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  • Articles  (6,856)
  • Hindawi  (6,856)
  • 2010-2014  (6,420)
  • 1980-1984  (274)
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  • 1950-1954
  • Electrical Engineering, Measurement and Control Technology  (6,489)
  • Process Engineering, Biotechnology, Nutrition Technology  (367)
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  • Articles  (6,856)
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  • 1
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    Fuel Cell Electrodes Based on Carbon Nanotube/Metallic Nanoparticles Hybrids Formed on Porous Stainless Steel Pellets (2013)
    Hindawi
    Details
    Publication Date: 2013-09-06
    Description: The preparation of carbon nanotube/metallic particle hybrids using pressed porous stainless steel pellets as a substrate is described. The catalytic growth of carbon nanotubes was carried out by CVD on a nickel catalyst obtained by impregnation of pellets with a highly dispersive colloidal solution of nickel acetate tetrahydrate in ethanol. Granular polyethylene was used as the carbon source. Metallic particles were deposited by thermal evaporation of Pt and Ag using pellets with grown carbon nanotubes as a base. The use of such composites as fuel cell electrodes is discussed.
    Print ISSN: 1687-806X
    Electronic ISSN: 1687-8078
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 2
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    Distributed Fault-Tolerant Event Region Detection of Wireless Sensor Networks (2013)
    Hindawi
    Details
    Publication Date: 2013-09-10
    Description: This work provides a distributed fault-tolerant event region detection algorithm for wireless sensor networks. The proposed algorithm can identify faulty and fault-free sensors and ignore the abnormal readings to avoid false alarm. Moreover, every event region can also be detected and identified. Simulation results show that fault detection accuracy (FDA) is greater than 92%, false alarm rate (FAR) is near 0%, and event detection accuracy (EDA) is greater than 99% under uniform distribution. FDA is greater than 92%, FAR is less than 1.2%, and EDA is greater than 88% under random distribution when sensor fault probability is less than 0.3.
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 3
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    Numerical Analysis of Copper-Indium-Gallium-Diselenide-Based Solar Cells by SCAPS-1D (2013)
    Hindawi
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    Publication Date: 2013-09-11
    Description: We used a one-dimensional simulation program Solar Cell Capacitance Simulator in 1 Dimension (SCAPS-1D) to investigate Copper-Indium-Gallium-Diselenide- (CIGS-) based solar cells properties. Starting with a conventional ZnO-B/i-ZnO/CdS/CIGS structure, we simulated the parameters of current-voltage characteristics and showed how the absorber layer thickness, hole density, and band gap influence the short-circuit current density (), open-circuit voltage (), fill factor (FF), and efficiency of solar cell. Our simulation results showed that all electrical parameters are greatly affected by the absorber thickness (w) below 1000 nm, due to the increase of back-contact recombination and very poor absorption. Increasing hole density (p) or absorber band gap () improves and leads to high efficiency, which equals value of 16.1% when p = 1016 cm−3 and  eV. In order to reduce back-contact recombination, the effect of a very thin layer with high band gap inserted near the back contact and acting as electrons reflector, the so-called back-electron reflector (EBR), has been investigated. The performances of the solar cells are significantly improved, when ultrathin absorbers (w 〈 500 nm) are used; the corresponding gain of due to the EBR is 3 mA/cm2. Our results are in good agreement with those reported in the literature from experiments.
    Print ISSN: 1110-662X
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    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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  • 4
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    Solar Power Generation (2013)
    Hindawi
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    Publication Date: 2013-09-11
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    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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  • 5
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    Research of Hydrogen Preparation with Catalytic Steam-Carbon Reaction Driven by Photo-Thermochemistry Process (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: An experiment of hydrogen preparation from steam-carbon reaction catalyzed by K2CO3 was carried out at 700°C, which was driven by the solar reaction system simulated with Xenon lamp. It can be found that the rate of reaction with catalyst is 10 times more than that without catalyst. However, for the catalytic reaction, there is no obvious change for the rate of hydrogen generation with catalyst content range from 10% to 20%. Besides, the conversion efficiency of solar energy to chemical energy is more than 13.1% over that by photovoltaic-electrolysis route. An analysis to the mechanism of catalytic steam-carbon reaction with K2CO3 is given, and an explanation to the nonbalanced [H2]/[CO + 2CO2] is presented, which is a phenomenon usually observed in experiment.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 6
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    Determination of Total Germanium in Chinese Herbal Remedies by Square-Wave Catalytic Adsorptive Cathodic Stripping Voltammetry at an Improved Bismuth Film Electrode (2013)
    Hindawi
    Details
    Publication Date: 2013-09-12
    Description: A catalytic adsorptive cathodic stripping voltammetric method on an improved bismuth film electrode (BiFE) for the determination of trace germanium in the presence of pyrogallol has been investigated. A well-defined and sensitive stripping peak of Ge(IV)-pyrogallol complex was observed at −0.79 V (versus SCE) in a 0.1 M acetate buffer solution (pH 4.8) at a deposition potential of −0.34 V. The reduction current is catalytically enhanced by adding KBrO3. The experimental variables and potential interference were studied. Compared with the BiFE plated in the solution prepared based on HAc-NaAc without trisodium citrate, the improved BiFE electrodeposited in the solution of HAc-NaAc containing trisodium citrate displayed a better electroanalytical performance for the determination of germanium(IV). Under the optimized conditions, the detection limit of Ge(IV) was 60 ng L−1, and the relative standard deviation (RSD) was 3.73% at 5 μg L−1 level (). This method was successfully applied to determine the total germanium in several Chinese herbal remedies.
    Print ISSN: 2090-3529
    Electronic ISSN: 2090-3537
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
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  • 7
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    Effect of UV Irradiation on Interactions of -Lipoic Acid with Free Radicals (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: Changes of antioxidant properties of -lipoic acid (LA) after UV irradiation were studied. LA is the typical drug used in diabetic neuropathy. Quenching of free radicals is an important factor of therapy by using this substance. -Lipoic acid is exposed to UV irradiation during the storage. The aim of our studies was to examine the effect of UV irradiation on the interactions of LA with free radicals. The -lipoic acid was irradiated by UVA 315–400 nm light during 10 to 110 minutes by intervals of 10 minutes. The electron paramagnetic resonance spectroscopy was used as the experimental technique. The antioxidant properties of LA were spectroscopically confirmed. The strong effect of UV irradiation on interactions of -lipoic acid with free radicals was observed. It was pointed out that interactions of LA with free radicals decrease after its exposition on UV. The interactions of LA with free radicals were higher after the sample irradiation during 10 minutes than for the samples irradiated longer (20–110 minutes). The results are important for problems connected with photomedicine; they pointed out that -lipoic acid should not be stored on UV exposition. Application of electron paramagnetic resonance spectroscopy to characterize interactions of pharmacological substance with free radicals was confirmed.
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    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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  • 8
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    Enhanced Photoelectrochemical Response from Copper Antimony Zinc Sulfide Thin Films on Transparent Conducting Electrode (2013)
    Hindawi
    Details
    Publication Date: 2013-09-12
    Description: Copper antimony sulfide (CAS) is a relatively new class of sustainable absorber material, utilizing cost effective and abundant elements. Band gap engineered, modified CAS thin films were synthesized using electrodeposition and elevated temperature sulfurization approach. A testing analog of copper zinc antimony sulfide (CZAS) film-electrolyte interface was created in order to evaluate photoelectrochemical performance of the thin film of absorber materials. Eu3+/Eu2+ redox couple was selected for this purpose, based on its relative band offset with copper antimony sulfide. It was observed that zinc has a significant effect on CAS film properties. An enhanced photocurrent was observed for CAS film, modified with zinc addition. A detailed investigation has been carried out by changing stoichiometry, and corresponding surface and optical characterization results have been evaluated. A summary of favorable processing parameters of the films showing enhanced photoelectrochemical response is presented.
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  • 9
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    - Calculations in CdS/CdTe Thin Films Solar Cells with a Interlayer (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: In CdS/CdTe solar cells, chemical interdiffusion at the interface gives rise to the formation of an interlayer of the ternary compound . In this work, we evaluate the effects of this interlayer in CdS/CdTe photovoltaic cells in order to improve theoretical results describing experimental - (capacitance versus voltage) characteristics. We extended our previous theoretical methodology developed on the basis of three cardinal equations (Castillo-Alvarado et al., 2010). The present results provide a better fit to experimental data obtained from CdS/CdTe solar cells grown in our laboratory by the chemical bath deposition (for CdS film) and the close-spaced vapor transport (for CdTe film) techniques.
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  • 10
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    A Quantitative Analysis of Photovoltaic Modules Using Halved Cells (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: In a silicon wafer-based photovoltaic (PV) module, significant power is lost due to current transport through the ribbons interconnecting neighbour cells. Using halved cells in PV modules is an effective method to reduce the resistive power loss which has already been applied by some major PV manufacturers (Mitsubishi, BP Solar) in their commercial available PV modules. As a consequence, quantitative analysis of PV modules using halved cells is needed. In this paper we investigate theoretically and experimentally the difference between modules made with halved and full-size solar cells. Theoretically, we find an improvement in fill factor of 1.8% absolute and output power of 90 mW for the halved cell minimodule. Experimentally, we find an improvement in fill factor of 1.3% absolute and output power of 60 mW for the halved cell module. Also, we investigate theoretically how this effect confers to the case of large-size modules. It is found that the performance increment of halved cell PV modules is even higher for high-efficiency solar cells. After that, the resistive loss of large-size modules with different interconnection schemes is analysed. Finally, factors influencing the performance and cost of industrial halved cell PV modules are discussed.
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  • 11
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    Research on the Comparison Analyses of Three-Phase Discrete and Integrated LC Filters in Three-Phase PV Inverter (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: In three-phase photovoltaic (PV) system, three-phase filter inductors are important part for the output electrical power quality. The comparison analyses of three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors in three-phase PV inverter are proposed. Firstly, the three-phase PV inverter operation with discrete filter inductors is analyzed, and the design of discrete filter inductors is given; then operation of the three-phase PV inverter with three-phase integrated five-limb magnetic core filter inductors is analyzed, the design of integrated filter inductors with five-limb magnetic core is given, then the operation of three-phase PV inverter with three-phase integrated three-limb magnetic core filter inductors is analyzed, and the design of integrated filter inductors with three limbs magnetic core is given. The conclusion of comparison between three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors is done; it means that the three-phase discrete filter inductors can achieve better output electrical power quality with lower power density and three-phase integrated filter inductors can achieve higher power density with lower output electrical power quality. Finally, the experiment results are given to compare the volume and filter effect of three kinds of filter inductors in three-phase PV inverter.
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  • 12
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    Field Measurement of Wind Effects of Roof Accessory Structures on Gable-Roofed Low-Rise Building (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: The components and claddings of low-rise buildings are usually destroyed first during typhoon disasters in coastal areas. Roof accessory structures can change the flow pattern on the roof, thus effectively reducing the wind load on the roof surface and the damage to the low-rise buildings. Three types of aerodynamic mitigation plates, that is, (1) 0.3 m high full-length roof-edge plate, (2) 0.3 m high and 0.5 m + 0.5 m long roof-corner plate, and (3) discrete roof-edge plates with different spaces (which can be used as advertisement boards), are studied on the basis of the field measurement results under roof pitches of 10° and 18.4°. By comparing the results of the roof with and without constructed plates, it is implied that the three types of plates can affect the formation of conical vortexes and can significantly reduce the mean and fluctuating pressure coefficients in the windward corner. Compared with the constructed plate, the roof ridge has a larger influence on the wind loads on leeward roof.
    Print ISSN: 1550-1329
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 13
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    Effectively Improved SiO2-TiO2 Composite Films Applied in Commercial Multicrystalline Silicon Solar Cells (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: Composite silicon dioxide-titanium dioxide (SiO2-TiO2) films are deposited on a large area of 15.6 × 15.6 cm2 textured multicrystalline silicon solar cells to increase the incident light trapped within the device. For further improvement of the antireflective coatings (ARCs) quality, dimethylformamide (DMF) solution is added to the original SiO2-TiO2 solutions. DMF solution solves the cracking problem, thus effectively decreasing reflectance as well as surface recombination. The ARCs prepared by sol-gel process and plasma-enhanced chemical vapor deposition (PECVD) on multicrystalline silicon substrate are compared. The average efficiency of the devices with improved sol-gel ARCs is 16.3%, only 0.5% lower than that of devices with PECVD ARCs (16.8%). However, from equipment depreciation point of view (the expiration date of equipment is generally considered as 5 years), the running cost (USD/watt) of sol-gel technique is 80% lower than that of PECVD method for the first five years and 66% lower than that of PECVD method from the start of the sixth year. This result proves that sol-gel-deposited ARCs process has potential applications in manufacturing low-cost, large-area solar cells.
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    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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  • 14
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    Throughput-Optimal Scheduling for Cooperative Communications in Wireless Ad Hoc Networks (2013)
    Hindawi
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    Publication Date: 2013-09-15
    Description: Cooperative communications that take advantage of the broadcasting nature of wireless environments can help to increase system throughput in wireless ad hoc networks. However, the promised throughput might be lost in presence of the error transmission and the interference caused by relay transmission in cooperative communication. In this paper, we introduced the relay selection schemes that can control the interference at the relay to prevent the relay that may harm other pairs. Then, we proposed the throughput-optimal scheduling that takes into account error probability in decision and maximizes throughput, that is, the amount of packets transmitted without error in network. In addition, we derive a simple and lightweight framework to implement the proposed policy in distributed manner. The simulation results show that the proposed scheduling policy outperforms the noncooperative policy and multihop relay policy.
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 15
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    A Novel PROMSIS Vertical Handoff Decision Algorithm for Heterogeneous Wireless Networks (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: A novel preference ranking organization method by similarity to ideal solution (PROMSIS) vertical handoff algorithm is proposed for heterogeneous wireless networks, and its essential idea includes the preference structure of the PROMETHEE and the concept of Euclid distance of the TOPSIS. Four 3GPP defined traffic classes are considered in performance evaluation. An attribute matrix is constructed considering some major attributes. Handoff decision meeting multiattribute QoS requirement is made according to the traffic features. The weight relation of decision elements is determined with the least square (LS) approach. The final decision is made using the proposed PROMSIS algorithm based on the attribute matrix and weight vector. The simulation results have manifested that the proposed PROMSIS algorithm can provide satisfactory vertical handoff performance, and the LS-PROMSIS algorithm can be fit to the characteristics of the traffic.
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  • 16
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    Enhanced Solar Photoelectrochemical Conversion Efficiency of ZnO:Cu Electrodes for Water-Splitting Application (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: n-type ZnO:Cu photoanodes were fabricated by simple spray pyrolysis deposition technique. Influence of low concentration (range ~10−4–10−1%) of Cu doping in hexagonal ZnO lattice on its photoelectrochemical performance has been investigated. The doped photoanodes displayed 7-time enhanced conversion efficiencies with respect to their undoped counterpart, as estimated from the photocurrents generated under simulated solar radiation. This is the highest enhancement in the solar conversion efficiency reported so far for the Cu-doped ZnO. This performance is attributed to the red shift in the band gap of the Cu-doped films and is in accordance with the incident-photon-current-conversion efficiency (IPCE) measurements. Electrochemical studies reveal an n-type nature of these photoanodes. Thus, the study indicates a high potential of doped ZnO films for solar energy applications, in purview of the development of simple nanostructuring methodologies.
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  • 17
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    Ontology-Based Methodology for Managing Heterogeneous Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-22
    Description: With the growing interest in ubiquitous technologies recently, many studies have been conducted in order to manage wireless sensor network, which is the central component in ubiquitous environment. To manage a certain wireless sensor network, a variety of techniques can be applied and thereby the network can be managed. However, it is very complicated and time-consuming to incorporate and manage more than a heterogeneous wireless sensor network since each network has different data, meanings, and terms. Instead of conducting verification through examining the detailed technology or simulation in order to manage a variety of wireless sensor networks, we suggest a methodology which manages data coming from the various sensors mentioned above, a technique by which those data from various sensor networks are managed in each different network, and a methodology which manages sensor networks where management languages exist. This paper defined the network-related terminology using Protégé for the tools and definitions necessary for ontology-based methodology, thereby defined OWL and the related rules, and suggested a methodology for incorporated management. In addition, this study showed that the methodology presented in this study has expandability and it can incorporate and manage a variety of wireless sensor networks.
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  • 18
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    Minimum Redundancy MIMO Array Synthesis by means of Cyclic Difference Sets (2013)
    Hindawi
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    Publication Date: 2013-09-26
    Description: Antenna array synthesis is an important issue in MIMO radars. By judiciously designing antenna positions, one can create a very long virtual array steering vector with a small number of antennas and therefore achieve very high spatial resolution at a small cost. This paper presents a combinatorial methodology based on cyclic difference sets (CDSs) for minimum redundancy (MR) MIMO array synthesis which seeks to maximize the virtual array aperture for a given number of antennas. First, the key features of CDSs and the CDS-based MR-MIMO layouts are described. Then, the analytical expression of the maximum contiguous virtual array aperture is derived. Further, based on this expression, an enumerative shifting procedure is developed for identifying the optimal CDS-based MR-MIMO layout. Selected examples are analyzed to point out the computational effectiveness of the CDS-based MR-MIMO array synthesis.
    Print ISSN: 1687-5869
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 19
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    A Framework for Robust Address Assignment in WSNs Whispering to Avoid Intruders (2013)
    Hindawi
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    Publication Date: 2013-09-26
    Description: Wireless sensor networks (WSNs) are becoming bigger, and with this growth comes the need for new automatic mechanisms for initializations done by hand. One of those mechanisms is the assignment of addresses to nodes. Several solutions were already proposed for mobile ad hoc networks but they either (i) do not scale well for WSN; (ii) have no energy constraints; (iii) have no security considerations; (iv) or have no mechanisms to handle fusion of network partitions. We proposed an address self-assignment protocol which uses negative acknowledgements and an improved version of a flood control mechanism to minimize the energy spent; uses a technique named whispering to achieve robustness against malicious nodes; is able to detect dynamic network re-joint and dynamic node addition without exchanging specific messages; and handles both dynamic events without compromising routing tables.
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  • 20
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    Hardware Design of Seismic Sensors in Wireless Sensor Network (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: Seismic sensors are invaluable for intruder detection and perimeter security. In a typical wireless sensor network application of seismic sensors, the units are battery powered and low power consumption becomes critical while fulfilling system requirements. Although many systems utilize 24-bit ADC for seismic signal processing, we employed 12-bit ADC for low power consumption. Because of this relatively low resolution ADC, preamplifier and filters require careful hardware design. We employ bidirectional T-type filtering, noise reduction, and distributed filtering between gain stages before the signal is input to ADC. The proposed design was verified with measurements. Seismic data signals due to footsteps at varying distances were successfully measured.
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  • 21
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    Robust Detection of Malicious Nodes in Mobile Sensor Networks Using Software Attestation (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: In ad hoc and sensor networks, reputation-based trust management schemes have been widely used to identify the malicious nodes. These schemes leverage each node’s behaviors for malicious node detection and thus require a certain amount of time to observe the behaviors of nodes. In mobile sensor networks, however, malicious nodes frequently move to different locations, and thus it is likely difficult to collect enough evidence for them. Moreover, when reputation-based schemes are employed, it is not easy to revoke the malicious nodes due to the risk of false positives. To mitigate these limitations of reputation-based schemes, we propose mobile malicious node detection schemes based on software attestation technique, which virtually fulfills zero false positives. In particular, we propose a probabilistic detection scheme in which each node attests its neighboring node with a certain probability. In order to reduce the attestation overhead of the probabilistic detection scheme, we also propose the SPRT (Sequential Probability Ratio Test) based detection scheme that uses the SPRT to determine when to perform the attestations. Through analysis and simulation, we show that our proposed schemes detect mobile malicious nodes through software attestations in robust and efficient manner.
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  • 22
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    Hybrid Ant Algorithm Based Query Processing with Multiagents in Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: The wireless sensor networks are usually deployed in various application-specific contexts, which can be treated as distributed databases with big data. The event-involved query responses can be obtained by issuing query requests to this kind of database. However, the constraints of the energy and delay have had a great impact on the operation of wireless sensor networks. How to design the query-involved network model and the corresponding query processing algorithms is extremely challenging. This work investigates query processing problem in resource-constrained wireless sensor networks with the two-tier architecture and multiple query agents, where the multiple nodes of query agents are configured in the networks and the corresponding source cluster-heads send collected events to only one optimum query agent. To reduce the energy consumption and shorten the delivery delay, an efficient query processing algorithm inspired by the swarm intelligence of ants is proposed, which takes advantage of the beneficial clustering and routing emerging in a hybrid self-organized way from the positive interaction of ants. The experimental results demonstrated that the proposed algorithm can deliver collected events to the optimum query agents efficiently. Not only is the energy cost reduced but also the delivery delay is shortened significantly when transmitting the named events to the appropriate query agents.
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  • 23
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    The Nonuniform Node Configuration of Wireless Sensor Networks for Long-Span Bridge Health Monitoring (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: This paper presents a nonuniform node configuration of wireless sensor networks (WSNs) for long-span bridge health monitoring. The methodology and strategy of two-phase node arrangement for nonuniform WSN configuration are firstly presented, and then numerical examples are carried out by a long-span suspension bridge. Three cases, which are four sensor nodes distributed on one side of the girder, ten sensor nodes distributed on one side of the girder, and eight sensor nodes distributed averagely on two sides of the girder, are employed. In case I and case II, three schemes that are the nonuniform node configuration arranged by the two-phase node arrangement method, the uniform nodes configuration, and the independent sensor nodes configuration are used for comparison. And in case III, two schemes that are nonuniform nodes configuration and the independent sensor nodes configuration are adopted. The results indicate that the nonuniform node configuration can balance energy consumption, eliminate “energy hole,” and maximize network performance effectively, which shows the most outstanding performance when compared with other conventional node configurations. So, the efficiency of the two-phase node arrangement method is validated.
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  • 24
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    Photovoltaic System Modeling with Fuzzy Logic Based Maximum Power Point Tracking Algorithm (2013)
    Hindawi
    Details
    Publication Date: 2013-10-01
    Description: This paper represents a novel modeling technique of PV module with a fuzzy logic based MPPT algorithm and boost converter in Simulink environment. The prime contributions of this work are simplification of PV modeling technique and implementation of fuzzy based MPPT system to track maximum power efficiently. The main highlighted points of this paper are to demonstrate the precise control of the duty cycle with respect to various atmospheric conditions, illustration of PV characteristic curves, and operation analysis of the converter. The proposed system has been applied for three different PV modules SOLKAR 36 W, BP MSX 60 W, and KC85T 87 W. Finally the resultant data has been compared with the theoretical prediction and company specified value to ensure the validity of the system.
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    Spectrum Sensing for Cognitive Coexistent Heterogeneous Networks (2013)
    Hindawi
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    Publication Date: 2013-10-02
    Description: This paper proposes a noncoherent spectrum sensing scheme for the cognitive coexistent heterogeneous networks with the assistance of geolocation information of primary and secondary nodes. Different from the conventional networks with single secondary network, the spectrum sensing scheme in the coexistence scenario should not only detect the primary signal but also detect the secondary signals to avoid the interference with both the primary network and the operating coexistent secondary networks. Therefore, the sensing scheme in this case should be able to differentiate the primary signal from each kind of the secondary signals. However, in the coexistent heterogeneous scenarios, the secondary signals may exploit different PHY modes (some of them may be the same as the primary PHY mode), which imposes difficulties in the coherent signal detection schemes. Aiming to tackle this problem, the parallel detection of both primary signal and each kind of secondary signals is implemented through a proposed noncoherent power decomposition scheme. In this scheme, the power decomposition is formulated into a problem of solving a nonhomogeneous linear equation matrix. During the signal detection, the characteristics of both primary and secondary signals are not required. Both the analysis and the simulation results show the feasibility and efficiency of the proposed scheme.
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    A Smart Electronic Tagging System Based on Context Awareness and Machine-to-Machine Interworking (2013)
    Hindawi
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    Publication Date: 2013-10-02
    Description: The existing electronic tagging system traces the location of a sex offender using triangulation by communicating with Global Positioning System (GPS) satellites and mobile phone base stations. The acquired location information is used to prevent the offenders from perpetrating repeat crimes. However, the battery resources of such a system are inadequate as it has to trace the location of the moving target in real time and consumes a large amount of battery power while communicating with GPS satellites and mobile phone base stations. In addition, the systems cannot infer the mental state of the targets or detect their alcohol consumption levels, which may be necessary for the prevention of a repeat crime. The purpose of this study is to connect the Ubiquitous System Network (USN), which consumes little electricity, and Android mobile platforms, which are commonly used for machine-to-machine communication. Thus, this system will legally facilitate the protection of minors by providing information only about the target’s approach to certain facilities. In addition, the system uses an Android platform to process data measured by the USN’s sensors, which can also detect alcohol intake and infer the mental state of the target, and then initiates the corresponding real-time context-awareness services.
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    Reconfigurable Antenna Assisted Intrusion Detection in Wireless Networks (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: Intrusion detection is a challenging problem in wireless networks due to the broadcast nature of the wireless medium. Physical layer information is increasingly used to protect these vulnerable networks. Meanwhile, reconfigurable antennas are gradually finding their way into wireless devices due to their ability to improve data throughput. In this paper, the capabilities of reconfigurable antennas are used to devise an intrusion detection scheme that operates at the physical layer. The detection problem is posed as a GLRT problem that operates on the channels corresponding to the different modes of a reconfigurable antenna. The performance of the scheme is quantified through field measurements taken in an indoor environment at the 802.11 frequency band. Based on the measured data, we study the achievable performance and the effect of the different control parameters on the performance of the intrusion detection scheme. The effect of pattern correlation between the different modes on the scheme’s performance is also analyzed, based on which general guidelines on how to design the different antenna modes are provided. The results show that the proposed scheme can add an additional layer of security that can significantly alleviate many vulnerabilities and threats in current fixed wireless networks.
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    Joint Relay Ordering and Linear Finite Field Network Coding for Multiple-Source Multiple-Relay Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: Network coding (NC) is significant for the spectral efficiency promotion of the multiple-source multiple-relay wireless sensor networks (WSNs). However, the existing scheme ignored further exploitation of the communications between relays. To address this issue, a relay ordering algorithm based on finite field NC (FFNC) is proposed in this paper. In the scheme, the relays who initially fail to decode from sources are kept listening and searching for the opportunity to decode the signals from other relays, so as to recover the failure links. The outage probability of the scheme and the corresponding lower bound are theoretically deduced under two-source two-relay assumption. Moreover, the scheme is proved to own the merit of diffusion effect, which makes the diversity improvement more efficient by simply increasing the relay number in the network. Simulation results correspond well with the analysis and demonstrate that the proposed scheme always outperforms FFNC in outage behavior and attains more opportunities to supply full diversity for the network. Moreover, it shows that the diffusion effect enables this scheme to be very suitable for the multiple-relay WSN.
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    Preparation and Characterization of Chitosan Binder-Based Electrode for Dye-Sensitized Solar Cells (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: A chitosan binder-based TiO2 photoelectrode is used in dye-sensitized solar cells (DSSCs). Field-emission scanning electron microscope (FE-SEM) images revealed that the grain size, thickness, and distribution of TiO2 films are affected by the chitosan content. With addition of 2.0 wt% chitosan to the TiO2 film (D2), the surface pore size became the smallest, and the pores were fairly evenly distributed. The electron transit time, electron recombination lifetime, diffusion coefficient, and diffusion length were analyzed by IMVS and IMPS. The best DSSC, with 2.0 wt% chitosan addition to the TiO2 film, had a shorter electron transit time, longer electron recombination lifetime, and larger diffusion coefficient and diffusion length than the other samples. The results of 2.0 wt% chitosan-added TiO2 DSSCs are an electron transit time of  s, electron recombination lifetime of  s, diffusion coefficient of  cm2 s−1, diffusion length of 14.81 μm, and a solar conversion efficiency of 4.18%.
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    Synthesis of Nitrogen-Doped ZnS with Camellia Brushfield Yellow Nanostructures for Enhanced Photocatalytic Activity under Visible Light Irradiation (2013)
    Hindawi
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    Publication Date: 2013-10-03
    Description: Nitrogen modified zinc sulfide photocatalysts were successfully prepared and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and surface area analysis. Thermal decomposition of the semisolid was carried out under nitrogen conditions at 500°C for 2 hours, and a series of nitrogen-doped ZnS photocatalysts were produced by controlling inflow flow rate of nitrogen at 15–140 mL/min. Optical characterizations of the synthesized N-doping ZnS substantially show the shifted photoabsorption properties from ultraviolet (UV) region to visible light. The band gaps of nitrogen-doped ZnS composite catalysts were calculated to be in the range of 2.58~2.74 eV from the absorptions edge position. The 15N/ZnS catalyst shows the highest photocatalytic activity, which results in 75.7% degradation of Orange II dye in 5 hrs by visible light irradiation, compared with pristine ZnS and higher percentage N-doping ZnS photocatalysts.
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    A Faster Convergence Artificial Bee Colony Algorithm in Sensor Deployment for Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-10-04
    Description: In wireless sensor networks (WSN), sensor deployment is one of the main topics for enhancing the sensor’s coverage rate. In this paper, by modifying updating equation of onlooker bee and scout bee of original artificial bee colony (ABC) algorithm, a sensor deployment algorithm based on the modified ABC algorithm is proposed. Some new parameters such as forgetting and neighbor factor for accelerating the convergence speed and probability of mutant for maximizing the coverage rate are introduced. Simulation results showed that comparing with the deployment method based on original ABC and particle swarm optimization (PSO) algorithm, the proposed approach can achieve a better performance in coverage rate and convergence speed while needing a less total moving distance of sensors.
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    Localization in Wireless Sensor Network (2013)
    Hindawi
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    Publication Date: 2013-10-04
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    An Efficient WSN Simulator for GPU-Based Node Performance (2013)
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    Publication Date: 2013-10-04
    Description: In wireless sensor network, when these sensors are wrongly placed in an observation region, they can quickly run out of batteries or be disconnected. These incidents may result in huge losses in terms of sensing data from numerous sensors and their costs. For this reason, a number of simulators have been developed as tools for effective design and verification before the actual arrangement of sensors. While a number of simulators have been developed, simulation results can be fairly limited and the execution speed can be markedly slow depending on the function of each simulator. In this regard, to improve the performance of existing simulators, this research aimed to develop a parallel calculation simulator for independent sensor (PCSIS) that enables users to selectively use the GPU mode and, based on this mode, enables parallel and independent operations by matching GPU with many cores in order to resolve the slowdown of the execution speed when numerous sensor nodes are used for simulations. The PCSIS supports the GPU mode in an environment that allows the operation of compute unified device architecture (CUDA) and performs the parallel simulation calculation of multiple sensors using the mode within a short period of time.
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    Development of the Prediction System of Condensation Based on Wireless Communications (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: Due to advances in microelectromechanical system (MEMS), many smart sensors have been developed. A large number of sensors build a wireless sensor network and can communicate with each other. Wireless sensor networks help monitor objects in our environment, and many researches about this technology are in progress. Condensation is a phenomenon that water vapor contained in the air condenses and makes water droplets. This is caused by the complex action of a variety of factors, including the temperature difference between indoor and outdoor and excessive indoor moisture, so it is never easy to identify the cause and establish measures for the actual building. In this paper, a system is presented to predict and alert condensation promptly and accurately, considering the causes and prevention of condensation. In this paper, a system will be developed to collect and monitor environmental information causing condensation, in real time using a wireless sensor network in order to build a system to prevent condensation. The users are expected to use this system to easily identify the cause of condensation and take actions based on the cause-specific alarm messages in order to alleviate aesthetics and hygiene problems due to condensation.
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    DFT/TDDFT and Experimental Studies of Natural Pigments Extracted from Black Tea Waste for DSSC Application (2013)
    Hindawi
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    Publication Date: 2013-09-12
    Description: We report results of combined experimental and theoretical studies of black tea waste extract (BTE) as a potential sensitizer for TiO2-dye-sensitized solar cells (DSSCs). UV-vis absorption data revealed that BTE contains theaflavin. DSSC sensitized with pigment complexes of BTE showed a photon-energy conversion efficiency of %, while a significant increase (%) is observed when pH of the pigment solution was lowered. The HOMO and LUMO energy levels were calculated using experimental data of UV-vis absorption and cyclic voltammetry. These calculations revealed a reduction of the band gap by 0.17 eV and more negativity of HOMO level of acidified pigment, compared to that of original pigment. Combined effect of these developments caused the enhanced efficiency of DSSC. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) computational calculations were carried out to study the four theaflavin analogues which are responsible for the dark colour of BTE. According to the calculations, two theaflavin analogues, theaflavin and theaflavin digallate, are the most probable sensitizers in this dye-sensitized solar cell system.
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    Full-Wave Analysis of Microstrip Antennas in Three-Layered Spherical Media (2013)
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    Publication Date: 2013-09-13
    Description: A model of three-layered spherical microstrip antenna has been analyzed based on Rao-Wilton-Glisson (RWG) triangular basis functions using mixed potential integral equation (MPIE). Firstly, the model of antenna and the dyadic Green’s function in spherical microstrip antennas are given at the beginning of this paper. Then, due to the infinite series convergence problem, asymptotic extraction approach is presented to accelerate the Green’s functions convergence speed when source and field points are located in the same layer and different layers. The convergence speed can be accelerated observably by using this method. Finally, in order to simplify impedance matrix elements calculation at the junction of the probe and patch, a novel division fashion of pair of triangles is adopted in this paper. The input impedance result obtained shows the validity and effectiveness of the analysis method comparing with published data.
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    Frequency-Adjustable Small Zeroth-Order Resonant Antenna with Capacitor-Loaded Rectangular Slot on Ground Plane (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: A capacitor-loaded electrical small zeroth-order resonant (ZOR) antenna is proposed. The proposed antenna is designed on the basis of a mushroom structure for zeroth-order resonance. To obtain a compact size, the proposed antenna has a rectangular slot on the ground plane, and the chip capacitor is mounted on the slot. The resonant frequency is easily controlled from 2.82 GHz to 2.29 GHz by changing the capacitance from 1 pF to 7 pF, respectively. Therefore, the proposed antenna has the advantages of a small antenna size as well as easy frequency adjustment.
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    The Application of a Surface Response Methodology in the Solar/UV-Induced Degradation of Dairy Wastewater Using Immobilized ZnO as a Semiconductor (2013)
    Hindawi
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    Publication Date: 2013-09-13
    Description: An Advanced Oxidation Process (AOPs) was carried out in this study with the use of immobilized ZnO and solar/UV as an energy source to degrade dairy wastewater. The semibatch reactor system consisted of metal plate of 800 × 250 mm and a glass tank. The reaction time was of 3 h for 3 L of dairy wastewater. Experiments were performed based on a surface response methodology in order to optimize the photocatalytic process. Degradation was measured in percentage terms by total organic carbon (TOC). The entry variables were ZnO coating thickness and pH, using three levels of each variable. The optimized results showed a TOC degradation of 31.7%. Optimal parameters were metal-plate coating of 100 μm of ZnO and pH of 8.0. Since solar/UV is a constant and free energy source in most tropical countries, this process tends to suggest an interesting contribution in dairy wastewater treatment, especially as a pretreatment and the optimal conditions to guarantee a better efficiency of the process.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    Coverage Optimization Algorithm Based on Sampling for 3D Underwater Sensor Networks (2013)
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    Publication Date: 2013-09-13
    Description: We discuss the problem of maximizing the sensor field coverage for a specific number of sensors while minimizing the distance traveled by the sensor nodes. Thus, we define the movement task as an optimization problem that involves the adjustment of sensor node positions in a coverage optimization mission. We propose a coverage optimization algorithm based on sampling to enhance the coverage of 3D underwater sensor networks. The proposed coverage optimization algorithm is inspired by the simple random sampling in probability theory. The main objective of this study is to lessen computation complexity by dimension reduction, which is composed of two detailed steps. First, the coverage problem in 3D space is converted into a 2D plane for heterogeneous networks via sampling plane in the target 3D space. Second, the optimization in the 2D plane is converted into an optimization in a line segment by using the line sampling method in the sample plane. We establish a quadratic programming mathematical model to optimize the line segment coverage according to the intersection between sensing circles and line segments while minimizing the moving distance of the nodes. The intersection among sensors is decreased to increase the coverage rate, while the effective sensor positions are identified. Simulation results show the effectiveness of the proposed approach.
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    Exergy, Energy, and Dynamic Parameter Analysis of Indigenously Developed Low-Concentration Photovoltaic System (2013)
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    Publication Date: 2013-09-13
    Description: Piecewise linear parabolic trough collector (PLPTC) is designed and developed to concentrate solar radiation on monocrystalline silicon based photovoltaic module. A theoretical model is used to perform electrical energy and exergy analysis of low-concentration photovoltaic (LCPV) system working under actual test conditions (ATC). The exergy efficiency of LCPV system is in the range from 5.1% to 4.82% with increasing rate of input exergy rate from 30.81 W to 96.12 W, when concentration ratio changes from 1.85 to 5.17 Sun. Short-circuit current shows increasing trend with increasing input exergy rate of ≈0.011 A/W. Power conversion efficiency decreases from 7.07 to 5.66%, and open-circuit voltage decreases from 9.86 to 8.24 V with temperature coefficient of voltage  V/K under ATC. The results confirm that the commercially available silicon solar PV module performs satisfactorily under low concentration.
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    QoS-Aware Fault Detection in Wireless Sensor Networks (2013)
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    Publication Date: 2013-09-13
    Description: Wireless sensor networks (WSNs) are a fundamental building block of many pervasive applications. Nevertheless the use of such technology raises new challenges regarding the development of reliable and fault-tolerant systems. One of the most critical issues is the detection of corrupted readings amidst the huge amount of gathered sensory data. Indeed, such readings could significantly affect the quality of service (QoS) of the WSN, and thus it is highly desirable to automatically discard them. This issue is usually addressed through “fault detection” algorithms that classify readings by exploiting temporal and spatial correlations. Generally, these algorithms do not take into account QoS requirements other than the classification accuracy. This paper proposes a fully distributed algorithm for detecting data faults, taking into account the response time besides the classification accuracy. We adopt the Bayesian networks to perform classification of readings and the Pareto optimization to allow QoS requirements to be simultaneously satisfied. Our approach has been tested on a synthetic dataset in order to evaluate its behavior with respect to different values of QoS constraints. The experimental evaluation produced good results, showing that our algorithm is able to greatly reduce the response time at the cost of a small reduction in classification accuracy.
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    Wireless Sensor Networks for the Internet of Things (2013)
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    Publication Date: 2013-09-17
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    Optical and Electrical Properties of Thin Films of CuS Nanodisks Ensembles Annealed in a Vacuum and Their Photocatalytic Activity (2013)
    Hindawi
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    Publication Date: 2013-09-18
    Description: Effects on the optical, electrical, and photocatalytic properties of undoped CuS thin films nanodisks vacuum annealed at different temperatures were investigated. The chemical bath prepared CuS thin films were obtained at 40°C on glass substrates. The grain size of  nm was computed directly from high-resolution transmission electron microscopy (HRTEM) images. The electrical properties were measured by means of both Hall effect at room temperature and dark resistivity as a function of the absolute temperature 100–330 K. The activation energy values were calculated as 0.007, 0.013, and 0.013 eV for 100, 150, and 200°C, respectively. The energy band gap of the films varied in the range of 1.98 up to 2.34 eV. The photocatalytic activity of the CuS thin film was evaluated by employing the degradation of aqueous methylene blue solution in the presence of hydrogen peroxide. The CuS sample thin film annealed in vacuum at 150°C exhibited the highest photocatalytic activity in presence of hydrogen peroxide.
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    W-LEACH Based Dynamic Adaptive Data Aggregation Algorithm for Wireless Sensor Networks (2013)
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    Publication Date: 2013-09-19
    Description: We consider the problem of data aggregation for nonuniform and evolving wireless sensor networks. We introduce a new data aggregation algorithm that is able to run on uniform, non-uniform, and evolving networks while maintaining the data accuracy. In addition, the algorithm is able to handle sudden bursts in the underlying data by recording the data in the area of interest for the whole event duration. Experimental results on real and synthetic data show that the algorithm performs well in terms of extending the lifetime of the network, maintaining the original distribution of the sensors as long as possible, maintaining the accuracy of the sensed data, and being able to detect and handle sudden bursts of data.
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    Congestion Control Based on Consensus in the Wireless Sensor Network (2013)
    Hindawi
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    Publication Date: 2013-09-19
    Description: The congestion control algorithm based on the weighted directed graph is designed for the network congestion over the wireless sensor network. The congestion problem is modeled as a distributed dynamic system with time-varying delay, and it can be proven that the sent rate for all nodes converges to the available bandwidth of the sink by the proposed congestion control algorithm. Via Lyapunov function, the validity of the proposed algorithm is shown under the varying network topologies. Ns simulation results indicate that the proposed algorithm restrains the congestion over the wireless sensor network, maintains a high throughput and a low delay time, and also improves the quality of service for the whole network.
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    Time-Domain Physical Optics Method for the Analysis of Wide-Band EM Scattering from Two-Dimensional Conducting Rough Surface (2013)
    Hindawi
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    Publication Date: 2013-09-20
    Description: Time-domain physical optics (TDPO) method is extended to investigate electromagnetic (EM) scattering from two-dimensional (2D) perfectly electrically conducting (PEC) rough surface in both time domain and frequency domain. The scheme requires relatively small amounts of computer memory and CPU time, and has advantage over the Kirchhoff Approximation (KA) method in obtaining transient response of rough surface by a program run. The 2D Gaussian randomly rough surface is generated by Monte Carlo method and then is partitioned into small triangle facets through the meshing preprocess. The accuracy of TDPO is validated by comparing the numerical results with those obtained by the KA method in both backward and specular directions. The transient response and its frequency distribution of radar cross section (RCS) from rough surface is shown, respectively. The scattering results from rough surface with different size in the specular direction are given. The influence of the root mean square height (σ) and correlation length () on electromagnetic scattering from PEC rough surface is discussed in detail. Finally, the comparisons of backscattering results at different incident angles are presented and analyzed.
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    Zero Index Metamaterial for Designing High-Gain Patch Antenna (2013)
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    Publication Date: 2013-09-20
    Description: A planar wideband zero-index metamaterial (ZIM) based on mesh grid structure is studied. It is demonstrated that the real part of the index approaches zero at the wideband covering from 9.9 GHz to 11.4 GHz. Two conventional patch antennas whose operating frequencies are both in the range of zero-index frequencies are designed and fabricated. And then, the ZIM is placed in the presence of the conventional patch antennas to form the proposed antennas. The distance between the antenna and the ZIM cover is investigated. Antenna performances are studied with simulations and measurements. The results show that the more directional and higher gain patch antennas can be obtained. The measured results are in good agreement with the simulations. Compared to the conventional patch antenna without the ZIM, it is shown that the beamwidth of antenna with the ZIM cover becomes more convergent and the gain is much higher.
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    Radiation Effects in Solar Cells and Optoelectronic Devices (2013)
    Hindawi
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    Publication Date: 2013-09-20
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    Life Cycle Costs and Life Cycle Assessment for the Harvesting, Conversion, and the Use of Switchgrass to Produce Electricity (2013)
    Hindawi
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    Publication Date: 2013-09-24
    Description: This paper considers both LCA and LCC of the pyrolysis of switchgrass to use as an energy source in a conventional power plant. The process consists of cultivation, harvesting, transportation, storage, pyrolysis, transportation, and power generation. Here pyrolysis oil is converted to electric power through cocombustion in conventional fossil fuel power plants. Several scenarios are conducted to determine the effect of selected design variables on the production of pyrolysis oil and type of conventional power plants. The set of design variables consist of land fraction, land shape, the distance needed to transport switchgrass to the pyrolysis plant, the distance needed to transport pyrolysis oil to electric generation plant, and the pyrolysis plant capacity. Using an average agriculture land fraction of the United States at 0.4, the estimated cost of electricity from pyrolysis of 5000 tons of switchgrass is the lowest at $0.12 per kwh. Using natural gas turbine power plant for electricity generation, the price of electricity can go as low as 7.70 cent/kwh. The main advantage in using a pyrolysis plant is the negative GHG emission from the process which can define that the process is environmentally friendly.
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    Skyline-Based Aggregator Node Selection in Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-24
    Description: In order to achieve the equal usage of limited resources in the wireless sensor networks (WSNs), we must aggregate the sensor data before passing it to the base station. In WSNs, the aggregator nodes perform a data aggregation process. Careful selection of the aggregator nodes in the data aggregation process results in reducing large amounts of communication traffic in the WSNs. However, network conditions change frequently due to sharing of resources, computation load, and congestion on network nodes and links, which makes the selection of the aggregator nodes difficult. In this paper, we study an aggregator node selection method in the WSNs. We formulate the selection process as a top-k query problem, where we efficiently solve the problem by using a modified Sort-Filter-Skyline (SFS) algorithm. The main idea of our approach is to immediately perform a skyline query on the sensor nodes in the WSNs, which enables to extract a set of sensor nodes that are potential candidates to become an aggregator node. The experiments show that our method is several times faster compared to the existing approaches.
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    High Reliable Relay Selection Approach for QoS Provisioning in Wireless Distributed Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-24
    Description: In wireless distributed sensor networks, one open problem is how to guarantee the reliable relay selection based on the quality of services diversity. To address this problem, we focus on the reliable adaptive relay selection approach and adaptive QoS supported algorithm, based on which we present a Markov chain model, in consideration of different packet states and error control algorithm assignment. The mathematical analyses and NS-2 simulation results show that the proposed relay selection approach could perform better in terms of saturation throughput, reliability, and energy efficiency, compared with the traditional approaches. More importantly, the quality of real-time multimedia streaming is improved significantly, in terms of decodable frame ratio and delay.
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    Wireless Ad Hoc Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-24
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    Deployment Support for Sensor Networks in Indoor Climate Monitoring (2013)
    Hindawi
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    Publication Date: 2013-09-24
    Description: Automatic recognition of personal comfort is critical in realizing autonomous control of building utilities. We can infer human comfort level based on indoor environmental conditions, such as temperature and humidity, collected through sensor networks. However, the majority of methods for optimally deploying sensor networks in indoor climate monitoring mainly focused on achieving accurate measurements such as temperature distribution map with the minimum cost. Indeed, for automatic recognition of comfort using machine learning, we need to collect datasets preserving as much of the discriminatory information for inferring personal comfort with the minimum cost. In this paper, we present a novel method of placing and minimizing sensor nodes for sensor networks in smart energy systems. We have developed ZigBee-based sensor nodes and collected temperature, humidity, and illumination dataset from 13 nodes for a week. Using the dataset, we group the sensor nodes into coherent clusters, and then select a representative node which has the maximum value of RSSI for each cluster and remove the other redundant sensors, reducing the number of sensor nodes deployed. To show the feasibility of the proposed method, we perform a classification analysis of building environment. The recognition accuracy decreased by 13 percent with 6 selected sensor nodes, compared to the result with all 13 sensor nodes.
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    Carbonic Anhydrase: An Efficient Enzyme with Possible Global Implications (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: As the global atmospheric emissions of carbon dioxide (CO2) and other greenhouse gases continue to grow to record-setting levels, so do the demands for an efficient and inexpensive carbon sequestration system. Concurrently, the first-world dependence on crude oil and natural gas provokes concerns for long-term availability and emphasizes the need for alternative fuel sources. At the forefront of both of these research areas are a family of enzymes known as the carbonic anhydrases (CAs), which reversibly catalyze the hydration of CO2 into bicarbonate. CAs are among the fastest enzymes known, which have a maximum catalytic efficiency approaching the diffusion limit of 108 M−1s−1. As such, CAs are being utilized in various industrial and research settings to help lower CO2 atmospheric emissions and promote biofuel production. This review will highlight some of the recent accomplishments in these areas along with a discussion on their current limitations.
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    On the Security of Data Collection and Transmission from Wireless Sensor Networks in the Context of Internet of Things (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: In the context of Internet of Things (IoT), multiple cooperative nodes in wireless sensor networks (WSNs) can be used to monitor an event, jointly generate a report and then send it to one or more Internet nodes for further processing. A primary security requirement in such applications is that every event data report be authenticated to intended Internet users and effectively filtered on its way to the Internet users to realize the security of data collection and transmission from the WSN. However, most present schemes developed for WSNs don’t consider the Internet scenario while traditional mechanisms developed for the Internet are not suitable due to the resource constraint of sensor nodes. In this paper, we propose a scheme, which we refer to as Data Authentication and En-route Filtering (DAEF), for WSNs in the context of IoT. In DAEF, signature shares are generated and distributed based on verifiable secret sharing cryptography and an efficient ID-based signature algorithm. Our security analysis shows that DAEF can defend against node compromise attacks as well as denial of service (DoS) attacks in the form of report disruption and selective forwarding. We also analyze energy consumption to show the advantages of DAEF over some comparable schemes.
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    A Utility-Based Rate Allocation of M2M Service in Heterogeneous Wireless Environments (2013)
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    Publication Date: 2013-09-25
    Description: This paper presents a dynamic adaptive machine-to-machine (M2M) service rate allocation scheme for optimum traffic distribution in heterogeneous wireless environments (HWEs). According to the M2M service characteristics, it proposes the utility function, which forms a convex optimization problem that maximizes the utility of M2M service and can be solved by the Lagrange multiplier. The simulation results show the proposed method convergence, and it can achieve load balance with maximized throughput and minimized cost.
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    A Coding and Postprocessing Framework of Multiview Distributed Video for Wireless Video Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: In many surveillance application scenarios of wireless video sensor networks (WVSNs), a number of video sensors are deployed, and multidimension monitored the visual information in a region of interest, forming multiview videos. Since the power, computing capability, and bandwidth are very limited in WVSNs, the conventional multiview video coding method is no longer applicable. So multiview distributed video coding (MDVC) emerged and developed rapidly. In this paper, we propose a new multiview video coding and postprocessing framework for multiview videos. First, in coding scheme, motion intense regions (MIRs) and nonmotion intense regions (NMIRs) based on sum of absolute difference (SAD) criteria are distinguished. For the MIR, the side information (SI) is generated by fusion temporal SI and interview spatial SI at the pixel level. But for the NMIR, the temporal SI is directly use as the ultimate SI. Then, to further improve the quality of the decoded image, an image postprocessing scheme is designed by using deblocking and deringing artifact filters on decoded image. Finally, a set of experimental results show that the proposed fusion SI approach can bring improvements up to 0.2–0.5 dB when compares with only temporal SI used. The subsequent decoded videos postprocessing simulation proves that the proposed postprocessing scheme can provide an additional improvement of about 0.1 dB to the decoded video sequences.
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    Delay-Driven Routing for Low-Duty-Cycle Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: Duty-cycled operation has been introduced as an efficient way to preserve nodes energy and prolong network lifetime for wireless sensor networks. However, such networks are often logically disconnected since there is a limited number of active nodes within a period of time. Traditional routing algorithms, which have been designed for always-awake wireless networks, suffer excessive waiting time incurred by asynchronous schedule of nodes and cannot be applied to these time-dependent sensor networks. In this work, we study the optimization of delivery delay for low-duty-cycle sensor networks. Specially, we theoretically analyze the sleep latency in low-duty-cycle networks and present a new routing metric, which takes both lossy link and asynchronous schedule of nodes into consideration. Based on the metric, we propose delay-driven routing algorithms to find optimal forwarder in order to reduce delivery delay for source-to-sink communication. We compare our design against state-of-the-art routing algorithms derived in wireless networks through large-scale simulations and testbed experiments, which show that our algorithms can achieve a significant reduction in delivery delay.
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    Fisher Information of Mine Collapse Hole Detection Based on Sensor Nodes Connectivity (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: It is very important to detect a collapse hole for coal mine workers. The possibility of detecting the collapse hole using WSN is presented because the tunnel in coal mine is narrow and has poor working condition. Comparing three types of the hole detection methods, it is seen that the connectivity-based methods are used to detect coal mine collapse better than other methods. By establishing a 2D model of the collapse hole in coal mine, a class of algorithms for detecting the collapse hole in coal mine is described. Based on log-normal shadowing channel model, the accuracy of detecting the collapse hole in coal mine using Fisher information is analyzed. Numerical calculation shows that connectivity-based localization schemes are better to detect collapse hole of coal mine.
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    Voltammetry Study of an Anti-HIV Compound by means of a Thin Organic Membrane (2013)
    Hindawi
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    Publication Date: 2013-09-25
    Description: Cyclic and square wave voltammetries have been used to study electrochemical behaviour of an anti-HIV agent (Guttiferone A) at the liquid-liquid interface. The thin organic membrane is formed by an organic solvent containing redox probe. Guttiferone A, a benzophenone (BP) with appropriate electrolyte. It is demonstrated that BP possesses three reduction systems due to the redox transformation of the three tautomeric forms that lead to the migration of proton between the hydroxyl group in position 4 and the carbonyl group in positions 2 and 10. The transfer of proton from the aqueous solution to the organic phase is crucial for the redox transformation of BP into the organic membrane. The voltammograms obtained are strongly influenced by the pH of the aqueous phase. The electrochemical mechanism consists of 2e−/2H+ exchange to form the separate redox compound BPH2.
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    Distributional Fractal Creating Algorithm in Parallel Environment (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: Nowadays, the fractal is used widely everywhere. Then, its creating time becomes an important study area for complex iteration functions because the escape-time algorithm (ETA), which is the most used algorithm in fractal creating, performs not so well in this condition. In this paper, in order to solve this problem, we improve ETA into the parallel environment and reach well performance. At first, we provide a separation method of ETA to reform it into a SIMC-MC2 grid. Secondly, we prove its correctness and compute the complexity of this novel parallel algorithm. Meantime, we separate an improved ETA which we have presented into the same parallel environment and compute its complexity. Additionally, theoretical and experimental results show the characteristics of this novel algorithm. Finally, the computational result shows that a novel environment is needed to decrease large manual allocation strategies, which block the improved benefit.
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    A+MAC: A Streamlined Variable Duty-Cycle MAC Protocol for Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-09-27
    Description: To improve the energy efficiency and the transmission performance of a sensor network MAC protocol under time varying traffic conditions, recent researches have adopted a variable duty cycle operation that makes each node dynamically adjust its own wakeup and sleep schedule according to a predefined trigger condition. However, most of the existing protocols still waste energy on a long preamble packet for waking up a receiver or long idle listening for checking potential communications. To address the energy waste problem, this paper introduces a hybrid MAC protocol called A+MAC that exploits a complementary cooperation between CSMA/CA and preamble sampling. In A+MAC CSMA/CA is used for carrying out communication processes, and preamble sampling is used for checking potential communications. Therefore, A+MAC minimizes both idle listening and the length of a preamble packet by exploiting a short preamble that makes nodes check only the event occurrence. A+MAC also optimizes control packet formats and eliminates both virtual carrier sensing and a separate clock synchronization period from conventional CSMA/CA based MAC protocols. We evaluated both the energy and the network performance of the protocol by using both NS-2 and MICA2 platforms. Our experimentation results show that A+MAC can achieve an order of magnitude energy savings while providing near optimal latency compared to the existing solutions.
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    Chemical Reaction Effect on Transient Free Convective Flow past an Infinite Moving Vertical Cylinder (2013)
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    Publication Date: 2013-09-29
    Description: An analysis is performed to study the heat and mass transfer on the flow past an infinite moving vertical cylinder, in the presence of first-order chemical reaction. The closed-form solutions of the dimensionless governing partial differential equations are obtained in terms of Bessel's functions and modified Bessel's functions by the Laplace transform technique. The transient velocity profiles, temperature profiles, and concentration profiles are studied for various sets of physical parameters, namely, the chemical reaction parameter, Prandtl number, Schmidt number, thermal Grashof number, mass Grashof number, and time. The skin friction, Nusselt number, and Sherwood number are also obtained and presented in graphs. It is observed that in presence of as well as increase in chemical reaction the flow velocity decreases. Also, in presence of destructive chemical reaction the concentration profile and Sherwood number tend to the steady state at large time.
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    Design and Analysis of High-Performance Smart Card with HF/UHF Dual-Band RFID Tag and Memory Functions (2013)
    Hindawi
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    Publication Date: 2013-09-30
    Description: In this paper, we introduce a novel design of high-performance smart card with HF/UHF dual-band RFID tag to overcome frequency interference problem. Firstly, we have designed and tested a UHF RFID tag using a simulation software system. In the smart card hardware design stage, we connect a HF antenna and a UHF antenna and place them in one inlay sheet. Using a spectrum analyzer, we systematically adjust the antenna pattern to detect the optimal patterns that fit the impedance of the RFID chip. We evaluate the performance of the resulting smart card with standard RFID testers. The experiments show that our proposed RFID tag outperforms other dual-band RFID tags and maintains itself in a reasonable size. Moreover, we increase IC chip's memory capacity to resolve security-related problems when RFID tags are used in a financial transaction. We firstly exploit an IC contact protruded from the card to add an additional memory, and we integrate functions of the RFID tag to use the equipped memory through the induced current of the contact. The implemented prototype of our proposal can accommodate an extended memory ranging from one gigabyte up to four gigabytes.
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    Handing Optimization Energy Consumption in Heterogeneous Wireless Sensor Networks (2013)
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    Publication Date: 2013-09-30
    Description: This paper presents an integer linear programming model devoted to optimize the energy consumption efficiency in heterogeneous wireless sensor networks. This model is based upon a schedule of sensor allocation plans in multiple time intervals subject to coverage and connectivity constraints. By turning off specifics sets of redundant sensors in each time interval, it is possible to reduce the total energy consumption in the network and, at the same time, avoid partitioning the whole network by losing some strategic sensors too prematurely. Since the network is heterogeneous, sensors can sense different phenomena from different demand points, with different sample rates. By resorting to this model, it is possible to provide extra lifetime to heterogeneous wireless sensor networks, reducing their setup and maintenance costs. This is an important issue to be considered when deploying sensor devices in hostile and inaccessible environments.
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    Dye-Sensitized Solar Cell Based on Polyaniline/Multiwalled Carbon Nanotubes Counter Electrode (2013)
    Hindawi
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    Publication Date: 2013-09-30
    Description: This work presented the successful fabrication of dye-sensitized solar cell using polyaniline base (EB), multiwalled carbon nanotubes (MWCNTs), organic dye (rhodamine B or riboflavin), zinc oxide (ZnO), and indium tin oxide (ITO). The electrical properties of the resultant devices were investigated by measuring the current density voltage (-), capacitance voltage (-), and impedance measurements under both dark and illuminated conditions. The photovoltaic cell characteristics, that is, open circuit voltage (), short circuit current density (), and energy conversion efficiency (), were evaluated under illumination and were found to be 0.48 mA/cm2, 400 mV, and 0.224%, respectively, for ITO/EB-MWCNTs/ZnO-rhodamine B/ITO heterostructure. Using impedance spectra, it was found that the series resistances of this type of solar cell are 62 and 60 Ω under darkness and illumination, respectively.
    Print ISSN: 1110-662X
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    Topics: Electrical Engineering, Measurement and Control Technology , Energy, Environment Protection, Nuclear Power Engineering
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    Application of Baro-Altimeter Sensor in Emergency Positioning and Navigation Based on Compass GEO Satellites (2013)
    Hindawi
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    Publication Date: 2013-09-30
    Description: Frame synchronization time of geostationary Earth orbit (GEO) satellites is faster than that of incline geosynchronous satellite orbit and medium Earth orbit satellites in Beidou navigation satellite system (BDS). So time to first fix can be reduced greatly with GEO satellites (GEOs) to provide emergency positioning service during the cold start process. Meanwhile, GEOs can also be utilized to provide radio determination satellite services. Therefore, it is meaningful to research the emergency positioning algorithm based on GEOs. However, due to the poor geometry of the GEOs, the availability and accuracy degrade distinctly. To solve this problem, a low-cost high resolution MS5534B barometric (baro-) module is applied to BDS. Firstly, the principle of emergency positioning based on a baro-altimeter sensor and its performance such as the accuracy are elaborated. Then the effects of baro-altimeter sensor measurement error on positioning are analyzed. Finally, after analyzing the limitation of the conventional algorithms, a new high-accuracy emergency positioning algorithm with baro-altimeter sensor aiding is proposed, which is not limited by the integration and user’s altitude. In comparison to the conventional algorithms, the stimulant and experimental results validate the effectiveness, robustness, and higher performance of the proposed algorithms incorporated with sensors.
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    A Novel Segmented Modeling Method of Via including the Effect of Power/Ground Plane Pair (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: This paper focuses on the modeling method of common interconnects which act as coupling channels in the analysis of PCB immunity. Fast modeling and parameters extraction of power/ground plane pair are realized using cavity resonance method. The calculated results of the model match with the simulation results of HFSS within 9 GHz, which demonstrates the effectiveness of the modeling method. Besides, segmented via modeling method including the effect of power/ground plane pair is proposed. In this modeling method, via structure is decomposed into three parts, and each part is modeled, respectively. The modeling of single via and differential vias in single plane pair and multilayer is completed using this method. High accuracy is reached due to the adoption of the effect of power/ground plane pair and the adoption of second-order circuit model of capacitance and inductance, where the parameters can be gotten from analytic formulas. Finally, considering an actual signal network, for example, the equivalent circuit model of the network, is established, and every part of the equivalent circuit model is imported into Designer for cosimulation. The results are consistent with the simulation results of HFSS within 9 GHz.
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    Broadband Multilayered Array Antenna with EBG Reflector (2013)
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    Publication Date: 2013-10-01
    Description: Most broadband microstrip antennae are implemented in the form of slot structure or laminate structure. The impedance bandwidth is broadened, but meanwhile, the sidelobe of the directivity pattern and backlobe level are enlarged. A broadband stacked slot coupling microstrip antenna array with EBG structure reflector is proposed. Test results indicate that the proposed reflector structure can effectively improve the directivity pattern of stacked antenna and aperture coupled antenna, promote the front-to-back ratio, and reduce the thickness of the antenna. Therefore, it is more suitable to be applied as an airborne antenna.
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    Examination of Perovskite Structure CaMnO3-δ with MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: Perovskite structure oxygen carriers with the general formula CaMnxMg1-xO3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH4 to CO2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO3-δ. The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO3-δ have no thermodynamic limitations for methane oxidation to CO2 and H2O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work.
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    A Betweenness Calibration Topology Optimal Control Algorithm for Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: In self-organized wireless sensor networks (WSNs), any two sensor nodes can connect if they are placed in each other's communication range. Therefore, the physical topology of WSNs is usually a strongly connected topology. Sensor nodes should frequently receive and process data from their large number of neighbors, which will consume great amounts of energy. Shocking wireless channel collision also causes low throughput and high loss packets ratio during data transmission. To improve the transmission performance and save scarce energy, a logical topology generating from the physical one is necessary for the self-organized WSNs. Based on the complex network theory, this paper proposed a novel betweenness addition edges expansion algorithm (BAEE). With betweenness calibration, BAEE algorithm expanded the minimum-cost edges to optimize the network topology. Two performance metrics-connectivity functions, robustness function and efficiency function , were utilized to evaluate the network capability of the robustness and invulnerability. is the parameter to measure the topology connectivity, and is the parameter to evaluate the network exchanging information capability. Based on the simulation under various random failures and intentional attack scenarios, BAEE can effectively optimize WSNs' topology and improve the network's robust connectivity and extremely efficient exchanging information capability.
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    MFT-MAC: A Duty-Cycle MAC Protocol Using Multiframe Transmission for Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-10-01
    Description: In many sensor network applications, energy efficiency and latency are major design criteria because battery-operated sensor nodes limit network lifetime. In this paper, we propose a new contention-based duty-cycle MAC protocol using a synchronized approach for use in wireless sensor networks. In the proposed MFT-MAC protocol, we use a control frame that considers the number of DATA frames to be transmitted to the next node in order to improve the energy efficiency and reduce the end-to-end delay. During the SLEEP period, each node transmits multiple DATA frames to the next node through the use of the control frame. The performance of the proposed MAC protocol is confirmed through the use of NS-2 simulator.
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    A Dopamine Sensor Based on Pre-Concentration by Magnetic Nanoparticles (2013)
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    Publication Date: 2013-10-01
    Description: Herein, Fe3O4 magnetic nanoparticles (MNPs) were synthesized and characterized. Afterward, a magnetic carbon paste electrode (MCPE) was modified with MNPs via casting and drying MNPs on top of the MCPE (MCPE/MNP). Electrochemical behavior of the MCPE/MNP was studied by cyclic voltammetry in the presence of [Fe(CN)6]3−/4− as a redox probe, and surface of MNPs was evaluated as . The behavior of MCPE/MNP towards dopamine (DA) and ascorbic acid (AA) has been investigated by electrochemical methods, and the obtained results showed that the MCPE/MNP has adsorption behavior towards only DA. Based on this behavior, the DA molecules were pre-concentrated on top of the MCPE/MNP and followed with stripping in DA free solution. Subsequent to experimental and instrumental optimization, a calibration curve from to  M DA with , DL =  M DA, and RSD = 4.6%, was obtained in the presence of  M AA. Performance of the MCPE/MNP was successfully tested in a pharmaceutical sample.
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    Security Analysis of Scalable Block Cipher PP-1 Applicable to Distributed Sensor Networks (2013)
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    Publication Date: 2013-10-02
    Description: PP-1 is a scalable block cipher which can be implemented on a platform with limited resource. In this paper, we analyze the security of PP-1 by using truncated differential cryptanalysis. As concrete examples, we consider four versions of PP-1, PP-1/64, PP-1/128, PP-1/192, and PP-1/256. Our attack is applicable to full-round versions of them, respectively. The proposed attacks can recover a secret key of PP-1 with the computational complexity which is faster than the exhaustive search. These are the first known cryptanalytic results on PP-1.
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    Suppression of Repeat-Intensive False Targets Based on Temporal Pulse Diversity (2013)
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    Publication Date: 2013-10-02
    Description: This paper considers the problem of suppressing the repeat-intensive false targets produced by a deception electronic attack (EA) system equipped with a Digital Radio Frequency Memory (DRFM) device. Different from a conventional repeat jammer, this type of jamming intensively retransmits the intercepted signal stored in a DRFM to the victim radar in a very short time-delay interval relative to a radar pulse wide. A multipeak matched-filtering output is then produced other than the merely expected true target. An electronic protection (EP) algorithm based on the space time block code (STBC) is proposed to suppress the adverse effects of this jammer. By transmitting a pulse sequence generated from the STBC in succession and the following cancellation process applied upon the received signal, this algorithm performs successfully in a single antenna system provided that the target models are nonfluctuating or slow fluctuating and the pulse repetition frequency (PRF) is comparatively high. The performance in white and correlated Gaussian disturbance is evaluated by means of Monte Carlo simulations.
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    A Microseismic/Acoustic Emission Source Location Method Using Arrival Times of PS Waves for Unknown Velocity System (2013)
    Hindawi
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    Publication Date: 2013-10-04
    Description: To eliminate the location error of MS/AE (microseismic/acoustic emission) monitoring systems caused by the measurement deviations of the wave velocity, a MS/AE source location method using P-wave and S-wave arrivals for unknown velocity system (PSAFUVS) was developed. Arrival times of P-wave and S-wave were used to calculate and fit the MS/AE source location. The proposed method was validated by numerical experimentations. Results show that the proposed method without the need for a premeasured wave velocity has a reasonable and reliable precision. Effects of arrival errors on location accuracy were investigated, and it shows location errors enlarged rapidity with the increase of arrival errors. It is demonstrated the proposed method can not only locate the MS/AE source for unknown velocity system but also determine the real time PS waves velocities for each event in rockmass.
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    Low Mismatch Key Agreement Based on Wavelet-Transform Trend and Fuzzy Vault in Body Area Network (2013)
    Hindawi
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    Publication Date: 2013-06-07
    Description: Body area network (BAN) is an emerging branch of wireless sensor networks for personalized applications in many fields, such as health monitoring. The services in BAN usually have a high requirement on security, especially for the medical diagnosis, which involves private information. With limitations of power and computation capabilities, one of the main challenges to ensure security in BAN is how to generate or distribute a shared key between nodes for lightweight symmetric cryptography. The current research almost exploits the randomness and distinctiveness (characteristics) of physiological signals to solve the key generation problem. However, it needs the help of additional hardware support and has the constraint on positions deployment, to acquire vital signals, which will bring the high cost and hardness to implementation of real system. To avoid the above problems, this paper presents a novel key generation scheme and a key distribution protocol, both of which are only based on wireless modules equipped on sensors. By exploiting the high correlation of received signal strength index (RSSI) between peer-to-peer communications, our scheme can provide a shared symmetric cryptographic key under the presence of an eavesdropper. We conduct experiments on the real Telosb nodes, and the results demonstrate that our proposed methods have a good performance on security.
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    How Much Delay Has to Be Tolerated in a Mobile Social Network? (2013)
    Hindawi
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    Publication Date: 2013-06-10
    Description: Message delivery in a mobile social network (MSN) is difficult due to the fact that the topology of such network is sparse and unstable. Various routing schemes for MSNs were proposed to make the message delivery robust and efficient. However, little research has been conducted to explore how much delay has to be tolerated for the message delivery from the source to the destination. Since the social relationships among nodes are stable during a certain period of time, it is expected that the delay of message delivery in MSNs could be modeled with a probability model. In this paper, we take the first step to address this issue. We firstly extract three routing models from the existing routing schemes for MSNs and then develop the probability models of the message transmission delay for each abstract routing model. The simulation results show that the theoretical models match very well the simulation trace statistics.
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    Characterization of Natural Dye Extracted from Wormwood and Purple Cabbage for Dye-Sensitized Solar Cells (2013)
    Hindawi
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    Publication Date: 2013-06-10
    Description: This study used natural dyes as sensitizers of dye-sensitized solar cells (DSSCs) to replace expensive chemical synthetic dyes. We prepared two natural dyes, chlorophyll dye and anthocyanin dye, by extracting them from wormwood and purple cabbage, respectively. Moreover, we mixed the prepared chlorophyll dye and anthocyanin dye at 5 different volume ratios to form cocktail dyes. For preparation of photoelectrode, P25 TiO2 nanoparticles were used to prepare paste, which was coated on fluorine-doped tin oxide (FTO) conductive glass by the spin coating method at different spin coating speeds in order to form TiO2 thin films with different thicknesses. The DSSC prepared by the cocktail dye achieves photoelectric conversion efficiency (η) of 1.95%, open-circuit voltage () of 0.765 V, and short-circuit current density () of 5.83 mA/cm2. Moreover, the prepared DSSC sensitized solely by chlorophyll extract of wormwood achieved a photoelectric conversion efficiency (η) of 0.9%, whereas the DSSC sensitized solely by anthocyanin extract of purple cabbage achieved a photoelectric conversion efficiency of 1.47%, achieving the longest lifetime of electrons amongst these three dyes.
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    Hilbert-Curve Based Data Aggregation Scheme to Enforce Data Privacy and Data Integrity for Wireless Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-06-13
    Description: Data aggregation techniques have been proposed for wireless sensor networks (WSNs) to address the problems presented by the limited resources of sensor nodes. The provision of efficient data aggregation to preserve data privacy is a challenging issue in WSNs. Some existing data aggregation methods for preserving data privacy are CPDA, SMART, the Twin-Key based method, and GP2S. These methods, however, have two limitations. First, the communication cost for network construction is considerably high. Second, they do not support data integrity. There are two methods for supporting data integrity, iCPDA and iPDA. But they have high communication cost due to additional integrity checking messages. To resolve this problem, we propose a novel Hilbert-curve based data aggregation scheme that enforces data privacy and data integrity for WSNs. To minimize communication cost, we utilize a tree-based network structure for constructing networks and aggregating data. To preserve data privacy, we make use of both a seed exchange algorithm and Hilbert-curve based data encryption. To support data integrity, we use an integrity checking algorithm based on the PIR technique by directly communicating between parent and child nodes. Finally, through a performance analysis, we show that our scheme outperforms the existing methods in terms of both energy efficiency and privacy preservation.
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    Multiple Harmonics Fitting Algorithms Applied to Periodic Signals Based on Hilbert-Huang Transform (2013)
    Hindawi
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    Publication Date: 2013-06-07
    Description: A new generation of multipurpose measurement equipment is transforming the role of computers in instrumentation. The new features involve mixed devices, such as kinds of sensors, analog-to-digital and digital-to-analog converters, and digital signal processing techniques, that are able to substitute typical discrete instruments like multimeters and analyzers. Signal-processing applications frequently use least-squares (LS) sine-fitting algorithms. Periodic signals may be interpreted as a sum of sine waves with multiple frequencies: the Fourier series. This paper describes a new sine fitting algorithm that is able to fit a multiharmonic acquired periodic signal. By means of a “sinusoidal wave” whose amplitude and phase are both transient, the “triangular wave” can be reconstructed on the basis of Hilbert-Huang transform (HHT). This method can be used to test effective number of bits (ENOBs) of analog-to-digital converter (ADC), avoiding the trouble of selecting initial value of the parameters and working out the nonlinear equations. The simulation results show that the algorithm is precise and efficient. In the case of enough sampling points, even under the circumstances of low-resolution signal with the harmonic distortion existing, the root mean square (RMS) error between the sampling data of original “triangular wave” and the corresponding points of fitting “sinusoidal wave” is marvelously small. That maybe means, under the circumstances of any periodic signal, that ENOBs of high-resolution ADC can be tested accurately.
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    Wireless Sensor Networks and the Internet of Things (2013)
    Hindawi
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    Publication Date: 2013-06-11
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    Design of Multilayer Dielectric Cover to Enhance Gain and Efficiency of Slot Arrays (2013)
    Hindawi
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    Publication Date: 2013-06-11
    Description: An effective design procedure, based on the Elliot synthesis method, is proposed to investigate the properties of waveguide slot arrays with multilayer dielectric cover. Then, the features of the designed arrays are analyzed by means of a FEM commercial software, namely, Ansys HFSS 13. We show how a proper choice of the dielectric cover configuration allows increasing the array gain and aperture efficiency, while taking advantage of the properties of the radome structure, in terms of insulation, protection, and pressurization of the radiating waveguides. Therefore, a significant outcome of the optimal choice of the multilayer dielectric cover is the reduction of the number of slots with respect to an array radiating into free space with the same gain and efficiency, with a consequent reduction of the production cost.
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    A Secret Sharing-Based Key Management in Hierarchical Wireless Sensor Network (2013)
    Hindawi
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    Publication Date: 2013-06-07
    Description: Wireless sensor networks (WSNs) are subject to various attacks because of the vulnerable environment, limited recourse, and open communication channel. To protect WSNs, in this paper, we present a Secret sharing-based key management (SSKM). SSKM utilizes the advantages of hierarchical architecture and adopts two-level key management and authentication mechanism, which can efficiently protect the allover network communication security and survivability. Different from previous works, the SSKM distributes keys based on secret sharing mechanism by the clustered architecture, which not only localizes the key things but also keeps scalability. The SSKM provides various session keys, the network key for base station (BS) and cluster heads (CHs); the cluster key between the cluster head and member nodes. The SSKM dynamically generates different keys based on different polynomials from BS in different periods which can protect the network from the compromised nodes and reduce the high probability of the common keys. The security analysis shows that the SSKM can prevent several attacks effectively and reduce the energy consumption.
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    APP: An Ultralightweight Scheme to Authenticate ONS and Protect EPC Privacy without Cryptography in EPCglobal Networks (2013)
    Hindawi
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    Publication Date: 2013-06-10
    Description: EPCglobal network is used to share product data between trading partners, which was proposed by EPCglobal. Object Name Service (ONS) in EPCglobal framework raises two critical security risks: the authenticity of IP addresses for Physical Markup Language (PML) servers and the privacy of Electronic Product Codes (EPCs). Existing work considers either the IP address authentication or the EPC privacy. In addition, that work mainly relies on cryptographic tools, in which key distribution is not a trivial task and also causes a large amount of computation overhead. In this paper, we make the first attempt to solve those two security risks together without relying cryptography. We propose a scheme, namely, APP (authenticate ONS and protect EPC privacy), to guarantee the authenticity of IP addresses for PML servers as well as EPC privacy and to maintain ultralightweight computation cost. Moreover, we give formal definition of the authenticity and the privacy in ONS context. The security achievements are strictly analyzed and proved. The extensive analysis results justify the applicability of the proposed scheme.
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    On the Security of Certificateless Signature Schemes (2013)
    Hindawi
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    Publication Date: 2013-06-10
    Description: Wireless Sensor Network (WSN) has proved its presence in various real time applications and hence the security of such embedded devices is a vital issue. Certificateless cryptography is one of the recent paradigms to provide security. Certificateless public key cryptography (CL-PKC) deals effectively with the twin issues of certificate management in traditional public key cryptography and key escrow problem in identity-based cryptography. CL-PKC has attracted special attention in the field of information security as it has opened new avenues for improvement in the present security architecture. Recently, Tsai et al. proposed an improved certificateless signature scheme without pairing and claimed that their new construction is secure against different kinds of attacks. In this paper, we present a security analysis of their scheme and our results show that scheme does not have resistance against malicious-KGC attack. In addition, we have found some security flaws in the certificateless signature scheme of Fan et al. and proved the scheme vulnerable to Strong Type I attack.
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    Performance Analysis of a Two-Hop MIMO Mobile-to-Mobile via Stratospheric-Relay Link Employing Hierarchical Modulation (2013)
    Hindawi
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    Publication Date: 2013-06-13
    Description: Next generation wireless communication networks intend to take advantage of the integration of terrestrial and aerospace infrastructures. Besides, multiple-input multiple-output (MIMO) architecture is the key technology, which has brought the wireless gigabit vision closer to reality. In this direction, high-altitude platforms (HAPs) could act as relay stations in the stratosphere transferring information from an uplink to a downlink MIMO channel. This paper investigates the performance of a novel transmission scheme for the delivery of mobile-to-mobile (M-to-M) services via a stratospheric relay. It is assumed that the source, relay, and destination nodes are equipped with multiple antennas and that amplify-and-forward (AF) relaying is adopted. The performance is analyzed through rigorous simulations in terms of the bit-error rate (BER) by using a recently proposed 3D geometry-based reference model in spatially correlated flat-fading MIMO channels, employing a hierarchical broadcast technique and minimum mean square error (MMSE) receivers.
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    Investigation of Influential Parameters in Deep Oxidative Desulfurization of Dibenzothiophene with Hydrogen Peroxide and Formic Acid (2013)
    Hindawi
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    Publication Date: 2013-06-13
    Description: An effective oxidative system consisting of hydrogen peroxide, formic acid, and sulfuric acid followed by an extractive stage were implemented to remove dibenzothiophene in the simulated fuel oil. The results revealed such a great performance in the case of H2O2 in the presence of formic and sulfuric acids that led to the removal of sulfur compounds. Sulfuric acid was employed to increase the acidity of media as well as catalytic activity together with formic acid. The oxidation reaction was followed by a liquid-liquid extraction stage using acetonitrile as a polar solvent to remove produced sulfones from the model fuel. The impact of operating parameters including the molar ratio of formic acid to sulfur (), hydrogen peroxide to sulfur (), and the time of reaction was investigated using Box-Behnken experimental design for oxidation of the model fuel. A significant quadratic model was introduced for the sulfur removal as a function of effective parameters by the statistic analysis.
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    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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    A Reconfigurable Triple-Notch-Band Antenna Integrated with Defected Microstrip Structure Band-Stop Filter for Ultra-Wideband Cognitive Radio Applications (2013)
    Hindawi
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    Publication Date: 2013-06-13
    Description: A printed reconfigurable ultra-wideband (UWB) monopole antenna with triple narrow band-notched characteristics is proposed for cognitive radio applications in this paper. The triple narrow band-notched frequencies are obtained using a defected microstrip structure (DMS) band stop filter (BSF) embedded in the microstrip feed line and an inverted π-shaped slot etched in the rectangular radiation patch, respectively. Reconfigurable characteristics of the proposed cognitive radio antenna (CRA) are achieved by means of four ideal switches integrated on the DMS-BSF and the inverted π-shaped slot. The proposed UWB CRA can work at eight modes by controlling switches ON and OFF. Moreover, impedance bandwidth, design procedures, and radiation patterns are presented for analysis and explanation of this antenna. The designed antenna operates over the frequency band between 3.1 GHz and 14 GHz (bandwidth of 127.5%), with three notched bands from 4.2 GHz to 6.2 GHz (38.5%), 6.6 GHz to 7.0 GHz (6%), and 12.2 GHz to 14 GHz (13.7%). The antenna is successfully simulated, fabricated, and measured. The results show that it has wide impedance bandwidth, multimodes characteristics, stable gain, and omnidirectional radiation patterns.
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    A Compact Microstrip Spiral Antenna Embedded in Water Bolus for Hyperthermia Applications (2013)
    Hindawi
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    Publication Date: 2013-04-10
    Description: This paper presents the design, simulation, fabrication, and measurement of a circular spiral microstrip antenna embedded in distilled water bolus. The antenna is mainly designed to operate at 434 MHz ISM band to be used for a hyperthermia applicator. The performance of the antenna is compared to a conventional patch antenna also embedded in water bolus. The results show that spiral antenna has significant narrower radiation pattern and is capable to operate at multiple frequencies as well. Narrow beam of the antenna is desired to design a multiantenna arrangement with less coupling and a better focusing resolution which can be crucial for deep regional hyperthermia applications. The option of other frequencies is desirable to have a better control over the penetration depth versus focusing depending on the application region.
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    Energy-Efficiency of Cooperative Communication with Guaranteed E2E Reliability in WSNs (2013)
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    Publication Date: 2013-04-10
    Description: This paper addresses the energy efficiency of cooperative communication in WSN. We first establish the energy model of single-hop WSN. It is found that the cooperative communication is more suitable for harsh transmission environment with long-haul distance. The energy consumption per bit is numerically minimized by finding the optimal broadcasting BER and the number of cooperative nodes. Then, we expand the conclusion to the multihop scenario where “energy hole” dominates the longevity of WSN. To mitigate the energy consumption in the hotspots, as well as to keep the promised reliability, we adjust the transmission BER of the clusters according to the hops between the sink and cluster. On one hand, the statistical reliability is met. On the other hand, the energy consumed is converted from the nearer cluster (from the sink) to the farther ones. The network lifetime is thus optimized.
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    Traffic Priority and Load Adaptive MAC Protocol for QoS Provisioning in Body Sensor Networks (2013)
    Hindawi
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    Publication Date: 2013-03-22
    Description: Body sensor networks (BSNs) carry heterogeneous traffic types having diverse QoS requirements, such as delay, reliability and throughput. In this paper, we design a priority-based traffic load adaptive medium access control (MAC) protocol for BSNs, namely, PLA-MAC, which addresses the aforementioned requirements and maintains efficiency in power consumption. In PLA-MAC, we classify sensed data packets according to their QoS requirements and accordingly calculate their priorities. The transmission schedules of the packets are determined based on their priorities. Also, the superframe structure of the proposed protocol varies depending on the amount of traffic load and thereby ensures minimal power consumption. Our performance evaluation shows that the PLA-MAC achieves significant improvements over the state-of-the-art protocols.
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    Synthesis of Nanostructured Anatase Mesoporous Membranes with Photocatalytic and Separation Capabilities for Water Ultrafiltration Process (2013)
    Hindawi
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    Publication Date: 2013-03-22
    Description: In this work, the nanostructured anatase mesoporous membranes were prepared for water ultrafiltration (UF) process with photocatalytic and physical separation capabilities. A macroporous substrate was synthesized from α-Al2O3, then a colloidal titania sol was used for the preparation of the intermediate layer. Also, the membrane top layer was synthesized by deposition and calcination of titania polymeric sol on the intermediate layer. The characterization was performed by DLS, TG-DTA, XRD, BET, FESEM, TEM, and AFM techniques. Also, the filtration experiments were carried out based on separation of methyl orange from aqueous solution by a membrane setup with a dead-end filtration cell. Photocatalytic activity of the membranes was evaluated by methyl orange photodegradation using UV-visible spectrophotometer. The mean particle size of the colloidal and polymeric sols was 14 and 1.5 nm, respectively. The anatase membranes exhibited homogeneity, with the surface area of 32.8 m2/g, the mean pore size of 8.17 nm, and the crystallite size of 9.6 nm. The methyl orange removal efficiency by the mesoporous membrane based on physical separation was determined to be 52% that was improved up to 83% by a coupling photocatalytic technique. Thus, the UF membrane showed a high potential due to its multifunctional capability for water purification applications.
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    OPCPP: An Online Plug-Configure-Play Experiment Platform for WSN (2013)
    Hindawi
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    Publication Date: 2013-04-03
    Description: Wireless sensor network (WSN) experiment platforms are used for teaching, research, and development of WSN. However, existing WSN experiment platforms generally have the following disadvantages: tedious manual operations, invasive measurement method, poor sensor self-awareness, and low resource utilization rate. To address the above problems, this paper proposes OPCPP, an online Plug-Configure-Play experiment platform for WSN. It has four prominent strongpoints: in-application programming in batch, noninvasive measurement method, sensor self-awareness, and remote operation. OPCPP has been used in eight colleges in China for teaching course of “internet of things” till now. We also develop a sensor-aware ZigBee-based smart home system prototype based on OPCPP.
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    Novel MAC Protocol and Middleware Designs for Wearable Sensor-Based Systems for Health Monitoring (2013)
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    Publication Date: 2013-04-10
    Description: We propose a middleware platform built on wireless USB (WUSB) over wireless body area networks (WBAN) hierarchical protocol for wearable health-monitoring systems (WHMS). The proposed middleware platform is composed of time-synchronization and localization solutions. It is executed on the basis of WUSB over WBAN protocol at each wearable sensor node comprising the WHMS. In the platform, firstly, the time-synchronization middleware is executed. After that, a WHMS host calculates the location of a receiving sensor node by using the difference between the times at which the sensor node received different WBAN beacon frames sent from the WHMS host. The WHMS host interprets the status and motion of the wearable body-sensor objects.
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    Selected Papers from “The 6th China Conference of Wireless Sensor Networks” (2013)
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    Publication Date: 2013-04-08
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    Ultrasonic Sensor-Based Personalized Multichannel Audio Rendering for Multiview Broadcasting Services (2013)
    Hindawi
    Details
    Publication Date: 2013-04-09
    Description: An ultrasonic sensor-based personalized multichannel audio rendering method is proposed for multiview broadcasting services. Multiview broadcasting, a representative next-generation broadcasting technique, renders video image sequences captured by several stereoscopic cameras from different viewpoints. To achieve realistic multiview broadcasting, multichannel audio that is synchronized with a user’s viewpoint should be rendered in real time. For this reason, both a real-time person-tracking technique for estimating the user’s position and a multichannel audio rendering technique for virtual sound localization are necessary in order to provide realistic audio. Therefore, the proposed method is composed of two parts: a person-tracking method using ultrasonic sensors and a multichannel audio rendering method using MPEG Surround parameters. In order to evaluate the perceptual quality and localization performance of the proposed method, a MUSHRA listening test is conducted, and the directivity patterns are investigated. It is shown from these experiments that the proposed method provides better perceptual quality and localization performance than a conventional multichannel audio rendering method that also uses MPEG Surround parameters.
    Print ISSN: 1550-1329
    Electronic ISSN: 1550-1477
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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    Modified Dual-Band Stacked Circularly Polarized Microstrip Antenna (2013)
    Hindawi
    Details
    Publication Date: 2013-04-09
    Description: A novel high-performance circularly polarized (CP) antenna is proposed in this paper. Two separate antennas featuring the global positioning system (GPS) dual-band operation (1.575 GHz and 1.227 GHz for L1 band and L2 band, resp.) are integrated with good isolation. To enhance the gain at low angle, a new structure of patch and two parasitic metal elements are introduced. With the optimized design, good axial ratio and near-hemispherical radiation pattern are obtained.
    Print ISSN: 1687-5869
    Electronic ISSN: 1687-5877
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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    Metamaterials (2013)
    Hindawi
    Details
    Publication Date: 2013-03-31
    Print ISSN: 1687-5869
    Electronic ISSN: 1687-5877
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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    Balance Analysis of Microstrip-to-CPS Baluns and Its Effects on Broadband Antenna Performance (2013)
    Hindawi
    Details
    Publication Date: 2013-04-01
    Description: Amplitude and phase balances of two types of microstrip-(MS-) to-coplanar stripline (CPS) baluns have been analyzed through simulations and measurements, and their effects on broadband antenna performance are investigated. The impedance bandwidth of the balun determined by a back-to-back configuration can sometimes overestimate the balun operating bandwidth. With the conventional balun with a 180° phase delay line, it is observed that the balun balance over the operating frequencies becomes much more improved as the CPS length increases to over 0.1 . As compared with the conventional balun, the proposed MS-to-CPS balun demonstrated very wideband performance from 5 to over 20 GHz. With the proposed balun, amplitude and phase imbalances are within 1 dB and ±5°, respectively. Effects of the balun imbalance on overall broadband antenna performance are also discussed with a quasi-Yagi antenna and a narrow beamwidth tapered slot antenna (TSA).
    Print ISSN: 1687-5869
    Electronic ISSN: 1687-5877
    Topics: Electrical Engineering, Measurement and Control Technology
    Published by Hindawi
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