Numerical simulation of thermal flying height control sliders in heat-assisted magnetic recording

Heat assisted magnetic recording (HAMR) is one of the most promising techniques to extend the recording density in hard disk drives beyond 1?Tb/in². Although the diameter of the spot on the disk that is heated by the laser beam is very small, on the order of nanometers, high local temperatures on the disk and the heat dissipated in the slider during the light delivery process can cause thermal deformations of both the disk and the slider, thereby affecting the flying characteristics at the head-disk interface. In this paper, a finite element model is developed which incorporates a HAMR optical system into a thermal flying height control (TFC) slider with dual heater/insulator elements to study the effect of heat dissipation in the wave guide on the thermal deformation and flying characteristics of a HAMR-TFC slider. In addition, the power input of the laser and design parameters of the heaters are investigated.     

基于有限元法的斜齿轮齿条啮合接触分析

通过Solidworks软件建立了斜齿轮齿条模型.采用有限元法和Solidworks Simu-lation有限元软件计算最恶啮合接触区域以及齿轮齿条啮合时齿根上最大的弯曲应力和接触区域上的接触应力.通过理论经验计算应力公式与有限元法计算的应力值相比较,以验证通过最恶啮合接触区域计算接触应力的可行性.     

MSMSE-based optimal beamforming design and simplification on AF MIMO two-way relay channels

An optimal cooperative beamforming for the amplify-and-forward (AF) MIMO two-way relay channels was designed. Supposing the channel state information (CSI) was perfectly known by the receiver and transmitter as well as the relay, optimal beamforming vectors (matrices) of all nodes were jointly designed based on the criterion of minimizing the sum mean square errors (MSMSE). The analysis result shows that the performance effect of transmitting and receiving beamforming pairs is to maximize the receive signal-to-noise ratio (SNR) at two communication nodes, and the rank of the optimal relay beamforming matrix is no larger than two when there is only one data stream at each source node. A simplified algorithm was put forward to accomplish the design based on the analysis conclusions. Simulation results provide that the system performance, which is characterized in terms of bit error rates (BER), is significantly improved by cooperative beamforming, and the performance of the simplified method is not only very close to the optimal one but also with faster iteration speed and much lower computational complexity.     

一种自适应Huffman算法在无线传感器网络数据压缩中的应用

针对无线传感器网络中数据压缩的问题,提出了一个基于时空相关性和Huffman编码的数据压缩算法,并在传输的比特数和压缩比方面与静态Huffman方法进行了比较。实验结果表明,所提出的算法执行效果更好。     

银川市浅层地温场分布特征及其控制因素探讨

为了探讨银川市浅层地温场分布特征及影响浅层地温场的控制因素,采用自动和人工相结合的方法对银川市90~200 m地温监测孔进行监测.数据显示,200 m以内浅层平均地温梯度一般为1.5~4℃/100 m,高地温带呈NNE向展布于银川市区中部,形态分布与该区重要隐伏活动断裂走向基本一致.研究表明,银川张性断裂是银川市浅层地温场分布的控制因素,是造成浅层地温异常的主要因素.     

Keccak算法非线性变换x的分析

x是keccak算法中唯一的非线性部件,本文研究了x变换的主要密码学性质,指出了x的非线性度为8,差分均匀度为8,代数次数为2,满足平衡性,可逆。计算出了x的逆变换的表达式,并分析了其密码学性质。基于x变换的设计思想,我们试图找到新的方法来构造分组密码中的S盒。     

生物黑炭的施加对连云港滨海盐碱土的改良作用

为了了解生物黑炭的施入对连云港滨海盐碱土的改良效果,采用田间试验研究了生物黑炭施入量对盐碱土土壤性状及小麦温室气体排放量的影响。结果表明,生物黑炭施入对中度盐化滨海盐碱土具有改良作用,土壤pH从8．1降为7．78,同时土壤微生物生物量碳含量最高增加了81．80％。利用静态箱法测定了生物黑炭还田对小麦N2O排放的影响。结果表明,与单施化肥处理相比,添加8和32t·hm-2生物黑炭处理的麦田N2O的排放量分别降低了46．24％和48．39％。综上说明,生物黑炭施入对该研究选择的连云港滨海盐碱土具有改良作用,并且减少了麦田温室气体的排放,具有一定的生态环境效益。     

奇偶间隔基短链双季铵膨润土的制备及结构表征

以六甲基丙二铵二甲硫酸盐(PDAS)和六甲基丁二铵二甲硫酸盐(BDAS)为改性剂制备奇偶间隔基短链双季铵有机膨润土,通过X-射线衍射(XRD)、红外光谱(FT-IR)、热分析(TG)和电镜(SEM/TEM)等手段表征其结构.结果表明,PDAS和BDAS改性膨润土层间距分别为1.380 nm和1.413 nm,两种双季铵盐在层间只能以单层平卧的方式排列;有机膨润土中,PDAS是分步分解的,BDAS是一步分解,PDAS和BDAS的开始热分解温度和最大质量损失率对应温度(tpeak)相比其季铵盐固体分别提高了15,30℃和30,80℃;PDAS和BDAS有机膨润土的表面形貌有明显差异.     

水利工程视频监控系统建设与技术支撑

结合国家防汛抗旱指挥系统二期工程视频监控系统初步设计,讨论水利工程视频监控系统建设的必要性,介绍水利工程视频监控系统的建设思路、基本结构及组成、系统主要特点,结合当前平台架构、云计算、物联网等IT领域最新技术的发展与应用,分析视频监控系统的发展方向和应用前景,为水利工程视频监控系统的建设提供技术参考.