Freeze-drying of structurally heterogeneous biomaterials such as porcine aorta presents considerable modeling challenges due to their inherent multilayer composition and moving sublimation interfaces.Conventional mode...Freeze-drying of structurally heterogeneous biomaterials such as porcine aorta presents considerable modeling challenges due to their inherent multilayer composition and moving sublimation interfaces.Conventional models often overlook structural anisotropy and dynamic boundary progression,while experimental determination of key parameters under cryogenic conditions remains difficult.To address these,this study develops a heat and mass transfer model incorporating a dynamic node strategy for the sublimation interface,which effectively handles continuous computational domain deformation.Additionally,specialized fixed nodes were incorporated to adapt to the multilayer structure and its spatially varying thermophysical properties.A novel non-contact gravimetric system was introduced to monitor mass loss in real time without disrupting vacuum,enabling accurate experimental validation.Combined with dehydration data,the model quantified critical parameters including effective thermal conductivity of the dried layer,vapor diffusivity,and sublimation mass transfer resistance.The results show that the migration of the sublimation fronts from both the inner and outer tunics toward the tunica media significantly alters the drying kinetics and heat-mass transfer characteristics.The proposed approach provides an adaptable and predictive framework for simulating freeze-drying processes in structurally heterogeneous systems with spatially varying thermophysical properties.展开更多
This study experimentally investigates the operational performance of a scroll compressor using R513A to expand its application range as a substitute for R134a.A vapor compression heat pump test platform was establish...This study experimentally investigates the operational performance of a scroll compressor using R513A to expand its application range as a substitute for R134a.A vapor compression heat pump test platform was established to analyze the variation trends of heating capacity,refrigerant mass flow rate,compressor power consumption,and current by controlling the compressor inlet and outlet pressures(i.e.,evaporating and condensing temperatures).The results indicate that both heating capacity and refrigerant mass flow rate decrease with increasing pressure ratio.Compressor power consumption and current initially increase and then decrease with rising evaporating temperature,whereas they exhibit an approximately linear positive correlation with condensing temperature.Based on the experimental data,a polynomial model with pressure ratio as the independent variable was developed.This model predicts heating capacity,mass flow rate,power consumption,and current with high accuracy,showing an average deviation of less than 2%.However,the model’s applicability is significantly influenced by evaporating and condensing temperatures.Therefore,an enhanced 10-coefficient polynomial model,incorporating both evaporating and condensing temperatures as independent variables,was established.This improved model eliminates operational limitations and demonstrates superior prediction performance,with an average deviation of±1.44%for compressor performance parameters,confirming its practical value for engineering applications.展开更多
The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression...The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.展开更多
In order to ensure the safe operation of the compressors used in water chillers,in the present study some interlock protections have been added to the related design.These include a low pressure protection,a high pres...In order to ensure the safe operation of the compressors used in water chillers,in the present study some interlock protections have been added to the related design.These include a low pressure protection,a high pressure protection,an exhaust temperature protection and a differential pressure protection.Some tests have been conducted by tuning the saturation suction and exhaust temperatures of the compressor through adjustment of the cold source outlet temperature and the ambient temperature.The results show that the ambient temperature increases with decreasing device load and increasing fan speed under the same saturated suction temperature;the device refrigerating capacity steps up with augmenting load and dropping saturation exhaust temperature,while it is not greatly affected by the fan speed.Moreover,the Energy efficiency ratio(COP)decreases with the rise of the saturation exhaust temperature.This parameter is not affected much by the device load and fan speed at high saturation exhaust temperature,while it improves on increasing the device load and decreasing the fan speed at low saturation exhaust temperature.展开更多
The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refr...The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refrigerant undergoing condensation.In particular four theoretical single-phase flow and three multi-phase flow models have been used in this regard.The experimental results show that:the Oliver et al.criterion equation overestimates the experimental results as its accuracy is significantly affected by the specific conditions realized inside micro-fin tubes;the Miyara et al.criterion equation prediction error is less than 15%;the Cavallini et al.approach gives the highest prediction accuracy;the Goto et al.model overestimates the test data.Such results are critically discussed and some indications for the improvement of such models are provided.展开更多
BACKGROUNDEctopic thyroid at the base of the tongue is a rare congenital condition, and it iseven rarer to have clinical symptoms and require surgical intervention. Thisdisease is easily misdiagnosed preoperatively. T...BACKGROUNDEctopic thyroid at the base of the tongue is a rare congenital condition, and it iseven rarer to have clinical symptoms and require surgical intervention. Thisdisease is easily misdiagnosed preoperatively. This article reports the diagnosis,surgical treatment, and follow-up of a case of lingual thyroid.CASE SUMMARYThe patient was a 54-year-old woman who presented with laryngeal foreign bodysensation and dysphagia for 20 d. The lingual thyroid was considered for generalexamination, and surgery was performed to transpose the lingual thyroid to theright submaxillary region. Pathological analysis confirmed thyroid tissue. Thepatient experienced complete remission after surgery, but developed hypothyroidismand required thyroid hormone replacement therapy, and her thyroidfunction gradually recovered over time.CONCLUSIONWe report a rare case of lingual thyroid with marked laryngeal foreign body sensationand dysphagia. Symptoms were completely relieved by transposition surgerybut postoperative hypothyroidism developed.展开更多
Network coding(NC)can prove to be particularly useful in multimedia streaming applications,where it could help to increase the network throughput and data persistence in Mobile Ad hoc NETwork(MANET).Slidingwindow Netw...Network coding(NC)can prove to be particularly useful in multimedia streaming applications,where it could help to increase the network throughput and data persistence in Mobile Ad hoc NETwork(MANET).Slidingwindow Network Coding is a variation of NC that is an addition to multimedia streaming and improves the data delay on MANETs.In this paper,we propose a Sliding Window Network Coding for free Viewpoint Multimedia streaming in MANETs(SWNC-VM).SWNC-VM preserves the degree distribution of the encoded packets through the recombination at the nodes.SWNC-VM enables to control the decoding complexity of each sliding-window independently from the packets received and recover the original data.The performance of the SWNCVM is studied using NS2 and evaluated in terms of the encoding overhead,decoding delay,packet loss probability and throughput when a packet is transmitted.The simulations result shows that the SWNC-VM with our proposition can significantly improve the network throughput and encoding efficiency.展开更多
The preparation of green and economical bio-aviation fuel is a priority for the sustainable development industry.In this study,Jatropha oil was used as a raw material to catalyze the conversion of raw material to avia...The preparation of green and economical bio-aviation fuel is a priority for the sustainable development industry.In this study,Jatropha oil was used as a raw material to catalyze the conversion of raw material to aviation kerosene fraction by photothermal coupling under the conditions of light and low temperature.The correlations among conversion rate,target alkane selectivity,composition distribution,and catalyst microstructure were investigated by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),nitrogen(N2)adsorption and desorption,X-ray fluorescence(XRF),ammoniatemperature programmed desorption(NH3-TPD),ultraviolet-visible spectrophotometry(UV-Vis),and other characterization.The correlation between conversion and target alkane selectivity and composition distribution and catalyst microstructure was investigated,and different modification methods and different molecular sieve materials were selected.The results showed that the molecular sieves modified with the solid dispersion method could retain the structural stability of titanium dioxide(TiO2)and molecular sieves to a great extent while slightly enhancing the pore capacity and pore size of the catalyst to make it easier to adsorb reactants;the introduction of active metal platinum(Pt)could reduce the forbidden bandwidth of the catalyst,increase the weak acid amount of the catalyst,improve the adsorption capacity of hydrogen(H2),and thus improve the catalytic ability,resulting in a suitable catalyst for this study:P-21.The photothermal catalytic reaction of Jatropha oil using P-21 catalyst obtained 97.21%conversion and 74.99%selectivity of the target alkanes under the optimal process parameters.The results of this study provide effective catalyst parameters for research in the field of clean energy.展开更多
Emerging non-volatile memory technologies,especially flash-based solid state drives(SSDs),have increasingly been adopted in the storage stack.They provide numerous advantages over traditional mechanically rotating har...Emerging non-volatile memory technologies,especially flash-based solid state drives(SSDs),have increasingly been adopted in the storage stack.They provide numerous advantages over traditional mechanically rotating hard disk drives(HDDs)and have a tendency to replace HDDs.Due to the long existence of HDDs as primary building blocks for storage systems,however,much of the system software has been specially designed for HDD and may not be optimal for non-volatile memory media.Therefore,in order to realistically leverage its superior raw performance to the maximum,the existing upper layer software has to be re-evaluated or re-designed.To this end,in this paper,we propose PASS,an optimized I/O scheduler at the Linux block layer to accommodate the changing trend of underlying storage devices toward flash-based SSDs.PASS takes the rich internal parallelism in SSDs into account when dispatching requests to the device driver in order to achieve high performance.Specifically,it partitions the logical storage space into fixed-size regions(preferably the component package sizes)as scheduling units.These scheduling units are serviced in a round-robin manner and for every chance that the chosen dispatching unit issues only a batch of either read or write requests to suppress the excessive mutual interference.Additionally,the requests are sorted according to their visiting addresses while waiting in the dispatching queues to exploit high sequential performance of SSD.The experimental results with a variety of workloads have shown that PASS outperforms the four Linux off-the-shelf I/O schedulers by a degree of 3%up to41%,while at the same time it improves the lifetime significantly,due to reducing the internal write amplification.展开更多
基金funded by the Scientific and Technological Research Projects in Henan Province(No.252102310425)the Key Scientific Research Projects of Higher Education Institutions in Henan Province(No.23A560018).
文摘Freeze-drying of structurally heterogeneous biomaterials such as porcine aorta presents considerable modeling challenges due to their inherent multilayer composition and moving sublimation interfaces.Conventional models often overlook structural anisotropy and dynamic boundary progression,while experimental determination of key parameters under cryogenic conditions remains difficult.To address these,this study develops a heat and mass transfer model incorporating a dynamic node strategy for the sublimation interface,which effectively handles continuous computational domain deformation.Additionally,specialized fixed nodes were incorporated to adapt to the multilayer structure and its spatially varying thermophysical properties.A novel non-contact gravimetric system was introduced to monitor mass loss in real time without disrupting vacuum,enabling accurate experimental validation.Combined with dehydration data,the model quantified critical parameters including effective thermal conductivity of the dried layer,vapor diffusivity,and sublimation mass transfer resistance.The results show that the migration of the sublimation fronts from both the inner and outer tunics toward the tunica media significantly alters the drying kinetics and heat-mass transfer characteristics.The proposed approach provides an adaptable and predictive framework for simulating freeze-drying processes in structurally heterogeneous systems with spatially varying thermophysical properties.
基金supported by Henan province key science and technology research projects with No.23A560018.
文摘This study experimentally investigates the operational performance of a scroll compressor using R513A to expand its application range as a substitute for R134a.A vapor compression heat pump test platform was established to analyze the variation trends of heating capacity,refrigerant mass flow rate,compressor power consumption,and current by controlling the compressor inlet and outlet pressures(i.e.,evaporating and condensing temperatures).The results indicate that both heating capacity and refrigerant mass flow rate decrease with increasing pressure ratio.Compressor power consumption and current initially increase and then decrease with rising evaporating temperature,whereas they exhibit an approximately linear positive correlation with condensing temperature.Based on the experimental data,a polynomial model with pressure ratio as the independent variable was developed.This model predicts heating capacity,mass flow rate,power consumption,and current with high accuracy,showing an average deviation of less than 2%.However,the model’s applicability is significantly influenced by evaporating and condensing temperatures.Therefore,an enhanced 10-coefficient polynomial model,incorporating both evaporating and condensing temperatures as independent variables,was established.This improved model eliminates operational limitations and demonstrates superior prediction performance,with an average deviation of±1.44%for compressor performance parameters,confirming its practical value for engineering applications.
基金supported by the National Natural Science Foundation of China(No.41877251)the Key project of Natural Science Foundation of Tianjin City(No.6JCZDJC39000).
文摘The performances of a refrigeration unit relying on compressors working in parallel have been investigated considering the influence of the compressor volumetric efficiency and isentropic efficiency on the compression ratio.Moreover,the following influential factors have been taken into account:evaporation temperature,condensation temperature and compressor suction-exhaust pressure ratio for different opening conditions of the compressor.The following quantities have been selected as the unit performance measurement indicators:refrigeration capacity,energy efficiency ratio(COP),compressor power consumption,and refrigerant flow rate.The experimental results indicate that the system refrigeration capacity and COP decrease with a decrease in evaporation temperature,increase of condensation temperature,and increase in pressure ratio.The refrigerant flow rate increases with the increase in evaporation temperature,decrease in condensing temperature and increase in pressure ratio.The compressor power consumption increases with the increase in condensing temperature and increase in pressure ratio,but is not significantly affected by the evaporation temperature.
基金This work was supported by the National Natural Science Foundation of China(No.41877251)Major Science and Technology Projects of Xinxiang City(No.21ZD012).
文摘In order to ensure the safe operation of the compressors used in water chillers,in the present study some interlock protections have been added to the related design.These include a low pressure protection,a high pressure protection,an exhaust temperature protection and a differential pressure protection.Some tests have been conducted by tuning the saturation suction and exhaust temperatures of the compressor through adjustment of the cold source outlet temperature and the ambient temperature.The results show that the ambient temperature increases with decreasing device load and increasing fan speed under the same saturated suction temperature;the device refrigerating capacity steps up with augmenting load and dropping saturation exhaust temperature,while it is not greatly affected by the fan speed.Moreover,the Energy efficiency ratio(COP)decreases with the rise of the saturation exhaust temperature.This parameter is not affected much by the device load and fan speed at high saturation exhaust temperature,while it improves on increasing the device load and decreasing the fan speed at low saturation exhaust temperature.
基金supported by the National Natural Science Foundation of China(No.41877251)Major Science and Technology Projects of Xinxiang City(No.21ZD012).
文摘The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refrigerant undergoing condensation.In particular four theoretical single-phase flow and three multi-phase flow models have been used in this regard.The experimental results show that:the Oliver et al.criterion equation overestimates the experimental results as its accuracy is significantly affected by the specific conditions realized inside micro-fin tubes;the Miyara et al.criterion equation prediction error is less than 15%;the Cavallini et al.approach gives the highest prediction accuracy;the Goto et al.model overestimates the test data.Such results are critically discussed and some indications for the improvement of such models are provided.
文摘BACKGROUNDEctopic thyroid at the base of the tongue is a rare congenital condition, and it iseven rarer to have clinical symptoms and require surgical intervention. Thisdisease is easily misdiagnosed preoperatively. This article reports the diagnosis,surgical treatment, and follow-up of a case of lingual thyroid.CASE SUMMARYThe patient was a 54-year-old woman who presented with laryngeal foreign bodysensation and dysphagia for 20 d. The lingual thyroid was considered for generalexamination, and surgery was performed to transpose the lingual thyroid to theright submaxillary region. Pathological analysis confirmed thyroid tissue. Thepatient experienced complete remission after surgery, but developed hypothyroidismand required thyroid hormone replacement therapy, and her thyroidfunction gradually recovered over time.CONCLUSIONWe report a rare case of lingual thyroid with marked laryngeal foreign body sensationand dysphagia. Symptoms were completely relieved by transposition surgerybut postoperative hypothyroidism developed.
基金This work is supported by The National Natural Science Foundation of China(No.61572012),The Key Natural Science Foundation of Hubei Province of China(No.2014CFA055,2013CFB309),and The Science Foundation of Ministry of Education of Wuhan of China(No.2011060).A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institution(PAPD).Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology(CICAEET).
文摘Network coding(NC)can prove to be particularly useful in multimedia streaming applications,where it could help to increase the network throughput and data persistence in Mobile Ad hoc NETwork(MANET).Slidingwindow Network Coding is a variation of NC that is an addition to multimedia streaming and improves the data delay on MANETs.In this paper,we propose a Sliding Window Network Coding for free Viewpoint Multimedia streaming in MANETs(SWNC-VM).SWNC-VM preserves the degree distribution of the encoded packets through the recombination at the nodes.SWNC-VM enables to control the decoding complexity of each sliding-window independently from the packets received and recover the original data.The performance of the SWNCVM is studied using NS2 and evaluated in terms of the encoding overhead,decoding delay,packet loss probability and throughput when a packet is transmitted.The simulations result shows that the SWNC-VM with our proposition can significantly improve the network throughput and encoding efficiency.
基金supported by the National Natural Science Foundation of China(Grant No.21868014)a Key Project of the Yunnan Fundamental Research Program(Study on Design of Novel Catalyst and Catalytic Process for Preparation of Bioaviation Kerosene from Vegetable Oils Based on Photo-thermal Catalytic Technology),2021 Low-carbon Development Guide Project of Yunnan Province,China(No.135),Key S&T Project of China Tobacco Yunnan Industrial Co.,Ltd.,(Grant No.2022GY03)+4 种基金Yunnan Academician and Expert Workstation(Grant No.202205AF150024)Yunnan International S&T Cooperation Program,China(Grant No.202003AF140001)Yunnan S&T Talents and Platform Program(Grant No.202105AC160058)Kunming International S&T Cooperation Base,China(Grant No.GHJD-2020026)Scientific research project of Yunnan Environmental Science Society,China(Grant No.XHKYKT006).
文摘The preparation of green and economical bio-aviation fuel is a priority for the sustainable development industry.In this study,Jatropha oil was used as a raw material to catalyze the conversion of raw material to aviation kerosene fraction by photothermal coupling under the conditions of light and low temperature.The correlations among conversion rate,target alkane selectivity,composition distribution,and catalyst microstructure were investigated by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM),nitrogen(N2)adsorption and desorption,X-ray fluorescence(XRF),ammoniatemperature programmed desorption(NH3-TPD),ultraviolet-visible spectrophotometry(UV-Vis),and other characterization.The correlation between conversion and target alkane selectivity and composition distribution and catalyst microstructure was investigated,and different modification methods and different molecular sieve materials were selected.The results showed that the molecular sieves modified with the solid dispersion method could retain the structural stability of titanium dioxide(TiO2)and molecular sieves to a great extent while slightly enhancing the pore capacity and pore size of the catalyst to make it easier to adsorb reactants;the introduction of active metal platinum(Pt)could reduce the forbidden bandwidth of the catalyst,increase the weak acid amount of the catalyst,improve the adsorption capacity of hydrogen(H2),and thus improve the catalytic ability,resulting in a suitable catalyst for this study:P-21.The photothermal catalytic reaction of Jatropha oil using P-21 catalyst obtained 97.21%conversion and 74.99%selectivity of the target alkanes under the optimal process parameters.The results of this study provide effective catalyst parameters for research in the field of clean energy.
基金supported by the National Basic Research Program(973)of China(No.2004CB318203) the National High-Tech R&D Program(863)of China(No.2009AA01A402)+1 种基金the Natural Science Foundation of Hubei Province,China(No.2013CFB035)the Key Science Research Project of Hubei Education Office in China(No.D20141301)
文摘Emerging non-volatile memory technologies,especially flash-based solid state drives(SSDs),have increasingly been adopted in the storage stack.They provide numerous advantages over traditional mechanically rotating hard disk drives(HDDs)and have a tendency to replace HDDs.Due to the long existence of HDDs as primary building blocks for storage systems,however,much of the system software has been specially designed for HDD and may not be optimal for non-volatile memory media.Therefore,in order to realistically leverage its superior raw performance to the maximum,the existing upper layer software has to be re-evaluated or re-designed.To this end,in this paper,we propose PASS,an optimized I/O scheduler at the Linux block layer to accommodate the changing trend of underlying storage devices toward flash-based SSDs.PASS takes the rich internal parallelism in SSDs into account when dispatching requests to the device driver in order to achieve high performance.Specifically,it partitions the logical storage space into fixed-size regions(preferably the component package sizes)as scheduling units.These scheduling units are serviced in a round-robin manner and for every chance that the chosen dispatching unit issues only a batch of either read or write requests to suppress the excessive mutual interference.Additionally,the requests are sorted according to their visiting addresses while waiting in the dispatching queues to exploit high sequential performance of SSD.The experimental results with a variety of workloads have shown that PASS outperforms the four Linux off-the-shelf I/O schedulers by a degree of 3%up to41%,while at the same time it improves the lifetime significantly,due to reducing the internal write amplification.
