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Abstract The rapid increase in energy demand and the limited resources of fossil fuel as well as the environmentally damaging effects, drive the world to find new options for sustainable electricity generation, which is represented by renewable energies. Concentrating solar power (CSP) is one of the most promising technologies in the field of electricity generation to tackle this issue with a competitive cost in the future. This paper presents an investigation of the potential of implementation of CSP plants in Libya. The socio-economic context, current energy situation of the country and different types of CSP plants are discussed. Moreover, an assessment of site parameters required for CSP plants including solar resources, land use and topography, water resources and grid connections are investigated in detail. In addition, thermo-economic simulation of a 50 MW parabolic trough power plant is performed. The simulation is conducted based on meteorological data measured by the weather station installed at the Centre for Solar Energy Research and Studies (CSERS) in Tajoura city. The performance results are compared with the reference plant Andasol-1 in Spain. Even though the proposed plant is located on the North coast where solar resources are at their minimum compared with other regions of the country, the outcome of the study proves that Libya is not only suitable but it can be economically competitive in the implementation of CSP technology.

Abstract The convergence characteristics of two Monte Carlo models are investigated in this paper. These two models or their variations have been used by the electric power industry. Model 1 is based on the random sampling of generator and transmission line status for each hour. Model 2 advances the generation and transmission using the next-event approach. Mathematical analysis and system studies indicate that model 2 converges slower than model 1. The simulation time for model 2 is generally more than twice the mean duration of loss of load. The CPU time per year of simulation is shorter for model 2. However, the total CPU time for model 2 is much longer than for model 1.

Global sensitivity analysis (GSA) of distribution system with respect to stochastic PV and load variations plays an important role in designing optimal voltage control schemes. This paper proposes a data-driven framework for GSA of distribution system. In particular, two representative surrogate modeling-based approaches are developed, including the traditional Gaussian process-based and the analysis of variance (ANOVA) kernel ones. The key idea is to develop a surrogate model that captures the hidden global relationship between voltage and real and reactive power injections from the historical data. With the surrogate model, the Sobol indices can be conveniently calculated through either the sampling-based method or the analytical method to assess the global sensitivity of voltage to variations of load and PV power injections. The sampling-based method estimates the Sobol indices using Monte Carlo simulations while the analytical method calculates them by resorting to the ANOVA expansion framework. Comparison results with other model-based GSA methods on the unbalanced three-phase IEEE 37-bus and 123-bus distribution systems show that the proposed framework can achieve much higher computational efficiency with negligible loss of accuracy. The results on a real 240-bus distribution system using actual smart meter data further validate the feasibility and scalability of the proposed framework.

Phasor-based frequency measurement techniques have very good steady-state performance, but their dynamic performance is not well documented. This paper analyzes a phasor-based frequency measurement method that considers the effect of dynamic frequency, and proposes a method to improve the dynamic performance of the phasor-based frequency measurements. Simulation results verify the effectiveness of the proposed method. Results of laboratory experiments are presented to show the performance of the proposed method compared to frequency measurements obtained from commercial phasor measurement units (PMUs).

A rich n-heptane/air mixture was burned in a flat flame burner in an inert environment, and the soot limits of stable one-stage flames were measured. With a small thin metal plate placed on the flame to suppress soot-containing cusps on the flamelets, the richest soot-free flame burned was with a mixture for which the equivalence ratio was 2.25. Hydrogen yield was, however, low. Extremely rich soot-free two-stage flames could be obtained, but they were unstable.

Forty-nine schools (N = 5,680 fifth and sixth grade students) were assigned to pre test/treatment, pretest/no treatment, no pretest/treatment, and no pretest/no treat ment conditions in the context of an alcohol misuse prevention study. At the first posttest, five months after the pretest and two months after the intervention, the effects of the pretest and of the intervention were examined. The analyses showed that failure to correct for the design effect due to clustering within schools resulted in the overestimation of the significance of treatment and pretest effects. After correction for the design effect, a significant treatment effect in the hypothesized direction was found with respect to students' awareness of the content of the curriculum. As hypo thesized, significant treatment effects on the alcohol use and misuse measures had not yet developed but are expected to occur at subsequent posttest occasions. Significant pretest effects were found for indices measuring trouble with peers resulting from students' alcohol use, students' internal health locus of control, and their perceptions of adults as a locus of control for their health. Two of the three pretest effects were in the direction that would be hypothesized if the pretest were providing the same impe tus as the intervention. Implications of these findings for school-based substance abuse prevention programs are discussed.

Abstract An orange and an apple juice each containing 250–385 ppm tin were under suspicion of having caused an outbreak of food poisoning in Kuwait in 1967 but did not cause any toxic signs when fed to pigeons, cats and dogs. One cat out of 11 vomited when fed an orange juice containing 540 ppm tin derived from the container, and with juices containing 1370 ppm tin, 20–30% of the cats vomited but none of the dogs was affected. Fruit juices containing 2000 ppm tin caused vomiting in up to 40% of the cats. Modification of orange juices with a high tin content by addition of nitrate or ethanol or by adjustment of the pH from 3 to 6 did not affect the incidence of vomiting. No toxic signs were produced in rats given fruit juices containing added tin salts up to a level of 995 ppm or in rats and cats given aqueous solutions of tin salts (up to 1200 ppm tin) in citric acid. Solid foods containing tin derived from the containers up to the highest level obtainable (470 ppm) had no toxic effect when fed to dogs and cats. Five human volunteers showed no toxic signs after drinking fruit juices containing 498, 540 or 730 ppm tin derived from the containers, but all five had some gastro-intestinal disturbance after drinking a fruit juice containing 1370 ppm tin. A repeat experiment with the latter juice had no effect in four of the volunteers and only mild symptoms in the fifth. In rats and cats, there was no evidence of tin absorption 24 hr after ingestion of fruit juices containing high levels of tin. No tin was recovered from the urine and in the rats 99% was recovered from the faeces. Only minute amounts of tin could be found in the body, apart from the alimentary tract, of a rat that had been given orange juice with a high tin content ad lib. instead of drinking water for 7 days. It is concluded that toxic signs follow the drinking of tin-containing fruit juices by man and cats only with tin levels of approximately 1400 ppm and above, that there is no evidence from these experiments that toxicity is due to the absorption of tin and that the most likely cause is local irritation of the mucous membrane of the alimentary tract.