Applied Mechanics and Materials Vols. 519-520

Abstract: Force-directed placement method for large scale integration physical design is a very effective and fast method to spread the cell uniformly in the placement region. But this kind of method also create large amount of cell overlap in initial placement. In this paper, we present an effective method to cope with cell spreading and add additional force without damaging the wire length. It mainly takes the following method: Firstly, in the prior period of iteration n we keep limit the cell moving distance using a rectangle structure .Because the prior iteration play a decisive role in the final placement quality. Secondly, after the cell relative order determined we can use a new method to compute the weight of additional force to accelerate converge. Thirdly, a strategy called iterative local refinement is added in the well-distributed placement to further reduce the total wire length.

Abstract: The method of traditional architectural decoration design can not meet the requirtments of modern industrlization for the disadvantages of excessive consumption on time and human resources as well as the inclination to high error rate . Computer aided technology, as an efficient auxiliary tool, while, facilitate the design of construction blueprint with the ability of powerful data processing and storaging, which achieve the realization of overcome of the disvantages amentioned before.

Abstract: This study addresses a method to realize cloth dynamics simulation by using a wind noise method. Taken a 1/f noise as its 2D model, the 3D model of the discussed cloth is constructed. During its 3D simulation, some stochastic functions are employed to depict its stochastic ability. For the purpose of realism and simplicity, we attend to convert our dynamic simulation frames into animation film files. From the feedback, the constructed model is improved and the real time simulation is realized by reducing the calculation.

Abstract: In this paper, we study the effective capacity (EC) which was proposed to measure the quality of service (QoS) for fading channels. A unified expression for the effective capacity based on the method of moment generating function (MGF) is proposed. The unified expression applies to various fading channels and is derived for both single antenna and multiple antenna diversity system. The mathematical expression is illustrated with Nakagami-m fading channels and closed form expressions are derived in this case. The simulation results verify the consistence of the closed-form expressions with numerical evaluations.

Abstract: In this paper, we study the different channel estimation strategies applied in an AF network, including ordinary channel estimation which estimate the whole source-relay-destination (SRD) channel at the destination, and a new proposed equalized AF (EAF) which make channel estimation separately at relay node and destination node. The EAF carries out the equalization at relay node by the channel estimation, which leads to performance improvement. The analysis of achievable rates is given and the performance benefit of EAF is verified by both numeric and realistic simulation.

Abstract: Partial transmit sequence (PTS) scheme is one of the most effective way to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The cyclic shift on time-domain PTS has better performance in PAPR reduction than that of the conventional PTS (C-PTS), and the receiver can recover phase rotations without using side information (SI). However, the receiver must know channel response before detecting and perform complex operations in order to detect the phase rotation factors. In this letter we proposed a pilot design method based on cyclic shift on time-domain PTS, which can estimate phase rotation factors and channel response more easily. Simulation results show that the PAPR performance of the proposed method is approximately same as the cyclic shift PTS scheme and the BER performance is also as well as C-PTS with perfect SI in multipath channel scene.

Abstract: Compared with binary-modulation, Multiple-modulation can obtain higher rate of transmission in the condition of same symbol-rate. If using binary channel codes with multiple-modulation, there exists an problem of information-loss of the probability from bit to symbol conversion. Underwater acoustic channel is an multipath, time-variation, high-noise and strong doppler-effect wireless channel, which leads to high error-rate caused by signal distortion. To solve the problems above, we adopt FH-MFSK modulation to overcome the inter-symbol interference by multipath. The PN sequence is used as a frame synchronization signal and frequency energy accumulation method is used to detect the frame-synchronization. PN hopping signal is chosen to estimate the doppler frequency-shift and using non-binary LDPC codes based on symbol for channel error codes. Finally, We perform numerical simulations and the experiments on the lake to show that compared with binary LDPC codes, non-binary LDPC codes for multiple-modulation can achieve same error-rate under lower SNR.

Abstract: The generating polynomials of higher power residue codes over finite fields are difficult to construct. This paper gives explicit expressions of generating idempotents of quartic residue codes over the field $F_4$.The result will enable one to construct the generating polynomials of quartic residue codes over the field $F_4$ by computing the greatest common divisors of these generating idempotents and the polynomial $x^n-1$ with computer software such as Matlab and Maple.

Abstract: As metropolitan areas have expanded and been surrounded by huge buildings and complicated express ways, it has been increased to utilize advanced ICT(Information Computer Technology) devices and systems to innovate utility services such as GIS(Geographic Information System). Keeping abreast of this, location privacy has emerged as a critical issue in ubiquitous computing environments for the metropolitan areas. Nevertheless, the focus of the location privacy is only about personal location information, not about location information such as the place itself. However, in a real world, as seen in the precedent of ‘Dow Chemical vs. United States’ or in controlled areas of military districts, we have already recognized the importance of location information. In this paper, we propose a negotiation protocol to protect location information as well as personal location information. Thus, we can achieve real data protection through the negotiation-process in the respect of self-regulation.

Abstract: Certificateless public key cryptography eliminates inherent key escrow problem in identity-based cryptography, and does not yet requires certificates as in the traditional public key infrastructure. Recently, Yu et al. propose a new certificateless signature scheme and their scheme offers shorter system parameters and higher computational efficiency than the previous schemes in the standard model. However, in this paper, we show Yu et al.'s certificateless signature scheme is vulnerable to malicious-but-passive KGC attack where a malicious KGC can forge valid signatures by embedding extra trapdoors in the system parameter.