Calculation of leak sizes in pressurised vessels and pipes according to the leak-before-break criterion

For the consideration of released mass flows and their effects within hazard studies, leakage areas need to be determined which are physically justifiable and which cannot be reasonably excluded. Applying the fracture mechanics the leak-before-break behaviour is verified by the calculation of the propagation of an initial material defect. Consequently, leakage areas of through-cracks are calculated to determine probable and maximum leakage areas. For this purpose, models for the calculation of leak sizes are compared and evaluated. Example calculations are stated for typical pressurised vessels and pipes of the chemical industry in order to check the present estimates of leakage areas. In addition, measures supporting the leak-before-break behaviour are outlined.     

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Spatiospectral transmission of a plane-mirror Fabry-Perot interferometer with nonuniform finite-size diffraction beam illuminations

The transmission of a plane-mirror Fabry-Perot (PFP) interferometer is theoretically modeled and investigated by treating the spatial and spectral features in a unified manner. A spatiospectral transfer function is formulated and utilized to describe the beam propagation and the multiple-beam interference occurring in an ideal one-dimensional strip PFP interferometer with no diffraction loss. The spatial-frequency filtration of a finite-size beam input not only determines the transmitted spatial beam profile but also plays a crucial role in affecting the overall spectral transmittance. The inherent deviations of the spectral transmittance from what we know as the standard Airy's formula are revealed in diverse aspects, including the less-than-unity peak transmittance, the displacement of a resonance peak frequency, and the asymmetric detuning profile. Our theoretical analysis extends to the misaligned PFP interferometers, such as the cases in which non-normal-incidence beams or wedge-aligned mirrors are used that could severely degrade the effective interferometer finesse.     

Reduction of stable differential–algebraic equation systems via projections and system identification

Most large-scale process models derived from first principles are represented by nonlinear differential–algebraic equation (DAE) systems. Since such models are often computationally too expensive for real-time control, techniques for model reduction of these systems need to be investigated. However, models of DAE type have received little attention in the literature on nonlinear model reduction. In order to address this, a new technique for reducing nonlinear DAE systems is presented in this work. This method reduces the order of the differential equations as well as the number and complexity of the algebraic equations. Additionally, the algebraic equations of the resulting system can be replaced by an explicit expression for the algebraic variables such as a feedforward neural network. This last property is important insofar as the reduced model does not require a DAE solver for its solution but system trajectories can instead be computed with regular ODE solvers. This technique is illustrated with a case study where responses of several different reduced-order models of a distillation column with 32 differential equations and 32 algebraic equations are compared.     

Advanced photospacers with elastic recovery

A new series of photospacers has been prepared with different types of crosslinkers to improve elastic recovery. Afunctional crosslinker with six reactive groups demonstrates the best elastic recovery. As the quantity of crosslinker is increased, the elastic recovery also increases, probably due to an increase in the crosslinking density. The use of ADMS EPS® results in high resolution, good uniformity, and high production yield in the liquid‐crystal‐display (LCD) process. Especially, EPS® improves and solves problems such as viewing angle, crosstalk, and dark spots.     

A new three-phase power-factor correction (PFC) scheme using twosingle-phase PFC modules

In this paper, a new three-phase power-factor correction (PFC) scheme is proposed using two single-phase PFC modules. In this approach, the "three" phase input is first transformed to "two" phase by means of a 0.14-pu-rated autotransformer. Two standard single-phase PFC modules are then employed to process the "two" phase power to DC output. Split inductors and diodes are employed to limit interaction between the two PFC stages. Due to cascade operation of two PFC stages, low-frequency (120 Hz) ripple in the DC-link capacitor is cancelled. Detailed analysis and simulation results are presented. A 220-V 1.5-kVA design example along with experimental results is shown     

Carrier-concentration dependence of velocity-field characteristics in ln0.53Ga0.47 as

The doping dependence of the velocity-field characteristic in InGaAs has been investigated by an analysis of measurements with transferred-electron devices. The electron peak velocity has been determined directly as a function of electron concentration and low-field mobility. The carrier-concentration dependence of the velocity-field characteristic has been deduced by comparing experimental and theoretical transient device behaviour. The experimental results support a theoretical approach for the velocity-field characteristic which has been proposed recently.     

Mathematical modeling of the reduction process of iron ore particles in two stages of twin-fluidized beds connected in series

A mathematical model is presented to describe the reduction process of iron ore particles in two stages of twin-fluidized beds (TFBs) connected in series: prereduction and final reduction stages. Main features of the model are the inclusion of particle degradation phenomenon to account for its effect on reduction of iron oxides and reduction kinetics for multiparticles having a wide size distribution. It was found that about 90 pct of overall particle degradation occurs in the prereduction stage mainly due to thermal stress and volume expansion. The reduction degree of particles larger than 1 mm decreased fast with increasing particle size in both the prereduction and final reduction stages. However, the particles sized between 0.2 and 1 mm showed mild increase in reduction degree, and steep increase for the fines smaller than 0.2 mm. The reduction degree was also gradually decreased with increasing the gas oxidation degree of feed gas in both the prereduction and final reduction stages. It was found that to obtain a desired reduction degree, it is of great importance to control the bed temperature in stage I rather than in stage II. The optimum range of residence time was 15 to 20 minutes in the prereduction stage and 30 to 35 minutes in the final reduction stage.