113 research outputs found
Mucuna pruriens Seed Extract Promotes Neurite Outgrowth via Ten-4 Dependent and Independent Mechanisms in Neuro2a Cells
No full textNeurological diseases are one of the serious health hazards faced by mankind for decades. Neurite outgrowth is a key factor responsible for proper neuronal development. Any misplacement in the process could lead to neurological diseases like Alzheimer’s and Parkinson’s. Treatment with the available synthetic drugs imparts many difficulties to the patients due to the side effects. Compounds from natural sources can be considered as an effective replacement for this. Mucuna pruriens, used in traditional ayurvedic medicine, contains L-3,4-dihydroxy phenylalanine (L-DOPA) in its seeds, which possesses medicinal effects against neurological diseases. In this regard, seed extracts of M. pruriens originated from Thailand and India, were analyzed for their neuroprotective effects in Neuro2a cells. Hexane, ethyl acetate and ethanol extracts were found to be non-toxic to the viability of the cells. Ethanol extracts of M. pruriens of Thai origin (MTE), hexane extracts of M. pruriens of Indian origin (MIH) and ethyl acetate extracts of M. pruriens of Indian origin (MIEA) were able to induce neurite outgrowth in Neuro2a cells. Interestingly, both MTE and MIH induced neurite outgrowth dependent on Teneurin-4 (Ten-4) transmembrane protein whereas MIEA did the same independent of Ten-4, which was confirmed by real time PCR and gene silencing approach. The present study suggested that M. pruriens can be used as a potential drug in the treatment of neurological diseases as it can induce neurite outgrowth by multiple mechanisms, which will be of great use in the field of medicine
Pilot based frameworks for weather research forecasting
No full textThe Weather Research Forecasting (WRF) domain consists of complex workflows that demand the use of Distributed Computing Infrastructure (DCI). Weather forecasting requires that weather researchers use different set of initial conditions and one or a combination of physics models on the same set of input data. For these type of simulations an ensemble based computing approach becomes imperative. Most DCIs have local job-schedulers that have no smart way of dealing with the execution of an ensemble type of computational problem as the job-schedulers are built to cater to the bare essentials of resource allocation. This means the weather scientists have to submit multiple jobs to the job-scheduler. In this dissertation we use Pilot-Job based tools to decouple work-load submission and resource allocation therefore streamlining the complex workflows in Weather Research and Forecasting domain and reduce their overall time to completion. We also achieve location independent job execution, data movement, placement and processing. Next, we create the necessary enablers to run an ensemble of tasks bearing the capability to run on multiple heterogeneous distributed computing resources there by creating the opportunity to minimize the overall time consumed in running the models. Our experiments show that the tools developed exhibit very good, strong and weak scaling characteristics. These results bear the potential to change the way weather researchers are submitting traditional WRF jobs to the DCIs by giving them a powerful weapon in their arsenal that can exploit the combined power of various heterogeneous DCIs that could otherwise be difficult to harness owing to interoperability issues.M.S.Includes bibliographical referencesby Dinesh Prasanth Ganapath
Data-driven spatial modeling of historic and future land change at global scale
No full textAssessing the historic and future impacts of land-use and land-cover change (LULCC) on climate requires spatially and temporally explicit data sets on LULCC spanning several decades to centuries, because climate change is a long-term problem. Though remote sensing data provides a globally consistent picture of land cover, these data are only available from the past four decades. Therefore, existing LULCC reconstructions are modeled estimates that combine remote sensing data with relatively coarser-resolution inventory statistics that covers longer historical period. The uncertainties in modeling assumptions, and limited availability and inconsistencies across inventory datasets among other reasons introduce uncertainties in LULCC reconstructions. These uncertainties not only limit our ability to model future LULCC, but also translate as uncertainties in both historic and future environmental assessments.
The objectives of my PhD work are as follows: (1) systematically investigate the causes of uncertainties in existing historical LULCC datasets, (2) test the sensitivity of LULCC quantification uncertainty in estimating CO2 emissions from LULCC (historic and future) using a process-based land-surface model, the Integrated Science Assessment Model (ISAM), (3) compare the relative uncertainties from various drivers (e.g. LULCC datasets, model processes e.g. nitrogen cycle, environmental factors such as climate) in estimating historic and future LULCC emissions, and (4) explore statistical techniques to model future LULCC that takes into account the uncertainties in quantifying the spatial and temporal patterns of LULCC, and (5) as a case-study, identify a key regional hotspot of historic LULCC quantification uncertainty (here, India), and reduce uncertainty through improved understanding of the dynamics and drivers of land change in the case-study region. I address the above goals by integrating land-surface modeling (ISAM), remote sensing and GIS, data collected through ground transects, and geospatial data on socioeconomics.
ISAM simulations show that the estimated net global emissions from LULCC (mean and range) across three different historical LULCC reconstructions are 1.88 (1.7 to 2.21) GtC/yr for the 1980’s, 1.66 (1.48 to 1.83) GtC/yr for the 1990's, and 1.44 (1.22 to 1.65) for the 2000's. The estimates are higher than other published estimates that range from 0.80 to 1.5 GtC/yr for the 1990’s and 1.1 GtC/yr for the 2000’s. These results are higher than other published estimates because they include the effects of nitrogen limitation on regrowth of forests following wood harvest and agricultural abandonment. The estimated LULUC emissions for the tropics are 0.79±0.25 for the 1980’s, 0.78±0.29 for the 1990’s and 0.71±0.33 GtC/yr for the 2000’s, and for the non-tropics regions are 1.08±0.52, 0.90±0.19 and 0.69±0.12 GtC/yr for the three decades. The model results indicate that failing to account for the nitrogen cycle underestimates LULCC emissions by about 40% globally (0.66 GtC/yr), 10% in the tropics (0.07 GtC/yr) and 70% in the non-tropics (0.59 GtC/yr). If LULCC emissions are higher than assessed, it means fossil fuel emissions would have to be even lower to meet the same mitigation target.
Extending ISAM simulations to the 21st century resulted in two key insights. First, nitrogen limitation of CO2 uptake is substantial and sensitive to nitrogen inputs. In ISAM, excluding nitrogen limitation underestimated global total LULUC emissions by 34-52 PgC (~21-29%) during the 20th century and by 128-187 PgC (90-150%) during the 21st century. The difference increases with time because nitrogen limitation will progressively down-regulate the magnitude of CO2 fertilization effect on regrowing forests, due to decreasing supply of plant-usable mineral nitrogen. Second, historically, the indirect effects of anthropogenic activity through environmental changes in land experiencing LULCC (indirect emissions) are small compared to direct effects of anthropogenic LULCC activity (direct emissions). As a result, including or excluding indirect emissions had a minor influence on the estimated total LULUC emissions historically. In contrast, the indirect LULCC emissions for the 21st century are a much larger source to the atmosphere, in simulations with nitrogen limitation. This is because of the gradual weakening of the photosynthetic response to elevated (CO2) caused by nitrogen limitation. Therefore, what fluxes are including in LULCC emissions across different models is a crucial source of uncertainty in future LULCC emissions estimates.
A detailed investigation of the sensitivity of different global-scale LULCC modeling techniques show that land use allocation approaches based solely on previous land use history (but disregarding the impact of driving factor), or those based on mechanistically fitting models for the spatial processes of land use change do not reproduce well long-term historical land use patterns. With an example application to the terrestrial carbon cycle, I show that such inaccuracies in land use allocation can translate into significant implications for global environmental assessments. In contrast to previous approaches, I present a statistical land use downscaling model and show that the model can reproduce the broad spatial features of the past 100 years of evolution of cropland and pastureland patterns. Therefore, the modeling approach and its evaluation provide an example that can be useful to the land use, Integrated Assessment, and the Earth system modeling communities.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Prasanth Meiyappan, accepted the attached license on 2016-04-13 at 20:33.The student, Prasanth Meiyappan, submitted this Dissertation for approval on 2016-04-13 at 20:39.This Dissertation was approved for publication on 2016-04-18 at 14:23.DSpace SAF Submission Ingestion Package generated from Vireo submission #9216 on 2016-07-07 at 14:16:41Made available in DSpace on 2016-07-07T21:14:41Z (GMT). No. of bitstreams: 3
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An Investigation of the Design and Development of a Multi Frequency Inductive Power Transfer System
No full textWith the current surge in the development and use of Electric Vehicles (EVs) due to increased environmental consciousness, methods to increase the driving range and improve the battery charging conditions of these vehicles have become important research areas. Inductive Power Transfer (IPT) is one of the solutions to the challenges currently faced by EV manufacturers and customers. IPT is a method that is used to transfer power over large air gaps and has proven to be efficient, reliable and convenient in the charging of electric vehicles and also for factory automation systems and charging of consumer devices such as mobile phones. In some cases, it necessary to have transmitter and receiver topologies having multiple coils especially in a three phase IPT highway system or a table top IPT system for charging many consumer devices or mobile phones at the same time. Multi coil topologies are also used in lumped charge pad topologies to enable better misalignment tolerances. In such cases it is necessary to mutually decouple these multiple coils to avoid interactions that could affect the efficiency of power transfer. The current state of the art systems offer solutions that lead to the decoupling of multiple coils by their relative spatial position, and are hence limited. Multi coil systems operating at the same frequency also generate magnetic fields that add or cancel out each other, thereby changing the air gap magnetic field orientation depending on which coil is powered. A multi frequency IPT system developed in this thesis aims to provide a solution to the above challenges. A multi coil primary system with two coils carrying currents of different frequencies can be designed to transfer power independently without interactions between the two different frequency systems. This thesis develops this concept by first investigating the need for decoupling multi coil transmitter and receiver designs. Multi frequency IPT is then introduced and the design considerations are developed in order to achieve a frequency decoupled IPT system. Experimental results of the proposed multi frequency method using two transmitter coils are also presented. Finally, a comparison is provided between this proposed multi frequency method using two transmitter coils and another recently published method that amplifies the third harmonic along with the fundamental from the input inverter, thereby achieving multi frequency IPT using one transmitter coil.DC Systems and StorageElectrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc
Electromagnetic Evaluation and Optimization of a Combined Inductive Power Transfer and Inductive Healing Road
No full textElectrical vehicles (EVs) can be charged wirelessly with an inductive power transfer (IPT) system that uses a magnetic field to deliver power to the EV. Such a system could be embedded in the highway to charge EVs while they are driving. The magnetic field of the IPT system is created using coils that are exited with a high frequency current. Recent developments has created a low maintenance asphalt that can be healed by means of induction heating. Steel wool is added to the asphalt to make it suitable for induction heating, which is also done using coils that are exited with high frequency currents. This thesis will investigate the feasibility of a combined inductive healing asphalt (IHA) and IPT highway. The main goal will be to reduce the losses in the IHA for an efficient operation of the IPT system, while maintaining the possibility to heat the asphalt by means of induction heating when desired. Also a preliminary economical analysis to estimate the financial profit of a low maintenance road is performed. A detailed loss model for IPT systems is created that is used to describe the power transfer efficiency and predict the losses in the asphalt. Four concepts are suggested to obtain a feasible combination, which are (1) a sectioned road that separates the IPT and the IHA systems in the geometry, (2) IHA with anisotropic conductivity and permeability, (3) asphalt with dedicated heating elements and (4) asphalt with frequency dependent hysteresis losses. The loss models are verified using an experimental setup, which shows that the models created for concepts (1)-(3) provide an accurate description of the system. Based on the models and the experimental results it is concluded that the concepts (1) and (3) can provide a feasible combination of an IHA highway in combination with IPT systems. The design of such a highway would however need careful considerations with respect to the dimensioning of the systems and external sources might be needed to apply induction healing for some parts of the highway. The result of the preliminary economical analysis shows that the expected reduction in maintenance will be more than the additional implementation costs and therefore the concepts are also economically feasible.Electrical Engineering, Mathematics and Computer ScienceElectrical Sustainable Energ
Comparison of magnetic couplers for IPT-based EV charging using multi-objective optimization
No full textInductive power transfer (IPT) is becoming increasingly popular in stationary electric vehicle (EV) charging systems. In this paper, the influence of the different IPT coupler geometries on the performance factors such as efficiency, power density, misalignment tolerance, and stray field is studied. Four different coupler topologies, namely the circular, rectangular, double-D (DD-DD), and the double-D transmitter with double-D-quadrature receiver (DD-DDQ) are considered in this study. The electromagnetic behavior of the couplers is modeled using three-dimensional finite-element method, which is validated by experiments on a laboratory prototype. A multi-objective optimization (MOO) framework is developed to analyze the Pareto tradeoffs between conflicting performance metrics for the couplers. Optimization results depict that the circular topology performs best among the selected topologies regarding higher coupling coefficient, and efficiency for similar active mass and coupler area. Circular and rectangular couplers perform better than the polarized couplers like DD-DD and DD-DDQ regarding stray field exposure in both vertical and lateral direction of the coupler position in the EV. However, polarized couplers show more tolerance toward misalignment compared to circular and rectangular couplers. Thus, this study provides information regarding the specific strengths and weaknesses of different coupler topologies, which can be used during the initial design phase.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag
Wireless Power Transfer for E-mobility
No full textWireless Power Transfer (WPT) is the process of transferring power from one circuit onto another without passing through any manmade conductive elements interconnecting them. Several schemes for wireless power transfer exist – Inductive, Capacitive, Laser, Microwave etc. Of these, Inductive Power Transfer (IPT) is the most popular and is being extensively studied particularly from the last two decades. The first part of this thesis is dedicated to an extensive theoretical study of the basic compensation topologies so as to understand their operation and hence aid the design of a generic IPT system depending on the criteria to be optimized. The idea of resonance so developed can also be used to characterize any complex resonant circuit from an engineering approach. This understanding later evolved into a search for understanding the physics of magnetic fields, inductances etc. The state-of-art for IPT in E-mobility is the powering while driving scenario or dynamic charging. The second part of this thesis is dedicated to enhancing the understanding of the fundamentals of dynamic charging. This scheme is characterized by a major limitation apart from its inherent poor coupling, that being -“Misalignment”. Misalignment hampers effective power transfer as the mutual inductance would fall badly as a result of the same. To tackle the issue of misalignment, modifications can be made to both the secondary as well as the primary of the IPT. Modifications to the secondary in the form of introducing a new set of inductors referred to as “Quadrature Coils” has been studied. Also, a novel primary that could yield potentially higher power transfer, referred to as “Double Lane Model” has been proposed.Electrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc
A robust real-time gait detection method for spinal cord injury rehabilitation
No full textIn a recent first-in-human clinical study, a therapy based on targeted epidural electrical stimulation together with body weight support has been validated to restore voluntary locomotion in chronically paralyzed subjects with Spinal Cord Injury (SCI). However, the system is currently open-loop controlled, meaning that the stimulation pattern cannot be influenced by the patient. Introducing closed-loop control with real-timemotion feedback is expected to improve activity-based plasticity and thereby the therapy, to which this thesis will be contributing. To be specific, this thesis investigates the possibility of a robust real-time gait event detection method for SCI patients, to be used to synchronize the stimulation to movement in real-time. The gait of SCI patients deviates remarkably from the gait of a healthy subject. We identified several factors contributing to the deviation and studied them separately. Datasets were created by mimicking various walking scenarios observed from video references of patients from the ongoing clinical study. A robust real-time gait detection method with three variations of it – one using zero crossings of angular velocity in sagittal plane, another using high frequency contents extracted using wavelet transform and a third using additional trunk kinematics - is proposed and tested in this study with IMU signals from foot, shank and trunk. The results were promising when tested on themimicked datasets and was then tested on the limited patients available. For patient with motor incomplete paralysis (AIS-D), the method seemingly identified events correctly 9 out of 10 times both for TO and HS detection. The performance dropped noticeably for TO detection (to around an F1 score of 0.24) for motor complete patient (AIS-B) while still maintaining the HS detection performance (at around an F1 score of 0.83). We conclude that patient-group-specific strategies might be necessary and that motor complete patients may require additional motion intention recognition strategies. In addition to this, a method to emulate IMU signals from motion capture datasets when limited number of markers are used, is also presented in this study, so as to be able to convert the already existing motion capture datasets to IMU datasets, and to time-synchronize these datasets explicitly when they are collected using independent sensors. Correlation values as high as 0.977 were observed between the emulated IMU signals (sagittal plane angular velocity) and that of the actual IMU signals.Mechanical Engineerin
Magnetic Energy Transfer in Roads
No full textThis thesis deals with the modelling and application of magnetic fields in roads. The backbone technology being inductive power transfer (IPT) for electric vehicles. The magnetics for energy transfer in vehicles, can be adapted for heating steel fibres in roads, referred to as self-healing and modelling this is a second aspect of this thesis. The first sections of this thesis is dedicated to an overview of modelling techniques for coil design of IPT systems using both analytical and semi-analytical tools. A detailed literature review of techniques is followed by a comparison highlighting the strengths and weakness of techniques in terms of ease of use, computational efficiency, application to material interfaces etc. Analytical modelling of single and multi-coil configurations of IPT systems is carried out subsequently. The theory of partial inductance is used to model these geometries, to assess the impact of system parameters such as coupling, power transferred and magnetic efficiency with shapes of couplers and misalignment. Next, the problem of misalignment is highlighted by considering a distributed IPT system. The analytical modelling and experimental analysis of misalignment - lateral and longitudinal is performed. Edge effect is observed and experimentally validated. The second part of this thesis is dedicated to a multi-objective optimization based on the results of the developed analytical model. The goal being the development of a prototype IPT system for powering light EVs. The double rectangular (DR) coupler is chosen as the geometry for power transfer. Several geometry parameters - turns, ferrites (number, dimensions), gap between ferrites etc. are considered as design variables. Efficiency, area related power density and weight are considered as the optimization targets. Pareto fronts are developed and a particle is chosen for the development of a prototype. An experimental set-up is built consisting of a 85 kHz inverter, compensated charge-pads, rectifier and resistive load. The inverter is based on SiC MOSFETS and SiC Schottky anti-parallel diodes, the rectifier made from the same diodes. Phase shift control of the inverter legs is used to control power flow. An experimental analysis to validate the magnetic models is also developed. The third part of this thesis deals with system level economic analysis of IPT technology. A case study of bus fleet is considered and a generic methodology is developed to determine driving range as a function of mass and frontal area of the EV. The economic analysis is performed also identifying the trade-offs between road coverage of IPT, efficiency and battery size. Finally, the thesis culminates with a vision toward a future highway. Such a highway is expected to undergo a functional upgrade to handle electrification of transportation. This evolves around the integration of IPT systems, with low maintenance inductive healing asphalt roadways and renewable energy generation. The modelling challenges to such an integration is studied both using simulations and experiments. A case study for sizing renewable energy in a highway (A12) in the Netherlands using IPT is detailed.DC systems, Energy conversion & Storag
Future of Electric Vehicle Charging
No full textCharging infrastructure for electric vehicles (EV) will be the key factor for ensuring a smooth transition to e-mobility. This paper focuses on five technologies that will play a fundamental role in this regard: smart charging, vehicle-to-grid (V2G), charging of EVs from photovoltaic panels (PV), contactless charging and on-road charging of EVs. Smart charging of EVs is expected to enable larger penetration of EVs and renewable energy, lower the charging cost and offer better utilization of the grid infrastructure. Bidirectional EV chargers will pave the way for V2G technology where the EV can be used for energy arbitrage and demand-side management. Solar charging of EV will result in sustainable transportation and use of the EV battery as PV storage. On the other hand, stationary contactless charging and on-road inductive charging of EV will remove the necessity for any cables, eliminate range anxiety issues and pave the way for automated driving. The electromagnetic and power converter design for contactless power transfer systems for future highways is reviewed in this paper.Accepted Author ManuscriptDC systems, Energy conversion & Storag
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