Wave Propagation Behavior in Saturated Porous Media

In this paper, an attempt is made to discuss the wave propagation behavior in saturated porous media with the decomposition of the motion equations. And it is denoted that there are two types of dilatational waves and one rotational wave. Also, the motion equations of the different waves are obtained, and the wave velocities in some special cases are calculated, from which it is concluded that permeability of media greatly affect wave propagation behavior.     

Experimental Analysis of Vibration Behavior for Large-span Underground Structure

In this paper, a shaking table test for large-span underground structure is introduced. Based on the test, the frequency of inherent vibration, damping ratio and the dynamic response of the structure are studied. The response of the underground structure for vertical seismic excitation is studied as a key point. With the different imbedding depth, the influence of interaction of soil and structure on the earthquake-resistant capacity of the underground structure is discussed.     

Mixed Finite Element Method for Dynamic Problems of Fluid Saturated Biphasic Porous Media

Based on the fluid saturated biphasic porous media model deduced from mixture theory,a finite element formulation with u S u F p variables for dynamic response analysis is given out.This method overcomes the difficulty of choosing suitable penalty parameter in penalty finite element method,and the accuracy of pressure distribution obtained with the mixed finite element method is higher than the penalty finile element method.An iterative solution method is suggested to solve the system of equations whose coefficient matrices are non positive definite.It is concluded from patch test that the order of interpolation function for pressure variables must be higher than that of displacement variables of solid phase.     

不同基质栽培百子莲生长效应评价

为探明基质不同理化性质对大花百子莲幼苗生长的影响,筛选百子莲适合的栽培基质,采用草炭、枯枝落叶腐熟肥、椰糠、松树皮、黄沙、珍珠岩、园土等材料配成8种混合基质,以园土作为对照,测定不同基质理化性质与不同基质栽培百子莲幼苗的形态、生长及相关生理指标,进行指标间相关性分析。结果显示,土壤总孔隙度、毛管孔隙度与叶片数、最大根长间存在显著正相关(P＜0.05),土壤EC值与根干重、根冠比及单叶鲜重间显著负相关(P＜0.05),土壤全钾与地上部分鲜重、地上部分干重间显著负相关(P＜0.05),表明改善土壤通气状况能够促进百子莲生长,EC值增高限制根系干物质积累、降低植株根冠比,钾素营养抑制百子莲地上、地下部分营养生长。方差分析表明,不同混合基质处理间百子莲幼苗各项指标存在极显著差异(P＜0.01),大多数配比基质百子莲生长形态指标优于园土对照,经生长指标综合评价,草炭、枯枝落叶腐熟肥、椰糠、松树皮、黄沙以2:1:1:1:1配比混合基质综合评价指数最高(0.91),其次为草炭、椰糠、黄沙以2:1:1配比基质(0.66),表明这2种混合基质较适宜百子莲生长,可在百子莲规模化生产中推广应用。     

弹性波作用下渗流多孔介质微粒运移分析

弹性波作用下渗流多孔介质微粒运移分析是对目前静态流体或稳态多相渗流中微粒运移/捕集的补充,通过分析弹性波对微粒剥离运移捕集过程的影响,建立弹性波作用下微粒运移模型,得到对微粒运移效果和储层物性变化的影响规律。由推导得到的弹性波作用下微粒剥离临界速度可知,当微粒与孔喉半径的比值越小时弹性波导致的振荡附加力影响越大,临界速度与流体粘度、微粒/孔喉半径比成负相关,与基质胶结程度、结构力、微粒半径、微粒密度成正相关。弹性波作用下微粒运移模型需同时考虑多孔介质渗流速度的变化,此时微粒剥离释放速率增加,但随着波衰减和时间延长而降低,微粒在孔隙表面沉积滞留速率先上升后下降,喉道堵塞的速率有所上升,说明弹性波作用下微粒的剥离和悬浮能力增加,但亦增加了微粒在微细孔喉"架桥"堵塞的可能性。研究结论对岩石物理学和工业化波动处理涉及的储层物性研究具有一定指导意义。     

FEM on Coupled Hydromechanical Dynamic Response of Geogrid Reinforced Soil Retaining Wall

Geogrid reinforced soil retaining wall(GRSRW) is composed of panel,geogrid and soil,its coupled hydromechanical structural characteristics are increasingly emphasized in practice.In this paper,based on the characteristics of the reinforcement-soil interaction,the grogrid and soil around it with a definite thickness were regarded as a kind of composite material with strain-compatible condition.A saturated porous media model was introduced to simulate the soil and reinforcement-soil composite material hereby and the mathematic model for numerical analysis on structural characteristics of GRSRW was built up.The FEM equations were deduced from the standard Galerkin procedure,resolving these equations,we can gain the relevant dynamic response of saturated GRSRW.     

农村受众在当前大众媒介中话语权现状及影响因素分析

为探索农村受众在当前大众媒介中话语权现状、影响因素。以东北地区农村受众为研究对象,通过对其发放问卷进行抽样调查的形式,从农村受众对媒体的信任度、运用媒介话语权的能力和媒介话语权意识方面进行分析。研究表明,农村受众在当前大众媒介中尚处于话语权缺失的状态,农村受众对媒体的信任度、运用媒介话语权的能力、媒介话语意识是主要影响因素。研究发现农村受众的媒介话语权需整体提升。     

CFD-DEM Simulation to Study the Filtration Characteristic of the Fine Particle in the Filter Media

The gas-solid two-phase flow characteristics of fine particles in the filter media were simulated based on CFD-DEM (Discrete Element Method) in this study, and the particle group, particle size distribution, and the rebound effect between particles, particle and fiber were taken into account the calculations. Additionally, the movement characteristics of the particle group and the deposition form of the fine particles in the fibrous filtration were analyzed. The results indicate that it is convenient and feasible to simulate the filtration process of the filter media as well as the deposition process and form of the fine particle on the media surface using CFD-DEM, and the simulation results are consistent with the experimental observations in the literature. The surface filtration has larger contribution to the filtration process, and most of the particles are captured by the media surface. Meanwhile, parts of smaller particles that enter into the media are captured by the depth filtration. A larger number of particles are collected by the particle-particle capture mechanism. The filtration efficiencies of the filter media are varied with the particle systems, and for the model of the filter media in this study, the filtration efficiency of the multi-particle system is about 20% higher than that of the single-particle one.     

A New Method of Separating the Shear Waves Splitting in Anisotropic Media

For azimuthal anisotropy seismic exploration, it is very important to separate the fast and slow shear waves splitting in this type of anisotropic media. Many researchers have worked on this problem, but their methods are not realistic in exploration. In this paper, a new method of separating the shear waves splitting in EDA media is presented, that can be directly applied to actual use. Through numerical examples, it can be found that the method is highly efficient and accurate.     

国内农业核心期刊新媒体应用现状分析

统计分析国内农业核心期刊新媒体应用数据和《中国科技期刊引证报告》(2015年版)农业核心期刊影响因子,旨在为新媒体环境下农业科技期刊发展策略研究提供支持。研究发现,农业核心期刊新媒体应用总体上呈现出"分散"的特点;不同学科新媒体的应用存在较大的差距;在同一学科中,应用新媒体的农业核心期刊的影响因子比未应用新媒体的期刊高。农业核心期刊新媒体应用现状拓展了科技期刊新媒体应用研究,为新媒体应用策略研究提供基础支持。新媒体应用有效提升农业核心期刊的影响力,将成为今后农业核心期刊影响力提升的主要措施。     

LIF与心肌条件液在小鼠ES细胞分离中的差异比较

通过比较LIF和大鼠心肌条件液在小鼠ES细胞分离培养过程中的差异, 从而选择较为合适的培养液用于小鼠ES细胞的分离培养与深入研究。取怀孕3.5 d小鼠囊胚, 培养于小鼠胎儿成纤维细胞饲养层上, 然后根据ES细胞培养液的不同分成2组,一组添加LIF的ES细胞培养液,另一组添加由大鼠心肌条件液组成的ES细胞培养液。结果显示,小鼠ICM的孵出率在心肌条件液中为76.30 %, LIF条件液中为59.35 %,两者差异极显著(p＜0.01)))))) ; 在LIF条件液中比心肌条件液中能较早地分离出ICM,时间差分别为11、11、12、10和12 h,平均为11.2 h; 对传代的ES细胞集落,培养48 h时周边出现分化现象的ES细胞集落所占的比例在心肌条件液中为51.55%, LIF条件液中为31.69 %,两者差异显著(p＜0.05); 第五代小鼠ES细胞核型正常率在心肌细胞条件液中为78.6 %, 稍高于LIF条件液中的76 %,差异不显著。     

简谐SH波作用下管桩的振动特性

在一维波动模型的基础上得到了简谐SH波作用下桩周土和桩芯土的位移。在三维轴对称的情况下,运用势函数和分离变量法求解了简谐水平集中荷载和SH波引起的管桩桩周土和桩芯土的振动问题,得到了桩周土和桩芯土的径向位移和环向位移。考虑管桩土动力相互作用和管桩土的连续性边界条件对简谐水平集中荷载和SH波作用下管桩的振动进行了研究,得到了管桩桩顶的动力放大因子。通过数值算例分析可知,简谐SH波作用下管桩存在共振现象;管桩管壁过薄宜导致桩基失稳;相同外径情况下采用管桩要比实芯桩的抗震性能更好。     

Frontline reporting,ethos and perception: Media challenges in the South Pacific

Abstract: The Melanesian sub‐region of the South Pacific, in particular, has been branded by some political analysts as an ‘arc of instability’ because of upheavals such as coups (Fiji), ethnic conflict (Solomon Islands), paramilitary revolts (Vanuatu), and secessionist rebellion and civil war (Bougainville‐Papua New Guinea and the Southern Highlands). Simplistic notions and prejudices about the region pose challenges for journalists attempting to report with depth, context and analytical skill. Pressures and dilemmas for the news media continue to gain momentum in the South Pacific, often from a cultural as well as socio‐political dimension. While the media in some countries is refreshingly outspoken and courageous, in others it has a trend towards self‐censorship. This article critiques coverage in the region and some of the problems in an age of globalisation and preoccupation with security. It also sketches the challenges for media education designed to contest images of the region beyond ‘coups, conflicts and contraband’.     

酿酒酵母培养条件及发酵培养基的优化

为了确定酿酒酵母的最适摇瓶发酵培养条件及最适培养基,采用单因素试验及L₉(3³)正交试验研究影响酿酒酵母生长的关键因素,包括培养温度、培养时间及摇床转速;采用单因素试验及L9(34)正交试验优化发酵培养基并进一步筛选出关键因素。结果表明：优化的培养条件为培养温度29℃,摇床转速160 r/min,培养27 h,优化的发酵培养基配方为葡萄糖20 g/L,酵母粉10 g/L,KH₂PO_{4sub> 1.5 g/L,MgSO4 1 g/L。结论：影响酿酒酵母生长的关键因素为摇瓶培养时间及培养基中葡萄糖浓度。}     

Finite Element Analysis on Electromechanical Behaviours in Bone Tissues

According to the importance of electromechancial behavior of bone on clinical medical treatment, the physiological structure of bone tissue is studied. Then the biphasic porous media theory associated with electro kinetics is used to model the electromechanical effects in bone tissue. The finite element governing equations are built up through Galerkin method and the penalty method. The distortion of skeleton, interstitial fluid flow and the streaming potential in bone tissue are numerically computed and simulated.     

黑曲霉发酵麦麸生产β-葡萄糖苷酶的培养基组成的优化

以黑曲霉为发酵菌株,研究其β-葡萄糖苷酶液体发酵的最佳培养基组成。通过对不同碳源、氮源、磷酸盐、金属离子、氨基酸、表面活性剂等单因素研究,发现麦麸、(NH_4)_2SO_4和KH_2PO_4对产酶有促进作用。3因素二次通用旋转组合设计试验得到该菌株产β-葡萄糖苷酶的优化培养基组成为:麦麸28.4 g/L,(NH_4)_2SO_41.2 g/L,KH_2PO_42.0 g/L,发酵液β-葡萄糖苷酶酶活达到(1 493.90±12.09)U/mL。     

Numerical Simulation for Dynamic Response of Large Space Cylindrical Reticulated Shell under Internal Explosion by Ritz POD Method

A numerical simulation test of the internal explosive loading on large space structure was carried out by employing algorithm ANSYS/LS DYNA.An appropriate model was established for calculating the dynamic responses of the large space cylindrical reticulated shell under inner blast loading based on the proof of correctness and reliability of the model and parameters selection.Combining the Ritz vibration mode superposition method with the Proper Orthogonal Decomposition (POD) method, the problems of spatiotemporal asynchrony of shock waveforms and pressure distributions on large space structure surface were solved and the calculation for dynamic response of large space structure was reduced and simplified.Furthermore, the numerical simulation of dynamic responses was carried out.And the influence of the ratio of rise to span and the explosive position on the dynamic responses of the structure was studied.It was found that the calculation model was suitable for the dynamic response analysis of the large space cylindrical reticulated shell under internal explosion and the cylindrical reticulated shells with bigger ratios of rise to span were stronger in the capacity of anti explosion.In general, the damages to the large space structure caused by eccentric blast shock waves were more serious than that caused by central explosion.And it was the most disadvantageous to the edge components of the structure.The more attention should be paid to the anti explosion capacity of the support areas and the edge components while designing the shells.     

2014年春季内蒙古2次大风降雪寒潮过程分析

对于环流特征相似的寒潮过程,其爆发的方式、产生的天气和影响的区域基本相似,但个别寒潮过程却存在较大的差异,造成预报上的误判。针对此类特例,基于常规气象观测资料,自动站观测资料和NCEP逐6 h 1°×1°再分析资料,应用天气学分析和诊断方法,对2014年4月24日（过程1）和5月1日（过程2）2次寒潮天气过程的环流、系统和爆发的动力、热力学机制等进行对比分析。结果表明：2次过程北半球中高纬500 hPa环流形势均具有两脊一槽的环流特征。寒潮区域升温明显,前期平均温度分别比历史同期偏高1.0~7.3℃和0.1~10.7℃,500 hPa冷槽和强锋区均在新疆北部堆积、爆发南侵;2次过程在爆发方式和成因上存在着较大的差异,过程1中促使寒潮爆发流场为横槽转竖,槽前疏散结构和正涡度平流使低槽切断出低涡并东南移,冷平流中心移至槽前,横槽转竖寒潮爆发。过程2为低槽东移,冷槽移过阿尔泰山和蒙古高原加深东移,冷空气入侵内蒙古,寒潮爆发。虽然2次过程均造成了全区范围的强降温,但由于上述影响方式和成因的不同,使得大风、沙尘暴和降水呈现出不同的影响特点。寒潮过程中大风和沙尘暴的分布除与冷平流有关外,还与高空动量下传的地点和时间密切相关,对于寒潮过程中的降水而言,低层的温度层结及其水汽输送特点,决定了不同地区的相态变化和降水的量级。通过关注环流相似寒潮过程中的爆发方式和动力过程,对于正确预报寒潮天气造成的不同地区的降温、大风、沙尘和降水具有很好的借鉴意义。     

THE OPTIMAL DESIGN CALCULATION OF te(MC)MEDIA FILTER

This paper introduces formula total water headloss of MC media filter anddiscusses the parameters of design calculation of MC media filter through the experiment.In the end,the optimal design calculation method and its program diagram are given.The method is important toguide the design of MC media filter.     

不同培养基对肠球菌的检测效果比较

肠球菌是食品、水、食品加工设备和食品生产环境等卫生状况的指示菌之一,对其进行检测的培养基种类较多。选用叠氮化钠葡萄糖肉汤和肠球菌肉汤对奶粉和水中肠球菌进行检测比较,结果表明,肠球菌肉汤具有绝对的优势,但在实际检测工作中,对不同样品进行检测时,应注意根据样品的性状合理选择培养基,以提高检测的速度和准确性。