No description available.

No description available.

No description available.

No description available.

No description available.

“Connected society” where everything and everyone are connected at any time and on any location brings new challenges for the network operators. This leads to the need of upgrading the transport networks as the segment of Internet infrastructure connecting the fixed users and mobile base stations to the core/aggregation in order to provide high sustainable bandwidth, as well as supporting a massive number of connected devices. To do this, operators need to change the way that access networks are currently deployed. The future access network technologies will need to support very high capacity and very long distances, which are the inherited characteristics of optical transmission. Hence, optical fiber technology is recognized as the only future proof technology for broadband access. Capacity upgrade in the access networks can lead to a huge capacity demand in the backbone network. One promising solution to address this problem, is to keep the local traffic close to the end users as much as possible, and prevent unnecessary propagation of this type of traffic through the backbone. In this way, operators would be able to expand their access network without the significant capacity upgrade in the higher aggregation layers. Motivated by this need, a comprehensive evaluation of optical access networks is carried out in this thesis regarding ability of accommodating local traffic and amount of possible saving in the backbone by implementing locality awareness schemes. Meanwhile, next generation optical access (NGOA) networks have to provide high capacity at low cost while fulfilling the increasing reliability requirements of future services and customers. Therefore, finding cost-efficient and reliable alternative for future broadband access is one of the most important contributions of this thesis. We analyzed the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the proposed protection mechanism. Among different NGOA architectures, hybrid time and wavelength division multiplexing passive optical network (TWDM PON) is considered as a proper candidate providing high capacity and large coverage. Therefore, this approach is further analyzed and several tailored protection schemes with high flexibility are proposed to statisfy different requirements from the residential and business users in the same PON.  The work carried out in the thesis has proved that TWDM PON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Considering some other advantages such as low power consumption and high flexibility in resource allocation of this architecture, it has high potential to be the best candidate for NGOA networks.  Moreover, new deployments of radio access networks supporting the increasing capacity demand of mobile users lead to the upgrade of the backhaul segment as a part of broadband access infrastructure. Hence, this thesis also contributes with a comprehensive techno-economic evaluation methodology for mobile backhaul. Several technologies are investigated in order to find the most cost-efficient solution for backhauling the high capacity mobile networks.  Finally, a PON-based mobile backhaul with high capacity and low latency has been proposed for handling coordinated multipoint transmission systems in order to achieve high quality of experience for mobile users. / <p>QC 20150320</p>

Laser forming is an innovative technique that uses a defocused laser beam to form sheet metal by thermal stresses rather than external forces. Promising potential applications of laser forming include rapid prototyping, straightening, aligning and adjusting of macro/micro-metallic components. Research to-date on laser forming has been largely focused, theoretically and experimentally, on the problem of characterization of process parameters on the forming results, and computational simulations of laser forming remain limited only providing the insight into the process. This study investigates the laser forming processes using the finite element analysis with respect to material responses during the processes, including complex processes, process optimization, process reliability and the effects of thermal and mechanical material properties. The first part of this thesis describes a nonlinear transient three-dimensional heat transfer finite element model and a rate dependent three-dimensional deformation model, which are developed for the laser forming simulations. Simulations are performed using an indirect coupled thermal-structural method for the processes of a straight-line heating, a circle-line heating, and a laser micro-adjustment. The thermo-mechanical behaviours during the straight-line heating process are presented in terms of temperature, stress and strain, and displacement distributions. The emphasis in the circle-line heating simulations is placed on the characterization of the quality of the deformed geometry by obtaining the radial and circumferential waviness. The micron size movements induced by laser point heating are focused the simulations of the micro-adjustment process. Simulation results are validated by comparison with published data or correlation to engineering point of view. The second part of this thesis presents the development of an effective method to determine optimum process parameters in laser forming. For the process optimization, design optimisation techniques are introduced into the finite element analysis of the laser forming process. The optimum parameter values to produce a predefined bend angle of 3° in the straight-line heating process are sought by two optimization procedures - one is the procedure involving the non-gradient method and the other is the gradient-based method. Optimum values of laser power, feed rate, beam diameter and number of passes are determined to produce a predefined bend angle in a multiple straight-line heating process using the two optimization procedures. A more suitable optimisation method for laser forming is chosen, which is used for a new optimisation problem to generate a maximum bend angle in a single pass of laser forming. In the third part of this thesis, a strategy to assess the reliability of the laser forming process is established by employing a well-known reliability analysis method, the Monte Carlo simulation. Robustness of the straight-line heating process of producing 3° with the optimum parameters determined by process optimization is evaluated with regard to the uncertain input variables of laser power, feed rate, plate thickness and coefficient of thermal expansion via the Monte Carlo simulations based on the finite element simulations of the process. The final part of this thesis identifies the effects of material properties on the bend angle resulting from laser forming. Process sensitivity to the properties of coefficient of thermal expansion, thermal conductivity, specific heat capacity and elastic modulus is investigated by measuring the Pearson product-moment correlation coefficient between the properties and the bend angle, which are based on the Monte Carlo simulations of laser forming. The conclusion is that the developed finite element models contribute to a better understanding of the laser forming process, and the optimization procedure is able to be used for straightening, aligning and adjusting of components.

Dependable communication links for unmanned aerial vehicles (UAV) are crucial to operational reliability and mission success. This study is focused on evaluating the probability of successful communication links for small UAVs. A program based on the Friis Transmission Equation was developed to calculate the power received in a line-of-sight communication link. The program was used to evaluate the probability of success for a variety of flight pa

Multi-piece wheels or rims used on large vehicles such as trucks, tractors, trailers, buses and off-road machines have often been known for their dangerous properties because of the large number of catastrophic accidents involving them. The main causes for these accidents range from dislocation of the rim components in the assembly, mismatch of the components, manufacturing tolerances, corrosion of components to tires. A finite element analysis of a two-piece rim design similar to one manufactured by some of the prominent rim manufacturers in the USA is undertaken. A linear static deformation analysis is performed with the appropriate loading and boundary conditions. The dislocation of the side ring with respect to the rim base and its original designer intent position is established using simulation results from ANSYS and actual rim failure cases. Reliability of the multi-piece rims is analyzed using the failure data provided by the rim manufacturers in connection with a lawsuit (Civil Action No. 88-C-1374). The data was analyzed using MINITAB. The effect of an OSHA standard (1910.177) on servicing multi-piece rims was studied for change in failure patterns of different rims. The hazard functions were plotted and failure rates were calculated for each type of rim. The failure rates were found to be increasing suggesting that the standard had minimal effect on the accidents and failures. The lack of proper service personnel training and design defects were suggested as the probable reasons for the increasing failure rates.

The increasing complexity of net-centric warfare requires assets to cooperate to achieve mission success. Such cooperation requires the integration of many heterogeneous systems into an interoperable system-of-systems (SoS). Interoperability can be considered a metric of an architecture, and must be understood as early as the conceptual design phase. This thesis approaches interoperability by first creating a general definition of interoperability, identifying factors that affect it, surveying existing models of interoperability, and identifying fields that can be leveraged to perform a measurement, including reliability theory and graph theory. The main contribution of this thesis is the development of the Architectural Resource Transfer and Exchange Measurement of Interoperability for Systems of Systems, or ARTEMIS methodology. ARTEMIS first outlines a quantitative measurement of system pair interoperability using reliability in series and in parallel. This step incorporates operational requirements and the capabilities of the system pair. Next, a matrix of interoperability values for each resource exchange in an operational process is constructed. These matrices can be used to calculate the interoperability of a single resource exchange, IResource, and layered to generate a weighted adjacency matrix of the entire SoS. This matrix can be plugged in to a separate model to link interoperability with the mission performance of the system of systems. One output of the M&S is a single value ISoS that can be used to rank architecture alternatives based on their interoperability. This allows decision makers to narrow down a large design space quickly using interoperability as one of several criteria, such as cost, complexity, or risk. A canonical problem was used to test the methodology. A discrete event simulation was constructed to model a small unmanned aircraft system performing a search and rescue mission. Experiments were performed to understand how changing the systems' interoperability affected the overall interoperability; how the resource transfer matrices were layered; and if the outputs could be calculated without time- and computationally-intensive stochastic modeling. It was found that although a series model of reliability could predict a range of IResource, M&S is required to provide exact values useful for ranking. Overall interoperability ISoS can be predicted using a weighted average of IResource, but the weights must be determined by M&S. Because a single interoperability value based on performance is not unique to an architecture configuration, network analysis was conducted to assess further properties of a system of systems that may affect cost or vulnerability of the network. The eigenvalue-based Coefficient of Networked Effects (CNE) was assessed and found to be an appropriate measure of network complexity. Using the outputs of the discrete event simulation, it was found that networks with higher interoperability tended to have more networked effects. However, there was not enough correlation between the two metrics to use them interchangeably. ARTEMIS recommends that both metrics be used to assess a networked SoS. This methodology is of extreme value to decision-makers by enabling trade studies at the SoS level that were not possible previously. It can provide decision-makers with information about an architecture and allow them to compare existing and potential systems of systems during the early phases of acquisition. This method is unique because it does not rely on qualitative assessments of technology maturity or adherence to standards. By enabling a rigorous, objective mathematical measurement of interoperability, decision-makers will better be able to select architecture alternatives that meet interoperability goals and fulfill future capability requirements.