In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE inc...In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.展开更多
Negative-pressure wound therapy(NPWT) has been a successful modality of wound management which is in widespread use in several surgical fields. The main mechanisms of action thought to play a role in enhancing wound h...Negative-pressure wound therapy(NPWT) has been a successful modality of wound management which is in widespread use in several surgical fields. The main mechanisms of action thought to play a role in enhancing wound healing and preventing surgical site infection are macrodeformation and microdeformation of the wound bed, fluid removal, and stabilization of the wound environment. Due to the devastating consequences of infection in the setting of joint arthroplasty, there has been some interest in the use of NPWT following total hip arthroplasty and total knee arthroplasty. However, there is still a scarcity of data reporting on the use of NPWT within this field and most studies are limited by small sample sizes, high variability of clinical settings and end-points. There is little evidence to support the use of NPWT as an adjunctive treatment for surgical wound drainage, and for this reason surgical intervention should not be delayed when indicated. The prophylactic use of NPWT after arthroplasty in patients that are at high risk for postoperative wound drainage appears to have the strongest clinical evidence. Several clinical trialsincluding single-use NPWT devices for this purpose are currently in progress and this may soon be incorporated in clinical guidelines as a mean to prevent periprosthetic joint infections.展开更多
AIM To evaluate the safety and feasibility of a new technology combining low-pressure pneumoperitoneum(LPP) and abdominal wall lift(AWL) in laparoscopic total mesorectal excision(TME) for rectal cancer.METHODS From No...AIM To evaluate the safety and feasibility of a new technology combining low-pressure pneumoperitoneum(LPP) and abdominal wall lift(AWL) in laparoscopic total mesorectal excision(TME) for rectal cancer.METHODS From November 2015 to July 2017,26 patients underwent laparoscopic TME for rectal cancer using LPP(6-8 mm Hg) with subcutaneous AWL in Qilu Hospital of Shandong University,Jinan,China.Clinical data regarding patients' demographics,intraoperative monitoring indices,operation-related indices andpathological outcomes were prospectively collected.RESULTS Laparoscopic TME was performed in 26 cases(14 anterior resection and 12 abdominoperineal resection) successfully,without conversion to open or laparoscopic surgery with standard-pressure pneumoperitoneum.Intraoperative monitoring showed stable heart rate,blood pressure and paw airway pressure.The mean operative time was 194.29 ± 41.27 min(range:125-270 min) and 200.41 ± 20.56 min(range:170-230 min) for anterior resection and abdominoperineal resection,respectively.The mean number of lymph nodes harvested was 16.71 ± 5.06(range:7-27).There was no positive circumferential or distal resection margin.No local recurrence was observed during a median follow-up period of 11.96 ± 5.55 mo(range:5-23 mo).CONCLUSION LPP combined with AWL is safe and feasible for laparoscopic TME.The technique can provide satisfactory exposure of the operative field and stable operative monitoring indices.展开更多
A novel operation of batch distillation-combination of varyingcolumn pressure and total reflux-total efflux is studiedexperimentally. In the operation, the product is accumulated at thetop of the column under total re...A novel operation of batch distillation-combination of varyingcolumn pressure and total reflux-total efflux is studiedexperimentally. In the operation, the product is accumulated at thetop of the column under total reflux and then drained off completely,and the column pressure is varying in the whole process. This processhas been industrialized successfully with large profits. Theconventional model of batch distillation is improved by this methodeffectively: the separation efficiency and the yield of product areincreased greatly, the operation time is shortened and the productioncost is cut down. Moreover, the amount of condensation water isdecreased and the over-high reboiler temperature is lowered.展开更多
Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline s...Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2. the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Co γ-rays up to 2.3×104Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.展开更多
By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazi...By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.展开更多
The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have fo...The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.展开更多
Wheat （Triticum aestivum） seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The sur...Wheat （Triticum aestivum） seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ,--20% by 6 min treatment with H2O/O2 plasma with respect to control.展开更多
Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produc...Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory.展开更多
With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becom...With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.展开更多
基金The authors would like to acknowledge the National Natural Science Foundation of China(Grant Nos.11802137,11702143)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX19_0292)+1 种基金the Natural Science Foundation for Young Scientists of Jiangsu Province of China(Grant No.BK20190468)the Fundamental Research Funds for the Central Universities(Grant Nos.30918011343,30919011259,309190112A1).
文摘In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.
文摘Negative-pressure wound therapy(NPWT) has been a successful modality of wound management which is in widespread use in several surgical fields. The main mechanisms of action thought to play a role in enhancing wound healing and preventing surgical site infection are macrodeformation and microdeformation of the wound bed, fluid removal, and stabilization of the wound environment. Due to the devastating consequences of infection in the setting of joint arthroplasty, there has been some interest in the use of NPWT following total hip arthroplasty and total knee arthroplasty. However, there is still a scarcity of data reporting on the use of NPWT within this field and most studies are limited by small sample sizes, high variability of clinical settings and end-points. There is little evidence to support the use of NPWT as an adjunctive treatment for surgical wound drainage, and for this reason surgical intervention should not be delayed when indicated. The prophylactic use of NPWT after arthroplasty in patients that are at high risk for postoperative wound drainage appears to have the strongest clinical evidence. Several clinical trialsincluding single-use NPWT devices for this purpose are currently in progress and this may soon be incorporated in clinical guidelines as a mean to prevent periprosthetic joint infections.
基金Supported by the Special Found for Taishan Scholar Project of Shandong Province,China
文摘AIM To evaluate the safety and feasibility of a new technology combining low-pressure pneumoperitoneum(LPP) and abdominal wall lift(AWL) in laparoscopic total mesorectal excision(TME) for rectal cancer.METHODS From November 2015 to July 2017,26 patients underwent laparoscopic TME for rectal cancer using LPP(6-8 mm Hg) with subcutaneous AWL in Qilu Hospital of Shandong University,Jinan,China.Clinical data regarding patients' demographics,intraoperative monitoring indices,operation-related indices andpathological outcomes were prospectively collected.RESULTS Laparoscopic TME was performed in 26 cases(14 anterior resection and 12 abdominoperineal resection) successfully,without conversion to open or laparoscopic surgery with standard-pressure pneumoperitoneum.Intraoperative monitoring showed stable heart rate,blood pressure and paw airway pressure.The mean operative time was 194.29 ± 41.27 min(range:125-270 min) and 200.41 ± 20.56 min(range:170-230 min) for anterior resection and abdominoperineal resection,respectively.The mean number of lymph nodes harvested was 16.71 ± 5.06(range:7-27).There was no positive circumferential or distal resection margin.No local recurrence was observed during a median follow-up period of 11.96 ± 5.55 mo(range:5-23 mo).CONCLUSION LPP combined with AWL is safe and feasible for laparoscopic TME.The technique can provide satisfactory exposure of the operative field and stable operative monitoring indices.
文摘A novel operation of batch distillation-combination of varyingcolumn pressure and total reflux-total efflux is studiedexperimentally. In the operation, the product is accumulated at thetop of the column under total reflux and then drained off completely,and the column pressure is varying in the whole process. This processhas been industrialized successfully with large profits. Theconventional model of batch distillation is improved by this methodeffectively: the separation efficiency and the yield of product areincreased greatly, the operation time is shortened and the productioncost is cut down. Moreover, the amount of condensation water isdecreased and the over-high reboiler temperature is lowered.
基金Supported by Science and Technology Development Foundation of Shanghai under Grant (No.98JC14004) partly by National Natural
文摘Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2. the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Co γ-rays up to 2.3×104Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201003023)~~
文摘By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.
文摘The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.
基金Partial financial support has been provided by the Ministry of Science and Technology, Republic of Bangladesh: 39.00.0000.09.06.79.2017/2/98ESBangladesh Council for Scientific and Industrial Research (BCSIR) for providing Professor Abdullah Al-Muti Sharfuddin fellowship
文摘Wheat （Triticum aestivum） seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ,--20% by 6 min treatment with H2O/O2 plasma with respect to control.
基金Supported by Tianjin Institute of Urban Construction(03046)
文摘Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory.
基金Supported bythe Doctoral Foundation of Education Ministry of China (No.20040056037) .
文摘With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.
