The dual-retrieval （DR） operation sequencing problem in the flow-rack automated storage and retrieval system （AS/RS） is modeled as an assignment problem since it is equivalent to pairing outgoing unit-loads for ea...The dual-retrieval （DR） operation sequencing problem in the flow-rack automated storage and retrieval system （AS/RS） is modeled as an assignment problem since it is equivalent to pairing outgoing unit-loads for each DR operation. A recursion symmetry Hungarian method （RSHM）, modified from the Hungarian method, is proposed for generating a DR operation sequence with minimal total travel time, in which symmetry marking is introduced to ensure a feasible solution and recursion is adopted to break the endless loop caused by the symmetry marking. Simulation experiments are conducted to evaluate the cost effectiveness and the performance of the proposed method. Experimental results illustrate that compared to the single-shuttle machine, the dual-shuttle machine can reduce more than 40% of the total travel time of retrieval operations, and the RSHM saves about 5% to 10% of the total travel time of retrieval operations compared to the greedy-based heuristic.展开更多
The problem of pick sequencing in the rotary rack S/R system (PPS-RRS) is investigated with the objective of minimizing the execution time. The rotary rack S/R system consists of one S/R machine and multiple levels of...The problem of pick sequencing in the rotary rack S/R system (PPS-RRS) is investigated with the objective of minimizing the execution time. The rotary rack S/R system consists of one S/R machine and multiple levels of carousels that can rotate independently in bi-directions. The routing policy, namely the decision on the storage or retrieval sequence, dominates the efficiency and the throughput for such S/R systems, due to the complicated relationship between all levels of carousels and the S/R machine. For the purpose of optimizing the PPS-RRS, a computational model is developed in terms of execution time for picking multiple items in one trip. Characteristics of the PPS-RRS are analyzed and a local search heuristic based on a newly proposed neighborhood is presented. Integrated with the proposed local search procedure a new hybrid genetic algorithm is developed. Experimental results demonstrate the structure characteristics of good sequence and the efficiency and effectiveness of the proposed sequencing algorithms.展开更多
A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact to...A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance have been proposed with the introduction of the profile shift coefficient.Then,the load stress factors are investigated under the variation of the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch.The results show that the pitting life can be extended significantly with the increase of the profile shift coefficient.展开更多
The concept of base isolation for storage racks is still a developing subject and has not been addressed in the recently updated seismic codes for storage racks.The friction pendulum bearing system(FPS)generates a nat...The concept of base isolation for storage racks is still a developing subject and has not been addressed in the recently updated seismic codes for storage racks.The friction pendulum bearing system(FPS)generates a natural period independent of the structure's seismic mass.This property makes FPS an ideal choice for isolating rack structures since merchandise may be placed on the racks in several possible arrangements.The results of a comprehensive parametric study aimed at evaluating the seismic performance of a four-shelf,two-bay selective pallet rack isolated with FPS is presented in this paper.The influence of radius of curvature of the FPS,seismic mass,and mass irregularity on the rack's seismic response is examined.The effect of variation of the coefficient of friction due to axial loading is studied by choosing friction values from two distinct friction characterization studies.The coefficient of friction calculated from these studies shows mild and significant variations,respectively,for the whole range of static axial loads expected on the isolator,and from different pallet mass arrangements considered.The optimum radius of curvature and the appropriate range of friction coefficient,for the defined range of static axial loads,to attain a desirable seismic performance are determined.展开更多
The receptor for activated C kinase 1(RACK1)is a protein that plays a crucial role in various signaling pathways and is involved in the pathogenesis of Alzheimer's disease(AD),a prevalent neurodegenerative disease...The receptor for activated C kinase 1(RACK1)is a protein that plays a crucial role in various signaling pathways and is involved in the pathogenesis of Alzheimer's disease(AD),a prevalent neurodegenerative disease.RACK1 is highly expressed in neuronal cells of the central nervous system and regulates the pathogenesis of AD.Specifically,RACK1 is involved in regulation of the amyloid-β precursor protein processing through α-or β-secretase by binding to different protein kinase C isoforms.Additionally,RACK1 promotes synaptogenesis and synaptic plasticity by inhibiting N-methyl-D-aspartate receptors and activating gamma-aminobutyric acid A receptors,thereby preventing neuronal excitotoxicity.RACK1 also assembles inflammasomes that are involved in various neuroinflammatory pathways,such as nuclear factor-kappa B,tumor necrosis factor-alpha,and NOD-like receptor family pyrin domain-containing 3 pathways.The potential to design therapeutics that block amyloid-β accumulation and inflammation or precisely regulate synaptic plasticity represents an attractive therapeutic strategy,in which RACK1 is a potential target.In this review,we summarize the contribution of RACK1 to the pathogenesis of AD and its potential as a therapeutic target.展开更多
基金The National Natural Science Foundation of China(No.61003158,61272377)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120092110027)
文摘The dual-retrieval （DR） operation sequencing problem in the flow-rack automated storage and retrieval system （AS/RS） is modeled as an assignment problem since it is equivalent to pairing outgoing unit-loads for each DR operation. A recursion symmetry Hungarian method （RSHM）, modified from the Hungarian method, is proposed for generating a DR operation sequence with minimal total travel time, in which symmetry marking is introduced to ensure a feasible solution and recursion is adopted to break the endless loop caused by the symmetry marking. Simulation experiments are conducted to evaluate the cost effectiveness and the performance of the proposed method. Experimental results illustrate that compared to the single-shuttle machine, the dual-shuttle machine can reduce more than 40% of the total travel time of retrieval operations, and the RSHM saves about 5% to 10% of the total travel time of retrieval operations compared to the greedy-based heuristic.
基金This work was supported by the National Natural Science Foundation of China (60104009)the Natural Science Foundation of Shandong Province, China (Z2000G01).
文摘The problem of pick sequencing in the rotary rack S/R system (PPS-RRS) is investigated with the objective of minimizing the execution time. The rotary rack S/R system consists of one S/R machine and multiple levels of carousels that can rotate independently in bi-directions. The routing policy, namely the decision on the storage or retrieval sequence, dominates the efficiency and the throughput for such S/R systems, due to the complicated relationship between all levels of carousels and the S/R machine. For the purpose of optimizing the PPS-RRS, a computational model is developed in terms of execution time for picking multiple items in one trip. Characteristics of the PPS-RRS are analyzed and a local search heuristic based on a newly proposed neighborhood is presented. Integrated with the proposed local search procedure a new hybrid genetic algorithm is developed. Experimental results demonstrate the structure characteristics of good sequence and the efficiency and effectiveness of the proposed sequencing algorithms.
基金Research financially supported by Changwon National University in 2011-2012,Korea
文摘A roller rack pinion(RRP)system,which consists of a rack-bar and a cam pinion,transforms a rotation motion into linear motion.The rack-bar has a series of roller train and meshes with the cam pinion.First,the exact tooth profile of the cam pinion and the non-undercut condition to satisfy the required performance have been proposed with the introduction of the profile shift coefficient.Then,the load stress factors are investigated under the variation of the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch.The results show that the pitting life can be extended significantly with the increase of the profile shift coefficient.
文摘The concept of base isolation for storage racks is still a developing subject and has not been addressed in the recently updated seismic codes for storage racks.The friction pendulum bearing system(FPS)generates a natural period independent of the structure's seismic mass.This property makes FPS an ideal choice for isolating rack structures since merchandise may be placed on the racks in several possible arrangements.The results of a comprehensive parametric study aimed at evaluating the seismic performance of a four-shelf,two-bay selective pallet rack isolated with FPS is presented in this paper.The influence of radius of curvature of the FPS,seismic mass,and mass irregularity on the rack's seismic response is examined.The effect of variation of the coefficient of friction due to axial loading is studied by choosing friction values from two distinct friction characterization studies.The coefficient of friction calculated from these studies shows mild and significant variations,respectively,for the whole range of static axial loads expected on the isolator,and from different pallet mass arrangements considered.The optimum radius of curvature and the appropriate range of friction coefficient,for the defined range of static axial loads,to attain a desirable seismic performance are determined.
基金supported by grants from the National Natural Science Foundation of China(Grant No.82071395)the Natural Science Foundation of Chongqing(Grant Nos.cstc2021ycjh-bgzxm0186,cstc2020jcyj-zdxmX0004,and cstc2021jcyj-bsh0023)the CQMU Program for Youth Innovation in Future Medicine(Grant No.W0044).
文摘The receptor for activated C kinase 1(RACK1)is a protein that plays a crucial role in various signaling pathways and is involved in the pathogenesis of Alzheimer's disease(AD),a prevalent neurodegenerative disease.RACK1 is highly expressed in neuronal cells of the central nervous system and regulates the pathogenesis of AD.Specifically,RACK1 is involved in regulation of the amyloid-β precursor protein processing through α-or β-secretase by binding to different protein kinase C isoforms.Additionally,RACK1 promotes synaptogenesis and synaptic plasticity by inhibiting N-methyl-D-aspartate receptors and activating gamma-aminobutyric acid A receptors,thereby preventing neuronal excitotoxicity.RACK1 also assembles inflammasomes that are involved in various neuroinflammatory pathways,such as nuclear factor-kappa B,tumor necrosis factor-alpha,and NOD-like receptor family pyrin domain-containing 3 pathways.The potential to design therapeutics that block amyloid-β accumulation and inflammation or precisely regulate synaptic plasticity represents an attractive therapeutic strategy,in which RACK1 is a potential target.In this review,we summarize the contribution of RACK1 to the pathogenesis of AD and its potential as a therapeutic target.
