bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Equations of Motion for a Stewart Platform Under Prescribed Mount Motion
Authors: Ono Takeyuki , Eto Ryosuke , Yamakawa Junya , Murakami Hidenori 
Published: January 2019

Analytical equations of motion are critical for real-time control of translating manipulators, which require precise positioning of various tools for their mission. Specifically, when manipulators mounted on moving robots or vehicles perform precise positioning of their tools, it becomes economical to develop a Stewart platform, whose sole task is stabilizing the orientation and crude position of its top table, onto which various precision tools are attached.
In this paper, analytical equations of motion are developed for a Stewart platform whose motion of the base plate is prescribed. To describe the kinematics of the platform, the moving frame method, presented by one of authors [1,2], is employed. In the method the coordinates of the origin of a body attached coordinate system and vector basis are expressed by using 4 × 4 frame connection matrices, which form the special Euclidean group, SE(3). The use of SE(3) allows accurate description of kinematics of each rigid body using (relative) joint coordinates. In kinetics, the principle of virtual work is employed, in which system virtual displacements are expressed through B-matrix by essential virtual displacements, reflecting the connection of the rigid body system [2]. The resulting equations for fixed base plate reduce to those for the top plate, obtained by the Newton-Euler method.
A main result of the paper is the analytical equations of motion in matrix form for dynamics analyses of a Stewart platform whose base plate moves. The control applications of those equations will be deferred to subsequent publications.
A Study on Evolution of Splat Radius and Temperature in Thermal Spray Process
Authors: Dash Manpreet , Kumar Sangharsh , Bandyopadhyay Partha Pratim , Bhattacharya Anandaroop 
Published: January 2019

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process.
During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.
Disappearance of Strengthened Micro Texture of Modified 9Cr-1Mo Steel Caused by Stress-Induced Acceleration of Atomic Diffusion at Elevated Temperatures
Authors: Luo Yifan , Miura Hideo 
Published: January 2019

The change of the lath martensitic structure in the modified 9Cr-1Mo steel was observed in the specimens after the intermittent fatigue and creep tests using EBSD (Electron Back-Scatter Diffraction) analysis. The Kernel Average Misorientation (KAM) value and the image quality (IQ) value obtained from the EBSD analysis were used for the quantitative evaluation of the change in the lath martensitic texture. It was found that the lath martensitic texture started to disappear clearly after 107–108 cycles under the fatigue loading at temperatures higher than 500°C when the amplitude of the applied stress exceeded a critical value. Similar change also appeared in the creep test. The critical value decreased monotonically with the increase of the test temperature. This microstructure change decreased the strength of the alloy drastically.
In order to explicate the dominant factors of the change quantitatively, the changes of the microstructure and the strength of the alloy were continuously measured by applying an intermittent creep test at elevated temperatures. It was found that the effective activation energy of atomic diffusion decreased drastically under the application of mechanical stress at elevated temperatures. The effective diffusion length for the disappearance was about 9 μm, and this value was much larger than the initial pitch of the lath martensitic texture of about 0.5 μm, and smaller than the average size of the initial austenite grains of about 20 μm. Therefore, the stress-induced acceleration of atomic diffusion was attributed to the disappearance of the initially strengthened micro texture. The change of the micro texture caused the drastic decrease in the yielding strength of this alloy. Finally, the prediction equation of the lifetime of the alloy was proposed by considering the stress-induced acceleration of atomic diffusion under the application of mechanical stress at elevated temperatures.
The Value of Energy Flexibility: Integrating Wind Resources in New York State
Authors: Conlon Terence M. , Modi Vijay , Waite Michael B. 
Published: January 2019

This paper explores the effects of energy system flexibility on the contribution of wind generation to the New York State (NYS) electricity generation mix. First, the benefits of NYS-specific flexible hydropower are investigated. For all simulations, a mixed integer linear program minimizes net load to determine the maximum aggregate capacity factor for the installed wind power. A similar routine explores the benefits of three different types of energy flexibility: flexible supply, flexible demand, and bidirectional flexibility (i.e. energy storage). To compare across technologies, a novel method of standardizing flexibility inputs, Potential Flexible Energy (PFE), is introduced.
With 30 GW wind capacity in NYS (average electricity demand of 18.7 GW), introducing electric vehicles with an average load of 1.44 GW and daily available battery capacity of 34.5 GWh (roughly equivalent to the daily use of 3.4 million passenger EVs) increases statewide wind utilization by 840 MW (9.0% of wind potential and 4.5% of average load). Added flexibility in the form of energy storage yields similar results: with 3.2 GW charge/discharge capability and 76.8 GWh storage capacity, statewide wind utilization increases by an average of 660 MW (7.0% of wind potential and 3.5% of average load).
Because of transmission constraints and the geographic distribution of high-potential wind resources, increased wind utilization is only achieved when flexibility is added in the region where 86% of the 30 GW simulated wind capacity is located.
Improve Enterprise Resources Management Through the Usage of IoT in the Shopfloor
Authors: Cunha Adriana , Silva João 
Published: January 2019

Industrial demand has changed and present increasingly demanding requirements. Companies need to evolve and innovate to be able to go along and fulfill its customers requirements. Currently, major players have the capacity, resources and money, to install the most innovate and expensive machines, tools and devices on its shop-floor. SMEs on its side, face several challenges to manage its limited resources. SME aims to maximize the usage of the available resources to continue its activity and if possible to grow. The usage of low-cost IoT devices allow companies to monitor the usage of its resources and the quality of its products without the need to made a huge investment that wouldn’t be affordable for them.
The results presented were a result of the C2NET Project that was designed to comprehensively cover the entire supply chain considering all stages of manufacturing, distribution and sales to supply a product to market.
The results achieved were able to fulfill specific needs of the industrial partners of the project, and were validated by 6 companies from Automative, DermoCosmetics, Metalworking and OEM (Original Equipment Manufacturer) Industries from Spain, France, Portugal and Finland.[1] A Metalworking SME was used as an use case due to its complexity and diversity, although most of the achievements can be replicated in other industries, even the more traditional ones.
Dislocation Theory of Orthogonal Metal Cutting of Cu-Zn Alloys
Authors: Payton Lewis N. 
Published: January 2019

The effects of stacking fault energy and hardness on the shear process during low-speed orthogonal metal cutting were examined in a designed experiment of 1680 tests in Copper Zinc (CU-ZN) alloys. Existing shear zone models were compared to the experimental results generated by a Videographic Quick Stop method.
Analysis of the data indicates that the onset of shear plane is more properly viewed as the activation of glide plane. This in turn is a result of the available slip planes, which are a function of the materials crystalline structure, the stacking fault energy and the dislocation density (i.e., the amount of work-hardening), as constrained by the tool’s rake face angle. Merchant’s Force Diagram is revised using an extension of the existing diagram to incorporate the material’s crystalline structure, incorporating well established dislocation theory.
Computational Analysis for Validation of Blast Induced Traumatic Brain Injury and Protection of Combat Helmet
Authors: Tan X. Gary , Bagchi Amit 
Published: January 2019

Current understanding of blast wave transmission and mechanism of primary traumatic brain injury (TBI) and the role of helmet is incomplete thus limiting the development of protection and therapeutic measures. Combat helmets are usually designed based on costly and time consuming laboratory tests, firing range, and forensic data. Until now advanced medical imaging and computational modeling tools have not been adequately utilized in the design and optimization of combat helmets. The goal of this work is to develop high fidelity computational tools, representative virtual human head and combat helmet models that could help in the design of next generation helmets with improved blast and ballistic protection.
We explore different helmet configurations to investigate blast induced brain biomechanics and understand the protection role of helmet by utilizing an integrated experimental and computational method. By employing the coupled Eulerian-Lagrangian fluid structure interaction (FSI) approach we solved the dynamic problem of helmet and head under the blast exposure. Experimental shock tube tests of the head surrogate provide benchmark quality data and were used for the validation of computational models. The full-scale computational NRL head-neck model with a combat helmet provides physical quantities such as acceleration, pressure, strain, and energy to blast loads thus provides a more complete understanding of the conditions that may contribute to TBI. This paper discusses possible pathways of blast energy transmission to the brain and the effectiveness of helmet systems at blast loads. The existing high-fidelity image-based finite element (FE) head model was applied to investigate the influence of helmet configuration, suspension pads, and shell material stiffness. The two-phase flow model was developed to simulate the helium-air shock wave interaction with the helmeted head in the shock tube.
The main contribution was the elucidation of blast wave brain injury pathways, including wave focusing in ocular cavities and the back of head under the helmet, the effect of neck, and the frequency spectrum entering the brain through the helmet and head. The suspension material was seen to significantly affect the ICP results and energy transmission. These findings can be used to design next generation helmets including helmet shape, suspension system, and eye protection.
Biomaterial Models Adjustment and Comparison for Ultra-High Molecular Weight Polyethylene in Finite Element Models
Authors: Corro-Hernández Humberto , Vidal-Lesso Agustín , Ledesma Elías , Balvantín-García Antonio de Jesús 
Published: January 2019

GUR1050 is a medical grade variety of ultra-high molecular weight polyethylene (UHMWPE) intended for use on total joint prosthesis and implants. Probes of this material were characterized on a compression test following ASTM norms and lineaments.
Available data from these mechanical tests is fitted on multiple material models. Achieved results on numerical solutions of finite element modeling (FEM) of the tests are discussed, looking for the best one available in order to simulate with accuracy GUR1050 behavior, with specific interest on the load curve results, showing the pertinence of using certain models on different conditions.
It was found that the use of a bilinear isotropic hardening model assures the best fit for GUR1050 behavior in uniaxial compression under a constant strain rate.
Advanced Modeling and Experimental Validation of an Optimized Power Transformer Tank
Authors: Mendes Hélder F. G. , Coutinho Cristiano J. P. , Tavares Sérgio M. O. , Félix Luís M. R. , de Matos Agostinho N. Martins , Meireles José F. B. , Pinho António C. Marques , Teixeira Joel R. S. 
Published: January 2019

Even though the power transformers are electrical machines, their design includes several important steps with strong emphasis on mechanical engineering topics, such as the design of welded metallic structures. Indeed, the tank and its cover are typically manufactured from steel sheets or plates to which a group of stiffeners are added, with the objective of reducing the bending stress, transverse displacements and/or buckling.
The current communication presents and discusses several incremental innovations in the structural design and simulation of tanks for Core type power transformers, including: (i) optimization of the stiffeners design and welding bead volume reduction; (ii) optimization of panels curvature; (iii) simulation of the transformer tank loaded by both hydrostatic pressure and vacuum conditions; and (iv) inclusion of non-linear behavior to more accurately simulate representative structures.
Achieved numerical results are compared with obtained experimental data, to evaluate the design procedures and the potential of virtual testing of new solutions.
Influence of the Microstructure on the Creep Behaviour of Tin-Silver-Copper Solder
Authors: Ribeiro Pedro E. , Soares Delfim F. , Cerqueira Maria F. , Teixeira Senhorinha F. , Barros Daniel A. , Teixeira José C. , Capela Pauline , Macedo Francisco 
Published: January 2019

A common failure mode of electronic printed circuit boards (PCB’s) is the appearance of cold solder joints between the component and PCB, during product life. This phenomenon is related to solder joint fatigue and is attributed mainly to the mismatch of the coefficients of thermal expansion (CTE) of component-solder-PCB assembly. With today’s solder joint thickness decreasing and increasing working temperatures, among others, the stresses and strains due to temperature changes are growing, leading to limited fatigue life of the products. As fatigue life decreases with increasing plastic strain, creep occurrence should have significant impact, especially during thermal cycles and, thus, should be studied. Through the cooling phase, on the production of PCB assembly’s by the reflow technology, the hoven atmosphere temperature is adjusted in order to control the cooling rate. Narrow criteria is used so as to control the inter-metallic compounds (IMC) thickness, PCB assembly distortion and defects due to thermal shock. The cooling rate also affects solder microstructure, which has direct impact on creep behaviour and, thus, on the soldered joint reliability.
In this paper, a dynamic mechanical analyser (DMA) is used to study the influence of the solder cooling rate on its creep behaviour. SAC405 samples with two distinct cooling rates were produced: inside a hoven cooling and by water quenching. Creep tests were made on three-point-bending clamp configuration, isothermally at 25 °C, 50 °C and 75 °C and under three separate levels of stress, 3, 5 and 9 MPa. The results show that creep behaviour has a noticeable cooling rate dependence. It was also noticed that creep propensity is exacerbated by the temperature at which stresses are applied, especially for the slower cooling rates. Creep mechanisms were related to the solder microstructural constituents, namely by the amount of phases ant their morphology.
Full Scale Testing of Pulse Jet Mixer Operating Control
Authors: Moualeu Leolein , Wand Aaron , Herman Klemme , Trenidad Michaela , Hall Michael , Springer Bethany , McAdams Nathan , Holton Langdon 
Published: January 2019

A standard high-solids vessel (SHSV) concept design approach using pulse jet mixers (PJM) has been proposed by the US Department of Energy (DOE) for the Hanford Tank Waste Treatment and Immobilization Plant (WTP) as a potential replacement for several vessels that will be used to process highly radioactive waste. To assist with the evaluation of the SHSV concept, at DOE’s direction, the WTP Project recently completed qualification testing of the SHSV PJM mixing system to verify the design. Testing of the SHSV design, conducted at full scale, was split into two phases. The first phase of testing developed PJM controls that supported all operational modes under a set of most adverse fluid conditions. The second phase of testing used the PJM operating strategy, established during the first phase, to perform qualification testing to verify that the mixing system design supports the transfer, de-inventory, throughput, and sampling functional requirements of the SHSV. The different control methods that were used to operate PJMs in simulants exhibiting Newtonian and non-Newtonian rheological properties with high solids loading are presented.
The PJM system of the SHSV uses six pulse tubes distributed in a circular array. Each pulse tube (3000 liters nominal volume) is connected to a jet pump pair (JPP) by means of an air link line. The JPP powers the PJM operation by applying a vacuum to refill the PJM (suction phase), pressurizing the PJM to discharge the pulse tube content at a target velocity (drive phase), and releasing the compressed air to allow the PJM to depressurize into a ventilation system (vent phase) designed for contaminated air. A PJM control system was developed to maximize the PJM operation and minimize potential impact to the structural integrity of the vessel. The experimental results showed effective control of the system parameters. The system response demonstrated reliable control of the drive set pressure, the drive time, and synchronization. The PJM control system design also proved robust in mobilizing settled solids.
Design of Damped Structures to Increase Machine Tool Dynamical Performance
Authors: Aggogeri Francesco , Borboni Alberto , Merlo Angelo , Pellegrini Nicola , Adamini Riccardo , Taesi Claudio 
Published: January 2019

The demand of ultra-high precision (UHP) machining is growing word-wide, driving the study and development of new solutions to increase the machine tool (MT) functionalities and performance. This trend has generated a request of smart, flexible and faster MTs that are able to reduce machining time and improve the final accuracy. The material selection in MT structure design and building may play a fundamental role to satisfy the customer’s requirements. In addition, the application of innovative materials in today’s technology may solve many issues that affect the machining quality due to static, dynamic and thermal behaviors.
This paper presents a set of hybrid materials that may be used to fabricate the moving parts of a machine tool. The proposed solutions aim to guarantee lightness, capacity to damp vibrations and high stiffness limiting static and dynamic issues. The study focuses on four types of hybrid materials: sandwich structures based on Aluminium Foam, in open and closed cells configuration, sandwich panels with a corrugated core and Carbon Fiber Reinforced Plastic (CFRP) materials. A number of prototypes (milling MT ram – z axis) has been designed, manufactured and tested for high speed applications, evaluating both static and dynamic properties and highlighting potential advantages, drawbacks and new opportunities respect to conventional materials (e.g. iron, steel).
Motion Capture of the Selective Hand Picking Movements As the Basis for the Design of Mechanically Assisted Picking Tools in Coffee Plantations in Colombia
Authors: Hernandez Barbosa Jeyson Andres , Roa Prada Sebastian , Hernandez Bolivar Dario J. , Ruiz Romero Brajan Nicolas , Rueda Oscar E. 
Published: January 2019

Besides oil, coffee is one of the most traded commodities worldwide. Colombia is known as the producer of the highest quality coffee in the world, thanks to its smooth taste and aroma. One of the key elements that are responsible for the quality of Colombian coffee is its harvesting method, in which it is enforced that only mature fruits are harvested. Given the terrain conditions in which coffee trees grow, the preferred harvesting method in Colombia is selective hand picking, in which each coffee grain is individually teared off from the branch that is attached to.
This work focuses on the analysis of the motion of a human hand performing the action of manual selective coffee harvesting. The analysis is based on the data collected from a custom made motion capture system, which consists of a glove capable of sensing the angular movement of the joints, and accelerations at the tip of the fingers, by means of a set of flex sensors and accelerometers, respectively. The methods followed in this investigation include the study of the biomechanics of the hand, as applied to the motion of hand picking of coffee, which proved to be fundamental for the analysis of the experimentally measured data. After processing the experimental data, the patterns of movement done by a human coffee harvester can be simulated and replicated, which allows identifying trajectories that a good harvester follows, as compared to other harvesters, which collect smaller amounts of grains during the same period of time.
After having parameterized the motion of efficient selective hand picking, the results from this investigation serve as the basis for the design and optimization of an electromechanical tool to assist in the process of coffee harvesting, which minimizes the amount of green beans removed from the branches of the coffee trees.