A NEW MINERAL——FLUORBRITHOLITE-(CE)

The new mineral fluorbritholite-(Ce)occurs innepheline syenite,marble xenoliths,sodalite syenite xenoliths andpegmatite dikes at Mont St.Hilaire,Quebec.It is associatedmainly with analcine,microcline,aegirine,zircon,biotite,Pyro-phanite,astrophylite,ancylite,natrolite,monazite etc.The mineral is hexagonal,P6_3/m,with a 9.517 (5) (?),c 6.983(4)(?),c/a 0.7337,v 547.7(8)(?),Z=2.The strongest Xray powder diffraction lines and their relative intensities(visual)are:2.851(100),2.821(30),2.753(30),1.970(20),1.969(30)(for MSH-3).Fluorbritholite-(Ce) crystal is shown prismatic.Its colouris pale yellow,tan,reddish-brown.Streak colourless to palebrown;Lustre adamantine;OPaque to translucent;Hardness 5;Brittle;Cleavage{0001}distinct;Fracture even to conchoidal;Density 4.66(1)(meas) or 4.66g/cm~3(calc.);Non-fluorscent.Optically umaxial(-),ω 1.792 (5),ε1.786(5) in Na light;Nonpleochroic.Electron microprobe analyses correspond to ((Ce_(1.69) La_(1.02)Na_(0.82) Nd_(0.44) Sr_(0.30) Ca_(0.17) Mn_(0.17) Y_(0.09) Pr_(0.06)     

Fast alternating direction implicit method for efficient transient thermal simulation of integrated circuits

This paper presents fast alternating direction implicit (FADI) method for efficient transient thermal simulation of integrated circuits. The FADI method is formulated from Peaceman–Rachford's ADI and Douglas–Gunn's ADI methods. The update procedure of the proposed method has basic implicit form that features derivative‐free right‐hand side and hence, better efficiency and conciseness. Subsequently, through the basic implicit form of FADI method, the relationship between classical Peaceman–Rachford's and Douglas–Gunn's ADI methods can be clarified and elucidated in detail. A unified boundary condition that can cater to common kinds of boundary conditions in thermal simulation is also introduced. To further accelerate FADI method, the graphics processing unit is also utilized through Compute Unified Device Architecture implementation. It is shown that high efficiency gain can be achieved using the proposed FADI method through large time step size and data parallelism, while maintaining stability and good accuracy. As numerical illustration, an integrated circuit structure with microchannel cooling is demonstrated. Numerical results further ascertain the cooling effect of the microchannels. Copyright © 2015 John Wiley & Sons, Ltd.     

Analytical performance of 3?m and 3?m +1 armchair graphene nanoribbons under uniaxial strain

The electronic band structure and carrier density of strained armchair graphene nanoribbons (AGNRs) with widths of n =3 m and n =3 m +1 were examined using tight-binding approximation. The current-voltage (I-V) model of uniaxial strained n =3 m AGNRs incorporating quantum confinement effects is also presented in this paper. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on a tight-binding approximation. Our results reveal the modification of the energy bandgap, carrier density, and drain current upon strain. Unlike the two-dimensional graphene, whose bandgap remains near to zero even when a large strain is applied, the bandgap and carrier density of AGNRs are shown to be sensitive to the magnitude of uniaxial strain. Discrepancies between the classical calculation and quantum calculation were also measured. It has been found that as much as 19% of the drive current loss is due to the quantum confinement. These analytical models which agree well with the experimental and numerical results provide physical insights into the characterizations of uniaxial strained AGNRs.     

含钡硫铝酸盐水泥混凝土界面结构与性能研究

实验通过对含钡硫铝酸盐水泥混凝土试块宏观断裂面的形貌观察和微观界面结构及界面产物的研究,发现断裂面从集料内部断开,说明含钡硫铝酸盐水泥混凝土的界面结合力大于集料内部自身的结合力;并利用扫描电子显微镜、能谱分析和差热分析仪对混凝土试块的微观界面区的形貌及水化产物进行分析观察,研究界面结构以及界面的水化产物对混凝土性能的影响.     

Analysis of particle cloud height dynamics in a stirred tank

Local and temporal variations of the particle cloud formed in a cylindrical mixing vessel were investigated experimentally. Different particle sizes (0.5, 1, and 2 mm) and volumetric concentration up to 20 vol % were evaluated at different impeller speeds. The time‐averaged cloud height was linear with impeller frequency and with volume concentration. Suspensions with larger particles had a lower average cloud height, while the standard deviation for the temporal cloud height variation was larger. Two strong periodic phenomena were identified to be dominating the particle cloud height variations. The frequencies were linear with impeller speed, resulting in dimensionless frequencies of S₁=0.02–0.03 and S₂=0.05–0.06. The frequencies were affected by neither the particle size nor the volumetric concentration. The amplitude showed no dependency on the particle size, but the S₂ amplitude significantly decreases and S₁ increases with increasing solid concentration. The results were compared to LES/discrete element method simulations and showed a fair agreement. © 2015 American Institute of Chemical Engineers AIChE J, 62: 338–348, 2016     

A Study on the mathematical modeling of turbulent recirculating flows in gas-stirred ladles

Computed results are presented describing the velocity field and the map of the turbulent kinetic energy in a water model of an argon-stirred ladle. The theoretical predictions agree well with the measurements, when an experimentally determined void fraction distribution is used in computing the body force driving the flow. The agreement is somewhat less satisfactory, particularly regarding the maps of the turbulent kinetic energy, when the no-slip or the drift flux models are used to predict the void fraction of the gas.     

MASS BALANCE APPROACH TO FORMULATE A380.0 ELECTRICAL CONDUIT FITTINGS FROM RECYCLED ALUMINUM ALLOY SCRAPS

This paper describes calculations using the mass balance method on aluminum alloy scraps, including soft drink cans, aluminum engine components, low alloy aluminum materials, and aluminum computer disks, to formulate A380.0 casting alloy. All recycled aluminum alloys from the same source were considered to be identical. Six approaches of mixing by weight percent, with the aid of an X-ray fluorescence technique, were successfully completed. A380.0 electrical conduit fittings were produced using the die casting technique. Mechanical tests including compression, impact, tensile, and suspended load indicated that die cast recycled aluminum alloy conduit fittings under classification 4 (heavy load condition) satisfied the requirements as stated in BSEN 50086-1: 1993.     

Plasma etching optimization of oxide/nitride/oxide interpolydielectric breakdown time in flash memory devices

The breakdown time of flash memory oxide/nitride/oxide (ONO) layer t_bd under positive constant current stressing has been found to be closely related to the cumulative extent of (over)etch of the tungsten silicide, control polysilicon, and ONO layers, i.e., Σ(ΛOE). An empirical first-order relation between t_bd and Σ(ΛOE) has been derived to facilitate the plasma etch recipe optimization. This has led to a four-fold increase in the average t_bd across a 200-mm wafer to 208 s. More importantly, the spread in t_bd has been tightened to ~5%, which is down from ~54%     

SURFACE INTEGRITY IN THE MACHINING OF SOFT MAGNETIC NICKEL-IRON ALLOYS

With the rapid developments taking place in the electrical and electronic industries, soft magnetic materials are finding increasing application. Degradation of machined surfaces due to the mechanisms of surface formation when machining under geometrically defined cutting conditions lead to a corresponding deterioration in the magnetic properties of soft magnetic nickel-iron alloys. Graphical simulation techniques have been applied in order to study the interactive mechanics associated with the single point machining operation. Both the outcome of this simulation as well as the conclusions of experimental investigations into the milling of the soft magnetic nickel-iron alloy MUMETALL are the subject of this paper. The influence of machining on the topographical, the mechanical/ physical and the metallurgical properties of the surface and subsurface layer for the face milling operation using tungsten carbide cutting tools is discussed.