A Novel Handwritten Letter Recognizer Using Enhanced Evolutionary Neural Network

Science.gov (United States)

Mahmoudi, Fariborz; Mirzashaeri, Mohsen; Shahamatnia, Ehsan; Faridnia, Saed

This paper introduces a novel design for handwritten letter recognition by employing a hybrid back-propagation neural network with an enhanced evolutionary algorithm. Feeding the neural network consists of a new approach which is invariant to translation, rotation, and scaling of input letters. Evolutionary algorithm is used for the global search of the search space and the back-propagation algorithm is used for the local search. The results have been computed by implementing this approach for recognizing 26 English capital letters in the handwritings of different people. The computational results show that the neural network reaches very satisfying results with relatively scarce input data and a promising performance improvement in convergence of the hybrid evolutionary back-propagation algorithms is exhibited.

New approach to wireless data communication in a propagation environment

Science.gov (United States)

Hunek, Wojciech P.; Majewski, Paweł

2017-10-01

This paper presents a new idea of perfect signal reconstruction in multivariable wireless communications systems including a different number of transmitting and receiving antennas. The proposed approach is based on the polynomial matrix S-inverse associated with Smith factorization. Crucially, the above mentioned inverse implements the so-called degrees of freedom. It has been confirmed by simulation study that the degrees of freedom allow to minimalize the negative impact of the propagation environment in terms of increasing the robustness of whole signal reconstruction process. Now, the parasitic drawbacks in form of dynamic ISI and ICI effects can be eliminated in framework described by polynomial calculus. Therefore, the new method guarantees not only reducing the financial impact but, more importantly, provides potentially the lower consumption energy systems than other classical ones. In order to show the potential of new approach, the simulation studies were performed by author's simulator based on well-known OFDM technique.

Path Loss Analysis of WSN Wave Propagation in Vegetation

International Nuclear Information System (INIS)

Sabri, Naseer; Aljunid, S A; Ahmad, R B; Malek, M F; Salim, M S; Kamaruddin, R

2013-01-01

Deployment of a successful wireless sensor network requires precise prediction models that provide a reliable communication links of wireless nodes. Prediction models fused with foliage models provide sensible parameters of wireless nodes separation distance, antenna height, and power transmission which affect the reliability and communication coverage of a network. This paper review the line of sight and the two ray propagation models combined with the most known foliage models that cover the propagation of wireless communications in vegetative environments, using IEEE 802.15.4 standard. Simulation of models is presented and the impacts of the communication parameters, environment and vegetation have been reported.

Evaluation of coherence interference in optical wireless communication through multiscattering channels.

Science.gov (United States)

Kedar, Debbie; Arnon, Shlomi

2006-05-10

Optical wireless communication has been the subject of much research in recent years because of the increasing interest in laser satellite-ground links and urban optical wireless communication. The major sources of performance degradation have been identified as the spatial, angular, and temporal spread of the propagating beam when the propagation channel is multiscattering, resulting in reduced power reception and intersignal interference, as well as turbulence-induced scintillations and noise due to receiver circuitry and background illumination. However, coherence effects due to multipath interference caused by a scattering propagation channel do not appear to have been treated in detail in the scientific literature. We attempt a theoretical analysis of coherence interference in optical wireless communication through scattering channels and try to quantify the resultant performance degradation for different media. We conclude that coherence interference is discernible in optical wireless communication through scattering channels and is highly dependent on the microscopic nature of the propagation medium.

Remote Monitoring of the Heart Condition of Athletes by Measuring the Cardiac Action Potential Propagation Time Using a Wireless Sensor Network

Directory of Open Access Journals (Sweden)

Amang Sudarsono

2016-04-01

Full Text Available Highly performing athletes are susceptible to cardiac damage of several kinds which may be irreversible. The monitoring of heart rate and ECG waveforms from such subjects by wireless sensor networks has been reported in health and sports care documents. However, a more decisive parameter for instant to instant changes would be the time of Cardiac Action Potential Propagation. This time, which can be between 15-20 ms would shoot suddenly in acute stress in highly performing athletes for short durations. Repeated incidents of such rising values will tend to cause irreversible damage to the heart. We developed the technique of measuring this time and reporting it through a wireless sensor network to monitoring station.

A Trace-Driven Analysis of Wireless Group Communication Mechanisms

Directory of Open Access Journals (Sweden)

Surendar Chandra

2012-08-01

Full Text Available Wireless access is increasingly ubiquitous while mobile devices that use them are resource rich. These trends allow wireless users to collaborate with each other. We investigate various group communication paradigms that underly collaboration applications. We synthesize durations when members collaborate using wireless device availability traces. Wireless users operate from a variety of locations. Hence, we analyzed the behavior of wireless users in universities, corporations, conference venues, and city-wide hotspots. We show that the availability durations are longer in corporations followed by university and then in hotspots. The number of simultaneously available wireless users is small in all the scenarios. The session lengths are becoming smaller while the durations between sessions are becoming larger. We observed user churn in all the scenarios. We show that synchronous mechanisms require less effort to maintain update synchronicity among the group members. However, distributed mechanisms require a large number of replicas in order to propagate updates among the users. For asynchronous mechanisms, we show that pull-based mechanisms naturally randomize the times when updates are propagated and thus achieve better performance than push based mechanisms.We develop an adaptive approach that customizes the update frequency using the last session duration and show that this mechanism exhibits good performance when the required update frequency intervals are large. We also show that for a given number of gossips, it is preferable to propagate updates to all available nodes rather than increasing the frequency while correspondingly reducing the number of nodes to propagate updates.We develop a middleware to illustrate the practicality of our approach.

Wireless sensors remotely powered by RF energy

NARCIS (Netherlands)

Visser, Hubregt J.; Vullers, Ruud J.M.

2012-01-01

Wireless, radiated far-field energy is being employed for charging a battery. This battery, while being recharged, is used to power a commercially of the shelf, low power, wireless sensor node. Propagation conditions in common office and house configurations are investigated experimentally. These

Self-Propagating Worms in Wireless Sensor Networks

DEFF Research Database (Denmark)

Giannetsos, Thanassis; Dimitriou, Tassos; Prasad, Neeli R.

2009-01-01

Malicious code is defined as software designed to execute attacks on software systems. This work demonstrates the possibility of executing malware on wireless sensor nodes that are based on the von Neumann architecture. This is achieved by exploiting a buffer overflow vulnerability to smash the c...

Wireless optical telecommunications

CERN Document Server

Bouchet, Olivier

2013-01-01

Wireless optical communication refers to communication based on the unguided propagation of optical waves. The past 30 years have seen significant improvements in this technique - a wireless communication solution for the current millennium - that offers an alternative to radio systems; a technique that could gain attractiveness due to recent concerns regarding the potential effects of radiofrequency waves on human health.The aim of this book is to look at the free space optics that are already used for the exchange of current information; its many benefits, such as incorporating chan

Simulation of Wireless Digital Communication Systems

Directory of Open Access Journals (Sweden)

A. Mohammed

2004-12-01

Full Text Available Due to the explosive demands for high speed wireless services, suchas wireless Internet, email and cellular video conferencing, digitalwireless communications has become one of the most exciting researchtopics in electrical and electronic engineering field. The never-endingdemand for such personal and multimedia services, however, demandstechnologies operating at higher data rates and broader bandwidths. Inaddition, the complexity of wireless communication and signalprocessing systems has grown considerably during the past decade.Therefore, powerful computer­aided techniques are required for theprocess of modeling, designing, analyzing and evaluating theperformance of digital wireless communication systems. In this paper wediscuss the basic propagation mechanisms affecting the performance ofwireless communication systems, and present a simple, powerful andefficient way to simulate digital wireless communication systems usingMatlab. The simulated results are compared with the theoreticalanalysis to validate the simulator. The simulator is useful inevaluating the performance of wireless multimedia services and theassociated signal processing structures and algorithms for current andnext generation wireless mobile communication systems.

Introductory survey for wireless infrared communications

Directory of Open Access Journals (Sweden)

Munsif Ali Jatoi

2014-08-01

Full Text Available Wireless infrared communications can be defined as the propagation of light waves in free space using infrared radiation whose range is 400–700 nm. This range corresponds to frequencies of hundreds of terahertz, which is high for higher data rate applications. Wireless infrared is applied for higher data rates applications such as wireless computing, wireless video and wireless multimedia communication applications. Introduced by Gfeller, this field has grown with different link configurations, improved transmitter efficiency, increased receiver responsivity and various multiple access techniques for improved quality. Errors are caused because of background light, which causes degradation overall system performance. Error correction techniques are used to remove the errors caused during transmission. This study provides a brief account on field theory used for error correction in wireless infrared systems. The results are produced in terms of bit error rate and signal-to-noise ratio for various bit lengths to show the ability of encoding and decoding algorithms.

Optical wireless connected objects for healthcare.

Science.gov (United States)

Toumieux, Pascal; Chevalier, Ludovic; Sahuguède, Stéphanie; Julien-Vergonjanne, Anne

2015-10-01

In this Letter the authors explore the communication capabilities of optical wireless technology for a wearable device dedicated to healthcare application. In an indoor environment sensible to electromagnetic perturbations such as a hospital, the use of optical wireless links can permit reducing the amount of radio frequencies in the patient environment. Moreover, this technology presents the advantage to be secure, low-cost and easy to deploy. On the basis of commercially available components, a custom-made wearable device is presented, which allows optical wireless transmission of accelerometer data in the context of physical activity supervision of post-stroke patients in hospital. Considering patient mobility, the experimental performance is established in terms of packet loss as a function of the number of receivers fixed to the ceiling. The results permit to conclude that optical wireless links can be used to perform such mobile remote monitoring applications. Moreover, based on the measurements obtained with one receiver, it is possible to theoretically determine the performance according to the number of receivers to be deployed.

Distributed Software-Attestation Defense against Sensor Worm Propagation

Directory of Open Access Journals (Sweden)

Jun-Won Ho

2015-01-01

Full Text Available Wireless sensor networks are vulnerable to sensor worm attacks in which the attacker compromises a few nodes and makes these compromised nodes initiate worm spread over the network, targeting the worm infection of the whole nodes in the network. Several defense mechanisms have been proposed to prevent worm propagation in wireless sensor networks. Although these proposed schemes use software diversity technique for worm propagation prevention under the belief that different software versions do not have common vulnerability, they have fundamental drawback in which it is difficult to realize the aforementioned belief in sensor motes. To resolve this problem, we propose on-demand software-attestation based scheme to defend against worm propagation in sensor network. The main idea of our proposed scheme is to perform software attestations against sensor nodes in on-demand manner and detect the infected nodes by worm, resulting in worm propagation block in the network. Through analysis, we show that our proposed scheme defends against worm propagation in efficient and robust manner. Through simulation, we demonstrate that our proposed scheme stops worm propagation at the reasonable overhead while preventing a majority of sensor nodes from being infected by worm.

Enabling Wireless Avionics Intra-Communications

Science.gov (United States)

Torres, Omar; Nguyen, Truong; Mackenzie, Anne

2016-01-01

The Electromagnetics and Sensors Branch of NASA Langley Research Center (LaRC) is investigating the potential of an all-wireless aircraft as part of the ECON (Efficient Reconfigurable Cockpit Design and Fleet Operations using Software Intensive, Networked and Wireless Enabled Architecture) seedling proposal, which is funded by the Convergent Aeronautics Solutions (CAS) project, Transformative Aeronautics Concepts (TAC) program, and NASA Aeronautics Research Institute (NARI). The project consists of a brief effort carried out by a small team in the Electromagnetic Environment Effects (E3) laboratory with the intention of exposing some of the challenges faced by a wireless communication system inside the reflective cavity of an aircraft and to explore potential solutions that take advantage of that environment for constructive gain. The research effort was named EWAIC for "Enabling Wireless Aircraft Intra-communications." The E3 laboratory is a research facility that includes three electromagnetic reverberation chambers and equipment that allow testing and generation of test data for the investigation of wireless systems in reflective environments. Using these chambers, the EWAIC team developed a set of tests and setups that allow the intentional variation of intensity of a multipath field to reproduce the environment of the various bays and cabins of large transport aircraft. This setup, in essence, simulates an aircraft environment that allows the investigation and testing of wireless communication protocols that can effectively be used as a tool to mitigate some of the risks inherent to an aircraft wireless system for critical functions. In addition, the EWAIC team initiated the development of a computational modeling tool to illustrate the propagation of EM waves inside the reflective cabins and bays of aircraft and to obtain quantifiable information regarding the degradation of signals in aircraft subassemblies. The nose landing gear of a UAV CAD model was used

Wireless communication for hearing aid system

DEFF Research Database (Denmark)

Nour, Baqer

This thesis focuses on the wireless coupling between hearing aids close to a human head. Hearing aids constitute devices withadvanced technology and the wireless communication enables the introduction of a range of completely new functionalities. Such devices are small and the available power...... the ear-to-ear wireless communication channel by understanding the mechanisms that control the propagations of the signals and the losses. The second objective isto investigate the properties of magneto-dielectric materials and their potential in antenna miniaturization. There are three approaches...... to study the ear-to-ear wireless communication link; a theoretical approach models the human head asa sphere that has the electrical properties of the head, a numerical approach implements a more realistic geometry of the head, and an experimental approach measures directly the coupling between...

Wireless energy transfer: Dielectric lens antennas for beam shaping in wireless power-transfer applications

Science.gov (United States)

Gonçalves, Ricardo; Carvalho, Nuno B.; Pinho, Pedro

2017-02-01

In the current contest of wireless systems, the last frontier remains the cut of the power cord. In that sense, the interest over wireless energy transfer technologies in the past years has grown exponentially. However, there are still many challenges to be overcome in order to enable wireless energy transfer full potential. One of the focus in the development of such systems is the design of very-high-gain, highly efficient, antennas that can compensate for the propagation loss of radio signals over the air. In this paper, we explore the design and manufacturing process of dielectric lenses, fabricated using a professional-grade desktop 3D printer. Lens antennas are used in order to increase beam efficiency and therefore maximize the efficiency of a wireless power-transfer system operating at microwave frequencies in the Ku band. Measurements of two fabricated prototypes showcase a large directivity, as predicted with simulations. xml:lang="fr"

Investigation of Prediction Accuracy, Sensitivity, and Parameter Stability of Large-Scale Propagation Path Loss Models for 5G Wireless Communications

DEFF Research Database (Denmark)

Sun, Shu; Rappaport, Theodore S.; Thomas, Timothy

2016-01-01

This paper compares three candidate large-scale propagation path loss models for use over the entire microwave and millimeter-wave (mmWave) radio spectrum: the alpha–beta–gamma (ABG) model, the close-in (CI) free-space reference distance model, and the CI model with a frequency-weighted path loss...... exponent (CIF). Each of these models has been recently studied for use in standards bodies such as 3rd Generation Partnership Project (3GPP) and for use in the design of fifth generation wireless systems in urban macrocell, urban microcell, and indoor office and shopping mall scenarios. Here, we compare...

Frameless ALOHA Protocol for Wireless Networks

DEFF Research Database (Denmark)

Stefanovic, Cedomir; Popovski, Petar; Vukobratovic, Dejan

2012-01-01

We propose a novel distributed random access scheme for wireless networks based on slotted ALOHA, motivated by the analogies between successive interference cancellation and iterative belief-propagation decoding on erasure channels. The proposed scheme assumes that each user independently accesse...

Reconfigurable Radio Access Unit for DWDM to W-Band Wireless Conversion

DEFF Research Database (Denmark)

Chorchos, Łukasz; Rommel, Simon; Turkiewicz, Jarosław P.

2017-01-01

In this letter a reconfigurable Remote Access Unit (RAU) is proposed and demonstrated, interfacing dense wavelength division multiplexed (DWDM) optical and W-band wireless links. The RAU is composed of a tunable local oscillator, a narrow optical filter and a control unit, making it reconfigurable...

DEVELOPMENT OF WIRELESS TECHNIQUES IN DATA AND POWER TRANSMISSION APPLICATION FOR PARTICLE-PHYSICS DETECTORS

CERN Document Server

Brenner, R; Dehos, C; De Lurgio, P; Djurcic, Z; Drake, G; Gonzales Gimenez, JL; Gustafsson, L; Kim, DW; Locci, E; Pfeiffer, U; Röhrich, D; Rydberg, D; Schöning, A; Siligaris, A; Soltveit, HK; Ullaland, K; Vincent, P; Vasquez, PR; Wiedner, D; Yang, S

2017-01-01

In the WADAPT project described in this Letter of Intent, we propose to develop wireless techniques for data and power transmission in particle-physics detectors. Wireless techniques have developed extremely fast over the last decade and are now mature for being considered as a promising alternative to cables and optical links that would revolutionize the detector design. The WADAPT consortium has been formed to identify the specific needs of different projects that might benefit from wireless techniques with the objective of providing a common platform for research and development in order to optimize effectiveness and cost. The proposed R&D will aim at designing and testing wireless demonstrators for large instrumentation systems.

Experimental Investigation of Subject-Specific On-Body Radio Propagation Channels for Body-Centric Wireless Communications

Directory of Open Access Journals (Sweden)

Mohammad Monirujjaman Khan

2014-01-01

Full Text Available In this paper, subject-specific narrowband (2.45 GHz and ultra-wideband (3–10.6 GHz on-body radio propagation studies in wireless body area networks (WBANs were performed by characterizing the path loss for eight different human subjects of different shapes and sizes. The body shapes and sizes of the test subjects used in this study are characterised as thin, medium build, fatty, shorter, average height and taller. Experimental investigation was made in an indoor environment using a pair of printed monopoles (for the narrowband case and a pair of tapered slot antennas (for the ultra-wideband (UWB case. Results demonstrated that, due to the different sizes, heights and shapes of the test subjects, the path loss exponent value varies up to maximum of 0.85 for the narrowband on-body case, whereas a maximum variation of the path loss exponent value of 1.15 is noticed for the UWB case. In addition, the subject-specific behaviour of the on-body radio propagation channels was compared between narrowband and UWB systems, and it was deduced that the on-body radio channels are subject-specific for both narrowband and UWB system cases, when the same antennas (same characteristics are used. The effect of the human body shape and size variations on the eight different on-body radio channels is also studied for both the narrowband and UWB cases.

Physics-based statistical model and simulation method of RF propagation in urban environments

Science.gov (United States)

Pao, Hsueh-Yuan; Dvorak, Steven L.

2010-09-14

A physics-based statistical model and simulation/modeling method and system of electromagnetic wave propagation (wireless communication) in urban environments. In particular, the model is a computationally efficient close-formed parametric model of RF propagation in an urban environment which is extracted from a physics-based statistical wireless channel simulation method and system. The simulation divides the complex urban environment into a network of interconnected urban canyon waveguides which can be analyzed individually; calculates spectral coefficients of modal fields in the waveguides excited by the propagation using a database of statistical impedance boundary conditions which incorporates the complexity of building walls in the propagation model; determines statistical parameters of the calculated modal fields; and determines a parametric propagation model based on the statistical parameters of the calculated modal fields from which predictions of communications capability may be made.

Auction design for the wireless spectrum market

CERN Document Server

Lin, Peng; Zhang, Qian

2014-01-01

This Brief introduces the wireless spectrum market and discusses the current research for spectrum auctions. It covers the unique properties of spectrum auction, such as interference relationship, reusability, divisibility, composite effect and marginal effect, while also proposing how to build economic incentives into the network architecture and protocols in order to optimize the efficiency of wireless systems.Three scenarios for designing new auctions are demonstrated. First, a truthful double auction scheme for spectrum trading considering both the heterogeneous propagation properties of c

Low-power wireless micromanometer system for acute and chronic bladder-pressure monitoring.

Science.gov (United States)

Majerus, Steve J A; Fletter, Paul C; Damaser, Margot S; Garverick, Steven L

2011-03-01

This letter describes the design, fabrication, and testing of a wireless bladder-pressure-sensing system for chronic, point-of-care applications, such as urodynamics or closed-loop neuromodulation. The system consists of a miniature implantable device and an external RF receiver and wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream. The implant consists of a custom application-specific integrated circuit (ASIC), a pressure transducer, a rechargeable battery, and wireless telemetry and recharging antennas. The ASIC includes instrumentation, wireless transmission, and power-management circuitry, and on an average draws less than 9 μA from the 3.6-V battery. The battery charge can be wirelessly replenished with daily 6-h recharge periods that can occur during the periods of sleep. Acute in vivo evaluation of the pressure-sensing system in canine models has demonstrated that the system can accurately capture lumen pressure from a submucosal implant location.

Model Development For Wireless Propagation In Forested Environments

Science.gov (United States)

2015-09-01

vegetation elements can be compared to the reduction of the propagated radio signals in buildings and urban areas. The diversity of operational...contexts for radio wave propagation through foliage is infinite, ranging from tall, dense canopy forests to open, low, sparse canopy woodlands [3], as...nearly flat and mainly consists of dry soil and sand that is covered by grass in some parts. The experimental site is mixed vegetation woodland with an

Radio propagation measurement and channel modelling

CERN Document Server

Salous, Sana

2013-01-01

While there are numerous books describing modern wireless communication systems that contain overviews of radio propagation and radio channel modelling, there are none that contain detailed information on the design, implementation and calibration of radio channel measurement equipment, the planning of experiments and the in depth analysis of measured data. The book would begin with an explanation of the fundamentals of radio wave propagation and progress through a series of topics, including the measurement of radio channel characteristics, radio channel sounders, measurement strategies

OPTICAL WIRELESS COMMUNICATION SYSTEM

Directory of Open Access Journals (Sweden)

JOSHUA L.Y. CHIENG

2016-02-01

Full Text Available The growing demand of bandwidth in this modern internet age has been testing the existing telecommunication infrastructures around the world. With broadband speeds moving towards the region of Gbps and Tbps, many researches have begun on the development of using optical wireless technology as feasible and future methods to the current wireless technology. Unlike the existing radio frequency wireless applications, optical wireless uses electromagnetic spectrums that are unlicensed and free. With that, this project aim to understand and gain better understanding of optical wireless communication system by building an experimental and simulated model. The quality of service and system performance will be investigated and reviewed. This project employs laser diode as the propagation medium and successfully transferred audio signals as far as 15 meters. On its quality of service, results of the project model reveal that the bit error rate increases, signal-to-noise ratio and quality factor decreases as the link distance between the transmitter and receiver increases. OptiSystem was used to build the simulated model and MATLAB was used to assist signal-to-noise ratio calculations. By comparing the simulated and experimental receiver’s power output, the experimental model’s efficiency is at 66.3%. Other than the system’s performance, challenges and factors affecting the system have been investigated and discussed. Such challenges include beam divergence, misalignment and particle absorption.

Experimental and simulation analysis of the W-band SC-FDMA hybrid optical-wireless transmission

DEFF Research Database (Denmark)

Dogadaev, Anton Konstantinovich; Pang, Xiaodan; Deng, Lei

2014-01-01

We report on the experimental demonstration of the W-band hybrid optical-wireless SC-FDMA with 1.49 Gbit/s transmission over up to 2.3 m of air propagation. Provided simulation performance analysis proves a potential to reach 12.1 Gbit/s.......We report on the experimental demonstration of the W-band hybrid optical-wireless SC-FDMA with 1.49 Gbit/s transmission over up to 2.3 m of air propagation. Provided simulation performance analysis proves a potential to reach 12.1 Gbit/s....

Low complexity source and channel coding for mm-wave hybrid fiber-wireless links

DEFF Research Database (Denmark)

Lebedev, Alexander; Vegas Olmos, Juan José; Pang, Xiaodan

2014-01-01

We report on the performance of channel and source coding applied for an experimentally realized hybrid fiber-wireless W-band link. Error control coding performance is presented for a wireless propagation distance of 3 m and 20 km fiber transmission. We report on peak signal-to-noise ratio perfor...

Radio Wave Propagation Scene Partitioning for High-Speed Rails

Directory of Open Access Journals (Sweden)

Bo Ai

2012-01-01

Full Text Available Radio wave propagation scene partitioning is necessary for wireless channel modeling. As far as we know, there are no standards of scene partitioning for high-speed rail (HSR scenarios, and therefore we propose the radio wave propagation scene partitioning scheme for HSR scenarios in this paper. Based on our measurements along the Wuhan-Guangzhou HSR, Zhengzhou-Xian passenger-dedicated line, Shijiazhuang-Taiyuan passenger-dedicated line, and Beijing-Tianjin intercity line in China, whose operation speeds are above 300 km/h, and based on the investigations on Beijing South Railway Station, Zhengzhou Railway Station, Wuhan Railway Station, Changsha Railway Station, Xian North Railway Station, Shijiazhuang North Railway Station, Taiyuan Railway Station, and Tianjin Railway Station, we obtain an overview of HSR propagation channels and record many valuable measurement data for HSR scenarios. On the basis of these measurements and investigations, we partitioned the HSR scene into twelve scenarios. Further work on theoretical analysis based on radio wave propagation mechanisms, such as reflection and diffraction, may lead us to develop the standard of radio wave propagation scene partitioning for HSR. Our work can also be used as a basis for the wireless channel modeling and the selection of some key techniques for HSR systems.

Letter Names, Letter Sounds and Phonological Awareness: An Examination of Kindergarten Children across Letters and of Letters across Children

Science.gov (United States)

Evans, Mary Ann; Bell, Michelle; Shaw, Deborah; Moretti, Shelley; Page, Jodi

2006-01-01

In this study 149 kindergarten children were assessed for knowledge of letter names and letter sounds, phonological awareness, and cognitive abilities. Through this it examined child and letter characteristics influencing the acquisition of alphabetic knowledge in a naturalistic context, the relationship between letter-sound knowledge and…

Wireless transmission of power

International Nuclear Information System (INIS)

Grotz, T.

1991-01-01

This paper reports that it has been proven by researchers that electrical energy can be propagated around the world between the surface of the Earth and the ionosphere at extremely low frequencies in what is known as the Schumann Cavity. Experiments to data have shown that electromagnetic waves with frequencies in the range of 8 Hz, the fundamental Schumann Resonance frequency, propagate with litter attenuation around the planet within the Schumann Cavity. It is the intent of this research to determine if the Schumann Cavity can be resonated, if the power that is delivered to the cavity propagated with very low losses, and if power can be extracted at other locations within the cavity. Experimental data collected and calculations made in recent years support the hypothesis that wireless power transmission is a viable and practical alternative to the present systems of power transmission

Experimental Evaluation of Wireless Communication Channels under Radiation Environment

International Nuclear Information System (INIS)

Wang, Quan; Bari, Ataul; Deng, Changjian; Li, Liquan

2014-01-01

Deployment of wireless systems in nuclear power plants has attracted a lot of attention recently. However, before wireless systems can be installed in a nuclear power plant, it is necessary to evaluate the effect of radiation environment on electromagnetic wave which is the communication media for all radio wave based wireless systems. This is particular important if the wireless systems are expected to work in a harsh and radioactive environment following a severe accident. This paper presents some results of an experiment for evaluating the effect of radiation on electromagnetic wave. The experiments involve placing transmitter antenna and receiver antenna in a hot cell with variable strength of radiation to study the attenuation effects of the radioactive media. The results indicate that radiation does not effect on the electromagnetic wave propagation. This fact should be considered during the design and deployment wireless systems in a potentially radioactive environment

Letter-Sound Knowledge: Exploring Gender Differences in Children When They Start School Regarding Knowledge of Large Letters, Small Letters, Sound Large Letters, and Sound Small Letters

Directory of Open Access Journals (Sweden)

Hermundur Sigmundsson

2017-09-01

Full Text Available This study explored whether there is a gender difference in letter-sound knowledge when children start at school. 485 children aged 5–6 years completed assessment of letter-sound knowledge, i.e., large letters; sound of large letters; small letters; sound of small letters. The findings indicate a significant difference between girls and boys in all four factors tested in this study in favor of the girls. There are still no clear explanations to the basis of a presumed gender difference in letter-sound knowledge. That the findings have origin in neuro-biological factors cannot be excluded, however, the fact that girls probably have been exposed to more language experience/stimulation compared to boys, lends support to explanations derived from environmental aspects.

Experimental validation of wireless communication with chaos

International Nuclear Information System (INIS)

Ren, Hai-Peng; Bai, Chao; Liu, Jian; Baptista, Murilo S.; Grebogi, Celso

2016-01-01

The constraints of a wireless physical media, such as multi-path propagation and complex ambient noises, prevent information from being communicated at low bit error rate. Surprisingly, it has only recently been shown that, from a theoretical perspective, chaotic signals are optimal for communication. It maximises the receiver signal-to-noise performance, consequently minimizing the bit error rate. This work demonstrates numerically and experimentally that chaotic systems can in fact be used to create a reliable and efficient wireless communication system. Toward this goal, we propose an impulsive control method to generate chaotic wave signals that encode arbitrary binary information signals and an integration logic together with the match filter capable of decreasing the noise effect over a wireless channel. The experimental validation is conducted by inputting the signals generated by an electronic transmitting circuit to an electronic circuit that emulates a wireless channel, where the signals travel along three different paths. The output signal is decoded by an electronic receiver, after passing through a match filter.

Experimental validation of wireless communication with chaos

Energy Technology Data Exchange (ETDEWEB)

Ren, Hai-Peng; Bai, Chao; Liu, Jian [Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing, Xian University of Technology, Xian 710048 (China); Baptista, Murilo S.; Grebogi, Celso [Institute for Complex System and Mathematical Biology, SUPA, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

2016-08-15

The constraints of a wireless physical media, such as multi-path propagation and complex ambient noises, prevent information from being communicated at low bit error rate. Surprisingly, it has only recently been shown that, from a theoretical perspective, chaotic signals are optimal for communication. It maximises the receiver signal-to-noise performance, consequently minimizing the bit error rate. This work demonstrates numerically and experimentally that chaotic systems can in fact be used to create a reliable and efficient wireless communication system. Toward this goal, we propose an impulsive control method to generate chaotic wave signals that encode arbitrary binary information signals and an integration logic together with the match filter capable of decreasing the noise effect over a wireless channel. The experimental validation is conducted by inputting the signals generated by an electronic transmitting circuit to an electronic circuit that emulates a wireless channel, where the signals travel along three different paths. The output signal is decoded by an electronic receiver, after passing through a match filter.

Experimental validation of wireless communication with chaos.

Science.gov (United States)

Ren, Hai-Peng; Bai, Chao; Liu, Jian; Baptista, Murilo S; Grebogi, Celso

2016-08-01

The constraints of a wireless physical media, such as multi-path propagation and complex ambient noises, prevent information from being communicated at low bit error rate. Surprisingly, it has only recently been shown that, from a theoretical perspective, chaotic signals are optimal for communication. It maximises the receiver signal-to-noise performance, consequently minimizing the bit error rate. This work demonstrates numerically and experimentally that chaotic systems can in fact be used to create a reliable and efficient wireless communication system. Toward this goal, we propose an impulsive control method to generate chaotic wave signals that encode arbitrary binary information signals and an integration logic together with the match filter capable of decreasing the noise effect over a wireless channel. The experimental validation is conducted by inputting the signals generated by an electronic transmitting circuit to an electronic circuit that emulates a wireless channel, where the signals travel along three different paths. The output signal is decoded by an electronic receiver, after passing through a match filter.

Determination of outdoor signal propagation via visibility analysis in outdoor wireless networks

Directory of Open Access Journals (Sweden)

Mustafa Coşar

2017-02-01

Full Text Available Wireless networks on university campuses has gained importance in recent years. These networks in major areas such as university campuses, are faced with many problems during the planning, design and establishment. These problems are among the first that comes to mind, the physical properties of the campus and is selected according to the characteristics of network equipment. There is no doubt at all points of a wireless network set up in order to provide uninterrupted service and quality of the signal is expected to be good. However, it should be understood literally cannot meet these expectations. Therefore, to solve many problems to campus planning and design can be made to have acceptable signal distribution will have the appropriate use of and satisfaction with increasing effect. In this study, due to the start of construction on the North Campus of Hitit University, wireless signal spread using the current spread has been determined with the help of geographic information systems visibility analysis. An area of 56 hectares, with the total of 9 AP the acceptable signal distribution was obtained.

Adaptive Wavelet Coding Applied in a Wireless Control System.

Science.gov (United States)

Gama, Felipe O S; Silveira, Luiz F Q; Salazar, Andrés O

2017-12-13

Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus E b / N 0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.

Adaptive Wavelet Coding Applied in a Wireless Control System

Directory of Open Access Journals (Sweden)

Felipe O. S. Gama

2017-12-01

Full Text Available Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER versus E b / N 0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.

Wireless cardiac action potential transmission with ultrasonically inserted silicon microprobes

International Nuclear Information System (INIS)

Shen, C J; Ramkumar, A; Lal, A; Gilmour, R F Jr

2011-01-01

This paper reports on the integration of ultrasonically inserted horn-shaped cardiac probes with wireless transmission of 3D cardiac action potential measurement for applications in ex vivo preparations such as monitoring the onset of ventricular fibrillation. Ultrasonically inserted silicon horn probes permit reduced penetration force during insertion, allowing silicon, a brittle material, to penetrate cardiac tissue. The probes also allow recording from multiple sites that are lithographically defined. An application-specific integrated circuit has been designed with a 40 dB amplifying stage and a frequency modulating oscillator at 95 MHz to wirelessly transmit the recorded action potentials. This ultrasonically inserted microprobe wireless system demonstrates the initial results in wireless monitoring of 3D action potential propagation, and the extraction of parameters of interest including the action potential duration and diastolic interval

Reduced-Complexity Wireless Transceiver Architectures and Techniques for Space-Time Communications

DEFF Research Database (Denmark)

Tsakalaki, Elpiniki

2012-01-01

The dissertation sheds light on the performance gains of multi-antenna systems when the antenna aspects and the associated signal processing and coding aspects are integrated together in a multidisciplinary approach, addressing a variety of challenging tasks pertaining to the joint design of smart...... wireless transceivers and communication techniques. These tasks are at the intersection of different scientific disciplines including signal processing, communications, antennas and propagation. Specifically, the thesis deals with reduced-complexity space-time wireless transceiver architectures...... and associated communication techniques for multi-input multi-output (MIMO) and cognitive radio (CR) systems as well as wireless sensor networks (WSNs). The low-complexity architectures are obtained by equipping the wireless transceiver with passive control ports which require the minimum amount of RF hardware...

Propagation Analysis for Wireless Sensor Networks Applied to Viticulture

OpenAIRE

Correia, Felipe Pinheiro; Alencar, Marcelo Sampaio de; Lopes, Waslon Terllizzie Araújo; Assis, Mauro Soares de; Leal, Brauliro Gonçalves

2017-01-01

Wireless sensor networks have been proposed as a solution to obtain soil and environment information in large distributed areas. The main economic activity of the São Francisco Valley region in the Northeast of Brazil is the irrigated fruit production. The region is one of the major agricultural regions of the country. Grape plantations receive large investments and provide good financial return. However, the region still lacks electronic sensing systems to extract adequate information from p...

Effect of LOS/NLOS Propagation on 5G Ultra-Dense Networks

DEFF Research Database (Denmark)

Galiotto, Carlo; Pratas, Nuno; Doyle, Linda

2017-01-01

The combined presence of Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) components in the radio propagation environment can severely degrade the Ultra-Dense Networks (UDNs) performance. Backed by a stochastic geometry model, we show that when the LOS/NLOS propagation components are taken into a...... and to take advantage of extreme cell densification in the upcoming 5G wireless networks....

System-level Modeling of Wireless Integrated Sensor Networks

DEFF Research Database (Denmark)

Virk, Kashif M.; Hansen, Knud; Madsen, Jan

2005-01-01

Wireless integrated sensor networks have emerged as a promising infrastructure for a new generation of monitoring and tracking applications. In order to efficiently utilize the extremely limited resources of wireless sensor nodes, accurate modeling of the key aspects of wireless sensor networks...... is necessary so that system-level design decisions can be made about the hardware and the software (applications and real-time operating system) architecture of sensor nodes. In this paper, we present a SystemC-based abstract modeling framework that enables system-level modeling of sensor network behavior...... by modeling the applications, real-time operating system, sensors, processor, and radio transceiver at the sensor node level and environmental phenomena, including radio signal propagation, at the sensor network level. We demonstrate the potential of our modeling framework by simulating and analyzing a small...

Field test of wireless sensor network in the nuclear environment

International Nuclear Information System (INIS)

Li, L.; Wang, Q.; Bari, A.; Deng, C.; Chen, D.; Jiang, J.; Alexander, Q.; Sur, B.

2014-01-01

Wireless sensor networks (WSNs) are appealing options for the health monitoring of nuclear power plants due to their low cost and flexibility. Before they can be used in highly regulated nuclear environments, their reliability in the nuclear environment and compatibility with existing devices have to be assessed. In situ electromagnetic interference tests, wireless signal propagation tests, and nuclear radiation hardness tests conducted on candidate WSN systems at AECL Chalk River Labs are presented. The results are favourable to WSN in nuclear applications. (author)

Field test of wireless sensor network in the nuclear environment

Energy Technology Data Exchange (ETDEWEB)

Li, L., E-mail: lil@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Wang, Q.; Bari, A. [Univ. of Western Ontario, London, Ontario (Canada); Deng, C.; Chen, D. [Univ. of Electronic Science and Technology of China, Chengdu, Sichuan (China); Jiang, J. [Univ. of Western Ontario, London, Ontario (Canada); Alexander, Q.; Sur, B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

2014-06-15

Wireless sensor networks (WSNs) are appealing options for the health monitoring of nuclear power plants due to their low cost and flexibility. Before they can be used in highly regulated nuclear environments, their reliability in the nuclear environment and compatibility with existing devices have to be assessed. In situ electromagnetic interference tests, wireless signal propagation tests, and nuclear radiation hardness tests conducted on candidate WSN systems at AECL Chalk River Labs are presented. The results are favourable to WSN in nuclear applications. (author)

Numerical study of propagation effects in a wireless mesh test bed

CSIR Research Space (South Africa)

Lysko, AA

2008-07-01

Full Text Available The present layout of the indoor wireless mesh network test-bed build at the Meraka Institute is introduced. This is followed by a description of a numerical electromagnetic model for the complete test-bed, including the coupling and diffraction...

Radio frequency propagation model and fading of wireless signal at 2.4 GHz in an underground coal mine

OpenAIRE

Patri, A.; Nimaje, D. S.

2015-01-01

Wireless sensor networks and wireless communication systems have become indispensable in underground mines. Wireless sensor networks are being used for better real-time data acquisition from ground monitoring devices, gas sensors, and mining equipment, whereas wireless communication systems are needed for locating and communicating with workers. Conventional methods like wireline communication have proved to be ineffective in the event of mine hazards such as roof falls, fires etc. Before imp...

Analyses and optimization of Lee propagation model for LoRa 868 MHz network deployments in urban areas

Directory of Open Access Journals (Sweden)

Dobrilović Dalibor

2017-01-01

Full Text Available In the recent period, fast ICT expansion and rapid appearance of new technologies raised the importance of fast and accurate planning and deployment of emerging communication technologies, especially wireless ones. In this paper is analyzed possible usage of Lee propagation model for planning, design and management of networks based on LoRa 868MHz technology. LoRa is wireless technology which can be deployed in various Internet of Things and Smart City scenarios in urban areas. The analyses are based on comparison of field measurements with model calculations. Besides the analyses of Lee propagation model usability, the possible optimization of the model is discussed as well. The research results can be used for accurate design, planning and for preparation of high-performance wireless resource management of various Internet of Things and Smart City applications in urban areas based on LoRa or similar wireless technology. The equipment used for measurements is based on open-source hardware.

Letters in the Forest: Global precedence effect disappears for letters but not for non-letters under reading-like conditions

Directory of Open Access Journals (Sweden)

Thomas eLachmann

2014-07-01

Full Text Available Normally-skilled reading involves special processing strategies for letters, which are habitually funneled into an abstract letter code. On the basis of previous studies we argue that this habit leads to the preferred usage of an analytic strategy for the processing of letters, while non-letters are preferably processed via a holistic strategy. The well-known Global Precedence Effect (GPE seems to contradict to this assumption, since, with compound, hierarchical figures, including letter items, faster responses are observed to the global than to the local level of the figure, as well as an asymmetric interference effect from global to local level. We argue that with letters these effects depend on presentation conditions; only when they elicit the processing strategies automatized for reading, an analytic strategy for letters in contrast to non-letters is to be expected. We compared the GPE for letters and non-letters in central viewing, with the global stimulus size close to the functional visual field in whole word reading (6.5o of visual angle and local stimuli close to the critical size for fluent reading of individual letters (.5o of visual angle. Under these conditions, the GPE remained robust for non-letters. For letters, however, it disappeared: letters showed no overall response time advantage for the global level and symmetric congruence effects (local-to-global as well as global-to local interference. We interpret these results as according to the view that reading is based on resident analytic visual processing strategies for letters.

On Throughput Improvement of Wireless Ad Hoc Networks with Hidden Nodes

Science.gov (United States)

Choi, Hong-Seok; Lim, Jong-Tae

In this letter, we present the throughput analysis of the wireless ad hoc networks based on the IEEE 802.11 MAC (Medium Access Control). Especially, our analysis includes the case with the hidden node problem so that it can be applied to the multi-hop networks. In addition, we suggest a new channel access control algorithm to maximize the network throughput and show the usefulness of the proposed algorithm through simulations.

SSIART: Opening the Way to Wireless Sensor Networks On-Board Spacecraft with an Inter-Agency Research Environment

Science.gov (United States)

Gunes-Lasnet, Sev; Dufour, Jean-Francois

2012-08-01

The potential uses and benefits of wireless technologies in space are very broad. Since many years the CCSDS SOIS wireless working group has worked at the identification of key applications for which wireless would bring benefits, and at supporting the deployment of wireless in space thanks to documents, in particular a Green informative book and magenta books presenting recommended practices.The Smart Sensor Inter-Agency Research Test bench (SSIART) is being designed to provide the space Agencies and the Industry with a reference smart sensor platform to test wireless sensor technologies in reference representative applications and RF propagation environments, while promoting these technologies at the same time.

30-Gb/s bidirectional transparent optical transmission with an MMF access and an indoor optical wireless link

NARCIS (Netherlands)

Chen, H.; Boom, van den H.P.A.; Tangdiongga, E.; Koonen, A.M.J.

2012-01-01

This letter describes a 30-Gb/s bidirectional transparent optical transmission, over a 4.4-km multimode fiber (MMF) in combination with an indoor optical wireless (OW) link, which could provide limited mobility. Due to MMF's advantages, such as lower installation costs and easy maintenance, it is

Radio Frequency Propagation Model and Fading of Wireless Signal at 2.4 GHz in Underground Coal Mine

OpenAIRE

Patri, Ashutosh; Nimaje, Devidas S.

2015-01-01

Deployment of wireless sensor networks and wireless communication systems have become indispensable for better real-time data acquisition from ground monitoring devices, gas sensors, and equipment used in underground mines as well as in locating the miners, since conventional methods like use of wireline communication are rendered ineffective in the event of mine hazards such as roof-falls, fire hazard etc. Before implementation of any wireless system, the variable path loss indices for diffe...

Terabit Wireless Communication Challenges

Science.gov (United States)

Hwu, Shian U.

2012-01-01

This presentation briefly discusses a research effort on Terabit Wireless communication systems for possible space applications. Recently, terahertz (THz) technology (300-3000 GHz frequency) has attracted a great deal of interest from academia and industry. This is due to a number of interesting features of THz waves, including the nearly unlimited bandwidths available, and the non-ionizing radiation nature which does not damage human tissues and DNA with minimum health threat. Also, as millimeter-wave communication systems mature, the focus of research is, naturally, moving to the THz range. Many scientists regard THz as the last great frontier of the electromagnetic spectrum, but finding new applications outside the traditional niches of radio astronomy, Earth and planetary remote sensing, and molecular spectroscopy particularly in biomedical imaging and wireless communications has been relatively slow. Radiologists find this area of study so attractive because t-rays are non-ionizing, which suggests no harm is done to tissue or DNA. They also offer the possibility of performing spectroscopic measurements over a very wide frequency range, and can even capture signatures from liquids and solids. According to Shannon theory, the broad bandwidth of the THz frequency bands can be used for terabit-per-second (Tb/s) wireless communication systems. This enables several new applications, such as cell phones with 360 degrees autostereoscopic displays, optic-fiber replacement, and wireless Tb/s file transferring. Although THz technology could satisfy the demand for an extremely high data rate, a number of technical challenges need to be overcome before its development. This presentation provides an overview the state-of-the- art in THz wireless communication and the technical challenges for an emerging application in Terabit wireless systems. The main issue for THz wave propagation is the high atmospheric attenuation, which is dominated by water vapor absorption in the THz

Study of RF Propagation Characteristics for Wireless Sensor Networks in Railroad Environments

Science.gov (United States)

2010-01-01

The freight railroad industry in North America is exerting efforts to leverage Wireless Sensor Networks to monitor systems and components on railcars. This allows fault detection and accident prevention even while a train is moving. Railcars, constru...

Power requirements and battery life measurement for wireless transmission between two nodes in different mediums

Directory of Open Access Journals (Sweden)

Radouane Karli

2017-06-01

Full Text Available One of the most important roles of the wireless sensor networks (WSN is to avoid wiring costs, be self-sustainable and be able to function for several years. However, due to the slow progress in battery technology, power continues to be a limited resource in wireless sensor communication and electric energy storage remains to be an important issue. On the other hand, if batteries must be replaced often, many remote sensing applications may become impractical. Therefore, batteries with long life on the order of several years are needed. This paper is an extension of work originally presented in The 5th International Conference on Electronic Devices, Systems and Applications to investigate further the power requirements for wireless data transfer between two nodes using batteries with different capacities (55 mAh, 550 mAh and 5500 mAh. In particular, the effect of a propagation medium such as air, distilled water and engine oil on the wireless communication inside a one meter long metallic pipe was investigated. Our first result shows a successful transmission of wireless signal through air, distilled water and oil medium with very low transmission losses. The second result shows that an increase in the battery capacity will increase the two-node wireless sensor operation time even in different propagation medium. This result can be used to determine the required battery capacity for extending the WSN operation time.

Preface for the book: Antennas And Propagation for Body-Centric Wireless Communications

DEFF Research Database (Denmark)

Frederiksen, Flemming Bjerge; Prasad, Ramjee

2006-01-01

The book address the following subjects: Body Centric Wireless Communications possibilities, Electromagnetic properties of the body, On-body Communication Channels at high and low frequency bands, Body Centric UWB Communications, Wearable Antennas for cellular and WLAN communications, Body...

An Integrated Intrusion Detection Model of Cluster-Based Wireless Sensor Network.

Science.gov (United States)

Sun, Xuemei; Yan, Bo; Zhang, Xinzhong; Rong, Chuitian

2015-01-01

Considering wireless sensor network characteristics, this paper combines anomaly and mis-use detection and proposes an integrated detection model of cluster-based wireless sensor network, aiming at enhancing detection rate and reducing false rate. Adaboost algorithm with hierarchical structures is used for anomaly detection of sensor nodes, cluster-head nodes and Sink nodes. Cultural-Algorithm and Artificial-Fish-Swarm-Algorithm optimized Back Propagation is applied to mis-use detection of Sink node. Plenty of simulation demonstrates that this integrated model has a strong performance of intrusion detection.

Opportunistic Beamforming with Wireless Powered 1-bit Feedback Through Rectenna Array

OpenAIRE

Krikidis, Ioannis

2015-01-01

This letter deals with the opportunistic beamforming (OBF) scheme for multi-antenna downlink with spatial randomness. In contrast to conventional OBF, the terminals return only 1-bit feedback, which is powered by wireless power transfer through a rectenna array. We study two fundamental topologies for the combination of the rectenna elements; the direct-current combiner and the radio-frequency combiner. The beam outage probability is derived in closed form for both combination schemes, by usi...

Statistical characterization of wave propagation in mine environments

KAUST Repository

Bakir, Onur

2012-07-01

A computational framework for statistically characterizing electromagnetic (EM) wave propagation through mine tunnels and galleries is presented. The framework combines a multi-element probabilistic collocation (ME-PC) method with a novel domain-decomposition (DD) integral equation-based EM simulator to obtain statistics of electric fields due to wireless transmitters in realistic mine environments. © 2012 IEEE.

Propagation modeling in a manufacturing environment

Energy Technology Data Exchange (ETDEWEB)

Birdwell, J.D.; Horn, R.D.; Rader, M.S. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Electrical Engineering; Shourbaji, A.A. [Oak Ridge Centers for Mfg. Technology, TN (United States)

1995-12-31

Wireless sensors which utilize low power spread spectrum data transmission have significant potential in industrial environments due to low cabling and installation costs. In addition, this technology imposes fewer constraints upon placement due to cable routing, allowing sensors to be installed in areas with poor access. Limitations are imposed on sensor and receiver placement by electromagnetic propagation effects in the industrial environment, including multipath and the presence of absorbing media. This paper explores the electromagnetic analysis of potential wireless sensor applications using commercially available finite element software. In addition, since the applications environment is often at least partially specified in electronic form using computer-aided drafting software, the importation of information from this software is discussed. Both three-dimensional and two-dimensional examples are presented which demonstrate the utility and limitations of the method.

Progress in Body-Worn Antennas for On-Body Propagation (invited)

DEFF Research Database (Denmark)

Jakobsen, Kaj Bjarne

2016-01-01

On-body propagation and on-body antennas for body-centric wireless communications are presented. The onbody communications rely on creeping waves launched and received by the antennas, respectively. Path gain and bandwidth at 2.4 GHz for different types of body-worn antennas for head-centric comm...

Site-Specific Study of In-Building Wireless Solutions with Poisson Traffic

DEFF Research Database (Denmark)

Liu, Zhen; Sørensen, Troels Bundgaard; Mogensen, Preben

2011-01-01

Due to the poor outdoor-to-indoor propagation into buildings, dedicated wireless systems installed inside the buildings is often preferred for providing indoor users with high-data-rate services. We study the typical in-building wireless solutions - distributed antenna system and small cell Femto...... system - together with another multi-cell system using our proposed centralized scheduling scheme. In our previous work, their performance is evaluated and compared in the LTE downlink context with full buffer traffic. Compared to real mobile networks, the full buffer traffic model is usually a worst...

Indoor Wireless RF Energy Transfer for Powering Wireless Sensors

Directory of Open Access Journals (Sweden)

H. Visser

2012-12-01

Full Text Available For powering wireless sensors in buildings, rechargeable batteries may be used. These batteries will be recharged remotely by dedicated RF sources. Far-field RF energy transport is known to suffer from path loss and therefore the RF power available on the rectifying antenna or rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency of the rectenna will also be very low. By optimizing not only the subsystems of a rectenna but also taking the propagation channel into account and using the channel information for adapting the transmit antenna radiation pattern, the RF energy transport efficiency will be improved. The rectenna optimization, channel modeling and design of a transmit antenna are discussed.

Addressing the Influence of Hidden State on Wireless Network Optimizations using Performance Maps

DEFF Research Database (Denmark)

Højgaard-Hansen, Kim; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

2015-01-01

be used to optimize the use of the wireless net- work by predicting future network performance and scheduling the net- work communication for certain applications on mobile devices. However, other important factors influence the performance of the wireless communication such as changes in the propagation...... environment and resource sharing. In this work we extend the framework of performance maps for wireless networks by introducing network state as an abstraction for all other factors than location that influence the performance. Since network state might not always be directly observable the framework......Performance of wireless connectivity for network client devices is location dependent. It has been shown that it can be beneficial to collect network performance metrics along with location information to generate maps of the location dependent network performance. These performance maps can...

Study on the Effect of Frequency on Conductivity of Underground Strata in Coal Mine Through-the-earth Wireless Communication

OpenAIRE

Jinyi TAO; Yuchen ZHANG

2014-01-01

The relationship of conductivity and the frequency, which is of decisive significance in through-the-earth wireless communication in coal mine, is closely related to the options of frequency range in coal mine wireless communication. When through-the-earth wireless communication is applied, the electromagnetic waves need to spread in the semi-conductive medium rocks. The main factors affecting the electromagnetic wave propagation in rocks is the rock strata electromagnetic parameters. These p...

Analysis Of Packets Delay In Wireless Data Networks

Directory of Open Access Journals (Sweden)

Krivchenkov Aleksandr

2015-12-01

Full Text Available The networks with wireless links for automation control applications traffic transmission when packets have small size and application payload is predictable are under consideration. Analytical model for packets delay on their propagation path through the network is proposed. Estimations for network architectures based on WiFi and Bluetooth wireless technologies are made. The specifications for physical layer 802.11 a/b/g/n and 802.15.1 are under consideration. Analytical and experimental results for delivered network bandwidth for different network architecture, traffic structure and wireless technologies were compared to validate that basic mechanisms are correctly taken into account in the model. It is shown that basic effects are taken into account and further accuracy “improvement” of the model will give not more than 5%. As a result that is important for automation control applications we have reliably received the lowest possible level for packets delay in one wireless link. For 802.11 it is of order of 0.2 ms, for 802.15.1 it is 1.25 ms and is true when application packet can be transferred by one data frame.

Structured printed referral letter (form letter; saves time and improves communication

Directory of Open Access Journals (Sweden)

R.P.J.C. Ramanayake

2013-01-01

Full Text Available Referral of patients to hospitals, specialists and other institutions is an essential part of primary health care. Patients are referred to specialists when investigation or therapeutic options are exhausted in primary care or when opinion or advice is needed from them. Referral has considerable implications for patients, health care system and health care costs. Good communication between primary and secondary care is essential for the smooth running of any health care system. Referral and reply letters are the sole means of communication between doctors most of the time and breakdown in communication could lead to poor continuity of care, delayed diagnoses, polypharmacy, increased litigation risk and unnecessary testing. A referral letter also helps to avoid patient dissatisfaction and loss of confidence in family physician. Studies of referral letters have reported that specialists are dissatisfied with their quality and content. Inclusion of letter writing skills in the medical curriculum, peer assessment and feedback have shown to improve the quality of referral letters. . Form letters have shown to enhance information content and communication in referral process. In Sri Lanka referral letters are usually hand written and frequent complaints are that these letters do not contain adequate information and retrieval of information is a problem due to poor legibility and clarity. Sometimes Primary care doctors refer patients to hospitals and specialists with only verbal instructions. To address these short comings this form letter was introduced. Based on the guidelines and systematic review of published articles, items of information to be included were decided. Printed forms of the letter are kept in the practice and the doctor has to just fill up relevant information under each heading. The objectives of introducing this structured referral letter was to improve the quality and standard of referral letters and save time for both general

Power Optimization With BLER Constraint for Wireless Fronthauls in C-RAN

OpenAIRE

Vu, Thang Xuan; Nguyen, Thang Van; Quek, Tony Q.S.

2016-01-01

Cloud radio access network (C-RAN) is a novel architecture for future mobile networks to sustain the exponential traffic growth thanks to the exploitation of centralized processing. In C-RAN, one data processing center or baseband unit (BBU) communicates with users via distributed remote radio heads (RRHs), which are connected to the BBU via high capacity, low latency fronthaul links. In this letter, we study C-RAN with wireless fronthauls due to their flexibility in deployment and management...

Communication on SWIPT and EH Using Electromagnetic Behaviour for Power Allocation in Wireless Networks

Science.gov (United States)

Khan, Sohel Rana; Ajij, Sayyad

2017-12-01

This review paper focuses on the basic relations between wireless power transfer, wireless information transfer and combined phenomenon of simultaneous wireless information and power transfer. The authors reviewed and discussed electromagnetic fields behaviour (EMB) for enhancing the power allocation strategies (PAS) in energy harvesting (EH) wireless communication systems. Further, this paper presents relations between Friis transmission equation and Maxwell's equations to be used in propagation models for reduction in specific absorption rate (SAR). This paper provides a review of various methods and concepts reported in earlier works. This paper also reviews Poynting vector and power densities along with boundary conditions for antennas and human body. Finally, this paper explores the usage of electromagnetic behaviour for the possible enhancement in power saving methods for electromagnetic behaviour centered-wireless energy harvesting (EMBC-WEH). At the same time, possibilities of PAS for reduction in SAR are discussed.

Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

Science.gov (United States)

Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

2014-01-01

The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

Propagation Characterization Based on Geographic Location Variation for 5G Small Cells

Directory of Open Access Journals (Sweden)

Byung-Jin Lee

2017-01-01

Full Text Available Developments in next-generation wireless transmission technology and efficient frequency-use research are based on understanding the characteristics of the exact radio channel. With regard to developments in next-generation mobile communication systems, performance verification of the development system is essential, for which it is necessary to estimate the exact wireless-space channel. This paper presents results of the analysis of radio propagation characteristics based on location variation in outdoor environments for small-cell 5th generation (5G mobile systems. Changes due to variation in location were measured using a channel sounder in a microcell environment with a 0.5 km radius in Korea. In order to analyze the propagation characteristics, the best distribution model reflecting the characteristics of the locations was derived. A comparison between actual measurements and three-dimensional ray-tracing simulation results confirmed the validity of the measurement result.

Letter and symbol identification: No evidence for letter-specific crowding mechanisms.

Science.gov (United States)

Castet, Eric; Descamps, Marine; Denis-Noël, Ambre; Colé, Pascale

2017-09-01

It has been proposed that letters, as opposed to symbols, trigger specialized crowding processes, boosting identification of the first and last letters of words. This hypothesis is based on evidence that single-letter accuracy as a function of within-string position has a W shape (the classic serial position function [SPF] in psycholinguistics) whereas an inverted V shape is obtained when measured with symbols. Our main goal was to test the robustness of the latter result. Our hypothesis was that any letter/symbol difference might result from short-term visual memory processes (due to the partial report [PR] procedures used in SPF studies) rather than from crowding. We therefore removed the involvement of short-term memory by precueing target-item position and compared SPFs with precueing and postcueing. Perimetric complexity was stringently matched between letters and symbols. In postcueing conditions similar to previous studies, we did not reproduce the inverted V shape for symbols: Clear-cut W shapes were observed with an overall smaller accuracy for symbols compared to letters. This letter/symbol difference was dramatically reduced in precueing conditions in keeping with our prediction. Our results are not consistent with the claim that letter strings trigger specialized crowding processes. We argue that PR procedures are not fit to isolate crowding processes.

The effect of letter string length and report condition on letter recognition accuracy.

Science.gov (United States)

Raghunandan, Avesh; Karmazinaite, Berta; Rossow, Andrea S

Letter sequence recognition accuracy has been postulated to be limited primarily by low-level visual factors. The influence of high level factors such as visual memory (load and decay) has been largely overlooked. This study provides insight into the role of these factors by investigating the interaction between letter sequence recognition accuracy, letter string length and report condition. Letter sequence recognition accuracy for trigrams and pentagrams were measured in 10 adult subjects for two report conditions. In the complete report condition subjects reported all 3 or all 5 letters comprising trigrams and pentagrams, respectively. In the partial report condition, subjects reported only a single letter in the trigram or pentagram. Letters were presented for 100ms and rendered in high contrast, using black lowercase Courier font that subtended 0.4° at the fixation distance of 0.57m. Letter sequence recognition accuracy was consistently higher for trigrams compared to pentagrams especially for letter positions away from fixation. While partial report increased recognition accuracy in both string length conditions, the effect was larger for pentagrams, and most evident for the final letter positions within trigrams and pentagrams. The effect of partial report on recognition accuracy for the final letter positions increased as eccentricity increased away from fixation, and was independent of the inner/outer position of a letter. Higher-level visual memory functions (memory load and decay) play a role in letter sequence recognition accuracy. There is also suggestion of additional delays imposed on memory encoding by crowded letter elements. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Letters and Letter Writing in Early Modern Culture: An Introduction

Directory of Open Access Journals (Sweden)

Gabriella Del Lungo Camiciotti

2014-04-01

Full Text Available The recently renewed scholarly interest in historical letters and letter writing has given rise to several studies which explore the culture of epistolarity from different perspectives. The article offers an introduction to recent scholarship on epistolary discourse and practices in early modern culture. Given the importance of letters as data for several types of diachronic investigation, the article focuses on three points that are crucial for an understanding of the relevance of epistolary discourse itself in early modern European culture. Firstly, letters are invaluable data for historical linguistics, to which they provide information for the history of languages, and sociohistorical and sociolinguistic research. A second recent field of investigation considers letters as documents and material items; the results of research in this area have contributed to the reconstruction of official relationships and information exchanges in past cultures and shed light on social interaction. A third, more traditional area of study, deals with the letter as a form that has given rise to many different genres across the centuries, both practical and literary.

Opportunistic Beamforming with Wireless Powered 1-bit Feedback Through Rectenna Array

Science.gov (United States)

Krikidis, Ioannis

2015-11-01

This letter deals with the opportunistic beamforming (OBF) scheme for multi-antenna downlink with spatial randomness. In contrast to conventional OBF, the terminals return only 1-bit feedback, which is powered by wireless power transfer through a rectenna array. We study two fundamental topologies for the combination of the rectenna elements; the direct-current combiner and the radio-frequency combiner. The beam outage probability is derived in closed form for both combination schemes, by using high order statistics and stochastic geometry.

Effect of orthographic processes on letter-identity and letter-position encoding in dyslexic children

Directory of Open Access Journals (Sweden)

Caroline eReilhac

2012-05-01

Full Text Available The ability to identify letters and encode their position is a crucial step of the word recognition process. However and despite their word identification problem, the ability of dyslexic children to encode letter-identity and letter-position within strings was not systematically investigated. This study aimed at filling this gap and further explored how letter identity and letter position encoding is modulated by letter context in developmental dyslexia. For this purpose, a letter-string comparison task was administered to French dyslexic children and two chronological-age (CA and reading-age (RA-matched control groups. Children had to judge whether two successively and briefly presented 4-letter-strings were identical or different. Letter-position and letter-identity were manipulated through the transposition (e.g., RTGM vs. RMGT or substitution of two letters (e.g., TSHF vs. TGHD. Non-words, pseudo-words and words were used as stimuli to investigate sub-lexical and lexical effects on letter encoding. Dyslexic children showed both substitution and transposition detection problems relative to CA controls. A substitution advantage over transpositions was only found for words in dyslexic children whereas it extended to pseudo-words in RA controls and to all type of items in CA controls. Letters were better identified in the dyslexic group when belonging to orthographically familiar strings. Letter position encoding was very impaired in dyslexic children who did not show any word context effect in contrast to CA controls. Overall, the current findings point to a strong letter identity and letter position encoding disorder in developmental dyslexia.

Chromatic aberration compensation in numerical reconstruction of digital holograms by Fresnel-Bluestein propagation.

Science.gov (United States)

Hincapie, Diego; Velasquez, Daniel; Garcia-Sucerquia, Jorge

2017-12-15

In this Letter, we present a method for chromatic compensation in numerical reconstruction of digitally recorded holograms based on Fresnel-Bluestein propagation. The proposed technique is applied to correct the chromatic aberration that arises in the reconstruction of RGB holograms of both millimeter- and micrometer-sized objects. The results show the feasibility of this strategy to remove the wavelength dependence of the size of the numerically propagated wavefields.

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2018-01-01

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir

2018-02-28

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Analysis of 38 GHz mmWave Propagation Characteristics of Urban Scenarios

DEFF Research Database (Denmark)

Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Sørensen, Troels Bundgaard

2015-01-01

The 38 GHz mm-wave frequency band is a strong candidate for the future deployment of wireless systems. Compared to lower frequency bands, propagation in the 38 GHz band is relatively unexplored for access networks in urban scenarios. This paper presents a detailed measurement-based analysis of ur...

Optical wireless communications an emerging technology

CERN Document Server

Capsoni, Carlo; Ghassemlooy, Zabih; Boucouvalas, Anthony; Udvary, Eszter

2016-01-01

This book focuses on optical wireless communications (OWC), an emerging technology with huge potential for the provision of pervasive and reliable next-generation communications networks. It shows how the development of novel and efficient wireless technologies can contribute to a range of transmission links essential for the heterogeneous networks of the future to support various communications services and traffic patterns with ever-increasing demands for higher data-transfer rates. The book starts with a chapter reviewing the OWC field, which explains different sub-technologies (visible-light, ultraviolet (UV) and infrared (IR) communications) and introduces the spectrum of application areas (indoor, vehicular, terrestrial, underwater, intersatellite, deep space, etc.). This provides readers with the necessary background information to understand the specialist material in the main body of the book, which is in four parts. The first of these deals with propagation modelling and channel characterization of ...

Investigation of propagation dynamics of truncated vector vortex beams.

Science.gov (United States)

Srinivas, P; Perumangatt, C; Lal, Nijil; Singh, R P; Srinivasan, B

2018-06-01

In this Letter, we experimentally investigate the propagation dynamics of truncated vector vortex beams generated using a Sagnac interferometer. Upon focusing, the truncated vector vortex beam is found to regain its original intensity structure within the Rayleigh range. In order to explain such behavior, the propagation dynamics of a truncated vector vortex beam is simulated by decomposing it into the sum of integral charge beams with associated complex weights. We also show that the polarization of the truncated composite vector vortex beam is preserved all along the propagation axis. The experimental observations are consistent with theoretical predictions based on previous literature and are in good agreement with our simulation results. The results hold importance as vector vortex modes are eigenmodes of the optical fiber.

A matched Bow-tie antenna at 433MHz for use in underwater wireless sensor networks

International Nuclear Information System (INIS)

Abdou, A A; Shaw, A; Mason, A; Al-Shamma'a, A; Cullen, J; Wylie, S; Diallo, M

2013-01-01

Electromagnetic (EM) wave propagation underwater is been disregarded because of attenuation at high frequencies, however the theory predicts that propagation is possible at some useful distance in the lower Industrial, Scientific and Medical (ISM) band. Common transceivers rely on narrowband antennas and matching circuit. The aim of this paper is to design a broadband 433MHz bow-tie antenna and experiment it in air and water without a matching circuit. This antenna could be attached to wireless transceivers and form a Wireless Sensor Network for deployment in various underwater applications. The bow-tie antennas were designed, simulated and constructed in laboratory. Experiments were setup carefully by using a completely isolated transmitter from electronics to avoid airborne transmission. The 433MHz. bow-tie proved its suitability for use in Underwater.

100-GHz Wireless-Over-Fiber Links With Up to 16-Gb/s QPSK Modulation Using Optical Heterodyne Generation and Digital Coherent Detection

DEFF Research Database (Denmark)

Sambaraju, R.; Zibar, Darko; Caballero Jambrina, Antonio

2010-01-01

In this letter, a novel technique for direct conversion of an optical baseband quadrature phase-shift keying (QPSK) signal to a millimeter-wave wireless signal and subsequent signal demodulation is reported. Optical heterodyne mixing of the optical baseband QPSK signal with a free-running unmodul...

Statistical Characterization of Electromagnetic Wave Propagation in Mine Environments

KAUST Repository

Yucel, Abdulkadir C.

2013-01-01

A computational framework for statistically characterizing electromagnetic (EM) wave propagation through mine tunnels and galleries is presented. The framework combines a multi-element probabilistic collocation method with a full-wave fast Fourier transform and fast multipole method accelerated surface integral equation-based EM simulator to statistically characterize fields from wireless transmitters in complex mine environments. 1536-1225 © 2013 IEEE.

Signal Processing for Improved Wireless Receiver Performance

DEFF Research Database (Denmark)

Christensen, Lars P.B.

2007-01-01

This thesis is concerned with signal processing for improving the performance of wireless communication receivers for well-established cellular networks such as the GSM/EDGE and WCDMA/HSPA systems. The goal of doing so, is to improve the end-user experience and/or provide a higher system capacity...... by allowing an increased reuse of network resources. To achieve this goal, one must first understand the nature of the problem and an introduction is therefore provided. In addition, the concept of graph-based models and approximations for wireless communications is introduced along with various Belief...... Propagation (BP) methods for detecting the transmitted information, including the Turbo principle. Having established a framework for the research, various approximate detection schemes are discussed. First, the general form of linear detection is presented and it is argued that this may be preferable...

Worm epidemics in wireless ad hoc networks

Energy Technology Data Exchange (ETDEWEB)

Nekovee, Maziar [BT Research, Polaris 134, Adastral Park, Martlesham, Suffolk IP5 3RE (United Kingdom); Centre for Computational Science, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

2007-06-15

A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

Worm epidemics in wireless ad hoc networks

Science.gov (United States)

Nekovee, Maziar

2007-06-01

A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

Worm epidemics in wireless ad hoc networks

International Nuclear Information System (INIS)

Nekovee, Maziar

2007-01-01

A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet

Prediction of transmission distortion for wireless video communication: analysis.

Science.gov (United States)

Chen, Zhifeng; Wu, Dapeng

2012-03-01

Transmitting video over wireless is a challenging problem since video may be seriously distorted due to packet errors caused by wireless channels. The capability of predicting transmission distortion (i.e., video distortion caused by packet errors) can assist in designing video encoding and transmission schemes that achieve maximum video quality or minimum end-to-end video distortion. This paper is aimed at deriving formulas for predicting transmission distortion. The contribution of this paper is twofold. First, we identify the governing law that describes how the transmission distortion process evolves over time and analytically derive the transmission distortion formula as a closed-form function of video frame statistics, channel error statistics, and system parameters. Second, we identify, for the first time, two important properties of transmission distortion. The first property is that the clipping noise, which is produced by nonlinear clipping, causes decay of propagated error. The second property is that the correlation between motion-vector concealment error and propagated error is negative and has dominant impact on transmission distortion, compared with other correlations. Due to these two properties and elegant error/distortion decomposition, our formula provides not only more accurate prediction but also lower complexity than the existing methods.

Wireless data transfer in saliniferous formations

International Nuclear Information System (INIS)

Wilsnack, T.; Grafe, F.; Roessel, A.

2012-01-01

The metrological surveillance of processes and long-term monitoring is an important requirement for closed mines or radioactive waste repositories. The available measuring technology is usually based on electrical power supply using existing underground power network. This is in contradiction with the targeted sealing of the monitored mine caverns and/or the integrity of hydraulic barriers. The authors developed a concept of wireless data transfer based on the radio wave propagation in mostly dry saliniferous formations. The system was tests at several reference sites.

An Integrated Signaling-Encryption Mechanism to Reduce Error Propagation in Wireless Communications: Performance Analyses

Energy Technology Data Exchange (ETDEWEB)

Olama, Mohammed M [ORNL; Matalgah, Mustafa M [ORNL; Bobrek, Miljko [ORNL

2015-01-01

Traditional encryption techniques require packet overhead, produce processing time delay, and suffer from severe quality of service deterioration due to fades and interference in wireless channels. These issues reduce the effective transmission data rate (throughput) considerably in wireless communications, where data rate with limited bandwidth is the main constraint. In this paper, performance evaluation analyses are conducted for an integrated signaling-encryption mechanism that is secure and enables improved throughput and probability of bit-error in wireless channels. This mechanism eliminates the drawbacks stated herein by encrypting only a small portion of an entire transmitted frame, while the rest is not subject to traditional encryption but goes through a signaling process (designed transformation) with the plaintext of the portion selected for encryption. We also propose to incorporate error correction coding solely on the small encrypted portion of the data to drastically improve the overall bit-error rate performance while not noticeably increasing the required bit-rate. We focus on validating the signaling-encryption mechanism utilizing Hamming and convolutional error correction coding by conducting an end-to-end system-level simulation-based study. The average probability of bit-error and throughput of the encryption mechanism are evaluated over standard Gaussian and Rayleigh fading-type channels and compared to the ones of the conventional advanced encryption standard (AES).

Implementation and Analysis of a Wireless Sensor Network-Based Pet Location Monitoring System for Domestic Scenarios.

Science.gov (United States)

Aguirre, Erik; Lopez-Iturri, Peio; Azpilicueta, Leyre; Astrain, José Javier; Villadangos, Jesús; Santesteban, Daniel; Falcone, Francisco

2016-08-30

The flexibility of new age wireless networks and the variety of sensors to measure a high number of variables, lead to new scenarios where anything can be monitored by small electronic devices, thereby implementing Wireless Sensor Networks (WSN). Thanks to ZigBee, RFID or WiFi networks the precise location of humans or animals as well as some biological parameters can be known in real-time. However, since wireless sensors must be attached to biological tissues and they are highly dispersive, propagation of electromagnetic waves must be studied to deploy an efficient and well-working network. The main goal of this work is to study the influence of wireless channel limitations in the operation of a specific pet monitoring system, validated at physical channel as well as at functional level. In this sense, radio wave propagation produced by ZigBee devices operating at the ISM 2.4 GHz band is studied through an in-house developed 3D Ray Launching simulation tool, in order to analyze coverage/capacity relations for the optimal system selection as well as deployment strategy in terms of number of transceivers and location. Furthermore, a simplified dog model is developed for simulation code, considering not only its morphology but also its dielectric properties. Relevant wireless channel information such as power distribution, power delay profile and delay spread graphs are obtained providing an extensive wireless channel analysis. A functional dog monitoring system is presented, operating over the implemented ZigBee network and providing real time information to Android based devices. The proposed system can be scaled in order to consider different types of domestic pets as well as new user based functionalities.

Implementation and Analysis of a Wireless Sensor Network-Based Pet Location Monitoring System for Domestic Scenarios

Directory of Open Access Journals (Sweden)

Erik Aguirre

2016-08-01

Full Text Available The flexibility of new age wireless networks and the variety of sensors to measure a high number of variables, lead to new scenarios where anything can be monitored by small electronic devices, thereby implementing Wireless Sensor Networks (WSN. Thanks to ZigBee, RFID or WiFi networks the precise location of humans or animals as well as some biological parameters can be known in real-time. However, since wireless sensors must be attached to biological tissues and they are highly dispersive, propagation of electromagnetic waves must be studied to deploy an efficient and well-working network. The main goal of this work is to study the influence of wireless channel limitations in the operation of a specific pet monitoring system, validated at physical channel as well as at functional level. In this sense, radio wave propagation produced by ZigBee devices operating at the ISM 2.4 GHz band is studied through an in-house developed 3D Ray Launching simulation tool, in order to analyze coverage/capacity relations for the optimal system selection as well as deployment strategy in terms of number of transceivers and location. Furthermore, a simplified dog model is developed for simulation code, considering not only its morphology but also its dielectric properties. Relevant wireless channel information such as power distribution, power delay profile and delay spread graphs are obtained providing an extensive wireless channel analysis. A functional dog monitoring system is presented, operating over the implemented ZigBee network and providing real time information to Android based devices. The proposed system can be scaled in order to consider different types of domestic pets as well as new user based functionalities.

Jamming Attack in Wireless Sensor Network: From Time to Space

Science.gov (United States)

Sun, Yanqiang; Wang, Xiaodong; Zhou, Xingming

Classical jamming attack models in the time domain have been proposed, such as constant jammer, random jammer, and reactive jammer. In this letter, we consider a new problem: given k jammers, how does the attacker minimize the pair-wise connectivity among the nodes in a Wireless Sensor Network (WSN)? We call this problem k-Jammer Deployment Problem (k-JDP). To the best of our knowledge, this is the first attempt at considering the position-critical jamming attack against wireless sensor network. We mainly make three contributions. First, we prove that the decision version of k-JDP is NP-complete even in the ideal situation where the attacker has full knowledge of the topology information of sensor network. Second, we propose a mathematical formulation based on Integer Programming (IP) model which yields an optimal solution. Third, we present a heuristic algorithm HAJDP, and compare it with the IP model. Numerical results show that our heuristic algorithm is computationally efficient.

Advanced Wireless Local Area Networks in the Unlicensed Sub-1GHz ISM-bands

NARCIS (Netherlands)

Aust, S.H.

2014-01-01

This dissertation addresses the challenges of wireless local area networks (WLANs) that operate in the unlicensed sub-1GHz industrial, scientific, and medical (ISM) band. Frequencies in the 900MHz spectrum enable a wider coverage due to the longer propagation characteristics of the radio waves. To

Chaos-based wireless communication resisting multipath effects

Science.gov (United States)

Yao, Jun-Liang; Li, Chen; Ren, Hai-Peng; Grebogi, Celso

2017-09-01

In additive white Gaussian noise channel, chaos has been shown to be the optimal coherent communication waveform in the sense of using a very simple matched filter to maximize the signal-to-noise ratio. Recently, Lyapunov exponent spectrum of the chaotic signals after being transmitted through a wireless channel has been shown to be unaltered, paving the way for wireless communication using chaos. In wireless communication systems, inter-symbol interference caused by multipath propagation is one of the main obstacles to achieve high bit transmission rate and low bit-error rate (BER). How to resist the multipath effect is a fundamental problem in a chaos-based wireless communication system (CWCS). In this paper, a CWCS is built to transmit chaotic signals generated by a hybrid dynamical system and then to filter the received signals by using the corresponding matched filter to decrease the noise effect and to detect the binary information. We find that the multipath effect can be effectively resisted by regrouping the return map of the received signal and by setting the corresponding threshold based on the available information. We show that the optimal threshold is a function of the channel parameters and of the information symbols. Practically, the channel parameters are time-variant, and the future information symbols are unavailable. In this case, a suboptimal threshold is proposed, and the BER using the suboptimal threshold is derived analytically. Simulation results show that the CWCS achieves a remarkable competitive performance even under inaccurate channel parameters.

Propagation Path Loss Models for 5G Urban Micro- and Macro-Cellular Scenarios

DEFF Research Database (Denmark)

Sun, Shu; Rappaport, Theodore S.; Rangan, Sundeep

2016-01-01

This paper presents and compares two candidate large-scale propagation path loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space reference distance model, for the design of fifth generation (5G) wireless communication systems in urban micro- and macro-cellular scenarios....

A wireless sensor enabled by wireless power.

Science.gov (United States)

Lee, Da-Sheng; Liu, Yu-Hong; Lin, Chii-Ruey

2012-11-22

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

What Do Letter Migration Errors Reveal About Letter Position Coding in Visual Word Recognition?

Science.gov (United States)

Davis, Colin J.; Bowers, Jeffrey S.

2004-01-01

Dividing attention across multiple words occasionally results in misidentifications whereby letters apparently migrate between words. Previous studies have found that letter migrations preserve within-word letter position, which has been interpreted as support for position-specific letter coding. To investigate this issue, the authors used word…

Analysis of reliability of professor recommendation letters based on concordance with self-introduction letter.

Science.gov (United States)

Kim, Sang Hyun

2013-12-01

The purpose of this study was to examine the concordance between a checklist's categories of professor recommendation letters and characteristics of the self-introduction letter. Checklists of professor recommendation letters were analyzed and classified into cognitive, social, and affective domains. Simple correlation was performed to determine whether the characteristics of the checklists were concordant with those of the self-introduction letter. The difference in ratings of the checklists by pass or fail grades was analyzed by independent sample t-test. Logistic regression analysis was performed to determine whether a pass or fail grade was influenced by ratings on the checklists. The Cronbach alpha value of the checklists was 0.854. Initiative, as an affective domain, in the professor's recommendation letter was highly ranked among the six checklist categories. Self-directed learning in the self-introduction letter was influenced by a pass or fail grade by logistic regression analysis (pprofessor recommendation letters and the sum of all characteristics in the self-introduction letter.

Wireless Local Area Network Performance Inside Aircraft Passenger Cabins

Science.gov (United States)

Whetten, Frank L.; Soroker, Andrew; Whetten, Dennis A.; Whetten, Frank L.; Beggs, John H.

2005-01-01

An examination of IEEE 802.11 wireless network performance within an aircraft fuselage is performed. This examination measured the propagated RF power along the length of the fuselage, and the associated network performance: the link speed, total throughput, and packet losses and errors. A total of four airplanes: one single-aisle and three twin-aisle airplanes were tested with 802.11a, 802.11b, and 802.11g networks.

Optimal training sequences for indoor wireless optical communications

International Nuclear Information System (INIS)

Wang, Jun-Bo; Jiao, Yuan; Song, Xiaoyu; Chen, Ming

2012-01-01

Since indoor wireless optical communication (WOC) systems can offer several potential advantages over their radio frequency counterparts, there has been a growing interest in indoor WOC systems. Influenced by the complicated optical propagation environment, there exist multipath propagation phenomena. In order to eliminate the effect of multipath propagation, much attention should be concentrated on the channel estimation in indoor WOC systems. This paper investigates optimal training sequences (TSs) for estimating a channel impulse response in indoor WOC systems. Based on the Cramer–Rao bound (CRB) theorem, an explicit form of search criterion is found. Optimum TSs are obtained and tabulated by computer search for different channel responses and TS lengths. Measured by mean square error (MSE) performance, channel estimation errors are also investigated. Simulation results show that the MSE of the channel estimator at the receiver can be reduced significantly by using the optimized TS set. Moreover, the longer the TS, the better the MSE performance that can be obtained when the channel order is fixed. (paper)

A STUDY ON LEGIBILITY OF LETTERING

Directory of Open Access Journals (Sweden)

Merve ERSAN,

2016-04-01

Full Text Available In the most general sense, lettering is the art of drawing letters, in which the letter forms carry illustrtive features. In this research which is titled "An Analysis on Legibility in Letterings Used in Print Advertisements", letterings used in and specially designed for print ads are analysed and their contribution to the ads are examined. Legibility, which is the fundamental function of writing and typography is examined in the field of lettering that has an illustrative approach. Also, the article puts emphasis on the technique and form’s contribution on content in letterings. Keywords: Lettering, print advertisements, letter design, illustration, legibility.

An Empirical Study of Propagation Models for Wireless Communications in Open-pit Mines

DEFF Research Database (Denmark)

Portela Lopes de Almeida, Erika; Caldwell, George; Rodriguez Larrad, Ignacio

2018-01-01

—In this paper, we investigate the suitability of the propagation models ITU-R 526, Okumura Hata, COST Hata models and Standard Propagation Model (SPM) to predict the path loss in open-pit mines. The models are evaluated by comparing the predicted data with measurements obtained in two operational...

Impact of a half-space interface on the wireless link between tiny sensor nodes

NARCIS (Netherlands)

Penkin, D.; Janssen, G.; Yarovoy, A.

2014-01-01

The power budget of a wireless link between two electrically small sensor nodes located close to an interface between two media is studied. The model includes both the propagation channel losses and input impedance of the radio frequency antennas. It is shown that a highly inductive half-space

An Improved Split-Step Wavelet Transform Method for Anomalous Radio Wave Propagation Modelling

Directory of Open Access Journals (Sweden)

A. Iqbal

2014-12-01

Full Text Available Anomalous tropospheric propagation caused by ducting phenomenon is a major problem in wireless communication. Thus, it is important to study the behavior of radio wave propagation in tropospheric ducts. The Parabolic Wave Equation (PWE method is considered most reliable to model anomalous radio wave propagation. In this work, an improved Split Step Wavelet transform Method (SSWM is presented to solve PWE for the modeling of tropospheric propagation over finite and infinite conductive surfaces. A large number of numerical experiments are carried out to validate the performance of the proposed algorithm. Developed algorithm is compared with previously published techniques; Wavelet Galerkin Method (WGM and Split-Step Fourier transform Method (SSFM. A very good agreement is found between SSWM and published techniques. It is also observed that the proposed algorithm is about 18 times faster than WGM and provide more details of propagation effects as compared to SSFM.

Subsurface event detection and classification using Wireless Signal Networks.

Science.gov (United States)

Yoon, Suk-Un; Ghazanfari, Ehsan; Cheng, Liang; Pamukcu, Sibel; Suleiman, Muhannad T

2012-11-05

Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs). The wireless signal networks take advantage of the variations of radio signal strength on the distributed underground sensor nodes of WSiNs to monitor and characterize the sensed area. To characterize subsurface environments for event detection and classification, this paper provides a detailed list and experimental data of soil properties on how radio propagation is affected by soil properties in subsurface communication environments. Experiments demonstrated that calibrated wireless signal strength variations can be used as indicators to sense changes in the subsurface environment. The concept of WSiNs for the subsurface event detection is evaluated with applications such as detection of water intrusion, relative density change, and relative motion using actual underground sensor nodes. To classify geo-events using the measured signal strength as a main indicator of geo-events, we propose a window-based minimum distance classifier based on Bayesian decision theory. The window-based classifier for wireless signal networks has two steps: event detection and event classification. With the event detection, the window-based classifier classifies geo-events on the event occurring regions that are called a classification window. The proposed window-based classification method is evaluated with a water leakage experiment in which the data has been measured in laboratory experiments. In these experiments, the proposed detection and classification method based on wireless signal network can detect and classify subsurface events.

Selective propagation and beam splitting of surface plasmons on metallic nanodisk chains.

Science.gov (United States)

Hu, Yuhui; Zhao, Di; Wang, Zhenghan; Chen, Fei; Xiong, Xiang; Peng, Ruwen; Wang, Mu

2017-05-01

Manipulating the propagation of surface plasmons (SPs) on a nanoscale is a fundamental issue of nanophotonics. By using focused electron beam, SPs can be excited with high spatial accuracy. Here we report on the propagation of SPs on a chain of gold nanodisks with cathodoluminescence (CL) spectroscopy. Experimental evidence for the propagation of SPs excited by the focused electron beam is demonstrated. The wavelength of the transmitted SPs depends on the geometrical parameters of the nanodisk chain. Furthermore, we design and fabricate a beam splitter, which selectively transmits SPs of certain wavelengths to a specific direction. By scanning the sample surface point by point and collecting the CL spectra, we obtain the spectral mapping and identify that the chain of the smaller nanodisks can efficiently transport SPs at shorter wavelengths. This Letter provides a unique approach to manipulate in-plane propagation of SPs.

An Immunization Strategy Based on Propagation Mechanism

Directory of Open Access Journals (Sweden)

Yixin Zhu

2014-01-01

Full Text Available With the ubiquity of smart phones, wearable equipment, and wireless sensors, the topologies of networks composed by them change along with time. The immunization strategies in which network immune nodes are chosen by analyzing the static aggregation network topologies have been challenged. The studies about interaction propagations between two pathogens show that the interaction can change propagation threshold and the final epidemic size of each other, which provides a new thinking of immunization method. The eradication or inhibition of the virus can be achieved through the spread of its opposite party. Here, we put forward an immunization strategy whose implementation does not depend on the analysis of network topology. The immunization agents are randomly placed on a few of individuals of network and spread out from these individuals on network in a propagation method. The immunization agents prevent virus infecting their habitat nodes with certain immune success rate. The analysis and simulation of evolution equation of the model show that immune propagation has a significant impact on the spread threshold and steady-state density of virus on a finite size of BA networks. Simulations on some real-world networks also suggest that the immunization strategy is feasible and effective.

Coherently Enhanced Wireless Power Transfer

Science.gov (United States)

Krasnok, Alex; Baranov, Denis G.; Generalov, Andrey; Li, Sergey; Alù, Andrea

2018-04-01

Extraction of electromagnetic energy by an antenna from impinging external radiation is at the basis of wireless communications and wireless power transfer (WPT). The maximum of transferred energy is ensured when the antenna is conjugately matched, i.e., when it is resonant and it has an equal coupling with free space and its load. This condition, however, can be easily affected by changes in the environment, preventing optimal operation of a WPT system. Here, we introduce the concept of coherently enhanced WPT that allows us to bypass this difficulty and achieve dynamic control of power transfer. The approach relies on coherent excitation of the waveguide connected to the antenna load with a backward propagating signal of specific amplitude and phase. This signal creates a suitable interference pattern at the load resulting in a modification of the local wave impedance, which in turn enables conjugate matching and a largely increased amount of extracted energy. We develop a simple theoretical model describing this concept, demonstrate it with full-wave numerical simulations for the canonical example of a dipole antenna, and verify experimentally in both near-field and far-field regimes.

A Survey of Routing Issues and Associated Protocols in Underwater Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Muhammad Khalid

2017-01-01

Full Text Available Underwater wireless sensor networks are a newly emerging wireless technology in which small size sensors with limited energy and limited memory and bandwidth are deployed in deep sea water and various monitoring operations like tactical surveillance, environmental monitoring, and data collection are performed through these tiny sensors. Underwater wireless sensor networks are used for the exploration of underwater resources, oceanographic data collection, flood or disaster prevention, tactical surveillance systems, and unmanned underwater vehicles. Sensor nodes consist of a small memory, a central processing unit, and an antenna. Underwater networks are much different from terrestrial sensor networks as radio waves cannot be used in underwater wireless sensor networks. Acoustic channels are used for communication in deep sea water. Acoustic signals have many limitations, such as limited bandwidth, higher end-to-end delay, network path loss, higher propagation delay, and dynamic topology. Usually, these limitations result in higher energy consumption with a smaller number of packets delivered. The main aim nowadays is to operate sensor nodes having a smaller battery for a longer time in the network. This survey has discussed the state-of-the-art localization based and localization-free routing protocols. Routing associated issues in the area of underwater wireless sensor networks have also been discussed.

Distributed estimation based on observations prediction in wireless sensor networks

KAUST Repository

Bouchoucha, Taha

2015-03-19

We consider wireless sensor networks (WSNs) used for distributed estimation of unknown parameters. Due to the limited bandwidth, sensor nodes quantize their noisy observations before transmission to a fusion center (FC) for the estimation process. In this letter, the correlation between observations is exploited to reduce the mean-square error (MSE) of the distributed estimation. Specifically, sensor nodes generate local predictions of their observations and then transmit the quantized prediction errors (innovations) to the FC rather than the quantized observations. The analytic and numerical results show that transmitting the innovations rather than the observations mitigates the effect of quantization noise and hence reduces the MSE. © 2015 IEEE.

RF and microwave engineering fundamentals of wireless communications

CERN Document Server

Gustrau, Frank

2012-01-01

This book provides a fundamental and practical introduction to radio frequency and microwave engineering and physical aspects of wireless communication In this book, the author addresses a wide range of radio-frequency and microwave topics with emphasis on physical aspects including EM and voltage waves, transmission lines, passive circuits, antennas, radio wave propagation. Up-to-date RF design tools like RF circuit simulation, EM simulation and computerized smith charts, are used in various examples to demonstrate how these methods can be applied effectively in RF engineering

Credit Card Debt Hardship Letter Samples

OpenAIRE

lissa coffey

2016-01-01

Having trouble with your credit card debt? Below you will find examples of hardship letters. There are several things to consider when writing a credit card hardship letter. A hardship letter is the first step to letting the credit card company know that things are bad. This free credit card hardship letter sample is only a guide in order to start the negotiation. Credit card debt hardship letter example, hardship letter to credit card. If you are having trouble paying off your debt and need ...

Critical contrastive rhetoric: The influence of L2 letter writing instruction on L1letter writing

Directory of Open Access Journals (Sweden)

Mehrnoosh Fakharzadeh

2014-08-01

Full Text Available The present study employed critical contrastive rhetoric to investigate the L2 to L1 transfer of organizational pattern and directness level of speech acts in business complaint letters. By examining the L1 complaint letters of 30 tourism university students in two phases of study, pre and post instruction of English complaint letter, the study revealed that the rhetorical organization of Persian letters are in a state of hybridity. The post instruction comparison of letters, however, showed a tendency towards applying English conventions both in organization and directness level of complaint speech act in the L1 complaint letters. The results also revealed that after instruction the expert in the field of tourism viewed some letters as inappropriate in terms of politeness which is reflected through some lexical items.

A Letter to Ahmad Khan

Directory of Open Access Journals (Sweden)

I.M. Mirgaleev

2016-12-01

Full Text Available We bring to attention of specialists an undated letter of Ottoman ruler Mehmed II Fatih to the Great Horde khan Ahmad from the collection of famous collector of Ottoman charters Feridun-bey [1, S. 289]. The addressee is the famous ruler of the Great Horde, khan Ahmad. Daulat Khan mentioned in the letter is Nur-Davlet. He was connected with khan Ahmad, and, as indicated by the letter, he had also set in close contact with the Ottomans whose ruler openly declares in a letter that “our sight of benevolence and patronage is directed toward him”. Thereby the Sultan made it clear to the “principal” Tatar khan Akhmad that Nur-Davlet was under the patronage of the Ottoman Empire. Considering the period of activity of Nur-Davlet in Crimea, presumably the letter was written in 1477. Famous researcher of the Crimean Khanate V.D. Smirnov had already examined the letter and the question of why Ahmad Khan was named the Crimean khan in the title of the letter [2, p. 221–222].

Optimizing wireless LAN for longwall coal mine automation

Energy Technology Data Exchange (ETDEWEB)

Hargrave, C.O.; Ralston, J.C.; Hainsworth, D.W. [Exploration & Mining Commonwealth Science & Industrial Research Organisation, Pullenvale, Qld. (Australia)

2007-01-15

A significant development in underground longwall coal mining automation has been achieved with the successful implementation of wireless LAN (WLAN) technology for communication on a longwall shearer. WIreless-FIdelity (Wi-Fi) was selected to meet the bandwidth requirements of the underground data network, and several configurations were installed on operating longwalls to evaluate their performance. Although these efforts demonstrated the feasibility of using WLAN technology in longwall operation, it was clear that new research and development was required in order to establish optimal full-face coverage. By undertaking an accurate characterization of the target environment, it has been possible to achieve great improvements in WLAN performance over a nominal Wi-Fi installation. This paper discusses the impact of Fresnel zone obstructions and multipath effects on radio frequency propagation and reports an optimal antenna and system configuration. Many of the lessons learned in the longwall case are immediately applicable to other underground mining operations, particularly wherever there is a high degree of obstruction from mining equipment.

Subsurface Event Detection and Classification Using Wireless Signal Networks

Directory of Open Access Journals (Sweden)

Muhannad T. Suleiman

2012-11-01

Full Text Available Subsurface environment sensing and monitoring applications such as detection of water intrusion or a landslide, which could significantly change the physical properties of the host soil, can be accomplished using a novel concept, Wireless Signal Networks (WSiNs. The wireless signal networks take advantage of the variations of radio signal strength on the distributed underground sensor nodes of WSiNs to monitor and characterize the sensed area. To characterize subsurface environments for event detection and classification, this paper provides a detailed list and experimental data of soil properties on how radio propagation is affected by soil properties in subsurface communication environments. Experiments demonstrated that calibrated wireless signal strength variations can be used as indicators to sense changes in the subsurface environment. The concept of WSiNs for the subsurface event detection is evaluated with applications such as detection of water intrusion, relative density change, and relative motion using actual underground sensor nodes. To classify geo-events using the measured signal strength as a main indicator of geo-events, we propose a window-based minimum distance classifier based on Bayesian decision theory. The window-based classifier for wireless signal networks has two steps: event detection and event classification. With the event detection, the window-based classifier classifies geo-events on the event occurring regions that are called a classification window. The proposed window-based classification method is evaluated with a water leakage experiment in which the data has been measured in laboratory experiments. In these experiments, the proposed detection and classification method based on wireless signal network can detect and classify subsurface events.

Letter Knowledge in Parent–Child Conversations

Science.gov (United States)

Robins, Sarah; Treiman, Rebecca; Rosales, Nicole

2014-01-01

Learning about letters is an important component of emergent literacy. We explored the possibility that parent speech provides information about letters, and also that children’s speech reflects their own letter knowledge. By studying conversations transcribed in CHILDES (MacWhinney, 2000) between parents and children aged one to five, we found that alphabetic order influenced use of individual letters and letter sequences. The frequency of letters in children’s books influenced parent utterances throughout the age range studied, but children’s utterances only after age two. Conversations emphasized some literacy-relevant features of letters, such as their shapes and association with words, but not letters’ sounds. Describing these patterns and how they change over the preschool years offers important insight into the home literacy environment. PMID:25598577

Energy-efficient digital and wireless IC design for wireless smart sensing

Science.gov (United States)

Zhou, Jun; Huang, Xiongchuan; Wang, Chao; Tae-Hyoung Kim, Tony; Lian, Yong

2017-10-01

Wireless smart sensing is now widely used in various applications such as health monitoring and structural monitoring. In conventional wireless sensor nodes, significant power is consumed in wirelessly transmitting the raw data. Smart sensing adds local intelligence to the sensor node and reduces the amount of wireless data transmission via on-node digital signal processing. While the total power consumption is reduced compared to conventional wireless sensing, the power consumption of the digital processing becomes as dominant as wireless data transmission. This paper reviews the state-of-the-art energy-efficient digital and wireless IC design techniques for reducing the power consumption of the wireless smart sensor node to prolong battery life and enable self-powered applications.

Letter-transposition effects are not universal: The impact of transposing letters in Hebrew.

Science.gov (United States)

Velan, Hadas; Frost, Ram

2009-10-01

We examined the effects of letter transposition in Hebrew in three masked-priming experiments. Hebrew, like English has an alphabetic orthography where sequential and contiguous letter strings represent phonemes. However, being a Semitic language it has a non-concatenated morphology that is based on root derivations. Experiment 1 showed that transposed-letter (TL) root primes inhibited responses to targets derived from the non-transposed root letters, and that this inhibition was unrelated to relative root frequency. Experiment 2 replicated this result and showed that if the transposed letters of the root created a nonsense-root that had no lexical representation, then no inhibition and no facilitation were obtained. Finally, Experiment 3 demonstrated that in contrast to English, French, or Spanish, TL nonword primes did not facilitate recognition of targets, and when the root letters embedded in them consisted of a legal root morpheme, they produced inhibition. These results suggest that lexical space in alphabetic orthographies may be structured very differently in different languages if their morphological structure diverges qualitatively. In Hebrew, lexical space is organized according to root families rather than simple orthographic structure, so that all words derived from the same root are interconnected or clustered together, independent of overall orthographic similarity.

Entropy Rate of Time-Varying Wireless Networks

DEFF Research Database (Denmark)

Cika, Arta; Badiu, Mihai Alin; Coon, Justin P.

2018-01-01

In this paper, we present a detailed framework to analyze the evolution of the random topology of a time-varying wireless network via the information theoretic notion of entropy rate. We consider a propagation channel varying over time with random node positions in a closed space and Rayleigh...... fading affecting the connections between nodes. The existence of an edge between two nodes at given locations is modeled by a Markov chain, enabling memory effects in network dynamics. We then derive a lower and an upper bound on the entropy rate of the spatiotemporal network. The entropy rate measures...

Markovian agents models for wireless sensor networks deployed in environmental protection

International Nuclear Information System (INIS)

Cerotti, Davide; Gribaudo, Marco; Bobbio, Andrea

2014-01-01

Wireless sensor networks (WSNs) are gaining popularity as distributed monitoring systems in safety critical applications, when the location to be controlled may be dangerous for a human operator or difficult to access. Fire is one of the major thread in urban as well as in open environments, and WSNs are receiving increasing attention as a mean to build effective and timely fire protection systems. The present paper presents a novel analytical technique for the study of the propagation of a fire in a wide open area and the interaction with a WSN deployed to monitor the outbreak of the fire and to send a warning signal to a base station. For the complex scenario under study, an analytical modeling and analysis technique based on Markovian agents (MAs) is discussed. It is shown that, even if the overall state space of the models is huge, nevertheless an analytical solution is feasible, by exploiting the locality of the interactions among MAs, based on a message passing mechanism combined with a perception function. - Highlights: • We present a revised theory of Markovian agent models, detailing the analysis techniques and its complexity • We a target a complex application of a wireless sensor network (WSN) that monitors forest fire. • The model captures the propagation of fire, heat, and the detection by the WSN. • We compute key performance indices such us the fire propagation front, and message travel time. • We perform an extensive set of experiments to study the effectiveness of the WSN in detecting forest fire

Effects of wireless packet loss in industrial process control systems.

Science.gov (United States)

Liu, Yongkang; Candell, Richard; Moayeri, Nader

2017-05-01

Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100% reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100% reliable communications. The sensitivity of the

Wireless device monitoring methods, wireless device monitoring systems, and articles of manufacture

Science.gov (United States)

McCown, Steven H [Rigby, ID; Derr, Kurt W [Idaho Falls, ID; Rohde, Kenneth W [Idaho Falls, ID

2012-05-08

Wireless device monitoring methods, wireless device monitoring systems, and articles of manufacture are described. According to one embodiment, a wireless device monitoring method includes accessing device configuration information of a wireless device present at a secure area, wherein the device configuration information comprises information regarding a configuration of the wireless device, accessing stored information corresponding to the wireless device, wherein the stored information comprises information regarding the configuration of the wireless device, comparing the device configuration information with the stored information, and indicating the wireless device as one of authorized and unauthorized for presence at the secure area using the comparing.

Overt use of a tactile-kinesthetic strategy shifts to covert processing in rehabilitation of letter-by-letter reading.

Science.gov (United States)

Lott, Susan Nitzberg; Carney, Aimee Syms; Glezer, Laurie S; Friedman, Rhonda B

2010-11-01

BACKGROUND: Letter-by-letter readers identify each letter of the word they are reading serially in left to right order before recognizing the word. When their letter naming is also impaired, letter-by-letter reading is inaccurate and can render even single word reading very poor. Tactile and/or kinesthetic strategies have been reported to improve reading in these patients, but only under certain conditions or for a limited set of stimuli. AIMS: The primary aim of the current study was to determine whether a tactile/kinesthetic treatment could significantly improve reading specifically under normal reading conditions, i.e. reading untrained words presented in free vision and read without overt use of the strategy. METHODS #ENTITYSTARTX00026; PROCEDURES: Three chronic letter-by-letter readers participated in a tactile/kinesthetic treatment aimed at first improving letter naming accuracy (phase 1) and then letter-by-letter reading speed (phase 2). In a multiple case series design, accuracy and speed of reading untrained words without overt use of the trained tactile/kinesthetic strategy was assessed before phase 1, after phase 1 and again after phase 2. OUTCOMES #ENTITYSTARTX00026; RESULTS: All three patients significantly improved both their speed and accuracy reading untrained words without overt use of the trained tactile/kinesthetic strategy. All three patients required the additional practice in phase 2 to achieve significant improvement. Treatment did not target sentence level reading, yet two of the three patients became so adept that they could read entire sentences. CONCLUSIONS: This study replicates previous findings on the efficacy of tactile/kinesthetic treatment for letter-by-letter readers with poor letter naming. It further demonstrates that this treatment can alter cognitive processing such that words never specifically trained can be read in free vision without overtly using the trained strategy. The data suggest that an important element in achieving

Wireless mesh networks.

Science.gov (United States)

Wang, Xinheng

2008-01-01

Wireless telemedicine using GSM and GPRS technologies can only provide low bandwidth connections, which makes it difficult to transmit images and video. Satellite or 3G wireless transmission provides greater bandwidth, but the running costs are high. Wireless networks (WLANs) appear promising, since they can supply high bandwidth at low cost. However, the WLAN technology has limitations, such as coverage. A new wireless networking technology named the wireless mesh network (WMN) overcomes some of the limitations of the WLAN. A WMN combines the characteristics of both a WLAN and ad hoc networks, thus forming an intelligent, large scale and broadband wireless network. These features are attractive for telemedicine and telecare because of the ability to provide data, voice and video communications over a large area. One successful wireless telemedicine project which uses wireless mesh technology is the Emergency Room Link (ER-LINK) in Tucson, Arizona, USA. There are three key characteristics of a WMN: self-organization, including self-management and self-healing; dynamic changes in network topology; and scalability. What we may now see is a shift from mobile communication and satellite systems for wireless telemedicine to the use of wireless networks based on mesh technology, since the latter are very attractive in terms of cost, reliability and speed.

Design of an Omnidirectional Multibeam Transmitter for High-Speed Indoor Wireless Communications

Directory of Open Access Journals (Sweden)

Tang Jaw-Luen

2010-01-01

Full Text Available For future high speed indoor wireless communication, diffuse wireless optical communications offer more robust optical links against shadowing than line-of-sight links. However, their performance may be degraded by multipath dispersion arising from surface reflections. We have developed a multipath diffusive propagation model capable of providing channel impulse responses data. It is aimed to design and simulate any multibeam transmitter under a variety of indoor environments. In this paper, a multi-beam transmitter system associated with hemisphere structure is proposed to fight against the diverse effects of multipath distortion albeit, at the cost of increased laser power and cost. Simulation results of multiple impulse responses showed that this type of multi-beam transmitter can significantly improve the performance of BER suitable for high bit rate application. We present the performance and simulation results for both line-of-sight and diffuse link configurations. We propose a design of power radiation pattern for a transmitter in achieving uniform and full coverage of power distributions for diffuse indoor optical wireless systems.

Writing more informative letters of reference.

Science.gov (United States)

Wright, Scott M; Ziegelstein, Roy C

2004-05-01

Writing a meaningful and valuable letter of reference is not an easy task. Several factors influence the quality of any letter of reference. First, the accuracy and reliability of the writer's impressions and judgment depend on how well he knows the individual being described. Second, the writer's frame of reference, which is determined by the number of persons at the same level that he has worked with, will impact the context and significance of his beliefs and estimations. Third, the letter-writing skills of the person composing the letter will naturally affect the letter. To support the other components of a candidate's application, a letter of reference should provide specific examples of how an individual's behavior or attitude compares to a reference group and should assess "intangibles" that are hard to glean from a curriculum vitae or from test scores. This report offers suggestions that should help physicians write more informative letters of reference.

Letters From Peplau.

Science.gov (United States)

Peden, Ann R

2018-03-01

Dr. Hildegard Peplau, considered to be our first modern Nurse theorist and the Mother of Psychiatric Nursing, was a prolific writer, engaging in correspondence with colleagues and students who sought her professional and theoretical expertise. Through these letters, she influenced psychiatric nursing while maintaining a broad international network of professional colleagues. An analysis of letters, written between 1990 and 1998, provides insights into Peplau's last decade of professional life and a model of how to support the next generation of nurse scholars. Using content analysis, 24 letters received between 1990 and 1998 were read, reread, and coded. Recurring themes were identified. Three themes were identified. These include Peplau, the Person: Living a Life of Professional Balance; Lighting a Spark: Investing in the Next Generation; and Work in the Vineyards of Nursing: Maintaining a Life of Scholarship. The letters depict Peplau's keen intellect, her wide professional network, her leisure time spent with family and friends, and her own work to assure that her theoretical legacy continued. Peplau's insights continue to be relevant as psychiatric mental health nursing leaders engage in activities to support the next generation of scholars and leaders.

Study on the Effect of Frequency on Conductivity of Underground Strata in Coal Mine Through-the-earth Wireless Communication

Directory of Open Access Journals (Sweden)

Jinyi TAO

2014-09-01

Full Text Available The relationship of conductivity and the frequency, which is of decisive significance in through-the-earth wireless communication in coal mine, is closely related to the options of frequency range in coal mine wireless communication. When through-the-earth wireless communication is applied, the electromagnetic waves need to spread in the semi-conductive medium rocks. The main factors affecting the electromagnetic wave propagation in rocks is the rock strata electromagnetic parameters. These parameters are magnetic permeability m (H/m, dielectric constant e (F/m and electrical conductivity s (S/m. In these parameters, electrical conductivity is not constant. Under the influence of various factors, it will be great changes. This paper, for the specific circumstances of coal mine rock, discuses and conduct dada mining the effect frequency on the electrical conductivity of underground rock in coal mine with through-the-earth wireless communication.

Wireless virtualization

CERN Document Server

Wen, Heming; Le-Ngoc, Tho

2013-01-01

This SpringerBriefs is an overview of the emerging field of wireless access and mobile network virtualization. It provides a clear and relevant picture of the current virtualization trends in wireless technologies by summarizing and comparing different architectures, techniques and technologies applicable to a future virtualized wireless network infrastructure. The readers are exposed to a short walkthrough of the future Internet initiative and network virtualization technologies in order to understand the potential role of wireless virtualization in the broader context of next-generation ubiq

The legibility of letters and words

DEFF Research Database (Denmark)

Beier, Sofie

2016-01-01

The saying made famous by Mathew Carter that "type is a beautiful group of letters, not a group of beautiful letters”, highlights the fact that although a typeface consists of a number of letters it is when the letters are assembled in a word that they become type. However, research indicates...... that what makes letters legible in isolation is not necessarily the same as what makes them legible in words. Is it possible to create a typeface where both letters and words have a high level of legibility or are those factors so different that they cannot be combined? Through a literature review...... on relevant experimental investigations, I will in this talk present examples of when the legibility findings on letters and words correlate and when they differ....

Bifurcation Analysis for an SEIRS-V Model with Delays on the Transmission of Worms in a Wireless Sensor Network

Directory of Open Access Journals (Sweden)

Zizhen Zhang

2017-01-01

Full Text Available Hopf bifurcation for an SEIRS-V model with delays on the transmission of worms in a wireless sensor network is investigated. We focus on existence of the Hopf bifurcation by regarding the diverse delay as a bifurcation parameter. The results show that propagation of worms in the wireless sensor network can be controlled when the delay is suitably small under some certain conditions. Then, we study properties of the Hopf bifurcation by using the normal form theory and center manifold theorem. Finally, we give a numerical example to support the theoretical results.

Can "CANISO" Activate "CASINO"? Transposed-Letter Similarity Effects with Nonadjacent Letter Positions

Science.gov (United States)

Perea, Manuel; Lupker, Stephen J.

2004-01-01

Nonwords created by transposing two "adjacent" letters (i.e., transposed-letter (TL) nonwords like "jugde") are very effective at activating the lexical representation of their base words. This fact poses problems for most computational models of word recognition (e.g., the interactive-activation model and its extensions), which assume that exact…

Geometry on the parameter space of the belief propagation algorithm on Bayesian networks

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Yodai [National Institute of Informatics, Research Organization of Information and Systems, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430 (Japan); Laboratory for Mathematical Neuroscience, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)

2006-01-30

This Letter considers a geometrical structure on the parameter space of the belief propagation algorithm on Bayesian networks. The statistical manifold of posterior distributions is introduced, and the expression for the information metric on the manifold is derived. The expression is used to construct a cost function which can be regarded as a measure of the distance in the parameter space.

Wireless Biological Electronic Sensors.

Science.gov (United States)

Cui, Yue

2017-10-09

The development of wireless biological electronic sensors could open up significant advances for both fundamental studies and practical applications in a variety of areas, including medical diagnosis, environmental monitoring, and defense applications. One of the major challenges in the development of wireless bioelectronic sensors is the successful integration of biosensing units and wireless signal transducers. In recent years, there are a few types of wireless communication systems that have been integrated with biosensing systems to construct wireless bioelectronic sensors. To successfully construct wireless biological electronic sensors, there are several interesting questions: What types of biosensing transducers can be used in wireless bioelectronic sensors? What types of wireless systems can be integrated with biosensing transducers to construct wireless bioelectronic sensors? How are the electrical sensing signals generated and transmitted? This review will highlight the early attempts to address these questions in the development of wireless biological electronic sensors.

The short-term effects of antenna insulation thickness on path losses in wireless telemetry implants at microwave frequencies

Directory of Open Access Journals (Sweden)

Lukas Kneisz

2013-07-01

Full Text Available Various physiological parameters can be monitored non-invasively using wireless biotelemetry links. The development of sophisticated ultra low power consuming transceivers allows the transmission of large amounts of data from the inside of the body to an external receiver in real time at microwave frequencies.Antenna impedance matching is crucial for obtaining an acceptable propagation link budget in a wireless telemetry link. The dielectric properties of biological tissue induce detuning to transceiver antennas when implanted into the body. To counteract detuning problems, implant antennas are coated with biocompatible insulating material. The study investigates the propagation losses of a wireless communication link at different insulation thicknesses of medical grade silicone in the Industrial-Scientific-Medical (ISM radio band at 2.45 GHz. The wireless link consisted of an implantable unit which was placed between two pads of tissue substitute material and an external receiver which was connected to a laptop. Predefined data packets were transmitted from the implant, the received packets were analyzed, packet errors and packet losses were logged and the received signal strength indicator values (RSSI were recorded. Our results showed that the mean RSSI values of insulated transmitter antennas - embedded in tissue equivalent material - provide more safety distance to critical receiver sensitivity level than uncoated antennas.The conducted measurements let us conclude that with increasing thickness of the insulation layer, the antenna becomes less sensitive to detuning by adjacent tissue substitute material. Therefore tuned antennas are less influenced by the surrounding tissue after implantation.

Sequential Uniformly Reweighted Sum-Product Algorithm for Cooperative Localization in Wireless Networks

OpenAIRE

Li, Wei; Yang, Zhen; Hu, Haifeng

2014-01-01

Graphical models have been widely applied in solving distributed inference problems in wireless networks. In this paper, we formulate the cooperative localization problem in a mobile network as an inference problem on a factor graph. Using a sequential schedule of message updates, a sequential uniformly reweighted sum-product algorithm (SURW-SPA) is developed for mobile localization problems. The proposed algorithm combines the distributed nature of belief propagation (BP) with the improved p...

Wireless data transfer in saliniferous formations; Kabellose Datenuebertragung im Salinar

Energy Technology Data Exchange (ETDEWEB)

Wilsnack, T.; Grafe, F. [IBeWa-Ingenieurpartnerschaft, Freiberg (Germany); Roessel, A. [RCS-Technik, Freiberg (Germany)

2012-07-01

The metrological surveillance of processes and long-term monitoring is an important requirement for closed mines or radioactive waste repositories. The available measuring technology is usually based on electrical power supply using existing underground power network. This is in contradiction with the targeted sealing of the monitored mine caverns and/or the integrity of hydraulic barriers. The authors developed a concept of wireless data transfer based on the radio wave propagation in mostly dry saliniferous formations. The system was tests at several reference sites.

Cognitive Security of Wireless Communication Systems in the Physical Layer

Directory of Open Access Journals (Sweden)

Mustafa Harun Yılmaz

2017-01-01

Full Text Available While the wireless communication systems provide the means of connectivity nearly everywhere and all the time, communication security requires more attention. Even though current efforts provide solutions to specific problems under given circumstances, these methods are neither adaptive nor flexible enough to provide security under the dynamic conditions which make the security breaches an important concern. In this paper, a cognitive security (CS concept for wireless communication systems in the physical layer is proposed with the aim of providing a comprehensive solution to wireless security problems. The proposed method will enable the comprehensive security to ensure a robust and reliable communication in the existence of adversaries by providing adaptive security solutions in the communication systems by exploiting the physical layer security from different perspective. The adaptiveness relies on the fact that radio adapts its propagation characteristics to satisfy secure communication based on specific conditions which are given as user density, application specific adaptation, and location within CS concept. Thus, instead of providing any type of new security mechanism, it is proposed that radio can take the necessary precautions based on these conditions before the attacks occur. Various access scenarios are investigated to enable the CS while considering these conditions.

Performance of a TV white space database with different terrain resolutions and propagation models

Directory of Open Access Journals (Sweden)

A. M. Fanan

2017-11-01

Full Text Available Cognitive Radio has now become a realistic option for the solution of the spectrum scarcity problem in wireless communication. TV channels (the primary user can be protected from secondary-user interference by accurate prediction of TV White Spaces (TVWS by using appropriate propagation modelling. In this paper we address two related aspects of channel occupancy prediction for cognitive radio. Firstly we investigate the best combination of empirical propagation model and spatial resolution of terrain data for predicting TVWS by examining the performance of three propagation models (Extended-Hata, Davidson-Hata and Egli in the TV band 470 to 790 MHz along with terrain data resolutions of 1000, 100 and 30 m, when compared with a comprehensive set of propagation measurements taken in randomly-selected locations around Hull, UK. Secondly we describe how such models can be integrated into a database-driven tool for cognitive radio channel selection within the TVWS environment.

Flexible quality of service model for wireless body area sensor networks.

Science.gov (United States)

Liao, Yangzhe; Leeson, Mark S; Higgins, Matthew D

2016-03-01

Wireless body area sensor networks (WBASNs) are becoming an increasingly significant breakthrough technology for smart healthcare systems, enabling improved clinical decision-making in daily medical care. Recently, radio frequency ultra-wideband technology has developed substantially for physiological signal monitoring due to its advantages such as low-power consumption, high transmission data rate, and miniature antenna size. Applications of future ubiquitous healthcare systems offer the prospect of collecting human vital signs, early detection of abnormal medical conditions, real-time healthcare data transmission and remote telemedicine support. However, due to the technical constraints of sensor batteries, the supply of power is a major bottleneck for healthcare system design. Moreover, medium access control (MAC) needs to support reliable transmission links that allow sensors to transmit data safely and stably. In this Letter, the authors provide a flexible quality of service model for ad hoc networks that can support fast data transmission, adaptive schedule MAC control, and energy efficient ubiquitous WBASN networks. Results show that the proposed multi-hop communication ad hoc network model can balance information packet collisions and power consumption. Additionally, wireless communications link in WBASNs can effectively overcome multi-user interference and offer high transmission data rates for healthcare systems.

ERP correlates of letter identity and letter position are modulated by lexical frequency

Science.gov (United States)

Vergara-Martínez, Marta; Perea, Manuel; Gómez, Pablo; Swaab, Tamara Y.

2013-01-01

The encoding of letter position is a key aspect in all recently proposed models of visual-word recognition. We analyzed the impact of lexical frequency on letter position assignment by examining the temporal dynamics of lexical activation induced by pseudowords extracted from words of different frequencies. For each word (e.g., BRIDGE), we created two pseudowords: A transposed-letter (TL: BRIGDE) and a replaced-letter pseudoword (RL: BRITGE). ERPs were recorded while participants read words and pseudowords in two tasks: Semantic categorization (Experiment 1) and lexical decision (Experiment 2). For high-frequency stimuli, similar ERPs were obtained for words and TL-pseudowords, but the N400 component to words was reduced relative to RL-pseudowords, indicating less lexical/semantic activation. In contrast, TL- and RL-pseudowords created from low-frequency stimuli elicited similar ERPs. Behavioral responses in the lexical decision task paralleled this asymmetry. The present findings impose constraints on computational and neural models of visual-word recognition. PMID:23454070

The letter knowledge assessment tool.

Science.gov (United States)

Pedro, Cassandra; Lousada, Marisa; Pereira, Rita; Hall, Andreia; Jesus, Luis M T

2017-10-10

There is a need to develop letter knowledge assessment tools to characterise the letter knowledge in Portuguese pre-schoolers and to compare it with pre-schoolers from other countries, but there are no tools for this purpose in Portugal. The aim of this paper is to describe the development and validation procedures of the Prova de Avaliação de Competências de Pré-Literacia (PACPL), which assesses letter knowledge. This study includes data that has been gathered in two phases: pilot and main study. In the pilot study, an expert panel of six speech and language pathologists analysed the instrument. Children (n = 216) aged 5;0-7;11 participated in the main study that reports data related to the psychometric characteristics of the PACPL. Content validity, internal consistency, reliability and contributing factors to performance were examined statistically. A modified Bland-Altman method revealed good agreement amongst evaluators. The main study showed that the PACPL has a very good internal consistency and high inter-rater (96.2% of agreement and a Cohen's k value of 0.92) and intra-rater (95.6% of agreement and a Cohen's k value of 0.91) agreement. Construct validity of the PCAPL was also assured (Cronbach's α of 0.982). Significant differences were found between age groups with children increasing their letter knowledge with age. In addition, they were better at identifying than at producing both letter names and letter sounds. The PACPL is a valid and reliable instrument to assess letter knowledge in Portuguese children.

An Energy-Efficient Underground Localization System Based on Heterogeneous Wireless Networks

Science.gov (United States)

Yuan, Yazhou; Chen, Cailian; Guan, Xinping; Yang, Qiuling

2015-01-01

A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners' should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on high speed Industrial Ethernet is deployed. Since the mobile wireless nodes are working in an irregular tunnel, a specific wireless propagation model cannot fit all situations. In this paper, an underground localization system is designed to enable the adaptation to kinds of harsh tunnel environments, but also to reduce the energy consumption and thus prolong the lifetime of the network. Three key techniques are developed and implemented to improve the system performance, including a step counting algorithm with accelerometers, a power control algorithm and an adaptive packets scheduling scheme. The simulation study and experimental results show the effectiveness of the proposed algorithms and the implementation. PMID:26016918

Evaluation of Deployment Challenges of Wireless Sensor Networks at Signalized Intersections

Directory of Open Access Journals (Sweden)

Leyre Azpilicueta

2016-07-01

Full Text Available With the growing demand of Intelligent Transportation Systems (ITS for safer and more efficient transportation, research on and development of such vehicular communication systems have increased considerably in the last years. The use of wireless networks in vehicular environments has grown exponentially. However, it is highly important to analyze radio propagation prior to the deployment of a wireless sensor network in such complex scenarios. In this work, the radio wave characterization for ISM 2.4 GHz and 5 GHz Wireless Sensor Networks (WSNs deployed taking advantage of the existence of traffic light infrastructure has been assessed. By means of an in-house developed 3D ray launching algorithm, the impact of topology as well as urban morphology of the environment has been analyzed, emulating the realistic operation in the framework of the scenario. The complexity of the scenario, which is an intersection city area with traffic lights, vehicles, people, buildings, vegetation and urban environment, makes necessary the channel characterization with accurate models before the deployment of wireless networks. A measurement campaign has been conducted emulating the interaction of the system, in the vicinity of pedestrians as well as nearby vehicles. A real time interactive application has been developed and tested in order to visualize and monitor traffic as well as pedestrian user location and behavior. Results show that the use of deterministic tools in WSN deployment can aid in providing optimal layouts in terms of coverage, capacity and energy efficiency of the network.

Letter-Transposition Effects Are Not Universal: The Impact of Transposing Letters in Hebrew

Science.gov (United States)

Velan, Hadas; Frost, Ram

2009-01-01

We examined the effects of letter-transposition in Hebrew in three masked-priming experiments. Hebrew, like English has an alphabetic orthography where sequential and contiguous letter strings represent phonemes. However, being a Semitic language it has a non-concatenated morphology that is based on root derivations. Experiment 1 showed that…

7 CFR 3560.709 - Demand letter.

Science.gov (United States)

2010-01-01

... 7 Agriculture 15 2010-01-01 2010-01-01 false Demand letter. 3560.709 Section 3560.709 Agriculture... DIRECT MULTI-FAMILY HOUSING LOANS AND GRANTS Unauthorized Assistance § 3560.709 Demand letter. (a) If a... repayment schedule, the Agency will send the borrower a demand letter specifying: (1) The amount of...

Letters of Map Change (LOMC)

Data.gov (United States)

Department of Homeland Security — Documents, including different types of Letters of MAP Revision (LOMR) and Letters of Map Amendment (LOMA), which are issued by FEMA to revise or amend the flood...

The Wireless ATM Architecture

Directory of Open Access Journals (Sweden)

R. Palitefka

1998-06-01

Full Text Available An overview of the proposed wireless ATM structure is provided. Wireless communication have been developed to a level where offered services can now be extended beyond voice and data. There are already wireless LANs, cordless systems offering data services and mobile data. Wireless LAN systems are basically planned for local, on-promises and in-house networking providing short distance radio or infrared links between computer system. The main challenge of wireless ATM is to harmonise the development of broadband wireless system with service B -ISDN/ATM and ATM LANs, and offer multimedia multiservice features for the support of time-sensitive voice communication, video, desktop multimedia applications, and LAN data traffic for the wireless user.

A hybrid stochastic approach for self-location of wireless sensors in indoor environments.

Science.gov (United States)

Lloret, Jaime; Tomas, Jesus; Garcia, Miguel; Canovas, Alejandro

2009-01-01

Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location estimation because of the issues arising in the indoor environment. Two different approaches had been proposed using WLAN location systems: on the one hand, the so-called deductive methods take into account the physical properties of signal propagation. These systems require a propagation model, an environment map, and the position of the radio-stations. On the other hand, the so-called inductive methods require a previous training phase where the system learns the received signal strength (RSS) in each location. This phase can be very time consuming. This paper proposes a new stochastic approach which is based on a combination of deductive and inductive methods whereby wireless sensors could determine their positions using WLAN technology inside a floor of a building. Our goal is to reduce the training phase in an indoor environment, but, without an loss of precision. Finally, we compare the measurements taken using our proposed method in a real environment with the measurements taken by other developed systems. Comparisons between the proposed system and other hybrid methods are also provided.

Implementation and Analysis of ISM 2.4 GHz Wireless Sensor Network Systems in Judo Training Venues.

Science.gov (United States)

Lopez-Iturri, Peio; Aguirre, Erik; Azpilicueta, Leyre; Astrain, José Javier; Villadangos, Jesús; Falcone, Francisco

2016-08-06

In this work, the performance of ISM 2.4 GHz Wireless Sensor Networks (WSNs) deployed in judo training venues is analyzed. Judo is a very popular martial art, which is practiced by thousands of people not only at the competition level, but also as part of physical education programs at different school levels. There is a great variety of judo training venues, and each one has specific morphological aspects, making them unique scenarios in terms of radio propagation due to the presence of furniture, columns, equipment and the presence of human beings, which is a major issue as the person density within this kind of scenarios could be high. Another key aspect is the electromagnetic interference created by other wireless systems, such as WiFi or other WSNs, which make the radio planning a complex task in terms of coexistence. In order to analyze the impact of these features on the radio propagation and the performance of WSNs, an in-house developed 3D ray launching algorithm has been used. The obtained simulation results have been validated with a measurement campaign carried out in the sport facilities of the Public University of Navarre. The analysis is completed with the inclusion of an application designed to monitor biological constants of judokas, aimed to improve their training procedures. The application, that allows the simultaneous monitoring of multiple judokas (collective workouts) minimizing the efforts of the coach and medical supervisor, is based on commercial off-the-shelf products. The presented assessment of the presence of interfering wireless systems and the presence of human beings within judo training venues shows that an in-depth radio planning is required as these issues can have a great impact in the overall performance of a ISM 2.4 GHz WSN, affecting negatively the potential applications supported by wireless channel.

Implementation and Analysis of ISM 2.4 GHz Wireless Sensor Network Systems in Judo Training Venues

Directory of Open Access Journals (Sweden)

Peio Lopez-Iturri

2016-08-01

Full Text Available In this work, the performance of ISM 2.4 GHz Wireless Sensor Networks (WSNs deployed in judo training venues is analyzed. Judo is a very popular martial art, which is practiced by thousands of people not only at the competition level, but also as part of physical education programs at different school levels. There is a great variety of judo training venues, and each one has specific morphological aspects, making them unique scenarios in terms of radio propagation due to the presence of furniture, columns, equipment and the presence of human beings, which is a major issue as the person density within this kind of scenarios could be high. Another key aspect is the electromagnetic interference created by other wireless systems, such as WiFi or other WSNs, which make the radio planning a complex task in terms of coexistence. In order to analyze the impact of these features on the radio propagation and the performance of WSNs, an in-house developed 3D ray launching algorithm has been used. The obtained simulation results have been validated with a measurement campaign carried out in the sport facilities of the Public University of Navarre. The analysis is completed with the inclusion of an application designed to monitor biological constants of judokas, aimed to improve their training procedures. The application, that allows the simultaneous monitoring of multiple judokas (collective workouts minimizing the efforts of the coach and medical supervisor, is based on commercial off-the-shelf products. The presented assessment of the presence of interfering wireless systems and the presence of human beings within judo training venues shows that an in-depth radio planning is required as these issues can have a great impact in the overall performance of a ISM 2.4 GHz WSN, affecting negatively the potential applications supported by wireless channel.

31 CFR 29.511 - Demand letters.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Demand letters. 29.511 Section 29.511... Overpayments § 29.511 Demand letters. Except as provided in § 29.516(e), before starting collection action to recover an overpayment, the Benefits Administrator must send a demand letter that informs the debtor in...

Spatial Characterization of Radio Propagation Channel in Urban Vehicle-to-Infrastructure Environments to Support WSNs Deployment

Directory of Open Access Journals (Sweden)

Fausto Granda

2017-06-01

Full Text Available Vehicular ad hoc Networks (VANETs enable vehicles to communicate with each other as well as with roadside units (RSUs. Although there is a significant research effort in radio channel modeling focused on vehicle-to-vehicle (V2V, not much work has been done for vehicle-to-infrastructure (V2I using 3D ray-tracing tools. This work evaluates some important parameters of a V2I wireless channel link such as large-scale path loss and multipath metrics in a typical urban scenario using a deterministic simulation model based on an in-house 3D Ray-Launching (3D-RL algorithm at 5.9 GHz. Results show the high impact that the spatial distance; link frequency; placement of RSUs; and factors such as roundabout, geometry and relative position of the obstacles have in V2I propagation channel. A detailed spatial path loss characterization of the V2I channel along the streets and avenues is presented. The 3D-RL results show high accuracy when compared with measurements, and represent more reliably the propagation phenomena when compared with analytical path loss models. Performance metrics for a real test scenario implemented with a VANET wireless sensor network implemented ad-hoc are also described. These results constitute a starting point in the design phase of Wireless Sensor Networks (WSNs radio-planning in the urban V2I deployment in terms of coverage.

Wireless Communication Technologies

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Wireless Communication Technologies. Since 1999, the wireless LAN has experienced a tremendous growth. Reasons: Adoption of industry standards. Interoperability testing. The progress of wireless equipments to higher data rates. Rapid decrease in product ...

Letter Dice. Technical Note No. 6.

Science.gov (United States)

Gunter, Jock

Letter and syllable dice devised for a project in rural Ecuador provide inexpensive, easily reproducible learning materials for practice in basic literary skills. Eleven wooden cubes with six letters on each cube are cast onto a surface and the player constructs words from the letters on the top side of the dice. After a word is formed and…

Simple statistical channel model for weak temperature-induced turbulence in underwater wireless optical communication systems

KAUST Repository

Oubei, Hassan M.

2017-06-16

In this Letter, we use laser beam intensity fluctuation measurements to model and describe the statistical properties of weak temperature-induced turbulence in underwater wireless optical communication (UWOC) channels. UWOC channels with temperature gradients are modeled by the generalized gamma distribution (GGD) with an excellent goodness of fit to the measured data under all channel conditions. Meanwhile, thermally uniform channels are perfectly described by the simple gamma distribution which is a special case of GGD. To the best of our knowledge, this is the first model that comprehensively describes both thermally uniform and gradient-based UWOC channels.

Letter to the parliament:

DEFF Research Database (Denmark)

2017-01-01

This piece was a letter directed towards various ministers in the parliament, targeted at raising a discussion on the values in the education of architects in Denmark and various related topics.......This piece was a letter directed towards various ministers in the parliament, targeted at raising a discussion on the values in the education of architects in Denmark and various related topics....

A MIMO-OFDM Testbed for Wireless Local Area Networks

Directory of Open Access Journals (Sweden)

Conrat Jean-Marc

2006-01-01

Full Text Available We describe the design steps and final implementation of a MIMO OFDM prototype platform developed to enhance the performance of wireless LAN standards such as HiperLAN/2 and 802.11, using multiple transmit and multiple receive antennas. We first describe the channel measurement campaign used to characterize the indoor operational propagation environment, and analyze the influence of the channel on code design through a ray-tracing channel simulator. We also comment on some antenna and RF issues which are of importance for the final realization of the testbed. Multiple coding, decoding, and channel estimation strategies are discussed and their respective performance-complexity trade-offs are evaluated over the realistic channel obtained from the propagation studies. Finally, we present the design methodology, including cross-validation of the Matlab, C++, and VHDL components, and the final demonstrator architecture. We highlight the increased measured performance of the MIMO testbed over the single-antenna system.

Wireless security in mobile health.

Science.gov (United States)

Osunmuyiwa, Olufolabi; Ulusoy, Ali Hakan

2012-12-01

Mobile health (m-health) is an extremely broad term that embraces mobile communication in the health sector and data packaging. The four broad categories of wireless networks are wireless personal area network, wireless metropolitan area network, wireless wide area network, and wireless local area network. Wireless local area network is the most notable of the wireless networking tools obtainable in the health sector. Transfer of delicate and critical information on radio frequencies should be secure, and the right to use must be meticulous. This article covers the business opportunities in m-health, threats faced by wireless networks in hospitals, and methods of mitigating these threats.

Peculiarities of the propagation of multidimensional extremely short optical pulses in germanene

Energy Technology Data Exchange (ETDEWEB)

Zhukov, Alexander V., E-mail: alex_zhukov@sutd.edu.sg [Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore (Singapore); Bouffanais, Roland [Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore (Singapore); Konobeeva, Natalia N. [Volgograd State University, 400062 Volgograd (Russian Federation); Belonenko, Mikhail B. [Laboratory of Nanotechnology, Volgograd Institute of Business, 400048 Volgograd (Russian Federation); Volgograd State University, 400062 Volgograd (Russian Federation)

2016-09-07

Highlights: • Established dynamics of ultra-short pulses in germanene. • Studied balance between dispersive and nonlinear effects in germanene. • Spin–orbit interaction effect onto pulse propagation. - Abstract: In this Letter, we study the propagation characteristics of both two-dimensional and three-dimensional extremely short optical pulses in germanene. A distinguishing feature of germanene—in comparison with other graphene-like structures—is the presence of a significant spin–orbit interaction. The account of this interaction has a significant impact on the evolution of extremely short pulses in such systems. Specifically, extremely short optical pulses, consisting of two electric field oscillations, cause the appearance of a tail associated with the excitation of nonlinear waves. Due to the large spin–orbit interaction in germanene, this tail behind the main pulse is much smaller in germanene-based samples as compared to graphene-based ones, thereby making germanene a preferred material for the stable propagation of pulses along the sample.

Flame Speed and Self-Similar Propagation of Expanding Turbulent Premixed Flames

Science.gov (United States)

Chaudhuri, Swetaprovo; Wu, Fujia; Zhu, Delin; Law, Chung K.

2012-01-01

In this Letter we present turbulent flame speeds and their scaling from experimental measurements on constant-pressure, unity Lewis number expanding turbulent flames, propagating in nearly homogeneous isotropic turbulence in a dual-chamber, fan-stirred vessel. It is found that the normalized turbulent flame speed as a function of the average radius scales as a turbulent Reynolds number to the one-half power, where the average radius is the length scale and the thermal diffusivity is the transport property, thus showing self-similar propagation. Utilizing this dependence it is found that the turbulent flame speeds from the present expanding flames and those from the Bunsen geometry in the literature can be unified by a turbulent Reynolds number based on flame length scales using recent theoretical results obtained by spectral closure of the transformed G equation.

Resource Letter: GW-1: Global warming

Science.gov (United States)

Firor, John W.

1994-06-01

This Resource Letter provides a guide to the literature on the possibility of a human-induced climate change—a global warming. Journal articles and books are cited for the following topics: the Greenhouse Effect, sources of infrared-trapping gases, climate models and their uncertainties, verification of climate models, past climate changes, and economics, ethics, and politics of policy responses to climate change. [The letter E after an item indicates elementary level or material of general interest to persons becoming informed in the field. The letter I, for intermediate level, indicates material of somewhat more specialized nature, and the letter A indicates rather specialized or advanced material.

Implied reading direction and prioritization of letter encoding.

Science.gov (United States)

Holcombe, Alex O; Nguyen, Elizabeth H L; Goodbourn, Patrick T

2017-10-01

Capacity limits hinder processing of multiple stimuli, contributing to poorer performance for identifying two briefly presented letters than for identifying a single letter. Higher accuracy is typically found for identifying the letter on the left, which has been attributed to a right-hemisphere dominance for selective attention. Here, we use rapid serial visual presentation (RSVP) of letters in two locations at once. The letters to be identified are simultaneous and cued by rings. In the first experiment, we manipulated implied reading direction by rotating or mirror-reversing the letters to face to the left rather than to the right. The left-side performance advantage was eliminated. In the second experiment, letters were positioned above and below fixation, oriented such that they appeared to face downward (90° clockwise rotation) or upward (90° counterclockwise rotation). Again consistent with an effect of implied reading direction, performance was better for the top position in the downward condition, but not in the upward condition. In both experiments, mixture modeling of participants' report errors revealed that attentional sampling from the two locations was approximately simultaneous, ruling out the theory that the letter on one side was processed first, followed by a shift of attention to sample the other letter. Thus, the orientation of the letters apparently controls not when the letters are sampled from the scene, but rather the dynamics of a subsequent process, such as tokenization or memory consolidation. Implied reading direction appears to determine the letter prioritized at a high-level processing bottleneck. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Development of a Wireless and Passive SAW-Based Chemical Sensor for Organophosphorous Compound Detection

Directory of Open Access Journals (Sweden)

Fang-Qian Xu

2015-12-01

Full Text Available A new wireless and passive surface acoustic wave (SAW-based chemical sensor for organophosphorous compound (OC detection is presented. A 434 MHz reflective delay line configuration composed by single phase unidirectional transducers (SPUDTs and three shorted reflectors was fabricated on YZ LiNbO3 piezoelectric substrate as the sensor element. A thin fluoroalcoholpolysiloxane (SXFA film acted as the sensitive interface deposited onto the SAW propagation path between the second and last reflectors of the SAW device. The first reflector was used for the temperature compensation utilizing the difference method. The adsorption between the SXFA and OC molecules modulates the SAW propagation, especially for the time delay of the SAW, hence, the phase shifts of the reflection peaks from the corresponding reflectors can be used to characterize the target OC. Prior to the sensor fabrication, the coupling of modes (COM and perturbation theory were utilized to predict the SAW device performance and the gas adsorption. Referring to a frequency-modulated continuous wave (FMCW-based reader unit, the developed SAW chemical sensor was wirelessly characterized in gas exposure experiments for dimethylmethylphosphonate (DMMP detection. Sensor performance parameters such as phase sensitivity, repeatability, linearity, and temperature compensation were evaluated experimentally.

Applying Game Theory in 802.11 Wireless Networks

Directory of Open Access Journals (Sweden)

Tomas Cuzanauskas

2015-07-01

Full Text Available IEEE 802.11 is one of the most popular wireless technologies in recent days. Due to easiness of adaption and relatively low cost the demand for IEEE 802.11 devices is increasing exponentially. IEEE works in two bands 2.4 GHz and 5 GHz, these bands are known as ISM band. The unlicensed bands are managed by authority which set simple rules to follow when using unlicensed bands, the rules includes requirements as maximum power, out-of-band emissions control as well as interference mitigation. However these rules became outdated as IEEE 802.11 technology is emerging and evolving in hours the rules aren’t well suited for current capabilities of IEEE 802.11 devices. In this article we present game theory based algorithm for IEEE 802.11 wireless devices, we will show that by using game theory it’s possible to achieve better usage of unlicensed spectrum as well as partially decline CSMA/CA. Finally by using this approach we might relax the currently applied maximum power rules for ISM bands, which enable IEEE 802.11 to work on longer distance and have better propagation characteristics.

CCNA Wireless Study Guide

CERN Document Server

Lammle, Todd

2010-01-01

A complete guide to the CCNA Wireless exam by leading networking authority Todd Lammle. The CCNA Wireless certification is the most respected entry-level certification in this rapidly growing field. Todd Lammle is the undisputed authority on networking, and this book focuses exclusively on the skills covered in this Cisco certification exam. The CCNA Wireless Study Guide joins the popular Sybex study guide family and helps network administrators advance their careers with a highly desirable certification.: The CCNA Wireless certification is the most respected entry-level wireless certification

The wireless internet explained

CERN Document Server

Rhoton, John

2001-01-01

The Wireless Internet Explained covers the full spectrum of wireless technologies from a wide range of vendors, including initiatives by Microsoft and Compaq. The Wireless Internet Explained takes a practical look at wireless technology. Rhoton explains the concepts behind the physics, and provides an overview that clarifies the convoluted set of standards heaped together under the umbrella of wireless. It then expands on these technical foundations to give a panorama of the increasingly crowded landscape of wireless product offerings. When it comes to actual implementation the book gives abundant down-to-earth advice on topics ranging from the selection and deployment of mobile devices to the extremely sensitive subject of security.Written by an expert on Internet messaging, the author of Digital Press''s successful Programmer''s Guide to Internet Mail and X.400 and SMTP: Battle of the E-mail Protocols, The Wireless Internet Explained describes and evaluates the current state of the fast-growing and crucial...

A method for the 3-D quantification of bridging ligaments during crack propagation

International Nuclear Information System (INIS)

Babout, L.; Janaszewski, M.; Marrow, T.J.; Withers, P.J.

2011-01-01

This letter shows how a hole-closing algorithm can be used to identify and quantify crack-bridging ligaments from a sequence of X-ray tomography images of intergranular stress corrosion cracking. This allows automatic quantification of the evolution of bridging ligaments through the crack propagation sequence providing fracture mechanics insight previously unobtainable from fractography. The method may also be applied to other three-dimensional materials science problems, such as closing walls in foams.

Wireless Access

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Wireless Access. Wireless connect to the Base station. Easy and Convenient access. Costlier as compared to the wired technology. Reliability challenges. We see it as a complementary technology to the DSL.

mm-Wave Hybrid Photonic Wireless Links for Ultra-High Speed Wireless Transmissions

DEFF Research Database (Denmark)

Rommel, Simon; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

Hybrid photonic-wireless transmission schemes in the mm-wave frequency range are promising candidates to enable the multi-gigabit per second data communications required from wireless and mobile networks of the 5th and future generations. Large FCC spectrum allocations for wireless transmission...

48 CFR 42.504 - Postaward letters.

Science.gov (United States)

2010-10-01

... CONTRACT ADMINISTRATION AND AUDIT SERVICES Postaward Orientation 42.504 Postaward letters. In some circumstances, a letter or other written form of communication to the contractor may be adequate postaward...

A Stimulus Sampling Theory of Letter Identity and Order

Science.gov (United States)

Norris, Dennis; Kinoshita, Sachiko; van Casteren, Maarten

2010-01-01

Early on during word recognition, letter positions are not accurately coded. Evidence for this comes from transposed-letter (TL) priming effects, in which letter strings generated by transposing two adjacent letters (e.g., "jugde") produce large priming effects, more than primes with the letters replaced in the corresponding position (e.g.,…

A Hybrid Stochastic Approach for Self-Location of Wireless Sensors in Indoor Environments

Directory of Open Access Journals (Sweden)

Alejandro Canovas

2009-05-01

Full Text Available Indoor location systems, especially those using wireless sensor networks, are used in many application areas. While the need for these systems is widely proven, there is a clear lack of accuracy. Many of the implemented applications have high errors in their location estimation because of the issues arising in the indoor environment. Two different approaches had been proposed using WLAN location systems: on the one hand, the so-called deductive methods take into account the physical properties of signal propagation. These systems require a propagation model, an environment map, and the position of the radio-stations. On the other hand, the so-called inductive methods require a previous training phase where the system learns the received signal strength (RSS in each location. This phase can be very time consuming. This paper proposes a new stochastic approach which is based on a combination of deductive and inductive methods whereby wireless sensors could determine their positions using WLAN technology inside a floor of a building. Our goal is to reduce the training phase in an indoor environment, but, without an loss of precision. Finally, we compare the measurements taken using our proposed method in a real environment with the measurements taken by other developed systems. Comparisons between the proposed system and other hybrid methods are also provided.

Launch of Zoological Letters.

Science.gov (United States)

Fukatsu, Takema; Kuratani, Shigeru

2016-02-01

A new open-access journal, Zoological Letters, was launched as a sister journal to Zoological Science, in January 2015. The new journal aims at publishing topical papers of high quality from a wide range of basic zoological research fields. This review highlights the notable reviews and research articles that have been published in the first year of Zoological Letters, providing an overview on the current achievements and future directions of the journal.

Performance analysis of LDPC codes on OOK terahertz wireless channels

International Nuclear Information System (INIS)

Liu Chun; Wang Chang; Cao Jun-Cheng

2016-01-01

Atmospheric absorption, scattering, and scintillation are the major causes to deteriorate the transmission quality of terahertz (THz) wireless communications. An error control coding scheme based on low density parity check (LDPC) codes with soft decision decoding algorithm is proposed to improve the bit-error-rate (BER) performance of an on-off keying (OOK) modulated THz signal through atmospheric channel. The THz wave propagation characteristics and channel model in atmosphere is set up. Numerical simulations validate the great performance of LDPC codes against the atmospheric fading and demonstrate the huge potential in future ultra-high speed beyond Gbps THz communications. (paper)

Reliable and energy-efficient communications for wireless biomedical implant systems.

Science.gov (United States)

Ntouni, Georgia D; Lioumpas, Athanasios S; Nikita, Konstantina S

2014-11-01

Implant devices are used to measure biological parameters and transmit their results to remote off-body devices. As implants are characterized by strict requirements on size, reliability, and power consumption, applying the concept of cooperative communications to wireless body area networks offers several benefits. In this paper, we aim to minimize the power consumption of the implant device by utilizing on-body wearable devices, while providing the necessary reliability in terms of outage probability and bit error rate. Taking into account realistic power considerations and wireless propagation environments based on the IEEE P802.l5 channel model, an exact theoretical analysis is conducted for evaluating several communication scenarios with respect to the position of the wearable device and the motion of the human body. The derived closed-form expressions are employed toward minimizing the required transmission power, subject to a minimum quality-of-service requirement. In this way, the complexity and power consumption are transferred from the implant device to the on-body relay, which is an efficient approach since they can be easily replaced, in contrast to the in-body implants.

Letters to those who Dare Feel: Using Reflective Letter-Writing to Explore the Emotionality of Research

Directory of Open Access Journals (Sweden)

Kathleen Pithouse-Morgan

2012-02-01

Full Text Available Using reflective letter-writing as a method of generating data, a group of four researchers embarked on a collaborative autoethnographic inquiry into the emotional dimensions of researching social aspects of HIV & AIDS. In this article, we use the medium of a narrative dialogue to represent and re-examine our reflective letter-writing method. The dialogue draws attention to key features of reflective letter-writing as a collaborative autoethnographic research method and, in so doing, highlights and explores the nature, potential significance, and challenges of this method. Our discussion points to the value of a collaborative process of reflective letter-writing as a way for researchers to access and portray emotional aspects of their research experience, to deepen their engagement with these emotional dimensions, and to gain insight into their own and others' lived research experiences.

Written Communications Simulation: Write Me a Letter.

Science.gov (United States)

North Carolina State Dept. of Public Instruction, Raleigh. Div. of Vocational Education.

This simulation is intended for use as a culminating activity after students have been exposed to personal and/or business letter writing, use of reference manuals, typing of letters, mailing procedures, typing of numbers, punctuation practice, and filing procedures. Stated objectives are to enable students to type a mailable letter; to inspect,…

K Coverage Probability of 5G Wireless Cognitive Radio Network under Shadow Fading Effects

Directory of Open Access Journals (Sweden)

Ankur S. Kang

2016-09-01

Full Text Available Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings,foliage and terrain.Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters.Shadowing introduces additional fluctuations,so the received local mean power varies around the area –mean.The present section deals with the performance analysis of fifth generation wireless cognitive radio network on the basis of signal and interference level based k coverage probability under the shadow fading effects.

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture

Science.gov (United States)

Steele, Kerry D [Kennewick, WA; Anderson, Gordon A [Benton City, WA; Gilbert, Ronald W [Morgan Hill, CA

2011-02-01

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture are described. In one aspect, a communications device identification method includes providing identification information regarding a group of wireless identification devices within a wireless communications range of a reader, using the provided identification information, selecting one of a plurality of different search procedures for identifying unidentified ones of the wireless identification devices within the wireless communications range, and identifying at least some of the unidentified ones of the wireless identification devices using the selected one of the search procedures.

Wireless adiabatic power transfer

International Nuclear Information System (INIS)

Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.

2011-01-01

Research highlights: → Efficient and robust mid-range wireless energy transfer between two coils. → The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. → Wireless energy transfer is insensitive to any resonant constraints. → Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.

On Coding Non-Contiguous Letter Combinations

Directory of Open Access Journals (Sweden)

Frédéric eDandurand

2011-06-01

Full Text Available Starting from the hypothesis that printed word identification initially involves the parallel mapping of visual features onto location-specific letter identities, we analyze the type of information that would be involved in optimally mapping this location-specific orthographic code onto a location-invariant lexical code. We assume that some intermediate level of coding exists between individual letters and whole words, and that this involves the representation of letter combinations. We then investigate the nature of this intermediate level of coding given the constraints of optimality. This intermediate level of coding is expected to compress data while retaining as much information as possible about word identity. Information conveyed by letters is a function of how much they constrain word identity and how visible they are. Optimization of this coding is a combination of minimizing resources (using the most compact representations and maximizing information. We show that in a large proportion of cases, non-contiguous letter sequences contain more information than contiguous sequences, while at the same time requiring less precise coding. Moreover, we found that the best predictor of human performance in orthographic priming experiments was within-word ranking of conditional probabilities, rather than average conditional probabilities. We conclude that from an optimality perspective, readers learn to select certain contiguous and non-contiguous letter combinations as information that provides the best cue to word identity.

Wireless communication technology NFC

OpenAIRE

MÁROVÁ, Kateřina

2014-01-01

Aim of this bachelor thesis is to handle the issue of new wireless communication technology NFC (Near Field Communication) including a comparison of advantages and disadvantages of NFC with other wireless technologies (Bluetooth, Wi-Fi, etc.). NFC is a technology for wireless communications between different electronic devices, one of which is typically a mobile phone. Near Field Communication allows wireless communication at very short distance by approaching or enclosing two devices and can...

75 FR 8400 - In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld...

Science.gov (United States)

2010-02-24

... Communications System Server Software, Wireless Handheld Devices and Battery Packs; Notice of Investigation... within the United States after importation of certain wireless communications system server software... certain wireless communications system server software, wireless handheld devices or battery packs that...

75 FR 43206 - In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld...

Science.gov (United States)

2010-07-23

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-706] In the Matter of Certain Wireless Communications System Server Software, Wireless Handheld Devices and Battery Packs: Notice of Commission... United States after importation of certain wireless communications system server software, wireless...

A Mixed Transmission Strategy to Achieve Energy Balancing in Wireless Sensor Networks

DEFF Research Database (Denmark)

Liu, Tong; Gu, Tao; Jin, Ning

2017-01-01

In this paper, we investigate the problem of energy balanced data collection in wireless sensor networks, aiming to balance energy consumption among all sensor nodes during the data propagation process. Energy balanced data collection can potentially save energy consumption and prolong network...... lifetime, and hence, it has many practical implications for sensor network design and deployment. The traditional hop-by-hop transmission model allows a sensor node to propagate its packets in a hop-by-hop manner toward the sink, resulting in poor energy balancing for the entire network. To address...... the problem, we apply a slice-based energy model, and divide the problem into inter-slice and intra-slice energy balancing problems. We then propose a probability-based strategy named inter-slice mixed transmission protocol and an intra-slice forwarding technique to address each of the problems. We propose...

Writing More Informative Letters of Reference

OpenAIRE

Wright, Scott M; Ziegelstein, Roy C

2004-01-01

Writing a meaningful and valuable letter of reference is not an easy task. Several factors influence the quality of any letter of reference. First, the accuracy and reliability of the writer's impressions and judgment depend on how well he knows the individual being described. Second, the writer's frame of reference, which is determined by the number of persons at the same level that he has worked with, will impact the context and significance of his beliefs and estimations. Third, the letter...

Use of Standard Guidelines for Department of Medicine Summary Letters.

Science.gov (United States)

Fitz, Matthew; La Rochelle, Jeffrey; Lang, Valerie; DeWaay, Deborah; Adams, William; Nasraty, Farah

2018-04-12

Phenomenon: Fourth-year medical students obtain Department of Medicine (DOM) letters ("Chair" letters) to support their residency applications. Writing and interpreting DOM letters are challenging. There is heterogeneity in the letters that makes it difficult to both write and read these letters. The purpose of this study is to determine the value of new guidelines developed by a task force of clerkship directors and program directors in internal medicine and assess the implementation of these guidelines. The Clerkship Directors in Internal Medicine performed a cross-sectional survey of internal medicine clerkship directors at U.S. and Canadian medical schools in 2014. In addition, the primary author's institution reviewed 1,347 DOM letters between 2012 and 2014 to assess the implementation of these guidelines. The survey response rate was 78%. DOM letter writers reported the guidelines were better, easier to implement, and more compatible with the purpose of DOM letters than previously. Most letter readers reported that letters using the guidelines were more credible. Writers of DOM letters in lower academic ranks rated the letters with guidelines higher in several domains than those in higher academic ranks. Readers of DOM letters in higher academic ranks rated the letters with guidelines higher in several domains than those in lower academic ranks. In the DOM letters examined, the odds of meeting each guideline increased with each additional year. However, for 3 guidelines there was an initial decline in adherence from 2012 to 2013 before increasing again in 2014-the recommended length, clerkship description, and detailed narrative guidelines. Letters solely written by a chair were less likely to incorporate the guidelines. Insights: Clerkship directors often write the DOM letters and identify with the purpose of the guidelines. As writers, lower ranking academic faculty value the guidelines more than higher ranking academic faculty. As readers of DOM letters

Automated alignment system for optical wireless communication systems using image recognition.

Science.gov (United States)

Brandl, Paul; Weiss, Alexander; Zimmermann, Horst

2014-07-01

In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receiver's position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10⁻⁹) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s.

Wireless Internet

NARCIS (Netherlands)

el Zarki, M.; Heijenk, Geert; Lee, Kenneth S.; Bidgoli, H.

This chapter addresses the topic of wireless Internet, the extension of the wireline Internet architecture to the wireless domain. As such the chapter introduces the reader to the dominant characteristics of the Internet, from its structure to the protocols that control the forwarding of data and

Wireless ATM : handover issues

OpenAIRE

Jiang, Fan; Käkölä, Timo

1998-01-01

Basic aspects of cellular systems and the ATM transmission technology are introduced. Wireless ATM is presented as a combination of radio ATM and mobile ATM. Radio ATM is a wireless extension of an ATM connection while mobile ATM contains the necessary extensions to ATM to support mobility. Because the current ATM technology does not support mobility, handover becomes one of the most important research issues for wireless ATM. Wireless ATM handover requirements are thus analysed. A handover s...

Wireless sensor networks architectures and protocols

CERN Document Server

Callaway, Jr, Edgar H

2003-01-01

Introduction to Wireless Sensor NetworksApplications and MotivationNetwork Performance ObjectivesContributions of this BookOrganization of this BookThe Development of Wireless Sensor NetworksEarly Wireless NetworksWireless Data NetworksWireless Sensor and Related NetworksConclusionThe Physical LayerSome Physical Layer ExamplesA Practical Physical Layer for Wireless Sensor NetworksSimulations and ResultsConclusionThe Data Link LayerMedium Access Control TechniquesThe Mediation DeviceSystem Analysis and SimulationConclusionThe Network LayerSome Network Design ExamplesA Wireless Sensor Network De

Study on Communication Mode of Wireless Sensor Networks Based on Effective Result

International Nuclear Information System (INIS)

Shi, J F; Zhong, X X; Chen, S

2006-01-01

The key challenge in wireless sensor networks is maximizing network lifetime. It will significantly reduce energy consumption of communication and prolong networks lifetime to choose appropriate communication mode. In this paper, energy model and communication topology are proposed, and then from the viewpoint of effective result, expression for communication energy cost of single sensor node and overall system in different communication mode is derived, impact that sensor nodes amount, communication radius and propagation loss exponent pose on communication mode based on simulations is analyzed, and the justification for choosing communication mode is summarized

Security for multihop wireless networks

CERN Document Server

Khan, Shafiullah

2014-01-01

Security for Multihop Wireless Networks provides broad coverage of the security issues facing multihop wireless networks. Presenting the work of a different group of expert contributors in each chapter, it explores security in mobile ad hoc networks, wireless sensor networks, wireless mesh networks, and personal area networks.Detailing technologies and processes that can help you secure your wireless networks, the book covers cryptographic coprocessors, encryption, authentication, key management, attacks and countermeasures, secure routing, secure medium access control, intrusion detection, ep

Internal model control for industrial wireless plant using WirelessHART hardware-in-the-loop simulator.

Science.gov (United States)

Tran, Chung Duc; Ibrahim, Rosdiazli; Asirvadam, Vijanth Sagayan; Saad, Nordin; Sabo Miya, Hassan

2018-04-01

The emergence of wireless technologies such as WirelessHART and ISA100 Wireless for deployment at industrial process plants has urged the need for research and development in wireless control. This is in view of the fact that the recent application is mainly in monitoring domain due to lack of confidence in control aspect. WirelessHART has an edge over its counterpart as it is based on the successful Wired HART protocol with over 30 million devices as of 2009. Recent works on control have primarily focused on maintaining the traditional PID control structure which is proven not adequate for the wireless environment. In contrast, Internal Model Control (IMC), a promising technique for delay compensation, disturbance rejection and setpoint tracking has not been investigated in the context of WirelessHART. Therefore, this paper discusses the control design using IMC approach with a focus on wireless processes. The simulation and experimental results using real-time WirelessHART hardware-in-the-loop simulator (WH-HILS) indicate that the proposed approach is more robust to delay variation of the network than the PID. Copyright © 2017. Published by Elsevier Ltd.

Maritime Geo-Fence Letter Report

Science.gov (United States)

2016-07-01

1 Classification | CG-926 RDC | author | audience | month year Maritime Geo-Fence Letter Report Authors: Irene Gonin and Gregory...Johnson   Distribution Statement A: Approved for public release; distribution is unlimited. July 2016 Report No. CG-D-10-16 Maritime Geo-Fence...United States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 Maritime Geo-Fence Letter Report 1

The role of sensorimotor learning in the perception of letter-like forms: tracking the causes of neural specialization for letters.

Science.gov (United States)

James, Karin H; Atwood, Thea P

2009-02-01

Functional specialization in the brain is considered a hallmark of efficient processing. It is therefore not surprising that there are brain areas specialized for processing letters. To better understand the causes of functional specialization for letters, we explore the emergence of this pattern of response in the ventral processing stream through a training paradigm. Previously, we hypothesized that the specialized response pattern seen during letter perception may be due in part to our experience in writing letters. The work presented here investigates whether or not this aspect of letter processing-the integration of sensorimotor systems through writing-leads to functional specialization in the visual system. To test this idea, we investigated whether or not different types of experiences with letter-like stimuli ("pseudoletters") led to functional specialization similar to that which exists for letters. Neural activation patterns were measured using functional magnetic resonance imaging (fMRI) before and after three different types of training sessions. Participants were trained to recognize pseudoletters by writing, typing, or purely visual practice. Results suggested that only after writing practice did neural activation patterns to pseudoletters resemble patterns seen for letters. That is, neural activation in the left fusiform and dorsal precentral gyrus was greater when participants viewed pseudoletters than other, similar stimuli but only after writing experience. Neural activation also increased after typing practice in the right fusiform and left precentral gyrus, suggesting that in some areas, any motor experience may change visual processing. The results of this experiment suggest an intimate interaction among perceptual and motor systems during pseudoletter perception that may be extended to everyday letter perception.

A video wireless capsule endoscopy system powered wirelessly: design, analysis and experiment

International Nuclear Information System (INIS)

Pan, Guobing; Chen, Jiaoliao; Xin, Wenhui; Yan, Guozheng

2011-01-01

Wireless capsule endoscopy (WCE), as a relatively new technology, has brought about a revolution in the diagnosis of gastrointestinal (GI) tract diseases. However, the existing WCE systems are not widely applied in clinic because of the low frame rate and low image resolution. A video WCE system based on a wireless power supply is developed in this paper. This WCE system consists of a video capsule endoscope (CE), a wireless power transmission device, a receiving box and an image processing station. Powered wirelessly, the video CE has the abilities of imaging the GI tract and transmitting the images wirelessly at a frame rate of 30 frames per second (f/s). A mathematical prototype was built to analyze the power transmission system, and some experiments were performed to test the capability of energy transferring. The results showed that the wireless electric power supply system had the ability to transfer more than 136 mW power, which was enough for the working of a video CE. In in vitro experiments, the video CE produced clear images of the small intestine of a pig with the resolution of 320 × 240, and transmitted NTSC format video outside the body. Because of the wireless power supply, the video WCE system with high frame rate and high resolution becomes feasible, and provides a novel solution for the diagnosis of the GI tract in clinic

Wireless power transfer to deep-tissue microimplants.

Science.gov (United States)

Ho, John S; Yeh, Alexander J; Neofytou, Evgenios; Kim, Sanghoek; Tanabe, Yuji; Patlolla, Bhagat; Beygui, Ramin E; Poon, Ada S Y

2014-06-03

The ability to implant electronic systems in the human body has led to many medical advances. Progress in semiconductor technology paved the way for devices at the scale of a millimeter or less ("microimplants"), but the miniaturization of the power source remains challenging. Although wireless powering has been demonstrated, energy transfer beyond superficial depths in tissue has so far been limited by large coils (at least a centimeter in diameter) unsuitable for a microimplant. Here, we show that this limitation can be overcome by a method, termed midfield powering, to create a high-energy density region deep in tissue inside of which the power-harvesting structure can be made extremely small. Unlike conventional near-field (inductively coupled) coils, for which coupling is limited by exponential field decay, a patterned metal plate is used to induce spatially confined and adaptive energy transport through propagating modes in tissue. We use this method to power a microimplant (2 mm, 70 mg) capable of closed-chest wireless control of the heart that is orders of magnitude smaller than conventional pacemakers. With exposure levels below human safety thresholds, milliwatt levels of power can be transferred to a deep-tissue (>5 cm) microimplant for both complex electronic function and physiological stimulation. The approach developed here should enable new generations of implantable systems that can be integrated into the body at minimal cost and risk.

Data converters for wireless standards

CERN Document Server

Shi, Chunlei

2002-01-01

Wireless communication is witnessing tremendous growth with proliferation of different standards covering wide, local and personal area networks (WAN, LAN and PAN). The trends call for designs that allow 1) smooth migration to future generations of wireless standards with higher data rates for multimedia applications, 2) convergence of wireless services allowing access to different standards from the same wireless device, 3) inter-continental roaming. This requires designs that work across multiple wireless standards, can easily be reused, achieve maximum hardware share at a minimum power consumption levels particularly for mobile battery-operated devices.

An application of nonlinear supratransmission to the propagation of binary signals in weakly damped, mechanical systems of coupled oscillators

International Nuclear Information System (INIS)

Macias-Diaz, J.E.; Puri, A.

2007-01-01

In the present Letter, we simulate the propagation of binary signals in semi-infinite, mechanical chains of coupled oscillators harmonically driven at the end, by making use of the recently discovered process of nonlinear supratransmission. Our numerical results-which are based on a brand-new computational technique with energy-invariant properties-show an efficient and reliable transmission of information

Teaching Complaint and Adjustment Letters--And Tact (My Favorite Assignment).

Science.gov (United States)

Deimling, Paula

1992-01-01

Describes a three-part assignment in which each student writes a complaint letter and an adjustment letter responding to another student's complaint letter. Discusses how the third part of the assignment--journal entries--allows students to formulate their own criteria for excellent letters based upon their reactions to the letters they receive.…

Novel Concepts of Cooperative Wireless Networking

DEFF Research Database (Denmark)

Zhang, Qi

2008-01-01

; secondly, the increasing density of the wireless devices makes cooperation possible; last, the cost of information exchange (i.e. transmission power, transmission time, spectrum, etc.) is very low if information exchange over short-range link is needed. Cooperation changes the way of information delivery......Although wireless networks have achieved great success in the lastest two decades, the current wireless networks have difficulties to fulll users' ever-increasing expectations and needs. It is mainly due to available spectrum resource scarcity, limited battery capacity of wireless device......, unreliable wireless radio link, etc. To tackle these issues, a new telecommunication paradigm has been proposed, referred to as cooperative wireless networking [1]. The basic idea of cooperative wireless networking is that wireless devices work together to achieve their individual goals or one common goal...

Wireless Networks: New Meaning to Ubiquitous Computing.

Science.gov (United States)

Drew, Wilfred, Jr.

2003-01-01

Discusses the use of wireless technology in academic libraries. Topics include wireless networks; standards (IEEE 802.11); wired versus wireless; why libraries implement wireless technology; wireless local area networks (WLANs); WLAN security; examples of wireless use at Indiana State University and Morrisville College (New York); and useful…

Scheduled Collision Avoidance in wireless sensor network using Zigbee

DEFF Research Database (Denmark)

Dnyaneshwar, Mantri; Prasad, Neeli R.; Prasad, Ramjee

2014-01-01

Transmission reliability and energy consumptions are two critical concerns associated with wireless sensor network (WSN) design for a long time and continuous operation. With the increase in reliability of the transmission, the energy consumption increases by affecting the efficiency of the network....... This paper proposes the Schedule based Collision Avoidance (SCA) algorithm for finding the tradeoff between reliability and energy efficiency by fusion of CSMA/CA and TDMA techniques in Zigbee/ IEEE802.15.4. It uses the multi-path data propagation for collision avoidance and effective utilization...... of the channel providing efficient energy consumption. It analyses different scheduling schemes to provide an appropriate solution for reducing collisions and improving network lifetime....

From early wireless to Everest.

Science.gov (United States)

Allen, A

1998-01-01

Medical information has been transmitted using wireless technologies for almost 80 years. A "wired wireless" electronic stethoscope was developed by the U.S. Army Signal Corps in the early 1920's, for potential use in ship-to-shore transmission of cardiac sounds. [Winters SR. Diagnosis by wireless. Scientific American June 11, 1921, p. 465] Today, wireless is used in a wide range of medical applications and at sites from transoceanic air flights to offshore oil platforms to Mt. Everest. 'Wireless LANs' are often used in medical environments. Typically, nurses and physicians in a hospital or clinic use hand-held "wireless thin client" pen computers that exchange patient information and images with the hospital server. Numerous companies, such as Fujitsu (article below) and Cruise Technologies (www.cruisetech.com) manufacture handheld pen-entry computers. One company, LXE, integrates radio-frequency (RF) enhanced hand-held computers specifically designed for production use within a wireless LAN (www.lxe.com). Other companies (Proxim, Symbol, and others) supply the wireless RF LAN infrastructure for the enterprise. Unfortunately, there have been problems with widespread deployment of wireless LANs. Perhaps the biggest impediment has been the lack of standards. Although an international standard (IEEE 802.11) was adopted in 1997, most wireless LAN products still are not compatible with the equipment of competing companies. A problem with the current standard for LAN adapters is that throughput is limited to 3 Mbps--compared to at least 10 Mbps, and often 100 Mbps, in a hard-wired Ethernet LAN. An II Mbps standard is due out in the next year or so, but it will be at least 2 years before standards-compliant products are available. This story profiles some of the ways that wireless is being used to overcome gaps in terrestrial and within-enterprise communication.

Exploring Corporate Rhetoric: Metadiscourse in the CEO's Letter.

Science.gov (United States)

Hyland, Ken

1998-01-01

Examines how metadiscourse is used to create a positive corporate image in 137 CEOs' letters, showing how CEOs use nonpropositional material to realize rational, credible, and affective appeals. Reveals the essentially rhetorical nature of CEOs' letters by comparing the frequency and distribution of metadiscourse in their letters and directors'…

Angles of Refraction: The Letters of Mary Delany

Directory of Open Access Journals (Sweden)

Eleonora Chiavetta

2014-04-01

Full Text Available Mary Delany (1700-1788 is particularly famous for her paper-cuttings or ‘mosaicks’ based on botanical subjects. A very lively woman of fashion, she was close to Queen Charlotte and one of the Bluestocking Ladies. She left a vivid portrait of life and society in eighteenth century England and Ireland in the six volumes of her Autobiography and Letters, edited in 1861 by her descendant Lady Llanover. Her autobiography is made up of 18 letters sent to her most intimate friend, Margaret Cavendish, Duchess of Portland. The first letter is dated 1740, but in this, as in the following ones, Mrs. Delany narrates her past life to her friend, starting from the early years of her life, describing her unhappy marriage, financial difficulties as a widow, and family relationships. Along with these ‘autobiographical’ letters, other letters written by her to her sister Ann are introduced, which date to the periods of life Mrs. Delany is dealing with. The aim of this paper is to focus on the textual, linguistic and content differences between the two letter types, and analyse how the identity of Mary Delany is differently constructed and perceived in the explicit autobiographical letters addressed to the Duchess of Portland, and the ones written to her sister. 

Securing a Wireless Site Network to Create a BIM-Allied Work-Front

Directory of Open Access Journals (Sweden)

Payam R. Zekavat

2014-08-01

Full Text Available The Building Information Model (BIM serves as a framework to align all the project-related data, providing interoperability to store and retrieve information interactively. Unfortunately, the construction site itself is excluded from this interaction as the large amount of data requires high data transfer rates and ruggedized hardware. However, advanced wireless communication technologies open radically new avenues to relay large amounts of data automatically and in near real-time. Construction could be a key beneficiary of these advancements. Wireless communication integrated with BIM, GPS and the Internet is able to provide the backbone necessary for creating intelligent systems, supporting the designer in his or her office as well as workers on the work-front. This paper presents a study that documents the development and testing of prototypes designed to facilitate information sharing at the field-level during construction. The main system constitutes an information hub, called the eCKiosk, connecting “senders and receivers” both on-site as well as off-site. The system design is discussed and some of the main modules are demonstrated. Since the electronic Kiosk depends on robust connections to the wireless devices distributed across the site, reliable connectivity is essential. For this reason, the discussion includes a study of the electronic signals behaviour in an ever-changing construction site. Measurements of the signal strengths during excavation and concrete work are presented and compared with theoretical calculations used to predict wave propagation. The results show how present models overestimate signal attenuation patterns on the construction site. This is important for designing a reliable and secure wireless site networks to link BIM to the work-front.

Wireless network pricing

CERN Document Server

Huang, Jianwei

2013-01-01

Today's wireless communications and networking practices are tightly coupled with economic considerations, to the extent that it is almost impossible to make a sound technology choice without understanding the corresponding economic implications. This book aims at providing a foundational introduction on how microeconomics, and pricing theory in particular, can help us to understand and build better wireless networks. The book can be used as lecture notes for a course in the field of network economics, or a reference book for wireless engineers and applied economists to understand how pricing

Student Teacher Letters of Reference: A Critical Analysis

Science.gov (United States)

Mason, Richard W.; Schroeder, Mark P.

2012-01-01

Letters of reference are commonly used in acquiring a job in education. Despite serious issues of validity and reliability in writing and evaluating letters, there is a dearth of research that systematically examines the evaluation process and defines the constructs that define high quality letters. The current study used NVivo to examine 160…

Wireless sensing without sensors—an experimental study of motion/intrusion detection using RF irregularity

International Nuclear Information System (INIS)

Lee, Pius W Q; Tan, Hwee-Pink; Seah, Winston K G; Yao, Zexi

2010-01-01

Motion and intrusion detection are often cited as wireless sensor network (WSN) applications with typical configurations comprising clusters of wireless nodes equipped with motion sensors to detect human motion. Currently, WSN performance is subjected to several constraints, namely radio irregularity and finite on-board computation/energy resources. Radio irregularity in radio frequency (RF) propagation rises to a higher level in the presence of human activity due to the absorption effect of the human body. In this paper, we investigate the feasibility of monitoring RF transmission for the purpose of intrusion detection through experimentation. With empirical data obtained from the Crossbow TelosB platform in several different environments, the impact of human activity on the signal strength of RF signals in a WSN is evaluated. We then propose a novel approach to intrusion detection by turning a constraint in WSN, namely radio irregularity, into an advantage for the purpose of intrusion detection, using signal fluctuations to detect the presence of human activity within the WSN. Unlike RF fingerprinting, the 'intruders' here neither transmit nor receive any RF signals. By enabling existing wireless infrastructures to serve as intrusion detectors instead of deploying numerous costly sensors, this approach shows great promise for providing novel solutions

Intelligent Wireless Sensor Network

OpenAIRE

Saeed, Bakhtiar I.; Mehrdadi, Bruce

2010-01-01

In recent years, there has been significant increase in utilisation of embedded-microcontrollers in broad range of applications extending from commercial products to industrial process system monitoring. Furthermore, improvements in speed, size and power consumption of microcontrollers with added wireless capabilities has provided new generation of applications. These include versatile and\\ud low cost solutions in wireless sensor networking applications such as wireless system monitoring and ...

Sixty-Minute Review of Letter Writing

Science.gov (United States)

Cunningham, Donald H.; Graham, Louise

1974-01-01

The article describes a one-hour presentation which provides a basic stereotyped pattern of letter organization for the four types of letters (order, request, claim, and reply) the business of secretarial student is most likely to have to write. The four paragraphs of the pattern are: purpose, explanation, optional, and closing. (AG)

The development of a wireless Love wave biosensor on 41° YX LiNbO3

International Nuclear Information System (INIS)

Oh, Hae-Kwan; Wang, Wen; Lee, Keekeun; Min, Churlki; Yang, Sangsik

2009-01-01

This paper presents a novel wireless Love-wave-based biosensor using a polymethyl methacrylate (PMMA) waveguide and protein A receptor layers on a 41° YX LiNbO 3 piezoelectric substrate for immunoglobulin G (IgG) detection. A 440 MHz reflective delay line composed of single-phase unidirectional transducers (SPUDTs) and three shorted grating reflectors was fabricated as the sensor element. A theoretical modeling was performed to describe the wave propagation of Love wave devices on a 41° YX LiNbO 3 piezoelectric substrate with large piezoelectricity. The fabricated devices were wirelessly characterized by using the network analyzer as the reader unit. The resultant reflection peaks showed large signal/noise ratio, sharp peaks, and few spurious signals. The binding of the IgG to the protein A receptor layer induced large phase shifts of the reflection peaks due to the mass loading effect. Good linearity, reproducibility, and high sensitivity were observed in the IgG concentration range 1–65 nM. Unique advantages such as high sensitivity and a simple wireless measurement method over other currently available biosensors are also presented

The wireless Web and patient care.

Science.gov (United States)

Bergeron, B P

2001-01-01

Wireless computing, when integrated with the Web, is poised to revolutionize the practice and teaching of medicine. As vendors introduce wireless Web technologies in the medical community that have been used successfully in the business and consumer markets, clinicians can expect profound increases in the amount of patient data, as well as the ease with which those data are acquired, analyzed, and disseminated. The enabling technologies involved in this transformation to the wireless Web range from the new generation of wireless PDAs, eBooks, and wireless data acquisition peripherals to new wireless network protocols. The rate-limiting step in the application of this technology in medicine is not technology per se but rather how quickly clinicians and their patients come to accept and appreciate the benefits and limitations of the application of wireless Web technology.

Method of synchronizing with an uplink channel and a method of determining a propagation delay in a wireless communications system

NARCIS (Netherlands)

Bosch, H.G.P.; Farag, E.N.; Mullender, Sape J.; Nathues, A.; Samuel, L.G.

2007-01-01

provided. In the example method of synchronizing, a propagation delay between a target base station and a mobile station is calculated. Then, the calculated propagation delay is sent to the target base station. In the example method of determining a propagation delay, a first signal is received

Frequency-division multiplexer and demultiplexer for terahertz wireless links.

Science.gov (United States)

Ma, Jianjun; Karl, Nicholas J; Bretin, Sara; Ducournau, Guillaume; Mittleman, Daniel M

2017-09-28

The development of components for terahertz wireless communications networks has become an active and growing research field. However, in most cases these components have been studied using a continuous or broadband-pulsed terahertz source, not using a modulated data stream. This limitation may mask important aspects of the performance of the device in a realistic system configuration. We report the characterization of one such device, a frequency multiplexer, using modulated data at rates up to 10 gigabits per second. We also demonstrate simultaneous error-free transmission of two signals at different carrier frequencies, with an aggregate data rate of 50 gigabits per second. We observe that the far-field spatial variation of the bit error rate is different from that of the emitted power, due to a small nonuniformity in the angular detection sensitivity. This is likely to be a common feature of any terahertz communication system in which signals propagate as diffracting beams not omnidirectional broadcasts.There is growing interest in the development of components to facilitate wireless communications in the terahertz but the characterization of these systems involve an unmodulated input. Here the authors demonstrate multiplexing and demultiplexing of data streams in the terahertz range using a real data link.

A Least Square-Based Self-Adaptive Localization Method for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Baoguo Yu

2016-01-01

Full Text Available In the wireless sensor network (WSN localization methods based on Received Signal Strength Indicator (RSSI, it is usually required to determine the parameters of the radio signal propagation model before estimating the distance between the anchor node and an unknown node with reference to their communication RSSI value. And finally we use a localization algorithm to estimate the location of the unknown node. However, this localization method, though high in localization accuracy, has weaknesses such as complex working procedure and poor system versatility. Concerning these defects, a self-adaptive WSN localization method based on least square is proposed, which uses the least square criterion to estimate the parameters of radio signal propagation model, which positively reduces the computation amount in the estimation process. The experimental results show that the proposed self-adaptive localization method outputs a high processing efficiency while satisfying the high localization accuracy requirement. Conclusively, the proposed method is of definite practical value.

Wireless network security theories and applications

CERN Document Server

Chen, Lei; Zhang, Zihong

2013-01-01

Wireless Network Security Theories and Applications discusses the relevant security technologies, vulnerabilities, and potential threats, and introduces the corresponding security standards and protocols, as well as provides solutions to security concerns. Authors of each chapter in this book, mostly top researchers in relevant research fields in the U.S. and China, presented their research findings and results about the security of the following types of wireless networks: Wireless Cellular Networks, Wireless Local Area Networks (WLANs), Wireless Metropolitan Area Networks (WMANs), Bluetooth

Initial and noninitial name-letter preferences as obtained through repeated letter rating tasks continue to reflect (different aspects of) self-esteem.

Science.gov (United States)

Hoorens, Vera; Takano, Keisuke; Franck, Erik; Roberts, John E; Raes, Filip

2015-09-01

We tested the usefulness of name-letter preference scores as indirect indicators of self-esteem by exploring whether multiple unsupervised self-administrations of letter rating tasks within a short period of time yield useful data. We also examined whether preferences for initials and noninitial name-letters tap different aspects of self-esteem. Participants from a community sample (N = 164; 58 men and 106 women, 17-67 years, Mage = 34.57, SD = 13.28) completed daily letter rating tasks and state self-esteem questionnaires for 7 consecutive days. They also completed a trait self-esteem questionnaire on the first measurement day as well as 6 months later. Preference scores for first-name initials were stronger but more unstable than preference scores for other name-letters. Preferences for first-name initials were primarily associated with directly measured state self-esteem whereas preferences for noninitials were primarily associated with directly measured trait self-esteem even if the latter was measured 6 months later. Thus, we showed that preferences for initials and noninitials are not simply interchangeable. Previous letter rating studies, which almost exclusively used initial preferences, should be interpreted in terms of state rather than trait self-esteem. In future studies, researchers should focus on the name-letter preference that reflects the aspect of self-esteem they wish to address. (c) 2015 APA, all rights reserved.

Wireless Cybersecurity

Science.gov (United States)

2013-04-01

completely change the entire landscape. For example, under the quantum computing regime, factoring prime numbers requires only polynomial time (i.e., Shor’s...AFRL-OSR-VA-TR-2013-0206 Wireless Cybersecurity Biao Chen Syracuse University April 2013 Final Report DISTRIBUTION A...19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 21-02-2013 FINAL REPORT 01-04-2009 TO 30-11-2012 Wireless Cybersecurity

The Lure of Wireless Encryption

CERN Multimedia

Computer Security Team

2013-01-01

Following our article entitled “Jekyll or Hyde? Better browse securely” in the last issue of the Bulletin, some people wondered why the CERN wireless network is not encrypted…   There are many arguments why it is not. The simplest is usability: the communication and management of the corresponding access keys would be challenging given the sheer number of wireless devices the CERN network hosts. Keys would quickly become public, e.g. at conferences, and might be shared, written on whiteboards, etc. Then there are all the devices which cannot be easily configured to use encryption protocols - a fact which would create plenty of calls to the CERN Service Desk… But our main argument is that wireless encryption is DECEPTIVE. Wireless encryption is deceptive as it only protects the wireless network against unauthorised access (and the CERN network already has other means to protect against that). Wireless encryption however, does not really help you. You ...

Advice letter on policy instruments renewable electricity

International Nuclear Information System (INIS)

2011-01-01

In a letter of July 2010 the Energy Council made recommendations for a policy framework with more obligations and fewer subsidies. This included the Energy Council's advice to investigate whether the introduction of a supplier obligation could play a major role in the realisation of the CO2 emission target of the Netherlands and increase the share of renewable energy in line with European agreements. This advice letter deals with one aspect of the broader considerations: the share of renewable electricity and the kind of incentive framework that is needed to achieve the target concerned. In this letter we will examine the possibilities of the SDE+ support (financial incentive for renewable energy) scheme and the supplier obligation, the effects on the market and the consequences for achieving the target. This letter closes with conclusions and recommendations. [nl

Proposal of Wireless Traffic Control Schemes for Wireless LANs

Science.gov (United States)

Hiraguri, Takefumi; Ichikawa, Takeo; Iizuka, Masataka; Kubota, Shuji

This paper proposes two traffic control schemes to support the communication quality of multimedia streaming services such as VoIP and audio/video over IEEE 802.11 wireless LAN systems. The main features of the proposed scheme are bandwidth control for each flow of the multimedia streaming service and load balancing between access points (APs) of the wireless LAN by using information of data link, network and transport layers. The proposed schemes are implemented on a Linux machine which is called the wireless traffic controller (WTC). The WTC connects a high capacity backbone network and an access network to which the APs are attached. We evaluated the performance of the proposed WTC and confirmed that the communication quality of the multimedia streaming would be greatly improved by using this technique.

Alphabetical: How Every Letter Tells a Story

OpenAIRE

Rosen, Michael

2013-01-01

From minding your Ps and Qs to wondering why X should mark the spot, Alphabetical is a book for everyone who loves words and language. Whether it's how letters are arranged on keyboards or Viking runes, textspeak or zip codes, this book will change the way you think about letters for ever. How on Earth did we fix upon our twenty-six letters, what do they really mean, and how did we come to write them down in the first place? Michael Rosen takes you on an unforgettable adventure through the hi...

Principles of wireless access and localization

CERN Document Server

Pahlavan, Kaveh

2013-01-01

A comprehensive, encompassing and accessible text examining a wide range of key Wireless Networking and Localization technologies This book provides a unified treatment of issues related to all wireless access and wireless localization techniques.  The book reflects principles of design and deployment of infrastructure for wireless access and localization for wide, local, and personal networking.   Description of wireless access methods includes design and deployment of traditional TDMA and CDMA technologies and emerging Long Term Evolution (LTE) techniques for wide area cellular networks, the

Wireless Technology in K-12 Education

Science.gov (United States)

Walery, Darrell

2004-01-01

Many schools begin implementing wireless technology slowly by creating wireless "hotspots" on the fly. This is accomplished by putting a wireless access point on a cart along with a set of wireless laptop computers. A teacher can then wheel the cart anywhere in the school that has a network drop, plug the access point in and have an…

Embedded Acoustic Sensor Array for Engine Fan Noise Source Diagnostic Test: Feasibility of Noise Telemetry via Wireless Smart Sensors

Science.gov (United States)

Zaman, Afroz; Bauch, Matthew; Raible, Daniel

2011-01-01

Aircraft engines have evolved into a highly complex system to meet ever-increasing demands. The evolution of engine technologies has primarily been driven by fuel efficiency, reliability, as well as engine noise concerns. One of the sources of engine noise is pressure fluctuations that are induced on the stator vanes. These local pressure fluctuations, once produced, propagate and coalesce with the pressure waves originating elsewhere on the stator to form a spinning pressure pattern. Depending on the duct geometry, air flow, and frequency of fluctuations, these spinning pressure patterns are self-sustaining and result in noise which eventually radiate to the far-field from engine. To investigate the nature of vane pressure fluctuations and the resulting engine noise, unsteady pressure signatures from an array of embedded acoustic sensors are recorded as a part of vane noise source diagnostics. Output time signatures from these sensors are routed to a control and data processing station adding complexity to the system and cable loss to the measured signal. "Smart" wireless sensors have data processing capability at the sensor locations which further increases the potential of wireless sensors. Smart sensors can process measured data locally and transmit only the important information through wireless communication. The aim of this wireless noise telemetry task was to demonstrate a single acoustic sensor wireless link for unsteady pressure measurement, and thus, establish the feasibility of distributed smart sensors scheme for aircraft engine vane surface unsteady pressure data transmission and characterization.

Investigation of interference in multiple-input multiple-output wireless transmission at W band for an optical wireless integration system.

Science.gov (United States)

Li, Xinying; Yu, Jianjun; Dong, Ze; Zhang, Junwen; Chi, Nan; Yu, Jianguo

2013-03-01

We experimentally investigate the interference in multiple-input multiple-output (MIMO) wireless transmission by adjusting the relative locations of horn antennas (HAs) in a 100 GHz optical wireless integration system, which can deliver a 50 Gb/s polarization-division-multiplexing quadrature-phase-shift-keying signal over 80 km single-mode fiber-28 and a 2×2 MIMO wireless link. For the parallel 2×2 MIMO wireless link, each receiver HA can only get wireless power from the corresponding transmitter HA, while for the crossover ones, the receiver HA can get wireless power from two transmitter HAs. At the wireless receiver, polarization demultiplexing is realized by the constant modulus algorithm (CMA) in the digital-signal-processing part. Compared to the parallel case, wireless interference causes about 2 dB optical signal-to-noise ratio penalty at a bit-error ratio (BER) of 3.8×10(-3) for the crossover cases if similar CMA taps are employed. The increase in CMA tap length can reduce wireless interference and improve BER performance. Furthermore, more CMA taps should be adopted to overcome the severe wireless interference when two pairs of transmitter and receiver HAs have different wireless distances.

Visual and Artistic Functions of Letters in Khaghani’s Poetry

Directory of Open Access Journals (Sweden)

Mohsen Zolfaghari

2013-11-01

Full Text Available Abstract The intensity of emotion and fluctuation of meaning in the poet's mind causes him to go beyond the ordinary language and convey intellectual and emotional meanings through metaphors, similes and linguistic preparations. He has sharp eyes and a sensitive spirit and creative temperament and attempts strengthening his own literary language and creating personal style by inventing novel images, showing the creativity and imagination and entering in various arenas of imagination. This point more than anything else could be done by presenting images and new figures. Perhaps in the sixth century, and especially in Azerbaijani school, more than other periods, poets have been looking for creating innovative style in eloquence. Their major attempts were mainly in imaging, a wide field that they have competed. It is obvious that in this illustration the alphabet letters would be very helpful. Khaghani's Divan of poetry, as one of the greatest poets of this school, is the perfect poetical book of paintings in which meaning has been hidden under a delicate pattern and new different scientific, cultural and religious images. Letters are a broad range of elements that put a new field in front of the poet and he is aware of the potential features of the letters, new images, and artistic creativity techniques as well. This paper shows descriptive - analytical study of various aspects of Khaghani’s poetry and frequency of letters in the alphabet letters, alphabetic-based authenticity of images, different similarity reasons, semantic and literal multi-relevance of letters in the context of poetry, producing figures of speech based on letters, sensational relationship exists between images and letters which have been shown in his poetry. Letter have a double and even multiple application in Khaghani's poetic works (divan and moreover the construction of words and conveying meaning which is the real and common usage, they were used as artistic instruments

Wireless and mobile systems in telemedicine

Directory of Open Access Journals (Sweden)

Reza Safdari

2012-12-01

Full Text Available Background: It is necessary to deploy mobile and wireless systems in healthcare, because they have many benefits for healthcare systems. The objectives of this article were introducing various systems, applications, and standards of the wireless and mobile telemedicine. Material and Methods: This review study was conducted in 2010. To conduct the study, published articles in the years 2005 to 2012, in English with an emphasis on wireless and mobile technologies in health were studied. Search was done with key words include telemedicine, wireless health systems, health and telecommunications technology in databases including Pubmed, Science Direct, Google Scholar, Web of Sciences, Proquest. The collected data were analyzed. Results: Telemedicine system in the ambulance, telemedicine systems in space, telecardiology systems, EEG system, ultrasound system are some types of wireless and mobile systems in telemedicine. PDA-based mobile and wireless telemedicine application, based PDA drug application, and patient tracking application are some of wireless and mobile applications of telemedicine. The most important standards of wireless and mobile telemedicine are HL7, DICOM, SNOMed, and ICD-9-CM. Conclusion: There are many challenges in the wireless and mobile systems in telemedicine, despite the many benefits. Slow speed in sending pictures and video, lack of attention to the privacy in the design of these systems, environmental variables and the number of users during the day are some of these challenges. It is recommended to consider these challenges during the planning and designing of wireless and mobile systems in telemedicine.

Letter position coding across modalities: the case of Braille readers.

Science.gov (United States)

Perea, Manuel; García-Chamorro, Cristina; Martín-Suesta, Miguel; Gómez, Pablo

2012-01-01

The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words. Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters. We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities. The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality) occur at a relatively late, abstract locus.

Digit and letter alexia in carbon monoxide poisoning

Institute of Scientific and Technical Information of China (English)

Qingyu Shen; Xiaoming Rong; Rui Pan; Ying Peng; Wei Peng; Yamei Tang

2012-01-01

This study examined a 24-year-old patient with delayed encephalopathy, who was admitted to hospital with complaints of headache and visual impairment 1 week after acute carbon monoxide poisoning. The results of a visual field assessment, electroencephalography and head magnetic resonance imaging indicated damage to the cerebral cortex. After a 2-week treatment period, the patient had recovered from the visual impairment, but exhibited digit- and letter-reading difficulty. The Chinese aphasia battery and the number and letter battery supplement were conducted. The results revealed that the patient exhibited digit and letter alexia, while the ability to read Chinese characters was preserved. In contrast, the patient exhibited a deficit in Chinese character writing, while number and letter writing remained intact. Following treatment, reading and writing ability was improved and electroencephalographic abnormalities were ameliorated. Overall, our experimental findings demonstrated that delayed encephalopathy following acute carbon monoxide poisoning was characterized by digit and letter alexia.

The Indirect Empathic Approach to Claim Letters.

Science.gov (United States)

Bell, James D.

1985-01-01

In discussing letter-writing methods for business communication classes, the article explains that claim letter formats other than the direct approach are not only legitimate, but also effective, and suggests that the approach selected should depend upon the circumstances surrounding the claim. (CT)

Culture and subculture in transactional letter writing

DEFF Research Database (Denmark)

Shaw, Philip; Okamura, Akiko

2000-01-01

This study examines the relative contributions of subculture membership and mother-tongue status/target culture membership in writing transactional letters. We examined the letters accompanying articles initially submitted for publication by 26 NSE and 23 NNSE academics, and compared them with ef...

The effect of various parameters of large scale radio propagation models on improving performance mobile communications

Science.gov (United States)

Pinem, M.; Fauzi, R.

2018-02-01

One technique for ensuring continuity of wireless communication services and keeping a smooth transition on mobile communication networks is the soft handover technique. In the Soft Handover (SHO) technique the inclusion and reduction of Base Station from the set of active sets is determined by initiation triggers. One of the initiation triggers is based on the strong reception signal. In this paper we observed the influence of parameters of large-scale radio propagation models to improve the performance of mobile communications. The observation parameters for characterizing the performance of the specified mobile system are Drop Call, Radio Link Degradation Rate and Average Size of Active Set (AS). The simulated results show that the increase in altitude of Base Station (BS) Antenna and Mobile Station (MS) Antenna contributes to the improvement of signal power reception level so as to improve Radio Link quality and increase the average size of Active Set and reduce the average Drop Call rate. It was also found that Hata’s propagation model contributed significantly to improvements in system performance parameters compared to Okumura’s propagation model and Lee’s propagation model.

Evaluation of wireless Local Area Networks

Science.gov (United States)

McBee, Charles L.

1993-09-01

This thesis is an in-depth evaluation of the current wireless Local Area Network (LAN) technologies. Wireless LAN's consist of three technologies: they are infrared light, microwave, and spread spectrum. When the first wireless LAN's were introduced, they were unfavorably labeled slow, expensive, and unreliable. The wireless LAN's of today are competitively priced, more secure, easier to install, and provide equal to or greater than the data throughput of unshielded twisted pair cable. Wireless LAN's are best suited for organizations that move office staff frequently, buildings that have historical significance, or buildings that have asbestos. Additionally, an organization may realize a cost savings of between $300 to $1,200 each time a node is moved. Current wireless LAN technologies have a positive effect on LAN standards being developed by the Defense Information System Agency (DISA). DoD as a whole is beginning to focus on wireless LAN's and mobile communications. If system managers want to remain successful, they need to stay abreast of this technology.

50 CFR 216.257 - Letters of Authorization.

Science.gov (United States)

2010-10-01

... ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking Marine Mammals Incidental to Conducting Precision Strike Weapon Missions in the Gulf of Mexico § 216.257 Letters of Authorization. (a) A Letter of Authorization, unless suspended or revoked...

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains nine separate letters on data on elastic (p,n) charge exchange: compilation, the potentialities of δ-electron control of luminosity in experiments with internal targets at the Nuclotron, pion broadening and low-mass dilepton production, fluctuation of electromagnetic cascade axis in dense amorphous segmented media, the forward detector of the ANKE spectrometer. Tracking system and its use in data analysis, quantum field theory with three-dimensional vector time, curvature decomposition and the Einstein-Yang-Mills equations, an integral equation for the spinor amplitude of a massive neutral Dirac particle in a curved space time with arbitrary geometry and surprising resonances in 147 Sm(nα) 144 Nd reaction

Wireless Sensor Network for Radiometric Detection and Assessment of Partial Discharge in High-Voltage Equipment

Science.gov (United States)

Upton, D. W.; Saeed, B. I.; Mather, P. J.; Lazaridis, P. I.; Vieira, M. F. Q.; Atkinson, R. C.; Tachtatzis, C.; Garcia, M. S.; Judd, M. D.; Glover, I. A.

2018-03-01

Monitoring of partial discharge (PD) activity within high-voltage electrical environments is increasingly used for the assessment of insulation condition. Traditional measurement techniques employ technologies that either require off-line installation or have high power consumption and are hence costly. A wireless sensor network is proposed that utilizes only received signal strength to locate areas of PD activity within a high-voltage electricity substation. The network comprises low-power and low-cost radiometric sensor nodes which receive the radiation propagated from a source of PD. Results are reported from several empirical tests performed within a large indoor environment and a substation environment using a network of nine sensor nodes. A portable PD source emulator was placed at multiple locations within the network. Signal strength measured by the nodes is reported via WirelessHART to a data collection hub where it is processed using a location algorithm. The results obtained place the measured location within 2 m of the actual source location.

Wireless Information-Theoretic Security in an Outdoor Topology with Obstacles: Theoretical Analysis and Experimental Measurements

Directory of Open Access Journals (Sweden)

Dagiuklas Tasos

2011-01-01

Full Text Available This paper presents a Wireless Information-Theoretic Security (WITS scheme, which has been recently introduced as a robust physical layer-based security solution, especially for infrastructureless networks. An autonomic network of moving users was implemented via 802.11n nodes of an ad hoc network for an outdoor topology with obstacles. Obstructed-Line-of-Sight (OLOS and Non-Line-of-Sight (NLOS propagation scenarios were examined. Low-speed user movement was considered, so that Doppler spread could be discarded. A transmitter and a legitimate receiver exchanged information in the presence of a moving eavesdropper. Average Signal-to-Noise Ratio (SNR values were acquired for both the main and the wiretap channel, and the Probability of Nonzero Secrecy Capacity was calculated based on theoretical formula. Experimental results validate theoretical findings stressing the importance of user location and mobility schemes on the robustness of Wireless Information-Theoretic Security and call for further theoretical analysis.

Wireless coexistence and interference test method for low-power wireless sensor networks

NARCIS (Netherlands)

Serra, R.; Nabi, Majid

2015-01-01

Wireless sensor networks (WSNs) are being increasingly introduced for critical applications such as safety, security and health. One the main characteristic requirements of such networks are that they should function with relative low power. Therefore the wireless links are more vulnerable.

Modeling and Performance Analysis of 10 Gbps Inter-satellite Optical Wireless Communication Link

Science.gov (United States)

Singh, Mehtab

2017-12-01

Free-space optical (FSO) communication has the advantages of two of the most predominant data transmission technologies - optical fiber communication and wireless communication. Most of the technical aspects of FSO are similar to that of optical fiber communication, with major difference in the information signal propagation medium which is free space in case of FSO rather than silica glass in optical fiber communication. One of the most important applications of FSO is inter-satellite optical wireless communication (IsOWC) links which will be deployed in the future in space. The IsOWC links have many advantages over the previously existing microwave satellite communication technologies such as higher bandwidth, lower power consumption, low cost of implementation, light size, and weight. In this paper, modeling and performance analysis of a 10-Gbps inter-satellite communication link with two satellites separated at a distance of 1,200 km has been done using OPTISYSTEM simulation software. Performance has been analyzed on the basis of quality factor, signal to noise ratio (SNR), and total power of the received signal.

Letter position coding across modalities: the case of Braille readers.

Directory of Open Access Journals (Sweden)

Manuel Perea

Full Text Available The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words.Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters.We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities.The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality occur at a relatively late, abstract locus.

Experimental test of contemporary mathematical models of visual letter recognition.

Science.gov (United States)

Townsend, J T; Ashby, F G

1982-12-01

A letter confusion experiment that used brief durations manipulated payoffs across the four stimulus letters, which were composed of line segments equal in length. The observers were required to report the features they perceived as well as to give a letter response. The early feature-sampling process is separated from the later letter-decision process in the substantive feature models, and predictions are thus obtained for the frequencies of feature report as well as letter report. Four substantive visual feature-processing models are developed and tested against one another and against three models of a more descriptive nature. The substantive models predict the decisional letter report phase much better than they do the feature-sampling phase, but the best overall 4 X 4 letter confusion matrix fits are obtained with one of the descriptive models, the similarity choice model. The present and other recent results suggest that the assumption that features are sampled in a stochastically independent manner may not be generally valid. The traditional high-threshold conceptualization of feature sampling is also falsified by the frequent reporting by observers of features not contained in the stimulus letter.

Novel method for water vapour monitoring using wireless communication networks measurements

Science.gov (United States)

David, N.; Alpert, P.; Messer, H.

2010-09-01

We propose a new technique for monitoring near-surface water vapour, by estimating humidity from data collected through existing wireless communication networks. Weather conditions and atmospheric phenomena affect the electromagnetic channel, causing attenuations to the radio signals. Thus, wireless communication networks are in effect built-in environmental monitoring facilities. The wireless microwave links, used in these networks, are widely deployed by cellular providers for backhaul communication between base stations, a few tens of meters above ground level. As a result, if all available measurements are used, the proposed method can provide moisture observations with high spatial resolution and potentially high temporal resolution. Further, the implementation cost is minimal, since the data used are already collected and saved by the cellular operators. In addition - many of these links are installed in areas where access is difficult such as orographic terrain and complex topography. As such, our method enables measurements in places that have been hard to measure in the past, or have never been measured before. The technique is restricted to weather conditions which exclude rain, fog or clouds along the propagation path. Strong winds that may cause movement of the link transmitter or receiver (or both) may also interfere with the ability to conduct accurate measurements. We present results from real-data measurements taken from microwave links used in a backhaul cellular network that show very good correlation with surface station humidity measurements (comparisons were performed for several links, found at different locations, during different time periods, showing correlations in the range of 0.5-0.9).

A Study on Wireless Charging for Prolonging the Lifetime of Wireless Sensor Networks.

Science.gov (United States)

Tu, Weijian; Xu, Xianghua; Ye, Tingcong; Cheng, Zongmao

2017-07-04

Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes in the network. Previous studies only consider a factor of the network (i.e., residual energy of sensor node) as a constraint to design the wireless charging strategy. However, other factors, such as the travelled distance of the mobile car, can also affect the effectiveness of wireless charging strategy. In this work, we study wireless charging strategy based on the analysis of a combination of two factors, including the residual energy of sensor nodes and the travelled distance of the charging car. Firstly, we theoretically analyze the limited size of the sensor network to match the capability of a charging car. Then, the networked factors are selected as the weights of traveling salesman problem (TSP) to design the moving path of the charging car. Thirdly, the charging time of each sensor node is computed based on the linear programming problem for the charging car. Finally, a charging period for the network is studied. The experimental results show that the proposed approach can significantly maximize the lifetime of the wireless sensor network.

A Study on Wireless Charging for Prolonging the Lifetime of Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Weijian Tu

2017-07-01

Full Text Available Wireless charging is an important issue in wireless sensor networks, since it can provide an emerging and effective solution in the absence of other power supplies. The state-of-the-art methods employ a mobile car and a predefined moving path to charge the sensor nodes in the network. Previous studies only consider a factor of the network (i.e., residual energy of sensor node as a constraint to design the wireless charging strategy. However, other factors, such as the travelled distance of the mobile car, can also affect the effectiveness of wireless charging strategy. In this work, we study wireless charging strategy based on the analysis of a combination of two factors, including the residual energy of sensor nodes and the travelled distance of the charging car. Firstly, we theoretically analyze the limited size of the sensor network to match the capability of a charging car. Then, the networked factors are selected as the weights of traveling salesman problem (TSP to design the moving path of the charging car. Thirdly, the charging time of each sensor node is computed based on the linear programming problem for the charging car. Finally, a charging period for the network is studied. The experimental results show that the proposed approach can significantly maximize the lifetime of the wireless sensor network.

Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm

Directory of Open Access Journals (Sweden)

Mi Jeong Kim

2015-07-01

Full Text Available In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA-based wireless mesh network (WMN with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation.

Distributed Synchronization Technique for OFDMA-Based Wireless Mesh Networks Using a Bio-Inspired Algorithm.

Science.gov (United States)

Kim, Mi Jeong; Maeng, Sung Joon; Cho, Yong Soo

2015-07-28

In this paper, a distributed synchronization technique based on a bio-inspired algorithm is proposed for an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network (WMN) with a time difference of arrival. The proposed time- and frequency-synchronization technique uses only the signals received from the neighbor nodes, by considering the effect of the propagation delay between the nodes. It achieves a fast synchronization with a relatively low computational complexity because it is operated in a distributed manner, not requiring any feedback channel for the compensation of the propagation delays. In addition, a self-organization scheme that can be effectively used to construct 1-hop neighbor nodes is proposed for an OFDMA-based WMN with a large number of nodes. The performance of the proposed technique is evaluated with regard to the convergence property and synchronization success probability using a computer simulation.

Introduction to Ultra Wideband for Wireless Communications

DEFF Research Database (Denmark)

Nikookar, Homayoun; Prasad, Ramjee

wireless channels, interference, signal processing as well as applications and standardization activities are addressed. Introduction to Ultra Wideband for Wireless Communications provides easy-to-understand material to (graduate) students and researchers working in the field of commercial UWB wireless......Ultra Wideband (UWB) Technology is the cutting edge technology for wireless communications with a wide range of applications. In Introduction to Ultra Wideband for Wireless Communications UWB principles and technologies for wireless communications are explained clearly. Key issues such as UWB...... communications. Due to tutorial nature of the book it can also be adopted as a textbook on the subject in the Telecommunications Engineering curriculum. Problems at the end of each chapter extend the reader's understanding of the subject. Introduction to Ultra Wideband for Wireless Communications will aslo...

Wireless rechargeable sensor networks

CERN Document Server

Yang, Yuanyuan

2015-01-01

This SpringerBrief provides a concise guide to applying wireless energy transfer techniques in traditional battery-powered sensor networks. It examines the benefits and challenges of wireless power including efficiency and reliability. The authors build a wireless rechargeable sensor networks from scratch and aim to provide perpetual network operation. Chapters cover a wide range of topics from the collection of energy information and recharge scheduling to joint design with typical sensing applications such as data gathering. Problems are approached using a natural combination of probability

When Do First Letters Mnemonics Aid Recall?

Science.gov (United States)

Morris, P. E.; Cook, N.

1978-01-01

The evidence for the effectiveness of the first letter mnemonic technique is confused. There are at least three studies showing no effect, and one where an improvement in recall occurred. Reports two experiments which attempted to locate the conditions under which the first letter mnemonic is effective. (Author/RK)

Radio Characterization for ISM 2.4 GHz Wireless Sensor Networks for Judo Monitoring Applications

Directory of Open Access Journals (Sweden)

Peio Lopez-Iturri

2014-12-01

Full Text Available In this work, the characterization of the radio channel for ISM 2.4GHz Wireless Sensor Networks (WSNs for judo applications is presented. The environments where judo activity is held are usually complex indoor scenarios in terms of radiopropagation due to their morphology, the presence of humans and the electromagnetic interference generated by personal portable devices, wireless microphones and other wireless systems used by the media. For the assessment of the impact that the topology and the morphology of these environments have on electromagnetic propagation, an in-house developed 3D ray-launching software has been used in this study. Time domain results as well as estimations of received power level have been obtained for the complete volume of a training venue of a local judo club’s facilities with a contest area with the dimensions specified by the International Judo Federation (IJF for international competitions. The obtained simulation results have been compared with measurements, which have been carried out deploying ZigBee-compliant XBee Pro modules at presented scenario, using approved Judogis (jacket, trousers and belt. The analysis is completed with the inclusion of an in-house human body computational model. Such analysis has allowed the design and development of an in house application devoted to monitor the practice of judo, in order to aid referee activities, training routines and to enhance spectator experience.

Extra-large letter spacing improves reading in dyslexia

Science.gov (United States)

Zorzi, Marco; Barbiero, Chiara; Facoetti, Andrea; Lonciari, Isabella; Carrozzi, Marco; Montico, Marcella; Bravar, Laura; George, Florence; Pech-Georgel, Catherine; Ziegler, Johannes C.

2012-01-01

Although the causes of dyslexia are still debated, all researchers agree that the main challenge is to find ways that allow a child with dyslexia to read more words in less time, because reading more is undisputedly the most efficient intervention for dyslexia. Sophisticated training programs exist, but they typically target the component skills of reading, such as phonological awareness. After the component skills have improved, the main challenge remains (that is, reading deficits must be treated by reading more—a vicious circle for a dyslexic child). Here, we show that a simple manipulation of letter spacing substantially improved text reading performance on the fly (without any training) in a large, unselected sample of Italian and French dyslexic children. Extra-large letter spacing helps reading, because dyslexics are abnormally affected by crowding, a perceptual phenomenon with detrimental effects on letter recognition that is modulated by the spacing between letters. Extra-large letter spacing may help to break the vicious circle by rendering the reading material more easily accessible. PMID:22665803

Numerical models and experiment of air flow in a simulation box for optical wireless communications

Directory of Open Access Journals (Sweden)

Latal Jan

2016-01-01

Full Text Available In this article, the authors focused on real measurements of mechanical turbulence generated by ventilators in the simulation box for Optical Wireless Communications. The mechanical turbulences disturb the optical beam that propagates along the central axis of the simulation box. The aim of authors is to show the effect of mechanical turbulence on optical beams at different heights in the simulation box. In the Ansys Fluent, we created numerical models which were then compared with real measurements. Authors compared the real and numerical models according to statistical methods.

Less wireless costs : optimizing firms aim to cut wireless service bills

International Nuclear Information System (INIS)

Mahony, J.

2006-01-01

The Calgary-based firm Alliance is offering optimized billing to oil companies, many of which spend more than $100,000 a month on wireless services for devices such as cellular telephones, pagers and Blackberries. In particular, Alliance is focusing on cutting the cost of wireless for corporate clients by analyzing client-usage patterns and choosing the most cost-efficient rate plans offered by the telecoms. Alliance suggests that do-it-yourself optimization is too complex for the average user, given the very large choice of rate plans. Using algorithms, Alliance software goes through all the wireless service contract options from the telecoms to choose the best plan for a company's needs. Optimizers claim their clients will see significant savings on wireless, in the order to 20 to 50 per cent. This article presented a brief case history of a successful optimization plan for Nabors Canada LP. Alliance allows its clients to view their billing information on their web-based server. Call records can be viewed by device or company division. 1 ref., 1 fig

The Predictive Validity of Teacher Candidate Letters of Reference

Science.gov (United States)

Mason, Richard W.; Schroeder, Mark P.

2014-01-01

Letters of reference are widely used as an essential part of the hiring process of newly licensed teachers. While the predictive validity of these letters of reference has been called into question it has never been empirically studied. The current study examined the predictive validity of the quality of letters of reference for forty-one student…

MIMO wireless networks channels, techniques and standards for multi-antenna, multi-user and multi-cell systems

CERN Document Server

Clerckx, Bruno

2013-01-01

This book is unique in presenting channels, techniques and standards for the next generation of MIMO wireless networks. Through a unified framework, it emphasizes how propagation mechanisms impact the system performance under realistic power constraints. Combining a solid mathematical analysis with a physical and intuitive approach to space-time signal processing, the book progressively derives innovative designs for space-time coding and precoding as well as multi-user and multi-cell techniques, taking into consideration that MIMO channels are often far from ideal. Reflecting developments

Teaching letter sounds to kindergarten English language learners using incremental rehearsal.

Science.gov (United States)

Peterson, Meredith; Brandes, Dana; Kunkel, Amy; Wilson, Jennifer; Rahn, Naomi L; Egan, Andrea; McComas, Jennifer

2014-02-01

Proficiency in letter-sound correspondence is important for decoding connected text. This study examined the effects of an evidence-based intervention, incremental rehearsal (IR), on the letter-sound expression of three kindergarten English language learners (ELLs) performing below the district benchmark for letter-sound fluency. Participants were native speakers of Hmong, Spanish, and Polish. A multiple-baseline design across sets of unknown letter sounds was used to evaluate the effects of IR on letter-sound expression. Visual analysis of the data showed an increase in level and trend when IR was introduced in each phase. Percentage of all non-overlapping data (PAND) ranged from 95% to 100%. All participants exceeded expected growth and reached the spring district benchmark for letter-sound fluency. Results suggest that IR is a promising intervention for increasing letter-sound expression for ELLs who evidence delays in acquiring letter sounds. Copyright © 2013 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

40 CFR 280.99 - Letter of credit.

Science.gov (United States)

2010-07-01

... (UST) Financial Responsibility § 280.99 Letter of credit. (a) An owner or operator may satisfy the... brackets are to be replaced with the relevant information and the brackets deleted: Irrevocable Standby.... We certify that the wording of this letter of credit is identical to the wording specified in 40 CFR...

Particles and Nuclei, Letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains eight separate letters on analysis of experimental data on relativistic nuclear collisions in the Lobachevski space, relativistic contribution of the final-state interaction to deuteron photodisintegration, on the charge asymmetry of the like-sign lepton pairs induced by B - B bar - production asymmetry, limits on the ν e → ν e neutrino oscillation parameters from an experiment at the IHEP-JINR neutrino detector, excitation of high spin isomers in photonuclear reactions, study of product formation in proton-nuclear reactions on the 129 I target induced by 660-MeV protons, application of jet pumps in the cryogenic system of the Nuclotron - superconducting accelerator of relativistic particles and study of the silicon drift detector performance with inclined tracks

Wireless motion sensor network for monitoring motion in a process, wireless sensor node, reasoning node, and feedback and/or actuation node for such wireless motion sensor network

NARCIS (Netherlands)

Havinga, Paul J.M.; Marin Perianu, Raluca; Marin Perianu, Mihai

2010-01-01

Wireless motion sensor network for monitoring motion in a process comprising at least one wireless sensor node for measuring at least one physical quantity related to motion or orientation, feature extraction means for deriving a feature for the measured quantities, a wireless transmitter connected

EEM{sup TM} wireless supervision

Energy Technology Data Exchange (ETDEWEB)

Bilic, H. [Ericsson-Nikola Tesla d.d. Zagreb (Croatia)

2000-07-01

By adding the GSM network to the communication level of Energy Management systems, energy operating centres (EOC) can offer wireless access to the supervised equipment. Furthermore EOC can profit from rapid service development in the GSM networks. With implementation of GPRS to the GSM network EOC can instantly offer wireless access to external IP based networks such as Internet and corporate Intranets. The author describes architecture and key characteristic of Ericsson EnergyMaster{sup TM} (EEM{sup TM}) system for Energy Management, how and where to implement wireless supervision, wireless access to IP addresses and also how to implement new services provided by the GSM network. (orig.)

An Improved Wireless Battery Charging System

OpenAIRE

Woo-Seok Lee; Jin-Hak Kim; Shin-Young Cho; Il-Oun Lee

2018-01-01

This paper presents a direct wireless battery charging system. The output current of the series-series compensated wireless power transfer (SS-WPT) system is used as a current source, and the output voltage of AC-DC converter controls the current source. Therefore, the proposed wireless battery charging system needs no battery charging circuit to carry out charging profiles, and can solve space constraints and thermal problems in many battery applications. In addition, the proposed wireless b...

A passive wireless ultrasound pitch–catch system

International Nuclear Information System (INIS)

Zahedi, F; Yao, J; Huang, H

2015-01-01

This paper exploits amplitude modulation and demodulation to achieve a passive wireless ultrasound pitch–catch system consisting of a wireless interrogator and a combination of a wireless actuator and a sensor mounted on a structure. The wireless interrogator operates in two modes, i.e. the generation and sensing modes. At the generation mode, the interrogator transmits two microwave signals; one is amplitude modulated with the ultrasound excitation signal while the other is a continuous-wave carrier signal. Once received by the wireless actuator, the amplitude modulated signal is demodulated using the carrier signal to recover the ultrasound excitation signal, which is then supplied to a piezoelectric wafer actuator for ultrasound generation. Subsequently, the interrogator is switched to the sensing mode by transmitting a carrier signal with a different frequency. Once received by the wireless sensor, this carrier signal is modulated with the ultrasound sensing signal acquired by the piezoelectric wafer sensor to produce an amplitude modulated microwave signal, which can then be wirelessly transmitted and demodulated by the interrogator to recover the original ultrasound sensing signal. The principle and implementation of the wireless ultrasound pitch–catch system as well as the data processing of the wirelessly received sensing signal are described. Experiment results validating wireless ultrasound generation and sensing from a distance of 0.5 m are presented. (paper)

Laboratory simulation of laser propagation through plasma sheaths containing ablation particles of ZrB2-SiC-C during hypersonic flight.

Science.gov (United States)

Zang, Qing; Bai, Xiangxing; Ma, Ping; Huang, Jie; Ma, Jing; Yu, Siyuan; Shi, Hongyan; Sun, Xiudong; Liu, Yang; Lu, Yueguang

2017-02-15

The optical communication method has potential for solving the blackout problem, which is a big challenge faced in the development of aerospace. Two laser transmission systems were set up to explore the influence of the plasma and the ablation particles on the propagation of the laser. The experimental results indicate that the laser can transmit through the plasma with little attenuation. When there are ablation particles of ZrB2-SiC-C added in the plasma, the intensity of the laser has fluctuations. The work introduced in this Letter can be regarded as basic research of the propagation characters of the laser through plasma sheaths.

A fast-multipole domain decomposition integral equation solver for characterizing electromagnetic wave propagation in mine environments

KAUST Repository

Yücel, Abdulkadir C.

2013-07-01

Reliable and effective wireless communication and tracking systems in mine environments are key to ensure miners\\' productivity and safety during routine operations and catastrophic events. The design of such systems greatly benefits from simulation tools capable of analyzing electromagnetic (EM) wave propagation in long mine tunnels and large mine galleries. Existing simulation tools for analyzing EM wave propagation in such environments employ modal decompositions (Emslie et. al., IEEE Trans. Antennas Propag., 23, 192-205, 1975), ray-tracing techniques (Zhang, IEEE Tran. Vehic. Tech., 5, 1308-1314, 2003), and full wave methods. Modal approaches and ray-tracing techniques cannot accurately account for the presence of miners and their equipments, as well as wall roughness (especially when the latter is comparable to the wavelength). Full-wave methods do not suffer from such restrictions but require prohibitively large computational resources. To partially alleviate this computational burden, a 2D integral equation-based domain decomposition technique has recently been proposed (Bakir et. al., in Proc. IEEE Int. Symp. APS, 1-2, 8-14 July 2012). © 2013 IEEE.

Study on characteristics of the aperture-averaging factor of atmospheric scintillation in terrestrial optical wireless communication

Science.gov (United States)

Shen, Hong; Liu, Wen-xing; Zhou, Xue-yun; Zhou, Li-ling; Yu, Long-Kun

2018-02-01

In order to thoroughly understand the characteristics of the aperture-averaging effect of atmospheric scintillation in terrestrial optical wireless communication and provide references for engineering design and performance evaluation of the optics system employed in the atmosphere, we have theoretically deduced the generally analytic expression of the aperture-averaging factor of atmospheric scintillation, and numerically investigated characteristics of the apertureaveraging factor under different propagation conditions. The limitations of the current commonly used approximate calculation formula of aperture-averaging factor have been discussed, and the results showed that the current calculation formula is not applicable for the small receiving aperture under non-uniform turbulence link. Numerical calculation has showed that aperture-averaging factor of atmospheric scintillation presented an exponential decline model for the small receiving aperture under non-uniform turbulent link, and the general expression of the model was given. This model has certain guiding significance for evaluating the aperture-averaging effect in the terrestrial optical wireless communication.

Photonic-assisted ultrafast THz wireless access

DEFF Research Database (Denmark)

Yu, Xianbin; Chen, Ying; Galili, Michael

THz technology has been considered feasible for ultrafast wireless data communi- cation, to meet the increasing demand on next-generation fast wireless access, e.g., huge data file transferring and fast mobile data stream access. This talk reviews recent progress in high-speed THz wireless...

The elaboration of motor programs for the automation of letter production.

Science.gov (United States)

Thibon, Laurence Séraphin; Gerber, Silvain; Kandel, Sonia

2018-01-01

We investigated how children learn to write letters. Letter writing evolves from stroke-by-stroke to whole-letter programming. Children of ages 6 to 9 (N=98) wrote letters of varying complexity on a digitizer. At ages 6 and 7 movement duration, dysfluency and trajectory increased with stroke number. This indicates that the motor program they activated mainly coded information on stroke production. Stroke number affected the older children's production much less, suggesting that they programmed stroke chunks or the whole letter. The fact that movement duration and dysfluency decreased from ages 6 to 8, and remained stable at ages 8 and 9 suggests that automation of letter writing begins at age 8. Automation seems to require the elaboration of stroke chunks and/or letter-sized motor programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Peer assessment of outpatient consultation letters – feasibility and satisfaction

Directory of Open Access Journals (Sweden)

Dojeiji Suzan

2007-05-01

Full Text Available Abstract Background Written correspondence is one of the most important forms of communication between health care providers, yet there is little feedback provided to specialists. The objective of this study was to determine the feasibility and satisfaction of a peer assessment program on consultation letters and to determine inter-rater reliability between family physicians and specialists. Methods A rating scale of nine 5-point Likert scale items including specific content, style items, education value of the letter and an overall rating was developed from a previous validated tool. Nine Internal Medicine specialists/subspecialists from two tertiary care centres submitted 10 letters with patient and physician identifiers removed. Two Internal Medicine specialists, and 2 family physicians from the other centre rated each letter (to protect writer anonymity. A satisfaction survey was sent to each writer and rater after collation of the results. A follow-up survey was sent 6–8 months later. Results There was a high degree of satisfaction with the process and feedback. The rating scale information was felt to be useful and appropriate for evaluating the quality of consultation letters by 6/7 writers. 5/7 seven writers felt that the feedback they received resulted in immediate changes to their letters. Six months later, 6/9 writers indicated they had maintained changes in their letters. Raters rank ordered letters similarly (Cronbach's alpha 0.57–0.84 but mean scores were highly variant. At site 1 there were significant differences in scoring brevity (p Conclusion Most participants found peer assessment of letters feasible and beneficial and longstanding changes occurred in some individuals. Family physicians and specialists appear to have different expectations on some items. Further studies on reliability and validity, with a larger sample, are required before high stakes professional assessments include consultation letters.

Green heterogeneous wireless networks

CERN Document Server

Ismail, Muhammad; Nee, Hans-Peter; Qaraqe, Khalid A; Serpedin, Erchin

2016-01-01

This book focuses on the emerging research topic "green (energy efficient) wireless networks" which has drawn huge attention recently from both academia and industry. This topic is highly motivated due to important environmental, financial, and quality-of-experience (QoE) considerations. Specifically, the high energy consumption of the wireless networks manifests in approximately 2% of all CO2 emissions worldwide. This book presents the authors’ visions and solutions for deployment of energy efficient (green) heterogeneous wireless communication networks. The book consists of three major parts. The first part provides an introduction to the "green networks" concept, the second part targets the green multi-homing resource allocation problem, and the third chapter presents a novel deployment of device-to-device (D2D) communications and its successful integration in Heterogeneous Networks (HetNets). The book is novel in that it specifically targets green networking in a heterogeneous wireless medium, which re...

Security For Wireless Sensor Network

OpenAIRE

Saurabh Singh,; Dr. Harsh Kumar Verma

2011-01-01

Wireless sensor network is highly vulnerable to attacks because it consists of various resourceconstrained devices with their low battery power, less memory, and associated low energy. Sensor nodescommunicate among themselves via wireless links. However, there are still a lot of unresolved issues in wireless sensor networks of which security is one of the hottest research issues. Sensor networks aredeployed in hostile environments. Environmental conditions along with resource-constraints give...

Pseudo-synesthesia through reading books with colored letters.

Directory of Open Access Journals (Sweden)

Olympia Colizoli

Full Text Available BACKGROUND: Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter 'a' always appears as light blue. In this study, we examine whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color. METHODOLOGY/PRINCIPAL FINDINGS: Non-synesthetes were given specially prepared colored books to read. A modified Stroop task was administered before and after reading. A perceptual crowding task was administered after reading. Reading one book (>49,000 words was sufficient to induce effects regarded as behavioral markers for synesthesia. The results of the Stroop tasks indicate that it is possible to learn letter-color associations through reading in color (F(1, 14 = 5.85, p = .030. Furthermore, Stroop effects correlated with subjective reports about experiencing letters in color (r(13 = 0.51, p = .05. The frequency of viewing letters is related to the level of association as seen by the difference in the Stroop effect size between upper- and lower-case letters (t(14 = 2.79, p = .014 and in a subgroup of participants whose Stroop effects increased as they continued to read in color. Readers did not show significant performance advantages on the crowding task compared to controls. Acknowledging the many differences between trainees and synesthetes, results suggest that it may be possible to acquire a subset of synesthetic behavioral traits in adulthood through training. CONCLUSION/SIGNIFICANCE: To our knowledge, this is the first evidence of acquiring letter-color associations through reading in color. Reading in color appears to be a promising avenue in which we may explore the differences and similarities between synesthetes and non-synesthetes. Additionally, reading in color is a plausible method for a long-term 'synesthetic' training program.

Emerging wireless networks concepts, techniques and applications

CERN Document Server

Makaya, Christian

2011-01-01

An authoritative collection of research papers and surveys, Emerging Wireless Networks: Concepts, Techniques, and Applications explores recent developments in next-generation wireless networks (NGWNs) and mobile broadband networks technologies, including 4G (LTE, WiMAX), 3G (UMTS, HSPA), WiFi, mobile ad hoc networks, mesh networks, and wireless sensor networks. Focusing on improving the performance of wireless networks and provisioning better quality of service and quality of experience for users, it reports on the standards of different emerging wireless networks, applications, and service fr

Introduction to wireless sensor networks

CERN Document Server

Forster, Anna

2016-01-01

Explores real-world wireless sensor network development, deployment, and applications. The book begins with an introduction to wireless sensor networks and their fundamental concepts. Hardware components, operating systems, protocols, and algorithms that make up the anatomy of a sensor node are described in chapter two. Properties of wireless communications, medium access protocols, wireless links, and link estimation protocols are described in chapter three and chapter four. Routing basics and metrics, clustering techniques, time synchronization and localization protocols, as well as sensing techniques are introduced in chapter five to nine. The concluding chapter summarizes the learnt methods and shows how to use them to deploy real-world sensor networks in a structured way.

Letter of Map Revision

Data.gov (United States)

Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

OIT Wireless Telemetry for Industrial Applications

Energy Technology Data Exchange (ETDEWEB)

Manges, WW

2002-09-03

The need for advanced wireless technology has been identified in the National Research Council publication (1) ''Manufacturing Process Controls for the Industries of the Future as a Critical Technology for the Future''. The deployment challenges to be overcome in order for wireless to be a viable option include: (1) eliminating interference (assuring reliable communications); (2) easing the deployment of intelligent, wireless sensors; (3) developing reliable networks (robust architectures); (4) developing remote power (long-lasting and reliable); and (5) developing standardized communication protocols. This project demonstrated the feasibility of robust wireless sensor networks that could meet these requirements for the harsh environments common to the DOE/OIT Industries of the Future. It resulted in a wireless test bed that was demonstrated in a paper mill and a steel plant. The test bed illustrated key protocols and components that would be required in a real-life, wireless network. The technologies for low power connectivity developed and demonstrated at the plant eased fears that the radios would interfere with existing control equipment. The same direct sequence, spread spectrum (DSSS) technology that helped assure the reliability of the connection also demonstrated that wireless communication was feasible in these plants without boosting the transmitted power to dangerous levels. Our experience and research have indicated that two key parameters are of ultimate importance: (1) reliability and (2) inter-system compatibility. Reliability is the key to immediate acceptance among industrial users. The importance cannot be overstated, because users will not tolerate an unreliable information network. A longer term issue that is at least as important as the reliability of a single system is the inter-system compatibility between these wireless sensor networks and other wireless systems that are part of our industries. In the long run, the

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains nine separate letters on nonlocal chiral quark model with confinement, perturbation of finite-lattice spectral levels by nearby nuclear resonances, on the application of 'Z 0 + jet' events for determining the gluon distribution in a proton at the LHC, account of light velocity constancy in the Galilean problem on the free movement of a particle and its fall onto the ground, first results of crystal deflector investigations at the Nuclotron external beams, decay parameters of K mesons, measured at proton synchrotron U-70 using 'Hyperon' set-up and modern world data, prototype of atomic-emission spectrometer on the basis of one-electrode impulse RF discharge for analytical measurements, polarimeter for Nuclotron internal beam and primordial bubbles of colour superconducting quark matter

Voice Quality Estimation in Wireless Networks

Directory of Open Access Journals (Sweden)

Petr Zach

2015-01-01

Full Text Available This article deals with the impact of Wireless (Wi-Fi networks on the perceived quality of voice services. The Quality of Service (QoS metrics must be monitored in the computer network during the voice data transmission to ensure proper voice service quality the end-user has paid for, especially in the wireless networks. In addition to the QoS, research area called Quality of Experience (QoE provides metrics and methods for quality evaluation from the end-user’s perspective. This article focuses on a QoE estimation of Voice over IP (VoIP calls in the wireless networks using network simulator. Results contribute to voice quality estimation based on characteristics of the wireless network and location of a wireless client.

Intrusion detection in wireless ad-hoc networks

CERN Document Server

Chaki, Nabendu

2014-01-01

Presenting cutting-edge research, Intrusion Detection in Wireless Ad-Hoc Networks explores the security aspects of the basic categories of wireless ad-hoc networks and related application areas. Focusing on intrusion detection systems (IDSs), it explains how to establish security solutions for the range of wireless networks, including mobile ad-hoc networks, hybrid wireless networks, and sensor networks.This edited volume reviews and analyzes state-of-the-art IDSs for various wireless ad-hoc networks. It includes case studies on honesty-based intrusion detection systems, cluster oriented-based

Design of Compact Flower Shape Dual Notched-Band Monopole Antenna for Extended UWB Wireless Applications

Science.gov (United States)

Sharma, Manish; Awasthi, Y. K.; Singh, Himanshu; Kumar, Raj; Kumari, Sarita

2016-11-01

In this letter, a compact monopole antenna for ultra wideband (UWB) applications is proposed with small size of 18×20=360 mm2. Antenna consist of a flower shape radiating patch with a pair of C-shaped slots which offer two notch bands for WiMAX (3.04-3.68 GHz) & WLAN (4.73-5.76 GHz) and two rectangular shaped slots in the ground plane which provides a wide measured usable fractional extended bandwidth of 163 % (2.83-14.0 GHz) with improved VSWR. Moreover, it is also convenient for other wireless application as close range radar, 8-12 GHz in X-band. Measured radiation patterns exhibits nearly omnidirectional in H-plane and dipole like pattern in E-plane across the bandwidth and furthermore exhibits good time domain performance.

Evolution of Heterogeneous Wireless Networks

DEFF Research Database (Denmark)

Zhang, Q.; Fitzek, Frank; Katz, Marcos

2006-01-01

Mobile and wireless content, services and networks - Short-term and long-term development trends......Mobile and wireless content, services and networks - Short-term and long-term development trends...

Patient information letters on nutrition: development and implementation.

NARCIS (Netherlands)

Binsbergen, J.J. van; Drenthen, A.J.

2003-01-01

BACKGROUND: In 1998 the Dutch College of General Practitioners (NHG) began developing patient information letters (PILs), based on the practice guidelines for family physicians (FPs) (NHG standards). Five nutritional guidance letters have since been developed with the Dutch Nutrition Center.

Energy-efficient wireless mesh infrastructures

OpenAIRE

Al-Hazmi, Y.; de Meer, Hermann; Hummel, Karin Anna; Meyer, Harald; Meo, Michela; Remondo Bueno, David

2011-01-01

The Internet comprises access segments with wired and wireless technologies. In the future, we can expect wireless mesh infrastructures (WMIs) to proliferate in this context. Due to the relatively low energy efficiency of wireless transmission, as compared to wired transmission, energy consumption of WMIs can represent a significant part of the energy consumption of the Internet as a whole. We explore different approaches to reduce energy consumption in WMIs, taking into accoun...

Performance Analysis of IIUM Wireless Campus Network

International Nuclear Information System (INIS)

Latif, Suhaimi Abd; Masud, Mosharrof H; Anwar, Farhat

2013-01-01

International Islamic University Malaysia (IIUM) is one of the leading universities in the world in terms of quality of education that has been achieved due to providing numerous facilities including wireless services to every enrolled student. The quality of this wireless service is controlled and monitored by Information Technology Division (ITD), an ISO standardized organization under the university. This paper aims to investigate the constraints of wireless campus network of IIUM. It evaluates the performance of the IIUM wireless campus network in terms of delay, throughput and jitter. QualNet 5.2 simulator tool has employed to measure these performances of IIUM wireless campus network. The observation from the simulation result could be one of the influencing factors in improving wireless services for ITD and further improvement

Integration of RFID and Wireless Sensor Networks

Institute of Scientific and Technical Information of China (English)

Miodrag; Bolic; Amiya; Nayak; Ivan; Stojmenovi.

2007-01-01

Radio Frequency Identification (RFID) and Wireless Sensor Network (WSN) are two important wireless technologies that have wide variety of applications and provide limitless future potentials. However,RFID and sensor networks almost are under development in parallel way. Integration of RFID and wireless sensor networks attracts little attention from research community. This paper first presents a brief introduction on RFID,and then investigates recent research works,new products/patents and applications that integrate RFID with sensor networks. Four types of integration are discussed. They are integrating tags with sensors,integrating tags with wireless sensor nodes,integrating readers with wireless sensor nodes and wire-less devices,and mix of RFID and sensors. New challenges and future works are discussed in the end.

Color associations for days and letters across different languages

Science.gov (United States)

Rouw, Romke; Case, Laura; Gosavi, Radhika; Ramachandran, Vilayanur

2014-01-01

While colors are commonplace in everyday metaphors, relatively little is known about implicit color associations to linguistic or semantic concepts in a general population. In this study, we test color associations for ordered linguistic concepts (letters and days). The culture and language specificity of these effects was examined in a large group (457) of Dutch-speaking participants, 92 English-speaking participants, and 49 Hindi-speaking participants. Non-random distributions of color choices were revealed; consistencies were found across the three language groups in color preferences for both days and letters. Interestingly, while the Hindi-speaking participants were presented with letter stimuli matched on phonology, their pattern of letter-to-color preferences still showed similarities with Dutch- and English-speaking participants. Furthermore, we found that that the color preferences corresponded between participants indicating to have conscious color experiences with letters or days (putative synesthetes) and participants who do not (non-synesthetes). We also explored possible mechanisms underlying the color preferences. There were a few specific associations, including red for “A,” red for “Monday,” and white for “Sunday.” We also explored more general mechanisms, such as overall color preferences as shown by Simner et al. (2005). While certainly not all variation can be explained or predicted, the results show that regularities are present in color-to-letter or color-to-day preferences in both putative synesthetes and non-synesthetes across languages. Both letter-to-color and day-to-color preferences were influenced by multiple factors. The findings support a notion of abstract concepts (such as days and letters) that are not represented in isolation, but are connected to perceptual representational systems. Interestingly, at least some of these connections to color representations are shared across different language/cultural groups. PMID

Color associations for days and letters across different languages

Directory of Open Access Journals (Sweden)

Romke eRouw

2014-05-01

Full Text Available While colors are commonplace in everyday metaphors, relatively little is known about implicit color associations to linguistic or semantic concepts in a general population. In this study, we test color associations for ordered linguistic concepts (letters and days. The culture and language specificity of these effects was examined in a large group (457 of Dutch-speaking participants, 92 English-speaking participants, and 49 Hindi-speaking participants. Non-random distributions of color choices were revealed; consistencies were found across the three language groups in color preferences for both days and letters. Interestingly, while the Hindi-speaking participants were presented with letter stimuli matched on phonology, their pattern of letter-to-color preferences still showed similarities with Dutch- and English-speaking participants. Furthermore, we found that that the color preferences corresponded between participants indicating to have conscious color experiences with letters or days (putative synesthetes and participants who do not (non-synesthetes. We also explored possible mechanisms underlying the color preferences. There were a few specific associations, including red for A, red for Monday, and white for Sunday. We also explored more general mechanisms, such as overall color preferences shown by Simner et al (2005. While certainly not all variation can be explained or predicted, the results show that regularities are present in color-to-letter or color-to-day preferences in both putative synesthetes and non-synesthetes across languages. Both letter-to-color and day-to-color preferences were influenced by multiple factors. The findings support a notion of abstract concepts (such as days and letters that are not represented in isolation, but are connected to perceptual representational systems. Interestingly, at least some of these connections to color representations are shared across different language/cultural groups.

Michelangelo, a Tireless Letter Writer

Directory of Open Access Journals (Sweden)

Adelin Charles Fiorato

2014-04-01

Full Text Available A titan of artistic creation, the sculptor-painter-architect Michelangelo was also a tireless letter writer. Five hundred and eighteen of his letters have reached us, stretching from his youth to the eve of his death, but we know that many others have been lost. Written in a kind of familiar Florentine and in a style of minimalist ‘realism’ – which does not prevent the presence of either impetuous polemical flights or pages of literary indulgence – these letters deal mainly with everyday subjects: day-by-day relationships, either endearing or resentful, with his relatives, financial or property matters and, above all, the marriage problems which concerned his nephew Leonardo, the sole heir of the family. But one also discovers in them the artist’s warm feelings of friendship and love, his poetic and aesthetic exchanges, his relationships, often conflictual, with his fellow-artists and patrons as well as his reflections on old age and death. All in all, these letters represent a documentary chronicle of a Florentine bourgeois family and the technical hassle of an entrepreneur’s activity. If, on the one hand, the Carteggio does not shed light either on Michelangelo’s conception of art or the way in which he realized his works, on the other it illustrates certain latent aspects of his projects, as well as of his personality, which was at the same time melancholy and aggressive, surprisingly whole and manifold. This luxuriant correspondence presents, so to speak, a ‘genetic’ interest, since it reveals the hidden face of the brilliant conceiver and creator, of the artist and entrepreneur struggling with the obstacles whose overcoming makes creation possible. 

How To Write a Business Letter. Power of the Printed Word.

Science.gov (United States)

Forbes, Malcolm

Business letters should turn people on rather than turning them off. To write a good business letter, know what the goal is before starting to write, call the reader by name, tell what the letter is about in the first paragraph, refer to dates when answering letters, and write from the reader's point of view. Be positive, be nice, and be natural.…

Using Wireless Network Coding to Replace a Wired with Wireless Backhaul

DEFF Research Database (Denmark)

Thomsen, Henning; De Carvalho, Elisabeth; Popovski, Petar

2014-01-01

of wireless emulated wire (WEW), based on two-way relaying and network coding. This setup leads to a new type of broadcast problem, with decoding conditions that are specific to the requirement for equivalence to the wired backhaul. We formulate and solve the associated optimization problems. The proposed...... approach is a convincing argument that wireless backhauling solutions should be designed and optimized for two-way communication....

DISA Wireless E-Mail Trial

National Research Council Canada - National Science Library

Haney, Steven

1997-01-01

.... Correspondingly unique wireless modems were obtained and mated to the PCMCIA slot of notebook computers in the user/evaluation population, consisting of InfoTac and Mobedem wireless modems for use...

DOCUMENTARY LETTER OF CREDIT IN THE REGULATION OF 600-PARIS PUBLICATION

Directory of Open Access Journals (Sweden)

VASILE NEMES

2011-04-01

Full Text Available In the year 2007 was adopted the Publication no. 600 of Paris regarding the Rules and the Uniform Practices for documentary letters of credit which replaced the Publication no. 500. Publication no. 600 (UCP 600 is applied to all the irrevocable documentary letters of credit when the parties make express reference to these Rules. The Publication no. 600 includes uniform rules, international practices and standards of irrevocable documentary letters of credit. The new Publication has brought a number of changes on the issues regarding the performance of the letters of credit, both in the relationship with the nonbanking institutions participants and in the relationship between the credit institutions participating in the performance of the letter of credit. This study, without being exhaustive, aims to capture the main aspects of novelty brought by the publication no. 600 and their legal approach to the new perspective of the international trade relations. It has in view, in particular, the irrevocable character of the letter of credit, the elaboration method and procedure of the letter of credit, the participants to the unfolding of the specific relationship of the letter of credit and the main duties of the involved credit institutions.

Return to sender: Constantijn Huygens as a man of letters

NARCIS (Netherlands)

Gosseye, L.; Blom, F.; Leerintveld, A.

2013-01-01

Return to Sender takes as its starting point Constantijn Huygens’ letters and shows us the author in his different guises: intimus of René Descartes, translator of John Donne, collector of art, writer of flirtatious love letters and the author of a long consolatory letter-poem for an ailing friend

Evidence for magnocellular involvement in the identification of flanked letters

NARCIS (Netherlands)

Omtzigt, D.; Hendriks, A.W.C.J.; Kolk, H.H.J.

2002-01-01

Little is known about the role of the magno system in reading. One important hypothesis is that this system is involved in the allocation of attention. We reasoned that the presentation of a single letter automatically draws attention to this letter, whereas in the case of a flanked letter, an

Cooperative Diversity in Wireless Networks

Directory of Open Access Journals (Sweden)

A. Mahmood

2010-01-01

Full Text Available Transmit Diversity is an effective methodology for improving the quality and reliability of a wireless network by reducingthe effects of fading. As majority of the wireless devices (i.e. mobile handsets, etc are limited to only one antenna, especiallydue to hardware constraints, size and cost factors; cooperative communication can be utilized in order to generatetransmit diversity [1]. This enables single antenna wireless devices to share their antennas during transmission in such amanner that creates a virtual MIMO (multiple-input and multiple-output system [2] [3]. In this paper, we will analyze therecent developments and trends in this promising area of wireless Ad hoc networks. The article will also discuss variousmain cooperative signaling methods and will also observe their performance.

Letter to Carl Niigeli

Indian Academy of Sciences (India)

We reproduce an english translation of one of these letters below, in which ... contemporary scientific knowledge, and that under the circumstances ... generation it became necessary to limit the numbers because of lack of space, so that, in.

Low-Power Wireless Sensor Network Infrastructures

DEFF Research Database (Denmark)

Hansen, Morten Tranberg

Advancements in wireless communication and electronics improving form factor and hardware capabilities has expanded the applicability of wireless sensor networks. Despite these advancements, devices are still limited in terms of energy which creates the need for duty-cycling and low-power protocols...... peripherals need to by duty-cycled and the low-power wireless radios are severely influenced by the environmental effects causing bursty and unreliable wireless channels. This dissertation presents a communication stack providing services for low-power communication, secure communication, data collection......, and network management which enables construction of low-power wireless sensor network applications. More specifically, these services are designed with the extreme low-power scenarios of the SensoByg project in mind and are implemented as follows. First, low-power communication is implemented with Auto...

Capacity Analysis of Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

M. I. Gumel

2012-06-01

Full Text Available The next generation wireless networks experienced a great development with emergence of wireless mesh networks (WMNs, which can be regarded as a realistic solution that provides wireless broadband access. The limited available bandwidth makes capacity analysis of the network very essential. While the network offers broadband wireless access to community and enterprise users, the problems that limit the network capacity must be addressed to exploit the optimum network performance. The wireless mesh network capacity analysis shows that the throughput of each mesh node degrades in order of l/n with increasing number of nodes (n in a linear topology. The degradation is found to be higher in a fully mesh network as a result of increase in interference and MAC layer contention in the network.

Letters of intent

International Nuclear Information System (INIS)

Anon.

1993-01-01

Thursday 5 November was another major milestone en route to the establishment of the experimental programme for CERN's LHC protonproton collider to be built in the 27- kilometre LEP tunnel. After initial discussions of 'Expressions of Interest' at the specially arranged meeting at Evian-les-Bains, France, earlier this year (May, page 1), three Letters of Intent have emerged, together involving nearly 2000 physicists from research institutes all over the world. As well as these researchers listed on the documents, the plans in fact involve many additional technical specialists who work behind the scenes. It was a historic moment as these three detector proposals were aired at the first open meeting of the new LHC Experiments Committee. CERN's main auditorium and a large overflow room receiving relayed video pictures were both packed. From these three schemes - ATLAS, CMS and L3P - and the first reactions to their letters of intent, eventually two projects will emerge, for which full technical proposals will be prepared, including construction plans and credible costings

Pseudo-synesthesia through reading books with colored letters

NARCIS (Netherlands)

Colizoli, O.; Murre, J.M.J.; Rouw, R.

2012-01-01

Background Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter ‘a’ always appears as light blue). In this study, we examine whether traits

Letters on nuclear controversy

International Nuclear Information System (INIS)

Kafka, P.; Maier-Leibnitz, H.

1982-01-01

Heinz Maier-Leibnitz a well-known scientist, nuclear physicist, for 50 years, who publicily supported the idea not to overrate the dangers of peaceful utilization of nuclear energy, has grown tired of talking only to colleagues. He invites a junior fellow physicist, who held engaged speeches against the nuclear power plant Zwentendorf, to an exchange of thoughts. Peter Kafka, an astro-physicist studied the self organisation of the universe from the big bang to the economic crisis and encountered the question of which conditions have to be fulfilled to prevent progress from becoming caranogenous. He became one of the spokesmen of 'political ecology' and called for resistance again large-scale technological use of scientific knowledge. He was enthusiastic about the idea of an exchange of letters, because he - just like his partner - believes in gaining knowledge by discussion. The variety of subjects is sketched briefly in form of three lectures. In the letters both scientists discuss intensly about: - Freedom of science and responsibility of science. - Decisions on energy questions under time-pressure. - Risks of nuclear plants. - Large scale technology and large-scale research or decentralization. - Energy utilization and energy waste. - Nuclear energy and alternatives. - Sense and nonsense of detailed future planning. In the end no one has convinced the other. The reader however finds a lot of new incentives in the letters - printed in unabridged form - a lot of new and significant arguments for a discussion which has only just started. (orig.) [de

Wireless body sensor networks for health-monitoring applications

International Nuclear Information System (INIS)

Hao, Yang; Foster, Robert

2008-01-01

Current wireless technologies, such as wireless body area networks and wireless personal area networks, provide promising applications in medical monitoring systems to measure specified physiological data and also provide location-based information, if required. With the increasing sophistication of wearable and implantable medical devices and their integration with wireless sensors, an ever-expanding range of therapeutic and diagnostic applications is being pursued by research and commercial organizations. This paper aims to provide a comprehensive review of recent developments in wireless sensor technology for monitoring behaviour related to human physiological responses. It presents background information on the use of wireless technology and sensors to develop a wireless physiological measurement system. A generic miniature platform and other available technologies for wireless sensors have been studied in terms of hardware and software structural requirements for a low-cost, low-power, non-invasive and unobtrusive system. (topical review)

Transposed-letter priming of prelexical orthographic representations.

Science.gov (United States)

Kinoshita, Sachiko; Norris, Dennis

2009-01-01

A prime generated by transposing two internal letters (e.g., jugde) produces strong priming of the original word (judge). In lexical decision, this transposed-letter (TL) priming effect is generally weak or absent for nonword targets; thus, it is unclear whether the origin of this effect is lexical or prelexical. The authors describe the Bayesian Reader theory of masked priming (D. Norris & S. Kinoshita, 2008), which explains why nonwords do not show priming in lexical decision but why they do in the cross-case same-different task. This analysis is followed by 3 experiments that show that priming in this task is not based on low-level perceptual similarity between the prime and target, or on phonology, to make the case that priming is based on prelexical orthographic representation. The authors then use this task to demonstrate equivalent TL priming effects for nonwords and words. The results are interpreted as the first reliable evidence based on the masked priming procedure that letter position is not coded absolutely within the prelexical, orthographic representation. The implications of the results for current letter position coding schemes are discussed.

Wireless networking for the dental office: current wireless standards and security protocols.

Science.gov (United States)

Mupparapu, Muralidhar; Arora, Sarika

2004-11-15

Digital radiography has gained immense popularity in dentistry today in spite of the early difficulty for the profession to embrace the technology. The transition from film to digital has been happening at a faster pace in the fields of Orthodontics, Oral Surgery, Endodontics, Periodontics, and other specialties where the radiographic images (periapical, bitewing, panoramic, cephalometric, and skull radiographs) are being acquired digitally, stored within a server locally, and eventually accessed for diagnostic purposes, along with the rest of the patient data via the patient management software (PMS). A review of the literature shows the diagnostic performance of digital radiography is at least comparable to or even better than that of conventional radiography. Similarly, other digital diagnostic tools like caries detectors, cephalometric analysis software, and digital scanners were used for many years for the diagnosis and treatment planning purposes. The introduction of wireless charged-coupled device (CCD) sensors in early 2004 (Schick Technologies, Long Island City, NY) has moved digital radiography a step further into the wireless era. As with any emerging technology, there are concerns that should be looked into before adapting to the wireless environment. Foremost is the network security involved in the installation and usage of these wireless networks. This article deals with the existing standards and choices in wireless technologies that are available for implementation within a contemporary dental office. The network security protocols that protect the patient data and boost the efficiency of modern day dental clinics are enumerated.

Insights from developmental and acquired letter position dyslexia on morphological decomposition in reading

Directory of Open Access Journals (Sweden)

Naama eFriedmann

2015-07-01

Full Text Available We explored morphological decomposition in reading, the locus in the reading process in which it takes place and its nature, comparing different types of morphemes. We assessed these questions through the analysis of letter position errors in readers with letter position dyslexia(LPD. LPD is a selective impairment to letter position encoding in the early stage of word reading, which results in letter migrations (cloud-could. We used the fact that migrations in LPD occur mainly in word-interior letters, whereas exterior letters rarely migrate.The rationale was that if morphological decomposition occurs prior to letter position encoding and strips off affixes, word-interior letters adjacent to an affix (signs-signs would become exterior following affix-stripping and hence exhibit fewer migrations.We tested 11 Hebrew readers with developmental LPD and 1 with acquired LPD in 6 experiments of reading aloud, lexical decision, and comprehension, at the single word and sentence levels. We examined migrations next to inflectional,derivational,or bound function morphemes compared with exterior letters.Root letters adjacent to inflectional and derivational morphemes were treated like middle letters, and migrated frequently, whereas root letters adjacent to bound function morphemes patterned with exterior letters, and almost never migrated. Given that LPD is a pre-lexical deficit, these results indicate that morphological decomposition takes place in an early, pre-lexical stage. Morphologically complex nonwords showed the same pattern, indicating that this decomposition is structurally, rather than lexically, driven.We suggest that letter position encoding takes place before morphological analysis, but in some cases, as with bound function morphemes, the complex word is re-analyzed as two separate words. In this reanalysis, letter positions in each constituent word are encoded separately,and hence the exterior letters of the root are treated as exterior and

Wireless Power Transfer and Data Collection in Wireless Sensor Networks

OpenAIRE

Li, Kai; Ni, Wei; Duan, Lingjie; Abolhasan, Mehran; Niu, Jianwei

2017-01-01

In a rechargeable wireless sensor network, the data packets are generated by sensor nodes at a specific data rate, and transmitted to a base station. Moreover, the base station transfers power to the nodes by using Wireless Power Transfer (WPT) to extend their battery life. However, inadequately scheduling WPT and data collection causes some of the nodes to drain their battery and have their data buffer overflow, while the other nodes waste their harvested energy, which is more than they need...

Security Threats on Wireless Sensor Network Protocols

OpenAIRE

H. Gorine; M. Ramadan Elmezughi

2016-01-01

In this paper, we investigate security issues and challenges facing researchers in wireless sensor networks and countermeasures to resolve them. The broadcast nature of wireless communication makes Wireless Sensor Networks prone to various attacks. Due to resources limitation constraint in terms of limited energy, computation power and memory, security in wireless sensor networks creates different challenges than wired network security. We will discuss several attempts at addressing the issue...

Wireless Power Supply via Coupled Magnetic Resonance for on-line Monitoring Wireless Sensor of High-voltage Electrical Equipment

DEFF Research Database (Denmark)

Xingkui, Mao; Qisheng, Huang; Yudi, Xiao

2016-01-01

On-line monitoring of high-voltage electrical equipment (HV-EE) aiming to detect faults effectively has become crucial to avoid serious accidents. Moreover, highly reliable power supplies are the key component for the wireless sensors equipped in such on-line monitoring systems. Therefore......, in this paper, the wireless power supply via coupled magnetic resonance (MR-WPS) is proposed for powering the wireless sensor and the associated wireless sensor solution is also proposed. The key specifications of the MR-WPS working in switchgear cabinet with a harsh operation environment are analyzed...... power is able to be delivered to the wireless sensor through the designed MR-WPS, and therefore the theoretical analysis and design is verified....

Structural processing for wireless communications

CERN Document Server

Lu, Jianhua; Ge, Ning

2015-01-01

This brief presents an alternative viewpoint on processing technology for wireless communications based on recent research advances. As a lever in emerging processing technology, the structure perspective addresses the complexity and uncertainty issues found in current wireless applications. Likewise, this brief aims at providing a new prospective to the development of communication technology and information science, while stimulating new theories and technologies for wireless systems with ever-increasing complexity. Readers of this brief may range from graduate students to researchers in related fields.

Matching theory for wireless networks

CERN Document Server

Han, Zhu; Saad, Walid

2017-01-01

This book provides the fundamental knowledge of the classical matching theory problems. It builds up the bridge between the matching theory and the 5G wireless communication resource allocation problems. The potentials and challenges of implementing the semi-distributive matching theory framework into the wireless resource allocations are analyzed both theoretically and through implementation examples. Academics, researchers, engineers, and so on, who are interested in efficient distributive wireless resource allocation solutions, will find this book to be an exceptional resource. .

7 CFR 1737.80 - Description of characteristics letter.

Science.gov (United States)

2010-01-01

... the amount of the proposed loan, its purposes, rate of interest, loan security requirements, and other... SERVICE, DEPARTMENT OF AGRICULTURE PRE-LOAN POLICIES AND PROCEDURES COMMON TO INSURED AND GUARANTEED TELECOMMUNICATIONS LOANS Characteristics Letter § 1737.80 Description of characteristics letter. (a) After all of the...

Wireless sensor networks in chemical industry

International Nuclear Information System (INIS)

Minhas, A.A.; Jawad, S.

2010-01-01

Recent advances in wireless technology are a clear indication of the commercial promise of wireless networks. Industrial wireless sensing has now become more economical, efficient and secure as compared to traditional wired sensing. Wireless Sensor Networks (WSN) are successfully being used for process monitoring and control of many industrial plants. This paper explores how Chemical Industry in particular can benefit from the application of WSN technology. Various examples of successful implementation are cited. In order to address the industrial requirements, we propose a low power and low cost solution for process monitoring by implementing WSN. (author)

Warming Up to Wireless

Science.gov (United States)

Milner, Jacob

2005-01-01

In districts big and small across the U.S., students, teachers, and administrators alike have come to appreciate the benefits of wireless technology. Because the technology delivers Internet signals on airborne radio frequencies, wireless networking allows users of all portable devices to move freely on a school's campus and stay connected to the…

A Remote WIRELESS Facility

Directory of Open Access Journals (Sweden)

Kees Uiterwijk

2007-10-01

Full Text Available Continuing need for available distance learning facilities has led to the development of a remote lab facility focusing on wireless technology. In the field of engineering there is a student need of gaining experience in set-up, monitoring and maintenance of 802.11A/B/G based wireless LAN environments.

Advanced Signal Processing for Wireless Multimedia Communications

Directory of Open Access Journals (Sweden)

Xiaodong Wang

2000-01-01

Full Text Available There is at present a worldwide effort to develop next-generation wireless communication systems. It is envisioned that many of the future wireless systems will incorporate considerable signal-processing intelligence in order to provide advanced services such as multimedia transmission. In general, wireless channels can be very hostile media through which to communicate, due to substantial physical impediments, primarily radio-frequency interference and time-arying nature of the channel. The need of providing universal wireless access at high data-rate (which is the aim of many merging wireless applications presents a major technical challenge, and meeting this challenge necessitates the development of advanced signal processing techniques for multiple-access communications in non-stationary interference-rich environments. In this paper, we present some key advanced signal processing methodologies that have been developed in recent years for interference suppression in wireless networks. We will focus primarily on the problem of jointly suppressing multiple-access interference (MAI and intersymbol interference (ISI, which are the limiting sources of interference for the high data-rate wireless systems being proposed for many emerging application areas, such as wireless multimedia. We first present a signal subspace approach to blind joint suppression of MAI and ISI. We then discuss a powerful iterative technique for joint interference suppression and decoding, so-called Turbo multiuser detection, that is especially useful for wireless multimedia packet communications. We also discuss space-time processing methods that employ multiple antennas for interference rejection and signal enhancement. Finally, we touch briefly on the problems of suppressing narrowband interference and impulsive ambient noise, two other sources of radio-frequency interference present in wireless multimedia networks.

Wireless Damage Location Sensing System

Science.gov (United States)

Woodard, Stanley E. (Inventor); Taylor, Bryant Douglas (Inventor)

2012-01-01

A wireless damage location sensing system uses a geometric-patterned wireless sensor that resonates in the presence of a time-varying magnetic field to generate a harmonic response that will experience a change when the sensor experiences a change in its geometric pattern. The sensing system also includes a magnetic field response recorder for wirelessly transmitting the time-varying magnetic field and for wirelessly detecting the harmonic response. The sensing system compares the actual harmonic response to a plurality of predetermined harmonic responses. Each predetermined harmonic response is associated with a severing of the sensor at a corresponding known location thereof so that a match between the actual harmonic response and one of the predetermined harmonic responses defines the known location of the severing that is associated therewith.

Pseudo-Synesthesia through Reading Books with Colored Letters

Science.gov (United States)

Colizoli, Olympia; Murre, Jaap M. J.; Rouw, Romke

2012-01-01

Background Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter ‘a’ always appears as light blue). In this study, we examine whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color. Methodology/Principal Findings Non-synesthetes were given specially prepared colored books to read. A modified Stroop task was administered before and after reading. A perceptual crowding task was administered after reading. Reading one book (>49,000 words) was sufficient to induce effects regarded as behavioral markers for synesthesia. The results of the Stroop tasks indicate that it is possible to learn letter-color associations through reading in color (F(1, 14) = 5.85, p = .030). Furthermore, Stroop effects correlated with subjective reports about experiencing letters in color (r(13) = 0.51, p = .05). The frequency of viewing letters is related to the level of association as seen by the difference in the Stroop effect size between upper- and lower-case letters (t(14) = 2.79, p = .014) and in a subgroup of participants whose Stroop effects increased as they continued to read in color. Readers did not show significant performance advantages on the crowding task compared to controls. Acknowledging the many differences between trainees and synesthetes, results suggest that it may be possible to acquire a subset of synesthetic behavioral traits in adulthood through training. Conclusion/Significance To our knowledge, this is the first evidence of acquiring letter-color associations through reading in color. Reading in color appears to be a promising avenue in which we may explore the differences and similarities between synesthetes and non-synesthetes. Additionally, reading in color is a plausible method for a long-term ‘synesthetic’ training program. PMID

30 CFR 1.3 - Use of letters and acronym MSHA.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Use of letters and acronym MSHA. 1.3 Section 1.3 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OFFICIAL EMBLEM AND...; ESTABLISHMENT AND USE OF OFFICIAL EMBLEM § 1.3 Use of letters and acronym MSHA. The letters and acronym MSHA may...

Wireless Network Penetration Testing and Security Auditing

Directory of Open Access Journals (Sweden)

Wang Shao-Long

2016-01-01

Full Text Available IEEE802.11 wireless wireless networks have security issues that are vulnerable to a variety of attacks. Due to using radio to transport data, attackers can bypass firewalls, sniff sensitive information, intercept packets and send malicious packets. Security auditing and penetration testing is expected to ensure wireless networks security. The contributions of this work are analyzed the vulnerability and types of attacks pertaining to IEEE 802.11 WLAN, performed well known attacks in a laboratory environment to conduct penetration tests to confirm whether our wireless network is hackable or not. WAIDPS is configured as auditing tool to view wireless attacks, such as WEP/WPA/WPA2 cracking, rouge access points, denial of service attack. WAIDPS is designed to detect wireless intrusion with additional features. Penetration testing and auditing will mitigate the risk and threatening to protect WALN.

Anonymous letters? DNA and fingerprints technologies combined to solve a case.

Science.gov (United States)

Barbaro, A; Cormaci, P; Teatino, A; La Marca, A; Barbaro, A

2004-12-02

Two brothers, living in two different cities, received two different anonymous letters. We performed latent prints development and DNA research on the letters and also on a glass used by a cousin suspected to be the letters' sender.

Attacks on IEEE 802.11 wireless networks

Directory of Open Access Journals (Sweden)

Dejan Milan Tepšić

2013-06-01

Full Text Available Security of wireless computer networks was initially secured with the WEP security protocol, which relies on the RC4 encryption algorithm and the CRC algorithm to check the integrity. The basic problems of the WEP are a short initialization vector, unsafe data integrity checking, using a common key, the lack of mechanisms for management and exchange of keys, the lack of protection from the endless insertion of the same package into the network, the lack of authentication of access points and the like. The consequences of these failures are easy attacks against the WEP network, namely their complete insecurity. Therefore, the work began on the IEEE 802.11i protocol, which should radically improve the security of wireless networks. Since the development of a protocol lasted, the WPA standard was released to offset the security gap caused by the WEP. The WPA also relies on RC4 and CRC algorithms, but brings temporary keys and the MIC algorithm for data integrity. The 802.1X authentication was introduced and common keys are no longer needed, since it is possible to use an authentication server. The length of the initialization vector was increased and the vector is obtained based on the packet serial number, in order to prevent the insertion of the same packet into the network. The weakness of the WPA security mechanism is the use of a common key. WPA2 (802.11i later appeared. Unlike the WPA mechanism that worked on old devices with the replacement of software, WPA2 requires new network devices that can perform AES encryption. AES replaces the RC4 algorithm and delivers much greater security. Data integrity is protected by encryption. Despite progress, there are still weaknesses in wireless networks. Attacks for denial of service are possible as well as spoofing package headers attacks. For now, it is not advisable to use wireless networks in environments where unreliability and unavailability are not tolerated. Introduction In the entire history of

Letters of Marcus Antonius Kappus from colonial America IV

Directory of Open Access Journals (Sweden)

Janez Stanonik

1989-12-01

Full Text Available The letter of Marcus Antonius Kappus which we publish in our present the fourth - continuation of his letters from Colonial America, is not preserved - as the first three letters are - in a manuscript. Instead we find it published in the famous contemporary collection of Jesuitic letters which appeared from 1728 till 1758 under the editorship of Joseph Stöcklein and his successors in Augsburg and Graz under the title Der neue Welt-Bott mit Allerhand Nachrichten derer Missionariorum Soc. Jesu. Kappus' letter can be found in vol. I, part II, p. 86-88 under the number 56. It has never since 1728 been reprinted in German, neither has it ever been published in an English translation. Our reprint of the German text is justified because Stöcklein's collection is generally not available even in the largest libraries, especially in America. An English translation can be useful because of the difficulties the old form of its German with its localisms can cause to its readers.

802.11 Wireless Networks The Definitive Guide

CERN Document Server

Gast, Matthew S

2005-01-01

As we all know by now, wireless networks offer many advantages over fixed (or wired) networks. Foremost on that list is mobility, since going wireless frees you from the tether of an Ethernet cable at a desk. But that's just the tip of the cable-free iceberg. Wireless networks are also more flexible, faster and easier for you to use, and more affordable to deploy and maintain. The de facto standard for wireless networking is the 802.11 protocol, which includes Wi-Fi (the wireless standard known as 802.11b) and its faster cousin, 802.11g. With easy-to-install 802.11 network hardware avail

Name-letter branding under scrutiny: real products, new algorithms, and the probability of buying.

Science.gov (United States)

Stieger, Stefan

2010-06-01

People like letters matching their own first and last name initials more than nonname letters. This name-letter effect has also been found for brands, i.e., people like brands resembling their own name letters (initial or first three). This has been termed name-letter branding effect. In the present study of 199 participants, ages 12 to 79 years, this name-letter branding effect was found for a modified design (1) using real products, (2) concentrating on product names rather than brand names, (3) using five different products for each letter of the Roman alphabet, (4) asking for the buying probability, and (5) using recently introduced algorithms, controlling for individual response tendencies (i.e., liking all letters more or less) and general normative popularity of particular letters (i.e., some letters are generally preferred more than other letters).

Energy-Efficient Broadcasting Scheme for Smart Industrial Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Zhuangbin Chen

2017-01-01

Full Text Available In smart Industrial Wireless Sensor Networks (IWSNs, sensor nodes usually adopt a programmable technology. These smart devices can obtain new or special functions by reprogramming: they upgrade their soft systems through receiving new version of program codes. If sensor nodes need to be upgraded, the sink node will propagate program code packets to them through “one-to-many” broadcasting, and therefore new capabilities can be obtained, forming the so-called Software Defined Network (SDN. However, due to the high volume of code packet, the constraint energy of sensor node, and the unreliable link quality of wireless network, rapidly broadcasting the code packets to all nodes in network can be a challenge issue. In this paper, a novel Energy-efficient Broadcast scheme with adjustable broadcasting radius is proposed aiming to improve the performance of network upgrade. In our scheme, the nonhotspots sensor nodes take full advantage of their residual energy caused in data collection period to improve the packet reception probability and reduce the broadcasting delay of code packet transmission by enlarging the broadcasting radius, that is, the transmitting power. The theoretical analyses and experimental results show that, compared with previous work, our approach can averagely reduce the Network Upgrade Delay (NUD by 14.8%–45.2% and simultaneously increase the reliability without harming the lifetime of network.

Implementation Issues of Adaptive Energy Detection in Heterogeneous Wireless Networks

Science.gov (United States)

Sobron, Iker; Eizmendi, Iñaki; Martins, Wallace A.; Diniz, Paulo S. R.; Ordiales, Juan Luis; Velez, Manuel

2017-01-01

Spectrum sensing (SS) enables the coexistence of non-coordinated heterogeneous wireless systems operating in the same band. Due to its computational simplicity, energy detection (ED) technique has been widespread employed in SS applications; nonetheless, the conventional ED may be unreliable under environmental impairments, justifying the use of ED-based variants. Assessing ED algorithms from theoretical and simulation viewpoints relies on several assumptions and simplifications which, eventually, lead to conclusions that do not necessarily meet the requirements imposed by real propagation environments. This work addresses those problems by dealing with practical implementation issues of adaptive least mean square (LMS)-based ED algorithms. The paper proposes a new adaptive ED algorithm that uses a variable step-size guaranteeing the LMS convergence in time-varying environments. Several implementation guidelines are provided and, additionally, an empirical assessment and validation with a software defined radio-based hardware is carried out. Experimental results show good performance in terms of probabilities of detection (Pd>0.9) and false alarm (Pf∼0.05) in a range of low signal-to-noise ratios around [-4,1] dB, in both single-node and cooperative modes. The proposed sensing methodology enables a seamless monitoring of the radio electromagnetic spectrum in order to provide band occupancy information for an efficient usage among several wireless communications systems. PMID:28441751

Optimization of Planar Monopole Wideband Antenna for Wireless Communication System.

Science.gov (United States)

Shakib, Mohammed Nazmus; Moghavvemi, Mahmoud; Mahadi, Wan Nor Liza

2016-01-01

In this paper, a new compact wideband monopole antenna is presented for wireless communication applications. This antenna comprises of a new radiating patch, a new arc-shaped strip, microstrip feed line, and a notched ground plane. The proposed radiating patch is combined with a rectangular and semi-circular patch and is integrated with a partial ground plane to provide a wide impedance bandwidth. The new arc-shaped strip between the radiating patch and microstrip feed line creates an extra surface on the patch, which helps further widen the bandwidth. Inserting one step notch on the ground plane further enhances the bandwidth. The antenna has a compact size of 16×20×1.6mm3. The measured result indicated that the antenna achieves a 127% bandwidth at VSWR≤2, ranging from 4.9GHz to 22.1GHz. Stable radiation patterns with acceptable gain are achieved. Also, a measured bandwidth of 107.7% at VSWR≤1.5 (5.1-17GHz) is obtained, which is suitable for UWB outdoor propagation. This antenna is compatible with a good number of wireless standards, including UWB band, Wimax 5.4 GHz band, MVDDS (12.2-12.7GHz), and close range radar and satellite communication in the X-band (8-12GHz), and Ku band (12-18GHz).

Wireless Communications Device Wakeup Method and System

NARCIS (Netherlands)

Drago, S.; Sebastiano, F.; Leenaerts, D.M.W.; Breems, L.J.

2008-01-01

Abstract of WO 2009044368 Disclosed are wakeable wireless communications devices, and methods for waking wireless communications devices, for use in a wireless network of such devices. The devices communicate during respectively-designated timeslots according to a communications protocol. The

Sinkhole Avoidance Routing in Wireless Sensor Networks

Science.gov (United States)

2011-05-09

COVERED (From- To) 09-05-2011 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Sinkhole Avoidance Routing in Wireless Sensor Networks 5b . GRANT NUMBER . 5c...reliability of wireless sensor networks. 15. SUBJECT TERMS wireless sensor networks, sinkhole attack, routing protocol 16. SECURITY CLASSIFICATION...Include area code) Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std . Z39.18 1 Sinkhole Avoidance Routing in Wireless Sensor Networks MIDN 1/C

Open Letter to Religious Leaders about Sex Education

Science.gov (United States)

American Journal of Sexuality Education, 2011

2011-01-01

The "Open Letter to Religious Leaders about Sex Education" reinforces scriptural and theological commitments to truth-telling in calling for "full and honest education about sexual and reproductive health." This "Open Letter" was published in 2002, at about the midpoint of a decade-long federal government commitment to…

Wireless Remote Control System

Directory of Open Access Journals (Sweden)

Adrian Tigauan

2012-06-01

Full Text Available This paper presents the design of a wireless remote control system based on the ZigBee communication protocol. Gathering data from sensors or performing control tasks through wireless communication is advantageous in situations in which the use of cables is impractical. An Atmega328 microcontroller (from slave device is used for gathering data from the sensors and transmitting it to a coordinator device with the help of the XBee modules. The ZigBee standard is suitable for low-cost, low-data-rate and low-power wireless networks implementations. The XBee-PRO module, designed to meet ZigBee standards, requires minimal power for reliable data exchange between devices over a distance of up to 1600m outdoors. A key component of the ZigBee protocol is the ability to support networking and this can be used in a wireless remote control system. This system may be employed e.g. to control temperature and humidity (SHT11 sensor and light intensity (TSL230 sensor levels inside a commercial greenhouse.

Wireless distributed functional electrical stimulation system

Directory of Open Access Journals (Sweden)

Jovičić Nenad S

2012-08-01

Full Text Available Abstract Background The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. Methods The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype’s software. Results The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers. One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. Conclusions The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.

Wireless distributed functional electrical stimulation system.

Science.gov (United States)

Jovičić, Nenad S; Saranovac, Lazar V; Popović, Dejan B

2012-08-09

The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement. The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype's software. The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers). One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms. The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.

Wireless communications resource management

CERN Document Server

Lee, B; Seo, H

2009-01-01

Wireless technologies continue to evolve to address the insatiable demand for faster response times, larger bandwidth, and reliable transmission. Yet as the industry moves toward the development of post 3G systems, engineers have consumed all the affordable physical layer technologies discovered to date. This has necessitated more intelligent and optimized utilization of available wireless resources. Wireless Communications Resource Managem ent, Lee, Park, and Seo cover all aspects of this critical topic, from the preliminary concepts and mathematical tools to detailed descriptions of all the resource management techniques. Readers will be able to more effectively leverage limited spectrum and maximize device battery power, as well as address channel loss, shadowing, and multipath fading phenomena.

Development and Application of Wireless Power Transmission Systems for Wireless ECG Sensors

Directory of Open Access Journals (Sweden)

Jin-Chul Heo

2018-01-01

Full Text Available We investigated the variations in the magnetic field distribution and power transmission efficiency, resulting from changes in the relative positions of the transmitting and receiving coils, for electromagnetic induction-type wireless power transmission using an elliptical receive coil. Results of simulations using a high-frequency structure simulator were compared to actual measurement results. The simulations showed that the transmission efficiency could be maintained relatively stable even if the alignment between the transmitting and receiving coils was changed to some extent. When the centre of the receiving coil was perfectly aligned with the centre of the transmitting coil, the transmission efficiency was in the maximum; however, the degree of decrease in the transmission efficiency was small even if the centre of the receiving coil moved by ±10 mm from the centre of the transmitting coil. Therefore, it is expected that the performance of the wireless power transmission system will not be degraded significantly even if perfect alignment is not maintained. Animal experiments confirmed good ECG signals for the simulation conditions. The results suggested a standardized application method of wireless transmission in the utilization of wireless power for implantable sensors.

Towards Controlling Latency in Wireless Networks

KAUST Repository

Bouacida, Nader

2017-04-24

Wireless networks are undergoing an unprecedented revolution in the last decade. With the explosion of delay-sensitive applications in the Internet (i.e., online gaming and VoIP), latency becomes a major issue for the development of wireless technology. Taking advantage of the significant decline in memory prices, industrialists equip the network devices with larger buffering capacities to improve the network throughput by limiting packets drops. Over-buffering results in increasing the time that packets spend in the queues and, thus, introducing more latency in networks. This phenomenon is known as “bufferbloat”. While throughput is the dominant performance metric, latency also has a huge impact on user experience not only for real-time applications but also for common applications like web browsing, which is sensitive to latencies in order of hundreds of milliseconds. Concerns have arisen about designing sophisticated queue management schemes to mitigate the effects of such phenomenon. My thesis research aims to solve bufferbloat problem in both traditional half-duplex and cutting-edge full-duplex wireless systems by reducing delay while maximizing wireless links utilization and fairness. Our work shed lights on buffer management algorithms behavior in wireless networks and their ability to reduce latency resulting from excessive queuing delays inside oversized static network buffers without a significant loss in other network metrics. First of all, we address the problem of buffer management in wireless full-duplex networks by using Wireless Queue Management (WQM), which is an active queue management technique for wireless networks. Our solution is based on Relay Full-Duplex MAC (RFD-MAC), an asynchronous media access control protocol designed for relay full-duplexing. Compared to the default case, our solution reduces the end-to-end delay by two orders of magnitude while achieving similar throughput in most of the cases. In the second part of this thesis

A Power Balance Aware Wireless Charger Deployment Method for Complete Coverage in Wireless Rechargeable Sensor Networks

Directory of Open Access Journals (Sweden)

Tu-Liang Lin

2016-08-01

Full Text Available Traditional sensor nodes are usually battery powered, and the limited battery power constrains the overall lifespan of the sensors. Recently, wireless power transmission technology has been applied in wireless sensor networks (WSNs to transmit wireless power from the chargers to the sensor nodes and solve the limited battery power problem. The combination of wireless sensors and wireless chargers forms a new type of network called wireless rechargeable sensor networks (WRSNs. In this research, we focus on how to effectively deploy chargers to maximize the lifespan of a network. In WSNs, the sensor nodes near the sink consume more power than nodes far away from the sink because of frequent data forwarding. This important power unbalanced factor has not been considered, however, in previous charger deployment research. In this research, a power balance aware deployment (PBAD method is proposed to address the power unbalance in WRSNs and to design the charger deployment with maximum charging efficiency. The proposed deployment method is effectively aware of the existence of the sink node that would cause unbalanced power consumption in WRSNs. The simulation results show that the proposed PBAD algorithm performs better than other deployment methods, and fewer chargers are deployed as a result.

Analyzing International Letters in a Business Communication Class.

Science.gov (United States)

Devet, Bonnie

1998-01-01

Shows how students can use persuasive principles of communication (format and writer's purpose) and of classical rhetoric (organization, ethos, pathos, logos, and style) to improve their ability to analyze business letters. Shows how applying these principles to the analysis of business letters from other countries helps students write better and…

Security for 5G Mobile Wireless Networks

OpenAIRE

Fang, Dongfeng; Qian, Yi; Qingyang Hu, Rose

2017-01-01

The advanced features of 5G mobile wireless network systems yield new security requirements and challenges. This paper presents a comprehensive survey on security of 5G wireless network systems compared to the traditional cellular networks. The paper starts with a review on 5G wireless networks particularities as well as on the new requirements and motivations of 5G wireless security. The potential attacks and security services with the consideration of new service requirements and new use ca...

The “Wireless Sensor Networks for City-Wide Ambient Intelligence (WISE-WAI” Project

Directory of Open Access Journals (Sweden)

Michele Zorzi

2009-05-01

Full Text Available This paper gives a detailed technical overview of some of the activities carried out in the context of the “Wireless Sensor networks for city-Wide Ambient Intelligence (WISEWAI” project, funded by the Cassa di Risparmio di Padova e Rovigo Foundation, Italy. The main aim of the project is to demonstrate the feasibility of large-scale wireless sensor network deployments, whereby tiny objects integrating one or more environmental sensors (humidity, temperature, light intensity, a microcontroller and a wireless transceiver are deployed over a large area, which in this case involves the buildings of the Department of Information Engineering at the University of Padova. We will describe how the network is organized to provide full-scale automated functions, and which services and applications it is configured to provide. These applications include long-term environmental monitoring, alarm event detection and propagation, single-sensor interrogation, localization and tracking of objects, assisted navigation, as well as fast data dissemination services to be used, e.g., to rapidly re-program all sensors over-the-air. The organization of such a large testbed requires notable efforts in terms of communication protocols and strategies, whose design must pursue scalability, energy efficiency (while sensors are connected through USB cables for logging and debugging purposes, most of them will be battery-operated, as well as the capability to support applications with diverse requirements. These efforts, the description of a subset of the results obtained so far, and of the final objectives to be met are the scope of the present paper.

Wireless mobile Internet security

CERN Document Server

Rhee, Man Young

2013-01-01

  The mobile industry for wireless cellular services has grown at a rapid pace over the past decade. Similarly, Internet service technology has also made dramatic growth through the World Wide Web with a wire line infrastructure. Realization for complete wired/wireless mobile Internet technologies will become the future objectives for convergence of these technologies thr

An Optimal Electric Dipole Antenna Model and Its Field Propagation

Directory of Open Access Journals (Sweden)

Yidong Xu

2016-01-01

Full Text Available An optimal electric dipole antennas model is presented and analyzed, based on the hemispherical grounding equivalent model and the superposition principle. The paper also presents a full-wave electromagnetic simulation for the electromagnetic field propagation in layered conducting medium, which is excited by the horizontal electric dipole antennas. Optimum frequency for field transmission in different depth is carried out and verified by the experimental results in comparison with previously reported simulation over a digital wireless Through-The-Earth communication system. The experimental results demonstrate that the dipole antenna grounding impedance and the output power can be efficiently reduced by using the optimal electric dipole antenna model and operating at the optimum frequency in a vertical transmission depth up to 300 m beneath the surface of the earth.

Green Wireless Power Transfer Networks

NARCIS (Netherlands)

Liu, Q.; Golinnski, M.; Pawelczak, P.; Warnier, M.

2016-01-01

wireless power transfer network (WPTN) aims to support devices with cable-less energy on-demand. Unfortunately, wireless power transfer itself-especially through radio frequency radiation rectification-is fairly inefficient due to decaying power with distance, antenna polarization, etc.

An 802.11 n wireless local area network transmission scheme for wireless telemedicine applications.

Science.gov (United States)

Lin, C F; Hung, S I; Chiang, I H

2010-10-01

In this paper, an 802.11 n transmission scheme is proposed for wireless telemedicine applications. IEEE 802.11n standards, a power assignment strategy, space-time block coding (STBC), and an object composition Petri net (OCPN) model are adopted. With the proposed wireless system, G.729 audio bit streams, Joint Photographic Experts Group 2000 (JPEG 2000) clinical images, and Moving Picture Experts Group 4 (MPEG-4) video bit streams achieve a transmission bit error rate (BER) of 10-7, 10-4, and 103 simultaneously. The proposed system meets the requirements prescribed for wireless telemedicine applications. An essential feature of this proposed transmission scheme is that clinical information that requires a high quality of service (QoS) is transmitted at a high power transmission rate with significant error protection. For maximizing resource utilization and minimizing the total transmission power, STBC and adaptive modulation techniques are used in the proposed 802.11 n wireless telemedicine system. Further, low power, direct mapping (DM), low-error protection scheme, and high-level modulation are adopted for messages that can tolerate a high BER. With the proposed transmission scheme, the required reliability of communication can be achieved. Our simulation results have shown that the proposed 802.11 n transmission scheme can be used for developing effective wireless telemedicine systems.

The distributed neural system for top-down letter processing: an fMRI study

Science.gov (United States)

Liu, Jiangang; Feng, Lu; Li, Ling; Tian, Jie

2011-03-01

This fMRI study used Psychophysiological interaction (PPI) to investigate top-down letter processing with an illusory letter detection task. After an initial training that became increasingly difficult, participant was instructed to detect a letter from pure noise images where there was actually no letter. Such experimental paradigm allowed for isolating top-down components of letter processing and minimizing the influence of bottom-up perceptual input. A distributed cortical network of top-down letter processing was identified by analyzing the functional connectivity patterns of letter-preferential area (LA) within the left fusiform gyrus. Such network extends from the visual cortex to high level cognitive cortexes, including the left middle frontal gyrus, left medial frontal gyrus, left superior parietal gyrus, bilateral precuneus, and left inferior occipital gyrus. These findings suggest that top-down letter processing contains not only regions for processing of letter phonology and appearance, but also those involved in internal information generation and maintenance, and attention and memory processing.

Anisotropic metamaterial for efficiency enhancement of mid-range wireless power transfer under coil misalignment

International Nuclear Information System (INIS)

Ranaweera, A L A K; Moscoso, Carlos Arriola; Lee, Jong-Wook

2015-01-01

In a wireless power transfer (WPT) system, misalignment between transmitter and receiver coils is one of the key factors affecting efficiency. Recently, metamaterials have shown great potential to enhance electromagnetic propagation in various environments. In this work, we apply a metamaterial to enhance the WPT in a more general environment where misalignment is considered. Using an anisotropic metamaterial, we obtain a significant efficiency enhancement. Therefore, we propose that the metamaterial is an effective means to mitigate the decreased efficiency caused by misalignment. In addition, we investigate the effect of coil misalignment on the threshold distance beyond which the metamaterial enhances the performance of WPT. (paper)

Microwave materials for wireless applications

CERN Document Server

Cruickshank, David B

2011-01-01

This practical resource offers you an in-depth, up-to-date understanding of the use of microwave magnetic materials for cutting-edge wireless applications. The book discusses device applications used in wireless infrastructure base stations, point-to-point radio links, and a range of more specialized microwave systems. You find detailed discussions on the attributes of each family of magnetic materials with respect to specific wireless applications. Moreover, the book addresses two of the hottest topics in the field today - insertion loss and intermodulation. This comprehensive reference also

Performance Evaluation of AODV, DSR, DYMO & ZRP in Cost 231 Walfisch-Ikegami Path Loss Propagation Model

Directory of Open Access Journals (Sweden)

Rachit JAIN

2011-07-01

Full Text Available A Mobile Ad hoc NETwork is a kind of wireless ad-hoc network, and is a self configuring network of mobile routers connected by wireless links. Mobile Ad-Hoc Network (MANET is a wireless network without infrastructure. Self configurability and easy deployment feature of the MANET resulted in numerous applications in this modern era. Efficient routing protocols will make MANETs reliable. Various research communities are working in field of MANET and trying to adopt the protocols and technology in other applications as well. In this work, we present investigations on the behavior of various routing protocol of MANET with a Cost 231 Walfisch-Ikegami Propagation Model. We evaluate the performance of four different ad-hoc routing protocols on four performance metrics such as Average Jitter, Average End-to-End Delay, Throughput, and Packet Delivery Fraction with varying Pause Time. From the simulation results it is concluded that DSR is better in transmission of packets per unit time and maximum number of packets reached their destination successfully with some delays, i.e. PDF & Throughput is more and Average jitter & end-to-end delay is less. Whereas AODV & ZRP having almost same values in all of the performance metrics, they transmit packets with very less delay but transmits less packets to their destination as compare to DSR

Professional Citation Practices in Child Maltreatment Forensic Letters

Science.gov (United States)

Schryer, Catherine F.; Bell, Stephanie; Mian, Marcellina; Spafford, Marlee M.; Lingard, Lorelei

2011-01-01

Using rhetorical genre theory and research on reported speech, this study investigates the citation practices in 81 forensic letters written by paediatricians and nurse practitioners that provide their opinion for the courts as to whether a child has experienced maltreatment. These letters exist in a complex social situation where a lack of…

Review: Security in Wireless Technologies in Business

Science.gov (United States)

Sattarova, F. Y.; Kim, Tai-Hoon

Wireless technology seems to be everywhere now - but it is still relatively in its infancy. New standards and protocols continue to emerge and problems and bugs are discovered. Nevertheless, wireless networks make many things much more convenient and it appears that wireless networks are here to stay. The differences and similarities of wireless and wired security, the new threats brought by mobility, the security of networks and devices and effects of security, or lack of it are shortly discussed in this review paper.

Readability of "Dear Patient" device advisory notification letters created by a device manufacturer.

Science.gov (United States)

Mueller, Luke A; Sharma, Arjun; Ottenberg, Abigale L; Mueller, Paul S

2013-04-01

In 2006, the Heart Rhythm Society (HRS) recommended that cardiovascular implantable electronic device (CIED) manufacturers use advisory notification letters to communicate with affected patients. To evaluate the readability of the HRS sample "patient device advisory notification" letter and those created by 1 CIED manufacturer. The HRS sample letter and 25 Boston Scientific Corporation letters dated from 2005 through 2011 were evaluated by using 6 readability tests. Readability (Flesch-Kincaid score) of the HRS sample letter was grade level 12.5, and median readability of the device manufacturer letters was grade level 12.8 (range 10.8-18.9). Similar results were obtained by using other readability scales. No letters had readability scores at the National Work Group on Literacy and Health's recommended reading level-fifth grade; the letters' readability exceeded this recommended level by an average of 7.7 grades (95% confidence interval 6.9-8.5; Preadability scores at the average reading level of US adults-eighth grade; the letters' readability exceeded this level by an average of 4.7 grades (95% confidence interval 3.9-5.5; Preadability of the HRS sample letter and those created by a CIED manufacturer significantly exceeded the recommended and average US adults' reading skill levels. Such letters are unlikely to be informative to many patients. CIED manufacturers should ensure that advisory letters are comprehensible to most affected patients. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Visual and Artistic Functions of Letters Khaghani’s Poetry

Directory of Open Access Journals (Sweden)

Dr. M. Zolfaghari

Full Text Available The intensity of emotion and vibration of meaning in the poet's mind causes him to go beyond the ordinary language and through metaphors, similes and linguistic preparation he conveys intellectual and emotional meanings. He has a sharp eye and a sensitive spirit and creative temprement and by inventing new images shows the creativity and imagination in various arenas and attempts in the way of literary strength and creating personal style and this point more than anything else must be done by presenting images and newness. Perhaps in the sixth century, and especially in Azerbaijani school, more than other periods, poets have been looking for creating innovative style in eloquence. Their major attempts were mainly in imaging, it was a wide field that they have competed and it is natural that in this illustration the alphabet letters would be very helpful. Khaghani poetry as one of the greatest poets of this school has the perfect poetrical book of painting and meaning, and delicated pattern in new and different scientific, cultural and religious paintings and letters are a broad range of elements that put a new field in front of the poet and he is aware of the potential features of the letters and also the new images and the artistic creativity.This paper shows descriptive - analytical study of various aspects of Khaghani’s poetry and frequency of letters in the alphabet, authentic images based on alphabet, taken at different pseudo relevance of poetry in the context of multiple semantic and literal characters, making figures of speech based on literary characters, images and characters and the sense of connection . . . which has been shown in his poetry.Letter has double and even multiple uses in Khaghani poetic works (divan and more than the construction of words which is the real and common sense that is used as an artistic. There is a world in the heart of every letter, word and morpheme lies in the poet's point of view is the last and

Letter Frequency Analysis of Lithuanian and Other Languages Using the Latin Alphabet

Directory of Open Access Journals (Sweden)

Gintautas Grigas

2015-12-01

Full Text Available It is important to evaluate specificities of alphabets, particularly the letter frequencies while designing keyboards, analyzing texts, designing games based on alphabets, and doing some text mining. In order to adequately compare lettter frequences of Lithuanian language to other languages in the Internet space, Wikipedia source was selected which content is common to different languages. The method of letter frequency jumps is used. The main attention is paid to the analysis of letter frequencies at the boundary between native letters and foreign letters used in Lithuanian and other languages.

Wireless Technology Application to Nuclear Power Plants

International Nuclear Information System (INIS)

Lee, Jeong Kweon; Jeong, See Chae; Jeong, Ki Hoon; Oh, Do Young; Kim, Jae Hack

2009-01-01

Wireless technologies are getting widely used in various industrial processes for equipment condition monitoring, process measurement and other applications. In case of Nuclear Power Plant (NPP), it is required to review applicability of the wireless technologies for maintaining plant reliability, preventing equipment failure, and reducing operation and maintenance costs. Remote sensors, mobile technology and two-way radio communication may satisfy these needs. The application of the state of the art wireless technologies in NPPs has been restricted because of the vulnerability for the Electromagnetic Interference and Radio Frequency Interference (EMI/RFI) and cyber security. It is expected that the wireless technologies can be applied to the nuclear industry after resolving these issues which most of the developers and vendors are aware of. This paper presents an overview and information on general wireless deployment in nuclear facilities for future application. It also introduces typical wireless plant monitoring system application in the existing NPPs

Integrated Frequency Synthesis for Convergent Wireless Solutions

CERN Document Server

Atallah, Jad G

2012-01-01

This book describes the design and implementation of an electronic subsystem called the frequency synthesizer, which is a very important building block for any wireless transceiver. The discussion includes several new techniques for the design of such a subsystem which include the usage modes of the wireless device, including its support for several leading-edge wireless standards. This new perspective for designing such a demanding subsystem is based on the fact that optimizing the performance of a complete system is not always achieved by optimizing the performance of its building blocks separately.  This book provides “hands-on” examples of this sort of co-design of optimized subsystems, which can make the vision of an always-best-connected scenario a reality. Provides up-to-date design information regarding one of the most complex subsystems used in state-of-the-art wireless devices; Describes a wireless front-end solution designed to provide an always-best-connected solution, based on a wireless det...

Letter-By-Letter Reading: Natural Recovery and Response to Treatment

Directory of Open Access Journals (Sweden)

Pélagie M. Beeson

2005-01-01

Full Text Available The present investigation provides a longitudinal study of an individual (RB with acquired alexia following left posterior cerebral artery stroke. At initial testing, RB exhibited acquired alexia characterized by letter-by-letter (LBL reading, mild anomic aphasia, and acquired agraphia. Repeated measures of reading accuracy and rate were collected for single words and text over the course of one year, along with probes of naming and spelling abilities. Improvements associated with natural recovery (i.e., without treatment were documented up to the fourth month post onset, when text reading appeared to be relatively stable. Multiple oral reading (MOR treatment was initiated at 22 weeks post-stroke, and additional improvements in reading rate and accuracy for text were documented that were greater than those expected on the basis of spontaneous recovery alone. Over the course of one year, reading reaction times for single words improved, and the word-length effect that is the hallmark of LBL reading diminished. RB's response to treatment supports the therapeutic value of MOR treatment to in LBL readers. His residual impairment of reading and spelling one-year post stroke raised the question as to whether further progress was impeded by degraded orthographic knowledge.

Standardized Letter of Recommendation for Otolaryngology Residency Selection

Science.gov (United States)

Perkins, Jonathan N.; Liang, Conan; McFann, Kim; Abaza, Mona M.; Streubel, Sven-Olrik; Prager, Jeremy D.

2013-01-01

Objectives/Hypothesis Develop a standardized letter of recommendation (SLOR) for otolaryngology residency application that investigates the qualities desired in residents and letter writer’s experience. Compare this SLOR to narrative letters of recommendation (NLOR). Study Design Prospective SLOR/NLOR Comparison. Methods The SLOR was sent to a NLOR writer for each applicant. The applicant’s NLOR/SLOR pair was blinded and ranked in seven categories by three reviewers. Inter-rater reliability and NLOR/SLOR rankings were compared. Means of cumulative NLOR and SLOR scores were compared to our departmental rank list. Results Thirty-one SLORs (66%) were collected. The SLORs had higher inter-rater reliability for applicant’s qualifications for otolaryngology, global assessment, summary statement, and overall letter ranking. Writer’s background, comparison to contemporaries/predecessors, and letter review ease had higher inter-rater reliability on the NLORs. Mean SLOR rankings were higher for writer’s background (p=0.0007), comparison of applicant to contemporaries/predecessors (p=0.0031), and letter review ease (p<0.0001). Mean SLOR writing time was 4.17±2.18 minutes. Mean ranking time was significantly lower (p<0.0001) for the SLORs (39.24±23.45 seconds) compared to the NLORs (70.95±40.14 seconds). Means of cumulative SLOR scores correlated with our rank list (p=0.004), whereas means of cumulative NLOR scores did not (p=0.18). Means of cumulative NLOR and SLOR scores did not correlate (p=0.26). Conclusions SLORs require little writing time, save reviewing time, and are easier to review compared to NLORs. Our SLOR had higher inter-rater reliability in 4 of 7 categories and was correlated with our rank list. This tool conveys standardized information in an efficient manner. PMID:23172646

Should intellectual property be disseminated by "forwarding" rejected letters without permission?

Science.gov (United States)

Gupta, V K

1996-08-01

Substantive scientific letter writing is a cost-effective mode of complementing observational and experimental research. The value of such philosophically uncommitted and unsponsored well-balanced scientific activity has been relegated. Critical letter writing entails the abilities to: maintain rational scepticism; refuse to conform in order to explain data; persist in keeping common sense centre-stage; exercise logic to evaluate the biological significance of mathematical figures, including statistics, and the ability to sustain the will to share insights regarding disease mechanisms on an ostensibly lower research platform. During peer review, innovative letter writing may share the occasionally unfortunate fate of innovative research. Rejected scientific letters do not automatically lose copyright. Periodicals with high letter loads will see some valuable contributions wasted, but that is the price for maintaining autonomy in scientific publication. The scientific community is an integrated whole that must respect the rights of authors at all levels. Unauthorised forwarding of rejected letters sets the dangerous precedent of justifying unjust means.

Letters to a Young Baller: Exploring Epistolary Criticism

Science.gov (United States)

Chawansky, Megan

2010-01-01

This article explores the possibilities of epistolary criticism within the realm of sport studies and aspires to encourage scholars to consider the use of non-traditional sport memorabilia and source materials when telling emotive stories about sport and sport practices. The use of letters and the letter-writing format to tell a personal narrative…

Melanie Klein's letters addressed to Marcelle Spira (1955-1960).

Science.gov (United States)

Quinodoz, Jean-Michel

2009-12-01

Between 1955 and 1960, Melanie Klein wrote some 45 hitherto unpublished letters to Marcelle Spira, the Swiss psychoanalyst living at that time in Geneva. In 2006, after Spira's death, these letters were deposited with the Raymond de Saussure Psychoanalysis Centre in Geneva. They are the only known letters that Klein addressed to her psychoanalyst colleagues. Several topics are mentioned in them: (1) the meetings between the two women in Geneva and London; (2) Spira's contribution to Boulanger's translation into French of The Psychoanalysis of Children, which Klein herself carefully revised; (3) the papers that Klein was at that time working on, including Envy and Gratitude; (4) Spira's own work; (5) the difficulties that Spira, a Kleinian psychoanalyst who trained in Buenos Aires, was encountering in her attempt to be admitted to the Swiss Psychoanalytical Society; and (6) a few items of personal and family news. In addition to the invaluable historical information that these letters provide, they offer us a very moving epistolary self-portrait of Melanie Klein, enabling us to discover her personality in the final years of her life - she died in September 1960, just two months after writing her last letter to Spira.

[Representation of letter position in visual word recognition process].

Science.gov (United States)

Makioka, S

1994-08-01

Two experiments investigated the representation of letter position in visual word recognition process. In Experiment 1, subjects (12 undergraduates and graduates) were asked to detect a target word in a briefly-presented probe. Probes consisted of two kanji words. The latters which formed targets (critical letters) were always contained in probes. (e.g. target: [symbol: see text] probe: [symbol: see text]) High false alarm rate was observed when critical letters occupied the same within-word relative position (left or right within the word) in the probe words as in the target word. In Experiment 2 (subject were ten undergraduates and graduates), spaces adjacent to probe words were replaced by randomly chosen hiragana letters (e.g. [symbol: see text]), because spaces are not used to separate words in regular Japanese sentences. In addition to the effect of within-word relative position as in Experiment 1, the effect of between-word relative position (left or right across the probe words) was observed. These results suggest that information about within-word relative position of a letter is used in word recognition process. The effect of within-word relative position was explained by a connectionist model of word recognition.

[Patients' letters and pre-modern medical lay-culture].

Science.gov (United States)

Stolberg, Michael

2007-01-01

Consulting by letter was fairly common practice among the educated, upper classes of early modern Europe. Surviving letters of consultation written by patients, relatives or friends count among the most valuable source for the analysis of pre-modern experiences of disease and the body. This essay gives a brief overview of the various types of consultation letters and related documents which resulted from this practice before tracing the historical development of epistolary consultations from the late Middle Ages through the heyday medical correspondence in the 18th c. before its decline in the 19th c. It presents "experience", "self-fashioning" and "discourse" as three particularly fruitful levels of analysis on which patients' letters can be used within the wider framework of a cultural history of medicine. These three levels of analysis, or three distinct approaches, enable historians to access a greater awareness of the ways in which the experience of illness and the body is culturally framed with an analysis of the performative effects of patients' narratives and the influence of medical discourse among the wider society.

Topological Analysis of Wireless Networks (TAWN)

Science.gov (United States)

2016-05-31

19b. TELEPHONE NUMBER (Include area code) 31-05-2016 FINAL REPORT 12-02-2015 -- 31-05-2016 Topological Analysis of Wireless Networks (TAWN) Robinson...Release, Distribution Unlimited) N/A The goal of this project was to develop topological methods to detect and localize vulnerabilities of wireless... topology U U U UU 32 Michael Robinson 202-885-3681 Final Report: May 2016 Topological Analysis of Wireless Networks Principal Investigator: Prof. Michael

Wireless radio a history

CERN Document Server

Coe, Lewis

2006-01-01

""Informative...recommended""--Choice; ""interesting...a good read...well worth reading""--Contact Magazine. This history first looks at Marconi's wireless communications system and then explores its many applications, including marine radio, cellular telephones, police and military uses, television and radar. Radio collecting is also discussed, and brief biographies are provided for the major figures in the development and use of the wireless.

Smart Home Wireless Sensor Nodes

DEFF Research Database (Denmark)

Lynggaard, Per

. This paper introduces an approach that considerably lowers the wireless sensor node power consumption and the amount of transmitted sensor events. It uses smart objects that include artificial intelligence to efficiently process the sensor event on location and thereby saves the costly wireless...

Collected Letters of José Martí: a linguistic approach

Directory of Open Access Journals (Sweden)

Guerra, Ana Jústiz

2012-01-01

Full Text Available Any approach to José Marti’s literary production should consider the study of his collected letters, which are noticeable for its content and expressive devices. This article synthesizes the criteria of former researchers who have considered Marti’s collected letters as a privileged genre among the multiple and diverse cultivated by the Apostle (speeches, dramas, essays, journal article, short stories and literary criticism. The collected letters takes a large proportion of his prolific literary production and its expressive force has been widely recognized as a source of inspiration for other poets. His collection of letters is outstanding and lasting in time for its expressive magnificence, its depth of content and precise choice of words. Originally written for a definite addressee, the letters are currently read by new generations of readers, who rediscover a new message in each. Topic considered in this article is part of a wider range study which is been prepared as Ph. D. thesis.

The Complaint Letter and Response.

Science.gov (United States)

Shukla, P. K.

1998-01-01

Describes an assignment in which students write a letter of complaint, and discusses how this assignment aids students in seeing the importance of effective written communication to their daily lives. (SR)

Scientific Letter: Monosymptomatic Hypochondriacal Psychosis ...

African Journals Online (AJOL)

Scientific Letter: Monosymptomatic Hypochondriacal Psychosis (somatic delusional disorder): A report of two cases. ... African Journal of Psychiatry. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives.

Particles and nuclei, letters

International Nuclear Information System (INIS)

2004-01-01

The present collection of letters from JINR, Dubna, contains thirteen separate letters on start-to-end simulations of SASE FEL at the TESLA test facility, possible ways of improvement of the FEM oscillator with a Bragg resonator, the status and perspectives of the electron cooling method development, crystalline ion beams in storage rings, latest results of modeling of LHC beam injection, charge exchange injection in a synchrotron equipped with an electron cooling system, fringe and hysteresis effects in electron guns, nonstationary regimes of electron flow formation in secondary emission inverse coaxial diodes, a proposal of the experiment testing of the fine structure of the Vavilov-Cherenkov radiation, computer simulation of the electron beam dynamics at the accelerator structure and the injector of S-band linac with energies of 3 and 10 MeV, calculation of the electron beam dynamics of the accelerator LUE-200, the accelerator-accumulation facility ITEP-TWAC and accelerators-drivers of electronuclear facilities

Proxy SDN Controller for Wireless Networks

Directory of Open Access Journals (Sweden)

Won-Suk Kim

2016-01-01

Full Text Available Management of wireless networks as well as wired networks by using software-defined networking (SDN has been highlighted continually. However, control features of a wireless network differ from those of a wired network in several aspects. In this study, we identify the various inefficient points when controlling and managing wireless networks by using SDN and propose SDN-based control architecture called Proxcon to resolve these problems. Proxcon introduces the concept of a proxy SDN controller (PSC for the wireless network control, and the PSC entrusted with the role of a main controller performs control operations and provides the latest network state for a network administrator. To address the control inefficiency, Proxcon supports offloaded SDN operations for controlling wireless networks by utilizing the PSC, such as local control by each PSC, hybrid control utilizing the PSC and the main controller, and locally cooperative control utilizing the PSCs. The proposed architecture and the newly supported control operations can enhance scalability and response time when the logically centralized control plane responds to the various wireless network events. Through actual experiments, we verified that the proposed architecture could address the various control issues such as scalability, response time, and control overhead.

Wireless radio channel for intramuscular electrode implants in the control of upper limb prostheses.

Science.gov (United States)

Stango, Antonietta; Yazdandoost, Kamya Yekeh; Farina, Dario

2015-01-01

In the last few years the use of implanted devices has been considered also in the field of myoelectric hand prostheses. Wireless implanted EMG (Electromyogram) sensors can improve the functioning of the prosthesis, providing information without the disadvantage of the wires, and the usability by amputees. The solutions proposed in the literature are based on proprietary communication protocols between the implanted devices and the prosthesis controller, using frequency bands that are already assigned to other purposes. This study proposes the use of a standard communication protocol (IEEE 802.15.6), specific for wireless body area networks (WBANs), which assign a specific bandwidth to implanted devices. The propagation losses from in-to-on body were investigated by numerical simulation with a 3D human model and an electromagnetic solver. The channel model resulting from the study represents the first step towards the development of myoelectric prosthetic hands which are driven by signals acquired by implanted sensors. However these results can provide important information to researchers for further developments, and manufacturers, which can decrease the production costs for hand prostheses having a common standard of communication with assigned frequencies of operation.

Wireless Testbed Bonsai

Science.gov (United States)

2006-02-01

wireless sensor device network, and a about 200 Stargate nodes higher-tier multi-hop peer- to-peer 802.11b wireless network. Leading up to the full ExScal...deployment, we conducted spatial scaling tests on our higher-tier protocols on a 7 × 7 grid of Stargates nodes 45m and with 90m separations respectively...onW and its scaled version W̃ . III. EXPERIMENTAL SETUP Description of Kansei testbed. A stargate is a single board linux-based computer [7]. It uses a

Pervasive wireless environments

CERN Document Server

Yang, Jie; Trappe, Wade; Cheng, Jerry

2014-01-01

This Springer Brief provides a new approach to prevent user spoofing by using the physical properties associated with wireless transmissions to detect the presence of user spoofing. The most common method, applying cryptographic authentication, requires additional management and computational power that cannot be deployed consistently. The authors present the new approach by offering a summary of the recent research and exploring the benefits and potential challenges of this method. This brief discusses the feasibility of launching user spoofing attacks and their impact on the wireless and sen

Burroughs's Postcolonial Visions in The Yage Letters

OpenAIRE

Keomany, Melanie

2016-01-01

In her article "Burroughs's Postcolonial Visions in The Yage Letters" Melanie Keomany discusses the contents of William S. Burroughs and Allen Ginsberg's The Yage Letters which could be dismissed as openly bigoted and racist. Keomany posits that the text reveals valuable connections between the colonial expansion of the eighteenth century and 1950s USA and Latin America. By re-shaping Burroughs's lived experiences in the Amazon into a text where the narrator William Lee mimics sardonically an...

Letters to a Young Writer.

Science.gov (United States)

Waldman, Anne; Becker, Robin

2002-01-01

Presents words of encouragement to a young poet. Includes empathetic words and motivating ideas. Presents a letter including a quote from "Tintern Abbey" by William Wordsworth and ideas about that quote. (SG)

Wireless Communications in Smart Grid

Science.gov (United States)

Bojkovic, Zoran; Bakmaz, Bojan

Communication networks play a crucial role in smart grid, as the intelligence of this complex system is built based on information exchange across the power grid. Wireless communications and networking are among the most economical ways to build the essential part of the scalable communication infrastructure for smart grid. In particular, wireless networks will be deployed widely in the smart grid for automatic meter reading, remote system and customer site monitoring, as well as equipment fault diagnosing. With an increasing interest from both the academic and industrial communities, this chapter systematically investigates recent advances in wireless communication technology for the smart grid.

Wireless home networking for dummies

CERN Document Server

Briere, Danny; Ferris, Edward

2010-01-01

The perennial bestseller shows you how share your files and Internet connection across a wireless network. Fully updated for Windows 7 and Mac OS X Snow Leopard, this new edition of this bestseller returns with all the latest in wireless standards and security. This fun and friendly guide shows you how to integrate your iPhone, iPod touch, smartphone, or gaming system into your home network. Veteran authors escort you through the various financial and logisitical considerations that you need to take into account before building a wireless network at home.: Covers the basics of planning, instal

Distributed medium access control in wireless networks

CERN Document Server

Wang, Ping

2013-01-01

This brief investigates distributed medium access control (MAC) with QoS provisioning for both single- and multi-hop wireless networks including wireless local area networks (WLANs), wireless ad hoc networks, and wireless mesh networks. For WLANs, an efficient MAC scheme and a call admission control algorithm are presented to provide guaranteed QoS for voice traffic and, at the same time, increase the voice capacity significantly compared with the current WLAN standard. In addition, a novel token-based scheduling scheme is proposed to provide great flexibility and facility to the network servi

The impact of familiarization strategies on the missing-letter effect.

Science.gov (United States)

Plamondon, Andréanne; Roy-Charland, Annie; Chamberland, Justin; Quenneville, Joannie; Laforge, Christian

2017-08-01

When reading a text and searching for a target letter, readers make more omissions of the target letter if it is embedded in frequent function words than if it is in rare content words. While word frequency effects are consistently found, few studies have examined the impacts of passage familiarity on the missing-letter effect and studies that have present conflicting evidence. The present study examines the effects of passage familiarity, as well as the impacts of passage familiarization strategy promoting surface or deep encoding, on the missing-letter effect. Participants were familiarized with a passage by retyping a text, replacing all common nouns with synonyms, or generating a text on the same topic as that of the original text, and then completed a letter search task on the familiar passage as well as an unfamiliar passage. In Experiment 1, when both familiar and unfamiliar passages use the same words, results revealed fewer omissions for the retyping and synonyms conditions. However, in Experiment 2, when different words are used in both types of texts, no effect of familiarization strategy was observed. Furthermore, the missing-letter effect is maintained in all conditions, adding support to the robustness of the effect regardless of familiarity with the text.

NASA Bluetooth Wireless Communications

Science.gov (United States)

Miller, Robert D.

2007-01-01

NASA has been interested in wireless communications for many years, especially when the crew size of the International Space Station (ISS) was reduced to two members. NASA began a study to find ways to improve crew efficiency to make sure the ISS could be maintained with limited crew capacity and still be a valuable research testbed in Low-Earth Orbit (LEO). Currently the ISS audio system requires astronauts to be tethered to the audio system, specifically a device called the Audio Terminal Unit (ATU). Wireless communications would remove the tether and allow astronauts to freely float from experiment to experiment without having to worry about moving and reconnecting the associated cabling or finding the space equivalent of an extension cord. A wireless communication system would also improve safety and reduce system susceptibility to Electromagnetic Interference (EMI). Safety would be improved because a crewmember could quickly escape a fire while maintaining communications with the ground and other crewmembers at any location. In addition, it would allow the crew to overcome the volume limitations of the ISS ATU. This is especially important to the Portable Breathing Apparatus (PBA). The next generation of space vehicles and habitats also demand wireless attention. Orion will carry up to six crewmembers in a relatively small cabin. Yet, wireless could become a driving factor to reduce launch weight and increase habitable volume. Six crewmembers, each tethered to a panel, could result in a wiring mess even in nominal operations. In addition to Orion, research is being conducted to determine if Bluetooth is appropriate for Lunar Habitat applications.

Ultra-High Temperature Distributed Wireless Sensors

Energy Technology Data Exchange (ETDEWEB)

May, Russell; Rumpf, Raymond; Coggin, John; Davis, Williams; Yang, Taeyoung; O' Donnell, Alan; Bresnahan, Peter

2013-03-31

Research was conducted towards the development of a passive wireless sensor for measurement of temperature in coal gasifiers and coal-fired boiler plants. Approaches investigated included metamaterial sensors based on guided mode resonance filters, and temperature-sensitive antennas that modulate the frequency of incident radio waves as they are re-radiated by the antenna. In the guided mode resonant filter metamaterial approach, temperature is encoded as changes in the sharpness of the filter response, which changes with temperature because the dielectric loss of the guided mode resonance filter is temperature-dependent. In the mechanically modulated antenna approach, the resonant frequency of a vibrating cantilever beam attached to the antenna changes with temperature. The vibration of the beam perturbs the electrical impedance of the antenna, so that incident radio waves are phase modulated at a frequency equal to the resonant frequency of the vibrating beam. Since the beam resonant frequency depends on temperature, a Doppler radar can be used to remotely measure the temperature of the antenna. Laboratory testing of the guided mode resonance filter failed to produce the spectral response predicted by simulations. It was concluded that the spectral response was dominated by spectral reflections of radio waves incident on the filter. Laboratory testing of the mechanically modulated antenna demonstrated that the device frequency shifted incident radio waves, and that the frequency of the re-radiated waves varied linearly with temperature. Radio wave propagation tests in the convection pass of a small research boiler plant identified a spectral window between 10 and 13 GHz for low loss propagation of radio waves in the interior of the boiler.

System and method for time synchronization in a wireless network

Science.gov (United States)

Gonia, Patrick S.; Kolavennu, Soumitri N.; Mahasenan, Arun V.; Budampati, Ramakrishna S.

2010-03-30

A system includes multiple wireless nodes forming a cluster in a wireless network, where each wireless node is configured to communicate and exchange data wirelessly based on a clock. One of the wireless nodes is configured to operate as a cluster master. Each of the other wireless nodes is configured to (i) receive time synchronization information from a parent node, (ii) adjust its clock based on the received time synchronization information, and (iii) broadcast time synchronization information based on the time synchronization information received by that wireless node. The time synchronization information received by each of the other wireless nodes is based on time synchronization information provided by the cluster master so that the other wireless nodes substantially synchronize their clocks with the clock of the cluster master.

SIMULATION AND ANALYSIS OF GREEDY ROUTING PROTOCOL IN VIEW OF ENERGY CONSUMPTION AND NETWORK LIFETIME IN THREE DIMENSIONAL UNDERWATER WIRELESS SENSOR NETWORK

Directory of Open Access Journals (Sweden)

SHEENA KOHLI

2017-11-01

Full Text Available Underwater Wireless Sensor Network (UWSN comprises of a number of miniature sized sensing devices deployed in the sea or ocean, connected by dint of acoustic links to each other. The sensors trap the ambient conditions and transmit the data from one end to another. For transmission of data in any medium, routing protocols play a crucial role. Moreover, being battery limited, an unavoidable parameter to be considered in operation and analysis of protocols is the network energy and the network lifetime. The paper discusses the greedy routing protocol for underwater wireless sensor networks. The simulation of this routing protocol also takes into consideration the characteristics of acoustic communication like attenuation, transmission loss, signal to noise ratio, noise, propagation delay. The results from these observations may be used to construct an accurate underwater communication model.

Wireless synapses in bio-inspired neural networks

Science.gov (United States)

Jannson, Tomasz; Forrester, Thomas; Degrood, Kevin

2009-05-01

Wireless (virtual) synapses represent a novel approach to bio-inspired neural networks that follow the infrastructure of the biological brain, except that biological (physical) synapses are replaced by virtual ones based on cellular telephony modeling. Such synapses are of two types: intracluster synapses are based on IR wireless ones, while intercluster synapses are based on RF wireless ones. Such synapses have three unique features, atypical of conventional artificial ones: very high parallelism (close to that of the human brain), very high reconfigurability (easy to kill and to create), and very high plasticity (easy to modify or upgrade). In this paper we analyze the general concept of wireless synapses with special emphasis on RF wireless synapses. Also, biological mammalian (vertebrate) neural models are discussed for comparison, and a novel neural lensing effect is discussed in detail.

Next Generation Intelligent Wireless Infrastructure

DEFF Research Database (Denmark)

Toftegaard, Thomas Skjødeberg

2010-01-01

Given the commercial success of wireless technologies that has already taken place over the last couple of decades, with a global mobile communication penetration beyond 3 billion subscribers as well as the enormous success of wireless data communication through IEEE 802.11x and Bluetooth, people...

Traffic Profiling in Wireless Sensor Networks

National Research Council Canada - National Science Library

Kirykos, Georgios

2006-01-01

.... Wireless sensor networks pose unique challenges and limitations to the traditional schemes, which are used in the other wireless networks for security protection, and are due mainly to the increased...

Wireless sensor network adaptive cooling

Energy Technology Data Exchange (ETDEWEB)

Mitchell, T. [SynapSense Corp., Folsom, CA (United States)

2009-07-01

Options for reducing data centre cooling energy requirements and their cost savings were discussed with particular reference to a wireless control solution developed by SynapSense Corporation. The wireless sensor network reduces cooling energy use at data centres by providing improved air flow management through the installation of cold aisle containment. The use of this low cost, non-invasive wireless sensor network has reduced the cooling energy use in a data center at BC Hydro by 30 per cent. The system also reduced the server and storage fan energy by 3 per cent by maintaining inlet air temperature below ASHRAE recommended operating range. The distribution of low power, low cost wireless sensors has enabled visualization tools that are changing the way that data centres are managed. The annual savings have been estimated at 4,560,000 kWh and the annual carbon dioxide abatement is approximately 1,400 metric tons. tabs., figs.

Wireless Sensing Opportunities for Aerospace Applications

Directory of Open Access Journals (Sweden)

William Wilson

2008-07-01

Full Text Available Wireless sensors and sensor networks is an emerging technology area with many applications within the aerospace industry. Integrated vehicle health monitoring (IVHM of aerospace vehicles is needed to ensure the safety of the crew and the vehicle, yet often high costs, weight, size and other constraints prevent the incorporation of instrumentation onto spacecraft. This paper presents a few of the areas such as IVHM, where new wireless sensing technology is needed on both existing vehicles as well as future spacecraft. From ground tests to inflatable structures to the International Space Station, many applications could receive benefits from small, low power, wireless sensors. This paper also highlights some of the challenges that need to overcome when implementing wireless sensor networks for aerospace vehicles.

A Survey on Underwater Wireless Sensor Networks: Progresses, Applications, and Challenges

Directory of Open Access Journals (Sweden)

Premalatha J.

2016-01-01

Full Text Available The endangered underwater species always drew the attention of the scientific society since their disappearance would cause irreplaceable loss. Asia is home to some of the most diverse habitats in the earth, but it is estimated that more than one in four species are endangered. In Underwater, a lot of factors are putting marine life under immense pressure. Extreme population pressure is leading to pollution, over-fishing and the devastation of crucial habitats. Consequently, the numbers of almost all fish are declining and many are already endangered. To help these species to survive, their habitat should be strictly protected. This can be achieved by strictly monitoring them. During this course, several parameters, constraints about the species and its environments are focused. Now, advances in sensor technology facilitate the monitoring of species and their habitat with less expenditure. Indeed, the increasing sophistication of underwater wireless sensors offers chances that enable new challenges in a lot of areas, like surveillance one. This paper endorses the use of sensors for monitoring underwater species endangered in their habitat. This paper further examines the key approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize major applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers.

Open letter to EU Commission about proposed EDC Criteria

DEFF Research Database (Denmark)

Ågerstrand, Marlene; Bero, Lisa; Beronius, Anna

2016-01-01

Open letter in response to the proposed criteria for identification and regulation of endocrine disrupting chemicals, under the PPP and Biocides Regulations......Open letter in response to the proposed criteria for identification and regulation of endocrine disrupting chemicals, under the PPP and Biocides Regulations...

50 CFR 216.258 - Renewal of Letters of Authorization.

Science.gov (United States)

2010-10-01

... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS Taking Marine Mammals Incidental to Conducting Precision Strike Weapon Missions in the Gulf of Mexico § 216.258 Renewal of Letters of Authorization. (a) A Letter of Authorization...

Resource slicing in virtual wireless networks: a survey

OpenAIRE

Richart, Matias; Baliosian De Lazzari, Javier Ernesto; Serrat Fernández, Juan; Gorricho Moreno, Juan Luis

2016-01-01

New architectural and design approaches for radio access networks have appeared with the introduction of network virtualization in the wireless domain. One of these approaches splits the wireless network infrastructure into isolated virtual slices under their own management, requirements, and characteristics. Despite the advances in wireless virtualization, there are still many open issues regarding the resource allocation and isolation of wireless slices. Because of the dynamics and share...

Wireless telecommunication systems

CERN Document Server

Terré, Michel; Vivier, Emmanuelle

2013-01-01

Wireless telecommunication systems generate a huge amount of interest. In the last two decades, these systems have experienced at least three major technological leaps, and it has become impossible to imagine how society was organized without them. In this book, we propose a macroscopic approach on wireless systems, and aim at answering key questions about power, data rates, multiple access, cellular engineering and access networks architectures.We present a series of solved problems, whose objective is to establish the main elements of a global link budget in several radiocommunicati

Sustainable wireless networks

CERN Document Server

Zheng, Zhongming; Xuemin

2013-01-01

This brief focuses on network planning and resource allocation by jointly considering cost and energy sustainability in wireless networks with sustainable energy. The characteristics of green energy and investigating existing energy-efficient green approaches for wireless networks with sustainable energy is covered in the first part of this brief. The book then addresses the random availability and capacity of the energy supply. The authors explore how to maximize the energy sustainability of the network and minimize the failure probability that the mesh access points (APs) could deplete their

The “Wireless Sensor Networks for City-Wide Ambient Intelligence (WISE-WAI)” Project

Science.gov (United States)

Casari, Paolo; Castellani, Angelo P.; Cenedese, Angelo; Lora, Claudio; Rossi, Michele; Schenato, Luca; Zorzi, Michele

2009-01-01

This paper gives a detailed technical overview of some of the activities carried out in the context of the “Wireless Sensor networks for city-Wide Ambient Intelligence (WISE-WAI)” project, funded by the Cassa di Risparmio di Padova e Rovigo Foundation, Italy. The main aim of the project is to demonstrate the feasibility of large-scale wireless sensor network deployments, whereby tiny objects integrating one or more environmental sensors (humidity, temperature, light intensity), a microcontroller and a wireless transceiver are deployed over a large area, which in this case involves the buildings of the Department of Information Engineering at the University of Padova. We will describe how the network is organized to provide full-scale automated functions, and which services and applications it is configured to provide. These applications include long-term environmental monitoring, alarm event detection and propagation, single-sensor interrogation, localization and tracking of objects, assisted navigation, as well as fast data dissemination services to be used, e.g., to rapidly re-program all sensors over-the-air. The organization of such a large testbed requires notable efforts in terms of communication protocols and strategies, whose design must pursue scalability, energy efficiency (while sensors are connected through USB cables for logging and debugging purposes, most of them will be battery-operated), as well as the capability to support applications with diverse requirements. These efforts, the description of a subset of the results obtained so far, and of the final objectives to be met are the scope of the present paper. PMID:22408513

David Bohm : causality and chance, letters to three women

CERN Document Server

2017-01-01

The letters transcribed in this book were written by physicist David Bohm to three close female acquaintances in the period 1950 to 1956. They provide a background to his causal interpretation of quantum mechanics and the Marxist philosophy that inspired his scientific work in quantum theory, probability and statistical mechanics. In his letters, Bohm reveals the ideas that led to his ground breaking book Causality and Chance in Modern Physics. The political arguments as well as the acute personal problems contained in these letters help to give a rounded, human picture of this leading scientist and twentieth century thinker.

A wireless acoustic emission sensor remotely powered by light

International Nuclear Information System (INIS)

Zahedi, F; Huang, H

2014-01-01

In this paper, wireless sensing of acoustic emission (AE) signals using a battery-free sensor node remotely powered by light is presented. The wireless sensor consists of a piezoelectric wafer active sensor (PWAS) for AE signal acquisition and a wireless transponder that performs signal conditioning, frequency conversion, and wireless transmission. For signal conditioning, a voltage follower that consumes less than 2 mW was introduced to buffer the high impedance of the PWAS from the low impedance of the wireless transponder. A photocell-based energy harvester with a stable voltage output was developed to power the voltage follower so that the wireless AE sensor can operate without an external power source. The principle of operation of the battery-free wireless AE sensor node and the sensor interrogation system is described, followed by a detailed description of the hardware implementation. The voltage follower and the wireless channel were characterized by ultrasound pitch–catch and pencil lead break experiments. (paper)

Contributions of Emergent Literacy Skills to Name Writing, Letter Writing, and Spelling in Preschool Children

Science.gov (United States)

Puranik, Cynthia S.; Lonigan, Christopher J.; Kim, Young-Suk

2011-01-01

The purpose of this study was to examine which emergent literacy skills contribute to preschool children’s emergent writing (name-writing, letter-writing, and spelling) skills. Emergent reading and writing tasks were administered to 296 preschool children aged 4–5 years. Print knowledge and letter-writing skills made positive contributions to name writing; whereas alphabet knowledge, print knowledge, and name writing made positive contributions to letter writing. Both name-writing and letter-writing skills made significant contributions to the prediction of spelling after controlling for age, parental education, print knowledge, phonological awareness, and letter-name and letter-sound knowledge; however, only letter-writing abilities made a significant unique contribution to the prediction of spelling when both letter-writing and name-writing skills were considered together. Name writing reflects knowledge of some letters rather than a broader knowledge of letters that may be needed to support early spelling. Children’s letter-writing skills may be a better indicator of children’s emergent literacy and developing spelling skills than are their name-writing skills at the end of the preschool year. Spelling is a developmentally complex skill beginning in preschool and includes letter writing and blending skills, print knowledge, and letter-name and letter-sound knowledge. PMID:21927537

Virtual Lab for Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

PICOVICI, D.

2008-06-01

Full Text Available This article details an experimental system developed to enhance the education and research in the area of wireless networks technologies. The system referred, as Virtual Lab (VL is primarily targeting first time users or users with limited experience in programming and using wireless sensor networks. The VL enables a set of predefined sensor networks to be remotely accessible and controlled for constructive and time-efficient experimentation. In order to facilitate the user's wireless sensor applications, the VL is using three main components: a a Virtual Lab Motes (VLM, representing the wireless sensor, b a Virtual Lab Client (VLC, representing the user's tool to interact with the VLM and c a Virtual Lab Server (VLS representing the software link between the VLM and VLC. The concept has been proven using the moteiv produced Tmote Sky modules. Initial experimental use clearly demonstrates that the VL approach reduces dramatically the learning curve involved in programming and using the associated wireless sensor nodes. In addition the VL allows the user's focus to be directed towards the experiment and not towards the software programming challenges.

Channel Measurements and Modeling at 6 GHz in the Tunnel Environments for 5G Wireless Systems

Directory of Open Access Journals (Sweden)

Shuang-de Li

2017-01-01

Full Text Available Propagation measurements of wireless channels performed in the tunnel environments at 6 GHz are presented in this paper. Propagation characteristics are simulated and analyzed based on the method of shooting and bouncing ray tracing/image (SBR/IM. A good agreement is achieved between the measured results and simulated results, so the correctness of SBR/IM method has been validated. The measured results and simulated results are analyzed in terms of path loss models, received power, root mean square (RMS delay spread, Ricean K-factor, and angle of arrival (AOA. The omnidirectional path loss models are characterized based on close-in (CI free-space reference distance model and the alpha-beta-gamma (ABG model. Path loss exponents (PLEs are 1.50–1.74 in line-of-sight (LOS scenarios and 2.18–2.20 in non-line-of-sight (NLOS scenarios. Results show that CI model with the reference distance of 1 m provides more accuracy and stability in tunnel scenarios. The RMS delay spread values vary between 2.77 ns and 18.76 ns. Specially, the Poisson distribution best fits the measured data of RMS delay spreads for LOS scenarios and the Gaussian distribution best fits the measured data of RMS delay spreads for NLOS scenarios. Moreover, the normal distribution provides good fits to the Ricean K-factor. The analysis of the abovementioned results from channel measurements and simulations may be utilized for the design of wireless communications of future 5G radio systems at 6 GHz.

SystemC modelling of wireless communication channel

Science.gov (United States)

Conti, Massimo; Orcioni, Simone

2011-05-01

This paper presents the definition in SystemC of wireless channels at different levels of abstraction. The different levels of description of the wireless channel can be easily interchanged allowing the reuse of the application and baseband layers in a high level analysis of the network or in a deep analysis of the communication between the wireless devices.

Wireless Competition in Canada: An Assessment

Directory of Open Access Journals (Sweden)

Jeffrey Church

2013-08-01

Full Text Available If there’s one thing Canadians agree on, it’s that Canada’s wireless industry can and should be more competitive. The federal government is on side with the policy objective of having four carriers in every region and has responded with policies that provide commercial advantages to entrants. But, the rub is that there has not been a study that actually assesses the state of competition in wireless services in Canada, until now. Those in favour of policies that will promote and sustain entry point to Canada’s high average revenue per user and low wireless penetration rate (mobile connections per capita as evidence that there is insufficient competition. The difficulty is that the facts are not consistent with this simplistic analysis. Measurements of wireless penetration are skewed toward countries that maintain the Calling Party Pays Protocol and favour pay-as-you-go plans, both of which encourage inflated user counts. Canada’s participation per capita on monthly plans and minutes of voice per capita are not outliers. Moreover, in terms of smartphone adoption and smartphone data usage, Canada is a global leader, contributing to high average revenue per user. Consistent with being world leaders in the rollout of high speed wireless networks, Canada lead its peer group in capital expenditures per subscriber in 2012: the competition of importance to Canadians is not just over price, but also over the quality of wireless networks. In any event, none of the measures typically used in international comparisons are relevant to assessing the competitiveness of Canadian wireless services. The appropriate competitive analysis recognizes two relevant features of the technology of wireless services: (i high fixed and sunk capital costs; and (ii economies of scale and scope. The implications of these are that profitability requires mark ups over short run measures of cost — high gross margins — and that there will be a natural, upper limit on

Supporting Adaptation of Wireless Communication Protocols

International Nuclear Information System (INIS)

Dhomeja, L.D.; Soomro, I.A.; Malkani, Y.A.

2016-01-01

Pervasive devices such as mobile phones and PDAs (Personal Digital Assistants) come with different wireless communication capabilities, for example, WiFi (Wireless Fidelity), Bluetooth, IrDA (Infrared), etc. In order for pervasive devices to interact with each other, they need to have matching (alike) communication capabilities, otherwise such heterogeneous devices would not be able to interact with each other. In this paper we address this issue and propose a system that makes devices with heterogeneous wireless communication capabilities communicate with each other. The proposed system supports adaptation of wireless communication protocols through a proxy, which sits between a client and a server, and supports adaptation of wireless communication protocols. Its functionality involves intercepting a request made by a client with a different wireless communication capability (e.g. Bluetooth) from what the server has (e.g. WiFi), connecting to the server and then sending results back to the client. We have tested the system by implementing a messaging service application and running it on the system. The proxy supports all Bluetooth protocols, i.e. OBEX (Object Exchange), L2CAP (Logical Link Control and Adaptation Protocol), RFCOM (Radio Frequency Communication) and WiFi protocol and can run on (J2MW (Java 2 Micro Edition) enabled mobile phones which support both Bluetooth and WiFi capabilities. (author)

LETTERS OF MARIA KUNCEWICZOWA TO HER LATE HUSBAND

Directory of Open Access Journals (Sweden)

Anna Wzorek

2017-04-01

Full Text Available The article discusses the last book of Maria Kuncewiczowa – a set of twenty-three letters (provided with a postscript addressed to her deceased husband. The uniqueness of this correspondence, presented in literary form, lies in the fact that the recipient is dead, treated by the sender as someone constantly present in the real world and still associated with the temporality. "Listy do Jerzego" ("Letters to Jerzy" are – as Tadeusz Swat, one of the reviewers say – “an attempt at denial of death, to save Jerzy by love, memory, and literature.” The analysis of the work highlights the occurring axiological categories. It has been demonstrated that "Letters to Jerzy" is a book about eternal love reaching beyond the grave (in this respect, in stark contrast with "Tristan" 1946, felt with dignity of old age, and finally transcending into faith. "Letters to Jerzy" is also an attempt to reduce the suffering of the writer over the loss of her beloved husband. To some extent, therefore, they correspond to her earlier work "Cudzoziemka" ("Foreigner" in which Kuncewiczowa liberates from the negative emotions associated with the death of her mother.

Partnership Opportunities with AFRC for Wireless Systems Flight Testing

Science.gov (United States)

Hang, Richard

2015-01-01

The presentation will overview the flight test capabilities at NASA Armstrong Flight Research Center (AFRC), to open up partnership collaboration opportunities for Wireless Community to conduct flight testing of aerospace wireless technologies. Also, it will brief the current activities on wireless sensor system at AFRC through SBIR (Small Business Innovation Research) proposals, and it will show the current areas of interest on wireless technologies that AFRC would like collaborate with Wireless Community to further and testing.

Referral letters to the psychiatrist in Nigeria: is communication ...

African Journals Online (AJOL)

history, may not be elements that non-psychiatrist phy- sicians routinely collect during their examinations and, therefore, one would not expect such information to be available to be included in referral letters. Conclusion. Deficits in communication or information transfer through referral letters to the psychiatrist are common.

Referral letters to the psychiatrist in Nigeria: is communication ...

African Journals Online (AJOL)

Result: A majority (>80%) of the referral letters had no information on the current medication list, relevant psychosocial history, outline of management to date, results of investigations to date, and known allergies. Conclusion: Deficits in communication or information transfer through referral letters to the psychiatrist are ...

Future Wireless Networks and Information Systems Volume 1

CERN Document Server

2012-01-01

This volume contains revised and extended research articles written by prominent researchers participating in ICFWI 2011 conference. The 2011 International Conference on Future Wireless Networks and Information Systems (ICFWI 2011) has been held on November 30 ~ December 1, 2011, Macao, China. Topics covered include Wireless Information Networks, Wireless Networking Technologies, Mobile Software and Services, intelligent computing, network management, power engineering, control engineering, Signal and Image Processing, Machine Learning, Control Systems and Applications, The book will offer the states of arts of tremendous advances in Wireless Networks and Information Systems and also serve as an excellent reference work for researchers and graduate students working on Wireless Networks and Information Systems.

Love letters to the dead: resurrecting an epistolary art.

Science.gov (United States)

Lander, Dorothy A; Graham-Pole, John R

This article explores the art of letter-writing, specifically to our beloved dead, as a form of autoethnographic research, pedagogy, and care work. As university teachers and qualitative researchers in palliative and end-of-life care, we review the literature and history of epistolary communications with the deceased, as a prelude to writing our own letters. John writes to his long-dead mother and Dorothy to her recently deceased spouse Patrick, each letter followed by a reflective dialogue between us. Through this dialogue, we highlight the potential application of this art, or handcraft, to formal and informal palliative care, and the implications for practice, pedagogy, policy, and research. We propose that such direct, non-mediated, communications can offer a valuable form of healing for bereaved people. The therapeutic potential of letter writing and the abundance of literary and popular culture exemplars of responses from the dead are also largely unexplored in death education and research.

Computer-Based Wireless Advertising Communication System

Directory of Open Access Journals (Sweden)

Anwar Al-Mofleh

2009-10-01

Full Text Available In this paper we developed a computer based wireless advertising communication system (CBWACS that enables the user to advertise whatever he wants from his own office to the screen in front of the customer via wireless communication system. This system consists of two PIC microcontrollers, transmitter, receiver, LCD, serial cable and antenna. The main advantages of the system are: the wireless structure and the system is less susceptible to noise and other interferences because it uses digital communication techniques.

Adaptive Naive Bayes classification for wireless sensor networks

NARCIS (Netherlands)

Zwartjes, G.J.

2017-01-01

Wireless Sensor Networks are tiny devices equipped with sensors and wireless communication. These devices observe environments and communicatie about these observations. Machine Learning techniques are of interest for Wireless Sensor Network applications since they can reduce the amount of needed

REVIEW OF WIRELESS MIMO CHANNEL MODELS

African Journals Online (AJOL)

user

MIMO wireless system, the transmitted signal interacts ... delay spread information, power delay profile, angle of arrival and ... With the advent of the MIMO wireless systems, there arose a ..... associated with channel transmission and reception.

Letters in this Issue

Science.gov (United States)

1998-01-01

Reforming the General Chemistry Textbook individual letters by Edward T. Samulski; Stephen J. Hawkes; Stephen J. Fisher; J. Stephen Hartman; A. R. H. Cole; Stanley Pine, Ronald Archer, and Herbert Kaesz; Jimmy Reeves; Robert Hill; and Brock Spencer, C. Bradley Moore and Nedah Rose. Re: article by R. J. Gillespie The author replies

Advanced Wireless Sensor Nodes - MSFC

Science.gov (United States)

Varnavas, Kosta; Richeson, Jeff

2017-01-01

NASA field center Marshall Space Flight Center (Huntsville, AL), has invested in advanced wireless sensor technology development. Developments for a wireless microcontroller back-end were primarily focused on the commercial Synapse Wireless family of devices. These devices have many useful features for NASA applications, good characteristics and the ability to be programmed Over-The-Air (OTA). The effort has focused on two widely used sensor types, mechanical strain gauges and thermal sensors. Mechanical strain gauges are used extensively in NASA structural testing and even on vehicle instrumentation systems. Additionally, thermal monitoring with many types of sensors is extensively used. These thermal sensors include thermocouples of all types, resistive temperature devices (RTDs), diodes and other thermal sensor types. The wireless thermal board will accommodate all of these types of sensor inputs to an analog front end. The analog front end on each of the sensors interfaces to the Synapse wireless microcontroller, based on the Atmel Atmega128 device. Once the analog sensor output data is digitized by the onboard analog to digital converter (A/D), the data is available for analysis, computation or transmission. Various hardware features allow custom embedded software to manage battery power to enhance battery life. This technology development fits nicely into using numerous additional sensor front ends, including some of the low-cost printed circuit board capacitive moisture content sensors currently being developed at Auburn University.

Wireless Connectivity to ATM Communication Grid

National Research Council Canada - National Science Library

Rajaravivarma, Veeramuthu

1998-01-01

The AFOSR funds were used to purchase a 12 port Fore ATM switch, ATM network interface cards, a SUN UltraSPARC workstation, Lucent WavePoint wireless bridge, and Lucent WaveLAN wireless network interface cards...

Wireless Underground Sensor Networks: Channel Modeling and Operation Analysis in the Terahertz Band

Directory of Open Access Journals (Sweden)

Mustafa Alper Akkaş

2015-01-01

Full Text Available Wireless underground sensor networks (WUSNs are networks of sensor nodes operating below the ground surface, which are envisioned to provide real-time monitoring capabilities in the complex underground environments consisting of soil, water, oil, and other components. In this paper, we investigate the possibilities and limitations of using WUSNs for increasing the efficiency of oil recovery processes. To realize this, millimeter scale sensor nodes with antennas at the same scale should be deployed in the confined oil reservoir fractures. This necessitates the sensor nodes to be operating in the terahertz (THz range and the main challenge is establishing reliable underground communication despite the hostile environment which does not allow the direct use of most existing wireless solutions. The major problems are extremely high path loss, small communication range, and high dynamics of the electromagnetic (EM waves when penetrating through soil, sand, and water and through the very specific crude oil medium. The objective of the paper is to address these issues in order to propose a novel communication channel model considering the propagation properties of terahertz EM waves in the complex underground environment of the oil reservoirs and to investigate the feasible transmission distances between nodes for different water-crude-oil-soil-CO2 compositions.

Experimental Performance Analysis of Wireless Links for Healthcare ...

African Journals Online (AJOL)

Wireless networking is currently being deployed for various applications. However, the application of wireless networking in healthcare remains a challenge mainly because of security and reliability concerns. This paper presents experimental results of performance analysis of a wireless network for healthcare application ...

Indoor optical wireless systems : technology, trends, and applications

NARCIS (Netherlands)

Koonen, T.

2018-01-01

Indoor wireless traffic is evolving at a staggering pace, and is quickly depleting radio spectrum resources. Optical wireless communication (OWC) offers powerful solutions for resolving this imminent capacity crunch of radio-based wireless networks. OWC is not intended to fully replace radio

Next-generation wireless technologies 4G and beyond

CERN Document Server

Chilamkurti, Naveen; Chaouchi, Hakima

2013-01-01

This comprehensive text/reference examines the various challenges to secure, efficient and cost-effective next-generation wireless networking. Topics and features: presents the latest advances, standards and technical challenges in a broad range of emerging wireless technologies; discusses cooperative and mesh networks, delay tolerant networks, and other next-generation networks such as LTE; examines real-world applications of vehicular communications, broadband wireless technologies, RFID technology, and energy-efficient wireless communications; introduces developments towards the 'Internet o

Remote Access Unit for Optic-to-Wireless Conversion

DEFF Research Database (Denmark)

Chorchos, Łukasz; Rommel, Simon; Turkiewicz, J. P.

. Growing demand for high speed wireless data transmission and new wireless standards like 5G force network operators to find new solutions for backhaul networks. Presently, to meet this need, attention of many researchers and top network vendors has been directed towards millimeter wave radio links....... Operation in the millimeter wave range brings new possibilities for a channel allocation as well as allows wider radio channels to be used. Moreover this frequency range is lighter licensed than regular GSM. This clearly shows a huge potential of millimeter waves for a high speed wireless data transmission...... was proposed and research projects like IPHOBAC-NG were founded. The aim of the mentioned project is to employ novel RAUs featuring opticto-wireless and wireless-to-optic conversion with a speeds of 1-10Gbit/s for broadband wireless access and up to 3Gbit/s for mobile backhaul. The RAU proposed in this paper...

Letter processing and font information during reading: beyond distinctiveness, where vision meets design.

Science.gov (United States)

Sanocki, Thomas; Dyson, Mary C

2012-01-01

Letter identification is a critical front end of the reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading.

How to model wireless mesh networks topology

International Nuclear Information System (INIS)

Sanni, M L; Hashim, A A; Anwar, F; Ali, S; Ahmed, G S M

2013-01-01

The specification of network connectivity model or topology is the beginning of design and analysis in Computer Network researches. Wireless Mesh Networks is an autonomic network that is dynamically self-organised, self-configured while the mesh nodes establish automatic connectivity with the adjacent nodes in the relay network of wireless backbone routers. Researches in Wireless Mesh Networks range from node deployment to internetworking issues with sensor, Internet and cellular networks. These researches require modelling of relationships and interactions among nodes including technical characteristics of the links while satisfying the architectural requirements of the physical network. However, the existing topology generators model geographic topologies which constitute different architectures, thus may not be suitable in Wireless Mesh Networks scenarios. The existing methods of topology generation are explored, analysed and parameters for their characterisation are identified. Furthermore, an algorithm for the design of Wireless Mesh Networks topology based on square grid model is proposed in this paper. The performance of the topology generated is also evaluated. This research is particularly important in the generation of a close-to-real topology for ensuring relevance of design to the intended network and validity of results obtained in Wireless Mesh Networks researches

Development and Operation of Dual-Mode Analyzers for Wireless Power Consortium/Power Matters Alliance Wireless Power Systems.

Science.gov (United States)

Um, Keehong

2016-05-01

We have designed a protocol analyzer to be used in wireless power systems and analyzed the operation of wireless chargers defined by standards of Qi of Wireless Power Consortium (WPC) and Power Matters Alliance (PMA) protocols. The integrated circuit (IC, or microchip) developed so far for wireless power transmission is not easily adopted by chargers for specific purposes. A device for measuring the performance of test equipment currently available is required to transform and expand the types of protocol. Since a protocol analyzer with these functions is required, we have developed a device that can analyze the two protocols of WPC and PMA at the same time. As a result of our research, we present a dual-mode system that can analyze the protocols of both WPC and PMA.

Characterization of In-Body to On-Body Wireless Radio Frequency Link for Upper Limb Prostheses.

Directory of Open Access Journals (Sweden)

Antonietta Stango

Full Text Available Wireless implanted devices can be used to interface patients with disabilities with the aim of restoring impaired motor functions. Implanted devices that record and transmit electromyographic (EMG signals have been applied for the control of active prostheses. This simulation study investigates the propagation losses and the absorption rate of a wireless radio frequency link for in-to-on body communication in the medical implant communication service (MICS frequency band to control myoelectric upper limb prostheses. The implanted antenna is selected and a suitable external antenna is designed. The characterization of both antennas is done by numerical simulations. A heterogeneous 3D body model and a 3D electromagnetic solver have been used to model the path loss and to characterize the specific absorption rate (SAR. The path loss parameters were extracted and the SAR was characterized, verifying the compliance with the guideline limits. The path loss model has been also used for a preliminary link budget analysis to determine the feasibility of such system compliant with the IEEE 802.15.6 standard. The resulting link margin of 11 dB confirms the feasibility of the system proposed.

The Syntax of Persuasion: Two Business Letters of Request.

Science.gov (United States)

Limaye, Mohan R.

1983-01-01

Business letter-writers are advised to develop reader empathy and benefit before they ask a favor. The author analyzed two model 16th century letters of request to determine if similar advice was given in the past, and found that the request was subordinate to building a mutually beneficial relationship. (PD)

Undergraduate nursing students writing therapeutic letters to families: an educational strategy.

Science.gov (United States)

Erlingsson, Christen

2009-02-01

Writing therapeutic letters to families is discussed in this article as an educational strategy encouraging students to think reflectively about family nursing. At the University of Kalmar, Sweden, undergraduate nursing students in a primary care module interviewed families using the Calgary Family Assessment Model and wrote therapeutic letters to these families. This article describes (a) the examination process, which was the context for writing therapeutic letters, (b) results of analyses of the letters, and (c) student's post-examination evaluation comments. Results indicate that most students needed encouragement to focus on the family's strengths and resources instead of focusing on own feelings or problems they perceived the family as having. Students also needed support in relinquishing their hierarchical role of "expert nurse." Students' evaluation comments showed that writing therapeutic letters provided students with opportunities to reflect about the connections between family nursing theory and the family itself.

A Fragmentary Archive: Migratory Feelings in Early Anglo-Saxon Women's Letters.

Science.gov (United States)

Watt, Diane

2017-01-01

The letters by Anglo-Saxon women in the Boniface correspondence are connected by cultural practices and emotions centered on the conversion mission that functioned to maintain connections between the Anglo-Saxon diaspora. A striking recurring focus of these letters is on loss and isolation, which connects them to the Old English elegies. Many of the letters describe the writers' traumatic experiences that result from the death or absence of kin. These are women who endured the trauma of being left behind when others migrated overseas or who, in traveling away from their homeland, found themselves isolated in an alien environment, displaced in time as well as space. This article offers an analysis of the letters, focusing on the queer temporalities they explore, the queer emotions they evoke, and the queer kinships that they forge. It argues that the women's letters represent fragments of an early queer archive of migratory feelings.

Filtering and control of wireless networked systems

CERN Document Server

Zhang, Dan; Yu, Li

2017-01-01

This self-contained book, written by leading experts, offers a cutting-edge, in-depth overview of the filtering and control of wireless networked systems. It addresses the energy constraint and filter/controller gain variation problems, and presents both the centralized and the distributed solutions. The first two chapters provide an introduction to networked control systems and basic information on system analysis. Chapters (3–6) then discuss the centralized filtering of wireless networked systems, presenting different approaches to deal with energy efficiency and filter/controller gain variation problems. The next part (chapters 7–10) explores the distributed filtering of wireless networked systems, addressing the main problems of energy constraint and filter gain variation. The final part (chapters 11–14) focuses on the distributed control of wireless networked systems. wireless networked systems for communication and control applications, the bo...

Practice brief. Securing wireless technology for healthcare.

Science.gov (United States)

Retterer, John; Casto, Brian W

2004-05-01

Wireless networking can be a very complex science, requiring an understanding of physics and the electromagnetic spectrum. While the radio theory behind the technology can be challenging, a basic understanding of wireless networking can be sufficient for small-scale deployment. Numerous security mechanisms are available to wireless technologies, making it practical, scalable, and affordable for healthcare organizations. The decision on the selected security model should take into account the needs for additional server hardware and administrative costs. Where wide area network connections exist between cooperative organizations, deployment of a distributed security model can be considered to reduce administrative overhead. The wireless approach chosen should be dynamic and concentrate on the organization's specific environmental needs. Aspects of organizational mission, operations, service level, and budget allotment as well as an organization's risk tolerance are all part of the balance in the decision to deploy wireless technology.

Open letter to the Vatican.

Science.gov (United States)

1999-01-01

An open letter was published by Latin American and Caribbean women during the Special Session of the UN General Assembly on the International Conference on Population and Development. The letter generally focused on the Church¿s stand on women's reproductive rights. In particular, it questioned the Church on the following aspects of reproductive health, which include: 1) maternal death related to lack of access to reproductive health care; 2) Vatican representatives insisting that only parents can supervise their children education and health, which also lead to many cases of sexual abuse and incest; 3) women's sexual inequality and daily violence; 4) the Vatican delegation blocking the advances of contraception, sexual education, and HIV prevention; 5) problems of migrants and allocation of resources; and 6) the Church failing to recognize the capacity of young people to make decisions based on their own conscience.

Electric Vehicle and Wireless Charging Laboratory

Science.gov (United States)

2018-03-23

Wireless charging tests of electric vehicles (EV) have been conducted at the EVTC Wireless Laboratory located at the Florida Solar Energy Center, Cocoa, FL. These tests were performed to document testing protocols, evaluate standards and evaluate ope...

Scientific Letter: High-intent suicide and the Beck's Suicide Intent ...

African Journals Online (AJOL)

Scientific Letter: High-intent suicide and the Beck's Suicide Intent scale: a case report. ... African Journal of Psychiatry. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current ... Abstract. Scientific Letter - No Abstract Available ...

Wireless sensor platform

Science.gov (United States)

Joshi, Pooran C.; Killough, Stephen M.; Kuruganti, Phani Teja

2017-08-08

A wireless sensor platform and methods of manufacture are provided. The platform involves providing a plurality of wireless sensors, where each of the sensors is fabricated on flexible substrates using printing techniques and low temperature curing. Each of the sensors can include planar sensor elements and planar antennas defined using the printing and curing. Further, each of the sensors can include a communications system configured to encode the data from the sensors into a spread spectrum code sequence that is transmitted to a central computer(s) for use in monitoring an area associated with the sensors.

Application opportunities in wireless communications. Final report

International Nuclear Information System (INIS)

Abbott, R.E.; Blevins, R.P.; Olmstead, C.

1998-07-01

This report presents the results of examinations of wireless technologies and applications that may offer potential to utilities. Five different wireless technology areas are reviewed. Three areas--Communication Networks, Monitored Security Services, and Home Automation--potentially represent new business ventures for utilities. Two areas--Automatic Vehicle Location and Automated Field-Force Management--represent wireless applications with potential for reduced operating costs and improved customer relations

Challenging Aspects of Terahertz Terabit Wireless Communications

DEFF Research Database (Denmark)

Yu, Xianbin; Galili, Michael; Jepsen, Peter Uhd

The increasing demand on fast wireless communications, e.g. huge data file transferring and mobile broadband access, has driven wireless communication systems into a path towards Terabit era. Terahertz (THz) technology is promising due to its unique features, such as unlimited bandwidth available......, in terms of THz generation and link power budget. The THz atmospheric absorption is another critical issue to limit wireless communication range....

[Changes in CIRUGIA ESPANOLA Letters to the Editor between 2000 and 2007].

Science.gov (United States)

Rosell-Pradas, Jorge; Sánchez-Cantalejo, Emilio

2008-09-01

To describe the frequency and bibliographic characteristics of letters to the editor in the journal, Cirugía Española published between 2000 and 2007 and to compare the differences in the periods between 2000-2003 and 2004-2007. A descriptive and cross-sectional study, using the letters to the editor published in Spanish surgery between 2000 and 2007, as observation units. The variables considered were: the number of letters according to the volume and year of publication, substantive content of the paper, text length, graphics resources use, number of signatories and their professional profile, institutions of the authors, by origin and number of Autonomous Communities and number of bibliographical references. To meet the second objective, we compared letters from the period 2000-2003 with the period 2004-2007 against the rest of variables considered as a result. We used descriptive statistics and statistical analysis for comparison of distributions (chi2), with a level of significance of p < 0.05, using the SPSS software (Version 15.0). We identified 312 documents classified as letters. Between 2002 and 2005 their number was small. Often referring to clinical cases 187 (59.9%) and related letters, 98 (31.4%). Of those, 81.1% met the standard length of the text and only 6 letters (1.9%) was the use of graphics exceeded. In 122 letters (39.1%) the permitted number of authors was exceeded. They were mostly contributed by surgeons, 238 cases (76.3%), usually a single hospital, with 294 letters (94.2%) mainly from, Catalonia, Andalusia, Madrid and Valencia. Only 58.1% of the letters complied with the permitted number of references. More related letters were published in the last period (59 letters; 42.1%) than during the years 2000-2003 (39 letters; 22.7%) (chi2 = 14.79; p < 0.001). The correct length of the text improved in the second period, 136 (97.1%), compared to the first 117 (68%) (chi2 = 42.67; p < 0.001. The graphics resources were used properly in both

Towards Controlling Latency in Wireless Networks

KAUST Repository

Bouacida, Nader

2017-01-01

Wireless networks are undergoing an unprecedented revolution in the last decade. With the explosion of delay-sensitive applications in the Internet (i.e., online gaming and VoIP), latency becomes a major issue for the development of wireless

Information Assurance in Wireless Networks

Science.gov (United States)

Kabara, Joseph; Krishnamurthy, Prashant; Tipper, David

2001-09-01

Emerging wireless networks will contain a hybrid infrastructure based on fixed, mobile and ad hoc topologies and technologies. In such a dynamic architecture, we define information assurance as the provisions for both information security and information availability. The implications of this definition are that the wireless network architecture must (a) provide sufficient security measures, (b) be survivable under node or link attack or failure and (c) be designed such that sufficient capacity remains for all critical services (and preferably most other services) in the event of attack or component failure. We have begun a research project to investigate the provision of information assurance for wireless networks viz. survivability, security and availability and here discuss the issues and challenges therein.

32 CFR 884.17 - Commander's instruction letter to member.

Science.gov (United States)

2010-07-01

... instruction letter to member. Subject: Instructions in Case of Release on Bail or Personal Recognizance 1. You... 32 National Defense 6 2010-07-01 2010-07-01 false Commander's instruction letter to member. 884.17... civilian custody on bail or on your own recognizance, report immediately in person or by telephone to the...

Implanted Antennas in Medical Wireless Communications

CERN Document Server

Rahmat-Samii, Yahya; Balanis, Constantine

2006-01-01

Implanted Antennas in Medical Wireless Communications summarizes the results of recent research activities on the subject of implanted antennas for medical wireless communication systems. It is anticipated that in the near future sophisticated medical devices will be implanted inside the human body for medical telemetry and telemedicine. To establish effective and efficient wireless links with these devices, it is pivotal to give special attention to antenna designs that are low profile, small, safe, and cost effective. In this book, authors Yahya Rahmat-Samii and Jaehoon Kim demonstrate how a

Bluetooth-based wireless sensor networks

Science.gov (United States)

You, Ke; Liu, Rui Qiang

2007-11-01

In this work a Bluetooth-based wireless sensor network is proposed. In this bluetooth-based wireless sensor networks, information-driven star topology and energy-saved mode are used, through which a blue master node can control more than seven slave node, the energy of each sensor node is reduced and secure management of each sensor node is improved.

An Analysis Of Wireless Security

OpenAIRE

Salendra Prasad

2017-01-01

The WLAN security includes Wired Equivalent Primary WEP and WI-FI protected Access WPA. Today WEP is regarded as very poor security standard. WEP was regarded as very old security standard and has many security issues which users need to be addressed. In this Paper we will discuss Wireless Security and ways to improve on wireless security.

Lost and Found, Letters and Methods: Assessing Attitudes toward Chiropractic and Medical Care

Directory of Open Access Journals (Sweden)

Hannah Kern

2010-10-01

Full Text Available Attitudes toward traditional and chiropractic medicine were compared using Milgram's lost letter technique. A total of 192 letters were placed on the windshields of vehicles in parking lots at six restaurants and department stores in each of four quadrants of a medium-sized, Southeastern city. These letters were addressed to "Admissions" at either a fictitious Institute of Medicine or Institute of Chiropractic Care. Return addresses included either a male or a female name. Thus, those who found a lost letter were faced with the option of returning or not returning a letter from either a male or a female, addressed to an Institute of traditional or non-traditional medicine. After examining previous studies which had used the lost letter technique, numerous methodological improvements were implemented. For example, letters were randomly assigned to potential drop spots for each of 24 study locations (six study locations in each of four city quadrants, and a Latin square design was used to control for possible order effects in the four study conditions that were implemented. Nearly 65% of the letters (124 of 192 were returned. We found: 1 letters addressed to a fictitious Institute of Chiropractic Care were just as likely to be returned as those addressed to a fictitious Institute of Medicine; 2 letters with female return addresses were as likely to be returned as those with male return addresses; 3 there was no interaction between study conditions; 4 based on what was essentially a replication study, a comparison of the pattern of returns using the first and second cycle of lost letters (n = 96 for each cycle revealed an equivalent pattern of no-difference findings. DOI: 10.2458/azu_jmmss.v1i1.78

Contemporary trends in the research of the Letter to Philemon

Directory of Open Access Journals (Sweden)

Bartosz Adamczewski

2005-03-01

Full Text Available In the period of last two or three decades interpretation of the Letter to Philemon has undergone significant changes. Exegetes applying the historical-critical method proposed recently several new ways of reconstructing the situation that occasioned Paul’s writing the letter. It has been suggested e.g. that Onesimus was no runaway, but probably an envoy from Colossae, or Philemon’s estranged brother, or a slave justifiably seeking intercession, or a roamer. Synchronic methods applied by many exegetes (structural, rhetorical, narrative and pragmatic criticism elucidate various kinds of influence of the letter upon the reader. More and more popular becomes also nowadays manifold liberationist approach. However, beyond applying these various hermeneutic procedures there is also, at least for believing exegetes, an important task of adequate explaining the significance of the Letter to Philemon as an inspired writing.

Compact wideband CMOS receiver frontends for wireless communication

NARCIS (Netherlands)

Blaakmeer, S.C.

2010-01-01

Abstract Wireless communication is an integral part of our daily life, the mobile phone is an example of a very popular wireless communication device. A communication link consists of a transmitter, a receiver and the transmission medium, which air or vacuum for a wireless link. Part of the receiver

A classification of marked hijaiyah letters' pronunciation using hidden Markov model

Science.gov (United States)

Wisesty, Untari N.; Mubarok, M. Syahrul; Adiwijaya

2017-08-01

Hijaiyah letters are the letters that arrange the words in Al Qur'an consisting of 28 letters. They symbolize the consonant sounds. On the other hand, the vowel sounds are symbolized by harokat/marks. Speech recognition system is a system used to process the sound signal to be data so that it can be recognized by computer. To build the system, some stages are needed i.e characteristics/feature extraction and classification. In this research, LPC and MFCC extraction method, K-Means Quantization vector and Hidden Markov Model classification are used. The data used are the 28 letters and 6 harakat with the total class of 168. After several are testing done, it can be concluded that the system can recognize the pronunciation pattern of marked hijaiyah letter very well in the training data with its highest accuracy of 96.1% using the feature of LPC extraction and 94% using the MFCC. Meanwhile, when testing system is used, the accuracy decreases up to 41%.

The A.I.D.A. Plan and the Writing of Sales Letters.

Science.gov (United States)

Jong, Rowena

A study based on textual analysis of sales letters is reported that evaluates the Attention, Interest, Desire, and Action (AIDA) approach to teaching the writing of sales letters. Thirty business letters written by undergraduate business students and executives were analyzed. The forms of cohesion, voice pattern, and information focus of the…

Self-Similar Traffic In Wireless Networks

OpenAIRE

Jerjomins, R.; Petersons, E.

2005-01-01

Many studies have shown that traffic in Ethernet and other wired networks is self-similar. This paper reveals that wireless network traffic is also self-similar and long-range dependant by analyzing big amount of data captured from the wireless router.

2nd International Conference on Mobile and Wireless Technology

CERN Document Server

Wattanapongsakorn, Naruemon

2015-01-01

This book provides a snapshot of the current state-of-the-art in the fields of mobile and wireless technology, security and applications.  The proceedings of the 2nd International Conference on Mobile and Wireless Technology (ICMWT2015), it represents the outcome of a unique platform for researchers and practitioners from academia and industry to share cutting-edge developments in the field of mobile and wireless science technology, including those working on data management and mobile security.   The contributions presented here describe the latest academic and industrial research from the international mobile and wireless community.  The scope covers four major topical areas: mobile and wireless networks and applications; security in mobile and wireless technology; mobile data management and applications; and mobile software.  The book will be a valuable reference for current researchers in academia and industry, and a useful resource for graduate-level students working on mobile and wireless technology...

Tradeoff Analysis for Combat Service Support Wireless Communications Alternatives

Energy Technology Data Exchange (ETDEWEB)

Burnette, John R.; Thibodeau, Christopher C.; Greitzer, Frank L.

2002-02-28

As the Army moves toward more mobile and agile forces and continued sustainment of numerous high-cost legacy logistics management systems, the requirement for wireless connectivity and a wireless network to supporting organizations has become ever more critical. There are currently several Army communications initiatives underway to resolve this wireless connectivity issue. However, to fully appreciate and understand the value of these initiatives, a Tradeoff Analysis is needed. The present study seeks to identify and assess solutions. The analysis identified issues that impede Interim Brigade Combat Team (IBCT) communication system integration and outlined core requirements for sharing of logistics data between the field and Army battle command systems. Then, the analysis examined wireless communication alternatives as possible solutions for IBCT logistics communications problems. The current baseline system was compared with possible alternatives involving tactical radio systems, wireless/near term digital radio, cellular satellite, and third-generation (3G) wireless technologies. Cellular satellite and 3G wireless technologies offer clear advantages and should be considered for later IBCTs.