bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Pre-Bending on Formability of DQ Steel and Al 5182
Authors: Memon Shabbir , Mohammed Obaidur Rahman , Lankarani Hamid M. 
Published: January 2019

The effect of the pre-bending operation on ductility can be significant in determining the limit strains of the final product. The strain path experienced in straight tube bulging is significantly different from that of elbow (tube with pre-bending), leading to a reduction in bulge height. The Tube bending introduces strain gradient both along the tube and across the tube. In this work the effect of pre-bending on limit strains during tube bulging process is predicted — and the results are compared to the limit strains of bulged tubes without pre-bending. The Finite Element (FE) model of the bending operation is developed which utilizes an explicit dynamic finite element formulation. The PAMSTAMP 2G code is used to perform the numerical pre-bend (and bulging) simulations.
Tension side of bend tube axial strain is found to be positive and hoop strain as negative and vice versa along the compression side. During the bulging, the neck usually develops perpendicular to major strain direction. During bend tube bulge test with fixed expansion and axial feed expansion of bend tubes, in both cases the crack is found to be in the axial direction.
Study on Turning of Non-Axisymmetric Three-Dimensional Curved Surfaces
Authors: Mori Taichi , Morimoto Yoshitaka , Hayashi Akio , Kaneko Yoshiyuki , Suzuki Naohiko , Hirono Ryo 
Published: January 2019

Conventional machining of complex parts having three-dimensional curved surfaces is performed in two steps using a five-axis machining center and a grinding machine. There is a problem with productivity. Therefore, we developed a CNC lathe to cope with high-speed machining. The newly developed CNC lathe has four axes (X1, X2, Z, C). In this machining, the tool on the X axis follows the curved surface synchronously with the rotation angle of the spindle. This cutting method enables machining of the three-dimensional curved surface. By adopting a linear motor for the X axis, high-speed reciprocal motion of the tool is realized, and the machining time has been reduced to approximately 1/30, as compared with the conventional milling process. In this operation, since high-response motion is required for the tool positioning, a certain profile error remains even if repeated control is applied using the linear scale.
In the present study, for the purpose of improving the contour accuracy of a three-dimensional curved surface, we report the result of compensation between the profile measurement method of workpiece and the desired profile accuracy. After machining a three-dimensional curved surface by the developed CNC lathe, a line laser displacement sensor is used to measure the workpiece profile on the machine without removing the workpiece. The position of the machining program is measured by synchronizing the controller of the CNC lathe and the line laser displacement gauge. In addition, the desired profile accuracy is improved by compensating for the error between the desired profile accuracy and the measurement result.
Research on a Mechanical Model of the Connecting and Sliding Parts in Motion for a Reciprocating Compressor
Authors: Mizobe Yu , Mori Yoshifumi , Saito Takashi 
Published: January 2019

To avoid discontinuation during long-term continuous operation in plants, a reliable monitoring system for the state diagnosis is strongly expected. However, occurring troubles of various facilities in a plant aren’t simple. We proposed a sophisticated estimation method to diagnose the state for reciprocating compressors. Our monitoring system uses both the measuring data in the factory and the analytical results based on the mathematical model, which can express the dynamic behavior about the reciprocating compressor. The mathematical model has multi degrees of freedom and the model parameters are identified to estimate the state change. To realize the reliable monitoring, we have to establish estimation and diagnosis method for any change of the operation state.
In this paper, we discuss estimation method of the rigidity in connecting and sliding portions by using the measuring data during operation of the reciprocating compressor in case of changing a connecting parts. We identified parameters of spring constant, by which one can be obtained the frequencies of eigenvalue analysis correspond to some natural frequencies determined based on an optimal problem. Moreover, we analyzed frequency responses of the model using the identified parameters and compared the frequency responses of the model with those of experimental results.
A Novel Hybrid Strategy for Multimode Operation Mapping and Feature Extraction on Data-Driven Statistical Fault Detection Methods
Authors: Pinzón Horacio , Audivet Cinthia , Alexander Javier , Torres Melitsa , Consuegra Marlon , Sanjuán Marco E. 
Published: January 2019

Fault detection and diagnosis schemes based on data-driven statistical modelling are highly dependent on an accurate and exhaustive feature extraction procedure to deliver a superior performance as a monitoring strategy. Otherwise conducted, a deficient feature extraction procedure leads to a monitoring structure widely deviated from normal operating conditions. If an operating state is not identified as it, an increment in false alarm rate would be evidenced whenever the process shifts towards that condition and the monitoring scheme triggers the abnormal condition warning. On the other hand, if two similar operating conditions could not be individualized i.e. to be identified as a single operating state, a lack of sensitivity for minor — yet typical — deviations would render a monitoring strategy with prominent misdetection rates.
Although Multimode Operational Mapping requires the proper identification of a finite set of normal process states, it is a challenging task especially for large-scale systems. Its complexity derives from a broad universe of monitoring variables, highly interactuating process units integrated over very dynamic network systems, among others. This is the case of natural gas transmission infrastructure, as it deals with variable upstream production rates, diverse consumption trends from customers, internal processes constrains, merged in a stringent operating scheme.
This paper proposes a novel strategy to address the identification and feature extraction of normal conditions on multimode operation systems. The proposed framework uses a segmentation approach based on operator’s knowledge, the Takagi-Sugeno-Kang fuzzy engine and k-means algorithm to characterize the normal operation states of the system. The results show an improvement in the performance of Principal Component Analysis during abnormal conditions detection, in addition an increase on the sensitivity of Hotelling and Q statistics.
Estimation of Hip and Ankle Visco-Elastic Parameters During Quiet Standing
Authors: Cerda-Lugo Angel , Gonzalez Alejandro , Cardenas Antonio , Piovesan Davide 
Published: January 2019

Balance control naturally deteriorates with age, so it comes as no surprise that nearly 30% of the elderly population in the United States report stability problems that lead to difficulty performing daily activities or even falling. Postural stability is an integral task to daily living which is reliant upon the control of the ankle and hip. To this end, the estimation of ankle and hip parameters in quiet standing can be a useful tool when analyzing compensatory actions aimed at maintaining postural stability.
Using an analytical approach, this work builds upon the results obtained by the authors and expands it to a two degrees of freedom system where the first two modes of vibration of a standing human are considered. The physiological parameters a second-order Kelvin-Voigt model were estimated for the actuation of the ankle and hip. Estimates were obtained during quiet standing when healthy volunteers were subjected to a step-like perturbation.
This paper presents the analysis of a second-order nonlinear system of differential equations representing the control of lumped muscle-tendon units at the ankle and hip. This paper utilizes motion capture measurements to obtain the estimates of the control parameters of the system. The dynamic measurements are utilized to construct a simple time-dependent regression that allows calculating the time-varying estimates of the control and body segment parameters with a single perturbation.
This work represents a step forward in estimating the control parameters of human quiet standing where, usually, the analysis is either restricted to the first vibrational mode of an inverted pendulum model or the control parameters are assumed to be time-invariant. The proposed method allows for the analysis of hip related movement in the control of stability and highlights the importance of core muscle training.
Numerical Examination of Jets Induced by Multi-Bubble Interactions
Authors: Mondal Joydip , Mishra Arpit , Lakkaraju Rajaram , Ghosh Parthasarathi 
Published: January 2019

Jets produced by the interaction of collapsing cavitating bubbles containing high-pressure gases can be utilized for wide variety of applications e.g. particle erosion, medical purposes (lithotripsy, sonoporation), tannery effluent treatment, etc. Among the many parameters, this jetting is largely influenced by spatial orientation of bubbles, their times of inception, relative bubble size ratio. In this context, multiple cavitating bubbles are able to generate numerous simultaneous jets, under suitable conditions, hence operating over a wider coverage area. Such multi-bubble arrangements can go a long way in enhancing the erosive impact on a target location even at cryogenic temperature (< 123 K) and hence necessitate investigation.
In this paper, different configurations of multiple-bubble interactions are numerically simulated to examine jets directed towards a target location (fictitious particle, cell etc.) using computational fluid dynamics. No phase change is considered and the effect of gravity is neglected. The transient behaviour of the interface between the two interacting fluids (bubble and ambient liquid) is modelled using VOF (volume of fluid) method.
In this paper, results obtained for different bubble configurations through numerical simulation are validated against suitable literature and further explored to assess the resulting jet effects. The time histories of interacting bubbles are presented and the consequent flow-fields are evaluated by the pressure and velocity distributions obtained. The same calculation is repeated in cryogenic environment and the results are compared. An attempt is made to approach towards an optimum arrangement and conditions for particle erosion.
Effect of Calcium Hydroxide and Water to Solid Ratio on Compressive Strength of Mordenite-Based Geopolymer and the Evaluation of its Thermal Transmission Property
Authors: Cornejo Mauricio H. , Elsen Jan , Togra Bolivar , Baykara Haci , Soriano Guillermo , Paredes Cecilia 
Published: January 2019

Mordenite-rich tuff is one of most available zeolitic rocks all over the world. Because of this, the research of natural mordenite as a raw material of geopolymeric materials can provide an almost unlimited source of solid precursor for manufacturing such building materials. Despite efforts to shed light on the behaviour of mordenite-rich tuff during geopolymeric reaction, the performance of these novel materials is barely understood. The aim of this study is to explore the effect of the content of calcium hydroxide, CH, and water-to-solid ratio, W/S, as mixing parameters on compressive strength of mordenite-based geopolymers, MBG, and its thermal conductivity.
As solid precursor was used mordenite-rich tuff and mixed with sodium hydroxide (NaOH) at 10M that kept constant during the experiment. Two experimental parameters were selected as independent variables i.e, the content of CH and water-to-solid ratio, and their levels, according to a central composite experimental design. All these designed mixes were characterized by using quantitative X-ray diffraction (QXRD), Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetry and differential scanning calorimetry (TGA-DSC), scanning electron microscopy coupled with energy dispersed spectroscopy (SEM-EDS), in addition thermal conductivity tests were also run according to standard method ASTM C177 at 9, 24, 39°C. The overall results suggested that MBG can be used as building material, however its thermal conductivity was higher than that of commercial isolate building material. The experimental design analysis indicated that the optimum water-to-solid ratio was 0.35, but in the case of the content of CH, the optimum value was not observed on this experimental range because the compressive strength increased as the content of CH increased as well. The compressive strength of MBG was observed in the range between 8.7 and 11.3 MPa. On the other hand, QXRD and FTIR showed that mordenite reacted during the geopolymeric reaction, but instead quartz, also found in zeolitic tuff, acted as inert filler.
Side Structure Integrity Research for Passenger Rail Equipment
Authors: Eshraghi Shaun , Carolan Michael , Perlman A. Benjamin 
Published: January 2019

The U.S. Department of Transportation (DOT) Federal Railroad Administration (FRA) began promulgating regulations for the structural crashworthiness of passenger rail equipment at 49 Code of Federal Regulations (CFR) Part 238 on May 12, 1999. These Passenger Equipment Safety Standards (PESS) [1] include requirements affecting the designs of sidewall structures on passenger rail equipment. The FRA’s Office of Research, Development and Technology and the DOT’s Volpe National Transportation Systems Center are conducting research to evaluate the side impact strength of Tier I passenger rail equipment designs that have been constructed according to the current side structure regulations in §238.215 and §238.217.
Following a fatal 2011 accident in which a highway semitrailer truck impacted the side of a passenger train that was transiting a grade crossing in Miriam, NV, the National Transportation Safety Board (NTSB) recommended that the FRA “develop side impact crashworthiness standards (including performance validation) for passenger railcars that provide a measurable improvement compared to the current regulation for minimizing encroachment to and loss of railcar occupant survival space” [2].
This paper describes the status of the current FRA research related to side structure integrity and describes the planned next stage of the research program which will include analyzing the performance of generalized passenger railcar structures in side impact collision scenarios. A discussion of the technical challenges associated with analyzing side impacts on passenger rail equipment is also presented.
Investigation and Modeling of Flag Generation in Honeycomb Sandwich Panel Machining
Authors: Yip-Hoi Derek M. , Gill David D. 
Published: January 2019

Light weight honeycomb structures lend themselves to important applications in aerospace. These range from aerodynamic and structural components such as wing edges, flaps, rotor blades and engine cowlings, to aircraft interior structures such as overhead luggage bins, compartment liners, bulkheads and the monument structures found in galleys and lavatory areas. Often the honeycomb is formed into a composite ply sandwich with fiberglass face sheets bonded to the honeycomb core. These panels are cut to shape using CNC routers and specially designed cutting tools. However, the quality of the cuts generated even with these special tools leaves much to be desired. The low stiffness of the structure leads to imperfections such as fraying of the cut face sheet edges and the generation of flags along the cut honeycomb edge. These impact the ease of assembly and often require manually intensive reworking to mitigate.
The cutting of honeycomb structures and sandwich panels is challenging due to low stiffness, anisotropic mechanical properties and a high proportion of interrupted cutting due to the air voids that are present. The cutting mechanics are not well understood at this time.
This paper presents findings from the study of cutting of honeycomb sandwich panels using high speed videography and correlates these with results of geometric modeling of the engagement between the cutter and workpiece. The study includes the impact of the trajectory of the tool path through the cell structures on the generation of flagging. It also reports on the effects of two different cutting tool geometries and the introduction of a lead angle on the size and structure of the flags generated. These findings present the case for a research regime similar to the one completed for solid metals, into modeling the mechanics behind machining honeycomb structures. This will help manufacturers using these materials to make better choices in the tools, cutting parameters and machining strategies that they employ in their process planning.
A Game-Theoretic Approach to Defending Nuclear Instrumentation and Control Systems From Cyber-Threats
Authors: Maccarone Lee T. , Cole Daniel G. 
Published: January 2019

Cyber-physical systems consist of interconnected physical processes and computational resources. Because the cyber and physical worlds are integrated, the system’s physical assets are vulnerable to cyber-attack. An attacker who is able to access control inputs and mask measurements can damage the system while remaining undetected. By masking certain measurement signals, an attacker may render part of the state space unobservable, meaning that it is impossible to reconstruct those states. This is called an observability attack.
A game-theoretic approach is presented to analyze observability attacks. The attacker’s strategy set includes all possible combinations of masked measurements. The defender’s strategy set includes redundant sensing and direct measurement of state variables. Attacker and defender payoffs are quantified using the responses of the observable and unobservable states. The observability attack game is analyzed for a nuclear balance of plant system. Combinations of sensor omissions are analyzed to find observability attacks with high impact and low detection. The effects of sensor augmentation are examined. A pure strategy Nash equilibrium is identified.
Mitigation of Greenhouse Gas Emissions Through the Shift From Fossil Fuels to Electricity in the Mass Transport System in Guayaquil, Ecuador
Authors: Ramirez Angel D. , Arcentales Danilo , Boero Andrea 
Published: January 2019

Climate change is a serious threat to sustainability. Anthropogenic climate change is due to the accumulation of greenhouse gases (GHG) in the atmosphere beyond natural levels. Anthropogenic GHG emissions are mostly associated with carbon-dioxide (CO2) originated in the combustion of fossil fuels used for heat, power, and transportation. Globally, transportation contributes to 14% of the global GHG emissions.
The transport sector is one of the main contributors to the greenhouse gas emissions of Ecuador. In Guayaquil, the road mass transportation system comprises regular buses and the bus rapid transit (BRT) system. Electricity in Ecuador is mostly derived from hydropower, hence incurs relatively low GHG emissions along its life cycle. Therefore, electrification of transport has been seen as an opportunity for mitigation of GHG emissions.
In this study, the effect of partial replacement of the bus rapid system fleet is investigated. Feeders have been chosen as the replacement target in five different scenarios. GHG emissions from diesel-based feeders have been calculated using the GREET Fleet Footprint Calculator tool. The GHG emissions associated with the electricity used for transportation is calculated using the life cycle inventory of the electricity generation system of Ecuador. Three energy mix scenarios are used for this purpose. The 2012 mix which had 61% hydropower; the mix of 85% hydropower and the marginal electricity scenario, which supposed the extreme case when the new demand for electricity occurs during peak demand periods.
Results indicate that mitigation of GHG emissions is possible for almost all scenarios of percentage fleet replacement and all mix scenarios. Electric buses efficiency and the carbon intensity of the electricity mix are critical for GHG mitigation.
Resolving the Electrochemical Equations of a Solid Oxide Fuel Cell for Use in Transient Simulation and Integration Into Cyber-Physical Systems
Authors: Arias Jesus E. , Haynes Comas L. , Giorges Aklilu G. 
Published: January 2019

A major challenge with complex cyber-physical systems stems from long model computational time that creates a mismatch between the model system and the physical system. The numerical modeling of solid oxide fuel cells (SOFCs) presents particular challenges due to the highly coupled nature of the underlying equations and the multiphysics needed to fully resolve their behavior during a transient event. To this end current approaches revolve around splitting the computational efforts into resolving temperature effects and resolving electrochemical effects. Current methods employed for the transient simulation of an SOFC for implementation in the Hybrid Performance (HyPer) facility cyberphysical plant at the National Energy Technology Laboratory reveal a distinct need for accelerated results with a high degree of stability. To this aim, an investigation into the computational time for the code reveals that the underlying electrochemical algorithm takes an order of magnitude more time than its thermal counterpart and has a tendency to vary in terms of iteration time and as such a rework of the underlying system is proposed.
The primary method for accelerated electrochemical algorithm solutions is to employ higher order root finding recipes for the resolution of the highly coupled electrochemical equations. This is done with the intention to reduce the overall number of subiterations necessary for resolving voltage, current density, and species concentration, properties of the fuel cell that are all directly coupled and require nested iterative approaches. The overall objective of this approach is an order of magnitude reduction in calculation time without sacrificing stability and increasing accuracy. Specific approaches involve using both bounded and unbounded techniques, such as the False Position method and the Secant method (or if applicable Newton-Raphson) respectively, the drawbacks being slower convergence for False Position and instability for the Secant or Newton-Raphson methods.
Current preliminary results on simplified versions of the parent functions involved for electrochemical calculations indicate a reduction in computational steps by a factor of two for the secant method and a factor of three for Newton-Raphson. When implemented into new modified electrochemical algorithms, the results indicate a possible order of magnitude reduction in calculation time.