17 research outputs found
Global Cities and Local Challenges: Booms and Busts in the London Real Estate Market
No full text© The Author(s) 2020. In this paper we investigate the dynamic features of house prices in London. Using a generalized smooth transition model (GSTAR) we show that dynamic symmetry in price cycles in the London housing market is strongly rejected. We also show that the GSTAR model is able to replicate the features of the observed cycle in the simulated data. Further, our results show that the proposed model performs well when compared to other linear and nonlinear specifications in a out-of-sample forecasting exercise.Università degli Studi di Torin
Correct Cross-Section of Cable Screen in a Medium Voltage Collector Network with Isolated Neutral of a Wind Power Plant
No full textThe article discusses the selection of cables for power lines connecting wind turbine generators at the wind power plant. The screen cross-section of these cables should be selected considering the value of the screen current at double line-to-earth fault. To calculate this current, the dimensions of the cable should be known. However, these parameters are hidden and cannot be used during designing. Therefore, a highly simplified method is currently used in practice. It is shown that the errors from the highly simplified method are up to 33%. Authors propose a simplified method based on open data of cable manufacturers. The proposed method is compared with simulation results of a common model of cable power line and takes into account self and mutual inductances of the cores and screens. It is shown that the error of the proposed method is smaller than 4.0% for real cable power lines at wind power plants. However, for a long section of cable power line (2.5 km) the error of calculation might increase up to 6.3%. This allows us to use the proposed method for designing. In addition, the authors show how the results of the highly simplified method can be corrected to improve accuracy
Synthesis of a self-reeling hose system for bathroom use
No full textThis work was carried out to design and test the self-reeling hose for bathroom use to achieve convenience and hygiene in the bathroom. The distribution of von Mises stress, displacement and safety factors were considered. SolidWorks, which is a solid modeling computer-aided design and engineering (CAD/CAE) software was used to integrate analysis and to help simulate physical interactions in engineering design such as stress, deflection and safety factors to match various parts of the self-reeling hose mechanisms. The House of Quality (HOQ) table was constructed to determine the engineering characteristics of the product. Three different design concepts were synthesized from the morphological chart and a design concept that was most critical to fulfilling the criteria was chosen using the method of Pugh concept selection. Consequently, the computer analysis and simulation for particular parts were done and the finalized assembly were presented. The bending force and torque of the ratchet and pawl system were calculated to ensure safety in its operation. Overall, the mechanism is safe to manufacture and use with the appropriate materials and design considerations
Collecting data in smart cities using energy harvesting technology
No full textThis work investigates the problems of extending the sensors network lifetime in smart cities. The limited capacity of the sensors’ batteries, and the difficulty of replacing the sensors’ batteries in hard-to-reach areas are some of the main challenges that contribute in reducing the lifetimes of the networks. The direction of this study is to use renewable energy as an energy source for collecting data from various infrastructures that are distributed throughout these cities. We present a model for data collection based on combining energy harvesting (EH) with the cluster head rotation feature, which results in flexible and sustainable networks that can be used in smart cities. Simulation results depict the performance of the proposed model with and without EH technology. The metrics used to compare the performance of the proposed model with and without EH technology include the consumed energy by sensors, number of live and dead sensors, and energy variance. The results show that the network lifetime increases when EH technology is used
Synthesis of a self-reeling hose system for bathroom use
No full textLink to publisher's homepage at http://ijneam.unimap.edu.myThis work was carried out to design and test the self-reeling hose for bathroom use to achieve
convenience and hygiene in the bathroom. The distribution of von Mises stress, displacement
and safety factors were considered. SolidWorks, which is a solid modeling computer-aided
design and engineering (CAD/CAE) software was used to integrate analysis and to help
simulate physical interactions in engineering design such as stress, deflection and safety
factors to match various parts of the self-reeling hose mechanisms. The House of Quality
(HOQ) table was constructed to determine the engineering characteristics of the product.
Three different design concepts were synthesized from the morphological chart and a design
concept that was most critical to fulfilling the criteria was chosen using the method of Pugh
concept selection. Consequently, the computer analysis and simulation for particular parts
were done and the finalized assembly were presented. The bending force and torque of the
ratchet and pawl system were calculated to ensure safety in its operation. Overall, the
mechanism is safe to manufacture and use with the appropriate materials and design
considerations
Initial Study On Safety Hazards by Heavy Transportation On Malaysian Roads
No full textA pilot study was done to evaluate the road safety in Malaysia that is related to heavy transportation. The project consisted of survey, analytical calculations, and computer simulations. The survey was conducted to investigate the use of current active safety features like the warning signs, which include lights, light reflective stickers, and the color of canvas used on heavy vehicles. Fortunately, light reflective stickers could be an aid to passively illuminate the heavy vehicles. The slow speed like 40 km/h commonly maintained by heavy vehicles when climbing up hills with heavy load is a hazard since being too slow may cause a more severe rear-end collision damage. Additionally, computer impact analyses were also done by using ABAQUS, where several collisions between a car and a heavy vehicle were studied. Hence, the conclusion can be made that the slower the speed of a heavy vehicle, the higher the stress experienced by the car colliding from behind the truck. It is recommended that the truck has about 376 kW power to pull a maximum load of 36,000 kg. Trucks are also suggested to maintain at least 60 km/h speed during hill climbing with a much lower load
Monitoring of power transformers using thermal model and permission time of overload
No full textThis paper presents the problem of increasing the reliability of electricity supply to consumers. Uninterrupted power supply to electricity consumers depends on the reliability of power supply system in general and power transformers in particular, the accident rate of which is quite high. The causes of the problem are the location of transformer substations at a considerable distance from the service centers, their spreading out over a large area, missing information about the current modes of their operation and so on. One of the ways to solve this problem is development and implementation a system for continuous diagnostics of power transformers. Failure analysis of power transformer based on fault tree is considered, the diagnostic parameters are determined. The insulation wear rate and permission operating time under overload have been defined with help of equivalent heat circuit. It is proposed to use a permission time as a parameter to diagnose the operation mode and increase the efficiency of maintenance of substations through remote monitoring based on the global service mobile (GSM) network. Remote diagnostics allows to receive an information about emergency situation timely. It helps to reduce operating costs, to ensure the reliability and quality of electricity supply for consumers
ZMIANA CHARAKTERYSTYKI CZĘSTOTLIWOŚCIOWEJ FILTRA Z WYKORZYSTANIEM DŁAWIKA O PŁYNNIE REGULOWANEJ INDUKCJI
No full textExperimental studies of the proposed reactor by the authors were carried out through direct measurements of electrical quantities. Structurally, the reactor is designed as a stator of an electric machine with a single pair of poles and a rotor without windings in the form similar to an elliptical shape with flat sides. The magnitude of the inductance varies by rotating the rotor within the range from zero to ninety degrees, where zero degrees corresponds to the alignment of the stator pole axis with the longer axis of the rotor. The effectiveness of using such a reactor to complement passive controlled harmonic current filters is confirmed by corresponding calculations. It is shown that one controlled filter can replace two or more precisely tuned filters capable of absorbing only certain current harmonics.Badania eksperymentalne proponowanego przez autorów reaktora przeprowadzono poprzez bezpośrednie pomiary wielkości elektrycznych. Konstrukcyjnie reaktor zaprojektowano jako stojan maszyny elektrycznej z pojedynczą parą biegunów i wirnikiem bez uzwojeń w kształcie zbliżonym do kształtu eliptycznego o płaskich bokach. Wielkość indukcyjności zmienia się poprzez obrót wirnika w zakresie od zera do dziewięćdziesięciu stopni, gdzie zero stopni odpowiada zrównaniu osi bieguna stojana z dłuższą osią wirnika. Efektywność zastosowania takiego dławika jako uzupełnienia pasywnych filtrów prądu harmonicznego potwierdzona jest odpowiednimi obliczeniami. Pokazano, że jeden kontrolowany filtr może zastąpić dwa lub więcej precyzyjnie dostrojonych filtrów zdolnych do pochłaniania tylko określonych harmonicznych prądu
Model sieci energetycznej oparty na zasadzie fraktalno-klastrowej
No full textEnergy systems with a significant share of distributed generation in modern energy play an increasingly important role and contribute to the green transition. In the Ukrainian energy sector, the introduction of distributed generation also occurs under conditions of military influence on energy infrastructure facilities, which additionally forces the distribution of generation facilities across the territory of the respective regions of the country. The fundamental difference between distributed generation systems and traditional power systems with concentrated generating capacities is the consumption of energy at the place of its generation. This sets the task of reviewing the general principles of building the configuration of electrical networks. The idealized model of the branched electrical network of the power system with distributed generation is proposed in the work, which takes into account the features of systems with distributed generation. This model is based on the fractal-cluster principle of forming the configuration of electrical networks. It is proposed to build an electrical distribution network based on a regular fractal. The assumptions and limitations of the model are defined. Modeling of the structure and configuration of electrical networks was carried out. The electrical power of the underlying network cluster is determined. The basic fractal properties of the proposed idealized distribution network model are determined. Circuit solutions of unified node substations and basic network cluster are proposed.Systemy energetyczne ze znacznym udziałem generacji rozproszonej w nowoczesnej energetyce odgrywają coraz ważniejszą rolę i przyczyniają się do zielonej transformacji. W ukraińskim sektorze energetycznym wprowadzenie generacji rozproszonej odbywa się również w warunkach wpływu wojskowego na obiekty infrastruktury energetycznej, co dodatkowo wymusza rozmieszczenie obiektów wytwórczych na terytorium poszczególnych regionów kraju. Podstawową różnicą między systemami generacji rozproszonej a tradycyjnymi systemami energetycznymi o skoncentrowanych mocach wytwórczych jest zużycie energii w miejscu jej wytwarzania. Stawia to przed nami zadanie przeglądu ogólnych zasad budowy konfiguracji sieci elektroenergetycznych. W pracy zaproponowano wyidealizowany model rozgałęzionej sieci elektroenergetycznej z generacją rozproszoną, który uwzględnia cechy systemów z generacją rozproszoną. Model ten opiera się na fraktalno-klastrowej zasadzie tworzenia konfiguracji sieci elektrycznych. Zaproponowano budowę elektrycznej sieci dystrybucyjnej w oparciu o regularny fraktal. Określono założenia i ograniczenia modelu. Przeprowadzono modelowanie struktury i konfiguracji sieci elektrycznych. Określono moc elektryczną podstawowego klastra sieci. Określono podstawowe właściwości fraktalne proponowanego wyidealizowanego modelu sieci dystrybucyjnej. Zaproponowano rozwiązania obwodowe zunifikowanych podstacji węzłowych i podstawowego klastra sieciowego
Initial Study On Safety Hazards by Heavy Transportation On Malaysian Roads
No full textA pilot study was done to evaluate the road safety in Malaysia that is related to heavy transportation. The project consisted of survey, analytical calculations, and computer simulations. The survey was conducted to investigate the use of current active safety features like the warning signs, which include lights, light reflective stickers, and the color of canvas used on heavy vehicles. Fortunately, light reflective stickers could be an aid to passively illuminate the heavy vehicles. The slow speed like 40 km/h commonly maintained by heavy vehicles when climbing up hills with heavy load is a hazard since being too slow may cause a more severe rear-end collision damage. Additionally, computer impact analyses were also done by using ABAQUS, where several collisions between a car and a heavy vehicle were studied. Hence, the conclusion can be made that the slower the speed of a heavy vehicle, the higher the stress experienced by the car colliding from behind the truck. It is recommended that the truck has about 376 kW power to pull a maximum load of 36,000 kg. Trucks are also suggested to maintain at least 60 km/h speed during hill climbing with a much lower load
