基于任务同步及节能的单机系统实时动态调度算法

提出了一种基于任务同步及节能的单机系统实时混合动态调度算法(HDSA), 以有效解决能耗及实时任务同步时的优先权反转所导致的缺乏实时可调度性的问题.HDSA包含静态算法及动态算法两部分.静态算法可在静态条件下, 固定临界区的运行速度, 并求出非临界区部分的静态速度. 动态调度算法在实际运行中, 在满足周期性任务实时可调度性及任务同步的条件下, 充分利用及回收任务运行时剩余的执行时间, 调节处理器的速度, 以有效降低能耗.同时也能避免高优先权任务被阻塞时, 低优先权任务的临界区继承高优先权任务的速度所造成的处理器电压开关的频繁切换, 故能有效地降低实时任务调度的成本.实验测试表明HDSA在调度性能上明显优于相关的有效算法.     

一种基于隐马尔可夫模型的多目标方位自动跟踪方法

方位-幅度-时间图(方位瀑布图)是声呐检测设备一种基本的显示图像。方位瀑布图由于在视觉上起着时空积分作用,可提供的信息量很大,声呐兵可通过观察长时间的目标方位轨迹来检测弱目标。本文在这种思想下应用隐马尔可夫模型和Viterbi算法,提出了一种自动提取方位轨迹的方法。计算机仿真研究表明这种方法是简单可行的。     

基于动态时间弯曲的轨道波形匹配方法

轨道平直度测量仪(简称平直尺)是轨道短波检测项目中非常重要的检测工具。由于平直尺测量范围有限,为了分析轨道短波的变化规律,需对所测波形进行匹配处理。首先对所测数据进行坐标转换,将待匹配数据统一在同一坐标系。传统匹配算法只能对坐标系内的曲线进行刚性的变换和匹配,无法解决不同坐标系下曲线的动态匹配问题。基于此提出了动态时间弯曲算法(DTW),通过对时间轴的弯曲和变形,找到最短弯曲路径,以及待匹配曲线间的单点对应关系,通过计算最短弯曲路径可衡量匹配的好坏。本文利用平直尺对标准铁轨进行实际测量,并将传统算法中常用的基于区域的匹配算法同动态时间弯曲法进行对比。实验结果表明,利用动态时间弯曲法可实现短波的动态匹配,匹配精度比传统匹配算法提高约10倍,匹配误差较小,稳定性较好。     

生成正多边形和圆的新算法

针对正多边形各顶点坐标的计算,构造了新的递推公式并加以证明。以新公式为基础给出了正多边形和圆生成算法,并对算法误差进行了分析。计算正多边形每个顶点需要两次乘法和两次加法,优于目前＂多边形逼近法＂所采用的顶点计算方法。算法具有构造简单、执行速度较快和精度高的特点。理论分析和上机验证算法可行,完全可以满足常规的应用。     

浅析P、V原语理论及其应用

尽管用锁变量、TS指令等方法可以实现进程之间的互斥,但这几种方法都有违背进程互斥访问临界区的条件,均存在影响系统可靠性和执行效率的问题。例如,循环测试锁定位将损耗较多的CPU计算时间,违背进程访问临界区条件:等待临界区时,释放CPU。如果并发进程数较多,且由于每个进程在申请进入临界区时都得对锁定位进行测试,这种开销是很大的。用P、V原语不但可以更好地解决进程管理中的互斥问题,而且我们还可以利用此方法解决进程同步与进程通信的问题。     

素数因子算法的FFT处理器的设计

为满足FFT运算速度的要求,提出了一种易于FPGA实现的素数因子算法FFT处理器的硬件结构。其中数据存储采用了乒乓RAM结构来实现,可以扩大吞吐量;数据缓存使用FIFO来实现,可以减少一半存储空间的使用;运算模块使用素数因子算法结合流水线结构,在一定延迟后可以连续输出结果;增加地址排序映射可以实现数据正序输入输出。     

面向网络数据实时检测的多线程内存管理技术

针对目前内存管理算法在多线程环境下存在的问题,提出了一种新的面向网络数据实时检测系统的多线程内存管理算法MLMalloc.MLMalloc算法采用线程局部内存区的方式解决了在多线程环境下内存锁的频繁竞争问题;预先在线程局部区和全局内存区分配大量内存,减少了在线程局部内存区、全局内存区和系统内存区之间的内存获取和归还抖动;线程局部内存区和全局内存区由固定大小的内存堆构成,在两种内存区之间采用预测的方式,一次锁操作分配或归还多个堆,减少了对内存区锁的竞争次数.实验结果表明,MLMalloc算法显著地提高了多线程环境下大规模网络数据实时检测系统内存操作的效率.MLMalloc算法的性能要优于PTMalloc算法和TCMalloc算法,并且运行线程的数目越多,性能提高的幅度越大.     

二阶锥规划的非精确不可行内点法

二阶锥规划在工程、控制、金融等领域具有广泛的应用.本文研究一种求解二阶锥规划的非精确不可行内点法.该算法的基本思想是首先定义不可行中心路径及其邻域,然后通过求解一个非线性方程组得到非精确的搜索方向,再取一个合适的步长,使得新的迭代点落在不可行中心路径的邻域内.该算法不要求初始点和迭代点位于严格可行解集内.在适当的假设条件下证明了算法只需迭代O(√n ln(1ε))次就可以找到问题的ε-近似解.     

基于动态时间规整的钢轨轨廓匹配方法

钢轨轨廓的精准匹配是研究其几何形态变化的重要前提。由于轨检小车行进时产生随机振动,引起传感器振动,导致采集数据失真。在测量过程中,因无法保证传感器绝对对称,故每个传感器的振动存在一些差异性。传统的特征点算法只能对振动引起的噪声进行刚性补偿,且有时特征点提取不到。基于此,提出动态时间规整算法,从初步匹配的数据中,选取标准轨廓和测量轨廓轨腰处数据作为两个时间序列,建立距离矩阵,通过对时间轴的扭曲变形,利用递归思想,计算累积代价矩阵,得到最优规整路径,从而找到两个时间序列各点的对应关系,实现轨廓的精准匹配。实验结果表明,相比特征点算法,动态时间规整算法的匹配精度提高了近7倍,匹配效果较好,稳定性很高。     

基于安全芯片的AES算法掩码方案研究

任何防御对策的目标都是使密码设备的能量消耗不依赖于设备所执行的密码算法的中间值,掩码技术通过随机化密码设备所处理的中间值来实现这个目标。这种方法的一个优点是它可以在算法级实现,并且无需改变密码设备的能量消耗特性。也就是说,即使设备的能量消耗具有数据依赖性,掩码技术也可以使设备的能量消耗与所执行的密码算法的中间值之间无依赖关系。本文讨论掩码技术的工作方式并设计一种AES算法的掩码方案。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.