350 research outputs found
Irrigation and drainage in the new millennium
Presented at the 2000 USCID international conference, Challenges facing irrigation and drainage in the new millennium on June 20-24 in Fort Collins, Colorado.Includes bibliographical references.A field study was conducted at Mashtul Pilot Area MPA (260 feddans' 1 feddan = 4200 m2) situated at north Zagazig to evaluate the performance of the long term constructed subsurface drainage system. The evaluation of grades, alignment and clogging of drain lines can give an indication of the system performance and efficiency. Three drainage units served by the same collector were selected. Four 30 m interval PVC lateral pipes were installed at different depths. The results revealed that, the collector drain slopes were either steep or flat while the overall slope of the collector drain was considered steep for about 45.50% of the sections and flat for the rest. On the other hand, some sections showed an inverse slope which can cause a decrease in the discharge rate. The regularity was classified as good for about 82% of the sections and moderate for the rest. The slope of the lateral drains was correct for 41.7% of those under study (12 lateral drains), steep for 16.60%, and flat for the rest, and the regularity was classified as poor except lateral number 71 which had moderate regularity in the first approach while, in the second approach 41.67% had moderate regularity and poor for the rest. Also the deviation of the drain pipes from the straight line was generally larger than pipe diameter. Consequently, air entrapment and sedimentation resulted. The results also indicated that, the average height of sedimentation inside lateral drains was 12.70 mm (618.30 gm/m drain length) while for collector drains, sediment was in 22.88% of pipe diameter. The average reduction in discharge capacity due to sedimentation for laterals and collectors upstream and downstream parts were 17.17%, 32.80% and 17.60% respectively. Also using Manning, Visser and Wesseling equations leads to different safety factors
Relative Rate Observer Self-Tuning of Fuzzy PID Virtual Inertia Control for An Islanded microgrid
Expanding the usage of renewable energy in islanded microgrids leads to a reduction in its total inertia. Low inertia microgrids have difficulties in voltage and frequency control. That affected saving its stability and preventing a blackout. To improve low inertia islanded microgrids\u27 dynamic response and save their stability, this paper presented relative rate observer self-tuning fuzzy PID (RROSTF-PID) based on virtual inertia control (VIC) for an islanded microgrid with a high renewable energy sources (RESs) contribution. RROSTF-PID based on VIC\u27s success in showing remarkable improvement in the microgrid\u27s dynamic response and enhancement of its stability. Moreover, it handles different contingency conditions successfully by giving the desired frequency support. Ant colony optimization (ACO) technique is used to find the optimal values of the RROSTF-PID based on VIC parameters. Furthermore, using MATLAB TM/Simulink, RROSTF-PID based on VIC response is compared to Optimal Fuzzy PID (OF-PID) based VIC, Fuzzy PID (F-PID) based VIC, PID-based VIC, conventional VIC responses, and the microgrid without VIC response under different operation conditions
Effect of Shape, Orientation and Aging of a Plastic Greenhouse Cover on the Degradation Rate of the Optical Properties in Arid Climates
In arid climates, the optical properties of plastic-covered greenhouses deteriorate very quickly. To examine the effect of greenhouse shape and orientation on the degradation rate of cover
optical properties, four greenhouse prototypes were constructed in two shapes (duo-pitched roof and tunnel), covered with a 200 âm thick low-density polyethylene film. Two types were oriented in the NorthâSouth direction, the other two in the EastâWest direction, and all were exposed for one year to an arid climate. Samples were taken from the different surfaces of each cover for testing. The total transmittance (Ts) and reflectance (Rs) of the samples were measured and averaged to obtain the whole cover properties (T and R). Measurements were carried out periodically every 30 days for the four prototypes. The degradation behavior of the optical properties of each cover surface (Ts, Rs) and the whole cover (T, R) was investigated for the four film covers during the exposure time. Results show that the degradation rate of Ts depends on the surface location and the cover orientation. Among the different surfaces of the four prototype covers, the maximum difference in the Ts value between the E and N surfaces for the tunnel cover oriented in the NâS direction was 15.5%. Although the variation of the Ts value among the different cover surfaces was found, the time dependences of the whole cover transmittance (T) for the four covers tested were almost similar. Accordingly, the shape and orientation of the small size greenhouses did not significantly affect the degradation rate of the cover optical properties. In the four covers tested, the reduction in the global solar radiation transmittance (T) was 27â31% after one-year exposure compared to the new film. Nonlinear correlation was developed to predict the degradation rate of the cover transmittance as a
function of the accumulated solar irradiance
Hepatic Ischemia-Reperfusion Injury: Pathogenesis and Pharmacological Treatment: Submitted: Dec 11, 2017 Accepted: Jan 28, 2018 Published online: Feb 5, 2018
Hepatic ischemia reperfusion injury (R/I) is a hepatic pathophysiologic process occurs post liver transplantation surgery. It also comprises complex systemic process affecting multiple tissues and organs. Hepatic I/R has serious impact on liver function, even producing irreversible failure, which may trigger multiple organ dysfunction. Many factors, including anaerobic metabolism, mitochondrial damage, oxidative stress and secretion of reactive oxygen species (ROS), intracellular calcium overload, cytokines and chemokines produced by Kupffer cells (KCs) and neutrophils are involved in the pathogenesis of hepatic I/R processes. There are many treatment options to combat hepatic I/R injury but none has shown clear beneficial clinical evidence. The purpose of this review is to provide insights into the mechanisms of hepatic I/R injury, indicating the potential factors/signaling pathways involved in this event and available therapeutic approaches that may help to improve controlling hepatic I/R during liver surgery
Evaluation of selective peripheral neurotomies in the treatment of refractory lower limb spasticity in adults
Background: ââSelective peripheral neurotomiesâ (SPNs) are indicated for the treatment of refractory focal and multifocal spasticity of lower limbs in adults.Objective: To evaluate the surgical results of selective peripheral neurotomies in 20 adult patients who had refractory focal & multifocal spasticity of the lower limbs, follow up period of one year.Patients and Methods: Prospective study included 20 adult patients who had refractory spasticity of the lower limbs. Preoperative evaluation for muscle tone using Modified Ashworth Score (MAS), muscle power using Medical Research Council Scale (MRCS), functional assessment using Oswestry Functional Scale (OFS) and Range Of Motion (ROM) using manual goniometry were done for all patients. All cases underwent surgery in the form of SPN of tibial, obturator, sciatic and/or femoral nerves. Follow up of the patients was done at 10th day, 3, 6 months and one year postoperatively.Results: The mean age of patients was 31.35 ± 12.42 years. There were statistically significant improvement of muscle tone, muscle power, functional assessment and range of motion between preoperative and one year postoperative values. Improvement of the muscle tone was from a preoperative Mean ± SD of 3.60 ± 0.68 on MAS to a postoperative 2.30 ± 0.86 at one year, improvement of muscle power on MRCS was from preoperative Mean ± SD 3.75 ± 1.08 to postoperative 4.08 ± 0.69 at one year, There was a functional improvement from a preoperative Mean ± SD of 3.0 ± 0.73 on OFS to 3.60 ± 0.60 at one year postoperatively. Also, there was a significant improvement between preoperative ROM Mean ± SD 61.25 ± 15.29 and one year postoperatively 72.25 ± 12.19.Conclusions: Selective peripheral neurotomies could effectively improve muscle tone, muscle power, functional performance & range of motion in patients with refractory focal and multifocal spasticity in the lower limbs.Keywords: Selective peripheral neurotomies, Spasticity, Neuroablative surgeries, Functional neurosurger
Sustainable Multi-objective Optimisation in Land-use Planning based on Non-dominated Sorting Genetic Algorithm (NSGA-II): a Case Study in Alexandria, Egypt
Due to urban sprawling, the worldâs land-use patterns have rapidly changed, leading to conflict and
competition among urban land-uses. This conflict resulted in a range of inefficient land-use patterns. The
negative impacts of such patterns suggest the need to improve the efficiency of land-use planning strategies
to support better sustainable development. To attain such efficiency, many researchers have adopted
algorithmic approaches perceiving land-use planning as a multi-objective optimization problem. These
approaches allow encompassment of the numerous variables and constraints that are introduced in the
planning process by decision makers and stakeholders. In this regard, a meta-heuristic method; the Nondominated Sorting Genetic Algorithm (NSGA-II), could provide an efficient decision support tool for landuse planning through offering pareto optimal land-use allocation alternatives.
This paper aims at adopting NSGA-II to enhance sustainable land-use planning strategies at a neighborhood
scale in the city of Alexandria, Egypt. The research suggests the adaptation of the Constrained Multiobjective Optimization of Land-use Allocation model (CoMOLA) for three main objectives: (i) maximizing
the value of economic benefit, (ii) spatial compactness, and (iii) land-use compatibility. Several land-use
allocation scenarios are investigated through an iterative process which includes the variables of spatial
unitsâ number, population sizes and significance of allocation objectives. The scenarios are then compared to
the existing condition of land-use distribution. The results show that the proposed approach using CoMOLA
tool exhibits good potential to support interactive land-use planning processes by searching over multiple
plans for optimal sets of non-dominated solutions. The optimized results could provide the scientific basis
for defining suitable interventions for improving sustainability measures and spatial optimization of landuses at the neighborhood scale
Texture evaluation of whey protein concentrate incorporated ice cream by Back Extrusion technique
Back extrusion technique was employed to evaluated texture properties of partial substituted whey protein concentrate (WPC) with milk solids not fat (1, 2, 3 and 4%) in ice cream formula.
There was no remarkable effect of adding WPC on total solids or fat %. Total protein increased, while ash, and lactose content were significantly decreased.
Back-extrusion results represented a decrease in hardness values of resultant ice cream, while, during storage, there was a slight increase. Energy input values decreased by increasing substitution levels of WP. Although, energy output inversely correlated with substitution levels of WP it correlated with storage period indicating a strong structure for stored ice cream. Load at target deformation (50%) applied to the samples when fresh and after 14 days storage showing decreased values proportional to increasing substitution levels of WP. The resilience showed decreased ratio indicating more visco-elastic properties in fresh ice cream. The recovered height and deformation increased with increasing substitution levels of WP and storage period. Therefore, more sticking properties were obtained in resultant ice cream. Adhesive force decreased significantly with increasing substitution levels of WP and storage period. Adhesiveness values were significantly higher in all treatments than control.
The texture of the ice cream became smoother by replacing milk solid not fat with WPC up to 3%. From the data obtained, it could be recommended that ice cream can be produced with high quality by substituting milk solid not fat with WPC up to 3%
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