214 research outputs found
Air flow distribution in and around a single-sided naturally ventilated room
No full textThis paper reports on the initial findings of the EPSRC project on rule-based control in naturally ventilated buildings which led to Marjanovic's PhD thesis, supervised by Eftekhari. Marjanovic is the second author
Liberty and Security :An Interactive Model
No full textLiberty and Security :An Interactive Model Asghar Eftekhari* (Received: 2014/April/7 – Accept: 2014/Octobr/27) Abstract Virtues have the main rule in managing Social and Political Life; hence, the following question is important: If there be an opposition between different Virtues, which one should – or could – be preferred? In this paper, author tries to analyze the relationship between Liberty and Security, and suggest two models in this regard. This two models developed by Islamic- Iranian discourse can be labeled Negative and positive. Security is the main virtue in Negative Model but Liberty is the major one, in the Positive Model. Therefore, author has designed a complex model which is biased on two different principles: Power (in negative model) and Satisfaction (in positive model). * Associate Professor of Political Science at Imam Sadiq University. ([email protected]
The Effect of Eight-Eeek Kegel Training on Quality of Life in Postmenopausal Females with Urinary Incontinence
No full textIntroduction: Urinary incontinence (UI) is the leakage of urine which is often uncontrollable and can negatively impact on the quality of life (QoL). The aim of this study was to determine the effects of an eight-week of Kegel exercise as a complementary therapy on QoL in postmenopausal females with UI.
Methods: The study design was a quasi-experimental pre-test post-test with a control group trial. The participants were Iranian women aged between 60 to 95 years with UI problems referring to medical centers in Najafabad city in Isfahan Province, Iran. Twenty four female UI patients were recruited and randomly divided into Kegel exercise (n = 12) and control group (n = 12). The Kegel group received exercise three times a week for eight-week, and the control group continued their routine life. The Questionnaire for Urinary Incontinence Diagnosis and the World Health Organization Quality of Life questionnaire were used for data collection. The variables were measured before and after the Kegel protocol in both groups. Descriptive statistics and analysis of covariance were used to assess variable differences between groups (p < 0.05).
Results: The mean age of UI patients was 70.83 ± 7.61 years old. Analysis of variance demonstrated a significant decrease in stress urinary incontinence symptoms (F = 61.88, p = 0.01), urge urinary incontinence symptoms (F = 111.56, p = 0.01), and UI symptoms (F = 88.20, p = 0.01), and significant increase in physical health (F = 28.93, p = 0.01), psychological health (F = 15.35, p = 0.01), social relationships (F = 18.83, p = 0.01), environment health (F = 155.51, p = 0.01), QoL (F = 132.07, p = 0.01) in Kegel exercise group.
Conclusion: Kegel exercise can be an effective complementary therapy for improving QoL in postmenopausal female suffering from UI. Healthcare providers should consider recommending Kegel exercise as part of comprehensive treatment approach for postmenopausal female with UI to help alleviate symptoms and enhance their overall QoL.
Corresponding Author: Elham Eftekhari
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In-Cylinder Pressure Sensors to combustion control and optimization : a systems and strategy perspective
No full textThesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (leaves 119-124).In-Cylinder Pressure Sensors (ICPS) today are close to satisfying the robustness, performance and cost requirements for application to closed loop control and monitoring of production automotive engines. Using the Robust Design framework as a compass, this thesis first checks the evidence for emergence followed by tracking the evolution of the sensor component itself and its application to robust closed loop control of the combustion process in internal combustion engines. After identifying the potential system level impact of the emerging ICPS technology, System Dynamic and Technology Strategy frameworks are used to find spillover triggers and to recommend a number of strategic options to generate and capture value for integrated system solution providers so that they can beat the very stable status quo that persists in the slow and mature prime mover industries. In addition, Chapter 2 gives a data driven method for identifying the Skills needed for suppliers to realize the above recommendations. This method is based on collective intelligence of 690 experienced professionals with 20 years of work experience on average from 40 targeted companies, representing a large body of engineering and managerial experience in battling complex engineering system hurdles. This approach is more effective than blindly copying the prominent integrated system solution providers or OEM's, because a side effect of long term incremental innovation in the mature prime mover industry is that the underlying reasons for their success is ingrained in their "tacit knowledge" and "organizational furniture" and hence not explicitly understood.by Kamran Eftekhari Shahroudi.S.M
Low Emission Conversion of Fossil Fuels with Simultaneous or Consecutive Storage of Carbon Dioxide
No full textThis thesis evaluates the possibility of using underground coal gasification with a low CO2 footprint. The thesis consists of two parts. In the first part, by using the concept of exergy, a framework was constructed through which the practicality (feasibility) of an energy conversion/extraction method can be systematically evaluated. This framework, based on exergy analysis and cumulative degree of perfection, is described by analyzing a low emission underground coal gasification (UCG) process. For the evaluation of energy conversion processes we introduce a new concept, viz. recovery factor, which is a better indicator of the exergetic viability of a conversion process than the traditionally used efficiency factors. In the second part, various issues related to the aquifer storage of CO2 are studied. Aquifer storage is considered as an option for low emission fossil fuel utilization. Each chapter is summarized as follows: In chapter 2, various options are considered to reduce CO2 emissions when utilizing deep coal by applying UCG, i.e., (1) in combination with carbonation of synthetic minerals (CaO), (2) conventional UCG followed by ex-situ separation of CO2 and (3) upgrading the product gas using naturally occurring minerals (wollastonite). A chemical equilibrium model was used to analyze the effect of the process parameters on product composition and use it for an exergy (useful energy) analysis. The result is presented in terms of theoretical (ideal unit operations), practical (state of the art technology), and zero-emission (applying current CO2 capture and sequestration (CCS) to all sources of CO2 emission) recovery factors. The results show that underground gasification of deep coal can optimally extract 52-68 % of the coal chemical exergy, but zero-emission extraction gives a negative recovery factor, indicating that it is not practical with the current state of the art CCS technology. Using in-situ CaO, which will enhance the H2 production, is theoretically feasible with a recovery factor around 80%, but is not exergetically feasible with the current state of technology, i.e. with a negative practical recovery factor. Ex-situ upgrading of the conventional UCG product gas with wollastonite is exergetically feasible for both practical and zero-emission cases according to the equilibrium model. Slow attainment of chemical equilibrium makes its application questionable. In chapter 3, based on recent successful low-pressure underground coal gasification pilot experiments that use alternating injection of air (oxygen) and steam, a mathematical model is written to evaluate the potential of alternating injection UCG in large scale hydrogen production. This chapter extends an existing steady state model to a transient model that can describe an alternating injection of air and steam for deep thin coal layers. The model includes transient heat conduction, where the produced heat during the air injection stage is stored in the coal and surrounding strata. The stored heat is subsequently used in the endothermic gasification reactions during the steam injection. Comparison of the results with field data show that product composition and temperature oscillation can be predicted with a reasonable accuracy. The stored heat can deliver additional energy that can maintain the gasification during the steam injection period for a limited time. During the steam injection cycle, at low pressure the volumetric flow and the hydrogen content of the product gas are both high, but at higher pressures while the hydrogen composition is still high, the coal conversion rate decreases considerably. The exergy analysis confirms that alternating injection of air/steam describes a practical process for UCG at low pressure. However, injection of a mixture of steam and oxygen results in a practical recovery factor of 50% and produces 0.15 kg CO2 per MJ of exergy, which is higher than the practical recovery factor (40%) of the alternating injection process, which produces 0.12 kg CO2 / MJ of exergy. In the second part of the thesis, two issues related to aquifer storage of CO2 are discussed: injectivity problems due to salt precipitation, and storage capacity and long term storage due to dissolution of CO2 in water. In chapter 4, the negative saturation (NegSat) method, which is a combination of negative flash and multicomponent single/two-phase flow in porous media, is studied. It has been shown to be beneficial in numerical simulations of phase appearance/disappearance for mixtures that consist of volatile components, i.e., components that appear in both liquid and gas phases. The method is extended to a three phase system of CO2 -water-NaCl, in which NaCl appears as a nonvolatile dissolved component (NaCl) and as an immobile precipitated solid phase. The extended method is of practical use to assess carbon dioxide storage options. A detailed thermodynamic analysis of the NegSat method is given and the possibility to extend it to injection in brine aquifers is demonstrated. Precipitation of salt occurs due to evaporation of water into supercritical CO2 . Precipitation decreases the permeability near the injection well forming a dried-out zone. With the ensuing permeability change, the injection pressure needs to be increased to maintain the CO2 injection rate, which requires more compression energy and hence influences the exergetic viability of the carbon dioxide sequestration process.. To address this issue, first a thermodynamic model is optimized to predict the phase behavior of the CO2 -water-NaCl system with reasonable accuracy. Then the NegSat method for two-phase flow is modified to include salt precipitation. The model is solved to analyze the effect of various physical parameters on the injectivity of CO2 . Finally an exergy analysis is performed to quantify the effect of salt precipitation on the compression power requirement for CO2 injection into high pressure-high temperature-high salinity aquifers. Exergetic applicability of carbon capture and sequestration for low emission carbon dioxide fuel consumption, can presently only be achieved if the energy-intensive step of nitrogen-CO2 separation prior to injection can be avoided. In chapter 5, the enhanced mass transfer of CO2 in water for a CO2 saturated layer on top of a water saturated porous medium is studied experimentally and theoretically. Dissolution of carbon dioxide in water has a large effect on the capacity of an aquifer for carbon dioxide storage. Without the dissolution effect the storage capacity of aquifers is low. A high pressure cylinder with a length of 0.5 m and a diameter of 0.15 m is used in pressure decay experiments. The relatively large size of the vessel minimizes the pressure measurement errors that can happen due to temperature fluctuations and small leakages. The experimental results were compared to the theoretical result in terms of onset time of natural convection and rate of mass transfer of CO2 in the convection dominated process. In addition a non-isothermal multicomponent flow model in porous media is solved numerically to study the effect of the heat of dissolution of CO2 in water on the rate of mass transfer of CO2 . The effect of the capillary transition zone on the rate of mass transfer of CO2 is also studied theoretically. The simulation results including the effect of the capillary transition zone show a better agreement with experimental results compared to the simulation result without considering a capillary transition zone. The simulation results also show that the effect of heat of dissolution on the rate of mass transfer is negligible. The overall conclusion is that, for the current state of technology, use of underground coal gasification with a similar carbon foot print as the use of natural gas is not possible. It is to be expected that technological developments will make it possible in the future to use coal with a low carbon footprint.Geoscience & EngineeringCivil Engineering and Geoscience
Experimental And Theoretical Investigation Of Natural Convection In CCS: Onset Time, Mass-Transfer Rate, Capillary Transition Zone, And Heat Of Dissolution
No full textWe study the enhanced mass transfer of CO2 in water for a CO2 saturated layer on top of a water saturated porous medium, experimentally and theoretically. A relatively large experimental set-up with a length of 0.5 m and a diameter of 0.15 m is used in pressure decay experiments to minimize the error of pressure measurement due to temperature fluctuations and small leakages. The experimental results were compared to the theoretical result in terms of onset time of natural convection and rate of mass transfer of CO2 in the convection dominated process. In addition, a non-isothermal multicomponent flow model in porous media, is solved numerically to study the effect of the heat of dissolution of CO2 in water on the rate of mass transfer of CO2. The effect of the capillary transition zone on the rate of mass transfer of CO2 is also studied theoretically. The simulation results including the effect of the capillary transition zone show a better agreement with experimental results compared to the simulation result without considering a capillary transition zone. The simulation results also show that the effect of heat of dissolution on the rate of mass transfer is negligibleGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Reservoir Engineerin
TGF-beta1 codon 10 and codon 25 polymorphisms in workers of sour and sweet natural gas refineries and their relations to lung functional parametrs
No full textAntioxidant properties of allium turcicum Özhatay & cowley plant extract, its effects on the proliferation and migration of cancer cells
No full textCancer is a type of non-communicable disease that is responsible for numerous deaths worldwide. Cancer incidence and mortality rates are on the rise due to a combination of factors, such as a growing population, aging, and poor dietary habits. The Allium turcicum Özhatay & Cowley plant is an endemic plant in the area where it grows and is consumed by the public due to its various benefits. This endemic plant, which generally grows in high-altitude regions, is sold in bunches because it is costly, mixed with rock salt, crushed into powder, and consumed as a spice. The cytotoxic and growth-inhibitory effects of A. turcicum Özhatay & Cowley herb extract on human glioblastoma U373 cells, human colorectal carcinoma cell HCT-116, and healthy HUVEC cell lines were determined by the MTT method. After 24 and 48 h of application, logIC50 values in HUVEC, HCT-116, and U373 cells were defined as 3.737, 3.765; 3.513, 3.696, 4.476, and 4.104 μg/mL, respectively. We conducted a cell migration experiment to study the A. turcicum Özhatay & Cowley Extract (ATÖCE) impact on cancer cells’ metastatic behavior. Our findings indicate that ATÖCE has an inhibitory effect on the migration potential of the cells used in the study. We conducted experiments using DPPH, ABTS, CUPRAC, and total phenolic content to assess the antioxidant properties of ATÖCE. The findings from the antioxidant activity experiments revealed an activity level of 0.20 ± 0.046 at IC50. Additionally, the total phenolic content was measured to be 0.26 ± 0.044 mg GAE/g. Copyright © 2024 İPEK, Baran, Cebe, Ahmadian, Eftekhari and Baran
Exergy analysis of the use of geothermal energy and carbon capture, transportation and storage in underground aquifers
No full textAt the moment global climate change is one of the most prominent environmental and energy issues of our life time. Currently CO2 levels in the atmosphere stand at 387 ppm, almost 40% higher since the start of the industrial revolution and the highest for at least the last 650,000 years. About 96% of these carbon emissions are the result of using fossil fuels. Another problem is that the fossil fuel reserves will be exhausted within 200 years and the nuclear energy within 260 years. Something has to be done to stop the addiction of fossil fuels and carbon dioxide emissions! However investing in renewable energy is still expensive but high energy prices, CO2 emissions, rising temperatures, fossil fuels depletion and the demand to be less dependent on other countries makes it more and more attractive to invest in renewable energy, like solar energy, wind energy, biomass, geothermal energy, tidal power and hydro power. Not all renewable energy sources are suitable in the Netherland. Geothermal energy, still unknown by a lot of people, has a very good potential to succeed in the Netherlands. The average temperature of the Dutch subsurface at a depth of 2,000 meters is around 75 – 80 °C. This energy is very suitable to heat houses, afterwards the rest heat can be used to heat low heat demanding facilities like swimming pools and greenhouses. In spite of the good potential, geothermal energy is still used on a small time scale in the Netherlands. Hopefully DAP can make a change in this by making more people aware that geothermal energy has a great potential for the Netherlands. The Netherlands has a geothermal potential of 90,000 PJ in heat. The benefits of geothermal energy are that it is clean and available 24 hours a day, 365 days a year. Also geothermal power plants have average availabilities of 90% or higher, compared to 75% for coal power plants. The greenhouse gas emissions of the geothermal plants are only 91 gCO2/kWh, this is very low compared to other fuels. The annual Dutch CO2 emission is nearly 180 Mt CO2 at present, of which approximately 100 Mt CO2/year emitted by the energy and manufacturing industry. The biggest emitters are large point sources like the power generation sector and large energy-consuming industries like oil and gas processing, iron and steel, cement and chemicals production. CCS can lower the emissions from the large point sources by capturing the carbon dioxide. CCS is not a new technology, this proven technique is already used for nearly 100 years for industrial purposes or to increase oil or gas production. CCS technology can reduce carbon dioxide emissions from large industrial sources and coal-fired power stations by approximately 85 - 90% depending on the used type of capture technology. Also transportation of CO2 is not a new technology in the Netherland because there is already a pipeline of 85 km from the Shell refinery in Pernis to greenhouses in the Westland area. However, large-scale CCS will require a new transportation infrastructure to link sources and sinks. In densely populated countries such as the Netherlands this can become a considerable challenge, think of Barendrecht. Even though the Netherlands has a very good storage potential there is a spatial mismatch between CO2 sources and sinks. When a new energy source is discovered the first and most important thing to know is how much energy (quantity) can be extracted from this source. But what we really need to know is the work potential (quality) of this energy source, in our case a geothermal well beneath the TU Delft. Work potential is the amount of energy which can be extracted as useful work, this property is called exergy. The maximum available power from the DAP geothermal reservoir is 0.66 MW and is obtained at a flow rate of 180 m3. It is not smart to increase the production rate above 200 m3 because the losses are increasing faster than the extra gained exergy. The invested energy in materials and drilling are minor compared to the energy needed for capture and compression. Over 94% of the total energy demand is needed to capture the CO2 over a life-time of 30 years.Section Applied Geophysics and PetrophysicsCivil Engineering and Geoscience
Development and validation of a computer assisted design methodology for gas-turbine-based aircraft engines
No full textAerospace Engineerin
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