bluuebunny/crossref_metadata_2025_split huggingface dataset:
Motion Synchronization of Multiple Hydraulic Actuators: A Linear Multivariable Approach
Authors: Sun Hong , Chiu George T.-C. 
Published: December 2021

Abstract
The electro-hydraulic (EH) synchronized motion of two linear ram type hydraulic actuators is considered in this paper. It is shown that the combined system of the load and the hydraulic actuators is unstable and requires additional mechanical and/or electronic synchronization. Two EH synchronization control methods, multivariable pole placement (MPP) and Linear Quadratic Integration (LQI), are presented based on a linearized multivariable model. It is shown that the synchronization error can be penalized implicitly or explicitly using multivariable control designs. Simulation results demonstrated that decoupled control as well as flow divider techniques can not adequately address the motion synchronization issue. Both multivariable control approaches showed significant improvement compared with individual controlled cylinders.
A Model for Conceptual Design Methodology
Authors: Condoor Sridhar S. , Weber Richard G. 
Published: December 2021

Abstract
Conceptual design is the seminal phase in the design process. This phase determines the level of product innovation, the efficiency of the product, and the effectiveness of the down-stream stages of the design process. It has tremendous leverage on the final product performance, cost, and time-to-market. To improve the efficiency of the conceptual design process, the paper combines the parameter analysis methodology with a fundamental insight from robust design. Parameter analysis is a generic design methodology that aids in systematically developing an idea into a viable design. It is particularly useful in creating innovative conceptual designs. Robust design is, often, used after finalizing the conceptual design. Robust design improves the product quality by first reducing the variability in product performance and then, tuning the low variability performance onto the target. The paper presents guidelines for executing the parameter analysis methodology which in turn provides consistent or low variability performance by considering robustness in the very early phases of the design process. The paper illustrates this process with two case studies. The case studies also show how to qualitatively optimize a conceptual design by developing the overall concept before details.
Concurrent Cost Calculations With a Feature-Based CAD System
Authors: Leibi Peter , Hoehne Guenther , Hundal Mahendra 
Published: December 2021

Abstract
The paper describes a procedure for calculating costs concurrent with the design process. The different modules of the computer program “IKF” are described. The modules include those for cost calculation, comparison and forecast. Form features are used for cost determination by classifying each feature and storing it in the detailed production plan. The production processes then follow from the list of stored features. The cost program takes the individual geometric data, e.g., part length, from the CAD program. The latter contains data sets, that describe the feature’s dimensions. The production time for the form feature is then calculated. From the time expenditures and the machine rates the program calculates the production costs for the given feature. Prior to developing the computer program a manual procedure was designed and developed. Upon testing, the group not using IKF took 40–50% more time and designed products that were about 80% costlier than the group using the IKF system. This procedure was then used as the model for the cost modules in a feature-based CAD program. Test cases dealing with sheet-metal design are described which demonstrate and quantify the advantages of this system.
Some Limitations of TRIZ Tools and Possible Ways of Improvement
Authors: Kosse V. 
Published: December 2021

Abstract
The Ideation/TRIZ Methodology has grown into the most powerful engineering problem solving methodology. However, experienced users may discover some limitations of TRIZ tolls, such as empty cells in the Contradiction Matrix, missing physical effects in the library of physical effects. In this paper possible ways of improvement of the Contradiction Matrix as well as special physical effects to complement the list of physical effects and phenomena are discussed.
An Analytical-Experimental Study for the Determination of the Effective Thermal Conductivity of High Porosity Fibrous Foams
Authors: Bhattacharya Anandaroop , Calmidi Varaprasad V. , Mahajan Roop L. 
Published: December 2021

Abstract
In this paper, we present a comprehensive analysis for estimating the effective thermal conductivity of high porosity fibrous foams. Commercially available fibrous foams form a complex array of interconnected fibers with an irregular lump of metal at the intersection of two fibers. In our theoretical analysis, we represent this structure by a model consisting of two-dimensional hexagonal arrays where the fibers form the sides of the hexagons. The lump is taken into account by considering a square, hexagonal or circular blob of metal at the intersection. The analysis shows that the effective thermal conductivity of the foam depends strongly on the porosity and the ratio of the cross-sections of the fiber and the intersection. It has no systematic dependence on pore density. Further, the choice of the geometric configuration of the intersection affects the estimate of the effective thermal conductivity. Experimental data with aluminum and Reticulated Vitreous Carbon (RVC) foams, using air and water as fluid media are used to validate the analytical predictions. Finally, the experimental results are used to arrive at a simple, closed-form empirical correlation for estimating the effective thermal conductivity in terms of the porosity, and the solid and fluid conductivities.
Solar Radiation Thruster Performance Analysis With Energy Storage in Porous Material
Authors: Chen Yen-Sen , Liu Jiwen , Wei Hong 
Published: December 2021

Abstract
The objective of this study is to develop analytical codes to support the design effort of the Shooting Star Flight Experiment’s rocket engine. Numerical models can augment the design effort by providing insight into fluid dynamics issues. Then, the design team can utilize the developed code to assess the design parameters and the engine performance as well as other issues related to thermal propulsion. The physical models developed in this study are: (a) a radiation model based on a GRASP code for general multi-block curvilinear coordinates and with a time accurate Crank-Nicholson marching scheme for heat conduction to model the absorber component of the engine; and (b) a fluid dynamics computational model using the Navier-Stokes equations, porosity factors and drag forces terms for simple one-dimensional simulations to complete three-dimensional modeling of the Shooting Star Engine internal flows.
Transient Temperature Computation of Spheres in Packings With Multi-Neighbors
Authors: Siu W. W. M. , Lee S. H.-K. 
Published: December 2021

Abstract
Packed sphere systems commonly involve heat transfer processes, such as catalytic beds and insulations. Most of the time, these types of systems were considered as porous media. In fact, porous medium approach has been successfully used for application involving considerable amount of spheres with corresponding resolution and, typically in geothermal system study. In recently years, researchers have started to investigate the problem in a finer length scale formulation because of the relevant application requirement, such as powder sintering processes. Using thermal constriction resistance for solving transient temperature of individual sphere in a packing was one of the attempt to achieve the finer resolution of temperature. It has been found that a special formulation is required in order to take care the finite heat diffusion mechanism between spheres. However, available correlations and governing equations from literature were only applicable for spheres with two neighbors. It is obviously not sufficient for solving temperatures of spheres within realistic packing. Furthermore, the interaction of the finite diffusion amoung spheres should be more complicated in three dimensional packing situation. Therefore, this work focuses on the enhancement of the approach of using constriction resistance for realistic packing of spheres. The formulation of the governing equation with the consideration of multi-neighbor arrangement was performed. A finite difference code was developed and using for solving the governing equation. It has been verified to be applicable to multi-neighbor situation few regular packing situations. Computation of sphere temperatures of a packing involving a thousand of spheres was also performed for illustrating the application.
Microscale Permeability Predictions of Porous Fibrous Media
Authors: Ngo Nam D. , Tamma Kumar K. 
Published: December 2021

Abstract
A good understanding of woven fiber preform permeabilities is critical in the design and optimization of the composite molding processes, yet these issues remain unresolved in the literature. Many have attempted to address permeability predictions for flat undeformed fiber preform, but few have investigated permeability variations for complex three-dimensional molds. In this study, the objectives are to: (i) first provide a brief review of existing methods for the prediction of the fiber mat permeability; (ii) postulate a more realistic representation of a unit cell to account for such fabric structures as crimp, tow spacing and the like; and (iii) apply computational approximations for predicting effective permeabilities for use in the modeling of structural composites processes. The Stokes equation is used to model the flow in the inter-tow region of the unit cell, and in the intra-tow region, the Brinkman’s equation is used. Preliminary permeability prediction calculations are performed for a three-dimensional unit cell model representative of PET 61 woven fabric. The results showed good agreement with experimental data published in literature.
Non-Isothermal “2-D Flow/3-D Thermal” Developments Encompassing Process Modeling of Composites: Flow/Thermal/Cure Formulations and Validations
Authors: Ngo Nam D. , Tamma Kumar K. 
Published: December 2021

Abstract
In the manufacturing process of large geometrically complex components comprising of fiber-reinforced composite materials by Resin Transfer Molding (RTM), the process involves injection of resin into a mold cavity filled with porous fiber preforms. The overall success of the RTM manufacturing process depends on the complete impregnation of the fiber mat by the polymer resin, prevention of polymer gelation during filling, and subsequent avoidance of dry spots. Since a cold resin is injected into a hot mold, the associated physics encompasses a moving boundary value problem in conjunction with the multi-disciplinary study of flow/thermal and cure inside the mold cavity. Although experimental validations are indispensable, routine manufacture of large complex structural geometries can only be enhanced via computational simulations, thus eliminating costly trial runs and helping the designer in the set-up of the manufacturing process. This study describes the developments towards formulating an effective simulation based design methodology using the finite element method. The specific application is for thin shell-like geometries with thickness being much smaller than the other dimensions of the part. Due to the highly advective nature of the non-isothermal conditions involving thermal and polymerization reactions, special computational considerations and stabilization techniques are also proposed. Validations and comparisons with experimental results are presented whenever available.
Mesoscale Machines and Electronics: “There’s Plenty of Room in the Middle”
Authors: Warren William L. , Dubois Lawrence H. , Wax Steven G. , Gardos Michael N. , Fehrenbacher Lawrence L. 
Published: December 2021

Abstract
Machine properties optimized in the mesoscale size regime include improved heat transfer, macroscopic electrostatic actuation, and chemical mixing. This manuscript describes the origin of these advantages along with the development of several energy-efficient meso-machines that exploit these properties. The advantages of direct-write mesoscale electronics are also presented. These include the ability to place the electronics on the physical structure of a machine to improve performance, reduce size and weight, and enhance durability.
State-of-the-Art in Micro- and Meso-Scale Heat Exchangers
Authors: Shekarriz Reza , Call Charles J. 
Published: December 2021

Abstract
A review of the literature and the state-of-the-art in research and development of miniature heat exchangers is presented in this paper. The authors provide a discussion of what makes the micro- and meso-scales important, highlight the design constraints and challenges that surface when miniaturizing a heat exchanger, and outline and discuss the outstanding practical and scientific issues in this area. Finally, the most recent advances in manufacturing processes and application of these miniature heat exchangers are covered in this article.
Integrated Mesoscopic Cooler Circuits (IMCCs)
Authors: Shannon Mark A. , Philpott Mike L. , Miller Norman R. , Bullard Clark W. , Beebe David J. , Jacobi Anthony M. , Hrnjak Predag S. , Saif Taher , Aluru Narayan , Sehitoglu Huseyin , Rockett Angus , Economy James 
Published: December 2021

Abstract
This paper presents the design, fabrication approach, and initial results on the development of an active composite fabric comprising a system of energy-efficient micro-miniature vapor-compression heat pumps to form integrated mesoscopic cooler circuits (IMCCs). Wafer-scale microfabrication, traditional volume processes such as injection molding, and new layered fabrication techniques have been combined with a scale-efficient vapor-compression cycle. The resulting IMCC offers significant improvements in cooling efficiency over normal-scale refrigeration. The flexible polymer-based IMCC patches may be interconnected to form distributed fault-tolerant refrigeration circuits for a wide variety of applications. Potential applications include microclimate control for military, space, and fire fighting personnel, on-board/chip cooling of electronic devices, medical applications requiring highly localized and/or efficient temperature control, and automotive comfort control devices.
The Use of a Psychrometric Chart in the Absorption-Evaporative Cooling Refrigerator
Authors: Morales G. Juan R. , Lara V. Araceli , Lizardi R. Arturo , López C. Raymundo , Díaz C. Alen 
Published: December 2021

Abstract
In the absorption-evaporative cooling refrigerator, the evaporator works with liquid butane and a gaseous ammonia-butane mixture. In order to design such a refrigerator the mixture behavior has to be known. In this paper such behavior is determined first considering an ideal gases mixture and no ammonia in the liquid butane. For this purpose a psychrometric chart for a pressure of 105 kPa is obtained. To validate these assumptions a second model is chosen that considers a certain amount of non-ideality. The selected model is represented by the equations of Peng-Robinson. The results obtained for the equilibrium conditions are compared with the 100% relative humidity of the psychrometric chart. A satisfactory agreement is found.
A Latching Mechanism for Unloading a Rotary Compressor
Authors: Smith Joseph L. , Webb Michael D. , Umans Stephen D. 
Published: December 2021

Abstract
A vane latching mechanism for unloading a rotary vane compressor is described. Mechanical unloading is proposed as a potential alternative to electronic control of motor speed for variable compressor capacity. Performance of a demonstration compressor operating at part capacity in a residential air conditioning system is described.
Profile Generation and Analysis for Twin Screw Multiphase Compressor/Pump
Authors: Cao Feng , Xing Ziwen , Peng Xueyuan , Shu Pengcheng 
Published: December 2021

Abstract
Multiphase transportation technology enables to transfer the mixture of crude oil, gas, water and sand in a single pipeline. Compared to the conventional method, it is more efficient since the multi-pipelines are not required.
Multiphase compressor is the key machine in a multiphase transportation system, and the twin screw multiphase compressor/pump has proved to be a suitable machine for this application. This paper investigates the twin screw multiphase compressor, mainly focusing on the rotor profile. The calculating methods for mesh line length and blow hole area between the two rotors are presented. The geometrical characteristics of the rotor profile are also discussed in the paper.
Modeling and Analysis of the Air Cooled Ammonia-Water Triple Effect Cycle
Authors: Shelton Sam V. , Jacob David , Schaefer Laura A. 
Published: December 2021

Abstract
Development of air-cooled absorption cycles appropriate for residential applications has been problematic. This study examines an ammonia-water triple effect cycle known as the kangaroo cycle, and investigates its limitations when used as an air-cooled space air conditioner. The triple effect absorption processes were modeled and a methodology for optimizing the design was developed. The arrangement and relative sizes of the heat exchangers thermally coupling the upper and lower loops were studied. The thermal coupling involves the upper rectifier, condenser, and absorber rejecting heat to the lower generator. Contrary to other triple effect studies, internal generator heat exchangers were incorporated in both the upper and lower generators and their optimum relative positions were studied. Also, errors of up to 150 percent were shown to result from conventional LMTD and pinch point analysis due to the highly non-linear temperature-enthalpy relationship in the upper condenser. Three configurations for the upper heat exchangers coupling the upper loop to the lower generator were analyzed, and their relative sizes were optimized. The cycle’s performance was shown to depend on the exit temperature of the lower loop generator, and the COP optimization was demonstrated with respect to this design variable. Operation at air-cooled ambient conditions was investigated. At lower ambient temperatures that are heavily weighted in air conditioning rating standards, the efficiency is very favorable. Equipment development and cost issues need to be addressed.
Modeling an Integral Dual Solar/Gas Fired Generator for a Water-Lithium Bromide Absorption Chiller
Authors: Cao Jiming , Christensen Richard N. 
Published: December 2021

Abstract
This paper presents a design process for a dual solar/gas fired generator. A generator fired by solar energy and/or natural gas for a water-lithium bromide absorption chiller of 25 refrigeration tons (RT) was modeled. The natural gas is considered as the backup heat when the solar energy is unavailable or insufficient. The flue gas and the water-lithium bromide solution are in co-current flow, while the solar fluid and the water-lithium bromide solution are in counter-current flow. Fifty fluted tubes were installed vertically between two concentric cylindrical tubes. A solid ceramic insert was used to enhance heat transfer on the gas side that is considered as having the dominant heat transfer resistance. The burner is installed inside the smaller cylindrical tube. The solar fluid from the solar collector enters the generator through the fluted tubes while the water-lithium bromide mixture flows in the annular channel around the fluted tubes as a subcooled liquid. The generator is divided into two regions according to the heat transfer mechanism: subcooled liquid region and desorption region. In this model, a simultaneous solar and gas fired desorption process was investigated. The amount of makeup heat needed from natural gas was determined as a function of the solar fluid flow rate. Local temperature profiles were predicted by the model.
The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption
Authors: Miller William A. , Keyhani Majid 
Published: December 2021

Abstract
Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for comfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to be one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller’s capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller.
The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.
Experiments were conducted on an internally cooled smooth tube 0.01905 m in outside diameter and 1.53 m in length. Tests were conducted with no heat and mass transfer additive. The data, for testing at 0.62 and 0.64 mass fraction of LiBr, were scaled and correlated into both Nusselt (Nu) and Sherwood (Sh) formulations. The average absolute error in the Nusselt correlation is about ±3.5% of the Nu number reduced from the experimental data. The Sherwood correlation is about ±5% of the reduced Sh data. Data from the open literature were reduced to the authors’ Nu and Sh formulations and were within 5% of the correlations developed in the present study. Hence, this study provides correlations for the complex heat and mass transfer process that is validated against extensive experimental data. The study therefore contains useful information for the design of a vertical column absorber operating with no heat and mass transfer additive.
Theory of Heat/Mass Transfer Additives in Absorption Chillers
Authors: Kulankara S. , Verma S. , Herold K. E. 
Published: December 2021

Abstract
A new theory is presented, termed the vapor surfactant theory, which explains the heat and mass transfer enhancement mechanism of additives in absorption chillers. The vapor surfactant theory holds that the enhancement additives are surfactants delivered to the surface of the solution film from the vapor and that they produce enhancement by generating intense secondary flows on the film. The secondary flows, driven by surface tension gradients (Marangoni convection), augment the transfer process by providing mixing of the film. The primary variable in the enhancement is the surface concentration distribution of the surfactant additive since the surface tension gradients arise due to non-uniformities in the surface concentration. The vapor surfactant theory is found to explain all observations from several different types of experiments. The new theory is a significant departure from past theories in its emphasis on the primary role of the vapor in the process.