A class of adaptive hybrid ARQ schemes for wireless links

Wireless links are known to suffer location-dependent, time-varying, and bursty errors. This paper considers a class of adaptive error-control schemes in the data link layer for reliable communication over wireless links in which the error-control code and the frame length are chosen adaptively, based on the estimated channel state/condition. Three error-control schemes are considered according to: (1) the number of Reed Solomon code segments a packet is divided into and (2) the way a lost packet is retransmitted. Through throughput performance and computation complexity analyses, these three schemes are compared, and then one of them is claimed to be the most attractive in terms of computation complexity and practicality even though its throughput performance is not the best. The simulation results also verify that this scheme works well over a time-varying fading channel. Error control for the medium access control (MAC) header and its effect on the performance of each error-control scheme are also considered since, without proper error protection for the header, it would be futile to exercise error control on the user data     

Full software analysis and impedance matching of radio frequencyCMOS integrated circuits

We present a systematic analysis technique of complementary metal-oxide-semiconductor (CMOS) radio-frequency (RF) integrated circuits (ICs). A full simulation program with integrated circuit emphasis (SPICE) simulation of the whole chip including the package and the die, with the parameters extracted from purely software analysis, has been performed. It is shown that the RF impedance matching without S-parameter based techniques is possible and the measured results agree well with our SPICE-only software based technique     

Dependence of thermo-mechanical and mechanical properties of novel fluorophosphate glass on various rare earth dopants

The dependence of thermo-mechanical, and mechanical properties on various rare earth dopants (RE) including Nd₂O₃, Er₂O₃, and Yb₂O₃ in 0.4MgF₂-0.4BaF₂-0.1Ba(PO₃)₂-0.1Al(PO₃)₃ glasses (MBBA system) is systematically investigated. MBBA system doped with RE dopants presented the potential application in the field of communication and high power layer system in the previous reports. In this work, it is found that the density of the doped glass increases with an increasing of RE concentration, which could be understood in terms of cationic field strength (CFS) effect. The Knoop hardness is found to decrease with the loading time and dopant concentration due to the indentation size effect (ISE) effect. The observed decrease of thermal expansion coefficient and the increase of glass transition temperature T _g with increasing dopant concentration are elucidated in terms of the increasing number of strong covalent bonds with increasing RE dopant concentration. Those results will be of paramount importance before designing optical devices.     

Contactless energy transfer using planar printed circuit boardwindings

An energy transfer circuit is proposed which employs a pair of neighbouring printed circuit board windings as a contactless energy transfer device, thereby making it amenable to low-profile designs and suitable for applications in which stringent requirements for height, space and reliability have to be met     

The elastic moduli and fatigue properties of canine trabecular bone tissue

The elastic modulus and fatigue properties of canine and human trabecular bone tissues (single trabeculae) were experimentally determined on a microstructural level using four-point bending cyclic test, and they were compared based on microstructural characteristics and mineral density. The results showed that canine trabecular bone tissue had significantly lower modulus and lower fatigue strength than human tissue. The observed microstructural differences between the two tissues may be more responsible for the differences, although the lower mineral density in canine tissue might also have contributed to the lower modulus and fatigue strength.     

Error concealment using affine transform for H.263 coded videotransmissions

A new error concealment method is proposed that uses motion estimation to consider actual motions, such as rotation, magnification, reduction, and parallel motion, in moving pictures. Since many videos include a variety of complex three-dimensional motions, the proposed method uses an affine transform to estimate the motion of lost data more accurately, thereby producing a higher peak signal-to-noise ratio value and better subjective video quality     

Composition Dependence of the Electrical Conductivity of ZnO(n)–CuO(p) Ceramic Composite

Electrical properties of semiconducting ZnO( n )-CuO( p ) ceramic composites with varying composition were investigated. The electrical conductivity increased with increasing CuO volume fraction between 1 to 95 mol%. Impedance response showed three semicircles, indicating three resistive elements contributing to the total resistance of the composite. A new model based on the equivalent circuits was developed to explain the contribution of grain boundaries to the resistance of the composite. The change of electrical conductivity was explained by the probability change of two equivalent circuits.     

Experimental studies on the instabilities of viscous fingering in a Hele-Shaw cell

When air is injected into silicone oil contained in a horizontal Hele-Shaw cell, a single air bubble forms and grows showing various interesting phenomena. In this study the effects of the bubble front velocity, air injection velocity at a nozzle, fluid properties and cell depth on the stability of the growing bubble were investigated experimentally. By using the modified capillary number involving the aspect ratio, we obtained the onset conditions of the unstable bubble. Also, the bubble width was analyzed both quantitatively and qualitatively. Before the bubble experiences splitting, the bubble front velocity is almost proportional to the air injection velocity. Therefore the latter velocity may be used in a practical sense.     

Effect of water drying conditions on the surface property and morphology of waterborne UV-curable coatings for engineered flooring

UV-curable coatings are widely used on wooden materials such as flooring and furniture, because they have excellent properties, including high hardness, gloss, mar and chemical resistance, and are also environmental friendly, containing no solvents. Recently, waterborne UV-curable coatings have been studied as a viable alternative, since solvents are added to spray applications to lower viscosity. We investigated the effects of water drying conditions on the surface properties and morphology of waterborne UV-curable coatings at the flash-off step. Temperature conditions studied were 22 °C, 50 °C, and 80 °C, with various drying times. We evaluated surface properties such as pendulum hardness, pencil hardness, and adhesion strength. Also observed was surface morphology, comparing surface properties using optical microscopy after drying and UV-curing. Insufficient drying caused cracking, peeling and blistering at the surface of a cured coating. Sufficient drying was very important for the best application and ideal surface morphology of waterborne UV-curable coatings.     

Control of chaotic dynamical systems using radial basis function network approximators

This paper presents a general control method based on radial basis function networks (RBFNs) for chaotic dynamical systems. For many chaotic systems that can be decomposed into a sum of a linear and a nonlinear part, under some mild conditions the RBFN can be used to well approximate the nonlinear part of the system dynamics. The resulting system is then dominated by the linear part, with some small or weak residual nonlinearities due to the RBFN approximation errors. Thus, a simple linear state-feedback controller can be devised, to drive the system response to a desirable set-point. In addition to some theoretical analysis, computer simulations on two representative continuous-time chaotic systems (the Duffing and the Lorenz systems) are presented to demonstrate the effectiveness of the proposed method.