一类非线性双曲方程整体弱解的存在性和不存在性

利用势井方法研究四阶非线性双曲方程utt-△utt-α△ut=g(u)的初边值问题整体弱解的存在唯一性、渐近性和不存在性。     

具有正负系数中立型时滞微分方程的振动性

考虑中立型时滞微分方程：［ｘ（ｔ）－Ｒ（ｔ）ｘ（ｔ－ｒ）］′＋Ｐ（ｔ）ｘ（ｔ－τ）－Ｑ（ｔ）ｘ（ｔ－σ）＝０其中Ｐ，Ｑ∈Ｃ（［ｔ０，∞），Ｒ＋］），Ｒ∈Ｃ（［ｔ０，∞），Ｒ）．ｒ，τ，σ∈Ｒ＋，文章中获得了上方程所有解振动的新判据，同时讨论了正解的存在性及非振动解的渐近性。     

一类时滞模型周期正解的存在性问题

利用非线性锥映射的拓扑度的性质，研究了一类时滞微分方程周期正解的存在性问题，并将所得结果应用于Nichloson's blowflies模型，证明了在周期环境下，Nicholson's blowflies模型方程存在周期正解。     

四种群食物链方程的整体渐近稳定性

本文考虑具有时滞的四种群食物链反应扩散方程。给出了在一定条件下解的存在性和平衡态方程正解的整体渐近稳定性。由此可以得到解的持久性,平凡解和所有半平凡解的不稳定性。     

二阶周期边值问题正解的存在性

周期边值问题已成为方程研究领域的一个重要分支,它在许多实际问题中有着更为广泛的应用,本文主要研究了二阶周期边值问题正解的存在性.利用锥上不动点指数理论研究了二阶周期边值问题方程组的正解的存在性,通过相应的线性问题的第一特征值和拓扑度乘积定理,建立了正解的存在性定理.最后,我们给出具体的例子说明了该正解存在性定理的结论.     

一类奇异椭圆方程正解存在性

研究了一类奇异椭圆方程。利用变分方法,证明了奇异椭圆方程正解的存在性和唯一性,包含和推广了已有的些结果。     

广义Lyapunov方程的一个性质及其应用

研究广义Lyapunov方程PA＋A'P ∑^ni=1C'iPCi=-Q在精确能观性的假设下，证明了该方程有正解等价于（A，∑^ni=1,Ci)的稳定性。最后给出了该性质的一个应用。     

双重Hammerstein型积分方程正解的存在性

利用锥理论,研究了一类新的双重Hammerstein型积分方程的正解的存在性.     

一类常微分方程组正解的存在性

讨论了一类二、四阶耦合常微分方程组正解的存在性,利用不动点定理和度理论,在一定条件下得到了该方程组正解的两个存在性定理。     

不动点指数理论下非线性Neumann型边值问题正解的存在性

应用Green函数可以将微分方程边值问题转化为等价的积分方程.近来此方法被应用于讨论微分方程边值问题正解的存在性.本文讨论非线性二阶Neumann边值问题,应用Green函数,将其转化为等价的积分方程,并设非线性项在无穷远处有增长条件,利用锥上的不动点指数理论证明正解的存在性和非存在性.     

Influence of the principal geometrical parameters of straight city streets on positive and negative phase blast wave impulses

This study is concerned with the effect of confinement, provided by tall buildings which border straight city streets, on the positive and negative phase impulses of blast waves originating from explosive detonations. An approach to the problem is described which is based on a parametric study comprising numerical simulations validated by comparison with small-scale experiments. Results of the simulations are presented in graphs of peak scaled positive and negative phase impulse, measured at locations near to ground level on the building facades, plotted against scaled distance along the centreline of the city street. A range of scaled street widths and building heights are considered which covers most cases of practical interest. The nature of the variation of both positive and negative phase impulses is described, and the implications for the design and hazard assessment of urban landscapes are considered.     

Bacterial endospore detection using terbium dipicolinate photoluminescence in the presence of chemical and biological materials

A determination of the viability of an endospore detection technique using terbium dipicolinate photoluminescence in the presence of other chemical and biological materials was performed. The compounds and organisms examined, possible environmental constituents, covered three broad categories: organic compounds, inorganic compounds, and biological materials. Each substance was tested for a false positive, which occurs if the intrinsic terbium photoluminescence is enhanced in the absence of a bacterial endospore. The detection technique was also investigated for false negatives, which occur if a known positive endospore signal is inhibited significantly. Although several materials may give rise to false negative signals, none caused a false positive signal to be observed.     

关于Patel-Toda迹不等式的一个推广

王伯英等[Lin．Alg．Appl．,293(1999)：39-49】将半正定Hermitian矩阵的Patel-Toda迹不等式V从迹推广到特征值。我们证明了这个结粜在比“半正定”更弱的条件下也是成立的。     

Highly mobile oxygen hole-type charge carriers in fused silica

Some peculiar positive charge carriers are thermally generated in fused silica above 500 degrees C. These charge carriers appear to be positive holes, chemically O- states, probably arising from dissociation of peroxy defects. The charge carriers give rise to a pronounced positive surface charge which disappears upon cooling but can be quenched by rapid quenching from approximately 800 degrees C. Reheating to approximately 200 degrees C remobilizes these charge carriers and causes them to anneal below 400 degrees C. The generation of positive holes charge carriers may be important to understand failure mechanisms of SiO2 insulators.     

Study of temperature dependence of positive charge generation in thin dielectric film of MOS structure under high-fields

In this work, the temperature effect on positive charge generation under high-field electron injection in MOS structures is studied using a new multilevel current stress technique. In our experiments, we used commercially made test MOS capacitors based on thermal silicon dioxide film with thickness in the range from 7 to 100 nm. Using the proposed multilevel current stress technique one can investigate the positive charge generation in MOS structure gate dioxide under high electric fields. The technique is different from the standard constant current stress technique, as it includes two levels of current: the stress current level, which provides the generation of positive charge, and the additional measuring current level, which allows to monitor the change of dielectric charge. Due to the additional measuring current level, it is possible to decrease significantly the error of positive charge density measurement in the dielectric. The latter error is caused by the positive charge trapped in the initial stage of electron injection while the steady-state of the stress mode is being reached. It was found that the rise of sample temperature leads to a decrease of the density of the positive charge generated in SiO₂ film under high-field injection of electrons from the silicon substrate. A model of the positive charge generation in MOS structures under high-field electron injection has been proposed. The new model of the positive charge generation in MOS structures takes into account the temperature effect and the subsequent phenomena of dielectric charge state change: the band-to-band impact ionization in SiO₂ with the creation of electron-hole pairs and the subsequent trapping of holes in traps in the oxide; the trapping of injected electrons by trapped holes as well as the thermal release of trapped holes from the traps.     

An empirical study of impacts of production mix,product route efficiencies on operations performance and profitability: a reverse logistics approach

This research studies the impact of two reverse logistics business strategies on profitability of the firm through operations management (OM). The study is employed on scrap steel industry. The first strategy is production mix efficiency (PME), which is involved in the process of producing goods. The second strategy is product route efficiency (PRE), which engages in the transportation of goods. Our finding indicates that OM alone does not have a positive impact on profitability. However, the two strategies have a positive effect on profitability, which provides a potential answer to firms trying to improve profitability.     

Lower Bound Solutions to Multi-Stage Production Scheduling Problems with Startup Delays

A methodology for determination of lower bound solutions for multi-stage production scheduling problems is treated here. The startup delays are expressed as analytical functions of demand, production rate, and cycle times for the appropriate stages. A theorem is proved which states that the lower bound solution is achievable if and only if adjacent stage cycle times differ by proportionality constants which are positive integers, or the reciprocal of positive integers. Computer algorithms for the solution of the lower bound problem are discussed.     

带有食饵保护的Holling-Ⅲ型扩散捕食系统的稳定性分析

本文研究了一类具食饵保护的Holling-Ⅲ型扩散捕食系统,带有齐次Neumann边界条件.首先,讨论了系统的全局吸引性;其次,给出了系统正常数平衡态局部/全局渐近稳定的充分条件,这些条件依赖于食饵保护参数;特别地,获得了扩散对系统常数平衡态稳定性的影响,即当扩散系数较大时可使得常数平衡态不稳定.     

洁净室空调设计的相关问题探讨

对于洁净室而言，恒定送风量，正压控制，末端过滤器的选择是达到室内洁净度的关键。采用变频风机送风是比较节能的送风方案；调节新，回风比能很好的控制正压末端过滤器的选择与所要达到的洁净度相符。     

Diffusion positive column of electric discharge in transverse magnetic field

The effect of a transverse magnetic field on the characteristics of planar diffusion positive column of electric discharge has been studied. It is shown that, as the magnetic induction increases, the distributions of plasma density and particle fluxes to walls become asymmetric; the density maximum shifts in the direction of Ampere’s force action, and the ion flux in this force direction can significantly exceed the reverse flux. It is established that there is a maximum value of magnetic induction, which bounds from above the region of magnetic fields in which a stationary state of the positive column is possible. In the region where a stationary state of the positive column is possible, each value of the magnetic induction corresponds to two positive-column regimes with different values of the electron energy, drift velocity, and electric field strength.