According to the distribution of abutment stress in a stope,this research established the mechanical model of mining abutment pressure transmission in floor base on the theory of semi-infnite plate body in elasticity....According to the distribution of abutment stress in a stope,this research established the mechanical model of mining abutment pressure transmission in floor base on the theory of semi-infnite plate body in elasticity.This study takes the 762 working face of Haizi Coal Mine as a case in point,and analyzed the dynamic evolution law of seam floor stress during the mining process.With an organic combination of the mining floor stress and surrounding rock stress,the study obtained the change laws of the maximum principle stress and the minimum one for the floor roadway surrounding rock when mining the upper working face.Considering the non-constant pressure force state and the cracks revolution mechanisms of floor roadway surrounding rock,the research built the mechanical model of roadway stress.Simulation results verify the reliability of the above conclusions.Moreover,this model could provide the theoretical basis and technical support for controlling floor roadway surrounding rock.展开更多
Magnesium(Mg)is the fourth most abundant element in the human body and is important in terms of specific osteogenesis functions.Here,we provide a comprehensive review of the use of magnesium-based biomaterials(MBs)in ...Magnesium(Mg)is the fourth most abundant element in the human body and is important in terms of specific osteogenesis functions.Here,we provide a comprehensive review of the use of magnesium-based biomaterials(MBs)in bone reconstruction.We review the history of MBs and their excellent biocompatibility,biodegradability and osteopromotive properties,highlighting them as candidates for a new generation of biodegradable orthopedic implants.In particular,the results reported in the field-specific literature(280 articles)in recent decades are dissected with respect to the extensive variety of MBs for orthopedic applications,including Mg/Mg alloys,bioglasses,bioceramics,and polymer materials.We also summarize the osteogenic mechanism of MBs,including a detailed section on the physiological process,namely,the enhanced osteogenesis,promotion of osteoblast adhesion and motility,immunomodulation,and enhanced angiogenesis.Moreover,the merits and limitations of current bone grafts and substitutes are compared.The objective of this review is to reveal the strong potential of MBs for their use as agents in bone repair and regeneration and to highlight issues that impede their clinical translation.Finally,the development and challenges of MBs for transplanted orthopedic materials are discussed.展开更多
Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and...Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.展开更多
Intensive farming is a primary cause of increased sediment and associated nitrogen(N)and phosphorus(P)loads in surface water systems.Determining their contributing sources,pathways and loads present major challenges i...Intensive farming is a primary cause of increased sediment and associated nitrogen(N)and phosphorus(P)loads in surface water systems.Determining their contributing sources,pathways and loads present major challenges in the high-intensity agricultural catchments.Herein,we quantify the sediment sources and magnitude of sediment total N and total P from different sources using a novel application of compound-specific stable isotope(CSSI)and fallout radionuclides(FRNs)of^(137)cs and^(210)pbex in an intensive agricultural catchment in North China.Sediment sources from surface and sub-surface soils were estimated from FRNs fingerprint and accounted for 62±7%and 38±7%respectively,while surface soil from land uses that originated from hillslope were identified by CssI fingerprint.Using a novel application of FRNs and CSSI sediment fingerprinting techniques,the dominant sediment source was derived from maize farmland(44±0.1%),followed by channel bank(38±7%).The sedimentation rate(13.55±0.30 t ha^(-1)yr^(-1))was quantifed by the^(137)cs cores(0-60 cm)at the outlet of this catchment.The total N and total P in sediment were both mostly derived from maize farmland and least from channel banks.The channel banks are significant sediment sources but contribute little to the input of sediment N and P for eutrophication.It implies that chemically-applied farmlands are the main hotspots for catchment erosion control and pollution prevention.The novel application of FRNs and CSSI techniques cost-effectively quantified sediment N and P loads from different sources with a single visit to the catchment,enabling rapid assessment for optimizing soil conservation strategies and land management practices.展开更多
During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow...During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow of the gathering pipeline in the Changning Shale Gas Field as an example to test the erosion rate and material removal mechanism of the test piece at different angles of the elbow through experiments and compares the four erosion models with the experimental results. Through analysis, it is found that the best prediction model for quartz sand-carbon steel erosion is the Oka model. Based on the Oka model, FLUENT software was used to simulate and analyze the law of erosion of the elbow of the gas gathering pipeline under different gas flow velocities, gas gathering pressure, particle size, length of L1,and bending directions of the elbow. And a spiral pipeline structure is proposed to reduce the erosion rate of the elbow under the same working conditions. The results show that this structure can reduce erosion by 34%.展开更多
Phytocyanin(PC)is a class of plant-specific blue copper proteins involved in electron transport,plant growth,development,and stress resistance.However,PC proteins have not been systematically evaluated in tobacco plan...Phytocyanin(PC)is a class of plant-specific blue copper proteins involved in electron transport,plant growth,development,and stress resistance.However,PC proteins have not been systematically evaluated in tobacco plants.We determined the whole-genome sequences of the PC family in the tobacco cultivar‘K326.’The transcriptome data were used to analyze the expression of the NtPC family at different development stages and tissue-specific genes.Real-time fluorescence quantitative analysis was used to analyze the expression of the NtPC gene family under low temperature and methyl jasmonate stress.The tobacco NtPC family contained 110 members and was divided into four subfamilies:early nodulin-like protein(NtENODL),uclacyanin-like protein,stellacyanin1-like protein,and plantacyanin-like protein.According to phylogenetic and structural analyses,the NtPC family could be divided into eight structural types.Fifty-three NtPCs were randomly distributed on 22 of 24 tobacco chromosomes.Collinearity analysis revealed 33 pairs of genes belonging to the NtPC family.Gene ontology analysis showed that the PC genes are components of the plasma membrane and may participate in plasma membrane-related functions.The NtPC family contained numerous elements related to hormonal and abiotic stress responses and was specifically expressed in the tobacco prosperous,maturation,and budding periods.Tissue-specific expression analysis showed that some genes were tissue specific.The expression of NtENODL58 and other genes was significantly induced by low-temperature and methyl jasmonate stress.Thus,the NtPC gene family plays an important role in plant stress response.展开更多
The compression and creep characteristics of moraine soil are important mechanical properties of geomaterials to be analyzed during the construction process of engineering projects.However,related references about the...The compression and creep characteristics of moraine soil are important mechanical properties of geomaterials to be analyzed during the construction process of engineering projects.However,related references about these characteristics through large-size in-situ tests have rarely been reported.In this study,in-situ tests of particle size distribution,compression deformation,and compression creep were conducted at the Xingkang Bridge,West Sichuan,China.The results show that the uniformity coefficient of moraine soil ranges from 12.1 to 183.3,and gradation coefficient ranges from 0.4 to 2.8.The total compression deformations of moraine samples during the conventional compression deformation test are 4.70,4.07,and 0.47 mm,and their residual deformations are 2.81,2.45,and 0.22 mm,respectively.The deformation modulus ranges from 127.3 to 676.4 MPa,and elastic modulus ranges from 316.3 to 765.7 MPa.During compression creep tests,moraine soil enters the steady creep stage after 3.8 h of loading pressure at 445 k Pa,and it keeps steady after 14 h of loading pressure at 900 k Pa.The Burgers model and generalized Kelvin model predict the deformation well in transient,deceleration and steady creep stages.Results provide a valuable reference for the analysis of the compression deformation and creep behavior of moraine soil during engineering construction and management.展开更多
Borehole blockage caused by asphaltene deposition is a problem in crude oil production in the Tahe Oilfield, Xinjiang, China. This study has investigated the influences of crude oil compositions, temperature and press...Borehole blockage caused by asphaltene deposition is a problem in crude oil production in the Tahe Oilfield, Xinjiang, China. This study has investigated the influences of crude oil compositions, temperature and pressure on asphaltene deposition. The asphaltene deposition trend of crude oil was studied by saturates, aromatics, resins and asphaltenes （SARA） method, and the turbidity method was applied for the first time to determine the onset of asphaltene flocculation. The results showed that the asphaltene deposition trend of crude oil by the turbidity method was in accordance with that by the SARA method. The asphaltene solubility in crude oil decreased with decreasing temperature and the amount of asphaltene deposits of T739 crude oil （from well T739, Tahe Oilfield） had a maximum value at 60℃. From the PVT results, the bubble point pressure of TH 10403CX crude oil （from well TH10403CX, Tahe Oilfield） at different temperatures can be obtained and the depth at which the maximum asphaltene flocculation would occur in boreholes can be calculated. The crude oil PVT results showed that at 50,90 and 130 ℃, the bubble point pressure of TH 10403CX crude oil was 25.2, 26,4 and 27.0 MPa, respectively. The depth of injecting asphaltene deposition inhibitors for TH10403CX was determined to be 2,700 m.展开更多
Monkeypox is a zoonotic disease.Since the first human monkeypox case was detected in 1970,it has been prevalent in some countries in central and western Africa.Since May 2022,monkeypox cases have been reported in more...Monkeypox is a zoonotic disease.Since the first human monkeypox case was detected in 1970,it has been prevalent in some countries in central and western Africa.Since May 2022,monkeypox cases have been reported in more than 96 non-endemic countries and regions worldwide.As of September 14,2022,there have been more than 58,200 human monkeypox cases,and there is community transmission.The cessation of smallpox vaccination in 1980,which had some cross-protection with monkeypox,resulted in a general lack of immunity to monkeypox,which caused global concern and vigilance.As of Sep-tember 14,2022,there are four monkeypox cases in China,including three in Taiwan province and one in Hong Kong city.Previous foreign studies have shown that children are vulnerable to monkeypox and are also at high risk for severe disease or complications.In order to improve pediatricians'understanding of monkeypox and achieve early detection,early diagno-sis,early treatment,and early disposal,we have organized national authoritative experts in pediatric infection,respiratory,dermatology,critical care medicine,infectious diseases,and public health and others to formulate this expert consensus,on the basis of the latest"Clinical management and infection prevention and control for monkeypox"released by The World Health Organization,the"guidelines for diagnosis and treatment of monkeypox(version 2022)"issued by National Health Commission of the People's Republic of China and other relevant documents.During the development of this consensus,multidisciplinary experts have repeatedly demonstrated the etiology,epidemiology,transmission,clinical manifestations,laboratory examinations,diagnosis,differential diagnosis,treatment,discharge criteria,prevention,disposal process,and key points of prevention and control of suspected and confirmed cases.展开更多
In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumptio...In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.展开更多
Al-cladded Al-Zn-Mg-Cu sheets were compressed up to70%reduction on a Gleeble-3500thermo-mechanical simulatorwith temperatures ranging from380to450°C at strain rates between0.1and30s-1.The microstructures of the A...Al-cladded Al-Zn-Mg-Cu sheets were compressed up to70%reduction on a Gleeble-3500thermo-mechanical simulatorwith temperatures ranging from380to450°C at strain rates between0.1and30s-1.The microstructures of the Al cladding and theAl-Zn-Mg-Cu matrix were characterized by electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD).Themicrostructure is closely related to the level of recovery and recrystallization,which can be influenced by deformation temperature,deformation pass and deformation rate.The level of recovery and recrystallization are different in the Al cladding and theAl-Zn-Mg-Cu matrix.Higher deformation temperature results in higher degree of recrystallization and coarser grain size.Staticrecrystallization and recovery can happen during the interval of deformation passes.Higher strain rate leads to finer sub-grains atstrain rate below10s-1;however,dynamic recovery and recrystallization are limited at strain rate of30s-1due to shorter duration atelevated temperatures.展开更多
Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support str...Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support structure,while combining a variety of algorithms,according to different geological conditions and slope stability,as well as summarizes the pile foundation bearing-retaining wall combination structure force analysis and design methods,taking a high-fill road project in Chongqing as an example.The application of this support structure under special conditions,such as thicker soil layer,steeper sliding surface,weak foundation,and limited slope release conditions,is presented,which illustrates the technical advantages of this support structure and proving that it has several other advantages,including clear force mechanism as well as economic and reasonable structure,thus providing reference for similar projects.展开更多
Many wellbores are blocked by asphaltene deposits,which lead to production problems in the oilfield development process.In this paper,methods such as elemental analysis,and solvent extraction are adopted for the study...Many wellbores are blocked by asphaltene deposits,which lead to production problems in the oilfield development process.In this paper,methods such as elemental analysis,and solvent extraction are adopted for the study of wellbore blockages.The content of organic matter in blockages is higher than 96% and asphaltene is the main component of the organic matter with n-heptane asphaltene content of 38%.Based on the above analyses,an agent for asphaltene dispersion and removal（named as SDJ） was developed.The performance of the SDJ agent was evaluated,and it was found that the dissolution rate of asphaltene can reach 2.9 mg.mL-1.min-1 at 60 oC.SDJ agent（1wt%） was added to crude oil with a colloid instability index greater than 0.9 can effectively inhibit asphaltene deposition in the wellbore.By the viscosity method,the dissolution amount of SDJ agent was calculated,and it was found that when the viscosity of the system is around 2,000 mPa.s（the common viscosity of crude oil）,the amount of SDJ agent added to the blockage was at least 96 g per 100 g blockages.Therefore,SDJ agent has promising application for dispersion and removal of asphaltene deposition in high-asphaltene wells.展开更多
Carried on the one-dimensional analysis to the motion state of coal-gas flow in the outburst hole, and deduced the relational expression between the motion parameters （containing of velocity, flow rate and density e...Carried on the one-dimensional analysis to the motion state of coal-gas flow in the outburst hole, and deduced the relational expression between the motion parameters （containing of velocity, flow rate and density etc.） of bursting coal-gas flow and gas pressure in the hole, then pointed out the critical state change of coal-gas flow under different pressure conditions which had the very tremendous influence on both stability and destructiveness of the entire coal and gas outburst system. The mathematical processing and results of one-dimensional flow under the perfect condition are simple and explicit in this paper, which has the certain practical significance.展开更多
Creep mechanics characteristics of large scale tectonic coal was studied under gas draingae and disturbance conditions by using the new self-developed coal gas cou- pling three axial creep equipment.The results show t...Creep mechanics characteristics of large scale tectonic coal was studied under gas draingae and disturbance conditions by using the new self-developed coal gas cou- pling three axial creep equipment.The results show that when σ_1 is smaller,σ_3 is larger, gas pressure and disturbance load are smaller,gassy coal has no disturbance to creep. When σ_3 is smaller,gas pressure and σ_1 are larger,disturbance load is constant,gassy coal has remarkable effects of disturbance to creep.The concepts of disturbance load sensitive domain and disturbance creep sensitive domain were put forward.Under same amplitude disturbance stress condition,blasting disturbance has a stronger influence on gassy coal deformation is related to frequency of disturbance load;gas drainage,blasting excavation and mining play an important role in coal-gas outbursting.The relationship of gassy coal creep and gas pressure gradient,the creep constitutive equation built with gas pressure gradient and disturbance load as independent variables within the framework of fluid-solid two phases coupling were established.展开更多
Introduction The 2021 Annual Conference of the Housing and Community Planning Committee of the Urban Planning Society of China(UPSC)was successfully held in Beijing on Jun.5,2021.Under the guidance of the UPSC,the con...Introduction The 2021 Annual Conference of the Housing and Community Planning Committee of the Urban Planning Society of China(UPSC)was successfully held in Beijing on Jun.5,2021.Under the guidance of the UPSC,the conference was hosted by the Housing and Community Planning Committee of the UPSC,and jointly supported by the Beijing Tsinghua Tongheng Urban Planning&Design Institute and the Specialized Committee of Community Building,Science and Technology Committee,Ministry of Housing and Urban-Rural Development.展开更多
Used numerical simulation method to study the floor water-inrush mechanism in working face which was influenced by fault structure, and set up many kinds of models and performs numerical calculation by fully using lar...Used numerical simulation method to study the floor water-inrush mechanism in working face which was influenced by fault structure, and set up many kinds of models and performs numerical calculation by fully using large finite element soft-ANSYS and element birth-death method. The results show that the more high the underground water pressure, the more big the floor displacement and possibility of water-inrush; the floor which has fault structure is more prone to water-inrush than the floor which not has fault structure, the floor which has multi-groups cracks is more prone to water-inrush than the floor which has single-group cracks. The numerical simulation result forecasts the water-inrush in working face preferably.展开更多
Based on mechanism of AE creation, put forward sphere cavity model, and deduced wave Equation of AE wave radiated by the AE source in detail, and analyzed the propagation attenuation law of AE stress wave in coal （r...Based on mechanism of AE creation, put forward sphere cavity model, and deduced wave Equation of AE wave radiated by the AE source in detail, and analyzed the propagation attenuation law of AE stress wave in coal （rock） strata. Displacement function of AE wave indicates that displacement field can be divided into two parts. Firstly, displacement of particle is approaching to the source intensity function in zone near the AE source. Secondly, in zone far away from the AE source, displacement of particle is approaching to the derivative of source intensity function. AE wave changes gradually in the spreading process, and notable change of the wave form happens when wave propagates far away from the AE source.展开更多
In order to study the influence of a fault on the movement law of the overlying strata as well as its effect on the gas drainage boreholes, based on the practical situation of 1242（1） panel at Xieqiao Mine in Huaina...In order to study the influence of a fault on the movement law of the overlying strata as well as its effect on the gas drainage boreholes, based on the practical situation of 1242（1） panel at Xieqiao Mine in Huainan, the Finite Element Method （FEM） model was built up, and the distribution of the stress field and the displacement field of the overlying strata in the stope with a fault were simulated by using the FEM software ANSYS. The results indicate that because of the existence of the fault, the horizontal displacement of overlying strata near the gas drainage borehole becomes larger than that in the stope without a fault, and the distribution of the stress field of the overlying strata changes greatly. When the working face is far away from the fault, the distribution of the stress field is approximately symmetrical. As the working face advances to the place 50 m away from the fault, the stress range at the right side goaf area is as twice as that at the left side. Here, the stress distribution area of goaf area and the fault plane run through, the fracture-connected-zone is formed. It can be presumed that the gas adsorbed in the coal and rock will flow into the fault zone along the fracture-connected-zone, which causes the quantity of gas drainage reduce remarkably.展开更多
基金supported by the National Natural Science Foundation of China(No.51074004)the Open Project of State Key Laboratory Breeding Base for Mining Disaster Prevention and Control of Shandong University of Science and Technology of China(No.MDPC2012KF06)+1 种基金the Natural Science Foundation of Anhui Province of China(No.11040606M102)Young Teachers Science Foundation of Anhui University of Science&Technology of China(No.2012QNZ14)
文摘According to the distribution of abutment stress in a stope,this research established the mechanical model of mining abutment pressure transmission in floor base on the theory of semi-infnite plate body in elasticity.This study takes the 762 working face of Haizi Coal Mine as a case in point,and analyzed the dynamic evolution law of seam floor stress during the mining process.With an organic combination of the mining floor stress and surrounding rock stress,the study obtained the change laws of the maximum principle stress and the minimum one for the floor roadway surrounding rock when mining the upper working face.Considering the non-constant pressure force state and the cracks revolution mechanisms of floor roadway surrounding rock,the research built the mechanical model of roadway stress.Simulation results verify the reliability of the above conclusions.Moreover,this model could provide the theoretical basis and technical support for controlling floor roadway surrounding rock.
基金financial support from the National Natural Science Foundation of China(No.81672230)the Natural Science Foundation of Chongqing(No.cstc2020jcyjmsxm2234)+1 种基金the Top-notch Young Talent Project of Chongqing Traditional Chinese Medicine Hospital(No.CQSZYY2020008)the Chongqing Graduate Research Innovation Project(No.CYS20199)。
文摘Magnesium(Mg)is the fourth most abundant element in the human body and is important in terms of specific osteogenesis functions.Here,we provide a comprehensive review of the use of magnesium-based biomaterials(MBs)in bone reconstruction.We review the history of MBs and their excellent biocompatibility,biodegradability and osteopromotive properties,highlighting them as candidates for a new generation of biodegradable orthopedic implants.In particular,the results reported in the field-specific literature(280 articles)in recent decades are dissected with respect to the extensive variety of MBs for orthopedic applications,including Mg/Mg alloys,bioglasses,bioceramics,and polymer materials.We also summarize the osteogenic mechanism of MBs,including a detailed section on the physiological process,namely,the enhanced osteogenesis,promotion of osteoblast adhesion and motility,immunomodulation,and enhanced angiogenesis.Moreover,the merits and limitations of current bone grafts and substitutes are compared.The objective of this review is to reveal the strong potential of MBs for their use as agents in bone repair and regeneration and to highlight issues that impede their clinical translation.Finally,the development and challenges of MBs for transplanted orthopedic materials are discussed.
基金the financial support provided by the National Natural Science Foundation of China(Grant No.42302332)the Special Funding of Chongqing Postdoctoral Research Project(Grant No.2022CQBSHTB2061,2022CQBSHTB1010)+3 种基金the Chongqing Postdoctoral Science Foundation(Grant No.CSTB2022NSCQ-BHX0738,CSTB2023NSCQBHX0223)the China Postdoctoral Science Foundation(Grant No.2023M730432)the Natural Science Foundation of Chongqing(Grant No.CSTB2023NSCQMSX0913,cstc2021jcyj-msxm X0869)the Postdoctoral Science Foundation of Chongqing Jiaotong University(Grant No.F1220105,22JDKJC-A008)。
文摘Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.
基金supported by the International Atomic Energy Agency through coordination research projects(CRP)under Research Contract No.23008 and technical cooperation project(TCP)RAS 5084,and the Central Public-interest Scientific Institution Basal Research Fund(No.BSRF202004)Funding for AC to collaborate on this work was provided by the High-end Foreign Experts Recruitment Program from State of Administration of Foreign Experts Affairs of ChinaThis work was partly supported by the Science and Technology Major Project of Guangxi(Guike AA17204078).
文摘Intensive farming is a primary cause of increased sediment and associated nitrogen(N)and phosphorus(P)loads in surface water systems.Determining their contributing sources,pathways and loads present major challenges in the high-intensity agricultural catchments.Herein,we quantify the sediment sources and magnitude of sediment total N and total P from different sources using a novel application of compound-specific stable isotope(CSSI)and fallout radionuclides(FRNs)of^(137)cs and^(210)pbex in an intensive agricultural catchment in North China.Sediment sources from surface and sub-surface soils were estimated from FRNs fingerprint and accounted for 62±7%and 38±7%respectively,while surface soil from land uses that originated from hillslope were identified by CssI fingerprint.Using a novel application of FRNs and CSSI sediment fingerprinting techniques,the dominant sediment source was derived from maize farmland(44±0.1%),followed by channel bank(38±7%).The sedimentation rate(13.55±0.30 t ha^(-1)yr^(-1))was quantifed by the^(137)cs cores(0-60 cm)at the outlet of this catchment.The total N and total P in sediment were both mostly derived from maize farmland and least from channel banks.The channel banks are significant sediment sources but contribute little to the input of sediment N and P for eutrophication.It implies that chemically-applied farmlands are the main hotspots for catchment erosion control and pollution prevention.The novel application of FRNs and CSSI techniques cost-effectively quantified sediment N and P loads from different sources with a single visit to the catchment,enabling rapid assessment for optimizing soil conservation strategies and land management practices.
基金supported by the Petrochina's “14th Five-Year plan” Project(2021DJ2804)Sichuan Natural Science Foundation(2023NSFSC0422)。
文摘During the production period of shale gas, proppant particles and rock debris are produced together,which will seriously erode the elbows of gathering pipelines. In response to this problem, this paper takes the elbow of the gathering pipeline in the Changning Shale Gas Field as an example to test the erosion rate and material removal mechanism of the test piece at different angles of the elbow through experiments and compares the four erosion models with the experimental results. Through analysis, it is found that the best prediction model for quartz sand-carbon steel erosion is the Oka model. Based on the Oka model, FLUENT software was used to simulate and analyze the law of erosion of the elbow of the gas gathering pipeline under different gas flow velocities, gas gathering pressure, particle size, length of L1,and bending directions of the elbow. And a spiral pipeline structure is proposed to reduce the erosion rate of the elbow under the same working conditions. The results show that this structure can reduce erosion by 34%.
基金This study was supported by the Tobacco Science Research Institute of the Chongqing Tobacco Company(A20201NY01-1305).
文摘Phytocyanin(PC)is a class of plant-specific blue copper proteins involved in electron transport,plant growth,development,and stress resistance.However,PC proteins have not been systematically evaluated in tobacco plants.We determined the whole-genome sequences of the PC family in the tobacco cultivar‘K326.’The transcriptome data were used to analyze the expression of the NtPC family at different development stages and tissue-specific genes.Real-time fluorescence quantitative analysis was used to analyze the expression of the NtPC gene family under low temperature and methyl jasmonate stress.The tobacco NtPC family contained 110 members and was divided into four subfamilies:early nodulin-like protein(NtENODL),uclacyanin-like protein,stellacyanin1-like protein,and plantacyanin-like protein.According to phylogenetic and structural analyses,the NtPC family could be divided into eight structural types.Fifty-three NtPCs were randomly distributed on 22 of 24 tobacco chromosomes.Collinearity analysis revealed 33 pairs of genes belonging to the NtPC family.Gene ontology analysis showed that the PC genes are components of the plasma membrane and may participate in plasma membrane-related functions.The NtPC family contained numerous elements related to hormonal and abiotic stress responses and was specifically expressed in the tobacco prosperous,maturation,and budding periods.Tissue-specific expression analysis showed that some genes were tissue specific.The expression of NtENODL58 and other genes was significantly induced by low-temperature and methyl jasmonate stress.Thus,the NtPC gene family plays an important role in plant stress response.
基金supported by the Engineering Research Center of Rock-Soil Drilling&Excavation and Protection,Ministry of Education (No.202202)the National Natural Science Foundation of China (Nos.42107180,42162023 and 42162025)the Construction S&T Project of Department of Transportation of Sichuan Province of China (No.2020A01)。
文摘The compression and creep characteristics of moraine soil are important mechanical properties of geomaterials to be analyzed during the construction process of engineering projects.However,related references about these characteristics through large-size in-situ tests have rarely been reported.In this study,in-situ tests of particle size distribution,compression deformation,and compression creep were conducted at the Xingkang Bridge,West Sichuan,China.The results show that the uniformity coefficient of moraine soil ranges from 12.1 to 183.3,and gradation coefficient ranges from 0.4 to 2.8.The total compression deformations of moraine samples during the conventional compression deformation test are 4.70,4.07,and 0.47 mm,and their residual deformations are 2.81,2.45,and 0.22 mm,respectively.The deformation modulus ranges from 127.3 to 676.4 MPa,and elastic modulus ranges from 316.3 to 765.7 MPa.During compression creep tests,moraine soil enters the steady creep stage after 3.8 h of loading pressure at 445 k Pa,and it keeps steady after 14 h of loading pressure at 900 k Pa.The Burgers model and generalized Kelvin model predict the deformation well in transient,deceleration and steady creep stages.Results provide a valuable reference for the analysis of the compression deformation and creep behavior of moraine soil during engineering construction and management.
基金National High Technology Research and Development Program of China(No.2013AA064301)National Natural Science Foundation of China (No.51274210)12th National Science and Technology Major Project of the Ministry of Science and Technology of China (No.2011ZX05049-003-001-002)
文摘Borehole blockage caused by asphaltene deposition is a problem in crude oil production in the Tahe Oilfield, Xinjiang, China. This study has investigated the influences of crude oil compositions, temperature and pressure on asphaltene deposition. The asphaltene deposition trend of crude oil was studied by saturates, aromatics, resins and asphaltenes （SARA） method, and the turbidity method was applied for the first time to determine the onset of asphaltene flocculation. The results showed that the asphaltene deposition trend of crude oil by the turbidity method was in accordance with that by the SARA method. The asphaltene solubility in crude oil decreased with decreasing temperature and the amount of asphaltene deposits of T739 crude oil （from well T739, Tahe Oilfield） had a maximum value at 60℃. From the PVT results, the bubble point pressure of TH 10403CX crude oil （from well TH10403CX, Tahe Oilfield） at different temperatures can be obtained and the depth at which the maximum asphaltene flocculation would occur in boreholes can be calculated. The crude oil PVT results showed that at 50,90 and 130 ℃, the bubble point pressure of TH 10403CX crude oil was 25.2, 26,4 and 27.0 MPa, respectively. The depth of injecting asphaltene deposition inhibitors for TH10403CX was determined to be 2,700 m.
基金National Natural Science Foundation of China(72174138)High-level Public health Talents Training Program of Beijing Municipal Health Commission(2022-2-002).
文摘Monkeypox is a zoonotic disease.Since the first human monkeypox case was detected in 1970,it has been prevalent in some countries in central and western Africa.Since May 2022,monkeypox cases have been reported in more than 96 non-endemic countries and regions worldwide.As of September 14,2022,there have been more than 58,200 human monkeypox cases,and there is community transmission.The cessation of smallpox vaccination in 1980,which had some cross-protection with monkeypox,resulted in a general lack of immunity to monkeypox,which caused global concern and vigilance.As of Sep-tember 14,2022,there are four monkeypox cases in China,including three in Taiwan province and one in Hong Kong city.Previous foreign studies have shown that children are vulnerable to monkeypox and are also at high risk for severe disease or complications.In order to improve pediatricians'understanding of monkeypox and achieve early detection,early diagno-sis,early treatment,and early disposal,we have organized national authoritative experts in pediatric infection,respiratory,dermatology,critical care medicine,infectious diseases,and public health and others to formulate this expert consensus,on the basis of the latest"Clinical management and infection prevention and control for monkeypox"released by The World Health Organization,the"guidelines for diagnosis and treatment of monkeypox(version 2022)"issued by National Health Commission of the People's Republic of China and other relevant documents.During the development of this consensus,multidisciplinary experts have repeatedly demonstrated the etiology,epidemiology,transmission,clinical manifestations,laboratory examinations,diagnosis,differential diagnosis,treatment,discharge criteria,prevention,disposal process,and key points of prevention and control of suspected and confirmed cases.
基金support from the National Natural Science Foundation of China (Nos.U1261205, 51474139 and 51204103)the Science and Technology Development Plan of Shandong Province (No.2013GSF12004)the Excellent Young Scientific Talents Project of Shandong University of Science and Technology (No.2014JQJH106)
文摘In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.
基金Projects(2016YFB0300901,2016YFB0700401) supported by the National Key Research and Development Program of ChinaProjects(106112015CDJXY130003,106112015CDJXZ138803) supported by the Fundamental Research Funds for the Central Universities,China
文摘Al-cladded Al-Zn-Mg-Cu sheets were compressed up to70%reduction on a Gleeble-3500thermo-mechanical simulatorwith temperatures ranging from380to450°C at strain rates between0.1and30s-1.The microstructures of the Al cladding and theAl-Zn-Mg-Cu matrix were characterized by electron back-scattered diffraction(EBSD)and X-ray diffraction(XRD).Themicrostructure is closely related to the level of recovery and recrystallization,which can be influenced by deformation temperature,deformation pass and deformation rate.The level of recovery and recrystallization are different in the Al cladding and theAl-Zn-Mg-Cu matrix.Higher deformation temperature results in higher degree of recrystallization and coarser grain size.Staticrecrystallization and recovery can happen during the interval of deformation passes.Higher strain rate leads to finer sub-grains atstrain rate below10s-1;however,dynamic recovery and recrystallization are limited at strain rate of30s-1due to shorter duration atelevated temperatures.
基金Youth Project of Science and Technology Research of Chongqing Municipal Education Commission“Research on the Promotion of Pile Foundation Bearing-Retaining Wall Combined Structure Technology”(Project Number:KJQN201905601)Youth Project of Science and Technology Research of Chongqing Education Commission“Research on Construction Monitoring and Risk Warning of Deep Foundation Pit Project Based on BIM+Internet of Things”(Project Number:KJQN201904306)。
文摘Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support structure,while combining a variety of algorithms,according to different geological conditions and slope stability,as well as summarizes the pile foundation bearing-retaining wall combination structure force analysis and design methods,taking a high-fill road project in Chongqing as an example.The application of this support structure under special conditions,such as thicker soil layer,steeper sliding surface,weak foundation,and limited slope release conditions,is presented,which illustrates the technical advantages of this support structure and proving that it has several other advantages,including clear force mechanism as well as economic and reasonable structure,thus providing reference for similar projects.
基金the National High Technology Research and Development Program of China (No.SS2013AA060801)National Natural Science Foundation of China (No.51274210)12th National Science and Technology Major Project of Ministry of Science and Technology of China (No. 20112X05049-003-001-002)for financial support
文摘Many wellbores are blocked by asphaltene deposits,which lead to production problems in the oilfield development process.In this paper,methods such as elemental analysis,and solvent extraction are adopted for the study of wellbore blockages.The content of organic matter in blockages is higher than 96% and asphaltene is the main component of the organic matter with n-heptane asphaltene content of 38%.Based on the above analyses,an agent for asphaltene dispersion and removal（named as SDJ） was developed.The performance of the SDJ agent was evaluated,and it was found that the dissolution rate of asphaltene can reach 2.9 mg.mL-1.min-1 at 60 oC.SDJ agent（1wt%） was added to crude oil with a colloid instability index greater than 0.9 can effectively inhibit asphaltene deposition in the wellbore.By the viscosity method,the dissolution amount of SDJ agent was calculated,and it was found that when the viscosity of the system is around 2,000 mPa.s（the common viscosity of crude oil）,the amount of SDJ agent added to the blockage was at least 96 g per 100 g blockages.Therefore,SDJ agent has promising application for dispersion and removal of asphaltene deposition in high-asphaltene wells.
基金Supported by the Key Program of＂National Basic Research Program of China （973 Program）＂ （2005CB221504） the Key Program of＂National Natural Science Foundation of China＂ （50534080）
文摘Carried on the one-dimensional analysis to the motion state of coal-gas flow in the outburst hole, and deduced the relational expression between the motion parameters （containing of velocity, flow rate and density etc.） of bursting coal-gas flow and gas pressure in the hole, then pointed out the critical state change of coal-gas flow under different pressure conditions which had the very tremendous influence on both stability and destructiveness of the entire coal and gas outburst system. The mathematical processing and results of one-dimensional flow under the perfect condition are simple and explicit in this paper, which has the certain practical significance.
基金the National Natural Science Foundation(50474029)the China Natural Science Foundation(50534080)+1 种基金the Innovative Research Group(50221402)the Anhui University of Science &Technology Doctor's Fund Project(11142)
文摘Creep mechanics characteristics of large scale tectonic coal was studied under gas draingae and disturbance conditions by using the new self-developed coal gas cou- pling three axial creep equipment.The results show that when σ_1 is smaller,σ_3 is larger, gas pressure and disturbance load are smaller,gassy coal has no disturbance to creep. When σ_3 is smaller,gas pressure and σ_1 are larger,disturbance load is constant,gassy coal has remarkable effects of disturbance to creep.The concepts of disturbance load sensitive domain and disturbance creep sensitive domain were put forward.Under same amplitude disturbance stress condition,blasting disturbance has a stronger influence on gassy coal deformation is related to frequency of disturbance load;gas drainage,blasting excavation and mining play an important role in coal-gas outbursting.The relationship of gassy coal creep and gas pressure gradient,the creep constitutive equation built with gas pressure gradient and disturbance load as independent variables within the framework of fluid-solid two phases coupling were established.
文摘Introduction The 2021 Annual Conference of the Housing and Community Planning Committee of the Urban Planning Society of China(UPSC)was successfully held in Beijing on Jun.5,2021.Under the guidance of the UPSC,the conference was hosted by the Housing and Community Planning Committee of the UPSC,and jointly supported by the Beijing Tsinghua Tongheng Urban Planning&Design Institute and the Specialized Committee of Community Building,Science and Technology Committee,Ministry of Housing and Urban-Rural Development.
文摘Used numerical simulation method to study the floor water-inrush mechanism in working face which was influenced by fault structure, and set up many kinds of models and performs numerical calculation by fully using large finite element soft-ANSYS and element birth-death method. The results show that the more high the underground water pressure, the more big the floor displacement and possibility of water-inrush; the floor which has fault structure is more prone to water-inrush than the floor which not has fault structure, the floor which has multi-groups cracks is more prone to water-inrush than the floor which has single-group cracks. The numerical simulation result forecasts the water-inrush in working face preferably.
基金Supported by National Basic Research Program of China （2005CB221505） National Natural Science Foundation of China （2005E041503）
文摘Based on mechanism of AE creation, put forward sphere cavity model, and deduced wave Equation of AE wave radiated by the AE source in detail, and analyzed the propagation attenuation law of AE stress wave in coal （rock） strata. Displacement function of AE wave indicates that displacement field can be divided into two parts. Firstly, displacement of particle is approaching to the source intensity function in zone near the AE source. Secondly, in zone far away from the AE source, displacement of particle is approaching to the derivative of source intensity function. AE wave changes gradually in the spreading process, and notable change of the wave form happens when wave propagates far away from the AE source.
基金Supported by the National Natural Science Foundation of China（50534080） the National Basic Research Program of China（2005CB221504） Taishan Scholar Engineering Construction Foundation of Shandong Province
文摘In order to study the influence of a fault on the movement law of the overlying strata as well as its effect on the gas drainage boreholes, based on the practical situation of 1242（1） panel at Xieqiao Mine in Huainan, the Finite Element Method （FEM） model was built up, and the distribution of the stress field and the displacement field of the overlying strata in the stope with a fault were simulated by using the FEM software ANSYS. The results indicate that because of the existence of the fault, the horizontal displacement of overlying strata near the gas drainage borehole becomes larger than that in the stope without a fault, and the distribution of the stress field of the overlying strata changes greatly. When the working face is far away from the fault, the distribution of the stress field is approximately symmetrical. As the working face advances to the place 50 m away from the fault, the stress range at the right side goaf area is as twice as that at the left side. Here, the stress distribution area of goaf area and the fault plane run through, the fracture-connected-zone is formed. It can be presumed that the gas adsorbed in the coal and rock will flow into the fault zone along the fracture-connected-zone, which causes the quantity of gas drainage reduce remarkably.
