Journal Articles

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A description of tidal propagation in Hooghly estuary using numerical and analytical solutions /
(Elsevier, 2018-09-18) Sivakholundu, K.M.
A tidal propagation characteristic of Hooghly estuary is presented using numerical (ADCIRC) and analytical models (Friedrichs and Aubrey, 1994) along with observations. The analytical model is based on Friedrichs and Aubrey (1994) that simplifies the governing hydrodynamic equations greatly by retaining only those terms that are significant without losing the overall understanding of the propagation process. The analytical model is compared with corresponding 2-D depth averaged numerical (ADCIRC) model that retains all non-linear terms. The assumptions for simplification are found to be reasonable in the light of close agreement among analytical, numerical models and observations. A plan-form geometrical characteristic as well as hydrodynamic variable of the Hooghly has been compared with that of Delaware estuary for corroborating similar tidal propagation process. The Hooghly estuary has flood dominant asymmetric tidal propagation and a positive amplitude growth factor (μ). The observed tidal celerity (phase speed) on an average is slightly more than frictionless celerity. Using the conventions of Toffolon et al. (2006), Hooghly can be classified into ‘strongly convergent – strongly dissipative’ estuary. From the results it can be construed that the estuary is yet to stabilise and reach its equilibrium morphology. It can be close to its equilibrium as very little amplification (0.1 m) is noticed in the predominant semi-diurnal constituent M2 over 78 km (barely 7%) in the estuary. The parameters of width variation (γ) and the ratio between friction and inertia (χ) have been used to define the marginal condition for amplification. The relative position of Hooghly in terms of marginal condition is consistent with similar set of estuaries elsewhere that have been grouped using the above parameters.
A fast and effective method for assessing insulation condition based on time domain spectroscopy data /
(IEEE, 2022-01-21) Mishra, D.
A novel methodology is suggested to predict the condition of Oil-paper Insulation (OPI), popularly used in power transformers. The proposed method is based on transient measurement of polarization current data from laboratory samples. Initially, complete polarization current profile is used to formulate an insulation model and then find the rise time of the system. After that, a relation is provided between rise time and measured performance parameters like moisture content(%pm). Further, another relation is suggested between rise time and the initial decay rate of recorded data. Hence, just by knowing the value of the initial decay rate, the value of crucial parameters like %pm can be evaluated using the proposed relationship.
A mathematical model of marine diesel engine speed control system
(Journal of The Institution of Engineers (India): Series C, 2018-02) Sinha, Rajendra Prasad.; Balaji, Rajoo.
Diesel engine is inherently an unstable machine and requires a reliable control system to regulate its speed for safe and efficient operation. Also, the diesel engine may operate at fixed or variable speeds depending upon user’s needs and accordingly the speed control system should have essential features to fulfil these requirements. This paper proposes a mathematical model of a marine diesel engine speed control system with droop governing function. The mathematical model includes static and dynamic characteristics of the control loop components. Model of static characteristic of the rotating fly weights speed sensing element provides an insight into the speed droop features of the speed controller. Because of big size and large time delay, the turbo charged diesel engine is represented as a first order system or sometimes even simplified to a pure integrator with constant gain which is considered acceptable in control literature. The proposed model is mathematically less complex and quick to use for preliminary analysis of the diesel engine speed controller performance.
A nonlinear regression-based approach to assess transformer insulation condition using dielectric response recorded for short duration /
(IEEE, 2023-01-01) Mishra, Deepak
Analysis of polarization current data is generally done to assess power transformer insulation condition. Due to considerable measurement time and low magnitude, noise and other environmental factors often affect the recorded dielectric response data. The influence of these factors cannot be avoided during field measurement. Once the recorded data are affected by external factors, it becomes difficult to analyze the data. Available literature has reported some techniques to reduce the testing time. However, these reported methods are ineffective in addressing the practical issues experienced during field measurement. This present article proposes a nonlinear regression-based approach to reduce insulation response measurement time significantly. Data collected from various in situ transformers have been analyzed to test the effectiveness of the proposed method.
A novel and fast approach for sensing activation energy for reliable health assessment of power transformer
(IEEE, 2022-09-13) Mishra, Deepak; Baral, Arijit; Chakravorti, Sivaji
Activation energy represents the average rate of interaction between aging by-products and cellulose. Activation energy is a crucial parameter that can be used to identify the remaining life of insulation in high voltage (HV) equipment. Existing noninvasive methods take a significantly longer time to sense activation energy for given insulation. This is primarily due to the volume of data required for such analysis, which generally takes significant time to measure. This work reports a noninvasive and effective approach to predict activation energy of oil–paper insulation using a dielectric response that is recorded for a very short span of time. The proposed method requires polarization current data sensed for a few seconds (15–20 s) to operate. The initial decay rate (DR) of the sensed data is found to be sensitive to the activation energy. This feature of the initial DR is utilized to sense the value of activation energy within a short duration. The proposed technique utilizes the current sensor (present within an electrometer) more efficiently. This facilitates the measurement of a highly accurate polarization profile and ensures reliable activation energy estimation. The proposed methodology has been successfully applied to data collected from a few real-life transformers. Reported results show that the suggested method provides satisfactory results with good accuracy.
A novel and fast approach for sensing activation energy for reliable health assessment of power transformer /
(IEEE, 2022-09-13) Mishra, Deepak
Activation energy represents the average rate of interaction between aging by-products and cellulose. Activation energy is a crucial parameter that can be used to identify the remaining life of insulation in high voltage (HV) equipment. Existing noninvasive methods take a significantly longer time to sense activation energy for given insulation. This is primarily due to the volume of data required for such analysis, which generally takes significant time to measure. This work reports a noninvasive and effective approach to predict activation energy of oil–paper insulation using a dielectric response that is recorded for a very short span of time. The proposed method requires polarization current data sensed for a few seconds (15–20 s) to operate. The initial decay rate (DR) of the sensed data is found to be sensitive to the activation energy. This feature of the initial DR is utilized to sense the value of activation energy within a short duration. The proposed technique utilizes the current sensor (present within an electrometer) more efficiently. This facilitates the measurement of a highly accurate polarization profile and ensures reliable activation energy estimation. The proposed methodology has been successfully applied to data collected from a few real-life transformers. Reported results show that the suggested method provides satisfactory results with good accuracy.
A novel approach towards gas turbine emission reduction by using neural networks /
(IEEE, 2023-11-15) Mitra, Kalyan
Optimizations of controlling parameters are the key factors to achieve effectual output and emission reduction from machinery running. This study relates prediction technology for gas turbine's (GT's) running optimization and emission reduction. The tool can identify upcoming disputes and alter the engine control setting to achieve highly efficient running operations. This research objects to get a machine learning approach to predict GT performance on emissions. The forecasting capabilities of this system are based on real-time data collected from a GT plant. A neural network is employed to analyze and predict the emissions of exhaust pollutants, primarily carbon monoxide and nitrogen oxides. The model performance is studied by considering the values of MSE, MAE, and residuals. The model's accuracy and precision are revealed by its low MSE (0.0035) and MAE (0.043). This approach is a cost-effective way to gage emissions accurately and can be used to confirm compliance with environmental regulations. It is also a helpful tool for monitoring the health of the turbine and identifying any potential issues with its operation.
A novel method to predict severity of thermal aging and degree of polymerization for reliable diagnosis of dry-type insulation
(IEEE, 2022-04) Mishra, Shalini; Baral, Arijit; Mishra, Deepak; Chakravorti, Sivaji
The effect of thermal aging on Nomex-paper-based vacuum pressure impregnation (VPI) insulation is reported in this article. The frequency-dependent dielectric loss of Nomex-paper-based VPI dry insulation is affected after significant thermal aging. This variation in dielectric loss of the insulation maintains a good correlation with the duration of thermal aging. A new parameter sensitive to the severity of thermal aging is also introduced. To identify the parameter, the excitation voltage waveform and the corresponding insulation response at a given frequency are required. Determining the parameter does not require denoising of recorded waveforms, reducing the overall computational burden. Based on the newly introduced parameter, a cost-effective method is proposed to predict the dielectric loss and degree of polymerization (DP) in a thermally aged VPI-type dry insulation. The proposed method employs the intermediate frequency range and hence does not require time-consuming low-frequency measurements.
A novel method to predict severity of thermal aging and degree of polymerization for reliable diagnosis of dry-type insulation /
(IEEE, 2022-01-01) Mishra, D.
The effect of thermal aging on Nomex-paper-based vacuum pressure impregnation (VPI) insulation is reported in this article. The frequency-dependent dielectric loss of Nomex-paper-based VPI dry insulation is affected after significant thermal aging. This variation in dielectric loss of the insulation maintains a good correlation with the duration of thermal aging. A new parameter sensitive to the severity of thermal aging is also introduced. To identify the parameter, the excitation voltage waveform and the corresponding insulation response at a given frequency are required. Determining the parameter does not require denoising of recorded waveforms, reducing the overall computational burden. Based on the newly introduced parameter, a cost-effective method is proposed to predict the dielectric loss and degree of polymerization (DP) in a thermally aged VPI-type dry insulation. The proposed method employs the intermediate frequency range and hence does not require time-consuming low-frequency measurements.
A review of developments in ballast water management
(Environmental Reviews, 2014-03) Balaji, Rajoo.; Yaakob, Omar.; Koh, Kho King.
Transportation and translocation of non-native species by ships through ballast water is one of the current issues the shipping industry is trying to address. The Ballast Water Convention is nearing full ratification after which treatment of ballast water will become mandatory for most of the trading merchant vessel categories. Ballast water management systems employing various technologies are commercially available but at high costs. Economics apart, the efficiency of these technologies and realistic ways to ensure compliance with stricter requirements of some Administrations are issues that need to be focussed upon. With the report of the Environmental Protection Agency as an assessment reference, this paper reviews the treatment technologies. Juxtaposing reports of Lloyd’s Register on the status, a concise overview of the technologies has been projected. A sustainable ballast water management based on data and assessments is proposed. The management must be extended to both shore and on-board platforms for practices, treatment, sampling, testing, and recycling. An exemplar system harvesting shipboard waste heat is projected as a route for thermal treatment in combination with technologies showing potential for optimized ballast water management
A robust identification procedure for phase field fracture mechanics parameters /
(Elsevier, 2023-07-13) Tota, Rakesh Kumar
The classical Phase Field (PF) model for fracture mechanics of brittle materials based on the finite element method involves three parameters in addition to the Poisson ratio v: the Young’s modulus E, the fracture toughness Gc, and the internal length scale Ic . The latter is mathematically conceived as a numerical regularization parameter that should tend to zero to recover linear elastic fracture mechanics (LEFM) predictions. To address this issue, a robust algorithm is implemented in MATLAB, which combines Particle Swarm Optimization (PSO) and the Phase Field (PF) approach to fracture based on the finite element method. The algorithm has been applied to a series of uni-axial tensile tests (with E and Ic to be identified) and to three-point bending tests (with E, Ic and also Gc to be identified) on specimens made of ABS material. Results show that the optimal values of E and Gc are consistent in both tests, while Ic presents a significant dependency upon the test type. Therefore, different values of the internal length scale should be identified and used to match the experimental responses under uni-axial tension or bending.
A study of ballast water treatment using engine waste heat
(Journal of The Institution of Engineers (India): Series C, 2019-04) Balaji, Rajoo.; Yaakob, Omar.; Koh, Kho King.; Adnan, Faizul Amri bin.; Ismail, Nasrudin bin.; Ahmad, Badruzzaman bin.; Ismail, Mohd Arif bin.
Heat treatment of ballast water using engine waste heat can be an advantageous option complementing any proven technology. A treatment system was envisaged based on the ballast system of an existing, operational crude carrier. It was found that the available waste heat could raise the temperatures by 25 C and voyage time requirements were found to be considerable between 7 and 12 days to heat the high volumes of ballast water. Further, a heat recovery of 14–33% of input energies from exhaust gases was recorded while using a test rig arrangement representing a shipboard arrangement. With laboratory level tests at temperature ranges of around 55–75 C, almost complete species mortalities for representative phytoplankton, zooplankton and bacteria were observed while the time for exposure varied from 15 to 60 s. Based on the heat availability analyses for harvesting heat from the engine exhaust gases(vessel and test rig), heat exchanger designs were developed and optimized using Lagrangian method applying Bell–Delaware approaches. Heat exchanger designs were developed to suit test rig engines also. Based on these designs, heat exchanger and other equipment were procured and erected. The species’ mortalities were tested in this mini-scale arrangement resembling the shipboard arrangement. The mortalities realized were[95% with heat from jacket fresh water and exhaust gases alone. The viability of the system was thus validated.
A time-efficient and innovative method to determine the dp value of power transformer insulation /
(IEEE, 2024-11-22) Mishra, Deepak; Parveen, Shabnam
The DP value is a robust and reliable parameter for estimating the state of cellulose-based insulation in power transformers. However, its practical application is limited due to the invasive nature of testing. Hence, a methodology is reported in the present work to predict DP value using Polarization Depolarization recorded for a short duration. Reported results later in this paper suggest that the initial rate of measured polarization current can be used to forecast the DP value. The suggested method was successfully tested on several specimens (having different amounts of moisture percentages) prepared in the laboratory.
Aiming to achieve zero emissions from ships
(Marine Engineers Review (India), 2019-02) Hare, Ram Hare
The world is on the brink of collapse with increase in the carbon emission and melting polar ice caps. We are almost near extinction with the average temperature rise around 7⁰C till 2100. As mankind is driving towards future, there is more importance being given to green practices with changing government policies. Maritime sector has also developed various regulations and conventions to lower the emissions and new concept of “Zero Emissions”, was derived. Recent trends in shipping show a huge inclination towards stripping-off emissions to lowest values possible. We know that the standard fuel cycles are not much efficient even with the various improvisations made over. Fuel cells have proven to be efficient power sources over the last decade with maximum efficiency up to 82% which is almost twice of the standard engine cycles. There have been sincere efforts by automobile industries with hybrid vehicles coming into the picture, now it is time for hybrid vessels too. Vessels can be run using hydrogen power plants with an effective analysis of the total outcomes of using hydrogen as a fuel in terms of profits to the owner and also to the environment. Economic viability of any change is the most important consideration in the industry, inherent with all other requirements all standards and conventions can be abided which are mainly concerned to environment with almost least equipment onboard.
AloA Optimized RLNN controller for LFC of deregulated two-area power system /
(Informatics Publishing Limited, 2021-07-20) Das, Milton Kumar
The performance of the ant lion optimization algorithm (AloA) optimized RLNN controllers are analysed in this work for LFC of two-area deregulation power system. The comparisons are performed for time domain performances of AloA optimized RLNN controllers with traditional PID controllers. The input of PID and RLNN controllers are used area control error (ACE) and controllers’ gains are adjusted through online for RLNN controllers. The performance analyses are also studied to check the controllers’ robustness with variation in parameters of the system and loads. The analysis exposes that AloA optimized RLNN controllers significantly improve the time domain performances of the considered power system compared to PID controllers.
Aluminium nanocomposites developed by additive manufacturing for use in automobile applications: advances and approaches /
(Bentham Science Publishers, 2024-05-09) Shukla, Amarish Kumar
Aluminium has a lightweight (density is 2.7 g/cm3 ), high specific strength, and excellent wear and corrosion resistance properties. Due to these properties, aluminium and its alloys are the most commonly used for structural, automobile, and aerospace applications. However, these monolithic materials have poor mechanical properties which are significant barriers to their further development. The resulting materials, when reinforced with ceramic particles, enhance the properties of materials and are capable of meeting the majority of industrial requirements. The reinforcement of ceramic affects the properties of developed composites. The composite fabricated by the conventional process has a limitation to the segregation of reinforced ceramic particles, porosity, weak interfacial bonding, and lower strength. Besides, additive manufacturing (AM) provides design freedom and dense and high-strength components. In the present study, advances in aluminium nanocomposite developed by laser powder bed fusion processes have been studied in detail. In addition, the objective of this chapter is to focus on the fabrication routes, formation mechanisms, effect of process parameters and its effect on laser absorption, grain refinement, interfacial bonding and mechanical properties of aluminium nanocomposite discussed in detail. The future scope of laser-processed aluminium composite is also briefly discussed.
An alternative, versatile, highâ€ tolerance design of a modified Richterâ€“Slevogt camera, using standard glasses /
(John Wiley & Sons, 2024-02-06) Gadey, Nishant Neeraj
Prime-focus catadioptric astrographs have been used for a long time in various astronomical applications. The prime advantage offered by them is the capability to produce remarkably wide fields of view, and hence generate a huge amount of data in relatively less observation time. An emerging application of such wide-field astrographs is in the form of telescope arrays. While this has been implemented mostly, using commercial refractive lenses, low-cost catadioptric objectives can be used as an alternative for wide-field or high-contrast array applications. Commercial catadioptric systems are generally available as modifications of Schmidt and Maksutov systems, that too, mostly in the Cassegrain configuration. Here, we present a low-cost alternative prime focus camera design of Richter–Slevogt configuration, which is in turn an extension of the Houghton correctors. The Richter–Slevogt design has the potential for a very high performance due to several degrees of freedom. The presented one is a 150 mm aperture, system, providing 3.5° (circular) diffraction-limited FOV (strehl ), using only standard glasses, N-BK7 and F2. We present the performance analysis, tolerance sensitivity, and statistical (Monte-Carlo) analysis for this design. Potential applications of the system, other than as an array are also briefly discussed.
An analysis of shipboard waste heat availability for ballast water treatment
(Journal of Marine Engineering & Technology, 2014-12) Balaji, Rajoo.; Yaakob, Omar.
Heat treatment of ballast water is one of the many treatment options being explored. This analysis has tried to assess the heat availability from the cooling water, exhaust gases of the engines and steam condensers based on design and operational data obtained from an existing crude oil carrier. Time requirements for ballasting and treatment using the seawater and condenser circulating pumps are projected. Heat balance exercises were also carried out on a testbed engine to verify attainable heat recoveries. It is seen that, although considerable heat is available, a longer time than that available during ballasting and normal ballast passages will be required for the treatment process.
An approach to investigate the characteristics of high speed turbo machines
(International Journal of Heat and Technology, 2013-12) Sarma, P. K.; Satyanarayana Murthy, Y. V. V.; Srihari, Reddipalli.; Chada, Kedarnath.; Ramnarayanan, C. P.
The article proposes a method to investigate some of the essential characteristics of high speed rotating machinery. The underlying principle of power versus speed dependence of a rotating machine is defined by a second order differential equation with dependent and independent variables respectively as power and speed. The solution of such an equation together with the dynamic relation of flow of the medium would enable further to generate the essential characteristics specific power of the compressible medium of the turbo machine under consideration.
An enhanced performance optimization of ATM networks for cross-border money transfers /
(IEEE, 2024-06-24) Srividhya, S.
This paper provides an improved approach to optimize the performance of ATM networks for move-border money transfers. The proposed technique involves an adaptive disbursed load-balancing strategy that minimizes each aid usage and verbal exchange delays. The proposed gadget makes use of aqueous-optimized neural networks in an ATM community to dynamically perform load balancing and routing responsibilities. Further, the proposed device gives a revolutionary approach to lessen transmission loss and latency by constructing a dedicated topology to mobilize the resources. To assess the effectiveness of the proposed approach, two experimental setups are used: a -level and four-stage simulated ATM community the usage of provider stage settlement (SLA) enabled routers and a real-global ATM network within the UAE. The consequences display that the proposed method outperforms the traditional tactics in terms of aid usage, communication delays, and transmission loss. The proposed method additionally gives higher scalability and fault-tolerance characteristics.