Mechanics of rib spalling of high coal walls under fully-mechanized mining

In order to solve the problem of rib spalling of high coal walls in fully-mechanized（HCWFM）mines,we used the principle of damage mechanics to analyze coal wall rib spalling.The results show that coal wall rib spalling is,to a certain degree,a macro-performance of the development of micro-cracks.We built a mechanical model to simulate the damage to the front of coal walls,carried out theoretical calculations of the damage parameters,analyzed the effect of mining height,original cracks,seam strength,horizontal stress,vertical displacement of the coal walls and other parameters on coal wall rib spalling, which conform well with the results of our field measurements and numerical simulation.The key to control coal wall rib spalling is to control the development of cracks in coal walls.Accelerating the speed of advancing the working face,improving the setting load of support and the horizontal force of the guard board,strengthening coal walls and other technical measures can effectively reduce the degree of damage to the coal walls and control coal wall rib spalling at HCWFM faces.

The role of agricultural mechanization technology in the promotion of scientific and technological achievements in agriculture

Agricultural mechanization is to the use advanced and applicable agricultural machinery and equipment in agriculture to improve agricultural production conditions, and continuously improve the production technology and economic, ecological processes of agriculture. The level of agricultural science and technology depends largely on the degree of agricultural mechanization promotion. An agricultural country level depends on the degree of modern agricultural mechanization level of the application, and the era of mechanization in agriculture can not only save a lot of labor, reduce labor intensity, but also improve labor efficiency, and enhance resistance to natural disasters. The importance of agricultural mechanization technology in the scientific and technological achievements in agriculture is visible.

Discussion and Research on Orthopedic Biomechanics Testing Technology

With the continuous development of today's science and technology,orthopedic research has also achieved continuous updates in materials and machinery.In this case,the mechanics testing technology of orthopedics also needs to be further updated and developed,so that it can effectively meet the requirement for today's orthopedic mechanical testing.Based on this,this article analyzes several advanced orthopedic mechanics testing techniques.It is hoped that this analysis can provide a reference for the good application and development of orthopedic mechanics testing technology.

Practical Analysis of Mechanical Automation Technology in Automobile Manufacturing

In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic demand,the automobile manufacturing industry has been continuously developing and growing globally.However,to cope with increasingly fierce market competition and ever-changing consumer demands,the automobile manufacturing industry is also facing the challenges of improving production efficiency,reducing costs,and improving product quality.In this context,automation technology has gradually become a major trend in the automobile manufacturing industry.As an important support of modern industry,automation technology has shown great application potential in many fields.From industrial production to daily life,automation technology can be seen everywhere.In the field of manufacturing,especially in automobile manufacturing,the application of automation technology is getting more and more attention.Automated production lines,intelligent robots,and automated warehousing systems have all changed the face of automobile manufacturing to varying degrees,bringing companies higher efficiency,more stable quality,and greater competitive advantages.The application trend of this automation technology in various fields not only meets the needs of modern industry for efficient,precise,and sustainable development but also provides new ideas and paths for the future development of the automobile manufacturing industry.

Effects of Rice Combine Harvester Application to Harvest Chinese Milk Vetch Seeds

During the test, the seed yield, Iabor efficiency, harvesting costs and eco-nomic benefits were compared and analyzed between mechanical harvesting tech-noIogy and traditional artificial harvesting technoIogy of Chinese miIk vetch seeds to studied the mechanical harvesting technoIogy and appIication effects. The resuIts showed that mechanical harvesting technoIogy increased the yield of 92.7 kg/hm2, reducing the seeds Ioss. It improved the Iabor efficiency and reduced the harvesting cost. For exampIe, a rice combine harvester was the equal of 18-20 person in the harvest quantity in one day, which directIy reduced the Iabor cost of 2 175-3 000 yuan/hm2 and increased the economic income of 3 307-4 099 yuan/hm2. So it wiI pIay an important roIe in soIving the shortage of Chinese miIk vetch seeds and ac-ceIerating the deveIopment of Chinese miIk vetch green manure crop in south China rice region.

Spatio-temporal Fragmentation of Leisure Activities in Information Era： Empirical Evidence from Nanjing, China

Activity fragmentation provides a new approach for understanding the transformation of urban space and function in the information era. Numerous theoretical and empirical studies have been conducted on activity fragmentation, but few studies have focused on the fragmentation of leisure activities. This study was intended to extend the extant literature by: 1) analysing the spatio-temporal fragmentation of physical and virtual leisure activities by using a dataset collected in Nanjing, China, and 2) evaluating the reasons of leisure activity fragmentation, as well as the potential spatial effect of activity fragmentation. The results indicated that virtual leisure activities are more fragmented than physical leisure activities, but the fragmentation of physical and virtual leisure activities varies on weekday and weekend, as well as in various locations and urban districts. In addition, the results suggested that sociodemographic factors and information and communication technology(ICT) variables distinctly affect the fragmentation of leisure activities. Meanwhile, the fragmentation of virtual leisure activities may enhance the transformation of traditional urban space by reallocating leisure activity times and locations.

Effects of Processing Technologies on Mechanical Properties of SiC Particulate Reinforced Magnesium Matrix Composites

Mg matrix composites with SiC particles ranging from 5vol%-25vol% were prepared using stirring casting method. Die casting, squeezing casting, and extrusion were applied for inhibiting or eliminating the defects such as gas porosity and shrinkage void. Through die casting and squeezing casting, most of the defects in Mg matrix composites could be eliminated, but the mechanical properties were improved limitedly. On the other hand, after hot extrusion, not only most of the defects of as-cast composites ingots were eliminated, but also the mechanical properties were improved markedly. With the addition of SiC, the tensile strength, yield strength and elastic modulus of as extrusion SiCp/AZ61 composites increased remarkably, and the elongation decreased obviously.

In-situ Fabricated TiB_2 Particle-whisker Synergistically Toughened Ti(C,N)-based Ceramic Cutting Tool Material

The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers.However,the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration;although a new in-situ two-step sintering process can solve the above problems to some extent,yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process.In this paper,an in-situ one-step synthesis technology is proposed,which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace.A kind of Ti（C,N）-based ceramic cutting tool material synergistically toughened by TiB_2 particles and whiskers is fabricated with this new process.The phase compositions,relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The composite which is sintered under a pressure of 32 MPa at a temperature of 1700℃in vacuum holding for 60 min can get the optimal mechanical properties.Its flexural strength,fracture toughness and Vickers hardness are 540 MPa,7.81 MPa·m（1/2）and 20.42 GPa,respectively.The composite has relatively high density,and the in-situ synthesized TiB_2 whiskers have good surface integrity,which is beneficial for the improvement of the fracture toughness.It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers,crack bridging by whiskers/particles and multi-scale particles synergistically toughening.This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.

The study of measuring technology on the dynamic mechanical properties of welded joint with high strainrate

In this paper, to meet the needs of studying work of dynamic mechanical properties of welded joint, the dynamic mechanical properties of welded joint were measured by means of SHPB(Split Hopkinson Pressure Bar).The dynamic mechanical property's curves of every part of welded joint were obtained. For studying the dynamic behavior of mechanical heterogeneity of welded joint, important data were offered. The method of test creates a new way of studying dynamic mechanical properties of welded joint.

Review on Modeling and Optimization for Refractories

This paper introduced characteristics of refractories and step of simulation. During simulation,firstly analyzed mechanism of technology; secondly described the mechanism as quadratic equation; thirdly designed and executed experiment; later made regression equation and optimization; then found technical conflict; finally analyzed and resolved the conflict. Doing repeatedly like this,resolved difficult problems.

Mechanization technology:The key to sugarcane production in China

Sugarcane is an important cash crop in southern China now planted on about 1.5 million ha in the main production areas in Guangxi,Zhuang Autonomous Region and Yunnan,Guangdong,and Hainan Provinces.Since the cost of labor in China is increasing rapidly and the price of local sugar is uncompetitive with the product from mechanized international producers,China needs to change its sugarcane production methods from manual work to mechanization in order to catch up with international trends in this global industry.Although a lot of effort in China have gone into sugarcane mechanization since the 1960s,the overall level of mechanization in sugarcane production is still only approximately 30%,which is about 20%lower than that achieved in the other main field crops.Almost all of the sugarcane grown in China is still harvested by hand.In order to summarize past experience and promote the mechanization of sugarcane production in China,this paper reviews the whole process of developing mechanization since 1960s and describes the current state of sugarcane mechanization in China.The research currently being undertaken and the main obstacles to be overcome in developing a mechanized sugarcane production system,are described.The design and testing of sugarcane harvesting machinery and its key components has been a significant research area by some Chinese universities,research institutes,and manufacturing companies in these past decades.This paper reviews that research and outlines the main achievements which have been made in this area.Mechanized harvesting systems for sugarcane,and the appropriate harvesting patterns suitable for different growing conditions applying in China,have also been studied.The paper concludes with some comments on the future directions for progress in China’s mechanization of sugarcane production and some policy suggestions to facilitate the industry's transition.

Somatosensory Neuron Typing with High-Coverage Single-Cell RNA Sequencing and Functional Analysis

Different physical and chemical stimuli are detected by the peripheral sensory receptors of dorsal root ganglion （DRG） neurons, and the generated inputs are transmitted via afferent fibers into the central nervous system. The gene expression profiles of DRG neurons contribute to the generation, transmission, and regulation of various somatosensory signals. Recently, the single-cell transcriptomes, cell types, and functional annotations of somatosensory neurons have been studied. In this review, we introduce our classification of DRG neurons based on single-cell RNA-sequencing and functional analyses, and discuss the technical approaches. Moreover, studies on the molecular and cellular mechanisms underlying somatic sensations are discussed.

Pyrolysis characteristics of Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae and correlations with the carbonizing process of Chinese herbs

AIM： The aim of the work is to study the pyrolysis characteristics of Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae in an inert atmosphere of argon （Ar）, and to investigate the mechanism of the carbonizing process of the three traditional Chinese herbs. METHODS： The pyrolysis characteristics of the crude materials and their extracts were studied by thermogravimetry-mass spectrometry （TG-MS） in a carrier gas of argon, coupled with Fourier transform infrared spectrometry （FTIR） and scanning electron microscopy （SEM） methods. Correlation of the pyrolysis behaviors with the carbonizing process by stir-frying of traditional Chinese medicines was made. RESULTS： Within the temperature range of 200-300 ℃, which is the testing range for the study of the carbonizing process of Chinese herbs, the temperatures indicated by the maximum weight loss rate peak of the above three extracts were taken as the upper-limit temperatures of the carbonizing process of the herbs, and which were 200, 240 and 247 ℃ for Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae, respectively. The ion monitoring signal peaks detected by the TG-MS method corresponded with reports that the level of chemical components of traditional Chinese medicinal materials would decrease after the carbonizing process. It was confirmed by Fourier transform infrared spectrometry （FTIR） and scanning electron microscopy （SEM） methods that better results of ＂medicinal property preservation＂ could be obtained by heating at 200 ℃ for Radix Rhizoma Rhei, at about 250 ℃ for Cortex Moudan Radicis, and Radix Sanguisorbae, as the relative intensity values of the common peaks were among the middle of their three carbonized samples by programmed heating. CONCLUSION： The upper-limit temperatures of the carbonizing process for Radix Rhizoma Rhei, Cortex Moudan Radicis and Radix Sanguisorbae were 200, 240 and 247 ℃ respectively. It is feasible to research the mechanism and technology of the carbonizing process of traditional Chinese medicinal materials using thermogravimetry, Fourier transform infrared spectrometry, and scanning electron microscopy methods.

Flow behavior and deposition study of pollen-shape carrier particles in an idealized inhalation path model

Pollen-shape （spiked sphere） hydroxyapatite （HA） particles for drug carrier application are studied. The particle shape and size effect on flow characteristics and deposition are assessed. The pollen-shape HA particles are synthesized to have comparable size as typical carrier particles with mean diameter of 30-50 μm and effective density less than 0.3 g/cm^3. The flow behaviors of HA and commonly used lactose （LA） carrier particles are characterized by the Carr＇s compressibility index （CI）. The HA particles have lower CI than the LA particles for the same size range. The flow fields of HA and LA carrier particles are measured in an idealized inhalation path model using particle image velocimetry （PLY） technique. The particle streamlines indicate that a large portion of particles may deposit at the bending section due to inertial impaction and gravitational deposition. The flow field result shows that HA particles give smaller separation regions than the LA particles for the same size range. The pollen-shape HA particles are found to be able to follow the gas flow in the model and minimize undesired deposition. Deposition result confirms the bending section to have the most deposition. Deposition is found to be a function of particle properties. An empirical correlation is derived for the deposition efficiency of the pollen-shape particles as a function of particles Stokes number.