Image sharpening in the JPEG domain

We present a new technique for sharpening compressed images in the discrete-cosine-transform domain. For images compressed using the JPEG standard, image sharpening is achieved by suitably scaling each element of the encoding quantization table to enhance the high-frequency characteristics of the image. The modified version of the encoding table is then transmitted in lieu of the original. Experimental results with scanned images show improved text and image quality with no additional computation cost and without affecting compressibility.     

Dynamic behaviour of protective covers in machine tools

The durability of protective covers in high dynamic machine tools is no longer acceptable. Due to high velocities and acceleration, the structural components of the bellow, the crossbar mechanism for example, do not withstand the occurring forces. The following article analyses the forces which affect a protective cover occurring due to feed motion of the axis. The requirements of protective covers are defined in order to derive the cycles for the dynamic tests. The measured variables recorded during the trials are analyzed and associated to the structural components of the bellow. This research is supported by the Arbeitsgemeinschaft industrieller Forschungsvereinigungen “Otto von Guericke” e. V.     

LED背光照明系统的设计方案选项利弊分析

LED正成为中小型彩色显示器背光照明应用的主流器件。LED的选择是决定显示子系统设计最佳性价比的关键因素。此外，LED驱动IC，尤其是最新的产品，能与较低成本的LED协同工作，透过多种方法提升现有LED的性能。除亮度控制外，这些驱动IC还能实现精确的亮度匹配，或允许使用一系列具备不同VF特性的LED。     

Modeling of monothermal ammonia-hydrogen chemical exchange column using a non-equilibrium model

The monothermal NH₃-H₂ chemical exchange process, operating at low temperature and high pressures, is simulated by considering non-ideal behavior of both phases and multicomponent mass transfer at the gas-liquid interface. The hydrodynamics of special ejector tube tray is incorporated in the simulation and validated against actual operating plant data. The column operation is simulated with respect to process parameters to determine the optimum operating window for the column. A higher temperature operation near 270 K has been suggested for better performance of the column. The multicomponent effect is not prominent in the first tower operated at 248 K and 20 MPa but is significant in the second tower operated at 270 K and 10 MPa. In the overall operation, the multicomponent effect cannot be neglected.     

Isolation improvement in dual-band astroid shaped MIMO DRA for LTE and ISM applications

This article presents the design of a novel astroid shaped dielectric resonator antenna (DRA) constructed from PTFE Teflon material with a dielectric constant of ε_r = 2.1 and a loss tangent tan δ = 0.0002 on an FR4 grounded substrate for LTE and ISM band applications. Inverted Omega ?-shaped feed along with asymmetric E-shaped dual metallic strips in the partial ground is used to obtain dual-band characteristics. A light weight, cost-effective plastic material is used to design the antenna. An isolation of 26.5 dB and 24.6 dB is achieved in the two frequency bands 1.8 GHz and 2.4 GHz respectively by modifying the ground plane. Metallic strips and stubs in the ground are used to enhance the isolation in the proposed MIMO system. The obtained impedance bandwidths in both the bands are 14.5% and 13%. The performance of the MIMO system is characterized by the envelope correlation coefficient and diversity gain. Good agreement is found between simulated and measured results.     

Formulation of Rosuvastatin-Loaded Self-Nanoemulsifying Drug Delivery System Using Box-Behnken Design

The objectives of present study were to understand the effect of formulation variables of self-nanoemulsifying drug delivery system (SNEDDS) of rosuvastatin (RSV). Box-Behnken design in conjunction with desirability function was used to evaluate the main effect, interaction effect and quadratic effect of independent formulation variables that included amounts of Acconon 200 E6, Cremophor RH40, and Lipoxol 300. For a better understanding of the selected variables for the optimal performance of RSV SNEDDS, the models were presented as three-dimensional response surface graphs. A fresh batch of optimized formulations and were prepared with optimized levels of the independent variables to yield dependent variables (Y1–Y6) values that were remarkably close to the predicted values. Drug excipient compatibility studies using the Fourier transform infrared spectroscopy, differential scanning calorimeter and x-ray diffraction indicated the absence of any incompatibility between RSV and selected excipients. The transmission electron microscopy of selected optimized SNEDDS of RSV showed the spherical shape of globules with no signs of coalescence and precipitation of RSV. The study demonstrates the use of Box-Behnken design for the preparation of RSV SNEDDS. The desirable goals can be obtained by systematic formulation approach in minimum possible time.     

In-plant material buffer sizes for pull system and level-material-shipping environments in the automotive industry

Traditionally automotive assembly plants operate with at least two weeks of frozen vehicle orders enabling them to calculate the amount of material needed for the next two weeks. Implementing a pull system between the plant and its customers, and level-material-shipping between the plant and its suppliers, changes the amount of material buffer needed within the assembly plant. The pull system eliminates the frozen vehicle-order schedule, without which plants cannot calculate the material needed, but must use inventory to buffer the line from random demand. Level-material-shipping, a just-in-time principle that provides suppliers with a constant shipping schedule, forces plants to use material inventory to buffer the line from un-level demand for parts resulting from un-level production or an un-level model mix. We model these effects to derive formulas for the buffer needed to provide a given service level in the face of demand variability, un-level production, and un-level model-mix.     

Optimal replacement policy for a repairable system with multiple vacations and imperfect fault coverage

The present investigation deals with the reliability analysis of a repairable system consisting of single repairman who can take multiple vacations. The system failure may occur due to two types of faults termed as major and minor. When the system has failed due to minor faults, it is perfectly recovered by the repairman. If the system failure is due to major faults, there are some recovery levels/procedures that recover the faults imperfectly with some probability. However, the system cannot be repaired in ‘as good as new’ condition. It is assumed that the repairman can perform some other tasks when either the system is idle or waiting for recovery from the faults. The life time of the system and vacation time of the repairman are assumed to be exponential distributed while the repair time follows the general distribution. By assuming the geometric process for the system working/vacation time, the supplementary variable technique and Laplace transforms approach are employed to derive the reliability indices of the system. We propose the replacement policy to maximize the expected profit after a long run time. The validity of the analytical results is justified by taking numerical illustrations.     

Nyquist plots,finite gain/phase margins & dissipativity

The relation between the small gain theorem and ‘infinite phase margin’ is classical; in this paper we formulate a novel supply rate, called the ‘not-out-of-phase’ supply rate, to first prove that ‘infinite gain margin’ (i.e. non-intersection of the Nyquist plot of a transfer function and the negative half of the real axis) is equivalent to dissipativity with respect to this supply rate. Capturing non-intersection of half-line makes the supply rate system-dependent: a novel feature unobserved in the supply rates considered in the literature so far.