不同释放力组合下小型外挂物投放的数值模拟

将嵌套方法和结构网格相结合,提出了一种高效的时间精确数值计算方法,对不同释放力下小型外挂物的投放进行了数值模拟.该模拟在有实验验证算例的基础上进行.首先对马赫数Ma=0.95下从机翼上挂载投放弹体过程进行了分析,并将模拟结果与实验结果进行比较,二者具有很好的一致性,表明该方法的准确性和可靠性.利用上述方法对一小型弹药在不同释放力组合下的投放进行了数值模拟.结果表明,投放物和释放力的参数特性对投放后物体的运动影响较大,尤其是前端释放力的大小和作用位置对该弹药投放后的俯仰角影响显著.对同一投放物来说,释放力参数的准确程度决定着数值模拟的准确性.计算结果为气动设计及有控投放提供了依据.

高速铁路解锁后纵连式无砟轨道纵向温度应力及界面损伤研究

针对持续高温作用下纵连板式无砟轨道结构因温度应力过大而产生严重病害的问题,提出部分解锁方案以释放其温度应力。为量化解锁后轨道结构温度应力的释放效果并探究其释放原理,建立部分解锁后CRTSⅡ板式无砟轨道数值计算模型,分析整体温升作用下层间界面损伤的演化规律和部分解锁后轨道结构对温度应力的释放效果。研究表明:整体温升作用下,由于解锁后轨道板和底座板纵向位移差较大,导致轨道结构层间损伤、离缝产生的临界整体温升较低;解锁后轨道结构层间离缝产生的临界整体温升为13℃。由于纵连板式无砟轨道结构体系的转变,且层间黏结强度随整体温升的升高而降低,解锁后轨道板和宽窄接缝的温度应力得到了部分释放;当整体温升为50℃时,轨道板纵向应力最大释放量可达17.5 MPa,相比于解锁前下降了95.5%;宽窄接缝纵向应力释放量最大可达17.35 MPa,相比于解锁前下降了95.3%。随整体温升的不断升高,层间界面损伤不断扩展,轨道板纵向约束减弱,故纵向应力反而降低;解锁后宽窄接缝温度应力随整体温升的变化规律受层间离缝面积影响,其随着整体温升升高呈先增大后减小再增加趋势。

从进出口地质结构力作用看太阳系地质递变规律

根据我国学者原创的太阳系交换地质力学,运用进口与出口地质结构理论,对交换力的形成及相互作用提出了一套新的理论,这是对力的一种新的认识。各种行星体与环境进行交换的过程中,持续产生吸收流与释放流,以及吸收力与释放力,从而推动行星体作持续运动,天体运动来源于行星体进出口地质结构交换运动。建立了一种新的力学计算体系,运用流力差公式分析了“万有引力”的来源,并揭示出:太阳对行星体只产生斥力,并不产生引力;行星体等吸收源为了自身生存的需要,必须从太阳获取物质和能量;在进口吸收力与出口释放力的相互作用下产生定向动力,自行向太阳靠近并围绕其运转;行星体等吸收源是太阳的“寄生物”;提出“推重比定律”,解释太阳与大量行星体吸收源结成交流关系时,各种行星体的运动规律;把太阳系分为低、中、高等三种速度区,从推重比与半径的关系,分析了太阳系不同区域行星体各种运动、构造形态的特点的成因,从奥尔特云到水星,对整个太阳系地质结构递变规律进行了分析。

桥上CRTSⅡ型板式无砟轨道温度力释放整治研究

研究目的:为从根本上解决CRTSⅡ型板式无砟轨道在冬季离缝夏季上拱问题,本文提出具有可行性的将纵连式轨道结构解锁成全单元结构的温度力释放方案,引入内聚力单元和混凝土损伤塑性本构建立无砟轨道温度力释放分析模型,分析不同整治方案的温度适应性,并设计全单元方案的纵横向限位方式。研究结论:(1)弱纵连方案存在轨道结构上拱病害隐患,不能有效地释放轨道结构的温度力;(2)全单元结构能够很好地适应极端温度条件,是一种可行的温度力释放方案;(3)采用全单元方案进行解锁后的轨道结构能够很好地保证横向稳定性,采取灌浆孔植入钢棒方式能保证良好的纵向稳定性;(4)本研究成果可为无砟轨道上拱病害整治提供借鉴和参考。

深大基础工程中的新技术——静力释放层的应用

利用大面积滤水层消减和释放地下水对基础底板的浮力,从而使深大基础的底板得以合理配置。

当前我国居民消费力不足的主要症结及其矫治

当前我国居民消费力不足,既存在消费力绝对水平不高的根源,也存在制约消费力充分释放或实现的症结,这是两类密切关联但却性质不同的问题。当前我国居民消费力不足的主要症结在于:一是消费力结构偏狭,尤其是消费需要能力、消费满足能力相对较低,整体拉低居民消费力。二是消费力代际转移,父辈向子辈或孙辈过度转移消费力,导致消费力闲置问题突出。三是消费力群体分化,社会收入分配差距过大持续存在,致使社会消费力严重滞后于绝对消费力。四是消费力释放阻滞,由于消费市场、消费制度、消费理念等多重影响,居民消费力难以充分、有效释放。

歌唱过程中的力学分析

歌唱过程中的力是以肌肉为动力源,在一定的歌唱运动形式和技术要求下所产生的机械能。力的运动从产生(发生)—转换(转化)—利用(作功)是一个连续、复杂、受歌唱运动目的控制的有确定方向的过程。处理好歌唱中有关力的问题,不但是美化声音的关键,更是掌握和运用各种歌唱技巧的前提和保障。

一种新型地面震击器的开发与应用

针对某些3000m以内的浅井,因大钩悬重小,采用常规地面震击器无法实现正常复位的问题,研制了一种新型地面震击器。该震击器由上接头、六方套、上筒体、心轴、调节螺母、下筒体、弹性机构总成、机械锁紧机构、延长心轴和下接头等组成。性能试验及现场应用情况表明,该震击器的所有技术参数均达到行业标准要求,复位力与释放力的大小无关,且均小于9.81kN,完全可以满足在浅井中使用地面震击器震击后顺利复位要求,应用效果很好。

YJ-A型随钻震击器应用分析及试验

震击器是将处于拉伸状态的钻具内部的潜在能量转化成动能。在震击发生后,这种动能将动力波传递给被卡的钻具,从而使钻具解卡。介绍了YJ-A型随钻震击器的结构特点、工作原理及释放力和密封试验。该震击器操作简单,性能稳定,安全可靠,磨损量小,使用寿命长,可满足陆地和海洋(包括欠平衡钻井)各种工况下钻井作业的需要。

液压震击器震击力影响因素分析

为解决液压震击器在工作时震击力偏小的问题,采用理论分析、仿真分析与试验研究的方法,根据液压震击器工况和震击原理,开展包括释放力、井深、震击器安放位置、钻井液黏度、润滑油黏度、震击器上下部钻杆数量、延时阀阀芯直径等因素对液压震击器震击力的影响分析。研究结果表明,增加一定的释放力可以增加震击力;井深越深,震击力越大;最适合安装震击器的位置在钻柱组合中和点偏上处;钻井液和润滑油的黏度越大,震击力越大;在一定范围内增大震击器上钻杆的质量,可以增大震击力,考虑刚度等原因,继续增大震击器上钻杆的质量,会导致震击力减小;阀体内径不变时,阀芯直径越大,震击力越大。

Poly-Silicon Micromachined Switch

By using LPCVD SiO 2 and poly silicon as sacrificial layer and cantilever respectively,a poly silicon micromachined RF MEMS(radio frequency microelectronic mechanical system) switch is fabricated.During the fabrication process,the stress of poly silicon is released to prevent poly silicon membrane from bending,and the issue of compatibility between RF switch and IC process technology is also resolved.The low residual tensile stress poly silicon cantilever is obtained by the optimization.The switch is tested,and the preliminary test results show:the pull down voltage is 89V,and the switch speed is about 5μs.The switch provides the potential to build a new fully monolithic integrated RF MEMS for radar and communications applications.

论扬琴演奏中力的运筹、释放与流动

本文针对扬琴演奏中肩、背、大臂、小臂、肘、腕、手、指各部位的状态,结合演奏中力的运筹、释放与流动进行了较为详细地论述。旨在使学生确立最佳的演奏状态,获取力的支持,提高演奏水平。

Effect of Silicon-on-Insulator Substrate on Residual Strain in 3C-SiC Films

One group of SiC films are grown on silicon-on-insulator （SOI） substrates with a series of silicon-overlayer thickness. Raman scattering spectroscopy measurement clearly indicates that a systematic trend of residual stress reduction as the silicon over-layer thickness decreases for the SOI substrates. Strain relaxation in the SiC epilayer is explained by force balance approach and near coincidence lattice model.

Bovine Serum Albumin (BSA) Microspheres Containing Methotrexate (MTX) I.Pharmaceutical Aspects

Microspheres Ⅰ,Ⅱ and Ⅲ were produced by emulsion technique.Microsphere I was solidified by glutaraldehyde crosslinking,microsphere Ⅱ was solidified by glutaraldehyde crosslinking and further treated with glycine solution and microsphere Illwas solidified by heating denaturation only.The results showed that the microsphere diameter produced by cross[inking was bigger than that prepared by heating.The microsphere Ⅱ had higher hydrophilicity than Microsphere I had.The methotrexate (MTX) contents in microspheres Ⅰ and Ⅱ were 2.73±0.053%,2.87±0.119% respectively. microsphere Ⅲ was only blank microspheres with MTX adsorbed on their surfaces.In vitro release studies,microspheres I and I have maintained sustained release of MTX till the next day,it was found that the drug releases from microspheres Ⅰ and Ⅱ were governed by Higuchi diffusion law.

Preparation and evaluation of ophthalmic thermosensitive in situ gels of penciclovir

Aim To develop pluronic F127 （PF127） based formulations of penciclovir （PCV） aimed at enhancing its ocular bioavailability. Methods Thermosensitive in situ gels of penciclovir were prepared through combination of HPMC K4M or carbopol 934P and pluronic F127. Optimized formulations were examined through measuring gelation temperature, rheology speciality, drug release behavior, pharmacokinetics and ocular irritation. Results The gelation temperature was reduced by adding HPMC K4M or carbopol 934P, and the viscosity was enhanced slightly. Either HPMC K4M or carbopol 934P delayed the release of PCV from in situ gel. PCV was released by non-Fickian diffusion. The study of ocular irritation for different PCV formulations did not show any irritation or damage for the cornea. PCV bioavailability from combination of carbopol 934P and pluronic F127 gels was higher than that obtained from any other gels. Conclusion Pluronic F127 formulations of PCV can be used as liquid for administration by instilling into the eye. Facilitated by the appropriate eye temperature, the formulations were transformed to gel phase. On the basis of in vitro and in vivo results, PCV formulations containing HPMC K4M or carbopol 934P and low concentration of pluronic F127 （12%） showed potential for use as a drug delivery system with improved ocular bioavailability.

Anti-Plane Elasticity Problem and Mode Ⅲ Crack Problem of Cubic Quasicrystal

The fracture theory of cubic quasicrystal was developed. The exact analytic solution of a Mode Ⅲ Griffith crack in the material was obtained by using the Fourier transform and dual integral equations theory, and so the displacement and stress fields, the stress intensity factor and strain energy release rate were determined. The results show that the stress intensity factor is independent of material constants, and the strain energy release rate is dependent on all material constants. These provide important information for studying the deformation and fracture of the new solid material.

Nitrogen Release Kinetics and Nitrification-Denitrification on Surface Sediments under Aerating Disturbance Condition

[Objective] This study aimed to investigate the nitrogen release kinetics and nitrification-denitrification on surface sediments under aerating disturbance condition, with the purpose to solve the sediment nitrogen release and secondary pollution problems. [Method] The effect of in situ sediments aeration on the release of nitrogen pollutants was investigated, and the nitrogen release kinetics parameters were analyzed. The process of nitrification and denitrification under sediments aeration condition was investigated in laboratory. [Result] The nitrogen released from sediments was enhanced by aeration disturbance. The concentration of NH4＋-N and TN reached the maximum value in 30 min, and release rates were proportional to the disturbance strength. In this study, with the distance of aerator to the sediments surface of 0, 1, 2 and 3 cm, the suspended sediments concentrations were 3.52, 3.41, 3.26 and 3.01 g/L, respectively. Maximum release concentration of NH4＋-N and TN were 14.3, 13.8, 13.2, 12.2 mg/L and 33.21, 30.98, 29.83, 27.30 mg/L, respec- tively. In addition, both NH4＋-N and TN release kinetics could be described by Double Constant Equation as InC=A＋Blnt. Nitrification reaction occurred and was promoted by continued aerating to sediments.The concentration of NH4＋-N dropped down from 12.4 mg/L to 0.2 mg/L in 8 d, with the concentration of NO3--N increased to the maximum value of 10.8 mg/L. In addition, concentration of NO3--N and TN decreased from 10.8 mg/L and 37.4 mg/L to 0.36 mg/L and 23.2 mg/L after the stop of aeration for 12 d, indicating the occurrence of denitdfication reaction. Therefore, sediment aeration could accelerate nitrogen release and nitrification reaction, and with intermittent aeration, nitrogen could be removed from sediments in-situ by nitrification and denitrification. [Conclusion] The results provided technical reference for the in situ sediment remediation for the black-odor rivers in cities.

Non-complete relief method for measuring surface stresses in surrounding rocks

The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.

Release of Soil Nonexchangeable K by Organic Acids

The amounts of soil nonexchangeable K extracted with 0.01 mL/ L oxalic acid and citric acid solutions and that with boiling 1 mL/ L HNO3 for ten minutes were remarkably significantly correlated with each other, and the amount extracted with the oxalic acid solution was higher than that with the citric acid solution. The soil nonexchangeable K release was comprised of two first-order kinetic processes. The faster one was ascribed to the interlayer K in outer sphere, while the slower one to that in inner sphere. The rate constants of the soil nonexchageable K were significantly correlated with the amounts of nonexchangeable K extracted with boiling ImL/ L HNO3 for ten minutes. Study on the fitness of different kinetic equations indicated that the first-order, parabolic diffusion and zero-order equations could all describe the release of soil nonexchangeable K. well, but Elovich equation was not suitable to describe it.