bluuebunny/crossref_metadata_2025 huggingface dataset:
Phantom Battery Pack for Destructive Testing of Li-Ion Batteries
Authors: Francis Alex , Avdeev Ilya , Berceau Calvin , Martins Hugo Pires Lage , Steinbach Luke , Mursch Justin , Kanack Vincent
Published: February 2017

The objective of this study is to find a structural alternative to jellyroll in order to safely conduct experimental crash testing of lithium-ion battery packs in academic laboratory environment. A procedure for lateral impact experiments has been developed and conducted on cylindrical cells and phantom cells using a flat rigid drop cart in a custom-built impact test apparatus. The main component of a cylindrical cell, jellyroll, is a layered spiral structure which consists of thin layers of electrodes and separator material. We investigate various phantom materials — candidates to replace the layered jellyroll with a homogeneous anisotropic material. During our experimentation with various phantom cells, material properties and internal geometries of additively manufactured components such as in-fill pattern, density and voids were adjusted in order to develop accurate deformation response. The deformation of the phantom cell was characterized and compared after impact testing with the actual lithium-ion cells. The experimental results were also compared with explicit simulations (LS-DYNA). This work shows progress toward an accurate and safe experimental procedure for structural impact testing on the entire battery pack consisting of thousands of volatile cells. Understanding battery and battery pack structural response can influence design and improve safety of electric vehicles.
Numerical Study of Transport Membrane Condenser Heat Exchangers
Authors: Ghasemisahebi Esmaiil , Soleimanikutanaei Soheil , Lin Cheng-Xian , Wang Dexin
Published: February 2017

In this study tube bundle Transport Membrane Condenser (TMC) has been studied numerically. The tube walls of TMC based heat exchangers are made of a nano-porous material and has a high membrane selectivity which is able to extract condensate pure water from the flue gas in the presence of other non-condensable gases (i.e. CO2, O2 and N2). Low grade waste heat and water recovery using ceramic membrane, based on separation mechanism, is a promising technology which helps to increase the efficiency of boilers and gas or coal combustors. The effects of inclination angles of tube bundle, different flue gas velocities, and the mass flow rate of water and gas flue have been studied numerically on heat transfer, pressure drop and condensation rates. To assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions, a single phase multi-component model is used. ANSYS-FLUENT is used to simulate the heat and mass transfer inside TMC heat exchangers. The condensation model and related source/sink terms are implemented in the computational setups using appropriate User Defined Functions (UDFs).
The Critical Velocity With Minimum Momentum Change in Pushing a Droplet Through a Constriction Channel
Authors: Zhang Zhifeng , Zhao Xinpeng , Xu Jie , Chen Xiaolin
Published: February 2017

Models of squeezing a droplet through a constrictions have wide applications in nature and engineering. In the present research, we found the minimum impulse required (momentum change) to squeeze a droplet through at different velocities. Our theoretical work result in an analytical expression of the critical velocity with minimum impulse. At this expression, we found a force balance between the average surface tension and the dynamic pressure loss at the channel inlet and outlet. Finally, we also compared the analytical results with numerical simulations. These results are important to understand some biological process and design of microscale filters.
Experimental Characterization of Low Velocity Impact Energy Dissipation in Sandwich Composites With Porous Cores With Tailored Structure and Morphology
Authors: Lane Kerry V. , Yasuda Nathan K. , Lo Michael E. , Mather Emily R. , Shih Frank J.
Published: February 2017

The impact performance of several porous polymeric and metallic foam core sandwich composite systems were evaluated for their suitability for protecting vehicle occupants in the event of a low velocity impact. The material systems evaluated were glass/phenolic face sheets reinforced with Nomax honeycomb core, cross-ply carbon-fiber face sheets reinforced with aluminum honeycomb cores of different cell sizes, and aluminum metallic foam cores of different cell sizes. Lastly, an exploratory study using an extrusion type 3D-printed polystyrene foam structure that customized pore size, pore distribution were undertaken. The peak load and energy dissipation of the composite materials were experimentally measured. An instrumented large semispherical impactor (48 mm diameter) applied loads at constant strain rate on the order of 0.1 m/sec to a 50 mm × 50 mm coupon sized composite specimen with varying thicknesses. The impact damage to materials were also visually examined. The current material system used for some interior components (glass/phenolic face sheets reinforced with Nomax honeycomb core) reaches a maximum load in a small time duration and displacement, causing catastrophic local crushing and delamination events. It is expected that the failure can be spread out with these alternative material systems with varying pore size distribution so that the energy dissipation can be accomplished with a lower peak force to improve occupant safety.
Chaos Analysis and Control in Fractional Order Systems Using Fractional Chebyshev Collocation Method
Authors: Dabiri Arman , Nazari Morad , Butcher Eric A.
Published: February 2017

In this paper, fractional Chebyshev collocation method is proposed to study Lyapunov exponents (LEs) and chaos in a fractional order system with nonlinearities. For this purpose, the solution of the fractional order system is discretized by N-degree Gauss-Lobatto-Chebyshev (GLC) polynomials where N is an integer number. Then, the discrete orthogonality relationship for the Chebyshev polynomials is used to obtain the fractional Chebyshev differentiation matrix. The differentiation matrix is then used to convert the nonlinear fractional differential equations to a system of nonlinear algebraic equations with the collocation points as the unknowns. The dominant LE (other than the zero LE) that corresponds to the time dimension is then computed by measuring the exponential rate of the trajectory deviations initiated slightly off the attractor point. The proposed technique is implemented to a damped driven pendulum with fractional order damping and the convergence of the dominant LE is studied versus the number of Chebyshev collocation points. The LE analysis is also verified by studying the system time and frequency responses for different values of the bifurcation parameter. Furthermore, the LE obtained by the proposed method for the analogous integer order system is compared with those obtained by the Jacobian technique and Grüwald-Letnikov approximation. Finally a fractional state feedback controller is designed to control the chaotic system to a desired equilibrium or periodic trajectory such that the error dynamics are time invariant or time periodic, respectively. The numerical example studied is the damped driven pendulum with fractional dampers.
Determination of Orthotropic Thermal Conductivity in Heat Generating Cylinder
Authors: Patil Sandeep , Chintamani Siddarth , Kumar Ratan , Dennis Brian H.
Published: February 2017

In this paper, numerical inverse analysis is used to predict properties of heat generating material by measuring temperature at outer boundary. Accuracy and efficiency of the method is enhanced by using accurate sensitivity information by use of Semi-Analytical Complex Variable Method (CVSAM). Steady state heat transfer analysis with axi-symmetric model was carried out using finite volume method. Temperature obtained from this analysis, is used as input to inverse method. Objective function for the optimization is difference between computed and measured temperature. This function was minimized with Conjugate Gradient Method (CGM). Coefficients obtained from CVSAM were used in gradient based optimization method. The robustness of developed approach was evaluated by adding Gaussian noise these temperature values. Material properties predicted from this method show close agreement with actual values.
A Probabilistic Model-Based Prognostics Using Meshfree Modeling: A Case Study on Fatigue Life of a Cantilever Beam
Authors: Endeshaw Haileyesus B. , Alemayehu Fisseha M. , Ekwaro-Osire Stephen , Dias João Paulo
Published: February 2017

Accurate prediction of remaining useful life (RUL) will improve reliability and reduce maintenance cost. Therefore, prognostics is essential to predict the RUL of systems and components. However, a big issue of uncertainty prevails in prognostics due to the fact that prognostics pertains to prediction of future state, which is affected by uncertainty. While various researches have been done in areas of prognostics and health management, they lack to perform RUL predictions efficiently. There is a need for an efficient comprehensive framework for quantifying uncertainty in prognostics. The research question to this study is: can meshfree modeling be used in probabilistic prognostics to efficiently predict RUL? The specific aims developed to answer the research question are (1) develop a computational framework for probabilistic prognostics of a fatigue life of a component using meshfree modeling, and (2) perform case study analyses on fatigue life of a cantilever beam. A probabilistic framework was developed that efficiently predicts the RUL of a component using a combination of the meshfree method known as local radial point interpolation method and a fatigue degradation model. Loading uncertainty is quantified and employed in the framework. The computational framework is easily customizable and computationally efficient and, hence, aids in decision making and fault mitigation. As a case study, the RUL of a cantilever beam under plane stress subjected to fatigue loadings was analyzed. Uncertainties in the RUL were quantified in terms of probability density functions, cumulative distribution functions, and 98% bounds of confidence interval. Sensitivity analysis was studied and computational efficiency of the framework was also investigated using first order reliability method and Monte Carlo method. When compared to the Monte Carlo method, first order reliability method provides reasonably good results and is found to be computationally more efficient.
Probabilistic Approach to Determine the Efficiency of Ocean Wave Energy Conversion Systems
Authors: Ekwaro-Osire Stephen , Alemayehu Fisseha M. , Chapman Jamie , Gecgel Ozhan , Dabetwar Shweta , Dias João Paulo , Endeshaw Haileyesus B.
Published: February 2017

Recently, several research studies are being conducted on Ocean Wave Energy Conversion (OWEC) systems that convert wave motion into electricity. The efficiency of OWEC systems is a parameter of great significance. Thus, it is important to consider factors that affect the efficiency of the system, such as ocean wave properties, airflow characteristics of the OWEC systems, and manufacturing inaccuracies. However, these parameters have inherent uncertainties, which should not be disregarded. Without considering these uncertainties, the feasibility assessment of an OWEC system can be misleading. For this study, the following research question was developed: can probabilistic analysis be used to determine the reliability of the efficiency of the OWEC system? To answer this research question, the specific aims developed were: (1) to quantify the uncertainties of the input parameters, and (2) to determine the reliability of efficiency of the OWEC system. The reliability of the efficiency of the system was calculated probabilistically. Probabilistic sensitivity analysis was performed to determine the random variable that had the most impact on the reliability of the efficiency of the OWEC system. Advanced Mean Value (AMV) method was used to determine the probability of failure. NESSUS software was used to perform the probabilistic analysis. In order to assess the reliability of the system, a target efficiency was set and the probability of achieving this efficiency under uncertain input conditions was investigated. The deterministic and probabilistic results were also compared. The results showed that, probabilistic analysis approach can reveal the reliability of the system efficiency by accounting for the wave parameter and manufacturing uncertainties. Moreover, sensitivity analysis showed the variables that had the most impact on reliability of efficiency.
Thermal Performance of Domestic Replacement A19 LED Lighting Products
Authors: Storey Thomas , Rackerby Robin , Dillon Heather , Gingerich Lydia
Published: February 2017

In an effort to create a Light Emitting Diode (LED) lighting system that is as efficient as possible, the heat dissipation system must be accurately measured for proper design and operation. Because LED lighting technology is new, little optimization has been performed on typical cooling system required for most A19 replacement products. This paper describes the research process for evaluating the thermal performance of over 15 LED lighting products and compares their performance to traditional lighting sources, namely incandescent and compact fluorescent (CFL). This process uses radiation and convection to model typical cooling mechanisms for domestic A19 type replacement LED products.

The A19 products selected for this investigation had input wattages ranging between 7 to 60 Watts, with outputs ranging from 450 to 1100 lumens. The average LED tested dissipated 43% (± 5%) of the total heat generated in the lighting product through the heat exchanger. The best thermal performance was observed in an LED product that dissipated approximately 58% of the total product heat through the heat exchanger. Results indicate that significant improvements to the current LED heat exchanger designs are possible, which will help lower the cost of future LED products, improve performance, and reduce the environmental footprint of the products.
Linguistic Fuzzy Logic Control of a Double Inverted Pendulum With Destabilizing Fractional Dampers
Authors: Dabiri Arman , Nazari Morad , Butcher Eric A.
Published: February 2017

In this paper, a fuzzy controller is designed for a mechanical system with fractional damping without a priori knowledge of the system dynamics. Because of the constitutive equation of the damping, equations of motion of the system consist of fractional order terms. In the process of developing the fuzzy controller, the fuzzy rules are selected based on the human brain functions. The controller is first implemented for the case of a single inverted pendulum with destabilizing fractional dampings mounted on a cart, i.e. a two degree of freedom (DOF) system, where the functions of human brain in balancing a stick on a fingertip are used to train the fuzzy rules. Then, by extending the linguistic rules, the controller is applied to a double inverted pendulum with destabilizing fractional dampings mounted on a cart, i.e. a three DOF system. Since the linguistic rules are based on qualitative motion of the pendulums, the controller is capable bringing the system to rest at the unstable equilibrium point despite the fractional destabilizing damping in the system. Finally, the numerical results of the both examples are discussed.
Investigation of the Effect of the Top and the Bottom Temperatures on the Performance of Humidification Dehumidification Desalination Systems
Authors: Qasem Naef , Imteyaz Binash , Antar M. A.
Published: February 2017

Humidification dehumidification process is an attractive small scale water desalination technique in which desalinated water is produced by mimicking the nature’s water cycle. Various modifications to the basic HDH system can be vital in improving the productivity and reducing the production cost of the fresh water. In this study, a closed-air-open-water water-heated (CAOW-WH) cycle and a closed-air-open-water air-heated (CAOW-AH) cycle are modeled and optimized. Effects of mass flow ratio, humidifier and dehumidifier effectiveness, relative humidity, top and bottom temperatures (main concern of study) on the gain output ratio (GOR), the recovery ratio (RR), entropy generation in the system have been analyzed and presented. It has been observed that an optimal mass flow ratio exists for both the cycles, which maximizes the GOR of the system. Moreover, effectiveness of the humidifier and the dehumidifier is an important parameter, which determines the productivity of the systems. Furthermore, a higher GOR can be obtained at low Tmin and high Tmax and at high Tmin and low Tmax for systems heated by a water heater, whereas the GOR of the air heated HDH system increases with increasing both the Tmin and the Tmax for values of humidifier and dehumidifier effectiveness of 0.8. This study provide extended design charts for building an optimum HDH system to produce a pre-determined rate of desalinated water.
Application of Moving Frame Method to Solve 3D Dynamics Problems
Authors: Rezaei Amir G. , Lee Shannon , Impelluso Thomas J.
Published: February 2017

This paper presents application of a new method to solve 3D Dynamics problems. Briefly: 1. The method uses the special orthogonal group, SO(3), and the special Euclidean group, SE(3), of the Lie Algebra. 2. The method uses Cartan’s Moving Frames 3. The method uses a new notation developed in the discipline of Geometrical Physics.

The method makes 3D Dynamics easier than 2D. It offers a more efficient way to model dynamics of rigid bodies and a new approach to linked mechanisms. The new method is founded on rigorous math and avoids the historical ambiguities that accompany traditional methods (such as the vector cross product that produces pseudo-vectors). It is easily learned with the simple mathematical tools of matrix multiplication and second semester calculus. We plan to apply the method to two different 3D dynamics problems: 1. Holonomic and 2. Non-holonomic. The solutions using the new method will be compared to the traditional method in Dynamics.
Numerical Analysis of Influence of SOFA on NOx Emissions for Pulverized Coal Boiler
Authors: Qi Xiangcun , Yang Mo , Zhang Yuwen
Published: February 2017

Influences of different SOFA ratios on NOx emission in a tower pulverized coal fired boiler that burners are arranged in the front and the rear wall are investigated in this paper. The front wall is arranged with three layers of burners, and the rear wall is arranged with two layers of burners. The upper layers are the SOFA nozzles. We adopt the method of adding SOFA to reduce NOx emission, and analyze the influence of SOFA on the internal combustion and NOx emissions for pulverized coal boiler. The results show that the addition of SOFA makes the pulverized coal fired boiler form a reduction zone in the main combustion zone, which can inhibit the NOx production increase, so as to achieve the goal of reducing NOx emissions. And the results show that, it is not true that the more SOFA ratio, the less NOx emissions. In fact, the percentage of SOFA has an optimal value, and below or above of this value, NOx yield will increase. Through comparison of different ratios of SOFA distribution modes with the furnace temperature, O2, CO and NOx, we analyze the influence of SOFA ratio on the internal combustion for pulverized coal boiler, and provide some guidance and bases for the optimization of other similar units.
A Virtual Modelling of a Hybrid Road Tractor for Freight Delivery
Authors: Cicconi Paolo , Landi Daniele , Germani Michele
Published: February 2017

The market of the hybrid electric vehicles has been increasing for several years. Different commercial EV and PHEV solutions are available for passenger cars and light vehicles for freight deliveries. However, the market of heavy trucks still regards traditional ICE vehicles powered by diesel oil fuel. The recent interest for electric solutions have been pushing the development of the hybrid solutions, but only micro-hybrid systems are considered feasible for heavy truck applications. The proposed research aims to define a methodological approach with a virtual model in order to simulate the behavior of a hybrid heavy truck. The scope of this research is the feasibility analysis of a retrofit hybrid heavy truck. A real driving cycle has been used in order to obtain reliable results in terms of cost, energy consumption and gas emission. The layout of the hybrid system has been proposed as well as the sizing of battery and electric motor. A commercial tool has been used for the vehicle modelling and simulation. As a test case, an 18-ton truck has been analyzed with a 10-liter diesel engine. Firstly, the simulation of the diesel truck has been reproduced considering the real driving cycle data. Secondly, the simulation activity has been focused on the evaluation of the hybrid system behavior by investigating different battery sizes with the same boundary conditions related to the real driving cycle.
Wireless Power Efficiency and Quality in Metal Shaft Environment With Eddy Current Losses and Electromagnetic Interference
Authors: Xu Miaomiao , Bu Xiongzhu , Tu Zhangjie
Published: February 2017

Wireless power transmission efficiency and ripple interference attract more and more attention nowadays, but in some special metal environments the transmission efficiency of wireless power will be greatly influenced. In some practical engineering application, we need to use wireless energy to power the sensor on the high speed rotating parts. In order to improve the transmission efficiency and quality of the wireless power supply, researches are conducted to evaluate the eddy current loss and electromagnetic interference of wireless power in high-speed rotating component parameter test system. In this paper, electromagnetic coupling wireless power supply system is established as the transmission model. Then the analytical expressions of eddy current loss are derived by solving Maxwell’s equations, and after that the eddy current loss characteristics is analyzed by combining with the electromagnetic coupling model and eddy current losses model in metal medium. To verify the theoretical results, Maxwell electromagnetic field simulation software is used to analyze the characteristics of the eddy current. Finally, experiments are carried out to illustrate the effect of ferrite magnetic shielding material on the eddy current loss and the shielding effect on the external electromagnetic interference in the metal shaft environment.
Piezoelectric-Based Viscosity Probe for Early-Age Concrete Curing Process Monitoring
Authors: Zhang Chen , Yu Xun
Published: February 2017

This paper presents an active sensing system for concrete viscosity measurement during its very early age. The proposed system is based on the analysis of energy transmission at the boundary of interface between probe (stainless steel bar in the system) and concrete mixture. Different from traditional systems, which employed a couple of actuator and sensor attaching to the surface of the concrete, the new system employs only one transducer as both actuator and sensor. Therefore, the system could be integrated in a small size and more portable. Since only one transducer is employed, the viscosity change of early age concrete is extracted by analyzing the energy variation of the reflected ultrasonic waves instead of applying traditional digital signal processing (DSP) technique (magnitude, phase, velocity). Laboratory experiments are carried out to evaluate the effect of this approach. Results show good match with theoretical analysis. This system can be used in large-scale field investigation of concrete viscosity monitoring for bridges, highways and airport pavements.
Micro Scale Air Sampling Devices: A Numerical Study
Authors: Mirzaee Iman , Charmchi Majid , Sun Hongwei , Song Minghao
Published: February 2017

Numerical simulation of particle collection in a newly developed microfluidic air sampling device is presented in this study. In the simulations, the air carrying the particles is injected into a liquid column to form a bubble. The bubble then releases from the air inlet following with interface deformations and rises in the liquid column carrying the particles inside. During this bubbling process, the particles having impact with the bubble interface are collected in the extraction liquid. For the simulations, Navier-Stokes equations are solved along with piecewise-linear Volume-of-Fluid (VOF) method for tracking the interface deformations. The particle trajectories are predicted on a Lagrangian frame of reference by integrating the force balance on each particle. To validate the numerical model, the results for bubble terminal velocity and shape, and particle removal rate are compared with the available experimental data in the literature. Finally, particle removal from different bubble sizes is studied.
Quantifying and Modeling the Force Variation Within Random Arrays of Spheres
Authors: Akiki G. , Jackson T. L. , Balachandar S.
Published: February 2017

In this study, we perform fully-resolved direct numerical simulations (DNS) of a flow past random arrays of spheres using immersed boundary methods (IBM). These simulations are used to quantify the error arising from point-particle (PP) force models which assumes equal drag and zero lateral forces on all particles. The results show that the rms drag and lateral force fluctuation can be as high as 26% and 15% of the mean drag value, respectively. For each sphere, the hydrodynamic forces are shown to be dependent on the exact location of few neighboring spheres. A pairwise interaction extended point-particle (PIEP) model is then presented. The model can approximate the drag and lateral forces on each sphere by systematically accounting for the location of few of its neighbors. The perturbation from each neighbor is considered separately then linearly superposed to obtain the total variation of the drag and lateral force. Significant error reduction is observed when using PIEP model instead of mean drag models upon comparing to exact forces acquired from the DNS IBM simulations.
Big Data Processing and Storage Framework for ITS: A Case Study on Dynamic Tolling
Authors: Figueiras Paulo , Silva Ricardo , Ramos André , Guerreiro Guilherme , Costa Ruben , Jardim-Goncalves Ricardo
Published: February 2017

Urban and national road networks in many countries are severely congested, resulting in increased travel times, unexpected delays, greater travel costs, worsening air pollution and noise levels, and a greater number of traffic accidents. Expanding traffic network capacities by building more roads is both extremely costly and harmful to the environment. By far the best way to accommodate growing travel demand is to make more efficient use of existing networks. Portugal has a good but underused toll highway network that runs near to an urban/national road network that is free to use but congested. In choosing not to pay a toll, many Portuguese drivers are apparently accepting greater risk to their safety and longer travel times. As a result, the urban/national road network is used far more intensively than projections anticipated, which raises maintenance costs while increasing levels of risk and inconvenience. The main idea behind the work presented here, is to motivate a shift of traffic from the overused network to the underused network. To this end, a model for calculating variable toll fees needs to be developed. In order to support the model, there is the need to accurately predict the status of road networks for real-time, short and medium term horizons, by using machine learning algorithms. Such algorithms will be used to feed the dynamic toll pricing model, reflecting the present and future traffic situations on the network. Since traffic data quantity and quality are crucial to the prediction accuracy of road networks’ statuses, the real-time and predictive analytics methods will use a panoply of data sources. The approach presented here, is being developed under the scope of the H2020 OPTIMUM, a European R&D project on ITS.
Uncertainties of Thermal Conductivities From Equilibrium Molecular Dynamics Simulations
Authors: Wang Zuyuan , Ruan Xiulin
Published: February 2017

The Green-Kubo method in the framework of equilibrium molecular dynamics (EMD) simulations is an effective method that has been widely used to calculate thermal conductivities of materials. The previous studies focused on the thermal conductivity values or the average values from repetitive simulations. Little research has been done to investigate the uncertainties of the thermal conductivities from EMD simulations. In this paper, we use solid argon as the material system to study the factors influencing the uncertainties of the predicted thermal conductivities. We find that the uncertainties decrease with the total simulation time as (ttotal)−α and increase with correlation time as (tcorre)β, where 0.48 < α, β < 0.52. We also find that the uncertainties decrease with increasing temperature, but the simulation domain size has a negligible effect. We propose some guidelines for selecting appropriate simulation parameters (e.g., the correlation time and total simulation time) to achieve a desired level of uncertainty. This work is potentially useful for future studies on calculating the thermal conductivities of materials using EMD simulations.
The Effect of Thermal Cycling on Mechanical Behavior of U-10Mo Monolithic Mini-Plate
Authors: Roh Hee Seok , Mohamed Walid
Published: February 2017

Mini fuel plates used in Advanced Test Reactor (ATR) undergo five steps during the reator operation: startup, ATR Cycle 146A, transition from Cycle 146A to 146B, ATR Cycle 146B, and shutdown. Although the overall irradiation behavior of U-10Mo fuel is expected to be similar to the reactors operating at comparable power levels, there is a concern regarding how variation in operation schedules (that is, how many start-ups and shut-downs could be inserted during the Cycle A and Cycle B) may affect the mechanical behavior of the fuel plate during operation. To investigate any potential effect of number of start-stop activities, we simulated the thermo-mechanical behavior of L1P756 mini-plate, one of fuel plates inserted in ATR under RERTR-12 irradiation conditions with various numbers of start-stop activities artificially added at different points of time in irradiation cycle.

This paper reviews four cases by varying the number of thermal cycles. Finite Element (FE) analyses were performed on the cases to investigate the effect of thermal cycling on the mechanical performance of L1P756 mini-plate. As a result, we observed that U-10Mo is in low stress level during the irradiation Cycle A and B due to creep behavior and that the maximum stress of aluminum cladding increases as the irradiation Cycle A and Cycle B proceeds. However, the number of thermal cycles did not affect the maximum stresses of U-10Mo, liner, and aluminum cladding.
Effects of Linear Hysteric Material Damping and Shock Pulse Shapes for Uniform Board Response
Authors: Kallolimath Sharan , Zhou Jiang
Published: February 2017

Validation of surface mounted electronic devices for drop test performance is considered as one of the most challenging tasks for researchers to search for key dynamic parameters either by experimentation or by numerical simulation. It has not only become challenging task to capture some of the important parameters that affect board flexural rigidity, stiffness, dynamic stresses and strains, but also avoid stress concentrations near undesired locations resulting in non-uniform strain distribution throughout the test board. There is a requirement to simulate exact drop condition that quantifies high impact energy on the board and also control drop to improve the board surface stress/strain distribution measured should be independent from standoff stress region. In this paper, an effort to find the importance of viscous and linear hysteric damping characteristics on uniform board response has been made. The influence of damped responses during no ring impact has been analyzed.

Two different types of computational models are developed and an approximate FEA numerical solutions are obtained to compare current JEDEC test board and alternative hexagonal boards at reduced computational time and challenging experimental cost. The effect of board responses with two types of linear damping models are considered to study the effect. An approach towards finding key parameters that affect stress/strain distribution under both free as well as constrained model has been made, with including different pulse shapes parameters into effect. Maximum board strains are validated and compared using Global FEA model and maximum stresses on the components are evaluated using cut boundary interpolation method. Comparative to empirical results data, an effort to improve uniform stress strain distribution of package solder joints has been made and results are correlated.
Effects of the Shape of a Nozzle With Chevrons on the Dynamics of Turbulent Impinging Jet
Authors: Horra Sadek , Nemouchi Zoubir , Khezzar Lyes
Published: February 2017

This work is a numerical study of a turbulent impinging jet issuing from a nozzle with chevrons. The Reynolds number based on the jet exit velocity and nozzle diameter is equal to 5000 corresponding to a low Mach number of 0.0057 at the nozzle exit. The main objectives of the investigation, inspired by the work of Violato et al. (Int. J. of Heat and Fluid Flow, 37, 2012), are to highlight, from a fundamental point of view, the effects of the nozzle shape and the nozzle-to-plate distance on the mean parameters characterizing the dynamics of the flow in question. The nozzle configurations considered are a circular nozzle without chevrons and nozzles provided with 4 and 6 chevrons. The nozzle-to-plate distance ranges from 2 to 6 nozzle diameters. All the other flow conditions and geometrical parameters used in the different cases treated are identical. Interesting features of the flow are revealed by the obtained results of averaged three-dimensional fields of velocity and turbulent kinetic energy, particularly close to the wall. An attempt is made to bring additional insight into the phenomena in the free jet, the impingement region and the wall jet when using 4, 6 and no chevrons, for different nozzle-to-plate distances.
Design of Broadband Acoustic Cloak Using Topology Optimization
Authors: Lin Weiyang , Newman James C. , Anderson W. Kyle
Published: February 2017

A procedure for broadband topology optimization is applied to the design of acoustic cloaking. An acoustic cloak conceals a given object with arbitrary shapes. That is, the object can be made undetectable with respect to acoustic wave propagation in a specific frequency range. The guided acoustic wave in a given direction will re-attach in the incident direction, leading to a minimized norm of the scattering field. Gradient-based topological optimization is accomplished using a time-dependent adjoint formulation for sensitivity analysis. Results indicate that the current methodology produces improved cloaking performance for narrowband near a target frequency, and as expected less than optimal performance is observed away from this frequency. For topology optimization over a broadband, improved performance is realized over the entire frequency range, but not necessarily optimal at any given target frequency.
Analysis of the Fatigue Performance of Thick T-Joint Samples Considering Residual Stresses
Authors: Esnaola J. A. , Ulacia I. , Ugarte D. , Lopez-Jauregi A. , Torca I. , Larranaga J.
Published: February 2017

Residual stress (RS) pattern of thick T-joint welds, which directly affects fatigue life, varies considerably depending on the thickness and number of passes. Nowadays, most approaches to predict fatigue life do not consider RS real value due to the difficulty of estimating them, hence, they tend to be conservatives. However, recent works have demonstrated that considering RS the conservative error in life prediction can be reduced down to around 15%.

In the present work, the fatigue performance of multipass T-joints of S275JR plates for a thickness range from 20 to 60mm is evaluated considering RS. It is observed that maximum RS value for thick plates decreases progressively (down to 66% of yield stress). Consequently, fatigue performance of different thickness T-joint samples subjected to the same stress load cycles varies considerably in the HCF regime.
Simulation of Leak Noise Propagation and Detection Using COMSOL Multiphysics
Authors: Chalgham Wadie R. , Seibi Abdennour C. , Boukadi Fathi
Published: February 2017

Pipelines leak detection represents an essential aspect in pipeline rehabilitation to avoid any unexpected failure. Several detection techniques have been adopted and received a widespread application in pipeline inspection nowadays but still present a major challenge to field operators. This paper presents an attempt to develop correlations between leaks and their effect on the fluid characteristics inside the pipeline such as fluid velocity, variation of pressure and sound level due to the presence of leaks along the pipeline. Characterization of these parameters and how they propagate with respect to time from the leak source will allow the development of a solution to detect leaks and quantify the amount of fluid being lost. This paper aims at conducting an experimental investigation to determine the sound level for specified leak sizes. The experimental data was used in COMSOL Multiphysics to simulate various fluid flow scenarios inside a 2 in. (5.08 cm.) pipe with different leak sizes.
Heat Transfer Analysis of Shell-and-Helical-Coil Heat Exchangers
Authors: Morris Anthony Edward , Wei C. S. , Unnthorsson Runar , Dell Robert
Published: February 2017

Since 2006, The Center for Innovation and Applied Technology (CIAT) at Cooper Union for the Advancement of Science and Art has been developing a system to use thermal pollution to heat the growth medium of green roofs. CIAT is researching various apparatus and techniques, including shell-and-tube and shell-and-coil heat exchangers, to improve its heated ground agricultural projects. There are limited recorded observations on shell-and-coil heat exchangers; therefore a laboratory work station was created of interchangeable components to test the efficiency of a variety of coil designs.

This paper discusses the data collected on temperature, pressure, and flow rates for a straight tube and two different helical coils. The analysis of this data indicates the superiority of a helical coil design when compared to a straight tube design with respect to both rating and heat transfer rate. The same data analysis has lead to preliminary observations on how the contour properties of a helical coil influence the heat transfer rate through a coil. The authors intend to further this helical coil research to develop a useful mathematical model for determining efficient designs for shell-and-coil heat exchangers.
Design of a Low-Power Quadruped Robot for Remote Data Acquisition in a Heated Garden
Authors: Mitchell Nicholas , Miller Kristin , Wei C. S. , Unnthorsson Runar , Foley William , Dell Robert
Published: February 2017

The authors have developed test beds heated green roofs in New York City and geothermal heated gardens in Iceland using waste heat. A thermoelectric generator developed by the authors for these gardens currently provides more than 6 watts of steady state power. This sustainable power source is independent from the grid and is used for web cameras. The test beds need a mobile, web-accessible robot platform for additional monitoring that is battery-charged by the thermoelectric generator. This robot’s power consumption must match the constraints of the thermoelectric generator’s output.

This paper presents the design and construction of a low-power walking quadruped robotic platform with a specifically designed walking algorithm. The robot will eventually provide the needed web accessible remote monitoring and maintenance capabilities for the test beds. Remote supervision and control of multiple heated green roofs and heated gardens will be possible from a central location.
Design and Construction of a Heated Garden System Utilizing Steam Condensate From an On Site Boiler
Authors: Dell Robert , Wei C. S. , Parikh Raj , Unnthorsson Runar , Mitchell Nicholas , Foley William
Published: February 2017

Municipal District Heating Services and Combined Heat and Power (CHP) systems can produce waste heat in the form of steam condensate and hot water. The authors have demonstrated (IMECE2014-39066) the potential of open field heating of green roofs to reduce thermal pollution, save potable water, and while increasing plant growth. Subsequent research in both Iceland and New York City using similar systems has resulted in the growth of out of region plants. The latest plant growth results are detailed.

The latest research has indicated additional potential impediments, including the need for an additional CHP system pump. A thorough structural analysis on existing older roofs is necessary to avoid an overstressed roof. Substantial UV shielding of the plastic piping and upgrading of the pipes from braided PVC to PEX(a) was also needed.

The details of selecting an appropriate heat exchanger were analyzed for a specific building and associated construction details are provided.
Effect of Surface Roughness on Pool Boiling Heat Transfer of Water on a Superhydrophilic Aluminum Surface
Authors: Kim Jinsub , Jun Seongchul , Lee Jungho , You Seung M.
Published: February 2017

The effect of surface roughness on the pool boiling heat transfer of water was investigated on superhydrophilic aluminum surfaces. The formation of nanoscale protrusions on the aluminum surface was confirmed after immersing it in boiling water, which modified surface wettability to form a superhydrophilic surface. The effect of surface roughness was examined at different average roughness (Ra) values ranging from 0.11–2.93 μm. The boiling heat transfer coefficients increased with an increase in roughness owing to the increased number of cavities. However, the superhydrophilic aluminum surfaces exhibited degradation of the heat transfer coefficients when compared with copper surfaces owing to the flooding of promising cavities. The superhydrophilic aluminum surfaces exhibited a higher critical heat flux (CHF) than the copper surfaces. The CHF was 1,650 kW/m2 for Ra = 0.11 μm, and it increased to 2,150 kW/m2 for Ra = 0.35 μm. Surface roughness is considered to affect CHF as it improves the capillary wicking on the superhydrophilic surface. However, further increase in surface roughness above 0.35 μm did not augment the CHF, even at Ra = 2.93 μm. This upper limit of the CHF appears to result from the hydrodynamic limit on the superhydrophilic surface, because the roughest surface with Ra = 2.93 μm still showed a faster liquid spreading speed.
Guided Waves in a Plate With a Delamination-Like Discontinuity
Authors: Schaal Christoph , Mal Ajit
Published: February 2017

In this paper, some of the useful properties of guided Lamb waves are investigated, using analytical, numerical and experimental methods, in an effort to provide the knowledge base required for the development of viable nondestructive evaluation (NDE) systems for composite structures. An analytical frame-work that considers propagating, nonpropagating and evanescent Lamb waves to analyze the scattering of an incident ultrasonic Lamb wave at delaminations and disbonds is presented. In addition to the delamination problem, the interaction of Lamb waves with a step discontinuity, which can be found at common stiffeners, is investigated using a similar analytical approach. A near-field solution is obtained, and power flows through the cross-sections of the plate are evaluated. The agreement between experimental, numerical and theoretical results is shown to be excellent in certain frequency ranges, providing guidance for the design of reliable and effective inspection systems for modern aeronautical and aerospace structural components.
Comparison of Johnson-Cook Model and an ISV Plasticity Damage Model in Penetration Simulation
Authors: Dou Yangqing , Liu Yucheng , Hammi Youssef
Published: February 2017

This paper compares Johnson-Cook model and an internal state variable (ISV) damage model developed by Bammann and Horstemeyer in simulating damage behavior of materials during penetration process. Bammann and Horstemeyer’s ISV damage model employs internal state variables and their rate equations to capture the evolution of internal states of materials during high speed impact and penetration. From the calculated internal states, observable states or global penetration and perforation response of materials can be decided. Compared to the JC model, the ISV damage model closely reflect history of materials’ mechanical behavior during the penetration and perforation process. Moreover, the damage model links the global impact and penetration performance of the materials to their microstructural evolution, such as the nucleation, growth, and coalescence of micro voids and cracks. Therefore, it possesses an enhanced predicative capability for high speed impact, penetration, and perforation problems. To demonstrate the reliability of the presented ISV model, that model is applied for studying penetration mechanics of aluminum and the numerical results are validated by comparing with simulation results yielded from the Johnson-Cook model as well as analytical results calculated from an existing theoretical model.
Efficient Modeling of Nonlinear Scattering of Ultrasonic Guided Waves From Fatigue Cracks Using Local Interaction Simulation Approach
Authors: Shen Yanfeng , Cesnik Carlos E. S.
Published: February 2017

This paper presents an efficient modeling technique to study the nonlinear scattering of ultrasonic guided waves from fatigue damage. A Local Interaction Simulation Approach (LISA) is adopted, which possesses the versatility to capture arbitrary fatigue crack shapes. The stick-slip contact dynamics is implemented in the LISA model via the penalty method, which captures the nonlinear interactions between guided waves and fatigue cracks. The LISA framework achieves remarkable computation efficiency with its parallel implementation using Compute Unified Device Architecture (CUDA) executed on GPUs. A small-size LISA model is tailored for the purpose of extracting the guided wave scattering features. The model consists of an interior damage region and an exterior absorbing boundary. The interior damage region captures various types of fatigue crack scenarios, while the exterior absorbing boundary surrounds the damage model to eliminate boundary reflections. Thus, the simulation of guided wave scattering in an infinite media can be achieved utilizing a small-size local LISA model. Due to the parallel CUDA implementation and the small-size nature, this local LISA model is highly efficient. Selective mode generation is achieved by coupling/decoupling excitation profiles with certain wave mode shapes, which allows the study of sensitivity of different wave modes to a certain fatigue damage situation. At the sensing locations, mode decomposition is performed on the scattering waves, which enables the study of mode conversion at the damage. Fourier analysis allows the extraction of scattering features at both fundamental and higher harmonic frequencies. A numerical case study on nonlinear scattering of guided waves from a fatigue crack is given. The higher harmonic generation and mode conversion phenomena are presented using the wave damage interaction coefficients (WDIC), from which the sensitive detection directions can be inferred to place sensors. This study can provide guidelines for the effective design of sensitive SHM systems using nonlinear ultrasonic guided waves for fatigue crack detection.