Optimal Energy Allocation for Kalman Filtering over Packet Dropping Links with Imperfect Acknowledgments and Energy Harvesting Constraints

This paper presents a design methodology for optimal transmission energy allocation at a sensor equipped with energy harvesting technology for remote state estimation of linear stochastic dynamical systems. In this framework, the sensor measurements as noisy versions of the system states are sent to the receiver over a packet dropping communication channel. The packet dropout probabilities of the channel depend on both the sensor's transmission energies and time varying wireless fading channel gains. The sensor has access to an energy harvesting source which is an everlasting but unreliable energy source compared to conventional batteries with fixed energy storages. The receiver performs optimal state estimation with random packet dropouts to minimize the estimation error covariances based on received measurements. The receiver also sends packet receipt acknowledgments to the sensor via an erroneous feedback communication channel which is itself packet dropping. The objective is to design optimal transmission energy allocation at the energy harvesting sensor to minimize either a finite-time horizon sum or a long term average (infinite-time horizon) of the trace of the expected estimation error covariance of the receiver's Kalman filter. These problems are formulated as Markov decision processes with imperfect state information. The optimal transmission energy allocation policies are obtained by the use of dynamic programming techniques. Using the concept of submodularity, the structure of the optimal transmission energy policies are studied. Suboptimal solutions are also discussed which are far less computationally intensive than optimal solutions. Numerical simulation results are presented illustrating the performance of the energy allocation algorithms.Comment: Submitted to IEEE Transactions on Automatic Control. arXiv admin note: text overlap with arXiv:1402.663

Configraphics:

This dissertation reports a PhD research on mathematical-computational models, methods, and techniques for analysis, synthesis, and evaluation of spatial configurations in architecture and urban design. Spatial configuration is a technical term that refers to the particular way in which a set of spaces are connected to one another as a network. Spatial configuration affects safety, security, and efficiency of functioning of complex buildings by facilitating certain patterns of movement and/or impeding other patterns. In cities and suburban built environments, spatial configuration affects accessibilities and influences travel behavioural patterns, e.g. choosing walking and cycling for short trips instead of travelling by cars. As such, spatial configuration effectively influences the social, economic, and environmental functioning of cities and complex buildings, by conducting human movement patterns. In this research, graph theory is used to mathematically model spatial configurations in order to provide intuitive ways of studying and designing spatial arrangements for architects and urban designers. The methods and tools presented in this dissertation are applicable in: arranging spatial layouts based on configuration graphs, e.g. by using bubble diagrams to ensure certain spatial requirements and qualities in complex buildings; and analysing the potential effects of decisions on the likely spatial performance of buildings and on mobility patterns in built environments for systematic comparison of designs or plans, e.g. as to their aptitude for pedestrians and cyclists. The dissertation reports two parallel tracks of work on architectural and urban configurations. The core concept of the architectural configuration track is the ‘bubble diagram’ and the core concept of the urban configuration track is the ‘easiest paths’ for walking and cycling. Walking and cycling have been chosen as the foci of this theme as they involve active physical, cognitive, and social encounter of people with built environments, all of which are influenced by spatial configuration. The methodologies presented in this dissertation have been implemented in design toolkits and made publicly available as freeware applications

Critical analysis and evaluation of different automata processing accelerators on large-scale datasets

Many established and emerging applications perform at their core some form of pattern matching, a computation that maps naturally onto finite automata abstractions. As a consequence, in recent years there has been a substantial amount of work on high-speed automata processing, which has led to a number of implementations targeting a variety of parallel platforms: from multicore CPUs, to GPUs, to FPGAs, to ASICs, to Network Processors. More recently, Micron has announced its Automata Processor (AP), a DRAMbased accelerator of non-deterministic finite automata (NFAs). Despite the abundance of work in this domain, the advantages and disadvantages of different automata processing accelerators and the innovation space in this area are still unclear. In this work we target this problem. In particular, to allow an apples-to-apples comparison, we focus on NFA acceleration on three platforms: GPUs, FPGAs and Micron's AP. We discuss the automata optimizations that are applicable to all three platforms. We perform an evaluation on large-scale datasets: to this end, we propose an NFA partitioning algorithm that minimizes the number of state replications required to maintain functional equivalence with an unpartitioned NFA, and we evaluate the scalability of each implementation to both large NFAs and large numbers of input streams. Our experimental evaluation covers resource utilization, throughput, and preprocessing cost

An Optimal Transmission Strategy for Kalman Filtering over Packet Dropping Links with Imperfect Acknowledgements

This paper presents a novel design methodology for optimal transmission policies at a smart sensor to remotely estimate the state of a stable linear stochastic dynamical system. The sensor makes measurements of the process and forms estimates of the state using a local Kalman filter. The sensor transmits quantized information over a packet dropping link to the remote receiver. The receiver sends packet receipt acknowledgments back to the sensor via an erroneous feedback communication channel which is itself packet dropping. The key novelty of this formulation is that the smart sensor decides, at each discrete time instant, whether to transmit a quantized version of either its local state estimate or its local innovation. The objective is to design optimal transmission policies in order to minimize a long term average cost function as a convex combination of the receiver's expected estimation error covariance and the energy needed to transmit the packets. The optimal transmission policy is obtained by the use of dynamic programming techniques. Using the concept of submodularity, the optimality of a threshold policy in the case of scalar systems with perfect packet receipt acknowledgments is proved. Suboptimal solutions and their structural results are also discussed. Numerical results are presented illustrating the performance of the optimal and suboptimal transmission policies.Comment: Conditionally accepted in IEEE Transactions on Control of Network System

Assessment of radiation doses to the West Rand public due to inhalation of 222Rn and its daughter products

A dissertation submitted to the Faculty of Science, University of Witwatersrand, Johannesburg, in fulfilment of the requirements for degree of Master of Science, Johannesburg, 2012Radon is a radioactive gas which contributes significantly to the natural radiation background. For this reason, it is important to estimate doses to representative member of the public especially in areas with an elevated concentration of naturally occurring radionuclides e.g. the Witwatersrand Basin. This study presents the results of radon monitoring carried out in selected houses close to the gold and uranium mining operations in South Africa. Monitoring of radon and its progeny was performed inside selected houses that were built about 100 years ago, using a calibrated AlphaGuard PQ2000PRO active instrument. Radon monitoring the interpretation of the results took into consideration meteorological parameters, which are critical for evaluating radon concentrations. The results obtained by AlphaGuard were compared with long-term measurements performed in the same locations using the passive RGM (Radiation Gas Monitor) caps manufactured in South Africa. Indoor monitoring of radon and its progeny was supplemented by additional monitoring outdoors, around the selected houses, the slimes dams and in several selected locations close to mining operations. Assessment of doses due to inhalation of air contaminated by radon and its progeny was based on the obtained results of radon monitoring and the doses were compared to internationally accepted intervention and action levels established by International Commission of Radiological Protection 65 (ICRP) and various regulatory authorities throughout the world. The values of the indoor radon concentrations were compared with the international recommendations, and since the meteorological parameters are critical for analysing the radon concentration, an effort has been made to find a possible correlation between them and the indoor radon concentration.XL201

FATIGUE BEHAVIOR AND DEFECT-BASED LIFE PREDICTION OF ALUMINUM CASTINGS UNDER AXIAL, TORSION, AND MULTIAXIAL LOADINGS

Defects in metallic components can be formed in many manufacturing techniques. These defects can significantly affect the mechanical properties, especially fatigue behavior of industrial components. In this study, the effect of defects on fatigue behavior and life prediction of a cast aluminum alloy, as an illustrative material containing defects, was investigated. Defect characterization was performed by using metallography, X-ray radiography and micro-computed tomography techniques. The variability of defects between the specimens of two sizes, different porosity levels, and based on location within the specimens were studied. The maximum defect size within the specimens was also estimated using extreme value statistics. In addition to fully-reversed fatigue tests, tension-tension as well as rotating bending tests were conducted to study the effects of mean stress and stress gradient. Fatigue tests were also performed under torsion, and under in-phase and out-of-phase combined axial-torsion loadings. Fatigue life predictions were performed using long and small crack growth models based on the observed defects size from fracture surfaces, as well as the maximum defect size estimated by extreme value statistics. Considering the effect of mean stress and overall plastic deformation, a small crack growth model is proposed which predicts fatigue lives in very good agreement with experimental results. Variable amplitude loading fatigue test results representative of service load histories were also predicted following both S-N and fracture mechanics approaches and the results are compared and discussed with reference to the experiments conducted

Toy Gun instead of Doll: Politicization of Children's Literature in the Declining Public Sphere of Iran (1963- 1979)

Abstract The present research is an attempt to shed light on the process of politicization of children’s literature in the shaky public realm of Iran during a historical period between 1963 and 1979. The main purpose has been to show how under the pressure of the absolutist regime of Pahlavi many suppressed conflicts have not had any spaces and realms to be manifested and discussed in public or through the free channels of communication clearly, openly and transparently. Consequently, children’s literature has been utilized as a political instrument to give expression to the latent conflicts in the Iranian public realm. Disagreements, contradictions, oppositions in terms of the governmental policy of peremptory socioeconomic development and political underdevelopment, did not have any opportunity to be vocalized in a rational, critical dialogue or in a clear direct debate. Therefore, many of these strangled voices in the Iranian public sphere, or at least parts of demands of dissident intellectuals, have been reflected in the realms like children’s literature, which are normally irrelevant to politics. It means that children’s literature has been politicized and used instrumentally to criticize the status quo. It is interesting that institutions like ‘the center for the intellectual development of children and adolescents’ that were inaugurated in 1965 were, in fact, governmental organizations with no political purpose at all. They opened to function in the same direction with socioeconomic modernization and cultural development specifically according to the capitalist model. However, critics and dissident groups, particularly the leftist and nativist intellectuals, utilized such realms exactly for their political purposes. Thus, it seems that for them children’s literature acts as a façade behind it antagonistic features of the political issues like: the growing gap between different economic classes, or between traditional and modern parts of the Iranian society could be expressed in an indirect and unclear way through artistic productions for children. So in this research it has been described how in the lack of the realms of public debate about disagreements and contradictory interests and ideas, the antagonistic features of the political has penetrated into one of the most innocent realm of communication according to the public institutions of a democratic society, namely, children’s literature. By reading two short stories for children by Samad Behrangi, and by using semiotics as a qualitative method of text analysis, an attempt has been made to reveal some of the suppressed struggles and conflicts within the declining public sphere of Iran. It seems that suppressed public demands and latent conflicts in terms of freedom, justice, independence and so on can be uncovered by the semiotic interpretation of these texts and looking beneath the surface of these juvenile literary works in the brittle Iranian public realm (1963- 1979). Keywords: Politicization, public spher