汶川地震前GPS资料反映的应变率场演化特征

对中国大陆东西向应变率场的研究结果表明,青藏块体西部(92°E以西)东西向拉张区和青藏块体东部(92°E以东)东西向挤压区反映了青藏高原物质东向流动受到了华北-华南地块的阻挡,形成了空间跨度约900 km的压缩区,3期应变率场结果均显示南北地震带中段位于东西向压应变率高值区。川滇地区应变率场结果表明,巴颜喀拉地块东向运动的增强导致了汶川地震震源区面应变率的集中;在东西向挤压高值区逐渐向东迁移的过程中,龙门山断裂带的东西向挤压变形逐渐增强;旋转率场动态演化结果表明,2004—2007年龙门山南段的逆时针旋转变形强度有所减弱,龙门山断裂带中北部的顺时针旋转变形有所增强;主应变率分布特征由散乱到一致的演化特征表明龙门山断裂带闭锁状态伴随着挤压和右旋剪切作用的增强达到了极高点。

S-R分解定理的张量表述及其率形式

目的研究S-R分解定理导出的应变率及旋转率,进一步完善S-R理论.方法以实方阵的对称、正交和分裂定理为基础,推导大变形、大转动情况下连续介质变形梯度张量的S-R分解定理,结合张量理论研究参数sinθ的本质及其在非笛卡尔坐标系下的计算公式,利用连续介质力学分析S-R分解定理前提条件、几何意义及由S-R分解定理导出的应变率和旋转率.结果由S-R分解定理导出的应变率、旋转率与通常使用的应变率、旋转率线性部分相同.结论将参数sinθ以张量形式表达可使S-R分解定理应用于非笛卡尔坐标系,同时需严格满足其前提条件.S-R理论体现了工程线应变、工程剪应变对应变张量S和局部刚体转动张量R的共同依赖性.

水泥稳定碎石基于旋转压实的压实次数与相关参数的研究

水泥稳定材料试件成型方法多种多样,本文采用旋转压实仪成型试件,故利用旋转压实试验研究旋转次数与试件的含水量、干密度及7d无侧限强度等相关参数的关系。结果证明相同的压实次数,水泥用量越多,试件的干密度、含水率及无侧限抗压强度越大。随着旋转压实次数的增加,各试件的参数也呈现一定的规律。

拓扑不变量在电力系统混沌特征分析中的应用

在电力系统混沌特征研究中引进了一种全新的方法即拓扑不变量的分析思想。首次将拓扑不变量的概念应用于电力系统混沌特征分析之中,并利用Poincare截面绘制系统分叉图,抽取各周期轨道,提取倍周期分叉和混沌状态的拓扑不变量——局部交叉数、相对旋转率、链接数,进而研究系统敏感参数和初值的变化对拓扑不变量的影响。,它可作为动态系统状态检测和故障诊断的依据,从而为该领域的研究提供一条新思路,仿真计算证明了该方法的可行性和有效性。

基于改进L系统的树木模拟技术

分析了L系统的文法系统和树木枝条的力学模型,将改进的L系统与枝条力学模型相结合,模拟了重力和趋向性对于树木枝条形状的影响,通过visual studio8对算法进行实现,更为有效的生成了自然逼真的三维树木。

模拟机运动系统及软件剖析

针对飞行模拟机运动载荷系统中平台质心处的线加速度的算法进行了剖析,并就液压伺服作动筒的伸缩长度与飞机特定力和飞机转动率之间的关系进行了分析。提出了运动方程建模的依据,探讨了模拟机六自由度运动系统在软硬件上的合成原理,为飞行模拟机液压伺服控制在运动系统过载保护性能方面的改善及研究打下了基础。

视频自跟踪系统目标动态特性分析

形状、尺寸、运动方向、旋转方向和光辐射强度等变化是航天测控视频自跟踪系统目标的重要动态特性。定义目标在视频自跟踪系统传感器平面中心坐标系中的目标运动方向和法线方向的两个方向数,把目标投影与目标运动弹道联系起来;并定义由A·和E·正交形成的传感器平面坐标系,把目标在视频自跟踪系统传感器平面上的运动方向与目标运动弹道联系起来,且给出了解析算法;用这些方法对飞行试验实际数据进行了仿真模拟和初步分析。

ESPRIT-Based Feature Extraction of Helicopter Acoustic Signal

Aim To extract harmonic frequencies of helicopter acoustic signal as features for hel icopter identification. Methods Estimation of signal parameters via rotational invariance techniques(ESPRIT) was selected to extract harmonic frequencies from really measured helicopter acoustic signal and an algorithm based on the SVD TLS was used. Results ESPRIT correctly extracted harmonic frequencies of helicopter using the data of limited length under the variousflight conditions. Conclusion ESPRIT is an effective method of extracting harmonic frequencies and using harmonic frequencies of helicopter acoustic signal to recognize helicopter is feasible.

An estimation of the penetration rate of rotary drills using the Specific Rock Mass Drillability index

The main purpose of the present study was to provide a practical, convenient drillability prediction model based on rock mass characteristics, geological sampling from blast holes, and drill operational factors. Empirical equations that predict drill penetration rate have been developed using statistical analyses of data from the Sarcheshmeh Copper Mine. Seven parameters of the rock or rock mass, including uniaxial compressive strength （UCS） of the rock, Schmidt hammer hardness value, quartz content, fragment size （dso）, alteration, and joint dip, are included in the model along with two operational parameters of the rotary drill, bit rotational speed and thrust. These parameters were used to predict values of the newly developed Specific Rock Mass Drillability （SRMD） index. Comparing measured SRMD values to those pre- dicted by the multi-parameter linear, or nonlinear, regression models showed good agreement. The cor- relation coefficients were 0.82 and 0.81. resoectively.

Ozonation of o-phenylenediamine in the presence of hydrogen peroxide by high-gravity technology

The study herein investigated the effectiveness of simultaneous use of ozone and hydrogen peroxide(O_3/H_2O_2 process) to degrade o-phenylenediamine(o-PDA) in a simulated wastewater. A rotor–stator reactor(RSR) was employed to create a high-gravity environment in order to enhance ozone-liquid mass transfer rate and possibly improve the degradation rate of o-PDA. The degradation efficiency of o-PDA(η) as well as the overall gas-phase volumetric mass transfer coefficient(KGa) were determined under different operating conditions of H_2O_2 concentration, initial o-PDA concentration, temperature of reaction, initial p H and rotation speed of RSR in attempt to establish the optimal conditions. Chemical oxygen demand reduction rate(rCOD) of wastewater treated at a particular set of conditions was also analyzed. Additionally, the intermediate products of degradation were identified using a gas chromatography-mass spectrometer(GC/MS) to further evaluate the extent of o-PDA degradation as well as establish its possible degradation pathway. Results were validated by comparison with those of sole use of ozone(O_3 process), and it was noted that η, KGa and rCODachieved by O_3/H_2O_2 process was 24.4%,31.6% and 25.2% respectively higher than those of O_3 process, indicating that H_2O_2 can greatly enhance ozonation of o-PDA. This work further demonstrates that an RSR can significantly intensify ozone-liquid mass transfer rate and thus provides a feasible intensification means for the ozonation of o-PDA as well as other recalcitrant organics.

Characteristics analysis of a novel centralized-driving flip-flow screen

During screening operation, blinding or clogging of screen perforations generally occurs to reduce the sieving capacity and efficiency. Recently, the flip-flow screening has been widely recognized as a feasible method to deal with the problem. In this paper, a novel centralized-driving flip-flow screen(CFS) was developed for the separation of fine and moist coal, and the key structures, namely, a centralized-driving mechanism and a quasi-circle beam mounted with the mat were designed for high reliability and stability. By means of a test on an experimental prototype, the effect of some factors, i.e., initial stretch and hardness of the polyurethane panel, respectively, and the rotation speed of the driving motor on the kinematic characteristic of the screen surface was investigated. Results show that without an initial stretch, the sieve mat generates the largest vibratory amplitude while the slacker the sieve mat initially is, the smaller amplitude it will accomplish. And an increase in the rotation speed could cause a rise in the vibratory amplitude. Unlike the two factors, the hardness does not have a definite effect on the kinematic performance, on which a further study is required. Finally, screening processing on a laboratory prototype was conducted to draw the conclusion that the developed CFS also has a high sieving efficiency for the fine and moist coal.

Superfluid Fermi Gases in a Rotating Anharmonic Trap

The quadrupole mode frequency, the monopole mode frequency, and the critical rotational frequency for stirring a single vortex nucleation along the BEC-BCS crossover are obtained. The results show that, in a rotating anisotropic anharmonic trap, the quadrupole mode frequency and the critical rotational frequency for stirring a single vortex nucleation are modified significantly when the system crosses from the BEC side to the BCS side： the anisotropy of the trap induces a downshiff of the quadrupole mode frequency and the critical rotational frequency and helps the vortex formation in the system, while an anharmonic trap induces an upshift of the quadrupole mode frequency and the critical rotational frequency and suppresses the vortex formation in the system.

Synchronization for the Environment of OFDM Cooperative Communications Based on Preamble Design and Phase Rotation

Timing and carrier frequency offset estimation are critical issue for OFDM cooperative communications. In view of the complexity and high accuracy requirement, 1/2 and 1/4 pilot symbol cycle CAZAC sequence structures are defined as the pilot frequency sequence. Estimation within one symbol cycle is carried out through averaging samples of two neighboring symbol cycles, after which the operation is expanded to all the symbol cycles in one band group. Taking multipath effect into account, the concept of phase rotation is proposed for a further step. Adjust the phase difference of estimated symbols by phase rotation, and cross estimation could be done. Meanwhile, timing scheme works within one cycle training sequence. Theoretical and simulation analysis indicate that CRLB does not only relate to estimation symbol length, but also be influenced by phase difference of estimation symbols seriously. In the condition that the length of estimation is fixed, the bigger the phase rotation angle is, the smaller the CRLB is. The complexity of proposed algorithm is less than full cycle average estimation method for almost 50%. Meanwhile, the estimation accuracy is approximate with the full cycle average estimation method as well. Timing scheme with the defined preamble structure is also proposed. Simulation proves its efficiency.

Interactive Optimization of Impressive Parameters Middling in Biological Leaching

In this study, single and interactive effect of three parameters, pH, ferrous and pulp concentration has been investigated by a 2^3 full factorial CCRD （central composite rotatable design） composed of eight factorial points, six central and six axial points. Initially, ＂none＂ mode from transformation subsection was chosen as the default choice for both responses, i.e. %recovery and gram of recovered zinc. Box-Cox plots give the best Lambda for each response （y^Lambda= f （A, B, C .....）） which occur at 1.91 and 2.16 for %recovey and gram of recovered zinc, respectively. A linear （y^1.91 = f （linear）） and a quadratic （y^2. 16= f （quadratic）） equation were suggested by software as the model for %recovery and gram of recovered zinc, respectively. Analysis of variance （ANOVA） for both models shows a high coefficient of determination （R^2）. In order to optimize and find the best conditions under which three parameters occur appropriately, optimization was done numerically. Desirability plots indicate properly that the best conditions occur at pH = 1.46, ferrous = 6.67 g/L, %pulp = 7.1 （%w/v）, %recovery = 86.5, gram of recovered zinc = 0.63 g and desirability = 0.777. Finally, PRP （progressive route of the process） analysis donates us a proper insight of what is happening during these 30 days. PRP analysis categorizes flasks in two parts, 1- flasks worth economically, 2- flasks with one-time-usable feed materials.

Modeling Abrasion Forces in a Pneumatically Powered Grinding Tool Using Compressible Large Eddy Simulation

This paper describes the design of a new kind of miniature abrading sphere, which is magnetically mounted inside a spherical gap and set in rotation pneumatically with air. Large eddy simulation is performed in conjunction with the compressible Smagorinsky model. Minimal temperature variation allows for the assumption of adiabatic walls. Fluid-solid interaction is modeled using the law of the wall for compressible turbulent flow. A parametric study is done to determine optimal geometric layout while taking physical restrictions into account. The resulting optimal configuration is then examined in detail in order to determine demands to be met by the computerized control of the magnetic bearing as well as to quantify the force available to the abrasion process. Finally, a mathematical relation is given that determines available abrasion force depending on standard volumetric flow rate and rotation frequency. The findings presented here provide a basis for further development of smaller versions of the tool.

Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller

A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved.In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption.

User Preference Survey on Staircase Rotation

Staircase is an important means of vertical transportation. Staircase design exerts a great influence on the aesthetics, transportation efficiency, user comfort and experience level. In this paper, a survey on the staircase rotation preference was conducted, based on the environment behavior studies. Different user frequencies of a pair of scissors stairs in the 2nd teaching building of North China University of Technology were analyzed. The psychological effect was evaluated and quantified, and the user preference on the two staircase rotations was then withdrawn. The survey found that the type of staircase with clockwise upstairs was much more preferred （78%） than the other staircase rotation anti-clock upstairs. Considering different genders, the female shows a 66% higher preference inclination of this type of staircase rotation than the male. To improve the transportation efficiency of the staircase in case of fire, the result of this paper can be very constructive for the evacuation staircase rotation choice for the high-rise buildings.

固定剂量率旋转调强治疗直肠癌临床疗效

目的 剖析直线加速器固定剂量率旋转调强(IMAT)在直肠癌放射治疗中的使用实际效果,研究运用IMAT放射治疗计划方案,替代容积旋转调强(VMAT)放射治疗计划方案的实际运用。方法 选取天津市第四中心医院2019年3月—2020年1月收治的22例直肠癌患者为研究对象,对每例患者分别设计IMAT放疗计划与VAMT放疗计划。观察两种计划靶区评估情况、危及器官剂量学参数、治疗时间和机器跳数。结果 两种计划适形指数比较差异无统计学意义(P>0.05);VMAT放疗计划均匀性指数明显优于IMAT放疗计划,差异有统计学意义(P<0.05)。两种计划危及器官剂量学参数比较,差异均无统计学意义(P>0.05)。VMAT放疗计划治疗时间和机器跳数均明显优于IMAT放疗计划,差异有统计学意义(P<0.05)。结论 虽然在目前的临床直肠癌治疗方面,VMAT放疗计划在直肠癌放疗中整体疗效优于IMAT放疗计划,但是他们的作用机理和由于照射导致的身体各部分的器官危害本质上是没有变的,不过也是可以通过这种调强技术,减少治疗所需要的时间、开展更有效地术后护理等,所以说在一定程度上可以应用IMAT放疗计划代替VMAT放疗计划。

Counter-Rotating Type Pump-Turbine Unit Stabilizing Momentarily Fluctuating Power from Renewable Energy Resources

It is difficult for renewable energy resources to provide constant power with excellent quality for the grid system. This serial research proposes a power stabilization system with a pumped storage to guarantee power quality and capacity, while the outputs from the energy resources are at unstable and/or fluctuating conditions. The power stabilization system with a counter-rotating type pump-turbine unit was prepared and operated at the pumping and the turbine modes. The unit composed of the tandem impellers/runners connected to the inner and the outer armatures of the unique motor/generator. The experiments have verified that this type pump-turbine unit is reasonably effective to stabilize momentarily/instantaneously the fluctuating power from the renewable energy resources.

FY-4 Meteorological Satellite

FY-4 is the second generation of Chinese geostationary satellite for quantitative remote sensing meteorological application. The detection efficiency, spectral bands, spatial and time resolution have been greatly improved with respect to those of first generation, as well as the radiometric calibration and sensitivity. The combination of multichannel detection and vertical sounding was first realized on FY-4, because both the Advanced Geostationary Radiation Imager(AGRI) and Geostationary Interferometric Infrared Sounder(GIIRS) are on the same spacecraft. The main performance of the payloads including AGRI, GIIRS and Lightning Mapping Imager, and the spacecraft bus are presented, the performance being equivalent to the level of the third generation meteorological satellites in Europe and USA. The acquiring methods of remote sensing data including multichannel and high precision quantitative observing, imaging collection of the ground and cloud, vertical observation of atmospheric temperature and moisture, lightning imaging observation and space environment detection are shown. Several innovative technologies including high accuracy rotation angle detection and scanning control, high precision calibration, micro vibration suppression, unified reference of platform and payload and on-orbit measurement, real-time image navigation and registration on-orbit were applied in FY-4.