Araştırma Çıktıları | TR-Dizin | WoS | Scopus | PubMedResearch Outputs | TR-Dizin | WoS | Scopus | PubMedhttps://hdl.handle.net/20.500.12573/3932024-03-29T12:10:05Z2024-03-29T12:10:05ZInequality in leisure mobility: An analysis of activity space segregation spectra in the Stockholm conurbationToger, MarinaTürk, UmutÖsth, JohnKourtit, KarimaNijkamp, Peterhttps://hdl.handle.net/20.500.12573/20582024-03-29T11:38:44Z2023-01-01T00:00:00ZInequality in leisure mobility: An analysis of activity space segregation spectra in the Stockholm conurbation
Toger, Marina; Türk, Umut; Östh, John; Kourtit, Karima; Nijkamp, Peter
Leisure mobility forms an important part of people’s spatial activity and mobility spectrum. This study aims to
analyse the inequality dimensions of spatial mobility of individuals who seek to move to recreational and leisure
destinations (often ‘green’ and ‘blue’) on designated days. The study traces – through the use of spatially
dependent multilevel models – the mobility patterns of people from the greater Stockholm area, using individual
pseudonymised mobile phone data and other publicly accessible data. We find significant socio-demographic
inequalities in the observed residents’ spatial leisure choices, where less affluent groups display especially low
variation in mobility when comparing between weekdays, weekends, vacation season and work-periods.
2023-01-01T00:00:00ZInstantaneous torque error compensation based online torque sharing function for Switched reluctance MachinesGenc, UfukTekgun, Burakhttps://hdl.handle.net/20.500.12573/20572024-03-29T08:33:00Z2023-01-01T00:00:00ZInstantaneous torque error compensation based online torque sharing function for Switched reluctance Machines
Genc, Ufuk; Tekgun, Burak
An online torque sharing function (TSF) with instantaneous torque error compensation
method for switched reluctance machines is proposed to maintain a minimized ripple operation.
The proposed method adjusts the shared torque between the phases based on instantaneous torque
error different than the existing TSF methods formulated with a mathematical expression. The
objective of this approach is to benefit from the outgoing phase torque as it has slow current
dynamics due to the high inductance. Also, the incoming phase is turned on as soon as it can generate positive torque. During this process, the total torque is estimated instantaneously using
lookup tables, and a correction current is calculated and injected into the incoming phase reference
current as the inductance is low and current dynamics are fast. This way, the torque ripple is
reduced for a wide speed range. Compared to the conventional linear, sinusoidal, exponential,
and cubic TSFs, better torque ripple performance is obtained
2023-01-01T00:00:00ZAnalysis of electret-based vibration energy harvesting devices with curved-beam hingesHah, Dooyounghttps://hdl.handle.net/20.500.12573/20552024-03-29T08:06:34Z2023-01-01T00:00:00ZAnalysis of electret-based vibration energy harvesting devices with curved-beam hinges
Hah, Dooyoung
Recently, vibration energy harvesting devices have gained growing interests. One of the main requirements for them is a broad bandwidth owing to stochastic spectral characteristics of the general vibration sources. Among various approaches for wide bandwidth, curved-beam hinges are quite attractive due to their simple structures. Although there have been several reports on curved beams, a more detailed study is needed. The device under study is an electret-based one with balanced comb-drive configuration. The whole system is modeled by using nonlinear stochastic differential equations. The numerical analysis results show that there is an optimum curve height for maximum power output, which depends on various conditions, such as external vibration strength, comb-drive dimensions, and initial electret charges. At the external acceleration magnitude of 0.02g and 0.05g, the device with curved beams can produce up to 2.9 times and 4.8 times higher power output, respectively, than one with straight beams for given device geometries. To the contrary, at lower and higher vibration magnitudes, straight-beam devices harvest more energy than curved-beam ones. Therefore, it can be concluded that the curved beam height needs to be carefully determined based on the conditions of the application, especially on the characteristics of the external vibration sources.
2023-01-01T00:00:00ZA dynamic connectedness analysis between rare earth prices and renewable energyMadaleno, MaraTaskin, DilvinDogan, EyupTzeremes, Panayiotishttps://hdl.handle.net/20.500.12573/20542024-03-29T07:51:05Z2023-01-01T00:00:00ZA dynamic connectedness analysis between rare earth prices and renewable energy
Madaleno, Mara; Taskin, Dilvin; Dogan, Eyup; Tzeremes, Panayiotis
Current world environmental challenges put pressure on clean energy produced mostly through renewables.
There is an undeniably important role of rare earth minerals in renewable energy technologies. This study aims
to infer the relationship between rare earth, clean energy, renewable energy technologies, and carbon emissions,
focusing on daily stock price index data and applying the novel quantile time-frequency connectedness model,
and the cross-quantilogram dependence approach during 2012–2022. Results show that spillovers among rare
earth minerals and renewable energy are dependent on market conditions, time horizons, and analyzed quantiles. They also highlight the net receiver role of rare earth, especially in the short term. Findings might help
investors understand diversification benefits and support policymakers in developing strategies for lessening
import dependence on rare earth metals, as important as they are for renewable technology adoption to ensure
green growth.
2023-01-01T00:00:00Z