CONTROL OF INTERCONNECTED JUMPING SYSTEMS: AN H∞ APPROACH

This paper investigates, by using an approach, the problems of stochastic stability and control for a class of interconnected systems with Markovian jumping parameters. Both cases of finite‐ and infinite‐horizon are studied. It is shown that the problems under consideration can be solved if a set of coupled differential or algebraic Riccati equations are solvable.     

Transport effects in catalytic fluidized-bed reactors

The majority of the fluidized-bed reactor models are models are rooted in the tacit assumption that transport between the bubble, cloud, and emulsion phases occurs in series with chemical reaction. A more realistic model that anticipates simultaneous transport and reaction is presented in terms of a fluid-bed effectiveness factor which embraces the limits between chemical and mass transport control. Analysis of the predictive capacity of this model vis-a-vis the Kunii-Levenspiel model reveals signal differences in chemical conversion.     

Determination of benzo(a)pyrene by GC/MS/MS in retail olive oil samples available in Qatar.

A survey was carried out for the presence of benzo(a)pyrene (B(a)P) in olive oils following reports that some batches of Spanish olive-pomace oil and its products contained high levels of B(a)P. Three types of olive oils (1) virgin olive oil, (2) refined olive oil and (3) olive-pomace oil, originating from France, Greece, Italy, the Lebanon, Spain, Tunisia and Turkey, and available on Qatar market, were analysed for B(a)P. Determination was carried out by extraction from a cyclohexane solution with N,N-dimethylformamide: water (9:1), back extraction with cyclohexane, followed by clean-up on a silica gel column and quantification by GC/MS/MS. The recovery and limit of quantitation of B(a)P in olive oils by this method were estimated as 88% and 0.5 microg kg(-1), respectively. B(a)P was detected in amounts below the permitted level of 2 microg kg(-1) in all 31 virgin olive oil samples and in 13 refined olive oil samples. However, all seven samples of Spanish olive-pomace oil produced and packed in Spain and three samples of olive-pomace oil produced in Spain, but packed in Saudi Arabia, were found to be contaminated with B(a)P, the level ranging from 3.1 to 70.8 microg kg(-1). In two samples of olive-pomace oil originating from Greece, B(a)P was not detected.     

Forecasting Daily Flood Water Level Using Hybrid Advanced Machine Learning Based Time-Varying Filtered Empirical Mode Decomposition Approach

Water Resources Management - Accurate water level forecasting is important to understand and provide an early warning of flood risk and discharge. It is also crucial for many plants and animal...     

Melt quenching and coolability by water injection from below: Co-injection of water and non-condensable gas

The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The goal of our work is to provide the fundamental understanding needed for melt–water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability. The work considers the ex-vessel coolability phenomena in two stages. The first stage is the melt quenching process and is being addressed by Argonne National Lab and University of Wisconsin in modified test facilities. Given a quenched melt in the form of solidified debris, the second stage is to characterize the long-term debris cooling process and is being addressed by Korean Maritime University via test and analyses. In this paper, experiments on melt quenching by the injection of water from below are addressed. The test section represented one-dimensional flow-channel simulation of the bottom injection of water into a core melt in the reactor cavity. The melt simulant was molten lead or a lead alloy (Pb–Bi). For the experimental conditions employed (i.e., melt depth and water flow rates), it was found that: (1) the volumetric heat removal rate increased with increasing water mass flow rate and (2) the non-condensable gas mixed with the injected water had no impairing effect on the overall heat removal rate. Implications of these current experimental findings for ALWR ex-vessel coolability are discussed.     

Mitigation of methane emissions from sanitary landfills and sewage treatment plants in Jordan

Mitigation of Greenhouse gases deals with measures to reduce the vulnerability of a certain sector to climate change through minimizing net emissions. In this paper, mitigation scenarios aimed at reducing Jordan methane emissions from sewage treatment plants and sanitary landfill sites were proposed and investigated. In the case of sewage treatment plants, As-Samra plant (the largest in Jordan) was selected for this mitigation study. Two scenarios (I and II) were proposed, the first was to expand the plant by the year 2005 using waste stabilization ponds the current treatment technology, and the second scenario involved switching the treatment technology to activated sludge type when the expansion starts in the year 2005. For sanitary landfills, the proposed mitigation scenario was the construction of two biogas plants, each with a processing capacity of 1,000 tons of solid waste per day at Rusaifeh and Akaider—the two largest landfills in Jordan at the beginning of the year 2005. For As-Samra plant, the cumulative reduction in methane emissions by the year 2030 was calculated to be 49 and 146 Gg under mitigation scenarios I and II, respectively. On the other hand, the biogas plant scenario reduces the methane emissions at each landfill by 28.1 Gg annually. The total emission reduction from both landfills in the life span (25 years) of the biogas plants will be about 1,406 Gg CH_4. In addition, this scenario generates electricity at a cost of 4.6 cents per kWh, which is less than the Jordan electric long-run marginal cost of generation at 5.5 cents/kWh. Moreover, annual savings of US$4.65 million will be achieved by the replacement of fuel oil with the generated biogas. The mitigation scenarios presented in this paper include measures that positively contribute to the national development of Jordan in addition to considerable reduction in methane emission.. This forms a win–win situation that favors the adoption of investigated mitigation scenarios by the decision-makers of the waste sector in Jordan.     

Capturing a Scheme Design for Rainscreen Cladding

Abstract:   This article reports on the exploratory application of product modeling techniques to the cladding of buildings. More specifically, it focuses on the development of a product model to formally capture the scheme design for a building that is clad with "rainscreen cladding." Such a model would enable the cladding scheme design to be conveyed in digital form throughout the subsequent procurement process. Rainscreen cladding was selected as being an exemplar of the cladding types used on buildings, although the resulting product model provides for the capture of visual and functional requirements. The article introduces the wider context of the research, explains the particular focus adopted for the modeling, describes the as-developed product model and includes an outline of prototype software that was developed specifically to help validate the model. The resulting product model could readily be reworked as a cladding extension to the IFC or the CIS/2.     

Characterization of the stress corrosion cracking behavior of thermally sensitized 20Cr-25Ni stainless steel in a simulated cooling pond environment

Niobium stabilized 20Cr-25Ni stainless steel is used for nuclear fuel cladding in the UK's fleet of advanced gas cooled reactors (AGRs). The cladding can have chromium-depleted grain boundaries as a consequence of irradiation in a reactor core, rendering a small proportion of cladding susceptible to intergranular stress corrosion cracking in cooling pond waters after removal from the reactor. In this work, thermal sensitization was used to simulate chromium depletion and the sensitized material was assessed for its susceptibility to pitting corrosion and stress corrosion cracking using slow strain rate testing (SSRT). Elevated chloride concentrations were used to accelerate corrosion initiation and propagation. In 10 ppm chloride and 80 °C, the pitting potential was at potentials between +375 mV and +400 mV (SCE). SSRT appeared to lower the pitting potential, with intergranular corrosion and intergranular stress corrosion cracks observed to nucleate at potentials of +200 mV (SCE).