ILLUMINATION AND EXPOSITION OF A CONVEX n-DIMENSIONAL BODY DEPENDING ON ITS SHARPNESS

IInttodllCt1ODLet C be a(comp。t)con。x。－dimensional body in E”,n＞2,and d be a direction,l·e·a nonzero vector·A Point P EaC Is said to be illuminated by d ifthe line throughphavingthe dlrectlondco尬ams apomt qE nit Cwhi山followsp．ThebodyCis ssidtobeillttthillat6d by 8 S6t Of diY6CtiollS dl,dZ,…If gch Of佃加llldaty pollltS IS lllttthillst6d by tleast one of these directions．The Illumination Problem is to establish the minunum integer Ii(called llumination number…     

结冰环境热合成双射流激励器工作特性数值研究

为研究结冰环境中热合成双射流激励器工作特性,采用离散相模型(discrete phase model,DPM),结合动网格方法,数值研究了结冰环境中来流速度、液滴含量、液滴直径对激励器工作特性的影响.结果表明,来流速度较小时,双射流激励器出口形成热合成射流融合区,由于热射流的加热作用,温度较高,环境中的过冷液滴难以进入...     

Kink effect in current-voltage characteristics of a GaN-based high electron mobility transistor with an AIGaN back barrier

The kink effect in current-voltage （IV） characteristic s seriously deteriorates the performance of a GaN-based HEMT. Based on a series of direct current （DC） IV measurements in a GaN-based HEMT with an AlGaN back barrier, a possible mechanism with electron-trapping and detrapping processes is proposed. Kink-related deep levels are activated by a high drain source voltage （Vds） and located in a GaN channel layer. Both electron trapping and detrapping processes are accomplished with the help of hot electrons from the channel by impact ionization. Moreover, the mechanism is verified by two other DC IV measurements and a model with an expression of the kink current.     

防护热板装置的研究进展及其在液氮温区的应用前景

随着新型绝热材料的研究及应用,防护热板装置已广泛用于测量各个领域绝热材料的导热系数,从航天到化工、从能源到建筑,防护热板装置都发挥着重要的作用.总结了防护热板装置国内外的最新研究进展;探讨了在低温液体贮存和运输领域,防护热板装置测量的技术问题及应用前景.     

Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography–tandem mass spectrometry: effect of household processes

Following quick, easy, cheap, effective, rugged and safe (QuEChERS) and LC/MS/MS analysis, pyridaben residual levels were determined in unprocessed and processed hot pepper fruit and leaves. The linearities were satisfactory with determination coefficients (R²) in excess of 0.995 in processed and unprocessed pepper fruit and leaves. Recoveries at various concentrations were 79.9–105.1% with relative standard deviations ≤15%. The limits of quantitation of 0.003–0.012 mg/kg were very low compared with the maximum residue limits (2–5 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. The effects of various household processes, including washing, blanching, frying and drying under different conditions (water volume, blanching time and temperature) on residual concentrations were evaluated. Both washing and blanching (in combination with high water volume and time factor) significantly reduced residue levels in hot pepper fruit and leaves compared with other processes. In sum, the developed method was satisfactory and could be used to accurately detect residues in unprocessed and processed pepper fruit and leaves. It is recommended that pepper fruit/leaves be blanched after washing before being consumed to protect consumers from the negative health effects of detected pesticide residues. Copyright © 2014 John Wiley & Sons, Ltd.     

An existence result for dissipative nonhomogeneous hyperbolic equations via a minimization approach

We discuss a purely variational approach to the study of a wide class of second order nonhomogeneous dissipative hyperbolic PDEs. Precisely, we focus on the wave-like equations that present also a nonzero source term and a first-order-in-time linear term. The paper carries on the research program initiated in [14], and developed in [15], [21], on the De Giorgi approach to hyperbolic equations.     

A variant of the Erdős-Sós conjecture

A well-known conjecture of Erdős and Sós states that every graph with average degree exceeding $m-1$ contains every tree with $m$ edges as a subgraph. We propose a variant of this conjecture, which states that every graph of maximum degree exceeding $m$ and minimum degree at least $\lfloor 2m/3\rfloor$ contains every tree with $m$ edges. As evidence for our conjecture we show (a) for every $m$ there is a $g\left(m\right)$ such that the weakening of the conjecture obtained by replacing the first $m$ by $g\left(m\right)$ holds, and (b) there is a such that the weakening of the conjecture obtained by replacing $\lfloor 2m/3\rfloor$ by $\text{◂⋅▸}\left(1-\gamma \right)m$ holds.     

着色的琼斯函数(英文)

In this paper,we discuss the properties of the colored Jones function of knots.Particularly,we calculate the colored Jones function of some knots（3₁,4₁,5₁,5₂）.Furthermore,one can compute the Kashaev’s invariants and study some properties of the Kashaev’s conjecture.     

Experimental analysis of interface contact behavior using a novel image processing method

The spatial and temporal evolution of real contact area of contact interface with loads is a challenge. It is generally believed that there is a positive linear correlation between real contact area and normal load. However, with the development of measuring instruments and methods, some scholars have found that the growth rate of real contact area will slow down with the increase of normal load under certain conditions, such as large-scale interface contact with small roughness surface,which is called the nonlinear phenomenon of real contact area. At present, there is no unified conclusion on the explanation of this phenomenon. We set up an experimental apparatus based on the total reflection principle to verify this phenomenon and analyze its mechanism. An image processing method is proposed, which can be used to quantitative analysis micro contact behaviors on macro contact phenomenon. The weighted superposition method is used to identify micro contact spots, to calculate the real contact area, and the color superimposed image is used to identify micro contact behaviors.Based on this method, the spatiotemporal evolution mechanism of real contact area nonlinear phenomena is quantitatively analyzed. Furthermore, the influence of nonlinear phenomenon of real contact area on the whole loading and unloading process is analyzed experimentally. It is found that the effects of fluid between contact interface, normal load amplitude and initial contact state on contact behavior cannot be ignored in large-scale interface contact with small roughness surface.