Deterministic finite automata with recursive calls and DPDAs

We study deterministic finite automata (DFA) with recursive calls, that is, finite sequences of component DFAs that can call each other recursively. DFAs with recursive calls are akin to recursive state machines and unrestricted hierarchic state machines. We show that they are language equivalent to deterministic pushdown automata (DPDA).     

A layered algorithm for quantifier elimination from linear modular constraints

Linear equalities, disequalities and inequalities on fixed-width bit-vectors, collectively called linear modular constraints, form an important fragment of the theory of fixed-width bit-vectors. We present a practically efficient and bit-precise algorithm for quantifier elimination from conjunctions of linear modular constraints. Our algorithm uses a layered approach, whereby sound but incomplete and cheaper layers are invoked first, and expensive but complete layers are called only when required. We then extend this algorithm to work with arbitrary Boolean combinations of linear modular constraints as well. Experiments on an extensive set of benchmarks demonstrate that our techniques significantly outperform alternative quantifier elimination techniques based on bit-blasting and linear integer arithmetic.     

An alternative characterization of fuzzy complement functional

In this short note we propose a novel fuzzy complement functional. This functional is different from other functionals known in the literature. However, it turns out to be an alternative characterization of the well-known negation function. We sincerely thank the anonymous reviewer whose insightful suggestions have significantly improved the paper.     

RF/wireless interconnect for inter- and intra-chip communications

Recent studies showed that conventional approaches being used to solve problems imposed by hard-wired metal interconnects will eventually encounter fundamental limits and may impede the advance of future ultralarge-scale integrated circuits (ULSls). To surpass these fundamental limits, we introduce a novel RF/wireless interconnect concept for future inter- and intra-ULSI communications. Unlike the traditional “passive” metal interconnect, the “active” RF/wireless interconnect is based on low loss and dispersion-free microwave signal transmission, near-field capacitive coupling, and modem multiple-access algorithms. In this paper we address issues relevant to the signal channeling of the RF/wireless interconnect and discuss its advantages in speed, signal integrity, and channel reconfiguration. The electronic overhead required in the RF/wireless-interconnect system and its compatibility with the future ULSI and MCM (multi-chip-module) will be discussed as well     

A Proof of the Security of Quantum Key Distribution

We prove the security of theoretical quantum key distribution against the most general attacks which can be performed on the channel, by an eavesdropper who has unlimited computation abilities, and the full power allowed by the rules of classical and quantum physics. A key created that way can then be used to transmit secure messages such that their security is also unaffected in the future.     

Efficient algorithms for approximate time separation of events

Finding bounds on time separation of events is a fundamental problem in the verification and analysis of asynchronous and concurrent systems. Unfortunately, even for systems without repeated events or choice, computing exact bounds on time separation of events is an intractable problem when both min and max type timing constraints are present. In this paper, we describe a method for approximating min and max type constraints, and develop a polynomial-time algorithm for computing approximate time separation bounds in choice-free systems without repeated events. Next, we develop a pseudo-polynomial time technique for analysing a class of asynchronous systems in which events repeat over time. Unlike earlier works, our algorithms can analyse systems with both min and max type timing constraints efficiently. Although the computed bounds are conservative in the worst-case, experimental results indicate that they are fairly accurate in practice. We present formal proofs of correctness of our algorithms, and demonstrate their efficiency and accuracy by applying them to a suite of benchmarks. A complete asynchronous chip has been modelled and analysed using the proposed technique, revealing potential timing problems (already known to designers) in the datapath design.     

Role of environmental variables on the stress corrosion cracking of sensitized AISI type 304 stainless steel (SS304) in thiosulfate solutions

The stress corrosion cracking (SCC) behavior of sensitized AISI type 304 stainless steel (SS304) has been studied in dilute thiosulfate solutions as a function of thiosulfate concentrations and applied potentials. The susceptibility to SCC was observed to increase with thiosulfate concentrations and applied potentials. The addition of boric acid produced the reverse effect. A critical potential was found to exist, below which no SCC took place. Potential fluctuations, as recorded in the tests under open circuit conditions, appeared to be correlated with crack initiation and propagation during SCC. Current fluctuations observed in the controlled potential tests also gave indications of crack nucleation; however, at higher applied potentials such fluctuations were absent. The formation and presence of martensite in the specimens seemed to have a minor role in the overall SCC process. The aggressiveness of the thiosulfate concentration was also an important factor in determining the degree of susceptibility to SCC. The results obtained in the slow strain rate tests under open circuit as well as under potential-controlled conditions suggested a film ruptureanodic dissolution type of mechanism operative during SCC of sensitized SS304 in thiosulfate solutions.     

Sonographically guided intravascular biopsy of an intraluminal mass in the inferior vena cava

In a 48-year-old Japanese man there was an uncontrollable and recurrent bleeding from a gastric ulcer and laparoscopic surgery was done. Two cannulae were placed in the gastric cavity through the abdominal wall and suture ligation of the bleeding vessel at the posterior wall of the stomach was done under video-visual control with endoscopic guidance. The bleeding ceased, complications were nil, and he remains well. This article reports on surgery done to repair uncontrollable, recurrent bleeding from a gastric ulcer. Two cannulae were placed in the gastric cavity through the abdominal wall and suture of the vessel at the posterior wall of the stomach was done with videovisual control and endoscopic guidance. This approach is concluded to have supplied minimal-access surgery, cost effectiveness, early discharge, less pain, and doctor-patient satisfaction.