Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines

Under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction arches.Based on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main causes.In this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.

Memory effect on the pressure-temperature condition and induction time of gas hydrate nucleation

The focus of this study is to investigate the influence of memory effect and the relation of its existence with the dissociation temperature,using gas hydrate formation and dissociation experiments.This is beneficial because memory effect is considered as an effective approach to promote the thermodynamic and dynamic conditions of gas hydrate nucleation.Seven experimental systems （twenty tests in total） were performed in a 1 L pressure cell.Three types of hydrate morphology,namely massive,whiskery and jelly crystals were present in the experiments.The pressures and temperatures at the time when visual hydrate crystals appeared were measured.Furthermore,the influence of memory effect was quantified in terms of pressure-temperature-time （p-T-t） relations.The results revealed that memory effect could promote the thermodynamic conditions and shorten the induction time when the dissociation temperature was not higher than 25℃.In this study,the nucleation superpressure and induction time decrease gradually with time of tests,when the earlier and the later tests are compared.It is assumed that the residual structure of hydrate dissociation,as the source of the memory effect,provides a site for mass transfer between host and guest molecules.Therefore,a driving force is created between the residual structures and its surrounding bulk phase to promote the hydrate nucleation.However,when the dissociation temperature was higher than 25 ℃,the memory effect vanished.These findings provide references for the application of memory effect in hydrate-based technology.

Residual lifetime prediction model of nonlinear accelerated degradation data with measurement error

For the product degradation process with random effect (RE), measurement error (ME) and nonlinearity in step-stress accelerated degradation test (SSADT), the nonlinear Wiener based degradation model with RE and ME is built. An analytical approximation to the probability density function (PDF) of the product's lifetime is derived in a closed form. The process and data of SSADT are analyzed to obtain the relation model of the observed data under each accelerated stress. The likelihood function for the population-based observed data is constructed. The population-based model parameters and its random coefficient prior values are estimated. According to the newly observed data of the target product in SSADT, an analytical approximation to the PDF of its residual lifetime (RL) is derived in accordance with its individual degradation characteristics. The parameter updating method based on Bayesian inference is applied to obtain the posterior value of random coefficient of the RL model. A numerical example by simulation is analyzed to verify the accuracy and advantage of the proposed model.

Storage reliability assessment model based on competition failure of multi-components in missile

The degradation data of multi-components in missile is derived by periodical testing. How to use these data to assess the storage reliability (SR) of the whole missile is a difficult problem in current research. An SR assessment model based on competition failure of multi-components in missile is proposed. By analyzing the missile life profile and its storage failure feature, the key components in missile are obtained and the characteristics voltage is assumed to be its key performance parameter. When the voltage testing data of key components in missile are available, a state space model (SSM) is applied to obtain the whole missile degradation state, which is defined as the missile degradation degree (DD). A Wiener process with the time-scale model (TSM) is applied to build the degradation failure model with individual variability and nonlinearity. The Weibull distribution and proportional risk model are applied to build an outburst failure model with performance degradation effect. Furthermore, a competition failure model with the correlation between degradation failure and outburst failure is proposed. A numerical example with a set of missiles in storage is analyzed to demonstrate the accuracy and superiority of the proposed model.

Effect of surfactant Tween on induction time of gas hydrate formation

Acceleration of gas hydrate formation is important in preventing coal and gas outbursts and is based on a hydration mechanism. It becomes therefore necessary to investigate the effect of surfactants, acting as accelerants for hydrate formation, on induction time. We experimented with three types of a Tween solution with equal concentrations of 0.001 mol/L (T40, T40/T80 (1:1), T40/T80 (4:1)). By means of visual experimental equipment, developed by us, we measured generalized induction time using a Direct Observation Method. The experimental data were analyzed combined with a mass transfer model and a hydrate crystal nuclei growth model. Our major conclusions are as follows: 1) solubilization of surfactants produces supersaturated gas molecules, which promotes the mass transfer from a bulk phase to hydrates and provides the driving force for the complexation between host molecules (water) and guest molecules in a gas hydrate formation process; 2) when the solution of the surfactant concentration exceeds the critical micelle concentration (CMC), the surfactant in an aqueous solution will transform to micelles. Most of the gas molecules are bound to form clusters with water molecules, which promotes the formation of crystal nuclei of gas hydrates; 3) the surfactant T40 proved to have more notable effects on the promotion of crystal nuclei formation and on shortening the induction time, compared with T40/T80 (1:1) and T40/T80 (4:1).

Research progress on permeability improvement mechanisms and technologies of coalbed deep-hole cumulative blasting

Coalbed gas extraction is an important means of exploiting and utilizing gas resources,as well as a means of preventing coal mine disasters.In view of the low gas extraction rate from coalbeds with high gas content and low permeability,a method of improving permeability through deep-hole cumulative blasting is applied to develop initial directional fractures using a jet flow.Under the action of the blasting stress wave and detonation gas wedge,the fractures extend over a large range within the coal,thereby improving coalbed permeability.This study focuses on the criteria of cumulative blasting-induced coalbed fracturing based on a literature review of the penetration effect of cumulative blasting.On this basis,we summarize the coal fracturing zone,crack extension process,and the key technologies of charging and hole sealing for cumulative blasting.In addition,the latest research progress in the optimization of field test drilling and blasting parameters for cumulative blasting is introduced.Research findings indicate that the permeability improvement mechanism of cumulative blasting could be further enhanced,and the technology and technical equipment are in urgent need of improvement.Finally,development trends in the cumulative blasting permeability improvement technique are identified.

Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible cracks.Afterblasting,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,respectively.The coefficient of air permeability is increased 4 times.After 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting before.The average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

Dynamic Surface Control with Nonlinear Disturbance Observer for Uncertain Flight Dynamic System

A new robust control method of a nonlinear flight dynamic system with aerodynamic coefficients and external disturbance has been proposed.The proposed control system is a combination of the dynamic surface control(DSC)and the nonlinear disturbance observer(NDO).DSC technique provides the ability to overcome the″explosion of complexity″problem in backstepping control.NDO is adopted to observe the uncertainties in nonlinear flight dynamic system.It has been proved that the proposed design method can guarantee uniformly ultimately boundedness of all the signals in the closed-loop system by Lyapunov stability theorem.Finally,simulation results show that the proposed controller provides better performance than the traditional nonlinear controller.

Evidence combination method in time domain based on reliability and importance

In order to achieve the information fusion in the time domain based on the evidence theory, an evidence combination method in the time domain based on reliability and importance is proposed according to the idea of evidence discount. Firstly, the distortion of the time-domain evidence is judged based on single exponential smoothing. The real-time reliability of the evidence at the adjacent time is obtained by the real-time reliability assessment method of the evidence based on the credibility decay model.Then, the relative importance of the evidence at the adjacent time is obtained by comprehensively considering improved conflict degree and uncertainty. Finally, based on the criterion of evidence discount and the Dempster’s rule of combination, the evidence combination is carried out to achieve the sequential combination of time-domain evidence. The numerical simulation and analysis show that this method has fully embodied the dynamic characteristics of time-domain evidence combination, and it has strong processing ability for conflict information and anti-disturbing ability.The proposed method has good applicability to information fusion in the time domain.

An apple (Malus domestica) AP2/ERF transcription factor modulates carotenoid accumulation

Color is an important trait for horticultural crops.Carotenoids are one of the main pigments for coloration and have important implications for photosynthesis in plants and benefits for human health.Here,we identified an APETALA2(AP2)/ETHYLENE RESPONSE FACTOR(ERF)transcription factor named MdAP2-34 in apple(Malus domestica Borkh.).MdAP2-34 expression exhibited a close correlation with carotenoid content in‘Benin Shogun’and‘Yanfu 3’fruit flesh.MdAP2-34 promotes carotenoid accumulation in MdAP2-34-OVX transgenic apple calli and fruits by participating in the carotenoid biosynthesis pathway.The major carotenoid contents of phytoene andβ-carotene were much higher in overexpressing MdAP2-34 transgenic calli and fruit skin,yet the predominant compound of lutein showed no obvious difference,indicating that MdAP2-34 regulates phytoene andβ-carotene accumulation but not lutein.MdPSY2-1(phytoene synthase 2)is a major gene in the carotenoid biosynthesis pathway in apple fruit,and the MdPSY2-1 gene is directly bound and transcriptionally activated by MdAP2-34.In addition,overexpressing MdPSY2-1 in apple calli mainly increases phytoene and total carotenoid contents.Our findings will advance and extend our understanding of the complex molecular mechanisms of carotenoid biosynthesis in apple,and this research is valuable for accelerating the apple breeding process.

Aviation multi-station collaborative detecting based on time-frequency correlation of data-link

As an important application research topic of the intelligent aviation multi-station, collaborative detecting must overcome the problem of scouting measurement with status of 'fragmentation', and the NP-hardness problem of matching association between target and measurement in the process of scouting to data-link, which has complicated technical architecture of network construction. In this paper, taking advantage of cooperation mechanism on signal level in the aviation multi-station sympathetic network, a method of obtaining target time difference of arrival (TDOA) measurement using multi-station collaborative detecting based on time-frequency association is proposed. The method can not only achieve matching between target and its measurement, but also obtain TDOA measurement by further evolutionary transaction through refreshing sequential pulse time of arrival (TOA) measurement matrix for matching and correlating. Simulation results show that the accuracy of TDOA measurement has significant superiority over TOA, and detection probability of false TDOA measurement introduced by noise and fake measurement can be reduced effectively.

The experimental study of the coal gangue as gel filling materials

The odd axes resist pressure intensity with large quantity coal gangue was dis- cussed and experimented on fly ash and coal gangue gel filling body between different concentration,proportion and additive dosage.The results show that forepart intensity of new gangue filling body is very low,and anaphase intensity have some increase which still go up after sixty days.The intensity of tao gangue can reach 1.0 MPa in seven days,and anaphase intensity can reach about 2.0 MPa.In the same term,the odd axes resist pres- sure intensity of gel filling body with tao gangue is higher than new gangue No.1 and No.2. To mix into proper additive dosage which occupied the quality point of cement and fly ash not more than 1.5% can improve the fluidity of slurry body and intensity of filling body.

Dynamic Surface Backstepping Global Sliding Mode Control for CPS Based on NDO

Based on dynamic surface control and the nonlinear disturbance observer technique,it proposes a nonlinear adaptive backstepping global sliding mode control system for a typical cyber physical system( CPS)with aerodynamic coefficients and external disturbance uncertainties. The dynamic surface control technique can provide the capability which can solve the problem of "explosion of complexity"in backstepping sliding mode controllers. The nonlinear disturbance observers are employed to observe the arbitrary model uncertainties of nonlinear flight dynamic system. The global sliding mode control method is used to improve the response rate and the precision of the tracking. The simulation results show the effectiveness of the proposed control system.

The Changhsingian Foraminiferal Fauna of the Meishan D Section, Zhejiang, China, and their Ecostratigraphic Implications

Samples were collected continuously and systematically from Beds 2 to 30 of the Meishan D section, and nearly 4,000 foraminiferal specimens were recognized. In total, 72 species （partially including undetermined species and conformis species） in 34 genera of foraminifers were identified. Twelve foraminiferal community zones were established from Beds 2 to 27 based on the abundance, dominance, diversity, and equitability of the foraminiferal fauna and a functional morphological analysis of the dominant and characteristic species. The habitat type indicated by each community zone and the sedimentary features were used to determine the paleo-water depths and the relative changes in sea level. We generated curves of both the habitat type and the hydrodynamic conditions, which together indicate the relative changes in the paleo-water depth and the substrate features in the studied area during the Changhsingian. This study discusses the possible relationship between the foraminiferal community zones and the sea-level changes based on a statistical analysis of the foraminiferal community zones.

Reaction mechanism between“memory effect”and induction time of gas hydrate formation

Using visual experimental apparatus,one system (T40,1×10^(-3) mol/L,non- added with coal) and another system (T40,2×10^(-3) mol/L,added with coal) were experi- mented with for three times and two times,respectively.Five groups of P-T experimental parameters were obtained using the data logger system and analyzed combined with the video information of the experiments.Major conclustions show that the induction time is shortened by 10-20 times in the experimental system containing residual pentahedral ring structures;'memory effect' can accelerate the dynamic progress and improve the ther- modynamic conditions of gas hydrate formation.

Experimental Study on In-situ Leaching and Electrokinetic Remediation of Composite Heavy Metal-contaminated Soil

[Objectives] This study was conducted to investigate in-situ leaching and electrokinetic combined remediation of composite heavy metal-contaminated soil.[Methods] Leaching and electrokientic combined remediation was applied to remediate artificially-simulated composite Cd,Cu,Pb,and Zn-contaminated soil.The electrokinentic remediation of the soil was carried out using EDTA and acetic acid as the eluents with electrodes placed on the top and bottom of the soil,to investigate the effects of different types and concentrations of eluents,reaction time and energization methods on the remediation.[Results]Applying electrodynamic force to the leaching remediation process achieved good removal effects of Cd,Cu,Pb,and Zn in the soil.Compared with pure leaching,the leaching and electrokinetic combined remediation saved 23.8% of EDTA consumption.EDTA showed the ability to complex heavy metals better than acetic acid,and after 10 d of reaction,the 0.1 mol/L EDTA achieved very good removal effects on Cd,Cu,Pb,and Zn from the upper and middle layers of the soil column,exhibiting removal rates of 94.4%,93.3%,91.4% and 92.8% in the upper layer and 87.2%,88.2%,83.3% and 84.6%,respectively.Compared with the conventional experiments,the intermittent energization method and the voltage-increasing method improved the removal rates of Cd,Cu,Pb and Zn by 6.3%,6.1%,5.9%and 6%,and 0.6%,0.9%,0.5% and 0.4%,respectively,and saved 46.8% and 10.3% of energy consumption,respectively.[Conclusions]The study provides reference for the remediation of composite heavy metal-contaminated soil.

Versatile physiological functions of the Nudix hydrolase family in berry development and stress response in grapevine

Nudix hydrolases are widely distributed across all classes of organisms and provide the potential capacity to hydrolyze a wide range of organic pyrophosphates. Although Nudix hydrolases are involved in plant detoxification processes in response to abiotic and biotic stresses, the biological functions of Nudix hydrolases remain largely unclear in grapevine.In the present study, a total of 25 putative grapevine Nudix hydrolases(VvNUDXs) were identified by bioinformatics analysis and classified into eight subfamilies based to their preferred substrates. Both tandem and segmental duplications were responsible for the evolution and expansion of the NUDX gene family in grapevine. To investigate the regulatory roles of VvNUDX genes during growth and development, as well as in response to abiotic and biotic stresses in grapevine, the expression patterns were revealed in publicly available microarray data. The spatial and temporal expression patterns of the VvNUDX genes indicated that they might play important roles in multiple developmental processes. Transcriptome and qRT-PCR analyses showed that ten VvNUDX genes were specifically expressed in grapevine berries, suggesting potential roles in grapevine berry development. Expression and phylogenetic analyses demonstrated that VvNUDX1 and VvNUDX3 might be involved in terpenoid biosynthesis in grapevine. Furthermore,most VvNUDX genes active toward the ADP-ribose/NADH showed different patterns in response to various abiotic and biotic stresses, such as salinity and drought, as well as different types of biotic treatments, such as Erysiphe necator,Bois Noir phytoplasma and leaf-roll-associated virus-3(GLRaV-3). These results indicated that VvNUDX genes were associated with plant detoxification processes in response to abiotic and biotic stresses, and regulate the disease immunity and resistance pathways. The information obtained here may provide good opportunities to explore the physiological functions of VvNUDX genes in berry development and stress response networks in grapevine.

Interaction between geological body and structural body in a three-body model

A three-body model composed of two geological bodies and a structural body was developed to explore how ground-support systems respond to axial loads in underground spaces. A detailed method was designed to fabricate physical scale-model specimens for testing. Three types of specimens were constructed to investigate how three different materials reacted to each other under load. The three types of specimens were called the weak-rock model, hard-rock model and mixed model. The results of uniaxial compression tests show that the mechanical behaviour of a three-body structural support is closely related to the interaction between the three bodies, but owing to different mechanisms, the three types of material behave very differently. To explain the test results, numerical simulations were conducted to explore fully the load responses of the three-body model specimens. The numerical simulations verify the hypotheses proposed for how the three types of material interact.