bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selection of Method for Fatigue Life Prediction Under Random Loading
Authors: Awasthi Amit , Mckeown Stephen , Sahay C. , Sammakia Bahgat 
Published: November 2021

Abstract
Solder fatigue continues to be one the primary reliability concerns in electronic packages. Three basic factors are necessary to cause fatigue failure. These are (i) a stress of sufficiently high value, (ii) varying amplitude stress, and (iii) a number of cycles of applied stress. Fatigue failure of a solder joint may also occur under cyclic thermal loading. The goal of this project is to compare the experimental results of fatigue testing with the various theoretical approaches (Rainflow counting method, Steinberg’s 3 band approach, and Rayleigh’s method) and come up with a formulation that would predict solder fatigue failure under random vibration loading.
Experiments have been performed to collect data. Initially various components having frequency range from 20–2000Hz were combined at random phase to produce a random profile. Rainflow cycle counting was done on 125 random profiles using an algorithm developed by downing (1982). The basic assumption made in this algorithm is that the strain-time history starts with either the maximum peak or the minimum valley. Further each cycle was segregated into one of the three bands depending on the value of the range of the cycle. It was found that the results matched very closely with Gaussian distribution curve.
The first phase of testing was to observe the behavior of aluminum and soldered copper (forming a lap joint) specimens under completely reversed sinusoidal loading in order to evaluate S-N curve. Three different stress levels were chosen and all experiments were carried out at a frequency of 20Hz. The second phase of testing consisted of observing the behavior of both the samples under semi-random loading. Random waveform was generated through a waveform function generator and was externally fed to the MTS machine.
The present paper presents the result of experiments along with the applicability to the three approaches to prediction.
Power Consumption of Polymer Solutions in a Stirred Vessel Powered by an Hyperboloid Impeller
Authors: Cavadas Adélio S. , Pinho Fernando T. 
Published: November 2021

Abstract
Measurements of power consumption in stirred vessel flows powered by a Rushton and an hyperboloid impeller were carried out. The fluids were aqueous solutions of tylose, CMC and xanthan gum at weight concentrations ranging from 0.1% to 0.6% and also included Newtonian fluids.
For the Rushton turbine flows the addition of polymer increased the Newton number by about 13–20% at Reynolds numbers in the range 1,000–3,000, whereas with the hyperboloid impeller the Newton number decreased about 13%. This decrease was especially noticeable for the CMC solutions and was absent from the 0.2% tylose solution flow.
Concentrated aqueous solutions of CMC (5.2%) and XG (3.6%) were also produced to determine the characteristic impeller parameter k for the hyperboloid, following the procedure of Metzner and Otto (1957) which was found to be 48 ±16.
Validation of Rheological Equations for Lubrication by Dynamic Experiments
Authors: Harnoy Avraham 
Published: November 2021

Abstract
Steady state experiments for determining the rheological characteristics of various non-Newtonian fluids. In particular, shear flow experiments, between cone and plate, are widely used for this purpose. In this study, it is shown that steady state experiments are not sufficient and dynamic (time dependent) experiments must be also conducted to uncover all the rheological characteristics. A squeeze-film flow between two parallel disks is shown to be a simple dynamic experiment that is suitable for viscoelastic fluids. This experiment can be used for validating of rheological constitutive equations of non-Newtonian fluids.
Decomposed EPS Gases Pressure Measurements in Iron Lost Foam Casting Process
Authors: Liu Ying , Bakhtiyarov Sayavur I. , Overfelt Ruel A. 
Published: November 2021

Abstract
A computer-aided temperature and pressure measurement technique has been built to study the thermal and pressure related processes during lost foam casting. The behavior of the gas pressure from the decomposed styrofoam pattern by-products inside both the mold and pattern during casting of ductile iron was investigated experimentally for coated and non-coated patterns. A transient history of temperature and pressure fluctuations is presented during the filling and freezing of the casting. The size of the pattern decomposition zone at the liquid metal/foam interface is estimated using the experimental data.
Experimental Study of EPS Decomposition in Lost Foam Casting Process
Authors: Liu Ying , Bakhtiyarov Sayavur I. , Overfelt Ruel A. 
Published: November 2021

Abstract
The thermal degradation of bulk and miniature samples of expanded polystyrene (EPS) has been investigated in a neutral atmosphere at 800°C and by differential scanning calorimetry over a range of temperatures. The differential scanning calorimetry experiments showed that the foam volatilization temperature is significantly affected by heating rate and varies from 380°C to 470°C at heating rates from 10–60°C/min. Bulk degradation due to the 800°C heat source appeared to occur instantly as the foam pattern approached the close proximity of the heat source. The chamber pressure increased and the heat source temperature dropped during degradation. The gas yield at 800°C was determined to be about 610 cm3 (STP)/g of EPS.
Gas Displacement of Non Newtonian Fluids in a Tube
Authors: Soares Edson J. , Mendes Paulo R. Souza , Carvalho Marcio S. 
Published: November 2021

Abstract
The displacement of a fluid in a capillary tube by gas injection occurs in many practical applications like enhanced oil recovery, coating of catalytic converters and gas-assisted injection molding. This situation has been extensively studied both by theory and experiments in the case of Newtonian fluids. However, the complete understanding of the effects of the rheological properties of the displaced fluid in this type of flow is still under investigation. Recent work has shown that, at a given Capillary number, the amount of shear thinning liquid deposited on the tube wall falls with decreasing power-law exponent, but a singular perturbation method was not able to capture this effect. The flow of viscoelastic liquids has also been analyzed experimentally by measuring the fractional coverage of the tube wall and by Particle Tracking Velocimetry. The main conclusion was that the flow near the interface presents strong extensional deformation and that the viscoelastic behavior of the liquid leads to larger deposited liquid layer on the wall. Flow simulation with non Newtonian liquids for this situation is rare. The presence of the free surface and the non linearities of the constitutive model make the problem extremely complex. In this work, the complete two dimensional solution of the free surface flow is obtained using the Galerkin finite element method. The rheological character of the liquid is modelled by two different constitutive equations: a simple Generalized Newtonian Liquid model, to analyze the effect of shear sensitive liquids; and a new algebraic constitutive relation that is capable of describing variable shear and extensional viscosity, first normal stress coefficient and second normal stress coefficient. This equation is used to analyze the effect of the viscoelastic properties of the liquid on the flow field.
Non-Linear Lubricant Behavior in Concentrated Contacts
Authors: Szeri Andras Z. 
Published: November 2021

Abstract
Elastohydrodynamic lubrication (EHL) is the name given to hydrodynamic lubrication when it is applied to solid surfaces of low geometric conformity (counterformal contacts) that are capable of, and are subject to, elastic deformation. In bearings relying on EHL principles, the residence time of the fluid is less than 1 ms, the pressures are up to 4 GP, the film is thin, down to 0.1 μm, and shear rates are up to 108 s−1 — under such conditions lubricants exhibit material behavior that is distinctly different from their behavior in bulk at normal temperature and pressure. In fact, without taking into account the viscosity-pressure characteristics of the liquid lubricant and the elastic deformation of the bounding solids, hydrodynamic theory is unable to explain the existence of continuous lubricant films in highly loaded gears and rolling contact bearings.
Pressure Drop of Liquid Crystal Flowing Between Two Parallel-Plate Electrodes
Authors: Tsukiji Tetsuhiro , Tanabe Shinsuke 
Published: November 2021

Abstract
Liquid crystal is one of homogeneous ER (Electrorheological) fluids in some range of temperature. Transient responses of pressure drop are examined when liquid crystal flows between two parallel-plate electrodes for constant flow rates. When voltages are applied on the liquid crystal and removed, the pressure responses of the inlet of electrodes are measured with the pressure transducer. At the same time, liquid crystal between the transparent electrodes made of glass is visualized with the high-speed video camera to investigate the time history of the director of the liquid crystal. Outlet of the flow channel with two parallel-plate electrodes is atmosphere. Relation between the flow visualization results and changes of pressure drop is investigated especially for transient period. In the present experiment the flow rates change from 0.001cc/sec (velocity is 1mm/sec) to 0.003cc/sec and the electric field intensity is from 0.2kV/mm to 1kV/mm. The gap of the electrodes is 0.2mm. The isotropic-nematic transition is 35.5°C and smectic-nematic transition is 23.1°C. The open-loop test facility with the liquid crystal is set in a pyrostat to keep the temperature constant.
The Yield Stress for an Electrorheological Fluid in Squeeze
Authors: El Wahed Ali K. , Sproston John L. 
Published: November 2021

Abstract
This paper is concerned with an experimental and theoretical determination of the rheological performance of an electrorhcological (ER) fluid when subjected to time-dependent applied loads. The experimental facility was built as a squeeze cell in which the fluid is sandwiched between two electrodes, one fixed and the other moving, which permits the instantaneous measurement of the mechanical and electrical responses of the fluid. The transient rheological characteristics of the fluid were assessed for various mechanical force levels and for constant voltage excitation of the fluid. Input and output stress levels across the fluid were monitored enabling the dynamic response of the fluid to be determined using a combination of displacement, force, velocity and acceleration transducers. The experimental results were compared with the results from a modified theoretical analysis, which employs a bi-viscous shear stress/shear strain characteristic of the electrically stressed fluid together with a fluid yield stress, which has a strain-direction dependence on the electrical field.
A Topological Study of the Genesis of a Horseshoe Vortex in the Symmetry Plane Due to an Adverse Pressure Gradient
Authors: van den Berg Martijn A. , Proot Michael M. J. , Bakker Peter G. 
Published: November 2021

Abstract
The present paper describes the genesis of a horseshoe vortex in the symmetry plane in front of a juncture. In contrast to a previous topological investigation, the presence of the obstacle is no longer physically modelled. Instead, the pressure gradient, induced by the obstacle, has been used to represent its influence. Consequently, the results of this investigation can be applied to any symmetrical flow above a flat plate.
The genesis of the vortical structure is analysed by using the theory of nonlinear differential equations and the bifurcation theory. In particular, the genesis of a horseshoe vortex can be described by the unfolding of the degenerate singularity resulting from a Jordan Normal Form with three vanishing eigenvalues and one linear term which is related to the adverse pressure gradient. The examination of this nonlinear dynamical system reveals that a horseshoe vortex emanates from a non-separating flow through two subsequent saddle-node bifurcations in different directions and the transition of a node into a focus located in the flow field.
Flow Through a Realistic Arterial Geometry With Two Aneurysms: Mixing Characteristics and Residence Times
Authors: Butty V. D. , Gudjonsson K. , Buchel P. , Makhijani V. B. , Ventikos Y. , Poulikakos D. 
Published: November 2021

Abstract
In the present work, we are presenting computational simulation results for the flow in a human right internal carotid artery, exhibiting two saccular aneurysms close to each other. We utilize computer tomography data in order to extract a realistic geometric description of the region of interest. Aspects of the flow inside the aneurysms are discussed in connection to secondary motion patterns and inflow-outflow regimes. We construct residence time maps that exhibit strong non-uniformity, connected to the existence of fluid entering only the first, only the second, or both aneurysms. Preliminary evidence that the inflow-outflow patterns of the two aneurysms may be leading to particularly complex flow and to chaotic mixing is discussed, based on the apparent properties of both the residence time map iso-contours and the basins of attraction of the two aneurysms. Particular attention is paid in establishing grid independence for the computed results and for this reason a second order spatial discretization scheme is utilized, with resolutions ranging from approximately 110,000 to 1,070,000 tetrahedra.
Computational Fluid Dynamics (CFD) Analysis to Study the Flow Phenomena Inside the Hydraulic Tank of an Earthmoving Vehicle
Authors: Barman Priyatosh 
Published: November 2021

Abstract
This paper summarizes the successful application of Computational Fluid Dynamics (CFD) analysis to study the flow phenomena inside the hydraulic tank of an earthmoving vehicle. The main purpose of this CFD analysis is to reduce the aeration inside the tank suction lines to avoid any cavitation damages to the suction pumps. The main source of aeration is suspected due to the strong fluid circulation inside the partially filled hydraulic tank. The CFD analysis predicts qualitatively as well as quantitatively the fluid circulation in the tank. Also, the CFD analysis is used to find the fluid pressure and velocity distribution in the tank.
Experimental Investigation of Rotating Instabilities in a Two-Stage Centrifugal Compressor With Vaneless Diffuser
Authors: Golubev Vladimir V. 
Published: November 2021

Abstract
This paper examines unsteady response of an experimental two-stage centrifugal compressor with vaneless diffusers. A thorough investigation of pressure fluctuations along the compressor channel is carried out in order to examine the onset of unstable flow conditions. Rotating stall structures are localized, with special attention paid to identifying the most sensitive area of the multi-stage compressor channel which may serve as a precursor to unstable compressor operation. It is shown that both stages may develop rotating stall structures simultaneously, however the 2nd stage tends to destabilize first and reveals higher magnitudes of the unsteady response.
Numerical Simulation of Particle Flow, Mixing and Chemical Reaction in the Circulating Fluidized Bed Absorbers
Authors: Mao D. , Edwards J. R. , Kuznetsov A. V. , Srivastava R. 
Published: November 2021

Abstract
A mixing model has been developed to simulate particle’s residence time distribution (RTD) in the circulating fluidized bed absorbers (CFBAs), also, a gas-solid reaction model for Sulfur Oxide removal by limestone has been developed. For the reaction model that considers RTD distribution inside the core and annulus regions of CFBA, macrochemical reaction can be simulated based on microchemical reaction dynamics. The presented model can predict Sulfur Oxide and limestone distributions inside the CFBA and give the amount of limestone needed to remove a given percentage of Sulfur Oxide. It is found that Sulfur Oxide concentration at the outlet from CFBA decreases with the increase of CFBA distance from the bottom in the core region. However, limestone concentration exhibits a very slight variation in the core region. This means that in CFBAs limestone is efficiently utilized to remove Sulfur Oxide. Sulfur Oxide partial pressure at the exit of CFBA decreases with the increase of the percentage of fresh limestone in the inlet to CFBA.
A Nonsymmetrical Uncertainty Analysis Method
Authors: Xu C. , Amano R. S. 
Published: November 2021

Abstract
An uncertainty evaluation method was proposed to reasonably consider the measurement uncertainty for measured variables which have nonsymmetric uncertainty components. The present method considers the nonsymmetrical uncertainty as one of the important parts of the uncertainty evaluation of measurements, which has not been dealt with in detail in previous uncertainty evaluation method. The present method provides more reasonable way to evaluate measurement uncertainty than other existing methods. The method is applied to report the uncertainty of a dynamic pressure measurement system.
Analysis of the Flow Past a Pivoting Plate
Authors: Veber Pascal 
Published: November 2021

Abstract
The increase of the water level in a room due to a pipe break is a common problem for many nuclear power plants. To avoid the submerging of safety components, flaps for load relieving are installed at the door. The increase of the water pressure will result in the opening of the flap. The plate weight counteracts the pressure force. In order to determine the water flow past the plate, a simple method is presented. Using the steady state balance of the forces moments, a rough estimation of the flow can be performed. A study case is discussed.
Calibration and Measurements of Low Speed Wind Tunnel Using Hot Wire
Authors: Shan Choo Voon 
Published: November 2021

Abstract
As technology advances, the principle of low air velocity plays an important part in high tech industries. The concept of measuring low speed in a confined area is a challenging one as the normal calibration method is not suitable. This paper study the method of calibrating and measuring low speed air using hot wire which focus on the effect of the overheat ratio on the calibration of a single hot wire and the design of a probe to be used for studying free convection effect.
Thermal Hydrodynamic Model of Oil-Immersed Power Transformers
Authors: Mufuta Jean-Michel 
Published: November 2021

Abstract
A lower hierarchy model of an oil-immersed – transformer was used to calculate the heat transfer in transformer windings. Contrary to the approach of other investigators, who considered a global network, this approach has the merit of focusing on the main body of the transformer. Further, it allows taking into account the geometric aspect of the problem. Consequently, the correlations found in this study include not only the Reynolds and the Prandtl numbers, but also the pitch ratio and the number of discs in the transformer.
The geometric model consists of an array of rectangular blocks with an in-line arrangement. It represents a part of the whole transformer. An array of 10 blocks with sufficient grid refinement was found to be relevant to study the heat transfer process.
Two different flow regimes were considered: the pure forced convection-regime and the mixed convection regime.
For the first regime, the Reynolds number spans over the range [60...450]. For the second regime, the mass flow was defined as function of a parameter, which is the ratio of the Reynolds number and the Grashof number Re/Gr1/2. This parameter range spans over [0.1...1.0] and expresses the interaction between the inertia forces and the buoyancy forces.
Parallelization of the Pseudo-Spectral Code for DNS of Channel Flow on a Shared Memory Architecture
Authors: Tiselj Iztok , Hetsroni Gad 
Published: November 2021

Abstract
The present paper describes our experience with the parallelization of the pseudo-spectral computer code FLOWH, which is used for DNS simulations of the channel and flume flows. The original version of the FLOWH code was developed by Gavrilakis et al. 1986 [11] and was optimized for vector computers (Cray...). In 1999 and 2000 we started the parallelization of the code for the shared memory type of parallel computers SGI Origin and Sun for turbulent heat transfer calculations (Tiselj et. al. [1,2]). OpenMP parallelization directives were used and very similar performances were obtained on both types of computers. The efficiency of the parallelization on 32 CPUs is approximately 50%. The main reason for the relatively low efficiency of the parallelization (comparing to the efficiency of finite volume codes) is in the nature of the pseudo-spectral codes, which does not allow permanent allocation of the nodes onto the particular CPU like finite volume or finite element codes.
Dynamic Analysis of Diesel Engine Common Rail Injection System: Part I — Injector Dynamics
Authors: Borghi M. , Milani M. , Piraccini M. 
Published: November 2021

Abstract
The aim of the paper is to analyze the dynamic behavior of an actual electro-hydraulic injector, included into a high-pressure accumulator injection system (Common Rail).
Firstly, a brief introduction of the hypotheses adopted for a lumped parameter description of each part of an industrial version of the injector (BOSCH) is outlined, together with the definition of the hypotheses assumed to treat the fuel efflux through the injection holes, through the internal mechanical couplings and the damping orifices, or to descript of the cavitations.
Then, the dynamic behavior of the injector is analyzed adopting some of the command signals imposed to the pilot stage by the Electronic Central Unit (ECU), as actually implemented into the standard map of an on board ECU of a industrial diesel engine. Among others, the paper presents the results coming from the injector handling for medium values of the crank-shaft regime (1800 and 2400 rpm), for different pressure levels in the Rail and involving also the pilot injection.
The reliability of the numerical results is stated through a wide numerical vs. experimental comparison, made up on the basis of the fuel mass injected for each cycle.
Finally, the discharge characteristics characterizing the injection are determined, such as the effective mean velocity and the effective area of the liquid core at the holes exit, or injection holes discharge coefficient.
The Specific Flowrate of Deviation Function Based Lobe Compressors
Authors: Yang Daniel C. H. , Tong Shih-Hsi 
Published: November 2021

Abstract
In this paper a general flowrate formula for lobe pumps is derived in terms of the pitch and deviation functions of the pump rotor. This formula applies to both circular and noncircular rotor pitch profiles. In order to relate the pump flowrate only to rotor geometry, a dimensionless flowrate expression, called “specific flowrate”, is adopted. This enables the flowrate analysis of lobe pumps without the ad-hoc effects of individual pump size and rotor speed. It is found that pump rotors can be grouped by the similarity of their deviation functions. The specific flowrates of a given group of pump rotors can be expressed solely in terms of their corresponding lobe noncircularities. This formulation enables a systematic and efficient design process of new lobe pumps. Classes of new lobe rotors based on some typical deviation functions are designed, and their corresponding specific flowrate functions are also provided.