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Preparation of TiC powders by carbothermal reduction method in vacuum 被引量:21
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作者 森维 徐宝强 +4 位作者 杨斌 孙红燕 宋建勋 万贺利 戴永年 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第1期185-190,共6页
The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and th... The preparation of fine TiC powders by carbothermal reduction of TiO2 in vacuum was investigated by XRD,SEM,XRF and laser particle sizer.Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and the formation sequence of products are Ti4O7(Magneli phase),Ti3O5,Ti2O3,TiCxO1-x and TiC with the increase of reaction temperature.Experimental results demonstrate that TiC powders with single phase are obtained with molar ratio of TiO2 to C ranging from 1:3.2 to 1:6 at 1 550 ℃ for 4 h when the system pressure is 50 Pa,and TiC1.0 is gained when the molar ratio of TiO2 to C is 1:4 and 1:5.In addition,fine TiC1.0 powders(D50 equals 3.04 μm) with single phase and low impurities are obtained when the molar ratio of TiO2 to C is 1:4.SEM observation shows that uniform shape,low agglomeration,and loose structure are observed on the surface of block product. 展开更多
关键词 titanium dioxide titanium carbide vacuum carbothermal reduction method
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Improvement of silty clay by vacuum preloading incorporated with electroosmotic method 被引量:4
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作者 M. Q. Vu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2010年第4期365-372,共8页
A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where... A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where the horizontal electrode configurations beneath the soil layer were possible and the drainage pipes and the prefabricated vertical drains (PVDs) system could be easily installed in advance before the sludge dragged from sea bed or river bed was filled into the site. Three groups of tests were conducted on the silty clay from Qinhuai River in Nanjing, China. The model is able to apply vacuum pressure at the bottom of the soil layer and a direct current electric field simultaneously. It is also possible to measure the pore pressures at different depths of soil column, and the changes in settlement and volume with the elapsed time. In this study, the vacuum preloading method, vacuum preloading applied at the bottom (VAB method), was applied and the cathodes were installed beneath the soil layer. The results obtained indicate substantial reduction in water content, and increases in dry density and undrained shear strength in comparison with those obtained by the vacuum preloading only, particularly at the positions close to the anode. The combined method utilizes the vertical drainage flow created by the electroosmosis integrating the horizontal drainage flow created mostly by the vacuum pressure. The total drainage flow can be calculated as a result of the vertical drainage flow by electroosmosis only and the horizontal drainage flow by the vacuum preloading only. The way of placement of the cathode and the anode in the combined method also overcomes the disadvantage of EOM method itself, i.e. the appearance of cracks between the anode and the surrounding soil. Moreover, it is observed that the vacuum preloading plays a primary role in earlier stage in deduction of free pore water; meanwhile, the electroosmotic method is more efficient in later stage for absorbing water in the diffused double layers of soil. 展开更多
关键词 vacuum preloading VAB method soil improvement CONSOLIDATION pore pressure undrained shear strength dry density electroosmotic method
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Structure and Performance of Fe-N_x-C Catalyst for Oxygen Reduction Reaction Prepared by Vacuum Casting Method and the Second Pyrolysis 被引量:1
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作者 钱亚声 童磊 +2 位作者 邵宗贵 囤荣敏 李文木 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2018年第6期937-947,共11页
Affordable non-precious metal(NPM) catalysts played a vital role in the wide application of polymer electrolyte membrane fuel cells(PEMFC). In current work, a facile vacuum casting reacting method based on vacuum ... Affordable non-precious metal(NPM) catalysts played a vital role in the wide application of polymer electrolyte membrane fuel cells(PEMFC). In current work, a facile vacuum casting reacting method based on vacuum casting was introduced to prepare Fe-N_x-C oxygen reduction reaction(ORR) catalysts with high efficient in acid medium. The catalysts were prepared with ammonium ferrous sulfate hexahydrate(AFS) and 1,10-phenanthroline monohydrate utilizing homemade mesoporous silica template. The heat treatment and its influence on structure and performance were systematically evaluated to achieve superior ORR performance and some clues were found. And 850 ℃ was found to be the best temperature for the first and second pyrolysis. The linear sweep voltammetry(LSV) results showed that there were only 18 mV slightly negative shifts of half-wave potential(E_(1/2)) of the optimal catalyst(749 mV) compared with the commercial Pt/C(20 μg·Pt·cm^-2). Besides, I850 R also showed better electrochemical stability and methanol-tolerance than that of Pt/C. All evidences proved that our vacuum casting reacting strategy and heat treatment process were prospective for the future R&D of high performance Fe-N_x-C ORR catalysts. 展开更多
关键词 oxygen reduction reaction acid medium vacuum casting reacting method temperature affected structure second pyrolysis
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Constant Stress Accelerated Life Tests for Vacuum Fluorescent Display Based on Least Square Method
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作者 张建平 王睿韬 《Journal of Southwest Jiaotong University(English Edition)》 2010年第1期45-50,共6页
To estimate the life of vacuum fluorescent display (VFD) more accurately and reduce test time and cost, four constant stress accelerated life tests (CSALTs) were conducted on an accelerated life test model. In the... To estimate the life of vacuum fluorescent display (VFD) more accurately and reduce test time and cost, four constant stress accelerated life tests (CSALTs) were conducted on an accelerated life test model. In the model, statistical analysis of test data is achieved by applying lognormal function to describe the life distribution, and least square method (LSM) to calculate the mean value and the standard deviation of logarithm. As a result, the accelerated life equation was obtained, and then a self-developed software was developed to predict the VFD life. The data analysis results demonstrate that the VFD life submits to lognormal distribution, that the accelerated model meets the linear Arrhenius equation, and that the precise accelerated parameter makes it possible to acquire the life information of VFD within one month. 展开更多
关键词 vacuum fluorescent display Constant stress Accelerated life tests Least square method Lognormal distribution
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Vacuum Filling Simulation with Combined Lagranian and VOF Method
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作者 Yujia Chen Maoxuan Cai +2 位作者 Shixun Zhang Na Zhang Wei Cao 《Journal of Mechanical Materials and Mechanics Research》 2022年第1期1-9,共9页
Jetting succeeded by accumulation is the characteristic of the vacuum filling,which is different from the conventional pressure-driven flow.In order to simulate this kind of flow,a three-dimensional theoretical model ... Jetting succeeded by accumulation is the characteristic of the vacuum filling,which is different from the conventional pressure-driven flow.In order to simulate this kind of flow,a three-dimensional theoretical model in terms of incompressible and viscous flow is established,and an iterative method combined with finite element method(FEM)is proposed to solve the flow problem.The Lagranian-VOF method is constructed to trace the jetting and accumulated flow fronts.Based on the proposed model and algorithm,a simulation program is developed to predict the velocity,pressure,temperature,and advancement progress.To validate the model and algorithm,a visual experimental equipment for vacuum filling is designed and construted.The vacuum filling experiments with different viscous materials and negative pressures were conducted and compared with the corresponding simulations.The results show the flow front shape closely depends on the fluid viscosity and less relates to the vacuum pressure. 展开更多
关键词 vacuum Finite element method Lagranian technique VOF method Flow front
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Formulating Highway Paving Asphalts from the Vacuum Residue of a Paraffinic Crude 被引量:1
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作者 郭爱军 管翠诗 +2 位作者 王宗贤 刘峰友 彭海 《Petroleum Science》 SCIE CAS CSCD 2004年第3期87-92,共6页
Many specifications of paving asphalts are closely related to their colloidal stability, which is, however, determined by their exact chemical compositions. The Yumen vacuum residue (YVR), the bottoms of a paraffinic... Many specifications of paving asphalts are closely related to their colloidal stability, which is, however, determined by their exact chemical compositions. The Yumen vacuum residue (YVR), the bottoms of a paraffinic crude oil is unfit for the production of highway paving asphalts directly, Neither are the de-oiled asphalts of the YVR. In this research a blending method and an optimal process of solvent de-asphalts are adopted to investigate the feasibility of formulating highway-paving asphalts from YVR. Results show that highway paving asphalts are formulated by blending solvent de-oiled asphalts with one or more of the materials including YVR, decanted oil from FCC process, and furfural extracts from lubricating base stocks. Further investigations indicate that adding oil decanted from FCC process to the solvent de-asphalting process can increase the de-asphalted oil production, improve the de-oiled asphalts quality, and thus optimize the refinery processes. The methodology of this research can be extended even to refineries processing non-paraffinic crude oils. 展开更多
关键词 Paraffinic crude oil vacuum residue paving asphalts FCC decanted oil solvent de-asphalting process blending method refinery optimization
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The Impact of Electrode Configuration on Characteristics of Vacuum Discharge Plasma 被引量:5
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作者 刘文正 张德金 孔飞 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第2期122-128,共7页
Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteri... Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy. 展开更多
关键词 electrode configuration vacuum PLASMA probe method generation charac- teristics
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FEM analysis of vacuum hot bulge forming of Hastelloy C-276 thin-walled cylindrical workpiece 被引量:2
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作者 朱智 张立文 顾森东 《Journal of Central South University》 SCIE EI CAS 2014年第8期3019-3023,共5页
A stress relaxation test has been carried out for Hastelloy C-276 at temperature of 800 ~C and initial stress level of 250 MPa. Based on the experimental stress relaxation curve, the relationship between creep strain ... A stress relaxation test has been carried out for Hastelloy C-276 at temperature of 800 ~C and initial stress level of 250 MPa. Based on the experimental stress relaxation curve, the relationship between creep strain rate and stress has been derived. Then, a set of creep constitutive equations has been built and the values of constants arising in the constitutive equations have been determined by fitting the creep strain rate-stress curve. Close agreement between computed results and experimental ones is obtained for stress relaxation data. The creep constitutive equation set has been integrated with the commercial FE (finite element) solver MSC.Marc via the user defined subroutine, CRPLAW, for the vacuum hot bulge forming process modelling of Hastelloy C-276 thin-walled cylindrical workpiece. The temperature field, the radius-direction displacement field and the stress-strain field are calculated and analyzed. Furthermore, the bulging dimension and the final internal diameter of workpiece are predicted and the test results verify the reliability of the finite element method. 展开更多
关键词 Hastelloy C-276 vacuum hot bulge forming creep constitutive equation finite element method
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A study of metal/die interfacial heat transfer behavior of vacuum die cast pure copper 被引量:2
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作者 Hong-mei Yang Zhou-meng Pu +2 位作者 Zhi-peng Guo Ang Zhang Shou-mei Xiong 《China Foundry》 SCIE 2020年第3期206-211,共6页
High pressure die casting copper is used to produce rotors for induction motors to improve efficiency.Experiments were carried out for a special"step-shape"casting with different step thicknesses.Based on th... High pressure die casting copper is used to produce rotors for induction motors to improve efficiency.Experiments were carried out for a special"step-shape"casting with different step thicknesses.Based on the measured temperature inside the die,the interfacial heat transfer coefficient(IHTC)at the metal/die interface during vacuum die casting was evaluated by solving the inverse problem.The IHTC peak value was 4.5×10^3-11×10^3 W·m^-2·K^-1 under the basic operation condition.The influences of casting pressure,fast shot speed,pouring temperature and initial die surface temperature on the IHTC peak values were investigated.Results show that a greater casting pressure and faster shot speed could only increase the IHTC peak values at the location close to the ingate.An increase of pouring temperature and/or initial die surface temperature significantly increases the IHTC peak values. 展开更多
关键词 vacuum die casting interfacial heat transfer behavior inverse method copper metal/die interface
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Improvements of marine clay slurries using chemicale-physical combined method(CPCM) 被引量:1
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作者 Dongqing Wu Wenyu Xu Romy Tjuar 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2015年第2期220-225,共6页
In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods(CPCMs) for treatment of marine clay (MC) slurries were evaluated. The method CPCM1 combineschemical stabilization ... In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods(CPCMs) for treatment of marine clay (MC) slurries were evaluated. The method CPCM1 combineschemical stabilization and vacuum preloading (VP), while CPCM2 is similar to CPCM1 but includes boththe application of surcharge and use of geo-bags to provide confinement during surcharge preloading.The key advantage of CPCM2 using geo-bags is that the surcharge can be immediately applied on thechemically stabilized slurries. Two types of geo-bags were investigated under simulated land filling anddyke conditions, respectively. The test results show that the shear strength (cu) of treated slurry byCPCM2 is generally much higher than that by CPCM1. Besides, the use of CPCM2 can significantly reducethe treatment time due to the short drainage paths created by geo-bags. Overall, CPCM2 allows fasterconsolidation and higher preloading that help to achieve higher mechanical properties of the stabilizedslurry. There are consistent relationships between cU and water content of slurries treated by CPCM2.Several important observations were also made based on comparisons of experimental data. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved. 展开更多
关键词 Chemical e physical combined method(CPCM) Soil improvement Marine clay(MC) slurry Land reclamation Chemical stabilization vacuum preloading(VP) Geo-bags SURCHARGE
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Rarefied planar jets into vacuum 被引量:1
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作者 Chunpei Cai Limei Wang 《Theoretical & Applied Mechanics Letters》 CAS 2012年第1期62-66,共5页
This paper presents a fundamental gaskinetic study on high speed rarefied jets expanding into vacuum from a cluster of planar exits.Based on the corresponding exact expressions for one planar jet,this paper straightfo... This paper presents a fundamental gaskinetic study on high speed rarefied jets expanding into vacuum from a cluster of planar exits.Based on the corresponding exact expressions for one planar jet,this paper straightforwardly derives the combined multiple jet flowfield solutions of density and velocity components,however,for the combined temperature and pressure solutions,extra attention shall be practiced.Several direct simulation Monte Carlo simulation results are provided and they validate these analytical solutions of rarefied planar jet flows. 展开更多
关键词 rarefied flows JET molecular beams vacuum Monte Carlo method
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Numerical Analysis on Neutron Shielding Structure of ITER Vacuum Vessel
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作者 刘常乐 武松涛 +1 位作者 郁杰 盛道林 《Plasma Science and Technology》 SCIE EI CAS CSCD 2008年第3期373-378,共6页
The neutron shielding component of ITER (International Thermonuclear Experimental Reactor) vacuum vessel is a kind of structure resembling a wall in appearance. A FE (finite element) model is set up by using ANSYS... The neutron shielding component of ITER (International Thermonuclear Experimental Reactor) vacuum vessel is a kind of structure resembling a wall in appearance. A FE (finite element) model is set up by using ANSYS code in terms of its structural features. Static analysis, thermal expansion analysis and dynamic analysis are performed. The static results show that the stress and displacement distribution are allowable, but the high stress appears in the junction between the upper and lower parts. The modal analysis indicates that the biggest deformation exists in the port area. Through modal superposition, the single-point response has been found with the lower rank frequency of the acceleration seismic response spectrum. But the deformation and the stress values are within the permissible limit. The analysis results would benefit the work in the next step and provide some reference for the implementation of the engineering plan in the future. 展开更多
关键词 ITER vacuum vessel neutron shielding structure numerical analysis finite element method
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Structure,Adhesion Strength and Corrosion Resistance of Vacuum Arc Multi-Period NbN/Cu Coatings
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作者 H.O.Postelnyk O.V.Sobol’ +1 位作者 O.Chocholaty G.I.Zelenskaya 《Journal of Metallic Material Research》 2020年第1期1-6,共6页
resistance,and adhesive strength of vacuum-arc multi-period NbN/Cu coatings is studied.It was found that in thin layers(about 8 nm,in a constant rotation mode),regardless of the change in the pressure of the nitrogen ... resistance,and adhesive strength of vacuum-arc multi-period NbN/Cu coatings is studied.It was found that in thin layers(about 8 nm,in a constant rotation mode),regardless of the change in the pressure of the nitrogen atmosphere,a metastableδ-NbN phase forms(cubic crystal lattice of the NaCl type).At a layer thickness of^40 nm or more,a phase composition changes from the metastableδ-NbN to the equilibriumε-NbN phase with a hexagonal crystal lattice.In the presence of theε-NbN phase in the niobium nitride layers,the highest adhesive strength is achieved with a value of LС5=96.5 N.Corrosion resistance tests have shown that for all the studied samples the corrosion process has mainly an anodic reaction.The highest corrosion resistance was shown by coatings obtained at a pressure of 7·10-4 Torr,with the smallest bias potential of-50 V and the smallest layer thickness;with a thickness of such a coating of about 10 microns,its service life in the environment of the formation of chloride ions is about a year. 展开更多
关键词 vacuum ARC method NbN/Cu Phase composition ADHESION strength IMPEDANCE spectroscopy Polarization resistance
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预处理方式对冻干草莓片品质的影响 被引量:1
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作者 胡云峰 余静 +2 位作者 吕婉莹 陈君然 路敏 《粮食与油脂》 北大核心 2024年第5期79-83,共5页
以草莓为原料制备冻干草莓片,研究鲜切冻藏、亚冻结切片和完全解冻切片3种不同预处理方式对冻干草莓片品质的影响。分析了冷冻草莓原料水分间的迁移情况、花色苷含量,并评价了冻干草莓片的感官品质和质构特性。结果表明:在3种预处理方... 以草莓为原料制备冻干草莓片,研究鲜切冻藏、亚冻结切片和完全解冻切片3种不同预处理方式对冻干草莓片品质的影响。分析了冷冻草莓原料水分间的迁移情况、花色苷含量,并评价了冻干草莓片的感官品质和质构特性。结果表明:在3种预处理方式中鲜切冻藏(-25℃)和亚冻结切片(-5~-8℃)草莓原料品质较好,水分迁移较小,花色苷含量无显著变化,且两者的冻干草莓片硬度、弹性、形变率等质构特性较好,感官品质与新鲜草莓的冻干成品接近。因此,在草莓冻干加工中宜选用鲜切冻藏或亚冻结切片草莓为加工原料。 展开更多
关键词 预处理方式 草莓 冷冻 解冻 真空冷冻干燥
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不同干燥方式对柠檬片品质的影响 被引量:1
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作者 郭红莲 张曼 +2 位作者 白亚辉 路敏 陈君然 《中国调味品》 CAS 北大核心 2024年第6期31-35,共5页
该研究旨在探究不同干燥方式对贮藏期柠檬片品质的影响。分别采用真空冷冻干燥(vacuum freeze drying,VFD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)3种方式加工制备柠檬片,并研究了3种干燥方式对柠檬片色泽、基... 该研究旨在探究不同干燥方式对贮藏期柠檬片品质的影响。分别采用真空冷冻干燥(vacuum freeze drying,VFD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)3种方式加工制备柠檬片,并研究了3种干燥方式对柠檬片色泽、基础品质、营养物质和风味的影响。结果表明,柠檬片经过真空冷冻干燥、热风干燥、微波干燥不同干燥处理后品质与风味不同。冻干组柠檬片具有较小的收缩率(11.65%),较高的复水比(5.14)、亮度值(48.6)和V_(C)含量(3.13 mg/g DW),电子鼻各传感器的响应值较高,即其色泽、品质、风味都优于热风干燥与微波干燥方式。因此,使用冻干工艺可以保证品质。 展开更多
关键词 柠檬片 干燥方式 真空冷冻干燥 热风干燥 微波干燥 营养物质 风味 色泽
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铀矿实物地质资料保护技术探究——以铀矿岩心保护为例
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作者 田宇 刘丹 陈江源 《铀矿地质》 CAS CSCD 2024年第5期1014-1018,共5页
岩心是铀矿资源勘查和开发中重要的数据来源,其对于研究矿床成因、预测矿床分布、评价矿产资源量和开采等具有重要意义。文章深入探究了岩心的保护技术,分析了目前常见的保护方法——石蜡封护法、树脂浇筑法以及真空包覆法的优缺点及对... 岩心是铀矿资源勘查和开发中重要的数据来源,其对于研究矿床成因、预测矿床分布、评价矿产资源量和开采等具有重要意义。文章深入探究了岩心的保护技术,分析了目前常见的保护方法——石蜡封护法、树脂浇筑法以及真空包覆法的优缺点及对铀矿岩心的适用性。研究结果表明,石蜡封护法、树脂浇筑法和真空包覆法均可用于铀矿岩心保护,应根据实际需要选择最适合的方法,真空包覆法在铀矿实物地质资料保护中的实用性更强,应加强这一方法的应用研究。 展开更多
关键词 铀矿岩心 保护技术 石蜡封护法 树脂浇筑法 真空包覆法
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时域间断伽辽金-粒子模拟方法研究进展
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作者 陈再高 齐红新 +1 位作者 李炎培 任泽平 《电波科学学报》 CSCD 北大核心 2024年第5期818-826,共9页
时域间断伽辽金-粒子模拟(discontinuous Galerkin time-domain particle-in-cell,DGTD-PIC)方法采用非结构网格能准确描述复杂结构,采用高阶基函数进一步提高了计算的精度,同时避免了求解大型逆矩阵,在等离子体和高功率电磁学相关数值... 时域间断伽辽金-粒子模拟(discontinuous Galerkin time-domain particle-in-cell,DGTD-PIC)方法采用非结构网格能准确描述复杂结构,采用高阶基函数进一步提高了计算的精度,同时避免了求解大型逆矩阵,在等离子体和高功率电磁学相关数值模拟方面具有广泛的用途。近年来国内外报道了大量DGTD-PIC方面的研究工作,该方法在核心关键技术方面已取得了许多突破性进展。为促进DGTD-PIC方法的发展及应用,本文对该方法在修正势的DGTD电磁场计算方法、复频移完全匹配层边界、非结构网格中带电粒子定位与电荷和电流分配等关键技术方面所取得的研究成果进行了详细介绍。 展开更多
关键词 等离子体模拟 时域间断伽辽金(DGTD)方法 有限元方法 全电磁粒子模拟算法 真空电子器件
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侧向排汽凝汽器设计与研发
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作者 宫传瑶 季丹 陈建 《电站辅机》 2024年第2期1-4,16,共5页
介绍了侧向排汽凝汽器的设计要点及关键技术,包括汽轮机与凝汽器的整体布置方案、凝汽器管束布置、凝汽器数值传热和真空力平衡方式等。侧向排汽机组布置紧凑,减少了土建成本,具有良好的社会及经济效益,通过对其设计与研发的介绍,为侧... 介绍了侧向排汽凝汽器的设计要点及关键技术,包括汽轮机与凝汽器的整体布置方案、凝汽器管束布置、凝汽器数值传热和真空力平衡方式等。侧向排汽机组布置紧凑,减少了土建成本,具有良好的社会及经济效益,通过对其设计与研发的介绍,为侧向排汽机组的推广提供了技术支持。 展开更多
关键词 侧向排汽 管束 凝汽器数值传热 真空力平衡方式
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真空微波干燥对草莓脯品质的影响 被引量:1
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作者 何茸茸 牛丽影 +6 位作者 李大婧 张钟元 唐冬妹 刘春菊 肖亚冬 聂梅梅 肖丽霞 《食品工业科技》 CAS 北大核心 2024年第16期64-72,共9页
为了研究真空环境下不同微波干燥条件对草莓脯质地和营养品质的影响,本文以热风干燥为对照,对3种真空微波处理条件(2.5 w/g-1.5 h、3.5 w/g-1 h、4.5 w/g-0.5 h)获得的草莓脯的水分迁移特性、质构特性、微观结构、色泽及花色苷和酚类物... 为了研究真空环境下不同微波干燥条件对草莓脯质地和营养品质的影响,本文以热风干燥为对照,对3种真空微波处理条件(2.5 w/g-1.5 h、3.5 w/g-1 h、4.5 w/g-0.5 h)获得的草莓脯的水分迁移特性、质构特性、微观结构、色泽及花色苷和酚类物质进行了测定。结果显示,真空微波干燥将草莓脯干燥至含水量20%±2%所需时间显著低于热风,微波功率越大,干燥时间越短。另外,干燥后获得的草莓脯中水分主要呈现结合水与不易流动水2种状态。真空微波干燥获得草莓脯的弛豫时间T2随微波功率增加而增大,说明水分自由度增加;横截面显微观察发现,真空微波干燥使细胞壁发生破裂,微波功率越大,裂隙形成部位越靠近髓芯,裂隙越大,孔隙率越小,而热风干燥的样品细胞完整性、孔隙率高于微波干燥。另外,真空微波干燥的草莓脯硬度、粘力、a^(*)值均低于热风干燥的样品,但L^(*)值、总糖、花青素以及酚类物质的含量均较高。综上所述,真空微波干燥具有更高的干燥效率,并能更好保留草莓脯中花色苷等营养物质。 展开更多
关键词 草莓脯 干燥 真空微波 理化品质
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不同干燥方式对毛竹笋全粉中氨基酸含量和蛋白质结构的影响 被引量:1
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作者 李艳艳 杨金来 +4 位作者 吴琰 李彬 张甫生 吴良如 郑炯 《食品与发酵工业》 CAS CSCD 北大核心 2024年第15期241-247,共7页
为探究不同干燥方式对竹笋全粉氨基酸含量及蛋白质结构的影响,该实验采用喷雾干燥(spray drying,SD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)、低温真空干燥(low-temperature vacuum drying,LVD)4种方式制备毛... 为探究不同干燥方式对竹笋全粉氨基酸含量及蛋白质结构的影响,该实验采用喷雾干燥(spray drying,SD)、热风干燥(hot air drying,HAD)、微波干燥(microwave drying,MD)、低温真空干燥(low-temperature vacuum drying,LVD)4种方式制备毛竹笋全粉(Phyllostachys pubescens shoot powder,PPSP),分析了4种干燥方式的PPSP氨基酸组成及含量,并基于拉曼光谱酰胺Ⅰ带比较了4组样品蛋白质二级结构变化。结果表明,LVD制备的PPSP总氨基酸含量最高,为29.19 g/100 g,其次为SD,HAD制备的PPSP总氨基酸含量最低。LVD组的PPSP中必需氨基酸含量最高,为10.43 g/100 g,占总氨基酸含量的35.73%。LVD和SD制备的PPSP中呈味氨基酸含量分别为17.58 g/100 g、15.81 g/100 g,显著高于HAD和MD组的呈味氨基酸含量。LVD样品中氨基酸组成最接近于标准模式谱。通过主成分分析提取出2个主成分,累计方差贡献率达89.45%,综合评分结果为:LVD>SD>MD>HAD,聚类热图将4种干燥方式分为3类。干燥后的PPSP蛋白质中β-折叠结构最高,占总二级结构的74.66%~83.35%,HAD样中β-折叠、α-螺旋结构含量明显高于其他样品。该研究可为毛竹笋干燥及竹笋全粉的开发利用提供理论参考。 展开更多
关键词 毛竹笋全粉 干燥方式 低温真空干燥 氨基酸含量 蛋白质二级结构
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