bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Density Computing: Efficient Versus Conventional Design
Authors: Comperchio Dan , Behere Sameer 
Published: March 2016

Data centers are expensive to build and operate. Large data centers cost $9–13/W to build [1] and can consume more than forty times, and up to over two hundred times, the amount of energy and resources consumed by a typical building [2], [3]. Therefore, space and energy considerations need to be accounted for when evaluating competing designs for high-performance computing (HPC) installations.
This paper describes the results of an incremental cost and energy savings analysis conducted using data collected from a real-world case study to evaluate the impacts of efficient resource planning and implementing a total cost of ownership (TCO) model in the analysis of IT equipment and systems. The analysis presented demonstrates the advantages of using the latest technologies and IT strategies when planning the growth of new HPC installations at an enterprise level. The data also indicates an efficient design can significantly reduce the space, power, and cooling requirements of the HPC deployment while maintaining the performance and reliability criteria.
Accelerations and Jerks Associated With Shaken Baby Syndrome
Authors: Akpinar Seyda , Saboori Parisa , Walker Graham 
Published: March 2016

Shaken Baby Syndrome is a collection of injuries that have been associated with the violent shaking of an infant or small child. These injuries can then lead to serious brain damage or even death. It is therefore important to identify the exact mechanism that leads from the shaking to the observed injuries, but little experimental work has been done in this area.
The first part of this study was designed to identify if a correlation exists between the physical characteristics of a person shaking a crash test dummy (CRABI) and the resulting accelerations and jerks associated with the motion of the dummy’s head. This was done by placing a three axis accelerometer in the head and two in the body (one in the chest and one in the groin) of a median twelve month old male dummy to determine the acceleration of the head and body. In particular, the relative angular acceleration and jerk of the head relative to the body was determined, since it was felt to be a better predictor of brain damage than would be the absolute linear acceleration of the head.
Similar work has been done in the past; however that study only considered the absolute acceleration of the head, and in only one direction. Since the present study allows the attitude of the head to be determined, a true relative angular acceleration of the head relative to the body was found. Consequently, it was found that no strong correlation existed between the absolute linear acceleration and any body characteristic, however a correlation (R2) of 0.6 was found to exist between the body weight of the shaker and the maximum angular jerk of the dummy’s head relative to its body, as compared to only a correlation of 0.5 when the shaker’s body weight was compared to the absolute linear acceleration of the head.
A two dimensional dynamic simulation was also developed that modelled the behavior of a child crash test dummy. The model included the legs, torso, and head of the dummy, and the elastic behavior of the neck. The model was created to allow the associated accelerations and jerks to be determined for inputs of various magnitude and temporal profiles. The model was then validated by comparing the simulation results to the test results obtained from the experimental study described above.
Application of Microscale Devices for Megawatt Scale Concentrating Solar Power Plants
Authors: Zada Kyle R. , Drost M. Kevin , Fronk Brian M. 
Published: March 2016

Concentrated solar power (CSP) plants have the potential to reduce the consumption of non-renewable resources and greenhouse gas emissions in electricity production. In CSP systems, a field of heliostats focuses solar radiation on a central receiver, which is ultimately transferred to thermal electrical power plant at high temperature. However, the maximum receiver surface fluxes are low (30–100 W cm−2) with high thermal losses, which has limited the market penetration of CSP systems.
Recently, small (∼ 4 cm2), laminated micro-channel devices have shown potential to achieve concentrated surface fluxes over 100 W cm−2 using supercritical CO2 as the working fluid. The present study explores the feasibility of using these microscale devices as building blocks for a megawatt scale (250 MW thermal) open solar receiver. This allows for a modular design of the central receiver with non-standard shapes customized to the heliostat field. The results show that the microscale unit-cells have the potential to be scaled to megawatt applications while providing high heat flux and thermal efficiency. At the design incident flux and surface emissivity, a global receiver thermal efficiency of > 90% can be achieved.
Enhancement of an Optimization-Based Damage Detection Technique
Authors: Yang Chulho , Chang Young Bae , Sa Jongsung , Park Junyoung 
Published: March 2016

Various structural health monitoring (SHM) techniques utilizing vibration signals have been developed for identification of damages in a structure. Many of these studies are based on sensitivity analysis, finite element model (FEM) updating, and optimization techniques. FEM updating technique is one of the major techniques that iteratively minimizes the difference between the modal parameters measured from the real structure and the corresponding analytical predictions. This method would be more beneficial for typical continuous systems such as beams, plates, and shells which cannot be reasonably discretized. One of the drawbacks of these techniques is the large number of unknowns to be estimated. These techniques in the literature that use FEM updating to estimate perturbed parameters for all elements in the model can be time-consuming and ill-conditioned, even for relatively simple structures. The technique also requires a full and accurate finite element model for each monitored structure.
A new method to identify damages in a structure using embedded sensitivity functions and optimization algorithms is described and its performance is demonstrated in this paper. The perturbed frequency response function (FRF) is calculated using Taylor series expansion in terms of the baseline system and the embedded sensitivity functions. The optimization process minimizes the difference between the measured FRFs of the damaged structure and the perturbed FRFs calculated from the baseline structure. Structural damages are often characterized by changes in mechanical parameters such as stiffness, mass, and damping. Embedded sensitivity functions offer a means of determining the path that is followed from the baseline to the perturbed FRF of the structure.
The robustness and efficiency of suggested structural health monitoring method are discussed in this paper. The accuracy of damage estimation is investigated with respect to various types and values of damages, objective functions, frequency ranges, scale factors, procedures, and noise levels. Precise measurement and monitoring of vibration signals are critical for accurate detection of the location, type, and level of damage. However, in most practical mechanical systems, vibration tests may result in noise on the input or output measurements. Noise on the measurement affects the accuracy of the FRFs and identification of damages in a structure. Based on the results of the study, several parameters and factors in the optimization process and structural dynamics are suggested to enhance the efficiency and robustness of damage identification process.
It is shown that the iteration number of the optimization process is significantly reduced. Accurate estimate of damages can be obtained within the range of 2∼5% error with various enhancements applied to the technique.
Analysis of Swirl Flow by Tube Inserts for CFD Study
Authors: Bouhairie Salem 
Published: March 2016

The petroleum and petrochemical industries continually seek mechanical methods to improve heat transfer in shell-and-tube heat exchangers. Tube bundle inserts are popular mechanical devices that help improve performance. The increase in the tubeside heat transfer coefficient by the insert allows for a decrease in required shellside flow length, assuming single tube pass. The flow length reduction allows for designing higher velocities and subsequent shellside shear rates, to help reduce crude oil fouling potential.
This work presents some of HTRI’s ongoing experimental measurements and preliminary Computational Fluid Dynamics (CFD) simulations. CFD visualization of swirl flow dynamics and heat transfer inside the augmented tube provides insight on complex flow physics, which is misunderstood.
Heat Transfer Research, Inc. (HTRI) collected experimental data for in-tube single-phase flow using twisted tape inserts in the Tubeside Single-Phase Unit (TSPU) situated in the Research and Technology Center (RTC). Our data will be used to calibrate ANSYS FLUENT CFD simulations of a tube with a twisted tape swirl insert. We first performed plain tube simulations and compared the heat transfer results with open literature measurements, for validation. We will modify the CFD tube model to have a swirl flow insert, and compare numerical results against open literature experimental data of diabatic single-phase swirl flow.
In future, we will compute heat transfer (heating and cooling) and pressure drop for tube insert configurations at laminar and turbulent Reynolds numbers from 3000 to 500000. The range of tubeside Reynolds numbers required the use of the laminar, transition, and Realizable k-epsilon turbulence models with scalable wall functions.
This study describes some of the mechanisms behind turbulent swirl flow augmentation inside a tube, as well as the limitations of conventional in-tube heat transfer correlations applied to swirl flow inserts.
Performance Analysis of Biologically Inspired Honeycomb Structured Heat Exchanger
Authors: Rahman Mosfequr , Iqbal Sakib , Calamas David 
Published: March 2016

The process of heat exchange between two fluids that are at different temperatures and separated by a solid wall occurs in many engineering applications. The device used to implement this exchange is termed a heat exchanger (HE), and specific applications may be found in space heating and air-conditioning, power generation, waste heat recovery, and chemical processing. Increasing heat transfer coefficient and making heat exchanger compact for various applications like in spacecraft, underwater vehicle, unmanned Ariel vehicle is one of the main challenges. Biologically-inspired design (or BID) has become an important and increasingly wide-spread movement in design for environmentally-conscious sustainable development. By definition, BID is based on cross-domain analogies; further, biologically-inspired approaches to design have a certain degree of openness to innovation. Compact heat exchanger can reduce the space and weight of any locomotives and spacecraft. Structural elements inspired from nature possess compactness and stability. Honeycomb structure allows minimize the spacing between cells which makes it possible to use thinnest possible metal boundary wall between two fluids. A rectangle structure can also do the same thing but it has less surface area, which will essentially decrease the volume of heat exchanger. Honeycomb structure provides high surface area to volume ratio which can be utilized to increase heat transfer coefficient of a heat exchanger and thus make compact system.
In this computational study, bio-inspired simple honeycomb structured and spiral finned honeycomb structured counter flow heat exchanger has been three dimensionally simulated using finite element methods in commercial software COMSOL. This work is used to reduce the weight of heat exchangers in steam reforming reactors. There is a good correlation when the fluid temperature is the same in all cells. There is also a good temperature gradient in the fluid owing to laminar flow. 3D modeling showed that a careful representation of the inlet is needed for realistic results. A tube-shell heat exchanger is also simulated using FEA in COMSOL. Spiral finned heat exchanger provides additional surface area in cost of pressure drop. The performance characteristics of honeycomb heat exchanger showed an increase in heat transfer rate with least vortex formation.
Multi-Objective Optimization of a Simplified Car Body Using Computational Fluid Dynamics
Authors: Bakshi Soham , Jawad Badih A. , Arslan Selin , Yee Kingman , Liu Liping 
Published: March 2016

Today’s strict fuel economy requirement produces the need for the cars to have really optimized shapes among other characteristics as optimized cooling packages, reduced weight, to name a few. With the advances in automotive technology, tight global oil resources, lightweight automotive design process becomes a problem deserving important consideration. It is not however always clear how to modify the shape of the exterior of a car in order to minimize its aerodynamic resistance. Air motion is complex and operates differently at different weather conditions. This gap can be covered by the use of adjoint solvers which predict the sensibility of the aerodynamic forces to changes of the geometry. Alternatively, Computational Fluid Dynamics (CFD) solvers can be partnered with optimization software which guide model design changes and evaluate the corresponding results. Design changes can be executed by modifying a parameterized geometry or using mesh morphing techniques. With the advances in computational fluid dynamics, design optimization methods in the aerodynamic design are more important than ever. In the present paper, ANSYS Fluent will be used in conjunction with the optimization software ANSYS DesignXplorer to study ways of reducing drag and lift for a simplified car body. ANSYS simulation software allows one to predict, with confidence, the impact of fluid flows on the product throughout design and manufacturing as well as during end use. CFD is a complex technology involving strongly coupled non-linear partial differential equations which attempt to computationally simulate theoretical and experimental models in a discrete domain of complex geometric shape. A detailed assessment of errors and uncertainties has to concern itself with the three roots of CFD: theory, experiment, and computation. Further, the application of CFD is rapidly expanding with the growth in computational resources. The body in question in this study is the Ahmed body [1] which has been used numerous times for CFD code validation. This geometry represents a road legal car which is used to study the effect of different forces like, aerodynamic drag force, lift force, and some other major forces which affect a car’s motion significantly. Despite being a simple body, accurate prediction of its aerodynamic performance often requires very accurate and computationally expensive calculations. We would like to investigate if meaningful optimizations can be achieved by using reduced resources, by analyzing how air at different velocity affect the body and what changes might be necessary for a further optimized performance.
The purpose here is not to predict the absolute values of drag for this body, but to demonstrate that optimization can be performed with limited resources relying on information about drag deltas rather than absolute values. Keeping limiting resources in mind, a grid independence study wasn’t done.
An Integrated Approach to the Planning of Manual Assembly Lines
Authors: Pintzos George , Matsas Markos , Triantafyllou Christos , Papakostas Nikolaos , Chryssolouris George 
Published: March 2016

Manual assembly planning methodologies have been in the center of industrial and academic research for many decades, since the manual assembly costs may often account for even half of the total manufacturing expenses. The existing and emerging manufacturing trends, such as mass customization and personalization, require fast responses when it comes to the conception and realization of the relevant manufacturing systems. Even though, work methodologies, such as concurrent engineering, have been proposed and applied, gaps still exist among product development, configuration and manufacturing. The Current Product Lifecycle (PLM) systems focus on the coordination of activities among engineers of different disciplines. However, they are unable to provide actual decision support functionality to decision makers. Moreover, solutions for the different phases of assembly planning have been proposed, without nevertheless taking into account the holistic nature of assembly planning that spans the different engineering phases.
The study presented in this paper is based on a methodology that integrates three distinct steps, regarding assembly planning; the generation of assembly related information, from the Computer Aided Design (CAD) files of an assembly, the calculation of the relevant process times from functions, generated through empirical measurements and the assembly line balancing of a line, based on the information gathered. The innovative aspect of this approach relies on the advancement of the relevant technologies as well as on their integration into a common working practice. The methodology enables the estimation of production related values in the later phases of product design or in the early phases of manufacturing planning. The generation of assembly precedence diagrams is made in an automatic way through the extraction of information on collision detection and the parts’ relations. This application is developed in the form of an add-on to a commercial CAD software suite. It utilizes features that are available in a wide range of such systems. The second step relies on the identification of specific features of parts, such as dimensions and mass. This information is then used as input in the functions already proposed in the academic literature for the estimation of the relevant process times for each part. Finally, the assembly line balancing is performed through the generation of the precedence diagram and the estimated process times, via a web-based service, which makes use of advanced optimization techniques.
In order for this methodology to be evaluated, a case study is presented by using the CAD file of an automotive sub-assembly. The case study demonstrates each step separately, beginning with the generation of the precedence diagram down to the balancing of the assembly line.
A Numerical Study of the Unsteady Flow Field and Tonal Hydrodynamic Sound of a Centrifugal Pump
Authors: Cai Jian-Cheng , Pan Jie , Guzzomi Andrew 
Published: March 2016

In this paper, the 3-D unsteady turbulent flow inside a centrifugal pump is investigated by computational fluid dynamics (CFD) in ANSYS CFX, using Detached Eddy Simulation (DES) as the turbulence approach. The pump has a single end-suction and a single volute discharge. The impeller is semi-open (unshrouded with baseplate) and has five backswept blades and pump-out back blades. The CFD model of the pump consists of the inlet, the impeller, and the volute. A sliding mesh technique has been applied to the interfaces in order to allow unsteady interactions between the rotating impeller and the stationary parts. These unsteady interactions generate pressure fluctuations over the volute casing and blade surfaces that are hydroacoustic dipoles according to Lighthill’s acoustic analogy theory. The pressure fluctuation spectra at the volute tongue show that pressure fluctuations are generated mainly by the discrete components related to the impeller rotation at low frequencies, especially the blade-passing frequency (BPF) component. This component is approximately 1% of the reference dynamic pressure 0.5ρν22 where ν2 is the circumferential velocity at the impeller outlet. The discrete components with frequency larger than 4 times BPF are no longer obvious in the spectra. Compared to the experimental results, the CFD simulation predicts much lower amplitudes for the broad band pressure fluctuations. This is reasonable, because DES combines a classical Reynolds averaged Navier Stokes (RANS) simulation with elements of Large Eddy Simulation (LES), and both RANS and LES use average methods which filter out the high frequency fluctuations. Nevertheless, CFD is capable of accurately predict the BPF component.
The pressure fluctuations on the casing and blade surfaces are extracted and modelled as the stationary and rotary dipoles, respectively, according to the Ffowcs Williams and Hawkings (FW-H) equation of the acoustic analogy theory. After Fast Fourier Transform, the spectra of the pressure fluctuations are obtained, and are used to predict the tonal hydrodynamic sound radiation at BPF and its low order harmonics. The sound radiation of casing surface dipoles is calculated by extracting the tonal components, and performing a surface integration with the fundamental solution to Helmholtz equation as the kernel. A frequency domain formulation of the FW-H equation with the moving surface dipole is employed to predict the tonal blade noise. The results from these acoustical simulations show that the sound power generated by the casing surface dipole is three orders of magnitude higher than that of the blade surface dipole, and the main hydroacoustic sources are located at the volute tongue.
Application of Advanced Model of Zr-Based Cladding Oxidation in Steam-Oxygen-Nitrogen Gas Mixtures to Separate Effects Tests and Integral Experiments
Authors: Vasiliev Alexander 
Published: March 2016

During postulated design-basis or beyond-design-basis accident at nuclear power plant with PWR or BWR, the high temperature oxidation of Zr-based fuel claddings in H2O-O2-N2 gas atmosphere could take place.
Recent experimental observations showed that the oxidation of those claddings in the air (or, more generally, in oxygen-nitrogen and steam-nitrogen mixtures) behaves in much more aggressive way (linear or enhanced parabolic kinetics) compared to oxidation in pure steam (standard parabolic kinetics).
This is why an advanced model of Zr-based cladding oxidation was developed. For calculations of cladding oxidation in oxygen-nitrogen and steam-nitrogen mixtures, the effective oxygen diffusion coefficient in ZrO2+ZrN layer formed in cladding is used. The diffusion coefficient enhancement factor depends on ZrN content in ZrO2+ZrN layer.
A numerical scheme was realized to determine ZrO2+ZrN/α-Zr(O) and α-Zr(O)/β-Zr layers boundaries relocation and layers transformations in claddings.
The model was implemented to the SOCRAT best estimate computer modeling code. The SOCRAT code with advanced model of oxidation was successfully used for calculations of separate effects tests and air ingress integral experiments QUENCH-10, QUENCH-16 and PARAMETER-SF4.