Thermal and physicomechanical properties of ethylene-vinyl acetate copolymer and layered double hydroxide composites

A series of ethylene-vinyl acetate (EVA) copolymer films have been prepared with different compositions viz. 2, 4, 6, and 8 wt % layered double hydroxide (LDH) nanoparticles by solution intercalation method. These solution-casted EVA/LDH nanocomposite films were dried and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. EVA/LDH films were further tested for tensile strength, density, moisture content, solubility resistance, flammability, and electrical properties. The DSC and FTIR analysis indicate strong interactions between the LDH layers and vinyl acetate groups in EVA. Further, EVA nanocomposite films show enhanced tensile strength, limiting oxygen index (LOI), and flammability rating for the addition of LDH without sacrificing the electrical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

A new benchmark for pose estimation with ground truth from virtual reality

The development of programming paradigms for industrial assembly currently gets fresh impetus from approaches in human demonstration and programming-by-demonstration. Major low- and mid-level prerequisites for machine vision and learning in these intelligent robotic applications are pose estimation, stereo reconstruction and action recognition. As a basis for the machine vision and learning involved, pose estimation is used for deriving object positions and orientations and thus target frames for robot execution. Our contribution introduces and applies a novel benchmark for typical multi-sensor setups and algorithms in the field of demonstration-based automated assembly. The benchmark platform is equipped with a multi-sensor setup consisting of stereo cameras and depth scanning devices (see Fig. 1). The dimensions and abilities of the platform have been chosen in order to reflect typical manual assembly tasks. Following the eRobotics methodology, a simulatable 3D representation of this platform was modelled in virtual reality. Based on a detailed camera and sensor simulation, we generated a set of benchmark images and point clouds with controlled levels of noise as well as ground truth data such as object positions and time stamps. We demonstrate the application of the benchmark to evaluate our latest developments in pose estimation, stereo reconstruction and action recognition and publish the benchmark data for objective comparison of sensor setups and algorithms in industry.     

EFFICIENT AND ROBUST MATRIX SOLVER FOR THE PRESSURE CORRECTION EQUATIONS IN TWO- AND THREE-DIMENSIONAL FLUID FLOW PROBLEMS

When fluid flow problems are solved by the SIMPLE-like sequential procedures, most of the computing time is spent on handling the pressure-correction equation. As a result, the overall efficiency of those sequential procedures is strongly dependent on how good is the matrix solver for the pressure correction equation. In this article, a modified conjugate gradient solver (MCGS) is presented that is specially tuned to solve the pressure-correction equations arising from both two- and three-dimensional fluid flow problems. A new solver described here lakes the advantages of conjugate gradient solver (CGS) and strongly implicit procedure (SIP) but eliminates the disadvantages of each. In contrast to the SIP, the present MCGS adopts the partial cancellation of zeroth order and is insensitive to variation of the cancellation parameter. In general, MCGS can be two or three times faster than CGS but is an order of magnitude faster than SIP and block-corrected ADI in treating large-scale problems.     

Evaluation of flowmeters for heat metering

Heat flowmeters are expected to be reasonably priced, be very reliable, and have high measurement accuracy. Various types of heat flowmeters have been developed and they are widely used in large residential and industrial buildings. In this study, three types of heat flowmeters (turbine, electromagnetic and ultrasonic) were tested for accuracy, effect of installation position and vibration, durability and performance in the field for several installation positions and in the presence of vibration. We used a liquid flow standard system and a customized durability test system in accordance with the International Organization of Legal Metrology (OIML) R 75-2 heat meter testing method. The field test was conducted in eight different locations from winter to summer. All flowmeters were calibrated before and after the field test, and the measurement deviation and the relative expanded uncertainty were calculated. The mean deviations obtained were–0.21%,–0.07%, and 0.11%, with the relative expanded uncertainties 0.48%, 0.17%, and 0.40% for turbine, electromagnetic, and ultrasonic flowmeters, respectively. The results of position and rotation tests, mean deviations by rotation angles at 90°, 180°and 270°relative to 0°(horizontal position) were–1.24%,–1.07% and–0.80%, respectively. For the vibration tests at 1 m/s² and 5 m/s² vibration acceleration, the turbine flowmeter, the electromagnetic flowmeter and the ultrasonic flowmeter showed deviations that ranged from −0.2% to −0.5%, −0.6% (2.6 m³/h), and 0.0% (negligible), respectively. In the durability tests, the accuracy of all three types of heat flowmeters remained at ±1% or less, showing sufficient durability. In the field test, the deviation of the turbine flowmeter and the ultrasonic flowmeter showed ±2.5% or less deviation. However, the electromagnetic flowmeter seems to be inaccurate below 6.9% of the maximum flow rate.     

Thermal analysis of high power LEDs on the MCPCB

The management of the reduced junction temperature of LEDs is a critical issue because it will affect many physical parameters such as light output, wave length and LED’s lifetime. The model used in this simulation consists of a metal core PCB attached with six chips(GaN on sapphire, Ag paste, cathode/anode, silicone encapsulant, mold frame) for 5W LED module. The MCPCB is composed of an aluminum base plate, a thin layer of dielectric, and a layer of copper. The temperature distribution of the developed LED module was simulated, and the thermal behavior within this 3-D model was investigated by using a commercial computational fluid dynamic code (Fluent 6.3). The results showed that the temperature variation along the vertical direction is more dominant than that in the circumferential direction due to the heat spreading effect of the copper layer. The ratio of heat dissipation through the each thermal path was calculated and compared for various input conditions. Several parameters that increase the junction temperature, such as the thermal conductivity and thickness of the dielectric layer and the encapsulate material, heat transfer coefficient and input power were also examined. Finally, a combination of designs for attenuating the junction temperature was proposed.     

Color local texture features for color face recognition

This paper proposes new color local texture features, i.e., color local Gabor wavelets (CLGWs) and color local binary pattern (CLBP), for the purpose of face recognition (FR). The proposed color local texture features are able to exploit the discriminative information derived from spatiochromatic texture patterns of different spectral channels within a certain local face region. Furthermore, in order to maximize a complementary effect taken by using both color and texture information, the opponent color texture features that capture the texture patterns of spatial interactions between spectral channels are also incorporated into the generation of CLGW and CLBP. In addition, to perform the final classification, multiple color local texture features (each corresponding to the associated color band) are combined within a feature-level fusion framework. Extensive and comparative experiments have been conducted to evaluate our color local texture features for FR on five public face databases, i.e., CMU-PIE, Color FERET, XM2VTSDB, SCface, and FRGC 2.0. Experimental results show that FR approaches using color local texture features impressively yield better recognition rates than FR approaches using only color or texture information. Particularly, compared with grayscale texture features, the proposed color local texture features are able to provide excellent recognition rates for face images taken under severe variation in illumination, as well as for small- (low-) resolution face images. In addition, the feasibility of our color local texture features has been successfully demonstrated by making comparisons with other state-of-the-art color FR methods.     

Influence of substrate temperature to prepare (1 0 3) oriented AlN films

(1 0 3) Oriented AlN films is an attractive piezoelectric material for the applications on surface acoustic wave (SAW) and film bulk acoustic wave (FBAR) devices. As regards the SAW properties of the (1 0 3) oriented AlN films, the electromechanical coupling constant (K²) is larger than the (0 0 2) oriented AlN films. As regards the bulk acoustic wave (BAW) properties of (1 0 3) oriented AlN films, it can excite a quasi-shear mode (velocity = 5957 m/s, K² = 3.8%) that can be used for FBAR liquid sensor. In this research, the (1 0 3) oriented AlN films were successfully prepared on the silicon substrate by rf magnetron sputtering. Different temperatures (100 °C, 200 °C, 300 °C, and 400 °C) were used in this experiment process. The crystalline structure of films was determined by X-ray diffraction (XRD) and the surface microstructure was investigated by the atomic force microscope (AFM). The result exhibited the optimal substrate temperature is 300 °C. The optimal (1 0 3) oriented AlN films have the strongest XRD intensity, the smallest full width at half maximum (FWHM) value (0.6°), the largest grain size (15.8 nm) and the smoothest surface (Ra = 3.259 nm).