Sensitivity Analysis of Calibration Methods and Factors Effecting the Statistical Nature of Radiation Measurement

The scintillator detectors are recalibrated against the datasheet given by the manufacturer. Optimal and mutual dependent values of (a) high voltage at PMT (Photomultiplier Tube), (b) amplifier gain, (c) average time to count the radiation particles (set by operator), and (d) number of instances/sample number are estimated. Total 5: two versions of Central Limit Theorem (CLT), (3) industry preferred Pulse Width Saturation, (4) calibration based on MPPC coupled Gamma-ray detector, and (5) gross method are used. It is shown that the CLT method is the most optimal method to calibrate the detector and its respective electronics couple. An inverse modeling-based Computerized Tomography method is used for verification. It is shown that statistically averaging results are more accurate and precise data than mode and median if the data is not skewed and a random number of samples are used during the calibration process. It is also shown that the average time to count the radiation particle is the most important parameter affecting the optimal calibration setting for precision and accurate measurements of gamma radiation.

     

Effect of electric field on the hydrodynamics of fluidized nanoparticles

The effect of electric field on the hydrodynamics of nanoparticles was studied in a fluidized rectangular bed, with electrodes attached to two parallel walls. It was shown that the electric field of the order of 3 times the gravity markedly decreased the bed expansion and increased the solids volume fraction of nanoparticles fluidized by air. In these experiments, a light diode assembly was utilized to infer the local solids volume fractions within a rectangular bed of 10 nm silica particles. These experimental measurements yielded a two dimensional solids volume fraction distribution within the rectangular bed. The experimental results provided some new insights into the distribution of solids within the bed. The agglomerate diameters were computed using a momentum balance with the drag given by the Ergun equation and the empirical Richardson-Zaki method. Both methods yielded agglomerate diameters of the order of 100 μm and showed dependence on the strength of the electric field. The electric field decreased the granular temperature of the nanoparticles.     

Acoustic modeling problem for automatic speech recognition system: conventional methods (Part I)

In automatic speech recognition (ASR) systems, the speech signal is captured and parameterized at front end and evaluated at back end using the statistical framework of hidden Markov model (HMM). The performance of these systems depend critically on both the type of models used and the methods adopted for signal analysis. Researchers have proposed a variety of modifications and extensions for HMM based acoustic models to overcome their limitations. In this review, we summarize most of the research work related to HMM-ASR which has been carried out during the last three decades. We present all these approaches under three categories, namely conventional methods, refinements and advancements of HMM. The review is presented in two parts (papers): (i) An overview of conventional methods for acoustic phonetic modeling, (ii) Refinements and advancements of acoustic models. Part I explores the architecture and working of the standard HMM with its limitations. It also covers different modeling units, language models and decoders. Part II presents a review on the advances and refinements of the conventional HMM techniques along with the current challenges and performance issues related to ASR.     

A unified graphical formulation for synthesis of basic and subcolumn distillation sequences

In contrast to the different approaches currently adopted for generating basic and side-split subcolumn distillation sequence for separating zeotropic multicomponent feed mixture, we present a unified graphical method applicable towards both basic and side-split subcolumn distillation sequence. For a given number of components in the feed mixture, we enforce constraints on a base graph to eliminate violations of conservation principles and to preclude distillation sequences that demand higher heat duty in all appraised practical scenarios. A compact set of algebraic constraints is transfixed using the graph counterpart for generating basic-only distillation configurations. These algebraic constraints utilize binary variables to quantify existence of submixture streams and this considerably reduces the number of variables in generating distillation sequences. We also suggest extension of the formulation to enable the exploration of thermally coupled configurations.     

Quantification of carbon nanotube dispersion and its correlation with mechanical and thermal properties of epoxy nanocomposites

An experimental study is carried out to quantitatively assess the dispersion quality of carbon nanotubes (CNTs) in epoxy matrix as a function of CNT variant and weight fraction. To this end, two weight fractions (0.05% and 0.25%) of as-grown, oxidized, and functionalized CNTs are used to process CNT/epoxy nanocomposites. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared analysis of different variants of CNTs are used to establish the efficiency of purification route. While the relative change in mechanical properties is investigated through tensile and micro-hardness testing, thermal conductivity of different nanocomposites is measured to characterize the effect of CNT addition on the average thermal properties of epoxy. Later on, a quantitative analysis is carried out to establish the relationship between the observed improvements in average composite properties with the dispersion quality of CNTs in epoxy. It is shown that carboxylic (-COOH) functionalization reduces the average CNT agglomerate size and thus ensures better dispersion of CNTs in epoxy even at higher CNT weight fraction. The improved dispersion leads to enhanced interfacial interaction at the CNT/epoxy interface and hence provides higher relative improvement in nanocomposite properties compared to the samples prepared using as-grown and oxidized CNTs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48879.     

Study of pyro-carbon coated alumina kernel using mixed contrast transfer based X-ray phase retrieval technique

We have used the contrast transfer function based X-ray phase retrieval technique for phase retrieval studies on a two-component system. Pyro-carbon coated alumina matrix was chosen as a two-component system for these studies. Simulations as well as experimental results are presented. This paper shows that X-ray phase contrast along with phase retrieval can become an alternative tool for non-destructive characterization of these materials. We have also attempted to retrieve the spatial distribution of the projected thickness map of the two different elements.     

Morphology,Ionic Conductivity,and Impedance Spectroscopy Studies of Graphene Oxide-Filled Polyvinylchloride Nanocomposites

Graphene oxide was synthesized using modified Hummers method. The preparation of polyvinylchloride/graphene oxide nanocomposites was carried out using colloidal processing. The morphology of polyvinylchloride/graphene oxide nanocomposite confirms that graphene oxide was uniformly distributed within the polyvinylchloride matrix indicating complete exfoliation of graphene oxide. Significant improvement in the microhardness of the nanocomposite was observed as compared to neat polyvinylchloride. The impedance spectroscopy of nanocomposites was carried out in the frequency range (50 Hz to 35 MHz) and temperature range (80–150°C). Thus, based on the results obtained, we found that polyvinylchloride/graphene oxide nanocomposites hold great promise in many potential applications such as an electrode material for supercapacitors.     

ASPE: attribute-based secure policy enforcement in vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) are usually operated among vehicles moving at high speeds, and thus their communication relations can be changed frequently. In such a highly dynamic environment, establishing trust among vehicles is difficult. To solve this problem, we propose a flexible, secure and decentralized attribute based secure key management framework for VANETs. Our solution is based on attribute based encryption (ABE) to construct an attribute based security policy enforcement (ASPE) framework. ASPE considers various road situations as attributes. These attributes are used as encryption keys to secure the transmitted data. ASPE is flexible in that it can dynamically change encryption keys depending on the VANET situations. At the same time, ASPE naturally incorporates data access control policies on the transmitted data. ASPE provides an integrated solution to involve data access control, key management, security policy enforcement, and secure group formation in highly dynamic vehicular communication environments. Our performance evaluations show that ASPE is efficient and it can handle large amount of data encryption/decryption flows in VANETs.     

Formal modeling and verification of software‐defined networks: A survey

Unlike traditional networking devices, control and management plane are decoupled from data plane in software‐defined networks (SDN). The logically centralized control and management plane facilitate dynamic orchestration of network resources, services, and policies by writing software programs. This provides much needed flexibility and programmability where networking rules and policies can be modified dynamically depending upon the application context. As the operation of network services entirely depends on a program, a small fault may induce several issues which can adversely affect the expected behavior of the network. Formal modeling and verification help in catching inconsistencies and existence of errors prior to the deployment of the programs that control the behavior of a network. In this paper, we provide a comprehensive survey of tools and techniques available in the literature for formal modeling and verification of SDN. These tools and techniques are classified based on their types, the components of SDN where they can be applied, and the design and development phase when they are utilized. In particular, their respective benefits and limitations are discussed in terms of ease of use, interfaces, and the ability to capture and verify intended network properties.     

Low Cost Low Power Smart Helmet for Real-Time Remote Underground Mine Environment Monitoring

Underground mining production process is vulnerable and highly dynamic in nature. Among the various causes of accidents in underground mine, major one is presence of flammable and noxious gases. Though many existing safety gadgets are there but they could not work reliably because of the typical nature of mines structure and production variability. Wireless data and communication network is also not successful because wireless communication in underground mine is significantly more challenging than through air. This work introduces the application of mobile wireless sensor network in order to monitor a variety of parameters in underground mines which have life threatening effects towards them. Each node of the network placed over the safety gear (helmet wore statutorily by every miner) comprises of various sensors depending on the requirement with microcontroller unit and other low power accessories. The proposed work has a unique feature that it will make the personnel aware about the situation of the gases present and surrounding by automatically generating different alarms and different light indicators. Other function of this device will be to transmit the data sensed by the sensors in the device to the control room wirelessly so that the responsible person would be aware of the situation. This work is focused on the design of such a prototype model for the underground mines with the aforementioned specification.