8,017 research outputs found

    Finite Element Analysis and Statistical Method to Determine Temperature Distribution on Cutting Tool in End-Milling

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    The aim of this study is to determine the temperature distribution on cutting tool when machining HASTELLOY C-22HS with carbide coated cutting tool. Response Surface Method (RSM) used to minimize the number of experiments and to develop first order temperature model. Finite element analysis (FEA) was used to verification of the temperature distribution on cutting tool. From FEA results show clearly that the relationship between the variables (cutting speed, feed rate and axial depth) with responses (temperature). From the first order model shows that cutting speed, feed rate and axial depth plays important role in producing cutting temperature. The feed rate has the most dominant parameter on the temperature, followed by the axial depth and cutting speed. The results from FEA were compared with the experimental values. The predicted values are quite close to the experimental results, even though its accuracy is slightly inferior as Finite Element Analysis and Statistical Method to Determine Temperature Distribution on Cutting Tool in End-Milling 452 compared to RSM. However, FEA is able to produce the temperature distribution around the cutting tool, in great detail

    A Theoretical Construction of Thin Shell Wormhole from Tidal Charged Black hole

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    Recently, Dadhich et al [ Phys.Lett.B 487, 1 (2000)] have discovered a black hole solution localized on a three brane in five dimensional gravity in the Randall-Sundrum scenario. In this article, we develop a new class of thin shell wormhole by surgically grafting above two black hole spacetimes. Various aspects of this thin wormhole are also analyzed.Comment: 14 pages, 6 figures, Accepted in Gen.Rel.Gra

    Causal Bulk Viscous Dissipative Isotropic Cosmologies with Variable Gravitational and Cosmological Constants

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    We consider the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a causal bulk viscous cosmological fluid, in the presence of variable gravitational and cosmological constants. The basic equation for the Hubble parameter, generalizing the evolution equation in the case of constant gravitational coupling and cosmological term, is derived, under the supplementary assumption that the total energy of the Universe is conserved. By assuming that the cosmological constant is proportional to the square of the Hubble parameter and a power law dependence of the bulk viscosity coefficient, temperature and relaxation time on the energy density of the cosmological fluid, two classes of exact solutions of the field equations are obtained. In the first class of solutions the Universe ends in an inflationary era, while in the second class of solutions the expansion of the Universe is non-inflationary for all times. In both models the cosmological "constant" is a decreasing function of time, while the gravitational "constant" increases in the early period of evolution of the Universe, tending in the large time limit to a constant value.Comment: 14 pages, 15 figure

    A new algorithm for anisotropic solutions

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    We establish a new algorithm that generates a new solution to the Einstein field equations, with an anisotropic matter distribution, from a seed isotropic solution. The new solution is expressed in terms of integrals of an isotropic gravitational potential; and the integration can be completed exactly for particular isotropic seed metrics. A good feature of our approach is that the anisotropic solutions necessarily have an isotropic limit. We find two examples of anisotropic solutions which generalise the isothermal sphere and the Schwarzschild interior sphere. Both examples are expressed in closed form involving elementary functions only.Comment: 16 pages, to appear in Pramana - J. Phy

    Static circularly symmetric perfect fluid solutions with an exterior BTZ metric

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    In this work we study static perfect fluid stars in 2+1 dimensions with an exterior BTZ spacetime. We found the general expression for the metric coefficients as a function of the density and pressure of the fluid. We found the conditions to have regularity at the origin throughout the analysis of a set of linearly independent invariants. We also obtain an exact solution of the Einstein equations, with the corresponding equation of state p=p(ρ)p=p(\rho), which is regular at the origin.Comment: 10 pages, 1 figure, revtex 4. This paper is in honor of Alberto Garcia's sixtieth birthday. Accepted by Gen. Rel. Gra

    DAIDZEIN: A REVIEW OF PHARMACOLOGICAL EFFECTS

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    Background: Daidzein is an isoflavone with extensive nutritious value and is mainly extracted from soy plants. It is also called phytoestrogen due to its structural similarity to the human hormone estrogen. However, daidzein is distinct from estrogen due to the specificity of the estrogen receptor (ER) complex. In recent years, the pharmacological properties of daidzein have been extensively investigated and considerable progress has been made. The present review aims to evaluate the pharmacological effects and mechanisms of daidzein as reported in scientific literature. Materials and Methods: Studies were identified as reported in PubMed, Elsevier, Scholar, and Springer over the last ten years and this resulted in the identification of 112 papers. Results: Daidzein is reported to play a significant role in the prevention and treatment of a variety of diseases such as cancer, cardiovascular disease, diabetes, osteoporosis, skin disease, and neurodegenerative disease. This pharmacological activity is attributed to various metabolites including equol and trihydroxy isoflavone. Conclusion: Daidzein appears to play a significant role in the prevention of a variety of diseases and has the potential of being used in a clinical setting. However, further research is needed to understand its molecular mechanisms and safety for use in humans. Keywords: Plant, natural product, phytoestrogen, pharmacolog

    The q-harmonic oscillator and an analog of the Charlier polynomials

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    A model of a q-harmonic oscillator based on q-Charlier polynomials of Al-Salam and Carlitz is discussed. Simple explicit realization of q-creation and q-annihilation operators, q-coherent states and an analog of the Fourier transformation are found. A connection of the kernel of this transform with biorthogonal rational functions is observed

    Free radical activity of industrial fibers: role of iron in oxidative stress and activation of transcription factors.

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    We studied asbestos, vitreous fiber (MMVF10), and refractory ceramic fiber (RCF1) from the Thermal Insulation Manufacturers' Association fiber repository regarding the following: free radical damage to plasmid DNA, iron release, ability to deplete glutathione (GSH), and activate redox-sensitive transcription factors in macrophages. Asbestos had much more free radical activity than any of the man-made vitreous fibers. More Fe3+ was released than Fe2+ and more of both was released at pH 4.5 than at pH 7.2. Release of iron from the different fibers was generally not a good correlate of ability to cause free radical injury to the plasmid DNA. All fiber types caused some degree of oxidative stress, as revealed by depletion of intracellular GSH. Amosite asbestos upregulated nuclear binding of activator protein 1 transcription factor to a greater level than MMVF10 and RCF1; long-fiber amosite was the only fiber to enhance activation of the transcription factor nuclear factor kappa B (NF kappa B). The use of cysteine methyl ester and buthionine sulfoximine to modulate GSH suggested that GSH homeostasis was important in leading to activation of transcription factors. We conclude that the intrinsic free radical activity is the major determinant of transcription factor activation and therefore gene expression in alveolar macrophages. Although this was not related to iron release or ability to deplete macrophage GSH at 4 hr, GSH does play a role in activation of NF kappa B

    The Potential of Treated Palm Oil Mill Effluent (Pome) Sludge as an Organic Fertilizer

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    Palm oil mill contributed a significant benefit to agro-based industry and social-economic for Malaysia. Palm oil mill effluent (POME) is considered as a polluted wastewater and the treated POME sludge was produced from the open treatment ponds. The objective of this study was to determine the physicochemical characteristics of treated POME sludge and its potential as an organic fertilizer. It was collected from the dumping ponds in Felda Jengka 8, palm oil mill. Physicochemical characteristics, sampling and preparation of samples were analyzed according to the standard method of soil and the wastewater. The samples were collected after one and six month of age with different depths (one, two and three meters). The statistical analysis revealed that the depth was not significant on the physicochemical characteristics. The characteristics of the treated POME sludge was measures using CHNS-O, C/N ratio, solid analysis, heavy metal, macro and micronutrient, moisture content, and pH. However, the elements of oxygen, iron and pH were shown an interaction effects with time. In conclusion, the treated POME sludge has shown significant effect and the potential used as an organic fertilizer. Indeed, further studies on crops response are being conducted to prove the findings
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