在τ—ρ域用特征积分法反演层状介质的速度和密度

本文提出一种在τ-p 域内用特征积分法反演层状介质速度与密度的方法。该方法首先把有偏移距的地震资料变换到截取时间τ和水平慢度 P 域内,然后,对任取的二道平面波地震记录,分别用特征积分法反演波阻抗,再用这对波阻抗分离层状介质的速度和密度。文中讨论了误差对反演结果的影响,并对理论模型进行了试算,效果令人满意。     

Database considerations in manufacturing systems integration

This paper deals with ideas that could form a basis for manufacturing integration. In recent times more attention is being paid to the idea of applying artificial intelligence (AI) techniques to manufacturing. However, very little attention is being paid to the proper use of these techniques. This research work explores three basic ideas:

1. 1. Applications of the entity-relationship approach to knowledge representation.

2. 2. The basic philosophy of expert database systems and

3. 3. Integration of manufacturing systems from the above two concepts.

The approaches for 1 and 2 are explained with actual implementation experiences, while a framework for integration is proposed from a more philosophical perspective.     

Effect of nitrocarburizing on sulphide layer during nitrocarburizing-sulphurating treatment

Compared with the single sulphurating treatment, the duplex treatment of nitrocarburizing-sulphurating can more effectively improve the properties of steel such as friction-reducing, wear resistance and anti-scuffing. Under the same processing parameters, the sulphide layers were fabricated on the surface of CrMoCu alloy cast iron by single ion-sulphurating treatment and nitrocarburizing-sulphurating duplex treatment, respectively. Through the analysis of the sulphide, the effect of the nitrocarburizing on the fabrication of the sulphide layer was investigated. And the result shows that the fabrication of sulphide layer is promoted by the nitrocarburizing treatment.     

计算机网络安全体系的研究

首先,结合国内外同行的最新研究成果,我们将对网络系统中的不安全因素加以分析,并形式化地给出一个安全计算机网络系统的定义;然后将从理论上阐述一个基于OSI-RM体系的网络安全保护体系的模型,并讨论该安全保护体系在现有系统中的作用。     

Ignition of nickel in environments containing oxygen and chlorine

The mixed oxidation of nickel in gases containing both oxygen and chlorine has been investigated using the techniques of thermogravimetric analysis and examination of the corrosion products by scanning electron microscopy. Two regimes of corrosion behavior have been detected: one in which a protective oxide film is present and the rate of corrosion is controlled by the transport of the volatile products of the reaction between the gas phase and the oxide, and one in which the protective film is penetrated and corrosion occurs rapidly enough to result in the ignition of the specimen. The oxide corrosion products on the specimens after corrosion have characteristic morphologies, with the products of volatilization type corrosion consisting of large grains and the products of ignition type attack consisting of fine spherical particles. Ignition is a serious hazard in environments containing 0.25 pct or more Cl₂ and 4 pct or more O₂ by volume at temperatures between 1000 K and 1100 K, but is not produced by exposures at higher temperatures. A model based on the stability of the protective film in steady state corrosion is presented which can be used to predict the transition from volatilization to ignition type attack.     

纳滤膜技术及其应用的研究进展

随着膜技术的发展,20世纪80年代出现的纳滤膜弥补了反渗透与超滤之间的空白。纳滤膜(nanofiltration membrane,NF)又称“疏松型”反渗透膜。通常情况下,膜的截留相对分子质量界限为200~1 000。与截留相对分子质量相对应的膜孔径为1~3 nm,故将这类膜称为纳滤膜。纳滤膜可以截留糖类等低相对分子质量有机物和高价无机盐(MgSO4等),但对单价无机盐的截留率低(仅为10%~80%),具有相当大的透过能力。由于单价盐可以自由透过纳滤膜,使得膜两侧因离子浓度不同而造成的渗透压差远远低于反渗透膜。在相同通量条件下,纳滤膜所要求的驱动压力比反渗透膜要低得多。一般纳滤的操作压力为0.5~1.5 MPa。由于纳滤膜的这种独特分离性能,确定了它在水软化和低相对分子质量有机物纯化浓缩的地位。此外,纳滤膜能有效去除许多中等相对分子质量溶质,如消毒副产物的前驱物、残留农药和某些色素等,因而在水净化处理和脱色中得到广泛应用。     

Selective recognition in molecularly imprinted polymer and its chromatographic characterization for cinchonine

A molecularly imprinting polymer (MIP) was synthesized via bulk polymerization under different conditions using anti-ague drug cinchonine (CN) as template. Infrared spectra (IR) results show that the template CNand functional monomer α-methyl acrylic acid (MAA) formed complexes before polymerization and the structure of complexes was simulated by Hyperchem. The results indicate that there are hydrogen bond or ionic bond between functional monomer and template molecule in acetonitrile solution. The MIP made in cold-initiated photo-polymerization has higher separation performance than that in the therm-initiated polymerization. The separation of the isomers CN and cinchonidine (CD) can be successfully obtained when its separate factor α reaches 1.82. Scatchard analysis suggests that the MIP recognizing CN with two classes of binding sites. The partition coefficient Kd, 1 and apparent maximum number nmax, 1 of binding sites with high affinity are 131.43 μmol/L and 58. 90 μmol/g, respectively,while Kd, 2 and nmax, 2 of binding sites with low affinity are 2.32 mmol/L and 169.08 mmol/g, respectively.     

On the design of multiple key hashing files for concurrent orthogonal range retrieval between two disks

This paper concerns the following problem: given a set of multi-attribute records, a fixed number of buckets and a two-disk system, arrange the records into the buckets and then store the buckets between the disks in such a way that, over all possible orthogonal range queries (ORQs), the disk access concurrency is maximized. We shall adopt the multiple key hashing (MKH) method for arranging records into buckets and use the disk modulo (DM) allocation method for storing buckets onto disks. Since the DM allocation method has been shown to be superior to any other allocation methods for allocating an MKH file onto a two-disk system for answering ORQs, the real issue is knowing how to determine an optimal way for organizing the records into buckets based upon the MKH concept.

A performance formula that can be used to evaluate the average response time, over all possible ORQs, of an MKH file in a two-disk system using the DM allocation method is first presented. Based upon this formula, it is shown that our design problem is related to a notoriously difficult problem, namely the Prime Number Problem. Then a performance lower bound and an efficient algorithm for designing optimal MKH files in certain cases are presented. It is pointed out that in some cases the optimal MKH file for ORQs in a two-disk system using the DM allocation method is identical to the optimal MKH file for ORQs in a single-disk system and the optimal average response time in a two-disk system is slightly greater than one half of that in a single-disk system.