Search results for: program performance

Authors: M. Heydari, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 444

Authors: Belkheir Noura, Rabah Kerfah, Boumehani Abdellah

Abstract:

The influence of solidity variations on the aerodynamic performance of H type vertical axis wind turbine is studied in this paper. The wind turbine model used in this paper is the three-blade wind turbine with the symmetrical airfoil, NACA0021. The length of the chord is 0.265m. Numerical investigations were implemented for the different solidity by changing the radius and blade number. A two-dimensional model of the wind turbine is employed. The approach a Reynolds-Averaged Navier–Stokes equations, completed by the K- ώ SST turbulence model, is used. Motion mesh model capability of a computational fluid dynamics (CFD) solver is used. For each value of the solidity, the aerodynamics performances and the characteristics of the flow field are studied at several values of the tip speed ratio, λ = 0.5 to λ = 3, with an incoming wind speed of 8 m/s. The results show that increasing the number of blades will reduce the maximum value of the power coefficient of the wind turbine. Also, for the VAWT with a lower solidity can obtain the maximum Cp at a high tip speed ratio. The effects of changing the radius and blade number on aerodynamic performance are almost the same. Finally, for the validation, experimental data from the literature and computational results were compared. In conclusion, to study the influence of the solidity in the performances of the wind turbine is to provide the reference for the design of H type vertical axis wind turbines.

Keywords: wind energy, darrieus h type vertical axis wind turbine, computational fluid dynamic, solidity

Procedia PDF Downloads 96

Authors: Candra Irawan, David Yudianto, Ahsanu Nadiyya, Dewi Anna Br Sitepu, Hanafi, Erna Styani

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Jelly drink was produced from a combination of both natural and synthetic materials, such as acesulfame potassium (acesulfame-K) as synthetic sweetener material. Acesulfame-K content in jelly drink could be determined by High-Performance Liquid Chromatography (HPLC), but this method needed validation due to having a change on the reagent addition step which skips the carrez addition and comparison of mix mobile phase (potassium dihydrogen phosphate and acetonitrile) with ratio from 75:25 to 90:10 to be more efficient and cheap. This study was conducted to evaluate the performance of determination method for acesulfame-K content in the jelly drink by HPLC. The method referred to Deutsches Institut fur Normung European Standard International Organization for Standardization (DIN EN ISO):12856 (1999) about Foodstuffs, Determination of acesulfame-K, aspartame and saccharin. The result of the correlation coefficient value (r) on the linearity test was 0.9987 at concentration range 5-100 mg/L. Detection limit value was 0.9153 ppm, while the quantitation limit value was 1.1932 ppm. The recovery (%) value on accuracy test for sample concentration by spiking 100 mg/L was 102-105%. Relative Standard Deviation (RSD) value for precision and homogenization tests were 2.815% and 4.978%, respectively. Meanwhile, the comparative and stability tests were tstat (0.136) < ttable (2.101) and |µ1-µ2| (1.502) ≤ 0.3×CV Horwitz. Obstinacy test value was tstat < ttable. It can be concluded that the HPLC  method for the determination of acesulfame-K in jelly drink product by HPLC has been valid and can be used for analysis with good performance.

Keywords: acesulfame-K, jelly drink, HPLC, validation

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Authors: Ladda Thiamwong, Renata Komalasari

Abstract:

Falls are the leading cause of disability and hospitalization in low-income older adults. Fear of falling is present in 20% to 85 % of older adults and has been identified as an independent risk factor of fall risk, activity restriction, and loss of independence. About 12% of American older adults have subjective cognitive decline. Cognitive impairment is also an established factor of fall risk. However, it is unclear whether measures of fear of falling and subjective cognitive decline have the greatest association with fall risk in low-income older adults. The aim of this study was to evaluate the association between fear of falling, subjective cognitive decline-functional performance (SCD-FP), and fall risk using simple screening tools. In this cross-section study, we collected data from community-dwelling older adults 60 years or older in low-income settings in Central Florida, and 86 participants were included in the data analysis. Fear of falling was assessed by the Short Fall Efficacy Scale- International (Short FES-I) with seven items. Subjective cognitive decline-functional performance (SCD-FP) was assessed by a self-reported experience of worsening or more frequent confusion or memory loss in the past 12 months and its functional implications. Fall risk was evaluated by the Centers for Disease Control and Prevention (CDC)'s Stay Independent checklist with 12 items. The majority of participants were female, and more than half of the participants were African American. More than half of the participants had a higher school degree or higher, and less than 20% had no financial problems. Less than 30% of the participants perceived their general health as very good- excellent. More than half of the participants lived alone, and less than 15% lived with a partner or spouse. About 60% of the participants had hypertension, 40% had diabetes, 16% had cancer, and 50% had arthritis. About 30% of the participants had difficulty walking up ten steps without resting, more than 40% felt unsteady when walking, and 30% had been advised to use a cane or walker to get around safely. Regression analysis showed that fall risk was associated with fear of falling ( = .524, p <.001) and subjective cognitive decline-functional performance ( = .465, p =.027). The structure coefficient showed that fear of falling (rs2 = .922) was a stronger predictor of fall risk than subjective cognitive decline-functional performance (rs2= .200). Fear of falling and subjective cognitive decline-functional performance are growing public health issues, and addressing those issues is a public priority. Proactive screening for fear of falling and subjective cognitive decline-functional performance is critical in fall prevention. A combination of all three self-reported tools (Short FES-I, SCD-FP, and CDC's Stay Independent checklist) takes less than 5 minutes to complete. Primary care providers or public health professionals should consider including these tools to screen fear of falling and subjective cognitive decline-functional performance as part of fall risk assessment, especially in low-income settings. Thus, encouraging older adults and healthcare professionals to discuss fear of falling, subjective cognitive decline, and fall risk during routine medical office visits.

Keywords: falls, fall risk, fear of falling, cognition, subjective cognitive decline, low-income, older adults, community, screening, nursing, primary care

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Authors: Bouchra Nadji, Elaid Bouchetob

Abstract:

PV systems are common in residential and industrial settings because of their low, upfront costs and operating costs throughout their lifetimes. Buck or boost converters are used in photovoltaic systems, regardless of whether the system is autonomous or connected to the grid. These converters became less appealing because of their low efficiency, inadequate power density, and use of silicon for their power components. Traditional devices based on Si are getting close to reaching their theoretical performance limits, which makes it more challenging to improve the performance and efficiency of these devices. GaN and SiC are the two types of WBG semiconductors with the most recent technological advancements and are available. Tolerance to high temperatures and switching frequencies can reduce active and passive component size. Utilizing high-efficiency dc-dc boost converters is the primary emphasis of this work. These converters are for photovoltaic systems that use wave energy.

Keywords: component, Artificial intelligence, PV System, ANN MPPT, DC-DC converter

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Authors: K. Rusnakova, D. Gerych, M. Stehlik

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Postural stability is a complex process involving actions of biomechanical, motor, sensory and central nervous system components. Numerous joint systems, muscles involved, the complexity of sporting movements and situations require perfect coordination of the body's movement patterns. To adapt to a constantly changing situation in such a dynamic environment as physical performance, optimal input of information from visual, vestibular and somatosensory sensors are needed. Combat soldiers are required to perform physically and mentally demanding tasks in adverse conditions, and poor postural stability has been identified as a risk factor for lower extremity musculoskeletal injury. The aim of this study is to investigate whether some personality traits are related to the performance of static postural stability among soldiers of combat troops. NEO personality inventory (NEO-PI-R) was used to identify personality traits and the Nintendo Wii Balance Board was used to assess static postural stability of soldiers. Postural stability performance was assessed by changes in center of pressure (CoP) and center of gravity (CoG). A posturographic test was performed for 60 s with eyes opened during quiet upright standing. The results showed that facets of neuroticism and conscientiousness personality traits were significantly correlated with measured parameters of CoP and CoG. This study can help for better understanding the relationship between personality traits and static postural stability. The results can be used to optimize the training process at the individual level.

Keywords: neuroticism, conscientiousness, postural stability, combat troops

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Authors: Habib Gorine, Rabia Saleh

Abstract:

Mobile Ad-Hoc Networks are the special type of wireless networks which share common security requirements with other networks such as confidentiality, integrity, authentication, and availability, which need to be addressed in order to secure data transfer through the network. Their routing protocols are vulnerable to various malicious attacks which could have a devastating consequence on data security. In this paper, three types of attacks such as selfish, gray hole, and black hole attacks have been applied to the two most important routing protocols in MANET named dynamic source routing and ad-hoc on demand distance vector in order to analyse and compare the impact of these attacks on the Network performance in terms of throughput, average delay, packet loss, and consumption of energy using NS2 simulator.

Keywords: MANET, wireless networks, routing protocols, malicious attacks, wireless networks simulation

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Authors: Dusittorn Ngamying

Abstract:

This investigation of Mon Dance is focused on using in Pathum Thani Province’s tradition and has the following objectives: 1) to study the background of Mon dance in Pathum Thani Province; 2) to study Mon dance in Pathum Thani Province; 3) to study of using Mon Dance in Pathum Thani province’s tradition. This qualitative research was conducted in Pathum Thani provinces (the central of Thailand). Data was collected from a documentary study and field data by means of observation, interview and group discussion. Workshops were also held with a total of 100 attendees, comprised of 20 key informants, 40 casual informants and 40 general informants. Data was validated using a triangulation technique and findings are presented using descriptive analysis. The results of the studied showed that the historical background of Mon dance in Pathum Thani Province initiated during the war evacuation from Martaban (south of Burma) to settle down in Sam Khok, Pathum Thani Province in Ayutthaya period to Rattanakosin. The study found that Mon dance typically consists of 12 dancing process. The melodies have 12 songs. Piphat Mon (Mon traditional music ensemble) was used in the performance. The costume was dressed on Mon traditional. The performers were 6-12 women and depending on the employer’s demands. Length of the performance varied from the duration of music orchestration. Rituals and Customs were paying homage to teachers before the performance. The offerings were composed of flowers, incense sticks, candles, money gifts which were well arranged on a tray with pedestal, and also liquors, tobaccos and pure water for asking propitiousness. To using Mon Dance in Pathum Thani Province’s tradition, was found that it commonly performed in the funeral ceremonial tradition at present because the physical postures of the performance were graceful and exquisite as approved conservative. In addition, the value since the ancient time had believed that Mon Dance was the sacred thing considered as the dignity glorification especially for funeral ceremonies of the priest or royal hierarchy classes. However, Mon dance was continued to use in the traditions associated with Mon people activities in Pathum Thani Province, for instance, customary welcome for honor guest and Songkran Festival.

Keywords: Mon dance, Pathum Tani Province, tradition, triangulation technique

Procedia PDF Downloads 592

Authors: Michelle V. Tomczak, Reyhaneh Bakhtiari, Aaron Granley, Anthony Singhal

Abstract:

Objective: Cannabis and cocaine are associated with a range of mental and physical effects that can impair aspects of human behavior. Driving is a complex cognitive behavior that is an essential part of everyday life and can be broken down into many subcomponents, each of which can uniquely impact road safety. With the growing movement of jurisdictions to legalize cannabis, there is an increased focus on impairment and driving. The purpose of this study was to identify driving-related cognitive-performance deficits that are impacted by recreational drug use. Design and Methods: With the assistance of law enforcement agencies, we recruited over 300 participants under the influence of various drugs including cannabis and cocaine. These individuals performed a battery of computer-based tasks scientifically proven to be re-lated to on-road driving performance and designed to test response-speed, memory processes, perceptual-motor skills, and decision making. Data from a control group with healthy non-drug using adults was collected as well. Results: Compared to controls, the drug group showed def-icits in all tasks. The data also showed clear differences between the cannabis and cocaine groups where cannabis users were faster, and performed better on some aspects of the decision-making and perceptual-motor tasks. Memory performance was better in the cocaine group for simple tasks but not more complex tasks. Finally, the participants who consumed both drugs performed most similarly to the cannabis group. Conclusions: Our results show distinct and combined effects of cannabis and cocaine on human performance relating to driving. These dif-ferential effects are likely related to the unique effects of each drug on the human brain and how they distinctly contribute to mental states. Our results have important implications for road safety associated with driver impairment.

Keywords: driving, cognitive impairment, recreational drug use, cannabis and cocaine

Procedia PDF Downloads 126

Authors: Nor Kalsum M. Isa, Mohd Yazid M. Yunos, Anuar Alias, Mazdi Marzuki, Kamarul Ismail, Mohd H. Ibrahim

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Green building is an emerging concept with the ultimate target to achieve sustainable development by integrating sustainability goals and principles into project development. Basically, a green building is a building that is designed, constructed and operated to boost environmental, economic, health and productivity performance over conventional buildings. The buildings have been proven to be successful in contributing towards sustainability and project success. The purpose of this study was to determine the benefits of sustainability application in building projects, looking towards project success from the perspective of Malaysian key project stakeholders. The study also aimed to explore the establishment of sustainability goals in the green building projects in Malaysia. The Triple Bottom Line (TBL) Concept of Sustainability was used as the foundation theoretical framework. Surveys, interviews and multiple case study methods were employed. A sample of 188 Malaysian building project stakeholders was selected for questionnaire surveys, and 15 stakeholders from three award-winning green building projects in Malaysia were involved in the interviews. The study found that the majority of the respondents were less aware that the sustainability integration in the building project can significantly affect cost reduction, schedule effectiveness and stakeholders’ satisfaction with the performance of buildings as at the same level as the quality performance. Of the four sustainability goals, the environmental aspect was given more priority than others in the development of the green building projects.

Keywords: green building, sustainability, project stakeholders, Malaysia

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Authors: Abdul-Hakeem Olatunji Abiola, A. E. Adeniran, A. O. Ajimo, A. B. Lamilisa

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Introduction: Conventional wastewater treatment technology has been found to fail in developing countries because they are expensive to construct, operate and maintain. Constructed wetlands are nowadays considered as a low-cost alternative for effective wastewater treatment, especially where suitable land can be available. This study aims to evaluate the performance of the constructed wetland vegetated with water hyacinth (Eichhornia crassipes) plant for the treatment of wastewater. Methodology: The sub-surface flow wetland used for this study was an experimental scale constructed wetland consisting of four beds A, B, C, and D. Beds A, B, and D were vegetated while bed C which was used as a control was non-vegetated. This present study presents the results from bed B vegetated with water hyacinth (Eichhornia crassipes) and control bed C which was non-vegetated. The influent of the experimental scale wetland has been pre-treated with sedimentation, screening and anaerobic chamber before feeding into the experimental scale wetland. Results: pH and conductivity level were more reduced, colour of effluent was more improved, nitrate, iron, phosphate, and chromium were more removed, and dissolved oxygen was more improved in the water hyacinth bed than the control bed. While manganese, nickel, cyanuric acid, and copper were more removed from the control bed than the water hyacinth bed. Conclusion: The performance of the experimental scale constructed wetland bed planted with water hyacinth (Eichhornia crassipes) is better than that of the control bed. It is therefore recommended that plain bed without any plant should not be encouraged.

Keywords: constructed experimental scale wetland, domestic sewage, treatment, water hyacinth

Procedia PDF Downloads 134

Authors: Data Collete Bob-Manuel

Abstract:

In light of global financial crisis in 2007-2008 various factors including board diversity, succession planning and board evaluation have been identified as essential ingredients in ensuring board effectiveness. The composition and structure of the board is of outmost importance in assessing a board’s ability and success in achieving its objectives. Following the corporate frauds and accounting scandals such as Enron, WorldCom, Parmalat, Oceanic Bank Nigeria and AfriBank Nigeria, there has been a notable amount of research about the effectiveness of the board of directors in the corporate governance of firms. The need to have an effective board cannot be over emphasized as it results in a more stable and thriving company. There has been an overarching need in the business world for a more diverse workforce and board of directors. Big corporations like Texaco, Ford Motors and DuPont have stated how diversity at every level of the workforce including the board of directors has been cited as a vital element for a company to succeed. Developed countries are also seeking for companies to have a more diverse board. For instance Norway has implemented a 60:40 board ratio to all companies. In West Africa, particularly Nigeria, the topic of diversity has received little attention as most studies conducted have focused on the gender aspect of diversity, which results found to have a negative impact on firm performance. This paper seeks to examine four variables of diversity; age, ethnicity, gender and skills to weigh the positive or negative impact the variables have on firm performance, based on evidence from the Nigerian Financial sector. Information used for this study will be gathered from financial statements and annual reports so as to enable the researcher to reflect on past years to know what is being done differently today. The findings of this study will help the researcher to develop a working definition for ethnicity with regards to the West African context where the issue of “tribe” is a sensitive topic.

Keywords: Board of Directors, Board Diversity, Firm Performance, Nigeria

Procedia PDF Downloads 396

Authors: H. Shokouhmand, A. Ghanami

Abstract:

A heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At a hot surface of the heat pipe, the liquid phase absorbs heat and changes to the vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to the liquid phase. Due to gravitational force the liquid phase flows to the evaporator section. In HVAC systems, the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses the heater, humidifier, or dryer is a suitable nominate for the utilization of heat pipes. Generally, heat pipes have three main sections: condenser, adiabatic region, and evaporator. Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In the present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of the heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian-Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances its heat transfer capacity.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 436

Authors: M. Turmanauli, T. Todua, O. Gvaberidze, R. Javakhadze, N. Chkhaidze, N. Khatiashvili

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Background: Mining process has the significant influence on human health and quality of life. In recent years the events in Georgia were reflected on the industry working process, especially minimal requirements of labor safety, hygiene standards of workplace and the regime of work and rest are not observed. This situation is often caused by the lack of responsibility, awareness, and knowledge both of workers and employers. The control of working conditions and its protection has been worsened in many of industries. Materials and Methods: For evaluation of the current situation the prospective epidemiological study by face to face interview method was conducted at Georgian “Manganese Zestafoni Ferroalloy Plant” in 2011-2013. 65.7% of employees (1428 bulletin) were surveyed and the incidence rates of temporary disability days were studied. Results: The average length of a temporary disability single accident was studied taking into consideration as sex groups as well as the whole cohort. According to the classes of harmfulness the following results were received: Class 2.0-10.3%; 3.1-12.4%; 3.2-35.1%; 3.3-12.1%; 3.4-17.6%; 4.0-12.5%. Among the employees 47.5% and 83.1% were tobacco and alcohol consumers respectively. According to the age groups and years of work on the base of previous experience ≥50 ages and ≥21 years of work data prevalence respectively. The obtained data revealed increased morbidity rate according to age and years of work. It was found that the bone and articulate system and connective tissue diseases, aggravation of chronic respiratory diseases, ischemic heart diseases, hypertension and cerebral blood discirculation were the leading among the other diseases. High prevalence of morbidity observed in the workplace with not satisfactory labor conditions from the hygienic point of view. Conclusion: According to received data the causes of morbidity are the followings: unsafety labor conditions; incomplete of preventive medical examinations (preliminary and periodic); lack of access to appropriate health care services; derangement of gathering, recording, and analysis of morbidity data. This epidemiological study was conducted at the JSC “Manganese Ferro Alloy Plant” according to State program “ Prevention of Occupational Diseases” (Program code is 35 03 02 05).

Keywords: occupational health, mining process, morbidity level, cerebral blood discirculation

Procedia PDF Downloads 428

Authors: Jianfang Wang, Xianzhe Chen, Zhuoliang Liu, Cheng-An Tao, Yujiao Li

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Organophosphorus (OPs) pesticide used as insecticides are widely used in agricultural pest control, household and storage deworming. The detection of pesticides needs more simple and efficient methods. One of the best ways is to make electrochemical biosensors. In this paper, an electrochemical enzyme biosensor based on acetylcholine esterase (AChE) was constructed, and its sensing properties and sensing mechanisms were studied. Reduced graphene oxide-polydopamine complexes (RGO-PDA), gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) were prepared firstly and composited with AChE and chitosan (CS), then fixed on the glassy carbon electrode (GCE) surface to construct the biosensor GCE/RGO-PDA-AuNPs-AgNPs-AChE-CS by one-pot method. The results show that graphene oxide (GO) can be reduced by dopamine (DA) and dispersed well in RGO-PDA complexes. And the composites have a synergistic catalysis effect and can improve the surface resistance of GCE. The biosensor selectively can detect acetylcholine (ACh) and OPs pesticide with good linear range and high sensitivity. The performance of the biosensor is affected by the ratio and adding ways of AChE and the adding of AuNPs and AChE. And the biosensor can achieve a detection limit of 2.4 ng/L for methyl parathion and a wide linear detection range of 0.02 ng/L ~ 80 ng/L, and has excellent stability, good anti-interference ability, and excellent preservation performance, indicating that the sensor has practical value.

Keywords: acetylcholine esterase, electrochemical biosensor, nanoparticles, organophosphates, reduced graphene oxide

Procedia PDF Downloads 112

Authors: Mohd Sabri Minhat, Nurul Adilla Mohd Subha

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The 1MWth PUSPATI TRIGA Reactor (RTP) in Malaysia Nuclear Agency has been operating more than 35 years. The existing core power control is using conventional controller known as Feedback Control Algorithm (FCA). It is technically challenging to keep the core power output always stable and operating within acceptable error bands for the safety demand of the RTP. Currently, the system could be considered unsatisfactory with power tracking performance, yet there is still significant room for improvement. Hence, a new design core power control is very important to improve the current performance in tracking and regulating reactor power by controlling the movement of control rods that suit the demand of highly sensitive of nuclear reactor power control. In this paper, the proposed Model Predictive Control (MPC) law was applied to control the core power. The model for core power control was based on mathematical models of the reactor core, MPC, and control rods selection algorithm. The mathematical models of the reactor core were based on point kinetics model, thermal hydraulic models, and reactivity models. The proposed MPC was presented in a transfer function model of the reactor core according to perturbations theory. The transfer function model-based predictive control (TFMPC) was developed to design the core power control with predictions based on a T-filter towards the real-time implementation of MPC on hardware. This paper introduces the sensitivity functions for TFMPC feedback loop to reduce the impact on the input actuation signal and demonstrates the behaviour of TFMPC in term of disturbance and noise rejections. The comparisons of both tracking and regulating performance between the conventional controller and TFMPC were made using MATLAB and analysed. In conclusion, the proposed TFMPC has satisfactory performance in tracking and regulating core power for controlling nuclear reactor with high reliability and safety.

Keywords: core power control, model predictive control, PUSPATI TRIGA reactor, TFMPC

Procedia PDF Downloads 241

Authors: Pratthana Ammaraphitak, Piyachon Ketsuwan, Rattapoom Prommana

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Electricity production from vermicompost liquid was investigated in microbial fuel cells (MFCs). The aim of this study was to determine the performance of vermicompost liquid as a biocatalyst for electricity production by MFCs. Chemical and physical parameters of vermicompost liquid as total nitrogen, ammonia-nitrogen, nitrate, nitrite, total phosphorus, potassium, organic matter, C:N ratio, pH, and electrical conductivity in MFCs were studied. The performance of MFCs was operated in open circuit mode for 7 days. The maximum open circuit voltage (OCV) was 0.45 V. The maximum power density of 5.29 ± 0.75 W/m² corresponding to a current density of 0.024 2 ± 0.0017 A/m² was achieved by the 1000 Ω on day 2. Vermicompost liquid has efficiency to generate electricity from organic waste.

Keywords: vermicompost liquid, microbial fuel cell, nutrient, electricity production

Procedia PDF Downloads 178

Authors: Rihab Hamdi, Amel Hadri Hamida, Ouafae Bennis, Sakina Zerouali

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This paper features a performance analysis and robustness assessment of a digitally controlled DC-DC three-cell buck converter associated in parallel, operating in continuous conduction mode (CCM), facing feeding parameters variation and loads disturbance. The control strategy relies on the continuous-time with an averaged modeling technique for high-frequency switching converter. The methodology is to modulate the complete design procedure, in regard to the existence of an instantaneous current operating point for designing the digital closed-loop, to the same continuous-time domain. Moreover, the adopted approach is to include a digital voltage control (DVC) technique, taking an account for digital control delays and sampling effects, which aims at improving efficiency and dynamic response and preventing generally undesired phenomena. The results obtained under load change, input change, and reference change clearly demonstrates an excellent dynamic response of the proposed technique, also as provide stability in any operating conditions, the effectiveness is fast with a smooth tracking of the specified output voltage. Simulations studies in MATLAB/Simulink environment are performed to verify the concept.

Keywords: continuous conduction mode, digital control, parallel multi-cells converter, performance analysis, power electronics

Procedia PDF Downloads 151

Authors: Hamid Reza Tabatabaiefar, Bita Mansoury, Mohammad Javad Khadivi Zand

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The current energy and climate change impacts of the residential building sector in Australia are significant. Thus, the Australian Government has introduced more stringent regulations to improve building energy efficiency. In 2006, the Australian residential building sector consumed about 11% (around 440 Petajoule) of the total primary energy, resulting in total greenhouse gas emissions of 9.65 million tonnes CO2-eq. The gas and electricity consumption of residential dwellings contributed to 30% and 52% respectively, of the total primary energy utilised by this sector. Around 40 percent of total energy consumption of Australian buildings goes to heating and cooling due to the low thermal performance of the buildings. Thermal performance of buildings determines the amount of energy used for heating and cooling of the buildings which profoundly influences energy efficiency. Employing sustainable design principles and effective use of construction materials can play a crucial role in improving thermal performance of new and existing buildings. Even though awareness has been raised, the design phase of refurbishment projects is often problematic. One of the issues concerning the refurbishment of residential buildings is mostly the consumer market, where most work consists of moderate refurbishment jobs, often without assistance of an architect and partly without a building permit. There is an individual and often fragmental approach that results in lack of efficiency. Most importantly, the decisions taken in the early stages of the design determine the final result; however, the assessment of the environmental performance only happens at the end of the design process, as a reflection of the design outcome. Finally, studies have identified the lack of knowledge, experience and best-practice examples as barriers in refurbishment projects. In the context of sustainable development and the need to reduce energy demand, refurbishing the ageing residential building constitutes a necessary action. Not only it does provide huge potential for energy savings, but it is also economically and socially relevant. Although the advantages have been identified, the guidelines come in the form of general suggestions that fail to address the diversity of each project. As a result, it has been recognised that there is a strong need to develop guidelines for optimised retrofitting of existing residential buildings in order to improve their energy performance. The current study investigates the effectiveness of different energy retrofitting techniques and examines the impact of employing those methods on energy consumption of residential brick veneer buildings in Victoria (Australia). Proposing different remedial solutions for improving the energy performance of residential brick veneer buildings, in the simulation stage, annual energy usage analyses have been carried out to determine heating and cooling energy consumptions of the buildings for different proposed retrofitting techniques. Then, the results of employing different retrofitting methods have been examined and compared in order to identify the most efficient and cost-effective remedial solution for improving the energy performance of those buildings with respect to the climate condition in Victoria and construction materials of the studied benchmark building.

Keywords: brick veneer residential buildings, building energy efficiency, climate change impacts, cost effective remedial solution, energy performance, sustainable design principles

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Authors: Cheng Sim Quah, Sandra Phek Lin Sim

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This study examined how individuals in their respective teams contributed to innovation performance besides defining the term of innovation in their own respective views. This study also identified factors that motivated University staff to contribute to the innovation products. In addition, it examined whether there is a significant relationship between professional training level and the length of service among university staff towards innovation and to what extent do the two variables contributed towards innovative products. The significance of this study is that it revealed the strengths and weaknesses of the university staff when contributing to innovation performance. Stratified-random sampling was employed to determine the samples representing the population of lecturers in the study, involving 123 lecturers in one of the local universities in Malaysia. The method employed to analyze the data is through categorizing into themes for the open-ended questions besides using descriptive and inferential statistics for the quantitative data. This study revealed that two types of definition for the term “innovation” exist among the university staff, namely, creation of new product or new approach to do things as well as value-added creative way to upgrade or improve existing process and service to be more efficient. This study found that the most prominent factor that propel them towards innovation is to improve the product in order to benefit users, followed by self-satisfaction and recognition. This implies that the staff in the organization viewed the creation of innovative products as a process of growth to fulfill the needs of others and also to realize their personal potential. This study also found that there was only a significant relationship between the professional training level and the length of service of 4-6 years among the university staff. The rest of the groups based on the length of service showed that there was no significant relationship with the professional training level towards innovation. Moreover, results of the study on directional measures depicted that the relationship for the length of service of 4 - 6 years with professional training level among the university staff is quite weak. This implies that good organization management lies on the shoulders of the key leaders who enlighten the path to be followed by the staff.

Keywords: innovation, length of service, performance, professional training level, motivation

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Authors: Grigoria Athanasaki, Veerarajan Vimala, A. M. Kannan, Louis Cindrella

Abstract:

Energy usage has been increased throughout the years, leading to severe environmental impacts. Since the majority of the energy is currently produced from fossil fuels, there is a global need for clean energy solutions. Proton Exchange Membrane Fuel Cells (PEMFCs) offer a very promising solution for transportation applications because of their solid configuration and low temperature operations, which allows them to start quickly. One of the main components of PEMFCs is the Gas Diffusion Layer (GDL), which manages water and gas transport and shows direct influence on the fuel cell performance. In this work, a novel dual-layer GDL with gradient porosity was prepared, using polyethylene glycol (PEG) as pore former, to improve the gas diffusion and water management in the system. The microporous layer (MPL) of the fabricated GDL consists of carbon powder PUREBLACK, sodium dodecyl sulfate as a surfactant, 34% wt. PTFE and the gradient porosity was created by applying one layer using 30% wt. PEG on the carbon substrate, followed by a second layer without using any pore former. The total carbon loading of the microporous layer is ~ 3 mg.cm-2. For the assembly of the catalyst layer, Nafion membrane (Ion Power, Nafion Membrane NR211) and Pt/C electrocatalyst (46.1% wt.) were used. The catalyst ink was deposited on the membrane via microspraying technique. The Pt loading is ~ 0.4 mg.cm-2, and the active area is 5 cm2. The sample was ex-situ characterized via wetting angle measurement, Scanning Electron Microscopy (SEM), and Pore Size Distribution (PSD) to evaluate its characteristics. Furthermore, for the performance evaluation in-situ characterization via Fuel Cell Testing using H2/O2 and H2/air as reactants, under 50, 60, 80, and 100% relative humidity (RH), took place. The results were compared to a single layer GDL, fabricated with the same carbon powder and loading as the dual layer GDL, and a commercially available GDL with MPL (AvCarb2120). The findings reveal high hydrophobic properties of the microporous layer of the GDL for both PUREBLACK based samples, while the commercial GDL demonstrates hydrophilic behavior. The dual layer GDL shows high and stable fuel cell performance under all the RH conditions, whereas the single layer manifests a drop in performance at high RH in both oxygen and air, caused by catalyst flooding. The commercial GDL shows very low and unstable performance, possibly because of its hydrophilic character and thinner microporous layer. In conclusion, the dual layer GDL with PEG appears to have improved gas diffusion and water management in the fuel cell system. Due to its increasing porosity from the catalyst layer to the carbon substrate, it allows easier access of the reactant gases from the flow channels to the catalyst layer, and more efficient water removal from the catalyst layer, leading to higher performance and stability.

Keywords: gas diffusion layer, microporous layer, proton exchange membrane fuel cells, relative humidity

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Authors: Oğuzhan Urhan

Abstract:

In this paper, an improved motion estimation (ME) approach based on weighted constrained one-bit transform is proposed for block-based ME employed in video encoders. Binary ME approaches utilize low bit-depth representation of the original image frames with a Boolean exclusive-OR based hardware efficient matching criterion to decrease computational burden of the ME stage. Weighted constrained one-bit transform (WC‑1BT) based approach improves the performance of conventional C-1BT based ME employing 2-bit depth constraint mask instead of a 1-bit depth mask. In this work, the range of constraint mask is further extended to increase ME performance of WC-1BT approach. Experiments reveal that the proposed method provides better ME accuracy compared existing similar ME methods in the literature.

Keywords: fast motion estimation; low-complexity motion estimation, video coding

Procedia PDF Downloads 316

Authors: Bessaad Taieb, Benbouali Abderrahmen

Abstract:

Fuzzy controllers are a powerful tool for controlling complex processes. However, its robustness capacity remains moderately limited because it loses its property for large ranges of parametric variations. In this paper, the proposed control method is designed, based on a fuzzy adaptive controller used as a remedy for this problem. For increase the robustness of the vector control and to maintain the performance of the five-phase asynchronous machine despite the presence of disturbances (variation of rotor resistance, rotor inertia variations, sudden variations in the load etc.), by applying the method of behaviour model control (BMC). The results of simulation show that the fuzzy adaptive control provides best performance and has a more robustness as the fuzzy (FLC) and as a conventional (PI) controller.

Keywords: fuzzy adaptive control, behaviour model control, vector control, five-phase asynchronous machine

Procedia PDF Downloads 95

Authors: Kai-Chieh Lin, Chih-Fu Wu, Hsiang Ling Hsu, Yung-Hsiang Tu, Chia-Chen Wu

Abstract:

With the rapid development of computer technology, the design of computers and keyboards moves towards a trend of slimness. The change of mobile input devices directly influences users’ behavior. Although multi-touch applications allow entering texts through a virtual keyboard, the performance, feedback, and comfortableness of the technology is inferior to traditional keyboard, and while manufacturers launch mobile touch keyboards and projection keyboards, the performance has not been satisfying. Therefore, this study discussed the design factors of slim pressure-sensitive keyboards. The factors were evaluated with an objective (accuracy and speed) and a subjective evaluation (operability, recognition, feedback, and difficulty) depending on the shape (circle, rectangle, and L-shaped), thickness (flat, 3mm, and 6mm), and force (35±10g, 60±10g, and 85±10g) of the keyboard. Moreover, MANOVA and Taguchi methods (regarding signal-to-noise ratios) were conducted to find the optimal level of each design factor. The research participants, by their typing speed (30 words/ minute), were divided in two groups. Considering the multitude of variables and levels, the experiments were implemented using the fractional factorial design. A representative model of the research samples were established for input task testing. The findings of this study showed that participants with low typing speed primarily relied on vision to recognize the keys, and those with high typing speed relied on tactile feedback that was affected by the thickness and force of the keys. In the objective and subjective evaluation, a combination of keyboard design factors that might result in higher performance and satisfaction was identified (L-shaped, 3mm, and 60±10g) as the optimal combination. The learning curve was analyzed to make a comparison with a traditional standard keyboard to investigate the influence of user experience on keyboard operation. The research results indicated the optimal combination provided input performance to inferior to a standard keyboard. The results could serve as a reference for the development of related products in industry and for applying comprehensively to touch devices and input interfaces which are interacted with people.

Keywords: input performance, mobile device, slim keyboard, tactile feedback

Procedia PDF Downloads 299

Authors: Z. Jannoo, B. W. Yap, N. Auchoybur, M. A. Lazim

Abstract:

The two common approaches to Structural Equation Modeling (SEM) are the Covariance-Based SEM (CB-SEM) and Partial Least Squares SEM (PLS-SEM). There is much debate on the performance of CB-SEM and PLS-SEM for small sample size and when distributions are non-normal. This study evaluates the performance of CB-SEM and PLS-SEM under normality and non-normality conditions via a simulation. Monte Carlo Simulation in R programming language was employed to generate data based on the theoretical model with one endogenous and four exogenous variables. Each latent variable has three indicators. For normal distributions, CB-SEM estimates were found to be inaccurate for small sample size while PLS-SEM could produce the path estimates. Meanwhile, for a larger sample size, CB-SEM estimates have lower variability compared to PLS-SEM. Under non-normality, CB-SEM path estimates were inaccurate for small sample size. However, CB-SEM estimates are more accurate than those of PLS-SEM for sample size of 50 and above. The PLS-SEM estimates are not accurate unless sample size is very large.

Keywords: CB-SEM, Monte Carlo simulation, normality conditions, non-normality, PLS-SEM

Procedia PDF Downloads 410

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section. In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, CFD simulation

Procedia PDF Downloads 426

Authors: Swanand Patil, Pankaj Agarwal

Abstract:

In past few decades, seismic performance objectives have shifted from earthquake resistance to earthquake resilience of the structures, especially for the lifeline buildings. Features such as negligible post-earthquake damage and replaceable damaged components, makes energy dissipating systems a valid choice for a seismically resilient building. In this study, various energy dissipation devices are applied on an eight-storey moment resisting RC building model. The energy dissipating devices include both hysteresis-based and viscous type of devices. The seismic response of the building is obtained for different positioning and mechanical properties of the devices. The investigation is carried forward to the deficiently ductile RC frame also. The performance assessment is done on the basis of drift ratio, mode shapes and displacement response of the model structures. Nonlinear dynamic analysis shows largely improved displacement response. The damping devices improve displacement response more efficiently in the deficient ductile frames than that in the perfectly moment resisting frames. This finding is important considering the number of deficient buildings in India and the world. The placement and mechanical properties of the dampers prove to be a crucial part in modelling, analyzing and designing of the structures with supplemental energy dissipation.

Keywords: earthquake resilient structures, lifeline buildings, retrofitting of structures, supplemental energy dissipation

Procedia PDF Downloads 345

Authors: H. Shokouhmand, A. Ghanami

Abstract:

Heat pipe is simple heat transfer device which combines the conduction and phase change phenomena to control the heat transfer without any need for external power source. At hot surface of heat pipe, the liquid phase absorbs heat and changes to vapor phase. The vapor phase flows to condenser region and with the loss of heat changes to liquid phase. Due to gravitational force the liquid phase flows to evaporator section.In HVAC systems the working fluid is chosen based on the operating temperature. The heat pipe has significant capability to reduce the humidity in HVAC systems. Each HVAC system which uses heater, humidifier or dryer is a suitable nominate for the utilization of heat pipes. Generally heat pipes have three main sections: condenser, adiabatic region and evaporator.Performance investigation and optimization of heat pipes operation in order to increase their efficiency is crucial. In present article, a parametric study is performed to improve the heat pipe performance. Therefore, the heat capacity of heat pipe with respect to geometrical and confining parameters is investigated. For the better observation of heat pipe operation in HVAC systems, a CFD simulation in Eulerian- Eulerian multiphase approach is also performed. The results show that heat pipe heat transfer capacity is higher for water as working fluid with the operating temperature of 340 K. It is also showed that the vertical orientation of heat pipe enhances it’s heat transfer capacity used in the abstract.

Keywords: heat pipe, HVAC system, grooved heat pipe, heat pipe limits

Procedia PDF Downloads 364

Authors: Rajesh Kumar, Prabha Chand

Abstract:

The present paper deals with the analytical investigation on the thermal and thermo-hydraulic performance of the solar air collector fitted with fins and perforated twisted tapes (PTT) of twist ratio 2 with different axial pitch ratio. The mathematical models are presented, and the effect of mass flow rate and axial pitch ratios on the thermal and effective efficiency has been discussed. The results obtained are compared with the results of the solar air heater without fins and twisted tapes. Results conveyed that the collectors with fins and perforated twisted tape perform better but at the expense of increased pressure drop. Also, twisted tape with minimum axial pitch ratio is found to be more efficient than others.

Keywords: solar air heater, thermal efficiency, twisted tape, twist ratio

Procedia PDF Downloads 266

Authors: Khaing Yadana Swe, Lillie Dewan

Abstract:

At present, the cascade PID control is widely used to control the super-heating temperature (main steam temperature). As the main steam temperature has the characteristics of large inertia, large time-delay, and time varying, etc., conventional PID control strategy can not achieve good control performance. In order to overcome the bad performance and deficiencies of main steam temperature control system, Model Free Adaptive Control (MFAC) P cascade control system is proposed in this paper. By substituting MFAC in PID of the main control loop of the main steam temperature control, it can overcome time delays, non-linearity, disturbance and time variation.

Keywords: model-free adaptive control, cascade control, adaptive control, PID

Procedia PDF Downloads 603