The superplastic characteristics of the β-SiC whisker reinforced 2024 aluminum composite, fabricated by pressure infiltration and hot-rolling after extrusion, were investigated. The composite has a fine grain size of...The superplastic characteristics of the β-SiC whisker reinforced 2024 aluminum composite, fabricated by pressure infiltration and hot-rolling after extrusion, were investigated. The composite has a fine grain size of about 1μm, and exhibits a maximum tensile elongation of 370% in the initial strain rate of 3.3×10-3 s-1 at 788K.The superplastic deformation mechanism of the composite is thought to be grain boundary (interface) sliding accommodated by grain boundary diffusion of aluminum atom and an appropriate amount of liquid phase.展开更多
In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservation...In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservations principle at the groove/land boundary in each method. The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in nu- merical method. It was observed that the numerical solutions had higher precision as mesh number exceed 70 x 70, and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.展开更多
To improve the microcrystalline silicon thin film deposition in quality and to increase its microcrystalline silicon content,we numerically investigated the characteristics of homogeneous discharges in hydrogen dilute...To improve the microcrystalline silicon thin film deposition in quality and to increase its microcrystalline silicon content,we numerically investigated the characteristics of homogeneous discharges in hydrogen diluted silane and argon mixed gases at atmospheric pressure using a two-dimensional fluid model.The model takes into account the primary processes of excitation and ionization,sixteen reactions of radicals with radicals in silane/hydrogen/argon discharges,so this model can adequately describe the discharge plasma.The effects of very high frequency(VHF)excitation on the electron density in such discharges are analyzed.The simulation results show that the electron density does not linearly vary with the excitation frequency within from 90150 MHz.he maximum value occurs at an appropriate excitation frequency i.e.the transition frequency.Increasof the excitation frequency would effectively increase the electron density before the transition frequency,but decreases the density afterwards.is.Moreover,the densities of involved particle species,including H2+,H,Ar*,Ar+,SiH3+,SiH3,SiH3,SiH2are closely interrelated.展开更多
Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produc...Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory.展开更多
Blood pressure and sleep,the two important indicators of health outcomes,are of increasing public health importance.There are variations in the blood pressure parameters during sleep and association exists between sle...Blood pressure and sleep,the two important indicators of health outcomes,are of increasing public health importance.There are variations in the blood pressure parameters during sleep and association exists between sleep and elevated blood pressure.The absence of nocturnal dipping of the blood pressure also increases cardiovascular risk.Sleep duration has been defined as normal(7-8 hours of sleep),short≤6 hours and long sleep≥9 hours.Short sleep duration is associated with hypertension especially during middle age and women who are deprived of sleep particularly post-menopausal had a higher risk of hypertension than men.Methodological concerns exist in the measurement of sleep duration,although both subjective and objective assessment of sleep duration showed an association with hypertension.Shorter sleep duration is believed to result in prolonged exposures to elevated sympathetic activity and psychosocial stressors.There is no enough evidence to support this statement for longer sleep duration.Long and short sleep duration are associated with the incidence of hypertension across most age groups.Relationships of short sleep are stronger among women and young adults compared to long sleep duration which is stronger among the elderly.展开更多
Background: The iStent inject is a Micro-Invasive Glaucoma Surgical (MIGS) device that has shown to reduce IOP and to be safe for glaucoma patients with fewer complications than regular surgery. Objective: To investig...Background: The iStent inject is a Micro-Invasive Glaucoma Surgical (MIGS) device that has shown to reduce IOP and to be safe for glaucoma patients with fewer complications than regular surgery. Objective: To investigate, up to 15 - 20 months, the efficacy and safety of implantation of two second-generation trabecular microbypass stents in patients with or without prior glaucoma surgery. Methods: Fifty-seven eyes were implanted with the iStent inject. The population was comprised of eyes with primary open-angle glaucoma (n = 51), pseudoexfoliation glaucoma (n = 5) and ocular hypertension (n = 1). Major outcome parameters included IOP, medication needs and corrected distance visual acuity (CDVA). Follow-up time points were one day, 2 - 4 months, 9 - 14 months and 15 - 20 months. Results: The main reason to perform MIGS was IOP reduction in 68.4%, reduced number of medications due to drug intolerance in 24.6% and reduced medication due to compliance issues in 7.0% of the eyes. IOP decreased by 22.47%, from 19.40 ± 3.83 mmHg preoperatively (preop) to 15.04 ± 1.67 mmHg at 15-20 months postoperatively. IOP reduction was achieved at all follow-up time points (p Conclusions: Insertion of the iStent inject in patients with or without prior glaucoma surgery shows effective and sustained improvements in IOP with no safety concerns.展开更多
The broken efficiency of cell wall and the release amount of Pichia pastoris intracellular protein under different cell breaking conditions were investigated in this paper. The results showed that broken efficiency us...The broken efficiency of cell wall and the release amount of Pichia pastoris intracellular protein under different cell breaking conditions were investigated in this paper. The results showed that broken efficiency using hot alkali combined with high-pressure homogenizing method was higher than that of enzyme hydrolysis, hot alkali treatment and high-pressure homogenation, respectively. Suspended medium had little effect on the broken efficiency of yeast cell, but had significant effect on the protein release yield. The results indicated that optimal condition for intracellular proteins extraction was 30% (wet weight, w/v) of yeast cells suspend in 50 mM phosphate buffer (pH 10.0), water bathed at 60?C for 2 hours, homogenized twice at 100 MPa pressure. The broken efficiency of Pichia pastoris cell could reach 87.6% and the protein yield was 35.48 g per 100 g cells.展开更多
The paper highlights the application of a recent semi-numerical successive linearization method(SLM)in solving highly coupled,nonlinear boundary value problem.The method is presented in detail by solving the problem o...The paper highlights the application of a recent semi-numerical successive linearization method(SLM)in solving highly coupled,nonlinear boundary value problem.The method is presented in detail by solving the problem of boundary layer convective heat transfer with low pressure gradient in the presence of viscous dissipation and radiation effects.The effects of the parameters on the flow are investigated.The velocity,temperature,skinfriction,and heat transfer coefficients have been obtained and discussed for various physical parametric values.展开更多
文摘The superplastic characteristics of the β-SiC whisker reinforced 2024 aluminum composite, fabricated by pressure infiltration and hot-rolling after extrusion, were investigated. The composite has a fine grain size of about 1μm, and exhibits a maximum tensile elongation of 370% in the initial strain rate of 3.3×10-3 s-1 at 788K.The superplastic deformation mechanism of the composite is thought to be grain boundary (interface) sliding accommodated by grain boundary diffusion of aluminum atom and an appropriate amount of liquid phase.
基金Supported by the Ministerial Level Foundation(2220060029)
文摘In order to calculate the pressure distribution of radial grooved thrust bearing, analytical and numerical methods were applied respectively. Grooved region and land region were linked by u- sing the mass conservations principle at the groove/land boundary in each method. The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in nu- merical method. It was observed that the numerical solutions had higher precision as mesh number exceed 70 x 70, and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.
基金Project supported by Liaoning Provincial Natural Science Foundation of China (201202037).
文摘To improve the microcrystalline silicon thin film deposition in quality and to increase its microcrystalline silicon content,we numerically investigated the characteristics of homogeneous discharges in hydrogen diluted silane and argon mixed gases at atmospheric pressure using a two-dimensional fluid model.The model takes into account the primary processes of excitation and ionization,sixteen reactions of radicals with radicals in silane/hydrogen/argon discharges,so this model can adequately describe the discharge plasma.The effects of very high frequency(VHF)excitation on the electron density in such discharges are analyzed.The simulation results show that the electron density does not linearly vary with the excitation frequency within from 90150 MHz.he maximum value occurs at an appropriate excitation frequency i.e.the transition frequency.Increasof the excitation frequency would effectively increase the electron density before the transition frequency,but decreases the density afterwards.is.Moreover,the densities of involved particle species,including H2+,H,Ar*,Ar+,SiH3+,SiH3,SiH3,SiH2are closely interrelated.
基金Supported by Tianjin Institute of Urban Construction(03046)
文摘Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory.
文摘Blood pressure and sleep,the two important indicators of health outcomes,are of increasing public health importance.There are variations in the blood pressure parameters during sleep and association exists between sleep and elevated blood pressure.The absence of nocturnal dipping of the blood pressure also increases cardiovascular risk.Sleep duration has been defined as normal(7-8 hours of sleep),short≤6 hours and long sleep≥9 hours.Short sleep duration is associated with hypertension especially during middle age and women who are deprived of sleep particularly post-menopausal had a higher risk of hypertension than men.Methodological concerns exist in the measurement of sleep duration,although both subjective and objective assessment of sleep duration showed an association with hypertension.Shorter sleep duration is believed to result in prolonged exposures to elevated sympathetic activity and psychosocial stressors.There is no enough evidence to support this statement for longer sleep duration.Long and short sleep duration are associated with the incidence of hypertension across most age groups.Relationships of short sleep are stronger among women and young adults compared to long sleep duration which is stronger among the elderly.
文摘Background: The iStent inject is a Micro-Invasive Glaucoma Surgical (MIGS) device that has shown to reduce IOP and to be safe for glaucoma patients with fewer complications than regular surgery. Objective: To investigate, up to 15 - 20 months, the efficacy and safety of implantation of two second-generation trabecular microbypass stents in patients with or without prior glaucoma surgery. Methods: Fifty-seven eyes were implanted with the iStent inject. The population was comprised of eyes with primary open-angle glaucoma (n = 51), pseudoexfoliation glaucoma (n = 5) and ocular hypertension (n = 1). Major outcome parameters included IOP, medication needs and corrected distance visual acuity (CDVA). Follow-up time points were one day, 2 - 4 months, 9 - 14 months and 15 - 20 months. Results: The main reason to perform MIGS was IOP reduction in 68.4%, reduced number of medications due to drug intolerance in 24.6% and reduced medication due to compliance issues in 7.0% of the eyes. IOP decreased by 22.47%, from 19.40 ± 3.83 mmHg preoperatively (preop) to 15.04 ± 1.67 mmHg at 15-20 months postoperatively. IOP reduction was achieved at all follow-up time points (p Conclusions: Insertion of the iStent inject in patients with or without prior glaucoma surgery shows effective and sustained improvements in IOP with no safety concerns.
文摘The broken efficiency of cell wall and the release amount of Pichia pastoris intracellular protein under different cell breaking conditions were investigated in this paper. The results showed that broken efficiency using hot alkali combined with high-pressure homogenizing method was higher than that of enzyme hydrolysis, hot alkali treatment and high-pressure homogenation, respectively. Suspended medium had little effect on the broken efficiency of yeast cell, but had significant effect on the protein release yield. The results indicated that optimal condition for intracellular proteins extraction was 30% (wet weight, w/v) of yeast cells suspend in 50 mM phosphate buffer (pH 10.0), water bathed at 60?C for 2 hours, homogenized twice at 100 MPa pressure. The broken efficiency of Pichia pastoris cell could reach 87.6% and the protein yield was 35.48 g per 100 g cells.
文摘基于光电容积脉搏波描记法(Photo Plethysmo Graphy,PPG)的柔性传感器可进行心率(Heart Rate,HR)和血压(Blood Pressure,BP)检测,但是对其检测结果的标定报道甚少.据此,本文提出一种基于模拟血液循环的反射式PPG心率检测和血压标定系统.以蠕动泵来产生脉动流,通过调节其转速的大小来控制模拟血液输送的频率和压力,从而引起弹性乳胶管内模拟血液体积的变化,而改变反射光的信号周期与强度,贴近于人体脉搏测量过程的实际场景.该系统心率检测误差均值为0.27778,95%一致性界限为(-2.59562,3.15117),所测收缩压(Systolic Blood Pressure,SBP)和舒张压(Diastolic Blood Pressure,DBP)的拟合优度分别为0.97185和0.98111.经标定后的柔性PPG传感器对4名志愿者检测的SBP和DBP的平均偏差(Mean Deviation,MD)±标准差(Standard Deviation,SD)均值分别为(1.21±2.16)mmHg和(0.76±2.02)mmHg,均符合且远小于美国医疗仪器促进协会(Association for the Advancement of Medical Instrumentation,AAMI)所制定的衡量血压计精度的标准指标(5±8)mmHg.结果表明,该系统能够准确高效地标定柔性PPG传感器,为实现便携式可穿戴设备的精准血压检测提供标定基础.
文摘The paper highlights the application of a recent semi-numerical successive linearization method(SLM)in solving highly coupled,nonlinear boundary value problem.The method is presented in detail by solving the problem of boundary layer convective heat transfer with low pressure gradient in the presence of viscous dissipation and radiation effects.The effects of the parameters on the flow are investigated.The velocity,temperature,skinfriction,and heat transfer coefficients have been obtained and discussed for various physical parametric values.