1,581 research outputs found

    Comparative diversity and composition of nitrogen-fixing cyanobacteria in three different land use systems of upper Assam

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    Three contrasting land use systems: reserve forests, rice fields and coal fields located at Upper Assam region of North East India were explored for documenting diversity and species composition of N2-fixing cyanobacteria. Altogether 24 taxa (16 heterocystous and 8 non-heterocystous) belonging to nine different genera were isolated. The Shannon’s diversity index was highest in rice fields (1.946), followed by reserve forest (1.485) and coal fields (0.975). Results of relative abundance revealed the dominance of Nostoc and Anabaena in the reserve forests and rice fields, whereas both were missing in the coal contaminated sites. Oscillatoria was the dominant genus and the species belonging to this genus were abundant in coal field areas. Canonical Correspondence Analysis revealed that environmental factors and physico-chemical properties cumulatively decided the composition and distribution of cyanobacteria in different land use systems of the region.Key Words: Diversity, Cyanobacteria, Land use, Reserve forest, Rice fields, Coal fields

    Design and Fabrication of a Gear Box Motor Current Analysis System

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    To achieve reliable and cost effective diagnosis, Motor current signature analysis is used to investigate the use of an induction motor as a transducer to indicate the faults in multistage gearbox via analyzing supply parameters such as phase current and instantaneous power. In gearboxes, load fluctuations on the gearbox and gear defects are two major sources of vibration. Further at times, measurement of vibration in the gearbox is not easy because of the inaccessibility in mounting the vibration transducers. This analysis system can be used for measuring the characteristics for a perfectly working gearbox and use the data as a standard for measuring faults and defects in other gearboxes. The objective of this paper is to design and fabricate a gearbox motor current analysis system at different gear operations for a constant load. Steady load conditions on the gearbox are tested for current signatures during different gear operations. The motor current analysis system can be used further to specify mainly faults in the gear, misalignment of meshed gears, and loss of contact of the gears

    Photo-excitation of a light-harvesting supra-molecular triad: a Time-Dependent DFT study

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    We present the first time-dependent density-functional theory (TDDFT) calculation on a light harvesting triad carotenoid-diaryl-porphyrin-C60. Besides the numerical challenge that the ab initio study of the electronic structure of such a large system presents, we show that TDDFT is able to provide an accurate description of the excited state properties of the system. In particular we calculate the photo-absorption spectrum of the supra-molecular assembly, and we provide an interpretation of the photo-excitation mechanism in terms of the properties of the component moieties. The spectrum is in good agreement with experimental data, and provides useful insight on the photo-induced charge transfer mechanism which characterizes the system.Comment: Accepted for publication on JPC, March 09th 200

    A Technical Review of Lawn Mower Technology

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    This paper summarizes and reviews different technological developments for making efficient and cost effective lawn mowers. Such lawn mower may be powered by solar energy, conventional electric and internal combustion engine. For each type of energy source mentioned above, we discuss the mechanisms followed for lawn mower device, the design of the model and results obtained in various literatures. Sometimes two such energy sources may be used in combination, like solar powered robotic lawn mower.Keywords: lawn mower, solar energy, sensor, motor, battery, exhaus

    Effect of time series length and resolution on abundance‐ and trait‐based early warning signals of population declines

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    Seasonal environmental conditions shape the behavior and life history of virtually all organisms. Climate change is modifying these seasonal environmental conditions, which threatens to disrupt population dynamics. It is conceivable that climatic changes may be beneficial in one season but result in detrimental conditions in another because life-history strategies vary between these time periods. We analyzed the temporal trends in seasonal survival of yellow-bellied marmots (Marmota flaviventer) and explored the environmental drivers using a 40-y dataset from the Colorado Rocky Mountains (USA). Trends in survival revealed divergent seasonal patterns, which were similar across age-classes. Marmot survival declined during winter but generally increased during summer. Interestingly, different environmental factors appeared to drive survival trends across age-classes. Winter survival was largely driven by conditions during the preceding summer and the effect of continued climate change was likely to be mainly negative, whereas the likely outcome of continued climate change on summer survival was generally positive. This study illustrates that seasonal demographic responses need disentangling to accurately forecast the impacts of climate change on animal population dynamics

    PAN AIR: A computer program for predicting subsonic or supersonic linear potential flows about arbitrary configurations using a higher order panel method. Volume 4: Maintenance document (version 3.0)

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    The Maintenance Document Version 3.0 is a guide to the PAN AIR software system, a system which computes the subsonic or supersonic linear potential flow about a body of nearly arbitrary shape, using a higher order panel method. The document describes the overall system and each program module of the system. Sufficient detail is given for program maintenance, updating, and modification. It is assumed that the reader is familiar with programming and CRAY computer systems. The PAN AIR system was written in FORTRAN 4 language except for a few CAL language subroutines which exist in the PAN AIR library. Structured programming techniques were used to provide code documentation and maintainability. The operating systems accommodated are COS 1.11, COS 1.12, COS 1.13, and COS 1.14 on the CRAY 1S, 1M, and X-MP computing systems. The system is comprised of a data base management system, a program library, an execution control module, and nine separate FORTRAN technical modules. Each module calculates part of the posed PAN AIR problem. The data base manager is used to communicate between modules and within modules. The technical modules must be run in a prescribed fashion for each PAN AIR problem. In order to ease the problem of supplying the many JCL cards required to execute the modules, a set of CRAY procedures (PAPROCS) was created to automatically supply most of the JCL cards. Most of this document has not changed for Version 3.0. It now, however, strictly applies only to PAN AIR version 3.0. The major changes are: (1) additional sections covering the new FDP module (which calculates streamlines and offbody points); (2) a complete rewrite of the section on the MAG module; and (3) strict applicability to CRAY computing systems

    Analyzing the perception, judgment and understanding of Ethics among Engineering students in Higher Education

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    The Royal Academy of Engineering, which is Britain’s national academy for engineering, identifies and stresses the importance of personal and professional commitments and obligations of professional engineers to enhance the wellbeing of the society. These can be attained by adopting the highest standards of professional conduct and integrity which are now commonly represented as ‘Engineering Ethics’. The engineering profession requires the exploitation of knowledge, resources and innovation and in the process; engineers face different complex situations and scenarios that regularly test their ethical judgment and understanding. A lot of emphasis is therefore placed today on familiarizing engineers with the ethical standards and moral codes of conduct involved in an organization as part of their commitment towards their roles. However, there is very little research conducted so far on the influence of Ethics Education on the moral growth of engineering students. Some recent studies suggest a growing concern among universities on the issue of increasing the ethical knowledge among their students and produce ethically responsible engineers or business leaders. Can Engineering Ethics Education reinforce students’ inclination to act ethically and give a strong foundation to their ethical decision making skills? Some researchers seem to imply that students who attend an ethics based course or module are more likely to recognize the core of a moral issue in a given complex situation than students who haven’t had any such prior experience. Other researchers seem to disagree on that context. There is also a degree of uncertainty and inconsistency as to how Ethics related courses can be incorporated and delivered as part of an Engineering curriculum. It is also not clear at what stage should engineering students be exposed to ethics courses? This study aims to bring clarity in some of these areas by examining the perception and decision making skills among two groups of students: one which has attended a course on ethics and the other which hasn’t. It uses the example of the MSc Engineering Management Programme at York where a session on Engineering Ethics is delivered every year. This study will analyze the potential of Ethics Education in boosting a student’s ethical responsibility, awareness and decision making skills

    Construction of the membership surface of imprecise vector

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    The Safe and Effective Use of Low-Assurance Predictions in Safety-Critical Systems

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    The algorithm-design paradigm of algorithms using predictions is explored as a means of incorporating the computations of lower-assurance components (such as machine-learning based ones) into safety-critical systems that must have their correctness validated to very high levels of assurance. The paradigm is applied to two simple example applications that are relevant to the real-time systems community: energy-aware scheduling, and classification using ML-based classifiers in conjunction with more reliable but slower deterministic classifiers. It is shown how algorithms using predictions achieve much-improved performance when the low-assurance computations are correct, at a cost of no more than a slight performance degradation even when they turn out to be completely wrong
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