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Comprehensive investigations on spectral and temporal features of GX 5-1 using AstroSat observations
Comprehensive spectrotemporal analyses of the Z-type neutron star low-mass X-ray binary GX 5-1 were performed using 10 broad-band observations from AstroSat/Soft X-ray Telescope and Large Area X-ray Proportional Counter (LAXPC) instruments. The LAXPC-20 hardness-intensity diagram showed horizontal and normal branches (HBs and NBs) of the Z track which exhibited secular motion. The time-averaged spectra in the energy range 0.7-25.0 keV could be fitted with the model combination -Cconstant tbabs edge edge thcomp diskbb. This yielded ? ?2, kTe ?3.3 keV, and Fdisc/Ftotal ? 0.8 indicating the soft/intermediate spectral state of the source during the observations. Flux-resolved spectral analysis revealed a positive correlation between kTin and Fbol. However, a negative correlation was observed between them in one of the NBs. Time-averaged temporal analysis revealed multiple HB oscillations (HBOs) and NB oscillations (NBOs), and peaked noise components in the ?5-50 Hz range. Furthermore, flux-resolved temporal analysis showed that the frequency of the HBOs correlates positively whereas the strength of HBOs correlates negatively with Fbol, indicating their probable origin from the accretion disc. In contrast, the frequency and strength of NBOs remain fairly constant with Fbol, suggesting that they originate from a different region in the system. Using the relativistic precession model along with highest frequency of the HBO, the upper limits of the magnetic dipole moment (?) and field strength (B) at the poles of the neutron star in the system were found to be 25.60 1025G cm3 and 3.6408 G, respectively, for kA= 1. 2024 The Author(s). -
NuSTAR and AstroSat observations of GX 9+1: spectral and temporal studies
We have studied the spectro-temporal properties of the neutron star low-mass X-ray binary GX 9+1 using data from NuSTAR/Focal Plane Module and AstroSat/Soft X-ray Telescope and Large Area X-ray Proportional Counter (LAXPC). The hardness-intensity diagram of the source showed it to be in the soft spectral state (banana branch) during both observations. NuSTAR spectral analysis yielded an inclination angle (?) = 29 and inner disc radius (Rin) ? 19 km. Assuming that the accretion disc was truncated at the AlfvCrossed D sign ?0.9) with a monotonic increase in mass accretion rate () along the banana branch. The analysis also showed the presence of absorption edges at ?1.9 and ?2.4 keV, likely due to Si xiii and S xv, respectively. Temporal analysis with LAXPC-20 data in the 0.02-100 Hz range revealed the presence of noise components, which could be characterized by broad Lorentzian components. -
Spectro-temporal and type I X-ray burst analysis of GX 3+1 using AstroSat observations
GX 3+1, an atoll type neutron star low-mass X-ray binary, was observed four times by Soft X-ray Telescope and The Large Area X-ray Proportional Counter on-board AstroSat between 2017 October 5 and 2018 August 9. The hardness-intensity-diagram of the source showed it to be in the soft spectral state during all the four observations. The spectra of the source could be adequately fit with a model consisting of blackbody (bbody) and powerlaw (powerlaw) components. This yielded the blackbody radius and mass accretion rate to be ?8 km and ?2 10?9 M? y?1, respectively. In one of the observations, a type I X-ray burst having a rise and e-folding time of 0.6 and 5.6 s, respectively, was detected. Time-resolved spectral analysis of the burst showed that the source underwent a photospheric radius expansion. The radius of the emitting blackbody in GX 3+1 and its distance were estimated to be 9.19 +?00.8297 km and 10.17 +?00.1807 kpc, respectively. Temporal analysis of the burst yielded upper limits of the fractional root mean square amplitude of 7 per cent, 5 per cent, and 6 per cent during burst start, burst maximum, and right after the radius expansion phase, respectively. 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. -
Spectral Properties of the Soft X-Ray Transient MAXI J0637-430 Using AstroSat
Soft X-ray transients are systems that are detected when they go into an outburst, wherein their X-ray luminosity increases by several orders of magnitude. These outbursts are markers of the poorly understood change in the spectral state of these systems from the low/hard state to the high/soft state. We report the spectral properties of one such soft X-ray transient: MAXI J0637-430, with data from the SXT and LAXPC instruments on board the AstroSat mission. The source was observed for a total of ?60 ks in two observations on 2019 November 8 and 21 soon after its discovery. Flux-resolved spectral analysis of the source indicates the presence of a multicolor blackbody component arising from the accretion disk and a thermal Comptonization component. The stable low temperature (?0.55 keV) of the blackbody component points to a cool accretion disk with an inner disk radius of the order of a few hundred kilometers. In addition, we report the presence of a relativistically broadened Gaussian line at 6.4 keV. The disk-dominated flux and photon power-law index of ?2 and a constant inner disk radius indicate the source to be in the soft state. From the study we conclude that MAXI J0637-430 is a strong candidate for a black hole X-ray binary. 2022. The Author(s). Published by the American Astronomical Society. -
Constraining the physical parameters of XTE J1701-462 through NuSTAR observations
The spectral properties of the transient neutron star low-mass X-ray binary XTE J1701-462 were studied using the data obtained from FPMA/B detectors onboard NuSTAR during its second known outburst (2022 September). The physical parameters of the system were derived from the analysis of the data in the 3.0-30.0 keV energy range. The patterns displayed on the hardness-intensity diagram of the three observations closely resembled the banana branch/normal branch, a vertex of horizontal and normal branch of the Z-track and a transition from normal branch to flaring branch. Spectral analysis of the source revealed the presence of Fe K emission complex. The source spectra were fitted with a multitemperature blackbody () component in conjunction with the reflection model (). The values of temperature (kTin) and radius (Rin) of the inner accretion disc obtained from the spectral fitting with the model combination - + showed the source to be in its soft spectral state during the observations. The inclination angle (?) of the source was estimated to be between 19 and 33 and the inner disc radius (Rin) was found to be 17.4 km. Assuming the case of magnetic truncation of accretion disc, the upper limits for the magnetic dipole moment (?) and the magnetic field strength (B) at the poles of the neutron star in the system were found to be 5.78 1026 G cm3 and 8.23 108 G, respectively, for kA = 1. 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. -
Comprehensive spectro-temporal studies of GX 17+2 using AstroSat observations
We performed a comprehensive spectro-temporal study of the Z-type neutron star low-mass X-ray binary GX 17+2 using long term data from the AstroSat/Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counter (LAXPC). The hardnessintensity diagrams (HIDs) of the source revealed a positive correlation between the hardness and intensity, characteristic of soft spectral state. Additionally, the LAXPC-20 HID showed the presence of secular shifts in both hardness and intensity. Time-averaged spectral modelling in the 0.7 ? 30.0 keV energy range indicated that the spectra could be well fitted with the model combination: constant edge edge tbabs thcomp bbodyrad. This analysis yielded a blackbody radius (Rbb) of ?59 km, photon index (?) of ?2.84 and electron temperature (kTe) of ?4.84 keV. Time-averaged temporal analysis revealed normal branch oscillations (NBOs) at ? 7 Hz in Observations 1 and 3, flaring branch oscillation (FBO) at ?15 Hz in Observation 2, and horizontal branch oscillation (HBO) at ?36 Hz in Observation 5. Flux resolved spectro-temporal analysis indicated that the source remained in the soft spectral state throughout all observations. A positive correlation was observed between kTbb, Fbb and Fbol, whereas an anti-correlation was noted between kTe and Fbol. The constant frequency of NBOs with an increase in Fbol suggests that their origin lies in a region strongly influenced by the corona, as explained by the radiation-hydrodynamic model. The origin of FBOs may be attributed to the damped radiation-hydrodynamic mode of radial flow, while the origin of HBOs is supported by the beat-frequency model. 2024 Elsevier B.V. -
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Linear and Nonlinear Convection in Magnetic Fluids
The thesis deals with linear and nonlinear Rayleigh-Bard ferroconvection in a horizontal porous layer. Modified Darcy law is used to describe the fluid motion. The effect of chemical reaction, temperature newlinemodulation, gravity modulation and finite amplitudes on the onset of Darcy ferrroconvection is considered. The findings of the problems addressed in the thesis may come in handy for heat transfer application newlinesituations with ferromagnetic fluids as working medium. The summary of the problems investigated in the thesis is given below.Effect of chemical reaction on the onset of ferroconvection in a porous medium The problem of the effect of chemical reaction on the onset of Darcy newlineferrroconvection in a horizontal porous layer heated from below is investigated by means of the classical linear stability analysis. It is assumed that the fluid undergoes a zero-order exothermic chemical reaction and that there exists a local thermal equilibrium between the fluid and the solid phases. It is proved that stationary convection is preferred to the oscillatory mode. The Galerkin method is employed to determine the eigenvalues.The effect of Frank-Kamenetskii number and magnetic parameters on the stability of the system is discussed. It is newlinefound that the basic temperature profile turns out to be more and more nonlinear and asymmetric as the Frank-Kamenetskii number increases and that the effect of both chemical reaction and magnetic forces is to newlinehasten the onset of Darcy ferrroconvection. Further, it is shown that when there is very strong nonlinearity of magnetization, the fluid layer is destabilized slightly. Effect of temperature modulation on the onset of ferroconvection in a porous medium The effect of temperature modulation on the onset of Darcy ferroconvection in a horizontal porous layer heated from below is considered. The analysis is based on the assumption that the amplitude of the temperature modulation is small enough compared with the imposed newlinesteady temperature difference. -
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Involvement of Social Enterprises in Promoting Sustainable Agricultural Practices: The Case of Uravu and Buffalo Back
Social enterprises are not-for-profit or for-profit organizations that work for the development of the community in different ways and are sustainable through their products or services. One such initiative of social enterprises is supporting and promoting agriculture and agricultural products. This chapter focuses on two social enterprises, Uravu and Buffalo Back, which work with farm products and their role in promoting sustainable agriculture practices. The primary data are collected through personal interviews with top-level managers, and secondary data are collected from websites and other published documents. This study looks at the concept of sustainability in terms of finitude, fragility and fairness. These two case studies explain how social enterprises promote the development of agriculture. The former organization ensures the communitys livelihood through farming support, upgrading local knowledge, technologies, skill development and marketing their commodities. The latter focuses on promoting farmers to focus on sustainable organic farming techniques and selling their products to customers. This study can help future entrepreneurs understand different models they can use to develop the agricultural sector through their social actions. 2024 by World Scientific Publishing Co. Pte. Ltd. -
A novel automated method for coconut grading based on audioception
The quality of the coconuts used for various purposes is of utmost importance. Demand for better quality products is constantly on the rise due to the improvements in the standard of living of people. There is a possibility that a bad coconut goes unnoticed by the traders, as it is hard to decide if a coconut is good or bad by relying only on its external appearance. Traditionally, quality assessment is carried out manually with the help of three senses; sight, hearing and smell. In the proposed work, a sound processing technique is used in an attempt to automate this process which overcomes the drawbacks of manual processing, which can be used in large godowns and warehouses. This proposed method provides the quality assessment of the coconut purely based on audioception. While creating the database, coconuts varying in size, shape, color and water content were taken from several places as a source for the dataset. Features are extracted from the sound pattern produced by the dropped coconut, which forms the basis for classification. Sequential Minimal Optimization (SMO), Dagging and Naive Bayes classifiers were used and the results obtained were found to be encouraging. 2005 ongoing JATIT & LLS. -
Factors influencing career decision of undergraduate and postgraduate students: an Indian context
Purpose: The objective of the study was to explore the factors influencing the career decisions of students doing the students' undergraduate (UG) and postgraduate (PG) programmes from urban private universities/colleges in the Indian context. Design/methodology/approach: Career decision-making is determined by different factors and is contextual. The present study explores and identifies the prominent factors influencing career decision-making. A pool of 33 questions was developed, and these questions were initially administered to a sample of 233 students. Principal component analysis with Varimax Rotation identified salient factors. In the second study, confirmatory analysis was performed based on the opinion of 304 students. Findings: The study shows that the student's career deciding factors include (1) career clarity, (2) career exploration, (3) career reward and recognition and (4) career initiative for professional and personal growth. Originality/value: The study focussed on career-deciding factors for UG and PG students from urban universities/colleges in the Indian context and the findings can be used for planning career counselling interventions. 2023, Emerald Publishing Limited. -
Dynamic Offloading Technique for Latency-Sensitive Internet of Things Applications using Fog Computing
Internet of Things (IoT) has evolved as a novel paradigm that provides com-putation power to different entities connected to it. IoT offers services to multiple sectors such as home automation, industrial automation, traffic management, healthcare sector, agriculture industry etc. IoT generally relies on cloud data centers for extended analytics, processing and storage support. The cloud offers highly scalable and robust platform for IoT applications. But latency sensitive IoT applications suffer delay issues as the cloud lies in remote location. Edge/fog computing was introduced to overcome the issues faced by delay-sensitive IoT applications. These platforms lie close to the IoT network, reducing the delay and response time. The fog nodes are usually distributed in nature. The data has to be properly offloaded to available fog nodes using efficient strategies to gain benefit from the integration. Differ-ent offloading schemes are available in the literature to overcome this prob-lem This paper proposes a novel offloading approach by combining two effi-cient metaheuristic algorithms, Honey Badger Algorithm (HBA) and Fla-mingo Search Algorithm (FSA) termed as HB-FS algorithm. The HB-FS is executed in an iterative manner optimizing the objective function in each it-eration. The performance evaluation of the proposed approach is done with different existing metaheuristic algorithms and the evaluations show that the proposed work outperforms the existing algorithms in terms of latency, response time and execution time. The methodology also offers better degree of imbalance with proper load balancing under different conditions. 2023 Authors. All rights reserved. -
Edge/Fog Computing: An Overview and Insight into Research Directions
The rapid proliferation of data from applications including IoT, and on-demand access to data have increased dependency on cloud computing, which helps to minimize the overhead related to data storage and maintenance. Applications such as IoT, industrial control, etc. generate data which are highly time-critical in most scenarios. The cloud platform offers permanent storage of this massive amount of data but with comparatively less focus on time-sensitivity. Edge/fog computing are extensions of the cloud computing paradigm and require less response time for time-sensitive data. The edge/fog brings processing and storage closer to the edge of the network, thereby reducing network traffic, delay, and latency. It acts as an intermediate layer between the end devices and the cloud platform, for data collection, offloading, processing, and data management. This chapter addresses the need for fog computing, presents the design model for edge/fog computing, and discusses applications and open issues of implementation. The three-layered network model, the services provided by the edge/fog computing, and a few research challenges of implementation will also be discussed. 2024 Taylor & Francis Group, LLC. -
Metaheuristicsbased Task Offloading Framework in Fog Computing for Latency-sensitive Internet of Things Applications
The Internet of Things (IoT) applications have tremendously increased its popularity within a short span of time due to the wide range of services it offers. In the present scenario, IoT applications rely on cloud computing platforms for data storage and task offloading. Since the IoT applications are latency-sensitive, depending on a remote cloud datacenter further increases the delay and response time. Most of the IoT applications shift from cloud to fog computing for improved performance and to lower the latency. Fog enhances the Quality of service (QoS) of the connected applications by providing low latency. Different task offloading schemes in fog computing are proposed in literature to enhance the performance of IoT-fog-cloud integration. The proposed methodology focuses on constructing a metaheuristic based task offloading framework in the three-tiered IoT-fog-cloud network to enable efficient execution of latency-sensitive IoT applications. The proposed work utilizes two effective optimization algorithms such as Flamingo search algorithm (FSA) and Honey badger algorithm (HBA). Initially, the FSA algorithm is executed in an iterative manner where the objective function is optimized in every iteration. The best solutions are taken in this algorithm and fine tuning is performed using the HBA algorithm to refine the solution. The output obtained from the HBA algorithm is termed as the optimized outcome of the proposed framework. Finally, evaluations are carried out separately based on different scenarios to prove the performance efficacy of the proposed framework. The proposed framework obtains the task offloading time of 71s and also obtains less degree of imbalance and lesser latency when compared over existing techniques. 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. -
Towards Computation Offloading Approaches in IoT-Fog-Cloud Environment: Survey on Concepts, Architectures, Tools and Methodologies
The Internet of Things (IoT) provides communication and processing power to different entities connected to it, thereby redefining the way objects interact with one another. IoT has evolved as a promising platform within short duration of time due to its less complexity and wide applicability. IoT applications generally rely on cloud for extended storage, processing and analytics. Cloud computing increased the acceptance of IoT applications due to enhanced storage and processing. However, the integration does not offer support for latency-sensitive IoT applications. The latency-sensitive IoT applications had greatly benefited with the introduction of fog/edge layer to the existing IoT-Cloud architecture. The fog layer lies close to the edge of the network making the response time better and reducing the delay considerably. The three-tier architecture is still in its earlier phase and needs to be researched further. This paper addresses the offloading issues in IoT-Fog-Cloud architecture which helps to evenly distribute the incoming workload to available fog nodes. Offloading algorithms have to be carefully chosen to improve the performance of application. The different algorithms available in literature, the methodologies and simulation environments used for the implementation, the benefits of each approach and future research trends for offloading are surveyed in this paper. The survey shows that the offloading algorithms are an active research area where more explorations have to be done. 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. -
Socio-economic Development and Value Creation Through Corporate Social Responsibility: A Case Study of Bosch India Foundation
In recent years, it is mandatory for profitable organizations in India to work toward Corporate Social Responsibility (CSR). Many thinkers in the industry have appreciated the move of the Indian Government by mandating profitable businesses to take responsibility for society by sharing certain portions of the profit made by these organizations. This study focuses on various initiatives taken by BOSCH India Foundation (BIF) for socio-economic development and value creation through its CSR activities. The primary data are collected by conducting interviews with the seniorlevel managers working in the CSR department of the Bidadi plant. The data are also collected by visiting the field of action, discussing with various stakeholders and observing their initiatives. The secondary data are collected from published sources and official records of the company. This case study shows that BOSCH India Foundation is focusing on the development of the villages in Bidadi. Their CSR initiatives focus on education, agriculture and livestock development, health and hygiene, environment, women empowerment, youth development and access to potable water. This study analyzes the economic and social impacts it has created in the society. The case provides new insight for researchers and students about the CSR approaches and best practices which can be a model for companies working on CSR projects. 2024 by World Scientific Publishing Co. Pte. Ltd. -
Talent Retention Practices: Concepts and Analytical Perspectives
Employee retention is a huge challenge for many companies because of the difficulty of getting the right talent at the right place for the right job with the required potential to cope with the new changing environment. A Gartner survey revealed that 91% of HR leaders expect employee turnover in the immediate future. Even more so if employees have more job offers while joining a company, and if they find discrepancies from their expectations, they are ready to leave the job. In this scenario, it is the need for organizations to identify the beststrategies to retain talented employees. This chapter explains the concepts of talent retention, its relevance, practices, factors, and analytics contributing in retaining employees. This chapter will be helpful for organizations to devise new strategies for retaining the employees. This will also be useful for academicians and students to apply analytics in retaining employees. 2023, IGI Global. All rights reserved. -
A USB- bluetooth two factor mutual authentication security protocol for wireless sensor networks
Wireless sensor networks are easy to deploy, effective, and can monitor unattended environments. As the data transmitted through these networks is highly sensitive, the security of the networks is important and strong authentication measures must be in place. Authentication is done by means of a security protocol, wherein a user is authenticated through certain factors such as a smartcard or a password, and several mathematical calculations such as hashing, and XOR operations. Several previously proposed authentication protocols and their flaws are discussed in this paper. We propose a new two factor mutual authentication protocol using a USB-Bluetooth token as the second factor, to overcome the security flaws seen in previous schemes. We also provide security analysis as well as Scyther results in support of the proposed protocol. The proposed protocol can be used across various fields such as healthcare, agriculture, traffic monitoring etc. BEIESP.