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/.     

An Efficient Path Planning and Control Algorithm for RUAV’s in Unknown and Cluttered Environments

This paper presents an efficient planning and execution algorithm for the navigation of an autonomous rotary wing UAV (RUAV) manoeuvering in an unknown and cluttered environment. A Rapidly-exploring Random Tree (RRT) variant is used for the generation of a collision free path and linear Model Predictive Control(MPC) is applied to follow this path. The guidance errors are mapped to the states of the linear MPC structure by using the nonlinear kinematic equations. The proposed path planning algorithm considers the run time of the planning stage explicitly and generates a continuous curvature path whenever replanning occurs. Simulation results show that the RUAV with the proposed methodology successfully achieves autonomous navigation regardless of its lack of prior information about the environment.     

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.

     

Cocoa Butter Substitute (CBS) Produced from Palm Mid-fraction/Palm Kernel Oil/Palm Stearin for Confectionery Fillings

This study investigated the physicochemical properties of ternary mixtures of palm mid-fraction (PMF):refined bleached deodorized palm kernel oil (RBDPKO):refined bleached deodorized palm stearin (RBDPS) for cocoa butter substitute (CBS). Fatty acid constituents, triacylglycerol constituents, solid fat contents (SFCs), melting behavior, polymorphism and crystal morphology were determined using gas chromatography (GC), high-performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), pulsed nuclear magnetic resonance (p-NMR), X-ray diffraction (XRD) and polarized light microscopy (PLM), respectively. Eight blends of various ratios of ternary mixtures were investigated based on the previously studied binary fat mixtures. The composition of palmitic (P) and oleic (O), POP, and crystal morphology (size and shape) of the PMF/RBDPKO/RBDPS [14.9/59.6/25.5 (%w/w)] mixture were comparable to cocoa butter (CB), while its melting profile (18.5 and 37 °C), SFC at 20 °C and polymorphism were different from CB. The iso-solid diagrams of the mixture displayed a monotectic effect at 20–25 °C. Therefore, the 14.9/59.6/25.5 PMF/RBDPKO/RBDPS mixture could be used as a CBS in confectionery fillings because of the crystal morphology and monotectic behaviors comparable to those of CB.     

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.