1,269 research outputs found

    Intuitionistic Robust Fuzzy Matrix for the Diagnosis of Stress, Anxiety and Hypertension

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    The mathematical model given here attempts to improve precisionin the diagnosis of stress, anxiety, and hypertension using Intuitionisticrobust fuzzy matrix (IRFM). In practice, the imprecise natureof medical documentation and the uncertainty of patient informationfrequently do not provide the appropriate level of confidence in thediagnosis. To that purpose, a novel method based on distinct fuzzymatrices and fuzzy relations is devised, which makes use of the capabilitiesof fuzzy logic in describing, understanding, and exploitingfacts and information that are unclear and lack clarity. With the assistanceof 30 doctors, a medical knowledge base is created during theprocedure. The model obtained 95.55%t accuracy in the diagnosis,demonstrating its utility

    Electric Field Analysis of Breast Tumor Cells

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    An attractive alternative treatment for malignant tumors that are refractive to conventional therapies, such as surgery, radiation, and chemotherapy, is electrical-pulse-mediated drug delivery. Electric field distribution of tissue/tumor is important for effective treatment of tissues. This paper deals with the electric field distribution study of a tissue model using MAXWELL 3D Simulator. Our results indicate that tumor tissue had lower electric field strength compared to normal cells, which makes them susceptible to electrical-pulse-mediated drug delivery. This difference could be due to the altered properties of tumor cells compared to normal cells, and our results corroborate this

    Towards adiabatic waveforms for inspiral into Kerr black holes: I. A new model of the source for the time domain perturbation equation

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    We revisit the problem of the emission of gravitational waves from a test mass orbiting and thus perturbing a Kerr black hole. The source term of the Teukolsky perturbation equation contains a Dirac delta function which represents a point particle. We present a technique to effectively model the delta function and its derivatives using as few as four points on a numerical grid. The source term is then incorporated into a code that evolves the Teukolsky equation in the time domain as a (2+1) dimensional PDE. The waveforms and energy fluxes are extracted far from the black hole. Our comparisons with earlier work show an order of magnitude gain in performance (speed) and numerical errors less than 1% for a large fraction of parameter space. As a first application of this code, we analyze the effect of finite extraction radius on the energy fluxes. This paper is the first in a series whose goal is to develop adiabatic waveforms describing the inspiral of a small compact body into a massive Kerr black hole.Comment: 21 pages, 6 figures, accepted by PRD. This version removes the appendix; that content will be subsumed into future wor

    A Novel Design Approach for Low Speed Recovery of High Performance Fighter Aircraft

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    In this paper, a novel design approach for low-speed recovery of a high-performance fighter aircraft is presented. It is shown that the phugoid mode has an important bearing on the problem of low-speed departure. Based on the analysis of the phugoid mode trajectories, a novel low-speed protection algorithm is presented in this paper. The proposed low speed recovery is achieved in three phases. The first phase consists of detecting the incipient departure followed in the second phase by the application of suitable recovery controls and finally the third phase ends with the transfer of controls to the pilot. The design of the first and the third phase consist of choosing the correct trigger conditions which ensures safe recovery of the aircraft in all conditions. The proposed Automatic low speed recovery is triggered when the aircraft trajectory crosses a fixed boundary in the region spanned by the dynamic pressure and its rate of decrease. It is observed that this boundary is approximately a straight line, implying that it is equivalent to a forward prediction in time to indicate when the aircraft will reach the lowest controllable airspeed. This Automatic Low Speed Recovery with Forward Prediction (ALSR-FP) algorithm is found to be simpler than other existing design methods and effective in preventing low speed departure for a variety of pilot inputs that result in the aircraft losing airspeed leading to stall. In the second phase control inputs are chosen to align the velocity vector to the direction of local gravity. The recovery phase is considered complete after the aircraft reaches the dynamic pressure which is approximately 10 % higher than the minimum dynamic pressure for control. Performance of the ALSR-FP is demonstrated using the high-performance fighter aircraft ADMIRE model which has a delta wing configuration, canards and multiple redundant controls. It is also shown that the proposed algorithm can be easily implemented on board for any other fighter and civil aircraft

    Fuzzy Computing for Control of Aero Gas Turbine Engines .

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    Many methods, techniques and procedures available for designing the control system of plants and processes, are applied only after knowing accurately the plant or process to be controlled. However, in some complex situations where plants/processes cannot be accurately modelled, and especially where their control has human interaction, controller design may not be completely satisfactory. In such cases, it has been found that control decisions can be made on the basis of heuristic/linguistic measures or fuzzy algorithms. Fuzzy set principles have been used in controlling various plants/processes ranging from a laboratory steam engine to an autopilot, including an aero gas turbine engine engine for which the response of the engine speed for a fuzzy input of fuel flow has been studied. In this paper, certain stipulations and logic are suggested for the control of the total gas turbine engine. A case study of a single spool aero gas turbine engine with one of its state variables varied by heuristic logic is presented

    Phase field modelling of crack propagation in functionally graded materials

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    We present a phase field formulation for fracture in functionally graded materials (FGMs). The model builds upon homogenization theory and accounts for the spatial variation of elastic and fracture properties. Several paradigmatic case studies are addressed to demonstrate the potential of the proposed modelling framework. Specifically, we (i) gain insight into the crack growth resistance of FGMs by conducting numerical experiments over a wide range of material gradation profiles and orientations, (ii) accurately reproduce the crack trajectories observed in graded photodegradable copolymers and glass-filled epoxy FGMs, (iii) benchmark our predictions with results from alternative numerical methodologies, and (iv) model complex crack paths and failure in three dimensional functionally graded solids. The suitability of phase field fracture methods in capturing the crack deflections intrinsic to crack tip mode-mixity due to material gradients is demonstrated. Material gradient profiles that prevent unstable fracture and enhance crack growth resistance are identified: this provides the foundation for the design of fracture resistant FGMs. The finite element code developed can be downloaded from www.empaneda.com/codes

    Corrosion of Aircraft Aluminium Alloys in Acid Solutions & its Prevention by Inhibitors

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    THE corrosion of metals is a serious problem confronting the industrially advanced countries of the world. Modern developments and war-time experiences have made it possible to manufacture metals at lower costs than before. Secondly, new sources of minerals have been discovered, thereby enabling each nation to increase its capacity for the production of metals. Iron and steel, aluminium, copper and zinc are amongst the metals in common use. In practice all of them are liable to corrode in various environments : atmosphere, soil and liquid medium. The loss of metal due to corrosion necessitating repair or removal of metal parts is one of fundamental importance affecting the economy of a country. The cost of corrosion control is rather high, the estimated figures per annum for some of the countries being U.S.A.' close to 10 billion dollars, U.K.2 600 million pounds, Canada3 500 million dollars, Australia4 100 million pounds. and India5 154 crore rupees. It becomes incre-asingly important to preserve available metals in use since a time may come when some of them approach exhaus-tion. From the available figures it has been indicated that immediate attention should be given to the non- ferrous metals, and greater attention to ferrous res-ources. In the case of iron the losses due to corrosion are estimated to be about 7.6 per cent a year. Corrosion control methods, therefore, assume great importance6

    Larval rearing, spat production and juvenile growth of the blood clam Anadara granosa

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    The blood clam A d r u gmtwsa spawned in the Shdl6lsh Hatchery Laboratory, Tuf icorin on two occasions. The fertilised eggs measured 50-60~in diameter, morula larvae developed in 3 4h m and the trochophorc stage was reached in 5 hrs. The straigb t hinge stage was attained in 20-26 hrs after fertilimtion and these larvae measured 8 3I~en ah and 65.5~h eight. Advanced umbo stage was reached on day 12 (size 155.3 x 140.5~) and on day 16, majority of the larvae were in pedivcliger stage with an average size of 182.7 x 162.9~. SettIement began on day 16 and majority of the larvae were set on day 18. The growth of the spat in the hatchery is described by the exponential equation L - 0.0002739 D - where L is length in mm and D. days. On day 59, tbe spat attained an average size of 2.42 x 1.70 mm. A total of 8090 spat were produced. During tha nursery rearing in the field, the seed clam attained 20 mm average length in the following 5 months. In India, A.grund~llsecd were grodwdfor the Arst time. The significance of this study forthe mass production of the blood clam seed in the bat~herya nd its relevma to undertake blood clam culture are highlighted
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