Steady-state response of the parametrically excited axially moving string constituted by the Boltzmann superposition principle

Summary.  The steady-state transverse vibration of a parametrically excited axially moving string with geometric nonlinearity is investigated in this paper. The Boltzmann superposition principle is employed to characterize the material property of the string. The method of multiple scales is applied directly to the governing equation, which is a nonlinear partial-differential-integral equation. The solvability condition of eliminating the secular terms is established. Closed form solutions for the amplitude and the existence conditions of nontrivial steady-state response of the summation resonance are obtained. Some numerical examples showing effects of the viscoelastic parameter, the amplitude of excitation, the frequency of excitation, and the transport speed are presented. Received February 12, 2002; revised October 25, 2002 Published online: May 8, 2003 The research was supported by the National Natural Science Foundation of China (Project No. 10172056).     

我国住宅产业化研究的回顾与展望

通过对国内近年来与住宅产业化相关的研究成果进行归纳和梳理,旨在厘清国内关于住宅产业化的概念界定、住宅产业化发展现状、现存问题及成因,针对国内住宅产业化研究提出几点建议并展望其未来发展趋势.     

高档日用细瓷高温快烧辊道窑的研制

高档日用细瓷高温快烧辊道窑的研制成功,大幅度降低了烧成成本和工人劳动强度,提高了机械化水平,同时,研究成功了与窑炉相适应的陶瓷配方,为实现高温快烧提供了工艺技术条件。     

Dynamic calibration method of high-pressure transducer based on quasi-δ function excitation source

This paper presents a dynamic calibration method of frequency response characteristics of high-pressure sensor. In this method, the pressure sensor was under high hydrostatic pressure in advance, then use the bullet impacted Hopkinson bar and generated quasi-δ function signal with small amplitude, which excited the sensor being calibrated. The excitation signal of sensor are collected, at the same time, output signal of the sensor are collected, and at last, the collected data are processed according to calibration principle and calculated the frequency response of the sensor being calibrated. This calibration method realized dynamic calibration of high pressure sensor under actual working pressure; it can realize the low limit frequency of the calibrated frequency range strictly reaches to zero frequency. This method can also be applied to acceleration sensor, transient high-temperature sensor, and other types of sensors. In this paper, the calibration principle of quasi-δ function dynamic calibration method is introduced. The relationship among pulse width of excitation signal, frequency range that can be calibrated and calibration precision is analyzed. The experimental results are also shown.     

现代仪器在浆料成分分析中的应用

本文主要采用超声仪、微波消解仪对浆料进行前处理,利用红外及热重对浆料中树脂进行定性及半定量,GCMS及热重对浆料中溶剂进行半定量,ICP-OES测定浆料中玻璃粉的成分及含量,以及利用差减法得到银粉的含量。     

磁悬浮硬盘转子控制系统中时序电路测试技术

为提高磁悬浮硬盘转子控制系统的可靠性，提出了对时序芯片的测试方法：手工测试和计算机辅助测试；及时时序电路逻辑功能的两种检测技术；基于状态表的测试技术和自动检测技术。对于时序芯片，手工测试方法效率较低，计算机辅助测试方法适用范围更广；对于电路逻辑功能，基于状态表的测试技术操作相对困难，但无须增加额外测试电路；自动检测技术操作简单，且测试速度快，但需要增加辅助检测电路。时序电路测试技术对保证悬浮硬盘转子各组成部分协同工作十分重要。     

优化工艺操作延长ZSM-5催化剂再生周期

通过分析烷基化催化剂表面结焦的原因，找到有效抑制烷基化催化剂表面结焦速度的方法，改善了苯乙烯装置烷基化反应的操作。     

Content and Color Stability of Anthocyanins Isolated from Schisandra chinensis Fruit

In this work, a multivariate study based on Box-Behnken Design was used to evaluate the influence of three major variables affecting the performance of the extraction process of Schisandra chinensis anthocyanins. The optimum parameters were 5.5 h extraction time; 1:19 solid-liquid ratio and 260 r/min stirring rate, respectively. The extraction yield of anthocyanins was 29.06 mg/g under the optimum conditions. Moreover, many factors on the impact of heating, ultrasound, microwave treatment and ultraviolet irradiation on content and color stability of anthocyanins from Schisandra chinensis fruit were investigated. The results show that thermal degradation reaction of anthocyanins complies with the first order reaction kinetics, and the correlation coefficient is greater than 0.9950 at 40–80 °C. Ultrasound and microwave treatment has little effect on the stability of anthocyanins, and the extraction time of ultrasound and microwave should be no more than 60 min and 5 min, respectively. The anthocyanins degradation effect of UVC ultraviolet radiation is greater than UVA and UVB; after 9 h ultraviolet radiation, the anthocyanins content degradation of UVC is 23.9 ± 0.7%, and the ΔE* was changed from 62.81 to 76.52 ± 2.3. Through LC-MS analysis, the major composition of Schisandra chinensis anthocyanins was cyanidin-3-O-xylosylrutinoside.     

BMP文件数据压缩与解压缩方法

以RLE方法为基础,针对BMP(Bitmap/位图)文件的特点,设计了独特的YSBMP4和YSBMP8无失真压缩方法,以及UNYSBMP4和UNYSBMP8解压缩方法,并通过实例进行了说明。对Windows下的16色和256色模式BMP文件进行压缩,数据压缩比最多可以达到8/100左右,达到图像无损恢复的目的。     

论若干因素对制定企业内部转移价格的影响

采用最佳内部转移价格对企业和内部各单位是有益的，在众多影响内部转移价格因素中，要考虑市场交易成本和技术进步产生的影响．当市场交易成本存在时，仅依靠由内部转移价格来确定企业内部单位的估算利润并以此来评价其贡献是片面的；若将估算利润同实施奖励结合在一起，内部转移价格可能会挫伤企业内部单位采用新技术和提高生产率的积极性．