Physicochemical principles of preparation of emulsion fuels

The basic physicochemical principles of preparation of emulsion fuel compositions based on heavy and extra-heavy crude cuts were analyzed with consideration of the nature and content of the phases constituting the emulsion, type of chemical additives — emulsifiers and stabilizers, and type of equipment for production of emulsion fuels. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 51–56, September–October, 2007.     

Influence of halide ions and alloy microstructure on the passive and localized corrosion behavior of alloy 22

Alloy 22 (N06022) is the current candidate alloy used to fabricate the external wall of the high-level nuclear waste containers for the Yucca Mountain repository. It was of interest to study and compare the general and localized corrosion susceptibility of Alloy 22 in fluoride and chloride solutions at 90 °C. Standard electrochemical tests such as cyclic potentiodynamic polarization, amperometry, and electrochemical impedance spectroscopy were used. Studied variables included the solution pH and the alloy microstructure (thermal aging). Results show that Alloy 22 is highly resistant to general corrosion in all the solutions tested. Thermal aging is not detrimental and even seems to be slightly beneficial for general corrosion at the higher solution pHs. Pitting corrosion was never observed. Crevice corrosion was found only for high chloride-containing solutions after anodic polarization. The presence of fluoride ions together with chloride ions seems to increase the susceptibility of Alloy 22 to crevice corrosion compared to pure chloride solutions. This article is based on a presentation made in the symposium “Effect of Processing on Materials Properties for Nuclear Waste Disposition,” November 10–11, 2003, at the TMS Fall meeting in Chicago, Illinois, under the joint auspices of the TMS Corrosion and Environmental Effects and Nuclear Materials Committees.     

A flexible architecture for distributed knowledge based systems with nomadic access through handheld devices

Nowadays any Knowledge Based System (KBS) realization needs of intercommunication among distributed components and to use non-connected and distributed data sources, which poses several challenges to the classical Artificial Intelligence field of KBS.

The multiagent paradigm and the use of ontologies are considered to be suitable tools to face the problems of designing and developing today KBS. On the other hand, using such networked KBS through handheld devices makes more efficient exploitation and interaction with the system.

This paper presents an open and flexible architecture for a distributed KBS and an application of it to construct a system for Psychological Disorders consulting, the so called PDA² (Psychological Disorder Assistant through PDA). We analyze the main features of the architecture as well as the agent tools we may use to construct it. Additionally, we present a support ontology for Psychological Disorders.     

Generation of Gas Discharge Plasma by an Arc Source with a Cold Hollow Cathode

The results from a study of an arc plasma source with a cold hollow cathode are presented. The source generates plasma with a density of ∼10¹⁰ cm⁻³ in a volume of ∼0.2 m³ at discharge currents of up to 150 A, an arc discharge operating voltage of 30–40 V, and a low pressure of 0.1–1 Pa. The motion of the cathode spot in the crossed electric and magnetic fields inside the hollow cathode and the cathode’s special design make it possible to eliminate almost completely the penetration of the sputtered cathode material into the working vacuum chamber.__________Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2005, pp. 62–66.Original Russian Text Copyright © 2005 by Schanin, Koval, Akhmadeev.     

Influence of generator load conditions on third-harmonic voltages in generator stator winding

The influence of changes in load conditions of the generator-transformer unit on the operating conditions of the 100% ground-fault protection of the generator stator winding based on the third-harmonic voltages was analyzed. The analyzed stator ground-fault protection system is by ratio of the voltages third harmonic in generator neutral and at the generator terminals. The third-harmonic voltages were determined on the base of the experimental tests (measurements) run in real conditions at changes in active and reactive load conditions of the generator. It was found that mainly the generator active load influences the voltage feeding the measuring element of ground-fault protection. Therefore, determining operating conditions of ground-fault protection the influence of the generator active and reactive load should be deeply considered. This can ensure the proper operation of the ground-fault protection based on the voltage third harmonics in the whole range of the changes in generator load. Considering the influence of changes in generator load on the third-harmonic voltages (feeding measuring element of the protection system) will allow eliminating irregular generator tripping as a result of unselective operation of these protections.     

Research on Marine Boiler＇s Pressurized Combustion and Heat Transfer

The effect of pressure on combustion and heat transfer is analyzed. The research is based on the basic combustion and heat transfer theorem. A correction for the heat calculation method for pressurized furnace is made on the basis of the normal pressure case. The correction takes the effect of pressurizing into account. The results show that the correction is reasonable and the method is applicable to combustion and heat transfer of the marine supercharged boiler.     

Hydrodynamics of marine current turbines

Various global studies have shown that marine currents have large potential as a predictable sustainable resource for commercial scale generation of electrical power. For successful exploitation of this resource, an understanding of the hydrodynamics of the marine current turbine is of primary importance. Although a lot can be learned from the technology transfer from wind turbines and ship propellers, there has been limited hydrodynamics research for this particular application. A methodology is presented for the hydrodynamic design of horizontal axis marine current turbines. Recent research has investigated the performance of suitable 2D section shapes both experimentally in a cavitation tunnel and with numerical simulations. A numerical model of a typical 3D rotor is used to demonstrate parametric variations of the design parameters and the use of alternative blade sections.     

Effect of sampling density on the measurement of stream condition indicators in two lowland Australian streams

There is widespread application of indicators to the assessment of environmental condition of streams. These indicators are intended for use by managers in making various comparative and absolute assessments and often have a role in resource allocation and performance assessment. Therefore, the problem of formally defining confidence in the results is important but difficult because the sampling strategies used are commonly based on a compromise between the requirements of statistical rigour and the pragmatic issues of access and resources. It is rare to see this compromise explicitly considered and consequently there is seldom quantification of the uncertainty that could affect the confidence a manager has in an indicator. In this paper, we present a method for quantitatively assessing the tradeoffs between sampling density and uncertainty in meeting various monitoring objectives. Assessments using judgement‐based representative reaches are shown to be unreliable; instead a sampling approach is recommended based on the random selection of measuring sites. A detailed dataset was collected along two streams in Victoria, Australia, and the effect of sampling density was assessed by subsampling from this dataset with precision related to the number of sites assessed per reach length and the intensity of the sampling at each site. The sampling scheme to achieve a given precision is shown to depend on the monitoring objective. In particular, three objectives were considered: (1) making a baseline assessment of current condition; (2) change detection; and (3) detection of a critical threshold in condition. Change detection is shown to be more demanding than assessing baseline condition with additional sampling effort required to achieve the same precision. Sampling to detect a critical threshold depends on nominating acceptable values of Type I and II error and the size of the effect to be detected. Copyright © 2006 John Wiley & Sons, Ltd.