A transmit/receive IF chip set for WCDMA mobiles in 0.35 /spl mu/m CMOS

An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/.     

Measurement of rubber cutting resistance in the absence of friction

A method for assessing the resistance of rubbers to cutting by sharp objects is described. It involves the application of the cutting implement -a razor blade-to the tip of a crack in a stretched tear test piece. The method enables effects of friction on the cutting process to be substantially eliminated. Under these conditions two distinct forms of cutting are observed: one is a slow time-dependent process, while the other involves rapid, catastropic failure. Effects of test piece shape and deformation on the cutting behaviour can be taken into account by use of fracture mechanics. The relative cutting resistance of different rubbers is found to vary according to the test conditions. At low deformations the onset of catastrophic cutting can be defined by a simple relationship which is applicable to all rubbers examined.

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Résumé On décrit une méthode pour établir la résistance des caoutchouc à la coupure par des objets affûtés. Cette méthode comporte l'application d'un moyen de coupage (lame de rasoir) à l'extrémité d'une fissure dans une pièce d'essai soumise à déchirement. La méthode permet d'éliminer de manière substantielle les effets de la friction lors du processus de coupure. Sous ces conditions, deux formes distinctes de coupures sont observées: l'une est un processus lent dépendant du temps, tandis que l'autre comporte une rupture rapide et catastrophique. En utilisant la mécanique de la rupture, on peut tenir compte des effets de la forme des pièces d'essai et de la déformation sur le comportement lors du coupage. La résistance relative au coupage de différents caoutchoucs parait varier avec les conditions d'essai. Lors de faibles déformations, le démarrage de la coupure dite catastrophique peut être défini par une relation simple qui est applicable dans tous les cas des caoutchoucs examinés.

     

COMBUSTION AND HEAT TRANSFER IN COMPARTMENT FIRES

Field modeling that incorporates increasingly complex representations of the physical and chemical processes for compartment fires warrants a detailed evaluation. Detailed quantitative comparisons of our predicted velocity and temperature fields against established the computed results of Lewis, Moss, and Rubini and the experimental data of Steckler, Quintiere, and Rinkinen of a single compartment fire are in good agreement. The prospect of using a flamelet-based combustion model is encouraging. Here, more detailed chemistry can be incorporated, especially that used to predict toxic CO concentrations. This, together with the discrete ordinates radiation method, offers potential in building fire prediction.     

探讨采用绿色和非绿色模塑料封装的功率MOSFET器件之性能

绿色指令推动半导体厂家在其微电子产品封装中摒弃氧化锑、阻燃剂及卤代化合物之类的环境有害物质,然而人们可能担心,绿色封装中的新化学材料有可能影响半导体器件的性能.本文中通过热压应力测试对采用绿色和非绿色环氧模塑料(EMC)封装的功率晶体管的性能进行了评测.实验表明,绿色器件的电气和物理性能都优于非绿色器件.     

Selective growth of InAs quantum dots by metalorganic chemical vapor deposition

We report results of both strain-driven surface segregation of indium from InGaAs thin films as well as selective area epitaxy of InAs quantum dots using these films. InAs segregation from an underlying InGaAs film allows for preferential growth of quantum dots when additional InAs is deposited. By using standard lithography techniques, a two-step selective growth process for quantum dots is achieved. Furthermore, by utilizing self-assembled nanostructures as a template, selective growth of coalesced wires and dots with 100-nm feature sizes are realized.     

CFD Studies of Indoor Airflow and Contaminant Particle Transportation

This article presents a numerical study of indoor airflows and contaminant particle transportation in three ventilated rooms. The realizable k - ε model is employed to model the air-phase turbulence, while the Lagrangian particle tracking model is utilized for the particle-phase simulation. The predicted air-phase velocities and contaminant particle concentrations are validated against the experimental data obtained from the literature. In the first case, the realizable k - ε model successfully captures the flow trend and reasonably predicts the airflow velocity. The realizable k - ε model under-predicts the vertical air velocities along the vertical inlet jet axis by 11% at x = 0.219 m, which is slightly better than the standard k - ε model error of 17%. In a two-zone room case, the realizable k - ε model, combined with a Lagrangian particle tracking model, predicts the particle concentration decay with the highest normalized difference being 24%. In the third case, the influence of particle size, location of particle resource, and particle-wall collision on the particle concentrations is investigated by the realizable k - ε model and the Lagrangian model. It is found that for relatively small particles (diameter ≤ 10 μm), the particle concentration may be insensitive to the particle diameter. In addition it has been observed that the particle-collision model may have considerable effect on the particle concentration prediction.     

Mechanochemical-treated Cr-promoted Vanadyl Pyrophosphate Catalyst for n-Butane Oxidation to Maleic Anhydride

Cr-promoted vanadium phosphate (VPO) catalyst was synthesized by mechanotreating VOHPO₄·0.5H₂O in cyclohexane for 2 hr using a high energy planetary ball miller followed by calcination in a flow of n-butane/air mixture at 673 K. The physico-chemical properties of the sample were investigated by several characterization techniques such as BET, XRD, redox titration, SEM, and TPR. The data were compared to the unmilled material. BET surface area measurement of the milled catalyst showed that it possesses higher surface area (13.2 m² g^-1) compared to the unmilled catalyst (6.4 m² g^-1). Milling also caused a slight increment in the average oxidation state of vanadium as well as the percentage of V⁵⁺ oxidation state. XRD pattern of the milled material revealed that the major diffraction peaks were broadened thus indicating a reduction of particle size. SEM micrographs showed the lost in the blossom morphology and the formation of layer packages, with more circular particles in the milled catalyst. The amount of active lattice oxygen species being removed from V⁴⁺-O^- pairs increased significantly for mechanochemical treated Cr-doped VPO catalyst leads to the enhancement of the catalytic activity for n-butane oxidation to maleic anhydride.     

Large-Eddy Simulation of Turbulent Natural Convection in Vertical Parallel-Plate Channels

A numerical investigation examining natural convection in a vertical parallel-plate channel with the simultaneous presence of laminar, transitional, and turbulent regimes is conducted using large-eddy simulation. The compressible three-dimensional Favre-filtered mass, momentum, and energy conservation equations are closed using the Smagorinsky and the Vreman subgrid-scale models. A two-stage predictor-corrector numerical methodology for low-Mach-number compressible flows is adopted. Time-averaged wall temperature and field profiles are well captured by the Vreman model, while the Smagorinsky model underpredicts wall behavior considerably. It is demonstrated that the present code is capable of capturing the flow development which is unachievable by conventional Reynolds-averaged Navier-Stokes approaches.     

Novel design for high-power single-lateral-mode lasers

A new laser design for single-mode high-power applications is reported. The waveguide is a laterally flaring and transversely tapering GaAs buried ridge fabricated by selective area epitaxy. Single-lateral-mode powers of 200 mW were achieved