Theoretic analysis on the manufacture of blended yarn by one spinneret

The possibility of producing blended yarn by using one spinneret is analyzed theoretically, especially the formation of differences in linear density and shrinkage between the monofils. Under the same spinning pressure, the die-spinning nozzles with different diameters are used to produce the differences in the flow of the melt. According to the hagen-poseuille equation for streamline flow in cylinder pipe, the volumetric flow rate and the mean melt speed of die-spinning nozzles increase with the increase of diameters. Under the conditions that the winding speeds are the same, so that the effective draw ratios decrease with the increase of the die-spinning nozzles diameters. Then, the filament formed through the die-spinning nozzle with large diameter is coarse and have a low birefringence. On the contrary, the filament formed through the die-spinning nozzle with small diameter is fine and have a high birefringence. The differences between the filament in structure and property could be acquired by one spinneret.     

毛竹竹材物理力学性能研究

为了解不同竹龄毛竹生材含水率、线性干缩率、气干密度、抗弯强度、抗弯弹性模量和顺纹抗压强度等物理性能,对其加工应用的影响,笔者以2-7年生毛竹为材料进行研究,结果表明：竹材的生材含水率、气干干缩率（弦向、径向、纵向）和全干缩率（弦向、径向、纵向）随着竹龄的增加呈减小的趋势;从基部到梢部竹材的生材含水率、线性干缩率均减小;竹材线性干缩率弦向＞径向＞纵向.竹材气干密度、抗弯强度、抗弯弹性模量和顺纹抗压强度均随着竹龄的增加呈增大的趋势,尤其是3年生竹材的这些物理力学性能与2年生差异显著,但3年后生竹材差异不大;从基部到梢部竹材的气干密度、抗弯强度、抗弯弹性模量和顺纹抗压强度逐渐增加.综合考虑毛竹的物理力学性能和竹林的经济效益,适合采伐的是3年后生竹材,锯截之后的竹材也应根据部位不同进行区分,以便于加工应用过程中合理利用,提高产品的理化性能和质量的稳定性.     

水库溢流坝闸墩裂缝修补加固技术研究

水库运行后出现溢流坝闸墩竖向裂缝,在调查与检测基础上,运用ANSYS有限元软件及线性静力学理论,分析静水荷载、闸墩上部重力荷载、闸门开启荷载、温度荷载等组合荷载作用下对闸墩整体结构应力分布计算,分析了闸墩混凝土危险区域及裂缝成因,提出裂缝修补加固技术,为类似工程问题提供借鉴。     

Preliminary Study on Features ofLaterite Clay in Beigu Area,Fuling

This paper briefly describes the formed condition,classification, and general characteristics of the laterite clay in Beigu area and analyses the physical and mechanical properties, the features of swelling and shrinkage and the relativity between the coefficient of free swelling and plastic index of the laterite clay. Finally, some opinions on the suitability of the water content and liquid index of the laterite clay are presented     

The Mechanism of Smooth and Pre-Cracking Blasting

The paper discusses some main factors of the mecha nism of smooth and pre-cracking blasting.The results of theoretical analyses show that the formation of directional cracks isrelated to the distan ce of holes.the quasi-static pressure and the strueture of rock mass. This paperalso studies the relation of len gth of crack and distance of holes.The initial cracks occur on the wallof holes instead of in the middle of two holes.     

NUMERICAL SIMULATIONS OF THE SOLIDIFICATION PROCESS IN HEAVY STEEL CASTINGS AND THE SHRINKAGE CAVITY PREDICTION

In this paper a numerical simulation software of the casting solidification process is designed with the implicit alternating direction method (i,e IAD) and the TRUE BASIC language. The solidification process of the cross-section A-A of the high pressure inner cylinder is simulated and the shrinkage cavity position is predicated by means of utility software. The simulation is agreeable to the measurement.     

Effect of Coarse Aggregate on Characteristics of Plastic Shrinkage Cracking of Lightweight Aggregate Concrete

The grading of lightweight aggregate (LA) and its water content has an effect on the plastic shrinkage cracking of lightweight aggregate concrete (LWAC). Test results show that the water absorption of LA and the water evaporation of the concrete increased with the increment of cubage of LA, but the area of plastic shrinkage cracking of LWAC decreased. Besides, LA with high water content is beneficial to restraining the plastic shrinkage cracking of LWAC.     

频域滤波的水泥路面图像降噪增强方法

针对在水泥路面裂缝图像识别中刻槽和纵向条带状形成的噪声干扰,提出了一种基于频域滤波的降噪增强方法。首先,分析了这两类噪声的频谱特征,并根据空域图像中刻槽的周期性,推导了频域图像中刻槽谱峰的位置,设计了消除这些谱峰的系列滤波器。根据纵向条带状干扰属于低频成分的特性,设计了抑制低频、增强高频的滤波器,经优化滤波器参数达到消除这类干扰的效果。实验结果表明,该方法能够消除两类噪声干扰,同时,增强了裂缝的对比度,为水泥路面裂缝识别提供了理论基础。     

DETERMING THE RELIABILITY OF A MEMBER WITH CRACK ACCORDING TO THE INFORMATION FROM FLAW-DETECTION WITH ULTRASONIC WAVE

Using the flaw-detecting with ultrasonic wave one may know the equivalant area of a crack that burys in the member. If the crack is ellipse shaped, the equivalant area is constant, and the distribution function of its major semiaxle and the plane strain fracture toughness of the material are given, then we would get the probability of reliability of the member under the uniform tension. In this condition, a formula of calculating the probability would be provided in this paper. Because a simple and enough precise approximate function has been introduced the formula in the paper is simple in shape and easy to use.