基于FDI算法在软件测试实践中的应用

软件测试对于软件系统的性能以及功能都有很重要的意义,是保证软件可靠运行的关键.在软件测试的实践应用中,对于软件故障定位时,提出了基于谓词统计故障定位的算法,也就是FDI频率差异积分算法.在软件测试实践中采用基于FDI频率差异积分算法,可以很好地监控软件程序,测试软件的覆盖率以及执行时间等内存占用情况,并找到软件的故障瓶颈,以便采取更好的方法改进软件性能.探讨了实践中基于FDI频率差异积分算法在软件测试内的应用.     

Quantum analysis of measurement results

It is shown that a stochastic matrix operator (quantum measurement matrix) may be considered in some cases as a density matrix. Results of measurements in the form of figure numbers, interconnected with a matrix of quantum measurements, are similar to quantum observable quantities determined in quantum statistical theory. __________ Translated from Izmeritel’naya Tekhnika, No. 12, pp. 3–8, December, 2006.     

High Order Finite Difference Approximations of Electromagnetic Wave Propagation Close to Material Discontinuities

Electromagnetic wave propagation close to a material discontinuity is simulated by using summation by part operators of second, fourth and sixth order accuracy. The interface conditions at the discontinuity are imposed by the simultaneous approximation term procedure. Stability is shown and the order of accuracy is verified numerically.     

worth和worthy的用法辨析

“worth”和“worthy”都有“值得的”含义。但用法却有所不同。使用时应加以区别、辨识。     

大型燃煤锅炉热偏差的试验与数值研究

针对安徽省平圩发电厂 2号炉过热器和再热器的热偏差 ,主要从烟气侧提出改造方案 ,利用数值模拟方法 ,在保留四角切圆燃烧方式优点的前提下 ,提出反复“起旋”、“消旋”的燃烧器喷口布置方式 ,以达到、维持炉内稳定的弱旋状态 ,从而来解决热偏差的问题。     

Determination of surface heat-transfer coefficients of steel cylinder with phase transformation during gas quenching with high pressures

In numerical simulation of quenching process, the boundary conditions of temperature field and stress field are very important, in which the boundary conditions of temperature field are very complicated. In order to simulate the thermal strains, thermal stresses, residual stresses and microstructure of the steel during gas quenching by means of the numerical method, it is necessary to obtain an accurate boundary condition of temperature field. The surface heat-transfer coefficient is a key parameter. The explicit finite difference method, non-linear estimate method and the experimental relation between temperature and time during quenching have been used to solve the inverse problem of heat conduction. The relationships between surface temperature and surface heat-transfer coefficient of cylinder have been given. The non-linear surface heat-transfer coefficients include the coupled effects between phase transformation and temperature. In calculation, physical properties were treated as the function of temperature and volume fraction of constituent. The results obtained have been shown that this technique can determine effectual the surface heat-transfer coefficients during gas quenching.     

Sensitivity of spectral reflectance to variation in live fuel moisture content at leaf and canopy level

Wildland fires burn large areas of the earth's land surface annually, causing significant environmental damage and danger to human health. In order to mitigate the effects, and to better manage the incidence of such fires, fire behaviour models are used to predict, among other things, the likelihood of ignition, the rate of spread, and the intensity and duration of burning. A key input parameter to these models is the amount of water in the vegetation, described as the fuel moisture content (FMC). A number of studies have shown that vegetation indices (VI) calculated from red and NIR reflectances may be used to map spatial and temporal variation in FMC in a range of fire-prone environments, with varying degrees of success. Strong empirical relationships may be established between VI and FMC over grasslands, yet over shrublands and forests, the relationships are weaker. If FMC is to be estimated with greater accuracy and consistency than is currently achieved, it is necessary to fully understand the relative contribution that spatial and temporal variation in the various biophysical and geometrical variables make to reflectance variability at the leaf and canopy level.This paper uses a modelling approach to investigate the sensitivity of reflectance data at leaf and canopy level to variation in the biophysical variables that are used to compute FMC. At the leaf level, the results show that the sensitivity of reflectance to variation in leaf water and dry matter content, used to compute FMC, is greatest in the SWIR and NIR, respectively. Variation in FMC has no effect in the visible wavelengths. At the canopy level, the results show that the sensitivity of reflectance to variation in leaf water and dry matter content is heavily dependent upon the type of model used and the range of variation over which the variables are tested. In the longer wavelengths of the SWIR, the competing influence of variable leaf area index, fractional vegetation cover, and solar zenith angle is shown to be greater than that at the shorter wavelengths of the SWIR and NIR. Empirical relationships between the normalised difference water index (NDWI) and FMC are shown to be weaker than that with canopy water content. However, when the range of the variables under study is more limited, useful empirical relationships between FMC and remotely sensed VI may be established.     

High order finite difference methods for unsteady incompressible flows in multi-connected domains

Using the vorticity and stream function variables is an effective way to compute 2-D incompressible flow due to the facts that the incompressibility constraint for the velocity is automatically satisfied, the pressure variable is eliminated, and high order schemes can be efficiently implemented. However, a difficulty arises in a multi-connected computational domain in determining the constants for the stream function on the boundary of the “holes”. This is an especially challenging task for the calculation of unsteady flows, since these constants vary with time to reflect the total fluxes of the flow in each sub-channel. In this paper, we propose an efficient method in a finite difference setting to solve this problem and present some numerical experiments, including an accuracy check of a Taylor vortex-type flow, flow past a non-symmetric square, and flow in a heat exchanger.