The growth of distributed energy resources together with the incorporation of new technologies in the generation and storage of energy are imposing new control and operational strategies. Due to its storage capability and that it is considered to be clean energy; fuel cell (FC) is one of the most promissory technologies as a stationary energy source in micro grids and also in transportation applications. Therefore, two main issues are addressed in this work; the conception, design, and setup of a fully instrumented test bench for proton exchange membrane (PEM) FC stacks and the design and experimental test of a new dynamic energy-exchange control strategy for multi source and multi load systems. To define the test bench instrument requirements, in the first part a complete dynamic model review is given. In the next section, relevant information regarding the setup of the FC test bench design and implementation is included, i.e., specification criteria of the instruments and acquisition and data display system. Some experimental results are performed in order to demonstrate the potentialities of the setup. In the following chapter, a new dynamic energy exchange control strategy (DSER) is introduced and tested in a two port system via simulation and experimentation. In order to establish a comparison and integrate the DSER in a FC application, in the fifth chapter a three port system - including a static model of FC - and two different control approaches, are tested via simulation. The thesis is closed with some concluding remarks and some potential research topics generated from this work.

隨著網路訊務流量的快速成長，如何妥善的運用網路資源是一個成功的擁塞控制機制要面對的根本問題。在終端設備上執行的TCP是網路上最廣為使用者使用的傳輸層協定，它有很多不同的版本被設計出來改進使用的效能，例如TCP Reno、TCP Vegas 等。由於TCP所棲身的終端設備並未具有網路內部狀態的資訊，大部份的TCP 擁塞控制機制僅能依賴封包遺失觸發擁塞控制機制，本研究提出TCP Muzha協定，藉由路由器協助，提供網路內部資訊給傳送端，在未發生擁塞前不需依賴封包遺失便可進行適度的傳輸速度控制，以減少因為封包遺失所造成劇烈的傳輸速度下降，並可更快速達到最佳傳輸速度。本研究的設計理念是設法尋找傳送路徑中的瓶頸，進而計算出瓶頸提供的可用頻寬，藉由瓶頸所提供的資訊動態的進行流量控制以充份利用頻寬並避免產生擁塞，增進整體的效能。本研究之重點在於路由器應提供何種資訊及如何運用所獲得的資訊進行動態速率調整。我們提出模糊化的多層級速率調整方法，藉著動態所獲得的細膩資訊做擁塞避免。最後於NS2平台實驗模擬，評估我們所提出的方法，實驗結果中顯示本方法能有效避免擁塞的產生，降低封包遺失，提升整體效能，和TCP Reno共存的環境下不因為Reno侵略性的傳輸方式而降低過多的效能並保有較低的封包遺失率。 / With the tremendous growth of Internet traffic, to utilize network resources efficiently is essential to a successful congestion control protocol. Transmission Control Protocol (TCP) is a widely used end-to-end transport protocol across the Internet. It has several enhencing versions (i.e. TCP Reno, TCP Vegas…) which intend to improve the drawbacks of the initial version of TCP. Most congestion control techniques use trial-and-error-based flow control to handle network congestion. In this paper, we propose a new method (TCP Muzha) that requires routers to feedback their status to the sender. Based on this information, the sender is able to adjust the sending data rate dynamically. Our approach can prevent data rate from decreasing dramatically due to packet loss. It can also help to increase the data rate quickly to where it supposes to be. Our design philosophy is to find out the bottleneck of the path, and its available bandwidth. Our goal is to increase network performance and avoid congestion by using the information obtained from the bottleneck. The design challenges are to determine which information is essential and how to use this information to dynamically adjust the data rate. We also propose the multi-level data rate adjustment method. Congestion can be avoided by dynamically adjusting data rate using this information. Finally, we use NS2 simulator to evaluate the performance of our approaches. From the experiment results, it shows our method can avoid congestion before it actually happen, decrease packet-loss rate and increase the network utilization. In the fairness experiment, our method will only suffer a minor throughputs decreasing when TCP Reno is coexisting.

Em ambientes de virtualização de redes (NVEs – Network Virtualization Environments), a infraestrutura física é compartilhada entre diferentes usuários (ou provedores de serviços) que criam múltiplas redes virtuais (VNs – Virtual Networks). Como parte do aprovisionamento de VNs, roteadores virtuais (VRs – Virtual Routers) são criados dentro de roteadores físicos que suportam a virtualização. Atualmente, o gerenciamento de NVEs é quase sempre realizado por soluções proprietárias, normalmente baseadas em interfaces de linha de comando (CLI – Command Line Interface). NVEs heterogêneos (i.e., com equipamentos e tecnologias diferentes) são difíceis de gerenciar, devido à falta de soluções de gerenciamento padronizadas. Como primeiro passo para conseguir a interoperabilidade de gerenciamento, bom desempenho e alta escalabilidade, foram implementadas, avaliadas e comparadas cinco interfaces de gerenciamento de roteadores físicos que hospedam roteadores virtuais. As interfaces são baseadas em SNMP (v2c e v3), NETCONF, e RESTful Web Services (sobre HTTP e HTTPS), e são projetadas para realizar três operações básicas de gerenciamento de VRs: criação de VR, recuperação de informações de VR e remoção de VR. Essas interfaces foram avaliadas em relação às seguintes métricas: tempo de resposta, tempo de CPU, consumo de memória e uso da rede. Os resultados mostram que a interface baseada no SNMPv2c é a mais adequada para pequenos NVEs, sem rigorosos requisitos de segurança, e o NETCONF é a melhor escolha para compor uma interface de gerenciamento para ser implantada em cenários mais realistas, onde a segurança e a escalabilidade são as principais preocupações. / In network virtualization environments (NVEs), the physical infrastructure is shared among different users (or service providers) who create multiple virtual networks (VNs). As part of VN provisioning, virtual routers (VRs) are created inside physical routers supporting virtualization. Currently, the management of NVEs is mostly realized by proprietary solutions, usually based on Command Line Interfaces (CLI). Heterogeneous NVEs (i.e., with different equipment and technologies) are difficult to manage due to the lack of standardized management solutions. As a first step to achieve management interoperability, good performance, and high scalability, we implemented, evaluated, and compared five management interfaces for physical routers that host virtual ones. The interfaces are based on SNMP (v2c and v3), NETCONF, and RESTful Web Services (over HTTP and HTTPS), and are designed to perform three basic VR management operations: VR creation, VR information retrieval, and VR removal. We evaluate these interfaces with regard to the following metrics: response time, CPU time, memory consumption, and network usage. Results show that the SNMPv2c interface is the most suitable one for small NVEs without strict security requirements and NETCONF is the best choice to compose a management interface to be deployed in more realistic scenarios, where security and scalability are major concerns.

Em ambientes de virtualização de redes (NVEs – Network Virtualization Environments), a infraestrutura física é compartilhada entre diferentes usuários (ou provedores de serviços) que criam múltiplas redes virtuais (VNs – Virtual Networks). Como parte do aprovisionamento de VNs, roteadores virtuais (VRs – Virtual Routers) são criados dentro de roteadores físicos que suportam a virtualização. Atualmente, o gerenciamento de NVEs é quase sempre realizado por soluções proprietárias, normalmente baseadas em interfaces de linha de comando (CLI – Command Line Interface). NVEs heterogêneos (i.e., com equipamentos e tecnologias diferentes) são difíceis de gerenciar, devido à falta de soluções de gerenciamento padronizadas. Como primeiro passo para conseguir a interoperabilidade de gerenciamento, bom desempenho e alta escalabilidade, foram implementadas, avaliadas e comparadas cinco interfaces de gerenciamento de roteadores físicos que hospedam roteadores virtuais. As interfaces são baseadas em SNMP (v2c e v3), NETCONF, e RESTful Web Services (sobre HTTP e HTTPS), e são projetadas para realizar três operações básicas de gerenciamento de VRs: criação de VR, recuperação de informações de VR e remoção de VR. Essas interfaces foram avaliadas em relação às seguintes métricas: tempo de resposta, tempo de CPU, consumo de memória e uso da rede. Os resultados mostram que a interface baseada no SNMPv2c é a mais adequada para pequenos NVEs, sem rigorosos requisitos de segurança, e o NETCONF é a melhor escolha para compor uma interface de gerenciamento para ser implantada em cenários mais realistas, onde a segurança e a escalabilidade são as principais preocupações. / In network virtualization environments (NVEs), the physical infrastructure is shared among different users (or service providers) who create multiple virtual networks (VNs). As part of VN provisioning, virtual routers (VRs) are created inside physical routers supporting virtualization. Currently, the management of NVEs is mostly realized by proprietary solutions, usually based on Command Line Interfaces (CLI). Heterogeneous NVEs (i.e., with different equipment and technologies) are difficult to manage due to the lack of standardized management solutions. As a first step to achieve management interoperability, good performance, and high scalability, we implemented, evaluated, and compared five management interfaces for physical routers that host virtual ones. The interfaces are based on SNMP (v2c and v3), NETCONF, and RESTful Web Services (over HTTP and HTTPS), and are designed to perform three basic VR management operations: VR creation, VR information retrieval, and VR removal. We evaluate these interfaces with regard to the following metrics: response time, CPU time, memory consumption, and network usage. Results show that the SNMPv2c interface is the most suitable one for small NVEs without strict security requirements and NETCONF is the best choice to compose a management interface to be deployed in more realistic scenarios, where security and scalability are major concerns.

Em ambientes de virtualização de redes (NVEs – Network Virtualization Environments), a infraestrutura física é compartilhada entre diferentes usuários (ou provedores de serviços) que criam múltiplas redes virtuais (VNs – Virtual Networks). Como parte do aprovisionamento de VNs, roteadores virtuais (VRs – Virtual Routers) são criados dentro de roteadores físicos que suportam a virtualização. Atualmente, o gerenciamento de NVEs é quase sempre realizado por soluções proprietárias, normalmente baseadas em interfaces de linha de comando (CLI – Command Line Interface). NVEs heterogêneos (i.e., com equipamentos e tecnologias diferentes) são difíceis de gerenciar, devido à falta de soluções de gerenciamento padronizadas. Como primeiro passo para conseguir a interoperabilidade de gerenciamento, bom desempenho e alta escalabilidade, foram implementadas, avaliadas e comparadas cinco interfaces de gerenciamento de roteadores físicos que hospedam roteadores virtuais. As interfaces são baseadas em SNMP (v2c e v3), NETCONF, e RESTful Web Services (sobre HTTP e HTTPS), e são projetadas para realizar três operações básicas de gerenciamento de VRs: criação de VR, recuperação de informações de VR e remoção de VR. Essas interfaces foram avaliadas em relação às seguintes métricas: tempo de resposta, tempo de CPU, consumo de memória e uso da rede. Os resultados mostram que a interface baseada no SNMPv2c é a mais adequada para pequenos NVEs, sem rigorosos requisitos de segurança, e o NETCONF é a melhor escolha para compor uma interface de gerenciamento para ser implantada em cenários mais realistas, onde a segurança e a escalabilidade são as principais preocupações. / In network virtualization environments (NVEs), the physical infrastructure is shared among different users (or service providers) who create multiple virtual networks (VNs). As part of VN provisioning, virtual routers (VRs) are created inside physical routers supporting virtualization. Currently, the management of NVEs is mostly realized by proprietary solutions, usually based on Command Line Interfaces (CLI). Heterogeneous NVEs (i.e., with different equipment and technologies) are difficult to manage due to the lack of standardized management solutions. As a first step to achieve management interoperability, good performance, and high scalability, we implemented, evaluated, and compared five management interfaces for physical routers that host virtual ones. The interfaces are based on SNMP (v2c and v3), NETCONF, and RESTful Web Services (over HTTP and HTTPS), and are designed to perform three basic VR management operations: VR creation, VR information retrieval, and VR removal. We evaluate these interfaces with regard to the following metrics: response time, CPU time, memory consumption, and network usage. Results show that the SNMPv2c interface is the most suitable one for small NVEs without strict security requirements and NETCONF is the best choice to compose a management interface to be deployed in more realistic scenarios, where security and scalability are major concerns.

The evolving technology has over the past decade contributed to a bandwidth explosion on the Internet. This makes it interesting to look at the development of the workhorses of the Internet, the core routers. The main objective of this project is to develop a 16 port gigabit core router architecture using intellectual property (IP) blocks and a SoCBUS on-chip interconnection network. The router architecture will be evaluated by making simulations using the SoCBUS simulation environment. Some changes will be made to the current simulator to make the simulations of the core router more realistic. By studying the SoCBUS network load the bottlenecks of the architecture can be found. Changes to the router design and SoCBUS architecture will be made in order to boost the performance of the router. The router developed in this project can under normal traffic conditions handle a throughput of 16x10Gbit/s without dropping packets. This core router is good enough to compete with the top of the line single-chip core routers on the market today. The advantage of this architecture compared to others is that it is very flexible when it comes too adding new functionality. The general on-chip network also reduces the design time of this system.

With open source router firmware being used for various tasks that would be hard to achieve for the standard closed source router firmware, it is important to compare the two in terms of performance. This study aimed to study the differences in performance between open source router firmware and that of closed source router firmware. In addition to have measured bandwidth, packet loss and response time has also been measured in order to make it easier for companies/people to make informed decisions regarding whether to use open source router firmware or not. To further help with decision making, a qualitative study was made to gather data regarding how easy each firmware is to configure and how secure they are. There were some larger differences between the open source router firmware and that of the closed source router firmware. The closed source router firmware performed better when it came to bandwidth, whereas the open source firmware got better response time and overall better stability.

The thesis concentrates on the network infrastructure problems , its proposal in the civil service area and analyses in detail the present condition of surroundings in the chosen organisation which requirements and needs for the suggested network infrastructure result from subsequently . On the base of the analysis it considers the posibility of realising the network infrastructure which consists in the choice of the suitable technology and the proposal of the computer network structure , including the implementation the solution in the given organisation and the specification of the financing resources.

This semestral work deals with the design and realization of multipurpose milling machine for production of prototype small components made from soft materials and PCBs. Thesis contains design of mechanical construction, individual parts of driving machine and graphic user interface.

The aim of this master's thesis is a design and implementation of a program for finding security and operational deficiencies of network devices and afterwards, resolving them by generating corrective configuration. Due to a lack of security and misconfiguration, there are a lot of devices exposed to the risk of a security incident. Therefore, the program compares settings with various standards, recommendations, and best practices and generates a report with findings. Afterwards, deficiencies can be eliminated by automatic resolution or manually if automatic resolving is not possible. The program uses regular expressions to find problem settings in previously exported configurations. Implementation is written in Python, and YAML markup language is used too. Another output of this thesis is a checklist, which can be used for the creation of future modules for support of other network device vendors and thus extend the program.