Behaviour of granular matter under gravity-induced stress gradient:A two-dimensional numerical investigation

Gravity is the most important load source in mining and geotechnical engineering,which causes both the stress level and stress gradient inside geomaterials.Different from the stress level,the influence of gravity-induced stress gradient on the behaviour of the material is still unknown.An in-deep study on it will help to promote the understanding of material behaviour,especially for those cases related to unconventional gravity such as terrestrial ng physical modelling and extraterrestrial resource exploitation(g is the terrestrial gravitational acceleration).In this study,a high-order homogenization for granular materials is proposed at first,in which the stress gradient is drawn into the constitutive representation by adopting a representative volume element(RVE).The consolidation and shear strength behaviour of RVE are then investigated by performing numerical biaxial tests.The results show that all the compressibility,shear strength,shear stiffness,volumetric deformation,and critical state behaviour show a stress gradient dependence.A coupling between stress gradient,stress level,and material properties is also observed.These observations suggest that,besides the stress level,extra attention needs to be paid to material responses related to stress gradient during engineering practices.

Influence of laser fields on the vibrational population of molecules and its wave-packet dynamical investigation

The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules. For a two-state system in laser fields, the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schrbdinger equation with the split- operator method. The calculation shows that the field parameters, such as intensity, wavelength, duration, and delay time etc. can have different influences on the vibrational population. By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state, which will benefit the light manipulation of atomic and molecular processes.

Preprocessing photospheric vector magnetograms for nonlinear force-free field extrapolation of the global corona

Nonlinear force-free magnetic field （NLFFF） extrapolation based on the observed photo- spheric magnetic field is the most important method to obtain the coronal magnetic field nowadays. However, raw photospheric magnetograms contain magnetic forces and small-scale noises, and fail to be consistent with the force-free assumption of NLFFF models. The procedure for removing the forces and noises in observed data is called preprocessing. In this paper, we extend the preprocessing code of Jiang ＆ Feng to spherical coordinates for a full sphere. We first smooth the observed data with Gaussian smoothing, and then split the smoothed magnetic field into a potential field and a non-potential field. The potential part is computed by a numerical potential field model, and the non-potential part is prepro- cessed using an optimization method to minimize the magnetic forces and magnetic torques. Applying the code to synoptic charts of the vector magnetic field from SDO/HMI, we find it can effectively reduce the noises and forces, and improve the quality of data for a better input which will be used for NLFFF extrapolations applied to the global corona.

Short-term solar flare prediction using multi-model integration method

A multi-model integration method is proposed to develop a multi-source and heterogeneous model for short-term solar flare prediction. Different prediction models are constructed on the basis of extracted predictors from a pool of observation databases. The outputs of the base models are normal- ized first because these established models extract predictors from many data resources using different prediction methods. Then weighted integration of the base models is used to develop a multi-model integrated model （MIM）. The weight set that single models assign is optimized by a genetic algorithm. Seven base models and data from Solar and Heliospheric Observatory/Michelson Doppler Imager lon- gitudinal magnetograms are used to construct the MIM, and then its performance is evaluated by cross validation. Experimental results showed that the MIM outperforms any individual model in nearly every data group, and the richer the diversity of the base models, the better the performance of the MIM. Thus, integrating more diversified models, such as an expert system, a statistical model and a physical model, will greatly improve the performance of the MIM.

Effects of Method for Returning Straw to Field on Soil Properties,Straw Decomposition and Nutrient Release

[Objectives]To alleviate the influence of meteorological conditions on soil environment(temperature and water content)and maintain high and stable grain yield.[Methods]Taking Sunzhen Experimental Station of Weinan Academy of Agricultural Sciences as the experimental base,the effects of returning double-crop wheat and corn straw to field(Twm),returning single-crop corn straw to field(Tm),returning single-crop wheat straw to field(Tw)on soil temperature,water content,straw decomposition rate and nutrient release,soil organic matter and bulk density were studied systematically.[Results]Twm treatment could effectively alleviate the effects of meteorological conditions on soil temperature and water content.The decomposition rate of straw treated with Twm was 4.7%higher than that of Tm treatment,3.8%higher than that of Tw treatment,10.5%higher than that of Tm treatment,and the decomposition rate of straw showed a trend of"first fast,then slow and then fast".The release of nitrogen from straw was basically similar to that of straw decay,and the release of potassium and phosphorus increased at first and then remained basically unchanged.The release rate of potassium was the highest,followed by phosphorus and nitrogen.The content of soil organic matter in Twm treatment increased by 11.67%annually,an annual average of 0.998 g/kg.The soil bulk density of Twm treatment decreased by 0.058 g/cm^(3) annually,an annual average of 4.29%.The fundamental reason is that Twm treatment provides conditions(temperature,water content,nutrition)for microbial growth,reproduction,enzyme production and biochemical reaction,and increases the exchange capacity of soil and external water,heat,gas and fertilizer.[Conclusions]It is expected is to help people change their understanding of returning straw to field from"quick harvest"to"fertilizer transformation".

A, ■-Ω METHOD FOR 3-D EDDY CURRENT ANALYSIS

After the field equations and the snonumuoo conditions between the interfaces for 3D eddy current problems Under various gauges were discussed, it was pointed cut in this paper that using the magnetic vector potential A. the electric scalar potential and Coulomb gauge △ .A = 0 in eddy current regions and using the magntetic scalar potential Ω in the non-conducting regions are more suitable. All field equations, the boundary conditions, the interface continuity conditions and the corresponding variational principle of this method are also given

On the Calculation of Lyapunov Indicators with Post-stabilization in a Weyl Field

We present details of a work aiming at the overestimation of Lyapunov exponents defined by the geodesic deviation equations in the previous work. The geodesic deviation vector with post-stabilization is used to compute the fast Lyapunov indicator, considered to be a very sensitive tool for discrimination between ordered or weakly chaotic motions. We make a detailed study of the dynamics in the superposed Weyl field between a black hole and shell of octopoles by using the fast Lyapunov indicator with the Poincare surface of section. In particular, we examine the effects on the dynamics around the fixed points, of varying one of the three parameters （specific energy E, specific angular momentum L and octopolar moment 0）, while keeping the other two fixed, and identify the intervals of the varying parameter where the motion is regular or chaotic.

固定污染源废气颗粒物现场测试关键性能指标校验方法的研究

传统污染源颗粒物监测方法虽保证了质量但耗时过长;而快速检测方法多以间接测量为主,测量信号与质量浓度量的对应关系无法现场进行校核。基于便携式振荡天平法采用标准膜重量直接验证方式解决了设备性能无法现场核查的难题,无需重新建立测量信号与质量浓度量的对应关系。研究表明:在水平振动为56.2~94.4 dB,垂直振动为58.4~96.5 dB条件下,测试前、后振荡天平称量值与标准滤膜定值的相对误差均不大于±3.5%,标准偏差均小于0.5%。该研究为固定污染废气颗粒物的现场快速监测提供了有效的质量保证。

基于GF-1与实测光谱数据鄱阳湖丰水期总悬浮物浓度反演

总悬浮物浓度是水质评价的重要参数之一。2015年8月,在鄱阳湖布设33个采样点,通过测量水面光谱和采集水样进行检测,获取水面遥感反射率、总悬浮物浓度和叶绿素a浓度等数据。结合实测水面遥感反射率数据与总悬浮物浓度的相关性分析,建立了单波段、一阶微分和波段比值3种反演模型,并分别进行了精度验证。研究发现,3种反演模型的拟合度(R2)均大于0. 9,其中单波段模型最优,其R2、均方根误差(root mean square error,RMSE)及平均相对误差(mean relative percentage error,MRPE)分别为0. 980 5,3. 78 mg/L和16. 99%。将该单波段模型应用于2015年8月3日的高分一号(GF-1)卫星影像数据,同样得到了较高的反演精度,R2,RMSE和MRPE分别为0. 847 7,12. 23 mg/L和35. 22%。结果表明,鄱阳湖丰水期总悬浮物浓度值总体偏低,平均值为23. 26 mg/L,高值主要集中在鄱阳湖北部通江河道及其以南的中部水域,其余水域分布较为均匀。利用2015年10月24日GF-1影像和准同步观测的21个采样点的总悬浮物浓度数据使用此模型做进一步验证,其反演精度接近于2015年8月影像验证结果,表明该模型能进一步推广应用到鄱阳湖不同时期总悬浮物浓度的反演。通过实测光谱的分析以及在遥感影像上的应用,可以为鄱阳湖总悬浮物浓度的反演以及环境监测提供参考。

广域电磁法在小秦岭地区的方法试验

小秦岭地区是我国著名的金矿矿集区,矿产资源潜力大,矿区浅部资源现已基本枯竭,深部探测刻不容缓。为探讨物探方法在该区的深部勘探效果,在该区开展了不同时段的广域电磁法测深剖面试验,同时开展了可控源音频大地电磁法作为对比。通过视电阻曲线和反演结果分析对比分析,显示广域电磁法具有抗干扰能力强,探测深度大等优点。试验结果表明,广域电磁法在小秦岭地区不同时段观测重复性好、效果佳,揭示了断裂带的深部延伸情况,探测深度超过4 km。最后总结了广域电磁法在山区工作的经验及注意事项。

Design and calibration of a high-sensitivity and high-accuracy polarimeter based on liquid crystal variable retarders

Polarimetry plays an important role in the measurement of solar magnetic fields. We devel- oped a high-sensitivity and high-accuracy polarimeter （HHP） based on nematic liquid crystal variable retarders （LCVRs）, which has a compact setup and no mechanical moving parts. The system design and calibration methods are discussed in detail. The azimuth error of the transmission axis of the polarizer as well as the fast axes of the two LCVRs and the quarter-wave plate were determined using dedicated procedures. Linearly and circularly polarized light were employed to evaluate the performance of the HHP. The experimental results indicate that a polarimetric sensitivity of better than 5.7 × 10-3 can be achieved by using a single short-exposure image, while an accuracy on the order of 10-5 can be reached by using a large number of short-exposure images. This makes the HHP a high-performance system that can be used with a ground-based solar telescope for high-precision solar magnetic field investigations.

NUMERICAL SIMULATION OF STRESS-STRAIN DISTRIBUTIONS FOR WELD METAL SOLIDIFICATION CRACKING IN STAINLESS STEEL

This paper analyzed the characteristics of welding solidification crack of stainless steels,and clearly re- vealed the the of the deformation in the molten - the pool and the solidification shrinkage on the stress - strain fields in the trail of molten - weld pool.Moreover, rheologic properties of the alloys in solid - liquid zone were also obtained by measuring the hading and unloading deform curves of the steels.As a result, a numerical model for simulation of stress - strain distributions of welding solidifi- cation crack was developed. On the basis of the model,the thesis simulated the driving force of solidifi- cation crack of stainless steels, that is, stress - strain fields in the trail of molten-weld pool with fi- nite element method.

A Non-axisymmetric Spherical α~2-Dynamo

Using the Chebyshev-tau method, the generation of oscillatory nonaxisymmetric stellar magnetic fields by the α^2-dynamo is studied in spherical geometry. Following the boundary conditions given by Schubert ＆ Zhang, the spherical α^2-dynamo consists of a fully convective spherical shell with inner radius ri and outer radius ro. A comparison of the critical dynamo numbers of axisymmetric and φ-dependent modes for different thicknesses of the convective shell and different α- profiles leads to the following qualitative results： （i） when the angular factor of α- profile is sin^n θ cosθ （n= 1, 2, 4） the solutions of the α^2dynamo are oscillatory and non-axisymmetric, （ii） the thinner the convective shell, the more easily is the nonaxisymmetric mode excited and the higher is the latitudinal wave number, （iii） the thickness of the outer convective shell has an effect on the symmetries of the magnetic fields.

A magnetic bald-patch flare in solar active region 11117

With SDO observations and a data-constrained magnetohydrodynamics （MHD） model, we identify a confined multi-ribbon flare that occurred on 2010 October 25 in solar active region 11117 as a magnetic bald patch （BP） flare with strong evidence. From the photospheric magnetic field observed by SDO/HMI, we find there are indeed magnetic BPs on the polarity inversion lines （PILs） which match parts of the flare ribbons. From the 3D coronal magnetic field derived from an MHD relaxation model constrained by the vector magnetograms, we find strikingly good agreement of the BP separatrix surface （BPSS） footpoints with the flare ribbons, and the BPSS itself with the hot flaring loop system. Moreover, the triggering of the BP flare can be attributed to a small flux emergence under the lobe of the BPSS, and the relevant change of coronal magnetic field through the flare is reproduced well by the pre-flare and post-flare MHD solutions, which match the corresponding pre- and post-flare AIA observations, respectively. Our work contributes to the study of non-typical flares that constitute the majority of solar flares but which cannot be explained by the standard flare model.

创新实践呼唤创新理论——发明问题解决理论(TRIZ)综述

研究目的:技术创新实践是一项实实在在的科学活动,既需要政策和制度保证,又需要正确运用科学理论作指导。采用科学的方法,才能达到“事半功倍”的效果。本文研究的目的是,借鉴发达国家在技术创新过程中运用的创新理论和方法,实现指导工程技术领域的技术创新活动。研究方法:查阅大量的文献和互联网信息和资料,通过调研相应的软件产品商,结合国内外知名企业应用的实例,分析、归纳和总结。研究结果:找到了一种可运用于指导工程技术创新活动的理论和方法。研究结论:本文在对科技创新的由来以及创新的传统方法进行简要阐述的基础上,论述了现代科技创新实践必须依靠科学的方法论作为理论指导。这个方法论就是当今在发达国家已经广泛应用的发明问题解决理论(TRIZ)。本文着重对TRIZ的基本原理、理论体系组成、国外应用情况进行了较为系统地阐述,并且简要地介绍了信息技术的最新成果———基于TRIZ的计算机辅助创新技术(CAI)。最后,提出了应用TRIZ指导创新实践的几点启示。

悬浮物输运的数学模型

为了研究镇江内湖悬浮物的输移运动规律,建立了二维悬浮物输运数学模型。模型考虑了风场及潮流作用下悬浮物的输运,同时还考虑了悬浮物的沉降和再悬浮机制,采用切应力概念确定悬浮物的起悬量和沉降量。在无结构网格上对水流和悬浮物输运方程进行有限体积的积分离散,应用高性能的Osher格式计算水量、动量及悬浮物输运等通量,提高了数值模拟的精度。应用2次大规模水文和悬浮物含量的野外同步监测资料对模型进行了验证。模拟值与实测值吻合较好,表明模型能合理地反映内湖水流及悬浮物的运动规律。

基于多目标决策模糊物元法的冷藏车传感器布点优化

提出了多目标决策模糊物元分析法,采用中心效果测度方法构建模糊物元矩阵,依据综合关联度对监测点进行优选,实现冷藏车厢内传感器布局的点位优化。结果表明,该方法能够在保证监测结果准确的前提下,传感器数量从27个减少到7个,降低了冷链运输成本。采用统计分析方法和温度场分析法,验证了优化后传感器布局的合理性。优化后传感器监测值具有95%以上的置信水平,优化前、后温度场分布图相似率达到90%,达到冷链运输中既节约成本又准确监测的双重要求。

在线铁谱仪中的磨粒沉降机理研究

为给研制在线铁谱仪提供理论依据 ,建立了在线铁谱仪中的磨粒沉降运动模型 ,采用有限元法仿真了直流电磁铁磁场的分布情况 ,研究了磨粒在磨粒探测器中的沉降运动机理 ,分析了油样粘度 ηc、初始高度y0 、磨粒直径D等参数对磨粒沉积位置的影响。仿真结果表明 :在两个磁极之间存在一个夹角 β的条件下 ,在线铁谱仪既具有较高的磨粒沉淀率 ,又避免了大磨粒的“堆积”。

论行动研究方法在反腐败领域的运用

行动研究作为一种扎根于真实情境的研究方法,其在反腐败领域的运用,具有独特的价值。既可以解决反腐败一线工作中的问题,提高反腐败工作的质量及一线工作者的业务素质,促进其职业发展;又可以在强化反腐败一线工作者的职业意识、增强其职业成就感的同时,推进反腐败研究范式的变革,推动反腐败理论的发展。在反腐败领域引入行动研究方法的关键节点主要包括研究的出发点、研究的实施者、研究的全过程以及研究成果的运用等。而将反腐败领域引入行动研究方法应注意的事项主要有三,即尽可能通过多种途径发现反腐败实践中存在的问题,尽可能采取多种方式开展合作研究,尽可能推进多维度的行为反思等。

同一模式在新能源物质深层分类理论中的探讨

基于对称与不对称同一模式结构及其证明;和在粒子物理中的应用初探;得出了正反原子、质子、中子质量;及其科学性论证。而今新能源一词又几乎成了这些反物质的代名词,于是可认为凡涉及这些反物质的更深层次的分类研究,也就必然等同开发新能源物质,并为之作出必要的前期性理论准备。目前正处于呼之欲出的反物质、(含理论和实验)急待深入探讨,这对于国民经济发展无疑是具有重要的战略意义。于是本文将继续应用"同一模式结构"向反物质的更深层次扩展,精确地计算出各种反介子、反夸克等等,并进行细致分类,进一步掌握模式规律,从而得出以非整质数方法查质数表与同一模式算法相结合是研究基本粒子理论的一个很有发展前景的数学工具。