Using Coding to Improve Localization and Backscatter Communication Performance in Low-Power Sensor Networks

Backscatter communication is an emerging wireless technology that recently has gained an increase in attention from both academic and industry circles. The key innovation of the technology is the ability of ultra-low power devices to utilize nearby existing radio signals to communicate. As there is no need to generate their own energetic radio signal, the devices can benefit from a simple design, are very inexpensive and are extremely energy efficient compared with traditional wireless communication. These benefits have made backscatter communication a desirable candidate for distributed wireless sensor network applications with energy constraints.

The backscatter channel presents a unique set of challenges. Unlike a conventional one-way communication (in which the information source is also the energy source), the backscatter channel experiences strong self-interference and spread Doppler clutter that mask the information-bearing (modulated) signal scattered from the device. Both of these sources of interference arise from the scattering of the transmitted signal off of objects, both stationary and moving, in the environment. Additionally, the measurement of the location of the backscatter device is negatively affected by both the clutter and the modulation of the signal return.

This work proposes a channel coding framework for the backscatter channel consisting of a bi-static transmitter/receiver pair and a quasi-cooperative transponder. It proposes to use run-length limited coding to mitigate the background self-interference and spread-Doppler clutter with only a small decrease in communication rate. The proposed method applies to both binary phase-shift keying (BPSK) and quadrature-amplitude modulation (QAM) scheme and provides an increase in rate by up to a factor of two compared with previous methods.

Additionally, this work analyzes the use of frequency modulation and bi-phase waveform coding for the transmitted (interrogating) waveform for high precision range estimation of the transponder location. Compared to previous methods, optimal lower range sidelobes are achieved. Moreover, since both the transmitted (interrogating) waveform coding and transponder communication coding result in instantaneous phase modulation of the signal, cross-interference between localization and communication tasks exists. Phase discriminating algorithm is proposed to make it possible to separate the waveform coding from the communication coding, upon reception, and achieve localization with increased signal energy by up to 3 dB compared with previous reported results.

The joint communication-localization framework also enables a low-complexity receiver design because the same radio is used both for localization and communication.

Simulations comparing the performance of different codes corroborate the theoretical results and offer possible trade-off between information rate and clutter mitigation as well as a trade-off between choice of waveform-channel coding pairs. Experimental results from a brass-board microwave system in an indoor environment are also presented and discussed.

The emerging ASEAN approach to mutual recognition : a comparison with Europe, trans-Tasman, and North America

Existing studies on mutual recognition agreements (MRAs) are mostly based on the European experience. In this paper, we will examine the ongoing attempts to establish a mutual recognition architecture in the Association of Southeast Asian Nations (ASEAN) and seek to explain the region's unique approach to MRAs, which can be classified as a "hub and spoke" model of mutual recognition. On one hand, ASEAN is attempting to establish a quasi-supranational ASEAN-level mechanism to confer "ASEAN qualification" effective in the entire ASEAN region. On the other hand, ASEAN MRAs respect members' national sovereignty, and it is national authorities, not ASEAN institutions, who have the ultimate power to approve or disapprove the supply of services by ASEAN qualification holders. Such a mixed approach to mutual recognition can be best understood as a centralized mechanism for learning-by-doing, rather than centralized recognition per se.

Power, Arab media Moguldum & gender rights as entertainment in the Middle East

Discourse is a giant field of research and gender related rights are still a disputed area of thinking. Thus, when Arab transnational satellite televisions produce dialogues, images, stories and narratives about the disputed “universal” gender rights in the Middle East, the big questions remain how and why. According to De Beauvoir (1949), one becomes woman and to Butler (1990) one is not born a gender at all but is “done” and “undone” to become one via discourse. Islamic feminism speaks of a cultural/religious specificity in defending women rights and even gender diversity based on new Quranic interpretations. The gender, “Al-Naw’u”, remains synonym to sex “Al Jins” as gender and queer theories never developed in Arabic in tandem with the European institutions or the theories of the19th century– especially those ideas emerging from studies of the mental asylum. This research tries to understand gender related “rights” and “wrongs” as manifest in the discursive institutions owned by media mogul Prince Al Waleed Ben Talal Al Saud. The trouble of such a study is lexical, ideological and institutional at the same time. Since we lack a critique of the discourses and narratives addressed in the pan-Arab satellite channels, in general it is difficult to understand their significance and influence in everyday life practices. What language is used to speak of gender rights or wrongs? Which ideology is favoured in this practice of legitimisation and/or policing? Using case studies, CDA of social and religious talk shows, narrative analysis of Arabic cinemas, this research adapted triangulation to show the complexity of conversing and narrating gender related content at the micro and macro levels within an institution of power. Using semi-structured interviews from fieldwork in Egypt (2009) and Lebanon (2011), archive research and online ethnography, the research exposes the power structure under which gender discourses evolve. It emerges that gender content is abundant on the Pan Arab satellite space, “manufactured” on talk shows and plotted tactfully in the cinematic “creative-act”. The result is a complex discourse of gender content that scratches the surface calling for interpretation. So how and why do gender rights and wrongs find place on Prince Al Waleed’s Media Empire?

Power control in cognitive radios, Internet-of Things (IoT) for factories and industrial automation

Cognitive radio (CR) is fast emerging as a promising technology that can meet the machine-to machine (M2M) communication requirements for spectrum utilization and power control for large number of machines/devices expected to be connected to the Internet-of Things (IoT). Power control in CR as a secondary user can been modelled as a non-cooperative game cost function to quantify and reduce its effects of interference while occupying the same spectrum as primary user without adversely affecting the required quality of service (QoS) in the network. In this paper a power loss exponent that factors in diverse operating environments for IoT is employed in the non-cooperative game cost function to quantify the required power of transmission in the network. The approach would enable various CRs to transmit with lesser power thereby saving battery consumption or increasing the number of secondary users thereby optimizing the network resources efficiently.

Real-time load-side control of electric power systems

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems.

(1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control.

(2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Fast and efficient user pairing and power allocation algorithm for non-orthogonal multiple access in cellular networks

Non-orthogonal multiple access (NOMA) is emerging as a promising multiple access technology for the fifth generation cellular networks to address the fast growing mobile data traffic. It applies superposition coding in transmitters, allowing simultaneous allocation of the same frequency resource to multiple intra-cell users. Successive interference cancellation is used at the receivers to cancel intra-cell interference. User pairing and power allocation (UPPA) is a key design aspect of NOMA. Existing UPPA algorithms are mainly based on exhaustive search method with extensive computation complexity, which can severely affect the NOMA performance. A fast proportional fairness (PF) scheduling based UPPA algorithm is proposed to address the problem. The novel idea is to form user pairs around the users with the highest PF metrics with pre-configured fixed power allocation. Systemlevel simulation results show that the proposed algorithm is significantly faster (seven times faster for the scenario with 20 users) with a negligible throughput loss than the existing exhaustive search algorithm.

An Islanding Detection Method based on Impedance Estimation and Grid Identification for Grid-Tie Distributed Power Generation Systems

Power system policies are broadly on track to escalate the use of renewable energy resources in electric power generation. Integration of dispersed generation to the utility network not only intensifies the benefits of renewable generation but also introduces further advantages such as power quality enhancement and freedom of power generation for the consumers. However, issues arise from the integration of distributed generators to the existing utility grid are as significant as its benefits. The issues are aggravated as the number of grid-connected distributed generators increases. Therefore, power quality demands become stricter to ensure a safe and proper advancement towards the emerging smart grid. In this regard, system protection is the area that is highly affected as the grid-connected distributed generation share in electricity generation increases. Islanding detection, amongst all protection issues, is the most important concern for a power system with high penetration of distributed sources. Islanding occurs when a portion of the distribution network which includes one or more distributed generation units and local loads is disconnected from the remaining portion of the grid. Upon formation of a power island, it remains energized due to the presence of one or more distributed sources. This thesis introduces a new islanding detection technique based on an enhanced multi-layer scheme that shows superior performance over the existing techniques. It provides improved solutions for safety and protection of power systems and distributed sources that are capable of operating in grid-connected mode. The proposed active method offers negligible non-detection zone. It is applicable to micro-grids with a number of distributed generation sources without sacrificing the dynamic response of the system. In addition, the information obtained from the proposed scheme allows for smooth transition to stand-alone operation if required. The proposed technique paves the path towards a comprehensive protection solution for future power networks. The proposed method is converter-resident and all power conversion systems that are operating based on power electronics converters can benefit from this method. The theoretical analysis is presented, and extensive simulation results confirm the validity of the analytical work.

Las limitaciones de la implementación del soft power en la política exterior China hacia Chile (2002-2012)

Este estudio de caso tiene como objetivo principal analizar la manera en la que las limitaciones de la implementación del soft power de la política exterior China hacia Chile han condicionado las relaciones sino-chilenas al aspecto económico en detrimento del aspecto político y cultural bajo el gobierno de Hu Jintao (2002-2012). Este análisis se elabora a partir de la conceptualización hecha por Joseph Nye en torno al soft power; al cual, se le han otorgado características adicionales dadas por teóricos chinos, como la introducción y, fortalecimiento de China a través de la diplomacia pública para la proyección de su imagen internacional, basada en la cooperación y beneficio mutuo, con el fin de lograr el desarrollo pacífico en el siglo XXI.

Soft Power del Vaticano en el reconocimiento de Palestina como Estado

Desde 1945, el inicio de la cuestión palestina, el país ha sufrido una serie de transformaciones e intervenciones en su soberanía y en legitimidad, las cuales siguen en discusión actualmente; y han dado como resultado el estudio del reconocimiento de Palestina como Estado. Es pertinente hacer un acercamiento a este tema desde la variable religiosa (Vaticano), teniendo en cuenta el gran número de lugares sagrados que hay en la región de Palestina y la variable religiosa del conflicto Palestino-israelí. Desde la mirada del Soft Power, concepto que ha venido tomando fuerza en la academia desde 1980, podemos acercarnos al objeto de estudio y dilucidar las injerencias de este actor. Mediante una aproximación cualitativa, que conlleva análisis del discurso, análisis histórico y análisis de política exterior, se logrará obtener el resultado esperado, que es entender de qué manera el Vaticano ejerce influencia (ideológica y cultural) en el Sistema Internacional, en el asunto del reconocimiento de Palestina como Estado.

Partitioning The Net Effect Of Host Diversity On An Emerging Amphibian Pathogen.

The 'dilution effect' (DE) hypothesis predicts that diverse host communities will show reduced disease. The underlying causes of pathogen dilution are complex, because they involve non-additive (driven by host interactions and differential habitat use) and additive (controlled by host species composition) mechanisms. Here, we used measures of complementarity and selection traditionally employed in the field of biodiversity-ecosystem function (BEF) to quantify the net effect of host diversity on disease dynamics of the amphibian-killing fungus Batrachochytrium dendrobatidis (Bd). Complementarity occurs when average infection load in diverse host assemblages departs from that of each component species in uniform populations. Selection measures the disproportionate impact of a particular species in diverse assemblages compared with its performance in uniform populations, and therefore has strong additive and non-additive properties. We experimentally infected tropical amphibian species of varying life histories, in single- and multi-host treatments, and measured individual Bd infection loads. Host diversity reduced Bd infection in amphibians through a mechanism analogous to complementarity (sensu BEF), potentially by reducing shared habitat use and transmission among hosts. Additionally, the selection component indicated that one particular terrestrial species showed reduced infection loads in diverse assemblages at the expense of neighbouring aquatic hosts becoming heavily infected. By partitioning components of diversity, our findings underscore the importance of additive and non-additive mechanisms underlying the DE.

Chikungunya In Brazil: An Emerging Challenge.

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As vozes da sociedade: letramento, consciência e poder

The dialectic tension between the phenomenon of illiteracy and the remedial efforts of the literate to provide a voice for those who don t have one, reflects at the same time the difficulties that the emerging discourses have to struggle with, and highlights the importance of this struggle as one that belongs to the opressed, not the well-meaning educators and political activists. It also informs the latter s efforts on behalf of the uneducated. Naturally these issues have attracted a good deal of attention of some specialists in South America. There is now a movement afoot there that aims at placing illiterate discourse inside the societal discourse proper without letting the latter manipulate the former for its own ends. I will address the typical exigencies and limitations inherent in such efforts, but at the same time point to new ways of understanding and handling the problem of literacy in a developing country.

Comparação entre métodos para mensuração da potência aeróbia em atletas tetraplégicos= : Comparison of methods for aerobic power assessment in athletes with tetraplegia

Universidade Estadual de Campinas . Faculdade de Educação Física

Reliability and discriminatory power of methods for dental plaque quantification

OBJECTIVE: This in situ study evaluated the discriminatory power and reliability of methods of dental plaque quantification and the relationship between visual indices (VI) and fluorescence camera (FC) to detect plaque. MATERIAL AND METHODS: Six volunteers used palatal appliances with six bovine enamel blocks presenting different stages of plaque accumulation. The presence of plaque with and without disclosing was assessed using VI. Images were obtained with FC and digital camera in both conditions. The area covered by plaque was assessed. Examinations were done by two independent examiners. Data were analyzed by Kruskal-Wallis and Kappa tests to compare different conditions of samples and to assess the inter-examiner reproducibility. RESULTS: Some methods presented adequate reproducibility. The Turesky index and the assessment of area covered by disclosed plaque in the FC images presented the highest discriminatory powers. CONCLUSION: The Turesky index and images with FC with disclosing present good reliability and discriminatory power in quantifying dental plaque.