52 research outputs found
Application of Pulse Calorimetry to Metal Systems
No full textThe pulse calorimeter developed as a part of the author\u27s masters thesis was used extensively in the doctoral research to determine the electrical resistivity and specific heat of Ni, Ni4Mo, Fe-A1 alloys and Ni-A1. The temperature range of measurements varied with different specimens but in general were between 375 K to 1300 K.
The pulse calorimeter essentially consists of a specimen in series with a standard resistor and a programmable power supply. The specimen is inside a vacuum chamber. The programmable power supply can be triggered from the computer to send a specific current to the specimen for a specific time. As the specimen heats, its temperature rises. Three signals - current, voltage and temperature (thermoelectric voltage) are acquired into the computer program to be processed later to determine the specific heat and electrical resistivity as functions of temperature. The specimen is allowed to cool from a high temperature and the temperature-time data are acquired as a function of time. This cooling data are used later to correct for the heat losses during heating.
A knife-edge apparatus was designed to determine the separation distance between the voltage taps on a specimen. This apparatus was also used to determine the room temperature electrical resistivity of specimens.
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Design and development of a computerized high temperature pulse calorimeter
No full textA computerized pulse heating calorimeter was designed to measure the specific heat of electrical conductors. A computer assisted data acquisition and control system was built and computer programs for acquisition and specific heat calculation were written.The calorimeter was tested from room temperature to 480°C with nickel as the specimen.
The next few paragraphs contain a brief description of the vacuum pumping system, instrument rack, power supply, data acquisition and control programs, overall manager program and preliminary data analysis.
The vacuum pumping system consisted of a mechanical pump and a diffusion pump whose outlet was connected to the vacuum chamber where the specimen was held in a vertical position by the specimen holder. The electrical connections (current leads, voltage taps and thermocouple wires) coming from the specimen holder were connected to terminals on the top platform. These terminals are connected to the instruments situated in the rack and then to a personal computer.
The instrument rack mainly consisted of (1) three separate Preston Amplifiers for amplification of the acquired signals, (2) programmable power supply, (3) a standard resistor and (4) a digital voltmeter. The amplifiers were set to accept thermoelectric voltage from the thermocouple welded to the specimen, voltage across the effective specimen length and the current signal from across a standard resistor. The amplified analog signals were fed to the analog-to-digital converter, and converted to digital signals which were then fed to the computer.
The input of the power supply was set to accept a digital to analog input signal from the computer, process it, then send the specified current to the specimen for the specified length of time.
Two main computer programs were written to conduct the specific heat experiment from the keyboard of the computer. The first program is a control and acquisition program and directs the power supply to send a one step current pulse to the specimen. The operator can specify the current for the pulse and its duration by typing their values using the keyboard or by selecting some standard runs. The acquisition part of the program loads the current, voltage and temperature signals from the specimen and arranges them in three data arrays. Calculations are performed on these data to compute the instantaneous power and the electrical resistivity of the specimen which are displayed on the screen for each data point. The data array for time, power and temperature can be stored on the hard disk to be used in another program.
The second program is the overall manager program and read the raw data created by the acquisition program from the hard disk and carries out conversions, differentiations and other calculations to get equations for the rate of change of temperature during pulsing and cooling and the equation for the power input to the specimen with time (t) and temperature (T). The calculated power and slope values are then substituted into the specific heat (Cp) equation and aCp-T curve in the desired range is obtained.
A section on preliminary data analysis has been included which shows the effect of current reversal, changing interval limits for data fitting and degree of fit on the specific heat curve. However, the main goal of the project was the design of the calorimeter rather than data analysis.
The main problems in the design of the calorimeter were due to vacuum leaks in the pumping system and disturbance in the thermocouple emf due to external electromagnetic fields
Structural characterization of spray-dried microgranules by spin-echo small-angle neutron scattering
No full textSpray-drying is a widely used industrial technique and has shown an immense potential in the fields of nanoscience and technology. This is due to its ability to synthesize microgranules consisting of correlated nanostructures using evaporation induced assembly through bottom-up approach. Although the nature of correlation among the constituent nanoparticles and their size distribution could earlier be obtained by conventional Small-angle Scattering (SAS) technique, a statistically averaged quantitative measure of the shell thickness and hollowness of the formed granules remained a challenge. In this work, we have used Spin-echo Small-angle Neutron Scattering (SESANS) technique to characterize spray-dried nanostructured microgranules having different hollowness. It is shown that this non-destructive technique provided precise quantification of the granular sizes and hollowness by utilizing polarization property of neutrons in real space directly.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.RST/Neutron and Positron Methods in Material
Comparing research trends through author-provided keywords with machine extracted terms: A ML algorithm approach using publications data on neurological disorders
No full textObjective. This study aimed to identify the primary research areas, countries, and organizational involvement in publications on neurological disorders through an analysis of human-assigned keywords. These results were then compared with unsupervised and machine-algorithm-based extracted terms from the title and abstract of the publications to gain knowledge about deficiencies of both techniques. This has enabled us to understand how far machine-derived terms through titles and abstracts can be a substitute for human-assigned keywords of scientific research articles.
Design/Methodology/Approach. While significant research areas on neurological disorders were identified from the author-provided keywords of downloaded publications of Web of Science and PubMed, these results were compared by the terms extracted from titles and abstracts through unsupervised based models like VOSviewer and machine-algorithm-based techniques like YAKE and CounterVectorizer.
Results/Discussion. We observed that the post-covid-19 era witnessed more research on various neurological disorders, but authors still chose more generic terms in the keyword list than specific ones. The unsupervised extraction tool, like VOSviewer, identified many other extraneous and insignificant terms along with significant ones. However, our self-developed machine learning algorithm using CountVectorizer and YAKE provided precise results subject to adding more stop-words in the dictionary of the stop-word list of the NLTK tool kit.
Conclusion. We observed that although author provided keywords play a vital role as they are assigned in a broader sense by the author to increase readability, these concept terms lacked specificity for in-depth analysis. We suggested that the ML algorithm being more compatible with unstructured data was a valid alternative to the author-generated keywords for more accurate results.
Originality/Value. To our knowledge, this is the first-ever study that compared the results of author-provided keywords with machine-extracted terms with real datasets, which may be an essential lead in the machine learning domain. Replicating these techniques with large datasets from different fields may be a valuable knowledge resource for experts and stakeholders
Inter-particle interaction dependent evaporation-induced assembly in contact-free micro-colloidal droplets
No full textAlternative Dispute Resolution for Sustainable Peace: A Pragmatic Proposition
No full textIn lieu of formal judicial process under the common law jurisprudence, tools and techniques of alternative dispute resolution (hereafter ADR) - as the same are so called ~ stand way ahead toward peace-building discourse in the contemporary society, as it was earlier. In forthcoming paragraphs. the author strives to articulate with arguments of his own - and corroborate (t)his position that (i) in Its given time and place - the twenty-first century South Asia - ADR, in technical sense of the term, seems a misnomer, because the same stands here in vogue as the mainstream judicious process toward peaceful settlement of disputes between and among individuals or group of individuals since time immemorial; (ii) also, with wide variety of tools and techniques of ADR, the author grapples with jurisprudence of the same to attain sustainable peace sans remnants of prejudice against one another. Besides, in perspective of hitherto ordeal of common law - procedural Law in particular - the author asserts imperative need for minute introspection toward befitting jurisprudence to suit the soil and its people in South Asia; thereby, get rid of the given piecemeal peace process the State grapples with in the course of its myopic dispute governance
Alternative Dispute Resolution for Sustainable Peace: A Pragmatic Proposition
No full textIn lieu of formal judicial process under the common law jurisprudence, tools and techniques of alternative dispute resolution (hereafter ADR) - as the same are so called ~ stand way ahead toward peace-building discourse in the contemporary society, as it was earlier. In forthcoming paragraphs. the author strives to articulate with arguments of his own - and corroborate (t)his position that (i) in Its given time and place - the twenty-first century South Asia - ADR, in technical sense of the term, seems a misnomer, because the same stands here in vogue as the mainstream judicious process toward peaceful settlement of disputes between and among individuals or group of individuals since time immemorial; (ii) also, with wide variety of tools and techniques of ADR, the author grapples with jurisprudence of the same to attain sustainable peace sans remnants of prejudice against one another. Besides, in perspective of hitherto ordeal of common law - procedural Law in particular - the author asserts imperative need for minute introspection toward befitting jurisprudence to suit the soil and its people in South Asia; thereby, get rid of the given piecemeal peace process the State grapples with in the course of its myopic dispute governance
Introduction to statistical mechanics
No full textAt the undergraduate level while studying Physics as a Major subject one has to have in-depth understanding of certain topics. One such topic is Statistical Mechanics. It analyses the behaviour of individual particles and shows the result in macroscopic parameters like pressure, volume and temperature. In spite of many books that have already been written in this field, the students of undergraduate course often find it difficult to grasp the subject in its entirety. Keeping this in mind the author has prepared this crisp volume in a lucid language illustrating many samples and relevant worked-out problems for the sake of effortless comprehension
Flameless Catalytic LPG Combustion and its Optimization Approach
No full textAbstractCatalytic combustion is a highly efficient and modern combustion technique. It incorporates noble metal catalysts to convert the fuel into the products of combustion and provide flameless heat. Flameless heat is appropriate to use in industrial hazardous areas. In this paper catalytic combustion of LPG is carried out with an intension of optimizing the combustion process considering residence time and quantity of excess air as parameters. The optimization was carried out for minimizing amount of unburned fuel. The exhaust gas was analysed using gas chromatograph. The experimentation was designed and optimized using Response Surface Methodology
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