Design of a Web Based Underwater Acoustic Communication Testbed and Simulation Platform

Wireless Personal Communications - Underwater Wireless Sensor Networks (UWSNs) are playing a vital role in exploring the unseen underwater (UW) natural resources. However, performance evaluation of...     

Special Issue: Technological Advancements in Wireless and Optical Communication Systems

Wireless Personal Communications -     

A New Efficiency-Weighted Strategy for Continuous Human/Robot Cooperation in Navigation

Autonomous robots are capable of navigating on their own. Shared control approaches, however, allow humans to make some navigation decisions. This is typically executed either by overriding the human or the robot control at some specific situations. In this paper, we propose a method to allow cooperation between humans and robots at each point of any given trajectory so that both have some weight in the emergent behavior of the mobile robot. This is achieved by evaluating their efficiencies at each time instant and combining their commands into a single order. In order to achieve a seamless combination, this procedure is integrated into a bottom-up architecture via a reactive layer. We have tested the proposed method using a real robot and several volunteers, and results have been satisfactory both from a quantitative and qualitative point of view.     

A New Sonar-based Landmark for Localization in Indoor Environments

This paper presents a new sonar based landmark to represent significant places in an environment for localization purposes. This landmark is based on extracting the contour free of obstacles around the robot from a local evidence grid. This contour is represented by its curvature, calculated by a noise-resistant function which adapts to the natural scale of the contour at each point. Then, curvature is reduced to a short feature vector by using Principal Component Analysis. The landmark calculation method has been successfully tested in a medium scale real environment using a Pioneer robot with Polaroid sonar sensors.     

Advancing Radio Testing Methodology via Formal Notations

Mandatory verification of the correct operation of equipment in public environments will increase the complexity of test equipment due to the high number of new vendors in the foreseen scenarios. Protocol and radio conformance tests are usually thought to be two separated fields, which makes that the test system design process is different for both cases. However, the only lack of radio test cases is the formalization of tests using a formal test notation. In this paper, it is shown how the design process can be merged for both protocol and radio test systems by modelling radio tests in TTCN. In this case, the same architecture and development tools can be used in the whole testing process, and a reduction of costs and time can be achieved. Abstraction of the instrumentation equipment and standardization of a control interface are required.     

Wireless Underwater Communications

The depths of the oceans have a high potential for future industrial development and applications. Robotic autonomous systems will greatly depend on a reliable communications channel with operators and equipment either performing joint operations or on the surface. However, communications must face harsh conditions that hinder the performance. Neither electromagnetic nor optical technologies are suitable for communication because of their short range in this medium. Due to this, acoustic equipment is envisaged as the most appropriate technology, even though it suffers several negative effects such as strong attenuation at high (ultrasonic) frequencies, Doppler shifts and a time-varying multipath. In this paper, we describe the characteristics of the acoustic underwater channel and how it impacts the mechanisms at the link and network layers.     

Framework for Analysis of Power System Operation in Smart Cities

For highly populated Asian countries like Pakistan, the smart cities may play numerous positive roles resulting in efficient utilization of available infrastructure. This can be achieved by transforming existing infrastructures into smart ones. To start with such transformation, the main emphasis would be given to energy. For this purpose, the model of a framework capable of analyzing emerging trends in upcoming power system to make it more reliable. This research work focused on the significance of implementing advanced systems like smart grids. Therefore the proposed framework addresses the provision of an integrated simulation tool for in-depth study of system to determine susceptibility of failure, critical situations and restoration scheme by adding renewable energy resources. The planned framework will be used to analyze the impact of emerging trends in power grid operation of intelligent grid which is more commonly known as the smart grid. The framework may also be used to develop contingency plans to optimize the generation, transmission and distribution schemes thus providing the more flexible solutions. The proposed framework may also be used to enhance the security features of supervisory control and data acquisition system which is essential part of such smart transformations.     

Radon exposure in uranium mining industry vs. exposure in tourist caves

There is a fairly general consensus among health physicists and radiation professionals that exposure to radon progeny is the largest and most variable contribution to the population's exposure to natural sources of radiation. However, this exposure is the subject of continuing debate concerning the validity of risk assessment and recommendations on how to act in radon-prone areas. The purpose of this contribution is to situate the radon issue in Spain in two very different settings. The first is a uranium mining industry located in Saelices el Chico (Salamanca), which is under strict control of the Spanish Nuclear Safety Council (CSN). We have measured radon concentrations in different workplaces in this mine over a five-year period. The second setting comprises four tourist caves, three of which are located in the province of Cantabria and the fourth on the Canary Island of Lanzarote. These caves are not subject to any administrative control of radiation exposure. Measured air 222Rn concentrations were used to estimate annual effective doses due to radon inhalation in the two settings, and dose values were found to be from 2 to 10 times lower in the uranium mine than in the tourist caves. These results were analysed in the context of the new European Basic Safety Standards Directive (EU-BSS, 1996).     

Population dose in the vicinity of old Spanish uranium mines

Regional surveys were conducted to determine exposure to natural sources of radiation for people in the vicinity of old Spanish uranium mines. The surveys evaluated indoor radon concentrations and outdoor and indoor external gamma dose rates. Indoor radon concentrations were measured in 222 dwellings by means of nuclear track-etched detectors. The terrestrial gamma ray dose rate was measured outdoors and indoors at a total of 256 points and 115 points, respectively. Estimates mean annual effective doses for the six areas studied ranged from 3.2 to 5.1 mSv per year, which is between 1.2 and 2 times higher than the average national value.     

Critical Analysis of Localization and Time Synchronization Algorithms in Underwater Wireless Sensor Networks: Issues and Challenges

Wireless Personal Communications - In underwater wireless sensor networks (UWSNs), localization and time synchronization plays a critical role among many underwater applications. However without...