A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of fl...A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly,the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacityflow rates are pretreated; Secondly, several rules are proposed to establish the superstructuremodel of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly,the improving genetic algorithm is applied to solve the mathematical model established at the secondstep effectively, and the original optimal structure of HEN based on the maximum operation limitingcondition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat loadof heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operationcondition between the upper and down bounds of supply temperature and heat capacity flow rates canbe obtained based on the original optimal structure of HEN by means of these rules. A case studydemonstrates the method presented in this paper is effective展开更多
Purpose： Flail chest （FC） injuries represent a significant burden on trauma services because of its high morbidity and mortality. Current gold standard conservative management strategies for FC, are now being chall...Purpose： Flail chest （FC） injuries represent a significant burden on trauma services because of its high morbidity and mortality. Current gold standard conservative management strategies for FC, are now being challenged by renewed interest in surgical rib fixation. This retrospective epidemiological study sets out to evaluate FC patients, and quantify the natural history of this injury by studying the injury patterns, epidemiology and mortality of patients sustaining FC injuries admitted to a major trauma centre （MTC）. Methods： A retrospective cohort analysis has been conducted at an MTC with full trauma service. All patients （age 〉 16 years） sustaining FC were included. Patient demographics, injury characteristics and inpatient stay information were extracted. Results： Two hundred and ninety-three patients were identified, with a mean injury severity score （ISS） of 28.9 （range 9-75）, average age of 56.1 years （range of 16-100）, and a male predominance （78%）. Road traffic accidents accounted for 45% （n = 132） of injuries, whilst 44% were fall or jump from height （n = 129）. Associated lung contusion was present in 133 patients （45%） while 76% of patients were found to have 5 or more ribs involved in the flail segment （n = 223） with 96% （n = 281 ） having a unilateral FC. Inpatient treatment was required 19.9 days （range 0-150 days） with 59% of patients （n = 173） requiring intensive care unit （ICU） level care for 8.4 days （range 1-63） with 61.8% requiring mechanical ventilation （n = 107） for 10.5 days （range 1-54）, and Z8g underwent rib fixation with rib plates （n = 23）. The mortality rate was found to be 14% （n = 42）. A non-significant trend towards improved outcomes in the conservative group was found when compared with the fixation group; ventilation days （6.94 vs 10.06, p = 0.18） intensive treatment unit （ITU） length of stay （LOS） （12.56 vs 15.53, p = 0.28） and hospital LOS （32.62 vs 35.24, p = 0.69）. Conclusion： This study has successfully described the natural history of flail chest injuries, and has found a nonsignificant trend towards better outcomes with conservative management. With the cohort and management challenges now defined, work on outcome improvement can be targeted. In addition the comnarahility of results to other studies makes collaboration with other MTCs a realistic vrovosal.展开更多
基金Supported by the State Major Basic Research Department Program of China (No. G20000263) and the Deutsche Forschungs- gemeinschaft(DFG)(No. RO294/9).
文摘A new superstructure model of heat exchanger networks (HEN) with streamsplits based on rangers of streams supply temperatures and heat capacity flow rates is presented.The simultaneous optimal mathematical model of flexible HEN synthesis is established too. Firstly,the streams with rangers of supply temperatures and/or the streams with the rangers of heat capacityflow rates are pretreated; Secondly, several rules are proposed to establish the superstructuremodel of HEN with splits and the simultaneous optimal mathematical model of flexible HEN; Thirdly,the improving genetic algorithm is applied to solve the mathematical model established at the secondstep effectively, and the original optimal structure of HEN based on the maximum operation limitingcondition can be obtained easily; Finally, the rules of heat exchange unit merged and the heat loadof heat exchanger relaxed are presented, the flexible configuration of HEN satisfied the operationcondition between the upper and down bounds of supply temperature and heat capacity flow rates canbe obtained based on the original optimal structure of HEN by means of these rules. A case studydemonstrates the method presented in this paper is effective
文摘Purpose： Flail chest （FC） injuries represent a significant burden on trauma services because of its high morbidity and mortality. Current gold standard conservative management strategies for FC, are now being challenged by renewed interest in surgical rib fixation. This retrospective epidemiological study sets out to evaluate FC patients, and quantify the natural history of this injury by studying the injury patterns, epidemiology and mortality of patients sustaining FC injuries admitted to a major trauma centre （MTC）. Methods： A retrospective cohort analysis has been conducted at an MTC with full trauma service. All patients （age 〉 16 years） sustaining FC were included. Patient demographics, injury characteristics and inpatient stay information were extracted. Results： Two hundred and ninety-three patients were identified, with a mean injury severity score （ISS） of 28.9 （range 9-75）, average age of 56.1 years （range of 16-100）, and a male predominance （78%）. Road traffic accidents accounted for 45% （n = 132） of injuries, whilst 44% were fall or jump from height （n = 129）. Associated lung contusion was present in 133 patients （45%） while 76% of patients were found to have 5 or more ribs involved in the flail segment （n = 223） with 96% （n = 281 ） having a unilateral FC. Inpatient treatment was required 19.9 days （range 0-150 days） with 59% of patients （n = 173） requiring intensive care unit （ICU） level care for 8.4 days （range 1-63） with 61.8% requiring mechanical ventilation （n = 107） for 10.5 days （range 1-54）, and Z8g underwent rib fixation with rib plates （n = 23）. The mortality rate was found to be 14% （n = 42）. A non-significant trend towards improved outcomes in the conservative group was found when compared with the fixation group; ventilation days （6.94 vs 10.06, p = 0.18） intensive treatment unit （ITU） length of stay （LOS） （12.56 vs 15.53, p = 0.28） and hospital LOS （32.62 vs 35.24, p = 0.69）. Conclusion： This study has successfully described the natural history of flail chest injuries, and has found a nonsignificant trend towards better outcomes with conservative management. With the cohort and management challenges now defined, work on outcome improvement can be targeted. In addition the comnarahility of results to other studies makes collaboration with other MTCs a realistic vrovosal.
