GLOBAL ENTROPY SOLUTIONS TO AN INHOMOGENEOUS ISENTROPIC COMPRESSIBLE EULER SYSTEM

In this article, we develop a new technique to prove the global existene of entropy solutions to an inhomogeneous isentropic compressible Euler equations through the compensated compactness and vanishing viscosity method. In particular, the entropy solutions are uniformly bounded independent of time.     

Enantiomeric resolution of new triazole compounds by high-performance liquid chromatography

Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) was synthesized and coated on aminopropylsilica to prepare a chiral stationary phase (CSP). HPLC methods were developed for the direct enantioseparation of 12 chiral triazole compounds on the CSP. The separations were made using normal phase methodology with a mobile phase consisting of n-hexane-alcohol (ethanol, 1-propanol, 1-butanol, 2-propanol, and t-butanol) in various portions. The column temperatures were studied for the optimization of the resolutions. The effects of structural features of the solutes on the discrimination between the enantiomers were examined. Baseline separation was easily obtained in many cases.     

平均熵

设Ｔ为紧度量空间Ｘ上的连续自映射,ｍ为Ｘ上的Ｂｏｒｅｌ概率测度,通过把测度（拓扑）摘局部化,引入了Ｔ关于ｍ的平均测度（拓扑）熵的概念,它们分别为相应ｍ－测度（拓扑）混沌吸引子熵的加权平均,从而Ｔ关于ｍ的平均测度（拓扑）熵大于零当且仅当Ｔ有ｍ－测度（拓扑）混沌吸引子．证明了线段Ｉ上关于Ｌｅｂｅｓｇｕｅ测度平均拓扑熵大于Ｃ与等于零的连续自映射都在Ｃ０（Ｉ,Ｉ）中稠密．     

CH_2(~3B_1)与NO的基元化学反应研究

Cth和NO都具有未配对电子,它们之间的反应属于自由基之间的反应．该反应可能经历的通道很多,因此研究这个反应,具有重要的学术价值．另一方面,烃类在燃烧过程中可热解成CH、CW、C：H或CIn等自由基碎片’‘’,亚甲基CW与NO的反应是重要的基元反应之一．除此之外NO是重要的环境污染物,在大气中低浓度NO能够存在较长时间”’,可继续与CHZ自由基发生反应．因此就环境保护方面来说,CIn自由基与NO反应的研究也有较大的现实意义．虽然以前很多人都通过实验测出过CW与NO总反应的速车常数’‘,’－’‘,但关于反应动力学方面的…     

CH2(～X3B1)与NO的基元化学反应研究

The reaction of methylene radicals in their 3B1 electronic ground state with molecular NO was studied. Pure CH2(～X3B1) radicals were produced by UV photolysis of ketene at 351 nm. The products were measured by Time-Resolved Fourier Transform Infrared (TR-FTIR) spectrometer. CO、OH、NH2 and HOCN or its isomer HNCO were found as primary products and several possible channels of this reaction were suggested.     

HBr分子的爱因斯坦自发辐射系数的计算

本文从第一性原理出发,计算了ＨＢｒ分子ｖ≤７,Ｊ≤１４,Δｖ＝１,Ｒ,Ｐ支谱线的爱因斯坦自发辐射系数Ａ＾ｖ‘Ｊ’ｖ＾ｎＪ＾ｎ。测量了ＨＢｒ红外发射的振转谱线强度,证实由理论计算获得的Ａ＾ｖＪ’Ｖ＾ｎＪ＾ｎ系数是可靠的。     

N‐Ethylpyridinium bis(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato)nickelate

The title compound, (C₇H₁₀N)[Ni(C₃S₅)₂] or (Etpy)[Ni(dmit)₂] (where Etpy is the N‐ethyl­pyridinium cation, C₇H₁₀N⁺, and dmit is the 2‐thio­xo‐1,3‐di­thiole‐4,5‐di­thiol­ate dianion, C₃S₅²⁻), crystallizes in the P space group with two mol­ecules in the asymmetric unit. The [Ni(dmit)₂]⁻ monoanion has a planar D_2h conformation, with the central Ni atom and the four coordinated S atoms forming an NiS₄ square plane. The six‐membered ring of the Etpy cation also shows good planarity, as expected. There are two main types of disorder in the two Etpy cations. Several short intermolecular interactions are present, such as S⋯S, Ni⋯S and Ni⋯Ni, which help to form the enhanced three‐dimensional structure of the crystal.     

A Simplified Formulation to Estimate Influence of Gearbox Parameters on the Rattle Noise

Occurrence of gear rattle in transmission systems can result in severe vibration and noise, which in applications such as automobiles is an important source of user discomfort. As a result , the reduction of the rattling noise has attracted lot of concerns. The rattling noise level is affected by several gearbox parameters, an understanding of which is essential to prevent the expensive design modifications at later stages of product development. To develop such understanding at the gearbox design stage, this paper analytically evaluates the gear parameters’ effect on the root mean square of the wheel gear acceleration under idling condition, which is known to be linearly correlated to the rattling noise level. Therefore, this evaluation allows for an investigation of the gear parameters’ influence on the rattling noise as well. This method is then verified by comparing the analytical results with the simulation results from a dynamic model built in SIMPACK as well as previously published experimental results. Thus, the proposed analytical evaluation method can optimize the gearbox specifications at the design stage to reduce the gear rattle noise level.     

THE STRESS ANALYSIS OF HOLE WALL OF FLOWER SHAPE OBTAINED BY INCLINATION RECTIFICATION DIGGING AND ENGINEERING APPLICATION

提出了一种带朵纠倾掏土孔的既有建筑纠倾新方法,给出了带朵纠倾孔孔壁最大应力的近似计算公式,用数值计算方法验证了近似公式的适用性。新方法相对于传统圆形掏土孔方法能更好地实现建筑纠倾工程的精确可控、快速纠倾、避免过倾。当大孔半径与小朵孔半径之比在1$\sim $6范围时,纠倾效果较好。     

利用回波相干性的医学超声成像相位畸变校正方法

为了提高相位畸变条件下的医学超声成像的横向分辨率和对比度,提出了一种利用回波信号相干性的校正方法。首先给出平均相干系数的概念,并将其作为相位误差校正的度量,然后通过最大化平均相干系数逐步校正各个通道的延时误差,最后再利用经过校正的数据计算出一组新的相干系数并对回波信号进行加权优化,从而得到最终用于成像的数据。对点散射目标及斑散射目标的仿真结果分别显示,利用所提出的方法横向分辨率提高了约0.24 mm,对比度提高了约18 dB,且要优于邻近阵元互相关方法和相干系数直接加权的处理方法。利用回波相干性的相位畸变校正方法结合了相位误差校正和加权处理的优点,可以有效地改善医学超声成像的质量。