Intact soft clay’s critical response to dynamic stress paths on different combinations of principal stress orientation

Comprehensive tests on Hangzhou intact soft clay were performed, which were used to obtain the soils’ critical response to undrained dynamic stress paths under different combinations of principal stress orientation. The different combinations included cyclic principal stress rotation (CPSR for short), cyclic shear with abrupt change of principal stress orientation (CAPSO for short) and cyclic shear with fixed principal stress orientation (CFPSO for short). On one side, under all these stress paths, samples have obvious strain inflection points and shear bands, and the excess pore water pressure is far from the level of initial effective confining pressure at failure. Stress paths of major principal stress orientation (α) alternating from negative and positive have quite different influence on soil’s properties with those in which α is kept negative or positive. On the other side, due to the soil’s strongly initial anisotropy, samples under double-amplitudes CPSR and CAPSO (or single-amplitude CPSR and CFPSO) have similar properties on dynamic shear strength and pore water pressure development tendency when α is kept within ±45°, while have quite different properties when α oversteps ±45°.     

Research advances of un-symmetric constitutive theory of anisotropic viscoelastic liquids and its hydrodynamic behavior

Research advances of un-symmetric constitutive equation of anisotropic fluid,influence of un-symmetric stress tensor on material functions,vibrational shear flow of the fluid with small amplitudes and rheology of anisotropic suspension were reported.A new concept of simple anisotropic fluid was introduced.On the basis of anisotropic principle,the simple fluid stress behaviour was described by velocity gradient tensor F and spin tensor W instead of velocity gradient tensor D in the classic Leslie-Ericksen continuum theory.Two relaxation times analyzing rheological nature of the fluid and using tensor analysis a general form of the constitutive equation of co-rotational type was introduced.More general model LCP-H for the fluid was developed.The unsymmetry of the shear stress was predicted by the present continuum theory for anisotropic viscoelastic fluid-LC polymer liquids.The influence of the relaxation times on material functions was specially studied.It is important to study the unsteady vibrational rotating flow with small amplitudes,as it is a best way to obtain knowledge of elasticity of the LC polymer,i.e.dynamic viscoelasticity.For the shear-unsymmetric stresses,two shear stresses were obtained thus two complex viscosities and two complex shear modulus(i.e.first and second one) were introduced by the constitutive equation which was defined by rotating shear rate introduced by author.For the two stability problems of fluid,such as stability of hydrodynamic flow and orientational motion,were discussed.The results show that the polymer suspension systems exhibit anisotropic character.The PNC systems can exhibit significant shear-thinning effects.For more concentrated polymer nano-suspensions,the first normal stress difference change from positive to negative,which is similar to LC polymer behavior.     

当前民办高校融资难的成因及对策

针对民办高校所需办学经费无国家财政拨款,全部为自筹资金的现状,分析了形成当前民办高校融资难的原因,既有信贷政策、银行方面的因素,也有民办高校自身的因素.提出民办高校要生存,要发展,光靠举办者投入或捐赠以及每年的学费收入是不够的,还需要积极拓展更多融资渠道解决办校融资难的问题.     

脉冲振动预磁器的研究和设计

根据细粒磁性物回收工艺中需要使用预磁器的要求,研究预磁器的工作时序、充放电回路的电器元件特性和电路电压、电流特征.设计的电磁预磁器磁场强度高,能耗低,性价比高.对预磁化电路展开理论计算和推导.首次提出脉冲振动预磁器系统结构,将RLC电路振荡波形转变为振动波形,形成"脉振"高场强,延长了线圈的使用寿命.经实际运行检验,该装置性能稳定,效果好,能耗低,每小时耗电仅0.8 kW,在预磁器领域是一项创新的实用技术.     

城市污水热能资源化的基础研究

作为城市污水热能资源化的基础研究,根据理论分析方法,对有效利用城市污水所赋存的热能时,其节能效果和对减轻大气污染的作用进行了若干分析和探讨.分别计算了流量为1 m3/s时城市污水赋存的热量,以及采暖面积为1万m2时所需的城市污水及赋存的热量,与空调、锅炉相比产生相同热量时的一次能和二次能的消减量,以及相应条件下的污染物年间(采暖期)消减量等.     

Vibrational shear flow of anisotropic viscoelastic fluid with small amplitudes

Using the constitutive equation of co-rotational derivative type for anisotropic viscoelastic fluid-liquid crystalline(LC),polymer liquids was developed.Two relaxation times are introduced in the equation:λn represents relaxation of the normal-symmetric stress components;λs represents relaxation of the shear-unsymmetric stress components.A vibrational rotating flow in gap between cylinders with small amplitudes is studied for the anisotropic viscoelastic fluid-liquid crystalline polymer.The time-dependent constitutive equation are linearized with respect to parameter of small amplitude.For the normal-symmetric part of stress tensor analytical expression of the shear stress is obtained by the constitutive equation.The complex viscosity,complex shear modulus,dynamic and imaginary viscosities,storage modulus and loss modulus are obtained for the normal-symmetric stress case which are defined by the common shear rate.For the shear-unsymmetric stress part,two shear stresses are obtained thus two complex viscosities and two complex shear modulus(i.e.first and second one) are given by the constitutive equation which are defined by rotating shear rate introduced by author.The dynamic and imaginary viscosities,storage modulus and loss modulus are given for each complex viscosities and complex shear modulus.Using the constituive equation the rotating flow with small amplitudes in gap between two coaxial cylinders is studied.     

玉米中转基因成分的定性PCR检测

利用改良 CTAB 法提取玉米产品的基因组 DNA,应用 PCR 检测方法,并以玉米特异性内源基因 IVR 为内参,花椰菜花叶病毒 35S 启动子(CaMV35S 启动子)、农杆茵胭脂碱合成酶终止子(NOS终止子)为靶基因检测玉米中是否存在转基因成分.实验结果表明,有些玉米样品中存在转基因成分,表明市场上存在未经标识的转基因玉米及其加工品.     

利用双折射晶体实现双偏振光叠加的教学研究

利用晶体的双折射现象和它的基本性质,采用现代光纤和CCD摄像放大技术手段研究了双偏振光的叠加和干涉现象,讨论了学生在教学中不易理解的难点问题.     

科技期刊版式设计略谈

对科技期刊版式设计中的标题、插图与空白的处置进行了分析探讨,认为科技期刊版式设计在总体上应是追求格式一致与节奏变化的统一,整体性与连贯性的统一.布局合理的版式设计带给期刊的是整体的和谐美,别具风格的版式设计标志着期刊的个性特征.     

解读连战先生的民族情

文章试图从两方面解读连战先生深厚的民族情.这种民族情一方面来源于他的家族,连战的先祖到台湾死也不臣服清,曾祖父至父亲三代以各种形式坚持抗日及父母对他言传身教;另一方面与他早年在祖国大陆的生活经历有关,从他对抗战和日本的态度及祖国大陆寻踪等方面体现出来.     

用声场抗性指数和不确定度限制规则确定声强测量的精度

本文对声强测量中声场抗性指数、有关判据以及不确定度限制规则作了详细的阐述。并且,选择了两组五种不同的初始测量条件,采用声强法对Jo41—4型三相异步电动机作了声功率级测定。结果表明:采用声强法进行测量时,只要按照不确定度限制规则及其判据进行,就能得到达到预期精度的测量结果。     

收发一体激光致声换能器声特性分析

设计并分析一种收发一体激光致声换能器的声学性能.利用旋转抛物面的声学反射特性,获得216.1 dB的激光声声源级和0.24°的角度分辨力.通过控制激光参数和击穿蒸馏水获得距离分辨力为4.9 mm的激光声信号,推导出该换能器接收波束和发射波束的指向性函数、波束宽度方程和指向性指数表达式.通过理论推导和数值计算,初步证明了该收发一体的激光声换能器在距离分辨力、角度分辨力和声源级3方面具备了作为图像声呐声源的必要条件,在距离分辨力上具有明显的优势.     

压力脉动法预测声场流化床最小流化速度

在内径140 mm,高1 600 mm的鼓泡流化床中,采用压力探针研究了声场流化床FCC和石英砂颗粒的流化特性,考察了声压级和频率对颗粒最小流化速度的影响。结果表明:无声场条件下,压力脉动标准方差随表观气速的增大而线性增大,声场的引入可以显著降低颗粒最小流化速度,声压级越大颗粒的最小流化速度越小;固定声压级改变声波频率,发现频率在300 Hz时颗粒最小流化速度最小。对不同声场条件下最小流化速度进行拟合,得到了声场流化床最小流化速度预测关联式。     

一种估算消声室室内声压级的新方法

JJF 1147消声室校准规程中反平方率声压级的推导公式存在一定缺陷,易导致推算出的自由声场偏差值出现“近大远小”的不合理现象,本文通过分析空气吸收因素对校准精度的影响,提出一种估算消声室室内理论声压级的新方法,在拟合模型中加入了空气吸收的衰减部分,采用非线性最小二乘法估计理论声压级,能够提高校准精度,为实际消声室校准工作提供理论依据.     

Sound transducer calibration of ambulatory audiometric system utilizing delta learning rule

An efficient calibration algorithm for an ambulatory audiometric test system is proposed. This system utilizes a personal digital assistant (PDA) device to generate the correct sound pressure level (SPL) from an audiometric transducer such as an earphone. The calibrated sound intensities for an audio-logical examination can be obtained in terms of the sound pressure levels of pure-tonal sinusoidal signals in eight-banded frequency ranges (250, 500, 1 000, 2 000, 3 000, 4 000, 6 000 and 8 000 Hz), and with mapping of the input sound pressure levels by the weight coefficients that are tuned by the delta learning rule. With this scheme, the sound intensities, which evoke eight-banded sound pressure levels by 5 dB steps from a minimum of 25 dB to a maximum of 80 dB, can be generated without volume displacement. Consequently, these sound intensities can be utilized to accurately determine the hearing threshold of a subject in the ambulatory audiometric testing environment.     

螺旋桨飞机舱室隔声技术研究

针对国内螺旋桨飞机的特点，重点对一实际飞机壁权进行了实验研究．实验结果表明，采用多层隔声结构、蜂窝刚度处理及阻尼处理、中间隔板及内装饰板弹性连接、附加声反射层等综合处理可以用较轻的重量代价获得较为理想的隔声效果．     

用主动噪声控制法改善车内声品质

以从4种类型轿车内采集到的16个不同噪声样本为评价对象,通过主观评价试验和统计分析计算建立了以心理声学客观参数描述主观评价结果的车内声品质分析模型,确定了稳态工况下车内噪声品质的主要影响因素为响度和尖锐度。并依此对声品质最差的两个样本实施了主动控制试验。试验结果表明,车内噪声的响度、尖锐度均减小。应用所建立的声品质模型进行计算,并结合二次主观评价试验结果验证声品质改善效果,两种方法均显示声品质烦躁度等级下降了5级左右,证明了主动控制方法用于改善汽车声品质的可行性和有效性。     

车站自动播音系统

本系统利用声霸卡在计算机上实现声音的录入、剪接、合成和播出．在播出时，可有自动／半自动两种状态转换，以适应千变万化的情况．     

用主动噪声控制法改善车内声品质

以从4种类型轿车内采集到的16个不同噪声样本为评价对象,通过主观评价试验和统计分析计算建立了以心理声学客观参数描述主观评价结果的车内声品质分析模型,确定了稳态工况下车内噪声品质的主要影响因素为响度和尖锐度。并依此对声品质最差的两个样本实施了主动控制试验。试验结果表明,车内噪声的响度、尖锐度均减小。应用所建立的声品质模型进行计算,并结合二次主观评价试验结果验证声品质改善效果,两种方法均显示声品质烦躁度等级下降了5级左右,证明了主动控制方法用于改善汽车声品质的可行性和有效性。     

声音媒体的数字处理技术

声音媒体是多媒体技术中的一个重要组成部分，作者分析了把连续的模拟音频信号转换成数字音频信号的技术处理过程，研究了在数字音频信号转化成声波文件后对声波文件进行进一步加工的几个主要处理手段。