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  • 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.
131

Snímače proudu / Current Sensors

Vaculík, Vlastimil January 2012 (has links)
This diploma theisis deals with the theoretical analysis of the known types of current sensors, including for example, current transformers, shunts, and advanced sensors using Hall sensor or Rogowski coil. Subsequently, the rest of the work deals with the issue of current transducers with Hall sensors, without using a ferromagnetic circuit. For optimal currnet measure and overall precision, several possible options are designed and calculated. This includes number of sensing elements and distribution of sensors around the wires. Based on calaculation of magnetic intensity, related 3D charts ale plotted unsing Excel software. These charts illustrate the theoretical calculations of field distribution around conductors for various number of sensor. In the last part, components ale designed for practical implementation and scheme of electrical wiring. According to this scheme there is PCB designed as well. Whole current meter ir practically build and its results are compared with theoretical assumtions that are discussed in conclusion part of this theisis.
132

Zařízení na výrobu vlákna z termoplastu PET pro použití k 3D tisku metodou FDM / An equipment for PET filament producing for 3D printing usage

Kotačka, Petr January 2016 (has links)
This thesis deals with design of equipment for the production of PET termoplastic fibre to be used in 3D printing by means of FDM method. Concise survey of plastics processing methods is presented herein, furthermore, structural design of equipment with necessary engineering calculations is included as well. Drawing documents with the total economic evaluation is a part of this thesis too.
133

The Influence of non-invasive Prefrontal/Frontal Brain Stimulation on Food Reappraisal Abilities and Calorie Consumption in Obese Females

Grundeis, Felicitas 25 November 2019 (has links)
Previous studies suggest that non-invasive transcranial direct current stimulation (tDCS) applied to the prefrontal cortex modulates food choices and calorie intake in obese humans. In a fully randomized, placebo-controlled, within-subject and double-blinded study, we applied single sessions of anodal, cathodal, and sham tDCS to the left dorsolateral prefrontal cortex (DLPFC) and contralateral frontal operculum in 25 hungry obese women and investigated possible influences on food reappraisal abilities as well as calorie intake. We hypothesized that tDCS, (i) improves the ability to regulate the desire for visually presented foods and, (ii) reduces their consumption. We could not confirm an effect of anodal or cathodal tDCS, neither on the ability to modulate the desire for visually presented foods, nor on calorie consumption. The present findings do not support the notion of prefrontal/frontal tDCS as a promising treatment option for obesity.:1. Introduction 1.1 Obejective of investigation 1.1.1 Obesity 1.1.2 Homeostasis versus hedonism? 1.1.3 Regulating the desire to eat 1.1.4 Obesity and the brain 1.2 Previous studies 1.2.1 EEG study 1.2.2 Buffet study 1.3 Transcranial direct current stimulation (TDCS) 1.4 TDCS study 2 Publication 3 Summary of work 3.1 Data Acquisition ans analysis 3.2 Results and discussion 3.2.1 Absence of evidence is not evidence of absence 3.2.2 Multifactorial influence on behavior 3.2.3 Limitations of study design 3.2.4 Limitations of method 3.3 Outlook 4 References 5 Attachments 5.1 Academic contribution 5.2 Erklärung über die eigenständige Abfassung der Arbeit 5.3 Einreichungserklärung 5.4 Curriculum vitae 5.5 Publications 5.6 Acknowledgements
134

Mind wandering regulation by non-invasive brain stimulation / 非侵襲脳刺激法によるマインドワンダリング制御

Kajimura, Shogo 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(教育学) / 甲第20127号 / 教博第204号 / 新制||教||167(附属図書館) / 京都大学大学院教育学研究科教育科学専攻 / (主査)准教授 野村 理朗, 教授 齊藤 智, 教授 Emmanuel MANALO / 学位規則第4条第1項該当 / Doctor of Philosophy (Education) / Kyoto University / DGAM
135

Traumatic brain injury and its impact on working memory : A systematic review

Hallgren, Li, Mohammed, Naema Adani January 2023 (has links)
The purpose of this systematic review is to provide insight into the impact traumatic brain injury (TBI) has on the executive function known as the working memory. TBI is a damage to the brain that occurs when the brain is critically injured to the degree that it impacts several brain regions and functions such as the hippocampus, its surrounding areas, the prefrontal cortex, and the performance of the working memory ability. TBI may occur from bleeding or infraction (stroke), lack of oxygen after cardiac arrest (anoxic brain injury), or diseases such as brain tumours or infections in the brain (encephalitis/meningitis). Working memory is the ability that maintains and manipulates information such as judgment and decision-making. TBI impacts several cognitive and executive functions such as the working memory. The implications that TBI has on working memory is that it relatively decreases the activation and connectivity capacity among the main areas of the working memory network which may result in difficulties of attention and concentration. This review summarises five studies about TBI and working memory that uses different working memory task while examiningwith brain imaging techniques. The studies conclude that TBI has a negative impact on working memory since the ability becomes weak.
136

Cerebellar Transcranial Direct Current Stimulation Improves Maximum Isometric Force Production during Isometric Barbell Squats

Kenville, Rouven, Maudrich, Tom, Maudrich, Dennis, Villringer, Arno, Ragert, Patrick 13 April 2023 (has links)
Maximum voluntary contraction force (MVC) is an important predictor of athletic performance as well as physical fitness throughout life. Many everyday life activities involve multi-joint or whole-body movements that are determined in part through optimized muscle strength. Transcranial direct current stimulation (tDCS) has been reported to enhance muscle strength parameters in single-joint movements after its application to motor cortical areas, although tDCS effects on maximum isometric voluntary contraction force (MIVC) in compound movements remain to be investigated. Here, we tested whether anodal tDCS and/or sham stimulation over primary motor cortex (M1) and cerebellum (CB) improves MIVC during isometric barbell squats (iBS). Our results provide novel evidence that CB stimulation enhances MIVC during iBS. Although this indicates that parameters relating to muscle strength can be modulated through anodal tDCS of the cerebellum, our results serve as an initial reference point and need to be extended. Therefore, further studies are necessary to expand knowledge in this area of research through the inclusion of different tDCS paradigms, for example investigating dynamic barbell squats, as well as testing other whole-body movements.
137

tDCS over the primary motor cortex contralateral to the trained hand enhances cross-limb transfer in older adults

Kaminski, Elisabeth, Maudrich, Tom, Bassler, Pauline, Ordnung, Madeleine, Villringer, Arno, Ragert, Patrick 29 February 2024 (has links)
Transferring a unimanual motor skill to the untrained hand, a phenomenon known as cross-limb transfer, was shown to deteriorate as a function of age. While transcranial direct current stimulation (tDCS) ipsilateral to the trained hand facilitated cross-limb transfer in older adults, little is known about the contribution of the contralateral hemisphere to cross-limb transfer. In the present study, we investigated whether tDCS facilitates cross-limb transfer in older adults when applied over the motor cortex (M1) contralateral to the trained hand. Furthermore, the study aimed at investigating short-term recovery of tDCS-associated cross-limb transfer. In a randomized, doubleblinded, sham-controlled setting, 30 older adults (67.0 4.6 years, 15 female) performed a short grooved-pegboard training using their left hand, while anodal (a-tDCS) or sham-tDCS (s-tDCS) was applied over right M1 for 20 min. Left (LHtrained) - and right-hand (RHuntrained) performance was tested before and after training and in three recovery measures 15, 30 and 45 min after training. LHtrained performance improved during both a-tDCS and s-tDCS and improvements persisted during recovery measures for at least 45 min. RHuntrained performance improved only following a-tDCS but not after s-tDCS and outlasted the stimulation period for at least 45 min. Together, these data indicate that tDCS over the M1 contralateral to the trained limb is capable of enhancing cross-limb transfer in older adults, thus showing that cross-limb transfer is mediated not only by increased bi-hemispheric activation.
138

Predicting Vigilance Performance Under Transcranial Direct Current Stimulation

Bridges, Nathaniel Reese 05 July 2011 (has links)
No description available.
139

Planning and Operation of Hybrid AC-DC Microgird with High Penetration of Renewable Energy Sources

Baseer, Muhammad January 2022 (has links)
A hybrid ac/dc microgrid is a more complex but practical network that combines the advantages of an AC and a DC system. The main advantage of this network is that it connects both alternating current and direct current networks via an interlinking converter (IC) to form a unified distribution grid. The hybrid microgrid (HMG) will enable the direct integration of both alternating current (AC) and direct current (DC) distributed generators (DGs), energy storage systems (ESS), and alternating current and direct current (DC) loads into the grid. The alternating current and direct current sources, loads, and ESS are separated and connected to their respective subgrids primarily to reduce power conversion and thus increase overall system efficiency. As a result, the HMG architecture improves power quality and system reliability. Planning a hybrid microgrid entails estimating the capacities of DGs while taking technical, economic, and environmental factors into account. The hybrid ac-dc microgrid is regarded as the distribution network of the future, as it will benefit from both ac and dc microgrids. This thesis presents a general architecture of a hybrid ac-dc microgrid, which includes both planning and design. The goal of the Hybrid ac-dc microgrid planning problem is to maximise social welfare while minimising total planning costs such as investment, maintenance, and operation costs. This configuration will assist Hybrid microgrid planners in estimating planning costs while allowing them to consider any type of load ac/dc and DER type. Finally, this thesis identifies the research questions and proposes a future research plan.
140

Improvement and Assessment of Two-Dimensional Resistivity Models Derived from Radiomagnetotelluric and Direct-Current Resistivity Data

Kalscheuer, Thomas January 2008 (has links)
Two-dimensional (2-D) models of electrical resistivity are improved by jointly inverting radiomagnetotelluric (RMT) and direct-current resistivity (DCR) data or by allowing for displacement currents in the inversion of RMT data collected on highly resistive bedrock. Uniqueness and stability of the 2-D models are assessed with a model variance and resolution analysis that allows for the non-linearity of the inverse problem. Model variance and resolution are estimated with a truncated singular value decomposition (TSVD) of the sensitivity matrix. In the computation of model errors, inverse singular values are replaced by non-linear semi-axes and the number of included eigenvectors is increased until a given error threshold is reached. Non-linear error estimates are verified with most-squares inversions. For the obtained truncation levels, model resolution matrices are computed. For RMT data, non-linear error appraisals are smaller than linearized ones. Hence, the consideration of the non-linearity in RMT data leads to reduced model errors or enhanced model resolution. The dielectric effect on RMT data is investigated with a new 2-D forward and inverse code that allows for displacement currents. As compared to the quasi-static approximation, apparent resistivities and phases of the impedance tensor elements are found to be significantly smaller and the vertical magnetic transfer function exhibits more distinct sign reversals. More reliable models of electrical resistivity are obtained from areas with highly resistive bedrock, if displacement currents are allowed for. In contrast, inversions with a quasi-static scheme introduce artefactual structures with extremely low or high resistivities. A smoothness-constrained 2-D joint inversion of RMT and DCR data is presented. The non-linear model variance and resolution analysis is applied to single and joint inverse models. For DCR data, the errors estimated by most-squares inversions are consistently larger than those estimated by the non-linear semi-axes, indicating that DCR models are poorly resolved. Certain areas of the joint inverse models are better resolved than in the single inverse models.

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