Optimum block-adaptive learning algorithm for errorback-propagation networks

An optimum block-adaptive learning rate (OBALR) backpropagation (BP) algorithm for training feedforward neural networks with an arbitrary number of neuron layers is described. The algorithm uses block-smoothed gradient as direction for descent and no momentum term, but produces an optimum block-adaptive learning rate which is constant within each block and is updated adaptively at the beginning of each block iteration so that it is kept optimum in a sense of minimizing the approximate output mean-square error of the block. Several computer simulations were tested on learning a deterministic chaos time-series mapping. The OBALR BP algorithm not only overcame the difficulty in choosing good values of the two parameters, but also provided significant improvement on learning speed and descent capability over the standard BP algorithm     

热红外多光谱遥感技术金矿调查应用研究

根据航空遥感实验获取的TIMS图象,利用计算机图象处理主成分分析和去相关等方法,并依据TIMS成象机制,提取出花岗岩、斜长片麻岩以及粘土化、硅化等蚀变岩岩性和丰富的断层信息,结合金矿化带光谱特征,圈出金矿化异常区,同时TIMS图象也显示了该地区北北东向金矿成矿主断层控制金矿化的规律,现有分析成果表明热红外多光谱扫描仪所获得的图象数据在岩性和金矿化带的识别上,以及增强断层信息方面有较好效果.     

The influence of light on the chroma of aviation kerosene

Influence of light on the chroma of low pressure hydrogenation aviation kerosene was studied using different lights (ultraviolet light, infrared light, sunlight and no light) in the same environment full of oxygen. UV light with short wavelength has the largest influence. Coloring substances were isolated by adsorption on neutral alumina followed by ether extraction and identified by using infrared spectrum, elemental analysis and two-dimensional GC-MS. Oxygen-containing compounds are main coloring substances. Light can provide the required energy to convert unsaturated hydrocarbons and heteroatom compounds to phenols, quinones and ketones.     

Characteristics of gaseous hydrocarbons generated from asphaltene pyrolysis and the geochemical significance

In order to study the mechanism of gas generation from the asphaltene, the thermal pyrolysis simulation experiment of the asphaltene is carried out by using high temperature and high pressure closed system. During asphaltene pyrolysis, the amount of methane is constantly increased but those of ethane, propane, and butane + pentane are all first increased and then decreased and eventually go to zero with the increase of the experiment temperature. And the dynamic parameters of gaseous hydrocarbon generation can be used to analyze the dynamic procedure of the asphaltene pyrolysis at the geological scale. The experimental results can perfect the theory of the origin of natural gas and provide an evidence for source judgment and resource evaluation of natural gas in marine strata in China.     

Strain effects in CdTe (111) epitaxial layers grown on GaAs (100) substrates by molecular beam epitaxy

Spectroscopic ellipsometry and photoreflectance measurements on CdTe/GaAs strained heterostructures grown by moleculclr beam epitaxy were carried out to investigate the effect of the strain and the dependence of the lattice parameter on the CdTe epitaxial layer thicknesses. Compressive strains exist in CdTe layers thinner than 2 μm. As the strain increases, the value of the critical-point energy shift increases linearly. These results indicate that the strains in the CdTe layers grown on GaAs substrates are strongly dependent on the CdTe layer thickness. Author to whom all correspondence should be addressed.     

Growth study of AlGaAs using dimethylethylamine alane as the aluminum precursor

We present a comprehensive study on the growth of AlGaAs by using an alternative Al precursor, dimethylethylamine alane (DMEAA), and a Ga coprecursor, either triethylgallium (TEG) or trimethylgallium (TMG). The growth rate of AlAs determined by using in situ reflectometry was studied as a function of the growth temperature, V/III ratio, growth pressure, and rotation speed of the substrate. The presence of gas phase reactions of DMEAA with arsine and TEG was indicated, and their reduction was achieved at a lower growth pressure, lower V/III ratio, or a lower growth temperature. Negligible pre-reaction of DMEAA with TMG was observed. Excellent material uniformity of AlGaAs was achieved on a 2″ diameter wafer. Secondary ion mass spectroscopy measurements revealed extremely low C and O contents in the AlAs layer grown by DMEAA. Photoluminescence measurements suggested the presence of some non-radiative defects in the as-grown DMEAA AlGaAs layers.     

检测数据触合算法分析

雷达组网反隐身目标探测技术是现代军事领域比较关注的一个问题,其中的多传感器数据融合技术又是一热点问题,因而有必要从概念和应用上对其进行了解并为检测数据融合算法的研究提供一个可参照的框架。为此,本文首先说明了多传感器下的检测问题和经典检测问题的相互关系,进而结合信息论的观点就近年来出现的一些典型检测融合算法进行了分析和比较,同时提出了其它可能的一些算法类型。最后,通过计算说明数据融合技术对探测系统的影响和对反隐身系统的重要意义。     

用红外热成像技术精确测定物体发射率

根据红外探测器对物体辐射的输出响应，从实际测量的角度提出了物体发射率的一般性定义，分析了红外热成像技术进行精确测量的条件，导出了物体温度Ｔｏｂｊ、环境温度Ｔｓｕｒ、物体发射率ηｏ和测量精度ｅ之间的关系，并建立了一套用红外热成像技术精确测定ηｏ的方法，实验表明该方法可获得满意的测量结果     

运用小型压裂测试确定储层参数新方法

在新区或低渗透油藏,需借助小型压裂测试来求取大型压裂设计所需参数,目前运用小型压裂测试闭合前的压力数据确定储层参数的误差较大,影响大型压裂的施工效果。为提高所需储层参数的准确度,利用小型压裂测试闭合后的压力数据,把小型压裂测试与试井分析理论相结合,建立了小型压裂测试闭合后压力分析的线性流和径向流的数学模型,利用点源函数、Homer法产量等效原则及Duhamel叠加原理,给出了其解析表达式,并提出了一套小型压裂测试闭合后压力分析的新方法,可以快速准确地确定油藏压力及油藏渗透率。通过现场实例,验证了该方法的准确性。     

塔河油田超深井井筒掺稀降粘技术研究

基于热量传递原理和两相流动理论,建立了井筒掺稀油降粘工艺中产液沿井筒流动与传热的热力学模型。计算了产液沿井筒的温度分布和压力分布,同时进行了不同掺稀条件下降粘的室内实验。运用该模型结合实验结果对塔河油田稠油井掺稀降粘效果进行了计算,分析了不同工艺参数对掺稀降粘效果的影响。结果表明,井筒掺稀油降粘工艺适合于含水率低于20%的油井,开式掺稀油反循环比开式掺稀油正循环生产更有利于提高降粘效果,塔河油田井筒掺稀降粘合理的掺稀比率为1:2至1:1。