Sheet metal forming is used in a wide range of industrial processes ranging from tube manufacturing to automobile and aviation industry. It includes processes like stamping, bending, stretching, drawing and wheeling. In the past few years materials for sheet metal forming and, technology have improved a lot. The improved materials have higher strength and more ductility than conventional sheet steel and therefore they have to be worked differently. For such steels conventional methods can not be applied totally. So there is a need for constant improvement in technology. Trial and error method currently in use increases lead time and is not economic also. To overcome the problems, use of simulation software in metal forming processes has increased significantly. The rapid development of software technology accompanied with lower cost computer hardware have enabled many manufacturing operations to be modeled cost-effectively that only a few years ago would have been considered impractical. However there are some difficulties in simulation of sheet metal forming process. For example it is never an easy task to select the correct software for a particular process. Various authors ascribe different causes for the difficulties. Among them the prominent ones are lacunae in elasto-plastic modeling, material behaviour, involved complexities and a lack of good elements. Apart from that the demands of sheet metal processes are increasing both with respect to the tolerance requirements of the finished part and with regard to geometric complexity of the part to be formed. A few years ago finite elements have been developed using Papcovitch-Neuber solutions of the Navier equation for the displacement function. Among these elements PN5X1 has the abilities to predict both displacements and stresses accurately. And recently the element is extended to include material nonlinearity and is working well for the small deformation range. To use this element for sheet metal forming it is necessary that the element should predict correct results for large deformations. In the present work we have further extended this element for large displacements and large rotation. In the literature there are various algorithms recommended for use with large deformation. Among them we have selected a suitable algorithm and verified its usefulness. First we have taken a simple truss and applied loads to cause large deflection. We observe adequate convergence with the chosen algorithm and then we extend it to PN5X1. in large deformation analysis, equilibrium is computed about the deformed shape. In the chosen algorithm we apply incremental loading and within each load step loop we iterate for equilibrium. We ensure error free solution (equilibrium) before additional loading is introduced. With the help of flowchart these processes have been depicted. A computer program in C, based on the above incremental method and equilibrium check has been written. For the purpose of verification of the program, we have solved some benchmark tests. We start with linear cases and then attempt a number of geometric nonlinear problems like- cantilever subjected to end shear, pinched cylinder with open end etc. We have also included the classical benchmark problem of the cantilever subjected to end moment. The present algorithm gives solutions which are in excellent agreement with those reported in the literature. Finally, we look at some aspects of the problem which require further investigation.

The use of positron emission tomography (PET) for imaging in oncology has grown rapidly in recent years. 2-[18F]-fluorodeoxyglucose (FDG) is the most common tracer of PET, although drawbacks exist. Radiolabeled 1-[11C]-acetate (C-AC) is a simple probe for evaluation of perfusion, anabolism (lipogenesis) and catabolism (oxidative metabolism) in all living tissues. This study explored the potential of AC PET in head and neck cancer, benign and malignant lymph nodes in prostate cancer and normal distribution.  In head and neck cancer, C-AC PET detected more primaries and lymph node metastases than FDG PET. The mean primary tumor volumes delineated by C-AC was 51% larger than that of FDG before radiotherapy (RT). Both FDG and C-AC PET tumor volumes must be carefully validated before used in clinical routine. Baseline tumor clearance rate (kmono) was higher in complete responders (CR) than that in partial responders (PR). kmono tended to correlate inversely with FDG SUV at baseline. Radiosensitive tumors might rely predominantly on oxidative metabolism for their biogenetic needs. kmono increased in PR during RT. The potential reversibility of impaired kmono in radioresistant tumors imply that treatment targeting the intermediary metabolism might improve the outcome. Tumor relative perfusion index (rF) and kmono were coupled in CR throughout the RT, but not in PR. Dynamic C-AC PET provides a new non-invasive method to simultaneously evaluate the tumor oxidative metabolism and perfusion which link the RT response in patients by a single tracer injection. In prostate cancer, elevated C-AC accumulation is common in benign inguinal lymph nodes, probably due to increased lipogenesis rather than lymphatic drainage. CT Hounsfield unit of benign nodes was lower than that of metastases, suggesting that density measurement using CT might improve the specificity of nodal staging of prostate cancer. A novel tracer 2-[18F]-fluoroacetate (F-AC) was synthesized and used for dynamic PET-CT imaging in animals. Compared with C-AC PET-CT, F-AC showed prolonged blood retention, no detectable trapping in myocardium and salivary glands, rapid excretion from liver to bile and urine and de-fluorination resulting in intensive skeletal activity. F-AC does not mimic the normal physiologic path of C-AC and appears to be of little use for assessment of perfusion, intermediary metabolism or lipogenesis.

Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks. Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost. Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack. Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++. / QC 20100707

Wireless Sensor Networks have found diverse applications from health to agriculture and industry. They have a potential to profound social changes, however, there are also some challenges that have to be addressed. One of the problems is the limited power source available to energize a sensor node. Longevity of a node is tied to its low power design. One of the areas where great power savings could be made is in nodal communication. Different schemes have been proposed targeting low power communication and short network latency. One of them is the introduction of ultra-low power wake-up receiver for monitoring the channel. Although it is a recent proposal, there has been many works published. In this thesis work, the focus is study and comparison of architectures for a wake-up receiver. As part of this study, an envelope detector based wake-up receiver is designed in 130nm CMOS Technology. It has been implemented in schematic and layout levels. It operates in the 2.4GHz ISM band and consumes a power consumption of 69µA at 1.2V supply voltage. A sensitivity of -52dBm is simulated while receiving 100kb/s OOK modulated wake-up signals. / This is a master's thesis work by a communication electronics student in a German company called IMST GmbH.

The aim of this paper is to examine the layout of public spaces and its effect on human behavior with focus on the relation between pedestrians and cyclists movement patterns in a specific path. The study emanates from the security aspect of pedestrians and cyclists, and builds upon previous theories and empirical studies about perception, security, information design, environmental psychology and behavior. The result shows that individual behavior and movement pattern differs with age, purpose, physical- and other conditions, and layout of the surroundings. A design proposal for improved layout of a path and a node between different oncoming paths has been developed to aid the users’ needs, where a separation of walkways and bike lanes forms zones of security for the purpose of better orientation and a better flow between the users. / Syftet med arbetet är att undersöka det offentliga rummets utformning och dess påverkan på det mänskliga beteendet med fokus på att studera relationen mellan gång-och cykeltrafikanternas rörelsemönster i ett specifikt gång-och cykelstråk. Studien utgår från trygghetsaspekten mellan gång- och cykeltrafikanter och bygger på samtida forskning om trafikanternas beteenden, teorier om perception, informationsdesign, stadsplanering, miljöpsykologi, samt empiriska studier. Resultatet visar att trafikanternas beteende och rörelsemönster skiljer sig beroende på ålder, mål med färden, fysiskt tillstånd och de egna förutsättningarna, samt omgivningen. Ett gestaltningsförslag på en förbättrad utformning av ett gång-och cykelstråk och en knutpunkt mellan olika mötande stråk har tagits fram utifrån trafikanternas behov, där en separering av gång -och cykelbana bildar olika trygghetszoner som ska bidra till en bättre orientering och ett bättre flöde mellan trafikanterna.

Multi-hop wireless networks or ad-hoc networks face several limiting characteristics that make it difficult to support a multitude of applications. It is in this context that we find smart antennas to find significant applications in these networks, owing to their ability to alleviate most of these limitations. The focus of my research is thus to investigate the use of smart antennas in ad-hoc networks and hence efficiently design network protocols that best leverage their capabilities in communication. There are two parts to the proposed objective of designing efficient network protocols that pertain to the nature of the smart antenna network considered, namely, homogeneous and heterogeneous smart antenna networks. Unlike heterogeneous smart antenna networks, where different devices in the network employ different antenna technologies, homogeneous smart antenna networks consist of devices employing the same antenna technology. Further, in homogeneous smart antenna networks, different antenna technologies operating in different strategies tend to perform the best in different network architectures, conditions and application requirements. This motivates the need for developing a {em unified} framework for designing efficient communication (medium access control and routing) protocols for homogeneous smart antenna networks in general. With the objective of designing such a unified framework, we start by designing efficient MAC and routing protocols for the most sophisticated of the smart antenna technologies, namely multiple-input multiple-output (MIMO) links. The capabilities of MIMO links form a super-set of those possible with other antenna technologies. Hence, the insights gained from the design of communication protocols for MIMO links are then used to develop unified MAC and routing frameworks for smart antennas in general. For heterogeneous smart antenna networks, we develop theoretical performance bounds by studying the impact of increasing degree of heterogeneity on network throughput performance. Given that the antenna technologies are already unified in the network, unified solutions are not required. However, we do develop efficient MAC and routing protocols to best leverage the available heterogeneous capabilities present in the network. We also design efficient cooperation strategies that will further help the communication protocols in exploiting the available heterogeneous capabilities in the network to the best possible extent.

In classical network information theory, information packets are treated as commodities, and the nodes of the network are only allowed to duplicate and forward the packets. The new paradigm of network coding, which was introduced by Ahlswede et al., states that if the nodes are permitted to combine the information packets and forward a function of them, the throughput of the network can dramatically increase. In this dissertation we focused on the design and analysis of low complexity network coding schemes for different topologies of wired and wireless networks. In the first part we studied the routing capacity of wired networks. We provided a description of the routing capacity region in terms of a finite set of linear inequalities. We next used this result to study the routing capacity region of undirected ring networks for two multimessage scenarios. Finally, we used new network coding bounds to prove the optimality of routing schemes in these two scenarios. In the second part, we studied node-constrained line and star networks. We derived the multiple multicast capacity region of node-constrained line networks based on a low complexity binary linear coding scheme. For star networks, we examined the multiple unicast problem and offered a linear coding scheme. Then we made a connection between the network coding in a node-constrained star network and the problem of index coding with side information. In the third part, we studied the linear deterministic model of relay networks (LDRN). We focused on a unicast session and derived a simple capacity-achieving transmission scheme. We obtained our scheme by a connection to the submodular flow problem through the application of tools from matroid theory and submodular optimization theory. We also offered polynomial-time algorithms for calculating the capacity of the network and the optimal coding scheme. In the final part, we considered the multicasting problem in an LDRN and proposed a new way to construct a coding scheme. Our construction is based on the notion of flow for a unicast session in the third part of this dissertation. We presented randomized and deterministic polynomial-time versions of our algorithm.

Nowadays the Learning Management System (LMS) platforms provide limited bidirectional, interactive mechanisms that they are competent to handle personal or small-scale distance learning systems. These mechanisms are designed for one to many online tutorials, and the technology utilizes single-input by single-output video stream technology, the video and audio data need to be coupled with one or many Multipoint Control Units (MCU) to mix or convert them into a single output media stream. In this platform MCU is critical to LMS, however, such system is expensive, lack of capacity and difficult to be massively deployed. Access-Grid (AG), an Open Source program, offers users capability to watch online multimedia audio-video contents from all the interconnected nodes of LMS through Multicast protocol, and supports groups-to-group high quality interactive distance learning. It requires all the networks to support the Multicast protocol. The MBONE (Multicast Backbone) can be used to connect different Multicast groups via Unicast communication. However, if the number of groups involving in the distance learning are large, the host computers or routers of the network will be heavily loaded because they need to handle the delivering of the media packets. To use a QuickBridge for aggregating and delivering packages is an alternative of LMS and requires (N-1) *N *BW bandwidth . For example, if there is a 15 nodes online conference and each node uses 800kbps data rate to transmit audio-video contents, then the demanded bandwidth of the aggregation is 168 Mbps. The way of dispersing and controlling the data flow becomes important factors and will greatly affect the quality of the AG online conference. This thesis modifies the procedure of AG and QuickBridge, and allows all the AG Clients to be able to transmit Unicast and Multicast packets in the online conference. It offers a Meeting Management Server to dynamically adjust topology and hub points, and achieves better elasticity to the system. By modifying VIC and RAT procedure, the system controls the outbound audio-video data flow from each nodes of online conference, and reduces the demand of bandwidth. The system can directly provide end-to-end conferencing, using Unicast communication to connect the nodes in different Multicast groups, or using the Multicast on the backbone and then using unicast communication to the local nodes. The functionality of the LMS can be improved and capable of supporting multi-windows to multi-user interactive online conference for the users. The results of this thesis can be applied upon real-time interactive distance learning, online video conferencing and interactive online TV. It also helps to lower the cost of the system and reduce the requirement of network bandwidth.

In this thesis, we study the energy efficient coverage and connectivity problem in wireless sensor networks (WSNs). We try to locate heterogeneous sensors and route data generated to a base station under two conflicting objectives: minimization of network cost and maximization of network lifetime. We aim at satisfying connectivity and coverage requirements as well as sensor node and link capacity constraints. We propose mathematical formulations and use an exact solution approach to find Pareto optimal solutions for the problem. We also develop a multiobjective genetic algorithm to approximate the efficient frontier, as the exact solution approach requires long computation times. We experiment with our genetic algorithm on randomly generated problems to test how well the heuristic procedure approximates the efficient frontier. Our results show that our genetic algorithm approximates the efficient frontier well in reasonable computation times.

In this study, we considered a heterogeneous, clustered WSN, which consists of two types of nodes (clusterheads and sensor nodes) deployed randomly over a sensing field. We investigated two cases based on how clusterheads can reach the sink: direct and multi-hop communication cases. Network dimensioning problems in randomly deployed WSNs are among the most challenging ones as the attributes of these networks are mostly non-deterministic. We focused on a number of network dimensioning problems based on the connected coverage concept, which is the degree of coverage achieved by only the connected devices. To evaluate connected coverage, we introduced the term cluster size, which is the expected value of the area covered by a clusterhead together with sensor nodes connected to it. We derived formulas for the cluster size and validated them by computer simulations. By using the cluster size formulas, we proposed a method to dimension a WSN for given targeted connected coverage. Furthermore, we formulated cost optimization problems for direct and multi-hop communication cases. These formulations utilize not only cluster size formulas but also the well-connectivity concept. We suggested some search heuristics to solve these optimization problems. Additionally, we justified that, in practical cases, node heterogeneity can provide lower cost solutions. We also investigated the lifetime of WSNs and for mulated a cost optimization problem with connected coverage and lifetime constraints. By solving this optimization problem, one can determine the number of nodes of each type and the initial energies of each type of node that leads to lowest cost solution while satisfying the minimum connected coverage and minimum lifetime requirements.