Adaptive exponentially smoothed control charts

This paper presents an adaptive exponentially smoothed control system. The adaptive nature is achieved by varying the weighting factor according to the value of a tracking signal. An example of an adaptive control chart is presented. Sensitivity curves, which present the probabilities of acceptance as a function of sampling periods after a change in a process occurs, are illustrated.     

Mechanical Properties of Hot-Pressed Silicon Nitride with Different Grain Structures

During hot-pressing of α-Si₃N₄ powders, the equiaxed α micro-structure gradually transforms into a β structure characterized by needle-shaped prismatic grains which are closely entangled and linked together. With increasing amounts of the β fraction, the bend strength, fracture toughness, and work of fracture increase significantly, then decrease as grain growth occurs. The K _lc, improves by a factor of >2 and the change in γ_F by a factor of >4. The crack resistance to achieve the same crack velocity in materials of different β contents shows a similar trend. The dependence of the mechanical properties on the microstructure is explained by linking and pullout of the β crystals and by grain coarsening.     

Self-assembling organomodified Co/Al based layered double hydroxides （LDH） via one-step route

The preparation of self-assembling organomodified Co/Al-layered double hydroxide (LDH) via one-step route was studied. A common surfactant, sodium dodecylbenzenesulfonate (DBS), was employed as an organic modifier. The behavior and structure of self-assembled intercalated organic Co/Al-LDH were investigated by FTIR, SEM, WAXS, element analysis and TGA. Based upon the WAXS results and calculation by Bragg equation, the interlayer distance (d value) for organic Co/Al-LDH is enlarged from 0.75 nm to 3.10 nm, showing that the self-assembling behavior has been carried out successfully. Considering the observation from SEM, the product shows the morphology of organic Co/Al-LDH of a layered structure. In addition, FTIR, element analysis and TGA analysis show that the modifier is intercalated into the gallery of the Co/Al-LDH. Since organic modification for nanofiller is deemed to be necessary before applying it into polymer, the successful preparation of organomodified Co/Al-LDH will be significantly beneficial to the preparation and investigation of novel polymer/LDH nanocomposite.     

The effect of monomolecular surface films on the microwave brightness temperature of the sea surface

Abstract

Airborne microwave radiometer measurements at 1·43 and 2·65 GHz over a sea surface covered with a monomolecular oleyl alcohol surface film and over adjacent slick sea surfaces are presented. The measurements show that at 2·65 GHz the brightness temperature T _B is not affected by the slick, while at 1·43 GHz it drops from 93 K to a minimum value of almost O K. This implies that at 1·43 GHz the emissivity of the slick-covered sea surface is extremely small, similar to a metallic layer, and that this resonant-type phenomenon is confined to a narrow frequency band of width δ?/ ?<0·6.

The theoretical implications of these experimental findings are discussed in the framework of the Debye relaxation theory of polar liquids. It is conjectured that a thin layer of water molecules polarized by the surface film gives rise to an anomalous dispersion, which causes the large decrease in brightness temperature at 1·43 GHz.

The modulus of the relative dielectric constant ε? is estimated to be ≥ 5·2 × 10^?4 and the thickness of the emitting layer ≤1·9 × 10^?4 m for 1·43 GHz. Furthermore, the film-induced surface activation energy is calculated to be 9·18 × 10^?21 J. These values seem reasonable in the light of the theories on the physicochemical structure of surface layers.     

Fermentation properties of a wine yeast over-expressing the Saccharomyces cerevisiae glycerol 3-phosphate dehydrogenase gene (GPD2)

Wine yeasts efficiently convert sugar into ethanol. The possibility of diverting some of the sugar into compounds other than ethanol by using molecular genetic methods was tested. Over-expression of the yeast glycerol 3-phosphate dehydrogenase gene ( GPD2 ) in a laboratory strain of Saccharomyces cerevisiae led to an approximate two-fold increase in the extracellular glycerol concentration. In the medium fermented with the modified strain, acetic acid concentration also increased approximately two-fold when respiration was blocked. A strain deleted for the GPD2 gene had the opposite phenotype, producing lower amounts of glycerol and acetic acid, with the latter compound only reduced during non-respiratory growth. A commercial wine yeast over-expressing GPD2 produced 16.5 g/L glycerol in a wine fermentation, compared to 7.9 g/L obtained with the parent strain. As seen for the laboratory strain, acetic acid concentrations were also increased when using the genetically modified wine yeast. A panel of wine judges confirmed the increase in volatile acidity of these wines. The altered glycerol biosynthetic pathway sequestered carbon from glycolysis and reduced the production of ethanol by 6 g/L.     

Discrimination between crude-oil spills and monomolecular sea slicks by airborne radar and infrared radiometer—possibilities and limitations

Abstract

The applicability of an X-band (9·4 GHz) real aperture radar (RAR) and an infrared (IR) radiometer to discriminate between crude-oil spills and monomolecular sea slicks is investigated over the same sea area. The results from quasi-simultaneous overflights over a crude-oil spill and three different sea slicks (oleyl alcohol, di-(ethylenglycol)-mono-isostearyletherand methyl oleate)show that the advantage of an imaging radar is its uniequi vocal potential for surveying large sea surfaces and that the advantage of an IR sensor is its ability to determinate quickly the thick centres of crude-oil spills. However, neither the RAR nor the IR radiometer can discriminate between crude-oil spills and sea slicks. Therefore, an airborne coastal patrol with the objective of monitoring oil pollution must comprise a package of additional sensors, e.g. a microwave radiometer and/or a lidar system.     

Water Supply Franchising in Buenos Aires

This paper outlines the approach which was recently adopted by the Government of Argentina for the franchising of water services in Buenos Aires. It briefly reviews the water and sewerage services in the area and outlines the operation, background and process which were adopted by the Government to secure the franchise. The paper explains the circumstances and objectives, and describes how the franchising process developed both politically and organizationally. It also examines the franchisee and selection process, the bidding requirements, and organizational arrangements which enabled a successful transfer of the water services from public to private sector.     

Field-theoretic analysis of wave propagation on FET electrodes including losses and small-signal amplification

A wave-theoretic analysis of MESFET electrode structures is presented where for the first time both the losses caused by the semiconductor layer and those caused by the finite conductivity of the electrodes are taken into consideration. The active properties of the transistor are modelled by adopting a suitable small-signal theory. The results are discussed by taking as an example a TW FET design, although they are equally relevant for all standard microwave MESFETs.