Search results for: small power

Authors: Soma Chatterjee, I. Das

Abstract:

In the present study, we have investigated the structural, electrical and magneto-transport properties of polycrystalline and nanocrystalline Gd0.5Sr0.5MnO3 compounds. The variation of transport properties is modified by tuning the grain size of the material. In the high-temperature semiconducting region, temperature-dependent resistivity data can be well explained by the non-adiabatic small polaron hopping (SPH) mechanism. In addition, the resistivity data for all compounds in the low-temperature paramagnetic region can also be well explained by the variable range hopping (VRH) model. The parameters obtained from SPH and VRH mechanisms are found to be reasonable. In the case of nanocrystalline compounds, there is an overlapping temperature range where both SPH and VRH models are valid simultaneously, and a new conduction mechanism - variable range hopping of small polaron s(VR-SPH) is satisfactorily valid for the whole temperature range of these compounds. However, for the polycrystalline compound, the overlapping temperature region between VRH and SPH models does not exist and the VR-SPH mechanism is not valid here. Thus, polarons play a leading role in selecting different conduction mechanisms in different temperature ranges.

Keywords: electrical resistivity, manganite, small polaron hopping, variable range hopping, variable range of small polaron hopping

Procedia PDF Downloads 83

Authors: Zanjbeel Tabassum, Cahit Ali Bayraktar, Asfa Muhammad Din, Murat Durucu

Abstract:

Six Sigma is a widely adapted quality improvement methodology applied throughout the world. Through this paper, an attempt has been made to identify Critical Success Factors (CSF) for successful implementation of Six Sigma in Pakistani Small and Medium-sized Enterprises (SMEs). A survey methodology was used to collect the data from SMEs in Pakistan. The results of this exploratory empirical research reflect the importance of different CSFs of Six Sigma implementation in SMEs in Pakistan. On the basis of extracted factors, a framework has been proposed for successful Six Sigma implementation in Pakistani SMEs. This study will provide a base for Pakistani SMEs and future researchers working in Six Sigma implementation and help them to prepare a road map to eradicate the hurdles in Six Sigma implementation.

Keywords: critical success factors, small medium enterprises (SMEs), six sigma, Pakistan

Procedia PDF Downloads 352

Authors: Mohammad Arif Sobhan Bhuiyan, Zainal Abidin Nordin, Mamun Bin Ibne Reaz

Abstract:

A compact and power efficient high performance Voltage Controlled Oscillator (VCO) is a must in analog and digital circuits especially in the communication system, but the best trade-off among the performance parameters is a challenge for researchers. In this paper, a design of a compact 3-stage differential voltage controlled ring oscillator (VCRO) with low phase noise, low power and higher tuning bandwidth is proposed in 0.18 µm CMOS technology. The VCRO is designed with symmetric load and positive feedback techniques to achieve higher gain and minimum delay. The proposed VCRO can operate at tuning range of 3.9-5.0 GHz at 1.6 V supply voltage. The circuit consumes only 1.0757 mW of power and produces -129 dbc/Hz. The total active area of the proposed VCRO is only 11.74 x 37.73 µm2. Such a VCO can be the best choice for compact and low-power RF applications.

Keywords: CMOS, VCO, VCRO, oscillator

Procedia PDF Downloads 463

Authors: Juan Luis Leal, Rafael Maestre, Ovidio López

Abstract:

As innovation progresses, more possibilities are made available to increase the efficiency and reach of solutions for Smart Cities, most of which require the data provided by the Internet of Things (IoT) devices and may even have higher power requirements such as motors or actuators. A reliable power supply with the lowest maintenance is a requirement for the success of these solutions in the long term. Energy harvesting, mainly solar, becomes the solution of choice in most cases, but only if there is enough power to be harvested, which may depend on the device location (e.g., outdoors vs. indoor). This is the case of Smart Waste Containers with compaction systems, which have moderately high-power requirements, and may be installed in places with little sunlight for solar generation. It should be noted that waste is unloaded from the containers with cranes, so sudden and irregular movements may happen, making wired power unviable. In these cases, a wireless power supply may be a great alternative. This paper proposes a cost-effective two coil resonant wireless power transfer (WPT) system and describes its implementation, which has been carried out within an R&D project and validated in real settings with smart containers. Experimental results prove that the developed system achieves wireless power transmission up to 35W in the range of 5 cm to 1 m with a peak efficiency of 78%. The circuit is operated at relatively low resonant frequencies, which combined with enough wire-to-wire separation between the coil windings, reduce the losses caused by the proximity effect and, therefore, allow the use of common stranded wire instead of Litz wire, this without reducing the efficiency significantly. All these design considerations led to a final system that achieves a high efficiency for the desired charging range, simplifying the energy supply for Smart Containers as well as other devices that may benefit from a cost-effective wireless charging system.

Keywords: electromagnetic coupling, resonant wireless charging, smart recycling containers, wireless power transfer

Procedia PDF Downloads 85

Authors: Jae Kyung Lee, Joon Young Park

Abstract:

Maintenance on power transmission lines requires a lot of works. Sometimes they should be maintained on live-line environment with high altitude. Therefore, there always exist risks of falling from height and electric shock. To decline those risks, drones are recently applying on the electric power industry. This paper presents new operational technology while inspecting power transmission line. This paper also describes a technique for creating a flight path of a drone for transmission line inspection and a technique for controlling the drones of different types. Its technical and economical feasibilities have confirmed through experiments.

Keywords: drones, transmission line, inspection, control system

Procedia PDF Downloads 346

Authors: Denila Jinny Arulraj, Thillai Rajan Annamalai

Abstract:

This paper aims to study the relationship between funding sources and firm performance of Indian private limited SMEs using cross-sectional data obtained from a nation-wide census. A unique feature of the study is that it analyses firms that use only one form of external funding. Employing Propensity Score Matching, we find that obtaining any form of external finance has a negative influence on equivalents of profit margin and return on assets and a negative influence on asset turnover of small firms. But, the impact of institutional sources of funding on small enterprises is found to be lesser than that of non-institutional sources of funding. External/institutional sources of funding have a less negative impact on the profit margin for medium enterprises and have no significant influence on other measures of performance. The contribution of this research is the discovery of institutional sources wielding a lesser influence on performance measures considered. It is also found that institutional sources can benefit small enterprises more than medium enterprises.

Keywords: external finance, institutional finance, non-institutional finance, performance, India, SME

Procedia PDF Downloads 267

Authors: Abongile Zweni, Grate Moyo, Ricardo Peters, Bingwen Yan

Abstract:

Budgets are one of the most important tools that organisations, big or small, need to use as management tools. When organisations, particularly Small, Medium and Micro Enterprises (SMMEs), do not use budgets, they are bound to fail in their infancy stage. The aim of this study was to assess whether or not SMMEs in South Africa used budgets as an effective management tool during the COVID-19 pandemic. For the purposes of this study, data was collected using an online questionnaire (survey). This study used the quantitative research approach. The study used descriptive statistics to analyse the research question. The study found that most SMMEs did not use budgets during the COVID-19 pandemic; one of the reasons, amongst others, was that most of them had to close down during the lockdown, and some of them did not even qualify for government bailout or government grants.

Keywords: budget management, SMMEs, COVID-19, South Africa

Procedia PDF Downloads 186

Authors: Stamatis Zoras, Boris Ceranic, Ashley Redfern

Abstract:

Green House Gas emissions from domestic properties currently account for a substantial part of the total UK’s carbon emissions and is a priority area for UK to reach zero carbon emissions. However, GHG emissions of urban complexes depend on building, road, structural developments etc surfaces that form urban microclimate. This in turn may further influence renewable energy system power generation that depend on solar or wind potential. Moreover, urban climatic conditions are also influenced by the installation of those power generation systems that may impact their own power generation efficiency. Increased air temperature is attributed to densely installed roof based solar panels that consequently impact their own production efficiency. Installation of roof based solar panels requires adequate guidance to enable housing businesses, councils and organisations to implement sufficient measures for improved power generation in relation to local urban microclimate. How microclimate is affected and how, in return, it affects solar power productivity. Derby Council & Derby Homes have been collecting solar panel power generation data for a large number of properties. The different building areas and system operation performance will be studied against microclimate conditions through time. It is envisaged that the outcomes of the study will support a working up strategy for Derby city to ensure that owned homes would be able to access information and data of solar photo voltaic PV and solar thermal panels potential on social housing, helping residents on low incomes create their own green energy to power their homes and heat their homeshot water.

Keywords: microclimate, solar power, urban climatology, urban morphology

Procedia PDF Downloads 60

Authors: Sayyed Benyamin Alavi, Giovanni Cerri, Leila Chennaoui, Ambra Giovannelli, Stefano Mazzoni

Abstract:

Primary energy consumption and emissions of pollutants (including CO2) sustainability call to search methodologies to lower power absorption for unit of a given product. Cool production plants based on vapour compression are widely used for many applications: air conditioning, food conservation, domestic refrigerators and freezers, special industrial processes, etc. In the field of cool production, the amount of Yearly Consumed Primary Energy is enormous, thus, saving some percentage of it, leads to big worldwide impact in the energy consumption and related energy sustainability. Among various techniques to reduce power required by a Vapour Compression Cool Production Plant (VCCPP), the technique based on Power Regeneration by means of Internal Direct Cycle (IDC) will be considered in this paper. Power produced by IDC reduces power need for unit of produced Cool Power by the VCCPP. The paper contains basic concepts that lead to develop IDCs and the proposed options to use the IDC Power. Among various selections for using turbo machines, Best Economically Available Technologies (BEATs) have been explored. Based on vehicle engine turbochargers, they have been taken into consideration for this application. According to BEAT Database and similarity rules, the best turbo machine selection leads to the minimum nominal power required by VCCPP Main Compressor. Results obtained installing the prototype in “ad hoc” designed test bench will be discussed and compared with the expected performance. Forecasts for the upgrading VCCPP, various applications will be given and discussed. 4-6% saving is expected for air conditioning cooling plants and 15-22% is expected for cryogenic plants.

Keywords: Refrigeration Plant, Vapour Pressure Amplifier, Compressor, Expander, Turbine, Turbomachinery Selection, Power Saving

Procedia PDF Downloads 425

Authors: K. V. Venugopalan

Abstract:

Micro, Small and Medium Enterprises (MSMEs) have been accepted as the engine of economic growth and for promoting equitable development. The major advantage of the sector is its employment potential at low capital cost. The labour intensity of the MSME sector is much higher than that of the large enterprises. The MSMEs constitute over 90% of total enterprises in most of the economies and are credited with generating the highest rates of employment growth and account for a major share of industrial production and exports. Kerala is a small state in India with the limited land area with high potential in educated human resources need micro, small and medium enterprises for development. Kerala has the highest Physical Quality of Life Index (PQLI) in India and the highest Human Development Index (HDI) at par with the developed countries SME play an important role in alleviating poverty and contribute significantly towards the growth of developing economies. Financial institutions can play a vital role for the promotion of micro, small and medium enterprises in Kerala. The study entitled “Financial Institutions and its role in the promotion of Small and Medium Enterprises in Kerala “examine the progress of MSME in Kerala and India and also the role of financial institutions and the problems faced by entrepreneurs for getting advances with reference to ‘Kerala Financial Corporation’-an agency set up by the government for promoting small and medium enterprises in the state. This study is based on both secondary and primary data. Primary data for the study was collected from those entrepreneurs who availed advances from financial institutions. The secondary data include the investment made, goods and services provided, the employment generated and the number of units registered in MSME sector for the last 10 years in Kerala. The study concluded that financial institutions providing finance with simple procedures and charging smaller interest rates will increase the number of MSME's and also contribute gross state domestic product and reduce the unemployment problem and poverty in the economy.

Keywords: gross state domestic product, human development index, micro, small and medium enterprises

Procedia PDF Downloads 403

Authors: Mousa Meratizaman, Sina Monadizadeh, Majid Amidpour

Abstract:

One of the most favorable thermal desalination methods used widely today is Multi Effect Desalination. High energy consumption in this method causes coupling it with high temperature power cycle like gas turbine. This combination leads to higher energy efficiency. One of the high temperature power systems which have cogeneration opportunities is Solid Oxide Fuel Cell / Gas Turbine. Integration of Multi Effect Desalination with Solid Oxide Fuel Cell /Gas Turbine power cycle in a range of 300-1000 kW is considered in this article. The exhausted heat of Solid Oxide Fuel Cell /Gas Turbine power cycle is used in Heat Recovery Steam Generator to produce needed motive steam for Desalination unit. Thermodynamic simulation and parametric studies of proposed system are carried out to investigate the system performance.

Keywords: solid oxide fuel cell, thermodynamic simulation, multi effect desalination, gas turbine hybrid cycle

Procedia PDF Downloads 371

Authors: Cassandra Springate, Alexandra Furber, Jack E. Hines

Abstract:

Objectives: To create an evidence map of the cost-utility studies available with non-small cell lung cancer patients, and identify the geographical settings and interventions used. Methods: Using the Disease, Study Type, and Model Type filters in heoro.com we identified all cost-utility studies published between 1960 and 2017 with patients with non-small cell lung cancer. These papers were then indexed according to pre-specified categories. Results: Heoro.com identified 89 independent publications, published between 1995 and 2017. Of the 89 papers, 74 were published since 2010, 28 were from the USA, and 35 were from Europe, 16 of which were from the UK. Other publications were from China and Japan (13), Canada (9), Australia and New Zealand (4), and other countries (8). Fifty-nine studies included a chemotherapy intervention, of which 23 included erlotinib or gefitinib, 21 included pemetrexed or docetaxel, others included nivolumab (3), pembrolizumab (2), crizotinib (2), denosumab (2), necitumumab (1), and bevacizumab (1). Also, 19 studies modeled screening, staging, or surveillance strategies. Conclusions: The cost-utility studies found for NSCLC most commonly looked at the effectiveness of different chemotherapy treatments, with some also evaluating the addition of screening strategies. Most were also conducted with patient data from the USA and Europe.

Keywords: cancer, cost-utility, economic model, non-small cell lung cancer

Procedia PDF Downloads 147

Authors: Shabnam Dadparvar, Laijin Shen

Abstract:

After a period of conflict between Russia and the West, new signs of confrontation between the United States and China are observed. China, as the most populous country in the world with a high rate of economic growth, neither stands the hegemonic power of the United States nor has the intention of direct confrontation with it. By raising the costs of the United States’ leadership at the international level, China seeks to find a better status without direct confrontation with the US. Meanwhile, the Shanghai Cooperation Organization (SCO), as a soft balancing strategy against the hegemony of the United States is used as a tool to reach this goal. The authors by using a descriptive-analytical method try to explain the policies of China and the United States on Shanghai Cooperation Organization as well as confrontation between these two countries within the framework of 'balance of soft power theory'.

Keywords: balance of soft power, Central Asia, Shanghai cooperation organization, terrorism

Procedia PDF Downloads 366

Authors: David Calderon Villegas, Thomas Kaltizky

Abstract:

Run-of-river (RoR) hydropower projects represent a viable, clean, and cost-effective alternative to dam-based plants and provide decentralized power production. However, RoR schemes cost-effectiveness depends on the proper selection of site and design flow, which is a challenging task because it requires multivariate analysis. In this respect, this study presents the development of an investment decision support tool for assessing the optimal size of an RoR scheme considering the technical, environmental, and cost constraints. The net present value (NPV) from a project perspective is used as an objective function for supporting the investment decision. The tool has been tested by applying it to an actual RoR project recently proposed in Colombia. The obtained results show that the optimum point in financial terms does not match the flow that maximizes energy generation from exploiting the river's available flow. For the case study, the flow that maximizes energy corresponds to a value of 5.1 m3/s. In comparison, an amount of 2.1 m3/s maximizes the investors NPV. Finally, a sensitivity analysis is performed to determine the NPV as a function of the debt rate changes and the electricity prices and the CapEx. Even for the worst-case scenario, the optimal size represents a positive business case with an NPV of 2.2 USD million and an IRR 1.5 times higher than the discount rate.

Keywords: small hydropower, renewable energy, RoR schemes, optimal sizing, objective function

Procedia PDF Downloads 126

Authors: B. G. Sheeparamatti, Prashant Hanasi, Vanita Abbigeri

Abstract:

The objective of this work is to carry out a critical comparison of different actuation mechanisms like electrostatic, thermal, piezoelectric, and magnetic with reference to a microcantilever. The relevant parameters like force generated, displacement are compared in actuation methods. With these results, they help in choosing the best actuation method for a particular application. In this study, Comsol/Multiphysics software is used. Modeling and simulation are done by considering the microcantilever of same dimensions as an actuator using all the above-mentioned actuation techniques. In addition to their small size, micro actuators consume very little power and are capable of accurate results. In this work, a comparison of actuation mechanisms is done to decide the efficient system in the micro domain.

Keywords: actuation techniques, microswitch, micro actuator, microsystems

Procedia PDF Downloads 397

Authors: Abdellah Boualouch, Ahmed Essadki, Tamou Nasser, Ali Boukhriss, Abdellatif Frigui

Abstract:

This paper presents a power control for a Doubly Fed Induction Generator (DFIG) using in Wind Energy Conversion System (WECS) connected to the grid. The proposed control strategy employs two nonlinear controllers, Backstipping (BSC) and sliding-mode controller (SMC) scheme to directly calculate the required rotor control voltage so as to eliminate the instantaneous errors of active and reactive powers. In this paper the advantages of BSC and SMC are presented, the performance and robustness of this two controller’s strategy are compared between them. First, we present a model of wind turbine and DFIG machine, then a synthesis of the controllers and their application in the DFIG power control. Simulation results on a 1.5MW grid-connected DFIG system are provided by MATLAB/Simulink.

Keywords: backstipping, DFIG, power control, sliding-mode, WESC

Procedia PDF Downloads 589

Authors: Mohab Magdy Mostafa Mohamed

Abstract:

The objective of this paper is to introduce a vertical handover (VHO) algorithm between wireless LANs (WLANs) and LTE mobile networks. The proposed algorithm is based on the fuzzy control theory and takes into consideration power level, subscriber velocity, and target cell load instead of only power level in traditional algorithms. Simulation results show that network performance in terms of number of handovers and handover occurrence distance is improved.

Keywords: vertical handover, fuzzy control theory, power level, speed, target cell load

Procedia PDF Downloads 342

Authors: Mehdi Ameur, Ahmed Essakdi, Tamou Nasser

Abstract:

The purpose of this paper is the analysis and modeling of the photovoltaic system with MPPT techniques. This system is developed by combining the models of established solar module and DC-DC converter with the algorithms of perturb and observe (P&O), incremental conductance (INC) and fuzzy logic controller(FLC). The system is simulated under different climate conditions and MPPT algorithms to determine the influence of these conditions on characteristic power-voltage of PV system. According to the comparisons of the simulation results, the photovoltaic system can extract the maximum power with precision and rapidity using the MPPT algorithms discussed in this paper.

Keywords: photovoltaic array, maximum power point tracking, MPPT, perturb and observe, P&O, incremental conductance, INC, hill climbing, HC, fuzzy logic controller, FLC

Procedia PDF Downloads 424

Authors: Todor Nickolov Stoyanov

Abstract:

These factors appear as a reason for difficulties in financing from programs for rural development of the European Union. Credit conditions for commercial banks are difficult to implement, and its interest rate is too high. One of the possibilities for short-term loans at preferential conditions for the small and medium-sized agricultural and forest owners is credit cooperative. After the changes, occurred in the country after 1990, the need to restore credit cooperatives raised. The purpose for the creation of credit cooperatives is to assist private agricultural and forest owners to take care for them, to assist in the expansion and strengthening of their farms, to increase the quality of life and to improve the local economy. It was found that: in Bulgaria there is a legal obstacle for credit cooperatives to expand their business in the deposit and lending sphere; private forest and agricultural owners need small loans to solve a small problem for a certain season; providing such loans is not attractive for banks, but it is extremely necessary for owners of small forests and lands; if a special law on credit cooperatives is adopted, as required by the Cooperatives Act, it will allow more local people to be members of such credit structures and receive the necessary loans. In conclusion, proposals to create conditions for the development of credit cooperatives in the country are made and positive results expected from the creation of credit cooperatives, are summarized.

Keywords: cooperatives, credit cooperatives, forestry, forest owners

Procedia PDF Downloads 217

Authors: Mark A. Spooner

Abstract:

The growth of technological advances in the digital communications industry has dictated the way forensic examination laboratories receive, analyze, and report on digital evidence. This study looks at the trends in a medium sized digital forensics lab that examines small communications devices (i.e., cellular telephones, tablets, thumb drives, etc.) over the past five years. As law enforcement and homeland security organizations budgets shrink, many agencies are being asked to perform more examinations with less resources available. Using multi-level statistical analysis using five years of examination data, this research shows the increasing technological demand trend. The research then extrapolates the current data into the model created and finds a continued exponential growth curve of said demands is well within the parameters defined earlier on in the research.

Keywords: digital forensics, forensic examination, small device, trends

Procedia PDF Downloads 193

Authors: Jiawen Wang, Qijun Chen

Abstract:

The performance of most machine-learning methods for image inpainting depends on the quantity and quality of the training samples. However, it is very expensive or even impossible to obtain a great number of training samples in many scenarios. In this paper, an image inpainting model based on a generative adversary network (GAN) is constructed for the cases when the number of training samples is small. Firstly, a feature extraction network (F-net) is incorporated into the GAN network to utilize the available information of the inpainting image. The weighted sum of the extracted feature and the random noise acts as the input to the generative network (G-net). The proposed network can be trained well even when the sample size is very small. Secondly, in the phase of the completion for each damaged image, a genetic algorithm is designed to search an optimized noise input for G-net; based on this optimized input, the parameters of the G-net and F-net are further learned (Once the completion for a certain damaged image ends, the parameters restore to its original values obtained in the training phase) to generate an image patch that not only can fill the missing part of the damaged image smoothly but also has visual semantics.

Keywords: image inpainting, generative adversary nets, genetic algorithm, small-sample size

Procedia PDF Downloads 125

Authors: Hussaini Tunde Subairu

Abstract:

Small and Medium Enterprises (SMEs) sectors serve as catalyst for employment generation, national growth, poverty reduction and economic development in developing and developed countries. However, in Nigeria despite copious and plethora of government policies and stimulus schemes directed at SMEs, the sector is still characterized by high rate of failure and discontinuities. This study therefore investigated owners/managers profile, firms characteristics and external factors as possible determinants of SMEs growth from selected SMEs in Kwara State. Primary data were sourced from 200 SMEs respondents registered with the National Association of Small and Medium Enterprises (NASMES) in Kwara State Central Senatorial District. Multiple Regressions Analysis (MRA) was used to analyze the relationship between dependent and independent variables, and pair wise correlation was employed to examine the relationship among independent variables. The Analysis of Variable (ANOVA) was employed to indicate the overall significant of the model The findings revealed that Analysis of variance (ANOVA) put the value of F-statistics at 420.45 and p-value at 0.000 was significant. The values of R2 and Adjusted R2 of 0.9643 and 0.9620 respectively suggested that 96 percent of variations in employment growth were explained by the explanatory variables. The level of technical and managerial education has t- value of 24.14 and p-value of 0.001, length of managers/owners experience in similar trade with t- value of 21.37 and p-value of 0.001, age of managers/owners with t- value of 42.98 and p-value of 0.001, firm age with t- value of 25.91 and p-value of 0.001, numbers of firms in a cluster with t- value of 7.20 and p-value of 0.001, access to formal finance with t-value of 5.56 and p-value of 0.001, firm technology innovation with t- value of 25.32 and p-value of 0.01, institutional support with t- value of 18.89 and p-value of 0.01, globalization with t- value of 9.78 and p-value of 0.01, and infrastructure with t-value of 10.75 and p-value of 0.01. The result also indicated that initial size has t-value of -1.71 and p-value of 0.090 which is consistent with Gibrat’s Law. The study concluded that owners/managers profile, firm specific characteristics and external factors substantially influenced employment growths of SMEs in the study area. Therefore, policy implication should enhance human capital development of SMEs owners/managers, and strengthen fiscal policy thrust through imposition on tariff regime to minimize effect of globalization. Governments at all level must support SMEs growth radically and enhance institutional support for SMEs growth and radically and significantly upgrading key infrastructure as rail/roads, rail, telecommunications, water and power.

Keywords: external factors, firm specific characteristics, owners / manager profile, small and medium enterprises

Procedia PDF Downloads 237

Authors: Fayssal Amrane, Azeddine Chaiba

Abstract:

In this paper, type-2 fuzzy logic control (T2FLC) and neuro-fuzzy control (NFC) for a doubly fed induction generator (DFIG) based on direct power control (DPC) with a fixed switching frequency is proposed for wind generation application. First, a mathematical model of the doubly-fed induction generator implemented in d-q reference frame is achieved. Then, a DPC algorithm approach for controlling active and reactive power of DFIG via fixed switching frequency is incorporated using PID. The performance of T2FLC and NFC, which is based on the DPC algorithm, are investigated and compared to those obtained from the PID controller. Finally, simulation results demonstrate that the NFC is more robust, superior dynamic performance for wind power generation system applications.

Keywords: doubly fed induction generator (DFIG), direct power control (DPC), neuro-fuzzy control (NFC), maximum power point tracking (MPPT), space vector modulation (SVM), type 2 fuzzy logic control (T2FLC)

Procedia PDF Downloads 410

Authors: Munnujahan Ara

Abstract:

In this paper, we investigate the effect of friendly jamming power allocation strategies on the achievable average secrecy rate over a bank of parallel fading wiretap channels. We investigate the achievable average secrecy rate in parallel fading wiretap channels subject to Rayleigh and Rician fading. The achievable average secrecy rate, due to the presence of a line-of-sight component in the jammer channel is also evaluated. Moreover, we study the detrimental effect of correlation across the parallel sub-channels, and evaluate the corresponding decrease in the achievable average secrecy rate for the various fading configurations. We also investigate the tradeoff between the transmission power and the jamming power for a fixed total power budget. Our results, which are applicable to current orthogonal frequency division multiplexing (OFDM) communications systems, shed further light on the achievable average secrecy rates over a bank of parallel fading channels in the presence of friendly jammers.

Keywords: fading parallel channels, wire-tap channel, OFDM, secrecy capacity, power allocation

Procedia PDF Downloads 502

Authors: Pedro Esteban

Abstract:

Most installations nowadays are exposed to many power quality problems, and they also face numerous challenges to comply with grid code and energy efficiency requirements. The reason behind this is that they are not designed to support nonlinear, non-balanced, and variable loads and generators that make up a large percentage of modern electric power systems. These problems and challenges become especially critical when designing green buildings and smart cities. These problems and challenges are caused by equipment that can be typically found in these installations like variable speed drives (VSD), transformers, lighting, battery chargers, double-conversion UPS (uninterruptible power supply) systems, highly dynamic loads, single-phase loads, fossil fuel generators and renewable generation sources, to name a few. Moreover, events like capacitor switching (from existing capacitor banks or passive harmonic filters), auto-reclose operations of transmission and distribution lines, or the starting of large motors also contribute to these problems and challenges. Active power filters (APF) are one of the fastest-growing power electronics technologies for solving power quality problems and meeting grid code and energy efficiency requirements for a wide range of segments and applications. They are a high performance, flexible, compact, modular, and cost-effective type of power electronics solutions that provide an instantaneous and effective response in low or high voltage electric power systems. They enable longer equipment lifetime, higher process reliability, improved power system capacity and stability, and reduced energy losses, complying with most demanding power quality and energy efficiency standards and grid codes. There can be found several types of active power filters, including active harmonic filters (AHF), static var generators (SVG), active load balancers (ALB), hybrid var compensators (HVC), and low harmonic drives (LHD) nowadays. All these devices can be used in applications in Smart Cities bringing several technical and economic benefits.

Keywords: power quality improvement, energy efficiency, grid code compliance, green buildings, smart cities

Procedia PDF Downloads 108

Authors: Gulnaz Erkomaishvili

Abstract:

Introduction: The paper assesses the impact of the COVID-19 pandemic on the activities of small and medium-sized enterprises in Georgia, identifies their problems, and analyzes the state economic policy measures. During the pandemic, entrepreneurs named the imposition of restrictions, access to financial resources, shortage of qualified personnel, high tax rates, unhealthy competition in the market, etc. as the main challenges. The Georgian government has had to take special measures to mitigate the crisis impact caused by the pandemic. For example - in 2020, they mobilized more than 1,6 billion Gel for various eventsto support entrepreneurs. Small and medium-sized entrepreneurship development strategy is presented based on the research; Corresponding conclusions are made, and recommendations are developed. Objectives: The object of research is small and medium-sized enterprises and economic-political decisions aimed at their promotion.Methodology: This paper uses general and specific methods, in particular, analysis, synthesis, induction, deduction, scientific abstraction, comparative and statistical methods, as well as experts’ evaluation. In-depth interviews with experts were conducted to determine quantitative and qualitative indicators; Publications of the National Statistics Office of Georgia are used to determine the regularity between analytical and statistical estimations. Also, theoretical and applied research of international organizations and scientist-economists are used. Contributions: The COVID-19pandemic has had a significant impact on small and medium-sized enterprises. For them, Lockdown is a major challenge. Total sales volume decreased. At the same time, the innovative capabilities of enterprises and the volume of sales in remote channels have increased. As for the assessment of state support measures by small and medium-sizedentrepreneurs, despite the existence of support programs, a large number of entrepreneurs still do not evaluate the measures taken by the state positively. Among the desirable measures to be taken by the state, which would improve the activities of small and medium-sized entrepreneurs, who negatively or largely negatively assessed the activity of the state, named: tax incentives/exemption from certain taxes at the initial stage; Need for periodic trainings/organization of digital technologies, marketing training courses to improve the qualification of employees; Logic and adequacy of criteria when awarding grants and funding; Facilitating the finding of investors; Less bureaucracy, etc.

Keywords: small and medium enterprises, small and medium entrepreneurship, economic policy for small and medium entrepreneurship development, government regulations in Georgia, COVID-19 pandemic

Procedia PDF Downloads 148

Authors: M. Doumi, K. Tahir, A. Miloudi, A. G. Aissaoui, C. Belfedal, S. Tahir

Abstract:

This paper presents a three-phase grid-connected photovoltaic generation system with unity power factor for any situation of solar radiation based on voltage-oriented control (VOC). An input voltage clamping technique is proposed to control the power between the grid and photovoltaic system, where it is intended to achieve the maximum power point operation. This method uses a Perturb and Observe (P&O) controller. The main objective of this work is to compare the energy production unit performances by the use of two types of controllers (namely, classical PI and Sliding Mode (SM) Controllers) for the grid inverter control. The proposed control has a hierarchical structure with a grid side control level to regulate the power (PQ) and the current injected to the grid and to obtain a common DC voltage constant. To show the effectiveness of both control methods performances analysis of the system are analyzed and compared by simulation and results included in this paper.

Keywords: grid connected photovoltaic, MPPT, inverter control, classical PI, sliding mode, DC voltage constant, voltage-oriented control, VOC

Procedia PDF Downloads 605

Authors: Kelaiaia Mounia Samira, Labar Hocine, Mesbah Tarek, Kelaiaia samia

Abstract:

The photovoltaic panel produces green power, and because of its availability across the globe, it can supply isolated loads (site away of the electrical network or difficult of access). Unfortunately this energy remains very expensive. The most application of these types of power needs storage devices, the Lithium batteries are commonly used because of its powerful storage capability. Using a solar panel or an array of panels without a controller that can perform MPPT will often result in wasted power, which results in the need to install more panels for the same power requirement. For devices that have the battery connected directly to the panel, this will also result in premature battery failure or capacity loss. In this paper it is proposed a modified P&O algorithm for the MPPT which takes in account the battery’s internal resistance vs temperature and stage of charging. Of course the temperature variation and irradiation of the PV panel are also introduced.

Keywords: modeling, battery, MPPT, charging, PV Panel

Procedia PDF Downloads 519

Authors: Norazuwin Najihah Mat Tahir, Fuziyah Ishak, Seripah Awang Kechil

Abstract:

The onset of the convective instability in the horizontal through flow of a power-law nanofluid saturated by porous layer heated from below under the influences of magnetic field are investigated in this study. The linear stability theory is used for the transformation of the partial differential equations to system of ordinary differential equations through infinitesimal perturbations, scaling, linearization and method of normal modes with two-dimensional periodic waves. The system is solved analytically for the closed form solution of the Rayleigh number by using the Galerkin-type weighted residuals method to investigate the onset of both traveling wave and oscillatory convection. The effects of the power-law index, Lewis number and Peclet number on the stability of the system were investigated. The Lewis number stabilizes while the power-law index and Peclet number destabilize the nanofluid system. The system in the presence of magnetic field is more stable than the system in the absence of magnetic field.

Keywords: convection, instability, magnetic field, nanofluid, power-law

Procedia PDF Downloads 263

Authors: El Hadji Mamadou Sonko, Ndiogou Sankhare, Maïmouna Lo, Jean Birane Gning, Cheikh Diop

Abstract:

In Senegal, access to water, hygiene, and sanitation in small island towns is a particular problem, which is still poorly understood by the public authorities and development aid actors. The main objective of this study carried out in the Municipality of Foundiougne is to contribute to the knowledge of the problems related to the supply of drinking water, access to sanitation, and hygiene in small island towns in Senegal. The methodology adopted consisted of a literature review and quantitative surveys of a sample of 100 households in the Municipality. Semi-structured interviews using interview guides and informal interviews were also conducted with mechanical and manual emptiers, municipal authorities, public toilet managers, and neighbourhood leaders. Direct observation with photography was also used. The results show that, with regard to access to drinking water, 35% of households have unimproved water services, 46% have a limited level of service, and 19% have a basic level of service. Regarding sanitation, 77% of households are considered to have access to basic sanitation services, compared to 23% with limited sanitation services. However, these figures hide the dysfunctions of the sanitation system. Indeed, manual emptying is practiced exclusively by 4% of households, while 17% of households combine it with mechanical emptying. In addition, domestic wastewater is mainly evacuated outside the sanitation facilities, and all the sludge extracted from the pits is discharged directly into the environment without treatment. As a matter of fact, the surveys showed that 52% of households do not have access to a basic level of hygiene-related to handwashing when leaving the toilet. These results show that there is real work to be done at the level of small urban centres if we want to achieve MDG 6.

Keywords: Foundiougne, Senegal, small island, small town, water-sanitation, hygiene

Procedia PDF Downloads 86