Mechanism of gas pressure action during the initial failure of coal containing gas and its application for an outburst inoculation

Faced with the continuous occurrence of coal and gas outburst(hereinafter referred to as“outburst”)disasters,as a main controlling factor in the evolution process of an outburst,for gas pressure,it is still unclear about the phased characteristics of the coupling process with in situ stress,which induce coal damage and instability.Therefore,in the work based on the mining stress paths induced by typical outburst accidents,the gradual and sudden change of three-dimensional stress is taken as the background for the mechanical reconstruction of the disaster process.Then the true triaxial physical experiments are conducted on the damage and instability of coal containing gas under multiple stress paths.Finally,the response characterization between coal damage and gas pressure has been clarified,revealing the mechanism of action of gas pressure during the initial failure of coals.And the main controlling mechanism during the outburst process is elucidated in the coupling process of in situ stress with gas pressure.The results show that during the process of stress loading and unloading,the original gas pressure enters the processes of strengthening and weakening the action ability successively.And the strengthening effect continues to the period of large-scale destruction of coals.The mechanical process of gas pressure during the initial failure of coals can be divided into three stages:the enhancement of strengthening action ability,the decrease of strengthening action ability,and the weakening action ability.The entire process is implemented by changing the dominant action of in situ stress into the dominant action of gas pressure.The failure strength of coals is not only affected by its original mechanical strength,but also by the stress loading and unloading paths,showing a particularly significant effect.Three stages can be divided during outburst inoculation process.That is,firstly,the coals suffer from initial damage through the dominant action of in situ stress with synergy of gas pressure;secondly,the coals with spallation of structural division are generated through the dominant action of gas pressure with synergy of in situ stress,accompanied by further fragmentation;and finally,the fractured coals suffer from fragmentation and pulverization with the gas pressure action.Accordingly,the final broken coals are ejected out with the gas action,initiating an outburst.The research results can provide a new perspective for deepening the understanding of coal and gas outburst mechanism,laying a theoretical foundation for the innovation of outburst prevention and control technologies.

Polarization characteristics and controllability mechanism of passive scattering elements

Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and rotorcraft.The electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are calculated.The typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and proved.Based on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is summarized.To solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.

Development,sand control mechanism and hydrocarbon accumulation of beach-bar sandstone in a saline lake basin:A case from the Neogene of southwestern Qaidam Basin,NW China

Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.

A bionic controllable strain membrane for cell stretching at air–liquid interface inspired by papercutting

Lung diseases associated with alveoli,such as acute respiratory distress syndrome,have posed a long-term threat to human health.However,an in vitro model capable of simulating different deformations of the alveoli and a suitable material for mimicking basement membrane are currently lacking.Here,we present an innovative biomimetic controllable strain membrane(BCSM)at an air–liquid interface(ALI)to reconstruct alveolar respiration.The BCSM consists of a high-precision three-dimensional printing melt-electrowritten polycaprolactone(PCL)mesh,coated with a hydrogel substrate—to simulate the important functions(such as stiffness,porosity,wettability,and ALI)of alveolar microenvironments,and seeded pulmonary epithelial cells and vascular endothelial cells on either side,respectively.Inspired by papercutting,the BCSM was fabricated in the plane while it operated in three dimensions.A series of the topological structure of the BCSM was designed to control various local-area strain,mimicking alveolar varied deformation.Lopinavir/ritonavir could reduce Lamin A expression under over-stretch condition,which might be effective in preventing ventilator-induced lung injury.The biomimetic lung-unit model with BCSM has broader application prospects in alveoli-related research in the future,such as in drug toxicology and metabolism.

A new classification of seepage control mechanisms in geotechnical engineering

Seepage flow through soils,rocks and geotechnical structures has a great influence on their stabilities and performances,and seepage control is a critical technological issue in engineering practices.The physical mechanisms associated with various engineering measures for seepage control are investigated from a new perspective within the framework of continuum mechanics;and an equation-based classification of seepage control mechanisms is proposed according to their roles in the mathematical models for seepage flow,including control mechanisms by coupled processes,initial states,boundary conditions and hydraulic properties.The effects of each mechanism on seepage control are illustrated with examples in hydroelectric engineering and radioactive waste disposal,and hence the reasonability of classification is demonstrated.Advice on performance assessment and optimization design of the seepage control systems in geotechnical engineering is provided,and the suggested procedure would serve as a useful guidance for cost-effective control of seepage flow in various engineering practices.

Characteristics and control mechanisms of coalbed permeability change in various gas production stages

According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.

Efficacy evaluation and mechanism of Bacillus subtilis EBS03 against cotton Verticillium wilt

Background:In our previous study,a strain EBS03 with good biocontrol potential was screened out of 48 strains of cotton endophyte Bacillus subtilis by evaluating the controlling effect against cotton Verticillium wilt.However,its mechanism for controlling Verticillium wilt remains unclear.The objective of this study was to further clarify its con-trolling effect and mechanism against cotton Verticillium wilt.Results:The results of confrontation culture test and double buckle culture test showed that the inhibitory effects of EBS03 volatile and nonvolatile metabolite on mycelium growth of Verticillium dahliae were 70.03%and 59.00%,respectively;the inhibitory effects of sporulation and microsclerotia germination were 47.16%and 70.06%,respec-tively.In the greenhouse test,the EBS03 fermentation broth root irrigation had the highest controlling effect at 87.11%on cotton Verticillium wilt,and significantly promoted the growth of cotton seedlings.In the field experi-ment,the controlling effect of EBS03 fermentation broth to cotton Verticillium wilt was 42.54%at 60 days after cotton sowing,and the boll number per plant and boll weight in EBS03 fermentation broth seed soaking,root irrigation,and spraying treatments significantly increased by 19.48%and 7.42%,30.90%and 2.62%,15.99%and 9.20%,respec-tively.Furthermore,EBS03 improved the resistance of cotton leaves against the infection of V.dahliae,and induced the outbreak of reactive oxygen species and accumulation of callose.In addition,the results of real time fluorescent quantitative polymerase chain reaction(RT-qPCR)detection showed that EBS03 significantly induced upregulation expression level of defense-related genes PAL,POD,PPO,and PR10 in cotton leaves,enhanced cotton plant resistance to V.dahliae,and inhibited colonization level of this fungal pathogen in cotton.Conclusion:Bacillus subtilis EBS03 has a good biological defense capability,which can inhibit the growth and coloni-zation level of V.dahliae,and activate the resistance of cotton to Verticillium wilt,thus increase cotton yield.

Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.

Tectonic Characteristics and Emplacement Mechanism of Dayishan Granite in Hunan Province, China

Dayishan granite, a significant metallogenic-rock body located in Shaoyang-Chenxian tectonomagmatic belt of Hunan Province, was controlled by 'Dayishan-type' fault pattern. Based on the study of tectonic setting and geological features of the grantie, it is concluded that the tectonic system controlling magmatic emplacement is a shear folded-fauted zone which resulted from NW-trending convergent strike-slip faulting. The close relationship between the temporal-spatial distribution, emplacement mechanism of Dayishan granite and the strike-slip faulting is detailed.

The Mechanism of Structural Control of Ore Formation and Geochemical Characteristics in the Massive Sulfide Deposits of the Wushan Copper Ore Field,Jiangxi

The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.

Perturbation to symmetries and Hojman adiabatic invariant for nonholonomic controllable mechanical systems with non-Chetaev type constraints

This paper studies the perturbation to symmetries and adiabatic invariant for nonholonomic controllable mechanical systems with non-Chetaev type constraints. It gives the exact invariants introduced by the Lie symmetries of the nonholonomic controllable mechanical system with non-Chetaev type constraints without perturbation. Based on the definition of high-order adiabatic invarlants of mechanical system, the perturbation of Lie symmetries for nonholonomic controllable mechanical system with non-Chetaev type constraints with the action of small disturbances is investigated, and a new type of adiabatic invariant of system are obtained. In the end of this paper, an example is given to illustrate the application of the results.

Noether-Form Invariance of Nonholonomic Controllable Mechanical Systems in Phase Space

In this paper,we study the Noether-form invariance of nonholonomic mechanical controllable systems inphase space.Equations of motion of the controllable mechanical systems in phase space are presented.The definitionand the criterion for this system are presented.A new conserved quantity and the Noether conserved quantity deducedfrom the Noether-form invariance are obtained.An example is given to illustrate the application of the results.

Weak Noether symmetry for a nonholonomic controllable mechanical system

This paper discusses the weak Noether symmetry for a nonholonomic controllable mechanical system of Chetaev type, and presents expressions of three kinds of conserved quantities obtained by using weak Noether symmetry. Finally, the application of these new results is illustrated by an example.

Multiphase Flow Simulation of New Vapor Distributor in Dividing Wall Column and Control Mechanism

A new vapor distributor based on the Coanda effect is added to the Dividing Wall column(DWC),and the multiphase flow simulation is performed using ANSYS Fluent by this model.The results show that with the addition of the liquid phase,the new vapor distributor still follows the Coanda effect.Hereby,the vapor is ejected from the slits of the distributor to take away the surrounding vapor,and a negative pressure is formed under the distributor,so as to achieve the purpose of regulating Rv.Analogously to the working principle of vapor distributor,a certain amount of vapor is drawn out from a position of prefractionator,which is equivalent to the vapor ejected by the distributor.The same amount of vapor is fed into the main column,which corresponds to the gas phase at the inlet of the distributor.The Rv is adjusted by changing the speed of the input or output vapor.Simulation results show that adding this control mechanism on the basis of temperature or concentration control structure can better achieve the effect of vapor distribution.

RELATIVISTIC VARIATION PRINCIPLES AND EQUATION OF MOTION FOR VARIABLE MASS CONTROLLABLE MECHANICAL SYSTEM

With classical variable mass and relativistic variable mass cases being considered.the relativistic D' Alembert principles of Lagrange form Nielsen form and Appell. form for variable mass controllable mechanical system are given the relativistic Chaplygin equation. Nielsen equation and Appell equation .for variable mass controllable mechanical system in quasi-coordinates and generalized- coordinates are obtained, and the equations of motion of relativistic controllable mechanical system for holonomic system and constant mass system are diseussed

Construction of the Control Mechanism of Rural Non-point Source Pollution in Nantong City

In view of the problems found in the in-depth interviews of the current situation of rural non-point source pollution control mechanism in Nantong City and their reasons,the following six countermeasures and suggestions are put forward,including giving full play to the role of fighting bastion of the Party branch and building a mechanism for Party building to lead the control of non-point source pollution in rural areas,giving prominence to the dominant role of farmers and establishing farmers’endogenous motivation excitation mechanism for rural non-point source pollution control,improving the interest coordination mechanism among multiple governance subjects and building a modern control system for rural non-point source pollution,combining regulations,administrative,economic,technical and other means of rural non-point source pollution control and strengthening the synergistic integration mechanism of multiple means of control,reconstructing the information disclosure mechanism of rural non-point source pollution control and building a comprehensive trust mechanism of multiple control subjects,and improving the mechanism for coordinating the supply of policy tools and ensure that basic mechanisms play their due role.

Cognition Based Adaptive Control Mechanism

According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.

Theoretical study of mutual control mechanism between magnetization and polarization in multiferroic materials

The mutual control mechanism between magnetization and polarization in multiferroic materials is studied. The system contains a ferromagnetic sublattice and a ferroelectric sublattice. To describe the magneto–electric coupling, we propose a linear coupling Hamiltonian between ferromagnetism and ferroelectricity without microscopic derivation. This coupling enables one to retrieve the hysteresis loops measured experimentally. The thermodynamic properties of the system are calculated, such as the temperature dependences of the magnetization, polarization, internal energy and free energy.The ferromagnetic and ferroelectric hysteresis loops driven by either a magnetic or an electric field are calculated, and the magnetic spin and pseudo-spin are always flipped synchronously under the external magnetic and electric field. Our theoretical results are in agreement with the experiments.

Mechanism of Electromagnetic Flow Control Enhanced by Electro-Discharge in Water

Pulsed discharge utilized to achieve large current density in the electromagnetic flow control is numerically studied. A mathematic discharge model is established to calculate the plasma channel, and an actuator is designed to generate the Lorentz force in the micro plasma channel. During the discharge process, the resistance in the channel decreases rapidly and a large current density appears between the discharge electrodes. After the actuator is applied in the leading edge of a flat plate, the separation region and downstream turbulent boundary layer on the plate disappear. Meanwhile, a skin-friction drag force reduction is achieved.