1,138 research outputs found
Modeling of a smart grid system using real time data on NEPLAN
No full textThe simulation model of the Smart Grids Laboratory of the Institute of Energy and Transport is presented in this paper and a day of its operation is analyzed. The developed model simulates six different modules (a photovoltaic array, a Li-ion battery storage system, a small wind turbine, a diesel generator, a laboratory load and the connection point with the grid). The modules are connected radially at a common bus
Comparative analysis of on-load tap changing (OLTC) transformer topologies
No full textOld - EWI-ESE-DC&S DC systems & StorageElectrical Power Processin
Smart grid opportunities and applications in Turkey
No full textA smart grid is a system that uses information and communication technologies to integrate, in an intelligent way, all users connected to the electrical power system considering their behaviour and actions. For this purpose, information about the electrical network, such as the current, the voltage or the power, is gathered together over time so that the behaviour of suppliers and consumers can be observed and automatically coordinated. Smart grids are becoming a significant part in the configuration of future electrical power systems. A lot of research has been done on using smart grids to achieve highly efficient and user-friendly electrical power systems. Many new methods have been introduced to solve the difficulties energy providers face when transforming conventional electrical networks into smart grids. These difficulties include the integration of renewable energy and different grid systems at national and international levels due to changes in frequency, voltage and in the synchronisation mechanism
Photovoltaic System Efficiency Enhancement With Thermal Management: Phase Changing Materials (pcm) With High Conductivity Inserts
No full textThe electrical conversion efficiency of photovoltaic cells from solar radiation heavily depends on the cell temperature. Here we propose a novel thermal management strategy to keep the cell temperature in the same order to attain maximum efficiency. The comparative study presented is based on four solar module configurations: a conventional photovoltaic module (PVT module), a conventional module with PCM layer underneath (PVT/PCM-I), a configuration where fins embedded into PCM (PVT/PCM-II), and configuration where the bottom of the PCM layer in PVT/PCM-II was cooled via convection (PVT/PCM-III). The developed 3D numerical model is solved via ANSYS software involving the solar ray tracing radiation model for incident solar radiations and a transient melting-solidification thermo-fluid model to cater for PCM phase transition. Results from the numerical model were validated via a comparison of experimentally studied results presented in the literature. After 120 minutes, results show that the conversion efficiency of PV cells becomes 16.84%, 18.65%, 18.83%, and 18.98% after 120 minutes for PVT module, PVT/PCM-I, PVT/PCM-II, and PVT/PCM-III with an inlet velocity of 3m/s, respectively. For the respective configurations, the specific electrical power per unit area produced reaches 75.30W/m2, 83.39W/m2, 84.19W/m2, and 89.42W/m2 for solar radiation of 540W/m2 and 26°C ambient temperature. Results reveal that a 5 mm increase in the fin height for PVT/PCM-II results in a 0.22% increase in efficiency while a 0.5m/s increase in the inlet velocity of the cooling air for PVT/PCM-III results in about 0.06% increase in efficiency. © 2021, ilhami Colak. All rights reserved
Första linjens chef - Att stå ensam i stormen? : En kvalitativ studie om hur första linjens chefer inom vård och omsorg balanserar organisationens mål och medarbetarnas behov
No full textSyftet med denna studie är att undersöka hur första linjens chefer inom vård och omsorg hanterar de utmaningar som uppstår i deras ledarskap. Fokus ligger på hur dessa chefer navigerar mellan organisationens mål och medarbetarnas behov, samt vilka strategier de använder för att skapa balans i det dagliga arbetet. För att besvara studiens frågeställningar har en kvalitativ metod använts, där semistrukturerade intervjuer genomförts med sju första linjens chefer inom en kommunal förvaltning i nordvästra Skåne. Den kvalitativa ansatsen möjliggjorde en fördjupad förståelse av respondenternas personliga erfarenheter och perspektiv, då den gav utrymme för att fånga nyanser i hur cheferna själva upplever och tolkar sin roll, sina utmaningar och de strategier de använder för att hantera dessa i praktiken. Tidigare forskning visar att chefsrollen inom vård och omsorg har förändrats avsevärt under de senaste decennierna, till följd av omfattande organisationsförändringar inom den offentliga sektorn. Yrkesrollen har blivit alltmer komplex och präglas idag av ett ökat ansvar kring exempelvis effektivitet, resultatstyrning och administration. Första linjens chefer förväntas därmed hantera en bred uppsättning uppgifter och samtidigt balansera krav från såväl högreledning som medarbetare och externa aktörer. Resultatet har indikerat att cheferna ofta upplever att de står i en pressad “mellanställning”, där de påverkas av både toppstyrda beslut från högsta ledningen och förväntningar från medarbetarna. Trots detta uttrycker respondenterna en förmåga att hitta balans i sin roll som första linjens chef, något som möjliggörs genom exempelvis stödstrukturer, goda organisatoriska förutsättningar samt egna individuella strategier. Studiens resultat pekar på vikten av fungerande stödfunktioner och ett hållbart ledarskap, där chefens inre motivation och engagemang spelar en central roll för attskapa en god arbetsmiljö och en välfungerande verksamhet. Balansen mellan organisatoriska krav och tillgängliga resurser framstår som avgörande, och upprätthålls i hög grad genomtydlig, öppen och lyhörd kommunikation. När medarbetares behov och perspektiv får utrymme samtidigt som ledningens förväntningar hanteras på ett strukturerat sätt, stärks chefens möjlighet att agera i en mellanposition utan att tappa riktning eller förankring. En sådan kommunikativ tydlighet bidrar inte bara till ökad förståelse och tillit i organisationen, utan också till en mer hållbar chefsroll över tid.The purpose of this study is to investigate how first-line managers in health and social care handle the challenges they face in their leadership roles. The focus is on how these managers navigate between the goals of the organization and the needs of their employees, as well as which strategies they use to create balance in their daily work. In order to answer the study’s research questions a qualitative method was used. Semi-structured interviews were conducted with seven first-line managers working in a public sector organization in northwestern Skåne, Sweden. This qualitative approach allowed for a deeper understanding of the participants’ personal experiences and perspectives, capturing how they perceive and manage their roles, challenges, and strategies in practice. Previous research shows that the role of managers in health and social care has changed significantly in recent decades, due to major organizational reforms in the public sector. The role has become more complex, with increased responsibilities related to efficiency, performance management, and administration. First-line managers are now expected to handle a wide range of assessments while balancing demands from senior management, employees, and external stakeholders. The results show that these managers often feel caught in the middle, pressured by decisions from higher levels of leadership while also trying to meet the expectations of their employers. Still, they demonstrate an ability to find balance in their roles. This is made possible through support structures, good working conditions, and their own personal strategies. The study highlights the importance of well-functioning support systems and sustainable leadership. The internal motivation and personal engagement of the manager are key factors in creating a healthy work environment and a well-functioning organization. Balancing organizational demands with available resources is crucial and is often supported by clear, open, and responsive communication. When employees’ needs and voices are acknowledged, and leadership expectations are managed in a structured way, the manager is better able to navigate their position without losing direction or focus. Such communication builds trust and clarity, contributing to a more sustainable leadership role over time.
A PROMOTER POLYMORPHISM IN THE PON1 GENE IS ASSOCIATED WITH ESSENTIAL HYPERTENSION
No full textColak, Ertugrul/0000-0003-3251-1043; Colak, Emine/0000-0002-6293-2909; Cosan, Didem Turgut/0000-0002-8488-6405Objective:
Increased vascular oxidative stress, the main risk factor of cardiovascular diseases, is seen as a role in the pathophysiology of essential hypertension. Genetic factors also play an important role in the formation of hypertension
Organisering av ekonomiskt bistånd – Perspektiv på en integrerad och en specialiserad kommun
No full textAuthor: Merima Colak Title: Organization of financial assistance - Perspective on an integrated and a specialized municipality [translated title] Supervisor: Håkan Johansson Assessor: Staffan Blomberg The purpose of this study was to examine how specialized and integrated social services manage their social assistance. In addition to this the aim was to examine how social workers and officials working within these two forms of organizations experience discretion. Furthermore, a goal of this paper was also to examine if the social workers felt that any of these two organizational forms had any impact on the workload and how that in such case manifested. The study was conducted through a qualitative research method. Six social workers and officials were interviewed for the study. The results from the study demonstrated that the employees in the integrated organization had more general work tasks and that those in the specialized organization had their tasks divided on different units that were more specialized. Findings also showed that employees in each municipality interpret discretion differently. The social workers from the integrated organization interpreted discretion in terms of being able to affect their client’s case. The social workers from the specialized organization, on the other hand, defined discretion as being able to influence their own daily work tasks. Conclusively, the study showed that workload exists in both municipalities and that it was manageable in each of the municipalities, the workload was however higher in the specialized one but it was no burden on the employees in neither the specialized nor the integrated. Key words: Discretion, organizational structure, integrated and specialized organizations, social assistance, workload. Key words: handlingsutrymme, organisationsstruktur, integrerade och specialiserade organisationer, ekonomiskt bistånd, arbetsbelastning
Hybrid Solar-RF Energy Harvesting Mechanisms for Remote Sensing Devices
No full textRecently, sensor networks effectively provide many applications in different fields. The deployment of mobile sensors, unmanned aerial vehicles is to reduce the burden of energy consumption for sensor nodes. However, saving energy in such networks is still a critical issue. This paper investigates the performance of a hybrid RF-Solar harvesting circuit for remote sensing devices. The harvesting circuit can simultaneously harvest power from solar and radio frequency (RF) sources readily available in the surrounding environment. The proposed work builds RF and solar harvester circuits to create hybrid harvesting circuits for all elements in the combined sensing networks. The stand-alone RF harvester circuit is a dual-band multi-stage harvester that is designed to work at 2.4GHz, Wi-Fi/WLAN bands. The standalone solar harvester circuit comprises a solar panel with a maximum power point tracking (MPPT) algorithm. The whole hybrid system can produce a maximum power of up to 133.25W with a boost current element in the charging system. Since each node is equipped with a rechargeable battery, all the batteries are charged by the harvested power from the proposed circuits. This approach supports the operation of the networks safe and continuous even when a shortage of harvested power happens due to bad conditions such as cloudy or rainy days. This work shows promise and is applicable
Innovative Computational Approach to Harmonic Mitigation for Seven-level Cascaded H-Bridge Inverters
No full textLow frequency modulation strategies are a good solution to increase the energy conversion efficiency in high power applications. The paper is devoted to presents an innovative way to low order harmonics mitigation for seven-level Cascaded H-Bridge Inverters. In particular, this approach is based on the mitigation of selected harmonics without solve non-linear equations for an extended range of the fundamental amplitude. In fact, in real-Time operation to evaluate the control angles the polynomial equations have been identified. Through circuit simulation analysis in MatLab/PLECS environment, the effectiveness of the harmonic mitigation method has been tested and compared with theoretical results
A Novel Framework of Hybrid Harvesting Mechanisms for Remote Sensing Devices
No full textSensing networks have recently proven to be useful in a variety of disciplines. The use of mobile sensing robots and unmanned aerial vehicles (UAVs) is intended to lessen the burden of sensor node energy consumption. However, conserving energy in the networks remains a major concern. In this work, a design of a hybrid RF-Solar harvesting system to support sensing devices is investigated. The harvesting circuits may collect energy from both solar and radio frequency (RF) resources that are commonly available in ambient environments. This approach creates hybrid harvesting circuits for all elements in the combined sensor networks by combining RF and solar harvester circuits. The RF harvester circuit is a dual-band multi-stage harvester for the 2.4GHz Wi-Fi/WLAN spectrum. In the solo solar harvester circuit, a solar panel with a maximum power point tracking (MPPT) algorithm is employed. The hybrid system can offer a maximum power of up to 136.5W due to a boost current element in the charging system. Because each node has a rechargeable battery, the gathered power from the proposed circuits is used to charge all of the batteries. This strategy allows networks to run safely and continuously even when there is a scarcity of gathered electricity due to severe weather, as cloudy or rainy days. This work is both promising and practical
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