do processo de desenvolvimento de produtos, responsável pela geração de conceitos e um importante motor de sucesso na inovação. O FEI caracteriza-se pelo dinamismo, a ambiguidade e a incerteza dos papéis. Vários autores dividem o FEI em outras subfases, a fim de organizar suas atividades, papéis e compreender a função de cada função. Apesar da crescente pesquisa sobre o FEI nos últimos anos, há necessidade de novas pesquisas sobre o assunto para entender melhor a dinâmica e ajudar a reduzir a incerteza na fase conceitual crítica. Os processos formais projetados para o front-end são insuficientes, os papéis e as regras e não são totalmente descritos e é necessário equilibrar as interações entre as atividades no FEI para obter um melhor estruturado Desenvolvimento de Novos Produtos - NPD - depois. Os principais modelos de FEI desenvolvidos na literatura discutem alguns papéis fundamentais como marketing, engenharia, consumidores, mas não discutem o papel do design, crítico nas atividades criativas, que, por sua vez, são a natureza do processo de desenvolvimento de novos produtos. A literatura também não tem discutido a integração externa no FEI, ou seja, como os clientes integram os parceiros, especialmente os fornecedores e agências de design, nesta fase crítica e incerta. Para abordar esta questão, esta pesquisa visa examinar o FEI em uma indústria dinâmica, examinando a integração de papéis em um processo iterativo. O objetivo desta pesquisa é identificar os papéis que desempenham no Front End de Inovação e os mecanismos de integração, sejam eles internos através de equipes multifuncionais; ou externos através da integração entre firmas. A principal questão que guiou esta pesquisa é \"Quais papéis estão envolvidas em cada atividade do FEI e quais são os mecanismos que integram estes papéis no FEI?\" Trata-se de uma pesquisa qualitativa e exploratória, baseada em estudos de casos múltiplos. Para este estudo, o setor de embalagens foi selecionado por sua cadeia de valor na fase conceitual, que possui um conjunto complexo de relacionamentos entre suas partes, as Indústrias de Bens de Consumo, as Agências de Design e os Produtores de Embalagens. Os consumidores compram o produto pela performance do mesmo e também pela embalagem. A embalagem é considerada um segundo produto no ponto de venda e um fator de decisão de compra vital. As Indústrias de Bens de Consumo entendem que precisam integrar fornecedores no FEI para ajudá-las a identificar oportunidades, ideação e conceituação. Foram entrevistados cinco Indústrias de Bens de Consumo e o FEI foi dividido em cinco atividades: Identificações e Análises de Oportunidades, Geração de Ideias, Enriquecimento de Ideias, Seleção de Ideias e Desenvolvimento de Conceitos.
5

Organizational decision making : the Fuzzy Front End

Alas, José Ernesto 08 February 2012 (has links)
Decision-makers have many defined and widely accepted tools in place to manage projects and programs. However, can the same be said for the very early stages of projects? This research investigates what researchers are now referring to as the Fuzzy Front End of Innovation, which is defined as the territory leading up to organizational-level absorption and commercialization of the innovation process. Despite all of the actions in establishing new operational efficiencies and project management guidelines to improve New Product Development (NPD), a formalized model does not exist for the screening and filtering of the most exceptional opportunities. The ALAS Fuzzy Front End of Innovation Process Model is proposed to help manage the innovation process. This model is based on an in-depth literature review and respondent interview data. As a secondary topic this thesis will look to understand and propose the organizational structure required to support pre-phase Fuzzy Front End activities, governance and management’s role. This will not be a discussion on organizational types within development or engineering organizations (i.e.: matrix, product, platform organizational structures) but rather from the findings propose a structure that helps define who the key stake holders are in approving or rejecting development efforts. / text
6

Design and Implementation of a Multi-Channel Field-Programmable Analog Front-End For a Neural Recording System

Ebrahimi Sadrabadi, Bahareh January 2014 (has links)
Neural recording systems have attracted an increasing amount of attention in recent years, and researchers have put major efforts into designing and developing devices that can record and monitor neural activity. Understanding the functionality of neurons can be used to develop neuroprosthetics for restoring damages in the nervous system. An analog front-end block is one of the main components in such systems, by which the neuron signals are amplified and processed for further analysis. In this work, our goal is to design and implement a field-programmable 16-channel analog front-end block, where its programmability is used to deal with process variation in the chip. Each channel consists of a two-stage amplifier as well as a band-pass filter with digitally tunable low corner frequency. The 16 recording channels are designed using four different architectures. The first group of recording channels employs one low-noise amplifier (LNA) as the first-stage amplifier and a fully differential amplifier for the second stage along with an NMOS transistor in the feedback loop. In the second group of architectures, we use an LNA as the first stage and a single-ended amplifier for implementing the second stage. Groups three and four have the same design as groups one and two; however the NMOS transistor in the feedback loop is replaced by two PMOS transistors. In our design, the circuits are optimized for low noise and low power consumption. Simulations result in input-referred noise of 6.9 ??Vrms over 0.1 Hz to 1 GHz. Our experiments show the recording channel has a gain of 77.5 dB. The chip is fabricated in AMS 0.35 ??m CMOS technology for a total die area of 3 mm??3 mm and consumes 2.7 mW power from a 3.3 V supply. Moreover, the chip is tested on a PCB board that can be employed for in-vivo recording.
7

A CMOS Analog Front-End IC for Gas Sensors

January 2011 (has links)
abstract: This thesis presents a gas sensor readout IC for amperometric and conductometric electrochemical sensors. The Analog Front-End (AFE) readout circuit enables tracking long term exposure to hazardous gas fumes in diesel and gasoline equipments, which may be correlated to diseases. Thus, the detection and discrimination of gases using microelectronic gas sensor system is required. This thesis describes the research, development, implementation and test of a small and portable based prototype platform for chemical gas sensors to enable a low-power and low noise gas detection system. The AFE reads out the outputs of eight conductometric sensor array and eight amperometric sensor arrays. The IC consists of a low noise potentiostat, and associated 9bit current-steering DAC for sensor stimulus, followed by the first order nested chopped £U£G ADC. The conductometric sensor uses a current driven approach for extracting conductance of the sensor depending on gas concentration. The amperometric sensor uses a potentiostat to apply constant voltage to the sensors and an I/V converter to measure current out of the sensor. The core area for the AFE is 2.65x0.95 mm2. The proposed system achieves 91 dB SNR at 1.32 mW quiescent power consumption per channel. With digital offset storage and nested chopping, the readout chain achieves 500 fÝV input referred offset. / Dissertation/Thesis / Ph.D. Electrical Engineering 2011
8

Front-end of innovation: roles and integration mechanisms / Front-end da inovação: papéis e mecanismos de integração

Lilian Cristina Schreiner 08 May 2018 (has links)
The Front End of Innovation (FEI) is the early phase of the Product Development Process, responsible for the concept generation and an important driver of innovation success. The FEI is characterized by roles\' dynamism, ambiguity, and uncertainty. Several authors divide the FEI into other sub-phases in order to organize its activities, roles, and understand the function of each role. Despite the growing research about the FEI in recent years, there is a need for further research on the theme to better understand the dynamics and help to reduce the uncertainty in the critical concept phase. The formal processes designed for the front end are insufficient, the rules and roles are not fully described, and it is necessary to balance the interactions between the activities in the FEI to get a better-structured New Product Development - NPD - later. The main FEI models developed at the literature have discussed some key roles such marketing, engineering, customers, but they do not discussed the role of design, which is critical in creative activities which, in turn, are the nature of the new product development process. The literature also has not discussed the external integration in the FEI, that is, how the Brand Owners integrate the partners, especially the suppliers and design agencies, in this critical and uncertain phase. To tackle this issue, this research aims to examine the FEI in a dynamic industry, examining the integration of roles in an iterative process. The objective of this research is to identify the roles that play in the Front End of Innovation and the mechanisms of integration, whether internal through cross-functional teams; or external through interfirms integration. The main question that guided this research is \"What roles are involved in each FEI activity and what are the mechanism that integrate these roles in the FEI?\". This is qualitative and exploratory research, based on multiple-cases-studies. For this study, the packaging industry was selected because of its value chain in the concept phase, which has a complex set of relationships among its parties, Brand Owner, Design Agencies and Packaging Producers. The consumers buy the product by the performance of the same and also by the packaging. Packaging is considered a second product at the point of sale and a vital buying decision factor. Brand Owners understand that they need to integrate suppliers into the FEI to assist them in identifying opportunities, ideation, and conceptualization. Five brand owners were interviewed, and the FEI has been divided into five activities: Opportunity Identifications and Analysis, Idea Generation, Idea Enrichment, Idea Selection, and Concept Development. / O Front End de Inovação (FEI) é a fase inicial do processo de desenvolvimento de produtos, responsável pela geração de conceitos e um importante motor de sucesso na inovação. O FEI caracteriza-se pelo dinamismo, a ambiguidade e a incerteza dos papéis. Vários autores dividem o FEI em outras subfases, a fim de organizar suas atividades, papéis e compreender a função de cada função. Apesar da crescente pesquisa sobre o FEI nos últimos anos, há necessidade de novas pesquisas sobre o assunto para entender melhor a dinâmica e ajudar a reduzir a incerteza na fase conceitual crítica. Os processos formais projetados para o front-end são insuficientes, os papéis e as regras e não são totalmente descritos e é necessário equilibrar as interações entre as atividades no FEI para obter um melhor estruturado Desenvolvimento de Novos Produtos - NPD - depois. Os principais modelos de FEI desenvolvidos na literatura discutem alguns papéis fundamentais como marketing, engenharia, consumidores, mas não discutem o papel do design, crítico nas atividades criativas, que, por sua vez, são a natureza do processo de desenvolvimento de novos produtos. A literatura também não tem discutido a integração externa no FEI, ou seja, como os clientes integram os parceiros, especialmente os fornecedores e agências de design, nesta fase crítica e incerta. Para abordar esta questão, esta pesquisa visa examinar o FEI em uma indústria dinâmica, examinando a integração de papéis em um processo iterativo. O objetivo desta pesquisa é identificar os papéis que desempenham no Front End de Inovação e os mecanismos de integração, sejam eles internos através de equipes multifuncionais; ou externos através da integração entre firmas. A principal questão que guiou esta pesquisa é \"Quais papéis estão envolvidas em cada atividade do FEI e quais são os mecanismos que integram estes papéis no FEI?\" Trata-se de uma pesquisa qualitativa e exploratória, baseada em estudos de casos múltiplos. Para este estudo, o setor de embalagens foi selecionado por sua cadeia de valor na fase conceitual, que possui um conjunto complexo de relacionamentos entre suas partes, as Indústrias de Bens de Consumo, as Agências de Design e os Produtores de Embalagens. Os consumidores compram o produto pela performance do mesmo e também pela embalagem. A embalagem é considerada um segundo produto no ponto de venda e um fator de decisão de compra vital. As Indústrias de Bens de Consumo entendem que precisam integrar fornecedores no FEI para ajudá-las a identificar oportunidades, ideação e conceituação. Foram entrevistados cinco Indústrias de Bens de Consumo e o FEI foi dividido em cinco atividades: Identificações e Análises de Oportunidades, Geração de Ideias, Enriquecimento de Ideias, Seleção de Ideias e Desenvolvimento de Conceitos.
9

Novel Front-end Electronics for Time Projection Chamber Detectors

García García, Eduardo José 03 September 2012 (has links)
Este trabajo ha sido realizado en la Organización Europea para la Investigación Nuclear (CERN) y forma parte del proyecto de investigación Europeo para futuros aceleradores lineales (EUDET). En física de partículas existen diferentes categorías de detectores de partículas. El diseño presentado esta centrado en un tipo particular de detector de trayectoria de partículas denominado TPC (Time Projection Chamber) que proporciona una imagen en tres dimensiones de las partículas eléctricamente cargadas que atraviesan su volumen gaseoso. La tesis incluye un estudio de los objetivos para futuros detectores, resumiendo los parámetros que un sistema de adquisición de datos debe cumplir en esos casos. Además, estos requisitos son comparados con los actuales sistemas de lectura utilizados en diferentes detectores TPC. Se concluye que ninguno de los sistemas cumple las restrictivas condiciones. Algunos de los principales objetivos para futuros detectores TPC son un altísimo nivel de integración, incremento del número de canales, electrónica más rápida y muy baja potencia. El principal inconveniente del estado del arte de los sistemas anteriores es la utilización de varios circuitos integrados en la cadena de adquisición. Este hecho hace imposible alcanzar el altísimo nivel de integración requerido para futuros detectores. Además, un aumento del número de canales y frecuencia de muestreo haría incrementar hasta valores no permitidos la potencia utilizada. Y en consecuencia, incrementar la refrigeración necesaria (en caso de ser posible). Una de las novedades presentadas es la integración de toda la cadena de adquisición (filtros analógicos de entrada, conversor analógico-digital (ADC) y procesado de señal digital) en un único circuito integrado en tecnología de 130nm. Este chip es el primero que realiza esta altísima integración para detectores TPC. Por otro lado, se presenta un análisis detallado de los filtros de procesado de señal. Los objetivos más importantes es la reducció / García García, EJ. (2012). Novel Front-end Electronics for Time Projection Chamber Detectors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16980 / Palancia
10

Side-Channel Attacks in RISC-V BOOM Front-end

Chavda, Rutvik Jayantbhai 29 June 2023 (has links)
The prevalence of side-channel attacks exploiting hardware vulnerabilities leads to the exfil- tration of secretive data such as secret keys, which poses a significant threat to the security of modern processors. The RISC-V BOOM core is an open-source modern processor design widely utilized in research and industry. It enables experimentation with microarchitec- tures and memory hierarchies for optimized performance in various workloads. The RISC-V BOOM core finds application in the IoT and Embedded systems sector, where addressing side-channel attacks becomes crucial due to the significant emphasis on security. While prior studies on BOOM mainly focus on the side channel in the memory hierarchy such as caches or physical attacks such as power side channel. Recently, the front-end of microprocessors, which is responsible for fetching and decoding instructions, is found to be another potential source of side-channel attacks on Intel Processors. In this study, I present four timing-based side-channel attacks that leverage components in the front-end of BOOM. I tested the effectiveness of the attacks using a simulator and Xilinx VCU118 FPGA board. Finally, I provided possible mitigation techniques for these types of attacks to improve the overall security of modern processors. Our findings underscore the importance of identifying and addressing vulnerabilities in the front-end of modern pro- cessors, such as the BOOM core, to mitigate the risk of side-channel attacks and enhance system security. / Master of Science / In today's digital landscape, the security of modern processors is threatened by the increasing prevalence of side-channel attacks that exploit hardware vulnerabilities. These attacks are a type of security threat that allows attackers to extract sensitive information from computer systems by analyzing the physical behavior. The risk of such attacks is further amplified when multiple users or applications share the same hardware resources. Attackers can ex- ploit the interactions and dependencies among shared resources to gather information and compromise the integrity and confidentiality of critical data. The RISC-V BOOM core, a widely utilized modern processor design, is not immune to these side-channel attacks. This issue demands urgent attention, especially considering its deploy- ment in data-sensitive domains such as IoT and embedded systems. Previous studies have focused on side-channel vulnerabilities in other areas of BOOM, ne- glecting the front-end. However, the front-end, responsible for processing initial information, has recently emerged as another potential target for side-channel attacks. To address this, I conducted a study on the vulnerability of the RISC-V BOOM core's front-end. By conduct- ing tests using both a software-based simulator and a physical board, I uncovered potential security threats and discussed potential techniques to mitigate these risks, thereby enhanc- ing the overall security of modern processors. These findings underscore the significance of addressing vulnerabilities in the front-end of processors to prevent side-channel attacks and safeguard against potential malicious activities.

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