The Qiangsheng gold deposit belongs to quartz vein type. The fluid inclusions consist of four types： aqueous single-phase inclusions, aqueous two-phase inclusions, carbonated two-phase inclusions and carbona- ted thr...The Qiangsheng gold deposit belongs to quartz vein type. The fluid inclusions consist of four types： aqueous single-phase inclusions, aqueous two-phase inclusions, carbonated two-phase inclusions and carbona- ted three-phase inclusions. The fluid inclusions are characterized by low salinity （5%-9% NaCl eqv） , low density （0.66-0.72 g/cm^3 ） and medium temperature （210℃-250℃）. The pressure of ore-forming is 60-95 MPa and the metallogenic depth is about 5.49-7.56 km. During the mineralizing process, ore-forming fluid under- went fluid unmixing in CO2-H2O-NaCl system. The stable isotope resuhs indicate that the ore-forming fluids mainly generated from mantle, with the participation of a small amount of atmospheric water. Comprehensive studies have suggested that Qiangsheng gold deposit belongs to the type of mesothermal hydrotherm with mantlederived fluid participating in mineralization.展开更多
With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even elimina...With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.展开更多
公有链无集中控制节点、去中心化和允许任意节点加入的特点使其拥有高效、低成本和高数据安全性的优势,但由于其允许任意节点接入,因此将增加公有链网络的脆弱性。基于Client Puzzle,提出一种节点接入控制模型CPACM(Client Puzzle based...公有链无集中控制节点、去中心化和允许任意节点加入的特点使其拥有高效、低成本和高数据安全性的优势,但由于其允许任意节点接入,因此将增加公有链网络的脆弱性。基于Client Puzzle,提出一种节点接入控制模型CPACM(Client Puzzle based Access Control Model),使新节点接入公有链前利用算力进行工作量证明,完成工作量证明后才可接入公有链。该模型在维持公有链去中心化的同时,增加了接入控制。实验证明,该模型在不影响诚实节点加入的情况下,能以较高成功率限制低诚意节点和低算力节点的加入,并且能防止节点间的伙同,防范了恶意行为,提高了公有链网络的安全性。展开更多
Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simpli...Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics （CFD）-fluid structure interaction （FSI） techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ＂dynamic mesh＂ technique. A new mesh movement approacb is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the joumal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function （UDF）. The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.展开更多
Traditional vegetation techniques for the control of concentrated flow erosion are widely recognized, whereas only a few studies have experimentally investigated the impacts of belowground roots on the erodibility of ...Traditional vegetation techniques for the control of concentrated flow erosion are widely recognized, whereas only a few studies have experimentally investigated the impacts of belowground roots on the erodibility of topsoils in semi-arid areas. To quantify the effects of root architectures on soil erodibility and its relevant structural properties, simulated flow experiments were conducted at six-week intervals from 18 July to 20 October in 2012 in the hilly Loess Plateau. Five treatments were: 1) bare(control), 2) purple alfalfa(Medicago sativa), representing tap roots(T), 3) switchgrass(Panicum virgatum), representing fibrous roots(F), 4) purple alfalfa and switchgrass, representing both tap and fibrous roots(T + F), and 5) natural recovery(N). For each treatment, soil structural properties and root characteristics were measured at an interval of six weeks. Soil anti-scouribility was calculated. Results showed that grass planting slightly reduced soil bulk density, but increased soil aggregate content by 19.1%, 10.6%, 28.5%, and 41.2% in the treatments T, F, T + F, and N, respectively. Soil shear strength(cohesion and angle of internal friction(φ)) significantly increased after the grass was planted. As roots grew, soil cohesion increased by 115.2%–135.5%, while soil disintegration rate decreased by 39.0%–58.1% in the 21 th week compared with the recorded value in the 9th week. Meanwhile, root density and root surface area density increased by 64.0%–104.7% and 75.9%–157.1%, respectively. No significant differences in soil anti-scouribility were observed between the treatments of T and F or of T + F and N, but the treatments of T + F and N performed more effectively than T or F treatment alone in retarding concentrated flow. Soil aggregation and root surface-area density explained the observed soil anti-scouribility during concentrated flow well for the different treatments. This result proved that the restoration of natural vegetation might be the most appropriate strategy in soil reinforcement in the hilly Loess Plateau.展开更多
Objective To study the effectiveness of waist circumference cut-off values in predicting the prevalence of metabolic syndrome （MetS） and risk factors in adults in China. Methods A cross-sectional survey was condcute...Objective To study the effectiveness of waist circumference cut-off values in predicting the prevalence of metabolic syndrome （MetS） and risk factors in adults in China. Methods A cross-sectional survey was condcuted in 14 provinces （autonomous region, municipality） in China. A total of 47 325 adults aged 〉20 years were selected by multistage stratified sampling, and questionnaire survey and physical and clinical examination were conducted among them. MetS was defined according to the International Diabetes Federation （IDF） criteria and modified IDF criteria.Results The age-standardized prevalence of MetS was 24.2% （22.1% in men and 25.8% in women） and 19.5% （22.1% in men and 18.0% in women} according to the IDF criteria and modified IDF criteria respectively. The age-standardized prevalence of pre-MetS was 8.1% （8.6% in men and 7.8% in women） according to the modified IDF criteria. The prevalence of MetS was higher in urban residents than rural residents and in northern China residents than in southern China residents. The prevalence of central obesity was about 30% in both men and women according to the ethnicity-specific cut-off values of waist circumference for central obesity （90 cm for men and 85 cm for women）. Multivariate regression analysis revealed no significant difference in risk factors between the two MetS definitions. Conclusion Using both the modified IDF criteria and ethnicity-specific cut-off values of waist circumference can provide more useful information about the prevalence of MetS in China.展开更多
基金Supported by projects of Geological Exploration of Jilin Province(No.22201300111)Shanhou Gold Deposit of Laixi of Shandong Province(SDLX2012-3-28)
文摘The Qiangsheng gold deposit belongs to quartz vein type. The fluid inclusions consist of four types： aqueous single-phase inclusions, aqueous two-phase inclusions, carbonated two-phase inclusions and carbona- ted three-phase inclusions. The fluid inclusions are characterized by low salinity （5%-9% NaCl eqv） , low density （0.66-0.72 g/cm^3 ） and medium temperature （210℃-250℃）. The pressure of ore-forming is 60-95 MPa and the metallogenic depth is about 5.49-7.56 km. During the mineralizing process, ore-forming fluid under- went fluid unmixing in CO2-H2O-NaCl system. The stable isotope resuhs indicate that the ore-forming fluids mainly generated from mantle, with the participation of a small amount of atmospheric water. Comprehensive studies have suggested that Qiangsheng gold deposit belongs to the type of mesothermal hydrotherm with mantlederived fluid participating in mineralization.
文摘With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.
文摘公有链无集中控制节点、去中心化和允许任意节点加入的特点使其拥有高效、低成本和高数据安全性的优势,但由于其允许任意节点接入,因此将增加公有链网络的脆弱性。基于Client Puzzle,提出一种节点接入控制模型CPACM(Client Puzzle based Access Control Model),使新节点接入公有链前利用算力进行工作量证明,完成工作量证明后才可接入公有链。该模型在维持公有链去中心化的同时,增加了接入控制。实验证明,该模型在不影响诚实节点加入的情况下,能以较高成功率限制低诚意节点和低算力节点的加入,并且能防止节点间的伙同,防范了恶意行为,提高了公有链网络的安全性。
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA04Z413)Zhejiang Provincial Natural Science Foundation of China (Grant No. Y1110109)
文摘Journal bearings are important parts to keep the high dynamic performance of rotor machinery. Some methods have already been proposed to analysis the flow field of journal bearings, and in most of these methods simplified physical model and classic Reynolds equation are always applied. While the application of the general computational fluid dynamics （CFD）-fluid structure interaction （FSI） techniques is more beneficial for analysis of the fluid field in a journal bearing when more detailed solutions are needed. This paper deals with the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearings and rotor dynamics with CFD-FSI techniques. The fluid dynamics of oil film is calculated by applying the so-called ＂dynamic mesh＂ technique. A new mesh movement approacb is presented while the dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The proposed mesh movement approach is based on the structured mesh. When the joumal moves, the movement distance of every grid in the flow field of bearing can be calculated, and then the update of the volume mesh can be handled automatically by user defined function （UDF）. The journal displacement at each time step is obtained by solving the moving equations of the rotor-bearing system under the known oil film force condition. A case study is carried out to calculate the locus of the journal center and pressure distribution of the journal in order to prove the feasibility of this method. The calculating results indicate that the proposed method can predict the transient flow field of a journal bearing in a rotor-bearing system where more realistic models are involved. The presented calculation method provides a basis for studying the nonlinear dynamic behavior of a general rotor-bearing system.
基金Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues of Chinese Academy of Sciences(No.XDA05060300)
文摘Traditional vegetation techniques for the control of concentrated flow erosion are widely recognized, whereas only a few studies have experimentally investigated the impacts of belowground roots on the erodibility of topsoils in semi-arid areas. To quantify the effects of root architectures on soil erodibility and its relevant structural properties, simulated flow experiments were conducted at six-week intervals from 18 July to 20 October in 2012 in the hilly Loess Plateau. Five treatments were: 1) bare(control), 2) purple alfalfa(Medicago sativa), representing tap roots(T), 3) switchgrass(Panicum virgatum), representing fibrous roots(F), 4) purple alfalfa and switchgrass, representing both tap and fibrous roots(T + F), and 5) natural recovery(N). For each treatment, soil structural properties and root characteristics were measured at an interval of six weeks. Soil anti-scouribility was calculated. Results showed that grass planting slightly reduced soil bulk density, but increased soil aggregate content by 19.1%, 10.6%, 28.5%, and 41.2% in the treatments T, F, T + F, and N, respectively. Soil shear strength(cohesion and angle of internal friction(φ)) significantly increased after the grass was planted. As roots grew, soil cohesion increased by 115.2%–135.5%, while soil disintegration rate decreased by 39.0%–58.1% in the 21 th week compared with the recorded value in the 9th week. Meanwhile, root density and root surface area density increased by 64.0%–104.7% and 75.9%–157.1%, respectively. No significant differences in soil anti-scouribility were observed between the treatments of T and F or of T + F and N, but the treatments of T + F and N performed more effectively than T or F treatment alone in retarding concentrated flow. Soil aggregation and root surface-area density explained the observed soil anti-scouribility during concentrated flow well for the different treatments. This result proved that the restoration of natural vegetation might be the most appropriate strategy in soil reinforcement in the hilly Loess Plateau.
基金supported by grants from the Chinese Medical Association Foundation and Chinese Diabetes Society
文摘Objective To study the effectiveness of waist circumference cut-off values in predicting the prevalence of metabolic syndrome （MetS） and risk factors in adults in China. Methods A cross-sectional survey was condcuted in 14 provinces （autonomous region, municipality） in China. A total of 47 325 adults aged 〉20 years were selected by multistage stratified sampling, and questionnaire survey and physical and clinical examination were conducted among them. MetS was defined according to the International Diabetes Federation （IDF） criteria and modified IDF criteria.Results The age-standardized prevalence of MetS was 24.2% （22.1% in men and 25.8% in women） and 19.5% （22.1% in men and 18.0% in women} according to the IDF criteria and modified IDF criteria respectively. The age-standardized prevalence of pre-MetS was 8.1% （8.6% in men and 7.8% in women） according to the modified IDF criteria. The prevalence of MetS was higher in urban residents than rural residents and in northern China residents than in southern China residents. The prevalence of central obesity was about 30% in both men and women according to the ethnicity-specific cut-off values of waist circumference for central obesity （90 cm for men and 85 cm for women）. Multivariate regression analysis revealed no significant difference in risk factors between the two MetS definitions. Conclusion Using both the modified IDF criteria and ethnicity-specific cut-off values of waist circumference can provide more useful information about the prevalence of MetS in China.
