131 research outputs found
Proposals for International Support to an Intercountry Cooperative Research Programme on the Water Buffalo
No full textReport of P. Mahadevan, a consultant commissioned by TAC to prepare proposals for an international water buffalo program. Based on an analysis of the world distribution of water buffalo and their economic importance, and an assessment of current national research on buffalo nutrition, reproduction, breeding, health problems and production systems, the author identifies priority areas for research. Consideration of a number of institutional and organizational alternatives leads to the recommendation for an international network of cooperating national institutions for buffalo research. Agenda document presented at the seventeenth meeting of TAC, September 1977
Not Available
No full textNot AvailableIN a recent communication (Mahadevan 1959) attention was drawn to an interesting
association of the pearl fish Fierasfer homei (Richardson) with the wing mussel Pteria
sp., * * found in the Gulf of Mannar off Tuticorin. A re -examination of the pearl
fish showed that the position of the vent is at the base of a line just behind pectoral
origin and the origin of the dorsal is in a line above the middle of pectoral (Plate,
1, Fig. C). Further, other distinguishing characters of this fish described elsewhere
in this account justified the earlier doubts (Mahadevan op. cit.) of the likelihood
of its coming under Carapus (syn : Fierasfer) margaritiferae (Rendahl), a brief
account of which is given by de Beaufort (1951) based on specimens collected from
Pulu Punga, Pulu Missa, coast of Flores and Cape Jaubert N. W. Australia, mostly
in association with the wing mussel or sometimes with a holothurian. Smith (1955),
while reviewing the family Carapidae has mentioned the occurrence of C margaritiferae
in South African waters also where three specimens, 75 -93 mm. in length, were
' taken from inside clams at Durban.' The data on two specimens of 63.5 and 85.0
mm. examined by the present author indicate differences in some of the characteristics
as compared with the South African form described by Smith. In order to facilitate
comparison of the Indian form with others occurring elsewhere a detailed
description of the material in hand is given below.Not Availabl
The Pearl fish Carapus margaritiferae (Rendahl), a new record for the Indian waters
No full textIN a recent communication (Mahadevan 1959) attention was drawn to an interesting
association of the pearl fish Fierasfer homei (Richardson) with the wing mussel Pteria
sp.,** found in the Gulf of Mannar off Tuticorin. A re-examination of the pearl
fish showed that the position of the vent is at the base of a line just behind pectoral
origin and the origin of the dorsal is in a line above the middle of pectoral (Plate,
1, Fig. C). Further, other distinguishing characters of this fish described elsewhere
in this account justified the earlier doubts (Mahadevan op. cit.) of the likelihood
of its coming under Carapus (syn : Fierasfer) margaritiferae (Rendahl), a brief
account of which is given by de Beaufort (1951) based on specimens collected from
Pulu Punga, Pulu Missa, coast of Flores and Cape Jaubert N. W. Australia, mostly
in association with the wing mussel or sometimes with a holothurian. Smith (1955),
while reviewing the family Carapidae has mentioned the occurrence of C margaritiferae
in South African waters also where three specimens, 75-93 mm. in length, were
' taken from inside clams at Durban.' The data on two specimens of 63.5 and 85.0
mm. examined by the present author indicate differences in some of the characteristics
as compared with the South African form described by Smith. In order to facilitate
comparison of the Indian form with others occurring elsewhere a detailed
description of the material in hand is given below
Flow-driven branching in a frangible porous medium
No full text© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Derr, N. J., Fronk, D. C., Weber, C. A., Mahadevan, A., Rycroft, C. H., & Mahadevan, L. Flow-driven branching in a frangible porous medium. Physical Review Letters, 125(15), (2020): 158002, doi:10.1103/PhysRevLett.125.158002.Channel formation and branching is widely seen in physical systems where movement of fluid through a porous structure causes the spatiotemporal evolution of the medium. We provide a simple theoretical framework that embodies this feedback mechanism in a multiphase model for flow through a frangible porous medium with a dynamic permeability. Numerical simulations of the model show the emergence of branched networks whose topology is determined by the geometry of external flow forcing. This allows us to delineate the conditions under which splitting and/or coalescing branched network formation is favored, with potential implications for both understanding and controlling branching in soft frangible media.N. D. was partially supported by the NSF-Simons Center for Mathematical and Statistical Analysis of Biology at Harvard, Grant No. 1764269, and the Harvard Quantitative Biology Initiative. C. H. R. and N. D. were partially supported by the National Science Foundation under Grant No. DMS-1753203. C. H. R. was partially supported by the Applied Mathematics Program of the U.S. DOE Office of Science Advanced Scientific Computing Research under Contract No. DE-AC02-05CH11231. L. M. was partially supported by the National Science Foundation under Grants No. DMR-2011754 and No. DMR-1922321
A computational study of interfacial phenomena in dissociative water confined by nanostructured silica
No full textMolecular Dynamics (MD) Simulation techniques were used to build a dissociative model for water that accurately represents the structure, vibration spectrum and thermal expansion curves over a wide range of temperatures and pressure. The structural changes and interaction of this water model when confined by nano layers of silica were observed. Hydronium formation was observed and the structure and diffusion properties between confined water, bulk water, and water far from the silica interface were compared.
The water model was based on a pair potential and atomic water which allows for dissociation of water and its interaction with silica to form silanols. An interaction parameter representing the O-H distance (ξr-OH) was adjusted based on temperature and pressure as a strong correlation was observed between changes in the OH distance and the structure, density and energies of simulated water. The properties of water were close to the experimentally observed physical properties of water.
An atomic model for vitreous silica was also built based on the same potential and using the same parameters for oxygen-oxygen interactions in silica as that of water. The cross species interactions (Si-H and Si-O) were determined to accurately predict the structure of vitreous silica and low energy structures of interacting silicic acid -- water clusters.
Based on the above potentials, a 3nm water film was placed between layers of vitreous silica and MD simulations of the above system were carried out for seven temperatures. The structure of water far away from the interface was closer to that of bulk water and the structure of the penetrated water had features of bulk water at higher temperature and pressure. The self diffusion coefficient of the penetrated water molecules was observed to an order of magnitude lower than that of bulk water. The confined water was also observed to respond differently to changes in temperature as compared to bulk water thus changing the averaged properties of water and exhibiting variation in phase behavior.Ph.D.Includes bibliographical references
Editorial: towards a collaborative understanding of intercultural engineering
No full textThe articles in this special issue deal with the topic of cultural engineering in various contexts and from different perspectives, bringing together interculturalists, management scholars and engineering academics and professionals. Claude-Hélène Mayer emphasizes that intercultural competences are key competences in international engineering organisations. Her article is based on selected empirical findings from a multi-method research study. It focuses on cultural engineering in a specific Engineering organisation in South Africa and investigates how managers in an international and culturally diverse engineering environment define intercultural competence, how they cope with intercultural challenges in their daily work routine and how intercultural competence could be promoted within cultural engineering contexts. The contribution by Kirsten Nazarkiewicz focuses on the relevance of conversation as a learning tool to gain intercultural competence. Her paper reflects on communication as a crucial dimension of intercultural learning processes while focusing in particular on the target group of engineers. She presents three significant findings on the characteristics of communication in educational settings. The author argues that the unconscious reproduction of this pedagogical structure is not helpful for intercultural learning and shows how to use these orientations for a collective intercultural learning process that involves experts of different subcultures (technical and intercultural expert) interacting on equal terms. Finally, four approaches for trainers' conduct of talk are introduced to foster intercultural competences. Henning Hinderer highlights the cultural complexities of intercultural technical projects across organizations. He shows how the incorporation of external consultants into a technical project multiplies cultural complexity and suggests a model of how to conceptualize this condition. The author identifies processes of identity-making and othering as crucial constituting factors of intercultural engineering across organizations. He suggests strengthening the position of hybrid individuals who are between professional or organizational cultures to utilize their integrative potential as intercultural boundary-spanners. Project managers are encouraged to incorporate cultural complexity into their activities.Adding to the interpretative understanding of intercultural engineering, Jasmin Mahadevan and Christian Klinke propose analyzing failure and success stories in technical project management. Based on a long-term interpretative study, they show that project reality does not exist as such but is constantly created through stories of project success and failure. They identify three, interrelated types of stories and show when and how intercultural conflict and culturalized interpretations impact the development of intercultural competencies and neglect the complexities of project reality. To overcome these obstacles, they give recommendations to academics and practitioners from various fields.What these articles have in common, is an interpretative approach to specific intercultural settings between social reality and technology. One of their aims is to deconstruct reified national cultural containers and to facilitate a dialogue between such diverse fields as engineering, management and intercultural communication. For doing so, one article concerns the education of future intercultural engineers, another focuses upon intercultural training practice. One article highlights the construction of culture amongst technical management while two other articles conceptualize the complexities of intercultural engineering in technical projects across societal cultures and organizations.The articles presented in this Special Issue outline the field of Intercultural Engineering, this being an academic first. They bring about new thoughts and ideas to empirical research and theoretical approaches in this field and intend to stimulate further debates, research and discussion. You are now welcomed to read on and be stimulated to move the discussion forward, in a constructive, intercultural and controversial way.Die Artikel in dieser Sonderausgabe beschäftigen sich mit dem Thema Intercultural Engineering in verschiedenen Kontexten und aus verschiedenen Perspektiven und bringen so Interkulturalisten, Manager und IngenieurInnen auf praktischer und theoretischer Ebene zusammen. Claude-Hélène Mayer betont in ihrem Artikel, dass interkulturelle Kompetenzen Schlüsselkompetenzen für international technische Organisationen sind. Der Beitrag von Kirsten Nazarkiewicz konzentriert sich auf die Wichtigkeit von Gesprächen als ein Lerninstrument zum Erwerb von interkulturellen Kompetenzen.Henning Hinderer beleuchtet die kulturelle Komplexität von interkulturellen technischen Projekten jenseits organisationaler Grenzen. Jasmin Mahadevan und Christian Klinke analysieren Erfolgs- und Misserfolgsgeschichten in technischem Projektmanagement. Was diese Artikel eint, ist der interpretative Blick auf spezifische kulturelle Felder zwischen sozialer Wirklichkeit und Technologie. Ein Ziel dieser Artikel ist es, essentialisierte Vorstellungen von Nationalkultur als Container zu dekonstruieren und den Dialog zwischen so unterschiedlichen Feldern wie Ingenieurwesen, Management und Interkultureller Kommunikation zu ermöglichen. Zur Erreichung dieses Ziels beschäftigt sich ein Artikel mit der Ausbildung interkultureller IngenieurInnen, ein anderer fokussiert sich auf die interkulturelle Trainingspraxis. Ein Artikel beleuchtet die Konstruktion von Kultur im technischen Management, zwei weitere konzeptionieren die Komplexitäten von Intercultural Engineering in organisations- und gesellschaftskultur-übergreifenden Projekten. Zusammenfassend stecken die Artikel dieser Sonderausgabe das Feld Intercultural Engineering ab. Sie vermitteln neuartige Gedanken und Ideen für empirische Forschung und theoretische Herangehensweisen an dieses Feld und möchten zukünftige Debatten, Forschung und Diskussionen anregen. Daher möchten wir zum Lesen dieser Beiträge anregen, so dass die diese Diskussion auf konstruktive, interkulturelle und kontroverse Art und Weise weiterfortgeführt werden kann
Improving the collaboration in BIM teams in the design phase of BIM-enabled infrastructure projects
No full textThe Architecture, Engineering, and Construction (AEC) industry is undergoing digital transformation to improve project performance and Building Information Modelling (BIM) is helping to achieve this objective. BIM is a comprehensive digital representation of a built facility with great information depth. BIM fosters collaboration across the construction supply chain however the benefits of collaboration are realised only in a relatively small number of BIM-enabled projects. Poor collaboration continues to be one of the major risks affecting BIM-enabled projects with misunderstandings, misinterpretation of data and increased rework. This is especially high in the design phase of construction projects because of the high BIM usage. This research aims to explore the most critical barrier to collaboration in BIM teams in the design phase of infrastructure projects and provide strategies to avoid the barrier in future projects. The most critical barrier in this research is defined as “the main issue that causes the occurrence of problems resulting in undesired outcomes”. For this objective, the case-study method is preferred. Three large infrastructure projects are studied and interviews were conducted with BIM teams to identify the barriers to collaboration in BIM teams. The data collected are analysed by comparing among cases and with literature. Why questions were asked until the main issue that led to the occurrence of problems is found. From the analysis, it is found that lack of guidelines and standards is the most critical barrier to collaboration in BIM teams in the design phase of infrastructure projects. To avoid this problem in future projects, the existing BIM-based design process is improved to work with ISO19650 standards along with strategies to achieve better results. To enable better collaboration in BIM teams, the process is automated using Business Process Management (BPM) software. The proposed strategies are validated with BIM teams for applicability in practice. To conclude, the proposed strategies help in solving the lack of guidelines and standards. It improves the BIM-based design process in infrastructure projects and leads to achieving better collaboration in BIM teams. This research benefits researchers as well as BIM teams. Researchers can validate the proposed strategies in real-life projects and BIM teams can improve their work practices by implementing the proposed strategies.Civil Engineering | Construction Management and Engineerin
Optical Emission Spectroscopy during Wire and Arc Additive Manufacturing
No full textAdditive Manufacturing (AM) has been identified to be a key technology in the ‘third industrial revolution’ - a new wave of manufacturing technologies characterised by functional software, flexible robots, and a range of digitized services that addressed the limitations of traditional casting and milling based subtractive manufacturing processes. Wire and Arc Additive Manufacturing (WAAM) is one such AM technique that is used to produce metal components that are near net shape. Mechanical testing, failure analysis and microstructure investigation of the finished component is done only after it is fully built. Building defective parts increases the material usage, power consumption, build time, and overall cost of production. Thus, real time detection of process and product anomalies not only saves money and material but can also improve the mechanical properties of the printed component. One such monitoring technique is Optical Emission Spectroscopy (OES), where the electromagnetic radiation emitted by the plasma arc in the printing process is used to characterize the processing conditions of the WAAM environment. Although OES has been used for quality control in arc welding as well as powder-based AM processes, there has not been any previous study directly focused on the use of OES to study the WAAM process. Monitoring systems require a robust setup that can collect reliable and repeatable data, if it is to be used for quality control. Although OES is a feasible method to study arc radiation, there is currently no application of this technique in a reliable monitoring system for commercial application. The goal of this study was to develop an OES based monitoring system for the WAAM process. The monitoring system consisted of an experimental setup designed to collect reliable optical emission data from the plasma arc using an optic fibre attachment to the WAAM robot and a software system was designed to perform data analysis and post-processing of the collected optical spectrum. The developed monitoring system was validated by performing a series of experiments with different processing conditions (welding current, voltage, speed and surface conditions) to investigate the potential correlations among them with the detected optical spectrum. A peak characterization test was designed with different material combinations to test the reliability of the emission peak matching algorithm that was developed. It was followed by a ramping test where the heat input was incrementally increased to study the correlation with the processed OES signals. The final experiment was an anomaly detection test where the OES data was used to characterize the presence of an artificially deposited ceramic anomaly on the base plate that simulated the presence of an impurity. Secondary investigation techniques like optical microscopy, a high-frequency V-I sensor and a high-speed camera footage was used to validate the OES observations. The results of these experiments showed the feasibility of OES based monitoring systems for WAAM. However, the obtained results were not always consistent and the system requires further research before it can be used for reliable quality control of the WAAM process
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