A Modified Cooling System for Stand Alone PV Greenhouse in Remote Areas

Abstract. Agricultural efforts are normally carried out in remote areas where electricity from national electric grid may not exist or grid connection is very expensive. Greenhouses industry is one of the most important agricultural practices in remote areas. Greenhouses help in extending the gardening activities and allows us to cultivate certain plants all over the year; by controlling air temperature and relative humidity inside greenhouse. In greenhouses, cooling and pumping equipments dominate the demand for electricity. Therefore, a stand-alone photovoltaic (PV) system is necessary to feed that demand. Medicinal herbs, for example are the most suitable plants to be cultivated in the greenhouses. They often need a temperature range of 15 -21 oC and about 70% relative humidity to grow. As the climate in Egypt is not suitable all over the year to cultivate these medicinal herbs, it is preferable and necessary to use PV-based control greenhouse to cultivate these medicinal herbs in Egyptian remote areas. This paper presents a proposed greenhouse cooling system, which uses a stand-alone PV system to feed the electrical loads of the greenhouse. At the same time, it introduces the complete sizing procedure of the greenhouse stand-alone PV system

Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

Injection Drug Use Is a Risk Factor for HCV Infection in Urban Egypt

OBJECTIVE: To identify current risk factors for hepatitis C virus (HCV) transmission in Greater Cairo. DESIGN AND SETTING: A 1:1 matched case-control study was conducted comparing incident acute symptomatic hepatitis C patients in two "fever" hospitals of Greater Cairo with two control groups: household members of the cases and acute hepatitis A patients diagnosed at the same hospitals. Controls were matched on the same age and sex to cases and were all anti-HCV antibody negative. Iatrogenic, community and household exposures to HCV in the one to six months before symptoms onset for cases, and date of interview for controls, were exhaustively assessed. RESULTS: From 2002 to 2007, 94 definite acute symptomatic HCV cases and 188 controls were enrolled in the study. In multivariate analysis, intravenous injections (OR = 5.0; 95% CI = 1.2-20.2), medical stitches (OR = 4.2; 95% CI = 1.6-11.3), injection drug use (IDU) (OR = 7.9; 95% CI = 1.4-43.5), recent marriage (OR = 3.3; 95% CI = 1.1-9.9) and illiteracy (OR = 3.9; 95% CI = 1.8-8.5) were independently associated with an increased HCV risk. CONCLUSION: In urban Cairo, invasive health care procedures remain a source of HCV transmission and IDU is an emerging risk factor. Strict application of standard precautions during health care is a priority. Implementation of comprehensive infection prevention programs for IDU should be considered

Genetic single objective optimisation for sizing and allocation of renewable DG systems

The optimal design of renewable-based distributed generations (DGs) is a challenging issue in order to maximise their benefits and to overcome power quality problems. Therefore, this paper proposes a methodology for optimal allocation and sizing of renewable DG units to minimise total power losses over radial distribution systems. The planning problem is formulated as a single objective nonlinear mixed integer-constrained optimisation problem and is solved by using the augmented Lagrangian genetic algorithm (ALGA) by combining the objective function and the nonlinear constraints. In that case, the ALGA solves a sequence of sub-problems where the objective function penalises the constraints violation in order to obtain the best solution. The proposed technique is applied to IEEE radial test systems including 33-bus, 69-bus and 119-bus and is implemented with different scenarios including all possible combinations and various types of renewable DG units to prove the effectiveness of the proposed methodology

Comparative study between true umbilical versus supra umbilical technique as an open access for pneumoperitoneum during laparoscopic surgery

Background: To start laparoscopic procedures, accessing the peritoneal cavity and establishing a carbon dioxide pneumoperitoneum are critical. The placement of the primary trocar is an important step in laparoscopic surgery. Many techniques have been reported in order to limit complications associated with the placement of the first trocar. In the study we describe a surgical method that offers quick, safe, and reliable preliminary entry into the peritoneal cavity with incredible functional and cosmetic results. Methods: A prospective randomised comparative study was conducted on 202 candidates for various laparoscopic surgery, comparing true umbilical versus supra umbilical open access for pneumoperitoneum from November 2021 to May 2022 in our surgical department. Results: There were 202 patients in the study, 109 (women) and 93 men. The port site entry per seconds was 41.3± 1.2 in true umbilical technique (group A) and 132.9± 5.5 in supra umbilical open technique (group B), and that was a statistically significant difference (p < 0.0001). There was a statistically significant difference in the mean time of port site wound closure (<0.0001) and port site gas leaking in the true umbilical access group compared to the supra umbilical access group (0.000161).&nbsp

Experimental evaluation of 8 kW grid-connected photovoltaic system in Egypt

An experimental observation study of 8 kW grid-connected photovoltaic (PV) system that is installed at Electronics Research Institute (ERI), Giza, Egypt (Latitude 30.04°N, Longitude 31.21°E), is presented. This study includes the quality of the electrical power generated and injected into the network. The considered system consists of 28 × 295 Wp multicrystalline PV modules, StecaGrid three-phase 8 kW grid-connected inverter and a Solar-Log 300 PM+ for data acquisition and remote monitoring. The power quality parameters at the inverter output side have been measured using CA8335 power quality analyzer. The system has been installed in August 2014 and generated 5.7 MWh till February 2015. The produced electricity by the system is injected directly into the grid without storage device. The purpose of this paper is to present and evaluate the measurements of the power quality parameters obtained from the PV site. Also, this paper presents a comprehensive evaluation of the performance of the system over a period of one week. The observation and analyses exploitation of the collected data can help to evaluate the performance of the PV system connected to the network

Alleviation of Salt Injury of Cucumber Plant by Grafting onto Salt Tolerance Rootstock

Abstract: Experiment was conducted in a greenhouse during the two successive seasons of 2008-2009 and 2009-2010 to investigate the effect of grafting technique in improving salt tolerant of grafted cucumber plants (Cucumis sativus L. cv. falcon, Hybrid F1) under saline conditions. Samples were taken at 70 days after planting to determine plant growth, leaf electrolyte leakage percentage (Membrane Permeability) and leaf relative water content (LRWC). As well as, fruits yield and quality, biochemical analyses and antioxidant enzymes activity. Grafting of cucumber on salt tolerance rootstock (Shintosa Supreme pumpkin) significantly increased growth parameters by 44% and 69% for fresh weight, dry weigh by 41% and 69%, plant height 86% and 83% and leaf area by 102% and 57% in both season respectively and enhancement 12% and 13% in leaf relative water content (LRWC) as compared to ungrafted cucumber in both season. Furthermore, These positive effects of grafting cucumber was correlated with significantly increased in chlorophyll, carotenoid, proline and total soluble protein concentrations. Although, grafting reduced membrane permeability and malondialdehyde (MDA) concentration in leaves of cucumber plants under salt stress conditions. As well as, improved fruit number, fruit weight, number of harvest and fruit yield comparing with ungrafted plants. As well as, Grafting increased PAL, POD, CAT, SOD, PPO and APX activities as compared to ungrafted plants under saline conditions. Excluding, grafted plants significantly reduced titratable acidity (TA %), total soluble solids (TSS %) and electrical conductivity (EC) in fruit juice as compared to ungrafted plants