bluuebunny/crossref_metadata_2025 huggingface dataset:
Algebraic Approach to Design of Automatic Controls
Authors: Oldenburger Rufus
Published: January 2022

The solution of linear problems in automatic control is generally reduced to the study of ordinary differential equations and thus to characteristic equations, which are algebraic. It is then necessary to solve an algebraic equation to predict the transients for a given controlled system. Whether or not the system is stable can be determined from the simple test of Routh. Because of the great difficulties encountered in the past in solving algebraic equations, especially in the case of all roots complex, resort has been made to qualitative methods of automatic control design based on frequency response and other techniques. The author applies to algebraic equations for stable systems certain procedures, including a right to left synthetic division, which enable the engineer to approximate some of the roots, after which the solution for all of the roots can be obtained readily. From the roots, the analyst can tell what the transients will look like. Good transients are necessary for good control. The author’s method, in use at the Woodward Governor Company for several years, is applied to the design of a governor for a gas turbine.
Statistical Treatment of Sampled-Data Control Systems for Actual Random Inputs
Authors: Mori Masahiro
Published: January 2022

Fundamental statistical relations of sampled-data systems in terms of the correlation functions of time series, the pulse spectral densities, and the modified z-transform are presented. If one is interested in signals between sampling instants, the modified z-transform method can be applied easily to the statistical treatments, as are presented in the paper. The relation between this method and the analysis on the basis of variable-system theory is proved. Examples are given discussing discrete compensation of sampled-data control system from the statistical standpoint.
The Time and Temperature Dependence of Thermal Stresses in Cylindrical Reactor Fuel Elements
Authors: Merckx K. R.
Published: January 2022

A method of calculating the thermal stresses in cylindrical shapes is developed in this paper which uses a material model relating strain rate, temperature, strain, and stress. The material model, evaluated for unirradiated uranium, is used with this method to obtain the build-up and decay of the thermal stresses and strains in a solid-uranium fuel element operating in the temperature ranges of 100 to 350 C and 350 to 600 C during a 25-min period of increasing power generation and 700-min period of steady-state operation. During the period of increasing power generation, the elastic surface stresses are predicted to relax 60 per cent for the 100–350 C example and 48 per cent for the 350–600 C example. Further relaxation of 11.5 per cent for the 100–350 C case and 40 per cent for the 350–600 C case is calculated during the period of steady-state power generation.
Shear-Zone Temperature in Metal Cutting and Its Effects on Shear-Flow Stress
Authors: Kececioglu Dimitri
Published: January 2022

Relationships are given from which the mean shear-zone temperature in oblique, as well as in orthogonal cutting, can be calculated. The mean shear-zone temperature, developed when machining SAE 1015, 118 Bhn seamless-steel tubing under a wide range of cutting conditions, is calculated and is found to vary from about 410 to 840 F. The effect of the mean shear-zone temperature on the mean shear-flow stress is studied. In general, the mean shear-flow stress is found to decrease by about 1800 psi for a 100-deg F increase in the mean shear-zone temperature within the range of 410 and 840 F. This compares with the little or no effect of the mean shear-zone temperature on the mean shear-flow stress reported by Shaw and Finnie (1) and Chao and Bisacre (2), respectively. A more comprehensive approach is proposed to establish the effect of the important shear-zone factors on the mean shear-flow stress.
Heat Transfer in Liquid Metals
Authors: Lykoudis P. S. , Touloukian Y. S.
Published: January 2022

The problem of heat transfer in liquid metals is studied for the case of a fully developed turbulent flow in cylindrical pipes of constant diameter, the fluid under consideration being heated (or cooled) by a constant and uniform heat input at the wall. In the analysis, the similarity theory between heat and momentum transfer is used. A theory is presented which gives the ratio of eddy diffusivities for heat and momentum transfer as a function of the Prandtl modulus. It is shown that heat transfer in liquid metals can be analyzed universally in terms of a dimensionless parameter called the “generalized Peclet modulus” and defined by the relationNPe​*=(NRe​*)(NPr​*)=[NRe(f/2)1/2](NPrσ) Temperature profiles are presented and the limiting cases for NPr = 0 are studied.
On the Stability of Boiling Heat Transfer
Authors: Zuber Novak
Published: January 2022

Boiling heat transfer in the nucleate region is reviewed. The transition film-boiling region is analyzed by considering the stability of a plane vortex sheet separating two inviscid fluids. Using the classical results of Helmholtz, Kelvin, and Rayleigh, expressions have been derived that predict the maximum and minimum heat-transfer rates in the nucleate and the film-boiling regimes, respectively. The model exhibits the essential features of the phenomenon and shows good agreement with experimental data.
Combined Free and Forced Convection in a Constant-Temperature Vertical Tube
Authors: Jackson T. W. , Harrison W. B. , Boteler W. C.
Published: January 2022

An experimental study of superposed free and forced convection for air in a vertical tube is examined. The Nusselt modulus, based on the log-mean-temperature difference, ranged from 15.0 to 57.1; the Graetz modulus, based on the bulk or average temperature of the air, ranged from 40.2 to 1710; and the Grashof-Prandtl D/L modulus, based on properties of air at the wall temperature, ranged from 1.05 × 105 to 1.30 × 106. The Martinelli equation for heating fluids flowing vertically upward does not correlate the data satisfactorily. An analysis of the system from a macroscopic viewpoint leads to the derivation of an equation which fits the experimental data.
Theoretical and Experimental Analysis of Hydrodynamic Gas-Lubricated Journal Bearings
Authors: Sternlicht B. , Elwell R. C.
Published: January 2022

In recent years, gas-lubricated bearings have aroused a great amount of interest. The interest is centered on the advantages of gas bearings for four major applications: (a) High-temperature devices, for which there is yet no lubricant available. (b) Radioactive atmospheres, where conventional lubricants may break down. (c) Applications sensitive to contamination, such as jet engines, where fouling from lubricating oil becomes serious. (d) Low-friction devices—an especially important advantage because of the trend to high-speed machinery.

This paper presents a numerical solution for finite-width journal bearings and results of experiments conducted with air-lubricated hydrodynamic journal bearings. Comparison is made between theoretical and experimental results. Design formulas and recommendations for future studies also are included.
Laminar Film Condensation of Pure Saturated Vapors on Inclined Circular Cylinders
Authors: Hassan Kamal-Eldin , Jakob Max
Published: January 2022

Laminar film condensation of pure saturated vapors on inclined circular cylinders is treated analytically. The analysis is based on, and made under the same assumptions of, Nusselt’s theory of film condensation. Experiments were performed to check the analytic results.

In the analysis, the problem is expressed in terms of dimensionless groups and the solution gives, in these terms, the local film thickness at any point on the surface of a cylinder. From the results of the analysis one can obtain the local film coefficient, and hence a mean film coefficient for the entire surface of any cylinder at any inclination.

The analysis shows that every tube has an optimum inclination at which the rate of condensation on the entire tube is a maximum.

The experiments were carried out by condensing steam on the inside surface of a thick copper tube 1¼ in. diam and about 8⅛ in. long. The actual film coefficients obtained during the experiments were 28 to 100 per cent higher than those predicted by the theoretical analysis. The deviation from the theory increased with the inclination of the tube and the temperature difference between the tube surface and the steam.
The Third Law of Thermodynamics: A Half-Century Appraisal of the Nernst Heat Theorem
Authors: Potter J. H.
Published: January 2022

Fifty years have passed since Nernst formulated his “New Heat Theorem,” which he subsequently referred to as the “Third Law of Thermodynamics.” The several statements of the theorem are examined in the light of classical thermodynamics, quantum considerations, and recent low-temperature experiments. The limitations under which the heat theorem may be considered a basic scientific law are cited.
The Effect of Tool-Chip Contact Area in Metal Machining
Authors: Takeyama H. , Usui E.
Published: January 2022

This paper stresses the effect of the tool-chip contact area in metal machining. Little attention has been paid to this variable in analyzing machinability. According to authors’ tests, the tool-chip contact area is closely related not only with the machining performance, but with the tool life. This paper treats the former subject summing up the results obtained by the experiments using special devices.
Influence of Pressure and Temperature on Oil Viscosity in Thrust Bearings
Authors: Sternlicht B.
Published: January 2022

A theoretical study to determine the influence of pressure and temperature on oil viscosity in finite-length thrust bearings. This paper points out that it is theoretically possible to determine the influence that pressure and temperature play on oil viscosity and, in turn, on bearing performance by solving the energy and Reynolds equations simultaneously.
Symposium on Welded Spiral Cases from the Consulting Engineers’ and Users’ Viewpoint: Welded Spiral Case Construction Procedures
Authors: Latham G. R.
Published: January 2022

This paper discusses comparative costs between riveted and welded spiral cases, suggests specific requirements for insuring satisfactory welded spiral cases, under varying erection conditions, and sets forth construction and welding procedures being carried out on three different examples.
The Transient Response of a Two-Fluid Counterflow Heat Exchanger—The Gas-Turbine Regenerator
Authors: Cima R. M. , London A. L.
Published: January 2022

Presented are some solutions for the transient behavior of a two-fluid direct-transfer counterflow gas-turbine regenerator, obtained experimentally using an electrical analog system. While restrictions were imposed on certain parameters with the gas-turbine-regenerator problem in mind, these results, presented in nondimensional form, are also of limited use for other two-fluid exchanger problems. A set of seven independent nondimensional parameters is proposed for general use. These include the three commonly associated with the steady-state performance plus four additional parameters unique to the transient problem. The electrical analog system is described in the Appendix and the associated experimental uncertainties are considered.
Sulfuric Acid Corrosion in Oil-Fired Boilers—Studies on Sulfur Trioxide Formation
Authors: Anderson Donald R. , Manlik Frank P.
Published: January 2022

Experimental studies on economizer and air-heater corrosion resulting from the formation of sulfuric acid in residual-oil-fired boilers are described. Factors controlling the oxidation of sulfur dioxide to sulfur trioxide have been investigated in a small experimental boiler. The fuel used was a distillate oil to which synthetic compounds were added to simulate the sulfur and metallic components commonly found in residual oils. The sulfur trioxide content of the flue gases was determined indirectly by measuring the corrosion of and sulfate deposition on a steel specimen maintained at a controlled temperature.

In an initially clean boiler, approximately equal quantities of sulfur trioxide formed in the flame, furnace, and convection sections, while less formed in the economizer-air heater section. Nickel, iron, sodium, and vanadium in the fuel each decreased the corrosion normally experienced by the test specimen, the magnitude of the effect increasing in the order given. Deposits of these metallic fuel-ash components in the boiler had a relatively small effect on the corrosion of the test specimen. Only the iron deposits indicated significant catalytic activity for the oxidation of sulfur dioxide to sulfur trioxide.

Combinations of sodium and vanadium in the fuel were found to decrease corrosion in an initially clean furnace, but boiler deposits from certain combinations of these elements were found to increase corrosion substantially. This catalytic effect is predominant over extended periods of time.
An Investigation of the Variation in Heat Absorption in a Pulverized-Coal-Fired Slag-Tap Steam Boiler at Blaine Island, Charleston, W. Va.
Authors: Orning A. A. , Weintraub M. , Schwartz C. H. , Mihok E. A. , McCann C. R. , Harrold W. C.
Published: January 2022

This paper resulted from the sixth in a series of investigations of heat absorption in large steam-boiler furnaces, sponsored by The American Society of Mechanical Engineers Special Research Committee on Furnace Performance Factors. The furnace heat absorption was determined from the furnace exit-gas composition and temperature in 18 tests on a steam generator rated at 250,000 lb of steam per hr at 675 psi and 670 F. The furnace was fired with pulverized coal, through opposed burners with reinjection of fly ash, over a refractory-insulated slagging bottom. Furnace heat absorption, at various loads and excess air values, was correlated with the adiabatic flame temperature and the residence time of combustion products in the furnace. The furnace performance was found to depend upon burner adjustments, but did not significantly depend upon recirculation of fly ash.
Effects of Stage Characteristics and Matching on Axial-Flow-Compressor Performance
Authors: Stone Aubrey
Published: January 2022

The use of stage characteristics obtained from test data in the performance analysis and development of an axial-flow compressor is described. The discussion is illustrated by an analysis of the general trends in relative stage matching as shown by an idealized example and also by test experience. Factors governing major performance parameters are discussed and certain development problems and possible solutions are reviewed.
Application of the Analog Computer to Product Dynamic Performance in Typical Hydraulic Circuits
Authors: Reethof Gerhard
Published: January 2022

The successful use of electronic-analog-computing techniques in the simulation of typical hydraulic systems is demonstrated. As an example, the instabilities of a certain open-center hydraulic-booster system are simulated, and corrective action is indicated and verified. The study involves the analysis of a grossly nonlinear system and methods of function generation are given.
Dimensionless Correlation of Coefficients of Turbine-Type Flowmeters
Authors: Hochreiter H. M.
Published: January 2022

The principles of dimensional reasoning are applied to a kinematic flowmeter of the turbine or propeller type. Experimental results are correlated over a wide range of fluid conditions and geometric variations, and coefficients compared against those predicted from a one-dimensional design equation.
Thermal Transfer in Turbulent Gas Streams—Effect of Turbulence on Macroscopic Transport From Spheres
Authors: Sato Kazuhiko , Sage B. H.
Published: January 2022

The rate of thermal transport from spheres in a flowing stream is of interest in many industrial operations. Limited data are available concerning the effect of turbulence level on this transfer process. Measurements of the thermal transport from spheres to an air stream at four levels of turbulence were made at four velocities varying between 4 and 32 fps. Results are presented in terms of the Nusselt number. The experimental work is a portion of a detailed study of the local thermal and material transport from spheres in turbulent air streams. The data indicate a significant increase in the thermal transport with an increase in the level of turbulence at a constant Reynolds number. For example, the Nusselt number was increased from 53 to 62 upon an increase in the level of turbulence from 0.05 to 0.12 at a Reynolds number of 7200.
Effect of Vibration on Heat Transfer From a Wire to Air in Parallel Flow
Authors: Anantanarayanan R. , Ramachandran A.
Published: January 2022

Studies on the effect of vibration of the heat-transferring surface on convective heat transfer are few and limited to natural-convection conditions. The present investigation deals with the influence of vibration on heat transfer from an electrically heated nichrome wire to parallel air streams. Air velocities ranged from 34 to 63 fps. At each air velocity, frequencies ranging from 75 to 120 cycles per second and different amplitudes were employed as vibrational variables. Both frequency and amplitude increased the heat-transfer coefficient. An increase as high as 130 per cent was obtained. The correlation of the experimental data shows that the proportional increase in heat transfer was controlled by the ratio of the mean vibrational velocity to the air-stream velocity.
Local Laminar Heat Transfer in Wedge-Shaped Passages
Authors: Eckert E. R. G. , Irvine T. F. , Yen J. T.
Published: January 2022

Heat transfer in noncircular passages recently has received increased attention in connection with various engineering applications, especially with nuclear-reactor technology. The present paper presents the results of calculations for heat transfer connected with steady laminar flow through ducts whose cross sections have the shape of circular sectors. Hydraulically and thermally developed flow is assumed. The temperature field, peripheral distribution of inner-duct surface temperature and of heat flux, as well as heat-transfer coefficients and friction factors, are presented for two boundary conditions: Peripherally constant heat flux and peripherally constant surface temperature, both with longitudinally constant heat flux. It is found that even average heat-transfer coefficients may be different by an order of magnitude for these two conditions. For this reason, it is pointed out that solutions for a class of boundary conditions can be obtained by linear superposition of the results obtained for the two conditions mentioned.
Survey of Mathematical Methods for Nonlinear Control Systems
Authors: Loeb Julien M.
Published: January 2022

This paper is a survey of presently known mathematical methods applicable to nonlinear control problems. After emphasizing the need for general theories which alone can facilitate equipment design, the author discusses: a Phase-plane and phase-space methods for graphical representation of general system behavior; b describing-function analysis of limit cycles; c piece-wise linear analysis; d probability calculus for the study of noise and random inputs in nonlinear systems; and e energy-balance and stroboscopic methods which apply to particular features of a system.
Theory of Oil Whip for Vertical Rotors Supported by Plain Journal Bearings
Authors: Ørbeck Finn
Published: January 2022

This paper endeavors to show that by considering the pressure forces, the viscous drag forces, and the centrifugal forces acting on the journal in a plain journal bearing in oil whip, it is possible to obtain a rational explanation of this phenomenon. The conditions of force equilibrium of the journal lead to two equations, the first of which determines the ratio of frequency of whirl to frequency of rotation in terms of the eccentricity ratio. The second equation relates the eccentricity ratio to the frequency of rotation. These equations therefore suffice to describe oil whip in frequency and amplitude. Numerical studies of the problem indicate some agreement with published experimental studies.
Solution of the Tapered-Land Sector Thrust Bearing
Authors: Pinkus O.
Published: January 2022

Reynolds’ equation in polar co-ordinates was solved on a digital computer for the actual sectorial geometry of finite thrust bearings. The oil-film shape is that of a uniform taper in the circumferential direction. Minimum film thickness, side and end leakage, power loss, and centroids are given in general dimensionless form as functions of a dimensionless group (μN/P) (L/b)2. A wide range of bearing parameters is covered and solutions are given for very heavy unit loadings. A short discussion is included on how to perform thrust bearing calculations using the results and expressions derived in the paper.
Contribution to the Stability Theory of Systems of Surge Tanks
Authors: Jaeger Charles
Published: January 2022

The paper develops and discusses the theory of stability for two surge tanks in series on the same tunnel. The number of free parameters involved in the analysis is reduced to the point where a general discussion becomes possible. The effect of relative tank locations, diameters, and periods is discussed, and the importance of friction losses on the over-all stability.
Water Hammer in Nonuniform Pipes as an Example of Wave Propagation in Gradually Varying Media
Authors: Paynter H. M. , Ezekiel F. D.
Published: January 2022

Wave disturbances propagate down a fluid pipe, whose characteristics vary only gradually over a single wavelength, in nearly the same manner as a uniform pipe of the same total transmission time. However, the variations in pressure and flow along the pipe are modified directly and inversely, respectively, with the square root of the change in characteristic impedance level. This generally useful “Green’s Law” approximation is checked against exact solutions and other methods of approximation.
Three-Dimensional Photoelasticity and Its Application in Machine Design
Authors: Leven M. M. , Wahl A. M.
Published: January 2022

The simplest equipment, the best model materials, and the most effective techniques for three-dimensional photoelastic tests are described. The optical equipment involves only a simple diffusion polariscope using only a single camera lens. Phthalic anhydride-cured epoxy resins, which are relatively easy to cast in large sizes, have much superior properties for photoelastic tests than previously used materials. A simple technique of using surface slices and normal incidence of light will give adequate results for the stresses on free surfaces. At interior points, the effective stress can be obtained by measuring the retardation and isoclinic parameters on the three faces of random oriented small cubes. Some discussion is given regarding methods of applying the photoelastic results in practical design applications where fatigue, repeated strain cycling, plastic flow, and creep-rupture effects may occur during operation.
The Boundary Layer on the End Wall of a Turbine Nozzle Cascade
Authors: Senoo Yasutoshi
Published: January 2022

The boundary layer flow was experimentally studied on an end wall of a turbine-nozzle cascade and the following results were obtained. 1 The boundary layer was laminar at the throat of the nozzle, even when the upstream boundary layer was apparently turbulent. 2 The end-wall boundary layer in the nozzle was little affected by the upstream boundary layer. A theoretical consideration supports the results and also reveals that the part of secondary flow in the nozzle, which is related to the upstream boundary layer, depends upon the configuration of the nozzle. 3 The observed boundary layer behavior was compared with the predicted flow by a three-dimensional laminar boundary layer theory, and good agreement was obtained. 4 The measurements showed the end-wall boundary layer rolling up at the suction-surface end-wall corner of the cascade. The mechanism of the rolling up is explained.
A Theory of Lubrication in Short Journal Bearings With Turbulent Flow
Authors: Tao L. N.
Published: January 2022

Short journal bearings operating in the turbulent-flow region have been studied. Expressions for the pressure distribution, the load capacity, and the attitude angle have been obtained. Also the condition of laminar flow is shown as the special case of the present study.
Subharmonic Oscillations of Nonlinear Feedback Control Systems
Authors: Ogata Katsuhiko
Published: January 2022

This paper presents an analysis on subharmonic oscillations as responses of nonlinear feedback control systems. The non-linearities treated in this paper are those whose input-output characteristic curves show saturating or limiting characteristics and are skew symmetric with respect to their origins. The analysis shows that the outputs of such nonlinear systems will oscillate either with the input frequencies or with odd order subharmonics of the input frequencies. This paper also presents a design aid for eliminating the possibility of subharmonic oscillations. Electronic analog computer techniques were employed to obtain the experimental results presented here.
Activity of Cell on Micro Stripe Ridges After Force Field Stimulation With Centrifuge
Authors: Hashimoto Shigehiro , Yonezawa Hiroki
Published: January 2022

Does response of a cell depend on the history of the direction of mechanical stimulation? A mechanical force field generated by centrifugal force is applied to the scaffold plane in the present study. To control the cell direction (0, 45, 90 degrees) with respect to the tangential force, striped micro-ridges in 3 directions were machined on the scaffold surface by photolithography technique. The behavior (movement, and deformation) of each mouse myoblast after cultivation in the tangential force field for 5 hours was tracked for 10 hours by time-lapse images. Experimental results show that the velocity of each cell migration tends to increase regardless of two-dimensional projected area on the scaffold by hysteresis of exposure to tangential force field perpendicular to the longitudinal direction of the cell. The experimental results will lead to the elucidation of the effect of the direction of force stimulation on cells.
Complex Material Behavior Seen With Novel Internal Cathode Tubular Solid Oxide Fuel Cells
Authors: Hartwell Alexander R. , Ahn Jeongmin
Published: January 2022

Rapid climate change and the rising frequency of extreme natural weather events that it causes motivate a paradigm shift in how energy is produced, directing much research interest towards combined heat and power (CHP) systems. With the fuel flexibility offered by solid oxide fuel cells (SOFCs) and their need for high operation temperatures, combustion systems become obvious targets for integration. The fuel-rich combustion of natural gas can produce synthesis gas, while providing the heat necessary for SOFC operation. To remedy issues associated with degradation of cell components, tubular SOFCS (tSOFCs) are best suited to this application. To match the environment present within the combustion chamber, tSOFCs must be turned inside-out yielding novel geometry internal cathode-tSFOCs (IC-tSOFCs).

IC-tSOFC development has revealed a wide variety of unexpected and yet fascinating material phenomenon. One example is the unique stress distribution present in these cells during sintering which ultimately leads to cracking. Another is the effect of the exothermic reaction of water formation at the anode which raises cell surface temperatures much higher than that of the environment, to the point of melting metal contacts. These behaviors, though cumbersome, motivate investigation into fundamental ceramic material behavior and ultimately adoption of new techniques to better control ceramic processing.
Thermo-Mechanical Stresses in the Design and Analysis of Thick-Walled Pressure Vessels
Authors: Mohammadzadeh AliReza , Haidar Salim M.
Published: January 2022

In design and analysis of mechanical and structural components, stresses due to the existence of temperature field in the part cannot be overlooked. In some practical cases, thermal stresses make a significant portion of total stresses.

In undergraduate stress analysis courses, the topic of thermal stresses is covered only in cases of uniform temperature rise and in presence of mechanical loads [1], [2]. Stresses induced by means of temperature gradient alone and in the absence of any mechanical loads are completely ignored. Although coverage of thermal stresses is available in advanced textbooks [3, 4, 5, 6, 7], nevertheless, the level of coverage is beyond the scope of undergraduate students’ understanding.

To address this important aspect of stress analysis in our undergraduate curriculum, the authors developed a project in the design and analysis of a thick-walled pressure vessel subject to a high internal pressure and a stiff temperature gradient in the cylinder wall, and they assigned a version of it to the students in the senior level machine design class at their university. Students were teamed in groups of three and were given one month to come up with their stress analysis results and design decisions for choice of bolts selected to fasten the cylinder’s caps to its body. The goal of this paper is mainly to present the pedagogical approach of the stress analysis aspect of this project in the cylindrical portion far away from the cap ends.
Study on Tribological Behaviour of ZnO Nano Additives Suspended in SAE 20W-50 Engine Oil
Authors: Elsoudy Sherif , Akl Sayed , Abdel-Rehim Ahmed A. , Salem Serag
Published: January 2022

In internal combustion engines, significant power losses are directly related to the mechanical friction of engine parts. Therefore, controlling tribological performance for engine lubricants has a major role in limiting those losses. In this study, the tribological properties of traditional engine oil with nano ZnO and oleic acid (OA) as a surfactant have been analyzed. Three different concentrations of 0.2, 0.5 and 1 wt.% were investigated using a pin-on-disc tribometer, according to ASTM G-99 with boundary/mixed lubrication regimes. The generated friction and wear characteristics revealed a remarkable reduction in friction coefficient with a range of 8–10%. Analysis of SEM and EDX was conducted on the worn surfaces. Additionally, the colloidal stability of nano dispersion was performed through sedimentation, FTIR, and Zeta analyses.
Rapid Design and Analysis of Versatile Robotic Platform
Authors: Islam Ariful , Campbell Chad , Merrikin Christian , Duan Shawn
Published: January 2022

To accommodate the ever-expanding data warehouse market, it is necessary to implement a degree of industrial automation to meet maintenance requirements. With the expansion of cloud-based storage and many new and existing companies moving to automate their processes, the need for a more effective method to manage and maintain server warehouses with reduced manpower is necessary.

In order to address the need, this design team has developed and prototyped — a platform that would meet the basic requirements for server retrieval. The model navigates on four wheels driven by stepper motors that allow for differential steering and navigation in an indexed workspace. In order to reach servers on both the top and bottom bays, a chassis with low ground clearance was fitted with a scissor lift mechanism. The two sides of the scissor lift are actuated by two stepper motors with a high-ratio gear reduction.

The operating system for controls and sensors run on Robot Operating System (ROS) and are powered by a Raspberry Pi that can be remotely programmed and operated from a single network connected computer. For precise controllability of electromechanical devices, appropriately sized drivers and sensors were selected. A Simulink-based step response analysis of inrush current and torque was completed to aid in component selection. This computer-based simulation resulted in important data regarding transient and steady state dynamics of the electromechanical system. This information can be ultimately used to design a PI, PD, or PID controller to eliminate steady state and transient state error from the actual robot, ensuring precise control.

Analysis was centered primarily on the lifting, driving, and control mechanisms. The structure of each system was analyzed to ensure proper dimensioning and material selection. At the same time, the mechatronic analysis was completed to ensure lifting requirements were met. Analysis was conducted on the motor shafts, scissor members, gears, and hardware resulting in a robust design. All of the physical parts were initially modeled to meet a minimum safety-factor and were later modified based on the results of finite element analysis studies. This approach will allow the robot to operate safely and effectively regardless of obstruction or human interference.

The design and programming enable a single technician to manage a fleet of robots for large scale operations. Because of the simplicity of the robot, the mechanisms and electronics selected can be modified to accommodate specific customer needs. This electromechanical platform and electrical simulation serve as a basis for future research and development of autonomous data warehouse maintenance.
Integrated System Architecture Development Framework and Complexity Assessment
Authors: Dalvi Akshay S. , El-Mounayri Hazim
Published: January 2022

Systems engineering is the popular top-down systematic approach to understand and develop complex systems. There is a gap between the systems engineering activities and engineering analysis in major system development processes. This paper presents an integrated MBSE development framework with definite and indefinite modeling capabilities to bridge this gap. The framework uses SysML, a system modeling language, to describe its elements from the system architecture’s perspective. A detailed workflow is presented that guides the engineer throughout the modeling process. The workflow establishes traceability throughout the framework. This research uses Functional Mock-up Interface (FMI) standards to integrate system engineering activities and engineering analysis. A district cooling system case study is presented to demonstrate the framework’s capabilities in enabling the system into existence. The system architecture model was developed using SysML language in the Cameo Enterprise Architecture environment. The engineering analysis model used object-oriented Modelica language in the Dymola environment. The analysis results show that the district chiller model developed using Modelica produces chilled water below 6.6 degrees Celsius, satisfying the district chiller’s system requirement. The exponential trend in the system architecture’s complexity pattern is measured and analyzed using complexity assessment techniques. The results show that the structural complexity of the system increases steadily from 2.7080 to 8.1241. However, the behavioral complexity increases drastically from 1.7915 to 59.2686 in the problem domain.
Three-Dimensional Computational Fluid Dynamics Modeling of a 6V150 Diesel Engine
Authors: Liu Zhentao , Zhang Yu , Fu Jiahong , Liu Jinlong
Published: January 2022

Three dimensional (3D) computational fluid dynamics (CFD) engine simulations can guide and/or complement experimental investigations and provide in-cylinder details that cannot be captured by conventional data acquisition methods. The main objective of this study was to establish a 3D RANS model (i.e., reasonable computational cost and running time) that can predict the efficiency and emissions of a 6V150 diesel engine under different operating conditions. The sub-models include renormalized k-epsilon turbulence model, G-equation model, solid cone breakup model (including hybrid KH-RT model and gas jet model), two-step soot formation model, and etc. The model was validated with experimental data from dynamometer tests. The results indicated that the numerical model captured the combustion and emission characteristics that occurred inside the combustion chamber, demonstrating its capability to evaluate engine characteristics during the development and optimization process.
Development of a Digital Twin for Additive Manufacturing
Authors: Machado Michael , Oliveira Eduardo , Silva Leopoldo , Silva João , Sousa João
Published: January 2022

Since the first industrial revolution that companies have been looking to produce more, cheaper and better products. Nowadays, this quest has achieved a new dimension due to the high market competitiveness. Moreover, is also possible to notice an improvement of the quality standards associated with the manufacturing technologies. Both quests have increased demand for new production technologies that are more efficient and sustainable than the technologies they replace. Leading to a continuous need to develop new technologies, improve existing solutions or even merge existing technologies into a single process to reduce intermediate stages during production of new products, reducing the production time of the products.

In recent years, one of the production technologies that has seen a great increase in popularity, and therefore in new developments are the additive manufacturing (AM) processes. This increase in popularity is due to some major aspects, in first place is the fact that AM generates less raw material waste during production that traditional solutions, in some cases the raw material waste is almost zero. In the other hand it also allows for a greater flexibility and continuous change of the production design since it does require fewer, or even no tools, to assist the production, especially AM based on powder bed fusion (PBF).

From a macroscopic perspective, manufacturing technologies need to be able to produce faster, in a more dynamic way and ensuring the quality standards are maintained, represent the fundamental needs for any institution. In order to provide solutions to the previous desired form the industrial stakeholders have been developing the concept of the industry 4.0 and Internet of Things (IoT). These solutions allow for a constant communication between the machines, resulting in a more efficient and control production cycle. However, this objective represents an exhaustive task due to a great variety of problems, ranging from interoperability, communications issues to equipment compliance to data-driven paradigm.

To increase the implementation scope of this paper, will be provided some development and contribution in terms of information modelling in the additive manufacturing area. Therefore, will be analyzed the fundamental aspects for developing a digital twin of the optical system of a PBF machine. Moreover, will be applied the concept of a digital twin to the laser source and to the galvanometric scanner. This process is fundamental for integrating IoT information modelling into additive manufacturing solutions. In the other hand, it will be analyzed how technical information is generated during the process and how this data can be later used for developing a digital twin that is able to connect IoT devices integrating an AM system. After a more theorical analysis is preformed will be presented a simplified prototype unit to test the implementation of the proposed system.
Multi Response Optimization of Friction Stir Process Parameters on AA2024 / SiC Composite Fabricated Using Friction Stir Processing
Authors: Manickam Akash , Kuppusamy Raman , Jayaprakasham Sudha , Santhanam Senthil Kumar Velukkudi
Published: January 2022

Friction Stir processing is used to modify the mechanical properties of the metal by refining the grain structure, which is proven to be effective for selective surface modification and also retaining the properties of bulk. In this present work Aluminium Alloy 2024 is used as a matrix material, which possess poor corrosion resistance and the softness of the material leads to high wear rate. Silicon Carbide (SiC), which has high hardness, high corrosion resistance and withstands high temperature is used as the reinforcement material. The present work aims to enhance the mechanical properties by refining the grain structure, and improvement in the corrosion behavior of AA2024 through surface composite (AA2024/SiC) fabricated using FSP. The Aluminium Metal Matrix Composite is fabricated using Friction Stir Processing by varying the volume fraction of SiC, rotational speed and traverse speed. The process parameters used in this experiment are rotational speed of 1200 rpm, 1500 rpm & 1800 rpm, traverse speed of 44 mm/min, 60 mm/min & 72 mm/min and volume fractions 8%, 16% & 24% of SiC. The experiment is conducted using Taguchi’s L9 Orthogonal array considering three factors at three different levels. A square pin tool of H13 steel with hardness of 60 HRC is designed and fabricated to provide better material flow of the reinforcement particles. The Silicon Carbide (SiC) particulate reinforced Aluminium Metal Matrix Composite (MMC) has been successfully fabricated through single pass FSP.

The tensile test were carried out using universal testing machine as per ASTM E8 standards to determine the elongation and the ultimate tensile strength (UTS) of FSPed AA2024/SiC composites and the corrosion rate were evaluated using immersion corrosion testing method by weighing the before and after weights of the samples as per ASTM G31-72, 2004. Grey Relational Analysis (GRA) is performed on the multiple response test results to find the optimum friction stir process parameters. Analysis of Variance (ANOVA) is performed to determine the most significant contributing friction stir process parameters at a 95% confidence level.
Influence of In-Process Cryogenic Cooling on Mechanical Performance of Friction Stir T6 – AA 2900 Alloy Weldments
Authors: Ashwath P. , Anthony Xavior M. , Jeyapandiarajan P. , Joel J.
Published: January 2022

Al-Li-Cu alloy A12195-T84 is used extensively in the aerospace launch vehicle external fuel tank structures. Aerospace components are generally joined using aluminium alloy materials, which increases the overall payload capacity of the launch vehicle. In this context, friction stir welding (FSW) process could be a potential solution. In this research work, Al2900-T6 specimens hot extruded were welded by FSW, using different parametric combinations of tool rotation and welding speed. In process cryo cooling was employed to dissipate the heat generated during the FSW. Microstructure and mechanical properties of the weldments were examined for both in-process cryo cooling and normally cooled conditions. It was observed that the grain size of the nugget zone (NZ) got refined because of the in-process cryogenic cooling during FSW. It was also discovered that microhardness was more in case of in-process cryo-cooled weldments as compared to naturally cooled weldments. Micro-hardness of the NZ was observed to be highest due to formation of finer grains because of the in-process cryogenic cooling. In-process cryogenic cooling has also improved tensile properties such as yield strength and % elongation of the FSW weldments.
Experimental Measurement of CID- and Vent-Activation in Cylindrical Lithium-Ion Batteries
Authors: Li Weisi , Crompton K. R. , Ostanek Jason
Published: January 2022

Two pressure-activated safety devices, a current interrupt device (CID) and a vent mechanism, are commonly built into the cap structure of cylindrical 18650 lithium-ion cells to isolate the cell electrically and relieve internal cell pressure prior to case rupture, respectively, in an abuse or thermal runaway event. The activation pressure for these two mechanisms, and how it varies with temperature, is an important parameter for the thermal runaway models incorporating electrolyte evaporation, gas generation and venting. This paper presents a method to extract the geometry of four commercial 18650 lithium-ion vent cap assemblies and measure the CID- and vent-activation pressures with a customized experimental setup. The experimental data were collected at ambient temperature and 100 °C. The CID-activation pressures of the MTI, LG MJ1, K2, and LG M36 caps were 1.058 ± 0.053, 1.293 ± 0.119, 0.997 ± 0.292 and 1.393 ± 0.113 MPa at ambient temperature and 0.920 ± 0.076, 1.066 ± 0.068, 0.834 ± 0.057 and 1.083 ± 0.077 MPa at 100°C, respectively. The vent-activation pressures of the MTI, LG MJ1, K2, and LG M36 caps were 2.308 ± 0.196, 2.202 ± 0.083, 2.190 ± 0.372 and 2.363 ± 0.199 MPa at ambient temperature and 1.919 ± 0.132, 1.866 ± 0.084, 1.781 ± 0.355 and 1.799 ± 0.284 MPa at 100°C, respectively. The experimental setup may be used in future studies to measure activation pressures of future cylindrical cells. The CAD model of the caps may be used to develop a finite element model (FEM) to simulate the CID- and vent-activation pressure and a computational fluid dynamics (CFD) model to design more reliable and effective CID and vent mechanisms.
Microfluidics-Based Fabrication of a Hele-Shaw Cell Device for Drop Coalescence Imaging
Authors: Emeigh Carson , Zhang Haipeng , Ryu Sangjin
Published: January 2022

The Hele-Shaw cell has been well used for various flow studies because it can simplify analyzing the flow of interest to two-dimensional creeping one. The Hele-Shaw cell consists of two parallel flat plates with a very small gap between them. When a working fluid is injected through this narrow gap, two-dimensional Stokes flow is generated with an extremely low Reynolds number and negligible flow velocity normal to the plates.

Applications of Hele-Shaw cell devices include experimental studies of drop coalescence, Stokes flow, and confining cells to a 2D plane, and they usually depend on cameras to capture phenomena of interest from the experiment. The quality of the collected images largely depends on the optical quality of the Hele-Shaw cell. Therefore, it is favorable to reduce the degree of light attenuation through Hele-Shaw cells.

Previously we fabricated a Hele-Shaw cell using polydimethylsiloxane (PDMS) and soft lithography, which are common in microfluidic fabrication, to study drop coalescence with high-speed imaging. It was found that the frame rate of high-speed imaging was limited by light intensity, which was affected by light attenuation through PDMS, and thus the very initial stage of the neck growth during coalescence was not captured. To overcome this limitation, an advanced fabrication method of the Hele-Shaw cell has been developed to incorporate a glass observation window in the PDMS part of the cell.

The previous and newly developed Hele-Shaw cell devices were compared in terms of local intensity and contrast, and improvement in image quality was confirmed. Our method has the following advantages. First, the thickness of the PDMS layers is controllable and thus the attenuation of light intensity can be reduced. Second, the glass-based observation window can enable clearer images with reduced image defects caused by PDMS. Therefore, the suggested microfluidics-based fabrication method of the Hele-Shaw cell has the potential to increase the resolution of high-speed imaging and to reduce the difficulty of post image processing.