Macroscopic and microscopic mechanical behavior and seepage characteristics of coal under hydro-mechanical coupling

Understanding the physical,mechanical behavior,and seepage characteristics of coal under hydro-mechanical coupling holds significant importance for ensuring the stability of surrounding rock formations and preventing gas outbursts.Scanning electron microscopy,uniaxial tests,and triaxial tests were conducted to comprehensively analyze the macroscopic and microscopic physical and mechanical characteristics of coal under different soaking times.Moreover,by restoring the stress path and water injection conditions of the protective layer indoors,we explored the coal mining dynamic behavior and the evolution of permeability.The results show that water causes the micro-surface of coal to peel off and cracks to expand and develop.With the increase of soaking time,the uniaxial and triaxial strengths were gradually decreased with nonlinear trend,and decreased by 63.31%and 30.95%after soaking for 240 h,respectively.Under different water injection pressure conditions,coal permeability undergoes three stages during the mining loading process and ultimately increases to higher values.The peak stress of coal,the deviatoric stress and strain at the permeability surge point all decrease with increasing water injection pressure.The results of this research can help improve the understanding of the coal mechanical properties and seepage evolution law under hydro-mechanical coupling.

反向混合并联Micro LED/OLED显示器件的驱动IC控制

提出一种集成蓝光微发光二极管(Micro LED)和红绿光有机发光二极管(OLED),具有特殊子像素排列的新型无源驱动全彩显示器件.该器件无需巨量转移就可实现全彩化显示,且较传统全彩OLED及Micro LED,器件效率更高,寿命更长.另外,将蓝色与绿色子像素反向并联,可以减少电极走线,提高器件像素密度.针对该器件的特殊结构,设计一套全新的驱动方案,具体以现场可编程逻辑门阵列FPGA作为主控制器,利用驱动芯片提供稳定的电流点亮LED,实现器件的全彩显示.通过仿真测试进一步验证了该器件良好工作的可行性.

Power Supply of Macro-Micro Driven Linear Piezoelectric Motor

To investigate a novel macro and micro driven linear piezoelectric motor composed of an ultrasonic motor with macro movement and a piezoelectric actuator with micro movement,a digital signal processing(DSP)based macro and micro power supply is designed,which fits the new linear piezoelectric motor.The power supply comprises a control circuit,a voltage conversion circuit,an amplifier circuit,a half-bridge module,an optical isolatorsdrive circuit,etc,where the DSP of TMS320F28335 is used as the controller.When the linear piezoelectric motor working in a macro driven state,the power supply outputs alternating currents with high frequency and high voltage,which drives the linear piezoelectric motor dynamically at an ultrasonic frequency;while working in the micro driven state,the power supply outputs direct currents with high voltage,which drives the linear piezoelectric motor in micro driven statically.Here a prototype of the macro-micro power supply is designed.After a series of experiments on the power supply with and without loads,the results show that the power supply can drive and control the macro micro driven linear piezoelectric motor,and realizes quick and seamless switch between macro and micro drive.In addition,the power supply can drive and control the ultrasonic motor or piezoelectric ceramic micro actuator individually.The power supply achieves the multiple parameters of output signals adjustable simultaneously and exhibits good control characteristics.

Effect of dry-wet cycles on dynamic properties and microstructures of sandstone:Experiments and modelling

Underground pumped storage power plant(UPSP)is an innovative concept for space recycling of abandoned mines.Its realization requires better understanding of the dynamic performance and durability of reservoir rock.This paper conducted ultrasonic detection,split Hopkinson pressure bar(SHPB)impact,mercury intrusion porosimetry(MIP),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure damage.The results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 MPa.The sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock particle.The pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle deterioration.The numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are dominant.The dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.

EXPERIMENTAL STUDY ON THE MACRO-AND MICRO- CHARACTERISTICS OF THE SPRAY FROM A PRESSURE SWIRL NOZZLE

The experimental study on the macro and micro characteristics of the spray from a pressure swirl nozzle embraces the growth of surface unstable wave,disintegration process,spray angle,breakup length and so on.The effects of injection pressure,nozzle geometry and liquid properties on these characteristics are also discussed.The results are helpful to understand the underlying physics of the pressure swirl nozzle and serve as the basis for the practical design,usage and improvement of the nozzle.

The Influence of Macro and Micro Contexts on Teaching and Learning in the Classroom

This paper is based on three observations and independent thinking of the classroom teaching of the author’s colleagues.It attempts to examine how macro and micro contexts affect teaching and learning in the classroom.The author focuses the discussion on three aspects:(i)the present EFL contextual setting in China;(ii)the influence of the evaluation system on both teachers and students;(iii)his own beliefs as a teacher.Finally,he comes to the implications that teachers should often reflect on their teaching by means of observing other teachers’teachings;In order to bring more effective teaching and learning to the class,Teachers should change their class from a teacher-centered one to a students-centered one.

An overview of laser-based multiple metallic material additive manufacturing: from macro- to micro-scales

Additive manufacturing(AM)is an emerging customized three-dimensional(3D)functional product fabrication technology.It provides a higher degree of design freedom,reduces manufacturing steps,cost and production cycles.However,existing metallic component 3D printing techniques are mainly for the manufacture of single material components.With the increasing commercial applications of AM technologies,the need for 3D printing of more than one type of dissimilar materials in a single component increases.Therefore,investigations on multi-material AM(MMAM)emerge over the past decade.Lasers are currently widely used for the AM of metallic components where high temperatures are involved.Here we report the progress and trend in laser-based macro-and micro-scale AM of multiple metallic components.The methods covered in this paper include laser powder bed fusion,laser powder directed energy deposition,and laser-induced forward transfer for MMAM applications.The principles and process/material characteristics are described.Potential applications and challenges are discussed.Finally,future research directions and prospects are proposed.

Macro-and Micro-Properties of Two Natural Marine Clays in China

In this paper,macro-and micro-properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that：（1）both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.（2）An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featured by small and medium-sized pores.The differences in their macro-and micro-properties can be attributed to different sedimentation environments.

Recent Advances in Computational Simulation of Macro-,Meso-,and Micro-Scale Biomimetics Related Fluid Flow Problems

Over the last decade, computational methods have been intensively applied to a variety of scientific researches and engineering designs. Although the computational fluid dynamics （CFD） method has played a dominant role in studying and simulating transport phenomena involving fluid flow and heat and mass transfers, in recent years, other numerical methods for the simulations at meso- and micro-scales have also been actively applied to solve the physics of complex flow and fluid-interface interactions. This paper presents a review of recent advances in multi-scale computational simulation of biomimetics related fluid flow problems. The state-of-the-art numerical techniques, such as lattice Boltzmann method （LBM）, molecular dynamics （MD）, and conventional CFD, applied to different problems such as fish flow, electro-osmosis effect of earthworm motion, and self-cleaning hydrophobic surface, and the numerical approaches are introduced. The new challenging of modelling biomimetics problems in developing the physical conditions of self-clean hydrophobic surfaces is discussed.

Numerical Simulation of Macro-and Micro-structures of Intense Convective Clouds with a Spectral Bin Microphysics Model

By use of a three-dimensional compressible non-hydrostatic convective cloud model with detailed microphysics featuring spectral bins of cloud condensation nuclei （CCN）, liquid droplets, ice crystals, snow and graupel particles, the spatial and temporal distributions of hydrometeors in a supercell observed by the （Severe Thunderstorm Electrification and Precipitation Study） STEPS triple-radar network are simulated and analyzed. The bin model is also employed to study the effect of CCN concentration on the evolution characteristics of the supercell. It is found that the CCN concentration not only affects the concentration and spectral distribution of water droplets, but also influences the characteristics of ice crystals and graupel particles. With a larger number of CCN, more water droplets and ice crystals are produced and the growth of graupel is restrained. With a small quantity of CCN the production of large size water droplets are promoted by initially small concentrations of water droplets and ice crystals, leading to earlier formation of small size graupel and restraining the recycling growth of graupel, and thus inhibiting the formation of large size graupel （or small size hail）. It can be concluded that both the macroscopic airflow and microphysical processes influence the formation and growth of large size graupel （or small size hail）. In regions with heavy pollution, a high concentration of CCN may restrain the formation of graupel and hail, and in extremely clean regions, excessively low concentrations of CCN may also limit the formation of large size graupel （hail）.

交流驱动无电学接触GaN基Micro⁃LED器件光电特性

针对Micro‐LED器件微型化带来的尺寸效应、高速巨量转移、发光器件与驱动背板的高精度键合等问题,本文通过金属有机化学气相沉积和原子层沉积技术制备了一种垂直结构的交流驱动无电学接触型GaN基Micro‐LED器件,研究了其光电特性。结果表明,器件电路模型可等效为RC电路,随着交流驱动信号频率的增大,器件等效阻抗先快速减小后趋于稳定。当频率固定时,器件I⁃V特性呈线性关系,器件等效阻抗稳定,器件亮度随着驱动电压增大而增强。当驱动电压固定时,器件在16~22 MHz频率范围内达到最大亮度,且亮度随频率增加呈现先上升后下降趋势;此外,由于回路呈电容特性,无电学接触型Micro‐LED器件存在发光延迟效应和电流超前效应。对比传统Micro‐LED器件,无电学接触型Micro‐LED器件与外部电极无电学接触,在交流驱动条件下实现内部载流子复合发光,有望解决Micro‐LED芯片微型化带来的技术难题。

Sedimentary Micro-facies and Macro Heterogeneity of Reservoir Beds in the Third Member of the Qingshankou Formation,Qian'an Area,Songliao Basin

An analysis of drill cores and well logs shows that the main micro-facies of the third member sand bodies of the Qingshankou Formation in Qian＇an are subaqueous distributary channel facies, sheet sand facies and subaqueous fan facies （olistostrome）. Maps showing the distribution of these micro-facies together with inter-channel bay and prodelta mocro-facies are presented for different time-slices （lower, middle and upper parts of the Qingshankou Formation）. These maps reveal the instability and change of sediment transport in the Baokang sedimentary system during the depositional period. Sediment transport was from the west in the early stage, from the south in the middle stage and from the northwest in the late stage. Values of thickness, porosity and permeability of the sand bodies in the third member of the Qingshankou Formation show that they have low to medium porosity and low permeability, and are characterized by serious reservoir heterogeneity. The joints between micro-facies and subaqueous fan micro-facies are characterized by the highest heterogeneity, the sheet sand and distal sand bar subfacies come next, and the heterogeneity of the subaqueous distributary channel sand bodies is relatively weak.

Recent Advances in One‑Dimensional Micro/Nanomotors:Fabrication,Propulsion and Application

Due to their tiny size,autonomous motion and functionalize modifications,micro/nanomotors have shown great potential for environmental remediation,biomedicine and micro/nano-engineering.One-dimensional(1D)micro/nanomotors combine the characteristics of anisotropy and large aspect ratio of 1D materials with the advantages of functionalization and autonomous motion of micro/nanomotors for revolutionary applications.In this review,we discuss current research progress on 1D micro/nanomotors,including the fabrication methods,driving mechanisms,and recent advances in environmental remediation and biomedical applications,as well as discuss current challenges and possible solutions.With continuous attention and innovation,the advancement of 1D micro/nanomotors will pave the way for the continued development of the micro/nanomotor field.

A Fractional Micro-Macro Model for Crowds of Pedestrians Based on Fractional Mean Field Games

Modeling a crowd of pedestrians has been considered in this paper from different aspects. Based on fractional microscopic model that may be much more close to reality, a fractional macroscopic model has been proposed using conservation law of mass. Then in order to characterize the competitive and cooperative interactions among pedestrians, fractional mean field games are utilized in the modeling problem when the number of pedestrians goes to infinity and fractional dynamic model composed of fractional backward and fractional forward equations are constructed in macro scale. Fractional micromacro model for crowds of pedestrians are obtained in the end. Simulation results are also included to illustrate the proposed fractional microscopic model and fractional macroscopic model, respectively. © 2014 Chinese Association of Automation.

Macro-Micro-Anatomy of the Lingual Artery

The macro-micro-anatomy of the lingual artery of 25 adult cadavers wasstudied.The origin of the artery is rather concentrated and the greater cornu of thehyoid bone can be used as the indicator.The entrance of the artery into the hyoglossusmuscle is almost constantly along the posterior border of the muscle,where the artery issuperficially located and easily to be exposed,and has a constant relationship with thevein and hypoglossal nerve.Thus the lingual artery can be used as the artery of a recipientarea in case of tongue reconstruction.The deep lingual artery has two types ofbranches;the short ones mainly supply the muscles of tongue while the long ones mainlysupply the mucosa by forming a submucosal network.In the muscles of tongue,minutearterioles run tortuously along the muscular fibers with abundant anastomoses betweeneach other,but no anastomosis is found to cross over the rnidline of the tongue.Be-neath the mucosa,there is an arterial network spreading all over the whole tongue notlimited to one side.The relationship of the arterial architecture to the structure and thefunctions of the tongue and its clinical significance were discussed.

Drive and Control of Electromagnetic Drive Module on Reciprocally Rotating Disc Used for Micro-Gyroscope

An innovative 3-phase AC (Alternative Current) drive circuit for the seismic disc in micro-gyroscopes is designed and verified by computer simulations and experiments. The in-plane dynamic model of the seismic disc with mass eccentricity and air gap against the centre bearing and the mathematic expression of two sinusoidal magnetic fields are developed respectively. In order to prevent the seismic disc from collision with the centre bearing and the EM (Electromagnetic) poles, an anti-collision controller is established by employing two Look-up tables which define the intensity of the applied current to the EM poles. Self-sensing technique is included to measure the real-time offset of the disc by two orthogonal pairs of EM poles, without any additional sensors. The drive circuit under SPWM (Sinusoidal Pulse Width Modulation) operation and the anti-collision strategy are verified by intensive computer simulations via commercial software, OrCAD 9, and experiments.

Numerical Simulation on the Comb Drive Micro-Accelerometer

In this study, we research about comb-drive micro-structure, which is a MEMS device used to measure velocities and accelerations. To ensure the accuracy and visualization of the result, we simulate the dynamics of the comb drive?using COMSOL Multiphysics, meanwhile introducing the concept of re-meshing.?We aim to find the optimal comb-drive-building material, which can provide the device with the most desirable first eigenfrequency. According to the optimization process, silver is the most suitable construction material. Afterwards, the electric responses of both the optimized device and the pre-optimized one are analyzed in frequency domain and stationary study. We conclude that the capacitance change is positively related to frequency in a linear manner, and that the optimized device has a larger increment of both displacement and capacitance per unit of frequency change than the pre-optimized one, showing that the optimization of material realizes our goal of enhancing electrical performance.

论新质生产力研究的经济学思维

“新质生产力”思维概念,基于历史唯物主义发展观的理论范式,将马克思主义的“生产力-生产关系”理论范式,运用于对新时代新现象的观察和研究。在新质生产力的经济学理论范式中,对于“人”的概化具有特别重要的认识论和逻辑自洽性意义。“人”的概化,不仅包含人与自然的关系,也包含人与人的关系,即马克思所说的人的本质是“社会关系的总和”。新质生产力经济学思维所概化的“人”,从“经济人”“组织人”演化产生了“智能机器人”。当新质生产力研究接受数字化人工智能的经济学思维时,主流经济学将发生颠覆性的范式变革。对生产力的“质态”关切,超越对生产力的“量态”关切,是新质生产力重要的经济学属性。经济学的范式变革,须将长期性、未来性、存量性、多元性等因素也纳入观察研究体系,这是域观经济学与新质生产力相契合的逻辑基础,可以引导现代经济学的“微观-宏观”范式体系,更科学地研究新时代、新世界所产生的新现象。

基于激光加工的微安保机构设计与性能

复杂场景下火工品微安保机构需具有可恢复与抗过载特性,为此,研究设计了基于激光加工的金属材质电热驱动微安保机构,采用有限元模拟分析了镍基微电热执行器动作特性,通过调整双热臂U型电热执行器热臂和冷臂的长度、宽度以及各臂之间的间隙,探究它们对输出位移的影响;通过正交实验得到优化的超快激光加工工艺参数分别为频率100 kHz、能量113μJ、切割速度100 mm·s^(-1),实现了镍基电热微安保机构的超快脉冲激光精确制造;最后,搭建了安保机构性能验证平台,验证了该机构在不同电流激励下的驱动位移与隔爆性能。结果表明,在8 A激励电流下,加工的镍基微安保机构驱动位移可达1084μm,所组装的火工品微安保机构在传爆序列中能够有效隔爆。

松辽盆地青山口组页岩有机质的源-汇过程与地质驱动因素

松辽盆地青山口组是盆地内巨量石油资源的最主要源岩。前人普遍认为青山口组有机质富集事件与藻类勃发和咸化缺氧水体环境的形成有关。本文从有机质的源-汇过程角度,综合古生物学、地球化学、岩石矿物学、旋回地层学和地质学等多方面证据,对青山口组页岩有机质的生物母源、矿化过程及地质驱动因素进行了分析,得出如下认识:以蓝细菌和疑源类等微生物为主的多元生物母源、异化铁还原菌和产甲烷菌主导的有机质矿化过程、海侵和火山等多地质因素驱动的古湖泊生态变革和物源供给变化,最终导致初级生产力勃发和水体环境分层,形成厚层富有机质沉积。未来应持续开展青山口组页岩有机质富集机制的精细化和系统化研究,以实现米级厚度富油层的层段识别和分布预测,满足盆地内页岩油勘探开发的需要。