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Using crosslinked polyvinyl alcohol polymer membrane as a separator in the microbial fuel cell

Yanping HOU, Kaiming LI, Haiping LUO, Guangli LIU, Renduo ZHANG, Bangyu QIN, Shanshan CHEN

《环境科学与工程前沿(英文)》 2014年 第8卷 第1期   页码 137-143 doi: 10.1007/s11783-013-0534-z

摘要: Separator between anode and cathode is an essential part of the microbial fuel cell (MFC) and its property could significantly influence the system performance. In this study we used polyvinyl alcohol (PVA) polymer membrane crosslinked with sulfosuccinic acid (SSA) as a new separator for the MFC. The highest power density of 759±4 mW·m was obtained when MFC using the PVA membrane crosslinked with 15% of SSA due to its desirable proton conductivity (5.16 × 10 S·cm ). The power density significantly increased to 1106±30?mW·m with a separator-electrode-assembly configuration, which was comparable with glass fiber (1170±46?mW·m ). The coulombic efficiencies of the MFCs with crosslinked PVA membranes ranged from 36.3% to 45.7% at a fix external resistance of 1000 ?. The crosslinked PVA membrane could be a promising alternative to separator materials for constructing practical MFC system.

关键词: microbial fuel cell     crosslinked polyvinyl alcohol (PVA) membrane     separator material     power generation     coulombic efficiency    

Regulating surface chemistry of separator with LiF for advanced Li-S batteries

《能源前沿(英文)》 2022年 第16卷 第4期   页码 601-606 doi: 10.1007/s11708-021-0759-7

摘要: Lithium-sulfur (Li-S) batteries have attracted intensive attention owing to their ultrahigh theoretical energy density. Nevertheless, the practical application of Li-S batteries is prevented by uncontrollable shuttle effect and retarded reaction kinetics. To address the above issues, lithium fluoride (LiF) was employed to regulate the surface chemistry of routine separator. The functional separator demonstrates a great ability to suppress active S loss and protect lithium anode. This work provides a facile strategy for the development of advanced Li-S batteries.

关键词: Li-S batteries     LiF     functional separator    

Experimental investigation on oil-gas separator of air-conditioning systems

Dianbo XIN,Shuliang HUANG,Song YIN,Yuping DENG,Wenqiang ZHANG

《能源前沿(英文)》 2019年 第13卷 第2期   页码 411-416 doi: 10.1007/s11708-017-0447-9

摘要: The oil-return system plays an important role in the variable refrigerant flow (VRF) systems because it ensures the reliable operation of the VRF systems. The oil-gas separator is the most essential component of the oil-return system, and the separation efficiency of the separator directly influences the performance of the VRF systems. Therefore, in this paper, a test rig was built to measure the oil discharge ratio of the compressor and the separation efficiency of the oil-gas separator. A sound velocity transducer was used to measure the oil mass concentration instantaneously, because the sound velocity was changed with the mass ratio of oil to refrigerant. The separation efficiency of the separator could be obtained by comparing the mass fraction of oil to refrigerant before and after the separator was connected to the system.

关键词: variable refrigerant flow system     oil-gas separator     separation efficiency    

Modeling the gas flow in a cyclone separator at different temperature and pressure

Gujun WAN, Guogang SUN, Cuizhi GAO, Ruiqian DONG, Ying ZHENG, Mingxian SHI

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 498-505 doi: 10.1007/s11705-010-0502-0

摘要: The gas flow field in a cyclone separator, operated within a temperature range of 293 K – 1373 K and a pressure range of 0.1 – 6.5 MPa, has been simulated using a modified Reynolds-stress model (RSM) on commercial software platform FLUENT 6.1. The computational results show that the temperature and pressure significantly influence the gas velocity vectors, especially on their tangential component, in the cyclone. The tangential velocity decreases with an increase in temperature and increases with an increase in pressure. This tendency of the decrease or increase, however, reduces gradually when the temperature is above 1000 K or the pressure goes beyond 1.0 MPa. The temperature and pressure have a relatively weak influence on the axial velocity profiles. The outer downward flow rate increases with a temperature increase, whereas it decreases with a pressure increase. The centripetal radial velocity is strong in the region of 0 – 0.25 below the vortex finder entrance, which is named as a short-cut flow zone in this study. Based on the simulation results, a set of correlations was developed to calculate the combined effects of temperature and pressure on the tangential velocity, the downward flow rate in the cyclone and the centripetal radial velocity in the short-cut flow region underneath the vortex finder.

关键词: cyclone separator     high temperature     high pressure     flow field     numerical simulation    

Aggravation of membrane fouling and methane leakage by a three-phase separator in an external anaerobic

Chao Pang, Chunhua He, Zhenhu Hu, Shoujun Yuan, Wei Wang

《环境科学与工程前沿(英文)》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1131-6

摘要:

The existence of three-phase separator did not affect COD removal in the EAnCMBR.

The existence of three-phase separator aggravated methane leakage of EAnCMBR.

The existence of three-phase separator aggravated membrane fouling rate of EAnCMBR.

Start-up of EAnCMBR equipped three-phase separator was slightly delayed.

关键词: Anaerobic membrane bioreactor     Three-phase separator     Membrane fouling     Methane leakage     Sludge property    

Gas-solids separation model of a novel FCC riser terminator device: super short quick separator (SSQS

LU Chunxi, LI Ruxin, SHI Mingxian, LIU Xiancheng

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 462-467 doi: 10.1007/s11705-008-0068-2

摘要: The gas flow field and the separation efficiency of a novel fluid catalytic cracking (FCC) riser terminal device, named as Super Short Quick Separator (SSQS), were studied. On the basis of above investigations, a section-lateral-mixing separation model was proposed, which included both the effect of inertia and structure of gas outlet on particles capture. After final modification, the results predicted with this model could be in good agreement with the cold experimental data. According to this model, the separation efficiency of SSQS is mainly influenced by the difference between the arc radius and the center pipe radius as well as the magnitude of particle tangential velocity.

关键词: catalytic cracking     separation efficiency     tangential velocity     agreement     magnitude    

Liquid metal material genome: Initiation of a new research track towards discovery of advanced energy

Lei WANG, Jing LIU

《能源前沿(英文)》 2013年 第7卷 第3期   页码 317-332 doi: 10.1007/s11708-013-0271-9

摘要: As the basis of modern industry, the roles materials play are becoming increasingly vital in this day and age. With many superior physical properties over conventional fluids, the low melting point liquid metal material, especially room-temperature liquid metal, is recently found to be uniquely useful in a wide variety of emerging areas from energy, electronics to medical sciences. However, with the coming enormous utilization of such materials, serious issues also arise which urgently need to be addressed. A biggest concern to impede the large scale application of room-temperature liquid metal technologies is that there is currently a strong shortage of the materials and species available to meet the tough requirements such as cost, melting point, electrical and thermal conductivity, etc. Inspired by the Material Genome Initiative as issued in 2011 by the United States of America, a more specific and focused project initiative was proposed in this paper—the liquid metal material genome aimed to discover advanced new functional alloys with low melting point so as to fulfill various increasing needs. The basic schemes and road map for this new research program, which is expected to have a worldwide significance, were outlined. The theoretical strategies and experimental methods in the research and development of liquid metal material genome were introduced. Particularly, the calculation of phase diagram (CALPHAD) approach as a highly effective way for material design was discussed. Further, the first-principles (FP) calculation was suggested to combine with the statistical thermodynamics to calculate the thermodynamic functions so as to enrich the CALPHAD database of liquid metals. When the experimental data are too scarce to perform a regular treatment, the combination of FP calculation, cluster variation method (CVM) or molecular dynamics (MD), and CALPHAD, referred to as the mixed FP-CVM-CALPHAD method can be a promising way to solve the problem. Except for the theoretical strategies, several parallel processing experimental methods were also analyzed, which can help improve the efficiency of finding new liquid metal materials and reducing the cost. The liquid metal material genome proposal as initiated in this paper will accelerate the process of finding and utilization of new functional materials.

关键词: liquid metal material genome     energy material     material discovery     advanced material     room-temperature liquid alloy     thermodynamics     phase diagram    

Robust topology optimization of multi-material lattice structures under material and load uncertainties

Yu-Chin CHAN, Kohei SHINTANI, Wei CHEN

《机械工程前沿(英文)》 2019年 第14卷 第2期   页码 141-152 doi: 10.1007/s11465-019-0531-4

摘要: Enabled by advancements in multi-material additive manufacturing, lightweight lattice structures consisting of networks of periodic unit cells have gained popularity due to their extraordinary performance and wide array of functions. This work proposes a density-based robust topology optimization method for meso- or macro-scale multi-material lattice structures under any combination of material and load uncertainties. The method utilizes a new generalized material interpolation scheme for an arbitrary number of materials, and employs univariate dimension reduction and Gauss-type quadrature to quantify and propagate uncertainty. By formulating the objective function as a weighted sum of the mean and standard deviation of compliance, the tradeoff between optimality and robustness can be studied and controlled. Examples of a cantilever beam lattice structure under various material and load uncertainty cases exhibit the efficiency and flexibility of the approach. The accuracy of univariate dimension reduction is validated by comparing the results to the Monte Carlo approach.

关键词: robust topology optimization     lattice structures     multi-material     material uncertainty     load uncertainty     univariate dimension reduction    

工程材料研究中科学问题的思考

于翘

《中国工程科学》 1999年 第1卷 第3期   页码 1-4

摘要:

在不少场合下,航天用工程材料处在极端条件下工作,这就对材料提出许多特殊的要求,虽然国内外有一定的研究积累,但对更精确的模型和符合特定材料的损伤的状态方程,有待深一步研究。如高级弹头再入时气动加热和粒子云侵蚀以及两者耦合效应引起弹头防护材料增大后退量的问题;空中垃圾和微流星的高速碰撞对航天器的威胁;特别是核爆和激光武器对材料的损伤和破坏,实质上是辐射引起的热击波层裂破坏,这些都属于超高速碰撞对材料的响应问题。天线罩材料、吸波材料、红外隐身材料、电磁屏蔽材料都是具有不同波长电磁波的电磁功能材料,它们对固体介质的穿透、吸收、反射等会产生响应,不同的电磁功能材料,其宏观性能的物理参量不同,但有几个参量是通用的,如介电常数、磁导率和损耗角正切,搞清这些参量与材料微观结构的关系,可以为材料设计和材料创新提供科学依据。

关键词: 天线罩材料     吸波材料     红外隐身材料     电磁兼容材料    

A novel approach to minimizing material loss for computer numerical control flank-regrinding of worn

《机械工程前沿(英文)》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0757-z

摘要: Flanks of end mills are prone to wear in a long machining process. Regrinding is widely used in workshops to restore the flank to an original-like state. However, the traditional method involves material waste by trial and error and dramatically decreases the potential regrinding. Moreover, over-cut would happen to the flutes of worn cutters in the regrinding processes because of improper wheel path. This study presented a new approach to planning the wheel path for regrinding worn end mills to minimize material loss and recover the over-cut. In planning, a scaling method was developed to determine the maximum size of the new cutter according to the similarity of cutter shapes before and after regrinding. Then, the wheel path is first generated by envelope theory to regrind the worn area with a four-axis computer numerical control grinder according to the new size of cutters. Moreover, a second regrinding strategy is applied to recover the flute shape over-cut in the first grinding. Finally, the proposed method is verified by an experiment. Results showed that the proposed approach could save 25% of cutter material compared with the traditional method and ensure at least three regrinding times. This work effectively provides a general regrinding solution for the worn flank with maximum material-saving and regrinding period.

关键词: flank-regrinding     worn end mill     wheel position and orientation     material loss     over-cut    

A MATLAB code for the material-field series-expansion topology optimization method

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 607-622 doi: 10.1007/s11465-021-0637-3

摘要: This paper presents a MATLAB implementation of the material-field series-expansion (MFSE) topo-logy optimization method. The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology. With the series-expansion method for bounded fields, this material field is described with the characteristic base functions and the corresponding coefficients. Compared with the conventional density-based method, the MFSE method decouples the topological description and the finite element discretization, and greatly reduces the number of design variables after dimensionality reduction. Other features of this method include inherent control on structural topological complexity, crisp structural boundary description, mesh independence, and being free from the checkerboard pattern. With the focus on the implementation of the MFSE method, the present MATLAB code uses the maximum stiffness optimization problems solved with a gradient-based optimizer as examples. The MATLAB code consists of three parts, namely, the main program and two subroutines (one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer). The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail. The code is intended for researchers who are interested in this method and want to get started with it quickly. It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method.

关键词: MATLAB implementation     topology optimization     material-field series-expansion method     bounded material field     dimensionality reduction    

Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

《能源前沿(英文)》 2011年 第5卷 第4期   页码 386-397 doi: 10.1007/s11708-011-0156-8

摘要: By performing gas flow field numerical simulations for several inlet Reynolds numbers (from 2 × 10 to 9 × 10 ) and byflow ratios (from 10% to 20%), the present study has proposed to improve the flow passage of an inlet particle separator. An adjacent objective of the study is to lower pressure losses of the inlet particle separator (IPS). No particle has been included in the gas flow for a -epsilon turbulence model. The velocity distribution in different sections and the pressure coefficient along the duct have been analyzed, which indicates that there exist important low-velocity regions and vortices in the separation area. Therefore, the profile of streamlines along the original passage has been considered. This profile illustrated a vacuum region in the same area. All investigations suggest that the separation area is the most critical one for fulfilling the objective on pressure losses limitation. Then the flow passage improvement method has focused on the separation area. An improved shape has been designed in order to suit smoothly to the streamlines in this region. Similar numerical studies as those for the original shape have been conducted on this improved shape, confirming some considerable enhancements compared with the original shape. The significant vortices which appear in the original shape reduce in amount and size. Besides, pressure losses are greatly decreased in both outlets (up to 30% for high Reynolds number) and the flow is uniform at the main outlet. Subsequent engineering surveys could rely on expressions obtained for in both outlets which extend the pressure losses for a wide range of inlet Reynolds numbers. As a result, the numerical calculations demonstrate that the flow passage improvement method applied in this study has succeeded in designing a shape which enhances the flow behavior.

关键词: streamlines     pressure losses     flow passage improvement     inlet particle separator (IPS)    

A multiscale material model for heterogeneous liquid droplets in solid soft composites

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1292-1299 doi: 10.1007/s11709-021-0771-3

摘要: Liquid droplets in solid soft composites have been attracting increasing attention in biological applications. In contrary with conventional composites, which are made of solid elastic inclusions, available material models for composites including liquid droplets are for highly idealized configurations and do not include all material real parameters. They are also all deterministic and do not address the uncertainties arising from droplet radius, volume fraction, dispersion and agglomeration. This research revisits the available models for liquid droplets in solid soft composites and presents a multiscale computational material model to determine their elastic moduli, considering nearly all relevant uncertainties and heterogeneities at different length scales. The effects of surface tension at droplets interface, their volume fraction, size, size polydispersity and agglomeration on elastic modulus, are considered. Different micromechanical material models are incorporated into the presented computational framework. The results clearly indicate both softening and stiffening effects of liquid droplets and show that the model can precisely predict the effective properties of liquid droplets in solid soft composites.

关键词: liquid in solid     soft composite     computational modeling     multiscale model     heterogeneity    

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

《结构与土木工程前沿(英文)》 2011年 第5卷 第1期   页码 63-70 doi: 10.1007/s11709-010-0016-3

摘要: This paper demonstrates the difficulties in determining the relevant material parameters for a valuation of the deformation behavior of the up- and downstream dam shell by means of an embankment dam of medium height. Laboratory as well as field tests on solid rock-fill material were performed before the beginning of construction. During the construction the properties of the available rock-fill changed from solid to soft materials. This gave rise to the necessity of adjusting the dam design of the downstream dam shoulder. Several times higher dam settlements as well as significant differential settlements between the up- and downstream dam shell were observed during construction and operation. Apart from this situation, the dam has been operated for nearly 20 years and the behavior of the water barrier has been very good.

关键词: embankment dam     bituminous concrete membrane     rock-fill material properties     deformation behavior    

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

Chao CHEN, Huiyang ZHANG, Shengdun ZHAO, Xiaoqiang REN

《机械工程前沿(英文)》 2021年 第16卷 第2期   页码 410-419 doi: 10.1007/s11465-020-0618-y

摘要: The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, the effects of sheet thickness and material on the mechanical properties of the clinched joint were studied. Al1060 and Al2024 sheets with 2 mm thickness were employed to develop the clinched joint by using different material configurations, and Al1060 sheets with 2.5- and 1.5-mm thicknesses were used to produce the clinched joint by using different thickness configurations. The clinched joints using various sheet configurations were sectioned, and dimensional analysis was conducted. Cross-tensile and shearing tests were carried out to analyze the mechanical properties of the clinched joint, including tensile strength, shearing strength, and absorbed energy. In addition, the failure modes of the clinched joints were discussed. Results indicated that the clinched joint with a stiff top sheet had increased static strength regardless of the test type. The clinched joint with a thick top sheet demonstrated lower static strength than the joint with a thick bottom sheet in the cross-tensile test. However, this result was reversed in the shearing tests. The flat clinching process has a great potential in joining dissimilar and various thickness materials.

关键词: clinched joint     flat clinching process     thickness configuration     material configuration     mechanical property    

标题 作者 时间 类型 操作

Using crosslinked polyvinyl alcohol polymer membrane as a separator in the microbial fuel cell

Yanping HOU, Kaiming LI, Haiping LUO, Guangli LIU, Renduo ZHANG, Bangyu QIN, Shanshan CHEN

期刊论文

Regulating surface chemistry of separator with LiF for advanced Li-S batteries

期刊论文

Experimental investigation on oil-gas separator of air-conditioning systems

Dianbo XIN,Shuliang HUANG,Song YIN,Yuping DENG,Wenqiang ZHANG

期刊论文

Modeling the gas flow in a cyclone separator at different temperature and pressure

Gujun WAN, Guogang SUN, Cuizhi GAO, Ruiqian DONG, Ying ZHENG, Mingxian SHI

期刊论文

Aggravation of membrane fouling and methane leakage by a three-phase separator in an external anaerobic

Chao Pang, Chunhua He, Zhenhu Hu, Shoujun Yuan, Wei Wang

期刊论文

Gas-solids separation model of a novel FCC riser terminator device: super short quick separator (SSQS

LU Chunxi, LI Ruxin, SHI Mingxian, LIU Xiancheng

期刊论文

Liquid metal material genome: Initiation of a new research track towards discovery of advanced energy

Lei WANG, Jing LIU

期刊论文

Robust topology optimization of multi-material lattice structures under material and load uncertainties

Yu-Chin CHAN, Kohei SHINTANI, Wei CHEN

期刊论文

工程材料研究中科学问题的思考

于翘

期刊论文

A novel approach to minimizing material loss for computer numerical control flank-regrinding of worn

期刊论文

A MATLAB code for the material-field series-expansion topology optimization method

期刊论文

Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

期刊论文

A multiscale material model for heterogeneous liquid droplets in solid soft composites

期刊论文

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

Peter TSCHERNUTTER

期刊论文

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

Chao CHEN, Huiyang ZHANG, Shengdun ZHAO, Xiaoqiang REN

期刊论文