Experimental measurement of focused wave group and solitary wave overtopping

Prediction of individual wave overtopping events is important in assessing danger to life and property, but data are sparse and hydrodynamic understanding is lacking. Laboratory-scale waves of three distinct types were generated at the Coastal Research Facility to model extreme waves overtopping a trapezoidal embankment. These comprised wave groups of compact form, wave groups embedded in a background wave field, and a solitary wave. The inshore wave propagation was measured and the time variation of overtopping rate estimated. The total volume overtopped was measured directly. The experiments provide well-defined data without uncertainty due to the effect of reflection on the incident wave train. The dependence of overtopping on a range of wave shapes is thus determined and the influence of wave-wave interactions on overtopping assessed. It was found that extreme overtopping may arise from focused waves with deep troughs rather than large crests. Furthermore, overtopping waves can be generated from small wave packets without affecting the applicability of results to cases in which there are surrounding waves. Finally, overtopping from a solitary wave is comparable with overtopping from focused wave groups of the same amplitude. © 2011 Copyright International Association for Hydro-Environment Engineering and Research

Sale-based estimation of pharmaceutical concentrations and associated environmental risk in the Japanese wastewater system

Information on sales and emission of selected pharmaceuticals were used to predict their concentrations in Japanese wastewater influent through a >300 of pharmaceuticals data sink. A combined wastewater-based epidemiology and environmental risk analysis follow was established. By comparing predicted environmental concentrations (PECs) of pharmaceuticals in wastewater influent against measured environmental concentrations (MECs) reported in previous studies, it was found that the model gave accurate results for 17 pharmaceuticals (0.5 1 μg/L), and the PECs of 6 pharmaceuticals were extremely high (>10 μg/L) in wastewater effluent, which could be attributed to their high usage rates by consumers and poor removal rates in wastewater treatment plants (WWTPs). Furthermore, environmental risk assessment (ERA) was carried out by calculating the ratio of predicted no effect concentration (PNEC) to PEC of different pharmaceuticals, and it was found that 9 pharmaceuticals were likely to have high toxicity, and 54 pharmaceuticals were likely to have potential toxicity. It is recommended that this is further investigated in detail. The priority screening and environmental risk assessment results on pharmaceuticals can provide reliable basis for policy-making and environmental management

A Study of Challenges and Benefits of Lean Construction (LC) Principles in Omani Construction Industry

There are frequent failures in the project delivery in time and increasing the waste in Oman construction industry. Lean Construction (LC) principles which is lean thinking in design and construction process may be a possible solution. Hence, the paper is aimed on exploring the status of the LC practices and its impact on Omani Construction Industry (OCI). The paper presents barriers, potential benefits, and the measures of suitability and acceptability of LC principles. A quantitative research approach was adopted and research data was collected using an online questionnaire survey in Oman. The data was analysed and results are presented in tables and charts followed by critical discussions. The survey found that one-third of the construction professionals have a good awareness and half of then having a higher level awareness about LC practices. More than one third of the construction organisations are adopting LC principles with a high consensus on the suitability and acceptability, and they recognised that time commitment are necessary for the successful implementation and achieve benefits. The study concludes that the reduction in project delivery time and construction at site waste is the key advantage of implementing LC principles in design and construction stages in the Omani construction industry

Large N limit of SO(N) gauge theory of fermions and bosons

In this paper we study the large N_c limit of SO(N_c) gauge theory coupled to a Majorana field and a real scalar field in 1+1 dimensions extending ideas of Rajeev. We show that the phase space of the resulting classical theory of bilinears, which are the mesonic operators of this theory, is OSp_1(H|H )/U(H_+|H_+), where H|H refers to the underlying complex graded space of combined one-particle states of fermions and bosons and H_+|H_+ corresponds to the positive frequency subspace. In the begining to simplify our presentation we discuss in detail the case with Majorana fermions only (the purely bosonic case is treated in our earlier work). In the Majorana fermion case the phase space is given by O_1(H)/U(H_+), where H refers to the complex one-particle states and H_+ to its positive frequency subspace. The meson spectrum in the linear approximation again obeys a variant of the 't Hooft equation. The linear approximation to the boson/fermion coupled case brings an additonal bound state equation for mesons, which consists of one fermion and one boson, again of the same form as the well-known 't Hooft equation.Comment: 27 pages, no figure

Offshore Conversion of Wind Power to Gaseous Fuels: Feasibility Study in a Depleted Gas Field

A proof-of-concept study is presented of a Power-to-Gas system that is located fully offshore. This paper analyses how such a system would perform if based at the depleted Kinsale Gas Field in the Celtic Sea Basin off the south coast of Ireland. An offshore wind farm is proposed as the power source for the system. Several conversion technologies are examined in detail in terms of resource efficiency, technological maturity, and platform area footprint, the aim being to ascertain their overall applicability to an offshore Power-to-Gas system. The technologies include proton exchange membrane electrolysers for electrolysis of water to release H2. Bipolar membrane electro-dialysis and electronic cation exchange module processes are also considered for the extraction of CO2 from seawater. These technologies provide the feedstock for the Sabatier process for the production of CH4 from H2 and CO2. Simulations of the end-to-end systems were carried out using Simulink, and it was found that the conversion of offshore wind power to hydrogen or methane is a technically feasible option. Hydrogen production is much closer to market viability than methane production, but production costs are too high and conversion efficiencies too low in both cases with present-day technology to be competitive with current wholesale natural gas prices

Watershed-scale environmental risk assessment of accidental water pollution: The case of laoguan river, China

Although co-existing sources of chemicals pose major cumulative environmental threats to watersheds, few risk asse- ssments have specifically tackled the accidental chemical pollution of rivers at watershed-scale. Herein, a Watershed-scale Accidental Pollution Risk Assessment (WAPRA) method was constructed which applied a risk ranking procedure to the whole watershed, and was based on watershed-scale stressors, exposures to and effects of water accidental pollution risk (e.g., sudden occurrences, waterway spread, and acute consequences). Multi-criteria analysis and instantaneous water quality models were used to refine the risk ranking procedure within the framework of a Relative Risk Model (RRM), a regional-scale ecological risk assessment approach. The study area comprised the Laoguan River, a tributary watershed of the Danjiangkou Reservoir, which will eventually feed into the South-to-North Water Diversion Project in China. The resultant map shows that risk is higher in the upstream and downstream reaches, and lower in the middle reaches. The map also indicates that the greatest threat to water quality arises from the upstream heavy metal mine tailings ponds. Sensitivity and uncertainty analyses were performed to validate the robustness of the WAPRA method

Analysing Delay Impact from Potential Risk Factors on Project Delivery of Oil and Gas Pipeline: A Case Study in Iraq

The aim of this paper is to present the design and specifications of an integrated Delay Analysis Framework (DAF), which could be used to quantify the delay caused by the Risk Factors (RFs) in Oil and Gas Pipelines (OGPs) projects in a simple and systematic way. The main inputs of the DAF are (i) the potential list of RFs in the projects and their impact levels on the projects and the estimated maximum and minimum duration of each task. Monte Carlo Simulation integrated within @Risk simulator was the key process algorithm that used to quantify the impact of delay caused by the associated RFs. The key output of the DAF is the amount of potential delay caused by RFs in the OGP project. The functionalities of the developed DAF were evaluated using a case study of newly developed OGP project, in the south of Iraq. It is found that the case study project might have delayed by 45 days if neglected the consideration of the RFs associated with the project at the construction stage. The paper concludes that identifying the associated RFs and analysing the potential delay in advance will help in reducing the construction delay and improving the effectiveness of the project delivery by taking suitable risk mitigation measures