The concept of legged-robot stability training with a training platform is proposed and a serial-parallel mechanism platform with 6 degrees of freedom is designed for this target. The designed platform is composed of ...The concept of legged-robot stability training with a training platform is proposed and a serial-parallel mechanism platform with 6 degrees of freedom is designed for this target. The designed platform is composed of 4-DOF parallel mechanism with spherical joints and prismatic pairs,and 2-DOF serial mechanism with prismatic pairs. With this design,the platform has advantages of low platform countertop,big workspace,high carrying capacity and high stiffness. On the basis of DOF analysis and computation of space mechanism,weight supporting auxiliary mechanism and raceways-balls supporting mechanism are designed,so as to improve the stiffness of designed large platform and payload capacity of servo motors. And then the whole structure design work of the platform is done. Meanwhile,this paper derives the analytical solutions of forward kinematics, inverse kinematics and inverse dynamics. The error analysis model of position and orientation is established. And then the simulation is done in ADAMS to ensure the correctness and feasibility of this design.展开更多
In the 21 stcentury,countries in the world scramble to develop marine industry,and the sea is key to the improvement of core competence of a country. With the development of marine science and technology and marine in...In the 21 stcentury,countries in the world scramble to develop marine industry,and the sea is key to the improvement of core competence of a country. With the development of marine science and technology and marine industry,the construction of marine culture has been paid more attention to gradually at present. In China which has rich marine resources and long marine history and culture,marine cultural industry has been started late,but it has a vast development prospect. Along with the rapid development of marine cultural industry,shortage of talent in the industry has become increasingly serious and has become one of key factors limiting the development of the industry. In this study,based on the introduction of related concepts,problems of talent training in China's marine cultural industry were analyzed,and talent training mechanisms of marine cultural industry were proposed.展开更多
Based on the review of related concepts,the current situation and problems of talent training in marine cultural industry in China were analyzed,and talent training mechanisms of marine cultural industry based on coll...Based on the review of related concepts,the current situation and problems of talent training in marine cultural industry in China were analyzed,and talent training mechanisms of marine cultural industry based on collaborative innovation of governments,enterprises,colleges,scientific institutions and users were proposed to promote the transformation,upgrading and vigorous development of marine cultural industry,accelerate the spread of marine culture with Chinese characteristics,and build China into a maritime power.展开更多
For the basic condition that the quality and efficiency of forestry cadres' education and training in China are not high at present, this paper first analyzes the necessity of constructing the management mechanism...For the basic condition that the quality and efficiency of forestry cadres' education and training in China are not high at present, this paper first analyzes the necessity of constructing the management mechanism for forestry cadres' education and training from two aspects: improve the quality of forestry cadres' education and training and the inherent needs of forestry development, and also summarizes the existing problems in the management of forestry cadres' education and training in China at present, and finally, this paper puts forward the corresponding solutions from four aspects: strengthen macro planning, strengthen the construction of the quality supervision mechanism, reform the incentive system and safeguard the mechanism.展开更多
The demand of tourism industry is the foothold and starting point of tourism talent training.How to adapt to the economic and social demand for tourism talent in the new era has become an important issue of The Times ...The demand of tourism industry is the foothold and starting point of tourism talent training.How to adapt to the economic and social demand for tourism talent in the new era has become an important issue of The Times for tourism higher education talent training.By sorting out the research dynamics of talent training and industrial demand integration,the early warning mechanism of tourism talent training and industry demand is studied from the perspective of talent and industry integration.The early warning index system of tourism talent training and industrial demand is constructed using AHP method,and the problems existing in tourism talent training are found through real-time data observation and warning situation handling,thus providing decision-making support for the development of tourism management major in colleges and universities.展开更多
On July 22, 2014, the second group of national human rights education and train- ing bases was announced,increasing the number of national bases from the previous three to a total of eight, which reflects the advancem...On July 22, 2014, the second group of national human rights education and train- ing bases was announced,increasing the number of national bases from the previous three to a total of eight, which reflects the advancement of human rights education and ~aining in China and has far-reaching significance.展开更多
Abstract: Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theor...Abstract: Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows: selecting engineers, training stage-l, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.展开更多
It has been challenging to design seedling pick-up mechanism based on given key points and trajectories,because it involves dimensional synthesis and rod length optimization.In this paper,the dimensional synthesis of ...It has been challenging to design seedling pick-up mechanism based on given key points and trajectories,because it involves dimensional synthesis and rod length optimization.In this paper,the dimensional synthesis of seedling pickup mechanism with planetary gear train was studied based on the data of given key points and the trajectory of the endpoint of seedling pick-up mechanism.Given the positions and orientations requirements of the five key points,the study first conducted a dimensional synthesis of the linkage size and center of rotation.The next steps were to select a reasonable solution and optimize the data values based on the ideal seedling trajectory.The link motion was driven by the planetary gear train of the two-stage gear.Four pitch curves of noncircular gears were obtained by calculating and distributing the transmission ratio according to the data.For the pitch curve with two convex points,the tooth profile design method of incomplete noncircular gear was applied.The seedling pick-up mechanism was tested by a virtual prototype and a physical prototype designed with the obtained parameter values.The results were consistent with the theoretical design requirements,confirming that the mechanism meets the expected requirements for picking seedlings up.This paper presents a new design method of vegetable pot seedling pick-up mechanism for an automatic vegetable transplanter.展开更多
Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train fo...Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.展开更多
The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating...The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.展开更多
BACKGROUND Cardiovascular disease is the most prevalent disease worldwide and places a great burden on the health and economic welfare of patients.Cardiac surgery is an important way to treat cardiovascular disease,bu...BACKGROUND Cardiovascular disease is the most prevalent disease worldwide and places a great burden on the health and economic welfare of patients.Cardiac surgery is an important way to treat cardiovascular disease,but it can prolong mechanical ventilation time,intensive care unit(ICU)stay,and postoperative hospitalization for patients.Previous studies have demonstrated that preoperative inspiratory muscle training could decrease the incidence of postoperative pulmonary complications.AIM To explore the effect of preoperative inspiratory muscle training on mechanical ventilation time,length of ICU stay,and duration of postoperative hospitalization after cardiac surgery.METHODS A literature search of PubMed,Web of Science,Cochrane Library,EMBASE,China National Knowledge Infrastructure,WanFang,and the China Science and Technology journal VIP database was performed on April 13,2022.The data was independently extracted by two authors.The inclusion criteria were:(1)Randomized controlled trial;(2)Accessible as a full paper;(3)Patients who received cardiac surgery;(4)Preoperative inspiratory muscle training was implemented in these patients;(5)The study reported at least one of the following:Mechanical ventilation time,length of ICU stay,and/or duration of postoperative hospitalization;and(6)In English language.RESULTS We analyzed six randomized controlled trials with a total of 925 participants.The pooled mean difference of mechanical ventilation time was-0.45 h[95%confidence interval(CI):-1.59-0.69],which was not statistically significant between the intervention group and the control group.The pooled mean difference of length of ICU stay was 0.44 h(95%CI:-0.58-1.45).The pooled mean difference of postoperative hospitalization was-1.77 d in the intervention group vs the control group[95%CI:-2.41-(-1.12)].CONCLUSION Preoperative inspiratory muscle training may decrease the duration of postoperative hospitalization for patients undergoing cardiac surgery.More high-quality studies are needed to confirm our conclusion.展开更多
BACKGROUND Mechanical ventilation is a common resuscitation method in the intensive care unit(ICU).Unfortunately,this treatment process prolongs the ICU stay of patients with an increased incidence of delirium,which u...BACKGROUND Mechanical ventilation is a common resuscitation method in the intensive care unit(ICU).Unfortunately,this treatment process prolongs the ICU stay of patients with an increased incidence of delirium,which ultimately affects the prognosis.AIM To evaluate the effect of progressive early rehabilitation training on treatment and prognosis of patients with mechanical ventilation in ICU.METHODS The convenience sampling method selected 190 patients with mechanical ventilation admitted to the Fourth Hospital of Hebei Medical University from March 2020 to March 2021.According to the random number table method,they were divided into the control and intervention groups.The control group received routine nursing and rehabilitation measures,whereas the intervention group received progressive early rehabilitation training.In addition,the incidence and duration of delirium were compared for the two groups along with mechanical ventilation time,ICU hospitalization time,functional independence measure(FIM)score,Barthel index,and the incidence of complications(deep venous thrombosis,pressure sores,and acquired muscle weakness).RESULTS In the intervention group,the incidence of delirium was significantly lower than in the control group(28%vs 52%,P<0.001).In the intervention group,the duration of delirium,mechanical ventilation time,and ICU stay were shorter than in the control group(P<0.001).The FIM and Barthel index scores were significantly higher in the intervention group than the control group(P<0.001).The total incidence of complications in the intervention group was 3.15%,which was lower than 17.89%in the control group(P<0.001).CONCLUSION Progressive early rehabilitation training reduced the incidence of delirium and complications in ICU patients with mechanical ventilation,which improved prognosis and quality of life.展开更多
Purpose-To optimize train operations,dispatchers currently rely on experience for quick adjustments when delays occur.However,delay predictions often involve imprecise shifts based on known delay times.Real-time and a...Purpose-To optimize train operations,dispatchers currently rely on experience for quick adjustments when delays occur.However,delay predictions often involve imprecise shifts based on known delay times.Real-time and accurate train delay predictions,facilitated by data-driven neural network models,can significantly reduce dispatcher stress and improve adjustment plans.Leveraging current train operation data,these models enable swift and precise predictions,addressing challenges posed by train delays in high-speed rail networks during unforeseen events.Design/methodology/approach-This paper proposes CBLA-net,a neural network architecture for predicting late arrival times.It combines CNN,Bi-LSTM,and attention mechanisms to extract features,handle time series data,and enhance information utilization.Trained on operational data from the Beijing-Tianjin line,it predicts the late arrival time of a target train at the next station using multidimensional input data from the target and preceding trains.Findings-This study evaluates our model’s predictive performance using two data approaches:one considering full data and another focusing only on late arrivals.Results show precise and rapid predictions.Training with full data achieves aMAEof approximately 0.54 minutes and a RMSEof 0.65 minutes,surpassing the model trained solely on delay data(MAE:is about 1.02 min,RMSE:is about 1.52 min).Despite superior overall performance with full data,the model excels at predicting delays exceeding 15 minutes when trained exclusively on late arrivals.For enhanced adaptability to real-world train operations,training with full data is recommended.Originality/value-This paper introduces a novel neural network model,CBLA-net,for predicting train delay times.It innovatively compares and analyzes the model’s performance using both full data and delay data formats.Additionally,the evaluation of the network’s predictive capabilities considers different scenarios,providing a comprehensive demonstration of the model’s predictive performance.展开更多
In order to improve the adaptability of the planting mechanism for different plant spacings,a variable differential gear train planting mechanism based on precise pose and trajectory control was proposed by combining ...In order to improve the adaptability of the planting mechanism for different plant spacings,a variable differential gear train planting mechanism based on precise pose and trajectory control was proposed by combining the open chain 2R rod group and the variable differential gear train.According to the pose requirements of receiving seedling point,transporting seedling point and planting point,three precise pose points of constrained planting trajectory were determined.Through the three-position motion generation structural synthesis method,combined with computer-aided optimization design software,a set of mechanism parameters that meet the planting requirements were optimized.Based on the optimized mechanism parameters,by only changing the coordinates of two trajectory shape control points,three planting trajectories with key point position information adapted to 300 mm,400 mm and 500 mm plant spacing were obtained by interpolation,and three pairs of total transmission ratio of three groups of variable differential gear trains were calculated.When distributing the total transmission ratio of the mechanism,the fixed axis gear train and the differential gear train are combined.The fixed axis gear train included a pair of non-circular gear pairs and a pair of positive gear pairs,which were convenient for disassembly and assembly.The former drives the sun gear at variable speed,and the latter drives the planet carrier at uniform speed.Based on this structure,the transmission ratio of the positive gear pair is-1,and the transmission ratio of the differential gear train is 0.5.The sub-transmission ratio of the single-stage non-circular gear pair was calculated and the pitch curves of three pairs of noncircular gears were solved.Three pairs of non-circular gear pairs with different transmission ratios were replaced in turn and three sets of planting mechanisms were modeled in three dimensions.The virtual prototype motion simulation was completed by ADAMS software,and the physical prototype was built for vegetable pot seedling planting test.The theoretical solution was consistent with the attitude and trajectory of the actual test.When the test sample size was 100 plants,the actual average plant spacing was measured to be 303 mm,402 mm,and 503 mm,with errors of 1.3%,1.25%,and 1.88%.The width of the moving hole was 72 mm,70 mm,and 71 mm,and the planting success rate were 94%,96%,and 95%.The test results verified the correctness of the optimization design results of the mechanism,indicating that the variable differential gear train planting mechanism can adapt to a variety of plant spacing and has good planting effect.展开更多
This paper focuses on the problem of the adaptive robust control of a lower limbs rehabilitation robot(LLRR) that is a nonlinear system running under passive training mode. In reality, uncertainties including modeling...This paper focuses on the problem of the adaptive robust control of a lower limbs rehabilitation robot(LLRR) that is a nonlinear system running under passive training mode. In reality, uncertainties including modeling error, initial condition deviation, friction force and other unknown external disturbances always exist in a LLRR system. So, it is necessary to consider the uncertainties in the unilateral man-machine dynamical model of the LLRR we described. In the dynamical model, uncertainties are(possibly fast) time-varying and bounded. However, the bounds are unknown. Based on the dynamical model, we design an adaptive robust control with an adaptive law that is leakagetype based and on the framework of Udwadia-Kalaba theory to compensate for the uncertainties and to realize tracking control of the LLRR. Furthermore, the effectiveness of designed control is shown with numerical simulations.展开更多
基金Sponsored by the National High-Tech Research and Development Program(Grant No.2006AA04Z201)
文摘The concept of legged-robot stability training with a training platform is proposed and a serial-parallel mechanism platform with 6 degrees of freedom is designed for this target. The designed platform is composed of 4-DOF parallel mechanism with spherical joints and prismatic pairs,and 2-DOF serial mechanism with prismatic pairs. With this design,the platform has advantages of low platform countertop,big workspace,high carrying capacity and high stiffness. On the basis of DOF analysis and computation of space mechanism,weight supporting auxiliary mechanism and raceways-balls supporting mechanism are designed,so as to improve the stiffness of designed large platform and payload capacity of servo motors. And then the whole structure design work of the platform is done. Meanwhile,this paper derives the analytical solutions of forward kinematics, inverse kinematics and inverse dynamics. The error analysis model of position and orientation is established. And then the simulation is done in ADAMS to ensure the correctness and feasibility of this design.
基金Supported by Educational Science Research Project of Shanghai City(C16064)Key Teaching Reform Project for Undergraduate Education of Colleges and Universities in Shanghai City "Research and Practice of Training Modes of Shipping Professionals Based on Collaboration among Different Domains from a Perspective of Innovation and Entrepreneurship Education"
文摘In the 21 stcentury,countries in the world scramble to develop marine industry,and the sea is key to the improvement of core competence of a country. With the development of marine science and technology and marine industry,the construction of marine culture has been paid more attention to gradually at present. In China which has rich marine resources and long marine history and culture,marine cultural industry has been started late,but it has a vast development prospect. Along with the rapid development of marine cultural industry,shortage of talent in the industry has become increasingly serious and has become one of key factors limiting the development of the industry. In this study,based on the introduction of related concepts,problems of talent training in China's marine cultural industry were analyzed,and talent training mechanisms of marine cultural industry were proposed.
基金Supported by Educational Science Research Project of Shanghai City(C16064)
文摘Based on the review of related concepts,the current situation and problems of talent training in marine cultural industry in China were analyzed,and talent training mechanisms of marine cultural industry based on collaborative innovation of governments,enterprises,colleges,scientific institutions and users were proposed to promote the transformation,upgrading and vigorous development of marine cultural industry,accelerate the spread of marine culture with Chinese characteristics,and build China into a maritime power.
文摘For the basic condition that the quality and efficiency of forestry cadres' education and training in China are not high at present, this paper first analyzes the necessity of constructing the management mechanism for forestry cadres' education and training from two aspects: improve the quality of forestry cadres' education and training and the inherent needs of forestry development, and also summarizes the existing problems in the management of forestry cadres' education and training in China at present, and finally, this paper puts forward the corresponding solutions from four aspects: strengthen macro planning, strengthen the construction of the quality supervision mechanism, reform the incentive system and safeguard the mechanism.
基金Undergraduate Education Reform Project of Shandong Province(M2018X291)High End United Front Think Tank Project of the Central Academy of Social Sciences(ZK20180341)+4 种基金Annual Subject of Humanities and Social Sciences in Shandong Province(18ZCGL08)Undergraduate Education Reform Program of Taishan University(201213)Philosophy and Social Sciences Planning Program of Tai’an City(18skx042)Statistical Research Project of Shandong Province(KT1955)Science and Technology Development Program of Tai’an City(2019ZC258).
文摘The demand of tourism industry is the foothold and starting point of tourism talent training.How to adapt to the economic and social demand for tourism talent in the new era has become an important issue of The Times for tourism higher education talent training.By sorting out the research dynamics of talent training and industrial demand integration,the early warning mechanism of tourism talent training and industry demand is studied from the perspective of talent and industry integration.The early warning index system of tourism talent training and industrial demand is constructed using AHP method,and the problems existing in tourism talent training are found through real-time data observation and warning situation handling,thus providing decision-making support for the development of tourism management major in colleges and universities.
文摘On July 22, 2014, the second group of national human rights education and train- ing bases was announced,increasing the number of national bases from the previous three to a total of eight, which reflects the advancement of human rights education and ~aining in China and has far-reaching significance.
基金supported by National Natural Science Foundation of China(Grant Nos.51275153,51105128)National Innovation Project of China(Grant No.2011IM010200)Social Science Planning Fund Program of Hebei Province,China(Grant No.HB13GL050)
文摘Abstract: Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows: selecting engineers, training stage-l, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.
基金National Key Research and Development Program of China(Grant No.2017YFD0700800)National Science Foundation of China(Grant Nos.51775512,51575496)Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ16E050003).
文摘It has been challenging to design seedling pick-up mechanism based on given key points and trajectories,because it involves dimensional synthesis and rod length optimization.In this paper,the dimensional synthesis of seedling pickup mechanism with planetary gear train was studied based on the data of given key points and the trajectory of the endpoint of seedling pick-up mechanism.Given the positions and orientations requirements of the five key points,the study first conducted a dimensional synthesis of the linkage size and center of rotation.The next steps were to select a reasonable solution and optimize the data values based on the ideal seedling trajectory.The link motion was driven by the planetary gear train of the two-stage gear.Four pitch curves of noncircular gears were obtained by calculating and distributing the transmission ratio according to the data.For the pitch curve with two convex points,the tooth profile design method of incomplete noncircular gear was applied.The seedling pick-up mechanism was tested by a virtual prototype and a physical prototype designed with the obtained parameter values.The results were consistent with the theoretical design requirements,confirming that the mechanism meets the expected requirements for picking seedlings up.This paper presents a new design method of vegetable pot seedling pick-up mechanism for an automatic vegetable transplanter.
基金Supported by National Basic Research Program of China (973 Program,Grant No.2001CB711104)National Natural Science Foundation of China (Grant No.51005190)Fok Ying Tung Education Foundation of China (Grant No.122014)
文摘Published studies in regard to coupler systems have been mainly focused on the manufacturing process or coupler strength issues. With the ever increasing of tonnage and length of heavy haul trains, lateral in-train forces generated by longitudinal in-train forces and coupler rotations have become a more and more significant safety issue for heavy haul train operations. Derailments caused by excessive lateral in-train forces are frequently reported. This article studies two typical coupler systems used on heavy haul locomotives. Their structures and stabilizing mechanism are analyzed before the corresponding models are developed. Coupler systems models are featured by two distinct stabilizing mechanism models and draft gear models with hysteresis considered. A model set which consists of four locomotives and three coupler systems is developed to study the rotational behavior of different coupler systems and their implications for locomotive dynamics. Simulated results indicate that when the locomotives are equipped with the type B coupler system, locomotives can meet the dynamics standard on tangent tracks; while the dynamics performance on curved tracks is very poor. The maximum longitudinal in-train force for locomotives equipped with the type B coupler system is 2000 kN. Simulations revealed a distinct trend for the type A coupler system. Locomotive dynamics are poorer for the type A case when locomotives are running on tangent tracks, while the dynamics are better for the type A case when locomotives are running on curved tracks. Theoretical studies and simulations carried out in this article suggest that a combination of the two types of stabilizing mechanism can result in a good design which can significantly decrease the relevant derailments.
基金National Natural Science Foundation of China(Nos.51675486 51505239 51575496)
文摘The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.
文摘BACKGROUND Cardiovascular disease is the most prevalent disease worldwide and places a great burden on the health and economic welfare of patients.Cardiac surgery is an important way to treat cardiovascular disease,but it can prolong mechanical ventilation time,intensive care unit(ICU)stay,and postoperative hospitalization for patients.Previous studies have demonstrated that preoperative inspiratory muscle training could decrease the incidence of postoperative pulmonary complications.AIM To explore the effect of preoperative inspiratory muscle training on mechanical ventilation time,length of ICU stay,and duration of postoperative hospitalization after cardiac surgery.METHODS A literature search of PubMed,Web of Science,Cochrane Library,EMBASE,China National Knowledge Infrastructure,WanFang,and the China Science and Technology journal VIP database was performed on April 13,2022.The data was independently extracted by two authors.The inclusion criteria were:(1)Randomized controlled trial;(2)Accessible as a full paper;(3)Patients who received cardiac surgery;(4)Preoperative inspiratory muscle training was implemented in these patients;(5)The study reported at least one of the following:Mechanical ventilation time,length of ICU stay,and/or duration of postoperative hospitalization;and(6)In English language.RESULTS We analyzed six randomized controlled trials with a total of 925 participants.The pooled mean difference of mechanical ventilation time was-0.45 h[95%confidence interval(CI):-1.59-0.69],which was not statistically significant between the intervention group and the control group.The pooled mean difference of length of ICU stay was 0.44 h(95%CI:-0.58-1.45).The pooled mean difference of postoperative hospitalization was-1.77 d in the intervention group vs the control group[95%CI:-2.41-(-1.12)].CONCLUSION Preoperative inspiratory muscle training may decrease the duration of postoperative hospitalization for patients undergoing cardiac surgery.More high-quality studies are needed to confirm our conclusion.
文摘BACKGROUND Mechanical ventilation is a common resuscitation method in the intensive care unit(ICU).Unfortunately,this treatment process prolongs the ICU stay of patients with an increased incidence of delirium,which ultimately affects the prognosis.AIM To evaluate the effect of progressive early rehabilitation training on treatment and prognosis of patients with mechanical ventilation in ICU.METHODS The convenience sampling method selected 190 patients with mechanical ventilation admitted to the Fourth Hospital of Hebei Medical University from March 2020 to March 2021.According to the random number table method,they were divided into the control and intervention groups.The control group received routine nursing and rehabilitation measures,whereas the intervention group received progressive early rehabilitation training.In addition,the incidence and duration of delirium were compared for the two groups along with mechanical ventilation time,ICU hospitalization time,functional independence measure(FIM)score,Barthel index,and the incidence of complications(deep venous thrombosis,pressure sores,and acquired muscle weakness).RESULTS In the intervention group,the incidence of delirium was significantly lower than in the control group(28%vs 52%,P<0.001).In the intervention group,the duration of delirium,mechanical ventilation time,and ICU stay were shorter than in the control group(P<0.001).The FIM and Barthel index scores were significantly higher in the intervention group than the control group(P<0.001).The total incidence of complications in the intervention group was 3.15%,which was lower than 17.89%in the control group(P<0.001).CONCLUSION Progressive early rehabilitation training reduced the incidence of delirium and complications in ICU patients with mechanical ventilation,which improved prognosis and quality of life.
基金supported in part by the National Natural Science Foundation of China under Grant 62203468in part by the Technological Research and Development Program of China State Railway Group Co.,Ltd.under Grant Q2023X011+1 种基金in part by the Young Elite Scientist Sponsorship Program by China Association for Science and Technology(CAST)under Grant 2022QNRC001in part by the Youth Talent Program Supported by China Railway Society,and in part by the Research Program of China Academy of Railway Sciences Corporation Limited under Grant 2023YJ112.
文摘Purpose-To optimize train operations,dispatchers currently rely on experience for quick adjustments when delays occur.However,delay predictions often involve imprecise shifts based on known delay times.Real-time and accurate train delay predictions,facilitated by data-driven neural network models,can significantly reduce dispatcher stress and improve adjustment plans.Leveraging current train operation data,these models enable swift and precise predictions,addressing challenges posed by train delays in high-speed rail networks during unforeseen events.Design/methodology/approach-This paper proposes CBLA-net,a neural network architecture for predicting late arrival times.It combines CNN,Bi-LSTM,and attention mechanisms to extract features,handle time series data,and enhance information utilization.Trained on operational data from the Beijing-Tianjin line,it predicts the late arrival time of a target train at the next station using multidimensional input data from the target and preceding trains.Findings-This study evaluates our model’s predictive performance using two data approaches:one considering full data and another focusing only on late arrivals.Results show precise and rapid predictions.Training with full data achieves aMAEof approximately 0.54 minutes and a RMSEof 0.65 minutes,surpassing the model trained solely on delay data(MAE:is about 1.02 min,RMSE:is about 1.52 min).Despite superior overall performance with full data,the model excels at predicting delays exceeding 15 minutes when trained exclusively on late arrivals.For enhanced adaptability to real-world train operations,training with full data is recommended.Originality/value-This paper introduces a novel neural network model,CBLA-net,for predicting train delay times.It innovatively compares and analyzes the model’s performance using both full data and delay data formats.Additionally,the evaluation of the network’s predictive capabilities considers different scenarios,providing a comprehensive demonstration of the model’s predictive performance.
基金financially supported by the Key Research Projects of Zhejiang Province(Grant No.2022C02042,2022C02002)the National Key Research and Development Program of China(Grant No.2022YFD2001803)+2 种基金the National Natural Science Foundation of China(Grant No.32071909)the Shanghai Science and Technology Agricultural Development Project 2021(No.4-1)the General Project of Agriculture and Social Development in Hangzhou(Grant No.202203B08).
文摘In order to improve the adaptability of the planting mechanism for different plant spacings,a variable differential gear train planting mechanism based on precise pose and trajectory control was proposed by combining the open chain 2R rod group and the variable differential gear train.According to the pose requirements of receiving seedling point,transporting seedling point and planting point,three precise pose points of constrained planting trajectory were determined.Through the three-position motion generation structural synthesis method,combined with computer-aided optimization design software,a set of mechanism parameters that meet the planting requirements were optimized.Based on the optimized mechanism parameters,by only changing the coordinates of two trajectory shape control points,three planting trajectories with key point position information adapted to 300 mm,400 mm and 500 mm plant spacing were obtained by interpolation,and three pairs of total transmission ratio of three groups of variable differential gear trains were calculated.When distributing the total transmission ratio of the mechanism,the fixed axis gear train and the differential gear train are combined.The fixed axis gear train included a pair of non-circular gear pairs and a pair of positive gear pairs,which were convenient for disassembly and assembly.The former drives the sun gear at variable speed,and the latter drives the planet carrier at uniform speed.Based on this structure,the transmission ratio of the positive gear pair is-1,and the transmission ratio of the differential gear train is 0.5.The sub-transmission ratio of the single-stage non-circular gear pair was calculated and the pitch curves of three pairs of noncircular gears were solved.Three pairs of non-circular gear pairs with different transmission ratios were replaced in turn and three sets of planting mechanisms were modeled in three dimensions.The virtual prototype motion simulation was completed by ADAMS software,and the physical prototype was built for vegetable pot seedling planting test.The theoretical solution was consistent with the attitude and trajectory of the actual test.When the test sample size was 100 plants,the actual average plant spacing was measured to be 303 mm,402 mm,and 503 mm,with errors of 1.3%,1.25%,and 1.88%.The width of the moving hole was 72 mm,70 mm,and 71 mm,and the planting success rate were 94%,96%,and 95%.The test results verified the correctness of the optimization design results of the mechanism,indicating that the variable differential gear train planting mechanism can adapt to a variety of plant spacing and has good planting effect.
基金supported by the National Natural Science Foundation of China(51505116)the Fundamental Research Funds for the Central Universities(JZ2016HGTB0716)+2 种基金Natural and Science Foundation of Anhui Province(1508085SME221)China Postdoctoral Science Foundation(2016M590563)the Science and Technology Public Relations Project of Anhui Province(1604a0902181)
文摘This paper focuses on the problem of the adaptive robust control of a lower limbs rehabilitation robot(LLRR) that is a nonlinear system running under passive training mode. In reality, uncertainties including modeling error, initial condition deviation, friction force and other unknown external disturbances always exist in a LLRR system. So, it is necessary to consider the uncertainties in the unilateral man-machine dynamical model of the LLRR we described. In the dynamical model, uncertainties are(possibly fast) time-varying and bounded. However, the bounds are unknown. Based on the dynamical model, we design an adaptive robust control with an adaptive law that is leakagetype based and on the framework of Udwadia-Kalaba theory to compensate for the uncertainties and to realize tracking control of the LLRR. Furthermore, the effectiveness of designed control is shown with numerical simulations.