Research advances in enhanced coal seam gas extraction by controllable shock wave fracturing

With the continuous increase of mining in depth,the gas extraction faces the challenges of low permeability,great ground stress,high temperature and large gas pressure in coal seam.The controllable shock wave(CSW),as a new method for enhancing permeability of coal seam to improve gas extraction,features in the advantages of high efficiency,eco-friendly,and low cost.In order to better utilize the CSW into gas extraction in coal mine,the mechanism and feasibility of CSW enhanced extraction need to be studied.In this paper,the basic principles,the experimental tests,the mathematical models,and the on-site tests of CSW fracturing coal seams are reviewed,thereby its future research directions are provided.Based on the different media between electrodes,the CSW can be divided into three categories:hydraulic effect,wire explosion and excitation of energetic materials by detonating wire.During the process of propagation and attenuation of the high-energy shock wave in coal,the shock wave and bubble pulsation work together to produce an enhanced permeability effect on the coal seam.The stronger the strength of the CSW is,the more cracks created in the coal is,and the greater the length,width and area of the cracks being.The repeated shock on the coal seam is conducive to the formation of complex network fracture system as well as the reduction of coal seam strength,but excessive shock frequency will also damage the coal structure,resulting in the limited effect of the enhanced gas extraction.Under the influence of ground stress,the crack propagation in coal seam will be restrained.The difference of horizontal principal stress has a significant impact on the shape,propagation direction and connectivity of the CSW induced cracks.The permeability enhancement effect of CSW is affected by the breakage degree of coal seam.The shock wave is absorbed by the broken coal,which may hinder the propagation of CSW,resulting in a poor effect of permeability enhancement.When arranging two adjacent boreholes for CSW permeability enhancement test,the spacing of boreholes should not be too close,which may lead to negative pressure mutual pulling in the early stage of drainage.At present,the accurate method for effectively predicting the CSW permeability enhanced range should be further investigated.

Role Dynamic Allocation of Human-Robot Cooperation Based on Reinforcement Learning in an Installation of Curtain Wall

A real-time adaptive roles allocation method based on reinforcement learning is proposed to improve humanrobot cooperation performance for a curtain wall installation task.This method breaks the traditional idea that the robot is regarded as the follower or only adjusts the leader and the follower in cooperation.In this paper,a self-learning method is proposed which can dynamically adapt and continuously adjust the initiative weight of the robot according to the change of the task.Firstly,the physical human-robot cooperation model,including the role factor is built.Then,a reinforcement learningmodel that can adjust the role factor in real time is established,and a reward and actionmodel is designed.The role factor can be adjusted continuously according to the comprehensive performance of the human-robot interaction force and the robot’s Jerk during the repeated installation.Finally,the roles adjustment rule established above continuously improves the comprehensive performance.Experiments of the dynamic roles allocation and the effect of the performance weighting coefficient on the result have been verified.The results show that the proposed method can realize the role adaptation and achieve the dual optimization goal of reducing the sum of the cooperator force and the robot’s Jerk.

Promoted catalytic property of Cu/SSZ-13 by introducing a minority of Mn for NO removal from diesel engine exhaust

The Cu-exchanged SSZ-13 with the small-pore chabazite framework is considered as a highly efficient catalyst for selective catalytic reduction of NO with NH_(3)(NH_(3)-SCR).In order to further improve the catalytic property,a series of Mn ion-assisted Cu/SSZ-13 powder catalysts were prepared by co-exchange method and stepwise exchange method.It is found that the NH_(3)-SCR activity,N_(2) selectivity,hydrothermal stability and sulfur resistance of Cu/SSZ-13 are promoted by introducing a minority of Mn(0.15%to 0.23%(mass))through co-exchange method.Characterization results reveal that the Cu,Mn co-exchange enables the higher amounts of Cu^(2+)active sites,the abundant medium strong and strong acid,the optimized ratio of Lewis acid to Brønsted acid etc.,which are required for a good NH_(3)-SCR catalytic property over broad temperature range and under harsh working environment.Moreover,a monolithic catalyst was prepared by impregnating a cordierite ceramic support into the coating slurry containing the optimized CuMn/SSZ-13 powder.The diesel engine bench tests show that Cu,Mn co-exchange gives the monolith catalyst a better catalytic property than commercial catalysts.This work provides an important guidance for the rational design of secondary-ion-assisted zeolites applied in NH_(3)-SCR.

SPERA Hydrogen System^(TM)by LOHC-MCH Method for Massive Hydrogen Storage and Transportation

Expanding the hydrogen energy utilization is essential for decarbonization,and the commercialization of hydrogen energy carrier systems that can“store”and“transport”hydrogen in a large scale is necessary.The organic chemical hydride method incorporates hydrogen atoms into the molecular structure of a LOHC(Liquid Organic Hydrogen Carrier)to store and transport hydrogen in a liquid state under normal temperature and pressure,and is a highly safe method with low business risk.Chiyoda has been developing the technology since 2002,completed a pilot demonstration in 2014 and named it the SPERA Hydrogen^(TM) System,and successfully completed an international supply chain demonstration that transports hydrogen from Brunei to Japan in a large scale in 2020,moving to the commercialization stage.Currently,Chiyoda is conducting feasibility studies with a number of domestic and foreign companies with the aim of commercializing the system as soon as possible.In this paper,outline,features,development status and our efforts in commercialization of SPERA HydrogenTM System are introduced.

老年人性生活质量影响因素的范围综述

目的 老年人通常被认为是无性生活,但性生活对老年人仍然很重要.因此,本研究对老年人性生活的相关研究进行范围综述,以明确老年人性生活质量的影响因素,为提升老年人性生活质量的研究提供依据.方法 按照Arksey和O'Malley提出的范围综述方法框架,在PubMed、Web of Science、CINAHL、PsycINFO、Cochrane Library和Scopus等数据库中检索于2012年1月至2022年4月发表的与老年人性生活质量相关的研究文献,仅纳入经过同行评审的中文或英文文献.由2名研究员独立进行文献的筛选、提取和分析.结果 共检索出7 374篇文章,共纳入13篇文献.老年人性生活质量的影响因素包括生理因素、社会文化因素、健康因素、夫妻关系、相关知识的缺乏.结论 老年人性生活质量的影响因素相互交叉、相互影响.医务人员可以为改善老年人性生活质量提供指导或建议.

Elimination mechanism of coal and gas outburst based on geo‑dynamic system with stress–damage–seepage interactions

Coal and gas outburst is a complex dynamic disaster during coal underground mining.Revealing the disaster mechanism is of great signifcance for accurate prediction and prevention of coal and gas outburst.The geo-dynamic system of coal and gas outburst is proposed.The framework of geo-dynamic system is composed of gassy coal mass,geological dynamic environment and mining disturbance.Equations of stress–damage–seepage interaction for gassy coal mass is constructed to resolve the outburst elimination process by gas extraction with boreholes through layer in foor roadway.The results show the occurrence of outburst is divided into the evolution process of gestation,formation,development and termination of geo-dynamic system.The scale range of outburst occurrence is determined,which provides a spatial basis for the prevention and control of outburst.The formation criterion and instability criterion of coal and gas outburst are established.The formation criterion F1 is defned as the scale of the geo-dynamic system,and the instability criterion F2 is defned as the scale of the outburst geo-body.According to the geo-dynamic system,the elimination mechanism of coal and gas outburst—‘unloading+depressurization’is established,and the gas extraction by boreholes through layer in foor roadway for outburst elimination is given.For the research case,when the gas extraction is 120 days,the gas pressure of the coal seam is reduced to below 0.4 MPa,and the outburst danger is eliminated efectively.

Intelligent BCI Headphone for a Healthier and a Deeper Immersive Gameplay

The developments in the area of brain research by analysing brain activity of individuals have given rise to many useful applications, such as diagnosing mental disorders more efficiently, treatment of cognitive disorders, and developing of brain-computer interfaces for treatment, communication and entertainment purposes. However, the development of such applications is hindered by a shortage of easy-to-use and comfortable sensors, as well as a lack of high-quality brain activity data. In the first part of this paper, a review of the status of BCI applications is presented followed by a proposal of a framework for developing an intelligent BCI headphone that takes leverages of the huge amount of data coming from playing video games to let the players experience a full immersive gaming experience.

Technical Research on Characteristics and Network Planning of Railway 5G-R Network

The railway 5G-R network is ready for the engineering construction.In order to provide technical reserve for the preliminary engineering stage,it is necessary to study the characteristics of 5G-R network and network planning technology in advance.The 5G-R network,different from the operators'5G network,is mainly available for railway staff and covers the railway line.It is upgraded based on the previous generation of railway communication system-GSM-R technology.By comprehensively summarizing and reviewing the characteristics of 5G-R system architecture,network coverage,networking technology,business characteristics,equipment redundancy,network performance,etc.,we study the network planning technology with 5G-R characteristics based on the above characteristics,including frequency,coverage,capacity,parameters,indoor distribution,switching and other key technologies.On this basis,this paper puts forward 5G-R network planning suggestion,which can provide technical support for subsequent project deployment.

Cybersecurity Requirements for Management Information Systems

Cybersecurity is therefore one of the most important elements of security in developed countries. Especially since there is an overall trend towards cybersecurity in all aspects of life, I have found that the idea of cybersecurity is based on protecting critical facilities: The nation’s information infrastructure. Information systems, including e-government management systems, are managed by key state agencies. As with economic, scientific, commercial, and other systems, threats are threats to a nation’s national security. We have therefore found that many countries are preparing institutions capable of integrating cybersecurity into protection, development, and information security. This concept has become the most important concern of developed countries, which have secured all scientific possibilities and systems to achieve it. The electronic information network has become an integral part of today’s daily lives in all places. In addition to personal uses, digital information is used, processed, stored, and shared. As this information increases and spreads, we have found that its protection has become more vital and has an effective impact on national security and technical progress.

Ti/Cu/Nb作中间层脉冲加压瞬间液相连接TiC金属陶瓷与不锈钢（英文）

部分瞬间液相焊接(PTLP)综合了钎焊和固相扩散连接的优点,且对连接母材表面粗糙度比传统固相连接相对较低,因此在陶瓷和金属异种材料连接方向上具有较大的优势。采用Ti–Cu–Nb金属中间层,对TiC金属陶瓷与06Cr19Ni10不锈钢进行PTLP连接试验。通过SEM、EDS、XRD和拉伸试验等方法,研究了活性元素中间层、工艺参数对TiC/Ti CuNb/06Cr19Ni10瞬间液相焊接头性能与界面微观结构的影响规律。结果表明,在连接温度885°C、脉冲压力2~10 MPa的工艺条件下保温5 min时接头剪切强度达到最大值(~106.7 MPa)。微观组织表征发现,在TiC金属陶瓷一侧,Ti–Cu层在高于共晶点的连接温度时发生熔化,与TiC金属陶瓷、核心金属层Nb产生界面反应;而在304SS侧,Nb与304SS进行固相扩散,形成具有固相扩散特征的连接结构,连接后界面形成06Cr19Ni10/σ/Nb/CuTi/CuTi2/α+βTi/Ti C过渡结构。连接接头的裂纹沿着Ti–Cu金属化合物层向TiC陶瓷母材扩展,呈脆性解理断裂特征。

An Efficient and Secure Aggregation Encryption Scheme in Edge Computing

Edge computing is a highly virtualized paradigm that can services the Internet of Things(Io T)devices more efficiently.It is a non-trivial extension of cloud computing,which can not only meet the big data processing requirements of cloud computing,but also collect and analyze distributed data.However,it inherits many security and privacy challenges of cloud computing,such as:authentication and access control.To address these problem,we proposed a new efficient privacy-preserving aggregation scheme for edge computing.Our scheme consists of two steps.First,we divided the data of the end users with the Simulated Annealing Module Partition(SAMP)algorithm.And then,the end sensors and edge nodes performed respectively differential aggregation mechanism with the Differential Aggregation Encryption(DAE)algorithm which can make noise interference and encryption algorithm with trusted authority(TA).Experiment results show that the DAE can preserve user privacy,and has significantly less computation and communication overhead than existing approaches.

Do biometric payment systems work during the COVID-19 pandemic?Insights from the Spanish users’viewpoint

Technological developments are changing how users pay for goods and services.In the context of the COVID-19(coronavirus disease 2019)pandemic,new payment systems have been established to reduce contact between buyer and seller.In addition to the pandemic,the future is payment processing is also uncertain due to the new EU security regulations of the Payment Services Directive(PSD2).Biometric payments one option that would guarantee the security of transactions and reduce the risk of conta-gion.This research analyses the intention to recommend the use of the mobile phone as a tool for collecting payments in a shop using iris reading as a biometric measure of the buyer.The moderating effect of the fear of contagion in the proposed relationships was also analysed.An online survey was carried out,which yielded a sample of 368 respondents.The results indicate that the main antecedents of intention to use,which precedes intention to recommend,are perceived trust,habit,personal innovativeness and comfort of use.Additionally,the moderating effect of COVID-19 was checked among users with a higher perception of risk.The results obtained have interesting implications for purchase management among manufacturers and retailers.

Influence of Rice Residue Management Techniques and Weed Control Treatments on Soil Available Plant Nutrients in Rice-Wheat Cropping System

Rice-wheat is the predominant cropping system of fertile soils of Indian, Pakistan, Bangladesh and Nepal falling in the alluvial Indo-Gangetic Plains (IGP). Management of rice residues produced after the harvest of rice crop and before sowing of the next wheat crop is a big challenge in that area. Mostly farmers burn rice residues assuming it low profile fodder and of little use. Burning of rice residues deprives the fields from many plant nutrients as they are lost during burning along with environmental pollutions and other issues. A field study was conducted for two consecutive years at the experimental area of the Department of Agronomy, Punjab Agricultural University, Ludhiana (India) to assess the impact of different rice residue management techniques and weed control treatments in wheat on soil available plant nutrients in rice-wheat cropping system. The experiment was laid out in split plot design with three replications. In main plots, five rice residue management treatments viz., no rice residue, rice residue 5 t·ha-1 (surface), rice residue 6 t·ha-1 (surface), rice residue 7 t·ha-1 (surface) and rice residue 5 t·ha-1 (incorporation) were settled and in sub plots, four weed control treatments i.e. clodinafop 60 t·ha-1, sulfosulfuron 25 t·ha-1, mesosulfuron + iodosulfuron 12 t·ha-1 and control (unweeded) were arranged. Results of the study revealed that surface application as well as incorporation of rice residues improved the organic carbon and NPK status than no rice residues. Among the residue management practices, incorporation of rice residues 5 t·ha-1 significantly improved the soil organic carbon, available nitrogen, phosphorus and potassium than no rice residue treatment in the 0 - 15 soil layer during both the years. Same trend was observed for 15 - 30 cm soil layer but differences were less wide than 0 - 15 cm soil layer. Among the weed control treatments, organic carbon was not significantly influenced. Herbicide treated plots registered significantly higher available nitrogen, phosphorus and potassium than control (unweeded) treatment in the 0 - 15 cm soil layer during both the years.

MIMO-Terahertz in 6G Nano-Communications:Channel Modeling and Analysis

With the development of wireless mobile communication technology,the demand for wireless communication rate and frequency increases year by year.Existing wireless mobile communication frequency tends to be saturated,which demands for new solutions.Terahertz(THz)communication has great potential for the future mobile communications(Beyond 5G),and is also an important technique for the high data rate transmission in spatial information network.THz communication has great application prospects in military-civilian integration and coordinated development.In China,important breakthroughs have been achieved for the key techniques of THz high data rate communications,which is practically keeping up with the most advanced technological level in the world.Therefore,further intensifying efforts on the development of THz communication have the strategic importance for China in leading the development of future wireless communication techniques and the standardization process of Beyond 5G.This paper analyzes the performance of the MIMO channel in the Terahertz(THz)band and a discrete mathematical method is used to propose a novel channel model.Then,a channel capacity model is proposed by the combination of path loss and molecular absorption in the THz band based on the CSI at the receiver.Simulation results show that the integration of MIMO in the THz band gives better data rate and channel capacity as compared with a single channel.

Analysis on the Problems and Countermeasures of Urban Wetland Park Tourism

Wetland with biological and ecological diversity, which can regulate regional climate, humidity, temperature, etc., has high tourism value. Development and management of wetland park in China started late, so we should establish explicit goals to adjust wetland management and publicity from the aspects of regularity, professionality and availability, to promote the sustainable development of wetland resources.

多线性交换子在变指数Herz空间上的有界性

We consider multilinear commutators of singular integrals de ned by T→bf(x)=∫R^(n)mПi=1(bi(x)-bi(y))K(x,y)f(y)dy,where K is a standard Calderon-Zygmund kernel,m is a positive integer and~b=(b_(1);b_(2);…;b_(m))is a family of m locally integrable functions.Based on the theory of variable exponent and on generalization of the BMO norm,we prove the boundedness of multilinear commutators T_(b) on grand variable Herz spaces.The result is still new even in the special case of m=1.

Analysis of Material Loss Behavior According to Long-Term Experiments on LDIE-FAC Multiple Degradation of Carbon Steel Materials

Recently, damage caused by liquid droplet impingement erosion (LDIE) in addition to flow-accelerated corrosion (FAC) has frequently occurred in the secondary side steam piping of nuclear power plants, and the damage-occurring frequency is expected to increase as their operating years’ increase. In order to scrutinize its causes, therefore, an experimental study was conducted to understand how the behavior of LDIE-FAC multiple degradation changes when the piping of nuclear power plants is operated for a long time. Experimental results show that more magnetite was formed on the surface of the carbon steel specimen than on the low-alloy steel specimen, and that the rate of magnetite formation and extinction reached equilibrium due to the complex action of liquid droplet impingement erosion and flow-accelerated corrosion after a certain period of time. Furthermore, it was confirmed at the beginning of the experiment that A106 Gr.B specimen has more mass loss than A335 P22 specimen. After a certain period of time, however, the mass loss tends to be the opposite. This is presumed to have resulted from the magnetite formed on the surface playing a role in suppressing liquid droplet impingement erosion. In addition, it was confirmed that the amount of erosion linearly increases under the conditions in which the formation and extinction of magnetite reach equilibrium.

Theoretical and exploratory research on sustainability mental model of the public in China:based on a typical survey in Guangdong province

This article aims to investigate the public's sustainability mental model(SMM), which can reveal the sustainability dilemma from the public respective, other than enterprise or government. In this article, SMM is defined as one's cognitive structure, thinking mode, and behavior tendency when someone deals with sustainability issues. After theoretical analysis, the authors developed reliable and valid measures systematically and conducted a typical survey with 581 participants from college students' families in Guangdong province in China. Based on those samples, the author used the exploratory factor analysis and confirmatory factor analysis to construct a measurement model of SMM, which includes three dimensions, i.e. sustainable cognition, sustainable thinking, and sustainable behavior intention. According to SMM survey and clustering analysis, the results indicate that SMM of those participants is inactive. Even though those samples do not represent the whole country comprehensively, but this survey was sampled typically and they came from around China. So, the authors consider the SMM scores can reflect Chinese people to some extent, leading to the assumption that SMM of Chinese people is not active presently.

EXAFS Studies on Local Atomic Structure in the Amorphous Mg_(65)Cu_(25)Gd_(10) Alloy

Local atomic structures of an amorphous Mg65Cu25Gd10 alloy and the structural changes by thermal annealing have been studied by extended X-ray absorption fine structure （EXAFS）. The correlation between structural changes and mechanical properties for the Mg65Cu25Gd10 alloy has also been discussed. Results showed that Cu atoms around Gd in Mg65Cu25Gd10 lost rapidly during annealing , resulting in the segregation of Cu atoms. The coordination number NGd-Mg of Mg65Cu25Gd10 annealed at 373 K first diminished and then augmented with the increase of annealing time. The formation of polyhedral short-range order unit with coordination number of nearly 12 around Gd atoms is in favor of the improvement of mechanical properties. The chemical short-range order, not topological short-range order in the amorphous Mg65Cu25Gd10 alloy had obvious changes during annealing.