Search Results (4)

We propose a miniaturized quad-band filter (QBF), designed using substrate-integrated coaxial cavities (SICCs). The employed SICC structure consists of two vertically stacked substrates with a large circular patch embedded in between. The embedded patch is segmented unevenly into four pieces, which are shorted to the cavity’s bottom wall through one or two blind vias. This SICC structure exhibits four independently controlled resonances with frequencies much lower than the frequency of its conventional SIW cavity counterpart, thus achieving size reduction. A sample quad-band filter is designed and fabricated for experimental measurement. Reasonably good agreement between measured and simulated data is observed. Full article

In order to ensure the correct behaviors and that bugs have not entered the design, equivalence checking technology plays an important role in VLSI design. In this paper, we propose a new template-based, semi-formal equivalence checking method for C-based system design and Register Transfer Level (RTL)/netlist implementation design, whose internal structures can be very different. Staring with a C-based description as a specification, we first randomly generate a set of templates. Each template has one or a small number of missing sentences based on the original C description. Many sets of mutants can be represented by these templates, using symbolic constants, variables, and operators. The process of finding those missing portions can be formulated as a Quantified Boolean Formula (QBF) problem. Then, based on the counter-example guided method, by simulating only the implementation, the templates can be refined. Since the templates are generated from the original C description, their structures are very similar to each other. With the original C description as a specification, we can simulate or formally check the equivalence between the refined template and the original C description, thereby indirectly achieving the equivalence checking of the C-based systems design and RTL/netlist implementation design. The experimental results on several practical examples demonstrate the effectiveness of the proposed method. Full article

Analytical channel design tools have not advanced appreciably in the last decades, and continue to produce designs based upon a single representative discharge that may not lead to overall sediment continuity. It is beneficial for designers to know when a simplified design may be problematic and to efficiently produce alternative designs that approximate sediment balance over the entire flow regime. The Capacity/Supply Ratio (CSR) approach—an extension of the Copeland method of analytical channel design for sand channels—balances the sediment transport capacity of a design reach with the sediment supply of a stable upstream reach over the entire flow duration curve (FDC) rather than just a single discharge. Although CSR has a stronger physical basis than previous analytical channel design approaches, it has not been adopted in practice because it can be a cumbersome and time-consuming iterative analysis without the use of software. We investigate eighteen sand-bed rivers in a comparison of designs based on the CSR approach and five single-discharge metrics: the effective discharge (Q_eff) or discharge that transports the most sediment over time; the 1.5-year recurrence interval discharge (Q_1.5); the bankfull discharge (Q_bf); and the discharges associated with 50th (Q_s50) and 75th (Q_s75) percentiles of the cumulative sediment yield curve. To facilitate this analysis, we developed a novel design tool using the Visual Basic for Applications (VBA) programming language in Excel^® to produce stable channel slope/width combinations based on the CSR methodology for both sand- and gravel-bed streams. The CSR Stable Channel Design Tool’s (CSR Tool) code structure was based on Copeland’s method in SAM and HEC-RAS (Hydrologic Engineering Center’s River Analysis System) and was tested with a single discharge to verify outputs. The Q_s50 and Q_s75 single-discharge designs match the CSR output most closely, followed by the Q_bf, Q_eff, and Q_1.5. The Q_eff proved to be the most inconsistent design metric because it can be highly dependent on the binning procedure used in the effectiveness analysis. Furthermore, we found that the more rigorous physical basis of the CSR analysis is potentially most important in designing “labile” channels with highly erodible substrate, high perennial flow “flashiness”, low width-to-depth ratio, and high incoming sediment load. The CSR Tool provides a resource for river restoration practitioners to efficiently utilize design techniques that can promote sediment balance in dynamic fluvial systems. Full article

In a Software Product Line (SPL), the central notion of implementability provides the requisite connection between specifications and their implementations, leading to the definition of products. While it appears to be a simple extension of the traceability relation between components and features, it involves several subtle issues that were overlooked in the existing literature. In this paper, we have introduced a precise and formal definition of implementability over a fairly expressive traceability relation. The consequent definition of products in the given SPL naturally entails a set of useful analysis problems that are either refinements of known problems or are completely novel. We also propose a new approach to solve these analysis problems by encoding them as Quantified Boolean Formulae (QBF) and solving them through Quantified Satisfiability (QSAT) solvers. QBF can represent more complex analysis operations, which cannot be represented by using propositional formulae. The methodology scales much better than the SAT-based solutions hinted in the literature and were demonstrated through a tool called SPLAnE (SPL Analysis Engine) on a large set of SPL models. Full article