A Novel Three-State ARQ Scheme for Variable Error-Tate Channels

This paper presents a new type of automatic-repeat-request (ARQ) scheme, Three-State ARQ (TS-ARQ), for error control in data transmission over a noisy channel. The new scheme is based on the Go-Back-N (GBN) protocol and uses three different methods of GBN protocols: basic GBN, n-copy GBN and continuous-GBN. The new ARQ model is applicable for channels having the variable noise level going from low through medium until very high levels. As it is known, such wireless channels are to be found in terrestrial and space (satellite) communications. This model is to be used for the estimation of the noise state in the channel and one of the methods is used, depending of the noise level. When the noise level is low GBN-ARQ is used, in the case of the medium noise level the n-copy GBN is used, and if the noise level is high continuous-GBN will be applied. This paper presents the method of determining the parameters and transfer moments from one state to another. An original mathematical model is given, together with evaluation results. These results are compared with the known methods and the conclusion that the described method provides some better performances is drowned. The implementation of this new procedure is simple as described in the flow chart given in the paper.     

高帧频数字摄像机显示系统设计

以Camera Link接口的高帧频数字摄像机具有输出帧频高、数据量大的特点,常规的监视器无法直接显示,限制了其在实时监测方面的应用,因此,高帧频数字摄像机的实时全分辨率显示具有重要意义。本文分析了高帧频摄像机数字口输出工作时序,针对其数据量大的特点,提出利用FPGA外部扩展SDRAM的方式存储缓冲图像数据的解决方案。该方案可灵活抽取SDRAM存储的部分数据帧来显示,实现高速图像数据流的帧频变换和时钟域变换,在相应的显示时序控制下,通过DAC转换成VGA视频格式以满足显示设备的需要,实现视频图像的稳定显示。     

改进的BP神经网络在交通流量预测中应用

针对传统BP学习算法收敛速度慢,对步长依赖明显等缺点,提出一种利用搜索较优步长的BP算法.在网络训练中,能够在每次迭代中搜索出一个相对合理的步长,从而使步长的选择对学习速度的影响大大降低.对交通流量预测仿真结果表明,新算法对步长选择的依赖性小于传统BP算法.     

磨料对蓝宝石衬底去除速率的影响

蓝宝石晶体已经成为现代工业,尤其是微电子及光电子产业极为重要的衬底材料,提高其化学机械抛光效率是业界无法回避的问题。在CMP系统中,磨料是决定去除速率及表面状态的重要因素。分析了化学机械抛光过程中抛光液中磨料的作用以及抛光机理,在确保表面状态的基础上,研究了抛光液中磨料体积分数、粒径和抛光液的黏度对速率的影响,指出纳米磨料是蓝宝石衬底抛光的最佳磨料。选用合适的磨料体积分数、粒径及抛光液黏度,不仅获得了良好的去除速率,而且有效地解决了表面状态方面的问题。     

Controlled Incorporation of Ni(OH)2 Nanoplates Into Flowerlike MoS2 Nanosheets for Flexible All‐Solid‐State Supercapacitors

In this work, self‐supporting three‐dimensional hierarchical nanostructured MoS₂@Ni(OH)₂ nanocomposites are synthesized via a facile single‐mode microwave hydrothermal technique. The fabricated MoS₂@Ni(OH)₂ nanocomposites for supercapacitors in aqueous electrolyte exhibit higher specific capacitance and better cyclic stability than those of MoS₂ and Ni(OH)₂ due to the pronounced synergistic effect between MoS₂ and Ni(OH)₂. Further, the flexible all‐solid‐state supercapcitor is readily constructed by composing the PVA/KOH gel electrolyte in between two MoS₂@Ni(OH)₂ electrodes on the flexible PET substrates. The resulting supercapacitors can operate at high rate up to 1000 V/s, have excellent long‐life cycling stability, retaining 94.2% of the initial capacitance after 9000 cycles, and mechanical flexibility during extreme bending, respectively. Thereby, the MoS₂@Ni(OH)₂ nanocomposites are a promising electrode materials for flexible long‐life cycling all‐solid‐sate supercapacitors.     

Periodic variation method for blind symbol rate estimation

In order to obtain unknown symbol rate of incoming signal at a receiver, in this paper, cyclostationary features of linear digitally modulated signals are exploited by proposed periodic variation method. A low complexity but highly accurate symbol rate estimation technique is obtained. The proposed method is based on a superposed epoch analysis over autocorrelations obtained blindly in different sampling frequencies. The obtained autocorrelations are analyzed in the frequency domain, and it is seen that there are large oscillations when the autocorrelation is obtained around the symbol rate. Then, a superposed epoch analysis is developed in order to estimate symbol rate based of the periodic variations on the frequency responses of autocorrelations. The proposed algorithm is quite accurate in the noisy environment because the noise is having no frequency component after taking Fourier transform of autocorrelations in all sampling rates, and this feature is also valid for the offset frequency that the purposed estimation is not affected by offset frequency. Thus, a successful blind symbol rate estimation algorithm is obtained, and it performs much better error performance than those using the well‐known cyclic correlation based symbol rate estimations, as it is proven by the obtained performances presented in the paper. Copyright © 2013 John Wiley & Sons, Ltd.     

Design of Distributed Beamforming for Dual‐Hop Multiple‐Access Relay Networks

This paper studies a dual‐hop multiple‐access relay network where two independent source nodes transmit information to a common destination node with the aid of multiple single‐antenna amplify‐and‐forward relays. Each relay node is subject to an individual power constraint. We focus on the design of distributed beamforming schemes for the relays to support the transmission rate requirements of the two sources. To this end, we first characterize the achievable rate region for this network via solving a sequence of corner point optimization problems proposed in this paper. We also develop several low‐complexity suboptimal schemes in closed form. Two inner bounds of the achievable rate region are theoretically shown to be approximately optimal in two special scenarios. Finally, numerical results demonstrate the effectiveness of our proposed approaches.     

硅通孔抛光液的研究进展

硅通孔(TSV)技术是一种先进的封装技术,化学机械抛光(CMP)是集成电路TSV制作过程中的重要步骤之一,是可兼顾材料表面局部和全局平坦化的技术。抛光液是影响抛光表面质量和加工效率的关键因素,是CMP工艺中消耗品成本最大的部分。TSV抛光液主要包括铜膜抛光液和阻挡层抛光液,依据抛光速率和抛光质量(表面粗糙度、碟形坑修正等)的要求对其进行了分类讨论,概述了近年来TSV抛光液的研究进展,对其今后的研究重点和发展趋势进行了分析和预测,认为TSV抛光液应朝着抛光速率和抛光质量的优化、低成本、环境友好的方向发展。     

含氢储能的多源联合发电系统调度研究

风电和光伏发电具有间歇性和随机性,为了降低在多源联合发电系统中的弃风弃光率,采用含氢储能系统和火电机组配合来平滑风电和光电机组出力。文中以系统运行成本最小和弃电惩罚成本最小为目标,以系统功率平衡、火电机组出力和爬坡、热备用、风电和光电出力及储能系统储氢罐容量、电解槽和燃料电池功率等为约束条件构建了多源联合发电系统日前调度模型。通过YALMIP工具箱对模型进行编程,并调用CPLEX对编写的程序进行求解。对含有风电、光电、火电机组以及储能系统的多源联合发电系统进行算例分析,通过对比有无储能系统的弃风弃光量和系统总运行成本,证明了含氢储能系统可以有效降低系统的弃风弃光率,并提高系统的经济性。     

Alkaline barrier slurry applied in TSV chemical mechanical planarization

We have proposed a TSV （through-silicon-via） alkaline barrier slurry without any inhibitors for barrier CMP （chemical mechanical planarization） and investigated its CMP performance. The characteristics of removal rate and selectivity of Ti/SiO2/Cu were investigated under the same process conditions. The results obtained from 6.2 mm copper, titanium and silica show that copper has a low removal rate during barrier CMP by using this slurry, and Ti and SiO2 have high removal rate selectivity to Cu. Thus it may be helpful to modify the dishing. The TSV wafer results reveal that the alkaline barrier slurry has an obvious effect on surface topography correction, and can be applied in TSV barrier CME