Model-based software synthesis

The knowledge-representation and compilation techniques used in a model-based, automatic software synthesis environment are discussed. The environment was used to build Caddmus, a system with more than 250 cooperating processes. The real-time execution environment automatically generates a macro-dataflow computation from declarative models. Central to the approach is the Multigraph Architecture, which provides the framework for model-based synthesis in real-time, parallel-computing environments. Application of Caddmus to analysis of all data related to testing new and redesigned turbine engines is described     

Synthesis of poly(4-methylstyrene)- graft-poly(ethylene oxide)s and application as polymeric dispersant in coal-water mixture

Poly(4-methylstyrene)-graft-poly(ethylene oxide)s were prepared via polymerisation of ethylene oxide on to poly(4-methylstyrene)s functionalised with hydroxyl groups. In this way, many ‘comb-like’ polymers having different hydrophobic backbone length, hydrophilic branch length and frequency of branches were synthesised. These polymers were tested as dispersants in coal-water mixtures in order to correlate the dispersing properties of this class of polymers with the investigated parameters.     

Three cases of dermatomyositis erroneously diagnosed as "chronic fatigue syndrome"

Dyspnea and cyanosis are common presenting manifestations of cardiopulmonary disease. When these findings occur in a cigarette smoker with an apparent pulmonary mass on chest radiograph, the differential diagnosis rapidly narrows to a short list of possibilities that include pulmonary neoplasm, pulmonary infection and pulmonary infarction. Pulmonary hypertension with pulmonary arterial enlargement and hypoxia secondary to alveolar hypoventilation should also, however, be included as a diagnostic possibility in the appropriate setting because the evaluation and treatment of this entity may differ markedly.     

Robust channel prediction technique for decision directed RAKEreceivers

The authors describe a robust channel prediction technique for a direct sequence spread spectrum (DS-SS) system in a fast fading environment. Coherent diversity reception is employed for improved performance. To estimate the channel response, an FIR type linear prediction filter is employed for each RAKE tap. The stability of the decision directed receiver is achieved through differential encoding of the data bits. It is demonstrated through simulations that the performance of the proposed decision directed receiver is better than a receiver which relies on a pilot signal     

Linear predictive receivers for fading channels

The authors discuss maximum likelihood sequence detection (MLSD) based on prediction techniques for linearly modulated digital signals transmitted over fading channels. Efficient implementations of the sequence detector are investigated and a general formulation for computing the prediction coefficients is derived. Furthermore, the equivalence of different existing prediction-based receivers is shown     

In situ13C NMR study of tert-butanol interaction with moderately concentrated sulfuric acid

An in situ NMR study of tert-butanol dehydration in 95 and 85% sulfuric acid did not indicate the formation of tert-butyl cations as active reaction intermediates. Instead, only NMR lines from oxonium ions under the condition of fast exchange with water and the acid were observed. It is most likely that, in the concentrated acid, the active intermediates of this reaction are represented by tert-butyl sulfuric ester which probably is a precursor of invisible tert-butyl carbenium ions representing short-lived excited or transition states.     

Conversion of saturated cyclic and noncyclic amines over a sulphided NiMo/Al2O3 catalyst : mechanisms of carbon - nitrogen bond cleavage

The objective of this work was to provide comprehensive hypotheses concerning the mechanisms operative in the C---N bond cleavages occurring during the catalytic conversion of amines over a conventional hydrotreating catalyst, so as to account for experimental observations and to help in developing better hydrodenitrogenation catalysts. The approach consists in a study of the relations between the structure and the reactivity of two series of amines with different numbers of hydrogen atoms on the carbon atoms in the and β positions with respect to their nitrogen atom. It was found that the hydrogen atoms on the carbon atom in the β position are involved in the formation of hydrocarbons, and that neither the hydrogen atoms on the carbons in the position nor those on the carbon atoms in the β position are involved in the formation of condensation products. On the basis of these results, two mechanisms are proposed for the formation of the different reaction products.     

Laboratory and analytical studies of the effects of multipulselightning current on metal oxide arresters

Multiple stroke lightning ground flashes can impose surges of exceptional severity on the arresters used to protect exposed distribution system equipment. This paper reports laboratory and analytical studies of the effects of representative multiple impulse currents on zinc-oxide surge arresters of distribution class. The results indicate that sextuple 8/20 μs currents can cause damage to arresters not evident with standard lightning current tests and so are worthy of inclusion in testing Standards