天津滨海地区浅层地基土先期固结压力规律的浅谈

在土力学中,研究土的固结应力状态、蠕变和应变速率一直是一个重要的课题。随着高层建筑地基和城市地面沉降研究工作的开展,通过高压条件下的压缩试验,了解土层的应力历史及固结性质,愈发显示出它在岩土工程中的重要性,同时也为分析地面沉降机理和准确计算地基土的沉降量提供了必要的依据和参数。     

考虑应力历史影响的饱和土一维非线性固结分析

引入e—lgσ＇和e—lgkv关系研究单层地基非线性固结问题，并考虑地基应力历史的影响，通过半解析法确定地基固结过程中正常同结与超固结的分界面。采用Fortran语言编制相应的计算程序ODNCAOS，并利用该程序对考虑应力历史影响的饱和土一维非线性固结的特性进行了分析。     

双层地基一维非线性固结性状分析

由于层状土一维非线性固结问题的复杂性,其解析解一般不易求得。本文采用半解析法对多层地基一维非线性固结问题进行了求解,通过编程计算得到了相关沉降量与固结度随时间变化曲线．并详细分析了土性参数等对双层地基一维非线性固结性状的影响。     

土水特征曲线在非饱和土一维固结理论中的应用

采用Bishop有效应力原理,将Fredlund土水特征曲线模型应用在固结方程中,提出了非饱和土一维固结理论。假定土体固结分为两个阶段。第一阶段为不排水、不排气阶段,土体的变形只是因为气体的被压密而引起的。第二阶段为排水、排气阶段,土体的变形是因为孔隙水和孔隙气的排出而引起的,在此过程的基础上,建立了非饱和土一维固结方程,并进行了数值求解。     

粉土压缩变形特性试验研究

通过粉土的固结试验,研究了其应变、时间、荷载之间的关系。试验结果表明,原状粉土的压缩变形主要与其作用荷载及本身含水量、孔隙比有关。通过粉土变形与时间的关系曲线,得出此粉土变形与时间符合双曲线函数,土体变形主要表现为瞬时变形,主固结时间较短,次固结较小。     

超固结饱和土的一维固结分析

基于半解析法研究了超固结饱和土的一维固结问题,采用Fortran语言编制相应的计算程序ODLCAOS,并利用该程序对超固结饱和土的一维固结性状进行了分析。研究表明,与传统的Terzaghi固结理论所描述的不同,超固结饱和土的超静孔压消散速率与沉降发展速率并不一致,荷载和先期固结压力的大小均对固结速率有明显影响。     

加筋方式对加筋黄土强度特性影响的试验研究

通过三轴压缩试验方法,研究了土工合成材料加筋黄土在不固结不排水条件下的应力应变关系及强度特征,探讨了在不同加筋方式,主要是不同加筋层数的加筋机理。实验结果表明,通过加筋的途径可以提高黄土的强度,且加筋黄土的强度随加筋层数增多而提高,但呈非线性关系。     

Laponite RD透明土模拟软黏土的适用性分析

评估Laponite RD透明土作为岩土实验材料的适用性。首先,以透射率作为评估透明度的指标,基于透明土透射率的测量结果,给出了Laponite RD透明土适用的实验厚度范围。其次,制备不同强度的透明土试样,进行了渗透试验、固结试验、直接剪切试验和固结不排水三轴压缩试验,将透明土的物理力学指标与天然软黏土的物理力学指标进行了对比分析。试验结果表明,Laponite RD透明土的渗透性能和天然软黏土相当,固结系数却远小于多数天然软黏土,黏聚力较多数天然软黏土略小,而内摩擦角大致处于天然软黏土的分布范围内。基于试验结果分析可知,Laponite RD透明土可较好地模拟天然软黏土的渗透性能,其次是模拟强度特性,而用于模拟压缩等变形特性时则可能与实际软黏性土相距较大。     

变电站工程软土地基处理方法探究

所谓软土是指基于静水或缓流环境近代沉积的细粒土,其特点表现在较大的孔隙率、较高的含水率,并且透水性与强度相对较差等方面,并且埋藏相对较深。由于软土地基强度差,压缩固结与剪切变形过程中可能出现较大的沉降,会对建筑物的性能产生直接影响,因此要采取相应的方法对软土地基进行加固处理。本文就以某工程实例针对电站工程软土地基的方法行研究。     

土工试验数据解决岩土工程勘查中问题的探讨

土工试验主要包括土的固结试验、土的抗剪强度试验、土的固结试验成果与抗剪强度之间的关系等试验,它所获得数据可以为岩土工程勘察提供参考.本文首先对上述试验具体内容进行了介绍,接下来探讨了上述试验结果在岩土工程勘察中的应用,并分析了在上述应用中应注意的相关问题,着重介绍了上述试验过程中误差产生的原因及避免的方法.最后,我们对本文进行了小结,并且对土木试验结果在工程勘察设计及其它工程的应用进行了展望.     

药王山摩崖造像和石刻艺术研究

铜川耀县耀城东的药王山,历代人们在此修庙、建殿、塑像、立碑,被誉为医药保健名山与石刻艺术宝库。药王山造像、石刻和壁画,是千百年来人们的信仰、生活、艺术以及情感和希望的真实反映,今天研究先人们不断延伸和流淌的精神寄托仍具有现实的意义。     

民族旅游社区空间的竞争性——基于地方意义的视角

文章以郎木寺为调研区域,采用相片引导的半结构化访谈方式获取调查数据。借助质性分析软件NVivo10.0对访谈内容进行分析,依据特征将地方划分为11种类目,并构建8大类及39小类地方意义类目。研究结果显示：自然景点、佛教寺院、丧葬地点、清真寺、食宿地点和村子家乡是受访者认为最重要的地方;“地方特色”、“精神性”、“群体联系”及“情感与体验”构成了受访者地方意义的主体;不同人群对郎木寺地方意义的表征各有侧重,显示出了明显的差异性：当地居民（藏族与回族）依靠宗教和社区生活形成地方感,而外来者（游客与经营者）则主要依靠原生态文化和生计形成地方感;以游客为代表的外来者和以藏族居民为代表的当地居民对地方意义的表征存在竞争关系,这种地方意义的竞争反映了不同人群关于地方权力的博弈,成为郎木寺地方身份变化的动力,也为认识当地旅游开发过程中的复杂社会现象提供了途径。     

Making fire work: pyrotechnics and natural philosophy

Everyone is familiar with fireworks, common to festivals and celebrations across the world. At first glance, the history of science might appear to have little to do with the history of these explosive devices. However, fireworks were an important element of court culture in Europe, which relied on spectacle and festival to manifest the power of princes. From the fifteenth century, courts regularly set off fireworks around elaborate theatrical scenery and ephemeral temples, fascinating audiences with a variety of exotic motions and effects exploding in the night sky. Fireworks also intrigued natural philosophers, and over several centuries there were diverse interactions among the sciences and pyrotechny.     

Efficient point-by-point engine calibration using machine learning and sequential design of experiment strategies

Modern engines are controlled by electronic control units, which operate all the engine actuators based on the signals from various sensors in the engine. Traditionally, the control parameters of the actuators are obtained through huge amount of trial-and-error experiments. However, using traditional approach to calibrate these parameters becomes more challenging with the increasing incorporation of new technologies into advanced engines. In order to reduce the number of experiments required in the calibration process of modern engines, a novel point-by-point engine calibration approach based on machine learning methods is proposed in this study. It is an iterative procedure that, for a given operating point, sequential design of experiment (DoE) strategy is utilized to measure the responses of different engine sensors corresponding to different actuator signals, and a machine learning algorithm called initial-training-free online extreme learning machine is utilized to incrementally learn the relationship between the sensors and actuators based on the measurement acquired. In each iterative cycle, meta-heuristic optimization is performed on the machine-learning-based model to search for the best parameters, which are then used as the initial parameters for generating DoE plan of the next cycle. The iteration is repeated until the optimal parameters of that operating point are found. To verify the effectiveness of the proposed approach, experiments on both simulation engine in commercial software and real engine in test bench have been conducted. The results show that the engine calibration can be carried out with significant fewer experiments and time by using the proposed approach.     

基于Simulink运动仿真与改进自适应遗传算法的曲轴优化设计

采用了Simulink仿真软件对曲柄连杆机构进行运动仿真,得到曲轴的受力极限情况,在此基础上,得到了最大拉伸载荷和最大压缩载荷对曲轴参数的约束,以及自身参数的边界条件约束,并进一步建立了以曲轴体积最小作为目标函数的曲轴优化模型,最终运用了改进自适应遗传算法来求解该模型的最优设计参数,并将其优化设计参数结果与实际曲轴参数比较,发现用改进自适应遗传算法求得的曲轴参数更加优于曲轴的实际设计参数。     

动物繁殖学实验教学改革与创新人才培养探讨

动物繁殖学实验是动物科学专业重要的基础课程,对培养学生的创新精神和实践能力起着十分重要的作用。通过对动物繁殖学实验内容的调整,将实验内容划分为两大模块：室内实验4个,室外实验3个。实验包括验证性实验、综合性实验、设计性实验和开放性实验,重点突出综合实验。实验重视设计性及创新性,引入多媒体辅助教学,并建立全面灵活的考核体系。通过这些改革措施,提高了学生的实验兴趣、增强了学生在实验中的主动性,培养了学生的创新能力。     

A microfluidic shear device that accommodates parallel high and low stress zones within the same culturing chamber

Fluid shear stress (FSS) plays a critical role in regulating endothelium function and maintaining vascular homeostasis. Current microfluidic devices for studying FSS effects on cells either separate high shear stress zone and low shear stress zone into different culturing chambers, or arranging the zones serially along the flow direction, which complicates subsequent data interpretation. In this paper, we report a diamond shaped microfluidic shear device where the high shear stress zone and the low shear stress zone are arranged in parallel within one culturing chamber. Since the zones with different shear stress magnitudes are aligned normal to the flow direction, the cells in one stress group are not substantially affected by the flow-induced cytokine/chemokine releases by cells in the other group. Cell loading experiments using human umbilical vein endothelial cells show that the device is able to reveal stress magnitude-dependent and loading duration-dependent cell responses. The co-existence of shear stress zones with varied magnitudes within the same culturing chamber not only ensures that all the cells are subject to the identical culturing conditions, but also allows the resemblance of the differential shear stress pattern in natural arterial conditions. The device is expected to provide a new solution for studying the effects of heterogeneous hemodynamic patterns in the onset and progression of various vascular diseases.     

搞好初中生物实验教学培养学生创新能力

生物学从本质上说是一门实验性学科．新课程改革后的生物教材中生物实验的权重也在不断加大．笔者遵循能力培养原理．紧扣实验教学的关键环节．唤起学生的创新意识．使验证式实验向探究式实验转变,提高创新意识,在自主体验和设计中培养学生的创新能力．重视实验总结反思．发展创新思维．引导学生将理论运用于实践。激发学生创新的能力．实现了“学以致用”的教学目的。     

Identification of a nonlinear dynamic biological model using the dominant parameter selection method

The identification of nonlinear models sometimes encounters problems because of the limited amount of available measurements in combination with a large number of uncertain model parameters to be identified. E.g., the determination of the chemical composition of a lettuce crop is a rather expensive procedure; thus the number of experimental measurements is limited. As a result, the number of parameters of the dynamic model that can be successively identified is also limited, and the subset of the parameters to be identified must be chosen in a reasonable way.Parameter estimation for an extended nonlinear three-state model for lettuce growth in greenhouses is presented in this paper. The varying structural nitrogen concentration and water contents are the new elements included in the model. The dominant parameter selection (DPS) method was used to select a suitable set of identifiable parameters. The resulting calibrated model predicts quite well the experimental data which also include observations with severe nitrogen stress.     

氮素胁迫下的冬小麦光谱特征提取与分析

高光谱遥感是对地观测的重要技术手段，利用野外光谱仪在地面的实测工作为其在精准农业等方面的应用进行有益的尝试，可以提高作物营养诊断的精度。养分胁迫下高光谱特征提取是这一目标的地面预研究。本次试验对不同氮素养分胁迫下东小麦的不同生育期，分别观测其光谱反射率，分析其生物物理参数的变化规律和反射光谱的特征，利用导数光谱技术对叶绿素密度和叶面积指数等生物物理参量同原始光谱、一阶倒数光谱进行拟合度比较，结合养份胁迫的特点，分析建立光谱模型的可能性。叶绿素密度在可见光和近红外波段均拟合较好，拟合度在0.5左右，高于叶绿素含量与光谱反射率的拟合，而叶面积指数与冠层光谱拟合在近红外波段较好，在可见光波段拟合度较小。通过作物的光谱特征，提取其中重要的近红外反射峰值、绿峰和红端位移特征，与冬小麦的叶绿素密度、叶绿素含量等生物物理参数进行相关分析，建立了线性光谱模拟模型。提取出的特征参量均可有效地模拟生物物理参数的变化，其中叶绿素含量与近红外反射峰值的拟合度（R2)除乳熟期外，都在0.9以上；孕穗期的模拟模型也有显著的相关关系。综合分析，孕穗期是利用高光谱遥感进行作物长势和养份分诊断研究的最佳时期。