A novel diagram-based representation approach is developed to analyze the thermodynamic efficiency and identify quickly the promising energy-use improvement for integrated fractionating and heat exchange processes in ...A novel diagram-based representation approach is developed to analyze the thermodynamic efficiency and identify quickly the promising energy-use improvement for integrated fractionating and heat exchange processes in delayed coking units. For considering temperature dependence of heat capacity and integrating fractionating and heat exchange processes, an advanced energy level composite curve is constructed by using the simulation results and a stepwise procedure. More accurate results of exergy analysis are obtained and the interaction between different components of the integrated system can be properly revealed in an integrated figure. Then the exergy calculation is performed to validate the performance of processes and to define the targets for improvement. The avoidable exergy destruction is also analyzed by applying the concepts of avoidable and unavoidable exergy destructions for the integrated system. In a case study for a Chinese refinery, the results reveal that the heat exchange between gas oil and deethanization gasoline is the most inefficient process with the highest retrofitting potential, and the lowest exergy efficiency of component in the integration system is only29.4%. The improvement potential and exergy efficiency for the fractionator are 38.1% and 97.3%, respectively.It is obvious that the fractionator is not the most promising component for improvement.展开更多
AIM:To examine the coexistence of diabetes mellitus(DM)and cataract in Hungary.The effects of DM on the cataract surgical results were also in the focus of analysis.METHODS:Statistical data analysis of the results of ...AIM:To examine the coexistence of diabetes mellitus(DM)and cataract in Hungary.The effects of DM on the cataract surgical results were also in the focus of analysis.METHODS:Statistical data analysis of the results of the Rapid Assessment of Avoidable Blindness with Diabetic Retinopathy(RAAB+DR)module conducted in Hungary in 2015.This cross-sectional,population-based,national survey included 3523 people aged 50 years and over.Participants of the survey were examined on-site.Visual acuity,main cause for visual impairment(using direct and indirect ophthalmoscopes),in case of best corrected visual acuity(BCVA)≤0.5 and blood glucose level(random test with glucometer)were examined.RESULTS:The prevalence of cataract was 23.4%,and DM was 20.0%.The occurrence of cataract steadily increased with age.Among the examined participants with DM,the prevalence of cataract was significantly(P=0.012)higher(+35%)than that in non-diabetic subjects(29.5%vs 21.8%).Following aging(OR=15.2%,P<0.001),DM proved to be the most independent influencing risk factor(OR=49.9%,P<0.001).The presence of DM was neither an influencing factor for complications of cataract surgery,nor for postoperative visual acuity.CONCLUSION:DM appears to be one of the main risk factors for developing cataract.Other risk factors,such as age,sex and environment also play an influencing role.Diabetes does not seem to affect the occurrence of cataract surgical complications.展开更多
AIM:To estimate the prevalence of blindness and visual impairment resulting from cataract in the population aged≥50 y in Hungary,and to assess the cataract surgical services.METHODS:A rapid assessment of avoidable bl...AIM:To estimate the prevalence of blindness and visual impairment resulting from cataract in the population aged≥50 y in Hungary,and to assess the cataract surgical services.METHODS:A rapid assessment of avoidable blindness(RAAB)was conducted.A total of 3523 eligible people were randomly selected and examined.Each participant underwent surgery for cataract was interviewed with regard to the year,place,and costs of the surgery.Participants with obvious cataract were asked why they had not yet undergone surgery(barriers to surgery).RESULTS:An estimated 12514 people were bilaterally blind;the visual acuity(VA)in 19293 people was<6/60,and the VA in 73962 people was<6/18 in the better eye due to cataract.An estimated 77933 eyes are blind;98067 eyes had a VA of<6/60,and an estimated 277493 eyes had a VA of<6/18 due to cataract.Almost all cataract surgeries were conducted in government hospitals.The age-and sexadjusted cataract surgical coverage with VA<3/60 in eyes was 90.0%.The rate of good visual outcome after surgery was 79.5%.Ocular comorbidity was the main cause of poor outcome(78.1%),followed by late complications(such as posterior capsule opacification)(17.2%),inadequate optical correction(3.1%),and surgical complications(1.6%).The main barrier to surgery in people with bilateral cataract and VA of<6/60 was‘need not felt’.CONCLUSION:The prevalence of visual impairment resulting from cataract is slightly higher than expected.The quality of the cataract surgical service seems adequate in Hungary.However,the number of cataract operations per year should continue to increase due to the increasing patient demands and the aging population.展开更多
Air-conditioning system consumes a large amount of electricity in residential sections,and its efficiency has drawn extensive concerns in energy-conscious era.Liquid-vapor separation is a heat transfer enhancement tec...Air-conditioning system consumes a large amount of electricity in residential sections,and its efficiency has drawn extensive concerns in energy-conscious era.Liquid-vapor separation is a heat transfer enhancement technology that can effectively improve the performance of the heat exchanger as well as the system.In this paper,a regular air-conditioning system as the baseline(system-A)and other two air-conditioning systems with liquid-vapor separation heat exchanger(system-B and system-C)are comparatively studied.The component behaviors and system performances are deeply explored by using advanced exergy analysis with a focus on quantifying how much consequences come from the variants,i.e.liquid-vapor separation.The results indicate that the system-B has large reduced exergy destruction from the compressor and condenser at cooling mode relative to the system-A.The system-C has mainly diminished exergy destruction in the compressor caused by other components relative to the system-B.At heating mode,the system-C has an enhanced system exergy efficiency of 9.6%over the system-A,and it also has the decreased avoidable exergy destruction which is dominantly contributed by the compressor and evaporator.Furthermore,it is found that liquid-vapor separation mainly benefits the compressor and outdoor heat exchanger where it locates,leading to the system performance improvements.展开更多
基金Supported by the National Natural Science Foundation of China(21473126)the Specialized Research Fund for the Doctoral Program of Higher Education(20124219110002)China Postdoctoral Science Foundation(2015M582285)
文摘A novel diagram-based representation approach is developed to analyze the thermodynamic efficiency and identify quickly the promising energy-use improvement for integrated fractionating and heat exchange processes in delayed coking units. For considering temperature dependence of heat capacity and integrating fractionating and heat exchange processes, an advanced energy level composite curve is constructed by using the simulation results and a stepwise procedure. More accurate results of exergy analysis are obtained and the interaction between different components of the integrated system can be properly revealed in an integrated figure. Then the exergy calculation is performed to validate the performance of processes and to define the targets for improvement. The avoidable exergy destruction is also analyzed by applying the concepts of avoidable and unavoidable exergy destructions for the integrated system. In a case study for a Chinese refinery, the results reveal that the heat exchange between gas oil and deethanization gasoline is the most inefficient process with the highest retrofitting potential, and the lowest exergy efficiency of component in the integration system is only29.4%. The improvement potential and exergy efficiency for the fractionator are 38.1% and 97.3%, respectively.It is obvious that the fractionator is not the most promising component for improvement.
基金Supported by Sight First Research Grant(No.SF1825/UND)from Lions Clubs International Foundation,Oak Brook(IL),USA。
文摘AIM:To examine the coexistence of diabetes mellitus(DM)and cataract in Hungary.The effects of DM on the cataract surgical results were also in the focus of analysis.METHODS:Statistical data analysis of the results of the Rapid Assessment of Avoidable Blindness with Diabetic Retinopathy(RAAB+DR)module conducted in Hungary in 2015.This cross-sectional,population-based,national survey included 3523 people aged 50 years and over.Participants of the survey were examined on-site.Visual acuity,main cause for visual impairment(using direct and indirect ophthalmoscopes),in case of best corrected visual acuity(BCVA)≤0.5 and blood glucose level(random test with glucometer)were examined.RESULTS:The prevalence of cataract was 23.4%,and DM was 20.0%.The occurrence of cataract steadily increased with age.Among the examined participants with DM,the prevalence of cataract was significantly(P=0.012)higher(+35%)than that in non-diabetic subjects(29.5%vs 21.8%).Following aging(OR=15.2%,P<0.001),DM proved to be the most independent influencing risk factor(OR=49.9%,P<0.001).The presence of DM was neither an influencing factor for complications of cataract surgery,nor for postoperative visual acuity.CONCLUSION:DM appears to be one of the main risk factors for developing cataract.Other risk factors,such as age,sex and environment also play an influencing role.Diabetes does not seem to affect the occurrence of cataract surgical complications.
基金Supported by SightFirst grant(No.SF 1825/UND)from Lions Clubs International Foundation,Oak Brook,IL,USA.
文摘AIM:To estimate the prevalence of blindness and visual impairment resulting from cataract in the population aged≥50 y in Hungary,and to assess the cataract surgical services.METHODS:A rapid assessment of avoidable blindness(RAAB)was conducted.A total of 3523 eligible people were randomly selected and examined.Each participant underwent surgery for cataract was interviewed with regard to the year,place,and costs of the surgery.Participants with obvious cataract were asked why they had not yet undergone surgery(barriers to surgery).RESULTS:An estimated 12514 people were bilaterally blind;the visual acuity(VA)in 19293 people was<6/60,and the VA in 73962 people was<6/18 in the better eye due to cataract.An estimated 77933 eyes are blind;98067 eyes had a VA of<6/60,and an estimated 277493 eyes had a VA of<6/18 due to cataract.Almost all cataract surgeries were conducted in government hospitals.The age-and sexadjusted cataract surgical coverage with VA<3/60 in eyes was 90.0%.The rate of good visual outcome after surgery was 79.5%.Ocular comorbidity was the main cause of poor outcome(78.1%),followed by late complications(such as posterior capsule opacification)(17.2%),inadequate optical correction(3.1%),and surgical complications(1.6%).The main barrier to surgery in people with bilateral cataract and VA of<6/60 was‘need not felt’.CONCLUSION:The prevalence of visual impairment resulting from cataract is slightly higher than expected.The quality of the cataract surgical service seems adequate in Hungary.However,the number of cataract operations per year should continue to increase due to the increasing patient demands and the aging population.
基金supported by State Key Program of National Natural Science Foundation of China(51736005)Science and Technology Program of Guangzhou(201704030108)+1 种基金Foshan Municipal Science and Technology Bureau Project(2015IT100162)Guangdong Special Support Program(2017TX04N371)。
文摘Air-conditioning system consumes a large amount of electricity in residential sections,and its efficiency has drawn extensive concerns in energy-conscious era.Liquid-vapor separation is a heat transfer enhancement technology that can effectively improve the performance of the heat exchanger as well as the system.In this paper,a regular air-conditioning system as the baseline(system-A)and other two air-conditioning systems with liquid-vapor separation heat exchanger(system-B and system-C)are comparatively studied.The component behaviors and system performances are deeply explored by using advanced exergy analysis with a focus on quantifying how much consequences come from the variants,i.e.liquid-vapor separation.The results indicate that the system-B has large reduced exergy destruction from the compressor and condenser at cooling mode relative to the system-A.The system-C has mainly diminished exergy destruction in the compressor caused by other components relative to the system-B.At heating mode,the system-C has an enhanced system exergy efficiency of 9.6%over the system-A,and it also has the decreased avoidable exergy destruction which is dominantly contributed by the compressor and evaporator.Furthermore,it is found that liquid-vapor separation mainly benefits the compressor and outdoor heat exchanger where it locates,leading to the system performance improvements.
