The central solenoid is an important part of the HT-7U device. In this paper， the computational analysis of the stress and the displacement on the pre-load structures of the central solenoid have been made by the fin...The central solenoid is an important part of the HT-7U device. In this paper， the computational analysis of the stress and the displacement on the pre-load structures of the central solenoid have been made by the finite element analysis system COSMOS/M2.0 under room and/or operating temperature. According to the analytical results, the clip aprons and compression plates are all satisfied with safety design criteria.展开更多
Background: As the prognosis of lung cancer (LC) patients improves, subcutaneously implanted central venous access device ports (CV-ports) have frequently been used for continuing chemotherapy (CC) or palliative care ...Background: As the prognosis of lung cancer (LC) patients improves, subcutaneously implanted central venous access device ports (CV-ports) have frequently been used for continuing chemotherapy (CC) or palliative care (PC). In this study, we examined the clinical course of LC patients with subcutaneously implanted CV-ports from the time of receiving chemotherapy to the endpoint of cancer. Materials and Methods: We retrospectively reviewed the clinical data and treatment history of LC patients with subcutaneously implanted CV-ports between June 2008 and November 2013 using clinical records and a pharmacy database. Results: Of the 132 LC patients with subcutaneously implanted CV-ports, 79 (59.8%) had CV-ports for CC (the CC group) and 53 (40.2%) had CV-ports for PC (the PC group). After CV-port implantation, LC patients in the CC group received a median of two regimens with a median of 6 cycles. The median survival time of patients in the CC and PC groups was 457 and 44 days, respectively. In the CC group, the median survival time of small cell and non-small cell LC patients was 342 (95% confidence interval, 235 - 627) and 563 (95% confidence interval, 368 - 728) days, respectively. Nine patients (6.8%) had their CV-ports removed due to complications. Forty (30.3%) of the 132 enrolled patients were referred for at-home PC. The at-home death rate observed among these 40 patients was 30.0% (N = 12). Conclusion: CV-ports may contribute to seamless oncological care.展开更多
Objectives:To assess whether the extension of the flushing interval will increase risks of complications associated with totally implantable venous access port(TIVAP)in the off-treatment period.Methods:A retrospective...Objectives:To assess whether the extension of the flushing interval will increase risks of complications associated with totally implantable venous access port(TIVAP)in the off-treatment period.Methods:A retrospective single-center observational study was performed.Patients with a TIVAP in the off-treatment period that underwent regular flushing in our clinic were included.Data concerning patients and their TIVAPs were recorded.Patient baseline characteristics and TIVAP-related complications were analyzed.Continuous variables were analyzed by ANOVA or the Kruskal-Wallis H test.To compare the occurrence of TIVAP-related complications,the chi-square test was used;if needed,Fisher’s exact test was used.Results:Totally 607 patients were reviewed,and 563 patients were finally included.Thirteen complications were recorded,including 11 cases of catheter occlusion(1.95%),one case of port cannula rotation(0.18%),and one case of catheter tip malposition(0.18%).No device-related infection or venous thrombosis was recorded.Among these patients,the average flushing interval was 35.27±13.09 days.Patients were divided into three groups according to the flushing interval:every 28 days or less(Group 1,n=133);every 29-44 days(Group 2,n=350);and every 45 days or more(Group 3,n=80).No significant difference in catheter-related complications was found among the three groups(P>0.05).Conclusions:In the TIVAP off-treatment period,patients without any history of TIVAP-related complications during approximately one year can attempt to prolong the flushing interval to more than 4 weeks;we further suggest that 5-6 weeks may be an appropriate option for these patients.展开更多
The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devi...The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research confirmed that the inside-filling pneumatic precision centralized seed-metering device satisfied the agronomic requirements of rapeseed planting and can be a reference for the development of precision seed metering devices.展开更多
In order to solve the problem of interaction between multiple evaluation indexes of seed metering performance under multiple factors of centralized seed feeding device,a multi-objective optimization of structure based...In order to solve the problem of interaction between multiple evaluation indexes of seed metering performance under multiple factors of centralized seed feeding device,a multi-objective optimization of structure based on particle swarm optimization(PSO)algorithm was proposed in this paper.The wheat centralized seed feeding device was taken as the research object,and the experimental factors were cone angle of type hole,working speed and seed filling gap.The working process of wheat centralized seed feeding device was simulated by discrete element method(DEM).The average seed number of type hole,the variation coefficient of the average seed number of type hole,and the maximum tangential force between seed and seed feeding mechanism were selected as the evaluation indexes.Through the variance analysis of the evaluation indexes by the experimental factors,the optimization objective function was constructed.Using PSO algorithm,the multi-objective optimization was carried out for the wheat centralized seed feeding device.The optimization results show that the best structural combination parameters of the wheat centralized seed feeding device are the hole cone angle of 31.6°and the seed filling gap of 4.6 mm.The validity of the method was verified by simulation and field test.The results show that the PSO algorithm multi-objective optimization method proposed in this paper can provide a reference for the structural improvement and optimal design of the centralized seed feeding device.展开更多
In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investiga...In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investigated using EDEM simulation.Furthermore,the CFD-DEM coupling approach was applied to determine movement trajectories and airflow fields.The impacts of rapeseed varieties and rotational speed on seeding performance were investigated by bench tests.The results showed that the seed feeding quantity increased with the increase of model-hole’s length,depth and section size.Under the model-hole’s depth of 3.0 mm,the type II model-hole and model-hole’s length of 10 mm,both the variation coefficient of seed feeding quantity and hill diameter were lower which meet the seeding quantity requirement of 2 seeds in each hill.It was revealed that the seed population migrated in a large airflow velocity area and the distribution was uniform.The bench tests indicated that rapeseed varieties and rotational speed had a significant effect on the seed feeding quantity in each hill at rotational speed of 10-40 r/min.The variation coefficient of seed feeding quantity in each hill was less than 17.0%for each treatment.The hill diameter,which did not exceed 3.5 cm,tended to reduce with increasing rotational speed.The variation coefficient of seeding quantity in each row and seeding uniformity was less than 6.5%and 32.0%,respectively.Field experiments demonstrated that the seedling was 9-13 plants per meter each row for three rapeseed varieties.The variation coefficient of plants was less than 25.0%for six rows and their yields reached 2761 kg/hm2,which realized the mechanized planting requirements.The results can optimize structure of an air-assisted centralized metering system and improve seeding performance.展开更多
文摘The central solenoid is an important part of the HT-7U device. In this paper， the computational analysis of the stress and the displacement on the pre-load structures of the central solenoid have been made by the finite element analysis system COSMOS/M2.0 under room and/or operating temperature. According to the analytical results, the clip aprons and compression plates are all satisfied with safety design criteria.
文摘Background: As the prognosis of lung cancer (LC) patients improves, subcutaneously implanted central venous access device ports (CV-ports) have frequently been used for continuing chemotherapy (CC) or palliative care (PC). In this study, we examined the clinical course of LC patients with subcutaneously implanted CV-ports from the time of receiving chemotherapy to the endpoint of cancer. Materials and Methods: We retrospectively reviewed the clinical data and treatment history of LC patients with subcutaneously implanted CV-ports between June 2008 and November 2013 using clinical records and a pharmacy database. Results: Of the 132 LC patients with subcutaneously implanted CV-ports, 79 (59.8%) had CV-ports for CC (the CC group) and 53 (40.2%) had CV-ports for PC (the PC group). After CV-port implantation, LC patients in the CC group received a median of two regimens with a median of 6 cycles. The median survival time of patients in the CC and PC groups was 457 and 44 days, respectively. In the CC group, the median survival time of small cell and non-small cell LC patients was 342 (95% confidence interval, 235 - 627) and 563 (95% confidence interval, 368 - 728) days, respectively. Nine patients (6.8%) had their CV-ports removed due to complications. Forty (30.3%) of the 132 enrolled patients were referred for at-home PC. The at-home death rate observed among these 40 patients was 30.0% (N = 12). Conclusion: CV-ports may contribute to seamless oncological care.
文摘Objectives:To assess whether the extension of the flushing interval will increase risks of complications associated with totally implantable venous access port(TIVAP)in the off-treatment period.Methods:A retrospective single-center observational study was performed.Patients with a TIVAP in the off-treatment period that underwent regular flushing in our clinic were included.Data concerning patients and their TIVAPs were recorded.Patient baseline characteristics and TIVAP-related complications were analyzed.Continuous variables were analyzed by ANOVA or the Kruskal-Wallis H test.To compare the occurrence of TIVAP-related complications,the chi-square test was used;if needed,Fisher’s exact test was used.Results:Totally 607 patients were reviewed,and 563 patients were finally included.Thirteen complications were recorded,including 11 cases of catheter occlusion(1.95%),one case of port cannula rotation(0.18%),and one case of catheter tip malposition(0.18%).No device-related infection or venous thrombosis was recorded.Among these patients,the average flushing interval was 35.27±13.09 days.Patients were divided into three groups according to the flushing interval:every 28 days or less(Group 1,n=133);every 29-44 days(Group 2,n=350);and every 45 days or more(Group 3,n=80).No significant difference in catheter-related complications was found among the three groups(P>0.05).Conclusions:In the TIVAP off-treatment period,patients without any history of TIVAP-related complications during approximately one year can attempt to prolong the flushing interval to more than 4 weeks;we further suggest that 5-6 weeks may be an appropriate option for these patients.
基金the National Natural Science Foundation of China(5140518)Modern Agro-industry Technology Research Systems(CARS-13)Scientific Research Outstanding Talent and Innovation Team Foundation of Ministry of Agriculture of China,and the Key Project of Hubei Province(2014070504020240).
文摘The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research confirmed that the inside-filling pneumatic precision centralized seed-metering device satisfied the agronomic requirements of rapeseed planting and can be a reference for the development of precision seed metering devices.
基金The authors acknowledge that this work was financially supported by Collaborative Innovation Project of Anhui Colleges and Universities(GXXT-2019-036)Nature Science Fund Project of Anhui province(2008085QE217)Natural Science Fund Project of Anhui Agricultural University(2019zd09).
文摘In order to solve the problem of interaction between multiple evaluation indexes of seed metering performance under multiple factors of centralized seed feeding device,a multi-objective optimization of structure based on particle swarm optimization(PSO)algorithm was proposed in this paper.The wheat centralized seed feeding device was taken as the research object,and the experimental factors were cone angle of type hole,working speed and seed filling gap.The working process of wheat centralized seed feeding device was simulated by discrete element method(DEM).The average seed number of type hole,the variation coefficient of the average seed number of type hole,and the maximum tangential force between seed and seed feeding mechanism were selected as the evaluation indexes.Through the variance analysis of the evaluation indexes by the experimental factors,the optimization objective function was constructed.Using PSO algorithm,the multi-objective optimization was carried out for the wheat centralized seed feeding device.The optimization results show that the best structural combination parameters of the wheat centralized seed feeding device are the hole cone angle of 31.6°and the seed filling gap of 4.6 mm.The validity of the method was verified by simulation and field test.The results show that the PSO algorithm multi-objective optimization method proposed in this paper can provide a reference for the structural improvement and optimal design of the centralized seed feeding device.
基金supported by the National Natural Science Foundation of China(Grant No.31901413)the National Key Project of Research and Development Program,Ministry of Science and Technology of the People’s Republic of China(Grant No.2018YFD0301204).
文摘In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investigated using EDEM simulation.Furthermore,the CFD-DEM coupling approach was applied to determine movement trajectories and airflow fields.The impacts of rapeseed varieties and rotational speed on seeding performance were investigated by bench tests.The results showed that the seed feeding quantity increased with the increase of model-hole’s length,depth and section size.Under the model-hole’s depth of 3.0 mm,the type II model-hole and model-hole’s length of 10 mm,both the variation coefficient of seed feeding quantity and hill diameter were lower which meet the seeding quantity requirement of 2 seeds in each hill.It was revealed that the seed population migrated in a large airflow velocity area and the distribution was uniform.The bench tests indicated that rapeseed varieties and rotational speed had a significant effect on the seed feeding quantity in each hill at rotational speed of 10-40 r/min.The variation coefficient of seed feeding quantity in each hill was less than 17.0%for each treatment.The hill diameter,which did not exceed 3.5 cm,tended to reduce with increasing rotational speed.The variation coefficient of seeding quantity in each row and seeding uniformity was less than 6.5%and 32.0%,respectively.Field experiments demonstrated that the seedling was 9-13 plants per meter each row for three rapeseed varieties.The variation coefficient of plants was less than 25.0%for six rows and their yields reached 2761 kg/hm2,which realized the mechanized planting requirements.The results can optimize structure of an air-assisted centralized metering system and improve seeding performance.
