センサーネットワークとデータ通信の国際ジャーナル

The analysis of mobile phone speech recordings can play an important role in criminal trials. However it may be erroneously assumed that all mobile phone technologies, such as the Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA), are similar in their potential impact on the speech signal. In fact these technologies differ significantly in their design and internal operation. This study investigates the impact of an important aspect of these networks, namely Frame Loss (FL), on the results of a forensic voice comparison undertaken using a Bayesian likelihood ratio framework. For both networks, whenever a frame is lost or irrecoverably corrupted, it is synthetically replaced at the receiving end using a history of past good speech frames. Sophisticated mechanisms have been put in place to minimize any resulting artefacts in the recovered speech. In terms of accuracy, FL with GSMcoded speech is shown to worsen same-speaker comparisons, but improve different-speaker comparisons. In terms of precision, FL negatively impacts both sets of comparisons. With CDMA-coded speech, FL is shown to negatively impact the accuracy of both same- and different-speaker comparisons. However, surprisingly, FL is shown to improve the precision of both sets.

Divisible Load Theory (DLT) is a very efficient tool to schedule arbitrarily divisible load on a set of network processors. Most of previous work using DLT assumes that the processors' speeds and links' speeds are time- invariant. Closed form solution was derived for the system under the assumption that the processors' speed s and the links' speeds stay the same during the task execution time. This assumption is not practical as most of distributed systems used today have an autonomous control. In this paper we consider a distributed system (Grid) where the availability of the processors varies and follows a certain distribution function. A closed form solution for the finish time is derived. The solution considers all system parameters such as links' speed, number of processors, number of resources (sites), and availability of the processors and how much of power they can contribute. The result is shown and it measures the variation of execution time against the availability of processors.

A method based on laser diffraction was reported to improve the defect recognition accuracy of surface micro defect detection of tapered rollers. According to Fraunhofer diffraction theory, the fluctuations of the width of a tiny slit can be transformed to obvious changes of diffraction fringes, which can be employed to measure the micro surface defect of tapered rollers. These optical diffraction fringes were captured by a CCD camera, and subsequently were transmitted to a developed image processing system. The system includes image de-noising based on anisotropic diffusion, automatic extraction of fringe center lines by the derivative-sign binary image method, and analysis of the extracted fringe center lines for automatic defect detection. The experimental results demonstrated that the proposed method could magnify defect effect and therefore improve the accuracy of defect detection, making it attractive for industrial applications on tapered roller defect detection.

Thermoluminescence dosimeters (TLDs) are widely used, serving the needs of various radiation applications. In recent times optical fibers have been introduced as alternatives to more conventional phosphor-based TLD systems, with many efforts being carried out to improve their thermoluminescence (TL) yield. While there have been extensive studies of many of the various TLD characteristics of optical fibers, including TL response, linearity, reproducibility, repeatability, sensitivity and fading, far more limited studies have concerned dependence on the type of TL activator used in optical fibers, promoting the TL mechanism. Present study focuses on TLD glow curves analysis for five different doped optical fibers that have been subjected to photon and electron irradiation. Trap parameters such as activation energy and frequency factors have been obtained from second order kinetics analysis, based on computerized glow curve deconvolution. An interesting observation is that co-doped fibers typically leads to enhanced TL characteristics, pointing to a need for optimization of the choice and levels in use of co-dopants.

The lifetime of a sensor network depends on the judicious utilization of the resource-constrained nodes. Practices like data aggregation, sleep scheduling play a major role in conserving the node’s energy. But in most cases, we observe a disparity in energy consumption rates among different sensors. This disparity results from higher utilization of a small set of deployed sensors in the field leaving these sensors drained out of power. To overcome this problem, it is often required to deploy redundant sensors to act as replacements for a faulty node. Secondly, the sensor network technology, being an application oriented technology, experiences variance in network parameters from application to application because of the various dynamics in nature. It is not often viable to go for a theoretically determined sensor distribution technique. Thus, it is often required to place sensors by studying the geographical constraints. These have proven to be highly valuable in designing energy efficient routing schemes anThe lifetime of a sensor network depends on the judicious utilization of the resource-constrained nodes. Practices like data aggregation, sleep scheduling play a major role in conserving the node’s energy. But in most cases, we observe a disparity in energy consumption rates among different sensors. This disparity results from higher utilization of a small set of deployed sensors in the field leaving these sensors drained out of power. To overcome this problem, it is often required to deploy redundant sensors to act as replacements for a faulty node. Secondly, the sensor network technology, being an application oriented technology, experiences variance in network parameters from application to application because of the various dynamics in nature. It is not often viable to go for a theoretically determined sensor distribution technique. Thus, it is often required to place sensors by studying the geographical constraints. These have proven to be highly valuable in designing energy efficient routing schemes and network topologies for sensor networks. In this paper we propose a scheme to decide how the distribution of available redundant sensor nodes should take place around sensor nodes. The scheme gives the flexibility to determine sensor positions based on application and geographical constraints. We propose to use the probability estimates of the utilization of a sensor in a given deployment to achieve desired network lifetimes. We also show how in some cases we can leverage the relative position from source(s) and sink be used for the same.d network topologies for sensor networks. In this paper we propose a scheme to decide how the distribution of available redundant sensor nodes should take place around sensor nodes. The scheme gives the flexibility to determine sensor positions based on application and geographical constraints. We propose to use the probability estimates of the utilization of a sensor in a given deployment to achieve desired network lifetimes. We also show how in some cases we can leverage the relative position from source(s) and sink be used for the same.

Airplane design involves complex system integration and must comply with a set of requirements, which are set up by certification authorities, customers, manufacturing, and that coming from market studies. From the traditional perspective of an airline, an interesting airplane is one that is capable of generating the highest revenue with minimum cost-a maximum profit airplane. In later years, however, the airline industry is swiftly broadening its consideration of what constitutes a nice-to-buy airplane. Not only economics but also environmental considerations are taking part in fleet-planning considerations-a trend spurred by environmental-aware passengers. In a move to comply with this trend, airplane conceptual design has incorporated methodologies for preliminary assessment of airplane noise and emissions. As more approaches become available to address these issues, the choice between the most suitable methodologies becomes tougher. The present work analyzes some methodologies in order to select a subset of them. The objective is the evaluation of such methodologies and their integration into a framework to airliner conceptual design. In order to test the design methodologies and the optimization techniques, the authors selected two test airplane categories: first, a long range, transcontinental jet; and a mid-size regional jet. Design tasks based on optimization with noise footprint, direct operational cost, and emission profile or a combination of them as objectives are presented and analyzed.

Wireless sensor networks (WSNs) are utilized in various applications and are providing the backbone for the new pervasive Internet, or Internet of Things. The development of a reliable and robust large-scale WSN system requires that the design concepts are checked and optimized before they are implemented and tested for a specific hardware platform. Simulation provides a cost effective and feasible method of examining the correctness and scalability of the system before deployment. In this work, we study the performance of Pymote, a high level Python library for event based simulation of distributed algorithms in wireless ad-hoc networks. We extended the Pymote framework allowing it to simulate packet level performance. The extension includes radio propagation, energy consumption, mobility and other models. The extended framework also provides interactive plotting, data collection and logging facilities for improved analysis and evaluation of the simulated system.

ECG signal vary from person to person, making it difficult to be imitated and duplicated. Biometric identification based on ECG is therefore a useful application based on this feature. Synchronization of chaotic systems provides a rich mechanism which is noise-like and virtually impossible to guess or predict. This study intends to combine our previously proposed information encryption/decryption system with chaotic synchronization circuits to create private key masking. To implement the proposed secure communication system, a pair of Lorenz-based synchronized circuits is developed by using operational amplifiers, resistors, capacitors and multipliers. The verification presented involves numerical simulation and hardware implementation to demonstrate feasibility of the proposed method. High quality randomness in ECG signals results in a widely expanded key space, making it an ideal key generator for personalized data encryption. The experiments demonstrate the use of this approach in encrypting texts and images via secure communications.

For the scenarios of indoors localization and tracking, the solutions generally need complex infrastructure because they would require either a grid of antennas, each having a well-known position (proximity based approach), or a sophisticated algorithm that uses scene fingerprint to estimate the location or the zone of an object by matching the online measurement with the closest offline measurement. Those techniques may not be available in unknown zones, which will make it difficult to locate a lost node. In this paper, with no additional hardware costs, we propose a new RSSIbased approach in order to find a lost node using a known node. By rotating the known node at the same spot we can collect different RSSI for different polar angles. Two pairs of angles with the strongest RSSI will indicate the main lobes of the radiation pattern, namely, zone of the unknown node. Experimental results illustrate a very close estimation of the unknown node zone, reducing up to 84% of the zone uncertainty.