To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses,a theoretical and methodological system called the statistical mechanics of rock masses(SMRM)was developed in the pas...To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses,a theoretical and methodological system called the statistical mechanics of rock masses(SMRM)was developed in the past three decades.In SMRM,equivalent continuum models of stressestrain relationship,strength and failure probability for jointed rock masses were established,which were based on the geometric probability models characterising the rock mass structure.This follows the statistical physics,the continuum mechanics,the fracture mechanics and the weakest link hypothesis.A general constitutive model and complete stressestrain models under compressive and shear conditions were also developed as the derivatives of the SMRM theory.An SMRM calculation system was then developed to provide fast and precise solutions for parameter estimations of rock masses,such as full-direction rock quality designation(RQD),elastic modulus,Coulomb compressive strength,rock mass quality rating,and Poisson’s ratio and shear strength.The constitutive equations involved in SMRM were integrated into a FLAC3D based numerical module to apply for engineering rock masses.It is also capable of analysing the complete deformation of rock masses and active reinforcement of engineering rock masses.Examples of engineering applications of SMRM were presented,including a rock mass at QBT hydropower station in northwestern China,a dam slope of Zongo II hydropower station in D.R.Congo,an open-pit mine in Dexing,China,an underground powerhouse of Jinping I hydropower station in southwestern China,and a typical circular tunnel in Lanzhou-Chongqing railway,China.These applications verified the reliability of the SMRM and demonstrated its applicability to broad engineering issues associated with jointed rock masses.展开更多
Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics re...Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.展开更多
BACKGROUND Colonoscopy quality relies heavily on adequate bowel preparation,yet traditional methods often result in suboptimal compliance.Emerging network-based monitoring systems offer promise for improving both prep...BACKGROUND Colonoscopy quality relies heavily on adequate bowel preparation,yet traditional methods often result in suboptimal compliance.Emerging network-based monitoring systems offer promise for improving both preparation quality and patient cooperation,potentially enhancing clinical outcomes.AIM To evaluate the effectiveness of an intestinal network monitoring system in enhancing the quality of bowel preparation for colonoscopy and its impact on patient psychological and physiological responses,compliance,and adverse event rates.METHODS Between July 2019 and July 2020,800 enteroscopy patients who met the inclusion criteria in the outpatient clinic of the gastroenterology department of our hospital were randomly divided into 400 cases each in the experimental group(network monitoring group)and the control group(verbal+written preaching group),and the psychological and physiological stress response situation,colon Boston Bowel Preparation Scale,enteroscopy to blindness,arrival time to blindness,and polyp detection rate of the patients were compared before and after the intervention,compliance and adverse reactions were compared.RESULTS There was no difference in anxiety and depression scores,heart rate and systolic blood pressure between the groups before the intervention(P>0.05),and after the intervention,the patients’anxiety and depression scores were lower and lower in the study group(P<0.05);heart rate and systolic blood pressure were elevated,but lower in the test group(P<0.05).The left hemicolon,right hemicolon,transverse colon and total Boston Bowel Preparation Scale scores were lower in the test group than in the control group(P<0.05),the colonoscopy arrival rate and polyp detection rate were higher than those in the control group,and the time to arrival and time to exit the scope were shorter than those in the control group(P<0.05),and the dietary preparations,the preparations for taking medications and the total adherence scores were higher than those in the control group(P<0.05).The incidence of adverse reactions in the experimental group was 11.00%,which was lower than that in the control group(P<0.05).CONCLUSION The Bowel Network Monitoring System has potential clinical promotion value in improving the quality of colonoscopic bowel preparation,which can effectively alleviate patient anxiety and depression,improve the quality of colonoscopic bowel preparation and patient compliance,and has a high degree of safety.展开更多
针对现有取苗末端执行器取苗针间距固定、适应性差,难以实现按需调整以适应移栽过程中不同规格穴盘钵苗取苗的问题,设计了一种插入针间距可调的针式取苗末端执行器。该执行器由直流电动推杆驱动,取苗针沿根钵四角倾斜插入。通过调整调...针对现有取苗末端执行器取苗针间距固定、适应性差,难以实现按需调整以适应移栽过程中不同规格穴盘钵苗取苗的问题,设计了一种插入针间距可调的针式取苗末端执行器。该执行器由直流电动推杆驱动,取苗针沿根钵四角倾斜插入。通过调整调节滑块和针座在支架上的位置,实现取苗针间距的调整。本文以72穴、128穴和200穴3种规格甘蓝穴盘所育钵苗为研究对象,研究了3种规格穴盘钵苗苗龄对根钵形成与甘蓝幼苗生长发育的影响,确定了取苗末端执行器主要结构参数,并对取苗瞬间进行了受力分析。在根钵均已形成的前提下,运用EDEM对根钵提取进行单因素仿真模拟,以穴盘规格、取苗加速度、取苗针插入边距比和根钵含水率为试验因素,根钵完整率和取苗失败率为评价指标,采用L9(3^4)正交试验,考察试验因素对评价指标的影响,通过极差分析、方差分析和综合加权法,得到各因素对评价指标影响的主次顺序为取苗加速度、根钵含水率、穴盘规格、插入比;得到优选参数组合:取苗加速度为0.1 m/s 2,根钵含水率为56.2%,穴盘规格为128穴,插入边距比为15%,此时根钵完整率为97.93%,取苗失败率为0.81%。展开更多
基金The authors are grateful to the financial support from the National Natural Science Foundation of China(Grant No.41831290)the Key R&D Project from Zhejiang Province,China(Grant No.2020C03092).
文摘To efficiently link the continuum mechanics for rocks with the structural statistics of rock masses,a theoretical and methodological system called the statistical mechanics of rock masses(SMRM)was developed in the past three decades.In SMRM,equivalent continuum models of stressestrain relationship,strength and failure probability for jointed rock masses were established,which were based on the geometric probability models characterising the rock mass structure.This follows the statistical physics,the continuum mechanics,the fracture mechanics and the weakest link hypothesis.A general constitutive model and complete stressestrain models under compressive and shear conditions were also developed as the derivatives of the SMRM theory.An SMRM calculation system was then developed to provide fast and precise solutions for parameter estimations of rock masses,such as full-direction rock quality designation(RQD),elastic modulus,Coulomb compressive strength,rock mass quality rating,and Poisson’s ratio and shear strength.The constitutive equations involved in SMRM were integrated into a FLAC3D based numerical module to apply for engineering rock masses.It is also capable of analysing the complete deformation of rock masses and active reinforcement of engineering rock masses.Examples of engineering applications of SMRM were presented,including a rock mass at QBT hydropower station in northwestern China,a dam slope of Zongo II hydropower station in D.R.Congo,an open-pit mine in Dexing,China,an underground powerhouse of Jinping I hydropower station in southwestern China,and a typical circular tunnel in Lanzhou-Chongqing railway,China.These applications verified the reliability of the SMRM and demonstrated its applicability to broad engineering issues associated with jointed rock masses.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0904)the National Natural Science Foundation of China(Grant No.42402277)the Fundamental Research Funds for the Central Universities(Grant No.300102264902).
文摘Intact rocks with layered microstructures,such as gneiss,exhibit strong anisotropy.Although anisotropy in the macroscopic strength of gneiss has been widely reported,the role of microstructures in tensile mechanics remains largely unclear.Utilizing a range of methodologies,it was determined that the tensile strength,deformation,and fracturing behavior of Himalayan gneiss are predominantly influenced by biotite.In contrast to the behavior of other transversely isotropic rocks,the apparent tensile strength of the gneiss first decreased and then increased with anisotropic angleβ,rather than the widely reported monotonic increase or single-shoulder response.The shear sliding of biotite along cleavage planes caused stress concentrations in the surrounding brittle minerals,inducing cracks and reducing the overall tensile strength of the gneiss.Micro-observations of the relationship between cracks and biotite orientation identified three types of biotite crystal fragmentation:tensile fragmentation along cleavage planes,shear fragmentation along cleavage planes,and tensile fragmentation perpendicular to cleavage planes.Tensile and shear fragmentation of biotite along cleavage planes negatively affected the gneiss'macroscopic tensile strength.Conversely,when the tensile stress was parallel to the biotite cleavage planes,tensile fragmentation perpendicular to the cleavage planes increased the macroscopic tensile strength of the gneiss due to plastic deformation and high surface energy.Quantitative analysis of shear stress along biotite cleavage planes revealed the mechanical mechanism behind the reduced tensile strength of the East Himalayan gneisses near an anisotropic angle of 30°.These results elucidated the influence of grain-level anisotropy on the macroscopic tensile mechanical properties of intact layered rocks.
基金Supported by the Changshu Municipal Health Commission Science and Technology Program,No.csws201902。
文摘BACKGROUND Colonoscopy quality relies heavily on adequate bowel preparation,yet traditional methods often result in suboptimal compliance.Emerging network-based monitoring systems offer promise for improving both preparation quality and patient cooperation,potentially enhancing clinical outcomes.AIM To evaluate the effectiveness of an intestinal network monitoring system in enhancing the quality of bowel preparation for colonoscopy and its impact on patient psychological and physiological responses,compliance,and adverse event rates.METHODS Between July 2019 and July 2020,800 enteroscopy patients who met the inclusion criteria in the outpatient clinic of the gastroenterology department of our hospital were randomly divided into 400 cases each in the experimental group(network monitoring group)and the control group(verbal+written preaching group),and the psychological and physiological stress response situation,colon Boston Bowel Preparation Scale,enteroscopy to blindness,arrival time to blindness,and polyp detection rate of the patients were compared before and after the intervention,compliance and adverse reactions were compared.RESULTS There was no difference in anxiety and depression scores,heart rate and systolic blood pressure between the groups before the intervention(P>0.05),and after the intervention,the patients’anxiety and depression scores were lower and lower in the study group(P<0.05);heart rate and systolic blood pressure were elevated,but lower in the test group(P<0.05).The left hemicolon,right hemicolon,transverse colon and total Boston Bowel Preparation Scale scores were lower in the test group than in the control group(P<0.05),the colonoscopy arrival rate and polyp detection rate were higher than those in the control group,and the time to arrival and time to exit the scope were shorter than those in the control group(P<0.05),and the dietary preparations,the preparations for taking medications and the total adherence scores were higher than those in the control group(P<0.05).The incidence of adverse reactions in the experimental group was 11.00%,which was lower than that in the control group(P<0.05).CONCLUSION The Bowel Network Monitoring System has potential clinical promotion value in improving the quality of colonoscopic bowel preparation,which can effectively alleviate patient anxiety and depression,improve the quality of colonoscopic bowel preparation and patient compliance,and has a high degree of safety.
文摘针对现有取苗末端执行器取苗针间距固定、适应性差,难以实现按需调整以适应移栽过程中不同规格穴盘钵苗取苗的问题,设计了一种插入针间距可调的针式取苗末端执行器。该执行器由直流电动推杆驱动,取苗针沿根钵四角倾斜插入。通过调整调节滑块和针座在支架上的位置,实现取苗针间距的调整。本文以72穴、128穴和200穴3种规格甘蓝穴盘所育钵苗为研究对象,研究了3种规格穴盘钵苗苗龄对根钵形成与甘蓝幼苗生长发育的影响,确定了取苗末端执行器主要结构参数,并对取苗瞬间进行了受力分析。在根钵均已形成的前提下,运用EDEM对根钵提取进行单因素仿真模拟,以穴盘规格、取苗加速度、取苗针插入边距比和根钵含水率为试验因素,根钵完整率和取苗失败率为评价指标,采用L9(3^4)正交试验,考察试验因素对评价指标的影响,通过极差分析、方差分析和综合加权法,得到各因素对评价指标影响的主次顺序为取苗加速度、根钵含水率、穴盘规格、插入比;得到优选参数组合:取苗加速度为0.1 m/s 2,根钵含水率为56.2%,穴盘规格为128穴,插入边距比为15%,此时根钵完整率为97.93%,取苗失败率为0.81%。
