力的时间分量

用狭义相对论分析变质量系统的受力情况 ;在狭义相对论中 ,力有三个空间分量和一个时间分量 ,当物体质量发生变化时 。

无线传感器网络中基于时间分量的混合路由协议

在均匀分簇的基础上,分析了多簇群情况下单跳和多跳模型能量的有效性,给出了两种情况下计算最优簇首数目的算法.考虑到单一的路由模式会引起网络能耗不均衡,提出并改进了多簇群情况下利用时间分量的单跳和多跳相结合的混合模型.仿真结果表明,基于时间分量的混合通信模式在能量有效性和能耗均衡分配方面均优于单跳、多跳模式.

具有不同节点的复杂动态网络有限时间部分状态分量同步控制

针对一类由不同节点组成的复杂动态网络,提出了一种分散控制策略以实现有限时间部分状态分量同步(只考虑网络中每个节点的部分状态分量在有限时间内达到同步)。首先,为了方便理论分析及推导,引入了一个特殊对角矩阵来表述每个节点所需关注的状态分量。其次,基于此特殊对角矩阵,给出了有限时间部分状态分量同步的定义。与有限时间同步相比,有限时间部分状态分量同步更广泛。再次,结合控制理论以及有限时间稳定性定理,提出了分散控制策略使网络实现有限时间部分状态分量同步。最后,通过一个仿真例子,验证了控制方法的有效性与正确性。

场的总角动量张量的“时间”分量守恒的物理意义

本文通过把场对应成经典力学中的点粒子的集合，讨论了场的总角动量张量守恒定律中“时间”分量守恒的物理意义．对于自旋为零、自旋为和自旋为１的场得到了相同的结论：场的惯性中心速度矢量与时间ｔ无关．

直流分量时间常数对断路器非对称开断性能影响分析

从短路电流的有效值、燃弧时差、电弧能量等方面分析了直流分量时间常数对断路器非对称电流开断性能的影响,给出了非对称短路计算模型及计算方法。结果表明直流分量时间常数越大,短路电流中直流分量越大且衰减越慢,燃弧时差越大,电弧能量越大,电流过零时di/dt降低,TRV参数亦有所降低,且非对称电流开断时,直流分量时间常数增大将导致断路器的开断条件变得苛刻。

大直流分量时间常数下SF_(6)断路器开断能力

近年来,随着我国电网系统电压等级的逐步提高以及一次设备电抗和阻抗比值的增大,导致电网中短路电流直流分量的衰减时间常数逐渐增大,直接影响对电网系统起重要控制和保护作用的断路器开断能力,进而影响整个电网的安全运行。该文通过关于直流分量时间常数对短路电流和断路器开断性能影响的分析,同时结合工程实践,提出了一种压气式SF_(6)断路器能否成功开断较大直流分量时间常数的短路电流判别方法,并采用热态气流场仿真计算和试验方法,验证了该判别方法的合理性。结果表明,当系统短路电流直流分量时间常数从45 ms提高到120 ms时,363 k V SF_(6)断路器在非对称短路电流开断试验(T100a)中短燃弧时间减小0.5 ms,长燃弧时间增大2 ms,导致断路器的有效开断区间需要增加7%。对于压气式SF_(6)断路器,为了保证能够成功开断直流分量时间常数较大(120 ms或者更高)的长燃弧,断路器需要具有足够的有效开断区间,且在长燃弧开断点应具有2.5 m/s以上的分闸速度。该结论为判别电网中断路器在短路电流直流分量时间常数不断增大时能否安全可靠运行提供了一种科学且有效的方法。

奇时间(time-odd)分量对^(41)Ca性质的影响

发展了包括奇时间(time-odd)分量的三轴形变的RMF理论模型,采用包含σ和ω介子自相互作用以及微观质心修正的PK1有效相互作用,自洽考虑了由于奇A核中的耒配对的核子对时间反演不交性的破坏所导致的重子流,以41Ca为例,研究了奇时间分量对重子流以及原子核性质的影响．

一种SVPWM脉宽调制控制算法的理论探讨

从电压空间矢量和磁链空间矢量关系出发,通过对非零电压矢量相位及作用时间与磁链方向及幅值的关系分析,以及对零电压矢量作用时间与逆变器输出电压幅值的关系分析,提出了磁链时间分量和压频时间分量的概念,为SVPWM调制方法下的电压频率协调控制提供了理论依据和控制方法。在此理论基础上,给出了一种最为简单的SVPWM脉宽调制算法。

Prediction and Analysis of O_3 based on the ARIMA Model

The research conducted prediction on changes of atmosphere pollution during July 9, 2014-July 22, 2014 with SPSS based on monitored data of O3 in 13 successive weeks from 6 sites in Baoding City and demonstrated prediction effect of ARIMA model is good by Ljung-Box Q-test and R2, and the model can be used for prediction on future atmosphere pollutant changes.

铝穹顶储罐雷击损伤及燃爆风险研究

针对铝穹顶储罐雷击问题,开展了回击后长持续时间雷电流分量作用下的铝合金板烧蚀损伤试验研究,分析了铝穹顶储罐损伤及油气燃爆风险。结果表明:当直流分量为164 C时,2 mm铝板发生穿孔,铝穹顶储罐存在雷击燃爆风险;当直流分量≤157 C时,未穿孔,背面温度最高为480℃,存在燃爆风险,铝穹顶储罐存在雷击燃爆风险;当直流分量196 C时,4 mm铝板发生穿孔;当直流分量为196 C时,6 mm铝板未发生穿孔,背面温升为125℃,小于205℃,铝穹顶储罐不存在雷击燃爆风险。

北太平洋海气系统主要模态的年代际变化

结合北太平洋各种指数、海表温度和高度场,分析了北太平洋海气系统的突变特征及其与时间尺度分量的联系.研究结果表明:各种指数、海表温度和高度场在20世纪60年代、70年代和90年代末期均存在显著突变;海表温度60年代的突变主要分布于北太平洋北部,70年代的突变主要分布于北太平洋北部、中部和东南部,90年代突变则主要分布于北太平洋东南部和西南部;高度场突变主要分布于北太平洋北部、西北部和东南部,且突变范围从高层向低层递减.各种指数中60年代突变1～8a尺度分量的贡献较大,70年代突变是20～30a尺度分量的贡献较大,90年代的突变则是1～8a尺度和20～30a尺度分量作用相当.在3个突变时期中,海表温度和高度场的空间分布及相关性分析验证了这种联系的可能性.

Effects of Storage Methods and Time on Content of Nutrients in Biogas Slurry of Straw

To study the effects of different storage methods and time on content of nutrients in biogas slurry of straw, two storage methods were carried out on biogas slurry between open storage and airtight storage conditions at normal atmospheric temperature. The contents of N, P, K, and organic matter in biogas slurry of straw were determined in different storage times. The results showed that： during the pro-cess of biogas slurry storage, little change occurred in the content of the organic matter while the total content of N, P, K significantly declined; up to 50 days, the total content of N, P, K reduced to nearly 80%-90%. Because the contents of N, P, K in biogas slurry reduced less in airtight storage conditions so that a better re-sult was found on airtight storage methods than open storage methods in fertilizer field of biogas slurry of straw.

非傍轴矢量高斯光束的光强表示

基于瑞利-索末菲衍射积分,未使用任何近似,对非傍轴矢量光束的两种光强表示式,即传统光强公式和时间平均坡印廷矢量的z分量进行了研究。对非傍轴矢量高斯光束详细数值计算结果的比较表明,两种表示式之间的差异,即两者的相对误差与束腰宽度及传输距离和波长的比值有关。对非傍轴矢量高斯光束,若传输距离与波长的比值为10,束腰宽度与波长的比值大于等于0.8,则最大相对误差不到1.5%。因此,传统光强公式是可用的。

非傍轴矢量余弦-高斯光束两种光强表示的比较研究

从矢量瑞利-索末菲衍射积分公式出发,以非傍轴矢量余弦-高斯(CoG)光束为例,对非傍轴矢量光束的两种光强表示式,即传统光强公式和时间平均坡印廷矢量的z分量进行了比较研究.对非傍轴矢量CoG光束轴上和横向光强分布详细的数值计算和比较结果表明,两种光强表示式之间的相对误差η与w0/λ、z/λ和偏心参量b有关,其中w0,λ和z分别为束腰宽度,波长和传输距离.当偏心参量b较小,且束腰宽度与波长相比不很小时,例如,b≤0.8,w0/λ≥0.8,z/λ=10时,二者间的最大相对误差ηmax<2%,传统光强公式可以使用.

Distance-Dependent Long-Range Electron Transfer in Protein:a Case Study of Photosynthetic Bacterial Light-Harvesting Antenna Complex LH2 Assembled on TiO 2 Nanoparticle by Femto-Second Time-Resolved Spectroscopy

The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna complex assembled onto TiO2 nanoparticle with an average size of 8 nm in diameter. Crystal structure shows that photosynthetic bacterial antenna complex LH2 has a ring-like structure composed by alpha- and beta-apoprotein helices. The alpha- and beta-transmembrance helices construct two concentric cylinders with pigments bacteriochlorophyll a (Bchl a) and carotenoid (Car) buried inside the protein. We attempt to insert TiO2 nanoparticle into the cavity of the inner cylindrical hollow of LH2 to investigate the nature of the electron transfer between the excited-state Bchl a and the TiO2 nanoparticle. A significant decrease in the ground state bleaching recovery time constant for Bchl a at 850 run (B850) in respect to that of the Bchl a in free LH2 has been observed. By using the relation of distance-dependent long-range electron transfer rate in protein, the distance between the donor B850 and the acceptor TiO2 nanoparticle has been estimated, which is about 0.6 nm. The proposed method of assembling proteins onto wide-gap semiconductor nanoparticle can be a promising way to determine the role of the protein playing in biological electron transfer processes.

A Precision-Positioning Method for a High-Acceleration Low-Load Mechanism Based on Optimal Spatial and Temporal Distribution of Inertial Energy

High-speed and precision positioning are fundamental requirements for high-acceleration low-load mechanisms in integrated circuit （IC） packaging equipment. In this paper, we derive the transient nonlinear dynamicresponse equations of high-acceleration mechanisms, which reveal that stiffness, frequency, damping, and driving frequency are the primary factors. Therefore, we propose a new structural optimization and velocity-planning method for the precision positioning of a high-acceleration mechanism based on optimal spatial and temporal distribution of inertial energy. For structural optimization, we first reviewed the commonly flexible multibody dynamic optimization using equivalent static loads method （ESLM）, and then we selected the modified ESLM for optimal spatial distribution of inertial energy; hence, not only the stiffness but also the inertia and frequency of the real modal shapes are considered. For velocity planning, we developed a new velocity-planning method based on nonlinear dynamic-response optimization with varying motion conditions. Our method was verified on a high-acceleration die bonder. The amplitude of residual vibration could be decreased by more than 20% via structural optimization and the positioning time could be reduced by more than 40% via asymmetric variable velocity planning. This method provides an effective theoretical support for the precision positioning of high-acceleration low-load mechanisms.

两种卒中筛查量表在脑卒中院前急救筛查中的应用价值

目的探讨面、臂、言语、时间评分(FAST)量表联合改良洛杉矶院前卒中筛查量表(MLAPSS)在脑卒中院前急救筛查中的应用价值。方法选取2019年2月至2020年6月重庆市第四人民医院急诊120出诊转送入院的1913例疑似脑卒中患者作为研究对象,应用随机数字表法分为3组,FAST组进行院前FAST量表评估(638例),MLAPSS组进行院前MLAPSS评估(638例),联合组进行院前FAST量表联合MLAPSS评估(637例)。比较3组院前脑卒中筛查时间(到达现场至根据量表初步诊断时间)、转运时间(出诊至送入救治医院时间)、获得影像检查时间(出诊至入院影像检查时间)、临床确诊时间(出诊至神经内科确诊时间),以及3组院前量表评估与临床诊断结果的一致性、筛查脑卒中的效能、确诊脑卒中患者的伤残率和病死率。结果1913例患者中1507例临床确诊为脑卒中,406例为非脑卒中。MLAPSS组和联合组院前脑卒中筛查时间、转运时间均长于FAST组[(3.2±0.6)、(3.9±0.7)min比(1.0±0.3)min,(42±4)、(42±4)min比(41±4)min](均P<0.05),3组获得影像检查时间、临床确诊时间比较差异均无统计学意义(均P>0.05)。FAST量表和MLAPSS诊断与临床诊断结果一致性中等(Kappa=0.432、0.596,均P<0.01),二者联合诊断与临床诊断结果一致性较高(Kappa=0.795,P<0.001)。FAST量表联合MLAPSS评估院前筛查脑卒中的敏感度、特异度、阳性预测值、阴性预测值、准确率最高,漏诊率、误诊率最低。联合组确诊脑卒中患者伤残率低于FAST组和MLAPSS组[15.1%(76/502)比33.3%(168/504)、27.9%(140/501)](均P<0.01),3组确诊脑卒中患者病死率比较差异无统计学意义(P=0.081)。结论FAST量表联合MLAPSS院前筛查脑卒中可明显提高筛查准确率,减少漏诊和误诊,降低确诊脑卒中患者伤残率。

Oil–water two-phase flow pattern analysis with ERT based measurement and multivariate maximum Lyapunov exponent

Oil–water two-phase flow patterns in a horizontal pipe are analyzed with a 16-electrode electrical resistance tomography(ERT) system. The measurement data of the ERT are treated as a multivariate time-series, thus the information extracted from each electrode represents the local phase distribution and fraction change at that location. The multivariate maximum Lyapunov exponent(MMLE) is extracted from the 16-dimension time-series to demonstrate the change of flow pattern versus the superficial velocity ratio of oil to water. The correlation dimension of the multivariate time-series is further introduced to jointly characterize and finally separate the flow patterns with MMLE. The change of flow patterns with superficial oil velocity at different water superficial velocities is studied with MMLE and correlation dimension, respectively, and the flow pattern transition can also be characterized with these two features. The proposed MMLE and correlation dimension map could effectively separate the flow patterns, thus is an effective tool for flow pattern identification and transition analysis.

Investigation on Exciton Relaxation Kinetics of ZnCulnS/ZnSe/ZnS Quantum Dots by Time-Resolved Spectroscopy Techniques

The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots （QDs） is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dynamics shows that the intrinsic exciton, the exciton in the interface defect state and that in donor-acceptor pair state （DAPS） together participate in the photoluminescence process of QDs, and the whole emission process is mainly dependent on the DAPS emission. Transient absorption data show that the intrinsic exciton and the interface defect species maybe together appear after excitation and the intensity-dependent Auger recombination process also exists in QDs at high excitation intensity.

A new process monitoring method based on noisy time structure independent component analysis

Conventional process monitoring method based on fast independent component analysis(Fast ICA) cannot take the ubiquitous measurement noises into account and may exhibit degraded monitoring performance under the adverse effects of the measurement noises. In this paper, a new process monitoring approach based on noisy time structure ICA(Noisy TSICA) is proposed to solve such problem. A Noisy TSICA algorithm which can consider the measurement noises explicitly is firstly developed to estimate the mixing matrix and extract the independent components(ICs). Subsequently, a monitoring statistic is built to detect process faults on the basis of the recursive kurtosis estimations of the dominant ICs. Lastly, a contribution plot for the monitoring statistic is constructed to identify the fault variables based on the sensitivity analysis. Simulation studies on the continuous stirred tank reactor system demonstrate that the proposed Noisy TSICA-based monitoring method outperforms the conventional Fast ICA-based monitoring method.