Object-oriented DBMS requirements

The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management.     

Effect of cooking on the chemical composition of lentils,rice and their blend (Koshary)

Lentils, rice and their blend (Koshary) were cooked by traditional Egyptian methods. Cooking resulted in slight changes in the total nitrogen, as well as in the non-protein nitrogen (NPN), ether extract and crude fibre of the three products, compared with raw grains. In contrast, significant decreases were found in the mineral elements, indicating losses through leaching, on washing and cooking. The mineral composition of lentils' cooking liquor confirmed this.     

Synthesis of vaterite CaCO3 as submicron and nanosized particles using inorganic precursors and sucrose in aqueous medium

It is reported the synthesis of CaCO₃ vaterite as stable nanoparticles and submicron-sized by a simple and relatively rapid procedure. XRD, SEM and FTIR techniques have been used to characterize the precipitated products. The synthesis is based on chemical precipitation of inorganic salt precursors, calcium nitrate tetrahydrate and sodium bicarbonate, and using the disaccharide sucrose as an additive in aqueous medium. The role of the disaccharide sucrose is to control the vaterite precipitation after nucleation and growth. It has been found that an increase in sugar concentration promotes the crystal precipitation of vaterite with spherulitic morphology, as revealed by SEM, and changed the surface of the precipitated particles. There is a significant difference between CaCO₃ precipitation in the absence and presence of sucrose. Addition of 0% of sucrose leads to 83% of calcite as identified by XRD methods. In contrast, addition of 67% of sucrose in aqueous medium produces 100% vaterite. The present results may be useful to provide a quick, simple, inexpensive and novel method for the controlled synthesis of new advanced biomaterials based on vaterite particles without hazardous chemicals and inert atmosphere, with great possibilities for industrial scale production.     

Three-Electrode Organic-Type G.M. Counter Design and Performance

The sensitivity of the organic-type G.M. tube is increased by introducing a third electrode (grid) between the cylindrical steel cathode and a concentric tungsten wire anode and applying positive potential to that grid. The optimum position of the grid inside the cathode corresponding to the minimum capacitance of the counter is determined by using the simulation technique. Plateau curves of this tube are obtained for different grid positions. It is justified that the best performance of the tube is determined with the optimum grid position. Plateau curves of the three-electrode G. M. tube are also reported, with optimum grid position, for different values of grid potential. It is found that the sensitivity of the counter can be controlled by variation of the grid potential.     

Construction of discrete-time models for port-controlled Hamiltonian systems with applications

The issues of constructing a discrete-time model for Hamiltonian systems are in general different from those for dissipative systems. We propose an algorithm for constructing an approximate discrete-time model, which guarantees Hamiltonian conservation. We show that the algorithm also preserves, in a weaker sense, the losslessness property of a class of port-controlled Hamiltonian systems. An application of the algorithm to port-controlled Hamiltonian systems with quadratic Hamiltonian is presented, and we use this to solve the stabilization problem for this class of systems based on the approximate discrete-time model constructed using the proposed algorithm. We illustrate the usefulness of the algorithm in designing a discrete-time controller to stabilize the angular velocity of the dynamics of a rigid body.     

A note on input-to-state stabilization for nonlinear sampled-datasystems

We provide a framework for the design of L_∞ stabilizing controllers via approximate discrete-time models for sampled-data nonlinear systems with disturbances. In particular, we present sufficient conditions under which a discrete-time controller that input-to-state stabilizes an approximate discrete-time model of a nonlinear plant with disturbances would also input-to-state stabilize (in an appropriate sense) the exact discrete-time plant model     

Performance Characteristics of Alpha-Particle Corona-Streamer Counter

Alpha-particle wire-plate corona counters in air can be operated either in the spark or in the corona-streamer modes. The streamer mode is preferred over the spark mode since it has the advantages of low dead time and the absence of electrode corrosion by sparking. An analysis of the alpha-particle corona-streamer counter is described. The alpha-particle triggered corona pulse characteristics (e.g., pulse shape, amplitude, repetition rate, etc.) are calculated. Not only the pulse characteristics but also the inception voltages of the corona-mode regime are determined. For each wire diameter, a transition gap length between corona and spark modes exists, which is termed ``critical gap length.' The counting rate characteristics have been obtained for wire diameters 0.05-0.1 mm. All the theoretical findings are confirmed by experiment.     

Studies on cocoa beans (Theobroma cocoa L.)

Summary Scanning electron microsopcy (SEM) was used to study the microstructure of raw and processed cocoa beans (Theobroma cocoa L.). Photomicrographs of seed coat revealed tracheary elements (spiral vessels) and simple pits, while the cotyledon of raw bean consists of parenchyma cells. When beans were roasted to 125 °C for 20 min, the cotyledon became porous and brittle and the cellular contents became thermally coagulated. Also, after basification there was an increase in surface porosity of the cotyledon. These SEM observations could be employed as a monitor for processing and/or quality control.The basification of cocoa beans with different alkalis, revealed differences in color as depending on the type of alkali and its concentration.

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Untersuchungen über Kakaobohnen (Theobroma cocoa L.)Einfluß einiger Verfahren auf die Mikrostruktur und Farbe der Bohnen

Zusammenfassung Scanning-Elektronenmikroskopie (SEM) wurde für die Untersuchung der Mikrostruktur roher und behandelter Kakaobohnen angewandt. Mikrophotographien der Samenschale zeigten Tracheenelemente (Spiralgefäße) und einfache Vertiefungen, während die Cotyledonen der rohen Bohnen aus Parenchymzellen bestehen. Wenn Bohnen für 20 min bei 125 °C geröstet werden, werden die Cotyledonen porös und brüchig und der Zellinhalt koaguliert. Auch nach der Alkalisierung erhöht sich die Porosität der Oberfläche der Cytoledonen. Diese SEM-Beobachtungen könnten zur Prüfung, der Arbeitsweise und/oder der Qualitätskontrolle angewandt werden. Die Alkalisierung der Kakaobohnen mit verschiedenen Alkalien zeigt Unterschiede in der Farbe in Abhängigkeit von der Art und Konzentration des Alkali.

     

Dimensional change and elastic behavior of layered silicates and Portland cement paste

The role of water in hydrated Portland cement paste (hpc) is germane to understanding the nature of nanostructure – property relationships of the material. The irreversible dimensional changes of hpc and phase pure C–S–H that occur on wetting and drying are dissimilar to those observed for other silicate minerals of interest to cement science. This irreversibility in hpc is also observed for the modulus of elasticity parameter. Length change, mass change and modulus of elasticity isotherms (including drying–wetting cycles) were determined for specimens of hpc, Ca-montmorillonite and 1.4 nm tobermorite. Length change and modulus of elasticity versus mass loss curves were also obtained for phase pure C–S–H (C/S = 0.8, 1.0 and 1.5). All the isotherms exhibit significant irreversible behavior. Similarities and differences in the nature and character of the isotherms and the relevance of the C–S–H data are discussed. Inferences are made with respect to the nanostructural nature of hpc, its dimensional response in aqueous media and the correspondence in behavior of synthetic C–S–H and that formed in hpc. It is apparent that hpc has unique characteristics that are responsible for stability.