The problem of designing robust controller for discrete two-time-scale interval systems, conveniently represented using interval matrix notion, is considered. The original full order two-time-scale interval system is ...
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Carbon dioxide is a major greenhouse gas (GHG) responsible for climate change. The energy sector accounts for approximately 75 % of the total carbon dioxide emissions in the world. The main options for reducing carbon...
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Carbon dioxide is a major greenhouse gas (GHG) responsible for climate change. The energy sector accounts for approximately 75 % of the total carbon dioxide emissions in the world. The main options for reducing carbon dioxide emissions in energy systems are energy efficiency, and utilization of renewable energy and nuclear energy. In the present global energy scenario, the share of modern renewables in the total primary energy use is marginal (about 4.5 %). This paper assesses the sustainability of renewables for the world using the criteria of life-cycle cost, net energy ratio, resource constraint and greenhouse gas emissions. Renewable options for electricity generation and hydrogen generation for vehicles are assessed on the basis of these criteria. Life-cycle assessment (LCA) is carried out using SimaPro 6 LCA software. For electricity generation the base case considered is thermal power generation using coal. The options considered are wind energy, solar photovoltaics and biomass gasification. For hydrogen production three methods based on renewables (photovoltaic (PV)-electrolysis, wind energy conversion systems (WECS)-electrolysis and biomass gasification) are compared with the steam methane reforming (SMR) method. The renewable-based technologies seem to be sustainable on the basis of all criteria except the high life-cycle cost. In some cases, e.g., in biomass-based systems, land availability may constrain sustainability. Biomass is likely to be a sustainable solution only if marginal/scrub lands can be used for biomass plantation with adequate yield. However, this option needs to be studied to see if the net energy ratio is greater than one. It is found that hydrogen production by photovoltaic-electrolyzer can be a non-renewable method at low load factor (~0.15) and PV module efficiency (10 %). However, this method is renewable for higher values of load factor and PV module efficiency. The framework developed in this paper can form the starting-point for s
Flux drooping occurs at the sector transition in direct torque controlled drives especially at low speed and high load operating conditions. A comprehensive analysis of this phenomenon and the schemes reported in the ...
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Though continuous-time sliding mode control has a variety of desirable properties, its discrete-time counterpart does not guarantee the same performance. This is due to the fact that most of the discrete-time sliding ...
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This paper compares four alternative vehicle technologies for a typical small family car in India (Maruti 800) - two conventional i) Petrol driven internal combustion (IC) engine, ii) Compressed natural gas (CNG) driv...
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ISBN:
(纸本)9781622765409
This paper compares four alternative vehicle technologies for a typical small family car in India (Maruti 800) - two conventional i) Petrol driven internal combustion (IC) engine, ii) Compressed natural gas (CNG) driven IC engine and two based on proton exchange membrane (PEM) fuel cells with different storage iii) Compressed hydrogen storage and iv) Metal hydride (FeTi) storage. Each technology option is simulated in MATLAB using a backward facing algorithm to calculate the force and power requirement for the indian urban drive cycle. The storage for the CNG and the fuel cell vehicles is designed to have driving range of 50% of the existing petrol vehicle. The simulation considers the part load efficiency vs. load characteristics for the computed ratings of the IC engine and the fuel cell. The analysis includes the transmission efficiency, motor efficiency and storage efficiencies. The comparison criteria used are the primary energy consumption (MJ/km), the cost (Rs./km) obtained by computing the annualized life cycle cost and dividing this by the annual vehicle travel and carbon dioxide emissions (g/km). For the primary energy analysis the energy required for extraction, processing of the fuel is also included. For the fuel cell vehicles, it is assumed that hydrogen is produced from natural gas through steam methane reforming. It is found that the fuel cell vehicles have the lowest primary energy consumption (1.3 MJ/km) as compared to the petrol and CNG vehicles (2.3 and 2.5 MJ/km respectively). The cost analysis is done based on existing prices in India and reveals that the CNG vehicle has the lowest cost (2.3 Rs./km) as compared to petrol (4.5 Rs./km). The fuel cell vehicles have a higher cost of 26 Rs./km mainly due to the higher fuel cell system cost (93% of the total cost). The CO2 emissions are lowest for the fuel cell vehicle with compressed hydrogen storage (98 g/km) as compared to the petrol vehicle (162 g/km). If the incremental annual cost of the fuel c
In this paper, an improvement in Pade approximation is proposed to reduce the order of a linear-time-invariant higher order stable system, using the Hermite-Biehler stability theorem. Two free parameters are introduce...
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In this paper, an improvement in Pade approximation is proposed to reduce the order of a linear-time-invariant higher order stable system, using the Hermite-Biehler stability theorem. Two free parameters are introduced in the denominator polynomial of the reduced model. It will be shown that for any positive values of these two parameters, the resulting reduced model will be stable. The numerator polynomial and these two parameters are obtained by matching time moments. In this proposed algorithm, the reduced model matches (r + 2) time moments exactly while (r + 3)-th moment is matched approximately. The proposed method is illustrated by two numerical examples.
The paper presents a novel method to design a spatial control for a large PHWR based on multirate output feedback robust sliding mode control. The proposed method does not require state information of the system, for ...
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ISBN:
(纸本)1424407265
The paper presents a novel method to design a spatial control for a large PHWR based on multirate output feedback robust sliding mode control. The proposed method does not require state information of the system, for feedback purposes. The proposed control technique is easy to obtain and to implement. Simulation has been carried out using the nodal core model of PHWR to show the effectiveness of the proposed method.
Nuclear reactors of small and medium size are generally described by point kinetics model, however, this model is not valid in case of a large reactor, because in that flux shape under-goes appreciable variation with ...
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Nuclear reactors of small and medium size are generally described by point kinetics model, however, this model is not valid in case of a large reactor, because in that flux shape under-goes appreciable variation with time. The behaviour of large reactor core can be explained with reasonable accuracy by spatial model like nodal model, which considers the reactor to be divided into number of regions or nodes. The thermal feedbacks which introduce nonlinearity into the problem, should be considered for realistic modeling. The spatial model of 540-MWe PHWR developed in [4] is augmented with the dynamics of coolant and fuel temperatures and a 72nd-order model is obtained. As working with such a large model is difficult from the point of view of numerical computations, the new model having 14 inputs and 14 outputs, is suitably reduced by aggregation technique to obtain a 26th-order reduced model, which is more suitable to handle. The design of spatial controller by a state feedback based on reduced model needs the availability of all the states of the system for feedback purpose. As all the states of the reactor are not accessible for measurement, one has to resort to output feedback. Also, as the stability is not guaranteed by static output feedback, here the spatial controller is designed by periodic output feedback which is static in nature and at the same time guarantees complete closed-loop pole assignability. The various zones in a large reactor are coupled and a change in the control input to any zone causes respective change in the neutron flux of the other neighbouring zones, which may not be desirable. Therefore, a decentralized controller would serve as a better option, as it ensures that the input to any zone affects corresponding zone only and other zones are not affected by it. The above idea of periodic output feedback controller design yields a gain matrix with large magnitude, which amplifies measurement noise and is difficult to implement practically. He
This paper presents an approach based on the use of the correspondence analysis (CA) algorithm for the task of fault detection and diagnosis. The CA algorithm analyzes the joint row-column association to represent the...
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This paper presents an approach based on the use of the correspondence analysis (CA) algorithm for the task of fault detection and diagnosis. The CA algorithm analyzes the joint row-column association to represent the information content in the data matrix X. Decomposition of the information represented by this metric is shown to capture dynamic information more efficiently [1] and therefore yield superior performance from the viewpoints of data compression, discrimination and classification as well as early detection of faults. In this paper, we are discussing certain implementation issues, such as dimensional homogeneity, before correspondence analysis can be applied to any data set. We also demonstrate how these conditions can be met for the data sets obtained from an online plant. We demonstrate performance improvements over PCA and DPCA on the Tennessee Eastman problem, which is a representative benchmark problem used in the literature. CA is shown to yield vastly superior performance for the monitoring of the TE problem, when compared with PCA and DPCA.
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