Simulation of frequency nonselective mobile channel with LOScomponent: a deterministic approach

A deterministic digital simulation model with finite sum of properly weighted sinusoids is used to simulate a frequency nonselective mobile channel with LOS component. Measurement data are used to optimise the parameters. Which are then used in the deterministic simulation model. The probability distribution and level cross rate (LCR) obtained from the measured data agree well with the analytical and simulation results     

Mesopore development in PAN-ACF resulting from non-metal additives

The narrow pore-size distribution of activated carbon fibres (ACF) limits their application in the fields concerning larger molecules, such as liquid adsorption and catalyst support. On the addition of carbon particles and organic materials to polyacrylonitrile fibres, and after stabilizing and activating, the mesoporosity in the resultant ACF has been obviously increased. Among these additives, carbon black gives the best effect. With 1 wt% carbon black I in precursor and on activating at 880°C for 30 min, a mesoporosity of 48.2% (total pore volume 0.704 ml g-1, mesopore volume 0.340 ml g-1) has been obtained. The mechanism of mesopore formation is also discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

Design of finite-length metal-clad optical waveguide polarizer

The performance of optical metal-clad waveguide polarizers is analyzed in this paper with a view to optimizing the extinction ratio, a condition for which power of the TM mode is completely attenuated is identified here. In general, such a condition corresponding to an infinitely high extinction ratio can be met for a wide range of buffer layer thicknesses by selection of metal film thickness and polarizer length. When a very thick (e.g., semi-infinitely thick) metal film is used, the aforementioned condition can be met with a properly chosen buffer layer thickness and polarizer length. The numerical results show that all the polarizers designed here for realization of infinitely high extinction ratios have either quite low or reasonably acceptable attenuations for the TE mode     

Vector-entropy optimization-based neural-network approach to imagereconstruction from projections

In this paper we propose a multiobjective decision making based neural-network model and algorithm for image reconstruction from projections. This model combines the Hopfield's model and multiobjective decision making approach. We develop a weighted sum optimization based neural-network algorithm. The dynamical process of the net is based on minimization of a weighted sum energy function and Euler's iteration, and apply this algorithm to image reconstruction from computer-generated noisy projections and Siemens Somatson DR scanner data, respectively. Reconstructions based on this method is shown to be superior to conventional iterative reconstruction algorithms such as the multiplicate algebraic reconstruction technique (MART) and convolution from the point of view of accuracy of reconstruction. Computer simulation using the multiobjective method shows a significant improvement in image quality and convergence behavior over the conventional algorithms     

关于解决黄牛鞋面革松面问题的探讨

本文讨论了在黄牛鞋面革生产过程中产生松面的原因，并经过多年的生产实践，摸索出解决松面问题行之有效的技术措施。     

Apoptosis in the early stage of compensatory renal growth following uninephrectomy in the young and old rats

Myostatin (GDF-8) is a member of the transforming growth factor-beta superfamily and plays a role in muscle growth and development. Mice having targeted disruption of this gene display marked increases in muscle mass, a phenotype similar to the muscular hypertrophy (mh) in several cattle breeds. Physical mapping data developed from YAC clones indicate the bovine myostatin gene lies close to the centromere of bovine Chromosome (Chr) 2 (BTA2) at 2q11, indistinguishable from the cytogenetic location of the mh locus. In addition, a polymorphism in the second intron of the gene was used to show that myostatin maps within the interval previously shown to contain mh. These data suggest myostatin may be the gene causing muscular hypertrophy in cattle.     

中原油田深井大井眼段钻井液工艺

濮深8井是中原油田在西部洼陷南部寻找接替储量的一口重点深探井,也是中原油田第一口井深达6000m的超深井。分析了濮深8井钻井液的配备及维护和处理技术,得出深井大井眼段钻井液工艺技术存在以下问题:井眼大,钻井液量及钻屑量多,处理时间长,处理剂用量多,处理频繁;返速低使钻井液清洗井眼的能力减弱;井下温度高使处理剂的作用明显降低,二氧化碳的侵入使钻井液性能变差。钻井液维护处理的较好方法是定时、定量补充处理剂胶液。固相控制是深井大井眼段钻井液工艺中的关键问题,必须配套并且有效地使用固控设备,以维护好钻井液性能。     

华北油田鄚东地区深井钻井液技术

鄚东地区钻井过程中经常发生垮塌、卡钻、井漏等复杂事故。该地区深井钻井采用了抑制性及封堵性较强的铵基沥青树脂高密度钻井液体系,并根据地层特点,对不同井段制定了相应的钻井液维护处理措施。结果表明,该钻井液体系抑制性好,抗温、抗污染能力强,性能稳定,成功地控制了复杂事故的发生,满足了该地区深层钻井的要求。     

四种别藻蓝蛋白三聚体的时间分辨荧光光谱研究

研究了从Ａｎａｂａｎａｖａｒｉｂｉｌｉｓ中提取的４种别藻蓝蛋白ＡＰＣＩ，ＡＰＣＩＩ，ＡＰＣＩＩ及ＡＰＣＢ三聚体的稳态光谱和皮秒荧光光谱。采用Ｍｏｎｔｅ－Ｃａｒｌｏ方法对瞬态荧光光谱进行拟合，实验结果表明：ＡＰＣＩ荧光有两个带，其中第一个带位于６６２ｎｍ，有两个时间组分：３５．８ｐｓ和１．６７ｎｓ；第二个带位于６８０ｎｍ，有两个时间组分：３４．２ｐｓ和１．６４ｎｓ；ＡＰＣＩＩ瞬态荧光位于６６０ｎｍ，有两个时间组分：２０．４ｐｓ和１．６４ｎｓ；ＡＰＣＩＩ瞬态荧光位于６６０ｎｍ，有两个时间组分：２３．８ｐｓ和１．７６ｎｓ；ＡＰＣＢ瞬态荧光有两个带，其中第一个带位于６６２ｎｍ，有两个时间组分：３６．６ｐｓ和１．４５ｎｓ；第二个带位于６８０ｎｍ，有两个时间组分：２５．８ｐｓ和１．６２ｎｓ。实验结果一方面说明了藻胆体核内４种别藻蓝蛋白形成能量传递的两条途径；另一方面瞬态荧光解叠结果揭示了ＡＰＣＩ和ＡＰＣＢ三聚体内能量传递的超快过程。     

判断油气藏非均质性的新方法

非均质性是油气藏的基本特性,也是影响油气面采收率的重要因素.它是反映油气藏的渗透率、孔隙度、有效厚度及其连通性的综合特征参数.不同油气藏在投入开发后,其产量随时间变化的分布曲线与油气藏自身的非质均性有密切关系.利用伽马分布描述油气藏产量随时间的变化,研制了典型曲线的理论图版,通过拟会求解,可判断油气藏的非均质程度.