A 1.5 V 3.1 GHz–8 GHz CMOS Synthesizer for 9-Band MB-OFDM UWB Transceivers

This paper presents the design of a CMOS synthesizer for dual-conversion zero-IF2 Multi-Band OFDM (MB-OFDM) transceivers covering the first 9 frequency bands from 3.1GHz to 8.0GHz, each with a bandwidth of 528 MHz. A wideband single-sideband mixer with wideband inductive network loading is proposed. Moreover, a modified transformer-coupled quadrature VCO and interconnection-loading-insensitive layout technique are employed. Fabricated in TSMC 0.18-mum CMOS process and operated at 1.5V, the synthesizer measures phase noise of -127.4dBc/Hz at 10MHz offset, integrated phase noise of 4.43deg, sideband suppression of better than -22 dBc, and a switching time of less than 1ns while consuming 59 mA     

外包在中国

目前，中国正逐渐成为西方寻找外包开发游戏公司的一片新热土，Pearl Research认为中国市场上存在的大量劳动力，相对较低的劳务成本，大批的游戏玩家以及完善的设施都是形成这种态势的重要原因。通过向中国开发公司外包，仅就游戏美工一项，往往就可以帮助西方公司节约20%以上的开发成本，在次时代游戏开发成本超越400万美元的今天，开发成本的减少将直接提升公司的毛利率，并对游戏产品的获利与否产生直接影响。     

Nitsche’s method for two and three dimensional NURBS patch coupling

We present a Nitche’s method to couple non-conforming two and three-dimensional non uniform rational b-splines (NURBS) patches in the context of isogeometric analysis. We present results for linear elastostatics in two and and three-dimensions. The method can deal with surface-surface or volume-volume coupling, and we show how it can be used to handle heterogeneities such as inclusions. We also present preliminary results on modal analysis. This simple coupling method has the potential to increase the applicability of NURBS-based isogeometric analysis for practical applications.     

Structure-property relations of 55 nm particle-toughened epoxy

55-nm rubber particles significantly toughened two epoxy systems without loss of Young’s modulus, tensile strength and glass transition temperature. Transmission Electron Microscopy (TEM) showed that the nanoparticles are uniformly dispersed in matrix and have blurred interface with epoxy. 5 wt% rubber nanoparticles increased the critical strain energy release rate (G_1c) of Jeffamine D230 (J230)-cured epoxy from 175 J/m² to 1710 J/m², while the 10 wt% increased G_1c of diaminodiphenyl sulfone (DDS)-cured epoxy from 73 J/m² to 696 J/m². This is explained by comparing the surface-surface interparticle distance and total particle surface of nanocomposites with those of composites. The higher the matrix stiffness, the more nanoparticles needed for toughening. Although the 10 wt% J230-cured nanocomposite showed a 50% larger size of stress-whitened zone than the 5 wt% J230-cured nanocomposite, the 5 wt% nanocomposite showed a higher toughness. These nanoparticles were found to pose barriers to the vibration of crosslinked matrix molecules, leading to higher glass transition temperatures. While the matrix shear banding caused by nanoparticle expansion and growth is the major toughening mechanism for the J230-cured nanocomposites, the matrix plastic void growth and deformation are most probably the major mechanisms for the DDS-cured system. Under tensile loading, the nanoparticles in the DDS-cured epoxy created fibrils of 100-200 nm in diameter and 3-5 μm in length. TEM analysis in front of a subcritically propagated crack tip showed a number of voids of 30-500 nm in diameter in the vicinity of the crack, implying that rubber nanoparticles expanded, grew and deformed under loading. Unlike conventional epoxy/rubber composites in which all of the rubber particles in the crack front cavitated under loading, only a portion of the nanoparticles in this study expanded to create voids. Huang and Kinloch’s model developed from composites was found not fit well into these nanocomposites.     

In situ fabrication of platinum/graphene composite shell on polymer microspheres through reactive self-assembly and in situ reduction

We present a simple method to fabricate a uniform-sized graphene–metal–polymer composite microsphere of core–shell structure. On the surface of amine-functionalized polymer microsphere, graphene oxide (GO) sheets were affixed to give a core–shell structure by self-assembly process followed by the immobilization of platinum (Pt) ions to the assembled GO shell. Subsequently, they were chemically reduced in situ converting both GO and Pt ions to reduced GO (RGO) and Pt nanoparticles (NPs), respectively. As a result, a robust RGO-Pt composite shell, composed of RGO sheets and well-distributed Pt NPs, was fabricated on the microsphere surface. Meanwhile, the insulative GO shell was converted to the conductive RGO-Pt shell giving 24.0 S m^?1 of electrical conductivity. We demonstrated that the electrical property of the shell was significantly improved by the incorporation of Pt NPs.     

Motion of points and lines in the uncalibrated case

In the present paper we address the problem of computing structure and motion, given a set point and/or line correspondences, in a monocular image sequence, when the camera is not calibrated.Considering point correspondences first, we analyse how to parameterize the retinal correspondences, in function of the chosen geometry: Euclidean, affine or projective geometry. The simplest of these parameterizations is called the FQs-representation and is a composite projective representation. The main result is that considering N+1 views in such a monocular image sequence, the retinal correspondences are parameterized by 11 N–4 parameters in the general projective case. Moreover, 3 other parameters are required to work in the affine case and 5 additional parameters in the Euclidean case. These 8 parameters are calibration parameters and must be calculated considering at least 8 external informations or constraints. The method being constructive, all these representations are made explicit.Then, considering line correspondences, we show how the the same parameterizations can be used when we analyse the motion of lines, in the uncalibrated case. The case of three views is extensively studied and a geometrical interpretation is proposed, introducing the notion of trifocal geometry which generalizes the well known epipolar geometry. It is also discussed how to introduce line correspondences, in a framework based on point correspondences, using the same equations.Finally, considering the F Qs-representation, one implementation is proposed as a motion module, taking retinal correspondences as input, and providing and estimation of the 11 N–4 retinal motion parameters. As discussed in this paper, this module can also estimate the 3D depth of the points up to an affine and projective transformation, defined by the 8 parameters identified in the first section. Experimental results are provided.     

A one-dimensional theory on the effects of diffusion current and carrier velocity saturation on E-type IGFET current-voltage characteristics

Current-voltage characteristics of an enhancement-type insulated gate field-effect transistor (E-type IGFET) are analyzed based on a one-dimensional model, taking account also of the diffusion current component. Explicit formulae for the entire I-V characteristic curve are given. The solution for the triode characteristic shows considerable deviation from “drift current theory” in terms of turn-on voltage (or threshold voltage) and drain voltage at just saturation. The solution for the pentode characteristic taking account of carrier's saturation velocity, shows that the increase in drain current per unit drain voltage is larger in short-channel devices than in long-channel devices. Agreement with experiment is very good.     

Long-wavelength 256×256 GaAs/AlGaAs quantum well infraredphotodetector (QWIP) palm-size camera

A 9 μm cutoff 256×256 palm-size quantum well infrared photodetector (QWIP) camera weighing only 2.5 lbs, and using 5.5 W of power has been demonstrated. Excellent imagery, with a noise equivalent differential temperature (NEΔT) of 23 mK has been achieved. It is well known that QWIP has very low 1/f noise, high operability, and uniformity. As a result, this camera uses a prerecorded nonuniformity correction table (i.e., gains and offsets) stored in its read-only-memory during operation, which enabled the miniaturization of this camera. In this paper, we discuss the development of this very sensitive long-wavelength infrared (LWIR) camera based on a GaAs/AlGaAs QWIP focal plane array (FPA) and its performance in terms of quantum efficiency, NEΔT, MRDT, uniformity, and operability