Injective modules and torsion functors*

A commutative ring is said to have ITI with respect to an ideal 𝔞 if the 𝔞-torsion functor preserves injectivity of modules. Classes of rings with ITI or without ITI with respect to certain sets of ideals are identified. Behavior of ITI under formation of rings of fractions, tensor products, and idealization is studied. Applications to local cohomology over non-noetherian rings are given.     

Abel范畴的右双-Giraud粘合

我们在本文中引入了Abel范畴的右双-Giraud粘合定义.我们证明了右双-Giraud粘合与余遗传和遗传的挠对存在着双射对应.此外,我们通过模范畴中特定的幂等理想刻画了这类挠对.     

超声辅助搅拌摩擦焊仿真分析及实验

为解决传统的搅拌摩擦焊工艺存在的轴向压力过大、搅拌头易磨损、焊接表面存在缺陷等问题,设计了一种集搅拌头与夹心式纵扭超声振动换能器为一体的超声辅助搅拌摩擦焊工具头。对超声辅助搅拌摩擦焊工具头进行了模态分析与谐响应分析,确保换能器结构满足要求。应用仿真软件对超声辅助搅拌摩擦焊进行了流体场、温度场和声场仿真分析,验证了在搅拌摩擦焊过程中加入纵扭超声振动能够增强材料的软化率,提高焊接材料的塑性流动。搭建实验平台,进行了6061铝合金的超声辅助搅拌摩擦焊焊接实验。结果表明,纵扭超声的引入能够提高焊接过程中材料流动性,减小搅拌头的前进阻力和轴向压力,改善焊接表面质量。在焊头转速900 r/min、焊接速度1.4 mm/s、轴向压力2.6 kN、超声功率100 W时,焊接效果最好,能较好地应在铝合金、镁合金等焊接熔点比较低的轻金属焊接之中。     

域外奇点法解杆的弹塑性扭转问题

本文提出一种借助于沙丘比拟的求解杆弹塑性扭转问题的域外奇点法,这种方法可降低所求问题的维数,有效地避免解的奇异性。它具有方法简单,不需要数值积分,计算时间短和精度高等优点。     

Saint-Venant Torsion of a Two-Phase Circumferentially Symmetric Compound Bar

This work is concerned with the Saint-Venant torsion problem of a two-phase circumferentially symmetric compound prismatic bar. By generalizing a method originally proposed by Packham and Shail [12], we demonstrate that for a particular two-phase configuration, simply or multiply connected, which is invariant with phase interchange, the solutions can be constructed from solutions of two analogous problems with constant material properties. An effective shear modulus is derived in analytic form, which is approximately the harmonic mean of the component shear moduli. We also show that the effective torsional shear modulus is homogeneous for arbitrary configurations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Environment‐Sensitive Behavior of DCNP in Solvents with Different Viscosity,Polarity and Proticity

A pyrazoline derivative, 3‐(1,1‐dicyanoethenyl)‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazole (DCNP), is studied by using optical spectroscopy methods in several solvents at room and at low temperatures. The DCNP molecule reveals a complex photophysics behavior, which is sensitive to solvent polarity, proticity, temperature and viscosity and arises from the presence of two rotational degrees of freedom of the dicyanovinyl group—the torsion around the double C=C bond and the s‐trans–s‐cis isomerization around the single C?C bond—that differently behave in various environmental conditions. The fluorescence yield of a few percent and sub‐nanosecond decay times observed at room temperature make the compound useful for optical studies of liquid environments. The proticity of polar solvents can be detected with two‐exponential fluorescence decays. At low temperatures, DCNP can be used as solvent viscosity or temperature fluorescent sensor.     

单侧睾丸扭转对精子DNA 碎片及核蛋白组型影响的研究

目的 探讨单侧睾丸扭转以及不同术式对患者精子质量的影响。方法 将58例单侧睾丸扭转患者（其中行睾丸扭转复位术32例,睾丸切除术26例）,按WHO《人类精液及精子-宫颈黏液相互作用实验室检验手册（第5版）》规定检测精子运动指标（10项）、精子DNA 碎片和精子核蛋白组型。结果 睾丸扭转复位组术后3、12、26 周的精子密度、前向运动精子比例逐渐升高,差异有统计学意义（P＜0.05）;精子DNA 碎片百分率、精子核蛋白组型百分率逐渐降低,差异均有统计学意义（均P＜0.05）。睾丸扭转复位组术后3周精子DNA 碎片百分率明显高于睾丸切除组,差异有统计学意义（P＜0.05）;术后26周精子密度明显低于睾丸切除组,差异也有统计学意义（P＜0.05）。结论 睾丸扭转使患者精子质量明显降低,单侧睾丸扭转切除术后精子质量的恢复比睾丸扭转复位快。     

Some analytical solutions for Saint-Venant torsion of non-homogeneous anisotropic cylindrical bars

The Saint-Venant torsion of linearly elastic anisotropic cylindrical bars with solid and hollow cross-section is treated. The shear flexibility moduli of the non-homogeneous bar are given functions of the Prandtl's stress function of considered cylindrical bar when its material is homogeneous. The solution of the torsion problem of non-homogeneous anisotropic bar is expressed in terms of the torsion and Prandtl's stress functions of the corresponding homogeneous anisotropic bar having the same cross-section as the non-homogeneous bar.