The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechani...The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechanisms responsible for initiating spontaneous ATP release have not been determined.Our previous study revealed that telomerase reverse transcriptase(TERT)is expressed in the basilar membrane during the first postnatal week.Its role in cochlear development remains unclear.In this study,we investigated the expression and role of TERT in postnatal cochlea supporting cells.Our results revealed that in postnatal cochlear Kölliker’s organ supporting cells,TERT shifts from the nucleus into the cytoplasm over time.We found that the TERT translocation tendency in postnatal cochlear supporting cells in vitro coincided with that observed in vivo.Further analysis showed that TERT in the cytoplasm was mainly located in mitochondria in the absence of oxidative stress or apoptosis,suggesting that TERT in mitochondria plays roles other than antioxidant or anti-apoptotic functions.We observed increased ATP synthesis,release and activation of purine signaling systems in supporting cells during the first 10 postnatal days.The phenomenon that TERT translocation coincided with changes in ATP synthesis,release and activation of the purine signaling system in postnatal cochlear supporting cells suggested that TERT may be involved in regulating ATP release and activation of the purine signaling system.Our study provides a new research direction for exploring the spontaneous electrical activity of the cochlea during the early postnatal period.展开更多
Lightweight thin-walled structures with lattice infill are widely desired in satellite for their high stiffness-to-weight ratio and superior buckling strength resulting fromthe sandwich effect.Such structures can be f...Lightweight thin-walled structures with lattice infill are widely desired in satellite for their high stiffness-to-weight ratio and superior buckling strength resulting fromthe sandwich effect.Such structures can be fabricated bymetallic additive manufacturing technique,such as selective laser melting(SLM).However,the maximum dimensions of actual structures are usually in a sub-meter scale,which results in restrictions on their appliance in aerospace and other fields.In this work,a meter-scale thin-walled structure with lattice infill is designed for the fuel tank supporting component of the satellite by integrating a self-supporting lattice into the thickness optimization of the thin-wall.The designed structure is fabricated by SLM of AlSi10Mg and cold metal transfer welding technique.Quasi-static mechanical tests and vibration tests are both conducted to verify the mechanical strength of the designed large-scale lattice thin-walled structure.The experimental results indicate that themeter-scale thin-walled structure with lattice infill could meet the dimension and lightweight requirements of most spacecrafts.展开更多
Aiming to mitigate the aerodynamic lift force imbalance between pantograph strips,which exacerbates wear and affects the current collection performance of the pantograph-catenary system,a study has been conducted to s...Aiming to mitigate the aerodynamic lift force imbalance between pantograph strips,which exacerbates wear and affects the current collection performance of the pantograph-catenary system,a study has been conducted to support the beam deflector optimization using a combination of experimental measurements and computational fluid dynamics(CFD)simulations.The results demonstrate that the size,position,and installation orientation of the wind deflectors significantly influence the amount of force compensation.They also indicate that the front strip deflectors should be installed downwards and the rear strip deflectors upwards,thereby forming a“π”shape.Moreover,the lift force compensation provided by the wind deflectors increases with the size of the deflector.Alternative wind compensation strategies,such as control circuits,are also discussed,putting emphasis on the pros and cons of various pantograph types and wind compensation approaches.展开更多
This paper discusses the important role of science and technology commissioners in the high-quality development of hundreds of counties,thousands of towns,and myriads of villages in the context of rural revitalization...This paper discusses the important role of science and technology commissioners in the high-quality development of hundreds of counties,thousands of towns,and myriads of villages in the context of rural revitalization,including building bridges,accelerating the transformation of achievements,promoting the value-added of the whole agricultural industry chain,and promoting the rapid development of rural industrial economy.It also discusses the working achievements of science and technology commissioners,in order to promote further development of rural revitalization in Guangdong Province.展开更多
A multi-purpose prototype test system is developed to study the mechanical behavior of tunnel sup-porting structure,including a modular counterforce device,a powerful loading equipment,an advanced intelligent manageme...A multi-purpose prototype test system is developed to study the mechanical behavior of tunnel sup-porting structure,including a modular counterforce device,a powerful loading equipment,an advanced intelligent management system and an efficient noncontact deformation measurement system.The functions of the prototype test system are adjustable size and shape of the modular counterforce structure,sufficient load reserve and accurate loading,multi-connection linkage intelligent management,and high-precision and continuously positioned noncontact deformation measurement.The modular counterforce structure is currently the largest in the world,with an outer diameter of 20.5 m,an inner diameter of 16.5 m and a height of 6 m.The case application proves that the prototype test system can reproduce the mechanical behavior of the tunnel lining during load-bearing,deformation and failure processes in detail.展开更多
For the hybrid multi-infeed HVDC system in which the receiving-end grid is a strong AC grid including LCC-HVDC subsystems and multiple VSC-HVDC subsystems,it has higher voltage support capability.However,for weak AC g...For the hybrid multi-infeed HVDC system in which the receiving-end grid is a strong AC grid including LCC-HVDC subsystems and multiple VSC-HVDC subsystems,it has higher voltage support capability.However,for weak AC grid,the voltage support capability of the multi-VSC-HVDC subsystems to the LCC-HVDC subsystem(voltage support capability-mVSCs-LCC)can resist the risk of commutation failure.Based on this consideration,this paper proposes an evaluation index called Dynamic Voltage Support Strength Factor(DVSF)for the hybrid multi-infeed system,and uses this index to qualitatively judge the voltage support capability-mVSCs-LCC in weak AC grid.In addition,the proposed evaluation index can also indirectly judge the ability of the LCC-HVDC subsystem to suppress commutation failure.Firstly,the mathematical model of the power flow of the LCC and VSC networks in the steady-state is analyzed,and the concept of DVSF applied to hybrid multi-infeed system is proposed.Furthermore,the DVSF index is also used to qualitatively judge the voltage support capability-mVSCs-LCC.Secondly,the influence of multiple VSC-HVDC subsystems with different operation strategies on the DVSF is analyzed with reference to the concept of DVSF.Finally,the indicators proposed in this paper are compared with other evaluation indicators through MATLAB simulation software to verify its effectiveness.More importantly,the effects of multi-VSC-HVDC subsystems using different coordinated control strategies on the voltage support capability of the receiving-end LCC-HVDC subsystem are also verified.展开更多
Tunnels deeply buried have high crustal stress and are prone to large deformation disasters when encountering soft rock.The large deformation phenomenon during the construction process of the Maoxian Tunnel on the Che...Tunnels deeply buried have high crustal stress and are prone to large deformation disasters when encountering soft rock.The large deformation phenomenon during the construction process of the Maoxian Tunnel on the Chengdu-Lanzhou Railway is particularly evident.This article focuses on the large deformation problem of the No.1 inclined shaft of the Maoxian Tunnel,and uses on-site monitoring methods to explore the reasons for tunnel structure failure,and analyzes the mechanical behavior of the tunnel structure.By using numerical simulation methods,the effectiveness of the second-layer support in resisting creep loads in tunnels was studied,and the influence of the construction time of the secondlayer support on the mechanical properties of the tunnel was discussed.The results indicate that the first-layer support in the tunnel is a structural failure caused by asymmetric deformation caused by creep,while the second-layer support has a good effect on resisting creep loads.The research results can provide a technical reference for deformation control of squeezing tunnels.展开更多
The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production...The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production performance and safety. Based on analysis of supporting objects for roadway repairing, this paper proposes the supporting parameters and condruction technics. The industrial ted of 70m long roadway repairing shows that the proposed parameters and technics of bolt shotcrete and mesh support for roadway repairing are reasouable, bring good technical and economic results for the colliery, and the repairing is successful.展开更多
In deep underground engineering,rock burst and other dynamic disasters are prone to occur due to stress concentration and energy accumulation in surrounding rock.The control of dynamic disasters requires bolts and cab...In deep underground engineering,rock burst and other dynamic disasters are prone to occur due to stress concentration and energy accumulation in surrounding rock.The control of dynamic disasters requires bolts and cables with high strength,high elongation,and high energy-absorbing capacity.Therefore,a constant resistance energy-absorbing(CREA)material is developed.In this study,the dynamic characteristics of the new material are obtained via the drop hammer tests and the Split Hopkinson Pressure Bar(SHPB)tests of the new material and two common bolt(CB)materials widely used in the field.The test results of drop hammer test and SHPB test show that the percentage elongation of CREA material is more than 2.64 and 3.22 times those of the CB material,and the total impact energy acting on CREA material is more than 18.50 and 21.84 times,respectively,indicating that the new material has high elongation and high energy-absorbing capacity.Subsequently,the CREA bolts and cables using the new material are developed,which are applied in roadways with high stress and strong dynamic disturbance.The field monitoring results show that CREA bolts and cables can effectively control the surrounding rock deformation and ensure engineering safety.展开更多
In order to solve the large deformation controlling problem for surrounding rock of gob-side entry driving under common cable anchor support in deep mine, site survey, physical modeling experiment, numerical simulatio...In order to solve the large deformation controlling problem for surrounding rock of gob-side entry driving under common cable anchor support in deep mine, site survey, physical modeling experiment, numerical simulation and field measurement were synthetically used to analyze the deformation and failure characteristics of surrounding rock. Besides, applicability analysis, prestress field distribution characteristics of surrounding rock and the control effect on large deformation of surrounding rock were also further studied for the gob-side entry driving in deep mine using the cable-truss supporting system. The results show that, first, compared with no support and traditional bolt anchor support, roof cable-truss system can effectively restrain the initiation and propagation of tensile cracks in the roof surrounding rock and arc shear cracks in the two sides, moreover, the broken development of surrounding rock, roof separation and extrusion deformation between the two sides of the roadway are all controlled; second, a prestressed belt of trapezoidal shape is generated in the surrounding rock by the cable-truss supporting system, and the prestress field range is wide. Especially, the prestress concentration belt in the shallow surrounding rock can greatly improve the anchoring strength and deformation resisting capability of the rock stratum;third, an optimized support system of ‘‘roof and side anchor net beam, roof cable-truss supporting system and anchor cable of the narrow coal pillar" was put forward, and the support optimization design and field industrial test were conducted for the gob-side entry driving of the working face 5302 in Tangkou Mine, from which a good supporting effect was obtained.展开更多
This paper presents a computer system reliability allocation method that is based on the theory of statistic and Markovian chain,which can be used to allocate reliability to subsystem, to hybrid system and software mo...This paper presents a computer system reliability allocation method that is based on the theory of statistic and Markovian chain,which can be used to allocate reliability to subsystem, to hybrid system and software modules. A relevant supporting tool built by us is introduced.展开更多
The random noises of multi-sensor and the environment make observations uncertain and correlative, so the performance of fusion algorithms is reduced by using observations directly. To solve this problem, a multi-laye...The random noises of multi-sensor and the environment make observations uncertain and correlative, so the performance of fusion algorithms is reduced by using observations directly. To solve this problem, a multi-layer track fusion algorithm based on supporting degree matrix is proposed. Combined with the track fusion algorithm based on filtering step by step, it uses multi-sensor observations to establish supporting degree matrix and realize multi-layer fusion. Simulation results show its estimation precision is higher than the original algorithm and is increased by 20% around. Therefore, it solves the problem of target tracking further in the distributed track fusion system.展开更多
Because of hydraulic-electromagnetic double supporting forms,the supporting capacity and stiffness of magnetic-liquid double suspension bearing(MLDSB)can be improved sharply and then it is more suitable for medium spe...Because of hydraulic-electromagnetic double supporting forms,the supporting capacity and stiffness of magnetic-liquid double suspension bearing(MLDSB)can be improved sharply and then it is more suitable for medium speed,heavy load and frequent-starting occasions.Due to the multiple uncertainty,such as the coupling,the unmodeled dynamics,the parameter perturbation and the external disturbance perturbation,the robust stability and stiffness of control system of MLDSB are hard to meet the design requirements.Firstly,the structural features and the regulation mechanisms of MLDSB are presented and the radial 4-DOF kinetic equations are established.Secondly,the influence factors of the control system's coupling on unbalanced vibration caused by the deviation of the rotor center of mass are revealed,and then the weighting function of suppressing the unbalanced vibration can be obtained.Finally,H∞ controller of MLDSB is designed with H∞ mixed-sensitivity method,and the control performances of H∞ controller is compared with the state feedback controller.The simulation results show that single degree of freedom(DOF)supporting system of MLDSB with H∞ controller has good robust stability,stiffness and the ability to suppress unbalanced external disturbances.This study can provide the theoretical reference for stabilized suspension and control of MLDSB.展开更多
In this paper, probabilistic models for three redundant configurations have been developed to analyze and compare some reliability characteristics. Each system is connected to a repairable supporting external device f...In this paper, probabilistic models for three redundant configurations have been developed to analyze and compare some reliability characteristics. Each system is connected to a repairable supporting external device for operation. Repairable service station is provided for immediate repair of failed unit. Explicit expressions for mean time to system failure and steady-state availability for the three configurations are developed. Furthermore, we compare the three configurations based on their reliability characteristics and found that configuration II is more reliable and efficient than the remaining configurations.展开更多
This proposal focuses on the prevalence of teenage pregnancy issue in NJ and illustrates the benefits of school-based health clinics and educational programs which should be implemented for teenage pregnancy and child...This proposal focuses on the prevalence of teenage pregnancy issue in NJ and illustrates the benefits of school-based health clinics and educational programs which should be implemented for teenage pregnancy and childbearing.Without the early intervention of educational programs and preventive medical services which should be implemented in school areas,teen pregnancy and childbearing can have physical and emotional health influences on teen mothers,their babies and other family members,and the worst consequence should be abortion.What’s more,teenage pregnancy and childbearing have substantial economic consequence for state.The annual estimated cost associated with teen childbearing (teens 19 and younger) in NJ to taxpayers is at least $167 million in 2004 (24% federal costs and 76% state and local costs).Studies demonstrated that a much larger amount of money is spent on the consequences of teenage pregnancy than on prevention.NJ has an opportunity to invest in prevention and reduce not only the monetary but also the societal costs to our youth burdened by the often overwhelming responsibilities of teenage pregnancy and parenting.According to the 15 years follow-up research and data analyzing,two models of success which specifically implemented in South Carolina high schools and Chicago public schools have been proved to effectively reduce incidence of repeat pregnancy and emergency room visits,reduce incidence of teen mothers smoking during pregnancy,improve emotional outcomes among teen mothers,decrease incidence of teen mothers drug impairment,arrest,conviction,or jail time and reduce use of food stamps and other public assistances,which can consequently increase the state public health costs.In order to support teen mothers’ academic,physical,emotional and social needs in a stable and consistent school environment,the plan which titled "Physical and Mental Health Promotion for NJ Teen Mothers" is effective and practical enough to arouse the attention of some relevant departments.It’s worth patron to fund the plan because supporting teenage pregnancy at early stage can subsequently benefit the national and state economy and teen mothers.展开更多
Based on analysis of the supporting object of bulking soft rock and comparing the supporting difficulty of the repairing projects with that of the newly excavated projects, this paper proposes a method to determine re...Based on analysis of the supporting object of bulking soft rock and comparing the supporting difficulty of the repairing projects with that of the newly excavated projects, this paper proposes a method to determine reasonable supporting parameters for soft rock project repairing. This method has been verified to be reasonable and economical in an industrial test.展开更多
The instability of trapezoidal Ⅰ-steel support is analysed for the compound roof of main coal seam in Shaqu Colliery, and the mechanism of bolt supporting is studied. A scheme of bolt supporting has been given and pu...The instability of trapezoidal Ⅰ-steel support is analysed for the compound roof of main coal seam in Shaqu Colliery, and the mechanism of bolt supporting is studied. A scheme of bolt supporting has been given and put into practice, remarkable technical and economic benefits have been got.展开更多
Permanent damage to hair cells(HCs)is the leading cause of sensory deafness.Supporting cells(SCs)are essential in the restoration of hearing in mammals because they can proliferate and differentiate to HCs.MDS1 and EV...Permanent damage to hair cells(HCs)is the leading cause of sensory deafness.Supporting cells(SCs)are essential in the restoration of hearing in mammals because they can proliferate and differentiate to HCs.MDS1 and EVI1 complex locus(MECOM)is vital in early development and cell differentiation and regulates the TGF-βsignaling pathway to adapt to pathophysiological events,such as hematopoietic proliferation,differentiation and cells death.In addition,MECOM plays an essential role in neurogenesis and craniofacial development.However,the role of MECOM in the development of cochlea and its way to regulate related signaling are not fully understood.To address this problem,this study examined the expression of MECOM during the development of cochlea and observed a significant increase of MECOM at the key point of auditory epithelial morphogenesis,indicating that MECOM may have a vital function in the formation of cochlea and regeneration of HCs.Meanwhile,we tried to explore the possible effect and potential mechanism of MECOM in SC proliferation and HC regeneration.Findings from this study indicate that overexpression of MECOM markedly increases the proliferation of SCs in the inner ear,and the expression of Smad3 and Cdkn2b related to TGF signaling is significantly down-regulated,corresponding to the overexpression of MECOM.Collectively,these data may provide an explanation of the vital function of MECOM in SC proliferation and trans-differentiation into HCs,as well as its regulation.The interaction between MECOM,Wnt,Notch and the TGF-βsignaling may provide a feasible approach to induce the regeneration of HCs.展开更多
基金supported by the National Natural Science Foundation of China,Nos.81870732(to DZ),82171161(to DZ),81900933(to YS),and 82000978(to ZL).
文摘The spontaneous bursts of electrical activity in the developing auditory system are derived from the periodic release of adenosine triphosphate(ATP)by supporting cells in the Kölliker’s organ.However,the mechanisms responsible for initiating spontaneous ATP release have not been determined.Our previous study revealed that telomerase reverse transcriptase(TERT)is expressed in the basilar membrane during the first postnatal week.Its role in cochlear development remains unclear.In this study,we investigated the expression and role of TERT in postnatal cochlea supporting cells.Our results revealed that in postnatal cochlear Kölliker’s organ supporting cells,TERT shifts from the nucleus into the cytoplasm over time.We found that the TERT translocation tendency in postnatal cochlear supporting cells in vitro coincided with that observed in vivo.Further analysis showed that TERT in the cytoplasm was mainly located in mitochondria in the absence of oxidative stress or apoptosis,suggesting that TERT in mitochondria plays roles other than antioxidant or anti-apoptotic functions.We observed increased ATP synthesis,release and activation of purine signaling systems in supporting cells during the first 10 postnatal days.The phenomenon that TERT translocation coincided with changes in ATP synthesis,release and activation of the purine signaling system in postnatal cochlear supporting cells suggested that TERT may be involved in regulating ATP release and activation of the purine signaling system.Our study provides a new research direction for exploring the spontaneous electrical activity of the cochlea during the early postnatal period.
基金The authors are grateful for the support by National Key Research and Development Program of China(2021YFF0500300,2020YFB1708300)the National Natural Science Foundation of China(52205280,12172041).
文摘Lightweight thin-walled structures with lattice infill are widely desired in satellite for their high stiffness-to-weight ratio and superior buckling strength resulting fromthe sandwich effect.Such structures can be fabricated bymetallic additive manufacturing technique,such as selective laser melting(SLM).However,the maximum dimensions of actual structures are usually in a sub-meter scale,which results in restrictions on their appliance in aerospace and other fields.In this work,a meter-scale thin-walled structure with lattice infill is designed for the fuel tank supporting component of the satellite by integrating a self-supporting lattice into the thickness optimization of the thin-wall.The designed structure is fabricated by SLM of AlSi10Mg and cold metal transfer welding technique.Quasi-static mechanical tests and vibration tests are both conducted to verify the mechanical strength of the designed large-scale lattice thin-walled structure.The experimental results indicate that themeter-scale thin-walled structure with lattice infill could meet the dimension and lightweight requirements of most spacecrafts.
文摘Aiming to mitigate the aerodynamic lift force imbalance between pantograph strips,which exacerbates wear and affects the current collection performance of the pantograph-catenary system,a study has been conducted to support the beam deflector optimization using a combination of experimental measurements and computational fluid dynamics(CFD)simulations.The results demonstrate that the size,position,and installation orientation of the wind deflectors significantly influence the amount of force compensation.They also indicate that the front strip deflectors should be installed downwards and the rear strip deflectors upwards,thereby forming a“π”shape.Moreover,the lift force compensation provided by the wind deflectors increases with the size of the deflector.Alternative wind compensation strategies,such as control circuits,are also discussed,putting emphasis on the pros and cons of various pantograph types and wind compensation approaches.
文摘This paper discusses the important role of science and technology commissioners in the high-quality development of hundreds of counties,thousands of towns,and myriads of villages in the context of rural revitalization,including building bridges,accelerating the transformation of achievements,promoting the value-added of the whole agricultural industry chain,and promoting the rapid development of rural industrial economy.It also discusses the working achievements of science and technology commissioners,in order to promote further development of rural revitalization in Guangdong Province.
文摘A multi-purpose prototype test system is developed to study the mechanical behavior of tunnel sup-porting structure,including a modular counterforce device,a powerful loading equipment,an advanced intelligent management system and an efficient noncontact deformation measurement system.The functions of the prototype test system are adjustable size and shape of the modular counterforce structure,sufficient load reserve and accurate loading,multi-connection linkage intelligent management,and high-precision and continuously positioned noncontact deformation measurement.The modular counterforce structure is currently the largest in the world,with an outer diameter of 20.5 m,an inner diameter of 16.5 m and a height of 6 m.The case application proves that the prototype test system can reproduce the mechanical behavior of the tunnel lining during load-bearing,deformation and failure processes in detail.
基金supported by the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid(No.U2066210).
文摘For the hybrid multi-infeed HVDC system in which the receiving-end grid is a strong AC grid including LCC-HVDC subsystems and multiple VSC-HVDC subsystems,it has higher voltage support capability.However,for weak AC grid,the voltage support capability of the multi-VSC-HVDC subsystems to the LCC-HVDC subsystem(voltage support capability-mVSCs-LCC)can resist the risk of commutation failure.Based on this consideration,this paper proposes an evaluation index called Dynamic Voltage Support Strength Factor(DVSF)for the hybrid multi-infeed system,and uses this index to qualitatively judge the voltage support capability-mVSCs-LCC in weak AC grid.In addition,the proposed evaluation index can also indirectly judge the ability of the LCC-HVDC subsystem to suppress commutation failure.Firstly,the mathematical model of the power flow of the LCC and VSC networks in the steady-state is analyzed,and the concept of DVSF applied to hybrid multi-infeed system is proposed.Furthermore,the DVSF index is also used to qualitatively judge the voltage support capability-mVSCs-LCC.Secondly,the influence of multiple VSC-HVDC subsystems with different operation strategies on the DVSF is analyzed with reference to the concept of DVSF.Finally,the indicators proposed in this paper are compared with other evaluation indicators through MATLAB simulation software to verify its effectiveness.More importantly,the effects of multi-VSC-HVDC subsystems using different coordinated control strategies on the voltage support capability of the receiving-end LCC-HVDC subsystem are also verified.
基金the National Natural Science Foundation of China(Grant No.51978041)。
文摘Tunnels deeply buried have high crustal stress and are prone to large deformation disasters when encountering soft rock.The large deformation phenomenon during the construction process of the Maoxian Tunnel on the Chengdu-Lanzhou Railway is particularly evident.This article focuses on the large deformation problem of the No.1 inclined shaft of the Maoxian Tunnel,and uses on-site monitoring methods to explore the reasons for tunnel structure failure,and analyzes the mechanical behavior of the tunnel structure.By using numerical simulation methods,the effectiveness of the second-layer support in resisting creep loads in tunnels was studied,and the influence of the construction time of the secondlayer support on the mechanical properties of the tunnel was discussed.The results indicate that the first-layer support in the tunnel is a structural failure caused by asymmetric deformation caused by creep,while the second-layer support has a good effect on resisting creep loads.The research results can provide a technical reference for deformation control of squeezing tunnels.
文摘The roadway support in many places of Jiulongkou Colliery, Fengfeng Mining Bureau, such as in the Permanent transportation roadway, was failed or locally caved, which seriously affected the colliery’s coal production performance and safety. Based on analysis of supporting objects for roadway repairing, this paper proposes the supporting parameters and condruction technics. The industrial ted of 70m long roadway repairing shows that the proposed parameters and technics of bolt shotcrete and mesh support for roadway repairing are reasouable, bring good technical and economic results for the colliery, and the repairing is successful.
基金This work was supported by the National Natural Science Foundation of China(Nos.41941018,52074164,and 42077267);the Natural Science Foundation of Shandong Province,China(Nos.2019SDZY04 and ZR2020JQ23)the Project of Shandong Province Higher Educational Youth Innovation Science and Technology Program,China(No.2019KJG013).
文摘In deep underground engineering,rock burst and other dynamic disasters are prone to occur due to stress concentration and energy accumulation in surrounding rock.The control of dynamic disasters requires bolts and cables with high strength,high elongation,and high energy-absorbing capacity.Therefore,a constant resistance energy-absorbing(CREA)material is developed.In this study,the dynamic characteristics of the new material are obtained via the drop hammer tests and the Split Hopkinson Pressure Bar(SHPB)tests of the new material and two common bolt(CB)materials widely used in the field.The test results of drop hammer test and SHPB test show that the percentage elongation of CREA material is more than 2.64 and 3.22 times those of the CB material,and the total impact energy acting on CREA material is more than 18.50 and 21.84 times,respectively,indicating that the new material has high elongation and high energy-absorbing capacity.Subsequently,the CREA bolts and cables using the new material are developed,which are applied in roadways with high stress and strong dynamic disturbance.The field monitoring results show that CREA bolts and cables can effectively control the surrounding rock deformation and ensure engineering safety.
基金provided by the National Basic Research 973 Program of China (No. 2013CB036003)the National Natural Science Foundation of China (No. 51374198)the Annual College Graduate Research and Innovation Projects of Jiangsu Province of China (No. KYLX15_1402)
文摘In order to solve the large deformation controlling problem for surrounding rock of gob-side entry driving under common cable anchor support in deep mine, site survey, physical modeling experiment, numerical simulation and field measurement were synthetically used to analyze the deformation and failure characteristics of surrounding rock. Besides, applicability analysis, prestress field distribution characteristics of surrounding rock and the control effect on large deformation of surrounding rock were also further studied for the gob-side entry driving in deep mine using the cable-truss supporting system. The results show that, first, compared with no support and traditional bolt anchor support, roof cable-truss system can effectively restrain the initiation and propagation of tensile cracks in the roof surrounding rock and arc shear cracks in the two sides, moreover, the broken development of surrounding rock, roof separation and extrusion deformation between the two sides of the roadway are all controlled; second, a prestressed belt of trapezoidal shape is generated in the surrounding rock by the cable-truss supporting system, and the prestress field range is wide. Especially, the prestress concentration belt in the shallow surrounding rock can greatly improve the anchoring strength and deformation resisting capability of the rock stratum;third, an optimized support system of ‘‘roof and side anchor net beam, roof cable-truss supporting system and anchor cable of the narrow coal pillar" was put forward, and the support optimization design and field industrial test were conducted for the gob-side entry driving of the working face 5302 in Tangkou Mine, from which a good supporting effect was obtained.
基金Supported by Visiting Scholar Foundation of Key Lab.In University"86 3" High Tech Projects(86 3-30 6 -ZT0 2 -0 4-2 )
文摘This paper presents a computer system reliability allocation method that is based on the theory of statistic and Markovian chain,which can be used to allocate reliability to subsystem, to hybrid system and software modules. A relevant supporting tool built by us is introduced.
基金Supported by the Aviation Science Funds (20090580013)the Fundamental Research Funds for the Central Universities (ZYGX2009J092)
文摘The random noises of multi-sensor and the environment make observations uncertain and correlative, so the performance of fusion algorithms is reduced by using observations directly. To solve this problem, a multi-layer track fusion algorithm based on supporting degree matrix is proposed. Combined with the track fusion algorithm based on filtering step by step, it uses multi-sensor observations to establish supporting degree matrix and realize multi-layer fusion. Simulation results show its estimation precision is higher than the original algorithm and is increased by 20% around. Therefore, it solves the problem of target tracking further in the distributed track fusion system.
基金Supported by the National Nature Science Foundation of China(No.51705445,52075468)General Project of Natural Science Foundation of Hebei Province(E2020203052)+1 种基金Youth Fund Project of Scientific Research Project of Hebei University(QN202013)Open Project Funding of Jiangsu Provincial Key Laboratory of Advanced Manufacture and Process for Marine Mechanical Equipment and Open Project Funding of Fluid Power Transmission Control Laboratory of Yanshan University.
文摘Because of hydraulic-electromagnetic double supporting forms,the supporting capacity and stiffness of magnetic-liquid double suspension bearing(MLDSB)can be improved sharply and then it is more suitable for medium speed,heavy load and frequent-starting occasions.Due to the multiple uncertainty,such as the coupling,the unmodeled dynamics,the parameter perturbation and the external disturbance perturbation,the robust stability and stiffness of control system of MLDSB are hard to meet the design requirements.Firstly,the structural features and the regulation mechanisms of MLDSB are presented and the radial 4-DOF kinetic equations are established.Secondly,the influence factors of the control system's coupling on unbalanced vibration caused by the deviation of the rotor center of mass are revealed,and then the weighting function of suppressing the unbalanced vibration can be obtained.Finally,H∞ controller of MLDSB is designed with H∞ mixed-sensitivity method,and the control performances of H∞ controller is compared with the state feedback controller.The simulation results show that single degree of freedom(DOF)supporting system of MLDSB with H∞ controller has good robust stability,stiffness and the ability to suppress unbalanced external disturbances.This study can provide the theoretical reference for stabilized suspension and control of MLDSB.
文摘In this paper, probabilistic models for three redundant configurations have been developed to analyze and compare some reliability characteristics. Each system is connected to a repairable supporting external device for operation. Repairable service station is provided for immediate repair of failed unit. Explicit expressions for mean time to system failure and steady-state availability for the three configurations are developed. Furthermore, we compare the three configurations based on their reliability characteristics and found that configuration II is more reliable and efficient than the remaining configurations.
文摘This proposal focuses on the prevalence of teenage pregnancy issue in NJ and illustrates the benefits of school-based health clinics and educational programs which should be implemented for teenage pregnancy and childbearing.Without the early intervention of educational programs and preventive medical services which should be implemented in school areas,teen pregnancy and childbearing can have physical and emotional health influences on teen mothers,their babies and other family members,and the worst consequence should be abortion.What’s more,teenage pregnancy and childbearing have substantial economic consequence for state.The annual estimated cost associated with teen childbearing (teens 19 and younger) in NJ to taxpayers is at least $167 million in 2004 (24% federal costs and 76% state and local costs).Studies demonstrated that a much larger amount of money is spent on the consequences of teenage pregnancy than on prevention.NJ has an opportunity to invest in prevention and reduce not only the monetary but also the societal costs to our youth burdened by the often overwhelming responsibilities of teenage pregnancy and parenting.According to the 15 years follow-up research and data analyzing,two models of success which specifically implemented in South Carolina high schools and Chicago public schools have been proved to effectively reduce incidence of repeat pregnancy and emergency room visits,reduce incidence of teen mothers smoking during pregnancy,improve emotional outcomes among teen mothers,decrease incidence of teen mothers drug impairment,arrest,conviction,or jail time and reduce use of food stamps and other public assistances,which can consequently increase the state public health costs.In order to support teen mothers’ academic,physical,emotional and social needs in a stable and consistent school environment,the plan which titled "Physical and Mental Health Promotion for NJ Teen Mothers" is effective and practical enough to arouse the attention of some relevant departments.It’s worth patron to fund the plan because supporting teenage pregnancy at early stage can subsequently benefit the national and state economy and teen mothers.
文摘Based on analysis of the supporting object of bulking soft rock and comparing the supporting difficulty of the repairing projects with that of the newly excavated projects, this paper proposes a method to determine reasonable supporting parameters for soft rock project repairing. This method has been verified to be reasonable and economical in an industrial test.
文摘The instability of trapezoidal Ⅰ-steel support is analysed for the compound roof of main coal seam in Shaqu Colliery, and the mechanism of bolt supporting is studied. A scheme of bolt supporting has been given and put into practice, remarkable technical and economic benefits have been got.
基金was supported by the Chinese National Natural Science Foundation of China(grant number 81371089)the Research Project of Wannan Medical College(grant number WK202122).
文摘Permanent damage to hair cells(HCs)is the leading cause of sensory deafness.Supporting cells(SCs)are essential in the restoration of hearing in mammals because they can proliferate and differentiate to HCs.MDS1 and EVI1 complex locus(MECOM)is vital in early development and cell differentiation and regulates the TGF-βsignaling pathway to adapt to pathophysiological events,such as hematopoietic proliferation,differentiation and cells death.In addition,MECOM plays an essential role in neurogenesis and craniofacial development.However,the role of MECOM in the development of cochlea and its way to regulate related signaling are not fully understood.To address this problem,this study examined the expression of MECOM during the development of cochlea and observed a significant increase of MECOM at the key point of auditory epithelial morphogenesis,indicating that MECOM may have a vital function in the formation of cochlea and regeneration of HCs.Meanwhile,we tried to explore the possible effect and potential mechanism of MECOM in SC proliferation and HC regeneration.Findings from this study indicate that overexpression of MECOM markedly increases the proliferation of SCs in the inner ear,and the expression of Smad3 and Cdkn2b related to TGF signaling is significantly down-regulated,corresponding to the overexpression of MECOM.Collectively,these data may provide an explanation of the vital function of MECOM in SC proliferation and trans-differentiation into HCs,as well as its regulation.The interaction between MECOM,Wnt,Notch and the TGF-βsignaling may provide a feasible approach to induce the regeneration of HCs.
