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Radial hydraulic machinery four-quadrant performance curves dependent on specific speed and applied in transient calculations

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IOP Conference Series. Earth and Environmental Science 2019年第4期240卷

作者： Giljen, Z Nedeljkovic, M PhD student Senior engineer for mechanical works Business and Technical Development Directorate Sector for new projects Montenegro Electric Company Vuka Karadžića 2 Nikšić Montenegro Professor University of Belgrade Faculty of Mechanical Engineering Department for Hydraulic Machinery and Energy Systems Kraljice Marije 16 Belgrade Serbia

The paper presents research analysis of possible analytical relationships that could exist in pointwise data for four-quadrant performance curves of one radial pump and seven pump-turbines for which the authors collected the basic data and performed the calculation. All the performance curves are for different specific speeds. Additionally, the examples of transformation calculation from the four-quadrant curves into Suter form curves shown in [1] -Thorley (1996) and [2] - Stepanoff (1959) have been presented. A numerical model has been developed for the calculation of transient processes in hydropower plants with installed pumps and pump-turbines. As an input data, the analytical relationships found in the previous research analysis have been used, as well as the pointwise curves for various specific speeds. The multi comparison of the results has been made and comprehensive conclusions given.

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Disagreement in middle ear volume estimation between tympanometry and three-dimensional volume reconstruction in the context of tympanic membrane perforation

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Journal of Otology 2017年第2期12卷 74-79页

作者： David J.Carpenter Debara L.Tucci David M.Kaylie Dennis O.Frank-Ito Division of Head and Neck Surgery&Communication Sciences Department of SurgeryDuke University Medical CenterDurhamNCUSA Computational Biology&Bioinformatics PhD Program Duke UniversityDurhamNCUSA Department of Mechanical Engineering and Materials Science Duke UniversityDurhamNCUSA

Introduction: Middle ear volume(MEV) is a clinically relevant parameter across middle ear diseases. MEV values between these techniques have never before been tested for agreement in ears with perforated tympanic membranes(TMs).Methods: Middle ears were identified from 36 patients ranging 18-89 years of age with TM perforations who underwent tympanometry and temporal bone computed tomography(CT) between 2005 and 2015. MEVs calculated by both tympanometry and three-dimensional volume reconstruction(3DVR) were analyzed for agreement using Bland Altman plots. The differences between tympanometric and 3DVR MEV values for each given middle ear were characterized across MEV quartiles(1= smallest; 4= largest) and across increasing states of middle ear disease using Kruskale Wallis and Wilcoxon testing with Bonferroni ***: Bland Altman plots demonstrated significant disagreement between MEV measurement techniques. Differences between tympanometric(T) and 3DVR MEV values were significantly greater with increasing average(i.e.(Tt3DVR)/2)) MEV per linear regression(p < 0.0001). Significance was demonstrated between fourth and first average MEV quartiles(p= 0.0024), fourth and second quartiles(p= 0.0024), third and first quartiles(p= 0.0048), and third and second quartiles(p= 0.048). Absolute MEV difference was not significantly different across varying states of middle ear disease(p= 0.44).Conclusion: Statistically and clinically significant disagreement was demonstrated between tympanometric and 3DVR MEV values. Studies that vary in MEV estimation techniques may be expected to demonstrate significantly different results. These preliminary results suggest that clinicians should endeavor to seek further confirmation when interpreting high tympanometric MEV values.

关键词： Middle ear volume Tympanometry Three-dimensional volume reconstruction Tympanic membrane perforation

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Behaviour of tunnel lining material in road tunnel fire

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IOP Conference Series: Materials Science and engineering 2018年第1期346卷

作者： M Tomar S Khurana R Singh PhD Scholar Department of Mechanical Engineering BITS Pilani – Dubai Campus UAE Assistant professor Department of Mechanical Engineering BITS Pilani – Dubai Campus UAE Senior Mechanical Engineer Systra – Delhi India

The worldwide road tunnel linings are protected against possible fire scenarios to safeguard the structure and assist in occupant evacuation. There are various choices of active and passive protection available, passive protections includes calcium silicate boards, polypropylene fibers, vermiculite cement based sprays, and other intumescent materials. Tunnel fire is a complex phenomenon and researchers in the past has highlighted that there are various factors which affect the tunnel fires. The effect of passive protection techniques on tunnel fire is not well understood, especially for the insulation boards. It's been understood from past research that for a heavy good vehicular (HGV) fire in the tunnel, the heat feedback effect is significant. Insulation boards may also affect the tunnel fires by altering the heat feedback effect in vehicular tunnels and hence this can affect the overall heat release rates and temperature profile inside a tunnel. This study focuses on studying the role of insulation boards in tunnel fires and evaluating its effect on overall heat release rate and tunnel temperatures.

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Investigation of mechanical properties of hemp/glass fiber reinforced nano clay hybrid composites

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AIP Conference Proceedings 2018年第1期1943卷

作者： Hanamantappa Ningappa Unki H. K. Shivanand H. N. Vidyasagar 1PhD Research Scholar Department of Mechanical Engineering UVCE Bangalore India 2Associate Professor Department of Mechanical Engineering UVCE Bangalore India 3Associate Professor Department of Mechanical Engineering UVCE Bangalore India

Over the last twenty to thirty years composite materials have been used in engineering field. Composite materials possess high strength, high strength to weight ratio due to these facts composite materials are becoming popular among researchers and scientists. The major proportion of engineering materials consists of composite materials. Composite materials are used in vast applications ranging from day-to-day household articles to highly sophisticated applications. In this paper an attempt is made to prepare three different composite materials using e-glass and Hemp. In this present investigation hybrid composite of Hemp, Glass fiber and Nano clay will be prepared by Hand-layup technique. The glass fiber used in this present investigation is E-glass fiber bi-directional: 90˚ orientation. The composite samples will be made in the form of a Laminates. The wt% of nanoclay added in the preparation of sample is 20 gm constant. The fabricated composite Laminate will be cut into corresponding profiles as per ASTM standards for mechanical Testing. The effect of addition of Nano clay and variation of Hemp/glass fibers will be studied. In the present work, a new Hybrid composite is developed in which Hemp, E glass fibers is reinforced with epoxy resin and with Nano clay.

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Etching characteristics of aluminium while machining square cavity using photochemical machining

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AIP Conference Proceedings 2018年第1期1998卷

作者： Ekta Tripathi Tapas Debnath P. K. Patowari 1M.Tech Scholar Department of Mechanical Engineering NIT Silchar India 2PhD Scholar Department of Mechanical Engineering NIT Silchar India 3Associate Professor Department of Mechanical Engineering NIT Silchar India

Photochemical machining (PCM) is one of the well-known non-traditional machining processes that offer the challenges of today’s manufacturing world. In this demanding world, PCM is useful for quick machining on any kind of material using suitable etchant. This work focuses on determining the etching characteristics of aluminium alloy (Al 6061) by PCM process using ferric chloride (FeCl3) as an etchant. Taguchi L9 orthogonal array is used to study the effect of process parameters like temperature, etching time and surface area to observe the effects on performance measures such as surface roughness and etching depth. An overall evaluation criterion (OEC) is formulated to optimize the etching characteristics which will yield in lower surface roughness and higher etching depth.

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Front Cover: Bioderived Molecular Electrodes for Next-Generation Energy-Storage Materials (ChemSusChem 9/2020)

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ChemSusChem 2020年第9期13卷 2101-2101页

作者： Mikhail Miroshnikov Kiran Mahankali Dr. Naresh Kumar Thangavel Dr. Sitakanta Satapathy Dr. Leela Mohana Reddy Arava Dr. Pulickel M. Ajayan Dr. George John Department of Chemistry and Biochemistry Center for Discovery and Innovation The City College of New York 85 St. Nicholas Terrace New York NY 10031 USA The PhD Program in Chemistry The Graduate Center of the City University of New York 365 5th Ave New York NY 10016 USA Department of Mechanical Engineering Wayne State University 5050 Anthony Wayne Dr. Detroit MI 48202 USA Department of Materials Science and NanoEngineering Rice University 6100 Main Street Houston TX 77005 USA

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Annual performance optimization of a linear Fresnel collector in Pretoria, South Africa

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AIP Conference Proceedings 2018年第1期2033卷

作者： Mohammad Moghimi Ardekani Ken Craig Josua Meyer 1PhD Lecturer Department of Mechanical and Aeronautical Engineering University of Pretoria Pretoria 0002 South Africa 2PrEng PhD Professor Department of Mechanical and Aeronautical Engineering University of Pretoria Pretoria 0002 South Africa 3PrEng PhD Professor Department of Mechanical and Aeronautical Engineering University of Pretoria Pretoria 0002 South Africa

This study presents a simulation based optimization study of a multi-tube trapezoidal cavity receiver of a Linear Fresnel Collector plant in Pretoria, South Africa. A comprehensive optimization study - an optical, thermal and economic optimization study - based on realistic simulations of these objective goals on an annual basis for such a plant is presented in this paper. This paper could be used as an applicable guideline for future researchers who work on the optimization of Concentrated Solar Power Plants.

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The Effect of Temperature on Stress Relaxation Behaviours in Bovine Cortical Bones

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IOP Conference Series: Materials Science and engineering 2018年第1期433卷

作者： Dr Bashar Awaid Bedaiwi Heider Abd Ali Abdalkadum Asst. Prof. PhD. Al-Mustansiriya University/College of Engineering Department of Mechanical Engineering Baghdad Iraq Msc. Student Al-Mustansiriya University/College of Engineering Department of Mechanical Engineering Baghdad Iraq

Stress relaxation is defined as the decay resulting from stress placed upon a material exposed to constant strain. Stress relaxation equipment designed and manufactured according to ASTM E328-86 was thus created to test this type of decay. Samples were extracted from animal femurs, in particular cortical bones from bovine around 24 months in age. The effect of various temperature on the stress relaxation behaviours of bovine femur samples was thus studied. The samples were examined for 1,800 seconds under the influence of three degrees of stress (25, 50, and 65 MPa respectively), with different temperatures of 29, 35, 40, and 50 °C used for each stress level; the stress results and diagrams for the effects of each stress were recorded and drawn separately.

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Investigation of EDM Process parameters for Hybrid Metal Matrix Composites

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IOP Conference Series: Materials Science and engineering 2018年第1期377卷

作者： Kamalkishor G. Maniyar Dr. Dilip S. Ingole PhD. Research Scholar Mechanical Engineering SGBAU Amravati (M.S.) India Professor Department of Mechanical Engineering PRMITR Badnera (M.S.) India

The goal of present research work is to investigate the Electrical discharge Machining process parameters namely current, pulse on time and combined equal weight percentage of silicon carbide and graphite on material removal rate, tool wear rate and surface roughness of hybrid metal matrix composites. Experimental trails are done by Taguchi's L27 orthogonal array. Signal to noise ratio is used to determine optimal setting of process parameters. Analysis of Variance is utilized to discover the most influential machining process parameters on output responses. This examination have shown results of ideal machining condition which can be utilized to boost material removal rate as well as to limit tool wear rate and surface roughness. Finally results are validated by confirmation Tests.

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Drilling studies on particle board composite using HSS twist drill and spade drill

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IOP Conference Series: Materials Science and engineering 2018年第1期402卷

作者： A Madhan Kumar K Jayakumar Assistant Professor Department of Mechanical Engineering New Prince Shri Bhavani College of Engineering and Technology Chennai - 600073 and PhD Scholar SSN College of Engg Chennai - 603110 India. Associate Professor Department of Mechanical Engineering SSN College of Engineering Chennai - 603110 India.

Composites materials are finding increased application in different engineering fields due to its favorable properties such as light weight, high strength, stiffness, etc. Among the composites, wood based composites are natural composites in which particle board (PB) and medium density fiberboard (MDF), etc., are extensively used in domestic and commercial purposes mainly in wood based furniture. Among different machining processes, drilling is the most generally used machining process in wood working industry for assembly operations and also affects the surface quality, aesthetic appearance and performance of the final product. Delamination at entry and exit sides of a hole, edge chipping, surface damage, etc are the major damages occurs during drilling of PB composites. The surface defects and delamination damages are significantly influenced by different machining particularly drilling parameters and machining environment. Therefore, study of effect of drilling parameters and machining environment on PB composite is an important area and it needs a detailed analysis. Twist drill is a most commonly used drill bit for drilling all materials however spade drill is specially used in drilling PB composite with lower thrust force and torque and spade drills is commonly used drill bit for rough drilling of particle board composite [5].

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