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A miniature triaxial apparatus for investigating the micromechanics of granular soils with

Zhuang CHENG, Jianfeng WANG, Matthew Richard COOP, Guanlin YE

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 357-373 doi: 10.1007/s11709-019-0599-2

摘要: The development of a miniature triaxial apparatus is presented. In conjunction with an X-ray micro-tomography (termed as X-ray μCT hereafter) facility and advanced image processing techniques, this apparatus can be used for investigation of the micro-scale mechanical behavior of granular soils under shear. The apparatus allows for triaxial testing of a miniature dry sample with a size of (diameter height). triaxial testing of a 0.4–0.8 mm Leighton Buzzard sand (LBS) under a constant confining pressure of 500 kPa is presented. The evolutions of local porosities (i.e., the porosities of regions associated with individual particles), particle kinematics (i.e., particle translation and particle rotation) of the sample during the shear are quantitatively studied using image processing and analysis techniques. Meanwhile, a novel method is presented to quantify the volumetric strain distribution of the sample based on the results of local porosities and particle tracking. It is found that the sample, with nearly homogenous initial local porosities, starts to exhibit obvious inhomogeneity of local porosities and localization of particle kinematics and volumetric strain around the peak of deviatoric stress. In the post-peak shear stage, large local porosities and volumetric dilation mainly occur in a localized band. The developed triaxial apparatus, in its combined use of X-ray μCT imaging techniques, is a powerful tool to investigate the micro-scale mechanical behavior of granular soils.

关键词: triaxial apparatus     X-ray μCT     in situ test     micro-scale mechanical behavior     granular soils    

Strengthening of polysulfone membranes using hybrid mixtures of micro- and nano-scale modifiers

Peyman P. Selakjani, Majid Peyravi, Mohsen Jahanshahi, Hamzeh Hoseinpour, Ali S. Rad, Soodabeh Khalili

《化学科学与工程前沿(英文)》 2018年 第12卷 第1期   页码 174-183 doi: 10.1007/s11705-017-1670-y

摘要: Polysulfone (PSf) membranes were modified by either a new organic modifier (sulfonated poly(ether sulfide sulfone), SPESS) or a traditional modifier (rice hulk). These membranes were further reinforced with either multi-walled carbon nanotubes (MWCNTs) or silica nanoparticles. Having a dye rejection of 98.46%, the reinforced membranes increased more than 50% in strength but no change in solution flux was observed. The morphological and roughness studies were conducted using scanning electron microscopy and atomic force microscopy. Moreover, the PSF membranes were also characterized by differential scanning calorimetry. Modifying the membranes with organic modifier or nanofiller increases the glass transition temperature ( ). The highest and strength were observed for the PSf-SPESS-MWCNT membrane. SPESS decreases surface roughness but MWCNT increases roughness on the nanoscale. All membranes show a bimodal pore size distribution, whereas the PSf-SPESS-MWCNT membrane exhibits a relatively uniform distribution of macroscopic and microscopic pores.

关键词: polysulfone membrane     mechanical properties     micro- and nano-modification     binary and ternary system     dye removal    

Achievements and trends of solid oxide fuel cells in clean energy field: a perspective review

Abdalla M. ABDALLA, Shahzad HOSSAIN, Pg MohdIskandr PETRA, Mostafa GHASEMI, Abul K. AZAD

《能源前沿(英文)》 2020年 第14卷 第2期   页码 359-382 doi: 10.1007/s11708-018-0546-2

摘要: The main concerns in the world today, especially in the energy field, are subjected to clean, efficient, and durable sources of energy. These three aspects are the main goals that scientist are paying attention to. However, the various types of energy resources include fossil and sustainable ones, but still some challenges are chasing these kinds from energy conversion, storage, and efficiency. Hence, the most reliable and considered energy resource nowadays is the utilized one which is as highly efficient, clean, and everlasting as possible. So, in this review, an attempt is made to highlight one of the promising types as a clean and efficient energy resource. Solid oxide fuel cell (SOFC) is the most efficient type of the fuel cell types involved with hydrogen and hydrocarbon-based fuels, especially when it works with combined heat and power (CHP). The importance of this type is due to its nature of work as conversion tool from chemical to electrical for generation of power without noise, pollution, and can be safely handled.

关键词: solid oxide fuel cells (SOFCs)     clean energy     design     micro-scale     nano-scale     performance    

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 396-401 doi: 10.1007/s11708-009-0049-2

摘要: Numerical simulations of flowing and boiling in micro channels are presented, including the modeling of bubble dynamics of nucleate boiling, and a description of the interface of two phases with the volume-of-fluid (VOF). The two calculated cases are compared with related experimental data in literature. Some simulated results are found corresponding well to the experimental data. The simulated results also show the details of 3-dimensional heat transfer and the flow in micro channels, which are helpful to the investigation of the mechanism of two-phase heat transfer and flow in micro channels.

关键词: volume-of-fluid (VOF)     micro channel     nucleate boiling     bubble dynamics     simulation    

Micro-spectrophotometer based on micro electro-mechanical systems technology

ZHOU Lianqun, LI Zhenggang, WU Yihui, ZHANG Ping, XUAN Ming, JIA Hongguang

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 37-43 doi: 10.1007/s11465-008-0001-x

摘要: A new mini-spectrophotometer is developed by adopting micro-silicon-slit and micro-silicon-fixer, which are based on micro electro-mechanical systems (MEMS) technology. Both the micro-silicon-slit and the micro-silicon-fixer have their own features, such as small volume and high precision, which are laid out and analyzed later. Meantime, through the analysis of the sample cell’s optical characteristics that have some impacts on the linearity of the spectrophotometer, a relationship equation, which is about the impact of the refractive index of the sample cell and the tested medium on the variety of the transmitted light intensity and the absorbency, is put forward. When the water and the air are taken as the referenced medium, the experiments demonstrate that the difference of the refractive index of the references does not influence the correlation coefficient and the slope of the absorbency-concentration curve. The final results show that the new mini-spectrophotometer with micro-silicon-slit and micro-silicon-fixer is worked out, its correlation coefficient > 0.999, and its refractive index resolving power is better than 0.01.

关键词: mini-spectrophotometer     referenced     micro-silicon-fixer     electro-mechanical     correlation coefficient    

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1047-1057 doi: 10.1007/s11709-021-0755-3

摘要: Magnesium phosphate cement (MPC) received increased attention in recent years, but MPC-based concrete is rarely reported. The micro-steel fibers (MSF) were added to MPC-based concrete to enhance its ductility due to the high brittleness in tensile and flexural strength properties of MPC. This paper investigates the effect of MSF volume fraction on the mechanical properties of a new pattern of MPC-based concrete. The temperature development curve, fluidity, cubic compressive strength, modulus of elastic, axial compressive strength, and four-point flexural strength were experimentally studied with 192 specimens, and a scanning electron microscopy (SEM) test was carried out after the specimens were failed. Based on the test results, the correlations between the cubic compressive strength and curing age, the axial and cubic compressive strength of MPC-based concrete were proposed. The results showed that with the increase of MSF volume fraction, the fluidity of fresh MPC-based concrete decreased gradually. MSF had no apparent influence on the compressive strength, while it enhanced the four-point flexural strength of MPC-based concrete. The four-point flexural strength of specimens with MSF volume fraction from 0.25% to 0.75% were 12.3%, 21.1%, 24.6% higher than that of the specimens without MSF, respectively.

关键词: magnesium phosphate cement-based concrete     micro-steel fibers     four-point flexural strength     compressive strength    

A bionic approach for the mechanical and electrical decoupling of an MEMS capacitive sensor in ultralow

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-023-0747-1

摘要: Capacitive sensors are efficient tools for biophysical force measurement, which is essential for the exploration of cellular behavior. However, attention has been rarely given on the influences of external mechanical and internal electrical interferences on capacitive sensors. In this work, a bionic swallow structure design norm was developed for mechanical decoupling, and the influences of structural parameters on mechanical behavior were fully analyzed and optimized. A bionic feather comb distribution strategy and a portable readout circuit were proposed for eliminating electrostatic interferences. Electrostatic instability was evaluated, and electrostatic decoupling performance was verified on the basis of a novel measurement method utilizing four complementary comb arrays and application-specific integrated circuit readouts. An electrostatic pulling experiment showed that the bionic swallow structure hardly moved by 0.770 nm, and the measurement error was less than 0.009% for the area-variant sensor and 1.118% for the gap-variant sensor, which can be easily compensated in readouts. The proposed sensor also exhibited high resistance against electrostatic rotation, and the resulting measurement error dropped below 0.751%. The rotation interferences were less than 0.330 nm and (1.829 × 10−7)°, which were 35 times smaller than those of the traditional differential one. Based on the proposed bionic decoupling method, the fabricated sensor exhibited overwhelming capacitive sensitivity values of 7.078 and 1.473 pF/µm for gap-variant and area-variant devices, respectively, which were the highest among the current devices. High immunity to mechanical disturbances was maintained simultaneously, i.e., less than 0.369% and 0.058% of the sensor outputs for the gap-variant and area-variant devices, respectively, indicating its great performance improvements over existing devices and feasibility in ultralow biomedical force measurement.

关键词: micro-electro-mechanical system capacitive sensor     bionics     operation instability     mechanical and electrical decoupling     biomedical force measurement    

Correction to: Effect of wood dust type on mechanical properties, wear behavior, biodegradability, and

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1071-1071 doi: 10.1007/s11709-021-0736-6

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 146-149 doi: 10.1007/s11465-013-0260-z

摘要:

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 μm . It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

关键词: Micro-Electro-Mechanical Systems (MEMS)     micro accelerometer     force-balanced micro accelerometer     frequency     error sensitivity    

A comparative study of the mechanical properties, fracture behavior, creep, and shrinkage of chemically

Mahdi AREZOUMANDI, Mark EZZELL, Jeffery S VOLZ

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 36-45 doi: 10.1007/s11709-014-0243-0

摘要: This study presents the results of an experimental investigation that compares the mechanical properties, fracture behavior, creep, and shrinkage of a chemically-based self-consolidating concrete (SCC) mix with that of a corresponding conventional concrete (CC) mix. The CC and SCC mix designs followed conventional proportioning in terms of aggregate type and content, cement content, air content, water-cementitiuos materials ( / ) ratio, and workability. Then, using only chemical admixtures, the authors converted the CC mix to an SCC mix with all of the necessary passing, filling, flowability, and stability requirements typically found in SCC. The high fluidity was achieved with a polycarboxylate-based high-range water-reducing admixture, while the enhanced stability was accomplished with an organic, polymer-based viscosity-modifying admixture. The comparison indicated that the SCC and CC mixes had virtually identical tensile splitting strengths, flexural strengths, creep, and shrinkage. However, the SCC mix showed higher compressive strengths and fracture energies than the corresponding CC mix.

关键词: admixture     conventional concrete (CC)     creep     fracture mechanic     mechanical Properties     self-consolidating concrete (SCC)     shrinkage    

Effect of wood dust type on mechanical properties, wear behavior, biodegradability, and resistance to

Sawan KUMAR, Ajitanshu VEDRTNAM, S. J. PAWAR

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1446-1462 doi: 10.1007/s11709-019-0568-9

摘要: The present work reports the inclusion of different proportions of Mango/Sheesham/Mahogany/Babool dust to polypropylene for improving mechanical, wear behavior and biodegradability of wood-plastic composite (WPC). The wood dust (10%, 15%, 20% by weight) was mixed with polypropylene granules and WPCs were prepared using an injection molding technique. The mechanical, wear, and morphological characterizations of fabricated WPCs were carried out using standard ASTM methods, pin on disk apparatus, and scanning electron microscopy (SEM), respectively. Further, the biodegradability and resistance to natural weathering of WPCs were evaluated following ASTM D5338-11 and ASTM D1435-99, respectively. The WPCs consisting of Babool and Sheesham dust were having superior mechanical properties whereas the WPCs consisting of Mango and Mahogany were more wear resistant. It was found that increasing wood powder proportion results in higher Young’s modulus, lesser wear rate, and decreased stress at break. The WPCs made of Sheesham dust were least biodegradable. It was noticed that the biodegradability corresponds with resistance to natural weathering; more biodegradable WPCs were having the lesser resistance to natural weathering.

关键词: wood-plastic composites     mechanical testing     wear     biodegradability     injection molding     weathering    

Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured

Mahdi IZADI, Khosrow BARGI

《结构与土木工程前沿(英文)》 2019年 第13卷 第5期   页码 1105-1119 doi: 10.1007/s11709-019-0539-1

摘要: The present study investigates the mechanical behavior of a new generation of buried pipelines, dubbed the textured pipeline, which is subjected to strike-slip faulting. In conventional cylindrical pipelines, the axial and bending stresses brought about in their walls as a result of fault movement, lead to local buckling, which is construed as one of the major reasons contributing to pipeline failure. The present study has assessed 3-D numerical models of two kinds of buried textured pipelines, with 6 and 12 peripheral triangular facets, subjected to a strike-slip faulting normal to the axis of the pipelines, with and without internal pressure, with the two kinds of X65 and X80 steel, and with different diameter-to-thickness ratios. The results indicate that, because of specific geometry of this pipeline shell which is characterized by having lower axial stiffness and higher bending stiffness, compared to conventional cylindrical pipeline, they are considerably resistant to local buckling. The results of this study can be conceived of as a first step toward comprehensive seismic studies on this generation of pipelines which aim at replacing the conventional cylindrical pipelines with textured ones in areas subjected to fault movement.

关键词: buried pipeline     textured pipeline     local buckling    

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 110-122 doi: 10.1007/s11709-018-0476-4

摘要: Asphalt concrete (AC) overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing pavements. The strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement material. This study was conducted to analyze the influence of anisotropy, modulus gradient properties, and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays, as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA). The mechanical behaviors of the AC overlay were numerically obtained using the three-dimensional finite element method with the aid of ABAQUS a commercial program. Variations in the AC overlay’s modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients method. Comparing the mechanical behavior in terms of surface deflection, stress, and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC overlay. In addition, the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore, future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词: asphalt concrete overlay     anisotropy     temperature gradients     modulus gradients     finite element simulation     sensitivity analysis    

Sensitivity analysis of torsional vibration behavior of the shafting of a turbo generator set to changesof its mechanical parameters

XIE Danmei, ZHANG Hengliang, DONG Chuan, LIU Zhanhui, YANG Changzhu

《能源前沿(英文)》 2007年 第1卷 第4期   页码 483-486 doi: 10.1007/s11708-007-0072-4

摘要: Aiming at a 300 MW turbo-generator model, the sensitivity of natural torsional frequencies and modes of torsional vibration (TV) to the rotational inertia and stiffness of the turbo-generator were analyzed. Calculation results show

关键词: Calculation     MW turbo-generator     sensitivity     stiffness    

Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor

Haoyi SUN, Tao LI, Weiyong YING, Dingye FANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 515-522 doi: 10.1007/s11705-010-0516-7

摘要: Slurry bubble column reactors (SBCR) is a three-phase fluidized reactor with outstanding advantages compared with other reactors and is difficult to scale-up due to lack of information on hydrodynamics and mass transfer over a wide range of operating conditions of commercial interest. In this paper, an experiment was conducted to investigate the bubble behavior in SBCR with a height of 5600 mm and an interior diameter of 480 mm. Bubble rise velocity, bubble diameter, and gas holdup in different radial and axial positions are measured in SBCR using four-channel conductivity probe. Tap water, air, and glass beads (mean diameter 75–150 μm) are used as liquid, gas, and solid phases, respectively. It shows that hydrodynamic parameters have good regularity in SBCR. Moreover, a commercial computational fluid dynamics (CFD) package, Fluent, was used to simulate the process in SBCR. The simulations were carried out using axi-symmetric 2-D grids. Data obtained from experiment and CFD simulation are compared, and results show that the tendency of simulation is almost uniform with the experiment, which can help to obtain further understanding about multiphase flow process and establish a model about the synthesis of alcohol ether fuel in SBCR.

关键词: SBCR     four-channel conductivity probe     hydrodynamics     CFD    

标题 作者 时间 类型 操作

A miniature triaxial apparatus for investigating the micromechanics of granular soils with

Zhuang CHENG, Jianfeng WANG, Matthew Richard COOP, Guanlin YE

期刊论文

Strengthening of polysulfone membranes using hybrid mixtures of micro- and nano-scale modifiers

Peyman P. Selakjani, Majid Peyravi, Mohsen Jahanshahi, Hamzeh Hoseinpour, Ali S. Rad, Soodabeh Khalili

期刊论文

Achievements and trends of solid oxide fuel cells in clean energy field: a perspective review

Abdalla M. ABDALLA, Shahzad HOSSAIN, Pg MohdIskandr PETRA, Mostafa GHASEMI, Abul K. AZAD

期刊论文

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

期刊论文

Micro-spectrophotometer based on micro electro-mechanical systems technology

ZHOU Lianqun, LI Zhenggang, WU Yihui, ZHANG Ping, XUAN Ming, JIA Hongguang

期刊论文

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

期刊论文

A bionic approach for the mechanical and electrical decoupling of an MEMS capacitive sensor in ultralow

期刊论文

Correction to: Effect of wood dust type on mechanical properties, wear behavior, biodegradability, and

期刊论文

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

期刊论文

A comparative study of the mechanical properties, fracture behavior, creep, and shrinkage of chemically

Mahdi AREZOUMANDI, Mark EZZELL, Jeffery S VOLZ

期刊论文

Effect of wood dust type on mechanical properties, wear behavior, biodegradability, and resistance to

Sawan KUMAR, Ajitanshu VEDRTNAM, S. J. PAWAR

期刊论文

Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured

Mahdi IZADI, Khosrow BARGI

期刊论文

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

Lingyun YOU, Zhanping YOU, Kezhen YAN

期刊论文

Sensitivity analysis of torsional vibration behavior of the shafting of a turbo generator set to changesof its mechanical parameters

XIE Danmei, ZHANG Hengliang, DONG Chuan, LIU Zhanhui, YANG Changzhu

期刊论文

Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor

Haoyi SUN, Tao LI, Weiyong YING, Dingye FANG

期刊论文