bluuebunny/crossref_metadata_2025_split huggingface dataset:
Atypical free‐floating iridociliary pigmented epithelial cysts and secondary glaucoma in a caiman (Caiman latirostris)
Authors: Oriá Arianne Pontes , Estrela‐Lima Alessandra , Teixeira Leandro B. C. , Dubielzig Richard R. , Ofri Ron 
Published: February 2021

AbstractWe describe a case of chronic ocular trauma that resulted in fixed and free‐floating, pigmented epithelial iridociliary cysts, inflammation, and secondary glaucoma in a caiman (Caiman latirostris). A 20‐ to 25‐year‐old male caiman was presented with phthisis bulbi in the right eye, and congested episcleral vessels, corneal leukoma, disorganized anterior chamber, multifocal anterior synechia, and elevated intraocular pressure in the left eye. Ocular ultrasound of the left eye revealed round structures dispersed in the anterior and posterior chambers and vitreous cavity. Bilateral enucleation was performed, and gross pathology of the left eye revealed multiple pigmented cysts attached to the iris and posterior corneal surface causing marked distortion of the anterior uvea, and free‐floating in the vitreous cavity. Histopathology demonstrated heavily pigmented cystic structures of iridociliary epithelium origin carpeting the anterior segment surfaces and causing obstruction of the iridocorneal angles, leading to secondary glaucoma. To the authors’ knowledge, this is the first report of iridociliary cysts in wildlife species.
A Method of Balancing Reciprocating Machines
Authors: Johnson W. E. 
Published: February 2021

Abstract
General types of balancing problems are classified into three groups: Those requiring perfect balance, those in which the machine inherently is balanced sufficiently well for practical purposes, and those requiring a distinct compromise, such as single-cylinder engines. It is a method of securing an optimum condition for the last class that is presented.
The method consists, first, of the selection of a suitable criterion for the particular problem, such as minimizing the average potential energy of vibration in a spring mounting, which tends to secure the least possible transmission of vibration. Another criterion may reduce the vibration of the machine itself to a minimum. The selection of a suitable criterion is a matter for the judgment of the designer. When the selection is made, the attainment of the optimum sought is carried out by mathematical analysis. This general method is particularly useful for balancing spring-mounted machines. An illustrative problem is given for this case, showing the effects of working to several different criteria.
The Temperature History During the Constant-Rate Heating of a Solid Circular Cylinder
Authors: Newman Albert B. , Church Austin H. 
Published: February 2021

Abstract
The authors present a solution of the partial-differential equation for heat conduction in a solid circular cylinder for the condition where the heat is forced into the cylindrical surface at a constant rate. A mathematical analysis is made of the temperature-history curve at the heated face and at the axis of the cylinder and the results are reduced to tabular and graphical form for practical application.
Single Point Incremental Forming Springback Reduction Using Edge Stiffener
Authors: Grimm Tyler J. , Parvathy Gowtham V. , Mears Laine 
Published: February 2021

Abstract
Single point incremental forming (SPIF) is a dieless forming process which uses local deformations to form complex geometries. This is achieved through the use of a typically hemispherical tipped forming tool. Several variations of SPIF have been developed to improve the performance of this process. This includes the use of a partial die which is placed on the back-side of the material. The forming tool is then able to press the material into this partial die. Another method is to utilize a clamping fixture with a periphery that closely matches that of the desired geometry. While both of these methods improve the performance of SPIF, they also require dedicated fixturing. While these modifications still present an advantage over traditional stamping, it is desirable to avoid the use of any geometry-specific equipment.
Springback is a significant issue when performing traditional SPIF. Springback can occur in two different ways: local and global. Local springback results from the elastic deformations created outside the region located directly beneath the forming tool. This causes poor accuracy as a result. Compensation methods have been developed to overcome this type of springback but are faced with certain limitations. Global springback refers to the springback experienced once the material is removed from its clamping fixture. This springback is a result of all residual stresses produced during forming. This springback is much more difficult to reduce and often requires annealing the workpiece subsequent to forming.
A toolpath approach is explored herein as a method to reduce springback without the use of geometry-specific equipment. The toolpath developed begins at the edge of the clamping fixture, regardless of the geometry shape, and forms the flashing material prior to the desired geometry. By starting the toolpath along the edge of the fixture, elastic deformations are minimized. Additionally, the work hardening produced during this forming acts as a stiffener for the desired geometry, which behaves as a frame which matches the periphery of the desired geometry.
This method was experimentally tested for its accuracy improvements when forming a truncated pyramid from 5052 aluminum. The angle of this stiffener, the step size of the stiffener, and the size of the desired geometry were varied. The fixture dimensions were held constant. This method was found to reduce the overall springback of the part and increase the accuracy of the resulting geometry. Furthermore, it was found that a large step size can be used to form the stiffener section of the part. By using a large step size, the time it takes to form this sacrificial region is minimized.
Deformation Behavior of Hollow Axles With Constant Hole Diameter by Three-Roll Skew Rolling
Authors: Zhang Song , Shu Xuedao , Wang Jitai , Xu Chang 
Published: February 2021

Abstract
At present, hollow axles with constant hole diameter is mainly formed by turning thick-walled hollow tubes. This method of processing has low material utilization and processing efficiency. And heat treatment is required to improve the mechanical properties of hollow axles. To improve the material utilization and processing efficiency of hollow axles with constant hole diameter during the forming process, a new processing technique, three-roll skew rolling process, is proposed to form a hollow axles with constant hole diameter in this paper. The three-roll skew rolling process is a continuous plastic forming process, which has high material utilization and processing efficiency, and it can improve the mechanical properties of the rolled parts. Firstly, combining the working principle of three-roll skew rolling and the structural characteristics of hollow axles with constant hole diameter, the forming mechanism of hollow axles with constant hole diameter by three-roll skew rolling is described. Secondly, the finite element model of the hollow axles with constant hole diameter by three-roll skew rolling is established according to the dimensions of the hollow axles with constant hole diameter, the material characteristics of the hollow axles, and the stable rolling conditions of three-roll skew rolling. The process parameters of the hollow axles are also determined. Thirdly, according to each step position of the hollow axles, the forming process of the hollow axles with constant hole diameter by three-roll skew rolling is divided into 5 deformation stages. Lastly, the stress and strain field of each deformation stage of the hollow axles was analyzed. The results show that the dimensions of the hollow axles with constant hole diameter by three-roll skew rolling are very close to the designed dimensions, which indicates that the material utilization of the rolled hollow axles is very high. Along the rolling direction, the descending step of the hollow axle is easier to form than the ascending step, and the forming quality is also better. The surface metal of the rolled hollow axles flows faster than the internal metal. Areas with large stress and strain are mainly concentrated at both ends of the rolled hollow axles. And the magnitude of stress and strain gradually decrease from the surface to the center. The hollow axles with constant hole diameter by three-roll skew rolling has a good forming quality and high forming efficiency. The hollow axles with constant hole diameter is formed by three-roll skew rolling process, which has broad application prospects.
Design and Development of an Additively Manufactured Geothermal Heat Exchanger for Improved Efficiency and Easy Installation
Authors: Gemeda Takele , Estrada Sandy , Demisse Wondwosen , Wang Lei , Xu Jiajun 
Published: February 2021

Abstract
Effective system energy management and cooling is critical for a range of increasingly complex systems and missions. Various industries and agencies seek technologies to use energy more efficiently in various applications, and thereby increase system energy efficiencies in future advanced energy systems. There has been an increasing interest in exploiting the use of additive manufacturing in developing nontraditional energy conversion schemes. Meanwhile, wind power and solar power systems have become part of common knowledge and conversation over the past few years. While these provide excellent sustainable options of energy production, geothermal energy systems are just as efficient and economical. Solar and wind energy collectors are also site specific. On the other hand, the geothermal systems do not take up buildable ground level space nor are they location or climate specific. The earth has a generally constant temperature throughout the year which can be used in geothermal systems to benefit all sites. If all geothermal resources were combined, enough energy would be produced to provide all of the electricity needs in the United States. However, conventional geothermal system requires the relatively complex installation process and can potentially be cost prohibitive to many potential users.
In this study, an additively manufactured heat exchanger was designed and developed to resolve that issue. The heat exchanger can be integrated with a conventional geothermal heating and cooling system for improved efficiency and easy installation. A customized geothermal heating and cooling loop was designed and developed for testing the efficiency of the heat exchanger. Within this proposed system, this additive manufactured heat exchanger is designed and fabricated to improve it efficiency and easy installation with minimal tools needed. This new design eliminates the need of excavation of the soil and installation of long tubes as conventionally required for geothermal system. This new heat exchanger was designed using CREO software and fabricated using an EOS M280 direct metal laser sintering system at University of the District of Columbia. It is then integrated with a heat pump to exchange heat between a constant temperature of water bath circulator and a water heat sink. A prototype system was designed and constructed, which allowed the direct assessment of its performance. The performance of the heat exchanger is studied using COMSOL software to assess its heat transfer performance. The results have shown a significant improvement in its efficiency. It has shown the promising application of metal additive manufacturing technique in improving the efficiency of existing energy harvesting applications.
Cylindricity Sensitivity Thermal Model of the AGR-5/6/7 Experiment in the Advanced Test Reactor
Authors: Hawkes Grant L. 
Published: February 2021

Abstract
The AGR-5/6/7 experiment is currently being irradiated in the Advanced Test Reactor (ATR) at the Idaho National Laboratory and is approximately 70% complete. Several fuel and material irradiation experiments have been planned for the U.S. Department of Energy Advanced Gas Reactor Fuel Development and Qualification Program, which supports the development and qualification of tristructural isotropic (TRISO)-coated particle fuel for use in high-temperature gas-cooled reactors. The goals of these experiments are to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support development of fuel performance models and codes, and provide irradiated fuel and materials for post-irradiation examination and safety testing. Originally planned and named as separate fuel experiments, but subsequently combined into a single test train, AGR-5/6/7 is testing low-enriched uranium oxycarbide TRISO fuel. The AGR-5/6/7 test train has five capsules with thermocouples and independent gas control mixtures.
Unique to this paper is a sensitivity study concerning the cylindricity of the graphite holders containing the fuel compacts and their eccentricity in relation to the stainless-steel capsule walls. Each capsule has small nubs on the outside used for centering the graphite holder inside the stainless-steel capsule with a small gas gap used to control temperature. Due to machining tolerances of these nubs, and vibration wearing the nubs down when the experiment is running in the reactor, the possibility exists that the holder may move around radially. Each capsule is equipped with several thermocouples placed at various radii and depths within each graphite holder. This paper will show the sensitivity of offsetting the graphite holder for various radii in 45-degree increments around the circle with the objective of minimizing the difference between the measured thermocouples and the modeled thermocouple temperatures. Separate gas mixtures of helium/neon are introduced into this gas gap between the holder and capsule wall and changed as necessary to maintain the desired thermocouple temperatures to keep the fuel compacts at a constant temperature as the nuclear reactor conditions change.
The goal of the sensitivity study is to find a radius and an angle to offset the holder from perfectly centered for each of the five capsules separately. The complex thermal model includes fission heating, gamma heating, radiation heat transfer, and heat transfer via conduction and radiation across the control gaps. Subroutines linked to the thermal model offer an easy method to offset the graphite holder from the capsule walls without remeshing the entire model.
Experimental Investigation of Friction Between Vehicle Air Bag Material and Head Skin for Humans and Crash Test Dummies
Authors: Dong Sheng , Kang Yun-Seok , Bolte John , Stammen Jason , Moorhouse Kevin 
Published: February 2021

Abstract
Motor vehicle crashes can produce serious head or brain injuries due to contact with interior vehicle structures. It has been found through both field data analysis and experimental testing that many of these brain injuries occur in oblique crashes, even with the deployment of air bags. Research has determined that rotational head velocity is strongly correlated to the risk of brain injury through metrics such as Brain Rotational Injury Criteria (BrIC). The severity of rotational head motion could be related to the friction force developed during contact between the head and air bags. Although crash test dummy head skins are designed with appropriate mass properties and anthropometry as well as material type and thickness to emulate the proper impact response of the human head, it is not known whether they accurately represent the frictional properties of human skin during air bag interaction. This study experimentally characterized the friction coefficient between human skin and air bag fabrics using a pin-on-disc tribometer. Skin samples were harvested from different locations (forehead, cheeks, chin) from specimens of post-mortem human subjects (PMHS). Fabric samples were cut from six different air bags spanning various vehicle manufacturers and interior mounting locations. For comparison, four types of dummy head skin samples were also tested against the air bag samples. Friction was measured between different skinair bag material combinations at various linear velocities and normal forces. It was determined that the difference between human and dummy skin friction with the air bag samples varied significantly among different air bags; however, the effect of linear speed, normal force, and human skin sample harvesting location on friction coefficient is negligible. Except for one air bag fabric, the friction coefficients of the dummy skin are higher than those quantified for human skin.
Effects of Different Cooling Methods After Demoulding on the Cornering Fatigue Resistance of the Injection-Molded Long-Glass-Fiber Reinforced Thermoplastic Composite Wheel
Authors: Zhang Yue , Liu Xiandong , Luo Jintao , Shan Yingchun 
Published: February 2021

Abstract
As an un-sprung rotary part of the vehicle, the wheel has a significant effect on reducing fuel consumption and emission for conventional fuel vehicles and increasing the mileage of electric vehicles, which is significantly higher than that of a spring-loaded non-rotating part. The high-performance long fiber reinforced thermoplastic composite is used to manufacture wheel through the injection molding, which not only can achieve wheel weight reduction but also provides a new way to promote wheel lightweight due to its advantages of fast molding, easy to achieve mass production, easy to recycle materials and so on. The wheel is a key safety component of a vehicle, and its performance is one of the most important factors that affect the safety of the vehicle. Therefore, the wheel made of long fiber reinforced thermoplastic composite must meet the requirements of cornering fatigue test, radial fatigue test and 13° bench impact test. In this paper, aiming at the cornering fatigue property of the composite wheel, the influence of different cooling methods on this performance of the composite wheel after demoulding are studied. The injection molding of passenger car wheels (type 5.5J × 15), composed of long-glass-fiber (LGF) reinforced thermoplastic composite (PA66+50 wt. % LGF), are fabricated under the same injection process conditions. The two cooling methods, water-cooling and air-cooling, are used to cool composite wheel to room temperature under atmospheric pressure respectively. The cornering fatigue test is carried out on the cooled composite wheels, and attain the variation curves of the maximum principal strain and the minimum principal strain with time in different directions at the test points of the spoke root of the composite wheel, respectively. In addition, during the process of cornering fatigue test of the composite wheel, the temperature change of the spokes is monitored in real-time with the aid of infrared thermal imager, and obtain the temperature distribution and change of the spokes under different load cycles. The effect of different cooling methods on the cornering fatigue performance of composite wheels is compared and analyzed based on the maximum number of cycles, the strain test results of spoke root and temperature distribution and change of composite wheel. The results show that after demouling, air cooling mode is more beneficial to improving the composite wheel cornering fatigue performance than water cooling mode. This rule is also applicable to composite wheels that are injection molded with composite materials provided by another manufacturer. The research results provide some guidance for the processing of the wheel made of long-glass-fiber reinforced thermoplastic composite.
Numerical Investigation of Convective Heat Transfer on a Dynamic Wall Heat Exchanger With Varying Amplitude and Frequency
Authors: Rahman Md. Habibur , Chowdhury Emdadul Haque , Redwan Didarul Ahasan , Prince Hasib Ahmed , Amin M. Ruhul 
Published: February 2021

Abstract
The current work aims to investigate the thermo-hydraulic performances of a dynamic wall heat exchanger by varying amplitude and frequency of the oscillating waveform. The lower wall of the channel is exposed to constant heat flux, the upper insulating wall is deforming in a sinusoidal waveform, and water is taken as the working fluid. The governing partial differential equations are solved by using the Arbitrary Lagrangian-Eulerian finite element method. The study has been performed in the transient regime for up to 1.0 second. At first the effects of frequency variation over the average mass flow rate, convective heat transfer coefficient, and the average liquid temperature have been observed for a particular amplitude of the dynamic wall. It has been found that the mass flow rate of water increases linearly with increasing frequency. Convective heat transfer coefficient decreases with increasing frequency up to 50 Hz, then starts to increase notably. Interestingly, the fluctuating average liquid temperature decreases and reaches a steady-state faster with increasing frequency. To explore the effect of amplitude over heat transfer characteristics, the amplitude ratio of the sinusoidal wave is varied maintaining a constant frequency of oscillation. It has been observed that with increasing amplitude, both mass flow rate and convective heat transfer coefficient increase exponentially. Increasing amplitude ratio from 0.5 to 0.9 results in an increment in the convective heat transfer coefficient by about 5 times. Although, the average liquid temperature decreases and reaches a steady state faster with increasing amplitude, initially the peak temperature of the water is recorded for the highest amplitude.
Investigation of the Secondary Crossflow at the Rectangular Exit of a Low-Speed Sectioned Contractive Wind Tunnel
Authors: Zhang Shuo , Tian Fu , Wang Xiaofang , Gao Qiang , Sui Yongfeng , Lan Jibing , Ding Xudong 
Published: February 2021

Abstract
The low-speed rectangular exit wind tunnel with sectioned contraction is widely used. The secondary flow vortices are found at contraction exit, which would lead to the non-uniform boundary layer and influence the aerodynamic experiment accuracy. In this paper, experimental and numerical approaches are adopted so as to clarify reasons for the formation of the secondary crossflow occurring at contraction exit and take measures to control it. The conclusions can be gotten as: the secondary crossflow is formed and developed in the second (rectangular-to-rectangular) contraction, and the first (circular-to-rectangular) contraction promote the secondary flow vortices to migrate to the middle of flow field to a certain extent; the formation of the secondary crossflow is related to the static pressure gradient in the contraction. Based on the mechanism analysis results, several methods aimed to control the secondary crossflow are proposed and verified, the results can be concluded as: in terms of the rectangular-to-rectangular contraction that contracts along one direction, it is difficult to effectively control the secondary crossflow just by optimizing contraction curves and contraction ratios, while adopting the boundary layer suction can significantly improve the boundary layer uniformity; if the rectangular-to-rectangular contraction contracts in two directions, such secondary crossflow can be well controlled.