bluuebunny/crossref_metadata_2025 huggingface dataset:
B‐cell lymphoma with Mott cell differentiation in a cat
Authors: Kanehara Tomomi , Matsui Naoko , Murakami Mami , Maruo Kohji , Mori Takashi , Hirata Akihiro , Yanai Tokuma , Sakai Hiroki
Published: March 2016

A 12‐year‐old, male castrated Domestic Shorthair cat was presented to Animal Medical Center of Gifu Univeristy with anorexia and vomiting. Physical examination revealed an enlarged left tonsil and right mandibular lymph node (approximately 2–3× the normal size), and a submucosal mass on the right side of the epiglottis (1.5 × 2.0 cm). On computed tomography images, an enlarged left tonsil, and enlarged right mandibular, right pharyngeal, and left and right cervical lymph nodes were observed. Cytologic examination of smears of tonsil and lymph nodes revealed numerous medium‐ to large‐sized neoplastic lymphoid cells, approximately half of which contained one or several light‐blue homogenous globoid cytoplasmic inclusions (5–10 μm), which stained magenta with periodic acid–Schiff (PAS) stain. Histopathologic examination of the left tonsil revealed diffuse proliferation of medium‐ to large‐sized neoplastic lymphoid cells effacing the original lymphoid architecture. Half of the cells contained one or several eosinophilic globoid cytoplasmic inclusions, which stained magenta with PAS and showed positive immunohistochemical reactions for immunoglobulin M (IgM) and λ light chain. Neoplastic lymphoid cells were also CD20+, Pax5+, and MUM1+, and CD3−. Thus, the neoplastic lymphoid cells expressed a B‐cell immunophenotype, and the globoid cytoplasmic inclusions represented an aberrant IgM λ light chain accumulation, similar to Russell bodies. B‐cell lymphoma with Mott cell differentiation was diagnosed based on cytologic, histopathologic, and immunohistochemical features. This is the first report of B‐cell lymphoma with Mott cell differentiation in a cat.
Activation of lysosomal P2X4 by ATP transported into lysosomes via VNUT/SLC17A9 using V‐ATPase generated voltage gradient as the driving force
Authors: Zhong Xi Zoë , Cao Qi , Sun Xue , Dong Xian‐Ping
Published: March 2016

Key points

SLC17A9 proteins function as a lysosomal ATP transporter responsible for lysosomal ATP accumulation.

P2X4 receptors act as lysosomal ion channels activated by luminal ATP.

SLC17A9‐mediated ATP transport across the lysosomal membrane is suppressed by Bafilomycin A1, the V‐ATPase inhibitor.

SLC17A9 mainly uses voltage gradient but not pH gradient generated by the V‐ATPase as the driving force to transport ATP into the lysosome to activate P2X4.

The lysosome contains abundant ATP which plays important roles in lysosome functions and in cell signalling. Recently, solute carrier family 17 member 9 (SLC17A9, also known as VNUT for vesicular nucleotide transporter) proteins were suggested to function as a lysosomal ATP transporter responsible for lysosomal ATP accumulation, and P2X4 receptors were suggested to be lysosomal ion channels that are activated by luminal ATP. However, the molecular mechanism of SLC17A9 transporting ATP and the regulatory mechanism of lysosomal P2X4 are largely unknown. In this study, we report that SLC17A9‐mediated ATP transport across lysosomal membranes is suppressed by Bafilomycin A1, the V‐ATPase inhibitor. By measuring P2X4 activity, which is indicative of ATP transport across lysosomal membranes, we further demonstrated that SLC17A9 mainly uses voltage gradient but not pH gradient as the driving force to transport ATP into lysosomes. This study provides a molecular mechanism for lysosomal ATP transport mediated by SLC17A9. It also suggests a regulatory mechanism of lysosomal P2X4 by SLC17A9.
Statistical Significance and Hypothesis for Friction Factor Correlations of Non-Newtonian Crude Oils in Pipelines
Authors: Kamel Ahmed H. , Shaqlaih Ali S. , Ibrahim Essam A.
Published: March 2016

In pipelines, non-Newtonian fluids are generally pumped under turbulent flow conditions where frictional pressure losses are required for hydraulic design. The friction factor is a crucial parameter in calculating frictional pressure losses. However, determination of the friction factor is a decisive challenge, especially for turbulent flow of non-Newtonian fluids. This is mainly due to the large number of friction factor equations and the precision of each.

The main objective of the present paper is to evaluate the published friction factor correlations for non-Newtonian fluids over a wide range of friction factor data to select the most accurate one. An analytical comparative study adopting the recently introduced Akaike information criterion (AIC) and the traditional coefficient of determination (R2) is conducted. Data reported by several researchers are used individually and collectively.

The results show that each model exhibits accuracy when examined with a specific data set while El-Emam et al. model proves its superiority to other models when examining the data mutually. In addition to its simple and explicit form, it covers a wide range of flow behavior indices and generalized Reynolds numbers.

It is also shown that the traditional belief that a higher R2 corresponds to better models may be misleading. AIC overcomes the shortcomings of R2 as it employs the parsimonious principle to trade between the complexity of the model and its accuracy not only to find the best approximating model but also to develop statistical inference based on the data. Although it has not yet been used in oil and gas industry, the authors present the AIC to initiate an innovative strategy that has been demonstrated in other disciplines to help alleviate several challenges faced by professionals in the oil and gas industry. Finally, a detailed discussion and models’ ranking according to AIC and R2 is presented showing the numerous advantages of AIC.
An Anaytical Prediction of Period-1 to Chaos in a Periodically Forced, Damped, Hardening Duffing Oscillator
Authors: Guo Yu , Luo Albert
Published: March 2016

In this paper, periodic motions of a periodically forced, damped Duffing oscillator are analytically predicted by use of implicit discrete mappings. The implicit discrete maps are achieved by the discretization of the differential equation of the periodically forced, damped Duffing oscillator. Periodic motion is constructed by mapping structures, and bifurcation trees of periodic motions are developed analytically, and the corresponding stability and bifurcations of periodic motion are determined through eigenvalue analysis. Finally, from the analytical prediction, numerical results of periodic motions are presented to show the complexity of periodic motions.
Bifurcation Trees of a Periodically Forced, Two-Degree-of-Freedom Oscillator With a Nonlinear Hardening Spring
Authors: Luo Albert C. J. , Yu Bo
Published: March 2016

In this paper, analytical solutions of periodic motions in a periodically forced, damped, two-degree-of-freedom oscillator with a nonlinear hardening spring are obtained. The bifurcation trees of periodic motions are presented, and the stability and bifurcation of the periodic motion are determined through the eigenvalue analysis. Numerical simulations of stable period-1 and period-2 motions in the two-degree-of-freedom systems are presented, and the harmonic amplitude spectrums are presented to show the harmonic effects on periodic motions, and the accuracy of approximate analytical solutions can be estimated through the harmonic amplitudes.
Ascertaining Affective Domain in Engineering: A New Learning Concept
Authors: Wadhwa Sujata , Barlow Audrey , Jadeja Siddharth
Published: March 2016

Engineering Education has always been focusing on the development of technical skills since decades. Technological advancement and digitalization have enabled the educators to implement various teaching pedagogies for the Digital Natives [1]. According to the World Bank report on the employability and skill set of newly graduated engineers in India, the core employability skills like self-discipline, reliability, self-motivation, team work, willingness to learn, flexibility, empathy, understanding and taking instructions for assignments with the weightage of 4.27 and communication skills with the weightage of 4.01 are prioritized much more than the professional skills with the average of 3.91 [2].

The three skills groups identified by The World Bank, partly underpinned by the tripartite conceptualization of learning as cognitive, psychomotor and affective domain of Bloom’s taxonomy are an important source of investigation for teaching learning pedagogy [3].

The engineers always play a critical role in the development of the society which demands from them critical thinking, problem solving, collaboration skills, decision making, communication skills, integrity, realizing human values, being compassionate and accountable etc. These skills enable them to work for the welfare of mankind. Much of the research has emphasized to have such types of skills among the engineers but increased demand and increased number of qualifying engineering graduates have led to poor quality of education and consequently skill shortage.

This paper presents a unique pedagogical framework focusing on the development of affective domain among the first year engineering students. The authors ascertain that the cognitive domain has been always emphasized in engineering education, more than the affective domain, albeit affective domain is substantial for engineers. The affective domain, arguably the most complex, [4] is about students’ values, attitude, emotions, appreciation etc. The authors have adopted a new hybrid learning concept offering a conducive, student-centered learning environment that motivates and enhances students’ engagement with their peers, friends, teachers and the institute. This paper discusses a new learning concept, specific to engineering education for the smooth transition of the students to real contributors and life-long learners by acquiring some indispensable 21st century skills.
Feature Based Classification of Melanoma From Skin Images
Authors: Guo Jiexin , Menon Prahlad G.
Published: March 2016

Melanoma is one of the most deadly skin cancers and amounts for ∼79% of skin cancer deaths. Early detection and timely therapeutic action can reduce mortality owing to melanoma. In this study, we demonstrate the feasibility of our in-house skin image classification framework, trained based on a library of normal as well as pathological skin images, for automatic feature extraction and detection of melanoma. The described framework begins with active contour segmentation the skin images followed by extraction of both color and texture features from the segmented image and employs a neural network classifier to for trained identification of melanoma cases. Training and testing was conducted using a 10-fold cross validation strategy and led to 88.06% ± 1.65% accuracy in classification of melanoma images.
Effect of Precipitation Hardening on Particle Reinforced Aluminum Alloy Composites
Authors: Xavior M. Anthony , Ashwath P. , Rajendran R.
Published: March 2016

In this research work two different composites are manufactured using Aluminum Alloy (AA) 2900 and 2024 as matrix with SiC and Al2O3 as reinforcement material through powder metallurgy technique. The objectives of this research work are to determine the influence of the sintering duration on the properties of composites and to understand the effect of different aging time on the properties of the composites. The weight percentage of reinforcement materials, sintering duration and aging duration were considered as variable parameters in this experimental work. The metal powder and the reinforcement are blended in high energy ball mill and compacted in Universal Testing Machine at a constant load of 500Mpa to fabricate green compacts. The green compacts were subjected to microwave sintering at 500°C for 60 minutes as per the design of experiments. The sintered samples are quenched in water till it reaches the temperature close to room temperature and loaded again into the sintering furnace for artificial aging (for a varying duration of 60 & 120 minutes). This will allow the samples to form CuAl2 and CuMgAl2 precipitates which are confirmed using SEM and X-ray diffraction studies. Hardness studies are carried out using Rockwell and Brinell hardness tester respectively.
Activity Based Learning: Overcoming Problems in Implementing OBE in Engineering Education During Transition Phase
Authors: Wadhwa Sujata , Barlow Audrey , Jadeja Siddharth
Published: March 2016

National Board of Accreditation, India has become the signatories of the Washington Accord adopting outcome based education guidelines in order to impart the quality education in engineering institutes [14]. Outcome Based education (OBE) requires thorough assessment and evaluation of the students individually, with special focus on the overall development of the students. OBE is based more on student centric learning and less on the role of a faculty or the content part (taught) which requires modifications at grass root level in the University teaching learning scheme. It demands a transition of a lecturer into a facilitator. It also requires a paradigm shift in teaching learning process in engineering education (EE) system as OBE focuses more on development of all the three learning domains, contradictory to the traditional teaching learning process which focuses more on development of the cognitive domain and psychomotor domain only.

According to the World Bank Report, the modern volatile and complex world demands from the engineers the core employability skills like critical thinking, problem solving, creativity and innovation, collaboration skill, communication skill which must be developed and honed during the course tenure so that they could become competent global engineers [2] [3].

This paper brings forth the out of box thinking and implementation concept of the OBE for UG program, through activity based students’ engagement, specially designed activity to achieve Programme Educational Outcomes (PEOs), Programme Outcomes (POs) and Course Learning Outcomes (CLOs). It intends to solve the problem of large classes through the implementation of the FLIP classroom model. A six month activity based teaching learning model had been adopted for different streams, involving more than 1500 engineering students. The outcome/s achieved by each activity had been termed as Activity Outcomes (AOs). This paper discusses the problems encountered during the implementation of OBE frame work for large class [4] in context with Indian environment and also strives to provide some methods to implement activity based learning to achieve desirable outcomes.
Study on the Effect of Clamping Sequence on Bulk Stress Redistribution of Long Edge
Authors: Wang Hua , Liu Jun
Published: March 2016

For a given assembly process, fixture-related operations contribute to the dimensional variations of compliant part. When the manufactured components are within the specified tolerances, the bulk stresses distribution of the assembly are respected. In addition to fixture geometric errors and clamping forces, the clamping sequence can also affect part bulk stress redistribution. This paper presents a numerical simulation of bulk stress redistribution in a long edge assembling with different clamping sequences. A finite element model of the plate with residual stresses after quenching and stretching is constructed. The edge is milled from the numerical plate, and the edge with the initial deformation and residual stresses is ready for clamping. The contact model between the clamper and edge is constructed to simulate the practical clamping process, especially considering the friction contact between the clamper and edge. Then the edge is virtually clamped in different clamping sequences, and its deformation and bulk stresses are obtained. The simulation results show that there are differences in the stains of edge under different clamping sequences, and the edge’s bulk stresses under different clamping sequences are different with each other also. The proposed numerical model could predict the edge’s bulk stresses under different clamping sequences. It will help obtaining optimal stresses of the edge by certain clamping sequence, and help systematically improving the compliant assembling efficiency in civil aircraft industry.
Thermo Mechanical Analysis of Ultrasonic Welding of Metal Joints Under Different Control Parameters
Authors: Yi Dalong , Zhang Hui , Zheng Lili
Published: March 2016

Ultrasonic welding is a complex process combining the processes of interface friction, heat transfer, plastic deformation heating, and atom diffusion and so on. Even though much work has been performed to understand ultrasonic welding process, the key characteristic process parameters of ultrasonic welding process and the key control parameters for the bond quality are still questions. Based on the interactions of bond factors and previous research of ultrasonic welding process, we believe that plastic deformation and temperature which represent the energy and strain condition at bonding interface are the key process parameters related to bond. A 3-D thermal-mechanical finite element model is built to analyze the thermal and mechanical files of ultrasonic welding process of two types of aluminum alloys under different control parameters. A possible mechanism between bond quality and control parameters based on max temperature and max plastic deformation of temperature-strain map of simulation is presented.
Simple Heat Transfer Experiment to Evaluate the Solid/Liquid Phase Change Thermal Energy Storage System
Authors: Siahpush Ali , O’Brien James , Crepeau John
Published: March 2016

A detailed experimental freezing study, designed for undergraduate students, has been carried out to evaluate the heat transfer performance of a solid/liquid phase-change thermal energy storage system. The test vessel system, experimental procedure and results, and analytical solutions are discussed. The phase-change material (PCM) is contained in a vertically oriented test cylinder that is cooled at its outside boundary, resulting in radially inward freezing. Detailed quantitative time-dependent volumetric temperature distributions and freeze-front motion and shape data were experimentally obtained. To fully understand the behavior of the eicosane, four freezing tests were performed with different temperature set points as low as 10°C.

In the analysis, results of a test in which molten eicosane, initially at 50°C, was solidified and brought to a final temperature of 10°C are presented. In the freezing case study, a mathematical model based on a one-dimensional analysis, which considered heat conduction as the only mode of heat transfer was developed. The phase-change medium, 99% pure eicosane (C20H42) was chosen as the PCM. Eicosane is desirable because its fusion temperature is just slightly higher than ambient temperature (36.5°C), which is convenient for phase-change experimentation. Low-temperature heating can be used to melt the PCM and ambient-temperature cooling can be used to re-freeze it.

To evaluate the inward radius of fusion, several analytical and experimental approaches were considered. These approaches were (1) experimental method; (2) conduction model; (3) integral method; and (4) cumulative heat transfer method. Comparison of these methods reveals excellent agreement. In most cases, the heat transfer estimated from the freezing-front analysis was slightly higher than the heat transfer evaluated from the time-series data. The largest discrepancy occurs at fifty minutes into the experiment (10.7%).
Geometrical Effects of an Entrapped Bubble on Pore Shape in Solid
Authors: Hsiao S. Y. , Wei P. S.
Published: March 2016

The shape of a pore which results from a bubble entrapped by a solidification front is predicted in this work. Pore formation and its shape in solid influence not only microstructure of materials, but also contemporary issues of various sciences of biology, engineering, foods, geophysics and climate change, etc. This work extends previous models by accounting for realistic mass, momentum and energy transport across a self-consistently determined shape of the bubble cap beyond the solidification front. Accurate determination of contact angle from a realistic shape of the cap is required to predict the relevant shape of the pore in solid. The results shows that an increase in Bond number and decrease in initial contact angle decrease radius and length of the pore and time for bubble entrapment. The predicted growth and entrapment of a tiny bubble as a pore in solid are found to agree with experimental data. A realistic prediction and control of the pore shape in solid has therefore been obtained.
Ultrasound Effect on Droplet Evaporation
Authors: Protheroe Michael D. , Al-Jumaily Ahmed M.
Published: March 2016

This paper investigates the effect of an ultrasound field on the evaporation of water droplets into an air stream flowing along a conduit. The air and droplet mixture (aerosol) is passed through an intense ultrasound field, generated in a cylindrical sonotrode, in an effort to accelerate the droplet evaporation process. The improvement in droplet evaporation was evaluated by measuring changes in the droplet size distribution and changes to the air humidity and temperature. It was found that at high power levels the droplets were rapidly and completely vaporized. At power levels in the 2–20 W range there was a significant increase in droplet evaporation, up to 28%, but also some droplet coalescence occurred. The mechanism for this improvement was thought to be a result of enhanced convection heat and mass transfer processes and the input of heat energy into the aerosol. This study has demonstrated that an ultrasound field does improve water droplet evaporation.
CFD Analysis of Aerodynamic Coefficients in Labyrinth Brush Seal
Authors: Wei Yuan , Chen Zhaobo , Dowell Earl H.
Published: March 2016

The aerodynamic force between a bristle pack and a rotor should be considered in order to predict the stability of a rotor brush seal system. The high pressure flow region in a brush seal makes the interaction of bristle pack, leakage flow and rotor complicated. It provides a challenge to the study of rotor brush seal system dynamic characteristics. To analyze the rotordynamic coefficients of a rotor brush seal system, a 3D CFD rotor labyrinth brush seal computational model was created using Reynolds-averaged Navier-Stokes (RANS) solutions coupled with a non-Darcian porous medium model. The results show that for the same geometry parameters the radial force rises when the pressure ratio increases, the tangential force rises when the pressure ratio increases, and the radial force is much greater than the tangential force. And the flow leakage will increase when the pressure load increases and the mass flow rate increases with the clearance increase. Direct and cross-coupled stiffness and direct damping and cross-coupled damping under different operating condition are discussed. The direct damping and cross-coupled damping both increase when the clearance increases. The cross-coupled stiffness will increase when the inlet pressure increases.
Robust Parameter Design of Derivative Optimization Methods for Image Acquisition Using a Color Mixer
Authors: Kim HyungTae , Kim SeungTaek , Jin KyungChan , Kim Jongseok , Lee SungHo
Published: March 2016

A tuning method was proposed for automatic lighting (auto-lighting) algorithms derived from the steepest descent and conjugate gradient methods. The auto-lighting algorithms maximize the image quality of the industrial machine vision by adjusting multiple-color light emitting diodes (LEDs), usually called color mixers. Searching for the driving condition for achieving maximum sharpness, which influences image quality, using multiple color LEDs, is time-consuming. Hence, the steepest descent and conjugate gradient methods were applied to reduce the searching time for achieving maximum image quality. The relationship between lighting and image quality is multi-dimensional, non-linear, and difficult to describe using mathematical equations. Hence the Taguchi method is actually the only method that can determine the parameters of auto-lighting algorithms. The Taguchi method was applied to an inspection system consisting of an industrial camera, coaxial lens, color mixer, image acquisition device, analog interface board, and semiconductor patterns for target objects. The algorithm parameters were determined using orthogonal arrays and the candidate parameters were selected by increasing the sharpness and decreasing the iterations of the algorithm, which were dependent on the searching time. After conducting retests using the selected parameters, the image quality was almost the same as that in the best-case parameters with a smaller number of iterations. The Taguchi method will be useful in reducing time-consuming tasks and the time required to set up the inspection process in manufacturing.
Tornado-Compatible Mechanical Aortic Valve Prosthesis: Experimental and Clinical Application of Tornado Technology
Authors: Gorodkov Alexander , Kiknadze Gennady , Agafonov Andrey , Zhorzholiany Shota , Krestinich Ivan , Zazybo Nikolay , Bockeria Leo
Published: March 2016

Currently used mechanical heart valve prostheses does not fully restore the function of the valve and require aggressive anticoagulation therapy. One of the reasons leading to the prostheses disfunction is neglecting of hydrodynamic compatibility with the blood flow pattern Studies of the hydrodynamic structure of the blood flow in the heart and aorta are being performed in the Bakulev Center for Cardiovascular surgery since 1992. It has been shown that blood flow, generated in the left ventricle corresponds to the structure of self-organizing tornado-like flows described by the exact solution of unsteady hydrodynamic equations for this class of flows, published in 1986. The previous attempts to adapt the geometry of prosthetic heart valve to the swirling blood flow were not successful since there were no any quantitative criteria of the flow structere. A new model of a mechanical aortic valve — Tornado-compatible valve (TCV) (patent RU 2434604 C1), has the lumen completely free from any kind of obstacles that could disrupt the flow pattern. The valve consists of a body and three cusps which profile is adopted both to the flow in Aorta, and to the flow in Sinuses when the valve is closed. The standard hydrodynamic testing of this valve has shown its significant advantage compared with other valve types. A special testing was developed using the original bench which generates the Tornado-like jet. For this a converging channel was worked out, which profile corresponds to the streamlines of Tornado-like flow, calculated from the exact solution. The resulted jet manifested all principal properties of Tornado: laminar “glass-transparent” jet without any visible perturbations in the flow core. Several valve types were testing using this bench. TCV did not affected the jet structure, and time of water flowing out. The valve was implanted in the pig without anticoagulant administration. According to echocardiography and coagulation control the valve function was satisfactory up to ten months of observation. In the autopsy the luminal surface of outflow part of the left ventricle, and the ascending aorta were free of thrombi and pannus formation. The clinical implantation in the patient with aortic stenosis was performed. The follow-up period is 4 years.
Prediction of Reliability in Friction Welded Dissimilar Joints by Weibull Distribution
Authors: Balasubramanian Manickam , Kumar Ramalingam
Published: March 2016

The reliability of experimental data obtained in friction welded titanium alloy and stainless steel with copper interlayer by using various interlayer thicknesses and upset time are investigated using the maximum likelihood method for the estimation of the Weibull parameters of the results. The results indicate that among the various process parameters, interlayer thickness was significant. Further the reliability of the tensile strength was estimated using weibull distribution. Using this technique in conjunction with the experimental data, we can predict the output, in this case tensile strength more accurately and minimize their impact. Titanium alloy when directly bonded to stainless steel, improper bonding happens. Hence an interlayer in the form of copper is added to have successful joints.
Reduced Order Model of Frequency Response of Superharmonic Resonance of Electrostatically Actuated MEMS Resonators
Authors: Caruntu Dumitru I. , Reyes Christian
Published: March 2016

This paper deals with superharmonic resonance of electrostatically actuated MEMS resonator sensors. The system consists of a MEMS cantilever on top of a parallel ground plate. An AC voltage of frequency near one fourth the natural frequency of the resonator provides the electrostatic force of actuation. The frequency response of the superharmonic resonance of the structure is investigated using two term Reduced Order Model (ROM) method.
Motion Tuning Method of Linear Axes and Rotary Axis Under a Constant Cutting Speed Vector at End-Milling Point With a Five-Axis Controlled Machining Center
Authors: Suzuki Takamaru , Ikegami Takakazu , Akai Takayuki , Hirogaki Toshiki , Aoyama Eiichi , Ogawa Keiji
Published: March 2016

Recently It is difficult to maintain the high surface quality ingenerating curved surface shape under five-axis controlled end-milling. In this study, we aimed at maintaining feed speed vector at milling point by controlling two linear axes and a rotary axis with a five-axis machining center, to improve machined surface quality and suggested a method for solving shape error of machined workpiece considering differences of three axes’s sarvo characteristics. As the results, it could be seen that shape error greatly decreased based on the proposed method.
Dynamic Parameters Identification of Structural Laminated Glass
Authors: Clementi Francesco , Consolini Laura , Lenci Stefano
Published: March 2016

In this work, we address experimentally the determination of the dynamical properties, in particular natural frequencies and damping factors, of laminated structural glass. Various specimens, coming from different productions and manufactures, are investigated. Damped free vibrations experiments are performed, where the excitation is provided by an instrumented hammer. The boundary conditions are free-free (the specimens lay on a very flexible sponge substrate). The dynamical characteristics are determined by last squares fitting of time histories, a technique that is very simple, fast and provides very good results. Finally, two theoretical models (a two-layer beam model and a 2D finite element model) are employed to interpret the experimental results.
Modelling and Experimental Investigation of Compressor Plant Operation Under Unsteady Conditions
Authors: Chukanova Ekaterina , Stosic Nikola , Kovacevic Ahmed
Published: March 2016

Compressor plants operate continuously or frequently at unsteady operational conditions. This is due to pressure fluctuations within the plant, variable flow demand, or unsteady inlet conditions, as well as compressor shaft speed variations. Also, following demand, the compressor plants often work intermittently and they frequently start and stop.

An experimental and analytical study of a screw compressor plant operating under unsteady conditions has been carried out. For this purpose the one dimensional model of the processes within a compressor was extended to include other plant components. This was based on the differential equations of the conservation of mass and energy. The results derived from the model have been verified by experiment in order to obtain a reliable tool that can simulate a variety of scenarios which may occur in everyday compressor plant operation.

The analytical model was then extended to demonstrate the whole plant transient operation when a screw compressor is connected through connecting pipes with storage tanks, control valves and heat exchangers in a complete system.
Accelerating RBF-Based Mesh Deformation by Implementing an Agglomeration Strategy
Authors: Strofylas Giorgos A. , Lygidakis Georgios N. , Nikolos Ioannis K.
Published: March 2016

During the past decade Radial Basis Functions-based mesh deformation techniques have been emerged as an indispensable tool of numerical simulations entailing grid transformation. Despite their important contribution to such problems, they suffer from a significant drawback; they call for relatively excessive memory and computation time requirements. A remedy to this deficiency seems to be the selection of a reduced set of surface nodes, to be used as RBF’s centers; an equations’ system with decreased dimensions is obtained in that way. In this paper a new methodology for such a reduced surface point selection is proposed, considering agglomeration of surface nodes’ control volumes. It relies on the strategy followed by the corresponding multigrid methods aiming to accelerate numerical solutions of fluid flow, radiative heat transfer, etc., problems. The developed merging procedure resembles the advancing front technique, as it begins from regions with surface discontinuities extending successively to the rest of the boundary domain. The proposed algorithm is assessed against a test case considering parabolic deformation of the wing of the DLR-F6 aircraft model; its potential to effectively generate deformed grids in terms of accuracy and efficiency is demonstrated, despite the notable reduction of RBF’s centers.
An Energy-Based Residual Stress Field Reconstruction Approach Using Limited Measurements
Authors: Liu H.-B. , Li Y.-P. , Wang Y.-Q. , Sheng X.-J.
Published: March 2016

To characterize the residual stress distribution is very crucial for workpiece fatigue lifetime and structural integrity assessment. An energy-based residual stress field reconstruction approach using limited measurements is proposed. Firstly, the Ferguson spline interpolation technique is employed as the stress interpolation base of the 2-order stress tensor. Then, an initial stress field can be reconstructed using the overall boundary conditions by minimizing strain energy. Further, the stress distribution is modified according to strain compatibility equation. At last, a typical stress unit from the artificial stress field constructed by FEM, was picked up as an input set to verify the validation of the developed model and algorithm numerically. It was demonstrated that the energy-based scheme was efficient and reliable to reconstruct the residual stress field from limited measurements.
Tensile and Fatigue Behavior of Direct Metal Laser Sintered (DMLS) Inconel 718
Authors: Kelley Paul F. , Saigal Anil , Vlahakis James K. , Carter Andrew
Published: March 2016

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, end-use parts, particularly using metals. In order for these parts to be designed to function both safely and effectively, it is necessary to have a thorough understanding of the mechanical behavior of materials produced via the AM process.

This research focuses on characterizing Inconel 718 produced via the Direct Metal Laser Sintering (DMLS) process. Specimens from three orthogonal build orientations were tested as both machined and as-fabricated specimens. Surface roughness was evaluated using non-contact profilometry. Tensile testing was performed in order to characterize material yield strength. Finally, high cycle fatigue (HCF) testing was conducted on a rotating beam apparatus.

Results show that the measured elastic modulus of the as-fabricated material was 162.7 GPa for the in-plane build orientation and 72.1 GPa for the vertical build orientation. In addition, the measured fatigue strength of horizontal build orientations was greater than that of specimens built in a vertical orientation. Furthermore, it was found that the fatigue lives of the machined specimens were at least 7 times greater than those of as-fabricated specimens.
Case Study Using Open Source Additive Manufacturing (AM) Technology for Improved Part Function
Authors: Kasture Pranit Vijay , Deole Prasad , Irwin John L.
Published: March 2016

The purpose of this study is to validate the design of plastic PLA extruded everyday use parts created in open source 3D printers, and to provide examples of design alterations so a 3D printed part will function similar to the OEM component. The methodology begins with selection of a common everyday use component that may fail under a load and need replacement. As a test specimen an aluminum coat hook is purchased, measured, modeled with 3D CAD software, analyzed and physically tested. Using AM a coat hook with identical specifications is created on a Delta style RepRap 3D printer with PLA as a material in the orientation providing the maximum strength. The 3D printed coat hook is analyzed using finite element analysis as well as physically using a loading apparatus test with identical loading and supporting conditions. The software used for the experimentation and data collection are NX9, ANSYS and NI LabVIEW. Material physical properties of open source 3D printed PLA parts obtained from tensile testing indicate that the strength of a 3D printed part will be less than that of an aluminum OEM part. Initial finite element analysis reveals the Coat Hook 3D printed using PLA deflects almost 20 times that of the OEM aluminum component when subjected to an identical load. This indicates that the component cannot be replaced with identical specifications even if there was a large factor of safety applied to the coat hook design. As a result of the study, part reinforcement features are proposed for redesign of a 3D printed part to perform as well as the OEM part under a similar load. Additional part redesigns utilizing these reinforcement features include shelf support brackets and solar photovoltaic mounting bracket systems.
Active Magnetic Bearings for High Speed Spindle Design With Nonlinear Time-Frequency Control
Authors: Liu Mengke , Suh C. Steve
Published: March 2016

A novel concept applicable to the control of spindles at high speed is developed by using active magnetic bearings (AMBs) that are non-contact and of low vibration. Though former studies are abundant and demonstrating promising potentials, however, two major issues hamper the broader application of AMBs. The first is the disregard for the gyroscopic effect and geometry coupling that influence the magnitude as well as distribution of the electromagnetic force in AMBs. Not considering the two has a significant implication for the proper control of AMBs. This paper considers the gyroscopic effect and explores the geometry coupling of the electromagnetic actuators to the formulation of a comprehensive nonlinear AMB-rotor model. The model provides the basis for the creation of a novel time-frequency control algorithm whose derivation requires no linearization or mathematical simplification of any kind, thus allowing the model system to retain its true fundamental characteristics. Unlike proportional-integral-derivative (PID) controllers that are dominant in most if not all AMB configurations, the controller developed for the research is inspired by the wavelet-based nonlinear time-frequency control methodology that incorporates the basic notions of online system identification and adaptive control. Due to the fact that dynamic instability is characterized by time-varying frequency and non-stationary spectrum, the control of AMBs needs be executed in the time and frequency-domain concurrently to ensure stability and performance at high speed. Wavelet filter banks and filtered-x least-mean-square (LMS) algorithm are two of the major salient physical features of the controller design, with the former providing concurrent temporal and spectral resolutions needed for identifying the nonlinear state of motion and the latter ensuring the dynamic stability of the AMB-rotor system at extremely high speed. It is shown that the vibration of the rotor is unconditionally controlled by maintaining a mandatory 0.55 mm air gap at 187,500 rpm subject to a tight spatial constraint (tolerance) of the order of 0.1375mm, which is the 25% of the air gap.
Challenges Moving From Physical Into Virtual Verification of Sheet Metal Assemblies
Authors: Lindau Björn , Rosenqvist Mikael , Lindkvist Lars , Söderberg Rikard
Published: March 2016

Within industry there is an established need for enhanced virtual tools and methods to improve product tolerance setting and conditions for successful manufacturing of non-rigid assemblies. A significant amount of research has been performed in the area, but there is still a need to find efficient working methods and the right preconditions in practice.

This paper reports experiences and findings made during recently performed virtual matching and trimming of sheet metals in a real automotive industrial setting. A case is presented, demonstrating the possible use of the Computer Aided Tolerance (CAT) tool RD&T, (Robust Design & Tolerancing), in order to predict the geometric behavior of non-rigid parts when assembled. Scanned parts are used as input and the analysis is performed using the described virtual platform instead of physical type-bound rigging equipment traditionally used for conflict, gap and final springback analysis. The proposed working procedure, and the reasons behind it, are presented. The need of additional radical and incremental innovations is brought into light, in order to make earlier predictions in the product realization process. Furthermore, it is discussed whether the necessary changes in working procedures can impose innovation barriers in the future.
A Semantic Enrichment Approach Based on the Vector Space Model Supporting Collaboration in the Manufacturing Domain
Authors: Figueiras Paulo , Melo Raquel , Costa Ruben , Agostinho Carlos , Lima Celson , Jardim-Goncalves Ricardo
Published: March 2016

Knowledge is a word that can have multiple definitions, one can think of it as information, understanding or skill that you get from previous experiences or education. In the business world, independently of the size of the companies, knowledge is without any doubt power. If in one hand the access to internal knowledge is crucial to support better decision and management strategies, on the other, when knowledge is shared by means of collaboration between partnered companies it could be the negotiations empowering base.

This work presents a knowledge gathering, enrichment and sharing approach, based on concepts such as Information Retrieval, Knowledge Management and Semantic technologies, that envisions to help Manufacturing Industry companies, engaged in collaborative e-procurement tasks, to share and gain easy and fast access to crucial knowledge.

The presented work was created and validated in Building & Construction domain and will be integrated in Horizon 2020 C2NET project in the Manufacturing domain. Namely, the relevant achievements pursued by this work are the following: (i) conceptualization of a model that enables the semantic enrichment of knowledge sources supported by domain experts; and (ii) implementation of a proof-of-concept focusing on the Manufacturing Industry context.
Modeling and Control of the Series Elasticity in Pneumatic Actuators
Authors: Zheng Hao , Shen Xiangrong
Published: March 2016

Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to close-loop control, and suffers from multiple related issues such as limited frequency range, potential stability issue, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elasticity actuator, leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modelled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.
Automated Estimation of Elastic Material Parameters of a Transversely Isotropic Material Using Asymmetric Indentation and Inverse Finite Element Analysis
Authors: Feng Yuan , Lee Chung-Hao , Sun Lining , Okamoto Ruth J. , Ji Songbai
Published: March 2016

Anisotropy exists in many soft biological tissues. The most common anisotropy is transverse isotropy, which is typical for fiber-reinforced structures, such as the brain white matter, tendon and muscle. Although many methods have been proposed to determine tissue properties, techniques to characterize transversely isotropic materials remain limited. The goal of this study is to investigate the feasibility of asymmetric indentation coupled with numerical optimization based on inverse finite element (FE) simulation to characterize transversely isotropic soft biological tissues. The proposed approach combining indentation and optimization may provide a useful general framework to characterize a variety of fiber-reinforced soft tissues in the future.