Capacity planning in job-shop environment

Presented here is a computerized capacity planning system for the IBM Microcomputer family. The system maintains the profile of the job shop in a data base along with data pertinent to various products that can be manufactured in the shop. Projected orders for the planning period are input to the system with their associated quantities and delivery dates. The system uses the forward and backward loading rules in generating capacity loading scenarios. User selects the best course of action which may satisfy delivery dates subject to the limitations of the work centers. Efficiency figures are provided to aid the user in his/her decision.     

Model concrete beam-column joints subjected to cyclic loading at two rates

Small-scale models of reinforced concrete beam-column joint were subjected to large cyclic displacements at two rates: 2.5×10⁻³ and 1.0 Hz. To assess damage, free-vibration tests were conducted. The reliability of the modelling techniques was established by comparison of the results for the slower rate with those obtained from the full-scale tests on prototype. The higher rate of loading caused a greater damage than that at the lower rate. This was evidenced by the measurements of the energy absorbed in the hysteresis loops, equivalent damping, and the stiffness and damping obtained from the free-vibration test. The relatively greater extent of damage appears to result from the different bond behaviour at different rates of loading.     

Layout-Specific Circuit Evaluation in 3-D Integrated Circuits

In this paper, we describe a comprehensive layout methodology for bonded three-dimensional integrated circuits (3D ICs). In bonded 3D integration technology, parts of a circuit are fabricated on different wafers, and then, the wafers are bonded with a glue layer of Cu or polymer based adhesive. Using our layout methodology, designers can layout such 3D circuits with necessary information on inter-wafer via/contact and orientation of each wafer embedded in the layout. We have implemented the layout methodology in 3DMagic. Availability of 3DMagic has led to interesting research with a wide range of layout-specific circuit evaluation, from performance comparison of 2D and 3D circuits to layout-specific reliability analyses in 3D circuits. Using 3DMagic, researchers have designed and simulated an 8-bit encryption processor mapped into 2D and 3D FPGA layouts. Moreover, the layout methodology is an essential element of our ongoing research for the framework of a novel Reliability Computer Aided Design tool, ERNI-3D.     

Effect of thermal treatment on ZnO substrate for epitaxial growth

ZnO is a highly efficient photon emitter, and has optical and piezoelectric properties that are attractive for a variety of applications in sensors and potentially optoelectronic devices such as emitters. Due to its identical stacking order and close lattice match to GaN, it is also being developed as a substrate material for GaN epitaxy. However, the surface finish of the ZnO is such that much of the damage induced by sawing and follow up mechanical polishing remains. We developed a thermal treatment method to eliminate surface damage on the 0 face of ZnO (0 0 0 1) to prepare it for epitaxial growth. Atomic force microscopy images of ZnO (0 0 0 1) annealed at 1050 °C for 3 h etc. show that residual scratches from mechanical polishing are removed and atomically flat, terrace-like surfaces are attained. In addition, low-temperature photoluminescence and high-resolution X-ray diffraction measurements have been employed to investigate the effect of annealing on ZnO substrates.     

Lowpass and bandpass transadmittance filter using operational amplifier pole

A new topology simultaneously implementing lowpass (LP) and bandpass (BP) transadmittance filtering signals using a single operational amplifier (OA), one capacitor, and two resistors is presented. The input impedance is very high which is essential for cascading without employment of buffers. The circuit uses absolute minimum number of active and passive components. The filter employs pole-model of OA and as such has acquired suitability for extended frequency operation. The circuit permits separate adjustment of natural frequency (ω₀) and quality factor (Q) in an orthogonal manner. The circuit has low sensitivity figures unlike the reported single amplifier biquads. The PSPICE simulation results are included.     

Efficient dissemination of personalized information using content-based multicast

There has been a surge of interest in the delivery of personalized information to users (e.g., personalized stocks or travel information), particularly as mobile users with limited terminal device capabilities increasingly desire updated and targeted information in real time. When the number of information recipients is large and there is sufficient commonality in their interests, as is often the case, IP multicast is an efficient way of delivering the information. However, IP multicast services do not consider the structure and semantics of the information in the multicast process. We propose the use of Content-Based Multicast (CBM) where extra content filtering is performed at the interior nodes of the IP multicast tree; this will reduce network bandwidth usage and delivery delay, as well as the computation required at the sources and sinks. We evaluate the situations in which CBM is advantageous. The benefits of CBM depend critically upon how well filters are placed at interior nodes of the IP multicast tree and the costs depend upon those introduced by filters themselves. Further, we consider the benefits of allowing the filters to be mobile so as to respond to user mobility or changes in user interests and the corresponding costs of filter mobility. The criterion that we consider is the total network bandwidth utilization. For this criterion, we develop an optimal filter placement algorithm, as well as a heuristic that executes faster than the optimal algorithm. We evaluate the algorithms by means of simulation experiments. Our results indicate that filters can be effective in substantially reducing bandwidth. We also find filter mobility is worthwhile if there is marked large-scale user mobility. We conclude with suggestions for further work.     

Analytical modeling of imperfect bond between coated fibers and matrix material

The present study is intended to find the stress intensity factors (SIF) and strain energy release rates (SERR) at the tips of an interface crack in a non-homogeneous medium. The boundary-value problem governing a three-phase concentric cylinders model is used to analyze annular interfacial crack problems with Love's strain functions. The complex form of a singular integral equation of second kind is formulated using Bessel's functions in Fourier domain. Stress intensity factors (SIF) and total strain energy release rates (SERR) are calculated using Jacoby polynomials. For validity of the equations of Stress Intensity Factors, the Singular Integral Equation (SIE) of a three concentric cylinders model is reduced to the SIE for a two concentric cylinders model and results are compared with previous results of Erdogan.