Applied Mechanics and Materials

Published by Trans Tech Publications
Online ISSN: 1660-9336
This paper discusses the regenerative braking system for electric vehicle (EV) that performs regenerative energy recovery based on analytical deduction of several regenerative braking systems with the microscopic view of pulse width modulation (PWM) driving, a constant regenerative current control scheme is proposed, thereby providing improved performance and the energy recovery efficiency at minimum cost. Experimental results of EV show that the proposed regenerative braking control strategy has not only excellent control performance, but also make the very significant energy saving possible.
The paper focused on proposing a generic design for the structure model of semiconductor manufacturing. By means of analyzing traits of semiconductor manufacturing, stratifying on the definition of semiconductor manufacturing line, and analyzing the feasibility for computer to achieve the model design, a prototype system was achieved on NET platform finally. The paper provided a solution consisted of a description of the standard model and a solution for computer development. And it's a guidance for establishing research platform of semiconductor manufacturing scheduling.
In this paper, an adaptive fractional controller has been designed to control chaotic systems. In fact, this controller is a fractional PID controller, which the coefficients will be tuned according to a proper adaptation mechanism. The adaptation law will be constructed from a sliding surface via gradient method. The adaptive fractional controller is implemented on a gyro system to signify the performance of the proposed technique.
This paper presents a practical approach to design guard robot alarm system using GPRS technology. GPRS offers an interesting communications infrastructure for remotely accessing, controlling and interacting with robots in an integrated and highly portable manner, particularly in recent years the GPRS network provides wireless access of internet for mobile phone which becomes the most important and common terminal equipment. Therefore, in this paper the alarm information is designed to send to the user’s mobile phone, and add man-made intervention to the system, thus achieves a more convenient and reliable alarm system. The system mainly consists of two parts: detection of abnormal and dangerous situation in domestic environment and sending the alarm information as MMS form to the user’s phone via GPRS networks. Finally experiments show that the alarm system can accurately send alarm information to the user’s mobile phone. The system is low-cost, flexible, reliable, and can be widely used.
Logistic cost is accompanied by logistic activities. A logistic cost is an important indicator to measure the production efficiency of an enterprise. With strengthening the logistic management awareness, how to effectively reduce logistic cost has become a core mission. Using primary components analysis (PCA) and its advantages, influential factors on logistic cost reduction in enterprise material conveying is analyzed. On the basis of PCA model and scores by the experts, the authors computed some results that can reflect logistic cost reduction. Through case study, it can be seen that some factors play very important role and all the reasons should be taken into account because logistic cost reduction depends on the interaction of all the factors. Through analysis and deduction, it is concluded that, under the premise of minimizing the information loss of data, the application of PCA in the investigation on logistic cost reduction in enterprise material conveying approves to be practicable.
This paper analyzes the character and performance of the synthesized test bed on ground of small satellites. By studying several small satellite systems, the hardware and software architectures of flexible test bed are presented. The communication request/reply relations as well as other communication parameter"s dynamic configuration, TM data format"s dynamic description, TM signal"s automatic analysis and presents, on-board internal as well as communication monitor between satellite and ground on satellite host computer and each kind of lower computer functional simulation and so on, provides an general test simulated platform for each constituent"s development on-board, has built a closed loop simulation testing environment for the entire satellite jointing debugging. Dynamic configuring each kind of parameter is the concrete manifestation of the test platform flexible thought, the flexible test bed"s realization establishes an general test simulated platform for the smallsat development, has made up the traditional special-purpose test system"s insufficiency. The design and corresponding implementation are proven very effectively on the development of three small satellite systems.
The paper introduces MVC design pattern briefly, then discusses the Struts framework based on J2EE MVC pattern and finally gives the development procedure of how to design Web application with Struts framework. From this we can see that software framework and component reuse can enhance the efficiency of software development, offer clear responsibilities between Web page designers and software developers and improve system maintainability and extensibility.
Computational materials and materials design combined with computer techniques are very important contents in materials science. The paper used computer simulations and modeling to study the structures and characteristics of functional materials. It used first principle theory or molecular dynamics methods to study the electronic structures, conductive properties and their relationship of the cathode material. It used molecular dynamics method to study the embedded light small atomic or molecular lamellar graphite thermal behavior of the system; the use of first principles methods to manually control the formation of chemical bonds in the scientific field of single molecule and its characteristics.
The process -oriented product process model is established. The map of process model and product development is built. On the basis of product development process model, a model DMPA (Product development process model based on the process or action) is proposed. The algorithms of process deletion and recursion are put forward to implement the application system.
Let G be a simple graph with vertex set V(G) and edge set E(G), and let Z2=(0,1) For a given binary edge labeling f:E(G)→Z2,the edge labeling f induces a partial vertex labeling f*:V(G)→Z2 such that f*(v)=1(0) iff the number of 1-edges (0-edges) is strictly greater than the number of 0-edges (1-edges) incident to , otherwise f*(v) is undefined. For i∈Z2, let v(i)=card(e∈V(G):f*(v)=i) and e(i)=card(e∈E(G):f(e)=i). The edge-balance index sets of a graph G,EBI(G), is defined as {|v(0)-v(1): the edge labeling f satisfies } . In this paper, we completely determine the edge-balance index |e(0)-e(1)|≤1 sets of the graph Cn×Pb(n=0,1,2 mod 6)
High luminescent intensity micro - nanometer Ca0.69Sr0.23(PxMoy)O-4:0.05Eu(3+) phosphor were synthesized by an innovative co precipitation-melted-salt (CPMS) method, Using Eu2O3, Ca(OH)(2), SrCO3, HNO3, (NH4)(6)Mo7O24 center dot 4H(2)O, (NH4)(2)HPO4 and inorganic flux as raw materials, room temperature co precipitation and Melted-salt-calcination at 800 degrees C. The results show that the Ca0.69Sr0.23(PxMoy)O-4:0.05Eu(3+) emits strong 615 nm red light (exited by 285 nm UV), the luminescent intensity of phosphor is the highest when x / y = 1 /1. The size of the dispersed phosphor is about 1.0 mu m. The phosphors have great potential applied as photon conversion materials in Si-solar photovoltaic system and devices.
The visible-light photocatalytic degradation of an azo dye Reactive Deep Blue K-R by BiOI and BiOCl0.2Br0.1I0.7 photocatalysts was investigated. When the reaction proceeded for 1 h under the conditions of 15mg/l Reactive Deep Blue K-R solution and PH=3, the visible-light degradation degrees of Reactive Deep Blue K-R were 93% and 52% for BiOCl0.2Br0.1I0.7 and BiOI, respectively. Moreover, the photodegradation of Reactive Deep Blue K-R by BiOI and BiOCl0.2Br0.1I0.7 followed a first-order reaction kinetic and the values of k for BiOI and BiOCl0.2Br0.1I0.7 are 0.911h(-1) and 1.981h(-1), respectively. BiOCl0.2Br0.1I0.7 exhibits better visible-light-responsive photocatalytic performance for photodegradation of Reactive Deep Blue K-R than BiOI due to the smaller particle size, the larger specific surface area and the stronger redox potential of BiOCl0.2Br0.1I0.7.
A 10Gbit/s burst-mode transimpedance preamplifier is described. Regulated cascade (RGC) TIA core with variable gain, fast response peak detector, single-to-differential and output buffer are included, providing auto-gain-control and threshold extraction functions. The burst-mode preamplifier is implemented by 0.13 mu m CMOS technology, presents a high gain of 67.9dB Omega with a 3-dB bandwidth of 6.92GHz and a low gain of 57.4dB Omega with a 3-dB bandwidth of 8.60GHz with a settling time less than 20ns.
This paper addresses the design of a 3.0-8.0GHz direct-conversion receiver front-end chip for ultra-wideband (UWB) WiMedia/MBOA data communication. It comprises a partial noise cancellation broadband low-noise amplifier (LNA) and a linearity enhancement quadrature mixer. The simulation results show that the chip performance achieved the input reflection coefficient better than -11dB along the entire band and a minimum single sideband noise figure (SSB NF) of 6.57dB at IF frequency of baseband. The conversion gain ranges from 24.9dB to 29.5dB while the input third order interception point (IIP3) ranges from 1.5dBm to 8.7dBm. The chip core merely consumes 20mW from 1.2V supply.
La1-xSrxMnO3 (LSMO) has recently shown promising features as a metal-insulator material over a limited range of Sr doping (x=0.175 to 0.25). Its thermal property has been commonly measured through the very expensive calorimetric method. In this paper, a considerably more convenient thermal investigation approach to this issue through the thermal irradiation theory is proposed. LSMO compounds were synthesized with a wide range of x (0.15 to 0.5) using the precisely controlled Pechini sol-gel method. XRD phase structure analysis and XPS composition and chemical state study were adopted for quality assurance of the compounds. Resistance and infrared reflectance of the samples were measured respectively with the help of the four probe technique in temperature range of 150K to 380K and an infrared spectrometer over a temperature range of 153 K to 544 K. Investigations showed a good correlation between these two measures approving the metal-insulator characteristic of all the samples. Calculation of the total normal emittance (εN(T)) of the compounds was innovatively simplified using the measured reflectivity data through the thermal irradiation theory for graybody. Moreover, the results showed that every x ratio fabricated through the precisely controlled Pechini method presented a unique εN(T) characteristic with a different metal-insulator transition temperature.
In this paper, elasto-plastic dynamic response analyses of 300m span arch trusss structure model are carried out under the condition of earthquake by using SAP2000. The geometric and material nonlinear effects are considered. Based on the plastic-hinge theory, by gradually increasing the peak acceleration of earthquake, the structures dynamic elasto-plastic analysis have been done with Ninghe wave under the initial condition that the arch trusss stress and strain are caused by constant load and snow. According to simulation results, the critical peak acceleration is obtained when the steel framework lose stability, which can judge the anti-seismic capacity of the structure.
This paper presents a 0.18μm CMOS based Gm-C complex band-pass (CBP) filter with tuning circuit. Active-Gm-C structure with Nauta transconductor and phase-locked loop (PLL) architecture are adopted by the filter and the tuning circuit respectively which can achieve accurate frequency response. The layout size is 970μm×920μm. Under a 1.8V supply voltage, measurement results show that the pass-band gain and the ripple of the filter is 3.1dB and 3dB respectively. The bandwidth after tuning is 32.5MHz, image rejection ratio (IRR) is about 47dB, and the power dissipation of the filter is about 21.6mW.
In order to explore the possibility of enhanced creep resistance by grain size control, creep tests of stress-relieved and annealed Zr-1Nb-0.7Sn-0.1Fe cladding tubes were carried out at intermediate temperatures. The creep rate decreased significantly with increase of grain size from ~1.2 μm to 4 μm with annealing. The stress exponent was observed to be in the range of 5.0~6.5 for both stress-relieved and annealed Zr-1Nb-0.7Sn- 0.1Fe, suggesting that the dislocation climb is the rate controlling creep mechanism. It was shown that not only the creep rate decreased but also creep life increased in the annealed Zr-1Nb-0.7Sn-0.1Fe, suggesting the grain size control may provide an effective way to enhance the creep resistance in Zr alloys for nuclear application.
Single phases of TbxY1-x Al3(BO3)4 (0≤x≤0. 2) phosphors were synthesized by a sol-gel combustion method with citric acid as fuel and complexing agent. Our method involves only exothermic decomposition of an aqueous citrate-nitrate gel and the gel yielded nanocrystalline TbxY1-x Al3(BO3)4 phosphors at 1000°C, without any formation of intermediate phase. The optimal doping concentration of Tb3+ ions in the serials was found to be approximately 12mol%. The decomposition of the gel was investigated by TG-DTA. The product has been further characterized by X-ray powder diffractometry (XRD) and fluorescent divide spectroscopy (FDS).
La1-xSrxMnO3 thin films with x=0.2 and 0.33 were prepared by magnetron sputtering method for its potential application on thermal control of spacecraft. The materials show a phase transition from ferromagnetic metal phase with a low infrared emittance to paramagnetic insulator phase with a high emittance. Because of the thermochromic property, they can automatically change their infrared emittance greatly in response to environment temperature and thermal load and keep the spacecraft electronic components working normally. A superconduction quantum interference device magnetometer was used to study magnetization over the temperature range 100-315 K. Temperature dependence of total hemispherical emittance was carried out in a liquid nitrogen cooled vacuum chamber by a steady state calorimetric method. Thermal emittance results indicate an obvious tuneability of both La0.8Sr0.2MnO3 and La0.67Sr0.33MnO3 thin films. Compared to La0.8Sr0.2MnO3 thin film, La0.67Sr0.33MnO3 thin film has a higher transition temperature and bigger emittance tuneability. Based on phase separation concept, the thermal emittance was fitted by two-energy-level Boltzmann distribution of metal phase volume fraction f(H). The measured magnetization curves were fitted in terms of mean-field approximation theory. The volume fraction of ferromagnetic phase f(M) was not coinciding with the f(H) very well. This result showed the f(H) and the f(M) plays a different role on thermal emittance property.
The compressive creep behavior of Mg-4Al-1RE-1Ca-0.2Sr (AECJ411002) alloy was investigated at temperatures in the range of 125 similar to 175 degrees C and different compressive stress in the range of 88 similar to 112MPa with special apparatus. The results show that the creep deformation increases with the increasing of temperature and compressive stress. There is linear logarithmic relationship between the steady creep rate and all the temperature and stress used. The steady creep rate obeys an empirical equation. The stress exponents are similar at different temperatures and the appearance activation energies are not greatly different under different stresses. Their average value is respectively 6.19 and 39.05kJ/mol. Material constant A is 4.18x10(-14). The steady creep rate is controlled by a dislocation climb led by grain boundary sliding. The creep resistance enhances because of the heat-resistant phases Al2Ca and Al4Sr distributing at grain boundary.
The compounds of Fe substitution of Cr in nanotructured Sr2Fe1-xCrxMoO6 (0 <= x <= 0.3) double perovskite have been prepared by sol-gel method. The x-ray diffraction patterns of the samples show that the samples are in nanometer range. And the average grain size D for these samples is 39.7, 37.1, 33.4, 31.9, and 31.2nm, respectively, decreases with the increasing of Cr ion. The saturation magnetization and the magnetoresistance of the samples decrease with the increasing of Cr for the disorder defects which increase for the close ionic radii of Mo and Cr.
It was optimized that the lateral stiffness of an under-designed super high-rise building located in 0.30g seismic fortified regions, with 58 stories above the ground and 235.80 meters total structural height. By having adequately adjusted the wall thicknesses of the core-wall and the cross sectional dimensions of the frame columns, a more reasonable structural scheme was obtained. It was then discussed the suitable numbers and heights of the strengthening stories set for controlling the building's story drifts. Finally, it was explored that the efficiency of seismic input energy dissipation via viscous dampers installed at the right places of the structure.
The corrosion behavior of AZ91-0.4%Nd alloys was investigated by immersion test in 3.5wt.% NaCl at 25 degrees C. The phase compositions and microstructure of the AZ91-0.4%Nd alloy were characterized by XRD and OM, respectively. The results show that the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, and the granular or acicular Al3Nd phase precipitate in matrix.The corrosion products of the AZ91-0.4%Nd alloy mainly composed of Mg(OH)(2) and Al. The addition of Nd element significantly refine the microstructure and improve the compactness of corrosion products of AZ91-0.4%%Nd magnesium alloy, as a result the corrosion resistance of alloy was improved obviously.
The microstructure and corrosion behavior of commercial AZ91/AZ91-0.4%Nd alloys were investigated by OM, immersion test and weight-loss method. It was found that the number of Nd element in the AZ91 magnesium alloy has effect on the grain refining efficiency, the coarse beta-Mg17Al12 phase distributed along the grain boundaries transformed into granular, and the granular or acicular Al3Nd phase precipitated in matrix. The addition of Nd element significantly reduces the corrosion rate of AZ91-0.4%Nd magnesium alloy, as a result the corrosion resistance of alloy was improved obviously.
The cylinder-flat gauge of 0.56 mm heel-toe difference (HTD) flat with 3 mm-long plane ground on setover was calculated by the method of geometry. The change curves of cylinder-flat gauge were given by using MATLAB software under three conditions of 0.56 mm HTD flat, 0.56 mm HTD flat with 3 mm-long plane ground on setover, and 0.49 mm HTD flat. It conclude that the average gauge under 0.49 mm HTD adopted is smaller than that under 0.56 mm HTD flat with 3 mm-long plane ground on setover, and 0.49 mm HTD is realized easily in processing.
(Na0.8K0.2)(0.5)Bi0.5TiO3 (NKBT20) lead free environmental protection thin films were deposited on Si(100), Pt/Ti/SiO2/Si(100),LaNiO3/SiO2/Si(100) and SrTiO3(STO)/Pt/Ti/SiO2/Si(100) by metal organic decomposition, and the effects of mismatch induced by different seed layers on microstructures, leakage current density, ferroelectric and dielectric properties of these thin films were investigated in detail. The NKBT20/STO thin film with single perovskite phase is of the largest grain size, dielectric constant, remnant polarization and the smallest leakage current density. This could be attributed to the fact that the optimum seed layers can lower the lattice and thermal mismatch between the seed layers and the thin film. The improved electric properties may make NKBT20/STO thin film a promising candidate in micro-electro-mechanical system.
The transient liquid-phase sintering behavior of micro-Zn/nano-Sn-3.0Ag-0.5Cu (SAC) pastes was examined at a temperature of 190 °C as a function of the volume of ultrafine (~12.4 nm) SAC nanoparticles present. SAC nanoparticles have lower melting point drop than the bulk SAC particles. Although successful linkage at the interface between all Zn particles was not accomplished in all sintered samples, the number of linkages increased marginally with a decrease in the SAC content. As a result, the electrical resistivity of the sintered samples decreased with the decrease in the SAC content; however, the resistivities were still very high in all samples. Microstructural observations indicated that the observed results were mainly due to the short lifespan of the liquid phase caused by the coarsening of SAC nanoparticles during heating.
Brass and cooper are widely used in heat pump water heater as heat exchanger between refrigerant and water, and the scaling is seriously at 60° Study the precipitation characteristics of CaCO3 is the first step to research anti-fouling technology. CaCO3 precipitated on brass and copper coupons from 0.5mmol/l CaCO3 solution by static reaction at 60° By weighing the coupons before and after experiments to get the mass of scaling and use Scanning Electron Microscope (SEM) to get the morphology. The results show that at the same condition there is more scaling on copper than brass; high pH not only makes more new crystal nuclei but also promotes square aragonite and calcite and square aragonite gradually recrystallizes to calcite; high pH makes both homogeneous and heterogeneous nucleation rate increasing, but the former increases more, so the scaling mass is bigger at low pH than high pH; under high temperature and supersaturation degree, very small and many crystals are the main substances covered metal surface and not big when scaling layer has been formed, but part of small crystals grow big and all three polymorphs existed but size and proportion were effect by temperature, concentration, pH and so on.
The corrosion behavior of extruded Mg-1Ca-0.5Mn (weight percent) alloy in 0.9% sodium chloride water solution was investigated by using mass-loss measurement and electrochemical method. The results show that filiform corrosion and pitting corrosion occur during immersion corrosion process. The average corrosion rate gradually decreases as immersion time increases; it is 0.53 mm/a after immersion at 37 degrees C for 11 days. The corrosion current density i(corr) and corrosion potential E-corr of the alloy is 0.042 mA/cm(2) and -1.60V, respectively. The instantaneous corrosion rate is 0.88 mm/a. Mg-1Ca-0.5Mn alloy erodes by continuous dissolution. The corrosion product Mg(OH)(2) layer surrounding the magnesium alloy can decrease the corrosion rate. The erosion process of the magnesium alloy is controlled by cathodic diffusion.
Effect of different strain rate on mechanical properties and microstructures of Fe-Mn-C twip steel were studied by dynamic compressed using Gleeble 3500 at room temperature. The results show that Rm and Rp0.2 gradually increase with the strain rate increasing, and the TWIP steel has a strong strain rate effect; The curves of strain hardening rate and true strain have different stage with different strain rate; The mechanism of the deformation behavior was also investigated, it was found that the evolution of microstructure was controlled by dislocation and deformation twins, but the density of dislocation and the appearance of twins were different with increasing strain rate.
This paper deals with the design and analysis of a three-phase CDROM motor driver chip using a 0.6um CMOS process. An analysis of this circuits system, it is found that the driving current can be up to 500mA as in the three-phase DC motor operation. In the CMOS process, a lot of component, i.e., control and power circuits are integrated in the same chip. Here, we will focus on the design of high-current driver part and present the results obtained from the motor operating at different situations.
Microstructure of as-cast AZ91D alloy doped with 0.7wt% silicon was investigated, the damping capacity of the alloy was measured by cantilever beam technique, and the damping mechanism was also analyzed. The results show that after addition 0.7%Si into AZ91D alloy, the dendritic grains are refined, and Chinese script Mg2Si phase forms in the interdendritic areas. The damping capacities of the alloy are improved by Si addition, and increase with increasing of strain amplitude. The damping behavior of the alloy is mainly resulted from dislocation movement, and can be explained by the theory of Granato and Lucke.
A fully integrated CMOS receiver front-end with digital output for optical signal processing system is presented. This circuit is composed of trans-impedance amplifier (TIA) for weak optical current detection, post-amplifier for both a linear and limiting amplification, control circuits and the digital output interface. Measured with photodiode which is driven by pulse voltage source, a sensitivity of 0.7 mu A was achieved. The current model methodology is employed to optimize the noise performance. The front-end consumes the current of 1.5mA with the power supply of 3.3V. The design was done in a low-cost standard CMOS process with 0.6 mu m featured size, taking area of 600 mu mx150 mu m excluding the bonding pads.
In this study, performances of double delta-doped AlGaAs/InGaAspseudomorphic high electron mobility transistors are investigated. Simulation results demonstrate good performance for this structure. Form simulation, the structure demonstrates a maximum current gain cutoff frequency of 145GHz for 100nm gate length, a peak extrinsic transconductance of 526mS/mm, and a maximum saturation current density of 350mA/mm.
In this paper the effects of Sb addition on heat-treated microstructure and mechanical properties of AZ61-0.7Si magnesium alloy were investigated. The results indicate that the solution heat treatment can modify the Chinese script shaped Mg2Si phase in the AZ61-0.7Si alloy. After solutionized at 420°C, the morphology of the Mg2Si phase in the AZ61-0.7Si alloy changes from the Chinese script shape to the short pole and block shapes, and the higher modification efficiency could be obtained for the alloy with the addition of 0.4 wt.%Sb. In addition, the effect of the solution heat treatment on the morphology of the Mg2Si phase can also result in the improvement of tensile and creep properties for the AZ61-0.7Si alloy. After solutionized at 420°C for 24h and followed by aging treatment at 200°C for 12h, the AZ61-0.7Si alloy exhibits higher tensile and creep properties than that of the as-cast alloy, and the properties improvement resulted from heat treatment, is more obvious for the AZ61-0.7Si alloy with the addition of 0.4 wt.%Sb
The effect of Sn addition on corrosion behavior of Mg-6Al-1.2Y-0.9Nd alloy in 3.5wt.% NaCl solution has been researched by static corrosion tests, corrosion morphologies observation, microstructure and corrosion scale analysis. The result shows that, with the content of Sn increasing, the corrosion rate decreases at first and then increases. When the addition of Sn is 1wt.%, the corrosion rate is the lowest and the corrosion resistance is improved obviously.
In this study, a new clock and ramp generator circuit framework with a 0.9V low operational voltage is designed for the voltage-mode/current-mode-controlled power management integrated chip of a DC-DC converter. In conventional clock and ramp generator circuit with operational amplifiers, its operational voltage is limited to be over 1.5V because of the problem of a higher threshold voltage in the metal-oxide-semiconductor field-effect transistor (MOSFET). As a result, it can not work well for a pulse-width-modulation DC-DC converter when a below 1V low-voltage single-cell clean-energy power source is applied. This newly-design clock and ramp generator circuit framework without operational amplifiers is investigated to cope with the limitation of the threshold voltage in the MOSFET. Therefore, the corresponding chip size and power consumption can be reduced. Moreover, this circuit still has the functions of adjustable clock frequency and ramp slope. In addition, numerical simulations by the HSPICE software and experimental results by a real chip fabricated in the TSMC 1P6M 0.18μm CMOS process are given to verify the effectiveness of the proposed circuit to produce the clock and ramp waveforms.
The first-principle method based on the pseudopotential plane-wave is adopted to analyze O-2 adsorption on the LaMnO3 (001) surface. The calculated results indicate that, LaMnO3 presents half-metal properties by calculating the band structure and density of states (DOS). In the MnO6 octahedron, the O-Mn-O bond is mainly covalent, on the contrast, O-La-O bond is mainly ionic. Molecular oxygen can adsorb on the LaMnO3 (001), M2 may be the most favourable adsorption mode. The adsorption mode leads to the formation of O-2(-).The valence of Mn in the adsorption sites after adsorption of M1 and M2 is Mn3+0.25, Mn3+0.31, respectively. M2 may be the most adsorption mode that can make Pd-0 to shift Pd2+ more quickly in the process of direct synthesis of diphenyl carbonate (DPC) using the catalyst -Pd supported on the LaMnO3.
Tidal energy is one of the most predictable forms of renewable energy. Tides posses both potential and kinetic energy. Tidal energy can be utilized by capturing potential energy i.e. by means of tidal barrage and tidal fence or by capturing kinetic energy i.e. by menas of tidal current technologies. This study is focused on diffuser augmented tidal turbines that capture the kinetic energy. The power generated by a tidal turbine is directly proportional to the cube of velocity of current flow. The role of the diffuser in diffuser augmented tidal turbines is to help accelerate the incoming current velocity. Consequently, the efficiency of the turbine is significantly increased by using a diffuser. The research community is investing considerable time and financial resources in this growing domain. The diffuser augmented tidal turbines research data is rather scarce due to their emerging nature, large and costly research & development setup, startup cost and proprietary issues. The purpose of this paper is to study the effect of length and angle on NACA 0010 airfoil for diffuser design. Numerical simulation is carried out to investigate velocity and mass flow rate at the throat. The drag force due to diffuser installation is also calculated.
The seawater corrosion resistance performances of 00Cr13Ni7Co5Mo4W maraging stainless steel were contrastively investigated by using electrochemical measurements and chemical immersion tests. The results show that breakdown potential of specimen in aging-state is reduced due to R phase precipices during aging. The difference between breakdown potential and protection potential of maraging stainless steel is little, and the restorability of the passive film is strong with small-scale shallow pits. After solution treated at 1100 degrees C for 1h followed by aged 490 degrees C for 8h,the breakdown potential and the annual corrosion rate of 00Cr13Ni7Co5Mo4W maraging stainless steel were 230 mV and 1.5091 mu m/a, respectively, showing a good resistance to seawater corrosion.
Rheological properties of microalgae suspensions affect the mixing and mass transport in photobioreactor systems and the design of downstream biomass processing technologies, and directly impact the energy demand and system performance of algae biofuel production. The purpose of this paper is to obtain the rheological properties as a function of volume fraction. The volume fractions of microalgae suspensions phi were derived according to the size distribution of the microalgae cells and cell number concentrations per cubic meter liquid. We found that at low concentrations, microalgae suspensions display a Newtonian fluid behavior. At high concentrations, microalgae suspensions behave as a shear thinning non-Newtonian fluid. The results are of potential scientific relevance and also useful in relation to the design of algae bioprocessing for the large scale production of economic biofuels.
RPSL-02 type photosensitive resin for stereolithography material was prepared with 3,4-epoxycyclohexylmethyl-3',4' -epoxycyclohexanecarboxylate (UVR 6110), bisphenol A type epoxy diacrylate (EA-612), trimethyolpropane triacrylate (TMPTA), polycaprolactone polyol (polyol-0301), triethylene glycol divinyl ether (DVE-3), benzil dimethyl ketal (Irgacure651) and a mixture of triarylsulfonium hexafluoroantimonate salts (UVI-6976) as raw materials. Some properties of the photosensitive resin were investigated. The viscosity of the photosensitive resin at 30 degrees C was 395mP(a).S, The glass transition temperature (Tg) of the UV-cured specimen was 52 degrees C, and the weight loss of the UV-cured specimen at 200 degrees C was less than 5%. The photosensitive resin and its UV-cured specimen were also characterized by infrared (IR).
The directionally solidified Nb-Ti-Si-Cr-Al-Ta-Hf-C-B (NTS-09C) superalloys were prepared by HRS method. This alloy with strong orientations of (Nb, Ti)ss and Nb-silicide along the growth direction consists of (Nb,Ti)ss, (Nb,Ti)(3)Si, alpha Nb5Si3, MC carbide and C14 Laves phases. Not only the morphologies and compositions of various phases have been systemically studied, but also the formation mechanisms have been analyzed and discussed in detail.
The copper infiltrated stainless steel was formed by double glow plasma surface metallurgy technology on 0Cr18Ni9 steel. A comparative test with untreated samples was carried out. The results indicates that the friction coefficient decreases with the load increasing, and copper infiltrated stainless steel is superior to untreated samples in wear rate and wear resistance, finally makes an analysis of the reasons.
In order to research the ablation of 0Cr18Ni9 stainless steel films whose thickness is 20 mu m, stainless steel films were ablated and micro-cut by fs laser in the paper. Firstly, the ablation threshold of 0Cr18Ni9 stainless steel films and the beam waist radius of fs laser were obtained based on the functional relation between ablation area and the laser energy. And, experimental results indicate that the waist radius of fs laser is 10.416 mu m and the ablation threshold of stainless steel films whose thickness is 20 mu m is 0.455J/cm(2). Secondly, in order to observe the heat-affected zone, metallographic phase and electrical resistivity of stainless steel films ablated by fs laser were researched in detail. And through the experimental results, we can deduce that metallographic phase of specimens which were cut by fs laser was in recovery process and the metallographic was not change. Finally, in order to research the composition of stainless steel films phase affected by fs laser ablation, specimens were tested by XRD. And through the XRD test, it can be deduced the composition of stainless steel films phase was not affected by fs laser cut and the content of phase was affected by it.
Austenite 0Cr18Ni9Ti stainless steel is one of difficult-to-cut materials. It has poor dilling process, especially for micro-hole machining. The main reasons are the tiny drill, poor rigidity, easy to deviation. Moreover, the chip is difficult to discharge, so the drilling force is increased and the drill bit is easy to break, or even it is impossible for micro-hole drilling. In this paper, the vibration drilling process is adopted. The vibration drilling 0Cr18Ni9Ti stainless steel micro-hole process mechanism is researched. The stainless steel micro-hole drilling experiments are conducted. The results show that the vibration drilling can be a better solution for 0Cr18Ni9Ti stainless steel micro-hole processing.
Accurate prediction of the order quantity for the next period is very important for the enterprise to enhance the commercial competitive advantage in a highly competitive business environment. GM(1,1) theory is one of the prediction methods that can be built with a small sample and yet has a strong ability to make short-term predictions. The objective of the paper is to propose a order quantity prediction model which is combined the improved GM(1,1) model and Markov chain model The effectiveness of the proposed approach to the order prediction is demonstrated using real-world data from a famous company in Liuzhou. The results indicate that the method of prediction is satisfying.
Applying the reciprocal accumulated generating and the constructing background value of non-equidistant sequence of GRM(1,1) model based on fitting the first accumulate+ d generating sequence with non-homogeneous exponential law for the problem of lower precision as well as lower adaptability in non-equidistant GM(1,1) model, the calculation formulas were deduced and a non-equidistant GRM(1,1) model generated by reciprocal accumulated was put forward. The grey GRM(1,1) model can be used in non-equidistant interval & equidistant interval time series and has the characteristic of high precision as well as high adaptability. Example validates the practicability and reliability of the proposed model.
Considering the problems in determining the initial value of the non-equidistant new information GM(1,1) model, the author analyzed its modeling mechanism to find out the causes of the problem. A new method for initiating value for the model is proposed to minimize the quadratic sum of the fitting error, and a initiating formula is deduced. The model with the proposed formula enjoys a high precision and adaptability, and its practicability and reliability have been validated by examples.
Top-cited authors
Roberto Sabatini
  • Khalifa University
Alessandro Gardi
  • Khalifa University
Subramanian Ramasamy
  • RMIT University
Azlan Mohd Zain
  • Universiti Teknologi Malaysia
Amirmudin Udin
  • Universiti Teknologi Malaysia