提出一种能在两类'货到人'订单拣选系统(即自动存储及取货系统(Automated storage and retrieval system,AS/RS)和Carousel系统)之间依据不同订单类型进行系统适用性选择的系统优化方法。订单拣选系统最常用的两种作业策略分区...提出一种能在两类'货到人'订单拣选系统(即自动存储及取货系统(Automated storage and retrieval system,AS/RS)和Carousel系统)之间依据不同订单类型进行系统适用性选择的系统优化方法。订单拣选系统最常用的两种作业策略分区策略和分批策略本质上都是对订单的聚类,因此订单可以被分为很多一维单元化网格;根据各系统的逻辑运动关系,得到单元化网格的拣选时间表达式;利用作业时间模型和空间填充线,对单元化网格进行聚类,得到二维系统的总订单拣选时间,采用遗传算法计算各系统的最优值;比较各系统的时间选择适用性,即选择总订单拣选时间更小的系统。通过对四类不同类型的订单进行试验研究,初步得出两类系统对四类订单的适用性分析和系统参数敏感性分析。展开更多
Pinhole corrosion is difficult to discover through conventional ultrasonic guided waves inspection,particularly for micro-sized pinholes less than 1 mm in diameter.This study proposes a new micro-sized pinhole inspect...Pinhole corrosion is difficult to discover through conventional ultrasonic guided waves inspection,particularly for micro-sized pinholes less than 1 mm in diameter.This study proposes a new micro-sized pinhole inspection method based on segmented time reversal(STR)and high-order modes cluster(HOMC)Lamb waves.First,the principle of defect echo enhancement using STR is introduced.Conventional and STR inspection experiments were conducted on aluminum plates with a thickness of 3 mm and defects with different diameters and depths.The parameters of the segment window are discussed in detail.The results indicate that the proposed method had an amplitude four times larger than of conventional ultrasonic guided waves inspection method for pinhole defect detection and could detect micro-sized pinhole defects as small as 0.5 mm in diameter and 0.5 mm in depth.Moreover,the segment window location and width(5-10 times width of the conventional excitation signal)did not affect the detection sensitivity.The combination of low-power and STR is more conducive to detection in different environments,indicating the robustness of the proposed method.Compared with conventional ultrasonic guided wave inspection methods,the proposed method can detect much smaller defect echoes usually obscured by noise that are difficult to detect with a lower excitation power and thus this study would be a good reference for pinhole defect detection.展开更多
The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system separately.But t...The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system separately.But there is little research on comparative study between sequential zoning and simultaneous zoning.In order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is presented.Essentially,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit grids.After the time formulation in one-dimensional unit was defined,the time models for each zoning policy in two-dimensional space were established using filling curves and sequence models to link the one-dimensional unit grids.In consideration of ＂U＂ shaped dual tour into consideration,the subtraction value of order picking time between sequential zoning and simultaneous zoning was defined as the objective function to select the suitable zoning policy based on time models.As it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking time.In the experimental study,5 different kinds of order/stock keeping unit（SKU） matrices with different densities d and quantities q following uniform distribution were created in order to test the suitability of sequential zoning and simultaneous zoning to different kinds of orders.After parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was gotten.By observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were obtained.The significant effect of batch size b,zone number z and density d on suitability was also found by experimental study.The proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts system,and improves the rationality and effi展开更多
For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams （1 st-5th） of Ashihe Ri...For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams （1 st-5th） of Ashihe River continuum in Maoershan Experimental Forest of Northeast Forestry University, Sharlgzhi City, Heilongjiang Province, China. The indexes of stream water quality, i.e., the pH, dissolved oxygen（DO）, turbidity, temperature, PO43-P, NO3-N and NH4^＋-N concentrations, total dissolved inorganic nitrogen （TDIN-N, including concentrations of NO3^＋-N and NH4^＋-N）, and total phosphorus （inorganic and organic phosphorous, TP） were measured and analyzed. The stream order, related environmental settings and land-use type were recorded for each sampling location. The indexes of stream water quality at different locations with different stream orders and land use types were compared by ANOVA analysis. The indexes of stream water quality at different sampling locations were analyzed by Hierarchical cluster analysis. Result showed that water quality had significant difference in different stream orders and land use types; some locations with different stream features （stream order and land use type） were grouped into same clusters, indicating that random disturbances produced the variations in water quality, which made the spatial variances of stream water quality inconsistent with the general rules.展开更多
The bond order and packing ratios in the single-crystal of the two structural polymorphs as well as the detailed electronic structures of the molecular model were studied using density functional theory. The strength ...The bond order and packing ratios in the single-crystal of the two structural polymorphs as well as the detailed electronic structures of the molecular model were studied using density functional theory. The strength of different Mn coordination bonds was analyzed in detail through Mayer bond order. Besides bond length, many other factors such as the orientation of ligand and nature of metal also significantly influence the bond order. Packing ratios cal- culated using cluster model reveals that packing along b direction in Dimer is more favorable than other directions due to the associated interactions of π-π and CI…H when packing in this direction. Electronic structure helps ex- plain the formation of Dimer from monomer or direct forming of Chain from ligand/Cl and metal. This would shed light on further understanding the importance of supramolecular interaction on crystal engineering.展开更多
The dynamical behavior on fractional-order Duffing system with two time scales is investigated,and the point-cycle coupling type cluster oscillation is firstly observed herein.When taking the fractional order as bifur...The dynamical behavior on fractional-order Duffing system with two time scales is investigated,and the point-cycle coupling type cluster oscillation is firstly observed herein.When taking the fractional order as bifurcation parameter,the dynamics of the autonomous Duffing system will become more complex than the corresponding integer-order one,and some typical phenomenon exist only in the fractional-order one.Different attractors exist in various parameter space,and Hopf bifurcation only happens while fractional order is bigger than 1 under certain parameter condition.Moreover,the bifurcation behavior of the autonomous system may regulate dynamical phenomenon of the periodic excited system.It results into the point-cycle coupling type cluster oscillation when the fractional order is bigger than 1.The related generation mechanism based on slow-fast analysis method is that the slow variation of periodic excitation makes the system periodically visit different attractors and critical points of different bifurcations of the autonomous system.展开更多
文摘提出一种能在两类'货到人'订单拣选系统(即自动存储及取货系统(Automated storage and retrieval system,AS/RS)和Carousel系统)之间依据不同订单类型进行系统适用性选择的系统优化方法。订单拣选系统最常用的两种作业策略分区策略和分批策略本质上都是对订单的聚类,因此订单可以被分为很多一维单元化网格;根据各系统的逻辑运动关系,得到单元化网格的拣选时间表达式;利用作业时间模型和空间填充线,对单元化网格进行聚类,得到二维系统的总订单拣选时间,采用遗传算法计算各系统的最优值;比较各系统的时间选择适用性,即选择总订单拣选时间更小的系统。通过对四类不同类型的订单进行试验研究,初步得出两类系统对四类订单的适用性分析和系统参数敏感性分析。
基金National Natural Science Foundation of China(Grant No.62071433)National Key R&D Program of China(Grant No.2022YFC3005002)。
文摘Pinhole corrosion is difficult to discover through conventional ultrasonic guided waves inspection,particularly for micro-sized pinholes less than 1 mm in diameter.This study proposes a new micro-sized pinhole inspection method based on segmented time reversal(STR)and high-order modes cluster(HOMC)Lamb waves.First,the principle of defect echo enhancement using STR is introduced.Conventional and STR inspection experiments were conducted on aluminum plates with a thickness of 3 mm and defects with different diameters and depths.The parameters of the segment window are discussed in detail.The results indicate that the proposed method had an amplitude four times larger than of conventional ultrasonic guided waves inspection method for pinhole defect detection and could detect micro-sized pinhole defects as small as 0.5 mm in diameter and 0.5 mm in depth.Moreover,the segment window location and width(5-10 times width of the conventional excitation signal)did not affect the detection sensitivity.The combination of low-power and STR is more conducive to detection in different environments,indicating the robustness of the proposed method.Compared with conventional ultrasonic guided wave inspection methods,the proposed method can detect much smaller defect echoes usually obscured by noise that are difficult to detect with a lower excitation power and thus this study would be a good reference for pinhole defect detection.
基金supported by National Natural Science Foundation of China (Grant No. 50175064)China Scholarship Council (Grant No. 2008622078)Material Handling Industry of America (Grant No. 12251)
文摘The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system separately.But there is little research on comparative study between sequential zoning and simultaneous zoning.In order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is presented.Essentially,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit grids.After the time formulation in one-dimensional unit was defined,the time models for each zoning policy in two-dimensional space were established using filling curves and sequence models to link the one-dimensional unit grids.In consideration of ＂U＂ shaped dual tour into consideration,the subtraction value of order picking time between sequential zoning and simultaneous zoning was defined as the objective function to select the suitable zoning policy based on time models.As it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking time.In the experimental study,5 different kinds of order/stock keeping unit（SKU） matrices with different densities d and quantities q following uniform distribution were created in order to test the suitability of sequential zoning and simultaneous zoning to different kinds of orders.After parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was gotten.By observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were obtained.The significant effect of batch size b,zone number z and density d on suitability was also found by experimental study.The proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts system,and improves the rationality and effi
基金This research was supported by a grant of the National Nature Science Foundation of China （No. 30370277）.
文摘For understanding the reasons that caused the degradation of water quality in lower order streams, systematic sampling was conducted at different spatial locations aiong the low order streams （1 st-5th） of Ashihe River continuum in Maoershan Experimental Forest of Northeast Forestry University, Sharlgzhi City, Heilongjiang Province, China. The indexes of stream water quality, i.e., the pH, dissolved oxygen（DO）, turbidity, temperature, PO43-P, NO3-N and NH4^＋-N concentrations, total dissolved inorganic nitrogen （TDIN-N, including concentrations of NO3^＋-N and NH4^＋-N）, and total phosphorus （inorganic and organic phosphorous, TP） were measured and analyzed. The stream order, related environmental settings and land-use type were recorded for each sampling location. The indexes of stream water quality at different locations with different stream orders and land use types were compared by ANOVA analysis. The indexes of stream water quality at different sampling locations were analyzed by Hierarchical cluster analysis. Result showed that water quality had significant difference in different stream orders and land use types; some locations with different stream features （stream order and land use type） were grouped into same clusters, indicating that random disturbances produced the variations in water quality, which made the spatial variances of stream water quality inconsistent with the general rules.
基金This work was supported by the National ScienceFoundation for Distinguished Young Scholars of China （No. 21525101）, the National Science Foundation of China and Guangxi Province （Nos. 91122032, 2014GXNSFFA118003）, the BAGUI scholar program （No. 2014A001）, the Project of Talents Highland of Guangxi Province, and Hubei University. This work is also supported by Opening Project of Wuhan National High Magnetic Field Center （No. 2015KF05）, and Huazhong University of Science and Technology. We acknowledge the group of Professor Jianzhuang Jiang （University of Science and Technology Beijing： USTB） for providing computational resources and thank Dr. Dongdong Qi for stimulating discussions.
文摘The bond order and packing ratios in the single-crystal of the two structural polymorphs as well as the detailed electronic structures of the molecular model were studied using density functional theory. The strength of different Mn coordination bonds was analyzed in detail through Mayer bond order. Besides bond length, many other factors such as the orientation of ligand and nature of metal also significantly influence the bond order. Packing ratios cal- culated using cluster model reveals that packing along b direction in Dimer is more favorable than other directions due to the associated interactions of π-π and CI…H when packing in this direction. Electronic structure helps ex- plain the formation of Dimer from monomer or direct forming of Chain from ligand/Cl and metal. This would shed light on further understanding the importance of supramolecular interaction on crystal engineering.
基金supported by the National Natural Science Foundation of China(Grants 11672191,11772206 and U1934201)the Hundred Excellent Innovative Talents Support Program in Hebei University(Grant SLRC2017053).
文摘The dynamical behavior on fractional-order Duffing system with two time scales is investigated,and the point-cycle coupling type cluster oscillation is firstly observed herein.When taking the fractional order as bifurcation parameter,the dynamics of the autonomous Duffing system will become more complex than the corresponding integer-order one,and some typical phenomenon exist only in the fractional-order one.Different attractors exist in various parameter space,and Hopf bifurcation only happens while fractional order is bigger than 1 under certain parameter condition.Moreover,the bifurcation behavior of the autonomous system may regulate dynamical phenomenon of the periodic excited system.It results into the point-cycle coupling type cluster oscillation when the fractional order is bigger than 1.The related generation mechanism based on slow-fast analysis method is that the slow variation of periodic excitation makes the system periodically visit different attractors and critical points of different bifurcations of the autonomous system.
