832 research outputs found

    Design Eye : a tool for design teams to analyze and address visual clutter

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    Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 43-44).User interface design is critical for the success of any information technology, from software packages to automobile dashboards. Colleagues from many different job functions often need to collaborate to produce these designs, in work environments which can often be strained. Collaborative design software can alleviate some of the problems of these teams, but current software is rarely tailored to the needs of a cross-functional group and does not actively guide users to create better designs. In this thesis, I describe DesignEye, a tool that I have developed with the Perceptual Science Group at MIT. Our tool computes the clutter of images and identifies the most salient visual elements, and allows designers to work with the softare in a tight iterative feedback loop to ensure that the most important design elements garner the most end-user attention. DesignEye is tailored to the use cases we have observed in our studies of design teams, and facilitates side-by-side comparisons of multiple design candidates as interface designers test various ideas. I conclude by demonstrating the extensibility of DesignEye, and its role not only as a tool but as a generalized platform to assist interface designers. Any vision model which quantifies some aspect of human cognitive response to a stimulus can be incorporated into DesignEye, allowing interface designers to create better and more effective user interfaces in an information technology world that is growing rapidly more complex.by Amal Kumar Dorai.M.Eng

    Mechanical Properties of Granular Materials Using Nanoindentation and Modeling with Distinct Element Method

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    The mechanics of granular material is an important issue that governs many geotechnical engineering applications. Two types of particles having similar particle size, but different shape are used in this research to evaluate the role of particle morphology on the physical properties of its assemblage. Experimentation of 1-D compression behavior at constant axial strain rate under laterally confined conditions is performed for these two particulate materials and the behavior of the stress path is analyzed in relation to the initial material packing and physical characteristics of the granules. The behavior of granular assemblages under imposed loading conditions are also evaluated by analyzing the macro and micro level morphological changes (in terms of shape and size distribution) resulting from 1-D compression tests. Various experimental procedures and techniques are employed for characterizing the size and shape aspect of these particles. The mechanical properties (hardness, modulus, and time dependent creep parameters) of the individual particles are determined and analyzed using nanoindentation technique. Nanoindentation has emerged recently as a powerful tool for precise measurements of mechanical properties of materials. Considering its potential applicability in the broad area of micromechanics associated with granular materials, an in-depth study of its application is performed. Since a rigorous study of the nanoindentation technique for finite size particles has not been done to date, initial testing for developing appropriate experimental and interpretation procedures required testing reference material such as fused quartz and novel composite materials to gain additional insight and experience. For this reason, besides granular materials, the changes in mechanical properties for structured materials (blended single wall carbon nanotube-epoxy composite specimens) are also included in this research The micromechanical analysis of granular assembly using computer simulation through the program PFC2D (2-Dimensional Particle Flow Code), an application of Distinct Element Method (DEM) is also performed. The material micro-properties such as particle shear stiffness and normal stiffness values are assigned from the nanoindentation test results for the two granular materials. The particle contact behavior, nature of force chain structure, and uniformity of deformation associated with 1-D compression on granular materials having different shape and mechanical properties are analyzed

    Slavery in the Bengal Presidency Under East India Company Rule, 1772-1843.

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    The thesis is an attempt to trace the history of slavery and its abolition in the Bengal Presidency under the East India Company's rule from 1772 to 1843. The first Chapter defines slavery and traces its history in the early and medieval periods of Indian history before the advent of the British power. It explains the reasons for its sanction as a punishment for the armed dacoits in 1772, and the various sources of slavery and the ways the slaves were procured during the Company's rule. The second chapter deals with domestic slavery in the Bengal Presidency in Hindu, Muslim and European families in the late eighteenth and the first half of the 19th century. The third Chapter is a detailed study of agrestic slavery in the Bengal Presidency and its importance as a social and economic institution in the Country. The fourth Chapter surveys the history of the seaborne slave-trade and deals with the measures taken by the Company's Government and the British Parliament to secure its gradual abolition. The fifth and sixth Chapters are devoted to two areas, Assam and Arakan, which stand rather apart, in the social and political structure from the rest of the Bengal Presidency. The seventh Chapter seeks to examine the British attitude towards slavery and the slave trade in India and gives an account of the ameliorative measures taken by the Company's Government and the British Parliament to suppress slavery and slave-trade. The roles played by the utilitarians and by such Company officials as Richardson, Metcalfe, Leycester, Harrington and Neufville to abolish slavery from India are considered and the reason for their failure. The eighth Chapter discusses the economic and social changes in Britain which led to the emergence of an anti-slavery movement strong enough to secure the institution of the Law Commission. It concludes with a study of the Law Commission's work and the abolition of slavery in 1843

    Electronic properties of graphene nano-flakes: Energy gap, permanent dipole, termination effect and Raman spectroscopy

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    The electronic properties of graphene nano-flakes (GNFs) with different edge passivation is investigated by using density functional theory. Passivation with F and H atoms are considered: CNc_{N_c} XNx_{N_x} (X=F or H). We studied GNFs with 10<Nc<5610<N_c<56 and limit ourselves to the lowest energy configurations. We found that: i) the energy difference Δ\Delta between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) decreases with NcN_c, ii) topological defects (pentagon and heptagon) break the symmetry of the GNFs and enhance the electric polarization, iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination and bilayer on the electronic properties of small GNFs.This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy.Comment: 23 pages, 14 figures, accepted in J. Chem. Phy

    Thermomechanical properties of a single hexagonal boron nitride sheet

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    Using atomistic simulations we investigate the thermodynamical properties of a single atomic layer of hexagonal boron nitride (h-BN). The thermal induced ripples, heat capacity, and thermal lattice expansion of large scale h-BN sheets are determined and compared to those found for graphene (GE) for temperatures up to 1000 K. By analyzing the mean square height fluctuations <h2>< h^2> and the height-height correlation function H(q)H(q) we found that the h-BN sheet is a less stiff material as compared to graphene. The bending rigidity of h-BN: i) is about 16% smaller than the one of GE at room temperature (300 K), and ii) increases with temperature as in GE. The difference in stiffness between h-BN and GE results in unequal responses to external uniaxial and shear stress and different buckling transitions. In contrast to a GE sheet, the buckling transition of a h-BN sheet depends strongly on the direction of the applied compression. The molar heat capacity, thermal expansion coefficient and the Gruneisen parameter are estimated to be 25.2 J\,mol−1^{-1}\,K−1^{-1}, 7.2×10−6\times10^{-6}K−1^{-1} and 0.89, respectively

    Characterization of mucoadhesive nasal gels containing midazolam hydrochloride prepared from Linum usitatissimum L. mucilage

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    Nasal drug delivery systems prepared from natural materials are gaining importance in the field of pharmaceutical technology. Mucilage isolated from Linum usitatissimum L. (LUM) seeds was reported to be an effective natural mucoadhesive agent. The present study deals with a comparison of various characteristics of nasal gels containing midazolam hydrochloride (HCl) prepared from mucoadhesive agent extracted from Linum usitatissimum L. seeds and synthetic polymers like HPMC and Carbopol 934P in terms of texture profile analysis, mucoadhesive strength, and in vivo drug absorption profiles. It was observed that gels formulated with the natural mucilage showed better results than the synthetic gels in all aspects like hardness, adhesiveness, cohesiveness and mucoadhesive strength. The absolute bioavailability of midazolam hydrochloride from the natural gel was 97.55% whereas that of synthetic gels was 57.33% and 76.81% respectively.Sistemas de liberação nasal preparados com produtos naturais estão ganhando importância no campo da tecnologia farmacêutica. A mucilagem isolada de sementes de Linum usitatissimum L. (LUM) mostrou-se agente mucoadesivo eficaz. O presente estudo trata da comparação de várias características de géis nasais contendo cloridrato de midazolam preparados com agente mucoadesivo extraído das sementes de Linum usitatissimum L. e com polímeros sintéticos, como HPMC e Carbopol 943P, com relação ao perfil de textura, força mucoadesiva e perfis de absorção do fármaco in vivo. Observou-se que os géis formulados com mucilagem natural apresentam melhores resultados do que os sintéticos em todos os aspectos, como dureza, adesão, coesão e força mucoadesiva. A biodisponibilidade absoluta do cloridrato de midazolam a partir do gel natural foi de 97,55%, enquanto que nos géis sintéticos foi de 57,33% e 76,81%, respectivamente

    EXTRACTION, PURIFICATION AND PHYSICOCHEMICAL EVALUATION OF MUCILAGE OF CHRYSOPHYLLUM LANCEOLATUM (BLUME) DC FRUITS: AN INVESTIGATION FOR BIOADHESIVE PROPERTY

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    Objective: The objective of the present investigation is to extract, purify and characterize the physicochemical properties of the mucilage obtained from the fruits of Chrysophyllum lanceolatum (Blume) DC and also to evaluate the bioadhesiveness of Chrysophyllum lanceolatum Mucilage (CLM) to be used as the biodegradable mucoadhesive agent.Methods: The mucilage was extracted, purified and identified by the methods as described in the official books. Purified CLM was characterized for physicochemical properties, swelling capacity, loss on drying and flow properties. The CLM was further characterized by Fourier Transform Infrared (FTIR) spectroscopy, Differential Scanning Calorimetry (DSC) and High-Performance Liquid Chromatography (HPLC). The mucoadhesivity of the mucilage was assessed by shear stress method and falling sphere method using goat intestine as mucosal substrate and the results were compared with Hydroxy Propyl Methyl Cellulose (HPMC) and Carbopol 934P (CP). The acute oral toxicity study was also conducted in Swiss Albino mice.Results: The nature of the CLM is confirmed as polysaccharide from the experimental data. The physicochemical property and toxicity study also shows its acceptability as bioadhesive excipient. The bioadhesive test of CLM showed a good adhesive strength to the biological membrane.Conclusion: The present investigation showed better bioadhesive property of the isolated mucilage and hence may provide an alternative to conventional synthetic/semi-synthetic mucoadhesive agents.Keywords: Chrysophyllum lanceolatum, Mucilage, Extraction, Physicochemical, Bioadhesivity, Mucosal

    Corrosion Behaviour of Metals in Artificial Tear Solution

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    Human tear comes in contact with a number of instruments during operation in the eyes.  This results in a variety of undesirable effects such as corrosion and malfunction.  Corrosion behaviour of five metals, namely, mild steel (MS), mild steel coated with zinc (MS-Zn), Ni-Cr, Ni-Ti super elastic (Ni-Ti.SE), and SS 316 L in artificial tear solution has been studied by polarization study and AC impedance spectra.  The study reveals that the decreasing order of corrosion resistance in artificial tear solution is : Ni-Ti SE &gt; Ni-Cr &gt; SS 316 L &gt; MS-Zn &gt; MS.  The first three metals are better candidates and the first one is the best candidate for making instruments used in operation in the eyes, in presence of tears
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