Wired Networks Research Articles

Magnetic response of aperiodic wire networks based on Fibonacci distortions of square antidot lattices

The static and dynamic magnetic responses of patterned ferromagnetic thin films are uniquely altered in the case of aperiodic patterns that retain long-range order (e.g., quasicrystals). We have fabricated permalloy wire networks based on periodic square antidot lattices (ADLs) distorted according to an aperiodic Fibonacci sequence applied to two lattice translations, d1 = 1618 nm and d2 = 1000 nm. The wire segment thickness is fixed at t = 25 nm, and the width W varies from 80 to 510 nm. We measured the DC magnetization between room temperature and 5 K. Room-temperature, narrow-band (9.7 GHz) ferromagnetic resonance (FMR) spectra were acquired for various directions of applied magnetic field. The DC magnetization curves exhibited pronounced step anomalies and plateaus that signal flux closure states. Although the Fibonacci distortion breaks the fourfold symmetry of a finite periodic square ADL, the FMR data exhibit fourfold rotational symmetry with respect to the applied DC magnetic field direction.

Deploying Wireless Sensor Networks with Fault-Tolerance for Structural Health Monitoring

Structural health monitoring (SHM) systems are implemented for structures (e.g., bridges, buildings) to monitor their operations and health status. Wireless sensor networks (WSNs) are becoming an enabling technology for SHM applications that are more prevalent and more easily deployable than traditional wired networks. However, SHM brings new challenges to WSNs: engineering-driven optimal deployment, a large volume of data, sophisticated computing, and so forth. In this paper, we address two important challenges: sensor deployment and decentralized computing. We propose a solution, to deploy wireless sensors at strategic locations to achieve the best estimates of structural health (e.g., damage) by following the widely used wired sensor system deployment approach from civil/structural engineering. We found that faults (caused by communication errors, unstable connectivity, sensor faults, etc.) in such a deployed WSN greatly affect the performance of SHM. To make the WSN resilient to the faults, we present an approach, called ${\tt FTSHM}$ (fault-tolerance in SHM), to repair the WSN and guarantee a specified degree of fault tolerance. ${\tt FTSHM}$ searches the repairing points in clusters in a distributed manner, and places a set of backup sensors at those points in such a way that still satisfies the engineering requirements. ${\tt FTSHM}$ also includes an SHM algorithm suitable for decentralized computing in the energy-constrained WSN, with the objective of guaranteeing that the WSN for SHM remains connected in the event of a fault, thus prolonging the WSN lifetime under connectivity and data delivery constraints. We demonstrate the advantages of ${\tt FTSHM}$ through extensive simulations and real experimental settings on a physical structure.

세방향 서명 수열 패킷 방식 기반 선내 전파 전달특성 측정시스템 설계 및 분석

Recently, the new issues for the safety and the information delivery system in the ship are raised. The deployment and the efficient algorithms of deploying the wireless sensor networks instead of using the built-in wired networks or the setup of the new wired networks is more desirable than the deployment of the wired networks in a ship after its final production since it can reduce the cost and the time of the brand new wired networks by reshaping some of the internal structure of the ship. In this paper, the shipboard signal propagation measurement system based on the signature sequence-three way slave mode are designed and its measureed data are analysed after measuring the signal propagation characteristics. Consequently, it is expected that the reliable and cost-effective signal measurement system with the three way algorithm for the deployment of the shipboard wireless networks can be achieved. 논문 15-40-01-25 The Journal of Korean Institute of Communications and Information Sciences '15-01 Vol.40 No.01 http://dx.doi.org/10.7840/kics.2015.40.1.193 193 First Author : First Author : Wireless Multimedia Communications Lab. Dept of Electronics Engineering, Ewha W. University, jho@ewha.ac.kr, 종신회원 논문번호:KICS2014-09-364, Received September 26, 2014; Revised November 16, 2014; Accepted January 12, 2015 The Journal of Korean Institute of Communications and Information Sciences '15-01 Vol.40 No.01

Effect of Substrate Temperature on the Properties of Sprayed WO3 Thin Films Using Peroxotungstic Acid and Ammonium Tungstate: A Comparative Study

A comparative study on the physicochemical properties of tungsten oxide (WO3) thin films synthesized using peroxotungstic acid (PTA) and ammonium tungstate (AT) by simple spray pyrolysis technique is reported. X-ray diffraction patterns show that the films deposited using both the precursors are polycrystalline with monoclinic crystal structure. The x-ray photoelectron spectroscopy studies confirm that the films are sub-stoichiometric with O/W ratios of 2.93 and 2.87, respectively, for typical PTA and AT films. Tungsten (W) exists in two chemical states, 5+ and 6+. Scanning electron microscopy images show the uniform and dense network of wires in PTA films, while the films deposited using AT possess a porous structure with small grains. Electrical and dielectric studies show that films are highly resistive and possess high dielectric constant. The near ultra-violet, blue, green and weak red emissions due to defects were observed in the photoluminescence studies. Properties of the WO3 thin films reported here are suitable for gas sensor applications. Films deposited using PTA are more functional than those deposited using AT.

Hands-on Analysis of 802.11ac Modulation and Coding Scheme

Current communication networks are full of mobile devices that are capable of performing data transfers at high data rates or access high resolution video streams. For such requirements, in the data communications there is a permanent concern of wireless communications development to keep up with the wired communication networks. Because the 802.11n technology is not fast enough for increasingly more users willing games and online broadcasts, the 802.11ac technology was developed. This new IEEE standard, along with the future technology 802.11ad, is aiming to achieve a new level of performance, called VHT (Very High Throughput). The goal is to reach transfer rates (over 1Gbps for now) comparable to those establish in wired networks. This article is proposing a study over 802.11ac technology by exploring the performances of the specific MCS (Modulation and Coding Scheme) with a handy digitally modulated signals investigation method, CCDF (Complementary Cumulative Distribution Function).

Applications of ZigBee Technology in the Safety Monitoring System of Low Gas Pipeline Transportation

The existing safety monitoring system of low gas pipeline transportation establishes a wired communication network monitoring system mainly on the basis of industrial bus. It has problems such as large transmission signal attenuation, complex wiring, high-labor intensity, inconvenient installation and maintenance, high maintenance cost, and so on. Featuring low cost, power-saving, reliability, stability and flexibility, the wireless sensor network established by ZigBee wireless communication technology can realize the real-time all-dimensional dynamic monitoring on parameters of low gas pipeline transportation system and overcome the shortcomings and deficiencies of wired network system.

Exploring Routing Security in Ad Hoc Networks

Ad Hoc networks are the ones don’t use any network axillary element for routing, but participated nodes in these networks have task of network routing. Security in Ad hoc networks has a particular condition, because besides problems such as existed problems in wire networks, we face with problems such as simple hearing and information changing in transferring, possibility of people impersonation or damage routing operations, non-possibility of using coded key distribution infrastructures and so on. One of the most important security cases in ad hoc networks is providing a secured routing algorithm in these networks. It has been tried in recent years to provide a secured routing algorithm in ad hoc networks, amongst, there are protocols such as ARAN, SAODA, SRP, Ariadne, SEAD, etc. but each one has its particular problems. Moreover, lack of an acceptable algorithm both according to security and network efficiency is felt.

Cyberspace Forensics Readiness and Security Awareness Model

The goal of reaching a high level of security in wire- less and wired communication networks is continuously proving difficult to achieve. The speed at which both keepers and violators of secure networks are evolving is relatively close. Nowadays, network infrastructures contain a large number of event logs captured by Firewalls and Domain Controllers (DCs). However, these logs are increasingly becoming an obstacle for network administrators in analyzing networks for malicious activities. Forensic investigators mission to detect malicious activities and reconstruct incident scenarios is extremely complex considering the number, as well as the quality of these event logs. This paper presents the building blocks for a model for automated network readiness and awareness. The idea for this model is to utilize the current network security outputs to construct forensically comprehensive evidence. The proposed model covers the three vital phases of the cybercrime management chain, which are: 1) Forensics Readiness, 2) Active Forensics, and 3) Forensics Awareness.

Sink based Cross Layer Routing for Image Delivery in Wireless Sensor Networks

With the advent of wireless technology, various applications in traditional wired networks have been adopted in wireless networks. To transmit multimedia in wireless networks, it is required to balance the power control and lifetime with the quality constraints. In this paper, we develop cross-layer mechanism based on power and modulation rate control for a multi-path routing protocol subject to total end-to-end quality level specified in terms of packet error rate and time constraint. The proposed sink-based maximal minimal residual energy (MMRE) AOMDV algorithm uses the information such as image size, node gain, noise, time constraint and residual energy of the nodes available in the route request packets to calculate the optimal power and rate vectors and the number of packets that can be sent by the source on each disjoint path to the sink. The source is freed from the complex algorithmic executions and hence the energy is conserved.

A high transmission wave-guide wire network made by self-assembly.

Polymer self-assembly of a 3D continuous gyroid morphology was replicated into a network consisting of hollow gold struts. This was achieved by first replicating a gyroid structured film into nickel. The Ni network was employed as an electrode for electrochemical Au deposition, followed by the removal of Ni. The resulting hollow network of plasmonic gold exhibited a substantial optical transmission enhancement by a factor of nearly 3, compared to a network of full Au struts. The overall transmission across the hollow wave-guide morphology depends sensitively on the wall-thickness of the hollow struts down to 1 nm. The dramatic transmission increase arises from an interplay of three mechanisms: (1) the additional number of modes propagating through the wave-guide structure, (2) the increased efficiency of light in-coupling, and (3) a reduction of dissipation by decreasing the Au-volume experienced in plasmon mode propagation.

Reaction pathway and wiring network dependent Li/Na storage of micro-sized conversion anode with mesoporosity and metallic conductivity

Highly mesoporous and conductive micro-sized nitride is used as potential conversion LIB and NIB anodes. Superior rate and cycling performances (e.g. 600 mA h g−1 and 100 mA h g−1 at 2 C for Li- and Na-storage, respectively) benefit from self-reconstruction and preservation of conductive networks.

Comparative Study of Proactive, Reactive and Geographical MANET Routing Protocols

Mobile Adhoc Network (MANET) is defined as a combination of mobile nodes that lack a fixed infrastructure and is quickly deployable under any circumstances. These nodes have self-aware architecture and are able to move in multiple directions, which renders it dynamic topology. Its dynamicity makes routing in MANET rather challenging compared to fixed wired networks. This paper aims to perform a comparative study on the three categories of MANET routing protocol by comparing their characteristics and operations, as well as their strength and weaknesses.

105 金網細工の亀甲形状に対する構造解析(GS1,13,20 構造解析,研究討論セッション)

105 金網細工の亀甲形状に対する構造解析(GS1,13,20 構造解析,研究討論セッション)

Evaluation of Japanese Metal Wire Network “Kana-ami” Based on Three-dimensional Analysis

‘Kana-ami’ is a kind of metal wire network in Japan. This study aimed to focus on ‘Kana-ami’ technique development in order to keep this culture wealth and skill to the next generation. In this study, the two participants were selected for comparison called as expert and non-expert. The products made by participants were measured by industry computed tomography system precisely. The deformation of two metal wires’ diameter was calculated, and the expert's rotation angle was shown smaller damage on the surface of metal wires.

Diagnosis of Multiple Wiring Faults Using Time-Domain Reflectometry and Teaching–Learning-Based Optimization

Time-domain reflectometry has proven to be one of the best methods for wiring network diagnosis, and it can easily be applied to the detection and localization of defects, while only requiring one access point to the wiring network. In this article, a novel approach combining the time-domain reflectometry response extracted from vector network analyzer measurements and the teaching–learning-based optimization technique is developed and applied to the diagnosis of wiring networks. The proposed approach consists of two steps. In the first step, propagation along the cables is modeled using the forward model. In the second step, teaching–learning-based optimization is used to solve the inverse problem to deduce physical information about the defects in the wiring network. The proposed approach has been successfully tested on several cases and for different configurations. Comparisons of the proposed time-domain reflectometry/teaching–learning-based optimization approach results with measurements reveal that this approach has a high potential and is very effective for wiring network diagnosis.

Polar-Based OFDM and SC-FDE Links Toward Energy-Efficient Gbps Transmission Under IM-DD Optical System Constraints [Invited

Recent studies have investigated the use of orthogonal frequency division multiplexing (OFDM) and single carrier frequency-domain equalization (SC-FDE) for gigabyte per second (Gpbs) short-range optical wired and wireless access networks based on direct intensitymodulation with direct detection (IM-DD). OFDM systems have an inherent high peak-to-average power ratio (PAPR). SC-FDE systems have lower PAPR and thus outperform comparable OFDM systems in terms of bit-error performance under various practical considerations, mainly the limited dynamic range of operation at the transmitter. In RF-based OFDM and SC-FDE systems, the output signal is bipolar, complex, and cannot be transmitted in IM-DD systems. Therefore, several power efficient schemes, however spectrally inefficient, have been proposed to make positive OFDM and SC-FDE signals, e.g., asymmetrically clipped optical OFDM (ACO-OFDM) and repetition and clipping optical SCFDE (RCO-SCFDE). To increase the data rate, novel OFDM and SC-FDE signal formats, called polar OFDM (P-OFDM) and polar SC-FDE (P-SC-FDE), based on a polar representation of complex symbols, are proposed. The proposed format offers twice as much spectral efficiency as state-of-the art unipolar OFDM and SC-FDE formats. Moreover, using a power allocation approach on the time-domain positive samples, the PAPR is further reduced, and the numerical evaluation of the bit-error performance under optical source power and dynamic range constraints demonstrates superior results toward Gpbs transmission.

Wired and wireless convergent extended-reach optical access network using direct-detection of all-optical OFDM super-channel signal

We propose and demonstrate the feasibility of using all-optical orthogonal frequency division multiplexing (AO-OFDM) for the convergent optical wired and wireless access networks. AO-OFDM relies on all-optically generated orthogonal subcarriers; hence, high data rate (> 100 Gb/s) can be easily achieved without hitting the speed limit of electronic digital-to-analog and analog-to-digital converters (DAC/ADC). A proof-of-concept convergent access network using AO-OFDM super-channel (SC) is demonstrated supporting 40 - 100 Gb/s wired and gigabit/s 100 GHz millimeter-wave (MMW) ROF transmissions.

Image compression algorithms in wireless multimedia sensor networks: A survey

Abstract Unlike classical wired networks and wireless sensor networks, WMSN differs from their predecessor’s scalar network basically in the following points; nature and size of data being transmitted, important memory resources, as well as, power consumed per each node for processing and transmission. The most effective solution to overcome those problems is image compression. As the image contains massive amount of redundancies resulting from high correlation between pixels, many compression algorithms have been developed. The main objective of this survey was to study and analyze relevant research directions and the most recent algorithms of image compression over WMSN. This survey characterizes the benefits and shortcomings of recent efforts of such algorithms. Moreover, it provides an open research issue for each compression method; and its potentials to WMSN. Reducing consumed power thus granting long life time is considered the main performance metric and will be the main target in the investigated solution.

선박 내 유선망에서 차등화 서비스 지원을 위한 패킷 폐기 기술

선내 유선 네트워크에서는 선내의 각종 센서와 제어기를 자율적으로 구성관리하고 원격제어를 제공하는 기능을 수행한다. 이러한 선박 내 유선 통신망에서 차등화서비스가 지원된다면, 우선순위가 높은 실시간 플로우는 최소전송률을 보장 받고 빠르게 전송되어, 지능적인 선박 통신망을 구현할 수 있다. 본 논문에서는 이러한 선박 내 유선 네트워크에서 차등화 서비스를 지원하기 위해, 기존 RIO (RED In and Out) 방식보다 우수한 패킷 폐기 기술을 제안한다. 제안한 패킷 폐기기술은 개별 플로우별로 관리하지 않고 특정한 기준에 따라 몇 개의 플로우 그룹으로 나누어, 그룹별 관리를 통해서 동일 클래스 내 플로우 간 공평성을 제공한다. 시뮬레이션 결과에서는 RIO 방식보다 링크 이용률은 조금 감소하나, 다중 병목 구간을 경유하는 플로우들이 RIO 방식보다 더 많은 전송률을 보장 받음을 알 수 있다. An wired ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, the DiffServ (Differentiated Services) realizes that the high-speed real-time flow with the higher priority has the guaranteed minimum data rate and is delivered faster. As a result of this DiffServ effect, the intelligent Ship Area Networks can be implemented. In this paper, an packet drop technique is proposed to outperform the previous RIO (RED In and Out) drop mechanism for DiffServ in ship area networks. the proposed packet drop technique does not manage the individual flows and divides them into several flow groups according to a criterion. And it guarantees the fairness between individual flows in the same QoS class through the group-based control. In simulation results of the proposed packet drop technique, the link utilization decreases than RIO. But it guarantees more data rates to DiffServ flows passing multiple bottleneck links.

A self-adaptive trust management scheme for wireless sensor networks

Trust management is fundamental to identify malicious, selfish, and compromised nodes which have been authenticated. Many trust management mechanisms are proposed to provide effective security solution for wire and wireless networks, even some of them have become one of the most known in this field. But in fact, trust management in wireless sensor networks still remains a challenging field. Traditional trust models developed for wireless sensor networks are not well suited for sensor networks because the trust evaluation process isn’t related to certain application. In this paper, we propose a self-adaptive trust management scheme, which can adaptively adjust the trust evaluation process to cope with application requirement changes of trust management. The simulation results show that our scheme has less rate of inauthentic downloads of nodes, energy consumption and message overheads as compared to the current state-of-the-art trust management schemes, and it is more suitable for large-scale sensor networks.