bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Technique for the Measurement of Wall Shear Stress Based on Micro Fabricated Hot-Film Sensor
Authors: Sawada Takuya , Terashima Osamu , Sakai Yasuhiko , Nagata Kouji , Shikida Mitsuhiro , Hida Hirotaka , Onishi Kazuhiro , Ito Yasumasa 
Published: April 2014

The objective of this study is to establish a technique for accurately measuring the wall shear stress in turbulent flows using a micro-fabricated hot-film sensor.
Previously, we developed a hot-film sensor with a flexible polyimide-film substrate. This sensor can be attached to curved walls and be used in various situations. Furthermore, the sensor has a 20-μm-wide, heated thin metal film. However, the temporal resolution of this hot-film sensor is not very high owing to its substrate’s high heat capacity. Consequently, its performance is inadequate for measuring the wall shear stress “fluctuations” in turbulent flows.
Therefore, we have developed another type of hot-film sensor in which the substrate is replaced with silicon, and a cavity has been introduced under the hot-film for reducing heat loss from the sensor and achieving high temporal resolution. Furthermore, for improving the sensor’s spatial resolution, the width of the hot-film is decreased to 10 μm. The structure of the hot-film’s pattern and the flow-detection mechanism are similar to those of the previous sensor.
Experimental results show that new hot-film sensor works as expected and has better temporal resolution than the previous hot-film sensor. As future work, we will measure the wall shear stress for a turbulent wall-jet and discuss the relationship between a large-scale coherent vortex structure and wall shear stress based on data obtained using the new hot-film sensor.
On the General Characterization of Machined Springs and Their Manufacturing Processes
Authors: Calderon Juan de Dios , Perez Carlos 
Published: April 2014

Springs are among the most important and common mechanical elements used. When springs are designed, it is important to make certain considerations and procedures in order to select the optimum spring configuration, fixturing system and other assembly features for a specific function. In conventional springs or wire wound springs, these individual features increase time and complexity of assembly. Machined springs have been developed as mean of solution for multi-objective design like reliability, repeatability and integration of multiple components, which results in a significative reduction of complexity of assembly.
On the other hand, machined springs have precise performance as well as additional capabilities and features that are not obtained with conventional springs. The key behind the versatility of machined springs is the capability of integration of special geometries for fixation, the possibility of usage of multiple entry coil geometries and obtention of accurate spring values.
In this work, description of some of the general characteristics of machined springs in terms of material and process selection is made; moreover, certain considerations during the design and manufacturing stages are pointed. A comparative study between a wire spring and machined spring for a specific application is performed as mean of evidence of the advantages of machined springs.
A Small-Scale ORC Energy Recovery System for Vehicular Application: Feasibility Analysis and Preliminary Components Design
Authors: Capata Roberto , Sciubba Enrico 
Published: April 2014

The paper analyses the feasibility of an “on-board” innovative and patented (patent ID RM2011 A 000671) ORC recovery system. The vehicle thermal source can be either a typical diesel engine (1400 cc) or a small gas turbine set (15–30 kW). The sensible heat recovered from the exhaust gases feeds the energy recovery system that can produce sufficient extra power to sustain the conditioning system and other auxiliaries. The concept is suitable for all types of thermally propelled vehicles, but it is studied here for automotive applications.
The characteristics of the organic cycle-based recovery system are discussed, and a preliminary design of the main components, such as condenser, evaporator and pre-heater is presented. The main challenge are the imposed size and weight limitations that require a particular design for this compact heat exchangers. A possible system layout is analysed and the requirements for a prototypal application are investigated.
At this stage of the project, no components costs evaluation is provided, in part because our scope is to demonstrate feasibility, and secondly most of the components are built in our own shop.
Analysis of Impedance for Water Management in Proton Exchange Membrane Fuel Cells Using Factorial Design of Experiment (DoE) Methodology
Authors: Mammar Khaled , Ould-Bouamama Belkacem 
Published: April 2014

Electrochemical impedance spectroscopy (EIS) is a very powerful tool for exploitation as a rich source of Proton Exchange Membrane Fuel Cell (PEMFC) diagnostic information.
A primary goal of this work was to develop a suitable PEMFC impedance model, which can be used in the analysis for flooding and drying of fuel cell. For this one a novel optimization method based on factorial Design methodology is used. It was applied for parametric analysis of electrochemical impedance Thus it is possible to evaluate the relative importance of each parameter to the simulation accuracy. Furthermore this work presents an analysis of the PEMFC impedance behavior in the case of flooding and drying.
Feedwater Repowering of Coal Fired Power Plants: Effects of Steam Turbine Overloads on Energy and Economic Performance of the Integrated Power System
Authors: Carapellucci Roberto , Giordano Lorena 
Published: April 2014

In recent years, the environmental concerns and the need to improve the competitiveness of existing coal-fired power plants have renewed the interest for the repowering option. Repowering techniques based on combustion turbines allow to increase thermodynamic performances of the steam power plant, as well as to reduce emissions of greenhouse gases, due to efficiency improvement and partial fuel-shift from coal to natural gas.
This paper aims to evaluate performances of feedwater repowering of a coal fired power plant, considering various steam turbine overloads. Two types of analysis are here proposed. First, thermodynamic and environmental benefits of feedwater repowering are evaluated in terms of efficiency gain and CO2 emission reduction, with reference to the steam power plant only. Then, effects of the integration of a gas turbine into the existing coal fired power plant are highlighted. Different feedwater repowering options, varying the operating mode of the coal fired power plant, are compared from the energy, economic and environmental point of view. The attention is focused on performance parameters of the integrated steam-gas power plant, as well as on marginal indices defining the efficiency and unit cost of electricity of the additional power production.
Event-Driven CNC Modularized Sewing Platform
Authors: Xie Xiaohui , Ma Cui , Han Bingzhe , Du Ruxu 
Published: April 2014

With ever increased demand for quality and productivity, modern industrial sewing machine is becoming very complex and requiring sophisticated control. This paper presents a control platform that can be used for all kinds of lockstitch sewing machines. This event-driven control platform can support various kinds of sewing operations, from simple lockstitches, to X-Y lockstitches, as well as thread cutting. The key to the control platform is the precision cooperative control. First, for each motion axis, both the position and the velocity must be precisely controlled. In addition, the multi-axis motions must be synchronized to achieve high accuracy stitches.
In order to increase the machine flexibility and decrease variety, a generalized and modularized sewing platform is proposed in this paper. It can be assembled with common lockstitch sewing machine and achieve several kinds of sewing functions. This platform module has independent driving capability to fulfill special movement and the communication ability to collaborate with other modules. Besides the modularized mechanism, the reusable and reconfigurable control system is the key point. For industry sewing machine, the important functions are the single-axis precise control and multi-axis cooperative control. In the X-Y moving platform, the closed-loop stepper motor system is adopted for each axis to obtain precise speed and position control. On the other hand, the cooperative control between modules is realized by event-based control method which uses a time-independent parameter to avoid the uncertain time-delay. To verify the system, the corresponding experiments are taken. And the results satisfy the requirements very well.
Halloysite Clay Nanotubes With PCM for Thermal Energy Storage and Efficiency
Authors: Thapa S. , Zhao Y. , Lvov Y. , Weiss L. 
Published: April 2014

There is opportunity to achieve energy savings and increasing energy sustainability through new techniques addressing thermal storage challenges. New materials may be useful to a wide variety of applications including solar thermal as well as building heating and cooling systems. This present work focuses on new thermal storage technology that may be utilized across a wide spectrum of structures. The technology itself relies on implementation of a phase-change insulation material that combines unique characteristics of naturally occurring halloysite clay nanotubes with low-cost eicosane-type waxes. This combination results in a microtube skeleton supported material. This allows for material shape preservation during phase transition heat conversion.
Investigations further consider the addition of thermal conductivity enhancement via graphite-based nano particles or tubes. In this manner a unique material is presented that is capable of maintaining shape during wax phase change while exhibiting increase in thermal conductivity. Unlike wax-based phase change material systems that allow the wax to change structure during phase change, the use of halloysite nanotubes also maintains the overall thermal conductivity increase through numerous phase change cycles. Multiple material combinations that vary included percentages of both halloysite and conductivity enhancement are investigated. Thermal conductivity of wax-halloysite-graphite (45/45/10 %) composite showed increased conductivity to 1.35 W/mK. This was nearly 3 times higher than the base wax-halloysite composite. Wax-halloysite-graphite-carbon nanotubes (45/45/5/5 %) composite showed thermal conductivity of 0.83 W/mK while maintaining original shape until 81°C (above the wax melting point).
Aspects of Fixture Clamp Modeling in Non-Rigid Variation Simulation of Sheet Metal Assemblies
Authors: Lindau Björn , Wärmefjord Kristina , Lindkvist Lars , Söderberg Rikard 
Published: April 2014

Today there is an increased use of CAT-tools (Computer Aided Tolerancing) within the automotive industry. These kinds of virtual tools are getting increasingly important to ensure robust solutions as early as possible in the development processes, to minimize the use of test series and thereby reduce lead times and development costs.
This paper focuses upon modeling of fixture locating scheme and the aspect of how many degrees of freedoms (DoF) a clamp actually locks. The clamps control part movement allowance, and it is of importance to investigate the influence from the friction forces between the clamping units and the fixated parts. Simulated forces in non-steering directions are compared to friction forces measured in real body shop production equipment. The non-rigid variation simulations have been performed based upon the Method of Influence Coefficients (MIC) and additional functionality for contact modeling, force estimation and weld sequence analysis.
There are a variety of alternatives of how to build the simulation model and the made choices obviously influence the simulation results. The industrial case study shows significant differences in both estimated in-plane forces and geometric results after springback for different choices of modeling alternatives. It demonstrates the difficulties in taking the friction force into consideration in variation simulation of sheet metal assembly processes.
PDM (Personal Design and Manufacturing) for Active Customers
Authors: Fukuda Shuichi 
Published: April 2014

As diversification is quickly increasing, industries are making tremendous efforts to cope with it. But this paper points out that these efforts are too much producer-centric.
Our customers are not passive consumers as most industries assume. They are very active and would like to customize our products to their own needs and to their preferences. We should note that this act of customization is deeply associated with our basic need of self actualization. That is why their requirements are diversifying. We have to change our product development much more to customer-centric.
New emerging technologies such as 3D printers enable them to get involved in product design and manufacturing. But if we consider the capabilities of the present states of these technologies and expertise of our customers, it is much easier to realize such customer-centric product development, if we extract the feature parts or feature points from a product that relate to personalization and let our customers develop them with the help of us, experts. The parts that do not substantially contribute to personalization may be developed as a common platform and these parts can be developed by experts without customer’s involvements. In this way, customers would feel they are actualizing themselves and would be more satisfied.
Flow Accelerated Degradation of Corrosion Protective Organic Coatings
Authors: Zhou Qixin , Wang Yechun 
Published: April 2014

Water percolation into coating-metal interface is usually the main cause for the deterioration of corrosion protective property of organic coatings, which leads to coating delamination and under film corrosion. Recently, flowing fluid has received attention due to its capability to accelerate the degradation of materials. A plethora of works have focused on the corrosion of metallic materials accelerated by the flow of working fluids, while few studies have investigated the flow accelerated degrading behavior of organic coatings. For organic coatings, flowing fluid above the coating surface affects corrosion by enhancing the water percolation and by abrading the surface due to wall shear stress. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings.
In this study, a commercially available epoxy based clear coating and pigmented marine coating were exposed to the laminar flow as well as stationary immersion. The laminar flow was pressure driven and confined in a newly designed flow channel. A 3.5 wt% sodium chloride solution was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The immersing solutions were measured by pH and conductivity meters as well as Fourier Transform Infrared Spectrometer (FTIR) to trace coating degradation products as they leached out from the coating. Initial attempts to acquire acceleration factors and predict service lifetime of organic coatings were also conducted.
Design Considerations for Compression Gas Driven Shock Tube to Replicate Field Relevant Primary Blast Condition
Authors: Sundaramurthy Aravind , Gupta Raj K. , Chandra Namas 
Published: April 2014

Detonation of a high explosive (HE) produces shock-blast wave, noise, shrapnel, and gaseous product; while direct exposure to blast is a concern near the epicenter; shock-blast can affect subjects even at farther distances. The latter is characterized as the primary blast with blast overpressure, time duration, and impulse as shock-blast wave parameters (SWPs). These parameters in turn are a function of the strength of the HE and the distance from the epicenter. It is extremely important to carefully design and operate the shock tube to produce a field relevant SWPs. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs to deduce relationship that can be used to control the blast profile and emulate the field conditions.
In order to determine these relationships, 30 experiments by varying the membrane thickness, breech length (66.68 to 1209.68 mm) and measurement location was performed. Finally, ConWep was utilized for the comparison of TNT shock-blast profiles with the profiles obtained from shock tube.
From these experiments, we observed the following: (a) burst pressure increases with increase in the number of membrane used (membrane thickness) and does not vary significantly with increase in the breech length; (b) within the test section, overpressure and Mach number increases linearly with increase in the burst pressure; however, positive time duration increases with increase in the breech length; (c) near the exit of the shock tube, there is a significant reduction in the positive time duration (PTD) regardless of the breech length.
Studying the Intact, ACL-Deficient and Reconstructed Human Knee Joint Using a Finite Element Model
Authors: Vairis Achilles , Petousis Markos , Stefanoudakis George , Vidakis Nectarios , Kandyla Betina , Tsainis Andreas-Marios 
Published: April 2014

The human knee joint has a three dimensional geometry with multiple body articulations that produce complex mechanical responses under loads that occur in everyday life and sports activities. Knowledge of the complex mechanical interactions of these load bearing structures is of help when the treatment of relevant diseases is evaluated and assisting devices are designed.
The anterior cruciate ligament in the knee connects the femur to the tibia and is often torn during a sudden twisting motion, resulting in knee instability. The objective of this work is to study the mechanical behavior of the human knee joint in typical everyday activities and evaluate the differences in its response for three different states, intact, injured and reconstructed knee. Three equivalent finite element models were developed. For the reconstructed model a novel repair device developed and patented by the authors was employed.
For the verification of the developed models, static load cases presented in a previous modeling work were used. Mechanical stresses calculated for the load cases studied, were very close to results presented in previous experimentally verified work, in both load distribution and maximum calculated load values.
Implications of Increased Lower Extremity Movement Variability on Fall Susceptibility at Increased Stride Lengths During Locomotion
Authors: Nordin Andrew D. , Bailey Joshua P. , Dufek Janet S. 
Published: April 2014

The purpose of this examination was to explore the effects of stride length (SL) perturbations on walking gait, relative to preferred walking (PW) and running (PR), via lower extremity range of motion (ROM) variability. ROM variability at the hip, knee, and ankle joints, in the sagittal and frontal planes were used in evaluating motor control of gait, where increased gait variability has been previously implicated in fall susceptibly.
Nine participants (5 male, 4 female; mean age 23.11±3.55 years, height 1.72±0.18m, mass 72.66±14.37kg) free from previous lower extremity injury were examined. Kinematic data were acquired using a 12-camera system (Vicon MX T40-S; 200Hz). Data filtering and interpolation included a low pass, 4th order, Butterworth filter (15Hz cutoff) and cubic spline. Five gait trials were completed for PW and PR, with subsequent SL manipulations computed as a percentage of leg length (LL). SL perturbations included 60%, 80%, 100%, 120%, and 140% of LL.
Kinematic analysis involved one stride (two steps) during each gait trial, assessing ROM at the hip, knee, and ankle from heel contact to toe-off for each limb, in the sagittal and frontal planes. Variability was expressed using coefficient of variation (%). Comparisons were made using 3×7 (joint × stride condition) mixed model ANOVAs, with repeated measures on stride condition (α = 0.05), using SPSS 20.0.
Differences in lower extremity ROM variability were detected among stride conditions in the frontal and sagittal planes (F[3.185,76.451] = 3.004, p = .033; F[4.595,110.279] = 2.834, p = .022, respectively). Greater ROM variability was observed at, and in excess of SLs of 100%LL relative to PW in the frontal plane (PW: 9.2±4.2%; 100%LL: 11.8±3.6%, p = .014; 120%LL: 13.5±5.8%, p = .046; 140%LL: 13.8±6.5%, p = .016), and between SLs of 80%LL and 120%LL in the sagittal plane (4.9±3.0%; 7.8±4.7%, p = .046, respectively). From this, PW appeared to occur within SLs of 60%LL to 80%LL, while SLs exceeding 100%LL resulted in increased lower extremity ROM variability. This may have consequences for fall susceptibility at increased stride lengths during walking. PR did not reveal significant variability differences (p>.05) compared to walking conditions in either the sagittal or frontal plane (7.5±5.0%; 12.8±7.7%, respectively), suggesting that running represents a separate, but stable gait pattern. In the sagittal plane, ROM variability was significantly lower at the hip (3.9±1.5%), relative to the ankle (8.4±1.6%, p<.001) and knee joints (7.4±2.6%, p = .001), suggesting that gait control may be more active at the ankle and knee joints. Future investigations should examine kinetic changes in gait when altering stride length.
Mechanics of Air-Inflated Drop-Stitch Fabric Panels Subject to Bending Loads
Authors: Cavallaro Paul V. , Hart Christopher J. , Sadegh Ali M. 
Published: April 2014

Rapid deployment and mobility of lightweight structures, namely inflatable structures, are of growing significance to the military and space communities. When deployment and rigidity are driven by pressure (for example, air or fluid) and materials such as textiles, elastomers and flexible composites are used, significant load carrying capacity per unit weight (or per-unit stowed volume) can be uniquely achieved. Specifically, the pressurized air directly provides the stiffness to support structural loads, thus eliminating the requirement for heavy metal stiffeners that are used in conventional rigid structures. However, the material and system behaviors are not sufficiently understood. Furthermore, predictive-performance analysis methods and test standards are not adequately established because the behaviors of inflatable fabric structures often involve coupled effects from inflation pressure such as fluid-structure interactions (FSI’s), thermo-mechanical coupling and nonlinear constitutive responses of the materials. These effects can restrict the use of conventional design, analysis and test methods.
This research explores the mechanics of air-inflated drop-stitch fabric panels subject to bending loads using analytical and experimental methods. Results of experimental four-point bend tests conducted at various inflation pressures are used to validate the analytical method. The predicted and experimental deflections, wrinkling onset moments, ultimate loads, pressure changes, etc. are compared and discussed.