知识体系与认知规律相结合建设分析化学课程教材

阐述教材是提高教学质量重要且必备的条件之一,回顾我国分析化学工作者编写教材的实践历程,提出编写教材应体现＂注重学科基础、关注学科前沿、适当拓展学科交叉,体现知识体系与认知规律相结合＂的特点。     

热环境中功能梯度圆柱薄壳分岔屈曲的边界约束效应

基于前屈曲一致理论,研究了热环境中受轴压功能梯度圆柱薄壳分岔屈曲的边界约束效应问题.导出前屈曲变形的解析解,结合分离变量法与有限差分法求解分岔屈曲控制方程,由此导出确定临界轴压的非线性特征值问题.考虑材料热物性质与温度的相关性,分别就两端简支和两端固支边界条件,分析了温度梯度、初始几何缺陷、组分材料体积分数对分岔屈曲临...     

高速切削刀具材料及其合理选用

刀具是实现高速切削加工的关键,本文阐述了高速切削刀具材料的要求、高速切削加工刀具材料的种类,以及高速切削不同材料时刀具材料的合理选用。     

基于输入整形技术的屋面材料送料系统

在对屋面材料自动送料控制系统进行建模的基础上,采用经典控制理论与输入整形技术相结合的控制方法,设计了屋面材料自动控制系统。经实际应用表明:整形后的位置响应超调量明显缩小,输出摆角明显减小,说明该控制系统实现了屋面材料送料系统的防摆控制,且稳定、可靠。     

Synthesis and properties of 1,1′-bis(diacetylene-group) connected ferrocene-thiophene derivative: a cooperatively functional behavior of diacetylene-group connected constituents

An extended π-electronic conjugation system of 1,1′-bis(diacetylene-group) connected ferrocene-thiophene derivative has been synthesized, with our integrated reaction between the corresponding TMS-protected acetylenes in one-pot. Its electronic properties have been examined, suggesting a cooperatively functional behavior of the diacetylene-group connected constituents.     

Using a multi-layered transducer model to estimate the properties of paraffin wax deposited on steel

When using ultrasound for detecting low impedance materials on the surface of high impedance materials, a major challenge is the contrast difference between the strong reverberations from the high impedance material and the weak echoes received from the low impedance material. The purpose of this work is to present the theoretical and experimental validation of an ultrasonic methodology for estimating the acoustical properties of paraffin wax on the surface of steel. The method is based on modeling and inversion of the complete electro-acoustic channel from the transmitted voltage over the active piezoelectric element, to the received voltage resulting from the acoustic reverberations in the multilayered structure. In the current work, two conceptually different models of the same multi-layer transducer structure attached to steel is developed and compared with measurements. A method is then suggested for suppressing the strong reverberations in steel, hence isolating the wax signals. This contrast enhancement method is fitted to the model of the structure, facilitating parameter inversion from the wax layer. The results show that the models agree well with measurements and that up to three parameters (travel time, impedance and attenuation) can be inverted from the wax simultaneously. Hence, given one of the three parameters, density, sound speed or thickness, the other two can be estimated in addition to the attenuation.     

Characterization of mechanical and geometrical properties of a tube with axial and circumferential guided waves

Guided waves propagating in cylindrical tubes are frequently applied for the characterization of material or geometrical properties of tubes. In a tube, guided waves can propagate in the axial direction and called axial guided waves, or in the circumferential direction called circumferential guided waves. Dispersion spectra for the axial and circumferential guided waves share some common behaviors and however exhibit some particular behaviors of their own. This study provides an investigation with theoretical modeling, experimental measurements, and a simplex-based inversion procedure to explore the similarity and difference between the axial guided waves and circumferential guided waves, aiming at providing useful information while axial and circumferential guided waves are applied in the area of material characterization. The sensitivity to the radius curvature for the circumferential guided waves dispersion spectra is a major point that makes circumferential guided waves different from axial guided waves. For the purpose of material characterization, both axial and circumferential guided waves are able to extract an elastic moduli and wall-thickness information from the dispersion spectra, however, radius information can only be extracted from the circumferential guided waves spectra.     

HIGH INDEX OPTICAL MATERIALS PREPARED BY COPOLYMERIZATION OF NOVEL BIFUNCTIONAL THIOMETHACRYLATES

Optical materials, such as ophthalmic lens, are thermosetting resins, which require crosslinking agents. An optical resin, having a high refractive index, is usually produced by radical copolymerization in which high index crosslinking monomers are significantly important. We provide here the resins prepared by radical polymerization of novel bifunctional thiomethacrylates as high index crosslinkers.     

A synthesis technique of single square loop frequency selective surface at terahertz frequency

In this paper, we have explored and extended the use of frequency selective surface towards the terahertz regime of the electromagnetic spectrum where interesting applications such as imaging, sensing and communication exist. We have discussed a synthesis technique to design the single square loop frequency selective surface (SSLFSS) at 150 and 300 GHz which have found suitable application in the fast analysis and fabrication of the frequency selective surface. Moreover, the analytical results have been supported by the CST Microwave Studio and Ansoft HFSS commercial simulators. We have discussed the angular insensitivity of the SSLFSS at 150 GHz as well as 300 GHz. However, the specific problems arise at terahertz frequencies as compared to the radio and microwave frequencies are the ohmic losses. The proposed analysis has been extended from 100 GHz to 350 GHz to discuss the ohmic and dielectric losses. We have also discussed the other important issues which are very much significant in the terahertz regime of the spectrum such as skin depth and surface roughness.     

蜡蚧轮枝菌侵染黑刺粉虱体表过程的显微观察

采用扫描电镜研究了蜡蚧轮枝菌侵染黑刺粉虱成虫的过程。结果表明：接种蜡蚧轮枝菌孢子12h后,附着在虫体上的分生孢子萌发形成芽管,24h后,在复眼、腹部气孔、足的基节和翅的基部等部位菌丝侵入黑刺粉虱体内,接种72h后虫体被厚厚的菌丝层覆盖。分生孢子可以直接以芽管侵入表皮,也可以产生附着胞再侵入。分生孢子在黑刺粉虱体表萌发形成芽管,芽管顶端可形成附着胞,附着胞再形成侵入钉穿透寄主体壁。寄主体表结构影响形成附着胞的形状及穿透体壁时芽管长度。穿刺点处的小孔及附着胞周围发现粘状分泌物,为蜡蚧轮枝菌在入侵黑刺粉虱过程中穿透体壁时对寄主表皮产生降解作用的酶。