Short-term scheduling of hybrid thermal, pumped-storage, and wind plants using firefly optimization algorithm

This paper presents a novel method based on an enhanced firefly algorithm (EFA) to solve scheduling hybrid thermal, pumped-storage, and wind plants. Since the scheduling problem is inherently discrete, basic EFA and binary encoding/decoding techniques are used in the proposed EFA approach. Optimal power values of thermal and pumped-storage units are determined separately in the presence of uncertainty caused by wind speed. The proposed method is applied to a real plant, including four pumped-storage units, 34 thermal units with different characteristics, and one wind turbine plant. In addition, dynamic constraints of upstream and downstream sources and constraints regarding thermal and wind units are also considered for finding the optimal solution. In addition, the proposed EFA is successfully applied to a real plant, and the results are compared with those of the three available methods. The results show that the proposed method has converted to a more optimal cost than the other methods

Optimal operation of an energy hub considering the uncertainty associated with the power consumption of plug-in hybrid electric vehicles using information gap decision theory

© 2019 Elsevier Ltd An energy hub is a multi-carrier energy system that is capable of coupling various energy networks. It increases the flexibility of energy management and creates opportunities to increase the efficiency and reliability of energy systems. When plug-in hybrid electric vehicles (PHEVs)are incorporated into the energy hub, batteries can act as an aggregated storage system, increasing the potential integration of variable renewable energy sources (RES)into power system networks. This paper presents a new model for the optimal operation of an energy hub that includes RES, PHEVs, fuel cell vehicles, a fuel cell, an electrolyzer, a hydrogen tank, a boiler, an inverter, a rectifier, and a heat storage system. A novel model is developed to estimate the uncertainty associated with the power consumption of PHEVs during trips using information gap decision theory (IGDT)under risk-averse and risk-seeking strategies. Simulation results demonstrate that the proposed method maximizes the objective function under the risk-neutral and risk-averse strategies, while minimizing the objective function under the risk-seeking strategy. Results from the modeling show that considering the uncertainty associated with the power consumption of PHEVs using IGDT enables the energy hub operator to make appropriate decisions when optimizing the operation of the energy hub against possible changes in power consumption of PHEVs

A simplified method for predicting the settlement of circular footings on multi-layered geocell-reinforced non-cohesive soils

Multiple layers of geosynthetic reinforcement, placed below foundations or in the supporting layers of road pavements, can improve section performance through several mechanisms, leading to reduction in stresses and deformations. This paper aims to present a new analytical solution, based on the theory of multi-layered soil system to estimate the pressure–settlement response of a circular footing resting on such foundations, specifically those containing geocell layers. An analytical model that incorporates the elastic characteristics of soil and reinforcement is developed to predict strain and confining pressure propagated throughout an available multi-layer system, is proposed. A modified elastic method has been used to back-calculate the elastic modulus in terms of strain and confining pressure with materials data extracted from triaxial tests on unreinforced and geocell-reinforced soil samples. The proposed model has been validated by results of plate load tests on unreinforced and geocell-reinforced foundation beds. The comparisons between the results of the plate load tests and proposed analytical method reflected a satisfactory accuracy and consistency, especially at expected, practical, settlement ratios. Furthermore, to have a better assessment of geocell-reinforced foundations' behaviour, a parametric sensitivity has been studied. The results of this study show that the higher bearing pressure and lower settlement were achieved when number of geocell layer, secant modulus of geocell and the modulus number of the soil were increased. These results are in-line with the experimental results of the previous researchers. The study also permits the limits of effective and efficient reinforcement to be determined

Experimental Evaluation of Geocell and EPS Geofoam as Means of Protecting Pipes at the Bottom of Repeatedly Loaded Trenches

© 2020 American Society of Civil Engineers. With growing populations and continuing urban development, embedding pipes in the ground that are then overrun by traffic is inevitable. This paper describes full-scale prototype tests on high-density polyethylene (HDPE) flexible pipes (of 250 mm diameter), buried at shallow depth, under simulated traffic loading. The paper studies the effect of surface load diameter (0.6×, 0.8×, and 1× pipe diameter) and the amplitude of repeated load (400 or 800 kPa) on pipe behavior. The effects of expanded polystyrene (EPS) geofoam blocks of various densities and also of geocells as a three-dimensional (3D) reinforcement in reducing the pressure transferred to the pipe, the deformation of the pipe, and the surface settlement of the backfill were investigated. The results show that, with an increase in loading surface diameter, the pipe's vertical diametral strain, the pressure transferred to the pipe, and the surface settlement grow significantly, irrespective of applied pressure. Using an EPS block over the pipe increases the soil settlement but reduces transferred pressure onto the pipe and, consequentially, results in lower pipe deformations. The increase in density of an EPS block helps improve response but was still found to be insufficient to prevent increase in surface deflections. The use of geocell reinforcement beneath the loading surface not only reduces the pressure transferred to the pipe and decreases its deformation but also significantly negates the tendency of the EPS block to increase the soil surface settlement. Thus, a geocell reinforcement layer placed over two EPS geofoam blocks (with total thickness 0.3× and width 1.5× the pipe diameter) all above a pipe buried at a depth of twice the pipe diameter, was found to deliver an acceptable, stable response. By these means, the vertical pipe strain, transferred pressure over the pipe, and soil surface settlement were reduced, respectively, by 0.45, 0.37, and 0.53× those obtained for the comparable unmodified buried pipe installation and are within allowable limits

Behavior of expanded polystyrene (EPS) blocks under cyclic pavement foundation loading

This study introduces a mechanism for initial assessment and future development to improve understanding of expanded polystyrene (EPS) behavior as a super-lightweight material for road construction. Large scale cyclic plate load tests on model pavements were performed. The effect of several factors including thickness of soil, thickness of subsequent EPS layers and density of EPS on the surface deformations, resilient modulus (Mr) and interlayer pressure transfer were investigated. The results indicated that, compared to a covering soil layer of 300 mm, the rut depth on the loading surface reduced by 13.5% and 40.8% when the soil thickness was increased by 33% and 100%, respectively. With a constant soil thickness, increasing the thickness of an upper (denser) EPS layer with respect to a bottom (softer) EPS layer, from 200 mm to 600 mm, would only result in a 20% decrease in the peak settlements after loading. Resilient modulus of the system was found to be dependent on soil thickness. A designer can choose an appropriate resilient modulus assuming the soil-EPS composite acts as subgrade or subbase. In order to extend the results to a wider range of geofoams, soils and layer thicknesses, a simple stress analysis method was also trialed

Quality of Life Among Veterans With Chronic Spinal Cord Injury and Related Variables

Background: In recent decades, the incidence of spinal cord injuries has increased. In a systemic review on epidemiology of traumatic spinal cord injury in developing countries reported 25.5/million cases per year. Objectives: To assess the quality of life (QOL) of the veterans among Iran-Iraq war with chronic spinal cord injuries (SCI) and to evaluate long-term impressions of SCI on their quality of life. Patients and Methods: Fifty-two veterans, all male, with chronic spinal cord injury from Iran-Iraq war (1980-1988) were interviewed and examined. The mean age of veterans at the time of interview was 49.3 years (38 to 80 years). Veterans were assessed by using a 36-item short-form (SF-36), hospital anxiety and depression scale (HADS) and the Barthel index. The presence or absence of pressure sores and spasticity were documented as well. Results: The mean age of veterans at the time of study was 49.3 years. Pearson's correlation test showed that depression and anxiety have a reverse association with mental component summary (MCS) scale and physical component summary (PCS) scale scores, respectively. Regression analysis showed a negative effect of depression and pressure sore on PCS. Moreover, no association was found between the duration of injury and age with quality of life. Conclusions: Lower QOL was found among veterans with chronic SCI. More researches on health-related quality of life (HRQOL) are needed to give us a better understanding of changes in life of patients with SCI and the ways to improve them

Experimental and numerical investigation of the uplift capacity of plate anchors in geocell-reinforced sand

Plate anchors are frequently used to provide resistance against uplift forces. This paper describes the reinforcing effects of a geocell-reinforced soil layer on uplift behavior of anchor plates. The uplift tests were conducted in a test pit at near full-scale on anchor plates with widths between 150 and 300 mm with embedment depths of 1.5–3 times the anchor width for both unreinforced and geocell-reinforced backfill. A single geocell layer with pocket size 110 mm × 110 mm and height 100 mm, fabricated from non-perforated and nonwoven geotextile, was used. The results show that the peak and residual uplift capacities of anchor models were highest when the geocell layer over the anchor was used, but with increasing anchor size and embedment depth, the benefit of the geocell reinforcement deceases. Peak loads between 130% and 155% of unreinforced conditions were observed when geocell reinforcement was present. Residual loading increased from 75% to 225% that of the unreinforced scenario. The reinforced anchor system could undergo larger upward displacements before peak loading occurred. These improvements may be attributed to the geocell reinforcement distributing stress to a wider area than the unreinforced case during uplift. The breakout factor increases with embedment depth and decreased with increasing anchor width for both unreinforced and reinforced conditions, the latter yielding larger breakout factors. Calibrated numerical modelling demonstrated favorable agreement with experimental observations, providing insight into detailed behavior of the system. For example, surface heave decreased by over 80% when geocell was present because of a much more efficient stress distribution imparted by the presence of the geocell layer

In Vitro and in Vivo Effectiveness of Carvacrol, Thymol and Linalool against Leishmania infantum

Background: One of the most important causative agents of visceral leishmaniasis (VL) is Leishmania infantum, which is mainly spread by Phlebotomus and Lutzomyia sandflies in the Old and New World, respectively. Novel and effective drugs to manage this neglected vector-borne disease are urgently required. In this study, we evaluated the toxicity of carvacrol, thymol and linalool, three common essential oil constituents, on amastigotes and promastigotes of L. infantum. Methods: in vitro experiments were performed by 24 h MTT assay. Carvacrol, thymol and linalool at concentrations ranging from 1.3 to 10 µg/mL were tested on promastigotes of L. infantum. For in vivo test, two groups of hamsters (Mesocricetus auratus) received 100 mg/kg of body weight/day of carvacrol and thymol as intraperitoneal injection on day 7 post-infection, followed by a 48 h later injection. The third group was treated with the glucantime as standard drug (500 mg/kg) and the last group (control) just received normal saline. On the 16th day, the number of parasites and histopathological changes in liver and spleen were investigated. Results: 24 h MTT assay showed promising antileishmanial activity of thymol and carvacrol, with IC50 values of 7.2 (48 µM) and 9.8 µg/mL (65 µM), respectively. Linalool at all concentrations did not affect L. infantum promastigote viability. In vivo toxicity data of carvacrol and thymol showed that the former at 100 mg/kg was the safest and most effective treatment with little side effects on the liver. Conclusions: Overall, thymol and carvacrol are highly promising candidates for the development of effective and safe drugs in the fight against VL

Mixing in a swarm of bubbles rising in a confined cell measured by mean of PLIF with two different dyes

The present contribution reports an experimental study of the mixing of a passive scalar of very low diffusivity in a homogeneous swarm of inertial bubbles rising in a thin gap. A patch of fluorescent dye is injected within the swarm, and we observe the evolution of its mass in a given region of observation. We analyse the effect of the liquid agitation on the mixing mechanisms varying the gas volume fraction from 1.3 to 7.5 %, while the Reynolds number of the bubbles, Re = 450, their Weber number, We = 0.7, and the gapto-bubble diameter ratio, w/d = 0.25, are kept approximately constant. Here, the in-plane local mass of dye is measured by using a two-dyes planar laser-induced fluorescence (PLIF) technique that has been adapted to fix the problem of multiple light reflections at the bubble interfaces. Indeed, they induce both temporal and spatial variations of the captured light intensity that are superimposed to the effective fluorescence signal and prevent from using a standard PLIF technique. The analysis of the instantaneous concentration fields reveals the dominant role of the bubble wakes in the scalar transport. It is shown that mixing in this planar confined geometry is very efficient and enhanced by the increasing gas volume fraction. The present study also highlights that the mixing is not governed by a Fickian law of diffusion

Minería de datos para el descubrimiento de patrones en enfermedades respiratorias en Bogotá, Colombia

Trabajo de InvestigaciónEl presente proyecto se basa en la aplicación de minería de datos mediante el algoritmo de clustering K- means que permita la generación de un modelo descriptivo con el análisis de los datos y con el objetivo de identificar posibles comportamientos en enfermedades respiratorias en la ciudad de Bogotá. El conjunto de clústeres generados por la herramienta RapidMiner es la recopilación de datos de un periodo de cinco años de 2012 a 2016, en donde se contemplan el número de casos asociados a 184 diagnósticos de enfermedades respiratorias y la edad de los pacientes corresponde de 0 a 5 años.Trabajo de Investigación1. GENERALIDADES 2. OBJETIVOS 3. JUSTIFICACIÓN 4. DELIMITACIÓN 5. MARCO REFERENCIAL 6. METODOLOGÍA 7. FUENTES DE EXTRACCIÓN Y SUS VARIABLES 8. DISEÑO 9. SELECCIÓN DE ALGORITMOS DE CLUSTERING 10. RECONOCER PATRONES A PARTIR DE LA INFORMACIÓN RECOPILADA 11. CONCLUSIONES 12. TRABAJOS FUTUROS 13. REFERENCIAS BIBLIOGRÁFICAS 14. ANEXOSPregradoIngeniero de Sistema