Communication delays in an electric power grid affect the performance of control systems and can cause power losses. This paper analyzes the causes and effects of communication delays. The analysis employs a simulated power network comprising several generators for which braking resistors with intelligent (fuzzy logic) controllers are used for transient stability control. A balanced 3LG (three-phase-to-ground) fault at different points on the transmission lines is considered. Simulation results show that, although a fuzzy-logic-controlled braking resistor can improve transient stability, the communication delay associated with the online calculation of the total kinetic energy deviation, which is the input parameter for fuzzy control, has an influence on the transient stability performance. The paper also examines the delay that a system can tolerate and the cyber attacks that can cause additional delays.
Biodiesel is synthesized via the transesterification of triglycerides contained within vegetable, animal, or waste oils. First-generation biofuels are not the solution to global transport energy needs; however, biodiesel does have a role to play in reducing greenhouse gas emissions from the transport sector, so long as necessary production can be achieved in a sustainable manner without negative impact on plant and animal biodiversity. The biodiesel content within diesel sold to consumers is set to increase in the future, with implications on vehicle fuel consumption, emissions, and base engine durability. This study examines the effects of increasing the biodiesel blend ratio on the performance and emissions of a production vehicle equipped with a common-rail direct-injection diesel engine, evaluated on a chassis rolls dynamometer, at various ambient temperatures. Results obtained show that reductions in engine-out carbon monoxide and hydrocarbon emissions do not always translate to lower tailpipe emissions as reduced exhaust gas temperatures at higher blend ratios lead to reduced catalyst conversion efficiencies and higher total cycle emissions. Catalyst conversion efficiencies for carbon monoxide and hydrocarbons over the New European Drive Cycle (NEDC) are reduced by 9–19 per cent (depending on the ambient temperature) for a 50:50 blend (B50) compared with the petroleum diesel (B0) baseline. Increasing the blend ratio caused a linear decrease in the vehicle's maximum tractive force. This reduction was of the order of 5 per cent for a B50 blend at low vehicle speeds and 6–10 per cent at higher speeds, which is greater than would be expected on the basis of the differences in calorific values. Over the NEDC, the fuel consumption was found to increase with increasing blend ratio.
A growth experiment was conducted to study performance, nutrients digestibility and economic efficiency of broiler chicks fed corn-soybean meal diets supplemented with a commercial phytogenic product (Bedgen 40 ) contained artichoke extract (Cynara scolymus), a commercial mixture of ® organic acids (Galliacid ) and a combination of both. Starter, grower and finisher diets were ® supplemented with two levels of both being 0 and 150 g tG artichoke extract and 0 and 600 g tG 1 1 organic acids in 2×2 factorial arrangement. Dietary treatments were examined on 200 one day-old Cobb broiler chicks. The experiment lasted from 1-39 days of age. The results showed that supplementation of artichoke extract or organic acids mixture significantly (p<0.05) increased body weight gain by about 6% and improved feed conversion ratio by about 7%, compared with the control diet of no feed additives. Addition of artichoke extract improved the digestibility coefficients (p<0.01) of CP and CF, while, addition of organic acids mixture improved the digestibility coefficients (p<0.01) of DM, OM, CP, CF and NFE compared to the un-supplemented diet. Supplementation of artichoke extract and organic acids decreased total feed cost/kg body weight and improved net profit and economic efficiency. It could be concluded that using artichoke extract or organic acids mixture improved broiler performance and economic efficiency of broilers fed corn-soybean meal diets. No associative effect was detected on performance, digestibility or economic efficiency when a combination of both products was used.
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