柴油机磨损状态监测及故障诊断专家系统知识库建立的研究

实践表明，为了确保机器的安全运行，避免突发性故障，对其实施磨损状态监测和故障诊断是十分必要的。尽管铁谱技术和光谱技术等在这方面的应用都比较成功，然而它们也各有其局限性。为了把机器的磨损状态监测和故障诊断技术推向更高的科学水平，在摩擦学系统的系统工程思想指导下，针对柴油机的“拉缸”和“拉瓦”故障，并且根据故障发生之前润滑油结构变化的各种信息，利用专家系统开发工具ＥＸＳＹＳ，建立了基于铁谱技术和光谱技术的柴油机磨损状态监测及故障诊断专家系统ＦＤＥＸＳＹＳ（Ｖ１．０）知识库；对该专家系统的测试和实际运行结果表明，所建立的知识库可以比较全面而可靠地描述柴油机的磨损状态及故障前兆，因而能够提醒用户适时采取有效措施以防止故障的发生。不仅如此，所述专家系统知识的获取方法、知识的分类表示及匹配方法等研究，对建立其它摩擦学系统的故障诊断专家系统都具有参考意义。     

（Ca,Mg）—Sialon陶瓷在空气及水润滑条件下的磨损机理研究

利用ＳＲＶ球－盘磨损试验机考察了一种（Ｃａ，Ｍｇ）－Ｓｉａｌｏｎ陶瓷在空气及水中的摩擦学性能，并采用ＥＰＭＡ，ＳＥＭ，ＥＤＡＸ以及ＸＰＳ等分析手段对其磨损机理做了进一步研究。结果表明：（Ｃａ，Ｍｇ）－Ｓｉａｌｏｎ陶瓷在水中比在空气中具有更低的摩擦因数，但具有较高的磨损体积损失。     

EAPPROXIMATE INERTIAL MANIFOLDS FOR THE SYSTEM OF THE J-J EQUATIONS

ＡＰＰＲＯＸＩＭＡＴＥＩＮＥＲＴＩＡＬＭＡＮＩＦＯＬＤＳＦＯＲＴＨＥＳＹＳＴＥＭＯＦＴＨＥＪ－ＪＥＱＵＡＴＩＯＮＳＡＰＰＲＯＸＩＭＡＴＥＩＮＥＲＴＩＡＬＭＡＮＩＦＯＬＤＳＦＯＲＴＨＥＳＹＳＴＥＭＯＦＴＨＥＪ－ＪＥＱＵＡＴＩＯＮＳ￥ＣａｉＲｉｚｅｎｇ（...     

On the (1, 3) distributions of limit cycles of plane quadratic systems

ＯＮＴＨＥ（１,３）ＤＩＳＴＲＩＢＵＴＩＯＮＳＯＦＬＩＭＩＴＣＹＣＬＥＳＯＦＰＬＡＮＥＱＵＡＤＲＡＴＩＣＳＹＳＴＥＭＳＬｉｎＸｉａｏ－ｌｉｎ（蔺小林）（ＮｏｒｔｈｗｅｓｔＩｎｓｔｉｔｕｔｅｏｆＬｉｇｈｔＩｎｄｕｓｔｒｙＸｉａｎｙａｎｇ）Ｄａｎｇｘｉｎ...     

ON THE STABILITY OF FORCED DISSIPATIVE NONLINEAR SYSTE

ＯＮＴＨＥＳＴＡＢＩＬＩＴＹＯＦＦＯＲＣＥＤＤＩＳＳＩＰＡＴＩＶＥＮＯＮＬＩＮＥＡＲＳＹＳＴＥＭ￥ＣｈｅｎＤａｄｕａｎ（陈达段）ＬｉｕＸｉａｏｍｉｎｇ（刘晓明）ＳｈｉＷｅｉｈｕｉ（施惟慧）（ＳｈａｎｇｈａｉＵｎｉｖｅｒｓｉｔｙ．Ｓｈａｎｇｈａｉ２００...     

SOLUTIONS FOR A SYSTEM OF NONLINEAR RANDOM INTEGRAL AND DIFFERENTIAL EQUATIONS

ＳＯＬＵＴＩＯＮＳＦＯＲＡＳＹＳＴＥＭＯＦＮＯＮＬＩＮＥＡＲＲＡＮＤＯＭＩＮＴＥＧＲＡＬＡＮＤＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳ￥ＤｉｎｇＸｉｅｐｉｎｇ（丁协平）ＷａｎｇＦａｎ（王凡）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，Ｓｉｃｈ...     

THE BOUNDED EXTERMINATION AND STABILITY OF MUTUAL INTERFERENCE SYSTEM OF FOUR－DIMENSIONAL SPECIES

ＴＨＥＢＯＵＮＤＥＤＥＸＴＥＲＭＩＮＡＴＩＯＮＡＮＤＳＴＡＢＩＬＩＴＹＯＦＭＵＴＵＡＬＩＮＴＥＲＦＥＲＥＮＣＥＳＹＳＴＥＭＯＦＦＯＵＲ－ＤＩＭＥＮＳＩＯＮＡＬＳＰＥＣＩＥＳＨｏｕＧａｎ－ｓｈｅｎｇ（侯赣生）（Ｄｅｐｌ．ｏｆＰｈｙｓｉｃｓ,Ｊｉａｎｇｘ...     

A STUDY OF THE ELASTO－PLASTIC AXIALLY TENSILE PROPERTIES OF METAL MATRIX COMPOSITES WITH FIBER－END DEBONDING

ＡＳＴＵＤＹＯＦＴＨＥＥＬＡＳＴＯ－ＰＬＡＳＴＩＣＡＸＩＡＬＬＹＴＥＮＳＩＬＥＰＲＯＰＥＲＴＩＥＳＯＦＭＥＴＡＬＭＡＴＲＩＸＣＯＭＰＯＳＩＴＥＳＷＩＴＨＦＩＢＥＲ－ＥＮＤＤＥＢＯＮＤＩＮＧＳｕＸｉａｏｆｅｎｇ（苏晓风）ＣｈｅｎＨａｏｒａｎ（陈浩然）（...     

AISI304钢表面低电压等离子体基离子注入层摩擦磨损性能研究

采用高频低电压等离子体浸没离子注入（ＨＬＰＩＩＩ）技术对ＡＩＳＩ３０４不锈钢表面进行了氮离子注入处理;用球－盘摩擦磨损试验机考察了注入处理后钢表面改性层的摩擦磨损性能;用扫描电子显微镜（ＳＥＭ）、俄歇电子能谱仪（ＡＥＳ）和Ｘ射线衍射（ＸＲＤ）考察了改性层的相组成、Ｎ元素的深度分布及磨损机理。研究结果表明：ＨＬＰＩＩＩ处理能够显著提高样品的摩擦学性能,且其摩擦学性能对温度有较大的依赖性,４００℃下处     

On the existence of harmonic solutions for higher-order Lienard systems

ＯＮＴＨＥＥＸＩＳＴＥＮＣＥＯＦＨＡＲＭＯＮＩＣＳＯＬＵＴＩＯＮＳＦＯＲＨＩＧＨＥＲ－ＯＲＤＥＲＬＩＥＮＡＲＤＳＹＳＴＥＭＳＤｏｎｇＱｉｎｘｉ董勤喜,ＨｕａｎｇＸｉａｎｋａｉ黄先开（ＲｅｃｅｉｖｅｄＪｕｌｙ４．１９９４,ＣｏｍｍｕｎｉｃａｔｅｄｂｙＦ...     

An adaptive open boundary condition

A significant improvement of the open boundary condition which was originally studied by Engquist and Majda is given. The method given here is applicable without limitation of the angle between the direction of the incident wave and the normal to the boundary. It also improves the precision of the method from order one to two. The test examples show that this method is much better than the method mentioned above. Inst. of Software, Academia Sinica     

Moment Boundary Conditions in Rarefied Gas Slip-Flow Problems

Two novel models of boundary conditions: diffusive-moment and reflective-moment, generalizing the well-known Cercignani boundary conditions, are proposed. The models take into account the possibility of the different moments of the distribution function being accommodated in different ways and independently of each other. This is impossible in both Maxwell's reflective-diffusive model and the Cercignani model. It is shown that both models approximate Maxwell's reflective-diffusive conditions for slip-flow problems correct to 1%.     

Minimum drag shape in two-dimensional viscous flow

The problem of finding the shape of a body with smallest drag in a flow governed by the two-dimensional steady Navier-Stokes equations is considered. The flow is expressed in terms of a streamfunction which satisfies a fourth-order partial differential equation with the biharmonic operator as principal part. Using the adjoint variable approach, both the first- and second-order necessary conditions for the shape with smallest drag are obtained. An algorithm for the calculation of the optimal shape is proposed in which the first variations of solutions of the direct and adjoint problems are incorporated. Numerical examples show that the algorithm can produce the optimal shape successfully.     

40×40mm方截面双层爆轰激波管的改造

为开展边界物理和几何条件对气相爆轰波传播影响的系统研究，需要对已有的４０×４０ｍｍ方截面双层爆轰激波管进行改造．实验要求在同一管道中安装堵塞物以改变边界的几何条件又能用多孔材料替代刚性管壁以改变边界的物理条件，且二者的改变互不影响．改造后的管道要能分别采集爆轰波在通过上述两种不同的边界时压力变化的数据和提供胞格结构的烟迹记录．在爆轰和气体动力学理论指导下，在原有的管道上加接一段自行设计的测试段，达到了预定的要求．     

On the application of slip boundary condition on curved boundaries

Hydrodynamic simulations of sloshing phenomena often involve the application of slip boundary condition at the wetted surfaces. If these surfaces are curved, the ambiguous nature of the normal vector in the discretized problem can interfere with the application of such a boundary condition. Even the use of consistent normal vectors, preferred from the point of view of conservation, does not assure good approximation of the continuum slip condition in the discrete problem, and non‐physical recirculating flow fields may be observed. As a remedy, we consider the Navier slip condition, and more successfully, the so‐called BC‐free boundary condition. Copyright © 2004 John Wiley & Sons, Ltd.     

Numerical study of aerosol particle deposition in simple and converging-diverging micro-channels with a slip boundary condition at the wall

The design of micro-devices involving aerosol transport requires the study of the deposition of aerosols in micro-channels. In this study, the slip and no-slip boundary conditions for the gas flow regime were applied to the Navier-Stokes equations to obtain the particle deposition in simple and converging-diverging micro-channels. The equation of particle motion included inertial, viscous, Brownian, and gravity terms. It was found that the ratio of gravity to inertial effects controls the deposition of particles with diameters of 0.1-1 μm, and the ratio of diffusion to inertial effects controls the deposition of particles with diameters of 0.01-0.001 i~m. Comparison between the no-slip and slip flow regimes showed that the deposition of 0.1- to 1-μm-diameter particles was less and the deposition of 0.01- to 0.001-1μm-diameter particles was greater for the slip flow regime. There was no significant difference between slip and no-slip flow regimes for the deposition of 0.01- to 0.1-μm-diameter particles. Finally, it was shown that the stagnated gas in the corners of the converging-diverging micro-channel produced similar gas velocity profiles under the slip and no-slip flow regimes.     

龙游大型古地下洞室群1～5号洞水文地质与工程地质条件研究

一个超浅埋大型古地下洞室群于1992年在浙江省龙游县被四个农民发现。该洞室群的发现引起了各方面专家和学者的广泛关注。但从发现至今已出现了多种破坏现象,如顶板脱落、洞间壁坍塌、柱子拉张或剪切破坏以及由于渗水导致的洞室围岩的干湿交替引发的风化现象等等。本文从工程地质调查入手,对龙游古地下洞室群的工程地质条件、水文地质条件等进行了分析,为下一步的保护工作提供地质基础。     

Modelling of heat transfer by conduction in a transition region between a porous medium and an external fluid

We study the modelling of purely conductive heat transfer between a porous medium and an external fluid within the framework of the volume averaging method. When the temperature field for such a system is classically determined by coupling the macroscopic heat conduction equation in the porous medium domain to the heat conduction equation in the external fluid domain, it is shown that the phase average temperature cannot be predicted without a generally negligible error due to the fact that the boundary conditions at the interface between the two media are specified at the macroscopic level.Afterwards, it is presented an alternative modelling by means of a single equation involving an effective thermal conductivity which is a function of point inside the interfacial region.The theoretical results are illustrated by means of some numerical simulations for a model porous medium. In particular, temperature fields at the microscopic level are presented.Roman Letters _sf interfacial area of thes-f interface contained within the macroscopic system m² - A _sf interfacial area of thes-f interface contained within the averaging volume m² - C _p mass fraction weighted heat capacity, kcal/kg/K - g vector that maps to _s , m - h vector that maps to _f , m - K _eff effective thermal conductivity tensor, kcal/m s K - l _s,l _f microscopic characteristic length m - L macroscopic characteristic length, m - n _fs outwardly directed unit normal vector for thef-phase at thef-s interface - n outwardly directed unit normal vector at the dividing surface. - R ₀ REV characteristic length, m - T _i macroscopic temperature at the interface, K - error on the external fluid temperature due to the macroscopic boundary condition, K - T ^* macroscopic temperature field obtained by solving the macroscopic Equation (3), K - V averaging volume, m³ - V _s,V _f volume of the considered phase within the averaging volume, m³. - _mp volume of the porous medium domain, m³ - _ex volume of the external fluid domain, m³ - _s , _f volume of the considered phase within the volume of the macroscopic system, m³ - dividing surface, m² - x, z spatial coordinates Greek Letters _s, _f volume fraction - ratio of the effective thermal conductivity to the external fluid thermal conductivity - ^* macroscopic thermal conductivity (single equation model) kcal/m s K - _s, _f microscopic thermal conductivities, kcal/m s K - spatial average density, kg/m³ - microscopic temperature, K - ^* microscopic temperature corresponding toT ^*, K - spatial deviation temperature K - error in the temperature due to the macroscopic boundary conditions, K - ^* _i macroscopic temperature at the interface given by the single equation model, K - spatial average - ^s , ^f intrinsic phase average.     

Numerical investigations of radial jet reattachment flows

A finite volume computational scheme to solve the Navier-Stokes equations for the laminar flow fields of partially enclosed axial and radial jets impinging on a flat plate has been devised and tested. This scheme is based on the SIMPLEC technique. However, because of the backflow at the ‘outflow’ boundary, the SIMPLEC pressure correction technique has to be modified. The need for this modification, necessitated by the convergence failure, showed the ‘hidden’ pressure boundary condition of SIMPLE-type techniques. Test computations with the present scheme for flows in a channel with a built-in cylinder show that the location of the exit boundary affects very slightly the separated flow behind the cylinder. Computed Squire jet flows compare quite well with the available analytical solution. Finally, impinging radial jets have been computed for different Reynolds numbers. The results show the critical Reynolds number below which a steady solution is obtained and above which periodic and eventually chaotic flows result.