The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equati...The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equation and the second virial coefficient was determined by the Vetere model. Then the standard enthalpy of vaporization for n-butyl carbamate was estimated. The heat capacity was measured for the solid state(299.39–324.2 K) and liquid state(336.65–453.21 K) by means of adiabatic calorimeter. The standard enthalpy of formation ΔfH[crystal(cr),298.15 K] and standard entropy S(crystal,298.15 K) of the substance were calculated on the basis of the gas-phase standard enthalpy of formation ΔfH(g,298.15 K)and gas-phase standard entropy S(g,298.15 K), which were estimated by the Benson method. The results are acceptable, validated by a thermochemical cycle.展开更多
Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property ...Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property rights, namely Elastic Structure Design, Anti-blocking Safety, Pressure Relief Safety and Lid Closing Safety. In the mean time, when participating in the activities related with revision proposals on IEC standard Electric Pressure Cooker, EPCA makes full use of the information and experience gained in these activities, improves and put forward the new-edition Electric Pressure Cooker Alliance Standard （hereafter referred to as Alliance Standard）. This article is an interpretation with this Alliance Standard aiming at bettering the pressure cooker enterprises＇ understanding with this standard, so as to guide the alliance enterprises to highlight the differentiated characteristics and product features in the links like products design, procurement of raw and auxiliary materials, manufacturing and sales, etc., as well as to let industrial peers learn about the characteristics of this standard and the products.展开更多
The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining ...The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.展开更多
Sulfur speciation and concentration in geothermal water are of great significance for the research and utilization of the water resources.In most situations,it is necessary to determine the total sulfur in geothermal ...Sulfur speciation and concentration in geothermal water are of great significance for the research and utilization of the water resources.In most situations,it is necessary to determine the total sulfur in geothermal water.In this study,the method was established for the determination of determining total sulfur content-the inductively coupled plasma-atomic emission spectrometry(ICP-AES),with the wavelength of 182.034 nm selected in spectral line of sulfur.It was identified that the optimal working conditions of the ICP-AES instrument were 1200 W for high frequency generator power 9 mm for vertical observation height,0.30 MPa atomizer pressure,and 50 r/min analytical pump speed.The matrix interference of the method was eliminated by the matrix matching method.Using this method,sulfur detection limit and minimum quantitative detection limit were 0.028 mg/L and 0.110 mg/L,respectively,whilst the linear range was 0.0-100.0 mg/L.The recovery rate of sample was between 90.67%and 108.7%,and the relative standard deviation(RSD)was between 0.36%and 2.14%.The method was used to analyze the actual samples and the results were basically consistent with the industry standard method.With high analysis efficiency,the method has low detection limit and minimum quantitative detection limit,wide linear range,good precision and accuracy,and provides an important detection method for the determination of total sulfur in geothermal water.展开更多
The experimental investigation of unsteady complex flow fields in wind tunnels requires advanced measurement techniques. The most important of such image based measurement techniques are those for the measurement of p...The experimental investigation of unsteady complex flow fields in wind tunnels requires advanced measurement techniques. The most important of such image based measurement techniques are those for the measurement of planar flow velocity fields, planar pressure distribution, model location and deformation, model temperature and quantitative high speed flow visualization. The applications as carried out by DLR range from low speed flows to transonic flows, from high lift configurations to propellers and rotors, from wake vortex investigations in catapult facilities and water towing tanks to investigations of vortex break down phenomena on delta wings. The capability to use image based measurement techniques in transonic flows requires dedicated technical developments and experienced scientists due to the special environment of a transonic wind tunnel. In this paper an overview of the state-of-the art of the application of image based measurement techniques in transonic flows as performed by DLR＇s Institute of Aerodynamics and Flow Technology will be given.展开更多
植被物候直接影响其生物量,调控生态系统碳循环过程。目前,气候变化(尤其干旱)对中国中高纬度植被物候的影响依然不清楚。因此,文章基于GIMMS NDVI3g数据集,提取中国30°N以北地区中多种植被类型生长季的开始日期(Start of the Seas...植被物候直接影响其生物量,调控生态系统碳循环过程。目前,气候变化(尤其干旱)对中国中高纬度植被物候的影响依然不清楚。因此,文章基于GIMMS NDVI3g数据集,提取中国30°N以北地区中多种植被类型生长季的开始日期(Start of the Season,SOS)与结束日期(End of the Season,EOS)两物候参数。然后结合野外观测数据,验证提取物候参数结果可靠性,并结合饱和水汽压差(Vapor Pressure Deficit,VPD)与改进后的标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI)探究植被物候对干旱的响应特征规律。结果表明:(1)不同地区的植被物候变化呈现明显的差异性,单季植被与双季植被第1个生长季的SOS集中在每年的第30~180天,而双季植被第2个生长季的SOS集中在每年的第200~220天。单季植被与双季植被第1个生长季的EOS主要集中在每年的第180~300天,双季植被第2个生长季的EOS主要集中在每年的第260~300天。(2)森林季前VPD的上升导致植被的SOS提前及EOS延迟;草地季前VPD上升导致植被的SOS滞后以及EOS提前。(3)研究区内大部分地区的SPEI与植被的SOS、EOS均呈正相关,即干旱促使该地区植被的SOS、EOS提前。展开更多
目的分析我国高龄高血压住院患者在降压标准150/90 mm Hg(1 mm Hg=0.133 kPa)下的降压达标率、用药及并发症分布情况。方法选择解放军空军特色医学中心所有科室年龄≥80岁且被诊断为高血压的409例住院患者为研究对象,将409例患者分为强...目的分析我国高龄高血压住院患者在降压标准150/90 mm Hg(1 mm Hg=0.133 kPa)下的降压达标率、用药及并发症分布情况。方法选择解放军空军特色医学中心所有科室年龄≥80岁且被诊断为高血压的409例住院患者为研究对象,将409例患者分为强化降压组(106例,收缩压<130 mm Hg)、标准降压组(155例,收缩压130~149 mm Hg)和降压未达标组(148例,收缩压≥150 mm Hg),分析各组患者血压控制现状。结果以150/90 mm Hg为降压标准时,强化降压组占25.9%,标准降压组占37.9%,降压未达标组占36.2%,降压未达标组年龄>90岁比例显著低于强化降压组和标准降压组(4.1%vs 7.5%、12.3%,P<0.05)。标准降压组一联用药比例显著高于强化降压组(46.5%vs 32.1%),强化降压组二联用药比例显著高于标准降压组(35.8%vs 22.6%),差异有统计学意义(P<0.05)。强化降压组并发心脏损害和脑血管损害比例显著高于标准降压组(43.4%vs 21.9%,26.4%vs 14.8%),合并视网膜病变比例显著低于标准降压组(11.3%vs 23.9%),差异有统计学意义(P<0.05)。结论对于高龄高血压患者,以150/90 mm Hg为启动降压标准更具有科学性、实用性,强化降压反而增加了高龄高血压患者心脑血管损害。展开更多
文摘The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equation and the second virial coefficient was determined by the Vetere model. Then the standard enthalpy of vaporization for n-butyl carbamate was estimated. The heat capacity was measured for the solid state(299.39–324.2 K) and liquid state(336.65–453.21 K) by means of adiabatic calorimeter. The standard enthalpy of formation ΔfH[crystal(cr),298.15 K] and standard entropy S(crystal,298.15 K) of the substance were calculated on the basis of the gas-phase standard enthalpy of formation ΔfH(g,298.15 K)and gas-phase standard entropy S(g,298.15 K), which were estimated by the Benson method. The results are acceptable, validated by a thermochemical cycle.
文摘Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property rights, namely Elastic Structure Design, Anti-blocking Safety, Pressure Relief Safety and Lid Closing Safety. In the mean time, when participating in the activities related with revision proposals on IEC standard Electric Pressure Cooker, EPCA makes full use of the information and experience gained in these activities, improves and put forward the new-edition Electric Pressure Cooker Alliance Standard （hereafter referred to as Alliance Standard）. This article is an interpretation with this Alliance Standard aiming at bettering the pressure cooker enterprises＇ understanding with this standard, so as to guide the alliance enterprises to highlight the differentiated characteristics and product features in the links like products design, procurement of raw and auxiliary materials, manufacturing and sales, etc., as well as to let industrial peers learn about the characteristics of this standard and the products.
基金National Natural Science Foundation of China(No.51675399)。
文摘The pressure pulsation of axial piston pump is not only an important cause of rotation speed fluctuation,vibration noise and output stability of the hydraulic system,but also the main information source for obtaining fault information.Hydraulic system is characterized by strong noise interference,which leads to low signal-to-noise ratio(SNR)of detection signals.Therefore,it is necessary to dig deep into the system operating state information carried by pressure signals.Firstly,based on flow loss mechanism of the plunger pump,the mapping relationship between flow pulsation and pressure pulsation is analyzed.After that,the pressure signal is filtered and reconstructed based on standard Gabor transform.Finally,according to the time-domain waveform morphology of pressure signal,four characteristic indicators are proposed to analyze the characteristics of pressure fluctuations under different working conditions.The experimental results show that the standard Gabor transform can accurately extract high-order harmonics and phase frequencies of the signal.The reconstructed time-domain waveform of pressure pulsation of the axial piston pump contains a wealth of operating status information,and the characteristics of pulsation changes under various working conditions can provide a new theoretical basis and a method support for fault diagnosis and health assessment of hydraulic pumps,motors and key components.
基金supported by the Fundamental Research Fund Project(SK201908)of the Institute of Hydrogeology and Environmental Geology,Chinese Academy of Geological Sciences.
文摘Sulfur speciation and concentration in geothermal water are of great significance for the research and utilization of the water resources.In most situations,it is necessary to determine the total sulfur in geothermal water.In this study,the method was established for the determination of determining total sulfur content-the inductively coupled plasma-atomic emission spectrometry(ICP-AES),with the wavelength of 182.034 nm selected in spectral line of sulfur.It was identified that the optimal working conditions of the ICP-AES instrument were 1200 W for high frequency generator power 9 mm for vertical observation height,0.30 MPa atomizer pressure,and 50 r/min analytical pump speed.The matrix interference of the method was eliminated by the matrix matching method.Using this method,sulfur detection limit and minimum quantitative detection limit were 0.028 mg/L and 0.110 mg/L,respectively,whilst the linear range was 0.0-100.0 mg/L.The recovery rate of sample was between 90.67%and 108.7%,and the relative standard deviation(RSD)was between 0.36%and 2.14%.The method was used to analyze the actual samples and the results were basically consistent with the industry standard method.With high analysis efficiency,the method has low detection limit and minimum quantitative detection limit,wide linear range,good precision and accuracy,and provides an important detection method for the determination of total sulfur in geothermal water.
文摘The experimental investigation of unsteady complex flow fields in wind tunnels requires advanced measurement techniques. The most important of such image based measurement techniques are those for the measurement of planar flow velocity fields, planar pressure distribution, model location and deformation, model temperature and quantitative high speed flow visualization. The applications as carried out by DLR range from low speed flows to transonic flows, from high lift configurations to propellers and rotors, from wake vortex investigations in catapult facilities and water towing tanks to investigations of vortex break down phenomena on delta wings. The capability to use image based measurement techniques in transonic flows requires dedicated technical developments and experienced scientists due to the special environment of a transonic wind tunnel. In this paper an overview of the state-of-the art of the application of image based measurement techniques in transonic flows as performed by DLR＇s Institute of Aerodynamics and Flow Technology will be given.
文摘植被物候直接影响其生物量,调控生态系统碳循环过程。目前,气候变化(尤其干旱)对中国中高纬度植被物候的影响依然不清楚。因此,文章基于GIMMS NDVI3g数据集,提取中国30°N以北地区中多种植被类型生长季的开始日期(Start of the Season,SOS)与结束日期(End of the Season,EOS)两物候参数。然后结合野外观测数据,验证提取物候参数结果可靠性,并结合饱和水汽压差(Vapor Pressure Deficit,VPD)与改进后的标准化降水蒸散指数(Standardized Precipitation Evapotranspiration Index,SPEI)探究植被物候对干旱的响应特征规律。结果表明:(1)不同地区的植被物候变化呈现明显的差异性,单季植被与双季植被第1个生长季的SOS集中在每年的第30~180天,而双季植被第2个生长季的SOS集中在每年的第200~220天。单季植被与双季植被第1个生长季的EOS主要集中在每年的第180~300天,双季植被第2个生长季的EOS主要集中在每年的第260~300天。(2)森林季前VPD的上升导致植被的SOS提前及EOS延迟;草地季前VPD上升导致植被的SOS滞后以及EOS提前。(3)研究区内大部分地区的SPEI与植被的SOS、EOS均呈正相关,即干旱促使该地区植被的SOS、EOS提前。
文摘目的分析我国高龄高血压住院患者在降压标准150/90 mm Hg(1 mm Hg=0.133 kPa)下的降压达标率、用药及并发症分布情况。方法选择解放军空军特色医学中心所有科室年龄≥80岁且被诊断为高血压的409例住院患者为研究对象,将409例患者分为强化降压组(106例,收缩压<130 mm Hg)、标准降压组(155例,收缩压130~149 mm Hg)和降压未达标组(148例,收缩压≥150 mm Hg),分析各组患者血压控制现状。结果以150/90 mm Hg为降压标准时,强化降压组占25.9%,标准降压组占37.9%,降压未达标组占36.2%,降压未达标组年龄>90岁比例显著低于强化降压组和标准降压组(4.1%vs 7.5%、12.3%,P<0.05)。标准降压组一联用药比例显著高于强化降压组(46.5%vs 32.1%),强化降压组二联用药比例显著高于标准降压组(35.8%vs 22.6%),差异有统计学意义(P<0.05)。强化降压组并发心脏损害和脑血管损害比例显著高于标准降压组(43.4%vs 21.9%,26.4%vs 14.8%),合并视网膜病变比例显著低于标准降压组(11.3%vs 23.9%),差异有统计学意义(P<0.05)。结论对于高龄高血压患者,以150/90 mm Hg为启动降压标准更具有科学性、实用性,强化降压反而增加了高龄高血压患者心脑血管损害。
