Special report on relationship between wind farms and power grids

The installed capacity of a large scale wind power plant will be up to a number of hundreds MW, and the wind power is transmitted to load centers through long distance transmission lines with 220 kV, 500 kV, or 750 kV. Therefore, it is necessary not only considering the power transmission line between a wind power plant and the first connection node of the power network, but also the power network among the group of those wind power plants in a wind power base, the integration network from the base to the existed grids, as well as the distribution and consumption of the wind power generation by loads. Meanwhile, the impact of wind power stochastic fluctuation on power systems must be studied. In recent years, wind power prediction technology has been studied by the utilities and wind power plants. As a matter of fact, some European countries have used this prediction technology as a tool in national power dispatch centers and wind power companies.     

Grain Boundary Triple Junction Effects on the Fatigue Deformation and Cracking Behaviors of Copper Tricrystal and Tetracrystals

Cyclic symmetrical tension-compression fatigue tests in an axial plastic strain range of 2.0×10-4 to 1.5×10-3 were performed on three copper tetracrystal specimens containing two grain boundary triple lines as well as one copper tricrystal specimen employing a multiple step method. Experimental results show that the strengthening effect of triple junction (TJ) on axial saturation stress increased with increasing plastic strain amplitude. The strengthening effects owe much to the strain incompatibilities at TJ. The cyclic stress-strain (CSS) curves of tetracrystals are higher than that of tricrystal. At low strain amplitude, deformation at TJ is smaller than that near grain boundary (GB), which results in that the width of TJ effect zone is smaller than that near GB. Whether GB split or not is associated with the angle between GB and loading axis, activation of slip systems beside GB and the accommodation and annihilation of residual dislocations on GB planes.     

Analytic Hierarchy Process(AHP)to Optimize the Service in a Water Supply Network

Decision making in drinking water supply networks is increasingly complex due to the large number of variables involved.In order to make better decisions it is necessary to use adequate and robust methodologies.This paper presents the application of the Analytic Hierarchy Process(AHP)related to the operation of the drinking water supply network of the city of Chihuahua,Mexico,where two possible alternatives are delineated with the objective to optimize the service.The application of AHP was carried out in 24 sectors that have substantial differences in their efficiency but with instrumentation and measurement in all the variables contemplated by the operating agency,with a population of 221,722 inhabitants which represent a 30%of the total population of the city,the results indicate that the best alternative is the one with less criteria to be controlled and fewer repercussions on the cost of operation and investment in the rehabilitation and replacement of the network.     

Corrosion Behavior of Extruded near Eutectic Al—Si—Mg and 6063 Alloys

In this work,a comparison study on corrosion behavior of extruded near eutectic Al—12.3%Si—0.26%Mg and 6063 alloys has been carried out by mass loss test in 4%H₂SO₄ aqueous solution in the open air and potentiodynamic polarization test in 3.5 wt.%NaCI aqueous solution.Results indicate that the corrosion resistance of the near eutectic Al—Si—Mg alloy is less than that of 6063 alloy.Macro/microscopy and scanning electron microscopy results clearly show the difference of the corrosion progress of these two alloys in 4%H₂SO₄ aqueous solution.The corrosion type of 6063 alloy is pitting corrosion.The Mg₂Si and AlFeSi particles and surface defects act as nucleation sites for pitting,and the amount and distribution of them have a significant effect on the pitting behavior.For the near eutectic alloy,there are two types of corrosion cells. One is between the extruded primaryα-AI and the eutectic,the other is between the eutectic Al and eutectic Si particles.Combination of these two types of corrosion cells leads to a lower corrosion resistance,a higher mass loss of the near eutectic alloy compared with 6063 alloy,and the formation of the paralleling corroded grooves.     

Phase Stability, Kinetic Diagrams and Diffusion Path in High Temperature Oxidation of Binary Solid-Solution Alloys

The phase diagrams of ternary systems involving two metal components and one oxidant are considered first, the limitations to their use is discussed in relation to the high temperature oxidation of binary alloys. Kinetic diagrams,which are useful to predict the conditions for the stability of the two mutually insoluble oxides as the external scale, are then calculated on the basis of thermodynamic and kinetic data concerning both the alloys and the oxides, assuming the validity of the parabolic rate law. A combination of the two types of diagrams provides a more detail information about the oxidation behavior of binary alloys. The calculation of the diffusion paths, which relate the oxidant pressure to the composition of the system in terms of the alloy components both in the alloy and in the scale during an initial stage of the reaction in the presence of the parabolic rate law, is finally developed.     

Properties of Cast Hiduminium/Corundum Particulate Composites

This paper reports some results obtained in an investigation to see how increasing the corundum dispersoid content from o% to 7% in a matrix of hiduminium alloy affects the tensile and compressive strengths, the hardness and the casting characteristics of the composite. The results show that as the corundum content is increased, ultimate tensile strength (UTS)- compressive strength and hardness increase remarkably, whereas fluidity of the molten composite during casting drops significantly. It was found that just a minute amount of corundum is sufficient to cause a fairly large change in the mechanical properties and the fluidity of the molten material.This drop in castability is one of the reasons why adding corundum beyond 7 percent is not recommended. If other factors are kept constant, the fluidity is seen to slightly improve if the pouring temperature of the molten metal were increased from 670 to 710℃     

A simple power supply and control unit for pulsed operation of a microchannel plate imaging detector

A simple power supply and control electronic system to operate microchannel plate (MCP) detectors for imaging transient events such as X-ray emission from laser-produced plasmas is described. The power supply consists of two parts, viz. a high voltage pulse generator of 1 kV amplitude with a variable pulse duration of 100 μs to 1 ms for the MCP input, and a regulated 5 kV d.c. for biasing the phosphor screen. The control unit synchronizes the high voltage pulse with the event and operates a safety switch to guard the detector against any accidental rise in the background pressure. A signal-to-noise ratio ≥ 75 is obtained, limited by the noise contribution of the Charge Coupled Device (CCD)-frame grabber combination attached to the MCP. The system is compact, has provision for both positive and negative pulses, is extendable to higher voltages for operating two-stage MCP, and is immune to electromagnetic interference.     

Development and Background of Shells Theories-A Review Study

Thin shells are one of the structural elements that have versatile contributions in different engineering sectors,specifically in architectural,civil,mechanical,aeronautical,and marine engineering industries.Liquid-retaining structures,wide-span roofs,water tanks,arch dooms,and shells used in building nuclear power plants are recognized application examples of shell structures in architectural and civil engineering.This variety in using shells in different engineering sectors is due to the productivity of load-carrying behavior,excellent reservation in strength and structural integrity,shell structures are preferable in comparison to structural systems having the same span and dimensions;high stiffness,and covering a large areas.Besides the above distinguishing mechanical pros,it is widely accepted that structures and building containing shells are usually preferred by architectures and designers for aesthetic purposes.The analysis of shells has gone through many stages until the arrival of modern theories.In this study the different theories of shells were discussed,the background and development of shell theories were illustrated in this investigation.     

Fushun Steel Plant

Fushun Steel Plant is situated at thewestern part of Fushun city, Liaoning Pro-vince, 45 km from Shenyang. It is one ofthe major special steel plants in China.Established in 1937, Fushun Steel Planthas had a history of more than half century.Before 1948 it was a small-scale plant.From 1937 to 1948 the total steel productionwas only 58000 t. After foundation of PRCthere have been two stages of reconstruction;after the 1st stage (1958 to 1962) the plantbecame the first production base of su-peralloy and stainless steel in China: from1978 to 1983 (second stage) five sets oflarge advanced melting and hot workingequipment and ten sets of measurement     

Metal/Ceramic Interfaces and their Orientation Relationship

When single crystals of two different materials are in contact at a sharp interface and there is an epitaxial orientation relationship between them, the orientation relationship at the two sides across the interface is such that the degree of lattice continuity is maximized. In this study, a geometric method for predicting the orientation relationship between two crystals has been developed and applied to different homo-and heteroepitaxial systems. By means of this method, it is possible to determine the orientation relationship between any two crystals.     

Computer Simulation of the Indentation Creep Tests on Particle-Reinforced Composites

A systematical simulation has been carried out on the indentation creep test on particle-reinforced composites.The deformation ,failure mechanisms and life are analyzed by three reasonable models.The following five factors have been considered simultaneously:creep property of the particle,creep property of the matrix,the shape of the particle, the volume faction of the particle and the size(relative size to the particle )of the indentation indenter.For all the cases,the power law respecting to the applied stress can be used to model the steady indentation creep depth rate of the indenter,and the detail expressions have been presented.The computer simulation is analyzed by the two-phase model and the three-phase model.Two places of the stress concentration are found in the composites.One is ahead of the indentation indenter, where the high stress state is deduced by the edge of theindenter and will decrease rapidly near to a steady value with the creep time The other one is at the interface,where the high stress state is deduced by the misfit of material properties between the particles and matrix.It has been found that the creep dissipation energy density other than a stress parameter can be used to be the criterion to model the debonding of the interfaces.With the criterion of the critical creep dissipation energy density, a power law to the applied stress with negative exponent can be used to model the failure life deduced by the debonding of interfaces.The influences of the shape of the particles and the matching of creep properties of particle and matrix can be discussed for the failure.With a crack model,the further growthe of interface crack is analyzed, and some important experimental phenomena can be predicted.The failure mechanism which the particle will be punched into matrix has been also discussed.The critical differences between the creep properties of the particles and matrix have been calculated, after a parameter has been defined.In the view of competition of failure mechanisms, the best matching of the creep properties of the two phases and the best shape of the particles are discussed for the composite design.     

An Axisymmetric Numerical Model for Simulating Kinetically—Limited Growth of a Cylindrical Rod in 3D Laser—induced Chemical Vapor Deposition

Laser-induced chemical vapor deposition（LCVD） is an important process for freeform microfabrication of high aspect ratio prototypes.The system consists of a laser beam focused onto a movable substrate in a vacuum chamber.Heat from the laser at or near the focal spot of the beam causes gas in the chamber to react.As a result ,solid-phase reaction products are deposited on the substrate to from the microstructure.In this paper,we develop a numerical model for simulating growth of an axisymmetric cylindrical rod by pre-specifying the surface temperatures.The solution using least squares is obtained by minimizing the sum of square deviations between the pre-specified surface temperatures and the calculated temperatures from the heat equation with a given laser power as a heat source.Model predictions of the laser power over growth time helped in optimizing the growth process.Rods grown based on the predicted laser power from the numerical model were very close to being cylindrical in shape.Ways to further improve the model are being investigated.     

Study of the Static Properties I-V of Mosfet

Today, telecommunications, data processing, physics and electronics, take a very important place in the activities of research of the various laboratories. In the field of the ultra high frequencies, the field-effect transistor MOSFET caused many studies and research to exploit its interesting and promising characteristics as well as possible. The objective of this contribution is devoted to study the static properties I-V of MOSFET. The study enables us to calculate the drain current as function of bias in both linear and saturated modes; this effect is evaluated using a numerical simulation program, one could notice that the MOS transistor characteristics are very sensitive to the temperature. The load of inversion via the threshold voltage and the mobility of the carriers are the two principal impacted parameters, it was noted that the increase in the temperature induces a drop of the threshold voltage like that of mobility, and an immediate consequence of this reduction is the diminution in the drain current. One can thus conclude that the temperature influences the performances of the device; more it is low, better is the reliability of the device under operation.     

Thermal Shock Behaviour of Alumina—Iron Composites

Thermal shock behaviour was investigated for two morphologically different composites comprising an alumina matrix and 20 vol.pct Fe particles for a wide range of quenching temperature differences(ΔT=100-800℃)and compared to a monolithic alumina.The retained strength and critical quenching temperature difference,ΔTc,of the two composites were a significant improvement over the values for the respective monolithic alumina.Crack lengths and densities were shown to be greater for the alumina than for the two composites at all quenching temperature differences .The thermal shock resistance parameters for monolithic alumina and the two composites were calculated according to their mechanical and physical properties.The calculated results agree well with the experimental one and indicate possible explanations for the differences in thermal shock behaviour.     

Ways of Increasing Synergy in Automated Factory Design and Commissioning Teamwork

The present paper is focused on the problems of reducing losses of resources at the start-up of new automated factories caused by human shortcomings in teamwork activities. The research is based on a unique database of empirical studies of human faults and mistakes at the design and commissioning of factory automation systems. This database covers over 25 automated factories on three continents, containing pulp and paper mills, chemical and petrochemical plants and power stations. It is shown that the most suitable tool for teamwork analysis is the design structure matrix （DSM）method, which allows visualisation of the full complexity of synergy relations between all team members on the basis of the frequency and amount of information interchange. The mathematical treatment of DSM matrixes enables us to form the most capable teams, to schedule and evaluate their activities. It is shown that as a result of logical analysis it is possible to create an optimal communication and cooperation system, where the competences and capabilities of the teams and their members can be more fully exploited.     

Neutron Capture Therapy (NCT) & In-hospital neutron irradiator (IHNI)—a new technology on binary targeting radiation therapy of cancer

BNCT is finally becoming “a new option against cancer”. The difficulties for its development progress of that firstly is to improve the performance of boron compounds, secondly, it is the requirements of quantification and accuracy upon radiation dosimetry evaluation in clinical trials. Furthermore, that is long anticipation on hospital base neutron sources. It includes dedicated new NCT reactor, accelerator based neutron sources, and isotope source facilities. In addition to reactors, so far, the technology of other types of sources for clinical trials is not yet completely proven. The In-Hospital Neutron Irradiator specially designed for NCT, based on the MNSR successfully developed by China, can be installed inside or near the hospital and operated directly by doctors. The Irradiator has two neutron beams for respective treatment of the shallow and deep tumors. It is expected to initiate operation in the end of this year. It would provide a safe, low cost, and effective treatment tool for the NCT routine application in near future.     

Hot-nanoparticle-mediated fusion of selected cells

Complete fusion of two selected cells allows for the creation of novel hybrid cells with inherited genetic properties from both original cells.Alternatively,via fusion of a selected cell with a selected vesicle,chemicals or genes can be directly delivered into the cell of interest,to control cellular reactions or gene expression.Here,we demonstrate how to perform an optically controlled fusion of two selected cells or of one cell and one vesicle.Fusion is mediated by laser irradiating plasmonic gold nanoparticles optically trapped between two cells (or a vesicle and a cell) of interest.This hot-particle-mediated fusion causes total mixing of the two cytoplasms and the two cell membranes resulting in formation of a new hybrid cell with an intact cell membrane and enzymatic activity following fusion.Similarly,fusion between a vesicle and a cell results in delivery of the vesicle cargo to the cytoplasm,and after fusion,the cell shows signs of viability.The method is an implementation of targeted drug delivery at the single-cell level and has a great potential for cellular control and design.     

The“gene”of reversible phase transformation of phase change materials:Octahedral motif

Nonvolatile phase change random access memory(PCRAM)is regarded as one of promising candidates for next-generation memory in the era of Big Data.The phase transition mechanism of phase change materials is the key scientific issue to be addressed for phase change memory.Moreover,obtaining homogeneous phase change materials with high speed,low power consumption,long life and good thermal stability is still the ultimate challenge for high-density three-dimensional(3D)PCRAM.In this paper,starting from the octahedral structure motifs(octahedrons)which are considered as the"gene"of phase change materials,a new view on the phase transition mechanism is proposed.Based on this mechanism,a homogeneous phase change material is developed by constructing three matched octahedrons,which achieved an overall improvement in performance,showing 180℃ten-year data retention,6 ns SET speed,one order of magnitude longer life time and 75%reduced power consumption compared with traditional Ge₂Sb₂Te₅(GST)devices.It is of great significance to use it in 3D PCRAM chip and multi-level brain-inspired computing chip in the future.     

Hydrodynamics numerical investigation of hoistable masts for underwater vehicles

Hoistable masts are key systems of underwater vehicles. The hoistable mast enables a underwater vehicle to penetrate the sea surface and exchange information with little risk of being detected. It is very important for researching the hydrodynamic behaviour of flow pass hoistable masts in order to reduce the production of visible, electro-optic, infrared, radar cross section wake and hydroacoustics signatures. Using the unsteady incompressible Navier-Stokes equation as the governing equation, the large eddy simulation (LES) model is implemented to investigate the shedding of vortices, the flow pattern of turbulence, the unsteady pressure fluctuation and the time history of the lift coefficient and drag coefficient of hoistable masts with various mast shapes and various arrangements in this paper. Combining the FFT, combined time-frequency transform and wavelet power spectrum analysis, the characteristics of unsteady pressure can be obtained in both time and frequency domain. It shows that the main frequency of pressure fluctuation is near the frequency of vortex shedding in time domain using the FFT method. It can be inferred from the combined time-frequency transform that the unsteady pressure fluctuation has obviously the peak value and second peak value in time domain. It could indicate that the fluctuation power varies from the fluctuation frequency through the power spectrum analysis. By the data analysis, it shows that the vortex shedding is the dominant cause of the periodically pressure fluctuation. And the interaction pattern of wake and interplay between wake and the walls of masts under different arrangements are also discussed in this paper.     

Ultrathin planar broadband absorber through effective medium design

Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material,fabrication,and system cost.Here,we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers.The absorber consists of two ultrathin absorbing dielectrics to designan effective absorbing medium,a transparent layer,and metallic substrate.Compared with previous studies,this strategy provides another dimension of freedom to enhance optical absorption;therefore,destructive interference can be realized over a broad spectrum.To demonstrate the power and simplicity of this strategy,we both experimentally and theoretically characterized an absorber with 5-nm-thick Ge,10-nm-thick Ti,and 50-nm-thick SiO2 films coated on an Ag substrate fabricated using simple deposition methods.Absorptivity higher than 80％ was achieved in 15-nm-thick (1/50 of the center wavelength) Ge and Ti films from 400 nm to near 1 μm.As an application example,we experimentally demonstrated that the absorber exhibited a normal solar absorptivity of 0.8 with a normal emittance of 0.1 at 500 ℃,thus demonstrating its potential in solar thermal systems.The effective medium design strategy is general and allows material versatility,suggesting possible applications in real-time optical manipulation using dynamic materials.