Applied Mechanics and Materials Vols. 284-287

Abstract: LED is the solid-state light source of the 21st century that ranges from white light to any color in the entire spectrum. LED lights create static or dynamic illumination in indoor lighting applications. Modern indoor lighting fixtures not only provide illumination, but also are the primary elements that create the atmosphere. The use of gradual mixing of lights or different colors not only makes lights fit more people’s physical and psychological needs, but also improve one’s aesthetic perspectives. However, the LED color mixing technique based on RGB colors requires the package of the RGB chips in on single space for the creation of color mixing through the control of voltage and current. An innovative color mixing technique was proposed in this study. A linkage mechanism was introduced. The individual RGB chips were installed in 3 sets of four-bar linkages to enable color mixing by driving the RGB chips with the crank of the mechanism. The color mixing effects provide a continuing change of colors to meet people’s requirements for color mixing fixtures in certain scenarios. The fixtures incorporating this design can be used for stage lighting and biomedical engineering testing.

Abstract: In order to overcome the vulnerability to eavesdropping on-off-keying based OCDMA scheme, a new multi-code keying reconfiguration is presented to enhance confidentiality over two dimensional time-spreading and wavelength-hopping (2D TS/WH) optical code division multiple access (OCDMA) schemes. The time-shifted carrier-hopping prime codes (CHPCs) are proposed and assigned as signature address code. This proposed scheme provides the integration of electronic and optical layer domain, which inherently comes from the data encryption and spectrum-spreading of the transmitted signals, and then achieves data-confidential enhancement in synchronous networks. Moreover, multi-code keying reconfiguration in a set of distinct codeword is assigned to individual user and random selection by using thin film filter, tunable delay line and optical switch. Here, the probability of interception performance in terms of various multi-code key numbers per user is analyzed. The result shows that the confidentiality is enhanced to combat against eavesdropping while signature address code number per user is increased in proposed multi-code key reconfiguration scheme.

Abstract: Multimedia traffic is expected to be one of the most important traffic types in wireless LANs. However, multimedia traffic is very sensitive to delay so that the traffic has to be transmitted to receivers within its delay bound. The IEEE 802.11e EDCA (Enhanced Distributed Channel Access) defines a TXOP (Transmission Opportunity) parameter to provide service differentiation and QoS (Quality of Service) of the traffic. A station can continuously transmit multiple packets for the duration of a TXOP. When stations support multimedia applications with different QoS requirements, fairness problem occurs. In order to alleviate the fairness problem, we propose a distributed TXOP allocation scheme based on the delay bound. In the proposed scheme, a station checks the delay bound of each data packet in the queue, and allocates its TXOP value to guarantee the delay bounds of all the packets in the queue. Simulation results show that the proposed scheme outperforms other TXOP allocation schemes.

Abstract: In this paper, we use MATLAB software to build the physical layer transceiver of the Digital Video Broadcasting Terrestrial System (DVB-T) and Additive White Gaussian Noise (AWGN) is added into the transmitted signal during its transmission. The transmitted signal passes through modulation, demodulation, encoding and decoding processes the resulting demodulated signal is compared with the transmitted signal to calculate its Bit Error Rate (BER). Three modulation formats, QPAK, 16-QAM and 64-QAM are simulated and through various Signal to Noise (SNR) ratio to evaluate the system performance. Various encoding techniques such as Reed Solomon Code, Convolutional Code and Viterbi Decoding [1-6] have been implemented and through simulation to make detailed system performance analysis and comparison. detailed system performance simulation, analysis and comparisons.

Abstract: Block-based motion estimation plays important roles in video applications such as video compression to detect movements as well as remove temporal redundancies between successive frames. Full-search block-matching (FSBM) is the preferred algorithm for accurate motion estimation. Frame-level pipelined systolic array (FLSA) FSBM architectures have advantages over block-level pipelined architectures in their simpler control and reduced number of memory accesses. In this paper, a frame-level pipelined FSBM motion estimation architecture using array processor for any square, N×N, block size is presented in full detail.

Abstract: This paper presents the research of an intelligent local search method for dynamic indoor path tracking over a low-cost, simple connected wireless sensor network (WSN) in the applications of the tour guidance in the theme exhibition, large-scale market and shopping center, etc. The enhanced heuristic-based path tracking algorithm (EHPTA) incorporates the weighted vertex-in-the-intersection method for wireless triangulation and explores three searching steps for dynamic path tracking while considering the effects of received signal deterioration through a RSSI (received signal strength indication) vs. distance curve which have been plotted by experimental measurements. Four kinds of scenarios of total 13 simulated paths and 2 real paths, an 8-meter-perimeter square path and a 16-meter zigzag-like path, have been designed and tracked to evaluate the proposed algorithm’s performance on tracking optimality. The numerical results show that the EHPTA achieves an outstanding performance among the developed techniques.

Abstract: This study proposes an improvement to tree-structured vector quantization (TSVQ). The selected codeword of TSVQ is employed as the reference codeword. The dynamic triangular inequality elimination (DTIE) is employed to improve the performance of TSVQ. In the DTIE-TSVQ approach, the selected codeword and SNR are identical to that of full-search vector quantization (FSVQ), and the computational saving is better than that of TIE-VQ. The experimental results confirm that DTIE-TSVQ outperforms TIE-VQ, TSVQ.

Abstract: A distribution system consists of a number of feeders, switches and load zones. The distribution system topology may be reconfigured by changing the statuses of switches on the feeders such that the system real power loss can be reduced. However, the loads in the zone may be varied at different time in reality which leads to the system losses changed from time to time. This paper applies Evolutionary Programming (EP) approach attempt to find a switch operation strategy that can be applied to change the topology of the distribution system while minimizing the system total energy loss for a period of time. As the feeder reconfiguration is a multi-objective problem in nature, Grey Correlation Grade (GCG) is employed to gratify the selection operation in EP. The required information of this paper is retrieved from the Outage Management System (OMS) of Taiwan Power Company (TPC). The results indicate the system energy loss can be reduced with limited number of switch operations when multiple objectives are considered simultaneously under load variation conditions.

Abstract: The element parameters of engineering machinery hydraulic system are detected, the fault eigenvector is extracted, and the information is applied to neural network fault diagnosis. Experience mode decomposition (EMD) is used to extract fault characteristic vectors in this paper, combined with the pressure, temperature and flow rate of dominant signal as neural network's inputs. In addition, the paper improves the Elman neural network learning algorithm by PSO algorithm. It can effectively increase network convergence rate and computing power. The particle swarm is used to optimize Elman neural network weights and the threshold value and then applied in the fault diagnosis system by training the network. The results show that the method increases the neural network convergence rate and reduces diagnoses error.

Abstract: To the best of our knowledge, this study represents the proposal using the dynamic least mean square (DLMS) algorithm to reduce the computation load of LMS. Moreover, three regions of impulse response of line echo path are also proposed to analyze the redundant coefficients. Using the DLMS method, redundant coefficients can be detected and grouped, thereby automatically reducing computation. We employed line echo cancellation (LEC) to evaluate the performance of DLMS. The pure-delay and overlong regions of impulse response of line echo path are grouped and the associated computation load is reduced. The experimental results confirm the excellent performance of DLMS achieving a 35% savings in computation. Moreover, the quality echo return loss enhancement (ERLE) of DLMS also maintains at a level nearly equal to LMS.