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  • 101
    Publikationsdatum: 2015-08-07
    Beschreibung: This paper presents a theoretical analysis for the accuracy requirements of the planar polarimetric phased array radar (PPPAR) in meteorological applications. Among many factors that contribute to the polarimetric biases, four factors are considered and analyzed in this study, namely, the polarization distortion due to the intrinsic limitation of a dual-polarized antenna element, the antenna pattern measurement error, the entire array patterns, and the imperfect horizontal and vertical channels. Two operation modes, the alternately transmitting and simultaneously receiving (ATSR) mode and the simultaneously transmitting and simultaneously receiving (STSR) mode, are discussed. For each mode, the polarimetric biases are formulated. As the STSR mode with orthogonal waveforms is similar to the ATSR mode, the analysis is mainly focused on the ATSR mode and the impacts of the bias sources on the measurement of polarimetric variables are investigated through Monte Carlo simulations. Some insights of the accuracy requirements are obtained and summarized.
    Print ISSN: 1687-5869
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 102
    Publikationsdatum: 2015-08-07
    Beschreibung: A dual circularly polarized (CP) omnidirectional antenna based on slot array in coaxial cylinder structure is presented in this paper. It is constructed by perpendicular slot pairs around and along the axis of the coaxial cylinder to realize the omnidirectional CP property, and two ports are assigned in its two sides as left hand circularly polarized (LHCP) port and right hand circularly polarized (RHCP) port, respectively. The proposed antenna achieves a bandwidth of 16.4% ranging from 5.05 to 5.95 GHz with an isolation higher than 15 dB between the two CP ports, and the return loss (RL) is higher than 10 dB within the bandwidth in both of the two ports. From the measured results, the average axial ratio (AR) of the proposed antenna in omnidirectional plane is lower than 1.5 dB.
    Print ISSN: 1687-5869
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 103
    Publikationsdatum: 2015-08-10
    Beschreibung: Construction and characterization of an inflatable mirror prototype made out of flexible polymeric membranes are being presented. Surfaces were curved by imposing a slight excess of air pressure. Lightweighted, lowcost, and commercially available materials were selected in order to produce solar concentration elements at competitive prices. In this sense, large-area, image-forming mirrors with low optical acuity were achieved by concentration purposes. Optical characterization of the mirror’s shape at a given pressure or curvature radius was done by means of a structuredlight technique with a resolution of 0.1 mm finding a conical shape acquired by the inflated mirror as the best approximation. Concentration ratio achieved for a focal length of 5068 mm was of 25.1 suns, making a promising approach for lowering initial investment costs in applications such as hot-water, parabolic dish with Stirling engines, or concentrated photovoltaic electricity generation.
    Print ISSN: 1110-662X
    Digitale ISSN: 1687-529X
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Energietechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 104
    Publikationsdatum: 2015-08-13
    Beschreibung: Existing work that schedules concurrent transmissions without collisions suffers from low channel utilization. We propose the Optimal Node Activation Multiple Access (ONAMA) protocol to achieve maximal channel spatial reuse through a distributed maximal independent set (DMIS) algorithm. To overcome DMIS’s excessive delay in finding a maximal independent set, we devise a novel technique called pipelined precomputation that decouples DMIS from data transmission. We implement ONAMA on resource-constrained TelosB motes using TinyOS. Extensive measurements on two testbeds independently attest to ONAMA’s superb performance compared to existing work: improving concurrency, throughput, and delay by a factor of 3.7, 3.0, and 5.3, respectively, while still maintaining reliability.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 105
    Publikationsdatum: 2015-08-14
    Beschreibung: This paper reports the design of a randomly deployed heterogeneous wireless sensor network (HWSN) with two types of nodes: a powerful node and an ordinary node. Powerful nodes, such as Cluster Heads (CHs), communicate directly to the data sink of the network, and ordinary nodes sense the desired information and transmit the processed data to powerful nodes. The heterogeneity of HWSNs improves the networks lifetime and coverage. This paper focuses on the design of a random network among HWSNs. In the design of a random HWSN, this paper uses algorithms based on the binary-valued versions of swarm intelligence, such as Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), and Ant Colony Optimization (ACO). The design is then considered to be an optimization problem of how many powerful and ordinary nodes will combine to minimize the network cost, while guaranteeing a desired coverage during a given period. Simulation results show the performance of each algorithm for solving the defined optimization problem.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 106
    Publikationsdatum: 2015-08-14
    Beschreibung: For shortcomings of current smart home system and power line carrier insufficient data transferring, an intelligent sensor networks system based on intelligent gateway is studied in this paper. Smart home system includes internal network, intelligent gateway, and external network. Multiple servers are designed in gateway, which start at the same time and receive various forms of data. Then data is processed for internal network format. External network includes several modes of communication such as TCP/IP, UDP, and pipe. Internal network includes ZigBee wireless and power line carrier (PLC) communication. Power line carrier protocol is improved, and it expands data transmission capacity to accommodate communication needs of modern family. Smart home system is designed as modules, such as intelligent gateway module, power line carrier communication module, ZigBee wireless communication modules, and appliance within electric equipment. Finally this system is physically designed and verified. The smart home system introduced in this paper has easily used and has strong compatibility.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 107
    Publikationsdatum: 2015-08-14
    Beschreibung: Fingerprint positioning can take advantage of existing WLAN to achieve indoor locations, which has been widely studied. We analyzed the corresponding positions distribution of similar fingerprints, and then found that the fuzzy similarity between fingerprints is the root cause of the larger errors existing. According to clusters distribution feature of corresponding positions of the similar fingerprints, we proposed a -Means+ clustering algorithm to achieve fine-grained fingerprint positioning. Due to the -Means+ algorithm failing to locate the positions of outliers, we also designed a linear sequence matching algorithm to improve the outliers positioning, and reduce the impact of fuzzy similarity. Experimental results illustrate that our algorithm can get a maximum positioning error less than 5 m, which outperforms other algorithms. Meanwhile, all the positioning errors over 4 m in our algorithm are less than 2%. The positioning accuracy has been improved significantly.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 108
    Publikationsdatum: 2015-08-14
    Beschreibung: In pertinence to the application of multidimensional scaling (MDS) methods in ranging-based positioning systems, an analysis is firstly conducted by the classical MDS algorithm. Modified MDS algorithm and subspace method are presented in localization application. We also depicted the unified framework and general solutions of MDS methods. However, the least square solutions under this framework are not optimal. Their performance is still related to selection of coordinate reference points. To address this problem, a minimum residual MDS algorithm based on particle swarm optimization (PSO) is proposed to derive a new solution for indoor robot localization under the unified framework. The result of analysis indicates that the performance of minimum residual MDS method is immune to selection of reference points. Furthermore, the localization accuracy for indoor robot has been enhanced by 41% as compared with the classical MDS algorithm.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 109
    Publikationsdatum: 2015-08-14
    Beschreibung: A chirp spread spectrum (CSS) transceiver architecture for IEEE 802.15.4a is proposed and implemented. In the transmitter, the size of the read-only memory that stores CSS signal samples for the chirp modulator is reduced by removing duplicate samples among subchirps. In the receiver, a matched filter is utilized to remove the other band noise caused by the band hopping property of CSS. A robust time synchronizer and chirp demodulator based on the matched filter are proposed. Low complexity architectures of the matched filter and biorthogonal decoder are also proposed. All of the proposed architectures are implemented in the field-programmable gate array chip and verified.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 110
    Publikationsdatum: 2015-08-14
    Beschreibung: Video transmission is a real challenge for wireless multihop networks with high packet loss rate. This paper proposes a cross layer video transmission scheme which combines the geographic routing in network layer and the short-length Luby transform (LT) codes in transport layer. We first analyze the effect of bit error rate (BER) on the retransmission load and the effect of payload length and LT symbols size on network efficiency. Then, based on the product of the link quality and the distance from destination, we design a routing metric for geographic routing. We further propose a cross layer transmission scheme, which adaptively adjusts payload length to encapsulate short-length LT encoded symbols and selects routes based on the new routing metric. The simulation results show that our cross layer scheme can decrease the decoding overhead and the packet loss rate, while improving the video transmission quality and the network efficiency.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 111
    Publikationsdatum: 2015-08-14
    Beschreibung: An efficient localization algorithm is proposed by utilizing the time difference of arrival (TDOA) without synchronization between base stations. Generally, a TDOA-based localization algorithm requires synchronization between base stations in order to improve the accuracy of localization. Hence, correlations using wideband signals or wire connections between base stations have been used to synchronize the base stations; however, these approaches result in additional operating costs. Thus, the proposed algorithm does not require synchronization between base stations. The TDOA equations are derived by continuously varying the locations of the source and the location of a base station. The number of packets necessary for localization is also reduced. The localization performance of the proposed algorithm is verified with Monte-Carlo simulations.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 112
    Publikationsdatum: 2015-08-14
    Beschreibung: In order to overcome the energy hole problem in some wireless sensor networks (WSNs), lifetime optimization algorithm with mobile sink nodes for wireless sensor networks (LOA_MSN) is proposed. In LOA_MSN, hybrid positioning algorithm of satellite positioning and RSSI positioning is proposed to save energy. Based on location information, movement path constraints, flow constraint, energy consumption constraint, link transmission constraint, and other constraints are analyzed. Network optimization model is established and decomposed into movement path selection model and lifetime optimization model with known grid movement paths. Finally, the two models are solved by distributed method. Sink nodes gather data of sensor nodes along the calculated paths. Sensor nodes select father nodes and transmit data to corresponding sink node according to local information. Simulation results show that LOA_MSN makes full use of node energy to prolong network lifetime. LOA_MSN with multiple sink nodes also reduces node energy consumption and data gathering latency. Under certain conditions, it outperforms MCP, subgradient algorithm, EASR, and GRAND.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 113
    Publikationsdatum: 2015-08-17
    Beschreibung: This paper investigates cooperative forwarding in two-dimensional highly dynamic wireless networks. Unlike traditional coordinated cooperative forwarding schemes that require a large amount of neighborhood discovery and coordination information to be exchanged before making the forwarding decision, this paper proposes an uncoordinated cooperative forwarding scheme where each node determines whether or not to forward a received packet independently based on a forwarding probability determined by its own location, the locations of the destination, and the transmitter from which it receives the packet, without the costly or even impractical neighbor discovery and coordination process. Analytical results are derived for the successful transmission probability and the expected number of forwarding nodes involved in the cooperative forwarding process. On that basis, discussions are presented on the optimal forwarding probability design that meets a predesignated successful transmission probability target using minimum number of forwarding nodes. Simulations are conducted to evaluate the performance of the proposed scheme.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 114
    Publikationsdatum: 2015-08-12
    Beschreibung: In VANETs, a clustering algorithm can be used to partition the network into smaller segments. Therefore, the clustering algorithms provide not only limited channel contention but also fair channel access within the cluster. In addition, they also increase spatial reuse in VANETs and efficient control for the network topology. The main concern in the clustering algorithm is the cluster stability. The major challenge is to elect a cluster head and to maintain the membership of member nodes in a highly dynamic and a fast-changing topology. Therefore, the major criterion for cluster formation is to form a stable cluster. In this paper, a clustering algorithm to affect organization and cooperative ADHOC MAC for cluster-based TDMA system in VANETs (ECCT) is proposed. The cooperation is used to help a cluster head update each neighbor cluster’s information which helps each cluster head to avoid collision when two clusters move into each other’s cluster’s transmission range. This efficiently utilizes a time slot. We use the lowest-ID algorithm to achieve organization. The analytical and simulated results show that not only the average number of time slots for electing a cluster head but also total number of time slots before data can be successfully transmitted is less than the existing cluster-based TDMA system and IEEE 802.11p.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 115
    Publikationsdatum: 2015-08-13
    Beschreibung: Although the uniform theory of diffraction (UTD) could be theoretically applied to arbitrarilyshaped convex objects modeled by nonuniform rational B-splines (NURBS), one of the great challenges in calculation of the UTD surface diffracted fields is the difficulty in determining the geodesic paths along which the creeping waves propagate on arbitrarilyshaped NURBS surfaces. In differential geometry, geodesic paths satisfy geodesic differential equation (GDE). Hence, in this paper, a general and efficient adaptive variable step Euler method is introduced for solving the GDE on arbitrarilyshaped NURBS surfaces. In contrast with conventional Euler method, the proposed method employs a shape factor (SF) to efficiently enhance the accuracy of tracing and extends the application of UTD for practical engineering. The validity and usefulness of the algorithm can be verified by the numerical results.
    Print ISSN: 1687-5869
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 116
    Publikationsdatum: 2015-08-13
    Beschreibung: A wideband dual-polarized antenna for WLAN, WiMAX, and LTE base station applications is presented in this paper. The proposed antenna consists of two pairs of orthogonal planar quasi-open-sleeve dipoles along the centerlines, a balanced feeding structure and a square ground plane. The planar quasi-open-sleeve dipole comprises a pair of bowtie-shaped planar dipoles with two parallel curve parasitic elements. The introduced parallel curve parasitic elements change the path of the current of the original bowtie-shaped planar dipoles at high frequencies and hence wideband characteristic is achieved. Two pairs of the planar quasi-open-sleeve dipoles placed orthogonally further broaden the bandwidth of the antenna with dual-polarization characteristics. The proposed antenna achieves a 10-dB return loss bandwidth from 2.32 to 4.03 GHz (53.9% bandwidth) using the planar quasi-open-sleeve dipole structures. The isolation between the two ports remains more than 32 dB in the whole bandwidth. Measured results show that the proposed antenna keeps the cross-polarization under −33 dB and the front-to-back ratio better than 15 dB in the operating band. The antenna has an area of 0.3λ  × 0.3λ at 2.32 GHz making it easy to be extended to an array element.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 117
    Publikationsdatum: 2015-08-14
    Beschreibung: In wired networks, monitor-based network tomography has been proved to be an effective technology for network internal state measurements. Existing wired network tomography approaches assume that the network topology is relatively static. However, the network topology of sensor networks is usually changing over time due to wireless dynamics. In this paper, we study the problem to assign a number of sensor nodes as monitors in large scale sensor networks, so that the end-to-end measurements among monitors can be used to identify hop-by-hop link metrics. We propose RoMA, a Robust Monitor Assignment, algorithm to assign monitors in large scale sensor networks with dynamically changing topology. RoMA includes two components, confidence-based robust topology generation and cost-minimized monitor assignment. We implement RoMA and evaluate its performance based on a deployed large scale sensor network. Results show that RoMA achieves high identifiability with dynamically changing topology and is able to assign monitors with minimum cost.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 118
    Publikationsdatum: 2015-08-17
    Beschreibung: Network robots provide services to users in smart spaces while being connected to ubiquitous instruments through wireless networks in ubiquitous environments. For more effective behavior planning of network robots, it is necessary to reduce the state space by recognizing a smart space as a set of spaces. This paper proposes a space classification algorithm based on automatic graph generation and naive Bayes classification. The proposed algorithm first filters spaces in order of priority using automatically generated graphs, thereby minimizing the number of tasks that need to be predefined by a human. The filtered spaces then induce the final space classification result using naive Bayes space classification. The results of experiments conducted using virtual agents in virtual environments indicate that the performance of the proposed algorithm is better than that of conventional naive Bayes space classification.
    Print ISSN: 1687-725X
    Digitale ISSN: 1687-7268
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 119
    Publikationsdatum: 2015-08-17
    Beschreibung: With the development of the Internet of Things (IoTs), various sensor networks were deployed to sense and collect data anytime and anywhere. Traditional sparse social sensor networks (SSSNs) assume that nodes are willing to help others with packet forwarding. However, real application scenarios, such as civilian SSSNs, often observe selfish behaviors. Therefore, the assumption that nodes are cooperative is not realistic in all applications. Currently, most of the existing incentive mechanisms focus on individual selfish behaviors. Little research work has addressed social selfish behavior in SSSNs. In this paper, we propose to incentivize nodes to cooperate with others by using a virtual bank mechanism. This incentive mechanism can effectively avoid individual selfish behaviors. This mechanism, however, renders unfair social distribution. That is, poverty nodes would appear in the networks and become internal threats for social SSSNs. To avoid this, we introduce the Gini coefficient to measure the inequality of the social distribution. Furthermore, by using the taxation strategy, we avoid the internal threats caused by social selfishness. To demonstrate the selfish behavior, we introduce the forwarding protocol which is based on social relations of nodes. We demonstrate the viability of our proposed methods through extensive simulation evaluations.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 120
    Publikationsdatum: 2015-08-17
    Beschreibung: Nowadays, vehicular ad hoc network (VANET) has attracted more and more attention due to its various applications to improve the road traffic safety and efficiency. So there were plenty of exploration work and merit on the intervehicle communication, routing, and data forwarding, but it is not easy to design the efficient routing and data forwarding algorithm, because it is hard to understand the dynamic evolution of its network topology due to the fast movement of the vehicles in the network. While the network evolution structure is the key to design the optimal data forwarding strategy, hence, in this paper, we will analyze the dynamic evolution of topology characteristics based on the real data collected by the GPS devices installed on vehicles and then model the network evolution by the dynamic topology characteristics. In the end, we analyze and verify the efficiency of our model by theoretical deductions and simulations, and our model will be helpful to find more efficient routing algorithm and build the more trustable simulator of VANET.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 121
    Publikationsdatum: 2015-09-11
    Beschreibung: Wave propagation along a closely spaced folded cylindrical helix (FCH) array is investigated for the purpose of designing compact array for energy transport and antenna radiation. It is found that the height of this surface wave guiding structure can be decreased from 0.24 to 0.06 by replacing the monopole element with the FCH. Both the propagation constant and the mode distribution of the dominant wave mechanism are extracted by ESPRIT algorithm, which indicates that a backward propagating surface wave is supported by the array structure. A compact backfire FCH antenna array is designed and measured based on the identified dominant wave mechanism.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 122
    Publikationsdatum: 2015-09-11
    Beschreibung: Multitag identification is one of the main advantages of the radio frequency identification (RFID) system. In the RFID system, the capture effect often happens in the real environment. When the capture effect occurs, the reader will not completely identify the tags in its scope. In many RFID applications, to get the real-time number of tags, the reader identifies the tags repeatedly. In these cases, the tag in the reader’s scope is a staying tag or an arriving tag. The reader already stores the IDs of all staying tags, so it can just verify the existence of these tags to rapidly identify them. As a result, the reader can spend the main time in recognizing arriving tags. To cope with the capture effect and identify staying tags rapidly, this paper presents a collecting collision tree protocol for RFID tag identification with capture effect (CCT). In CCT, a collecting mechanism is adopted and a lot of staying tags can be recognized in a slot. What is more, the reader can identify all tags in its range when the capture effect happens. Finally, various analysis and simulation results show that CCT outperforms the existing algorithms significantly.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 123
    Publikationsdatum: 2015-09-11
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 124
    Publikationsdatum: 2015-09-14
    Beschreibung: A new multiple antenna-aided cascaded energy and matched filter detector (MCEM) for cognitive radio networks is proposed. Our proposed scheme is equipped with multiple receive antennas employing energy efficient energy detector (ED) and reliable matched filter (MF) to mitigate the channel fading and increase the detection performance of the secondary users (SUs). Partial decisions are first made by using cascaded energy and matched filter detector (CEM) at each antenna and then the final collaborative decision is made based on those partial decisions. The probability of detection/false alarm of the proposed scheme is presented in terms of the complementary receiver operating characteristics (ROCs). The performance of MCEM scheme is explored via MATLAB simulations that implement the clear channel assessment (CCA) modules for IEEE 802.15.4. Simulation results showed that our proposed MCEM scheme improves the detection performance and is more energy efficient as compared to CEM scheme employing single antenna and other conventional schemes.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 125
    Publikationsdatum: 2015-09-15
    Beschreibung: This work presents a review on the concept of harmonic or secondary radar, where a tag or transponder is used to respond at a harmonic multiple of the incoming interrogation signal. In harmonic radar, the tag is called a harmonic transponder and the necessary frequency multiplication is implemented using a nonlinear element, such as a Schottky diode. Different applications and operating frequencies of harmonic transponders are presented, along with various tag design aspects. The designer may have to deal with certain tradeoffs during the design with respect to a number of transponder properties, and the role of these tradeoffs is also considered. Additionally, techniques usable for characterization of harmonic transponders are discussed.
    Print ISSN: 1687-5869
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 126
    Publikationsdatum: 2015-09-15
    Beschreibung: Distributed camera networks play an important role in public security surveillance. Analyzing video sequences from cameras set at different angles will provide enhanced performance for detecting abnormal events. In this paper, an abnormal detection algorithm is proposed to identify unusual events captured by multiple cameras. The visual event is summarized and represented by the histogram of the optical flow orientation descriptor, and then a multikernel strategy that takes the multiview scenes into account is proposed to improve the detection accuracy. A nonlinear one-class SVM algorithm with the constructed kernel is then trained to detect abnormal frames of video sequences. We validate and evaluate the proposed method on the video surveillance dataset PETS.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 127
    Publikationsdatum: 2015-09-15
    Beschreibung: With the development of the LEO satellite communication technology, highly dependable wireless communication and sensor data collection using LEO satellites have been getting much attention for emergency, marine research, and forest fire disaster in the remote region. The satellite system is expected to have the following features: rapid production, low cost, and fast construction of the satellite network. In this paper, a QS-CDMA uplink access technique in the LEO satellite is presented and discussed, which is focused on the local clocks using GPS 1PPS timing signals and the Doppler compensation for terminal uplink. The spreading code with length of 1023, which is used for the uplink preamble, selects the shift-m-sequence that can greatly reduce the MAI and increase the number of simultaneous access users. A novel analysis method for the accuracy of clock synchronization and a novel method for the estimation of Doppler shift and propagation delay are presented. These methods are used to guide the specific hardware implementation of the QS-CDMA LEO satellite sensor data collection system. Through simulations and experiments, it results in that this system structure can drastically reduce the complexity in implementing the acquisition in the satellite and increase the adaptability of the satellite system in different environments.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
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  • 128
    Publikationsdatum: 2015-09-16
    Beschreibung: Sidelobe level suppression is a major problem in circular array antenna (CAA) synthesis. Many conventional numerical techniques are proposed to achieve this which are time consuming and often fail to handle multimodal problems. In this paper, a method of circular array synthesis using nature inspired flower pollination algorithm (FPA) is proposed. The synthesis technique considered here adapts one and two degrees of freedom, namely, amplitude only and amplitude spacing. The effectiveness of the FPA is studied by comparing the results with genetic algorithm (GA) and uniform circular array antenna (UCAA) with uniform spacing. Also the effect of additional degree of freedom on the aperture size and the computational time is analyzed. A relative side lobe level (SLL) of −25 dB is achieved using the algorithm under both no beam scanning (0°) and beam scanning (15°) conditions for 20 and 40 elements of CAA.
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  • 129
    Publikationsdatum: 2015-09-16
    Beschreibung: The complexity of channel estimation algorithms is of critical importance in high mobility orthogonal frequency division multiplexing (OFDM) systems. To reduce the complexity of the algorithm, the existing channel estimation algorithms take advantage of the correlations between the channel coefficients. However, they do not take into account the variations of the correlations with the delay tap. In this paper, we consider the change in correlation between channel coefficients for different delay taps. By considering these variations, the number of computations needed for channel estimation can be decreased. This results in a reduction in the circuit energy. The simulation results show that the proposed scheme consumes less total energy per bit for transmission distances less than about 170 m when the mobile speed is 324 Kmph.
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  • 130
    Publikationsdatum: 2015-09-17
    Beschreibung: Sensing coverage, which is one of vital issues in the design of wireless sensor networks (WSNs), can usually interact with other performance metrics such as network connectivity and energy consumption. Whatever the metrics, the fundamental problem is to know at least how many sensor nodes are needed to maintain both sensing coverage and network connectivity. In this paper, we propose a Percolation Model on Novel Gilbert Graph (PM-NGG) to obtain the critical density at which the network can become fully covered and connected considering the similarity between the occurrence of percolation and the formation of a covered and connected network. The PM-NGG is based on directional sensor network where sensors are assigned a determined sensing direction with angular intervals varying from 0 to 2π. Furthermore, we define the sensing and communication model in directional sensor network in presence of channel randomness including deterministic path attenuation, shadow fading, and multipath fading. Besides, we discuss the coverage and connectivity together as a whole under the proposed model. It is worth mentioning that the theoretical analysis and simulation results of the relationship between critical density and transmitting power give insights into the design of directional sensor network in practice.
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  • 131
    Publikationsdatum: 2015-09-18
    Beschreibung: A wireless sensor network (WSN) with the potential to monitor and locate partial discharge (PD) in high-voltage electricity substations using only received signal strength (RSS) is proposed. The advantages of an RSS-based operating principle over more traditional methods (e.g., time-of-arrival and time-difference-of-arrival) are described. Laboratory measurements of PD that emulate the operation of a PD WSN are presented. The hardware architecture of a prototype PD WSN is described and the particular challenges of an RSS-based location approach in an environment with an unknown, and spatially varying, path-loss index are discussed. It is concluded that an RSS-based PD WSN is a plausible solution for the monitoring of insulation integrity in electricity substations.
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  • 132
    Publikationsdatum: 2015-09-18
    Beschreibung: This paper presents a novel ultrawideband (UWB) bandpass filter using stepped impedance stub loaded microstrip resonator (SISLMR). The proposed resonator is so formed to allow its four resonant frequencies in the UWB passband, which extends from 3.1 GHz to 10.6 GHz. Moreover, two spurline sections are employed to create a sharp notched-band filter for suppressing the signals of 5 GHz WLAN devices. Experimental results of the fabricated filters are in good agreement with the HFSS simulations and validate the design.
    Print ISSN: 1687-5826
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 133
    Publikationsdatum: 2015-09-18
    Beschreibung: The cross-correlation method allows phase-noise measurements of high-quality devices with very low noise levels, using reference sources with higher noise levels than the device under test. To implement this method, a phase-noise analyzer needs to compute the cross-spectral density, that is, the Fourier transform of the cross-correlation, of two time series over a wide frequency range, from fractions of Hz to tens of MHz. Furthermore, the analyzer requires a high dynamic range to accommodate the phase noise of high-quality oscillators that may fall off by more than 100 dB from close-in noise to the noise floor at large frequency offsets. This paper describes the efficient implementation of a cross-spectrum analyzer in a low-cost FPGA, as part of a modern phase-noise analyzer with very fast measurement time.
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  • 134
    Publikationsdatum: 2015-09-18
    Beschreibung: Capacity of a wireless link can be enhanced by increasing the number of receive antennas. However, imposed receiver physical size constraints necessitate that the antenna elements be in close proximity, which typically reduces the overall link capacity of the wireless channel. Counterintuitively, under certain conditions the capacity of the overall link can be enhanced by decreasing antenna spacings. The focus of this paper is that of identifying the fundamental mechanisms and the conditions that give rise to this excess capacity. Closed-form expressions that directly quantify this capacity gain are derived based on a representative circuit theoretic model. Interesting insights are developed about the impact of different noise and interference sources and the limiting effect of heat losses in the antenna system. The capacity analysis is subsequently generalized to encompass the effect of antenna current deformation and load mismatch due to mutual coupling, based on the standard Method of Moments (MoM) analysis, demonstrating similar capacity enhancement behavior as predicted by the closed-form expressions.
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  • 135
    Publikationsdatum: 2015-09-21
    Beschreibung: Fractal patch antennas based on the Sierpinski structure are studied in this paper. The antennas operate at dual bands (around 2 and 5 GHz) and are designed to steer the beam directions at around 5 GHz band (the first harmonic). The antennas use reconfigurable triple feeds on the same antenna plane to have three beam directions. The same scale factor defines the geometrical self-similarity of the Sierpinski fractal. The proposed antennas are fabricated through three iterations from 1st order to 3rd order and utilize FR-4 (εr = 4.4) for the microwave substrate. The performances of the antennas, such as reflection coefficients and radiation patterns are verified by simulation and measurement. The results show that the properties of the proposed antennas in three orders are similar.
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  • 136
    Publikationsdatum: 2015-09-21
    Beschreibung: A triband MIMO antenna used for gsm1800/td-scdma/lte/wi-max/wiLan/wifi has been proposed in this paper. The design with the size of 32 m 73.6 mm is fabricated on FR4 substrate (thickness is 1.6 mm). This antenna consists of two reversed monopole meandered radiators and defected ground structure which work together to achieve impedance match and enhance isolation for all operating bands. According to the subsequent measured results, the working frequency domains are at gsm1800 (1.71 GHz–1.88 GHz), td-scdma (1.88 GHz–2.025 GHz), lte (2.1–2.35, 2.48–2.51), wi-max (3.5 GHz, 5.5 GHz), wiLan (5.725 GHz–5.8 GHz), and wifi (5.8 GHz–5.88 GHz) approximately. Besides, the measured radiation patterns (gain total) are also well at these working frequency domains and the omnidirectional performance has been achieved for the reversed MIMO antenna array. Furthermore, the realized isolation is more than 15 dB, 24.2 dB, and 22 dB at the first, the second, and the third working frequency band, respectively.
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  • 137
    Publikationsdatum: 2015-09-21
    Beschreibung: The aims of this paper are to analyze the performance of a one-dimensional ALOHA ad hoc network and to investigate the impact of the access probability of the ALOHA protocol on the network performance. As a performance metric we consider the average number of nodes that successfully receive a packet from an arbitrary node. To mathematically model the random locations of nodes and the interference in the ad hoc network, we use stochastic geometry theory. With the help of stochastic geometry theory, we model the ad hoc network, derive an analytic form of the performance metric, and finally obtain the optimal access probability that maximizes the performance metric. Numerical examples are provided to validate our analysis and to investigate the performance behavior.
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  • 138
    Publikationsdatum: 2015-09-21
    Beschreibung: Interdigital transducers fabricated with piezopolymer film have been realized to excite ultrasonic Lamb waves in a composite laminate subjected to pure bending stresses. Lamb waves were generated and detected in a cross-ply [0°/90°] 4 mm thick carbon-fiber composite, by using two interdigital transducers in pitch-catch configuration. We demonstrate that the choice of the piezopolymer transducer technology is suitable for this type of investigation and the advantages of the proposed transducer assembly and bonding are described. A full set-up is described to determine the relationship between the time of flight of the recorded signals and the applied bending moment. Interdigital transducers were designed according to simulations of the dispersion curves, in order to operate at a central frequency of 450 kHz. This frequency corresponds to a central wavelength of 16 mm and to a group velocity of about 6000 m/s for the first symmetric guided wave mode. The variations in the time of flight of ultrasonic recorded signals were measured as a function of the variations in the bending moment. The static and dynamic load tests were in good agreement with strain gage measurements performed in the micro deformation range (0–1400 µm/m).
    Print ISSN: 1687-725X
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 139
    Publikationsdatum: 2015-09-21
    Beschreibung: The conventional methodologies used for the detection of human papillomavirus (HPV) present actually robust and reproducible advantages. However, at the same time, they involve complex protocols that sometimes are difficult to popularize. Over the first half of XX century, the adequate treatment of complex and delicate processes from a simple instrumental base seemed a fundamental and intrinsic contradiction. However, interdisciplinary trends have allowed the manipulation of tissues, proteins, and nucleic acids through innovative increasingly smaller devices. The proper diagnosis of HPV has seen great advances since biosensor researchers are employing its virus strains as models to study the interactions between the biorecognition element and the transducer. Additionally, all recent improvements and trends that material sciences, biotechnology, and data processing scientists excel for biosensors can be applied for the HPV detection platforms. In this review, we highlight the recent trends on materials, nanomaterials, and transducers for the specific detection and differentiation of HPV strains. The most influential methods for the detection and identification of these papillomaviruses include optical, electrochemical, and piezoelectric transducers; we will visit their sensibility and advantages. Additionally, we highlight the factors that contributed to the increasing importance of these biodevices as potential substitutes to conventional diagnostic methods.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 140
    Publikationsdatum: 2015-09-28
    Beschreibung: COSB-128 (Moldovyan et al., 2002) is a block cipher with 128-bit and 256-bit secret keys, which use key and data-dependent operational substitutions in fast controllable permutation blocks (CPB) concept. It is designed with a simple key schedule to ensure a high speed of data transformation by fast block encryption algorithms and expected to be high stability to all known methods of cryptanalysis, especially differential and linear attacks. In this paper, we show that the COSB-128 block cipher still remains weaknesses to differential related-key cryptanalysis, by constructing two full 10-round related-key differential characteristics (DCs) of COSB-128 with high probabilities, and thence propose our two related-key differential attacks. The attacks require about 224 data and time complexities to recover 63-bit key information and 222 data and time complexities to recover 6-bit key information. This study is the first known cryptanalytic result on COSB-128 until now. From this study, the new potential for the cryptanalysis on these types of block cipher will be further revealed.
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  • 141
    Publikationsdatum: 2015-09-28
    Beschreibung: To effectively handle duplicate files, data deduplication schemes are widely used in many storage systems. Data deduplication algorithms reduce storage space by eliminating data to ensure that only single instance of data is stored in storage device. In this paper, we propose an energy efficient file synchronization scheme that provides hybrid data chunking using variable-length chunking (VLC) and fixed-length chunking (FLC). The main idea is to analyze similarities between old and new versions of data and decide which chunking method to apply in synchronizing the files. In particular, the proposed algorithm exploits the file similarity pattern for calculating the energy efficiency of chunking algorithms. We have developed an Android mobile application for file synchronization and measured energy consumption. The experiment results show that the proposed scheme helps save energy in synchronizing files, regardless of file types or amount of redundancies the files have.
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  • 142
    Publikationsdatum: 2015-09-28
    Beschreibung: There have been efforts made to come up with a solution through advancement based on developing technological solution. However, it has come to the point where various forms of the leakage centering on people that are the subject of core asset leakage cannot be solved through technological method. At present time in which the limitation of information security that seeks technological security has been clearly revealed, there is an increasing interest in industrial security for establishing convergence security system upon understanding technological/physical/managerial security measures and establishing security strategies. Accordingly, this paper conducted an analysis on the characteristics of industrial security manpower to present a vision and systematically cultivate industrial security experts manpower for protecting core technologies of companies in intelligent sensor network. In particular, occupational cluster of industrial security experts manpower was classified, which was verified by conducting case analysis. In addition, it estimated the demand for industrial security experts manpower by substituting it to the present condition of manpower of Korea. It is expected that the result of this study will be able to be used as basic information for cultivating industrial security experts manpower in intelligent sensor network.
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  • 143
    Publikationsdatum: 2015-09-28
    Beschreibung: Many researchers in various fields are seeking solutions to such problems through political and administrative measures. However, concrete solutions have yet to be presented. Researches that seek solutions to the said problems using new technologies are increasing. In this study, a solution for changing and improving society was proposed by investigating social issue solutions and technologies centered on social organizations and systems. To do that, the types of social issues were analyzed by defining them through the analysis in the preceding studies and using a metaresearch technique. I suggested a crime prevention security system to prevent crimes in deteriorated areas. The system is integrated with the IOT, which differs from the existing manual camera.
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  • 144
    Publikationsdatum: 2015-09-28
    Beschreibung: Demand forecasting in the biomedical area is becoming more important because of radical changes in the macroeconomic environment and consumption trends. Moreover, the need for big data analysis on data from wireless sensor networks and social media is increasing because it shows not only the rapidly changing environmental data such as fine dust concentration but also the responses of potential customers that are expected to affect the demand for a medicine. Therefore, demand forecasting models based on data analysis in wireless sensor networks and topic modeling of buzzwords in blog documents were suggested in this study. First, we analyzed topics of documents from blogs that describe the symptoms of certain diseases related to selected medicines. Thereafter, we extracted topic trends for a selected period and constructed demand forecasting models that consist of topic trends, environmental data from wireless sensor networks, and time-series sales data. The experiment results show that topic trends about medicines significantly affect the performance of demand forecasting for these medicines.
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  • 145
    Publikationsdatum: 2015-09-28
    Beschreibung: Cloud computing is a new IT trend to meet the new business requirements such as business agility and operational efficiency with business process outsourcing (BPO). Sensor-Cloud infrastructure is the extended form of cloud computing to manage the sensors which are scattered throughout the network. Several benefits of adopting cloud computing including cost saving, high scalability, and business risk reductions also can be applied to sensor data collection. As a first investment for new technology, we analyze IT managers’ feedbacks to identify the most important factors of decision making for cloud platform adoption and IT outsourcing. Even though the technological motivation is persuasive in Korean IT market, survey results show that the cost efficiency is the most important for cloud platform adoption. Also surveys reveal that IT service consumers have difficulties understanding complicated service contracts and data sharing issues with infrastructure providers, which serve as main blockers of adopting cloud computing.
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  • 146
    Publikationsdatum: 2015-09-28
    Beschreibung: We present an automated verification methodology of the security events, that is, IDS alerts, based on heuristic analysis. The proposed verification methodology aims to automatically identify real cyberattacks from the security events and filter out false positive, so that the security analyst is able to conduct security monitoring and response more effectively. For the proposed verification methodology, we used the 1,528,730,667 security events that were obtained from Science and Technology Security Center (S&T-SEC). We then extracted the core security events that were caused by the real cyberattacks. Among the core security events, we selected the top 20 types of the security events in the number of the real attacks that they raised. By analyzing the top 20 types of the security events, we discovered essential elements and optional elements for using in the automated verification of the security events. The evaluation results showed that the proposed verification methodology could contribute to the reduction (about 67%) of the meaningless security events. Furthermore, we demonstrated that the proposed verification methodology contributed to the detection of 140 true negatives that were not identified by the security analyst and the total accuracy of the proposed verification methodology was 96.1%.
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  • 147
    Publikationsdatum: 2015-09-28
    Beschreibung: Voice over Internet Protocol (VoIP) is an emerging communication service that has advanced in ubiquitous computing environments. Although VoIP is inexpensive and offers additional services, there has been little provision for attacks at the weak points. With the advances of Wireless Sensor Network (WSN) technologies, the risk is increasing. Due to the resource constraints of WSN, attacks have become easier, making protection of the network more difficult. In this work, we attempt to distinguish fraud call attacks as outliers from normal calls on the basis of call detail records. We adopted and applied a Local Outlier Factor (LOF) method on real call data, which include actual fraud call attacks. Our results show the outlier detection method can be effective in detecting fraud calls. Moreover, introducing two additional attributes related to fraud call characteristics enhanced the detection performance.
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  • 148
    Publikationsdatum: 2015-09-28
    Beschreibung: We propose a method to compensate the effects of multiple carrier frequency offsets (CFOs) for orthogonal frequency division multiplexing (OFDM) systems. The multiple CFOs, we considered, are caused by several spatially separated frequency-unsynchronized transmitters as in amplify-and-forward relay communication networks or wireless ad hoc sensor networks. Despite its appealing features, OFDM is extremely sensitive to CFO, especially to multiple CFOs. At the receiver, the residual CFO which appears due to incomplete compensation of multiple CFOs destroys orthogonality among subcarriers and brings interchannel interference (ICI). In the proposed scheme, we compensate the CFOs of the received signal by the predesigned value, which results in cancellation of the opposite ICI by each other. This is based on the property that the spectrum of ICIs shown in a subcarrier has similar magnitudes and opposite signs from the fact that spectrum shapes of the ICI are of sinc function. Simulation results are shown to demonstrate the effectiveness of the proposed method.
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  • 149
    Publikationsdatum: 2015-09-28
    Beschreibung: Secure key distribution is one of the most important building blocks to ensure confidentiality in wireless sensor and actor networks (WSANs). However, the key distribution becomes a challenging task when keys have to be relayed by compromised nodes in order to establish secure communication between distant nodes. To deal with this issue, we propose in this paper a key distribution scheme, named key distribution using fragmentation and assimilation (KDFA). In this scheme, the sender node splits the actual key into fragments and sends them through intermediate actor nodes towards the receiver node. The latter assimilates these key fragments using XOR operation to reconstruct the actual key. In this case, attacker cannot retrieve the actual key and only gets the key fragment. KDFA is composed of two parts: (a) key distribution protocol (KDP) to distribute the key using intra-actor and interactor communication scenarios and (b) key fragmentation algorithm (KFA) to slice the key using binary calculations. KDFA execution has been specified and formally verified using Rubin logic. Moreover, the performance and the resilience of the proposed protocol are further analyzed through extensive simulations using ns-2.35. Results show that KDFA is resilient against actor node compromise and key exposure.
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  • 150
    Publikationsdatum: 2015-09-28
    Beschreibung: Although Internet of Things (IoT) technologies and services are being developed rapidly worldwide, concerns of potential security threats such as privacy violation, information leak, and hacking are increasing as more various sensors are connected to the Internet. There is a need for the study of introducing risk management and existing security management standard (e.g., ISO27001) to ensure the stability and reliability of IoT services. K-ISMS is a representative certification system that evaluates the security management level of the enterprise in Korea and is possible to apply as a standardized process to enhance the security management of IoT services. However, there are growing concerns about the quality deterioration of the K-ISMS certification assessment these days because of internet security incidents occurring frequently in K-ISMS certified enterprises. Therefore, various researches are required to improve the accuracy and objectivity of the certification assessment. Since existing studies mainly focus on simple statistical analysis of the K-ISMS assessment results, analysis on the cause of certification assessment fault based on past data analysis is insufficient. As a method of managing the certification inspection quality, in this paper, we analyze the association among the fault items of the K-ISMS certification assessment results using association rule mining which involves identifying an association rule among items in the database.
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  • 151
    Publikationsdatum: 2015-09-28
    Beschreibung: This study suggests a methodology called a smart ubiquitous data mining (UDM) that consolidates homogeneous models in a smart ubiquitous computing environment. It tests the suggested model with financial datasets. It basically induces rules from the dataset using diverse rule extraction algorithms and combines the rules to build a metamodel. This paper builds several personal credit rating prediction models based on the UDM and benchmarks their performance against other models which employ logistic regression (LR), Bayesian style frequency matrix (BFM), multilayer perceptron (MLP), classification tree methods (C5.0), and neural network rule extraction (NR) algorithms. To verify the feasibility and effectiveness of UDM, personal credit data and personal loan data provided by a Financial Holding Company (FHC) were used in this study. Empirical results indicated that UDM outperforms other models such as LR, BFM, MLP, C5.0, and NR.
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  • 152
    Publikationsdatum: 2015-09-28
    Beschreibung: A sensor-rich mobile video represents a new type of videos acquired from modern smart phones. During video recording, it is also recorded various amounts of sensor data collected from embedded sensors. Unlike the conventional videos acquired from proprietary capturing devices, these videos allow enriched reconstruction of their surrounding environments, while enabling users to record them handily. In this paper, we examine the robustness of existing device orientation detection method, by analyzing the motion sensor samples that are publicly available from the sensor-rich mobile video hosting website, and discuss our observation results and potential problems when computing device orientation of georeferential mobile videos.
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  • 153
    Publikationsdatum: 2015-09-28
    Beschreibung: For a hybrid sensor network, the effective coverage rate can be optimized by adjusting the location of the mobile nodes. For many deployments by APF (artificial potential field), due to the common problem of barrier effect, it is difficult for mobile nodes to diffuse by the weaker attraction when the nodes initially distribute densely in some places. The proposed deployment algorithm PFPSO (Potential Field-Directed Particle Swarm Optimization) can overcome this problem and guide the mobile nodes to the optimal positions. Normally the requirement is different for the effective coverage rate between the hotspot area and the ordinary area. On the basis of PFPSO, NPFPSO (Nonuniform PFPSO) algorithm was also proposed to implement nonuniform coverage according to the importance degree of the monitoring area. Simulation result illustrates that PFPSO algorithm can effectively improve the effective coverage rate of the network, and NPFPSO algorithm can obtain a balanced result of effective coverage rate for both hotspot area and ordinary area.
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  • 154
    Publikationsdatum: 2015-09-28
    Beschreibung: Changes in natural light in the daily cycle and monthly cycle and its seasonal changes create rhythms in bodies of living creatures including humans. The circadian rhythm connected to natural light stimulates psychological states and hormonal changes. As such, natural light is a major environmental factor that affects humans’ psychological and physiological conditions. To create healthy and comfortable lighting environments in windowless space such as a basement where no natural light can enter, the daily, monthly, and seasonal cycles of natural light need to be represented by means of artificial lightings. Upon certain situations related to purposes of space and user behaviors, lighting control technology is required for appropriate lighting environments. To this end, this study designs and implements a natural light reproduction system based on context awareness in wireless sensor networks to restructure lighting environments in adaptation to the changing situation of the occupant. As the object space in the experiment, a clothing shop to occupy the largest portion of underground space was selected. The scenarios were selected for each time period in connection with the behaviors of the seller who resided there for a long time. The suggested system’s performance was evaluated in terms of conformity with natural light, comfort, and energy-saving effect.
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  • 155
    Publikationsdatum: 2015-09-28
    Beschreibung: Web and mobile platforms have provided an environment of technical cooperation through technical development and the diffusion of related devices. Large-scale data sets have been available to analyze web interaction and data analysis. Particularly, large-scale data make us learn new patterns and insight into several research fields. For healthcare field, most chronic diseases are caused by environmental and genetic factors (Van der Laan et al., 2003). The relationship between environmental exposure and gene factors is crucial regarding disease etiology (Swift et al., 2004). For example, Tobacco is considered one of the biggest environmental factors responsible for many diseases each year. Schwartz and Collins (2007) discussed the importance of gene and environment factor correlation in human diseases. Thomas (2010) published a review of different approaches on gene-environment association studies attempting to explain some of the most complex diseases. Although previous studies have studied chronicle diseases with their causes one by one, those studies do not show integrated relationships between various diseases and their related human genes. Therefore, this study investigates the gene-disease relationships which are affected by tobacco and is able to find new association links with social network analysis and other mining techniques.
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  • 156
    Publikationsdatum: 2015-09-28
    Beschreibung: To create wide and deep knowledge flows by providing implicit and explicit knowledge services, organizations have constructed knowledge management systems (KMS). As employees are major knowledge resources in an organization, it is essential to use their collaborative intelligence in KMS, but there has been little research on how the heterogeneous networks of people interact to produce intelligent outcomes. This research suggests a new KM framework that leverages collaborative intelligence techniques, such as collaborative search, collaborative filtering, and social network analysis, as well as conventional knowledge management techniques including smart sensor technology. Finally, this paper reports our experience in a real world KMS development case that applied the framework and suggests challenges of knowledge management learned from this research.
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  • 157
    Publikationsdatum: 2015-09-28
    Beschreibung: River water quality is directly related to the wellness of its neighbors. Because the West Nakdong River has long suffered both from the infiltration of sea water and from the inflow of turbid wastewater, inconsiderate use of this water can cause disastrous result to nearby agricultural areas and neighbors. Busan city in Korea had deployed a pilot USN (ubiquitous sensor network) system that monitors this river and nearby tube wells to properly react to those situations. In this paper, we have designed a system that predicts salinity level of groundwater while monitoring the electrical conductivity (EC) values of sensors in that USN. We use a hybrid method that combines pattern-based approach together with statistical regression model to analyze sensor data. After classifying past sensor outputs into several characteristic patterns, we trace each day’s change to identify base pattern of that day and thus predict the next value of sensor output. Since the detection of each day’s pattern takes some time, we need to incorporate statistical regression model as an interim prediction method. Through an experiment that compares the hybrid model to previous statistical regression model, we have shown that our hybrid model is more accurate to predict the sensor’s movement.
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  • 158
    Publikationsdatum: 2015-09-28
    Beschreibung: An iterative approach, based on the linear sampling method (LSM) and the contrast source inversion (CSI) method, is proposed to improve the recovered images of multiple targets and targets with layered or continuous profile, including shape and distribution of electric properties. The difficulties in dealing with large targets or high contrast are partly overcome with this approach. Typical targets studied in the literatures are chosen for simulations and comparison.
    Print ISSN: 1687-5826
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 159
    Publikationsdatum: 2015-09-28
    Beschreibung: In some business applications, all kinds of cameras sensors are employed in a distributed way to capture videos for different tasks such as surveillance. Once some illegal actions happen, then somebody or some organization wants to forge or replace some surveillance video clips to destroy evidences or obtain illegal profits. How to authenticate the genuineness and integrity of the source video or trace the source of a video information leak becomes a growing requirement in these small businesses. Fortunately, video watermark just provides an effective technology to resolve this issue. This paper proposes a real-time video watermarking scheme for MPEG, where firstly exploits fast scenes segmentation to original video sequence and adaptively selects appropriate scenes to be embedded. Furthermore, visual model is utilized to modulate watermark strength. Watermarks are embedded by adjusting the number of bit1 in the bitstreams through changing level of run-level pairs. Experiment results show little loss of video quality and also exhibit excellent robustness against many attacks. As watermark is directly detected in bitstreams domain, real-time detection becomes a reality. In addition, the embedding strategy guarantees that the bit rate is not increased and the experiments also validate it.
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  • 160
    Publikationsdatum: 2015-09-28
    Beschreibung: Currently, access control is facing many issues for information protection in the ubiquitous sensor network (USN) environment. In particular, dynamic access control is a central problem where context always changes because of volatile ubiquitous sensors. The use of context is important in USN. In this paper, we focus on the context-driven privacy protection model. In context-based access control research, the access permission technique that uses context is being intensely investigated because of the ease with which various dynamic access permissions can be assigned in accordance with the various changes in context. A key feature of this approach is dynamic access control. Therefore, we propose a model for privacy preservation that is context-based dynamic access control that uses intuitive 5W1H for USN. According to this model, the access control strategy can be determined dynamically based on context elements and subject attributes, in addition to objects and operations, using access control entities; therefore, it is relatively easy to infer the dynamic access control of context expressivity both accurately and efficiently.
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  • 161
    Publikationsdatum: 2015-09-29
    Beschreibung: For network users roaming in a wireless sensor network (WSN), they can broadcast queries to WSNs to obtain the latest sensed data from sensor nodes using their mobile devices. In such a scenario, each sensor node has to verify the validity of every query sent from users. In this paper, RSA-like public key cryptography is employed to design a mechanism for multiuser broadcast authentication in WSNs. Within the proposed scheme, the use of certificates becomes optional. When users broadcast queries to WSNs, each sensor node can verify every query immediately without buffering any one. As a result, the energy cost for verifying a query by a sensor node is very small. Furthermore, our scheme provides enough scalability and security. The quantitative analyses show that our scheme is efficient in terms of storage and computational overheads.
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  • 162
    Publikationsdatum: 2015-11-23
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 163
    Publikationsdatum: 2015-11-23
    Beschreibung: As various applied sensors have been integrated into embedded devices, the Embedded Graphics Processing Unit (EGPU) has assumed more processing tasks, which requires an EGPU with higher performance. A tile-based EGPU is proposed that can be used in both general-purpose computing and 3D graphics rendering. With fused, scalable, and hierarchical parallelism architecture, the EGPU has the ability to address nearly 100 million vertices or fragments and achieves 1 GFLOPS per second at a clock frequency of 200 MHz. A fused and scalable architecture, constituted by Universal Processing Engine (UPE) and Graphics Coprocessor Cluster (GCC), ensures that the EGPU can adapt to various graphic processing scenes and situations, achieving more efficient rendering. Moreover, hierarchical parallelism is implemented via the UPE. Additionally, tiling brings a significant reduction in both system memory bandwidth and power consumption. A 0.18 µm technology library is used for timing and power analysis. The area of the proposed EGPU is 6.5 mm 6.5 mm, and its power consumption is approximately 349.318 mW. Experimental results demonstrate that the proposed EGPU can be used in a System on Chip (SoC) configuration connected to sensors to accelerate its processing and create a proper balance between performance and cost.
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  • 164
    Publikationsdatum: 2015-11-23
    Beschreibung: The following paper introduces a novel scanning method for mapping and localization purposes in mobile robotics. Our method is based on a rotating monostatic radar network, which determines the positions of objects around the scanner via a continuously running lateration algorithm. The estimation of surfaces with ultrawideband radar networks has been studied experimentally in lab environments, especially with lateration, envelopes of spheres, and SEABED algorithms. But we do not see a link to the field of mapping and localization of mobile robots, where laser scanners are dominating. Indeed, only few research groups use radars for mapping and localization, but their applied sensor principle is based on a rotating focused radar beam. Consequently, only 2D radar scanners are known inside the robotic world and methods for 3D scanning with radars need to be investigated. This paper will derive the theoretical background of the sensor principle, which is based on a radar network on a rotating joint, and discuss its erroneous influences. We were performing first scans of standard geometries and deriving a model in order to compare theoretical and experimental measurement results. Furthermore, we present first mapping approaches and a simulation of a scanner with multiple sensors.
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  • 165
    Publikationsdatum: 2015-11-23
    Beschreibung: This paper proposes a calibration technique of a stereo gamma detection camera. Calibration of the internal and external parameters of a stereo vision camera is a well-known research problem in the computer vision society. However, few or no stereo calibration has been investigated in the radiation measurement research. Since no visual information can be obtained from a stereo radiation camera, it is impossible to use a general stereo calibration algorithm directly. In this paper, we develop a hybrid-type stereo system which is equipped with both radiation and vision cameras. To calibrate the stereo radiation cameras, stereo images of a calibration pattern captured from the vision cameras are transformed in the view of the radiation cameras. The homography transformation is calibrated based on the geometric relationship between visual and radiation camera coordinates. The accuracy of the stereo parameters of the radiation camera is analyzed by distance measurements to both visual light and gamma sources. The experimental results show that the measurement error is about 3%.
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  • 166
    Publikationsdatum: 2015-11-23
    Beschreibung: Data collection from deployed sensor networks can be with static sink, ground-based mobile sink, or Unmanned Aerial Vehicle (UAV) based mobile aerial data collector. Considering the large-scale sensor networks and peculiarity of the deployed environments, aerial data collection based on controllable UAV has more advantages. In this paper, we have designed a basic framework for aerial data collection, which includes the following five components: deployment of networks, nodes positioning, anchor points searching, fast path planning for UAV, and data collection from network. We have identified the key challenges in each of them and have proposed efficient solutions. This includes proposal of a Fast Path Planning with Rules (FPPWR) algorithm based on grid division, to increase the efficiency of path planning, while guaranteeing the length of the path to be relatively short. We have designed and implemented a simulation platform for aerial data collection from sensor networks and have validated performance efficiency of the proposed framework based on the following parameters: time consumption of the aerial data collection, flight path distance, and volume of collected data.
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  • 167
    Publikationsdatum: 2015-11-24
    Beschreibung: Nowadays, a mobile phone plays an important role in daily life. There are many applications developed for mobile phones. Location service application is one kind of mobile application that serves location information. GPS receiver is embedded on a mobile phone for localization. However, GPS cannot provide localization service over indoor scenario efficiently. This is because obstacles and structures of building block GPS signal from the satellites. Many indoor localization systems have been proposed but most of them are developed over single-floor scenario only. The dimension of altitudes in localization results will be missed. In this paper, we propose floor localization system. The proposed system does not need any site survey and any support from back-end server. It has a self-learning algorithm for creating fingerprint in each floor. The self-learning algorithm utilizes sensors on the mobile phone for detecting trace of mobile phone user. This algorithm is low computation complexity, which can be operated on any mobile phones. Moreover, the mobile phone can exchange fingerprints with others via virtual ad hoc network instead of learning all floor fingerprints by themselves only. Our proposed floor localization system achieves 87% of accuracy.
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  • 168
    Publikationsdatum: 2015-11-26
    Beschreibung: An Automated Demand Response is the most fundamental energy service that contributes to balancing the power demand with the supply, in which it realizes extensive interoperations between the power consumers and the suppliers. The OpenADR specification has been developed to facilitate the service communications, and several facilities offer primitive forms of services in a retail market. However, few researches have reported the details of such a real-world service yet, and thus we are still unaware of how it works exactly. Instead, we rely on our textbooks to design next generations of the ADR service. To overcome the discrepancy of our understanding, this paper shares our hand-on experiences on the commercialized ADR service. In particular, we deploy smart submeters to manage energy loads and install an energy management system in a small commercial facility, helping the owner participate in the ADR service that a local utility offers. The building owner makes a service contract with a qualified load aggregator based on her curtailment rate, a reference point that decides the success of her load curtailment. With the rate, the customer facility participates in three DR events for tests that last for 2, 1, and 3 hours, respectively. Our experimental results are illustrated with discussions on various aspects of the service.
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  • 169
    Publikationsdatum: 2015-11-26
    Beschreibung: Wireless sensor networks are often deployed in unattended and hostile environments. Due to the resource limitations and multihop communication in WSN, selective forwarding attacks launched by compromised insider nodes are a serious threat. A trust-based scheme for identifying and isolating malicious nodes is proposed and a mixed strategy and a continuous strategy Monitor-Forward game between the sender node and its one-hop neighboring node is constructed to mitigate the selective dropping attacks in WSN. The continuous game will mitigate false positives on packet dropping detection on unreliable wireless communication channel. Simulation results demonstrate that continuous Monitor-Forward game based selective forwarding solution is an efficient approach to identifying the selective forwarding attacks in WSN.
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  • 170
    Publikationsdatum: 2015-11-26
    Beschreibung: The existing compressed sensing (CS) based data gathering (CSDG) methods in wireless sensor networks (WSNs) usually assume that the sensed data are sparse or compressible. However, the sparsity of raw sensed data in some case is not straightforward. In this paper, we present reshuffling cluster compressed sensing based data gathering (RCCSDG) method to achieve both energy efficiency and reconstruction accuracy in WSNs. By incorporating CS into the cluster protocol, RCCSDG is able to reduce the energy consumption and support larger networks. Moreover, the sparsity of raw sensed data can be greatly improved by reshuffling pretreatment. A theoretical analysis to energy consumption of cluster head is performed, and the cost of the pretreatment is small enough to be neglected. Based on these natures, the raw sensed data can be recovered from fewer samples. Also, considering the sensed data to be of excellent temporal stability in a short time, we reshuffle them just one time in this stable period to further reduce the energy consumption of WSNs. In addition, the delay of RCCSDG is analyzed based on TDMA2 scheduling scheme. We carry out simulations on real sensor datasets. The results show that the RCCSDG can effectively compress the data transmission and decrease energy consumption of WSNs while ensuring the reconstruction accuracy.
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  • 171
    Publikationsdatum: 2015-11-24
    Beschreibung: A compact circular polarized antenna array with a convenient gain/bandwidth/dimension trade-off is proposed for applications in the C-band. The design is based on the recursive application of the sequential phase architecture, resulting in a 4 × 4 array of closely packed identical antennas. The 16 antenna elements are disc-based patches operating in modal degeneration, tuned to exhibit a broad while imperfect polarization. Exploiting the compact dimension of the patches and a space-filling design for the feeding network, the entire array is designed to minimize the occupied area. A prototype of the proposed array is fabricated with standard photoetching procedure in a single-layer via less printed board of overall area 80 × 80 mm2. Adequate left-hand polarization is observed over a wide bandwidth, demonstrating a convenient trade-off between bandwidth and axial ratio. Satisfying experimental results validate the proposed design, with a peak gain of 12.6 dB at 6.7 GHz maintained within 3 dB for 1 GHz, a very wide 10 dB return loss bandwidth of 3 GHz, and a 4 dB axial ratio bandwidth of 1.82 GHz, meaning 31% of fractional bandwidth.
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  • 172
    Publikationsdatum: 2015-11-24
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
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  • 173
    Publikationsdatum: 2015-11-23
    Beschreibung: Pulse coupled neural network (PCNN) has been widely used in image processing. The 3D binary map series (BMS) generated by PCNN effectively describes image feature information such as edges and regional distribution, so BMS can be treated as the basis of extracting 1D oscillation time series (OTS) for an image. However, the traditional methods using BMS did not consider the correlation of the binary sequence in BMS and the space structure for every map. By further processing for BMS, a novel facial feature extraction method is proposed. Firstly, consider the correlation among maps in BMS; a method is put forward to transform BMS into frequency map series (FMS), and the method lessens the influence of noncontinuous feature regions in binary images on OTS-BMS. Then, by computing the 2D entropy for every map in FMS, the 3D FMS is transformed into 1D OTS (OTS-FMS), which has good geometry invariance for the facial image, and contains the space structure information of the image. Finally, by analyzing the OTS-FMS, the standard Euclidean distance is used to measure the distances for OTS-FMS. Experimental results verify the effectiveness of OTS-FMS in facial recognition, and it shows better recognition performance than other feature extraction methods.
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  • 174
    Publikationsdatum: 2015-11-23
    Beschreibung: In target tracking wireless sensor network, choosing the proper working nodes can not only minimize the number of active nodes, but also satisfy the tracking reliability requirement. However, most existing works focus on selecting sensor nodes which are the nearest to the target for tracking missions and they did not consider the correlation of the location of the sensor nodes so that these approaches can not meet all the goals of the network. This work proposes an efficient and adaptive node selection approach for tracking a target in a distributed wireless sensor network. The proposed approach combines the distance-based node selection strategy and particle filter prediction considering the spatial correlation of the different sensing nodes. Moreover, a joint distance weighted measurement is proposed to estimate the information utility of sensing nodes. Experimental results show that EANS outperformed the state-of-the-art approaches by reducing the energy cost and computational complexity as well as guaranteeing the tracking accuracy.
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  • 175
    Publikationsdatum: 2015-11-23
    Beschreibung: For the problem of easily losing track target when obstacles appear in intelligent robot target tracking, this paper proposes a target tracking algorithm integrating reduced dimension optimal Kalman filtering algorithm based on phase-path volume integral with Camshift algorithm. After analyzing the defects of Camshift algorithm, compare the performance with the SIFT algorithm and Mean Shift algorithm, and Kalman filtering algorithm is used for fusion optimization aiming at the defects. Then aiming at the increasing amount of calculation in integrated algorithm, reduce dimension with the phase-path volume integral instead of the Gaussian integral in Kalman algorithm and reduce the number of sampling points in the filtering process without influencing the operational precision of the original algorithm. Finally set the target centroid position from the Camshift algorithm iteration as the observation value of the improved Kalman filtering algorithm to fix predictive value; thus to make optimal estimation of target centroid position and keep the target tracking so that the robot can understand the environmental scene and react in time correctly according to the changes. The experiments show that the improved algorithm proposed in this paper shows good performance in target tracking with obstructions and reduces the computational complexity of the algorithm through the dimension reduction.
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  • 176
    Publikationsdatum: 2015-11-23
    Beschreibung: Nowadays many camera-based advanced driver assistance systems (ADAS) have been introduced to assist the drivers and ensure their safety under various driving conditions. One of the problems faced by drivers is the faded scene visibility and lower contrast while driving in foggy conditions. In this paper, we present a novel approach to provide a solution to this problem by employing deep neural networks. We assume that the fog in an image can be mathematically modeled by an unknown complex function and we utilize the deep neural network to approximate the corresponding mathematical model for the fog. The advantages of our technique are as follows: (i) its real-time operation and (ii) being based on minimal input, that is, a single image, and exhibiting robustness/generalization for various unseen image data. Experiments carried out on various synthetic images indicate that our proposed technique has the abilities to approximate the corresponding fog function reasonably and remove it for better visibility and safety.
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  • 177
    Publikationsdatum: 2015-11-23
    Beschreibung: Prolonged monitoring is more likely to diagnose atrial fibrillation accurately than intermittent or short-term monitoring. In this study, an implantable electrocardiograph (ECG) sensor to monitor atrial fibrillation patients in real time was developed. The implantable sensor is composed of a micro controller unit, an analog-to-digital converter, a signal transmitter, an antenna, and two electrodes. The sensor detects ECG signals from the two electrodes and transmits these to an external receiver carried by the patient. Because the sensor continuously transmits signals, its battery consumption rate is extremely high; therefore, the sensor includes a wireless power transmission module that allows it to charge wirelessly from an external power source. The integrated sensor has the approximate dimensions 3 mm × 4 mm × 14 mm, which is small enough to be inserted into a patient without the need for major surgery. The signal and power transmission data sampling rate and frequency of the unit are 300 samples/s and 430 Hz, respectively. To validate the developed sensor, experiments were conducted on small animals.
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  • 178
    Publikationsdatum: 2015-11-25
    Beschreibung: This paper deals with a method of phase current sensor fault reconstruction for permanent magnet synchronous motor (PMSM) drives. A new state variable is introduced so that an augmented system can be constructed to treat PMSM sensor faults as actuator faults. This method uses the PMSM two-phase stationary reference frame fault model and a sliding mode variable structure observer to reconstruct fault signals. A logic algorithm is built to isolate and identify the faulty sensor for a stator phase current fault after reconstructing the two-phase stationary reference frame fault signals, which allows the phase fault signals to be reconstructed. Simulation results are presented to illustrate the functionality of the theoretical developments.
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  • 179
    Publikationsdatum: 2015-08-26
    Beschreibung: A new algorithm for improving Direction of Arrival Estimation (DOAE) accuracy has been carried out. Two contributions are introduced. First, Doppler frequency shift that resulted from the target movement is estimated using the displacement invariance technique (DIT). Second, the effect of Doppler frequency is modeled and incorporated into ESPRIT algorithm in order to increase the estimation accuracy. It is worth mentioning that the subspace approach has been employed into ESPRIT and DIT methods to reduce the computational complexity and the model’s nonlinearity effect. The DOAE accuracy has been verified by closed-form Cramér-Rao bound (CRB). The simulation results of the proposed algorithm are better than those of the previous estimation techniques leading to the estimator performance enhancement.
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  • 180
    Publikationsdatum: 2015-08-27
    Beschreibung: Associated with a project, the application of real-time monitoring and early warning system in the retrofitting process of structures was investigated. Based on the software ANSYS, structural analysis and thermal analysis were carried out to determine the distribution of sensors and the early warning threshold value in monitoring process. SHM system was developed for damage sensing in real-time using FBG sensors. Eight FBG sensor clusters consisting of a strain sensor and a temperature sensor were welded on the steel beam surface. Using these FBG sensors, the real-time strains in key positions during the cutting process of steel beam were measured. The monitoring data provided the early warnings and effective reference for analyzing the stability of steel beam in real-time.
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  • 181
    Publikationsdatum: 2015-08-27
    Beschreibung: Recently, RFID technology has come into end-user applications for monitoring, tracking, and so forth. In RFID system, a reader identifies a set of tags over a shared wireless channel. When multiple tags communicate with the same reader simultaneously, all packages will be lost and no tag can be recognized, which is known as tag collision. Tag collision is a significantly important issue for fast tag identification. We firstly make a thorough analysis among a variety of traditional RFID anticollision algorithms. Then a novel hybrid anticollision algorithm called T-GDFSA is proposed. Tags are assigned to different groups based on the initial tag estimation and then experience several dynamic read frames for identification. When a collision occurs in current slot, a tree-based recursive process will be deployed immediately. T-GDFSA combines the advantages of ALOHA-based and tree-based together and acquires higher system throughput by reducing unnecessary idle and collision slots and lower communication complexity by decreasing the data transmitted, which makes it identify tags faster with less power consumption. Simulations show that the theoretical values match well the simulation results. Moreover, T-GDFSA also has a good tolerance for the inaccuracy of initial tag estimation and the length variation of tag’s ID.
    Print ISSN: 1550-1329
    Digitale ISSN: 1550-1477
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 182
    Publikationsdatum: 2015-08-27
    Beschreibung: The dramatically increasing number of connected things based on Internet protocol is leading to a new concept called the Internet of Things (IoT). The Internet-integrated wireless sensor network has recently become one of the most important service targets in IoT field. To provide secure IoT services, the IETF proposed using Datagram Transport Layer Security (DTLS) as a de facto security protocol. In this paper, we examine problems that can happen when applying the DTLS protocol to the IoT, which comprises constrained devices and constrained networks. To solve the problems at hand, we separate the DTLS protocol into a handshake phase (i.e., establishment phase) and an encryption phase (i.e., transmission phase). Our approach enhances the performance of both device and network by using a way to delegate the DTLS handshake phase. The proposed scheme supports secure end-to-end communication despite using delegation.
    Print ISSN: 1550-1329
    Digitale ISSN: 1550-1477
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 183
    Publikationsdatum: 2015-08-27
    Beschreibung: IEEE 1609.4 defines MAC layer implementation in a vehicular ad hoc network (VANET). In IEEE 1609.4 multichannel operation, the control channel interval (CCHI) and the service channel interval (SCHI) are defined such that service channels cannot be utilized during the CCHI, and vice versa, which leads to poor utilization of scarce spectrum resources. In this paper, we propose a multi-schedule-based channel switching mechanism to improve channel utilization and uniformly distribute channel load. In our proposed mechanism, four schedules are defined to switch between the control channel and service channels. Therefore, service channels can be utilized during the CCHI, and the control channel can be utilized during the SCHI. Moreover, control channel load is distributed throughout the whole sync interval. We compared our proposed MAC protocol with IEEE802.11p for wireless access in the vehicular environment using the OMNET++ 4.5 network simulator. In the simulation results, we determined that utilization of the service channel increased and contention on the control channel was reduced, compared with the legacy standard, especially in slow motion and high-density VANETs.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 184
    Publikationsdatum: 2015-08-27
    Beschreibung: Green synthesis of metallic particles has become an economic way to improve and protect the environment by decreasing the use of toxic chemicals and eliminating dyes. The synthesis of metal particles is gaining more importance due to its simplicity, rapid rate of synthesis of particles, and environmentally friendly. The present work aims to report a novel and environmentally friendly method for the synthesis of iron particles using deoiled Pimenta dioica L. Merrill husk as support. The indigo carmine removal efficiency by ozonation and catalyzed ozonation is also presented. Synthesized materials were characterized by N2 physisorption and scanning electron microscopy (SEM/EDS). By UV-Vis spectrophotometry the removal efficiency of indigo carmine was found to be nearly 100% after only 20 minutes of treatment under pH 3 and with a catalyst loading of 1000 mgL−1. Analytical techniques such as determination of the total organic carbon content (TOC) and chemical oxygen demand (COD) showed that iron particles supported on deoiled Pimenta dioica L. Merrill husk can be efficiently employed to degrade indigo carmine and achieved a partial mineralization (conversion to CO2 and H2O) of the molecule. From the results can be inferred that the prepared biocomposite increases the hydroxyl radicals generation.
    Print ISSN: 1110-662X
    Digitale ISSN: 1687-529X
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Energietechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 185
    Publikationsdatum: 2015-08-27
    Beschreibung: The individual methods of disinfection peracetic acid (PAA) and UV radiation and combined process PAA/UV in water (synthetic) and sanitary wastewater were employed to verify the individual and combined action of these advanced oxidative processes on the effectiveness of inactivation of microorganisms indicators of fecal contamination E. coli, total coliforms (in the case of sanitary wastewater), and coliphages (such as virus indicators). Under the experimental conditions investigated, doses of 2, 3, and 4 mg/L of PAA and contact time of 10 minutes and 60 and 90 s exposure to UV radiation, the results indicated that the combined method PAA/UV provided superior efficacy when compared to individual methods of disinfection.
    Print ISSN: 1110-662X
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Energietechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 186
    Publikationsdatum: 2015-08-27
    Beschreibung: In wireless sensor network, two scenarios are combined which involve either short-range or long-range communications. IEEE 802.15.4g and IEEE 802.11 are considered in machine to machine environments, because they can utilize the identical frequency band. The performances of the physical modes of the IEEE 802.15.4g and the IEEE 802.11 standards are presented and are compared in terms of the bit error rate and throughput when additive white Gaussian noise, shadowing, and multipath fading channels are assumed. The numerical results show that IEEE 802.11 is more vulnerable than IEEE 802.15.4g in the shadowing channels when compared to the AWGN channel. For the multipath fading channel, IEEE 802.11 performs better than IEEE 802.15.4g. It is necessary that adequate communication is configured depending on the required performance characteristics, , service coverage, and channel environments.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 187
    Publikationsdatum: 2015-08-27
    Beschreibung: This work presents a novel approach to design a maximally flat negative group delay (NGD) circuit based on microwave recursive filters. The proposed NGD circuit is realized by cascading stages of quarter-wavelength stepped-impedance transformer. It is shown that the given circuit can be designed to have any prescribed group delay by changing the characteristic impedance of the quarter-wave transformers (QWTs) cascaded with each other. The proposed approach provides a systematic method to synthesize NGD of arbitrary amount without including any discrete lumped component. For various prescribed NGD, the characteristic impedance of QWT has been tabulated for two and three stages of the circuit. The widths and lengths of microstrip transmission lines can be obtained from characteristic impedance and the frequency of operation of the transmission line. The results are verified in both simulation and measurement, showing a good agreement.
    Print ISSN: 1687-5826
    Digitale ISSN: 1687-5834
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 188
    Publikationsdatum: 2015-08-27
    Beschreibung: The world is experiencing an unprecedented explosion in the number of smart devices and mobile apps that are available to users. In the health and fitness domains, many of the devices and technologies in the market place are restricted to proprietary platforms, typically working in isolation with fixed hardware settings. Consequently, an important challenge is to investigate techniques for combining and analyzing data encapsulated by these ubiquitous technologies. In this paper, we introduce an intelligent middleware—Device Nimbus—to meet this challenge. The middleware supports the integration of distributed and heterogeneous mobile sensor data, enabling both context and predictive analysis. We describe a minimum viable product of Device Nimbus and report the results of preliminary tests spanning multiple data sources focused on fitness apps, illustrating the efficacy of the middleware.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 189
    Publikationsdatum: 2015-08-27
    Beschreibung: Biologically inspired modeling techniques have received considerable attention for the realization of robustness, scalability, and adaptability with simple local interactions and limited information. Gene Regulatory Networks (GRNs) play a central role in understanding natural evolution and development of biological organisms from cells. In this paper, we employ GRN principles and propose a new GRN model for self-organizing control of Wireless Sensor Networks (WSNs) with dual aims of energy saving and delay guarantee. Through this scheme, each sensor node schedules its state autonomously according to the controlled gene expression and protein concentration of the proposed GRN model. Simulation results also indicate that the proposed scheme achieves good performance in meeting delay requirements and conserving energy in WSN systems.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 190
    Publikationsdatum: 2015-08-27
    Beschreibung: We propose an adaptive interference avoidance scheme that enhances the performance of ZigBee networks by adapting ZigBees' transmissions to measured wireless local area network (WLAN) interference. Our proposed algorithm is based on a stochastic analysis of ZigBee operation that is interfered with by WLAN transmission, given ZigBee and WLAN channels are overlaid in the industrial, scientific, and medical (ISM) band. We assume that WLAN devices have higher transmission power than ZigBee devices. Then, the high transmission power of WLAN devices causes the capture effect when WLAN and ZigBee transmit simultaneously. On the other hand, ZigBee performs backoff during clear channel assessment (CCA) operation if the WLAN is transmitting its frames on the channel. We adopt a widely used WLAN queueing/transmission model that is based on a Markov chain concept. We model a ZigBee device’s operation using the Markov chain that includes WLAN interference statistically derived from the WLAN queueing/transmission model. Our proposed algorithm is evaluated in a simulated ZigBee network in the presence of varying WLAN interference. Numerical results show that our WLAN interference mitigation scheme finds the ZigBee control parameters, among a candidate set, which enhances ZigBee network performance compared to the conventional ZigBee operation.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 191
    Publikationsdatum: 2015-10-28
    Beschreibung: This paper presents an energy harvesting wireless sensor network (EHWSN) architecture designed for use within an astronaut’s space suit. The contribution of this work spans both physical (PHY) layer energy harvesting transceiver design and low power medium access control (MAC) solutions. The architecture consists of a star topology with two types of transceiver nodes: a powered gateway radio (GR) node and multiple energy harvesting biosensor radio (BSR) nodes. To demonstrate the feasibility of an EHWSN at the PHY layer, a representative BSR node is implemented. The BSR node is powered by a thermal energy harvesting system (TEHS) which exploits the difference between the temperatures of a space suit’s cooling garment and the astronaut’s body. It is shown that, through appropriate control of the duty cycle in transmission and receiving modes, it is possible to operate with less than 1 mW generated by the TEHS. This requires ultralow duty cycle which complicates MAC layer design because a BSR node must sleep for more than 99.6% of overall operation time. The challenge for MAC layer design is the inability to predict when the BSR node awakens from sleep mode due to unpredictability of the harvested energy. Therefore, a new feasible MAC layer design, GRI- (gateway radio initialized-) MAC, is proposed and analyzed.
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 192
    Publikationsdatum: 2015-10-28
    Beschreibung: The design and simulation of a 10 × 8 multibeam dual-band orthogonal linearly polarized antenna array operating at Ku-band are presented for transmit-receive applications. By using patches with different coupling methods as elements, both perpendicular polarization in 12.25–12.75 GHz band and horizontal polarization in 14.0–14.5 GHz band are realized in a shared antenna aperture. A microstrip Rotman lens is employed as the beamforming network with 7 input ports, which can generate a corresponding number of beams to cover −30°–30° with 5 dB beamwidth along one dimension. This type of multibeam orthogonal linearly polarized planar antenna is a good candidate for satellite communication (SatCom).
    Print ISSN: 1687-5869
    Digitale ISSN: 1687-5877
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 193
    Publikationsdatum: 2015-06-01
    Beschreibung: As the available space in the board of a mobile device becomes smaller and more compact, circuit elements and transmission lines are arranged in very close proximity, especially from the antennas which are usually installed on the same board. Due to the various on-board antennas which are designed in small space, the transmission lines on the board are electromagnetically interfered, resulting in the performance degradation of the circuit. So the engineers and circuit designers should find the least interfered place for the transmission lines and components to minimize the electromagnetic interferences. This paper discusses and presents a methodology to find the least sensitive position in the induced current distribution as well as in the noise power delivered from the antenna. For this purpose some vertical, horizontal, and bent transmission lines with antenna on the same board are designed and fabricated with and without common ground, and the transferred powers to the transmission lines were measured and were also simulated using a full-wave simulator. The results predicted by the EM simulation model were successfully confirmed through the measurement of S-parameters in the experimental setup, which shows the validness of the suggested analysis method.
    Print ISSN: 1687-5869
    Digitale ISSN: 1687-5877
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 194
    Publikationsdatum: 2015-06-01
    Beschreibung: With the popularity of web, the internet is becoming a major information provider and poster of an event due to its real-time, open, and dynamic features. In this paper, crowd sensing based burst computation algorithm of a web event is developed in order to let the people know a web event clearly and help the social group or government process the events effectively. Different temporal features of web events are developed to provide the basics for the proposed computation algorithm. The burst power is presented to integrate the above temporal features of an event. Empirical experiments on real datasets including Google Zeitgeist and Google Trends show that the number of web pages and the average clustering coefficient can be used to detect events. The evaluations on real dataset show that the proposed function integrating the number of web pages and the average clustering coefficient can be used for event detection efficiently and correctly.
    Print ISSN: 1550-1329
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    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 195
    Publikationsdatum: 2015-06-02
    Beschreibung: We consider a problem of minimum cost (energy) data aggregation in wireless sensor networks computing certain functions of sensed data. We use in-network aggregation such that data can be combined at the intermediate nodes en route to the sink. We consider two types of functions: firstly the summation-type which includes sum, mean, and weighted sum, and secondly the extreme-type which includes max and min. However for both types of functions the problem turns out to be NP-hard. We first show that, for sum and mean, there exist algorithms which can approximate the optimal cost by a factor logarithmic in the number of sources. For weighted sum we obtain a similar result for Gaussian sources. Next we reveal that the problem for extreme-type functions is intrinsically different from that for summation-type functions. We then propose a novel algorithm based on the crucial tradeoff in reducing costs between local aggregation of flows and finding a low cost path to the sink: the algorithm is shown to empirically find the best tradeoff point. We argue that the algorithm is applicable to many other similar types of problems. Simulation results show that significant cost savings can be achieved by the proposed algorithm.
    Print ISSN: 1687-725X
    Digitale ISSN: 1687-7268
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 196
    Publikationsdatum: 2015-06-02
    Beschreibung: The paper proposes a novel secure data fusion strategy based on compressed image sensing and watermarking; namely, the algorithm exploits the sparsity in the image encryption. The approach relies on -norm regularization, common in compressive sensing, to enhance the detection of sparsity over wireless multimedia sensor networks. The resulting algorithms endow sensor nodes with learning abilities and allow them to learn the sparse structure from the still image data, and also utilize the watermarking approach to achieve authentication mechanism. We provide the total transmission volume and the energy consumption performance analysis of each node, and summarize the peak signal to noise ratio values of the proposed method. We also show how to adaptively select the sampling parameter. Simulation results illustrate the advantage of the proposed strategy for secure data fusion.
    Print ISSN: 1687-725X
    Digitale ISSN: 1687-7268
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 197
    facet.materialart.
    Unbekannt
    Hindawi
    Publikationsdatum: 2015-06-02
    Beschreibung: Ant colony algorithm is a classical routing algorithm. And it are used in a variety of application because it is economic and self-organized. However, the routing algorithm will expend huge amounts of energy at the beginning. In the paper, based on the idea of Dijkstra algorithm, the improved ant colony algorithm was proposed to balance the energy consumption of networks. Through simulation and comparison with basic ant colony algorithms, it is obvious that improved algorithm can effectively balance energy consumption and extend the lifetime of WSNs.
    Print ISSN: 1687-725X
    Digitale ISSN: 1687-7268
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 198
    Publikationsdatum: 2015-06-02
    Beschreibung: We design and implement a low-cost rehabilitation glove to meet the needs of those patients who have paralysis in their affected hand. The novelty of this glove is that it is to be worn on the unaffected hand which acts as a natural robotic arm during the rehabilitation session. The glove is equipped with FSR sensors that measure the forces exerted by the affected hand on the unaffected hand. A virtual reality rehabilitation game is developed using Microsoft Kinect to facilitate the exercises and motivate the patients. The system is tested on three patients for six weeks. Objective measurements showed that patients have significantly improved over the study period. Moreover, the patients themselves gave positive feedback on the whole system; wearing the glove on the unaffected hand made their life easier and let them enjoy the rehabilitation sessions.
    Print ISSN: 1550-1329
    Digitale ISSN: 1550-1477
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 199
    Publikationsdatum: 2015-06-02
    Beschreibung: Balanced energy consumption in WSNs is the key to maximize network lifetime. After analyzing laws of energy consumption of WSNs, a heterogeneous node deployment model based on area topology control is proposed in this paper. It utilizes predetermined heterogeneous node deployment to balance area energy consumption ratio and the topology control algorithm based on area energy consumption ratio to maintain dynamic equilibrium energy consumption. Simulation results show that our model takes a superior performance on maintaining network coverage, balancing energy consumption, and maximizing network lifetime. Compared with similar WSNs deployment models, our model can be more efficient to prolong network lifetime and has advantages in reducing dependence on deployment accuracy, balancing dynamic energy consumption, and improving lifetime in poor network environment.
    Print ISSN: 1550-1329
    Digitale ISSN: 1550-1477
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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  • 200
    Publikationsdatum: 2015-06-02
    Beschreibung: We present an e-therapy framework that collects live therapeutic context by analyzing body joint data in a noninvasive way. Using our proposed framework, a therapist can model complex gestures by mapping them to a set of primitive gesture sequences and generate high-level serious game-based therapies. As a proof of concept, we have developed scenarios to express a hemiplegic patient’s behavior into a set of trackable primitive gestures. We have used Second Life and Map browsing based serious game environment for immersive experience. The initial feedback from the therapists who have tested our developed framework is encouraging. Finally, we share the implementation details and analysis of test results.
    Print ISSN: 1550-1329
    Digitale ISSN: 1550-1477
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Publiziert von Hindawi
    Standort Signatur Erwartet Verfügbarkeit
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