The performance degradation rates of the missile tank are generally time-varying functions uneasily evaluated by general classical evaluation methods. This paper develops a segmented nonlinear accelerated degradation ...The performance degradation rates of the missile tank are generally time-varying functions uneasily evaluated by general classical evaluation methods. This paper develops a segmented nonlinear accelerated degradation model （SNADM） based on the equivalent method of accumulative damage theory, which tackles the problem that product life is difficult to be determined with degradation rate being a function of the variable of time. A segmented expression of the function of population accumulative degradation is derived. And combined with nonlinear function, an accelerated degradation function, i.e., SNADM is obtained. The parameters of the SNADM are identified by numerical iteration, and the statistical function of degradation track is extrapolated. The reliability function is determined through the type of random process of the degradation distribution. Then an evaluation of product storage life is undertaken by combining the statistical function of degradation track, reliability function and threshold. An example of a missile tank undergoes a step-down stress accelerated degradation test （SDSADT）, in which the results with the SNADM and the classical method are evaluated and compared. The technology introduced is validated with the resultant coincidence of both evaluated and field storage lives.展开更多
Double-crossed-step-stress(DCSS) accelerated life test(ALT) method is widely used for estimating the lifetime of products with high reliability and long lifetime. In order to further reduce the test time and test cost...Double-crossed-step-stress(DCSS) accelerated life test(ALT) method is widely used for estimating the lifetime of products with high reliability and long lifetime. In order to further reduce the test time and test cost, a double-synchronous-step-stress(DSSS) ALT method which combines a double-synchronous-step-downstress(DSSDS) ALT method and a double-synchronous-step-up-stress(DSSUS) ALT method is proposed. The accelerated stresses decrease and increase in a synchronous way with one step in the DSSDS-ALT and DSSUSALT methods, respectively. Monte Carlo method is adopted to simulate the two methods, and the validity and efficiency of them are demonstrated by the simulation results. In addition, a comparison analysis of efficiency between DSSDS-ALT method and DSSUS-ALT method is carried out. The result shows that the DSSDS-ALT method compared with the DSSUS-ALT method can significantly improve the test efficiency under the same test condition.展开更多
AIM:To investigate the predictors of success in stepdown of proton pump inhibitor and to assess the quality of life(QOL).METHODS:Patients who had heartburn twice a week or more were treated with 20 mg omeprazole(OPZ) ...AIM:To investigate the predictors of success in stepdown of proton pump inhibitor and to assess the quality of life(QOL).METHODS:Patients who had heartburn twice a week or more were treated with 20 mg omeprazole(OPZ) once daily for 8 wk as an initial therapy(study 1).Patients whose heartburn decreased to once a week or less at the end of the initial therapy were enrolled in study 2 and treated with 10 mg OPZ as maintenance therapy for an additional 6 mo(study 2).QOL was in-vestigated using the gastrointestinal symptom rating scale(GSRS)before initial therapy,after both 4 and 8 wk of initial therapy,and at 1,2,3,and 6 mo after starting maintenance therapy.RESULTS:In study 1,108 patients were analyzed.Their characteristics were as follows;median age:63(range: 20-88)years,sex:46 women and 62 men.The success rate of the initial therapy was 76%.In the patients with successful initial therapy,abdominal pain,indigestion and reflux GSRS scores were improved.In study 2,83 patients were analyzed.Seventy of 83 patients completed the study 2 protocol.In the per-protocol analysis,80%of 70 patients were successful for stepdown.On multivariate analysis of baseline demographic data and clinical information,no previous treatment for gastroesophageal reflux disease(GERD)[odds ratio (OR)0.255,95%CI:0.06-0.98]and a lower indigestion score in GSRS at the beginning of step-down therapy(OR 0.214,95%CI:0.06-0.73)were found to be the predictors of successful step-down therapy.The improved GSRS scores by initial therapy were maintained through the step-down therapy.CONCLUSION:OPZ was effective for most GERD patients.However,those who have had previous treatment for GERD and experience dyspepsia before stepdown require particular monitoring for relapse.展开更多
The response to single heat treatment and Step-down heat (SDH) treatment in vitro of V79 and L cells was studied. Colony-forming ability was assayed in medium after treatment in vitro. Time-response curves were establ...The response to single heat treatment and Step-down heat (SDH) treatment in vitro of V79 and L cells was studied. Colony-forming ability was assayed in medium after treatment in vitro. Time-response curves were established and subjected to Arrhenius analysis. The Arrhenius curves showed inflection points at 43℃ for V79 cells and at 42℃ for L cells. The activation energies were 145 kcal/mole and 400 kcal/mole above and below 43℃ (P<0.05), respectively, for V79 cells, while 160 kcal/mole and 300 kcal/mole above and below 42℃ (P<0.05), respectively, for L cells. Thermosensitivity of L cells are markedly higher than V79 cells. Both V79 and L cells were sensitized by SDH. The SDH effect was characterized by a reduction in shoulder (an addition effect to sublethal damage), an increase in slope (thermosensitization), and the delay and disappearance of thermotolerant 'tail' for V79 and L cells at 45℃ to 40℃ and 44℃ to 42℃ SDH treatment respectively. Particularly, 42℃ to 39℃ or 42℃ to 40℃ SDH for L cells resulted in thermosensitization effect up to a factor of 7.1 or 2.7, respectively. The effect was quantified by thermorsensitization ratio (TSR), defined as T0 single heated/T0SDH-heated. The relative ratio was much higher for V79 than for L cells. Heat killing with SDH characterized by Arrhenius analysis showed that Step-down heating reduced the activation energy for heat killing more than single heating. The decrease of activation energy for L cells was markedly greater than for V79. These data suggest that greater cellular sensitivity under step-down heating conditions may reflect a different mechanism for cell killing.展开更多
A novel high step-down non-isolated DC-DC converter has been proposed. The proposed converter consists of highly efficient non-isolated cell converters using bidirectional semiconductor power devices, and these cell c...A novel high step-down non-isolated DC-DC converter has been proposed. The proposed converter consists of highly efficient non-isolated cell converters using bidirectional semiconductor power devices, and these cell converters are connected in ISOP （input series and output parallel）. The non-isolated ISOP converter achieves high step-down ratio of D/N, operating N cell converters under the duty ratio olD. Availability of the proposed converter has been shown by developing the 48 V-12 V laboratory prototype using two 24 V-12 V cell converters. Design consideration for the 48 V-3 V multicellular converter using four 12 V-3 V cell converters has been also conducted, and the potential to approach the efficiency of 97% has been discussed. The proposed topology is suitable for the POL （point of load） converters in the highly efficient next generation DC distribution system for data centers.展开更多
A key challenge in food drying is achieving an optimal balance between processing efficiency,energy consumption,and maintaining high quality in the final product.This study investigates three drying methods for mango ...A key challenge in food drying is achieving an optimal balance between processing efficiency,energy consumption,and maintaining high quality in the final product.This study investigates three drying methods for mango slices:conventional hot air drying(HA),far-infrared combined hot air drying(FIRHA),and step-down temperature FIRHA.The effects of various operating parameters were analyzed,including drying medium temperature and the influence of far-infrared assistance,on the drying kinetics and quality attributes of the mango slices.The quality attributes assessed include color,shrinkage percentage,texture profile,water activity,microstructure,and energy consumption.The results indicate that the drying rates for FIRHA were significantly higher than those for HA.Mango slices dried using FIRHA and step-down temperature FIRHA exhibited greater lightness and greenness,along with increased crispness,while demonstrating lower yellowness compared to those dried by HA.The far-infrared assistance resulted in larger pore sizes and a higher void area fraction in the mango slices,but it also led to reduced hardness and shrinkage percentage compared to those dried using HA.In terms of specific energy consumption,the electric heater consumed significantly more energy than the far-infrared radiator and blower.Additionally,the total specific energy consumption of step-down temperature FIRHA was lower than that of both HA and FIRHA under all drying conditions.Based on these findings,this study recommends using step-down temperature FIRHA at 90℃ for 1 h for the effective drying of mango slices,offering an optimal solution to the core challenges in the field.Ultimately,this work provides a valuable framework and empirical evidence for the adoption of hybrid drying technologies,contributing significantly to the fields of food engineering and sustainable agricultural processing.展开更多
The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color diffe...The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color difference(ΔE*),Panax notoginseng saponins(PNS)content,and ginsenosides content(R1,Rg1,Re,Rd,Rb1)of Panax notoginseng roots were evaluated.The drying time was significantly affected by the drying temperature followed by the relative humidity(RH)of the drying air.Special combination of drying conditions,i.e.,drying temperature of 50°C,relative humidity of 40%for 3 h and then continuous dehumidification from 40%to 8%allowed to shorten the drying time by 25%compared to drying at the same temperature and continuous dehumidification.The longer was the drying time under constant high RH of drying air,the lower was the RR of dried samples.The step-down RH strategy contributed to the formation of a porous structure,enhancement of drying efficiency and quality improvement.Generally,the ginsenosides content increased with the increase in temperature,while no obvious trend was recorded for ginsenoside R1.The contents of the ginsenoside R1,Rg1,Rb1 and PNS decreased with the increase in the drying time under constant high RH.Taking into account the drying time,energy consumption and quality attributes,drying at the temperature of 50°C,constant RH of 40%for 3 h and then step-down RH from 40%to 8%was proposed as the most favorable combination of drying conditions for dehydration of whole Panax notoginseng roots.展开更多
文摘The performance degradation rates of the missile tank are generally time-varying functions uneasily evaluated by general classical evaluation methods. This paper develops a segmented nonlinear accelerated degradation model （SNADM） based on the equivalent method of accumulative damage theory, which tackles the problem that product life is difficult to be determined with degradation rate being a function of the variable of time. A segmented expression of the function of population accumulative degradation is derived. And combined with nonlinear function, an accelerated degradation function, i.e., SNADM is obtained. The parameters of the SNADM are identified by numerical iteration, and the statistical function of degradation track is extrapolated. The reliability function is determined through the type of random process of the degradation distribution. Then an evaluation of product storage life is undertaken by combining the statistical function of degradation track, reliability function and threshold. An example of a missile tank undergoes a step-down stress accelerated degradation test （SDSADT）, in which the results with the SNADM and the classical method are evaluated and compared. The technology introduced is validated with the resultant coincidence of both evaluated and field storage lives.
基金the National Natural Science Foundation of China(Nos.51265025 and 51665029)
文摘Double-crossed-step-stress(DCSS) accelerated life test(ALT) method is widely used for estimating the lifetime of products with high reliability and long lifetime. In order to further reduce the test time and test cost, a double-synchronous-step-stress(DSSS) ALT method which combines a double-synchronous-step-downstress(DSSDS) ALT method and a double-synchronous-step-up-stress(DSSUS) ALT method is proposed. The accelerated stresses decrease and increase in a synchronous way with one step in the DSSDS-ALT and DSSUSALT methods, respectively. Monte Carlo method is adopted to simulate the two methods, and the validity and efficiency of them are demonstrated by the simulation results. In addition, a comparison analysis of efficiency between DSSDS-ALT method and DSSUS-ALT method is carried out. The result shows that the DSSDS-ALT method compared with the DSSUS-ALT method can significantly improve the test efficiency under the same test condition.
文摘AIM:To investigate the predictors of success in stepdown of proton pump inhibitor and to assess the quality of life(QOL).METHODS:Patients who had heartburn twice a week or more were treated with 20 mg omeprazole(OPZ) once daily for 8 wk as an initial therapy(study 1).Patients whose heartburn decreased to once a week or less at the end of the initial therapy were enrolled in study 2 and treated with 10 mg OPZ as maintenance therapy for an additional 6 mo(study 2).QOL was in-vestigated using the gastrointestinal symptom rating scale(GSRS)before initial therapy,after both 4 and 8 wk of initial therapy,and at 1,2,3,and 6 mo after starting maintenance therapy.RESULTS:In study 1,108 patients were analyzed.Their characteristics were as follows;median age:63(range: 20-88)years,sex:46 women and 62 men.The success rate of the initial therapy was 76%.In the patients with successful initial therapy,abdominal pain,indigestion and reflux GSRS scores were improved.In study 2,83 patients were analyzed.Seventy of 83 patients completed the study 2 protocol.In the per-protocol analysis,80%of 70 patients were successful for stepdown.On multivariate analysis of baseline demographic data and clinical information,no previous treatment for gastroesophageal reflux disease(GERD)[odds ratio (OR)0.255,95%CI:0.06-0.98]and a lower indigestion score in GSRS at the beginning of step-down therapy(OR 0.214,95%CI:0.06-0.73)were found to be the predictors of successful step-down therapy.The improved GSRS scores by initial therapy were maintained through the step-down therapy.CONCLUSION:OPZ was effective for most GERD patients.However,those who have had previous treatment for GERD and experience dyspepsia before stepdown require particular monitoring for relapse.
文摘The response to single heat treatment and Step-down heat (SDH) treatment in vitro of V79 and L cells was studied. Colony-forming ability was assayed in medium after treatment in vitro. Time-response curves were established and subjected to Arrhenius analysis. The Arrhenius curves showed inflection points at 43℃ for V79 cells and at 42℃ for L cells. The activation energies were 145 kcal/mole and 400 kcal/mole above and below 43℃ (P<0.05), respectively, for V79 cells, while 160 kcal/mole and 300 kcal/mole above and below 42℃ (P<0.05), respectively, for L cells. Thermosensitivity of L cells are markedly higher than V79 cells. Both V79 and L cells were sensitized by SDH. The SDH effect was characterized by a reduction in shoulder (an addition effect to sublethal damage), an increase in slope (thermosensitization), and the delay and disappearance of thermotolerant 'tail' for V79 and L cells at 45℃ to 40℃ and 44℃ to 42℃ SDH treatment respectively. Particularly, 42℃ to 39℃ or 42℃ to 40℃ SDH for L cells resulted in thermosensitization effect up to a factor of 7.1 or 2.7, respectively. The effect was quantified by thermorsensitization ratio (TSR), defined as T0 single heated/T0SDH-heated. The relative ratio was much higher for V79 than for L cells. Heat killing with SDH characterized by Arrhenius analysis showed that Step-down heating reduced the activation energy for heat killing more than single heating. The decrease of activation energy for L cells was markedly greater than for V79. These data suggest that greater cellular sensitivity under step-down heating conditions may reflect a different mechanism for cell killing.
文摘A novel high step-down non-isolated DC-DC converter has been proposed. The proposed converter consists of highly efficient non-isolated cell converters using bidirectional semiconductor power devices, and these cell converters are connected in ISOP （input series and output parallel）. The non-isolated ISOP converter achieves high step-down ratio of D/N, operating N cell converters under the duty ratio olD. Availability of the proposed converter has been shown by developing the 48 V-12 V laboratory prototype using two 24 V-12 V cell converters. Design consideration for the 48 V-3 V multicellular converter using four 12 V-3 V cell converters has been also conducted, and the potential to approach the efficiency of 97% has been discussed. The proposed topology is suitable for the POL （point of load） converters in the highly efficient next generation DC distribution system for data centers.
基金Faculty of Engineering and the Faculty of Science and Technology at Rajamangala University of Technology Phra Nakhon for their support in providing research tools and facilities.
文摘A key challenge in food drying is achieving an optimal balance between processing efficiency,energy consumption,and maintaining high quality in the final product.This study investigates three drying methods for mango slices:conventional hot air drying(HA),far-infrared combined hot air drying(FIRHA),and step-down temperature FIRHA.The effects of various operating parameters were analyzed,including drying medium temperature and the influence of far-infrared assistance,on the drying kinetics and quality attributes of the mango slices.The quality attributes assessed include color,shrinkage percentage,texture profile,water activity,microstructure,and energy consumption.The results indicate that the drying rates for FIRHA were significantly higher than those for HA.Mango slices dried using FIRHA and step-down temperature FIRHA exhibited greater lightness and greenness,along with increased crispness,while demonstrating lower yellowness compared to those dried by HA.The far-infrared assistance resulted in larger pore sizes and a higher void area fraction in the mango slices,but it also led to reduced hardness and shrinkage percentage compared to those dried using HA.In terms of specific energy consumption,the electric heater consumed significantly more energy than the far-infrared radiator and blower.Additionally,the total specific energy consumption of step-down temperature FIRHA was lower than that of both HA and FIRHA under all drying conditions.Based on these findings,this study recommends using step-down temperature FIRHA at 90℃ for 1 h for the effective drying of mango slices,offering an optimal solution to the core challenges in the field.Ultimately,this work provides a valuable framework and empirical evidence for the adoption of hybrid drying technologies,contributing significantly to the fields of food engineering and sustainable agricultural processing.
基金supported in part by the Hebei Province Key Research and Development Project(Grant No.203777119D,19227210D)in part by the Scientific Research Projects of Universities in Hebei Province(Grant No.ZD2021056)in part by the Hebei Province College and Middle School Students Science and Technology Innovation Ability Cultivation Project(Grant No.2021H060505)and part by China Agriculture Research System of MOF and MARA(CARS-21).
文摘The effects of temperature and step-down relative humidity controlled hot-air drying(THC-HAD)on the drying kinetics,energy efficiency and quality,i.e.,rehydration ratio(RR),color parameters(L*,a*,b*),total color difference(ΔE*),Panax notoginseng saponins(PNS)content,and ginsenosides content(R1,Rg1,Re,Rd,Rb1)of Panax notoginseng roots were evaluated.The drying time was significantly affected by the drying temperature followed by the relative humidity(RH)of the drying air.Special combination of drying conditions,i.e.,drying temperature of 50°C,relative humidity of 40%for 3 h and then continuous dehumidification from 40%to 8%allowed to shorten the drying time by 25%compared to drying at the same temperature and continuous dehumidification.The longer was the drying time under constant high RH of drying air,the lower was the RR of dried samples.The step-down RH strategy contributed to the formation of a porous structure,enhancement of drying efficiency and quality improvement.Generally,the ginsenosides content increased with the increase in temperature,while no obvious trend was recorded for ginsenoside R1.The contents of the ginsenoside R1,Rg1,Rb1 and PNS decreased with the increase in the drying time under constant high RH.Taking into account the drying time,energy consumption and quality attributes,drying at the temperature of 50°C,constant RH of 40%for 3 h and then step-down RH from 40%to 8%was proposed as the most favorable combination of drying conditions for dehydration of whole Panax notoginseng roots.
