By measuring the mass transfer coefficient of benzoic acid between water and oil, the oxygen transfer rate in BOF bath was researched, and the influence of top and bottom blowing gas flow rate on the mass transfer bet...By measuring the mass transfer coefficient of benzoic acid between water and oil, the oxygen transfer rate in BOF bath was researched, and the influence of top and bottom blowing gas flow rate on the mass transfer between metal and slag was discussed. The results show that with increasing the bottom blowing gas flow rate under the conditions of fixed top blowing, the mass transfer rate evidently increases, and the influence of fixed top blowing on the mass transfer is 10% of bottom blowing. The stirring intensity was determined as a function of top blowing gas flow rate, bottom blowing gas flow rate, and lance height. The equation of the mass transfer coefficient between metal and slag was established. The relationship between the emulsification ratio of oil to water and the bottom blowing gas flow rate under the conditions of top and bottom blowing was obtained. The result shows that with the increase in the bottom blowing gas flow rate, the emulsification ratio increases linearly, which increases the mass transfer rate of benzoic acid between water and oil.展开更多
The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;h...The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.展开更多
This work used artificial neural network(ANN)to predict the heat transfer rates of shell-and-tube heatexchangers with segmental baffles or continuous helical baffles,based on limited experimental data.The BackPropagat...This work used artificial neural network(ANN)to predict the heat transfer rates of shell-and-tube heatexchangers with segmental baffles or continuous helical baffles,based on limited experimental data.The BackPropagation (BP) algorithm was used in training the networks.Different network configurations were alsostudied.The deviation between the predicted results and experimental data was less than 2%.Comparison withcorrelation for prediction shows ANN superiority.It is recommended that ANN can be easily used to predict theperformances of thermal systems in engineering applications,especially to model heat exchangers for heattransfer analysis.展开更多
For Brain-Computer Interface(BCI) systems, improving the Information Transfer Rate(ITR) is a very critical issue. This study focuses on a Steady-State Visually Evoked Potential(SSVEP)-based BCI because of its advantag...For Brain-Computer Interface(BCI) systems, improving the Information Transfer Rate(ITR) is a very critical issue. This study focuses on a Steady-State Visually Evoked Potential(SSVEP)-based BCI because of its advantage of high ITR. Unsupervised Canonical Correlation Analysis(CCA)-based method has been widely employed because of its high efficiency and easy implementation. In a recent study, an ensemble-CCA method based on individual training data was proposed and achieved an excellent performance with ITR of 267 bit/min.A 40-target SSVEP-BCI speller was investigated in this study, using an integration of Minimal-Distance(MD) and Maximal-Phase-locking value(MP) approaches. In the MD approach, a spatial filter is developed to minimize the distance between the training data and the reference sine signal, and in this study, two different types of distance were compared. In the MP approach, a spatial filter is developed to maximize the Phase-Locking Value(PLV)between the training calibration data and the reference sine signal. In addition to the fundamental frequency of stimulation, the harmonics were used to train MD and MP spatial filters, which formed spatial filter banks. The test data epoch was multiplied by the MP and MD spatial filter banks, and the distances and PLVs were extracted as features for recognition. Across 12 subjects with a 0.4 s-data length, the proposed method realized an average classification accuracy and ITR of 93% and 307 bit/min, respectively, which is significantly higher than the current state-of-the-art method. To the best of our knowledge, these results suggest that the proposed method has achieved the highest ITR in SSVEP-BCI studies.展开更多
When examining the file transfer performance in a peer-to-peer file sharing system, a fundamental problem is how to describe the service rate for a file transfer. In this paper, the problem is examined by analyzing th...When examining the file transfer performance in a peer-to-peer file sharing system, a fundamental problem is how to describe the service rate for a file transfer. In this paper, the problem is examined by analyzing the distribution of server-like nodes' upstream-bandwidth among their concurrent transfers. A sufficient condition for the service rate, what a receiver obtains for downloading a file, to asymptotically be uniform is presented. On the aggregate service rate for transferring a file in a system, a sufficient condition for it to asymptotically follow a Zipf distribution is presented. These asymptotic equalities are both in the mean square sense. These analyses and the sufficient conditions provide a mathematic base for modeling file transfer processes in peer-to-peer file sharing systems.展开更多
Objective To analyse factors influencing the outcome of frozen-thawed embryo transfer （FET）. Method A retrospective analysis was performed in our center on 129 thawing cycles from March 2001 to April 2003. The relat...Objective To analyse factors influencing the outcome of frozen-thawed embryo transfer （FET）. Method A retrospective analysis was performed in our center on 129 thawing cycles from March 2001 to April 2003. The related parameters were compared between conceived and non-conceived cycles. Results There were totally 129 clinical pregnancies in these transfers （pregnancy rate： 27.1%）. Frozen-thawed embryos were transferred to natural cycles and CC cycling and hormone replacement treatment had equal success. Groups of IVF and ICSI did not differ significantly in pregnancy rates （P〉0.05）. The pregnancy rates for one, two, three and four pre-embryos transfer were 0, 20.0%,44.1% and 75.0%, respectively （P〈0.05）. There were statistical differences between pregnancy group or non- pregnancy group in the endometrial thickness, CES, CES/No. of embryo. A higher pregnancy rate was observed in embryo transfers which had at least one 4-cell grade I embryo （d 2）（P〈0.01）. Conclusions The most important factors influencing the implantation rate and pregnancy rate of frozen-thawed embryo transfer are age, endometrium thickness, and the number, morphology and growth rate of transferred frozen embryos of women participants.展开更多
Objective To investigate the effect of FTY720-treated immature bone marrow-derived dendritic cells（BMDCs） on the embryo resorption rate in the CBA/J× DBA/2 abortion mouse model.Methods The dendritic cells（DCs...Objective To investigate the effect of FTY720-treated immature bone marrow-derived dendritic cells（BMDCs） on the embryo resorption rate in the CBA/J× DBA/2 abortion mouse model.Methods The dendritic cells（DCs） were derived from bone marrow of DBA/2 mice, and then co-cultured with FTY720. The abortion mouse models were established by mating female CBA/J mice with DBA/2 mice. Via the CBA/J×DBA/2 abortion mouse model, six groups were established, group A： normal pregnancy model; group B： abortion mouse model with no treatment; group C： abortion mouse model injected with DC culture medium（DCCM）; group D： abortion mouse model injected with DC; group E： abortion mouse model injected with FTY720; group F： abortion model mouse injected with FTY720-DC. The differences were compared in the embryo resorption rates of the CBA/J ×DBA/2 abortion mouse model treated with FTY720-DC or different controls observed on gestation day 12 to 14, and then the microenvironment in murine pregnancy was investigated.Results The embryo resorption rate was statistically significantly decreased in group D and group E when they compared with group B and group C（P〈0.05, respectively）.Furthermore, the embryo resorption rate in group F showed a statistically significant decrease when compared with the other groups except group A（P〈0.01）. These resultssuggest that FTY720-DCs possess a notable advantage over DCs or FTY720 in reducing the embryo resorption rate of the abortion mouse model. The percentage of Th17（IL-17＋CD4＋T cells） in peripheral blood mononuclear cell（PBMC） in the abortion mouse model was 4.35%±0.34% before treated with FTY720-DC, and was1.34%±0.28% after treated with FTY720-DC（P〈0.01）. The percentage of Tregs（CD4~＋CD25~＋Foxp3~＋T cells） in PBMC was significantly increased in group F（8.35%±1.80%） as compared with group B（2.68%±0.65%）（P〈0.01）.Conclusion Adoptive transfer of FTY720-DC can statistically significantly reduce the embryo resorption rate in the CBA/J×DBA/2 abortion mouse model. The lower embryo resorption rate in the FTY720-DC treated abortion mouse model may be caused by the imbalance of Treg/Th17.展开更多
After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated ...After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.展开更多
Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter ...Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap.展开更多
Lithium-ion batteries(LIBs)have shown considerable promise as an energy storage system due to their high conversion efficiency,size options(from coin cell to grid storage),and free of gaseous exhaust.For LIBs,power de...Lithium-ion batteries(LIBs)have shown considerable promise as an energy storage system due to their high conversion efficiency,size options(from coin cell to grid storage),and free of gaseous exhaust.For LIBs,power density and energy density are two of the most important parameters for their practical use,and the power density is the key factor for applications such as fast-charging electric vehicles,high-power portable tools,and power grid stabilization.A high rate of performance is also required for devices that store electrical energy from seasonal or irregular energy sources,such as wind energy and wave energy.Significant efforts have been made over the last several years to improve the power density of LIBs through anodes,cathodes,and electrolytes,and much progress has been made.To provide a comprehensive picture of these recent achievements,this review discusses the progress made in high-power LIBs from 2013 to the present,including general and fundamental principles of high-power LIBs,challenges facing LIB development today,and an outlook for future LIB development.展开更多
An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is ...An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.展开更多
Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,P...Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction.Pt nanoclusters with a diameter of∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature.The CdS/Pt photocatalyst using lactic acid shows a higher H_(2)production rate of 4762μmol g^(-1)h^(-1)compared to that using methanol,tri-ethanolamine,and glycerol.To understand the cause,the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H_(2)production are revealed by femtosecond transient absorption spec-troscopy.Among the four organic EDs,lactic acid enables the fastest electron transfer rate of 1.8×10^(9)s^(-1)and the highest electron transfer efficiency of 76%at the CdS/Pt interface due to the most efficient hole consumption.This work sheds light on the importance of efficient interfacial electron transfer for im-proving the photocatalytic performance of Schottky junction photocatalysts.展开更多
To improve the efficiency of the steelmaking process,a system of self-rotating lance was designed,and corresponding cold simulation mechanism was developed.The influence of the self-rotating lance on the mass transfer...To improve the efficiency of the steelmaking process,a system of self-rotating lance was designed,and corresponding cold simulation mechanism was developed.The influence of the self-rotating lance on the mass transfer rate between slag and molten steel was investigated by comparing this novel system with the traditional oxygen lance.The results show that the self-rotating lance can stably rotate with a gas jet as the power source.The mass transfer rate increases with an increase in the top and bottom blow flow rates and with a decline in the lance position.Approximately 13.7% of the top blow flow rate is converted to stirring energy,which is approximately twice that of the traditional oxygen lance,and the mass transfer rate can increase by over 30%.Furthermore,the impact energy can be concentrated at different depths of the molten bath by adjusting the rotational speed.With the same energy density,the mass transfer rate produced by the self-rotating lance is higher;however,the influence of the energy density on the mass transfer rate is low when the rotational speed is 30-50 r/min.展开更多
This work investigates the steam condensation phenomena in an air-cooled condenser.The considered horizontal flattened tube has a 30 mm hydraulic diameter,and its length is a function of the steam quality with a limit...This work investigates the steam condensation phenomena in an air-cooled condenser.The considered horizontal flattened tube has a 30 mm hydraulic diameter,and its length is a function of the steam quality with a limit value between 0.95 and 0.05.The mass flow rate ranges from 4 to 40 kg/m^(2).s with a saturated temperature spanning an interval from 40°C to 80°C.A special approach has been implemented using the Engineering Equation Solver(EES)to solve a series of equations for the two-phase flow pattern and the related heat transfer coefficients.A wavy-stratified structure of the two-phase flow has been found when the mass rate was between 4 and 24 kg/m^(2).s.In contrast,an initially annular flow is gradually converted into a wavy stratified flow(due to the condensation process taking place inside the flattened tube)when the considered range ranges from 32 to 40 kg/m^(2).s.展开更多
In wastewater treatment plants（WWTPs）using the activated sludge process,two methods are widely used to improve aeration efficiency — use of high-efficiency aeration devices and optimizing the aeration control strat...In wastewater treatment plants（WWTPs）using the activated sludge process,two methods are widely used to improve aeration efficiency — use of high-efficiency aeration devices and optimizing the aeration control strategy. Aeration efficiency is closely linked to sludge characteristics（such as concentrations of mixed liquor suspended solids（MLSS）and microbial communities）and operating conditions（such as air flow rate and operational dissolved oxygen（DO）concentrations）. Moreover,operational DO is closely linked to effluent quality. This study,which is in reference to WWTP discharge class A Chinese standard effluent criteria,determined the growth kinetics parameters of nitrifiers at different DO levels in small-scale tests. Results showed that the activated sludge system could meet effluent criteria when DO was as low as 0.3 mg/L,and that nitrifier communities cultivated under low DO conditions had higher oxygen affinity than those cultivated under high DO conditions,as indicated by the oxygen half-saturation constant and nitrification ability. Based on nitrifier growth kinetics and on the oxygen mass transfer dynamic model（determined using different air flow rate（Q′air）and mixed liquor volatile suspended solids（MLVSS）values）,theoretical analysis indicated limited potential for energy saving by improving aeration diffuser performance when the activated sludge system had low oxygen consumption; however,operating at low DO and low MLVSS could significantly reduce energy consumption. Finally,a control strategy coupling sludge retention time and MLVSS to minimize the DO level was discussed,which is critical to appropriate setting of the oxygen point and to the operation of low DO treatment technology.展开更多
This paper investigates the simultaneous wireless information and powertransfer(SWIPT) for network-coded two-way relay network from an information-theoretic perspective, where two sources exchange information via an S...This paper investigates the simultaneous wireless information and powertransfer(SWIPT) for network-coded two-way relay network from an information-theoretic perspective, where two sources exchange information via an SWIPT-aware energy harvesting(EH) relay. We present a power splitting(PS)-based two-way relaying(PS-TWR) protocol by employing the PS receiver architecture. To explore the system sum rate limit with data rate fairness, an optimization problem under total power constraint is formulated. Then, some explicit solutions are derived for the problem. Numerical results show that due to the path loss effect on energy transfer, with the same total available power, PS-TWR losses some system performance compared with traditional non-EH two-way relaying, where at relatively low and relatively high signalto-noise ratio(SNR), the performance loss is relatively small. Another observation is that, in relatively high SNR regime, PS-TWR outperforms time switching-based two-way relaying(TS-TWR) while in relatively low SNR regime TS-TWR outperforms PS-TWR. It is also shown that with individual available power at the two sources, PS-TWR outperforms TS-TWR in both relatively low and high SNR regimes.展开更多
To realize stable rotating spray transfer in the region of high constant current is the key of realizing high deposition rate MAG welding process without helium in shielding gas and extending the welding current rang...To realize stable rotating spray transfer in the region of high constant current is the key of realizing high deposition rate MAG welding process without helium in shielding gas and extending the welding current range of traditional MAG welding process. In this paper, the magnetic control mechanism of the rotating spray transfer is stated and mathematical model is given. Theoretic basis is established, which implements high deposition rate MAG welding process with magnetic control instead of helium in shielding gas.展开更多
The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be v...The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.展开更多
基金Item Sponsored by National Science and Technology Support Program for 11th Five-Year Plan of China (2006BAE03A00)
文摘By measuring the mass transfer coefficient of benzoic acid between water and oil, the oxygen transfer rate in BOF bath was researched, and the influence of top and bottom blowing gas flow rate on the mass transfer between metal and slag was discussed. The results show that with increasing the bottom blowing gas flow rate under the conditions of fixed top blowing, the mass transfer rate evidently increases, and the influence of fixed top blowing on the mass transfer is 10% of bottom blowing. The stirring intensity was determined as a function of top blowing gas flow rate, bottom blowing gas flow rate, and lance height. The equation of the mass transfer coefficient between metal and slag was established. The relationship between the emulsification ratio of oil to water and the bottom blowing gas flow rate under the conditions of top and bottom blowing was obtained. The result shows that with the increase in the bottom blowing gas flow rate, the emulsification ratio increases linearly, which increases the mass transfer rate of benzoic acid between water and oil.
基金gratefully express their appreciation to National Natural Science Foundation of China(Nos.51974153 and U1960203)the Joint Fund of State Key Laboratory of Marine Engineering and University of Science and Technology Liaoning(SKLMEA-USTL-201707)the China Scholarship Council(201908210457).
文摘The interfacial oxygen transfer rate is one of the main factors to control the composition of alloys.The commonly employed method of studying the interfacial oxygen transfer rate is the chemical composition analysis;however,it is difficult to be studied in situ.Here,a new method of measuring the oxygen transfer rate at the gas-slag and slag-metal interfaces was reported based on electrochemical analyses.The interfacial oxygen transfer rate in the smelting process of Inconel 718 superalloy was investigated at 1723,1773,1823,and 1873 K.The experimental results show that the electrochemical method can measure the real-time oxygen content;hence,this method is promising in controlling the oxygen content in alloys.As the temperature increased,both the equilibrium oxygen content and the rate of oxygen absorption increased significantly,and the increase was the most obvious when the temperature was 1873 K.The possible reason is that the increase in temperature weakens the mass transfer resistance of the electric double layer at the interface,thus accelerating the oxygen transfer rate.
文摘This work used artificial neural network(ANN)to predict the heat transfer rates of shell-and-tube heatexchangers with segmental baffles or continuous helical baffles,based on limited experimental data.The BackPropagation (BP) algorithm was used in training the networks.Different network configurations were alsostudied.The deviation between the predicted results and experimental data was less than 2%.Comparison withcorrelation for prediction shows ANN superiority.It is recommended that ANN can be easily used to predict theperformances of thermal systems in engineering applications,especially to model heat exchangers for heattransfer analysis.
基金supported by the National Natural Science Foundation of China (Nos. 61431007 and 91320202)
文摘For Brain-Computer Interface(BCI) systems, improving the Information Transfer Rate(ITR) is a very critical issue. This study focuses on a Steady-State Visually Evoked Potential(SSVEP)-based BCI because of its advantage of high ITR. Unsupervised Canonical Correlation Analysis(CCA)-based method has been widely employed because of its high efficiency and easy implementation. In a recent study, an ensemble-CCA method based on individual training data was proposed and achieved an excellent performance with ITR of 267 bit/min.A 40-target SSVEP-BCI speller was investigated in this study, using an integration of Minimal-Distance(MD) and Maximal-Phase-locking value(MP) approaches. In the MD approach, a spatial filter is developed to minimize the distance between the training data and the reference sine signal, and in this study, two different types of distance were compared. In the MP approach, a spatial filter is developed to maximize the Phase-Locking Value(PLV)between the training calibration data and the reference sine signal. In addition to the fundamental frequency of stimulation, the harmonics were used to train MD and MP spatial filters, which formed spatial filter banks. The test data epoch was multiplied by the MP and MD spatial filter banks, and the distances and PLVs were extracted as features for recognition. Across 12 subjects with a 0.4 s-data length, the proposed method realized an average classification accuracy and ITR of 93% and 307 bit/min, respectively, which is significantly higher than the current state-of-the-art method. To the best of our knowledge, these results suggest that the proposed method has achieved the highest ITR in SSVEP-BCI studies.
基金National High Technology Research and Development Program of China (No.2007AA01Z457)Shanghai Science and Technology Development Fundation,China(No.07QA14033)
文摘When examining the file transfer performance in a peer-to-peer file sharing system, a fundamental problem is how to describe the service rate for a file transfer. In this paper, the problem is examined by analyzing the distribution of server-like nodes' upstream-bandwidth among their concurrent transfers. A sufficient condition for the service rate, what a receiver obtains for downloading a file, to asymptotically be uniform is presented. On the aggregate service rate for transferring a file in a system, a sufficient condition for it to asymptotically follow a Zipf distribution is presented. These asymptotic equalities are both in the mean square sense. These analyses and the sufficient conditions provide a mathematic base for modeling file transfer processes in peer-to-peer file sharing systems.
文摘Objective To analyse factors influencing the outcome of frozen-thawed embryo transfer （FET）. Method A retrospective analysis was performed in our center on 129 thawing cycles from March 2001 to April 2003. The related parameters were compared between conceived and non-conceived cycles. Results There were totally 129 clinical pregnancies in these transfers （pregnancy rate： 27.1%）. Frozen-thawed embryos were transferred to natural cycles and CC cycling and hormone replacement treatment had equal success. Groups of IVF and ICSI did not differ significantly in pregnancy rates （P〉0.05）. The pregnancy rates for one, two, three and four pre-embryos transfer were 0, 20.0%,44.1% and 75.0%, respectively （P〈0.05）. There were statistical differences between pregnancy group or non- pregnancy group in the endometrial thickness, CES, CES/No. of embryo. A higher pregnancy rate was observed in embryo transfers which had at least one 4-cell grade I embryo （d 2）（P〈0.01）. Conclusions The most important factors influencing the implantation rate and pregnancy rate of frozen-thawed embryo transfer are age, endometrium thickness, and the number, morphology and growth rate of transferred frozen embryos of women participants.
基金supported by the National Natural Science Foundation of China(Grant No.81200477)
文摘Objective To investigate the effect of FTY720-treated immature bone marrow-derived dendritic cells（BMDCs） on the embryo resorption rate in the CBA/J× DBA/2 abortion mouse model.Methods The dendritic cells（DCs） were derived from bone marrow of DBA/2 mice, and then co-cultured with FTY720. The abortion mouse models were established by mating female CBA/J mice with DBA/2 mice. Via the CBA/J×DBA/2 abortion mouse model, six groups were established, group A： normal pregnancy model; group B： abortion mouse model with no treatment; group C： abortion mouse model injected with DC culture medium（DCCM）; group D： abortion mouse model injected with DC; group E： abortion mouse model injected with FTY720; group F： abortion model mouse injected with FTY720-DC. The differences were compared in the embryo resorption rates of the CBA/J ×DBA/2 abortion mouse model treated with FTY720-DC or different controls observed on gestation day 12 to 14, and then the microenvironment in murine pregnancy was investigated.Results The embryo resorption rate was statistically significantly decreased in group D and group E when they compared with group B and group C（P〈0.05, respectively）.Furthermore, the embryo resorption rate in group F showed a statistically significant decrease when compared with the other groups except group A（P〈0.01）. These resultssuggest that FTY720-DCs possess a notable advantage over DCs or FTY720 in reducing the embryo resorption rate of the abortion mouse model. The percentage of Th17（IL-17＋CD4＋T cells） in peripheral blood mononuclear cell（PBMC） in the abortion mouse model was 4.35%±0.34% before treated with FTY720-DC, and was1.34%±0.28% after treated with FTY720-DC（P〈0.01）. The percentage of Tregs（CD4~＋CD25~＋Foxp3~＋T cells） in PBMC was significantly increased in group F（8.35%±1.80%） as compared with group B（2.68%±0.65%）（P〈0.01）.Conclusion Adoptive transfer of FTY720-DC can statistically significantly reduce the embryo resorption rate in the CBA/J×DBA/2 abortion mouse model. The lower embryo resorption rate in the FTY720-DC treated abortion mouse model may be caused by the imbalance of Treg/Th17.
文摘After the electron transfers from the metal electrode to the Fe3+(H2O)(6) ion, the free energy of activation of this electron transfer reaction is calculated, then using the transition probability which is calculated by the perturbed degeneration theory and the Fermi golden rule,, the rate constant is gotten. Compared with the experimental results, it is satisfactory.
基金supported by the National Natural Science Foundation of China (Grant No. 42104001)。
文摘Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap.
基金financial support from National Natural Science Foundation of China(Grant No.21805079)the Fundamental Research Funds for the Central Universities(531107051077)Hunan high-level talent gathering project(2018RS3054)
文摘Lithium-ion batteries(LIBs)have shown considerable promise as an energy storage system due to their high conversion efficiency,size options(from coin cell to grid storage),and free of gaseous exhaust.For LIBs,power density and energy density are two of the most important parameters for their practical use,and the power density is the key factor for applications such as fast-charging electric vehicles,high-power portable tools,and power grid stabilization.A high rate of performance is also required for devices that store electrical energy from seasonal or irregular energy sources,such as wind energy and wave energy.Significant efforts have been made over the last several years to improve the power density of LIBs through anodes,cathodes,and electrolytes,and much progress has been made.To provide a comprehensive picture of these recent achievements,this review discusses the progress made in high-power LIBs from 2013 to the present,including general and fundamental principles of high-power LIBs,challenges facing LIB development today,and an outlook for future LIB development.
文摘An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.
基金the National Key Research and Development Program of China(Nos.2022YFB3803600 and 2018YFB1502001)National Natural Science Foundation of China(Nos.22238009,51932007,U1905215,52073223,52173065,and 52202375)+2 种基金the Natural Science Foundation of Hubei Province of China(No.2022CFA001)China Postdoctoral Science Foundation(Nos.2021TQ0311 and 2021M702990)International Postdoc-toral Exchange Fellowship Program(No.PC2022051).
文摘Electron donors(EDs)are widely used to improve the H 2 production performance of Schottky junction photocatalysts,but the functions of EDs are still unknown from the perspective of electron transfer dy-namics.Herein,Pt nanocluster-decorated CdS nanorod is successfully prepared to construct a typical CdS/Pt Schottky junction.Pt nanoclusters with a diameter of∼2 nm are deposited on the surface of CdS nanorods by in situ photoreduction at sub-zero temperature.The CdS/Pt photocatalyst using lactic acid shows a higher H_(2)production rate of 4762μmol g^(-1)h^(-1)compared to that using methanol,tri-ethanolamine,and glycerol.To understand the cause,the dynamics of photogenerated carriers in CdS/Pt photocatalysts during ED-assisted H_(2)production are revealed by femtosecond transient absorption spec-troscopy.Among the four organic EDs,lactic acid enables the fastest electron transfer rate of 1.8×10^(9)s^(-1)and the highest electron transfer efficiency of 76%at the CdS/Pt interface due to the most efficient hole consumption.This work sheds light on the importance of efficient interfacial electron transfer for im-proving the photocatalytic performance of Schottky junction photocatalysts.
基金the National Key Research and Development Program with Project Number 2017YFB0304000the Beijing Natural Science Foundation with Project Number 2172057 in China.
文摘To improve the efficiency of the steelmaking process,a system of self-rotating lance was designed,and corresponding cold simulation mechanism was developed.The influence of the self-rotating lance on the mass transfer rate between slag and molten steel was investigated by comparing this novel system with the traditional oxygen lance.The results show that the self-rotating lance can stably rotate with a gas jet as the power source.The mass transfer rate increases with an increase in the top and bottom blow flow rates and with a decline in the lance position.Approximately 13.7% of the top blow flow rate is converted to stirring energy,which is approximately twice that of the traditional oxygen lance,and the mass transfer rate can increase by over 30%.Furthermore,the impact energy can be concentrated at different depths of the molten bath by adjusting the rotational speed.With the same energy density,the mass transfer rate produced by the self-rotating lance is higher;however,the influence of the energy density on the mass transfer rate is low when the rotational speed is 30-50 r/min.
文摘This work investigates the steam condensation phenomena in an air-cooled condenser.The considered horizontal flattened tube has a 30 mm hydraulic diameter,and its length is a function of the steam quality with a limit value between 0.95 and 0.05.The mass flow rate ranges from 4 to 40 kg/m^(2).s with a saturated temperature spanning an interval from 40°C to 80°C.A special approach has been implemented using the Engineering Equation Solver(EES)to solve a series of equations for the two-phase flow pattern and the related heat transfer coefficients.A wavy-stratified structure of the two-phase flow has been found when the mass rate was between 4 and 24 kg/m^(2).s.In contrast,an initially annular flow is gradually converted into a wavy stratified flow(due to the condensation process taking place inside the flattened tube)when the considered range ranges from 32 to 40 kg/m^(2).s.
基金supported by the National Science and Technology Major Project(No.2013ZX07314-001)
文摘In wastewater treatment plants（WWTPs）using the activated sludge process,two methods are widely used to improve aeration efficiency — use of high-efficiency aeration devices and optimizing the aeration control strategy. Aeration efficiency is closely linked to sludge characteristics（such as concentrations of mixed liquor suspended solids（MLSS）and microbial communities）and operating conditions（such as air flow rate and operational dissolved oxygen（DO）concentrations）. Moreover,operational DO is closely linked to effluent quality. This study,which is in reference to WWTP discharge class A Chinese standard effluent criteria,determined the growth kinetics parameters of nitrifiers at different DO levels in small-scale tests. Results showed that the activated sludge system could meet effluent criteria when DO was as low as 0.3 mg/L,and that nitrifier communities cultivated under low DO conditions had higher oxygen affinity than those cultivated under high DO conditions,as indicated by the oxygen half-saturation constant and nitrification ability. Based on nitrifier growth kinetics and on the oxygen mass transfer dynamic model（determined using different air flow rate（Q′air）and mixed liquor volatile suspended solids（MLVSS）values）,theoretical analysis indicated limited potential for energy saving by improving aeration diffuser performance when the activated sludge system had low oxygen consumption; however,operating at low DO and low MLVSS could significantly reduce energy consumption. Finally,a control strategy coupling sludge retention time and MLVSS to minimize the DO level was discussed,which is critical to appropriate setting of the oxygen point and to the operation of low DO treatment technology.
基金supported by the National Natural Science Foundation of China ( No . 61602034 )the Beijing Natural Science Foundation (No. 4162049)+2 种基金the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University (No. 2014D03)the Fundamental Research Funds for the Central Universities Beijing Jiaotong University (No. 2016JBM015)the NationalHigh Technology Research and Development Program of China (863 Program) (No. 2015AA015702)
文摘This paper investigates the simultaneous wireless information and powertransfer(SWIPT) for network-coded two-way relay network from an information-theoretic perspective, where two sources exchange information via an SWIPT-aware energy harvesting(EH) relay. We present a power splitting(PS)-based two-way relaying(PS-TWR) protocol by employing the PS receiver architecture. To explore the system sum rate limit with data rate fairness, an optimization problem under total power constraint is formulated. Then, some explicit solutions are derived for the problem. Numerical results show that due to the path loss effect on energy transfer, with the same total available power, PS-TWR losses some system performance compared with traditional non-EH two-way relaying, where at relatively low and relatively high signalto-noise ratio(SNR), the performance loss is relatively small. Another observation is that, in relatively high SNR regime, PS-TWR outperforms time switching-based two-way relaying(TS-TWR) while in relatively low SNR regime TS-TWR outperforms PS-TWR. It is also shown that with individual available power at the two sources, PS-TWR outperforms TS-TWR in both relatively low and high SNR regimes.
文摘To realize stable rotating spray transfer in the region of high constant current is the key of realizing high deposition rate MAG welding process without helium in shielding gas and extending the welding current range of traditional MAG welding process. In this paper, the magnetic control mechanism of the rotating spray transfer is stated and mathematical model is given. Theoretic basis is established, which implements high deposition rate MAG welding process with magnetic control instead of helium in shielding gas.
基金supported by the National Natural Science Foundation of China (10672090,11002034,11072055 and 11032008)the National High Technology Research and Development Program of China (2006AA02Z4E8)the China Postdoctoral Science Foundation
文摘The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.
