Expertise, domain-structure and expert system design: a case study in development control

Abstract: This paper outlines the approach taken and presents some early findings from a research project which aims to examine the potential of expert systems in British Development Control; it is a progress report more than an account of finished research. It follows the structure of the research project, dealing first with methodological issues, and then moving on to discuss the specific domain of application.     

Viscosity of ionomer gels

We study the viscosity behaviour of metal sulphonate- (or metal carboxylate-) containing ionomers in solution with non-polar solvents; at relatively low polymer concentration these ionomer solutions show an unusually large thickening behaviour, due to the association of the metallic groups. By regarding the ionomer system as a polymer solution with transient crosslinks, an expression is derived from the viscosity of the sulphonated polymer in terms of the viscosity of the corresponding non-sulphonated polymer and the average number of crosslinks associated with any chain.     

Hydrocracking of n-heptane with a NiO-MoO3/HYUS zeolite as catalyst. Kinetic study

The hydrocracking of n-heptane has been carried out in a fixed bed reactor at 2.45 MPa pressure and with a H₂/n-heptane molar ratio of 5.0 using a 4 wt% NiO - 8 wt% MO₃/HYUS zeolite as a catalyst. The W/F₁₀ ratio was varied between 75.3 and 1624 kg · s/kmol at different reaction temperatures: 573, 588, 603 and 623 K. The kinetics of the reaction has been studied by two different procedures due to the slight deactivation of the catalyst. One of them uses the conversion and yield values extrapolated at time on stream to zero and the other uses a kinetic equation where the deactivation of the catalyst has been included. The experimental data were fit well by a pseudo-first order kinetic equation and the kinetic constant values obtained by both methods coincide. The apparent activation energy of the reaction has a value of 105.8 + 5.0 kJ/mol.     

A PROTOTYPICAL SEASONAL ADJUSTMENT MODEL

Abstract. The paper analyses unobserved-components modelling and estimation for the simplest ARIMA process that accepts a full decomposition into trend, seasonal and irregular components. This prototypical model exemplifies many features of and issues arising in model-based seasonal adjustment that are less transparent in more complex seasonal time series models. In particular the analysis illuminates the major issues surrounding the specification of the component models and the identification of a unique structure for them. In so doing, the relationship between reduced- and structural-form approaches to unobserved components estimation is illustrated within an ARIMA-modelling framework. Finally, the properties of the minimum mean-squared-error estimators of the unobserved components are examined and the two main types of estimation error, revisions in the preliminary estimator and error in the final estimator, are analysed.     

高k材料／金属栅电极迈向大规模量产

到了45纳米技术节点,高介电常数绝缘材料和金属栅电极将被用于射造逻辑电路器件。而采用高金属功函数和能隙工程电荷陷阱的闪存也能从这些项技术中获益。     

Isomerization of lactose over natural sepiolite

Sepiolite (a hydrated magnesium silicate) was investigated as a catalyst for the isomerization of lactose. Factors such as temperature, concentration and time were studied. The main reaction product was lactulose; small amounts of epilactose, galactose, tagatose and 3-deoxypentulose were also formed. Product distribution indicated that the reaction routes were isomerization of the disaccharide followed by degradation of lactulose.     

Sonochemical decomposition of phenol: evidence for a synergistic effect of ozone and ultrasound for the elimination of total organic carbon from water

Advanced oxidation processes (AOPs) for water and wastewater treatment are often handicapped by their inability to completely eliminate total organic carbon (TOC). In order to explore the capability of the combination of ultrasonic irradiation with ozone for the rapid removal of TOC, we examined the degradation rates of dissolved phenol (C6H5OH) in water with high-frequency ultrasound over the range of 200-1000 kHz, with ozone and with the combined application of sonication and ozonation. When ozone and ultrasound are applied simultaneously, a pronounced synergistic effect is observed that leads to the complete and rapid elimination of TOC at enhanced reaction rates. At longer reaction times, phenol oxidation by 03 leads to oxalate and formate, which accounts for the majority of the residual TOC. However, the combination of US (ultrasound) and ozone together readily oxidizes HCO2- and C2O4(2-) to CO2 while they prove to be relatively resistant to further oxidation to CO2 by O3 alone.     

Kinetic study of calcite particle (powder) thermal decomposition: Part I

In the first step of the firing cycle used to manufacture white-firing wall tile bodies, the calcium carbonate that is added, as a source of CaO, to the clay raw materials mixture used to form these bodies needs to decompose. In order to study the kinetics of this process, a representative rate equation of the chemical reaction step of calcium carbonate thermal decomposition is needed.There is a disparity of opinions regarding the reaction order of this chemical reaction step. For this reason, it was decided to obtain a rate equation for this chemical decomposition step, using the same type and size calcite particles that are usually added to these clay mixtures in industrial practice.The present paper proposes a rate equation for this chemical reaction step. With this rate equation and the application of the “Uniform Conversion Model”, an expression has been derived that relates the fractional calcium carbonate conversion, in the studied calcite particles, to residence time and operating temperature. The equation satisfactorily fits the experimental results obtained under isothermal conditions in the studied temperature range for particles smaller than 100 μm.The calcite particles studied are highly porous aggregates (smaller than 1.1 mm) of very small single crystals (smaller than 20 μm). The experiments were conducted in the 850–950 °C temperature range.     

Combustion and emission performances of coconut,palm and soybean methyl esters under reacting spray flame conditions

The spray combustion characteristics of coconut (CME), palm (PME) and soybean (SME) biodiesels/methyl esters were compared with diesel by using an axial swirl flame burner. Atomisation of the liquid fuels was achieved via an airblast-type nozzle with varied atomising air-to-liquid ratios (ALR) of 2–2.5. The fully developed sprays were mixed with strongly swirled air to form combustible mixtures prior to igniting at the burner outlet. Under fuel-lean condition, biodiesel spray flames exhibited bluish flame core without the yellowish sooty flame brush, indicating low sooting tendency as compared to baseline diesel. Increasing the atomising air led to the reduction of flame length but increase in flame intensity. Measurements of post-combustion emissions show that SME produced higher NO as compared to CME and PME due to higher degree of unsaturation, while the most saturated CME showed the lowest NO and CO emissions amongst the biodiesels tested across all equivalence ratios. By preheating the main swirl air to 250 °C, higher emissions of NO, CO and CO₂ were observed for biodiesels. Higher ALR led to reduced NO and CO emissions regardless of the fuel used, making it a viable strategy to resolve the simultaneous NOCO reduction conundrum. This work shows that despite different emission characteristics exhibited by biodiesels produced from different feedstock, they are in principle potential supplemental fuels for practical combustion systems. The pollutants emitted can be mitigated by operating at higher ALR in a twin-fluid based swirl combustor.