基于LVM 的系统扩容技术研究

近年来,随着大数据业务的使用,系统在运行时会产生大量的数据信息与日志文件并保存在磁盘中。由于在系统规划初期,对系统分区大小规划预期不足,很难合理规划磁盘空间,造成后期系统运行中经常出现系统分区磁盘不足的问题。当发生此类告警时,通常的分区很难动态调整大小,通常采用暂停业务,更换磁盘,数据备份与恢复的方式,该方式操作困难,程序复杂,有数据丢失的风险。在Linux系统里使用LVM(逻辑卷)技术,支持在线空间扩容,可以在用户无感知的情况下扩展系统分区容量,达到合理利用磁盘空间的目的。本文介绍了LVM技术,并在Linux系统里将分区做成逻辑卷,达到合理利用磁盘空间的目的。     

Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal

This paper aims to improve the accuracy and applicability of gas diffusion mathematical models from coal particles. Firstly, a new constitutive model for gas diffusion from coal particles with tri-disperse pore structure is constructed by considering the difference in characteristics between soft coal and hard coal.The analytical solution is then derived, that is, the quantitative relationship between gas diffusion rate(Qt/Q_∞) and diffusion time(t), The pore structure parameters of soft coal and hard coal from Juji coal mine are determined. Gas diffusion rules are numerically calculated and investigated by physical simulation methods. Lastly, the applicability of this model is verified. The results show that the homogeneous model only applies to the gas diffusion process of hard coal during the initial 10 min. The calculation results from this model and the physical experimental results of soft coal and hard coal are nearly identical during the initial 30 min.     

双向中继信道中Polar码与物理层网络编码的联合设计

为解决双向中继信道中采用低密度奇偶校验码LDPC(low density parity check code)或Turbo码的网络编码系统信道编码编译码算法及设备的复杂度太高这一问题,提出一种联合Polar编码与网络编码的中继转发策略.该策略利用无线通信中信号的叠加特性和Polar编码、网络编码的线性性质直接估计网络编码的码字,使得中继节点进行Polar译码的复杂度和信源节点之间的信息交换时间都比直接网络编码系统减少了50%.同时,由于基于信道极化理论的Polar码具有在离散无记忆信道BDMC(binary discrete memoryless channel)上达到信道容量及编译码算法简单等优点,使得所提方案不仅保证了系统的可靠性,而且更容易实现.仿真结果验证了该方案的有效性.     

采用4-WFRFT和人工噪声的变换域通信物理层安全传输

为了提高变换域通信(TDCS)信号的物理层安全性,提出了一种基于4项加权分数阶傅里叶变换(4-WFRFT)和人工噪声的TDCS信号加密方式。首先利用4-WFRFT代替传统TDCS中的DFT/IDFT,改变了TDCS信号的空间分布,在保持原系统复杂度的同时增加了TDCS信号的抗截获性,在此基础上使用人工噪声进一步增强系统的安全性,最后推导了非法用户理论误码率以及系统保密容量。仿真结果表明,无论是全频谱或是频谱失配情况下,采用当参数 在[0,0.8)或(1.7,4]的范围内时,窃听者误码率始终保持在0.5,无法正确解调发送信号,同时系统保密容量也为正数,有效保证了信息的安全传输。     

基于显著性分析的气缸盖结构优化设计

为了改变缸盖的结构,提高气缸盖运行工况下的温度分布及结构可靠性,进行了以鼻梁区宽度等六组参数为设计变量、以其许用范围约束条件、以等效热应力最低为优化目标的汽缸盖结构优化。基于正交实验法,构建了6因素5水平的正交实验表,并建立相应的三维模型,仿真得到了温度场及热应力。通过均值化法去量纲,分析得到了各因素的显著性水平,基于各因素的显著性水平选取了最优方案,并进行对比。结果表明,优化尺寸优选后方案的最大热应力比原始结构降低了13.48%,为缸盖的结构设计提供了一定的参考。     

Stability analyses of vertically exposed cemented backfill:A revisit to Mitchell's physical model tests

Mitchell's solution is commonly used to determine the required strength of vertically exposed cemented backfill in mines. Developed for drained backfill, Mitchell model assumed a zero friction angle for the backfill. Physical model tests were performed. Good agreements were obtained between the required strengths predicted by the analytical solution and experimental results. However, it is well-known that zero friction angle can only be possible in terms of total stresses when geomaterials are submitted to unconsolidated and undrained conditions. A revisit to Mitchell's physical model tests reveals that both the laboratory tests performed for obtaining the shear strength parameters of the cemented backfill and the box stability tests were conducted under a condition close to undrained condition. This explains well the good agreement between Mitchell's solution and experimental results. Good agreements are equally obtained between Mitchell's experimental results and FLAC3 D numerical modeling of shortterm stability analyses of exposed cemented backfill.     

提升试验设计与数据处理教学效果的研究与实践

结合试验设计与数据处理教学实践,提出了提升其教学效果的几点体会。认为在本课程的教学中,强调课程学习重要性、激发学生学习热情,以注重实用性,优化教学内容,不断改进教学方法,加强实践教学和计算机技术应用将有利于提升该课程的教学效果。     

高校教师亚健康状况分析与对策研究

为了解我校教师的亚健康状况,采用问卷法和统计法调查研究我校教师的亚健康与运动现状。结果表明,亚健康的症状和发生机制与机体运动不足有关。因此加强亚健康与运动的宣传教育,提高教师的兴趣和热情,让更多的人进行体育锻炼,是预防和控制亚健康,恢复健康的最佳途径。     

拖拉机液压悬挂系统模糊控制的研究

该文对拖拉机液压悬挂系统的模糊控制器进行了设计，采用MATLAB软件进行了仿真分析，并进行了试验研究，结果表明模糊控制对液压悬挂系统控制是适应的，对改善拖拉机作业质量提供了可靠的理论和试验依据。     

An Innovative Methodology for the Performance Evaluation of Coated Cemented Carbide Inserts in Milling of Inconel 718

The performance of cemented carbide inserts coated with various PVD-films in milling Inconel 718 is evaluated by innovative analytical and experimental methods. Three PVD films with different micro and macro structures were applied. The coatings’ strength properties were detected by nanoindentations and by impact tests at various temperatures. These results were considered in FEM calculations of the material removal process to determine the mechanical and thermal loadings of the cutting wedge. Employing this innovative methodology, it is possible to capture proactively the effect of the cutting conditions on tool wear, thus reducing the effort dedicated in traditional sequential cutting experimentation.