Ballistic limit velocity of small caliber projectiles against SS400 steel plates:Live fire experiments and empirical models

This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.

Tailoring strength-ductility balance of caliber-rolled AZ31 Mg alloy through subsequent annealing

Recently,multi-pass caliber rolling has been shown to be effective for Mg alloys.This study investigated the effect of subsequent annealing on the mechanical properties of a caliber-rolled AZ31 Mg alloy to modulate the strength-ductility relationship.This annealing gave rise to different trends in mechanical properties depending on the temperature regime.Low-temperature annealing(T≤473 K)exhibited a typical trade-off relationship,where an increase in annealing temperature resulted in increased ductility but decreased strength and hardness.Such a heat treatment did not degrade the high strength-ductility balance of the caliber-rolled alloy,suggesting that the mechanical properties could be tailored for different potential applications.In contrast,high-temperature annealing(T>473 K)caused a simultaneous deterioration in strength,hardness,and ductility with increasing annealing temperature.These differences are discussed in terms of the varying microstructural features under the different investigated annealing regimes.

Microstructure and texture evolution in AZ31 magnesium alloy during caliber rolling at different temperatures

Magnesium alloy AZ31 was caliber rolled at different temperatures viz.523K,573K,623K,673K and 723K imposing a total cumulative reduction of 92%and a cumulative strain of 2.6.The associated microstructure and texture evolution were studied using Electron Back Scattered Diffraction(EBSD)and X-ray macro-texture observations respectively.Grain refinement was observed in all the caliber rolled bars indicating the occurrence of dynamic recrystallization.Asymmetry parameter and texture index were used to study the evolution of texture.Near doubling of the yield strength at room temperature was observed by caliber rolling at a temperature of 573K.The improvement in mechanical properties was explained on the basis of the fine grain microstructures and suitable development of crystallographic texture.Based on the present study,warm caliber rolling can be used as a good production method for obtaining long bars of high strength magnesium alloy AZ31.

Effects of caliber rolling on microstructure and room temperature tensile properties of Mge3Ale1Zn alloy

Mge3Ale1Zn(AZ31)alloy was caliber rolled isothermally in the temperature range of 250e450
C to develop fine grains of 3.6e12.5 mm.The stressestrain curves obtained from tensile tests at room temperature were found to vary with the temperature employed in caliber rolling.Maximum tensile strength of 290 MPa and ductility of 13.5%were obtained upon caliber rolling at 300
C as compared to 188 MPa and 15.2%,respectively,in the mill-rolled condition.The variations in tensile properties are explained by the concomitant grain size,texture and twins obtained as a function of caliber rolling temperature.

Improved tensile properties of AZ31 Mg alloy subjected to various caliber-rolling strains

A multi-pass caliber rolling has attracted attentions as an alternative to severe plastic deformation processes.The present study enhanced strength and ductility of AZ31 Mg alloy simultaneously through the application of caliber rolling.The improving trends in tensile properties were interpreted with various caliber-rolling strains.The oval/circular-shaped calibers imposed a high plastic strain at the center of crosssection,leading to effective grain refinement to submicron scale.This work also confirmed the texture randomizing effect of caliber rolling.Such microstructural evolutions gave rise to the fabrication of high-strength material.Moreover,the caliber-rolled AZ31 Mg alloys exhibited an improvement in ductility as compared to the as-received sheet-rolled material.This was discussed in terms of activation of non-basal slip systems and suppression of mechanical twinning.This study successfully proved the possibility of caliber rolling to produce a bulk Mg rod with enhanced tensile properties.

Numerical Simulation and Experimental Research on Microstructural Evolution During Compact Hot Extrusion of Heavy Caliber Thick-Wall Pipe

Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion parameters on the microstructural evolution are investigated systematically. The metadynamic recrystallization(MDRX) kinetic models and grain size models of as-cast P91 steel are established for the first time according to the hot compression tests performed on the Gleeble-3500 thermal-simulation machine. Then a thermal-mechanical and micro-macro coupled hot extrusion finite element(FE) model is established and further developed in DEFORM software. The results indicated that the grain size of the extruded pipe increases with the increasing of initial temperature and extrusion speed, decreases when extrusion ratio increases. Moreover, the grain size is more sensitive to the initial temperature and the extrusion ratio. The optimum hot extrusion parameters are including that, the initial extrusion temperature of 1250 °C, the extrusion ratio of 9 and the extrusion speed of 50 mm/s. Furthermore, in order to verify the simulation precisions, hot extrusion experiment verification on the heavy caliber thick-wall pipe is carried out on the 500 MN vertical hot extrusion equipment. The load–displacement curve of the extrusion process and the grain sizes of the middle part extruded pipe are in good accuracy with the simulation results, which confirms that the hot extrusion FE models of as-cast P91 steel could estimate the hot extrusion behaviors. The proposed hot extrusion FE model can be used to guide the industrial production research of CHE process.

Retinal vessels caliber changes after strabismus surgery：results of 6mo follow-up

AIM：To evaluate the effect of strabismus surgery on retinal vessels calibers with digital color fundus photographs.METHODS：Two hundred consecutive strabismus patients underwent surgery,and 118 patients（female/male,55/63） who finished 6-month follow-up were finally included in this study.Optic disc-centered digital color fundus photographs of both eyes of all patients were taken prior to surgery and 6mo post surgery.The retinal vascular caliber of 116 operated eyes were measured using the computer program IVAN.The operated eyes were divided into 3 groups according to the surgical methods,recession of one muscle,one muscle recession and one muscle folding,one muscle resection and one muscle recession.The effect of number of altered muscles on retinal vessels was analyzed using statistic software SPSS 16.0.RESULTS：The mean age was 12.4±8.6y.Averaged central retinal artery equivalent（CRAE） of all patients was 120.31 ±23.02 μm preoperatively,and 122.87 ±15.93 μm six months after surgery.Averaged central retinal vein equivalent（CRVE） was 171.11 ±31.73 μm preoperatively and175.02±21.00 μm postoperatively.There was no significant difference of averaged CRAE（P=0.22） or CRVE（P=0.19）before and after operation.Averaged arteriole to venule ratio（AVR） was 0.71 ±0.07 before surgery and 0.70±0.07 after surgery.Comparison of preoperative and postoperative retinal vessels calibers among different surgical groups did not show significant differences.Also,there was no advantage of rectus muscle folding to muscle resection.CONCLUSION：Up to 6mo after strabismus surgery,the retinal vascular calibers were not altered.No more than two muscles in one surgery are safe for retinal perfusion.

Research on the floating performance of a novel large caliber machine gun based on the floating principle with complicated boundary conditions

In this paper,a novel large caliber machine gun was taken as the research object to analyze the floating technique based on the principle of fixed-point constraint and secondary counter-recoil.A rigid-flexible coupling multi-body dynamic model of the large caliber machine gun with muzzle brake based on floating principle was established,in which the influence of soil and human body was taken into account.The dynamic simulation was conducted and then the results were compared with the corresponding experimental data The dynamic characteristics of the machine gun with or without floating technique were analyzed to indicate the influence of floating technique upon the performance of the gun.Furthermore,the rigid-flexible coupling dynamic models with five different firing angles was constructed to study the influence caused by the angles.The results indicated that the floating mechanism could reduce the recoil effectively and improve the operational performance of this novel large caliber machine gun.

Design Scheme of New Type Shell Raising and Feeding System of Medium-large Caliber Naval Gun

The medium -large caliber naval gun is still playing an important role in modern war. The development of highly automatic Shell Raising and Feeding System (SRFS) in the world has been briefly outlined. Several typical SRFS of medium-large caliber naval guns have been analyzed. A re-design of the system is introduced, in which systematic design method has been used to demonstrate its feasibility. The design goal of the system is to realize rapid shell feeding, with application to many types of shells, quick change of shell types , accurate and reliable feeding operation, simple mechanical structure and easy realization of shell withdrawing.

Effect of reduction in area per pass on strain distribution and microstructure during caliber rolling in twinning-induced plasticity steel

The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod applications.The steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were analyzed.The skin pass caliber-rolled wire was characterized as a duplex fiber texture of major<111>and minor<100>.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire drawing.The skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.

条纹相机远程控制系统设计

针对激光驱动惯性约束核聚变超快诊断的远程控制需要,设计了一种条纹相机远程控制系统.该系统采用了网络化虚拟仪器结构,系统硬件主要由PC104+计算机、PC104多功能数据采集卡、通用计算机以及局域网组成,系统软件使用LabVIEW环境进行开发.对条纹相机远程控制系统进行了实验测试,结果表明,系统能够远程实现条纹相机电源控制、工作电压监控、延迟时间控制及扫描速度控制.

数字信号源频率校准及测量不确定度评定研究

以广泛应用的数字信号源为研究对象,将传统测量系统分析(MSA)方法与田口方法相结合进行了数字信号源频率测量系统分析和校准公式的推导,并进行具有交互效应场合下的数字信号源频率多变量误差分析和测量不确定度的评定。研究表明,可以通过测量数字信号源的典型值得到校准公式,由此推导出全量程任意点估计值,方便仪器的校准;可以使用正交表和SN比方法相结合分析测量仪器误差及进行测量不确定度评定。

基于质量损失函数的仪器最佳校准周期的确定

根据现行标准,测量器具的校准周期由各生产厂家和研究机构根据具体情况自行规定。田口(Taguchi)质量工程学给出了单质量特性情况下的最佳校准周期确定方法,但没有多质量特性下的计算公式。文中从质量经济性出发,使用马氏距离度量多元测量质量特性,应用田口二次质量损失函数,以数字信号源为例推导其最佳测量周期的理论公式,为该仪器测量周期的确定提供了理论依据。

Effect of the Biostimulant Foliar Addition of Marine Algae on cv, O＇Neal Blueberries Production

In the Retiro, ＂El Lucero＂ county, Maule, VII Region of Chile, an application of a marine algae extract known as Ascophilliurn nodosum, whose commercial name is Ekologik~, was evaluated by applying it to the whole foliage in order to evaluate the impact on total weight, average weight, equatorial diameter and soluble solids in cv. O＇Neal blueberries harvested in a three-year old orchard having a plantation density of 3,333 plants hal. The marine algae extract was applied in three phenologic phases： full bloom, fruit set and fruit color break. Four treatments were conducted： To, application of pure water （without the product）; T1, a 280 mL ha1 dose per application; T2, a 140 mL ha^-1 dose, equivalent to 50% of the treatment dose T1; and T3, a 420 mL ha^-1 dose, equivalent to a 50% extra than the treatment dose T1. The experimental design comprised sutb-sampling blocks with three repetitions of three uniform and healthy plants per treatment. Regarding the total and average fruit weight, they did not show significant statistical differences, but an increase in the average weight of fruits treated with the aforementioned product was observed. For parameters such as equatorial diameter, caliper and soluble solids of harvested fruit, the product caused a statistically significant increase. T3 was found to be the best treatment with a 15% weight, increasing taste, sugar amount, size and weight of the harvested fruits.

驼峰自动控制系统中车辆走行阻力预测与自动校正问题的研究

车辆走行阻力是随机、离散的参数 ,难以精确地测定。用经验公式和以重代阻的方法制约了自动控制系统控制质量的提高。实现阻力预测模型的自动校正 ,可以有效地提高阻力的使用精度 ,从而提高驼峰控制系统的解体效率和作业安全。本文介绍了车辆走行阻力的在线自动校正方面的研究结果。

电容式和压力式水位仪动态标定及传输函数测定

采用现代数字采样技术和仪器标定测试平台,对ORBES—89电容传感式水位仪和压力式水位仪进行了动态标定。标定信号是标定平台产生的正弦型和阶跃型水位变化。文中采用线性最小二乘拟合方法,求得了两仪器传输函数的解析表达式。分析结果表明,两台仪器在低频段内产生的相位滞后及振幅畸变均很小,在固体潮观测资料数据分析处理时可忽略不计。

结构声实验中加速度计和力传感器的校准

本文利用绝对法和比较法对加速度计的灵敏度进行了校准；利用冲击法对力传感器的灵敏度进行了校准．所得数据与出厂数据进行了比较．结果表明：这些方法是可行的，是实验室条件下有用的、可靠的传感器灵敏度校准方法．

一种三维物体的测量方法及其应用

介绍了一种仅使用一台CCD摄象头的低成本三维视觉测量方法。将结构光投射到由转动系统带动而旋转的三维物体上,经图象采集后,计算机求出三维物体的表面深度及各点的空间坐标,其数据用于计算机辅助雕刻及非规则形体的表面测量和加工。

非实验条件下内燃机润滑油使用期定标

利用铁谱技术,辅以斑痕法等,给出了非实验条件下内燃机润滑油使用期的定标方法,为铁谱技术更有效地应用于内燃机状态监测和故障诊断中提供了保证。

300MW机组送风自动调节系统的投运

针对汉川电厂 3 0 0 MW机组在实现机炉协调控制和 AGC调节后 ,送风投自动难的问题 ,对测风装置进行了正确标定 ,确定了与文丘利装置相对应差压变送器量程值 ,改进了测风装置差压信号取压方式和加装了防堵吹扫装置 ,成功地解决了风量信号测量难的课题。