Layering Approach Research Articles

Study of Layering Procedures in Finite-Element Analysis of RC Flexural and Torsional Elements

A new postcracking formulation for concrete, along with both implicit and explicit layering procedures, is used in the analysis of reinforced-concrete (RC) flexural and torsional elements. The postcracking formulation accounts for tension stiffening in concrete along the rebar directions, compression softening in cracked concrete based on either stresses or strains, and aggregate interlock based on crack-confining normal stresses. Transverse shear stresses computed using the layering procedures are included in material model considerations that permit the development of inclined cracks through the RC cross section. Examples of a beam analyzed by both the layering techniques, a torsional element, and a column-slab connection region analyzed by the implicit layering procedure are presented here. The study highlights the primary advantages and disadvantages of each layering approach, identifying the class of problems where the application of either procedure is more suitable.

The effects of layering and encapsulation on software development cost and quality

Software engineers often espouse the importance of using abstraction and encapsulation in developing software components. They advocate the of new components on top of existing components, using only information about the functionality and interfaces provided by the existing components. This layering approach is in contrast to a direct implementation of new components, utilizing unencapsulated access to the representation data structures and code present in the existing components. By increasing the reuse of existing components, the layering approach intuitively should result in reduced development costs, and in increased quality for the new components. However, there is no empirical evidence that indicates whether the layering approach improves developer productivity or component quality. We discuss three controlled experiments designed to gather such empirical evidence. The results support the contention that layering significantly reduces the effort required to build new components. Furthermore, the quality of the components, in terms of the number of defects introduced during their development, is at least as good using the layered approach. Experiments such as these illustrate a number of interesting and important issues in statistical analysis. We discuss these issues because, in our experience, they are not well known to software engineers. >

Wide-band packet radio technology

Advances in signal processing and architectural design for high-performance packet radio are described. The scope of the work roughly encompasses the data-link and physical levels of standardized layered-network architectures. A hardware-function layering approach is used, including the purposeful design of an interface to provide a structured control environment for a demonstration packet radio. The advanced signal processing provides a robust, flexible data link to service demanding network environments, and uses 100-MHz-bandwidth surface-acoustic-wave (SAW) convolvers as large time-bandwidth product matched filters for communication with nonrepeating pseudonoise waveforms. The convolvers are combined with a binary-quantized postprocessor to implement a hybrid correlator which provides high processing gain for detection, demodulation, and ranging measurements. Data rates can be selected, in response to varying channel conditions, over a range from 1.45 Mbits/s down to 44 bits/s with an almost ideal tradeoff in processing gain for interference rejection and privacy ranging from 18 dB up to 61 dB. Future enhancements are proposed that will advance both the signal processing and the architecture.