Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present ...Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.展开更多
This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined u...This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined using Vic-3D non-contact three-dimensional digital optical system.The evolution of inhomogeneous strain fields on the surface of composite specimens of the structure under study has been analyzed.The variants of strain averaging in the specimen working area have been analyzed using Vic-3D tools.AMSY-6 acoustic emission system has been used to assess the structural integrity of composite materials under loading.展开更多
In this study the medium-term response of beach profiles was investigated at two sites： a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the ea...In this study the medium-term response of beach profiles was investigated at two sites： a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the east coast of the USA, which is exposed to Atlantic Ocean swells and storm waves, and the latter is the Milford-on-Sea site at Christchurch Bay, on the south coast of England, which is partially sheltered from Atlantic swells but has a directionally bimodal wave exposure. The data sets comprise detailed bathymetric surveys of beach profiles covering a period of more than 25 years for the Duck site and over 18 years for the Milford-on-Sea site. The structure of the data sets and the data-driven methods are described. Canonical correlation analysis （CCA） was used to find linkages between the wave characteristics and beach profiles. The sensitivity of the linkages was investigated by deploying a wave height threshold to filter out the smaller waves incrementally. The results of the analysis indicate that, for the gently sloping sandy beach, waves of all heights are important to the morphological response. For the mixed sand and gravel beach, filtering the smaller waves improves the statistical fit and it suggests that low-height waves do not play a primary role in the medium-term morohological resoonse, which is primarily driven by the intermittent larger storm waves.展开更多
For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic...For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.展开更多
Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-eve...Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-event basis.It is shown that the initial-state fluctuations may give rise to bumpy structures of the medium during hydrodynamical evolution,which affects the two-pion emission space and leads to a visible two-tiered shape in the source function imaged using the two-pion Bose–Einstein correlations.This two-tiered shape can be understood within a similar but more analytic granular source model and is found to be closely related to the introduced quantity n,which characterizes the granular inhomogeneity of the source.By fitting the imaged source function with a granular source parametrization,we extract the granular inhomogeneity of the hydrodynamic source,which is found to be sensitive to both the Gaussian smearing width of the HIJING initial condition and the centrality of the collisions.展开更多
Machine-type communication (MTC) devices provide a broad range of data collection especially on the massive data generated environments such as urban, industrials and event-enabled areas. In dense deployments, the dat...Machine-type communication (MTC) devices provide a broad range of data collection especially on the massive data generated environments such as urban, industrials and event-enabled areas. In dense deployments, the data collected at the closest locations between the MTC devices are spatially correlated. In this paper, we propose a k-means grouping technique to combine all MTC devices based on spatially correlated. The MTC devices collect the data on the event-based area and then transmit to the centralized aggregator for processing and computing. With the limitation of computational resources at the centralized aggregator, some grouped MTC devices data offloaded to the nearby base station collocated with the mobile edge-computing server. As a sensing capability adopted on MTC devices, we use a power exponential function model to compute a correlation coefficient existing between the MTC devices. Based on this framework, we compare the energy consumption when all data processed locally at centralized aggregator or offloaded at mobile edge computing server with optimal solution obtained by the brute force method. Then, the simulation results revealed that the proposed k-means grouping technique reduce the energy consumption at centralized aggregator while satisfying the required completion time.展开更多
Differential evolution algorithm based on the covariance matrix learning can adjust the coordinate system according to the characteristics of the population, which make<span style="font-family:Verdana;"&g...Differential evolution algorithm based on the covariance matrix learning can adjust the coordinate system according to the characteristics of the population, which make<span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> the search move in a more favorable direction. In order to obtain more accurate information about the function shape, this paper propose</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""> <span style="font-family:Verdana;">covariance</span><span style="font-family:Verdana;"> matrix learning differential evolution algorithm based on correlation (denoted as RCLDE)</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">to improve the search efficiency of the algorithm. First, a hybrid mutation strategy is designed to balance the diversity and convergence of the population;secondly, the covariance learning matrix is constructed by selecting the individual with the less correlation;then, a comprehensive learning mechanism is comprehensively designed by two covariance matrix learning mechanisms based on the principle of probability. Finally,</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">the algorithm is tested on the CEC2005, and the experimental results are compared with other effective differential evolution algorithms. The experimental results show that the algorithm proposed in this paper is </span><span style="font-family:Verdana;">an effective algorithm</span><span style="font-family:Verdana;">.</span></span>展开更多
Productivity is a very important element in the process of construction project management especially with regard to the estimation of the duration of the construction activities, this study aims at developing constru...Productivity is a very important element in the process of construction project management especially with regard to the estimation of the duration of the construction activities, this study aims at developing construction productivity estimating model for marble finishing works of floors using Multivariable Linear Regression technique (MLR). The model was developed based on 100 set of data collected in Iraq for different types of projects such as residential, commercial and educational projects. Which these are used in developing the model and evaluating its performance. Ten influencing factors are utilized for productivity forecasting by MLR model, and they include age, experience, number of the assist labor, height of the floor, size of the marbles tiles, security conditions, health status for the work team, weather conditions, site condition, and availability of construction materials. One model was built for the prediction of the productivity of marble finishing works for floors. It was found that MLR have the ability to predict the productivity for finishing works with excellent degree of accuracy of the coefficient of correlation (R) 90.6%, and average accuracy percentage of 96.3%. This indicates that the relationship between the independent and independent variables of the developed models is good and the predicted values from a forecast model fit with the real-life data.展开更多
The reformation of the economy system has led the functional departments and status of the enterprises into the variance state. Under the condition of the market economy, the kernel of the enterprises＇ functional dep...The reformation of the economy system has led the functional departments and status of the enterprises into the variance state. Under the condition of the market economy, the kernel of the enterprises＇ functional department has diverted to that of marketing decision-making, which faces to market and meets with the need of consumption. Assuredly, the kernel of marketing decision-making is to prognosticate the future market requirement quantity of the production of enterprises accurately, so that it can ensure and realize the maximum of the enterprises＇ profit to increase. Applying the proof to test demonstration analytical method of economics and adopting the multi-regression technique, this paper analyzes the enterprises＇ production requirement quantity decision-making of the GMC （Global Management Challenge） and changes a great many of uncontrollable factors to the controllable ones of the enterprises. So, it can make the forecast order form closer to the actual prices of the future market requirement quantity in the production marketing decision-making of the enterprises and realize the optimizing combination and the working object with the minimum of the cost and the maximum of the profit. And it can insure the realization of the profit increase of the enterorises mostly in the life-cvcle of the production.展开更多
We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to genera...We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion.The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method.We also perform the effective equivalent storage and subdomain techniques in the starting model calculation,the forward modeling and the inversion procedures,which allow fast computation in space domain with reducing memory consumption but maintaining accuracy.The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data.The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km,which may be originated from hot anomalies in the lower crust.The results show that our inversion method is useful for 3D quantitative interpretation.展开更多
For two odd integers m and s with 1≤s < m and gcd(m, s) = 1, let h satisfy h(2~s-1) ≡1(mod 2~m+ 1) and d =(h + 1)(2~m-1) + 1. The cross correlation function between a binary m-sequence of period 22~m-1 and its d-...For two odd integers m and s with 1≤s < m and gcd(m, s) = 1, let h satisfy h(2~s-1) ≡1(mod 2~m+ 1) and d =(h + 1)(2~m-1) + 1. The cross correlation function between a binary m-sequence of period 22~m-1 and its d-decimation sequence is proved to take four values, and the correlation distribution is completely determined. Let n be an even integer and k be an integer with 1≤k≤n/2. For an odd prime p and a p-ary m-sequence {s(t)} of period p^n-1, define u(t) =∑(p^k-1)/2 i=0 s(d_it), where d_i = ip^(n/2) + p^k-i and i = 0, 1,...,(p^k-1)/2. It is proved that the cross correlation function between {u(t)} and {s(t)} is three-valued or four-valued depending on whether k is equal to n/2 or not, and the distribution is also determined.展开更多
目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医...目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医院健康管理中心接受体格检查的1152名中老年男性体检者为研究对象,采集受试者年龄、身高、体重、血压、腰围、臀围、体脂肪质量与体肌肉质量数据,并计算体质量指数(body mass index,BMI)、体脂率(body fat percentage,BFP)与骨骼肌质量指数(skeletal muscle mass index,SMI)。同时使用QCT技术测量受试者腰椎BMD值,按照BMI进行分组,分为BMI正常组(18.5≤BMI<24 kg/m^(2))、超重及肥胖组(BMI为>24 kg/m^(2)),并在两组中分别按照骨量诊断标准进行讨论。采用单因素方差分析,Pearson相关性分析和偏相关分析体格测量、体成分分析指标与腰椎BMD的相关性。结果在BMI正常组中,骨质疏松组的年龄、收缩压、腰臀比、BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05);超重及肥胖组中,骨质疏松组的年龄、收缩压、腰围、腰臀比与BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05)。Pearson相关性分析结果显示,BMI正常组中腰椎BMD值与年龄、腰围、腰臀比、BFP呈显著负相关关系(r=-0.385,r=-0.122,r=-0.199,r=-0.168,P均<0.05),与SMI呈正相关(r=0.226,P<0.05);超重及肥胖组中腰椎BMD值与年龄、收缩压、腰围、腰臀比、BFP呈显著负相关关系(r=-0.379,r=-0.087,r=-0.101,r=-0.187,r=-0.199,P均<0.05),与SMI呈正相关(r=0.251,P<0.05)。在校正年龄因素后,偏相关分析分析结果显示,BMI正常组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.157,r=-0.212,r=-0.134,P均<0.05),与SMI呈正相关(r=0.167,P<0.05);超重及肥胖组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.120,r=-0.163,r=-0.126,P均<0.05),与SMI呈正相关(r=0.159,P<0.05)。结论腰围、腰臀比、BFP、SMI与中老年男性体检人群腰椎BMD值密切相关,对肥胖和骨质疏松症的预防与管理具有一定临床价值。展开更多
MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试...MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试验,利用数字图像相关技术获取了拉伸过程中试样表面应变场演化;然后,采用场发射扫描电子显微镜分析了拉伸断裂机理;最后,通过二值化量化了补焊对轫脆转变的影响。研究结果表明:补焊试样中存在明显的二次熔合线,多次的热输入导致树枝状铁素体增多;补焊试样焊缝根部由于补焊坡口较小,其硬度总体偏高,焊缝顶端铁素体发生重结晶,其焊缝硬度高于热影响区;受补焊影响,补焊及外部区域焊缝试样在拉伸过程中具有较大的局部应变,其中,补焊试样抗拉强度增大,屈服强度减小,在3种试样中屈强比最低,具有较好的塑性;与其他试样不同,由于焊缝根部性能减弱,补焊外部区域试样整体拉伸性能最弱,且由于晶界结合力减弱,表现出脆性断裂特征。展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)the Ministry of Education, Science and Technology (Grant number: 2009-0083068)
文摘Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.
基金the Russian Foundation for Basic Research within the Projects(Grants 19-31-90148 and 18-01-00763)The experimental studies of shear material properties were conducted within the State Assignment of the Ministry of Education and Science of the Russian Federation(9.7529.2017/9.10).
文摘This work is dedicated to the experimental study of the shear properties of three-dimensional reinforced composites taking into account their structural features,in Iosipescu tests.Shear strains have been determined using Vic-3D non-contact three-dimensional digital optical system.The evolution of inhomogeneous strain fields on the surface of composite specimens of the structure under study has been analyzed.The variants of strain averaging in the specimen working area have been analyzed using Vic-3D tools.AMSY-6 acoustic emission system has been used to assess the structural integrity of composite materials under loading.
基金supported by the UK Natural Environment Research Council(Grant No.NE/J005606/1)the UK Engineering and Physical Sciences Research Council(Grant No.EP/C005392/1)the Ensemble Estimation of Flood Risk in a Changing Climate(EFRa CC)project funded by the British Council under its Global Innovation Initiative
文摘In this study the medium-term response of beach profiles was investigated at two sites： a gently sloping sandy beach and a steeper mixed sand and gravel beach. The former is the Duck site in North Carolina, on the east coast of the USA, which is exposed to Atlantic Ocean swells and storm waves, and the latter is the Milford-on-Sea site at Christchurch Bay, on the south coast of England, which is partially sheltered from Atlantic swells but has a directionally bimodal wave exposure. The data sets comprise detailed bathymetric surveys of beach profiles covering a period of more than 25 years for the Duck site and over 18 years for the Milford-on-Sea site. The structure of the data sets and the data-driven methods are described. Canonical correlation analysis （CCA） was used to find linkages between the wave characteristics and beach profiles. The sensitivity of the linkages was investigated by deploying a wave height threshold to filter out the smaller waves incrementally. The results of the analysis indicate that, for the gently sloping sandy beach, waves of all heights are important to the morphological response. For the mixed sand and gravel beach, filtering the smaller waves improves the statistical fit and it suggests that low-height waves do not play a primary role in the medium-term morohological resoonse, which is primarily driven by the intermittent larger storm waves.
基金Project(51004005) supported by the National Natural Science Foundation of ChinaProject supported by Open Research Fund Program of Beijing Engineering Research Center of Monitoring for Construction Safety (Beijing University of Civil Engineering and Architecture), China
文摘For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.
基金the Research Start-up Funding of Hubei University of Education(No.201801)Hubei Provincial Natural Science Foundation of China(No.2020CFB697)+1 种基金the China Postdoctoral Science Foundation(No.2019M652929)the MOE Key Laboratory of Quark and Lepton Physics(Central China Normal University)(No.QLPL201802).
文摘Using the source imaging technique in two-pion interferometry,we study the image of the hydrodynamic particle-emitting source with the HIJING initial conditions for relativistic heavy-ion collisions on an event-by-event basis.It is shown that the initial-state fluctuations may give rise to bumpy structures of the medium during hydrodynamical evolution,which affects the two-pion emission space and leads to a visible two-tiered shape in the source function imaged using the two-pion Bose–Einstein correlations.This two-tiered shape can be understood within a similar but more analytic granular source model and is found to be closely related to the introduced quantity n,which characterizes the granular inhomogeneity of the source.By fitting the imaged source function with a granular source parametrization,we extract the granular inhomogeneity of the hydrodynamic source,which is found to be sensitive to both the Gaussian smearing width of the HIJING initial condition and the centrality of the collisions.
文摘Machine-type communication (MTC) devices provide a broad range of data collection especially on the massive data generated environments such as urban, industrials and event-enabled areas. In dense deployments, the data collected at the closest locations between the MTC devices are spatially correlated. In this paper, we propose a k-means grouping technique to combine all MTC devices based on spatially correlated. The MTC devices collect the data on the event-based area and then transmit to the centralized aggregator for processing and computing. With the limitation of computational resources at the centralized aggregator, some grouped MTC devices data offloaded to the nearby base station collocated with the mobile edge-computing server. As a sensing capability adopted on MTC devices, we use a power exponential function model to compute a correlation coefficient existing between the MTC devices. Based on this framework, we compare the energy consumption when all data processed locally at centralized aggregator or offloaded at mobile edge computing server with optimal solution obtained by the brute force method. Then, the simulation results revealed that the proposed k-means grouping technique reduce the energy consumption at centralized aggregator while satisfying the required completion time.
文摘Differential evolution algorithm based on the covariance matrix learning can adjust the coordinate system according to the characteristics of the population, which make<span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> the search move in a more favorable direction. In order to obtain more accurate information about the function shape, this paper propose</span><span style="font-family:Verdana;">s</span><span style="font-family:;" "=""> <span style="font-family:Verdana;">covariance</span><span style="font-family:Verdana;"> matrix learning differential evolution algorithm based on correlation (denoted as RCLDE)</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">to improve the search efficiency of the algorithm. First, a hybrid mutation strategy is designed to balance the diversity and convergence of the population;secondly, the covariance learning matrix is constructed by selecting the individual with the less correlation;then, a comprehensive learning mechanism is comprehensively designed by two covariance matrix learning mechanisms based on the principle of probability. Finally,</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">the algorithm is tested on the CEC2005, and the experimental results are compared with other effective differential evolution algorithms. The experimental results show that the algorithm proposed in this paper is </span><span style="font-family:Verdana;">an effective algorithm</span><span style="font-family:Verdana;">.</span></span>
文摘Productivity is a very important element in the process of construction project management especially with regard to the estimation of the duration of the construction activities, this study aims at developing construction productivity estimating model for marble finishing works of floors using Multivariable Linear Regression technique (MLR). The model was developed based on 100 set of data collected in Iraq for different types of projects such as residential, commercial and educational projects. Which these are used in developing the model and evaluating its performance. Ten influencing factors are utilized for productivity forecasting by MLR model, and they include age, experience, number of the assist labor, height of the floor, size of the marbles tiles, security conditions, health status for the work team, weather conditions, site condition, and availability of construction materials. One model was built for the prediction of the productivity of marble finishing works for floors. It was found that MLR have the ability to predict the productivity for finishing works with excellent degree of accuracy of the coefficient of correlation (R) 90.6%, and average accuracy percentage of 96.3%. This indicates that the relationship between the independent and independent variables of the developed models is good and the predicted values from a forecast model fit with the real-life data.
文摘The reformation of the economy system has led the functional departments and status of the enterprises into the variance state. Under the condition of the market economy, the kernel of the enterprises＇ functional department has diverted to that of marketing decision-making, which faces to market and meets with the need of consumption. Assuredly, the kernel of marketing decision-making is to prognosticate the future market requirement quantity of the production of enterprises accurately, so that it can ensure and realize the maximum of the enterprises＇ profit to increase. Applying the proof to test demonstration analytical method of economics and adopting the multi-regression technique, this paper analyzes the enterprises＇ production requirement quantity decision-making of the GMC （Global Management Challenge） and changes a great many of uncontrollable factors to the controllable ones of the enterprises. So, it can make the forecast order form closer to the actual prices of the future market requirement quantity in the production marketing decision-making of the enterprises and realize the optimizing combination and the working object with the minimum of the cost and the maximum of the profit. And it can insure the realization of the profit increase of the enterorises mostly in the life-cvcle of the production.
基金the Institute of Crustal Dynamics,China Earthquake Administration(Grant No.ZDJ2019-09)the National Science Foundation of China(Grant No.41704086)the National Key Research&Development Program(2016YFC060110401).
文摘We present a 3D inversion method to recover density distribution from gravity data in space domain.Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion.The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method.We also perform the effective equivalent storage and subdomain techniques in the starting model calculation,the forward modeling and the inversion procedures,which allow fast computation in space domain with reducing memory consumption but maintaining accuracy.The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data.The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km,which may be originated from hot anomalies in the lower crust.The results show that our inversion method is useful for 3D quantitative interpretation.
基金supported by National Natural Science Foundation of China (Grant No. 61170257)
文摘For two odd integers m and s with 1≤s < m and gcd(m, s) = 1, let h satisfy h(2~s-1) ≡1(mod 2~m+ 1) and d =(h + 1)(2~m-1) + 1. The cross correlation function between a binary m-sequence of period 22~m-1 and its d-decimation sequence is proved to take four values, and the correlation distribution is completely determined. Let n be an even integer and k be an integer with 1≤k≤n/2. For an odd prime p and a p-ary m-sequence {s(t)} of period p^n-1, define u(t) =∑(p^k-1)/2 i=0 s(d_it), where d_i = ip^(n/2) + p^k-i and i = 0, 1,...,(p^k-1)/2. It is proved that the cross correlation function between {u(t)} and {s(t)} is three-valued or four-valued depending on whether k is equal to n/2 or not, and the distribution is also determined.
文摘目的应用定量CT(quantitative computed tomography,QCT)技术测量腰椎骨密度(bone mineral density,BMD),探讨体格测量、体成分分析指标与中老年男性腰椎BMD的相关性。方法本研究为横断面研究,选取2018年1月至2023年2月在河南省人民医院健康管理中心接受体格检查的1152名中老年男性体检者为研究对象,采集受试者年龄、身高、体重、血压、腰围、臀围、体脂肪质量与体肌肉质量数据,并计算体质量指数(body mass index,BMI)、体脂率(body fat percentage,BFP)与骨骼肌质量指数(skeletal muscle mass index,SMI)。同时使用QCT技术测量受试者腰椎BMD值,按照BMI进行分组,分为BMI正常组(18.5≤BMI<24 kg/m^(2))、超重及肥胖组(BMI为>24 kg/m^(2)),并在两组中分别按照骨量诊断标准进行讨论。采用单因素方差分析,Pearson相关性分析和偏相关分析体格测量、体成分分析指标与腰椎BMD的相关性。结果在BMI正常组中,骨质疏松组的年龄、收缩压、腰臀比、BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05);超重及肥胖组中,骨质疏松组的年龄、收缩压、腰围、腰臀比与BFP显著高于骨量正常组,SMI显著低于骨量正常组与骨量减少组(P均<0.05)。Pearson相关性分析结果显示,BMI正常组中腰椎BMD值与年龄、腰围、腰臀比、BFP呈显著负相关关系(r=-0.385,r=-0.122,r=-0.199,r=-0.168,P均<0.05),与SMI呈正相关(r=0.226,P<0.05);超重及肥胖组中腰椎BMD值与年龄、收缩压、腰围、腰臀比、BFP呈显著负相关关系(r=-0.379,r=-0.087,r=-0.101,r=-0.187,r=-0.199,P均<0.05),与SMI呈正相关(r=0.251,P<0.05)。在校正年龄因素后,偏相关分析分析结果显示,BMI正常组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.157,r=-0.212,r=-0.134,P均<0.05),与SMI呈正相关(r=0.167,P<0.05);超重及肥胖组中腰椎BMD值与腰围、腰臀比、BFP呈显著负相关关系(r=-0.120,r=-0.163,r=-0.126,P均<0.05),与SMI呈正相关(r=0.159,P<0.05)。结论腰围、腰臀比、BFP、SMI与中老年男性体检人群腰椎BMD值密切相关,对肥胖和骨质疏松症的预防与管理具有一定临床价值。
文摘MAG(metal active gas)焊接是常用的不锈钢焊缝补焊工艺。为探究MAG补焊对轨道车辆电气箱体用06Cr19Ni10不锈钢接头力学性能的影响,首先,设计并开展了原始焊缝(AW)、补焊区域(RW)及补焊外部区域(ERW)试样金相试验、显微硬度测试和拉伸试验,利用数字图像相关技术获取了拉伸过程中试样表面应变场演化;然后,采用场发射扫描电子显微镜分析了拉伸断裂机理;最后,通过二值化量化了补焊对轫脆转变的影响。研究结果表明:补焊试样中存在明显的二次熔合线,多次的热输入导致树枝状铁素体增多;补焊试样焊缝根部由于补焊坡口较小,其硬度总体偏高,焊缝顶端铁素体发生重结晶,其焊缝硬度高于热影响区;受补焊影响,补焊及外部区域焊缝试样在拉伸过程中具有较大的局部应变,其中,补焊试样抗拉强度增大,屈服强度减小,在3种试样中屈强比最低,具有较好的塑性;与其他试样不同,由于焊缝根部性能减弱,补焊外部区域试样整体拉伸性能最弱,且由于晶界结合力减弱,表现出脆性断裂特征。
