Mechanized proofs of opacity: a comparison of two techniques

Software transactional memory (STM) provides programmers with a high-level programming abstraction for synchronization of parallel processes, allowing blocks of codes that execute in an interleaved manner to be treated as atomic blocks. This atomicity property is captured by a correctness criterion called opacity, which relates the behaviour of an STM implementation to those of a sequential atomic specification. In this paper, we prove opacity of a recently proposed STM implementation: the Transactional Mutex Lock (TML) by Dalessandro et al. For this, we employ two different methods: the first method directly shows all histories of TML to be opaque (proof by induction), using a linearizability proof of TML as an assistance; the second method shows TML to be a refinement of an existing intermediate specification called TMS2 which is known to be opaque (proof by simulation). Both proofs are carried out within interactive provers, the first with KIV and the second with both Isabelle and KIV. This allows to compare not only the proof techniques in principle, but also their complexity in mechanization. It turns out that the second method, already leveraging an existing proof of opacity of TMS2, allows the proof to be decomposed into two independent proofs in the way that the linearizability proof does not.     

Isolierung und Identifizierung von Farbstoffen in Seifen

Isolation and Identification of Dyes in Soaps A method is described for isolation and identification of dyes in soaps. The principle depends on separation of the dyes with the help of various organic solvents or acids, adsorption on polyamide powder and identification through thin layer chromatography. The inorganic pigments are identified by classical analytical procedures.     

Butadiene rubbers: topological constraints and microscopic deformation by mechanical and small angle neutron scattering investigation

Summary Results of stress-strain measurements are reported for butadiene rubbers of varying crosslink density. The fluctuation of the effective tube diameter of the polymer networks was investigated under uniaxial elongation by mechanical measurements as well as by small angle neutron scattering (SANS) which probe the local orientation on a segmental scale. The effect of topological constraints on the microscopic deformation of the butadiene network chains is well described within a tube approach. For the first time, experiments at large deformations and for polydisperse sample are presented. Excellent agreement between the statistical mechanical model and the experimental results is obtained. Received: 20 November 2001 /Revised version: 5 March 2002/ Accepted: 5 March 2002     

Clearing the air on EU guidance projects for school buildings

ABSTRACT

Professionals engaged in the design of new or retrofit of existing school buildings currently struggle to find comprehensive guidelines for achieving healthy and energy-efficient school environments. Recently, two major and independent research projects aimed at improving indoor environmental quality and energy performance of school buildings in Europe have been completed: SINPHONIE and School of the Future. Their guidelines reflect the distinct priorities and limited scope of each project. This paper compares for the first time and, as far as possible, synthesizes these outputs to facilitate their use in practice and research. Overall, SINPHONIE is most useful in addressing indoor environmental quality of schools in terms of the physical, chemical and microbiological stressors that impact and potentially affect human health. It aims to influence the future development of policy and regulations. By contrast, School of the Future presents a broader design-oriented approach based on best practice in four European countries. For the most part they complement each other in their recommendations; however, this review highlights several areas that require further clarification and research including links between indoor environmental quality and cognitive performance, the consequent appropriate level for the designed ventilation rate, and the role of adaptive thermal comfort in schools.     

Material removal mechanism in ultrasonic-assisted grinding of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> by single-grain scratch test

Alumina is an advanced ceramic that is frequently used in high-performance applications. Grinding of alumina is usually associated with micro-cracks and deteriorated surface quality. Ultrasonic-assisted grinding has been introduced in several applications as a promising method to overcome these constraints. In order to get a deeper knowledge of the characteristics of material removal mechanisms in alumina during grinding with ultrasonic stimulation of the workpiece, single-grain scratch tests were performed and the theoretical and experimental kinematics of grain-workpiece engagement were investigated. It was shown that in the real contact conditions, interrupted contact conditions happen, which is analogous to the theoretical model. The measured workpiece resonance frequency and mode shape were very close to the design conditions. The investigations show that the superposition of ultrasonic vibration into the grinding process increases the material removal of each grain. This result fully correlates with the presented theoretical analysis. Additionally, it was found that the impact action of ultrasonic-assisted grinding induces chipping around the produced scratch.     

Isotopenhydrologische Methoden (2H, 18O) zur Bestimmung der Grundwasserneubildung in Trockengebieten: Potenzial und Grenzen

Grundwasser - Die Quantifizierung der Grundwasserneubildung in Trockengebieten stellt aufgrund klimatischer Gegebenheiten, mächtiger ungesättigter Zonen sowie hochangepasster Vegetation...     

Segmental mobility in poly(isoprene) rubber studied by deuterium-carbon NMR correlation spectroscopy

Summary A HMQC based deuterium-carbon correlation method is used for the first time to study the segmental mobility in a fully deuterated poly(isoprene) (PI) rubber network. The isotropic J _CD couplings can be utilized for polarization transfer between ²H and ¹³C spins in a mobile solid polymer. This makes it possible to correlate the ²H resonances with the ¹³C chemical shifts of the attached carbon in a two-dimensional (2D) experiment, and thus allow the extraction of the individual ²H signals. The experimental data obtained from the 2D correlation spectrum indicates differences in the segmental mobility of the C-D vectors in perdeuterated PI. The conclusions are fully consistent with ²H and ¹³C T ₁ relaxation data. The results shown in this paper demonstrate the potential of ²H-¹³C NMR correlation spectroscopy in solid systems which produce overlapped 1D ²H spectra. Received: 11 December 2000/Revised version: 1 March 2001/Accepted: 1 March 2001     

Integrating Owicki–Gries for C11-Style Memory Models into Isabelle/HOL

Journal of Automated Reasoning - Weak memory presents a new challenge for program verification and has resulted in the development of a variety of specialised logics. For C11-style memory models,...