• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 75
  • 42
  • 18
  • 8
  • 6
  • 4
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 192
  • 59
  • 48
  • 41
  • 34
  • 30
  • 24
  • 23
  • 21
  • 21
  • 20
  • 20
  • 19
  • 19
  • 19
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Analýza využití funkce breaker/limiter u odběrných míst nízkého napětí / Analyses of the breaker/limiter functions for low voltage supply points

Bajánková, Denisa January 2017 (has links)
The diploma thesis provides an insight into the remote control and disconnection of DSO supply points phenomenon. The remote or local disconnection/connection of supply point is allowed by the breaker function. The automatic disconnection of supply point is enabled by the limiter function. Due to the anticipated implementation of smart meters in the Czech Republic in the future, this work contains the comprehensive description of breaker/limiter function with proposed possibilities of use in the Czech Republic. The thesis deals with the current breaker/limiter function use in the Czech Republic and in other countries. It introduces the smart meter installation in pilot projects to analyze the breaker/limiter function use in other countries. The thesis is focused on the technical solution of breaker/limiter. Moreover, it describes the ways of connecting the breaker, settting the limiter, connecting/disconnecting a supply point and breaker operation. Further, the thesis introduces the ways of activating the breaker by a customer and defines in which cases it is possible to limit and interrupt the electricity supply in the Czech Republic currently. The main aim of thesis is to describe the specific possibilities of breaker/limiter function use in the Czech Republic. With regard to the function use in other countries and the limiting or interrupting the electricity supply by DSO according to energy law, the possibilities of use are proposed. Each possibility of use is analyzed when implementing the breaker function or the breaker/limiter function. The benefits are defined for a DSO and for a customer. The proposed uses are evaluated in terms of applicability and valid legislation in the Czech Republic. The result of this work is the summary of information about breaker/limiter function which is one of the new features in the implementation of smart metering. The function installation and the implementation of possibilities described in the thesis depends on the DSO decision.
122

Assessing and Predicting the Impact of Energy Conservation Measures Using Smart Meter Data

Collard, Sophie January 2014 (has links)
Buildings account for around 40 percent of the primary energy consumption in Europe and in the United States. They also hold tremendous energy savings potential: 15 to 29 percent by 2020 for the European building stock according to a 2009 study from the European Commission. Verifying and predicting the impact of energy conservation measures in buildings is typically done through energy audits. These audits are costly, time-consuming, and may have high error margins if only limited amounts of data can be collected. The ongoing large-scale roll-out of smart meters and wireless sensor networks in buildings gives us access to unprecedented amounts of data to track energy consumption, environmental factors and building operation. This Thesis explores the possibility of using this data to verify and predict the impact of energy conservation measures, replacing energy audits with analytical software. We look at statistical analysis techniques and optimization algorithms suitable for building two regression models: one that maps environmental (e.g.: outdoor temperature) and operational factors (e.g.: opening hours) to energy consumption in a building, the other that maps building characteristics (e.g.: type of heating system) to regression coefficients obtained from the first model (which are used as energy-efficiency indicators) in a building portfolio. Following guidelines provided in the IPMVP, we then introduce methods for verifying and predicting the savings resulting from the implementation of a conservation measure in a building.
123

Individual metering and charging of heat and hot water in row house areas - Comparing study of two row house areas in Stockholm / Individuell mätning av värme och varmvatten i radhusområden - Jämförande studie av två radhusområden i Stockholm

Åhlander Cevallos, Viktor, Åström, Henrik January 2014 (has links)
In today’s society our residents and premises consume 38 % of the total energy use in Sweden. 2011 that number corresponded to 77,8 TWh/year. Governments and the public’s strive to lower the energy use and the European Union’s goal that all member countries should lower their energy consumption with 20 % until year 2020 creates incentives to renovations and energy efficiency measures. A possible measure that could lead to reduced energy consumption for rental apartments and smaller residences like row-houses is to install individual metering. Individual metering is a method to measure how much energy is consumed in residences. Devices are installed in homes and can measure the water and heat consumption and let the residence pay for what is actually used. In this report the consumption and the costs for heat and warm water and the attitude to individual metering between two row-house areas is investigated. Both areas are located in Stockholm, in Huddinge and Farsta, where one of the areas has installed individual metering. Our study shows difference of the consumption and costs between the two areas. The installation of individual metering has result in a higher awareness for the people living in that area which has led to a reduced consumption and cost. The attitude for individual metering is positive in both areas and unchanged after the installation of individual metering. / I dagens samhälle förbrukar våra bostäder och lokaler ca 38 % av den totala energianvändningen i Sverige. 2011 motsvarade den siffran 77,8 TWh/år. Myndigheter och allmänhetens strävan att minska energiförbrukningen och EU:s målsättning att alla medlemsländer ska sänka sin energikonsumtion med 20 % fram till år 2020 skapar incitament för renoveringar och energieffektiviseringsåtgärder. En möjlig åtgärd för hyreslägenheter och mindre boenden som radhusområden är införandet av individuell mätning. Individuell mätning är en metod för att mäta energiförbrukningen i bostäder. Mätare installeras i hemmen och kan mäta vatten och värme och låter de boende betala för det de faktiskt konsumerar. I rapporten undersöks förbrukningen och kostnaderna för värme och varmvatten samt hur de boendes inställning är till individuell mätning mellan två radhusområden. Båda är belägna i Stockholm, i Huddinge respektive Farsta, där ett av områdena har infört individuell mätning. Studien visar skillnader på förbrukningen och kostnaderna mellan områdena jämfört med det andra området). Införandet av individuell mätning har medfört att de boende i området fått en högre medvetenhet vilket lett till en minskad förbrukning och kostnad. Inställningen och attityden till individuell mätning är lika positiv i båda områdena och attityden är oförändrad efter införandet i det området.
124

Analysis of the Effects of Adaptive Ramp Metering on Measures of Efficiency with a Proposed Framework for Safety Evaluation

Loh, Jacky 01 June 2019 (has links) (PDF)
Adaptive ramp metering (ARM) is a widely popular intelligent transportation system (ITS) tool that boasts the ability to reduce congestion and streamline traffic flow during peak hour periods while maintaining a lower implementation cost than traditional methods such as freeway widening. This thesis explores the effectiveness of ARM implementation on an 18 mile segment of the Interstate 80 (I-80) corridor in the Bay Area residing in northern California. Smaller segments of this particular segment were analyzed to determine the effective length of ARM on efficiency at various lengths originating from a known bottleneck location. Efficiency values were also compared against a control segment of the Interstate 280 (I-280) in San Jose to provide a test site experiencing similar traffic congestion but without any ARM implementation. An Empirical Bayes analysis was conducted to provide the foundation of a safety evaluation of the ramp metering implementation and determine a counterfactual estimate of expected collisions had ARM implementation not occurred. It was found that the installation of the ramp meters did allow for some marginal increases in efficiency but may not be entirely associated with ARM implementation due to a variety of external factors as well as showing inconsistent behavior between analyzed segments. Regarding safety, the predictive model estimates 32.8 collisions to occur along a 0.5 mile segment within a three-year timeframe if ARM were not installed, which implies substantial improvements in safety conditions. However additional efficiency and safety data within the “after” period may be necessary to provide a more robust and conclusive evaluation as the ARM system is still relatively new.
125

Implementation Strategies For Real-time Traffic Safety Improvements On Urban Freeways

Dilmore, Jeremy Harvey 01 January 2005 (has links)
This research evaluates Intelligent Transportation System (ITS) implementation strategies to improve the safety of a freeway once a potential of a crash is detected. Among these strategies are Variable Speed Limit (VSL) and ramp metering. VSL are ITS devices that are commonly used to calm traffic in an attempt to relieve congestion and enhance throughput. With proper use, VSL can be more cost effective than adding more lanes. In addition to maximizing the capacity of a roadway, a different aspect of VSL can be realized by the potential of improving traffic safety. Through the use of multiple microscopic traffic simulations, best practices can be determined, and a final recommendation can be made. Ramp metering is a method to control the amount of traffic flow entering from on-ramps to achieve a better efficiency of the freeway. It can also have a potential benefit in improving the safety of the freeway. This thesis pursues the goal of a best-case implementation of VSL. Two loading scenarios, a fully loaded case (90% of ramp maximums) and an off-peak loading case (60% of ramp maximums), at multiple stations with multiple implementation methods are strategically attempted until a best-case implementation is found. The final recommendation for the off-peak loading is a 15 mph speed reduction for 2 miles upstream and a 15 mph increase in speed for the 2 miles downstream of the detector that shows a high crash potential. The speed change is to be implemented in 5 mph increments every 10 minutes. The recommended case is found to reduce relative crash potential from .065 to -.292, as measured by a high-speed crash prediction algorithm (Abdel-Aty et al. 2005). A possibility of crash migration to downstream and upstream locations was observed, however, the safety and efficiency benefits far outweigh the crash migration potential. No final recommendation is made for the use of VSL in the fully loaded case (low-speed case); however, ramp metering indicated a promising potential for safety improvement.
126

Integrating the Built and Natural Environments Through Renewable Energy Technologies: supplying wind power to Kirkmont Center

Cerny, Mark A. 02 May 2006 (has links)
No description available.
127

Prices in Wholesale Electricity Markets and Demand Response

Aketi, Venkata Sesha Praneeth 02 June 2014 (has links)
No description available.
128

Fluidic Energy Harvesting and Sensing Systems

Alrowaijeh, Jamal Salem 09 July 2018 (has links)
Smart sensors have become and will continue to constitute an enabling technology to wirelessly connect platforms and systems and enable improved and autonomous performance. Automobiles have about two hundred sensors. Airplanes have about eight thousand sensors. With technology advancements in autonomous vehicles or fly-by-wireless, the numbers of these sensors is expected to increase significantly. The need to conserve water and energy has led to the development of advanced metering infrastructure (AMI) as a concept to support smart energy and water grid systems that would respond to emergency shut-offs or electric blackouts. Through the Internet of things (IoT) smart sensors and other network devices will be connected to enable exchange and control procedure toward reducing the operational cost and improving the efficiency of residential and commercial buildings in terms of their function or energy and water use. Powering these smart sensors with batteries or wires poses great challenges in terms of replacing the batteries and connecting the wires especially in remote and difficult-to-reach locations. Harvesting free ambient energy provides a solution to develop self-powered smart sensors that can support different platforms and systems and integrate their functionality. In this dissertation, we develop and experimentally assess the performance of harvesters that draw their energy from air or water flows. These harvesters include centimeter-scale micro wind turbines, piezo aeroelastic harvesters, and micro hydro generators. The performance of these different harvesters is determined by their capability to support wireless sensing and transmission, the level of generated power, and power density. We also develop and demonstrate the capability of multifunctional systems that can harvest energy to replenish a battery and use the harvested energy to sense speed, flow rate or temperature, and to transmit the data wirelessly to a remote location. / PHD
129

Betriebsstrategien und regenerative Betriebsmodi für Ventilsysteme mit getrennten Steuerkanten in bedienergeführten Anwendungen

Lübbert, Jan Frederik 18 June 2024 (has links)
Hersteller mobiler Arbeitsmaschinen sind im Zuge des angestrebten CO2-Ausstiegs zunehmendem Druck ausgesetzt, die Energieeffizienz ihrer Maschinen zu verbessern. Insbesondere vor dem Hintergrund der Elektrifizierung der Antriebssysteme als Alternative zu konventionellen fossil betriebenen Verbrennungsmotoren gewinnt die Energieeffizienz wesentlich an Bedeutung. Wurden Ventilsysteme mit getrennten Steuerkanten (gSk) aufgrund der tendenziell höheren Kosten bisher oft verworfen, so lohnt sich ihr Einsatz in Zeiten teurer Energie und hoher Preise für elektrische Akkukapazität jetzt zunehmend. In den vergangenen Jahrzehnten wurde bereits sehr viel Forschungsarbeit auf dem Gebiet der gSk geleistet. Viele publizierte Ansätze zur Bewegungssteuerung, also der Steuerung von Druck und Volumenstrom, in diesen Mehrgrößensystemen zeichnen sich durch eine hohe Komplexität der Algorithmen und/oder die Notwendigkeit hoch leistungsfähiger Ventiltechnik aus. Aus der Nutzung regenerativer Betriebsmodi zur Energieeinsparung resultiert in vielen Fällen die Notwendigkeit einer Umschaltung zwischen den Modi in der laufenden Bewegung. Vergleiche der jeweils vorgeschlagenen Lösungen erfolgen meistens nur mit einer konventionellen Referenz, nicht aber untereinander, sodass dem Entwickler verborgen bleibt, welcher Lösungsansatz für die Probleme Bewegungssteuerung und Modusumschaltung in der betrachteten Anwendung am besten geeignet ist. Zudem wird bei der Entwicklung energiesparender Betriebsstrategien, also der situationsabhängigen Wahl von Solldrücken und Betriebsmodi, in der vorliegenden Literatur kaum auf die Auswirkungen der vorgeschlagenen Lösungen auf das Bedienverhalten der Maschine eingegangen. Die vorliegende Arbeit soll diese Lücken schließen. Es werden verschiedene Steuerungs- und Regelungsansätze für Druck und Volumenstrom eines gSk-Systems vorgestellt, die sich durch einfache Gleichungen und eine Parametrierung nahezu ausschließlich mit leicht verfügbaren Konstruktionsdaten, sowie Unempfindlichkeit gegenüber Parameterschwankungen im Betrieb der Maschine auszeichnen. Teilweise kommen dabei Druckwaagen oder Druckregelventile als hydraulische Regler zum Einsatz. Die Algorithmen werden mittels der linearen Systemtheorie auf Stabilität untersucht und - soweit notwendig - Prüf- und Einstellverfahren hergeleitet. Die Arbeit stellt heraus, welche nachteiligen Auswirkungen eine energieoptimale Betriebsstrategie auf das Bedienverhalten hat und schlägt als Lösung einen energetischen Kompromiss bei ungestörter Bedienbarkeit vor. Ein Wechsel zwischen verschiedenen Betriebsmodi in der laufenden Bewegung ist mit einer stetigen Umschaltung mit einem Kurzschlussventil, einer stetigen Umschaltung mit einem Rückschlagventil, sowie einer störungsfreien diskreten Umschaltung mit einer Druckwaage realisierbar. Diese drei und die aus der Literatur bekannte diskrete Umschaltung ohne weiter Maßnahmen werden miteinander verglichen. Die aus den theoretischen Vorüberlegungen favorisierten Lösungsansätze für die vorgenannten Themengebiete Bewegungssteuerung, Betriebsstrategie und Modusumschaltung werden an einem Baggerarm-Laborprüfstand mit verschiedenen Ventilsystemen in realitätsnahmen Szenarien validiert, wobei der Schwerpunkt der Versuche auf der Analyse des Bedienverhaltens und der Komponentenanforderungen liegt. Die Ergebnisse zeigen, dass es unter Beachtung und Umgehung einiger in der Arbeit identifizierter Fallstricke möglich ist, mit mobiltypischer Hardware und einfachen Algorithmen ein gut bedienbares und energieeffizientes gSk-System aufzubauen. Weiterhin bilden die erreichten Ergebnisse die Basis für anforderungsabhängige Empfehlungen bestimmter Ansätze für die jeweiligen Detailfragen Bewegungssteuerung, Modusumschaltung und Betriebsstrategie. Damit ist dem Ingenieur ein Leitfaden zur anwendungsabhängigen Entwicklung eines gSk-Ventilsystems gegeben.
130

The analysis of primary metered half-hourly electricity and gas consumption in municipal buildings

Ferreira, Vasco Guedes January 2009 (has links)
This thesis addressed the need for improved analysis and interpretation of primary meter half-hourly energy consumption data. The current work offers a novel benchmarking technique that was tested for 6 types of municipal buildings. This approach is different from conventional annual benchmarking mainly because it uses electricity and gas data in half-hourly periods, together with outside temperature data. A survey to European local authorities’ metering and monitoring practices was conducted in order to assess municipal energy managers' current procedures and needs in terms of data analysis to assess building energy performance and to identify potential energy saving opportunities. The benchmarking approach was developed considering the energy managers’ needs, but also the state-of the art in terms of building energy monitoring techniques, particularly building energy signatures, and the analysis techniques used on electricity grid demand forecasting. The benchmarking approach is based on the use of a metric composed of several indicators that are related to the load demand shape profile and the building energy signature. The comparison of indicators for buildings of the same type using standard scores identifies uncommon load demand profile characteristics and/or gas dependency on outside temperature in specific buildings. The metric is able to support the identification of potential energy wastage, which is linked to the detection of opportunities to save energy. The benchmarking technique was tested in 81 municipal building owned by Leicester City Council. This methodology can be applied to any non-domestic building equipped with primary meters for registering half-hourly electricity and gas consumption. In theory, this approach can also be applied to residential buildings, and to other short time series data types, for example quarter-hourly or 10 minutes interval data. The main contribution of this thesis is to improve the objectivity of building primary meter half-hourly electricity and gas consumption data analysis and interpretation by using quantitative parameters, instead of subjective visualisation techniques. The interpretation of building consumption data in short time series periods can now be streamlined, automated and perhaps incorporated in existing energy analysis software. This thesis raises questions that can lead to future research projects aiming to improve the metric and also to enlarge the scope of its application to national and European scale, to other building types and to other utilities.

Page generated in 0.1128 seconds