Trade space for time for inspecting an earthquake cycle by modern seismological observation: The central-southern part of the Sichuan-Yunnan rhombic block

The central-southern part of the eastern border of the Sichuan-Yunnan rhombic block provides the research strategy of ‘trade space for time' with an interesting fault system, where the segments have similar focal mechanisms and cover almost continuous spectra of elapse rates. We experiment to study the seismological characteristics of different segments with different elapse rates. We employed the de-clustered earthquake catalog for the calculation of b values for each segment. The analysis revealed that different segments have similar b values,which implies that, although different segments have different periods of earthquake recurrence, the 'natural time' for the whole fault system elapses with a homogeneous pace. We extended the earthquake potential score(EPS)for nowcasting earthquakes to a quasi-EPS(q EPS). It is found that q EPS increases with the increase of elapse rates,albeit for those fault segments whose elapse rates have exceeded 1, q EPS may better reflect the seismic hazard.

Incremental Static Analysis of 2D Flow by Inter-Colliding Point-Particles and Use of Incompressible Rhombic Element

A simple method is proposed, for incremental static analysis of a set of inter-colliding particles, simulating 2D flow. Within each step of proposed algorithm, the particles perform small displacements, proportional to the out-of-balance forces, acting on them. Numerical experiments show that if the liquid is confined within boundaries of a set of inter-communicating vessels, then the proposed method converges to a final equilibrium state. This incremental static analysis approximates dynamic behavior with strong damping and can provide information, as a first approximation to 2D movement of a liquid. In the initial arrangement of particles, a rhombic element is proposed, which assures satisfactory incompressibility of the fluid. Based on the proposed algorithm, a simple and short computer program (a “pocket” program) has been developed, with only about 120 Fortran instructions. This program is first applied to an amount of liquid, contained in a single vessel. A coarse and refined discretization is tried. In final equilibrium state of liquid, the distribution on hydro-static pressure on vessel boundaries, obtained by proposed computational model, is found in satisfactory approximation with corresponding theoretical data. Then, an opening is formed, at the bottom of a vertical boundary of initial vessel, and the liquid is allowed to flow gradually to an adjacent vessel. Almost whole amount of liquid is transferred, from first to second vessel, except of few drops-particles, which remain, in equilibrium, at the bottom of initial vessel. In the final equilibrium state of liquid, in the second vessel, the free surface level of the liquid confirms that the proposed rhombing element assures a satisfactory incompressibility of the fluid.

Fault plane solutions in Sichuan-Yunnan rhombic block and their dynamic implica-tions

Harvard Centroid Moment Tensor （CMT） solutions for earthquakes from 1977 to 2004 showed that the stress fields are obviously different in northwestern Sichuan sub-block （NWSSB）, western parts of Central Yunnan sub-block （CYSB） and eastern part of CYSB. The characteristics of the mean stress fields in these three regions are obtained by fitting to CMT solutions. The stress state in NWSSB is characterized by its sub-horizontal tensile principal axis of stress （T axis） in roughly N-S direction and west dipping compressive principal axis of stress （P axis）; the one in western part of CYSB is characterized by its ENE dipping T axis and sub-horizontal medium principal axis of stress （B axis） in roughly N-S direction; the one in eastern part of CYSB is characterized by its sub-horizontal P axis in roughly NNW-SSE direction and sub-horizontal T axis in roughly WSW-ENE direction. Finite element method simulation clearly shows that the Indian Plate imposes great extrusion on Sichuan-Yunnan rhombic block （SYRB） near Assam massif. The value of the simulated compressive principal stress decreases with the distance from Assam massif. The simulated directions of the T axes in SYRB form annular distribution encir cling Assam. For a homogeneous elastic medium with free boundary conditions on the top and bottom surfaces as well as the displacement boundary conditions derived from the GPS observations on the lateral boundaries, the computation results are consistent with the Harvard CMT solutions in NWSSB and western part of CYSB, while inconsistent with the Harvard CMT solutions in eastern part of CYSB. The inconsistency in eastern part of CYSB can be reduced when it includes inhomogeneous elastic media. The stress states in NWSSB and western part of CYSB revealed by the Harvard CMT solutions are not local, which are mainly controlled by the boundary force on the whole region. On the other hand, the stress state in eastern part of CYSB given by the Harvard CMT solutions is local, which may be affected by local topography, material inhomogeneity, and the drag force underneath.

Precise Location of Earthquakes at the Eastern Boundaries of the Sichuan-Yunnan Rhombic Block

Based on the seismic station data sets from Sichuan and Yunnan provinces,we employed a multi-step seismic location method( Hypo2000 + Velest + HypoDD) to precisely locate the 7,787 earthquakes that occurred during 2010-2015 along the eastern boundaries of the Sichuan-Yunnan rhombic block,namely from southern Dawu to the Qiaojia segment.The final results show that location precision is greatly advanced and epicenter distribution exhibits good consistency with the linear distribution of the seismic faults. Earthquake distribution is quite intensive at the intersection region in the southern segment of the Xianshuihe fault,the Anninghe fault zone,the Xiaojinhe fault zone and the Daliangshan fault zone to the east. The depth profile of seismicity shows a clear stepwise activity along the active seismic fault zones. The profile crossing the faults of the Xianshuihe,Anninghe,and Daliangshan presents a complex interaction among faults near the multiple faults intersection region,Shimian,where the earthquakes are obviously divided into two groups in depth. Earthquakes are very rare at the depth of 15km-20 km,which is consistent with the region of the plastic rheology between 14km-19 km calculated by Zhu Ailan et al.,( 2005).

Design, Manufacture and Measurements of Beta-Type Stirling Engine with Rhombic Drive Mechanism

The purpose of carrying out present work is to design, build and test a rhombic drive Stirling engine with a β-type configuration consisting of two dynamic pistons (displacer and power) reciprocates in the in-line concentric cylinder arrangement. The displacement rod is assembled concentrically inside the power piston rod. The rhombic drive mechanism is proposed in such a way that, by using a pair of gear wheels the sliding motion of both piston rods is controlled and thus, an engine is balanced. The developed prototype has a swept volume of 75 cm3 with the displacer piston and power piston cylinder hot ends heated by liquefied petroleum gas (LPG) burner and cooled water, respectively. It uses air as the working gas at atmospheric pressure for initial charging of the engine. Several designs were studied before settling on a β-type configuration. The LPG gas burner was considered as a potential heat source. The various elements of an engine (heater, cooler, re-generator, flywheel and piping systems) were designed, constructed and analyzed. The testing results revealed that the engine at initial atmospheric air filling started working in only about 120 seconds at an LPG heater temperature of 400℃ (824°F) with 280 rpm. At a heater temperature of 550℃ (1022°F), the engine speed was 630 rpm. At the engine speed of 245 rpm, the maximum torque was 0.215 Nm, while the maximum power was 8 Watts at 355 rpm. Engine speed increased with the increase of flame temperature. Several tests were performed on the engine to improve its running efficiency and critical problem areas were isolated and addressed. Moreover, results revealed that Stirling engines working with relatively low-temperature air are potentially attractive engines of the future, especially LPG powered low temperature differential Stirling engines. The Stirling engine was capable of generating between 50 to 100 Watts of electricity.

The Recent Crustal Deformation on the Sichuan-Yunnan Rhombic Block Boundaries

Based on data from an across-fault survey along the Sichuan-Yunnan rhombic block boundaries, the recent deformation characteristics on each fault have been analyzed. It was found that the rate of crustal deformation is slowing down along the northern segment and increasing along the southern segment. Each fault has different features of deformation. The horizontal deformation is mainly characterized by left-lateral strike-slip. The rate of vertical deformation is less than that of the horizontal deformation. The faults have the feature of upper wall uplifting alternated with descending. The anomaly changes of crustal deformation at some sites are closely related to the seismicities near the sites.

Classical spin liquid state in a rhombic lattice metal-organic framework

Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimensional(2D)rhombic lattice Fe-metal-organic framework(Fe-MOF)with frustrated antiferromagnetism.This Fe-MOF exhibits a high frustration factor f=|θCW|/TN≥315,and its long-range magnetic order is suppressed down to 180 mK.Detailed theoretical calculations demonstrate strong antiferromagnetic coupling between adjacent Fe3+ions,indicating the potential of a classical spin-liquid-like behavior.Notably,a T-linear heat capacity parameter,γ,originating from electronic contributions and with magnetic field independence up to 8 T,can be observed in the specific heat capacity measurements at low-temperature,providing further proof for the spin-liquid-like behavior.This work highlights the potential of MOF materials in geometrically frustrated systems,and will promote the research of exotic quantum physics phenomena.

Finite Element Prediction of Residual Stress in Rhombic Dodecahedron Ti‑6Al‑4V Titanium Alloy Additively Manufactured by Electron Beam Melting

In this work,a three-dimensional nonlinear transient thermo-mechanically coupled finite element model(FEM)is established to investigate the variation in temperature and stress fields during electron beam melting(EBM)of rhombic dodecahedron Ti-6Al-4V alloy.The influence of the processing parameters on the temperature and residual stress evolutions was predicted and verified against existing literature data.The calculated results indicate that the interlayer cooling time has very little effect on both the temperature and stress evolutions,indicating that the interlayer cooling time can be set up as short as possible to reduce manufacturing time.It is presented that the residual stress of the intersection is higher than that of non-intersection.With increasing preheating temperature,the residual stress decreases continuously,which is about 20%–30%for every 50℃rise in temperature.The temperature and stress fields repeated every four layers with the complex periodic scanning strategy.Both x and y-component residual stresses are tensile stresses,while z-component stress is weak compressive or tensile stress in typical paths.It is proposed that the interlayer cooling is necessary to obtain a rhombic dodecahedron with low residual stress.These results can bring insights into the understanding of the residual stress during EBM.

Simultaneous formation of trimetallic Pt-Ni-Cu excavated rhombic dodecahedrons with enhanced catalytic performance for the methanol oxidation reaction

Multimetallic Pt-based alloys with excavated structures have attracted great interest owing to their compositional and morphological tunability, high specific surface areas, and impressive electro-catalytic activities. Herein, we report the first facile one-pot synthesis of trimetallic Pt-Ni-Cu highly excavated rhombic dodecahedrons （ERDs） with a yield approaching 100%. More importantly, these highly uniform nanocrystals have three-dimensionally accessible excavated surfaces, where abundant stepped atoms are observed. Benefiting from the highly excavated rhombic dodecahedral structures, electronic and synergistic effects within the trimetallic allo3~ and abundant stepped atoms, the as-prepared trimetallic Pt-Ni-Cu ERDs exhibit an enhanced electro-catalytic performance for the electro-oxidation of methanol compared to commercial Pt/C and bimetallic Pt-Cu ERDs and Pt-Ni-Cu solid rhombic dodecahedrons solid rhombic dodecahedrons （SRDs）.

偏载作用下菱形负刚度隔振系统的刚度特性

为探究偏载对菱形负刚度隔振系统刚度的影响,课题组基于力学分析方法,建立了偏载作用下隔振系统的数学模型,得到其无量纲刚度-位移非线性曲线,分析了偏载对其准零刚度特性的影响。利用Simulink进行仿真实验,给偏载作用下的隔振系统振动基座施加激励,得到了不同激励下隔振系统的时变刚度;结合傅里叶变换,探讨了隔振系统刚度的时变特性和幅频特性。结果表明:偏载越大,低刚度区间越窄,准零刚度特性越弱;时变刚度波动范围与峰值随偏载的增加而变大,但时变刚度的波动趋势不受偏载的影响;时变刚度幅值主要集中在低频区间,随频率的增加而减小,最终趋近于0。研究表明偏载对隔振系统的刚度会产生一定的影响。

Construction of rhombic triacontahedron discrete global grid systems

Discrete Global Grid System(DGGS)is a new multi-resolution geospatial data modeling and processing scheme for the digital earth.The icosahedron is commonly regarded as an ideal polyhedron for constructing DGGSs with small distortions;however,the shape of its face is triangular,making it difficult to incorporate the matrix structure used for geospatial data storage and parallel computing.To overcome this limitation,this study utilizes the rhombic triacontahedron(RT)as the basic polyhedron to construct DGGSs.An equal-area projection between the surface of RT and the sphere is developed and used to design a grid-generation algorithm for the aperture 4 hexagonal DGGS based on RT.Compared with the equal-area DGGS based on the icosahedron,the proposed scheme results in smaller angular projection distortions,with the mean and standard deviation decreasing by 41.6%and 30.9%,respectively.The grid cells of the RT DGGS also achieve more optimized geometric characteristics in shape compactness,length deviation,and angle deviation than those in the icosahedron DGGS.Additionally,the cross-surface computation efficiency provides advantages in code conversion to latitude and longitude and proximity queries.Furthermore,the use of RT offers a new and better framework within the context of DGGS research and application.

辅助站立坐便器设计与试验

针对老龄人及行动不便患者在如厕时存在难以自行站立的问题,设计了一款辅助站立坐便器。首先在对人体自然站立阶段分析的基础上采集了关节运动轨迹数据,提出了辅助站立装置要尽可能地还原自然站立状态需要满足三个原则;其次对菱形传动机构进行分析计算,并对关节理论轨运动迹进行了评估;再次设计了辅助站立机构的功能尺寸,并对其运动稳定性进行了评价;最后通过搭建的原型装置完成了辅助站立实验,结果表明髋关节与肩关节位移幅值分别为22cm和46cm,与自然站立采集结果基本吻合。辅助装置可以还原自然站立状态。

仿生双菱形肋边多胞薄壁结构的耐撞性能研究

为提高汽车吸能盒结构耐撞性,受毛竹微观结构启发,提出3种不同的仿生双菱形肋边多胞薄壁结构。建立仿生双菱形肋边多胞薄壁结构的有限元模型,通过有限元仿真对比研究仿生双菱形肋边多胞薄壁结构与传统八边形多胞薄壁结构的耐撞性。分析双菱形肋边布置方式、内层壁厚等因素对新型薄壁结构吸能特性和变形模式的影响。结果表明,与传统八边形多胞薄壁结构相比,仿生双菱形肋边多胞薄壁结构的吸能特性有了明显的提升;双菱形肋边布置方式和内外层壁厚对结构吸能特性均有一定影响;随着内层壁厚的增加,结构最大峰值力减小,但总能量吸收和比吸能减少,载荷平稳度降低。仿生双菱形肋边多胞薄壁结构能有效降低乘员在汽车正面碰撞中所受的伤害,可应用到新能源汽车吸能盒的设计开发中。

Hydrothermal Synthesis, Characterization and Photoluminescence Properties of GdOHCO3 Rhombic Microcrystals

GdOHCO3 rhombic microcrystals were synthesized by hydrothermal method with urea used as the preci- pitator. Experimental parameters, such as the molar ratio of the starting reagents, reaction temperature and reaction time were examined. The as-obtained product was characterized by powder X-ray diffraction（XRD）, field-emission scanning electron microscopy（FESEM）, X-ray photoelectron spectroscopy（XPS）, Fourier transform infrared spec- troscopy（FTIR） and spectrofluorometry. The main reactions to form GdOHCO3 were proposed. In addition, the pho- toluminescence（PL） properties of GdOHCO3 rhombic microcrystals were discussed. The broad band located between 350 nm and 600 nm in the emission spectrum can be attributed to the self-trapped exciton luminescence.

Characteristics of strong earthquake evolution around the eastern boundary faults of the Sichuan-Yunnan rhombic block

Based on the existing materials of fault segmentation,characteristic earthquakes,and their empirical relationships,we calculated the parameters of the fault segments,such as length,width,magnitudes of characteristic earthquakes,etc.Constrained by GPS velocity field,the slip rates of these fault segments in depth were inversed using the 3-D half-space elastic dislocation model.As not all of the recurrence periods and co-seismic displacements of characteristic earthquakes are known,we selected the fault segments with these two parameters known and calculated the accumulation rate of average co-seismic displacement,which shows the faults' slip rate in seismogenic layer.Then,the slip rate in depth was compared with that in seismogenic layer,the relationship between them was obtained,and this relationship was used to get the recurrence periods and co-seismic displacements of all fault segments.After the studies above,we calculated the co-seismic deformation field of all the earthquakes larger than M s 6.8 from AD 1700 one by one and inversed the potential displacement in the co-seismic deformation field.Then,we divided the potential displacement by the slip rate from GPS inversion to get the influences of these fault segments,added the influences into the elapsed time of the characteristic earthquakes,and obtained the earthquake hazard degree of all the segments we studied in the form of the ratio of elapsed time to recurrence period;so,we name the ratio as the Impending Earthquake Risk (IER).Historical earthquake cases show that the fault segment is in safety when the IER is less than 1 but in danger after the IER becomes larger than 1.In 2009,the IER is larger than 1 on the following segments,1.35 on the Tagong segment of Xianshuihe fault,1 on the Menggu-Dongchuan segment,1.04 on the Dongchuan-Xundian segment,and 1.09 on the Yiliang-Chengjiang segment of Xiaojiang fault.

类菱形肋片流道印刷电路板换热器热工水力特性研究

为研究类菱形肋片流道印刷电路板换热器热工水力特性,采用数值模拟方法,以冷侧超临界二氧化碳(S-CO_(2))和热侧气态CO_(2)为工质,分析了冷侧进口温度313.15~353.15 K,热侧进口温度553.15~593.15 K,冷热侧热工水力特性的变化,比较了NACA0030翼型肋片流道和类菱形肋片流道的综合性能。结果表明:S-CO_(2)入口温度增大40.0 K,总换热量减小23.91%,冷、热侧压降分别增大29.95%、11.14%;气态CO_(2)温度增大40.0 K,总换热量增大16.40%,冷、热侧压降分别增大9.42%、7.43%,S-CO_(2)入口温度变化对热工水力特性的影响更明显;类菱形肋片流道印刷电路板换热器有着更小的流动阻力和较好的综合性能。该研究结果对间断型印刷电路板换热器设计有一定的参考意义。

菱形三十面体六边形全球离散格网系统构建算法

全球离散格网系统是递归剖分整个地球空间形成的多分辨率离散地球参考模型,有助于建立以空间位置为主键的多源数据关联融合新模式。正二十面体的三角面不利于建立格网单元行列索引,且生成的球面格网单元存在较大形状差异,对此,该文采用面数更多、结构更优的菱形三十面体构建六边形全球离散格网系统。首先,在单个菱形面上建立离散斜坐标系描述多种孔径六边形剖分产生的多分辨率格网;其次,根据菱形三十面体的几何属性确定跨面单元归属,据此拼接各面上的多分辨率单元,构成封闭三十面体上的格网系统;最后,通过Snyder等积多面体投影将封闭菱形三十面体上的格网系统映射至球面。实验结果表明,相比二十面体的同类成果,菱形三十面体六边形全球离散格网系统的几何属性和应用潜力更好,有助于建立地球空间信息数据的高精度承载模型。

反向支撑弧形菱形幕墙施工技术

通过对某火车站的幕墙技术阐述,详细分析了装饰幕墙与仿生结构融合的技术要素、实施途径与关键技术。工程实践表明,类似结构与装饰的融合设计,尤其是不同专业间的融合处理,需要在前期反复进行可行性分析与论证,综合考虑材料的工艺制作及偏差处理的可操作性。针对弧形幕墙的曲面效果,提出玻璃热弯法、折线拟合法、玻璃冷弯法3种方法,需综合考虑经济投入与效果。所述相关实施途径与关键技术可为类似工程提供参考。

高速铁路站房反向支撑弧形菱形幕墙施工技术研究

本文通过对江门站幕墙技术的阐述,分析了装饰幕墙与仿生结构融合的技术难点、关键技术和实施途径。工程实践结果表明,类似结构与装饰融合设计,尤其是不同专业间的融合处理,需要在前期进行反复可行性分析与论证,综合考虑材料的工艺制作及偏差处理的可操作性。本文通过仿生结构设计和幕墙的协同研究,创新地解决了反向支撑弧形菱形幕墙体系的难点,实现了幕墙的曲面弧度线型,整体效果良好,较好地实现了施工技术与设计协同。