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Assessment of glass fiber-reinforced polyester pipe powder in soil improvement

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 742-753 doi: 10.1007/s11709-021-0732-x

摘要: This study investigates the use of glass fiber-reinforced polyester (GRP) pipe powder (PP) for improving the bearing capacity of sandy soils. After a series of direct share tests, the optimum PP addition for improving the bearing capacity of soils was found to be 12%. Then, using the optimum PP addition, the bearing capacity of the soil was estimated through a series of loading tests on a shallow foundation model placed in a test box. The bearing capacity of sandy soil was improved by up to 30.7%. The ratio of the depth of the PP-reinforced soil to the diameter of the foundation model (H/D) of 1.25 could sufficiently strengthen sandy soil when the optimum PP ratio was used. Microstructural analyses showed that the increase in the bearing capacity can be attributed to the chopped fibers in the PP and their multiaxial distribution in the soil. Besides improving the engineering properties of soils, using PP as an additive in soils would reduce the accumulation of the industrial waste, thus providing a twofold benefit.

关键词: shallow foundation     sandy soil     bearing capacity     soil improvement     pipe powder    

Mechanical properties of steel, glass, and hybrid fiber reinforced reactive powder concrete

Atheer H.M. ALGBURI, M. Neaz SHEIKH, Muhammad N.S. HADI

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 998-1006 doi: 10.1007/s11709-019-0533-7

摘要: This study examines the properties of fiber-reinforced reactive powder concrete (FR-RPC). Steel fibers, glass fibers, and steel-glass hybrid fibers were used to prepare the FR-RPC. The non-fibrous reactive powder concrete (NF-RPC) was prepared as a reference mix. The proportion of fibers by volume for all FR-RPC mixes was 1.5%. Steel fibers of 13 mm length and 0.2 mm diameter were used to prepare the steel fiber-reinforced RPC (SFR-RPC). Glass fibers of 13 mm length and 1.3 mm diameter were used to prepare the glass fiber-reinforced RPC (GFR-RPC). The hybrid fiber-reinforced RPC (HFR-RPC) was prepared by mixing 0.9% steel fibers and 0.6% glass fibers. Compressive strength, axial load-axial deformation behavior, modulus of elasticity, indirect tensile strength, and shear strength of the RPC mixes were investigated. The results showed that SFR-RPC achieved higher compressive strength, indirect tensile strength and shear strength than NF-RPC, GFR-RPC, and HFR-RPC. Although the compressive strengths of GFR-RPC and HFR-RPC were slightly lower than the compressive strength of NF-RPC, the shear strengths of GFR-RPC and HFR-RPC were higher than that of NF-RPC.

关键词: reactive powder concrete     steel fiber     glass fiber     hybrid fiber    

An investigation into the properties of ternary and binary cement pastes containing glass powder

Marcelo Frota BAZHUNI, Mahsa KAMALI, Ali GHAHREMANINEZHAD

《结构与土木工程前沿(英文)》 2019年 第13卷 第3期   页码 741-750 doi: 10.1007/s11709-018-0511-5

摘要: The properties of binary and ternary cement pastes containing glass powder (GP) were examined. Hydration at early age was evaluated using semi-adiabatic calorimetry and at late ages using non-evaporable water content and thermogravimetric analysis. The transport characteristic was assessed by measuring electrical resistivity. The binary paste with slag showed the highest hydration activity compared to the binary pastes with GP and fly ash (FA). The results indicated that the pozzolanic behavior of the binary paste with GP was less than that of the binary pastes with slag or FA at late ages. An increase in the electrical resistivity and compressive strength of the binary paste with GP compared to other modified pastes at late ages was observed. It was shown that GP tends to increase the drying shrinkage of the pastes. Ternary pastes containing GP did not exhibit synergistic enhancements compared to the respective binary pastes.

关键词: cement paste     glass powder     pozzolanic reaction     supplementary cementitious material    

Orientation effect of electropolishing characteristics of 316L stainless steel fabricated by laser powder

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 580-592 doi: 10.1007/s11465-021-0633-7

摘要: 3D metal printing process has attracted increasing attention in recent years due to advantages, such as flexibility and rapid prototyping. This study aims to investigate the orientation effect of electropolishing characteristics on different surfaces of 316L stainless steel fabricated by laser powder bed fusion (L-PBF), considering that the rough surface of 3D printed parts is a key factor limiting its applications in the industry. The electropolishing characteristics on the different surfaces corresponding to the building orientation in selective laser melting are studied. Experimental results show that electrolyte temperature has critical importance on the electropolishing, especially for the vertical direction to the layering plane. The finish of electropolished surfaces is affected by the defects generated during L-PBF process. Thus, the electropolished vertical surface has higher surface roughness Sa than the horizontal surface. The X-ray photoelectron spectroscopy spectra show that the electropolished horizontal surface has higher Cr/Fe element ratio than the vertical surface. The electropolished horizontal surface presents higher corrosion resistance than the vertical surface by measuring the anodic polarization curves and fitting the equivalent circuit of experimental electrochemical impedance spectroscopy.

关键词: electropolishing     laser powder bed fusion     316L stainless steel     corrosion resistance     microstructure    

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0724-0

摘要: The internal structures of metallic products are important in realizing functional applications. Considering the manufacturing of inner structures, laser-based powder bed fusion (L-PBF) is an attractive approach because its layering principle enables the fabrication of parts with customized interior structures. However, the inferior surface quality of L-PBF components hinders its productization progress seriously. In this article, process, basic forms, and applications relevant to L-PBF internal structures are reviewed comprehensively. The causes of poor surface quality and differences in the microstructure and property of the surface features of L-PBF inner structures are presented to provide a perspective of their surface characteristics. Various polishing technologies for L-PBF components with inner structures are presented, whereas their strengths and weaknesses are summarized along with a discussion on the challenges and prospects for improving the interior surface quality of L-PBF parts.

关键词: laser-based powder bed fusion     polishing     internal structures     surface quality     surface features     post process     additive manufacturing    

Precision glass molding: Toward an optimal fabrication of optical lenses

Liangchi ZHANG,Weidong LIU

《机械工程前沿(英文)》 2017年 第12卷 第1期   页码 3-17 doi: 10.1007/s11465-017-0408-3

摘要:

It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 105 to 1012 Pa·s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

关键词: precision glass molding     optical lens     constitutive modeling     optimization     manufacturing chain     Industry 4.0    

Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

《结构与土木工程前沿(英文)》 2010年 第4卷 第3期   页码 376-382 doi: 10.1007/s11709-010-0086-2

摘要: Pre-tensioned high strength trusses using alloy steel bar are widely used as glass wall supporting systems because of the high degree of transparency. The breakage of glass panes in this type of system occurs occasionally, likely to be due to error in design and analysis in addition to other factors like glass impurity and stress concentration around opening in a spider system. Most design does not consider the flexibility of supports from finite stiffness of supporting steel or reinforced concrete beams. The resistance of lateral wind pressure of the system makes use of high tension force coupled with the large deflection effect, both of which are affected by many parameters not generally considered in conventional structures. In the design, one must therefore give a careful consideration on various effects, such as support settlement due to live loads and material creep, temperature change, pre-tension force, and wind pressure. It is not uncommon to see many similar glass wall systems fail in the wind load test chambers under a design wind speed. This paper presents a rigorous analysis and design of this type of structural systems used in a project in Hong Kong, China. The stability function with initial curvature is used in place of the cubic function, which is only accurate for linear analysis. The considerations and analysis techniques are believed to be of value to engineers involved in the design of the structural systems behaving nonlinearly.

关键词: tension system     glass wall     nonlinear analysis     pre-tensioning     second-order analysis    

Experimental study and assessment of thermal energy storage mortar with paraffin/recycled brick powder

Luchen HAO; Jianzhuang XIAO; Wanzhi CAO; Jingting SUN

《结构与土木工程前沿(英文)》 2022年 第16卷 第10期   页码 1301-1314 doi: 10.1007/s11709-022-0883-4

摘要: Thermal energy storage recycled powder mortar (TESRM) was developed in this study by incorporating paraffin/recycled brick powder (paraffin/BP) composite phase change materials (PCM). Fourier transform infrared and thermogravimetric analysis results showed that paraffin/BP composite PCM had good chemical and thermal stability. The onset melting temperature and latent heat of the composite PCM were 46.49 °C and 30.1 J·g−1. The fresh mortar properties and hardened properties were also investigated in this study. Paraffin/BP composite PCM with replacement ratio of 0%, 10%, 20%, and 30% by weight of cement were studied. The results showed that the static and dynamic yield stresses of TESRM were 699.4% and 172.9% higher than those of normal mortar, respectively. The addition of paraffin/BP composite PCM had a positive impact on the mechanical properties of mortar at later ages, and could also reduce the dry shrinkage of mortar. The dry shrinkage of TESRM had a maximum reduction about 26.15% at 120 d. The thermal properties of TESRM were better than those of normal mortar. The thermal conductivity of TESRM was 36.3% less than that of normal mortar and the heating test results showed that TESRM had good thermal energy storage performance.

关键词: recycled powder mortar     recycled brick powder     thermal energy storage     paraffin     phase change material    

Progress of three-dimensional macroporous bioactive glass for bone regeneration

Lijun JI, Yunfeng SI, Ailing LI, Wenjun WANG, Dong QIU, Aiping ZHU

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 470-483 doi: 10.1007/s11705-012-1217-1

摘要: Bioactive glasses (BGs) are ideal materials for macroporous scaffolds due to their excellent osteoconductive, osteoinductive, biocompatible and biodegradable properties, and their high bone bonding rates. Macroporous scaffolds made from BGs are in high demand for bone regeneration because they can stimulate vascularized bone ingrowth and they enhance bonding between scaffolds and surrounding tissues. Engineering BG/biopolymers (BP) composites or hybrids may be a good way to prepare macroporous scaffolds with excellent properties. This paper summarizes the progress in the past few years in preparing three-dimensional macroporous BG and BG/BP scaffolds for bone regeneration. Since the brittleness of BGs is a major problem in developing macroporous scaffolds and this limits their use in load bearing applications, the mechanical properties of macroporous scaffolds are particularly emphasized in this review.

关键词: bioactive glass     biopolymer     bone regeneration     macroporous scaffolds     tissue engineering    

Aging properties and aging mechanism of activated waste rubber powder modified asphalt binder based on

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 625-636 doi: 10.1007/s11709-023-0938-1

摘要: The research and development of high-performance pavement materials has been intensified owing to the demand for long-life pavements. This study is performed to develop a novel pavement material using waste rubber powder, waste lubricating by-product (LBP), and asphalt. Subsequently, the aging properties and aging mechanism of activated waste rubber powder modified asphalt (ARMA) are investigated based on its rheological properties and micro-characterization. The rheological results show that, compared with waste rubber powder modified asphalt (RMA), ARMA offers a higher aging resistance and a longer fatigue life. A comparison and analysis of the rheological aging parameters of ARMA and RMA show that LBP activation diminishes the aging sensitivity of ARMA. The micro-characterization result shows that the aging of ARMA may be caused by the fact that LBP-activated waste rubber powder is more reactive and can form a dense colloidal structure with asphalt. Therefore, the evaporation loss of asphalt light components by heat and the damage to the colloidal structure by oxygen during the aging process are impeded, and the thermal-oxidative aging resistance of ARMA is improved.

关键词: rubber powder modified asphalt     aging     mechanism     rheological     characterization    

Influence of damages on static behavior of single-layer cable net supported glass curtain wall: full-scale

Gang SHI, Yongjiu SHI, Yuanqing WANG, Yongzhi ZUO, Xiaohao SHI, Zaoyang GUO,

《结构与土木工程前沿(英文)》 2010年 第4卷 第3期   页码 383-395 doi: 10.1007/s11709-010-0074-6

摘要: The single-layer cable net supported glass curtain wall has been applied in many building structures all over the world. In service, it will inevitably be subject to various damages. To study the influence of such damages on the static behavior of the single-layer cable net supported glass curtain wall, a full-scale model with the outside outline size of 4.85 m × 4.85 m and 4 × 4 grids is designed and tested. Two kinds of damages that are the cable prestress loss and cable anchorage end failure are led into the structure model during the test, and their influence has been investigated. The stiffness contribution of glass panels to the single-layer cable net supported glass curtain wall structure with or without damages and its change have been tested and analyzed. The results show that the maximum change rate of nodal deflection is 13.78% for the damage of cable prestress loss, while the change rate of nodal deflection is between 7% and 22% for the damage of cable anchorage end failure. The influence degree of the damages depends on the ratio of the structure initial stress stiffness change caused by damages to the total stiffness of the structure. The stiffness contribution of glass panels increases with the load increase. Under the same loading condition, the stiffness contribution of glass panels to the damaged structure is greater than that to the intact structure. The stiffness contribution of glass panels reduces the effect of the damages on the structural displacement and the cable tension force, but the glass panel could break if its stiffness contribution is too large.

关键词: single-layer plane cable net supported glass curtain wall     damage     cable prestress loss     cable anchorage end failure     stiffness contribution of glass panels    

of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis via laser powder

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0727-x

摘要: High-entropy alloys (HEAs) are considered alternatives to traditional structural materials because of their superior mechanical, physical, and chemical properties. However, alloy composition combinations are too numerous to explore. Finding a rapid synthesis method to accelerate the development of HEA bulks is imperative. Existing in situ synthesis methods based on additive manufacturing are insufficient for efficiently controlling the uniformity and accuracy of components. In this work, laser powder bed fusion (L-PBF) is adopted for the in situ synthesis of equiatomic CoCrFeMnNi HEA from elemental powder mixtures. High composition accuracy is achieved in parallel with ensuring internal density. The L-PBF-based process parameters are optimized; and two different methods, namely, a multi-melting process and homogenization heat treatment, are adopted to address the problem of incompletely melted Cr particles in the single-melted samples. X-ray diffraction indicates that HEA microstructure can be obtained from elemental powders via L-PBF. In the triple-melted samples, a strong crystallographic texture can be observed through electron backscatter diffraction, with a maximum polar density of 9.92 and a high ultimate tensile strength (UTS) of (735.3 ± 14.1) MPa. The homogenization heat-treated samples appear more like coarse equiaxed grains, with a UTS of (650.8 ± 16.1) MPa and an elongation of (40.2% ± 1.3%). Cellular substructures are also observed in the triple-melted samples, but not in the homogenization heat-treated samples. The differences in mechanical properties primarily originate from the changes in strengthening mechanism. The even and flat fractographic morphologies of the homogenization heat-treated samples represent a more uniform internal microstructure that is different from the complex morphologies of the triple-melted samples. Relative to the multi-melted samples, the homogenization heat-treated samples exhibit better processability, with a smaller composition deviation, i.e., ≤ 0.32 at.%. The two methods presented in this study are expected to have considerable potential for developing HEAs with high composition accuracy and composition flexibility.

关键词: laser powder bed fusion (L-PBF)     in situ alloying     high-entropy alloys     heat treatment     rapid synthesis    

Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

《结构与土木工程前沿(英文)》 2013年 第7卷 第4期   页码 419-428 doi: 10.1007/s11709-013-0224-8

摘要: With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials. Due to differences in mixture design, placement and consolidation techniques, the strength and durability of Self Compacting Concrete (SCC) may be different than those of conventional concrete. Therefore, replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes. The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties. In present study, fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0% to 50%. Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume. Nevertheless, compressive, flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased. The strength reduction of concrete in different glass replacement ratios is not remarkable, thus it can be produced SCC with waste glass as fine aggregate in a standard manner.

关键词: Self Compacting Concrete (SCC)     recycle glass     fine aggregate     fresh and hardened properties    

Preparation of adsorptive nanoporous membrane using powder activated carbon: Isotherm and thermodynamic

Majid Peyravi

《化学科学与工程前沿(英文)》 2020年 第14卷 第4期   页码 673-687 doi: 10.1007/s11705-019-1800-9

摘要: Adsorptive polyethesulfone (PES) membranes were prepared by intercalation of powder activated carbon (PAC) with and without functionalization. Accordingly, PAC was aminated with 1,5-diamino-2-methylpentane, and the physicochemical properties of the functionalized PAC were analyzed. Intercalation of PAC within the PES scaffold changed the porosity and mean pore size of the aminated membrane (AC-NH ) from 52.6% to 92.5% and from 22.6 nm to 3.5 nm, respectively. The effect of temperature on the performance of the modified membranes was monitored by the flux and chemical oxygen demand (COD) removal of leachate. At ambient temperature, the COD removal of the neat, AC-containing, and AC-NH membranes was 47%, 52%, and 58.5%, respectively. A similar increment was obtained for the membrane flux, which was due to the synergistic effect of the high porosity and large number of hydrophilic functional groups. The experimental leachate adsorption data were analyzed by Langmuir, Freundlich, and Dubinin- Radushkevich isotherm models. For all membranes, the significant thermodynamic parameters ( , , and ) were calculated and compared. The isosteric heat of adsorption was lower than 80 kJ∙mol , indicating that the interaction between the membranes and the leachate is mainly physical, involving weak van der Waals forces.

关键词: amine functionality     nanoporous membrane     adsorption isotherm     thermodynamic parameters     landfill leachate    

Global warming potential associated with Irish milk powder production

William Finnegan, Jamie Goggins, Aksana Chyzheuskaya, Xinmin Zhan

《环境科学与工程前沿(英文)》 2017年 第11卷 第3期 doi: 10.1007/s11783-017-0949-z

摘要: Climate change is an ever growing issue and a major concern worldwide. Both producers and processors need to address the issue now by reducing their carbon footprint. Additionally, if Ireland is to meet their climate and energy targets, as outlined in Food Harvest 2020, which outlines a range of objectives for the Irish agricultural sector, the efficient use of resources and fuels within the industry will need to be increased. In Ireland, agriculture accounts for 29.2% of the total greenhouse gas emissions (58.5 million tonnes CO eq). Therefore, in this paper, a single agri-food product, milk powder, is examined in order to estimate the global warming potential (GWP) associated with its manufacture using life cycle assessment. A cradle-to-processing factory gate analysis, which includes raw milk production, raw milk transportation to the processing factory, its processing into each product and product packaging, is assessed in this study using data collected circa 2013. The factories surveyed processed approximately 24% of the total raw milk processed in the Republic of Ireland in 2013, which was 5.83 billion liters. The average total GWP associated with the manufacture of milk powder is 9.731 kg CO eq·kg milk powder, which has a standard deviation of 2.26 kg CO eq·kg milk powder, for the life cycle stages analyzed in this study. The most significant contributor to GWP is raw milk production (84%), followed by dairy processing (14%), with the remainder of the life cycle stages contributing approximately 2%.

关键词: Dairy     Global warming potential     Ireland     Life cycle assessment     Milk powder     Milk production    

标题 作者 时间 类型 操作

Assessment of glass fiber-reinforced polyester pipe powder in soil improvement

期刊论文

Mechanical properties of steel, glass, and hybrid fiber reinforced reactive powder concrete

Atheer H.M. ALGBURI, M. Neaz SHEIKH, Muhammad N.S. HADI

期刊论文

An investigation into the properties of ternary and binary cement pastes containing glass powder

Marcelo Frota BAZHUNI, Mahsa KAMALI, Ali GHAHREMANINEZHAD

期刊论文

Orientation effect of electropolishing characteristics of 316L stainless steel fabricated by laser powder

期刊论文

Advances in polishing of internal structures on parts made by laser-based powder bed fusion

期刊论文

Precision glass molding: Toward an optimal fabrication of optical lenses

Liangchi ZHANG,Weidong LIU

期刊论文

Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

期刊论文

Experimental study and assessment of thermal energy storage mortar with paraffin/recycled brick powder

Luchen HAO; Jianzhuang XIAO; Wanzhi CAO; Jingting SUN

期刊论文

Progress of three-dimensional macroporous bioactive glass for bone regeneration

Lijun JI, Yunfeng SI, Ailing LI, Wenjun WANG, Dong QIU, Aiping ZHU

期刊论文

Aging properties and aging mechanism of activated waste rubber powder modified asphalt binder based on

期刊论文

Influence of damages on static behavior of single-layer cable net supported glass curtain wall: full-scale

Gang SHI, Yongjiu SHI, Yuanqing WANG, Yongzhi ZUO, Xiaohao SHI, Zaoyang GUO,

期刊论文

of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis via laser powder

期刊论文

Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

期刊论文

Preparation of adsorptive nanoporous membrane using powder activated carbon: Isotherm and thermodynamic

Majid Peyravi

期刊论文

Global warming potential associated with Irish milk powder production

William Finnegan, Jamie Goggins, Aksana Chyzheuskaya, Xinmin Zhan

期刊论文