Effects of basicity and MgO content on the viscosity of the SiO2-CaO-MgO-9wt%Al2O3 slag system

The effects of basicity and MgO content on the viscosity of SiO2-CaO-MgO-9wt%Al2O3 slags with basicity from 0.4 to 1.0 and MgO content from 13wt%to 19wt%were investigated using the rotating cylinder method. A correlation between the viscosity and the slag structure was determined by Fourier transform infrared （FTIR） spectroscopy. It is indicated that the complex network structure of the slag melt is depolymerized into simpler network units with increasing basicity or MgO content, resulting in a continuous decrease in viscosity of the slag. The viscosity is strongly dependent on the combined action of basic oxide components in the slag. Under the present experimental conditions, increasing the basicity is found to be more effective than increasing the MgO content in decreasing the viscosity of the slag. At higher temperatures, the increase of basicity or MgO content does not appreciably decrease the viscosity of the slag, as it does at lower tem-peratures. The calculated activation energy of viscous flow is between 154 and 200 kJ＆#183;mol-1, which decreases with an increase in basicity from 0.4 to 1.0 at a fixed MgO content in the range of 13wt%to 19wt%.     

Subsurface macro-inclusions and solidified hook character in aluminum-killed deep-drawing steel slabs

Subsurface macro-inclusions and hooks are detrimental to the surface quality of deep-drawing steel sheets. However, little is known about the relationship between macro-inclusions and hooks. Thus, in this work, two ultralow carbon (ULC) steel slabs and two low carbon (LC) aluminum-killed steel slabs were sampled to study the relationship between hooks and subsurface macro-inclusions, which were detected on the cross-sections of steel samples with an area of 56058 mm2 using an automated scanning electron microscopy/energy-dispersive X-ray spectroscopy system. Results show that subsurface inclusions larger than 200 μm were almost entrapped by hook structures, whereas the location of other inclusions smaller than 200 μm had no obvious dependence on the location of solidified hooks. Furthermore, the number density (ND) of subsurface inclusions larger than 200 μm decreased from 0.02 to 0 cm-2 in ULC steel as the mean hook depth decreased from 1.57 to 1.01 mm. Similar trends were also observed in LC steel. In addition, the detected inclusions larger than 200 μm were concentrated in the region near the slab center (3/8 width-5/8 width), where hook depths were also larger than those at any other locations. Therefore, minimizing the hook depth is an effective way to reduce inclusion-induced sliver defects in deep-drawing steels.     

Influence of Te doping on the dielectric and optical properties of InBi crystals grown by directional freezing

Stoichiometric pure and tellurium (Te) doped indium bismuthide (InBi) were grown using the directional freezing technique in a fabricated furnace. The X-ray diffraction profiles identified the crystallinity and phase composition. The surface topographical features were observed by scanning electron microscopy and atomic force microscopy. The energy dispersive analysis by X-rays was performed to identify the atomic proportion of elements. Studies on the temperature dependence of dielectric constant (?), loss tangent (tanδ), and AC conductivity (σ_ac) reveal the existence of a ferroelectric phase transition in the doped material at 403 K. When InBi is doped with tellurium (4.04 at%), a band gap of 0.20 eV can be achieved, and this is confirmed using Fourier transform infrared studies. The results thus show the conversion of semimetallic InBi to a semiconductor with the optical properties suitable for use in infrared detectors.     

Cache performance optimization of irregular sparse matrix multiplication on modern multi-core CPU and GPU

This paper focuses on how to optimize the cache performance of sparse matrix-matrix multiplication （SpGEMM）.It classifies the cache misses into two categories：one is caused by the irregular distribution pattern of the multiplier-matrix,and the other is caused by the multiplicand.For each of them,the paper puts forward an optimization method respectively.The first hash based method removes cache misses of the 1 st category effectively,and improves the performance by a factor of 6 on an Intel 8-core CPU for the best cases.For cache misses of the 2nd category,it proposes a new cache replacement algorithm,which achieves a cache hit rate much higher than other historical knowledge based algorithms,and the algorithm is applicable on CELL and GPU.To further verify the effectiveness of our methods,we implement our algorithm on GPU,and the performance perfectly scales with the size of on-chip storage.     

A study on the characterization of smoke movement in shafts with different fire source positions

In this study, experimental and numerical simulation methods were combined to simulate the changing course of the temperature and velocity fields in nine different fire scenes. The characteristics of smoke movement in shafts with different fire source position factors （h/H） were quantitatively investigated, and the non-dimensional fitting function between the fire source position factors and the maximum temperature was deduced. The results showed that the location of the neutral plane moved upward as the fire source rose, and all the generated smoke spread to the upper areas; however, there was barely any smoke in the lower areas. The maximum temperature was inversely proportional to the fire source position factor; the higher the source position is, i.e. the higher the ra- tio factor is, the lower the maximum temperature is in the shaft. The experimental verification of the fire dynamics simulator （FDS） showed good results.     

Full-scale model tests and nonlinear analysis of prestressed concrete simply supported box girders

Full-scale model tests were carried out on a 30 m span prestressed concrete box girder and a 20 m span prestressed concrete hollow slab. Failure models were prestressed reinforcement tensile failure and crashing of roof concrete, respectively. The ductility indexes of the box girder and hollow slab were 1.99 and 1.23, respectively, according to the energy viewpoint. Based on the horizontal section hypothesis, the nonlinear computation procedure was established using the limited banding law, and it could carry out the entire performance analysis including the unloading, mainly focusing on the ways to achieve the unloading curves computation through stress-strain, moment-curvature and load-displacement curves. Through the procedure, parameters that influence on the bearing capacity, deformation performance and ductility of the structures were analyzed. Those parameters were quantity of prestressed reinforcement and tension coefficients of prestressed reinforcement. From the analysis, some useful conclusions can be obtained.     

Microstructure and mechanical properties of （Ti,AI,Zr）N/（Ti,AI,Zr,Cr）N films on cemented carbide substrates

（Ti,Al,Zr）N/（Ti,Al,Zr,Cr）N bilayer films were deposited on cemented carbide （WC-8%Co） substrates by multi-arc ion plating （MAIP） using two Ti-AI-Zr alloy targets and one pure Cr target. To investigate the composition, morphology, and crystalline structure of the bilayer films, a number of complementary methods of elemental and structural analysis were used, namely, scanning electron microscopy （SEM）, energy disperse X-ray spectroscopy （EDS）, and X-ray diffraction （XRD）. Adhesive strength and mechanical properties of the films were evaluated by scratch testing and Vickers microindentation, respectively. It is shown that the resulting films have a TiN-type face-centered cubic （FCC） structure. The films exhibit fully dense, uniform, and columnar morphology. Furthermore, as the bias voltages vary from -50 to -200 V, the microhardness （max. Hv001 4100） and adhesive strength （max. 〉 200 N） of the bilayer films are superior to those of the （Ti,Al,Zr）N and （Ti,Al,Zr, Cr）N monolayer films.     

Adaptive and local analysis of climate data

This paper focuses on how to extract physically meaningful information from climate data, with em- phases placed on adaptive and local analysis. It is argued that many traditional statistical analysis methods with rigorous mathematical footing may not be efficient in extracting essential physical information from climate da- ta; rather, adaptive and local analysis methods that agree well with fundamental physical principles are more ca- pable of capturing key information of climate data. To illustrate the improved power of adaptive and local analy- sis of climate data, we also introduce briefly the empirical mode decomposition and its later developments.     

Determining the approach speed envelope of carrier aircraft

Many factors, such as deck motion and air wave, influence the determination of the approach speed which has an important effect on landing safety. Until recently, there are no design criteria about approach speed of carrier aircraft in the current standards and available publications. Therefore, the requirements of stall margin, longitudinal acceleration ability, altitude correction and field-of-view on approach speed were researched. Based on the flight dynamics model, the flight simulations were conducted to study the effect of the response time of en- gine, wave off requirements, elevator efficiency and deflection rate on the approach speed. The results presented that the approach longitudinal acceleration and altitude correction ability had crucial influence on the approach speed envelope of the aircraft. The limitations of the control requirements, field-of-view requirements and gear were also given through the simulation and analysis. Based on the above results, the approach speed envelope were determined.     

The HITCR-I： Evaluation on a free gait generation method for the hexapod robot on irregular terrain

The purpose of this paper is to present and evaluate a method of free gait generation for HITCRI,a hexapod walking robot.The HITCR-I is designed as a modularized structure of legs that is based upon a four-bar linkage mechanism and with force sensors in the tip of legs,distributed hardware structure and a modular software structure of the control system.Based on a set of local rules between adjacent legs,finite state machine （FSM） model is built to control the coordination of legs.An automatic smooth transition of gait pattern is achieved through deriving the mathematical relation between gait pattern and locomotion parameters.The disordered inter-leg phase sequence is adjusted to a regular state smoothly and quickly by the local rules based FSM,and the gait pattern can transform automatically adapting to irregular terrain.The experiment on HITCR-I has demonstrated that it can walk through irregular terrain reliably and expeditiously with the free gait controller designed in this paper.     

Microstructure, crystallography and nucleation mechanism of NANOBAIN steel

The microstructure of bainite ferrite in NANOBAIN steel transformed at different temperatures was investigated by scanning electron microscopy, transmission electron microscopy, electron back-scattered diffraction, and vickers hardness tester in detail. It is found that the average width of bainitic ferrite (BF) plates can be refined to be thinner with the reduction of temperature (473–573 K), and the bainitic ferrite plates can reach up to 20–74 nm at 473 K. Crystallographic analysis reveals that the bainitic ferrite laths are close to the Nishiyama-Wasserman orientation relationship with their parent austenite. Temperature shows a significant effect on the variant selection, and a decrease in temperature generally weakens the variant selection. Thermodynamic analyses indicates that the Lacher, Fowler and Guggenheim (LFG) model is more suitable than the Kaufman, Radcliffe and Cohen (KRC) model dealing with NANOBAIN steel at a low temperature range. The free energy change ΔGγ→BF is about ?1500 J·mol?1 at 473 K, which indicates that nucleation in NANOBAIN steel is the shear mechanism. Finally, the formation of carbon poor regions is thermodynamically possible, and the existence of carbon poor regions can greatly increase the possibility of the shear mechanism.     

Synthesis and formation mechanism of micro/nano flower-like MgCO3·5H2O

Micro/nano magnesium carbonate pentahydrate（MgCO3 ·5H2 O） with flower-like morphology was synthesized using magnesite as a substrate and potassium dihydrogen phosphate as an additive. The synthesized samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The influence of pyrolysis time on crystal morphology was explored. The formation mechanism was investigated on the basis of the characterized results and the crystal structure of MgCO3 ·5H2 O. The results showed that the flower-like MgCO3 ·5H2 O was 1.5-3.0 μm in length and 100-500 nm in diameter and was successfully obtained with a pyrolysis time of 30 min. The formation mechanism of flower-like MgCO3 ·5H2 O is suggested to be the selective adsorption of potassium dihydrogen phosphate on the surface. The process of flower-like crystal growth is as follows： amorphous nanoparticles formation, acicular and rod monocrystal formation, flower-like monocrystal formation, and flower-like polymers（MgCO3 ·5H2 O） crystallization. In the MgCO3 ·5H2 O crystal, the magnesium ion presents two different octahedral coordinations corresponding to2 26 Mg（H O）＋and2 2 2 4 23 [Mg（H O）（CO） ]--, and the chemical formula of the crystal is2 2 6 2 4 23 Mg（H O） Mg（H O）（CO）2.     

Load compensation research on twicetension for loop anchor cable of inner lining in Yellow River-crossing tunnel

The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension （referred to as twice-tension anchorage system） is proposed in the paper. Calculation results of loop anchorage prestressing loss （PL） values of inner lining （IL）in Yellow River-crossing tunnel under two anchorage systems, including twice-tension anchorage system and HM （Chinese transliteration is huanmao） anchorage system, are introduced. The software ANSYS is selected to realize the three-dimensional （3D） finite element modeling to accomplish simulation and calculation works under the two anchorage systems, respectively. Stress processes of IL under the two working conditions, of which one is completed cable tensioning （CCT） and the other is water in the tunnel with the designed water pressure （DWP）, are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete （WC）. Meanwhile, the anchorage system has the advantages of improving security and stability of tunnel structure, reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable, and is worthy of promotion and application.     

Dynamic Characteristic Study of Ball Screw Feed Drive Systems Based on Multi-flexible Body Model

A new ball screw dynamic model was developed under the adequate consideration of the interaction in the screw-nut assembly （not only the mutual-coupling factors but also the self-coupling factors） . Based on this model,the multi-flexible body （MFB）dynamic model of ball screw feed drive system was then founded in order to take full account of the influencing factor of system flexibility and study the dynamic behaviors of the whole mechanical transmissions. Moreover,the MFB based state space modeling was proposed by modal state space method, which extraced the eigenmodes of more dominant modes and applied them into an MFB state space model,and realized the integrated model of servo drives and MFB mechanical transmissions more effectively and efficiently. In conclusion,the comparisons between simulations and experimental results show： the stiffness formulation of the ball screw assembly derived above is a suitable method for achieving accurate MFB models of ball screw mechanical transmission systems,this proposed MFB model is valid,and the integrated model of ball screw feed drive system is accurate and reliable. All these provide the important approaches and guidelines for dynamic characteristic study and selection of control parameters in the machine tool design period.     

Characteristics of hydrocarbon source rocks of No.3 buried-hill region in Nanpu Sag

Based on the data of 44 samples of hydrocarbon source rocks in Nanpu No.3 buffed-hill region, the kerogen type is judged through the pyrolysis and microscopic identification. At the same time, organic matter maturity and hydrocarbon generation threshold are studied by using vitrinite reflectance, pyrolysis yield and hydrocarbon abundance. Meanwhile the hydrocarbon expulsion threshold is calculated. And the characteristics of organic hydrocarbon generation and expulsion are preliminarily revealed and evaluated. The result shows that the No.3 buffed-hill region has abundant hydrocarbon source rocks with high content of organic carbon. And the primary types of kerogen are II, and lI 2. The hydrocarbon source rocks which passed biochemistry, thermolysis and thermal cracking have developed into the mature-postmature phase of different extents. And plenty of oil and gas were expelled out. It is believed the depth of oil-generating window is 3 600 m and the depth of hydro- carbon-expulsion threshold is 4 100 m. The comprehensive analysis indicates that Nanpu No.3 burried-hill region has a certain condition to generate hydrocarbon which is very promising in oil exploration and thus can become an important exploration and development target next.     

Recovery of iron from copper slag by deep reduction and magnetic beneficiation

Aiming at recovering iron from high-iron-content copper slag, this article introduced a combination technology of deep reduction and magnetic beneficiation, investigated the iron recovery efficiency and optimized the technical conditions. When coke powder with 86wt% fixed carbon was used as a reductant, iron was successfully extracted from the copper slag. Under the optimized condition of the coke powder content of 14wt%, the calcium-to-silicon mass ratio (Ca/Si) of 0.2, the roasting temperature of 1300℃, the roasting time of 3 h, the grinding time of 20 min, and the magnetic field intensity of 61 kA·m?1, the iron recovery rate of the copper slag can reach 91.82%, and the extracted iron powder has an iron grade of 96.21%. With the characteristics of high iron grade and low impurity content, the extracted iron powder can be used as high-quality raw materials of weathering steel.     

Design and evaluation of a Laval-type supersonic atomizer for low-pressure gas atomization of molten metals

A Laval-type supersonic gas atomizer was designed for low-pressure gas atomization of molten metals. The principal design objectives were to produce small-particle uniform powders at lower operating pressures by improving the gas inlet and outlet structures and optimizing structural parameters. A computational fluid flow model was developed to study the flow field characteristics of the designed atomizer. Simulation results show that the maximum gas velocity in the atomization zone can reach 440 m·s?1; this value is independent of the atomization gas pressure P₀ when P₀ > 0.7 MPa. When P₀ = 1.1 MPa, the aspiration pressure at the tip of the delivery tube reaches a minimum, indicating that the atomizer can attain the best atomization efficiency at a relatively low atomization pressure. In addition, atomization experiments with pure tin at P₀ = 1.0 MPa and with 7055Al alloy at P₀ = 0.8 and 0.4 MPa were conducted to evaluate the atomization capability of the designed atomizer. Nearly spherical powders were obtained with the mass median diameters of 28.6, 43.4, and 63.5 μm, respectively. Compared with commonly used atomizers, the designed Laval-type atomizer has a better low-pressure gas atomization capability.     

A dynamic programming algorithm for network selection in 3G/WLAN

An essential characteristic of the 4th Generation （4G） wireless networks is integrating various heterogeneous wireless access networks.This paper considers the network selection for both admission and handoff strategy problems in heterogeneous network of 3G/WLAN.A novel dynamic programming algorithm is proposed by taking heterogeneous network characteristics,user mobility and different service types into account.The specificity of our approach is that it puts the situations in a new model and makes decisions in stages of different states.Simulation results validate that the proposed scheme can obtain better new call blocking and handoff dropping probability performance than traditional schemes while ensuring quality-of-services （QoS） for both real-time and data connections.     

Exploration on ecological regulation of the reservoirs

Reservoir regulation process in the Yangtze River basin is mainly divided into two types of flood regulation and initiating benefit regulation. The present reservoir management system and operation mode are mainly for dealing with or coordinating of flood control and benefit initiation as well as benefit distribution among various beneficial functions. From the view point of river ecosystem protection, the current regulation mode has two kinds of problems ： firstly, most of the reservoir regulation plans do not consider ecosystem protection at downstream of dams and needs of environment protection in reservoir areas; secondly, integrated regulation or management of water resources is ignored. It is very necessary to improve reservoir regulation mode, bearing problems faced by regulation of the Three Gorges reservoir and issues related to cascade development and regulation in Tuojiang and Minjiang River basins in mind. In accordance with the concept of scientific development, and the philosophy of ＂ensuring a healthy Yangtze River and promoting the harmony between human and water＂, taking flood control, benefit initiation and eco-system as a whole, this paper put forward the basic consideration to improve reservoir regulation as follows ： on the basis of requirements of ecosystem protection at downstream of dams and needs of environment protection in reservoir areas, we should bring the functions of reservoir such as flood control and benefit initiation into full play, control the negative influence to the ecosystem at downstream of dams and the environment in reservoir areas in an endurable scope, and restore the ecosystem and the environment step by step. This paper put forward the relevant regulation process aiming at the idiographic problems such as protection of ecosystem at downstream of dams and environment in reservoir areas, protection of aquatic wildlife species and fish species, regulation of sediment and protection of wetland.     

Preparation of composite abrasives by electrostatic self-assembly method and its polishing properties in Cu CMP

The adsorption characteristics of cationic polyelectrolyte poly dimethyl diallyl ammonium chloride （PDADMAC） and anionic polyelectrolyte poly （sodium-p-styrenesulfonate） （PSS） on benzoguanamine formal- dehyde （BGF） particles are investigated. The charging characteristics of BGF particles are changed and con- trolled using electrostatic self-assembly method. A variety of PE,-BGF/SiO2 composite abrasives are obtained. The as-prepared samples are analyzed by zeta potential analysis, transmission electron microscope （TEM） and thermogravimetric （TG） analysis. The composite abrasive slurries are prepared for copper polishing. The poli- shing results indicate that it is SiO2 abrasives, not only coated SiO2 abrasive on polymer particles but also free SiO2 abrasive in slurry, that offer the polishing action. The material removal rates of copper polishing are 264 nm/min, 348 nm/min and 476 nm/min using single SiO2 abrasive slurry, PE0-BGF/SiO2 mixed abrasive slur- ry and PE3-BGF/SiO2 composite abrasive slurry, respectively. The surface roughness Ra of copper wafer （with 5μm×5μm district） is decreased from 0.166 μm to 3.7 nm, 2.6 nm and 1.5 nm, and the surface peak-valley values Rrv are less than 20 nm, 14 nm and 10 nm using these kinds of slurries, respectively. Key words ： chemico-mechanical polishing; polishing slurry; composite abrasives ; polyelectrolyte ; copper