Counterexample-guided abstraction refinement for symmetric concurrent programs

Predicate abstraction and counterexample-guided abstraction refinement (CEGAR) have enabled finite-state model checking of software written in mainstream programming languages. This combination of techniques has been successful in analysing system-level sequential C code. In contrast, there is little evidence of fruitful applications of CEGAR to shared-variable concurrent software. We attribute this gap to the lack of abstraction strategies that permit a scalable analysis of the resulting multi-threaded Boolean programs. The goal of this paper is to close this gap. We have developed a symmetry-aware CEGAR technique: it takes into account the replicated structure of programs that consist of many threads executing the same procedure, and generates a Boolean program template whose multi-threaded execution soundly overapproximates the original concurrent program. State explosion during model checking parallel instantiations of this template can now be absorbed by exploiting symmetry. We have implemented our method in a tool, SymmPa, and demonstrate its superior performance over alternative approaches on a range of synchronisation programs.     

Analysis of specific heat anomalies of high-Tc superconductors based on a two-carrier high-Tc superconductor model

We investigate the specific heat properties of a high-T _c superconductor model, the two-carrier model which includes an electron-phonon interaction driven by lattice defects such as oxygen deficiencies in the otherwise conventional BCS superconductor. The normal state is identified as a two-carrier model system which is composed of two groups of charge carriers: the normal and the renormalized Bloch carriers. An enhanced normal-state electronic specific heat is obtained, and there is good agreement between theoretical predictions about the specific heat anomalies at and aboveT _c and experimental data.     

A transport-level proxy for secure multimedia streams

To provide a secure traversal service, firewalls need more than static packet filtering and application-level proxies. SOCKS (Secure sOCKets) is an application-independent transport-level proxy that offers user-level authentification and data encryption. An extended SOCKS UDP (user datagram protocol) binding model with appropriate socket calls is proposed to provide complete support for UDP-based multimedia streaming applications     

Integrated process planning and scheduling by an agent-based ant colony optimization

This paper presents an ant colony optimization (ACO) algorithm in an agent-based system to integrate process planning and shopfloor scheduling (IPPS). The search-based algorithm which aims to obtain optimal solutions by an autocatalytic process is incorporated into an established multi-agent system (MAS) platform, with advantages of flexible system architectures and responsive fault tolerance. Artificial ants are implemented as software agents. A graph-based solution method is proposed with the objective of minimizing makespan. Simulation studies have been established to evaluate the performance of the ant approach. The experimental results indicate that the ACO algorithm can effectively solve the IPPS problems and the agent-based implementation can provide a distributive computation of the algorithm.     

Fuzzy modelling and simulation for aggregate production planning

The market demands and financial constraints in medium- to long-term production planning are often subject to uncertainties. As an extension of the author's previous paper, this paper focuses on a formulation and simulation analysis for multi-product aggregate production-planning problems with fuzzy demands and fuzzy capacities. The fuzzy production–inventory balance equation is formulated as a soft equation and can be interpreted as the possibility level of meeting the market demands, which is more meaningful and accepted by the practitioner than the previous one. With this interpretation, a fuzzy multi-product aggregate production-planning model is transformed into a parametric programming model. A simulation of a practical instance is conducted to illustrate the model and demonstrate the performance and effect of various parameters on the optimal aggregate production plan. The proposed formulation and simulation analysis can help the decision-maker make a reasonable and preferred aggregate plan to guarantee feasibility of the downstream family disaggregation plans.     

A Java-based parallel platform for the implementation of evolutionary computation for engineering applications

As computers continually improve in performance and decrease in manufacturing cost, distributed systems consisting of multiple computers implemented as parallel computation platforms have become viable for engineering applications which demand intensive computation power. This paper proposes an extended version of a previously developed low cost parallel computation platform called para worker. The system is based on a cluster structure which is a form of a distributed system. The new system is termed para worker 2 which differentiates it from the earlier system. The new proposed system adds enhanced features of improved dynamic object reallocation, adaptive consistency protocols, and location transparency. Performance of the para worker 2 has proven to be superior to the para worker. Testing was based on an execution of Genetic Algorithm to solve the Economic Dispatch problem in Power Engineering. The proposal is particularly useful for the implementation and execution of computational intelligence techniques such as evolutionary computing for engineering applications.     

Object‐oriented classification for urban land cover mapping with ASTER imagery

This document demonstrates the potential of using an object‐oriented approach to map urban land cover. One objective of this work was to test the ability of the object‐oriented classification in the generation of urban land cover maps. Anotehr was to produce an updated land cover map for the city of Beijing from Advanced Spaceborne Thermal Emission and Reflecton Radiometer (ASTER) data, with an evaluation of its accuracy.     

Transmission electron microscopy at 20 kV for imaging and spectroscopy

The electron optical performance of a transmission electron microscope (TEM) is characterized for direct spatial imaging and spectroscopy using electrons with energies as low as 20 keV. The highly stable instrument is equipped with an electrostatic monochromator and a C_S-corrector. At 20 kV it shows high image contrast even for single-layer graphene with a lattice transfer of 213 pm (tilted illumination). For 4 nm thick Si, the 200 reflections (271.5 pm) were directly transferred (axial illumination). We show at 20 kV that radiation-sensitive fullerenes (C₆₀) within a carbon nanotube container withstand an about two orders of magnitude higher electron dose than at 80 kV. In spectroscopy mode, the monochromated low-energy electron beam enables the acquisition of EELS spectra up to very high energy losses with exceptionally low background noise. Using Si and Ge, we show that 20 kV TEM allows the determination of dielectric properties and narrow band gaps, which were not accessible by TEM so far. These very first results demonstrate that low kV TEM is an exciting new tool for determination of structural and electronic properties of different types of nano-materials.     

Butenolides in small ermine moths,Yponomeuta spp. (Lepidoptera: Yponomeutidae), and spindle-tree,Euonymus europaeus (Celastraceae)

A new butenolide, isosiphonodin [3-hydroxymethyl-2(5H)-furanone], along with a trace of siphonodin [4-hydroxymethyl-2(5H)-furanone], was isolated from fifth-instar larvae of the small ermine mothYponomeuta cagnagellus. Leaves of its host plant spindle-tree,Euonymus europaeus, were found to contain the same two butenolides with siphonodin being present as the major compound. TLC showed that isosiphonodin was also present in larvae or pupae of six other small ermine moths which did not feed on spindle-tree. InY. cagnagellus butenolides might be plant derived, while isosiphonodin in the other investigated small ermine moths is probably synthesized by the insect. The possible role of butenolides in the chemical defense of small ermine moths is discussed.     

Indentation plasticity and fracture of Si3N4 ceramic alloys

The response of a series of one- and two-phase-Si₃N₄ ceramic alloy surfaces to sharp diamond microindentation has been examined by optical and electron microscopy. The microhardness (H), which obeys the load-independent relationH=P/a ² (whereP anda are load and indent size, respectively) is nearly constant within the alloy series, indicating a retention of high covalency at large (Al and O) substitution levels. Indentation results from severe localized plasticity which is characterized by the operation of the dominant dislocation Burgers vectora[0 0 0 1] in the hexagonal lattice. The severe anisotropy in plasticity induces grain-boundary microcracking which is believed to nucleate median cracks which propagate away from the plastic zone on symmetry planes beneath the indenter. The relation between load, median crack size (c) and fracture toughness (K _c) is of the form,K _c=constant (P/c ^3/2) predicted theoretically. Values ofK _c rank correctly with those from notched-beam measurements, but there is uncertainty about the value of the constant.