bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Solution Treatment on Microstructure and Mechanical Properties of Graphene Nanoplatelets Reinforced Inconel 718 Composites by Selective Laser Melting
Authors: Wang Yachao , Shi Jing , Deng Xiaoyang , Lu Shiqiang
Published: February 2017

Graphene nanoplatelets (GNPs) have many outstanding properties, such as high mechanical strengths, light weight, and high electric conductivity. These unique properties make it an ideal filler material for various composites. On the other hand, the development MMNCs (metal matrix nanocomposites) through additive manufacturing (AM) processes has become a major innovation in the field of advanced structural materials, owing to shorter production lead time, less material waste, high production flexibility. It is of great innovativeness to have the attractive features combined to produce GNPs reinforced MMNCs using AM techniques. In addition, metal components produced by laser assisted additive manufacturing (LAAM) methods usually have inferior mechanical properties, as compared to the counterparts by the traditional metal forming processes. To achieve optimized mechanical properties, the obtained MMNCs are subjected to various post treatment routines and the effect of post heat treatment on material properties is investigated. In this study, pure Inconel 718 and GNPs reinforced IN718 with 1.1 vol.% and 4.4 vol.% filler material are fabricated by selective laser melting (SLM). Room temperature tensile tests are conducted to evaluate the tensile properties. Scanning electron microscopy (SEM) observations are conducted to analyze the microstructure of materials and to understand the reinforcing mechanism. It is found that fabrication of GNPs reinforced MMC using SLM is a viable approach. The obtained composites possess dense microstructure and enhanced tensile strength. The strengthening effect and mechanisms involved in the composites are discussed. Solution treatments at three levels of temperature (940, 980, and 1020°C) for 1 hour period are carried out to evaluate the effect of the heat treatment on the material microstructure and therefore the resulted mechanical properties of the composite material. The results of samples with and without heat treatment are also compared. The experiments results indicate that that addition of GNPs into Inconel 718 results in significant strength improvement. Moreover, at any volume content of reinforcement, higher solution treatment leads to lower strength, mainly due to coarsened microstructure. The addition of GNPs effectively inhibits the grain growth during the post heat process and the average grain size is significantly refined compared to unreinforced samples. Moreover, through the investigation of various strengthening mechanisms, it is found that Orowan strengthening effect is small and can be neglected for both as-built and heat treated conditions. Load transfer effect is the dominating strengthening effect among all contributors and solution treatment significantly reduces thermal mismatch strengthening.
Fabrication Parameters and Performance Relationship of Twisted and Coiled Polymer Muscles
Authors: Saharan Lokesh , Tadesse Yonas
Published: February 2017

Twisted and Coiled Polymer (TCP) muscles are soft actuators made by inserting twist in a precursor fiber while attaching a dead weight at the end, followed by heat treatment. TCP muscles are thermally driven actuators with high power to weight ratio, large strain and low cost. These muscles have a wide variety of applications in engineering, specifically for robotics since these actuators have large linear deformation in response to applied power (Joule’s Effect). The performance of these muscles depend on numerous fabrication parameters such as speed of the coiling, dead weight used, precursor fiber type, number of filament in precursor fiber, number of plies and training cycles. An in-depth study of the fabrication parameters is required to understand the performance of the muscles. We have designed experimental setup to study the performance of the muscles on different input parameters such as load, current, voltage and output results such as displacement, force and temperature. We present the study of single, double and tripled plied muscles that are fabricated by plying together a twisted and coiled filament. Further, the power consumption of the muscles under various conditions is discussed. This study would help to establish a procedure to fabricate these materials with consistent properties.
Thermal Analysis of Elemental Sulfur in a Shell-and-Tube Configuration for Thermal Energy Storage Applications
Authors: Shinn Mitchell , Nithyanandam Karthik , Barde Amey , Wirz Richard
Published: February 2017

Currently, concentrated solar power (CSP) plants utilize thermal energy storage (TES) in order to store excess energy so that it can later be dispatched during periods of intermittency or during times of high energy demand. Elemental sulfur is a promising candidate storage fluid for high temperature TES systems due to its high thermal mass, moderate vapor pressure, high thermal stability, and low cost. The objective of this paper is to investigate the behavior of encapsulated sulfur in a shell and tube configuration. An experimentally validated, transient, two-dimensional numerical model of the shell and tube TES system is presented. Initial results from both experimental and numerical analysis show high heat transfer performance of sulfur. The numerical model is then used to analyze the dynamic response of the elemental sulfur based TES system for multiple charging and discharging cycles. A sensitivity analysis is performed to analyze the effect of geometry (system length), cutoff temperature, and heat transfer fluid on the overall utilization of energy stored within this system. Overall, this paper demonstrates a systematic parametric study of a novel low cost, high performance TES system based on elemental sulfur as the storage fluid that can be utilized for different high temperature applications.
Conjugated Dynamic Modeling on Vanadium Redox Flow Battery With Non-Constant Variance for Renewable Power Plant Applications
Authors: Siddiquee Abu Nayem Md. Asraf , Jeong Kwangkook
Published: February 2017

A parametric modeling study has been carried out to investigate the effect of change in operating conditions on VRFB performance. The objective of this research is to develop a computer program to predict the dynamic behavior of single cell VRFB combining fluid mechanics, reaction kinetics, and electric circuit. This paper deals with the exact solutions obtained by solving the governing differential equations of VRFB by using Maple 2015. Calculations were made under electrolyte concentrations of 1M–3M of V2+, charging-discharging current of 1.85A–3.85A, and tank to cell ratio of 5:1 to 10:1. Results show that the discharging time increases from 2.2 hours to 6.7 hours when the value of electrolytes concentration of V2+ increases from 1M to 3M. However, the charging time decreases from 6.9 hours to 3.3 hours with the increment of applied current from 1.85A to 3.85A. Additionally, when the tank to cell ratio is increased from 5:1 to 10:1, the charging-discharging time increased from 4.5 hours to 8.2 hours. Ampere-hour capacity of the cell was found to increase when molar concentration of vanadium and, tank to cell ratio were increased.
Comparison of Brain Tissue Material Finite Element Models Based on Threshold for Traumatic Brain Injury
Authors: Eslaminejad Ashkan , Sarvghad-Moghaddam Hesam , Rezaei Asghar , Ziejewski Mariusz , Karami Ghodrat
Published: February 2017

Blast traumatic brain injury (bTBI) may happen due to sudden blast and high-frequency loads. Due to the moral issues and the burden of experimental approaches, using computational methods such as finite element analysis (FEA) can be effective. Several finite element studies have focused on the effects of TBI to anticipate and understand the brain dynamic response. One of the most important factors in every FEA study of bTBI is the accurate modeling of brain tissue material properties. The main goal of this study is a comparison of different brain tissue constitutive models to understand the dynamic response of brain under an identical blast load. The multi-material FE modeling of the human head has several limitations such as its complexity and consequently high computational costs. Therefore, a spherical head model is modeled which suggests more straightforward observation/understanding of the FE modeling of skull (solid), CSF (fluid), and the brain tissue. Three different material models are considered for the brain tissue, namely hyperelastic, viscoelastic, and hyperviscoelastic. Brain dynamic responses are studied in terms of the head kinematics (linear acceleration), intracranial pressure (ICP), shear stress, and maximum mechanical strain. Our results showed that the hyperelastic model predicts larger ICP and shear than other constitutive brain tissue models. However, all material models predicted similar shear strain and head accelerations.
Atomic Diffusion Induced Damage of Ni-Base Super Alloy at Elevated Temperature
Authors: Takahashi Motoki , Suzuki Ken , Miura Hideo
Published: February 2017

Ni-base superalloys consisting of binary phases such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix) have been generally used for rotor blades in energy power plants. However, fine dispersed γ’ precipitates are coarsened perpendicularly to the applied load direction during high temperature creep loading. As this phenomenon called “Rafting” proceeds, the strengthened micro texture disappears and then, cracks starts to grow rapidly along the boundaries of the layered texture. Thus, it is very important to evaluate the change of the crystallinity of the alloy in detail for explicating the atomic scale damage process. In this study, the change of the micro-texture of the Ni-base superalloy (CM247LC) was observed by using EBSD method. The change in the crystallinity was evaluated using both Kernel Average Misorientation (KAM) and image quality (IQ) values. The KAM value indicates the dislocation density and the IQ value shows the order of atom arrangement in the observed area. As a result, KAM value showed no significant change with increasing the creep damage. On the other hand, the IQ value monotonically shifted to lower values and the average IQ value gradually decreased as the creep loading time increased. Decreasing IQ value without change in KAM value implies that the density of point defects such as vacancies mainly increased under creep loading and ordered Ll2 structure became disordered. Therefore, the creep damage of this alloy is mainly dominated by not the accumulation of dislocations, but the increase in the disorder of atom arrangement in the micro texture caused by the diffusion of component elements.
A Comparison of Commercial Building Retrofits Using EnergyPlus for Energy and Emissions Savings
Authors: Fallahi Zahra , Smith Amanda D.
Published: February 2017

For existing commercial buildings, structural retrofits and energy efficiency actions play an important role in providing potential energy and cost saving options to the building owner or operator. Depending on the type of modification made to the building or its operations, the environmental impacts associated with the building may also be reduced. The aim of this research is to compare three simple energy efficiency changes for a modeled commercial office building and quantify their relative impacts in terms of greenhouse gas emissions. Both direct emissions from on-site combustion and indirect emissions through electricity purchases are compared. Hourly emission factors for electricity purchases are used for calculations of CO2 emissions. These emissions factors are unique to the electrical grid in the region where electricity is purchased, and they vary both diurnally and seasonally. In this paper, the selected energy-saving retrofits and energy efficiency actions are: adjusting lighting intensity, adding insulation, and changing the allowable range of temperatures in the buildings HVAC control scheme. Large and small office building prototype models are simulated using the U.S. Department of Energy’s open source building energy modeling software, EnergyPlus. Finally, the relative environmental impacts based on the type of energy modification and the size of the office building is presented in terms of CO2 emissions.
Computational Investigations for a New, Constrained Least-Squares Datum Definition for Circles, Cylinders, and Spheres
Authors: Shakarji Craig M. , Srinivasan Vijay
Published: February 2017

For engineering drawings and CAD definitions, the problem of a suitable datum definition for datum features of circles, spheres, and cylinders has been sought by standards writers over decades. The maximum-inscribed and minimum-circumscribed definitions that have often been used have known problems relating to stability in many common, industrial cases. Examples of these problem cases include cylindrical datum features having an hourglass shape, barrel shape, or the shape of a tapered shaft and circular or spherical datum features that are dimpled. For this cause, many resort to using a least-squares fit whose diameter is scaled to be just inside (or just outside) the datum feature. However, we show this shifted least-squares solution has its own drawbacks.

This paper investigates a new datum definition based on a constrained least-squares criterion. The use of this definition for datum planes has already elegantly solved the problem of providing a full contact solution when that solution is stable, while providing a balanced, stable solution in the case of rocker conditions. With that success as motivation, we now investigate using this definition for circles, spheres, and cylinders.

We demonstrate that the constrained least-squares is an excellent choice for several known problematic cases. This datum definition maintains stability in cases where the maximum-inscribed fits are not unique and thus not stable. Yet they also maintain close adherence to the maximum-inscribed solution when such solutions are stable. We also show that the constrained least-squares solution has clear benefits over the shifted least squares solution.

This is the first computational investigation into the behavior of the constrained least-squares as a possible datum definition for these features. While not being fully comprehensive, these initial findings indicate that the constrained least-squares appears to be a safe and advantageous datum definition choice and provide substantial optimism that results in future investigated cases will be pleasing as well.
Testing the Salinity Control Designs in Calcasieu Lake Using Hydrodynamic and Salinity Transport Models
Authors: Regmi Susan , Zhang Ning
Published: February 2017

An in-house hydrodynamic and salinity transport model was used to test the performance of several salinity control designs in Calcasieu Lake, Louisiana. The 256 sq.km shallow water lake is located in southwest Louisiana, with a 5 mile waterway (Calcasieu Pass) connecting to the Gulf. The salt water in the lake comes from the Gulf due to daily high tide and due to storm surges. In the south west part of the lake, called West Cove, has unique flow circulations and has relatively high salinity concentration comparing to the other part of the lake. A deep Calcasieu Ship Channel is the eastern border of West Cove. The surrounding wetlands of West Cove are disappearing due to the salt water intrusion. The vegetation is dying due to the high salinity concentration, and the soils are eroded quickly without the surface vegetation. The design goal is to reduce the salinity concentration in West Cove without reducing too much flow. The proposed designs include installing a levee and flow and salinity control stations at the eastern border of West Cove separating the water body with Calcasieu Ship Channel. The optimal length and location of the levee and the flow control structure are the objectives of the research. The in-house code was used to simulate the hydrodynamics and salinity transport with the different designs. The results were used to show the effectiveness of the designs on reducing the average salinity concentration in the area and maintaining reasonable flow speed in and out of the area. In the implementation of the designs, the flow and salinity control stations were also included in the simulation. The main function of the stations is to block the salt water from the Gulf during high tide, and direct the fresh water from the north into the area during low tide. This action can keep maintain a single direction fresh water flow from north to south in order to keep salt water out of the system.
Effect of Raster Orientation on Fracture Toughness Properties of 3D Printed ABS Materials and Structures
Authors: Khatri Amit , Adnan Ashfaq
Published: February 2017

Additive manufacturing is a rapidly growing cutting edge technology. Number of experimental studies have shown that strength of product manufactured by additive Fused Deposition Method (FDM) is influenced by different processing parameters involved during manufacturing. This research paper presents experimental and theoretical investigation of fracture toughness of ABS material fabricated with variation in some of process parameters such as Axis Orientations, Raster Orientation, Infill Percentage, Layer Height and Number of Shells. Experiment was designed to manufacture number of cracked specimens with variation in process parameters, measure their tensile strengths for fracture toughness and compare stress intensity factor (SIF) for all of the specimens. This study helps to understand, how different raster orientations affect the fracture toughness of 3D printed structures and also tells us under which process parameters additive manufactured cracked structures provide better strength.
Progress Toward Understanding Catastrophic Failure of Electric Vehicle Li-Ion Batteries: Multi-Physics Modeling
Authors: Gilaki Mehdi , Francis Alex , Bautista Daniel , Avdeev Ilya
Published: February 2017

The goal of this work is to enhance understanding of critical design aspects that would prevent automotive lithium-ion battery packs from catastrophic failures. Modeling lithium-ion batteries is a complex multiscale multi-physics problem. The most dangerous energy producing component of a lithium ion cylindrical cell, jellyroll, is a layered spiral structure, which consists of thin layers of electrodes and separator only microns thick. In this study, we investigate the feasibility of using commercial explicit finite element code LS-DYNA to understand the structural integrity of lithium-ion batteries subjected to crushing condition through computer simulation. The jellyroll was treated as homogeneous material with an effective stress-strain curve obtained through characterization experiments of representative jellyroll samples and individual electrode layers. Physical and numerical impact tests have been conducted on cylindrical cells using developed drop test system. Results of material homogenization, experimental drop testing, and initial structural simulations are discussed. The investigation of structural cell deformations coupled with thermal heat generation and distribution after the crash brings us one step closer to accurate modeling of the entire battery pack that consists of hundreds of cells.
Modelling of Shell and Tube Transport Membrane Condenser Heat Exchangers in Low Grade Waste Heat and Water Recovery Applications
Authors: Soleimanikutanaei Soheil , Ghasemisahebi Esmaiil , Lin Cheng-Xian , Wang Dexin
Published: February 2017

In this study Transport Membrane Condenser (TMC), a new waste heat and water recovery technology based on a nanoporous ceramic membrane vapor separation mechanism has been studied for waste heat and water recovery in power plant application. TMC 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). The effects of mass flow rate of flue gas and water vapor content of flow on the heat transfer and condensation rate of a TMC shell and tube heat exchanger have been studied numerically. A single phase multi-component model is used to assess the capability of single stage TMC heat exchangers in terms of waste heat and water recovery at various inlet conditions. Numerical simulation has been performed using ANSYS-FLUENT software and the condensation rate model has been implemented applying User Define Function.
Multi-Objective Optimal Airfoil Design for Cargo Aircrafts
Authors: Naranjani Yousef , Sun Jian-Qiao
Published: February 2017

The airfoil/wing design is probably the most important part of an aircraft design. A practical aerodynamic design of airfoil requires optimal performance on a wide range of operating conditions. These requirements are often found to be conflicting and demand designer expertise for satisfactory results, not to mention the computational burden of the simulations. Although there exists many studies on direct and inverse design of airfoils, less attention has been paid to simultaneous consideration of multiple objectives. In this paper, a multi-objective optimal airfoil design procedure is presented. PARSEC parametrization method has been utilized to express the airfoil geometry in terms of twelve physical parameters. The aerodynamic performance is obtained by 2D panel method using XFOIL package. Multi-Objective Particle Swarm Optimization (MOPSO) algorithm has been applied for airfoil geometry design because it is efficient and keeps the diversity among the solution set. The objective functions and constraints are chosen to enhance the flight performance at takeoff, cruise, and landing conditions for a long range cargo aircraft. Objectives include maximization of lift to drag ratio (CL/CD), maximization of rate of change of lift to attack angle (dCL/dα) for having increased lift at takeoff/landing condition and minimization of pitching moment CM2. Two applied constraints are CL > CLmin at operating condition and thickness ≤ %25. Each evaluation is consist of finding the optimal operating angle of attack and reporting the corresponding objective values. The quality of the solution at various generations has been studied to guarantee the convergence of the solution. Like any other multi-objective optimization problem (MOP), the solution would be a set of Pareto optimal configurations. Although having multiple solutions gives us a better understanding of the problem, only one configuration should be chosen by the designer. A post processing technique is also used to help the decision maker to choose the most appropriate compromise in the solution set. The method is found to be effective in finding efficient set of airfoils. The simulation is also found to be effective because it can be done on a regular personal computer. It should be noticed that the method can be easily applied to other airfoil design applications by simply modifying the objective functions and the constraints.
Computational Modeling of Anterior and Posterior Pelvic Organ Prolapse (POP)
Authors: Chanda Arnab , Unnikrishnan Vinu , Richter Holly E. , Lockhart Mark E.
Published: February 2017

Pelvic Organ Prolapse (POP) is a condition of the female pelvic system suffered by a significant proportion of women in the U.S. and more across the globe, every year. POP is caused by the weakening of the pelvic floor muscles and musculo-connective tissues due to child birth, menopause and morbid obesity. Prolapse of the pelvic organs namely the urinary bladder, uterus, and rectum into the vaginal canal can cause vaginal discomfort, strained urination or defecation, and sexual dysfunction. To date, success rates of native tissue POP surgeries vary from 50–70% depending on the definition of cure and time-point of assessment. A better understanding of the mechanics of prolapse may lead to improvement in surgical outcomes. In the current work, the mechanics of progression of anterior and posterior vaginal prolapse were modeled to understand the effect of bladder fill and posterior vaginal stresses using computational approaches. A realistic and full-scale female pelvic system model, comprised of the urinary bladder, vaginal canal, uterus, rectum, and fascial connective tissue, was developed using image segmentation methods. All of the relevant loads and boundary conditions were applied based on a comprehensive study of the anatomy and functional morphology of the female pelvis. Hyperelastic material models were adopted to characterize all pelvic tissues, and a non-linear analysis was invoked. In the first set of simulations, a realistic bladder filling and vaginal tissue stiffening in prolapse were modeled and their effects on the anterior vaginal wall (AVW) were estimated in terms of the induced stresses, strains and displacements. The degree of bladder filling was found to be a strong indicator of stress build-up on the AVW. Also, vaginal tissue stiffening was found to increase the size of the high stress zone on the AVW. The second simulation consisted of modeling the different degrees of posterior vaginal wall (PVW) prolapse, in the presence of an average abdominal pressure. The vaginal length was segmented into four sections to study the localized stresses and strains. Also, a clinically well-known phenomena known as the kneeling effect was observed with the PVW in which the vaginal wall displaces away from the rectum and downward towards the vaginal hiatus. All of these results have relevant clinical implications and may provide important perspective for better understanding the mechanics of POP pathophysiology.
Micron Level Placement of Nanowires via Real Time Observation Under Optical Microscope on a Desired Nanochannel for Nanosensors Application
Authors: Beheshti Mohammad , Park Sunggook , Choi Junseo , Geng X. , Podlaha-Murphy Elizabeth
Published: February 2017

Alignment and placement of a single nanowire is a crucial task to assemble lab-on-a-chip devices. Nanowires placement techniques have been mostly performed by pick and place techniques or flow control techniques. These techniques require expensive control systems and they cannot be performed in the ambient conditions. This paper introduces a vision-based inexpensive approach for the alignment and placement of individual metal nanowires on a target nanochannel. Through visual observation of the optical microscope, the method aligned the nanowire perpendicular to the nanochannel. The reproducibility of the procedures was experimentally evaluated.
Exergy Analysis of Metal Cutting Processes
Authors: Pervaiz Salman , Gadalla Mohamed
Published: February 2017

The major global drivers affecting our societies are listed as human population, food based security, energy based security, resource depletion, emissions and associated climate change, community safety, transportation and economic globalization. Out of these global drivers, the most important global driver is identified to be the human population. In order to satisfy the increasing needs of the growing population, manufacturing sector is facing rapid growth and technological developments. Environment friendly design and manufacturing methods are attaining high importance for sustainable development. As manufacturing sector deals with different input resources and waste streams, there is a need to make these developments economically feasible and sustainable in nature. Thermodynamic assessment methodologies can provide an efficient way of quantifying input and output streams. In order to have better understanding of the energy flow involved in the manufacturing process, there is a need to explore a methodology based on the principles of thermodynamics to assess the manufacturing process. The application of second law of thermodynamics, in the form of exergy analysis, is very helpful in improving the efficiency of the process. In addition exergy analysis has potential to reveal the energy inefficiencies present within the process generally mentioned as exergy losses. The increase in exergy efficiency of the process decreases the environmental impact. The presented study provides an overview of implementing exergy analysis for a metal cutting operation of discrete nature. The study revealed that efficiency of removal can be increased by optimizing the input raw materials and electrical energy supplied during the cutting operation.
Evaluate the Effect of pH on the Mixed Brine and Chemical Solutions
Authors: Chancellor Cody , Kirby Connor , Elsharafi Mahmoud
Published: February 2017

The purpose of this study is to observe the effects of a superabsorbent polymer (SAP) when it is introduced to brine solutions containing Calcium ions at varying pH values. When injected into an oil well, a superabsorbent polymer will swell, blocking high permeability zones. The swelled polymer will decrease reservoir heterogeneity, diverting injected water to oil rich zones/areas of the formation. Understanding the kinetics of an SAP is crucial to its proper employment. However, when the polymer is introduced to brine solutions containing calcium, reactions involving the ionization of the sodium crosslinker of the polymers result in the destruction of the polymers and the formation of a precipitate. In an attempt to solve this problem, pH values of various concentrations of Calcium Chloride and Sodium Chloride in deionized water solutions will be varied and introduced to polymer samples to determine if lowering the pH can prevent precipitation. The procedure includes first introducing hydrochloric acid to brine mixtures, mixing and agitating the polymer with the brine solution, and lastly recording the results. The measurements to be recorded will include the volume of the polymers before, during, and after the swelling process. From this data, the swelling ratios of the polymer samples will be calculated, graphed, and contrasted appropriately according to time intervals and the pH of each sample. By following this procedure, the data shows that a very low pH can significantly inhibit the extent to which the polymer precipitates out with Calcium ions. Temperature tends to decrease polymer volume in brines with pH values above the 1–2 pH range, while pH values in or below said range increase in volume substantially.
Critical Heat Balance Error for a General Imbalanced Heat Exchanger
Authors: Zhang Zhifeng , Bai Bofeng
Published: February 2017

The reliability of experimental data are important for heat exchanger design and evaluation. In the present paper, we extended the concept of Critical Heat Balance Error (CHBE) to a general imbalanced heat exchanger with thermal capacity ratio great than 1. Based on the principle of positive entropy generation in experiment, were analytically expressed the CHBE under the influence of different thermal capacity ratios. Interestingly, we found the same analytical expression as previous research which is, CHBE = −(1 − τ)(1 − ε), where ε and τ are heat exchanger efficiency and inlet temperature ratio, respectively. Therefore, we claim this analytical filter can be used for a general heat exchanger with any thermal capacity configuration.
Towards a Technoeconomic Framework for Estimating Cost-Performance Tradeoffs for Power Plants Incorporating Transformative Dry-Cooling Technologies
Authors: Short Geoffrey , Stark Addison K. , Matuszak Daniel , Klausner James F.
Published: February 2017

Fresh water withdrawal for thermoelectric power generation in the U.S. is approximately 139 billion gallons per day (BGD), or 41% of total fresh water draw, making it the largest single use of fresh water in the U.S. Of the fresh water withdrawn for the power generation sector, 4.3 BGD is dissipated to the atmosphere by cooling towers and spray ponds. Dry-cooled power plants are attractive and sometimes necessary because they avoid significant withdrawal and consumption of freshwater resources that could otherwise be used for other purposes. This could become even more important when considering the potential effects of climate change (1). Additional benefits of dry-cooling include power plant site flexibility, reduced risk of water scarcity, and faster permitting (reducing project development time and cost). However, dry-cooling systems are known to be more costly and larger than their wet-cooling counterparts. Additionally, without the benefit of additional latent heat transfer through evaporation, the Rankine cycle condensing (cold) temperature for dry-cooling is typically higher than that for wet-cooling, affecting the efficiency of power production and the resultant levelized cost of electricity (LCOE).

The Advanced Research Projects Agency - Energy (ARPA-E) has developed a technoeconomic analysis (TEA) model for the development of indirect dry-cooling systems employing steam condensation within a natural gas combined cycle power plant. The TEA model has been used to inform the Advanced Research in Dry-Cooling (ARID) Program on the performance metrics needed to achieve an economical dry-cooling technology. In order to assess the relationship between air-cooled heat exchanger (ACHX) performance, including air side heat transfer coefficient and pressure drop, and power plant economics, ARPA-E has employed a modified version of the National Energy Technology Laboratory (NETL) model of a 550 MW natural gas combined cycle (NGCC) plant employing an evaporative cooling system. The evaporative cooling system, including associated balance of system costs, was replaced with a thermodynamic model for an ACHX with the desired improved heat transfer performance and supplemental cooling and storage systems. Monte Carlo simulation determined an optimal ACHX geometry and associated ACHX cost. Allowing for an increase in LCOE of 5%, the maximum allowable additional cost of the supplemental cooling system was determined as a function of the degree of cooling of the working fluid required. This paper describes the methodologies employed in the TEA, details the results, and includes related models as supplemental material, while providing insight on how the open source tool might be used for thermal management innovation.
Embedded Controller Based Automatic Gear Change Mechanism for Two Wheeled Manual Transmission Motorcycle
Authors: Mairal Aditya A. , Pandey Akash B. , Shah Jimil M.
Published: February 2017

For the vehicle to move forward the engine has to be connected to driving wheels so as to propel the vehicle. The engine rotates at relatively high speeds, while the wheels are required to turn at slower speeds. The torque requirements of the vehicle vary as per the prevailing conditions of load, terrain etc. Gear box provides different gear ratios between the engine and the driving wheels, to suit the varying road conditions such as when climbing hills, traversing rough road or sandy road or pulling a load. The required gear shift for providing varying torque requirements can be obtained either manually or automatically. Automatic gear shifting mechanism is a concept implementing an embedded control system for actuating the gears automatically without human intervention. The automation is achieved by using a microcontroller and suitable sensor and actuator hardware. Whenever the speed of the vehicle increases or decreases beyond a pre-defined set of values, the microcontroller based control system actuates the clutch as well as the gear and helps maintain a steady operation of the automobile. The concept of automatic gear change is applied in this work to a 4-stroke, manual transmission motorcycle. The clutch is actuated by means of a DC Motor actuated mechanism and gear lever is actuated by means of the spring loaded solenoid actuator, both controlled by a microcontroller based circuit, programmed to read the signals from an inductive proximity sensor which senses the actual speed of the wheel. The system design and development is described in this paper with control circuit and control logic.
An Introduction to Flow Field Analysis Models for Wind Harnessing Machines
Authors: Goudarzi Navid , Heydarlaki Ramin
Published: February 2017

Even though wind turbine industry is a mature technology, it fails in standalone power systems, especially in low wind speed regimes. Vertical axis wind turbine (VAWT)/unconventional configurations have shown a great potential for generating electricity in an expanded range of operation in residential, commercial, and off-grid property applications. Their low power coefficient values and high cost of energy at different wind speeds should be improved through more comprehensive studies. In this work, novel wind harnessing configurations to fill some of the existing wind turbine performance gaps are reviewed and compared. A number of flow field analysis models for wind harnessing machines is explored. The results show the strength of VAWTs compared to conventional horizontal axis wind turbines. Also, it introduces appropriate models for flow field analysis of VAWTs/unconventional wind harnessing machines to obtain an enhanced aerodynamic performance, to the greatest extent for both onshore and offshore applications. Finally, new designs to further expand the operational range of wind harnessing machines at a lower cost are proposed.
Design and Development of Compliant Microgripper-Based Assembly Station
Authors: Shrivastava Khushboo , Joshi Suhas S.
Published: February 2017

This paper presents the design and development of a flexure-based compliant microgripper to handle and manipulate objects of various sizes ranging from 500–1000 μm. A flexure based compliant microgripper is developed using pseudo rigid body (PRB) modeling, which is then optimized using multi-objective genetic algorithm. A simulation based methodology is adopted to predict the motion movement of the PRB-based and designed microgripper. The final prototype developed generates a maximum end deflection of 2200 μm at maximum force of 0.3 N. Linear and rotational positioning systems are incorporated to manipulate objects in 2D. The system has been successfully demonstrated to grip a metal wire of size 750 μm.
Localized Heating due to Stress Concentrations Induced in a Lossy Elastic Medium via the Scattering of Compressional Waves by a Rigid Spherical Inclusion
Authors: Mares Jesus O. , Woods Daniel C. , Baker Caroline E. , Son Steven F. , Rhoads Jeffrey F. , Bolton J. Stuart , Gonzalez Marcial
Published: February 2017

High-frequency mechanical excitation has been shown to generate heat within composite energetic materials and even induce reactions in single energetic crystals embedded within an elastic binder. To further the understanding of how wave scattering effects attributable to the presence of an energetic crystal can result in concentrated heating near the inclusion, an analytical model is presented. The stress and displacement solutions associated with the scattering of compressional plane waves by a spherical obstacle (Pao and Mow, 1963) are modified to account for the viscoelastic effects of the lossy media surrounding the inclusion (Gaunaurd and Uberall, 1978). The results from this solution are then utilized to estimate the spatial heat generation due to the harmonic straining of the material, and the temperature field of the system is predicted for a given duration of time. It is shown that for certain excitation and sample configurations, the elicited thermal response near the inclusion may approach, or even exceed, realistic decomposition temperatures of various energetic materials. Although this prediction indicates that viscoelastic heating of the binder may initiate the decomposition of the crystal even in the absence of defects such as initial voids or debonding between the crystal and binder, the thermal response resulting from this bulk heating phenomenon may be a precursor to dynamic events associated with such crystal-scale effects.
A Study of TCPC-Stent Conjunction for Cavopulmonary Assist in Fontan Patients With Right Ventricular Dysfunction
Authors: Jagani Jakin , Untaroiu Alexandrina
Published: February 2017

Mechanical circulatory support devices have gained significant importance in recent years as a viable therapeutic option to support paediatric population and children with single functional ventricle. The Fontan operation helps to reroute the deoxygenated blood to the lungs by bypassing the dysfunctional right ventricle. Total Cavopulmonary Connection (TCPC) is usually a method opted by the clinicians to connect the superior vena cava (SVC) and inferior vena cava (IVC) to the left and right pulmonary artery (LPA and RPA). However, the non-physiologic flow patterns created by the Fontan procedure leads to an increase in chances of platelet deposition and pressure loss which calls for heart transplantation to prevent early and late stage pathophysiology. This had led to modification of TCPC geometry to reduce the pressure and energy loss and thereby unload the single functional ventricle to ensure longer survival period. A study on mechanical circulatory device in conjunction with the modified TCPC geometry has seen little exposure and has opened new gates to develop a variety of state-of-art cavopulmonary assist devices. This study is focused on the selection of optimal TCPC to reduce energy loss and the effect of stent inside the modified TCPC on hemodynamics and flow structures.

Four TCPC connections, developed for a particular age group of children, were studied for the velocity field, overall pressure and energy loss. In addition, the four TCPC connection geometries were also studied for distribution of hepatic blood from the IVC to both pulmonary arteries, and hence the lungs, to prevent development of any arteriovenous malformations. The entire stent assembly mounted inside the two best performing TCPC connections was examined for the hemodynamic effects using a series of 3D-CFD simulations.

The curved-type connection for the TCPC proved to provide minimum pressure and energy loss along with reduced traces of vortex and recirculation. However, it was not efficient in terms of hepatic blood distribution. The flared geometry performed second best in terms of both minimum power loss and even hepatic blood distribution. There was a slight difference in power loss between the flared and the curved TCPC configuration with stent but the flared geometry had better hepatic blood distribution.

This study demonstrated that a stent in conjunction with a TCPC leads to development of a helical flow pattern which provides better mixing of blood and even distribution to both the pulmonary arteries. The design of a stent with the best performing flared TCPC configuration can be optimized to reduce the amount of power loss and vortex generation and can be used to design similar scaled models for paediatric population of various age groups.
Seeing is believing: Visualization of He distribution in zircon and implications for thermal history reconstruction on single crystals
Authors: Danišík Martin , McInnes Brent I. A. , Kirkland Christopher L. , McDonald Brad J. , Evans Noreen J. , Becker Thomas
Published: February 2017

Inverse modeling of intracrystal (U-Th)/(Pb-He) abundances in individual zircons constrains the thermal history of Earth’s crust.
Biophysical properties of human β-cardiac myosin with converter mutations that cause hypertrophic cardiomyopathy
Authors: Kawana Masataka , Sarkar Saswata S. , Sutton Shirley , Ruppel Kathleen M. , Spudich James A.
Published: February 2017

Converter HCM mutations cause only small changes in the biophysics of myosin, suggesting an alternative mechanism for hypercontractility.
Homodimerization attenuates the anti-inflammatory activity of interleukin-37
Authors: Ellisdon Andrew M. , Nold-Petry Claudia A. , D’Andrea Laura , Cho Steven X. , Lao Jason C. , Rudloff Ina , Ngo Devi , Lo Camden Y. , Soares da Costa Tatiana P. , Perugini Matthew A. , Conroy Paul J. , Whisstock James C. , Nold Marcel F.
Published: February 2017

Interleukin-37 homodimerization regulates its anti-inflammatory activity.
Hypoxia determines survival outcomes of bacterial infection through HIF-1α–dependent reprogramming of leukocyte metabolism
Authors: Thompson A. A. Roger , Dickinson Rebecca S. , Murphy Fiona , Thomson John P. , Marriott Helen M. , Tavares Adriana , Willson Joseph , Williams Lynne , Lewis Amy , Mirchandani Ananda , Dos Santos Coelho Patricia , Doherty Catherine , Ryan Eilise , Watts Emily , Morton Nicholas M. , Forbes Shareen , Stimson Roland H. , Hameed Abdul G. , Arnold Nadine , Preston Julie A. , Lawrie Allan , Finisguerra Veronica , Mazzone Massimiliano , Sadiku Pranvera , Goveia Jermaine , Taverna Federico , Carmeliet Peter , Foster Simon J. , Chilvers Edwin R. , Cowburn Andrew S. , Dockrell David H. , Johnson Randall S. , Meehan Richard R. , Whyte Moira K. B. , Walmsley Sarah R.
Published: February 2017

Infection outcomes are regulated by neutrophil responses to oxygen and nutrient availability.
Carbon Source-Dependent Inducible Metabolism of Veratryl Alcohol and Ferulic Acid in Pseudomonas putida CSV86
Authors: Mohan Karishma , Phale Prashant S.
Published: February 2017

Pseudomonas putida
CSV86 degrades lignin-derived metabolic intermediates,
viz
., veratryl alcohol, ferulic acid, vanillin, and vanillic acid, as the sole sources of carbon and energy. Strain CSV86 also degraded lignin sulfonate. Cell respiration, enzyme activity, biotransformation, and high-pressure liquid chromatography (HPLC) analyses suggest that veratryl alcohol and ferulic acid are metabolized to vanillic acid by two distinct carbon source-dependent inducible pathways. Vanillic acid was further metabolized to protocatechuic acid and entered the central carbon pathway via the β-ketoadipate route after
ortho
ring cleavage. Genes encoding putative enzymes involved in the degradation were found to be present at
fer
,
ver
, and
van
loci. The transcriptional analysis suggests a carbon source-dependent cotranscription of these loci, substantiating the metabolic studies. Biochemical and quantitative real-time (qRT)-PCR studies revealed the presence of two distinct
O
-demethylases,
viz
., VerAB and VanAB, involved in the oxidative demethylation of veratric acid and vanillic acid, respectively. This report describes the various steps involved in metabolizing lignin-derived aromatic compounds at the biochemical level and identifies the genes involved in degrading veratric acid and the arrangement of phenylpropanoid metabolic genes as three distinct inducible transcription units/operons. This study provides insight into the bacterial degradation of lignin-derived aromatics and the potential of
P. putida
CSV86 as a suitable candidate for producing valuable products.

IMPORTANCE
Pseudomonas putida
CSV86 metabolizes lignin and its metabolic intermediates as a carbon source. Strain CSV86 displays a unique property of preferential utilization of aromatics, including for phenylpropanoids over glucose. This report unravels veratryl alcohol metabolism and genes encoding veratric acid
O
-demethylase, hitherto unknown in pseudomonads, thereby providing new insight into the metabolic pathway and gene pool for lignin degradation in bacteria. The biochemical and genetic characterization of phenylpropanoid metabolism makes it a prospective system for its application in producing valuable products, such as vanillin and vanillic acid, from lignocellulose. This study supports the immense potential of
P. putida
CSV86 as a suitable candidate for bioremediation and biorefinery.