沿任意方向运动多层介质分界面上电磁波的广义传播特征分析

利用静止和沿任意方向运动坐标系间的Lorentz变换矩阵,以及运动分层介质界面上的边界条件、电磁场的状态方程和本构关系,推导平面波入射下多层介质沿任意方向运动时电磁波的广义传播特征.分析沿某一坐标方向运动多层介质电磁波的矩阵传递关系,并将这种传播关系退化到半空间分层介质界面沿任意方向,或且当多层介质运动速度为零时,其传...     

Possible seismic reflector in the lower crust： Evidence from fabrics and experiments of seismic velocity on layered gabbro at high temperature and high pressure

Lattice preferred orientations (LPO) of plagioclase and augite are measured on layered gabbro from the Panxi region, Sichuan Province. The LPO concentration [010] of plagioclase and [100] of augite are perpendicular to the foliation, which indicates a kind of growth fabric associated with crystallizing habits of minerals when the magma is solidifying under the compaction. Calculated seismic velocities based on LPO data of minerals give rise to rather strong anisotropy 5.81% and 5.54% for compressional seismic wave (Vp) and shear seismic wave (Vs), respectively. The experiments at high temperature and high pressure show that the P-wave velocity of layered gabbro is 6.4-6.97 km/s with the maximum Vp anisotropy 5.22% and the Poisson‘s ratio is between 0.28-0.31. According to the comparison of fabrics with seismic velocities of layered gabbro, it is suggested that the large-scale layered intrusive body or the similar layered geological body may exist in the lower crust of this area. Such a layered intrusive body which has strong seismic anisotropy may be the seismic reflector in the lower crust.     

主成分分析在震动信号目标识别算法中的应用

为了改进基于震动信号的地面运动目标识别算法,提出了一种基于主成分分析（PCA）的2次特征提取算法.首先对地面运动目标引起的震动信号进行目标特性分析,提取多维的特征值;然后利用主成分分析方法对众多的特征值进行分析,去除特征值之间的相关性,提取综合特征值并应用于分类器,得到目标识别结果.基于实地采集的地面运动目标的震动信号进行实验,结果表明：该方法有效地减少了特征值的维数和相关性,降低了分类器训练的难度和训练时间,同时提高了目标的正确识别率.     

通讯槽对电磁波传播随钻测量信号的影响

采用径向成层介质的Green函数分析天线屏蔽罩上通讯槽的长度、数目等参数对电磁波传播随钻测量信号的影响规律。结果表明:增加通讯槽的长度和数目可降低电磁信号的衰减,但当这些参数增加到一定数值后信号的衰减不再明显变化;一般取通讯槽的长度约0.1 m、数目在20个以内即可满足工程实际需要;当填充材料的电导率较低时,其引起的电磁信号衰减可忽略不计。     

Propagation characteristics of arrayed transient electromagnetic pulses

Starting from the uniform disk current model, an analytical solution for the electromagnetic pulse axial energy radiation is derived and a physical meaning then given to the axial energy propagation characteristics of a unit antenna. From this solution, a point-source approximation model in the time domain is introduced. Parameters such as the energy propagation characteristics and beamwidth of the electromagnetic pulse beam radiating from arrayed antenna are analyzed theoretically. An arrayed transient electromagnetic pulse generator is developed incorporating a 23×16 ultra-wideband tapered slot antenna integrated with a Blumlein formation line and photoconductive semiconductor switch. Experiments performed over a 2.5 km range confirm that the arrayed transient electromagnetic pulse can propagate in free space with the specified waveform. Moreover, the field components can be superposed in phase, and the radiation beam can be focused into a single pulse. Results from calculations are in agreement with experimental results within the measurement uncertainties.     

Recent progress of deep seismic experiments and studies of crustal structure in northern South China Sea

The South China Sea (SCS) is one of the largest marginal seas in the western Pacific. Its northern part has the features of a passive continental margin. The studies of deep crustal structure in this area are very important for understanding the tectonic nature, evolution history, basin formation of the northern margin, and the origin of the SCS. In the past decades, the deep seismic experiments of crustal studies in the northern SCS have gone through three stages, namely the sonobuoy, two-ship Expanding Spread Profile (ESP), and Ocean Bottom Hydrophone/Seismometer (OBH/OBS). Along the continental slope, the sonobuoy experiments provided useful information about the velocity structure of the upper crust, while the ESP data recorded for the first time the seismic signals from deep crustal structure and Moho interface. And the OBH/OBS profiles revealed the crustal structure in much greater detail. This paper first gives a brief historical review of these deep seismic experiments and studies, then a summary of the latest progress and important research results. The remaining problems and suggestions for further research work are presented as conclusive remarks.     

Ability to detect weak effective seismic signals by utilizing chaotic vibrator system

Taking the advantage of CVS (Chaotic Vibrator System) sensitivity of large-scale periodic phase-state response to quasi-periodic or periodic signals,a series of numerical experiments were made to understand the ability of CVS to detect weak effective seismic signals in the common-shot seismic record distorted by strong stochastic noise. The re-sults demonstrate that the large-scale periodic phase-states of CVS are correlated with the signal composition of the quasi-periodic wavelet sequence constructing from horizontal moveout of seismic events,noise strength and the noise distortion de-gree to signal. For the same kind of events,the higher the noise distortion degree is,the lower the detectable SNR can be reached by CVS. For seismic data with the same noise distortion degree,the closer the scanning seismic velocity (the trial moveout ve-locity) approaches to the accurate velocity,the higher the detectable SNR can be reached by CVS. More-over,the truncating scanning velocities form an asymmetric belt,which indirectly makes CVS achieve a large-scale periodic phase-state and then the ratio of wavelet distortion coefficients in events can be a biggish variable scope.     

Analysis of electromagnetic pressure on thin plate melt

An equation used to calculate electromagnetic pressure for confining and shaping a plate-form melt with small or medium thickness is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and current frequency f, melt thickness a and electromagnetic parameter μγ . The main results can be summarized as follows: ( i ) As the f, a and μγ are large enough, causing the ratio of melt thickness to current skin depth a/ S to be larger than 2.2, p will be a constant ( p = 1) and the electromagnetic pressure can be calculated with Pm = B2/2λ. ( ii ) As the f, a, and μγare not large enough, and the ratio a/ 8 is less than 2.2, p is no longer a constant but changes from 1 to 0 with the decrease of a/δ. In this case, the value of electromagnetic pressure is determined not only by magnetic flux density 8 but also by the current frequency f, melt thickness a and electromagnetic parameter μγ.     

基于电磁信号导航的智能车系统设计与开发

运用嵌入式系统的开发方法,详细描述了一套基于电磁导航原理设计的智能车系统开发过程。系统设计目标是:在保证智能车不脱离运行轨道的前提下,速度尽可能地快。系统选取32位微控制器MK60DX256ZVLQ10为主控芯片,通过完整地设计并优化小车的硬件系统、软件系统和机械系统,最终实现了智能车通过自行检测轨道导线激发的电磁波自主循迹行驶。     

煤岩冲击矿压过程电磁辐射传播规律的研究

从电磁辐射MAXWELL方程出发,对煤岩冲击矿压过程中产生的电磁辐射在煤岩中的传播规律进行了分析与研究,提出对破裂过程电磁辐射在煤岩中的传播进行数值模拟时可将电磁辐射产生源理想化为水平电偶极子和水平磁偶极子的叠加;并得出了电磁辐射源产生的场在煤岩中空间分布的解析计算式,为冲击矿压等动力灾害预测的电磁辐射监测仪的研制和定向定位监测提供了理论和计算依据。     

化学实验教学中的学习迁移研究

分析了化学实验教学在化学教学中的地位和作用;指出当前化学实验教学中的定势的种种原因;阐明对“学习迁移”概念的理解;提出消除负迁移和促进正迁移的具体教学改进措施.     

平稳随机信号准确模型的研究

针对对平稳随机信号建立参数模型的常用信号处理方法，研究了信号建模的本质，给出了“准确模型”的定义，指出，对给定的平稳随机信号，以其不同阶次统计量建立的“准确模型”的输出信号与原信号并不相等，二者只是在相应的统计特征上相匹配。从这一概念出发，在总结了二阶统计意义下建模的一些主要结论后指出，平稳信号在二阶统计意义下总可以准确建模，证明了在三阶统计意义下并非所有的平稳过程均可准确建模，并给出了可准确建模的必要条件。     

食品工程原理实验报告探析

了解学生在食品工程原理课程实验报告中人数、性别、班别、分数组成的变化情况,每个实验项目按照6项内容分别评分,对实验报告构成的统计分析结果表明,女生总分成绩高于男生,女生在实验结果和讨论分析的变异系数大于男生,男生要加强改进实验建议环节,是提高分数的潜力。     

基于偏差传递的多工位装配过程质量评估模型

针对多工位装配系统中尺寸偏差传递的特点,建立了一种新的装配过程质量评估模型.首先分析了多工位装配系统的偏差源,研究了多工位装配尺寸偏差传递关系,构建了偏差流传递的状态方程.然后从过程系统本身寻找影响偏差传递和累积的特征参数来评价系统的装配质量特性,通过对尺寸偏差传递模型推导引出工位系数矩阵,经过合并变换求出各工位的系数矩阵的最大特征值,再乘以偏差精度权因子来建立装配质量评估模型,进而提出用装配偏差指数来衡量装配工艺过程的优劣.最后通过实际零件的装配过程说明该模型和装配偏差指数的应用方法.     

中华常春藤繁殖技术研究

本文报道中华常春藤繁殖试验研究结果。种子繁殖于4月中旬以腐殖土＋河沙为播种基质可获得78.50%-93.50%的发芽率；扦插繁殖于7－8月份采用顶部枝条作插穗，以肥泥＋河沙为基质进行扦插可获得87．50％－97．50％的生根率。     

电磁对偶广义毕奥-萨伐尔定律的初步讨论

从电磁学的毕奥-萨伐尔定律出发,然后利用矢势描写形式推导静态和非静态的毕奥-萨伐尔定律,并进一步研究推广到一般电磁源存在的情况,然后验证电磁场满足SO(2)电磁对偶性.     

新台糖25号组织培养及快速繁殖研究

本研究采用新台糖25号蔗株茎尖培养出绿苗和茎梢嫩叶诱导出愈伤组织,再分化出绿苗的方法,快速成功培育出了大批量绿苗.试验表明茎尖培养用MS 6-BA2.0mg·L-1 NAA0.3mg·L-1附加活性炭0.05%;MS 2,4-D1.0～3.0mg·L-1对诱导愈伤组织效果较佳,MS 6-BA1.0mg·L-1 KT1.0mg·L-1 NAA0.3mg·L-1对分化绿苗及其增殖效果最好;生根培养基选用1/2MS IBA1.0mg·L-1 NAA1.0mg·L-1,附加活性炭0.05%效果好.     

基于地震属性建模的数值模拟及其应用

为了解决花岗岩潜山储层内部结构复杂、非均质性强、在数值模拟建模过程中模型参数填充误差大的问题,本文提出了一种基于地震属性建模的数值模拟技术.该技术首先优选地震属性建立储层模型;然后采用波动方程的数值模拟方法对模型进行“正演+偏移”计算,并对比分析模拟得到的偏移剖面与原始地震剖面,逐步修正观测系统参数,直至两者的主要特征一致;最后,结合其他地震属性(如裂缝检测属性),综合分析目的层的地震响应特征.对渤海某区花岗岩储层的数值模拟结果表明,该方法有效地刻画了花岗岩“溶蚀孔隙+高角度裂缝”所形成的“率珠状”反射特征,为该区后续的勘探研究奠定了基础.利用本文提出的方法综合分析储层结构的地震波场特征是一种可行的方法,该方法除了应用于花岗岩储层的数值模拟外,还可以应用于其他复杂储层的数值模拟.     

海洋电磁勘探中空气波相互作用机制和水深影响分析

基于一维层状介质的电磁位和电磁场分析,采用电磁场的模式分解理论建立空气、海水层和海底地层之间的电磁场相互作用关系.以假想无限水深模型和五层介质模型为基础,导出水平电偶极子(HED)的横电(TE)和横磁(TM)模式的电磁场数学关系,分析空气波占优的临界偏移距随水深和海底地层电导率的变化规律,指出前人定义的300 m水深作...     

新型磁电阻尼器理论模型进一步研究

对新型磁电阻尼器恢复力理论模型做了进一步研究,将原有双参数模型即振动频率、运动幅值归一化为单参数速度幅值模型,两种模型与试验对比,结果表明改进的模型效果更好.为开发用于实际工程的产品及安装磁电阻尼器结构减振体系模拟计算打下了基础.