Computation of hydrostatic piezoelectric coefficients for 1–3 composites by the finite-element method

The hydrostatic piezoelectric charge coefficients (d_h) and hydrostatic piezoelectric voltage coefficients (g_h) of 1–3 PZT/polymer composites have been calculated by two equations containing the stress tensors of each element. A composite model is divided into 162 elements, and the stress distributions are computed under 0.7 MPa hydrostatic pressure using the finite-element method. The higher d_h value is found for the composite with 30.9% PZT and the higher g_h value for the composite with 19.8% PZT.     

Efficient operation of a low-impedance Blumlein discharge initiated HF/DF chemical laser

A study is described on the efficient operation of an HF/DF chemical laser initiated by a low-impedance Blumlein discharge. Some combinations of 0.33 and 0.66-Ω flat-plate Blumlein lines with simple discharge chambers of various active volumes were investigated. For an SF6/H2mixture, an HF laser gave a maximum efficiency of 6.3 percent, and 5 J/1 was extracted. Substitution of D2for H2gave a DF laser output energy as high as 80 percent of the HF chemical laser output.     

Effect of clay modifiers on the morphology and physical properties of thermoplastic polyurethane/clay nanocomposites

Thermoplastic polyurethanes (TPUs)/clay nanocomposites were prepared via melt processing using the ester type and the ether type TPUs and three differently modified organoclays (denoted as C30B, C25A and C15A) as well as pristine montmorillonite (PM). XRD and TEM results showed that the addition of C30B with hydroxyl group led to the nearly exfoliated structures in both TPUs. In the case of C25A and C15A clays, partially intercalated nanocomposites were obtained in both TPUs, where C25A showed better dispersion than C15A. Natural clay (PM) was not effectively dispersed in both TPUs. The tensile properties of nanocomposites with C30B were better than ones with the other clays. Higher tensile properties were obtained for ester type TPU than ether type TPU nanocomposites with all clays tested. Although the improvement in tensile properties decreased after the second extrusion of the nanocomposites, properties of the nanocomposite after first melt processing were still good enough for practical applications. Morphological changes induced by the addition of clays were analyzed using FTIR, DSC and rheological test results. Some clays were observed to cause demixing of hard and soft segments in the nanocomposites and location of clays in either soft segment or hard segment domains was also studied.     

A Fully Synthesizable Bluetooth Baseband Module for a System‐on‐a‐Chip

Bluetooth is a specification for short‐range wireless communication using the 2.4 GHz ISM band. It emphasizes low complexity, low power, and low cost. This paper describes an area‐efficient digital baseband module for wireless technology. For area‐efficiency, we carefully consider hardware and software partitioning. We implement complex control tasks of the Bluetooth baseband layer protocols in software running on an embedded microcontroller. Hardware‐efficient functions, such as low‐level bitstream link control; host controller interfaces (HCIs), such as universal asynchronous receiver transmitter (UART) and universal serial bus (USB) interfaces; and audio Codec are performed by dedicated hardware blocks. Furthermore, we eliminate FIFOs for data buffering between hardware functional units. The design is done using fully synthesizable Verilog HDL to enhance the portability between process technologies so that our module can be easily integrated as an intellectual property core on system‐on‐a‐chip (SoC) ASICs. A field programmable gate array (FPGA) prototype of this module was tested for functional verification and realtime operation of file and bitstream transfers between PCs. The module was fabricated in a 0.25‐µm CMOS technology, the core size of which was only 2.79 mm×2.80 mm.     

Spatially adaptive high-resolution image reconstruction of DCT-based compressed images

The problem of recovering a high-resolution image from a sequence of low-resolution DCT-based compressed observations is considered in this paper. The introduction of compression complicates the recovery problem. We analyze the DCT quantization noise and propose to model it in the spatial domain as a colored Gaussian process. This allows us to estimate the quantization noise at low bit-rates without explicit knowledge of the original image frame, and we propose a method that simultaneously estimates the quantization noise along with the high-resolution data. We also incorporate a nonstationary image prior model to address blocking and ringing artifacts while still preserving edges. To facilitate the simultaneous estimate, we employ a regularization functional to determine the regularization parameter without any prior knowledge of the reconstruction procedure. The smoothing functional to be minimized is then formulated to have a global minimizer in spite of its nonlinearity by enforcing convergence and convexity requirements. Experiments illustrate the benefit of the proposed method when compared to traditional high-resolution image reconstruction methods. Quantitative and qualitative comparisons are provided.     

Adaptive mode decision for H.264 encoder

An adaptive mode decision algorithm is presented, with rate-distortion optimisation that reduces the complexity of the H.264 encoder without loss of image quality and compression ratio. The proposed algorithm uses the property of an all-zero coefficients block that is produced by quantisation and coefficient thresholding to effectively skip unnecessary modes. Experimental results show that the speed of the adaptive mode decision algorithm is two times faster than the full-mode decision algorithm of the JM72 reference encoder, without any coding loss.     

Hydrodenitrogenation reaction of quinoline with nascent hydrogen generated from water gas shift reaction

The HDN of quinoline was investigated for the purpose of utilizing the hydrogen which could be generated from the water gas shift reaction (WGSR). The optimum concentration of hydrogen were produced under 1.5 of water to carbon monoxide mole ratio and 6 hr^-1 of space velocity at 390°C of temperature during WGSR over Co-Mo/γ-Al₂O₃ catalyst. The HDN reactions were compared by using the pure hydrogen and the nascent hydrogen which was produced by a WGSR. The pure hydrogen gave much higher activity in the overall HDN reaction than the nascent hydrogen. However, kinetic study on the hydrogenation, hydrogenolysis and cracking reaction steps showed that only at the cracking reaction step the nascent hydrogen gave the superiority to the pure hydrogen. This inferiority of the nascent hydrogen in overall HDN reaction could be resulted from the negative effect of water which should be accompanied during WGSR. The conversion of the HDN reaction was maximized at the water pressure of 150 kpa.     

Strategic allocation of inspection stations for a flow assembly line: a hybrid procedure

A hybrid method is presented for the design of inspection stations in serial production systems. The hybrid method combines a constrained bottleneck shortest path algorithm and discrete event simulation. The network method determines the allocation of the inspection stations and the simulation helps the decision maker estimate accurately the possible outcome of the allocation. A computational study with the method is performed based on a practical problem. Other aspects related to the application of the method to real problems are also discussed.