• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 277
  • 119
  • 60
  • 58
  • 38
  • 27
  • 23
  • 16
  • 9
  • 9
  • 7
  • 7
  • 5
  • 5
  • 5
  • Tagged with
  • 747
  • 747
  • 196
  • 168
  • 145
  • 119
  • 108
  • 102
  • 100
  • 90
  • 89
  • 88
  • 86
  • 75
  • 69
  • 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.
41

Propuesta de un Programa de Clima Organizacional que contribuya a la calidad del servicio de la Empresa Hermes Transportes Blindados de Lima Metropolitana.

De la Rada Salas, Jessica Mary January 2017 (has links)
El objetivo principal proponer un programa de Clima Organizacional que contribuya con el nivel de Calidad de Servicio en la Empresa Hermes Transportes Blindados de Lima Metropolitana.El tipo de estudio fue hipotético deductivo, ya que se planteó la hipótesis en función a la información obtenida, el diseño es de tipo experimental, del tipo pre - experimento. The main objective is to propose an Organizational Climate program that contributes to the level of Quality of Service in the Company Hermes Arportes Blindados of Metropolitan Lima. The type of study was hypothetical deductive, since the hypothesis was proposed based on the information obtained, the design is experimental, of the pre - experimental type.
42

Implementación de un sistema de gestión gerencial para mejorar la calidad de servicio a los usuarios de Luz del Sur periodo 2016-2017

Linares Rodriguez, Pedro Andres January 2017 (has links)
El objetivo general de la investigación fue comprobar que la implementación de un sistema de gestión gerencial mejorará la calidad de servicio a los usuarios de Luz del Sur - período 2016-2017. Para la investigación el tipo de estudio fue descriptivo-aplicada. Se utilizó el método deductivo-explicativo. The general objective of the research was to verify that the implementation of a management management system will improve the quality of service to the users of Luz del Sur - 2016-2017 period. For research the type of study was descriptive-applied. The deductive-explanatory method was used.
43

Quality of Heterogeneous Services with Distributed Resource Management for a WCDMA Uplink

Das, Pratik January 2006 (has links)
A radio resource management scheme for WCDMA uplinks is proposed that manages quality of service (QoS) for heterogeneous services whilst maintaining high channel utilisation efficiency. The proposed system is partitioned into the 3 modules, viz. a QoS-sensitive rate scheduler, an inter-service and intra-service user prioritisation schemes, and a frame admission controller for dynamic resource reallocation. Users are allocated the minimum resources required to manage their QoS requirements through just-in-time delivery of payload, leaving more room for best-effort service users. The transmission urgency of each user is estimated by the rate scheduler based on a target transmission delay - a unique parameter used in the proposed resource management strategy to enable just-in-time payload delivery, service differentiation, and uncomplicated mapping of application requirements to QoS parameters. Transmission rate change requests from the rate schedulers are collectively processed through inter-service and intra-service priority queuing in a manner that is shown to exhibit fairness in allocation of resources amongst users of a heavily loaded network. The performance of the proposed strategy is explored through discrete-event simulations for 3 classes of traffic - voice, video and data, over the WCDMA uplink in the presence of short-term Rayleigh fading, ARQ, FEC, target transmission delays and FER targets in a multi-cell environment. Two alternatives for distributed resource management have been studied, with the UE or Node-B in control of resource allocation. The UE controlled resource management system is shown to achieve higher channel utilisation efficiency at the cost of fairness. The Node-B controlled resource manager respects the priority of speech, video and data traffic in heavily loaded systems, as reflected in 95 percentile packet transmission delays. / PhD Doctorate
44

Scheduling and management of real-time communication in point-to-point wide area networks

Pope, Cheryl Lynn January 2003 (has links)
Applications with timing requirements, such as multimedia and live multi-user interaction, are becoming more prevalent in wide area networks. The desire to provide more predictable performance for such applications in packet switched wide area networks is evident in the channel management provided by Asynchronous Transfer Mode (ATM) networks and in the extensions to the Internet protocols proposed by the Internet Engineering Task Force (IETF) working groups on integrated and differentiated service. The ability to provide guarantees on the performance of traffic flows, such as packet delay and loss characteristics, relies on an accurate model of the traffic arrival and service at each node in the network. This thesis surveys the work in bounding packet delay based on various proposed queuing disciplines and proposes a method for more accurately defining the traffic arrival and worst case backlog experienced by packets. The methods are applied to the first in first out (FIFO) queuing discipline to define equations for determining the worst case backlog and queuing delay in multihop networks. Simulation results show a significant improvement in the accuracy of the delay bounds over existing bounds published in the literature. An improvement of two orders of magnitude can be realised for a ten hop path and the improvement increases exponentially with the length of the path for variable rate network traffic. The equations derived in the thesis also take into consideration the effect of jitter on delay, thereby removing the requirement for rate controllers or traffic shaping within the network. In addition to providing more accurate delay bounds, the problem of providing fault tolerance to channels with guaranteed quality of service (QoS) is also explored. This thesis introduces a method for interleaving resource requirements of backup channels to reduce the overall resource reservations that are required to provide guaranteed fault recovery with the same QoS as the original failed channel. An algorithm for selecting recovery paths that can meet a channel's QoS requirements during recovery is also introduced. / Thesis (Ph.D.)--Computer Science, 2003.
45

HW-SW components for parallel embedded computing on Noc-based MPSoCs

Joven Murillo, Jaume 15 March 2010 (has links)
Recentment, en el camp del sistemes encastats, estem assistint al creixement de sistemes Multi-Processor System-on-Chip (MPSoC). El paradigma de Network-on-chip (NoC) s'ha proposat una solució viable, eficient, escalable, predictible i flexible per connectar components dins un xip, o inclús sistemes complets basats en busos dins al xip amb la finalitat de crear sistemes altament complexos. Així, el paradigma de computació encastada d'altres prestacions està arribant a través d'integrar hardware altament paral·lel amb llibreries software per obtenir una màxima integració a nivell de plataforma utilitzant de components prèviament dissenyats (IP cores), en la forma de arquitectures NoC-based MPSoCs. No obstant, quan el nombre de components augmenta hi ha diversos desafiaments i problemes a resoldre. El primer repte és el disseny d'una xarxa d'interconnexió que proporcioni qualitat de servei assegurant un cert ample de banda i latència entre cada bloc del sistema, amb el mínim area i consum possible. Ja que l'espai de disseny en arquitectures NoCs és enorme, s'han de desenvolupar entorns de simulació, i verificació per explorar validar i optimitzar múltiples NoC arquitectures. El segon objectiu, que és actualment un forat de recerca, és proveir models de programació paral·lela flexibles i eficients sobre les arquitectures NoC-based MPSoCs. Així, és obligatori l'ús de llibreries software lleugeres capaces d'explotar la capacitats del hardware present a la plataforma d'execució. Fent servir aquestes llibreries software permetrà els programadors reutilitzar i programar de manera fàcil aplicacions paral·leles dins un xip. Finalment, per obtenir un sistema eficient, un punt clau és el disseny de les interfícies HW-SW apropiades. Aquest fet és crucial in multi processadors heterogenis on els paradigmes de programació paral·lela and middleware han d'abstreure els recursos de comunicació durant l'especificació d'aplicacions software. El principal objectiu d'aquesta tesis és enriquir les emergents arquitectures NoC-based MPSoC explorant i fent contribucions de caire científic afrontant els nous reptes apareguts aquest últims anys. Aquesta tesis es focalitza en els següents temes: Descripció of un entorn experimental anomenat NoCMaker per realitzar exploració arquitectural de sistemes NoC-based MPSoC, permetent alhora una validació i prototipatge ràpid. Extensió de les interfícies de xarxa per controlar tràfic heterogeni de diferents estàndards (AMBA AHB, OCP-IP) amb la finalitat de reutilitzar i comunicar de manera transparent múltiple IP cores des del punt de vista de l'usuari. Proporcionar qualitat de servei en temps d'execució a traves de components hardware a la NoC, i de rutines middleware en software. Exploració de les interfícies HW-SW i la compartició de recursos quan una unitat de punt flotant es connecta com a coprocessador a un sistema NoC-based MPSoC. Migració de paradigmes de programació paral·lela, com memòria compartida i pas de missatges en arquitectures NoC-based MPSoCs. En aquesta tesis presentem el desenvolupament d'un model de programació paral·lela basat en pas de missatges (MPI), anomenat on-chip MPI. Això permet el disseny de programes paral·leles distribuïts a nivell de tasca o funció fent servir la programació paral·lela explicita amb els mètodes de sincronia entre els elements integrats en el xip. Proporcionant qualitat de servei en temps d'execució a sobre d'una llibreria OpenMP dissenyada per sistemes de memòria compartida amb la finalitat d'accelerar o balancejar aplicacions critiques i fils d'execució durant la seva execució. Tots els reptes explorats durant aquesta tesi doctoral estan formalitzats en una metodologia hardware-software centrada en la infraestructura de comunicació de la plataforma. Així, el resultat d'aquest treball d'investigació serà una plataforma cluster-on-chip per una computació paral·lela encastada d'altes prestacions, on els components hardware and software poden ser reutilitzats a diverses nivells d'abstracció. / Recently, on the on-chip and embedded domain, we are witnessing the growing of the Multi-Processor System-on-Chip (MPSoC) era. Network-on-chip (NoCs) have been proposed to be a viable, efficient, scalable, predictable and flexible solution to interconnect IP blocks on a chip, or full-featured bus-based systems in order to create highly complex systems. Thus, the paradigm to high-performance embedded computing is arriving through high hardware parallelism and concurrent software stacks to achieve maximum system platform composability and flexibility using pre-designed IP cores. These are the emerging NoC-based MPSoCs architectures. However, as the number of IP cores on a single chip increases exponentially, many new challenges arise. The first challenge is the design of a suitable hardware interconnection to provide adequate Quality of Service (QoS) ensuring certain bandwidth and latency bounds for inter-block communication, but at a minimal power and area costs. Due to the huge NoC design space, simulation and verification environments must be put in place to explore, validate and optimize many different NoC architectures. The second target, nowadays a hot topic, is to provide efficient and flexible parallel programming models upon new generation of highly parallel NoC-based MPSoCs. Thus, it is mandatory the use of lightweight SW libraries which are able to exploit hardware features present on the execution platform. Using these software stacks and their associated APIs according to a specific parallel programming model will let software application designers to reuse and program parallel applications effortlessly at higher levels of abstraction. Finally, to get an efficient overall system behaviour, a key research challenge is the design of suitable HW/SW interfaces. Specially, it is crucial in heterogeneous multiprocessor systems where parallel programming models and middleware functions must abstract the communication resources during high level specification of software applications. Thus, the main goal of this dissertation is to enrich the emerging NoC-based MPSoCs by exploring and adding engineering and scientific contribution to new challenges appeared in the last years. This dissertation focuses on all of the above points: by describing an experimental environment to design NoC-based systems, xENoC, and a NoC design space exploration tool named NoCMaker. This framework leads to a rapid prototyping and validation of NoC-based MPSoCs. by extending Network Interfaces (NIs) to handle heterogeneous traffic from different bus¬based standards (e.g. AMBA, OCP-IP) in order to reuse and communicate a great variety off-the-shelf IP cores and software stacks in a transparent way from the user point of view. by providing runtime QoS features (best effort and guaranteed services) through NoC-level hardware components and software middleware routines. by exploring HW/SW interfaces and resource sharing when a Floating Point Unit (FPU) co¬processor is interfaced on a NoC-based MPSoC. by porting parallel programming models, such as shared memory or message passing models on NoC-based MPSoCs. We present the implementation of an efficient lightweight parallel programming model based on Message Passing Interface (MPI), called on-chip Message Passing Interface (ocMPI). It enables the design of parallel distributed computing at task-level or function-level using explicit parallelism and synchronization methods between the cores integrated on the chip. by provide runtime application to packets QoS support on top of the OpenMP runtime library targeted for shared memory MPSoCs in order to boost or balance critical applications or threads during its execution. The key challenges explored in this dissertation are formalized on HW-SW communication centric platform-based design methodology. Thus, the outcome of this work will be a robust cluster-on-chip platform for high-performance embedded computing, whereby hardware and software components can be reused at multiple levels of design abstraction.
46

Maintaining Quality of Service for Adaptive Mobile Map Clients

Abdelsalam, Wegdan Ahmad Elsay Fouad January 2001 (has links)
Mobile devices must deal with limited and dynamically varying resources, in particular, the network quality of service (QoS). In addition, wireless devices have other constraints such as limited memory, battery power, and physical dimensions. Applications that execute in such environments need to adapt to the dynamic operating conditions in order to preserve an acceptable level of service as close to 100% of the time as possible. Viewing and downloading digital spatial data on mobile devices has become more popular, especially with the availability of <i>location-aware</i> applications that exploit GPS (Global Positioning System) receivers integrated in many of today's mobile devices. Map client applications face many challenges in accessing data across a wireless network. Vector spatial data files tend to be large, and file sizes tend to increase unpredictably depending on the complexity of feature geometry. Due to the limited size of the mobile device display, viewing all the details of the map could cause unreasonable clutter and render the map useless. Even if it is feasible to transmit all the details from a QoS standpoint, this could pose a problem from a usability standpoint. This research effort aims to tackle the issues of QoS and usability on mobile devices through a client-proxy-server model where clients are on mobile devices. The proxy performs two functions. First, it supplies the client with vital data about the status of the system that allows the client to take adaptive decisions aimed at maintaining the QoS. Second, it performs the adaptive actions requested by the client. There are two types of adaptive actions performed by the proxy, activating and deactivating filters. When filters are activated, the amount of data transmitted from the server to the client is reduced. The client may decide to activate one or more filters either to maintain QoS or to limit clutter on the screen and enhance usability. The map client-server application and the proxy were developed in Java (tm), and a number of experiments and real-life scenarios were designed to determine the effectiveness and feasibility of the proposed adaptation model and to evaluate the performance of the proxy.
47

Quality of Service i IP-nätverk / Quality of Service in IP Networks

Ahlin, Karl January 2003 (has links)
The original promise behind the Internet Protocol was to deliver data from a sender to the receiver using a best-effort approach. This means that the protocol makes no guarantees except that it will try to deliver the data to the destination. If some problem occurs the packet may be discarded by the network without any notice. No guarantees are made regarding the time it takes to deliver the data, the rate at which data will be delivered or if data is delivered in the same order it was sent. The best-effort approach is arguably the reason behind the success of the Internet Protocol and is what makes IP scalable to networks the size of the Internet. However, this approach is also a problem for network operators who want to offer better quality of service to some of their customers. This master thesis will discuss some of the theories behind the implementation of quality of service schemes in an IP network and also provide an example of how to implement it in an existing network.
48

Maintaining Quality of Service for Adaptive Mobile Map Clients

Abdelsalam, Wegdan Ahmad Elsay Fouad January 2001 (has links)
Mobile devices must deal with limited and dynamically varying resources, in particular, the network quality of service (QoS). In addition, wireless devices have other constraints such as limited memory, battery power, and physical dimensions. Applications that execute in such environments need to adapt to the dynamic operating conditions in order to preserve an acceptable level of service as close to 100% of the time as possible. Viewing and downloading digital spatial data on mobile devices has become more popular, especially with the availability of <i>location-aware</i> applications that exploit GPS (Global Positioning System) receivers integrated in many of today's mobile devices. Map client applications face many challenges in accessing data across a wireless network. Vector spatial data files tend to be large, and file sizes tend to increase unpredictably depending on the complexity of feature geometry. Due to the limited size of the mobile device display, viewing all the details of the map could cause unreasonable clutter and render the map useless. Even if it is feasible to transmit all the details from a QoS standpoint, this could pose a problem from a usability standpoint. This research effort aims to tackle the issues of QoS and usability on mobile devices through a client-proxy-server model where clients are on mobile devices. The proxy performs two functions. First, it supplies the client with vital data about the status of the system that allows the client to take adaptive decisions aimed at maintaining the QoS. Second, it performs the adaptive actions requested by the client. There are two types of adaptive actions performed by the proxy, activating and deactivating filters. When filters are activated, the amount of data transmitted from the server to the client is reduced. The client may decide to activate one or more filters either to maintain QoS or to limit clutter on the screen and enhance usability. The map client-server application and the proxy were developed in Java (tm), and a number of experiments and real-life scenarios were designed to determine the effectiveness and feasibility of the proposed adaptation model and to evaluate the performance of the proxy.
49

Adaptive Measurement-Based Traffic Engineering in Packet-Switched Radio Access Networks

Krasser, Sven 21 June 2004 (has links)
In this research, we propose a framework for measurement-based traffic engineering and connection admission control in radio access networks based on the Internet Protocol (IP). This framework is evaluated by simulation using the popular network simulator ns-2. The framework is adaptive to changes in the network load and can distinguish between different types of service. All traffic engineering decisions are made by edge routers (ERs) at the rim of the network domain. Multiple disjoint paths are configured between those ERs. Network state information is gathered in two different fashions. We evaluate a scheme based on the states of the queues on each alternative path and a scheme based on end-to-end probe packet transmission characteristics on each alternative path. Both schemes are compared to a shortest path first (SPF) routing approach.
50

Efficient Bandwidth Allocation with QoS support for IEEE 802.16 Systems

Lai, Da-Nung 07 September 2011 (has links)
Multimedia applications in wireless communication have shown notable increases over recent years. Specifically, Quality of Service (QoS) has become an important support mechanism in the context of a variety of applications which utilize network resources. The IEEE 802.16 standard for Wireless Metropolitan Area Networks (WirelessMAN) provides a complete QoS control structure designed to enable flow isolation and service differentiation over the common wireless interface. Although the media access control (MAC) mechanisms defined in this standard can offer predefined QoS provisioning on a pre-connection basis (additionally, many algorithms have been addressed to support QoS guarantees for various kinds of applications), the design for a stable, efficient and flexible MAC scheduling algorithm for such QoS provisioning still remains to be discovered. In this paper, we propose a QoS control scheme, Efficient Bandwidth Allocation (EBA), for the WirelessMAN system. Notably, this schedule enables predefined service parameters to control the service provided for each uplink connection and it provides each connection with different service opportunities such that the BS could allocate the most suitable bandwidth constantly for each connection with the various QoS parameters. Moreover, through MAC layer resource allocation, the proposed algorithm is capable of providing QoS guarantee for the SSs under different distance.

Page generated in 0.0617 seconds