bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hyperelastic and Viscoelastic Properties of Brain Tissue in Tension
Authors: Rashid Badar , Destrade Michel , Gilchrist Michael D. 
Published: October 2013

Mechanical characterization of brain tissue at high loading velocities is particularly important for modelling Traumatic Brain Injury (TBI). During severe impact conditions, brain tissue experiences a mixture of compression, tension and shear. Diffuse axonal injury (DAI) occurs in animals and humans when the strains and strain rates exceed 10% and 10/s, respectively. Knowing the mechanical properties of brain tissue at these strains and strain rates is thus of particular importance, as they can be used in finite element simulations to predict the occurrence of brain injuries under different impact conditions.
In this research, uniaxial tensile tests at strain rates of 30, 60 and 90/s up to 30% strain and stress relaxation tests in tension at various strain magnitudes (10%–60%) with an average rise time of 24 ms were performed. The brain tissue showed a stiffer response with increasing strain rates, showing that hyperelastic models are not adequate and that viscoelastic models are required. Specifically, the tensile engineering stress at 30% strain was 3.1 ± 0.49 kPa, 4.3 ± 0.86 kPa, 6.5 ± 0.76 kPa (mean ± SD) at strain rates of 30, 60 and 90/s, respectively. The Prony parameters were estimated from the relaxation data. Numerical simulations were performed using a one-term Ogden model to analyze hyperelastic and viscoelastic behavior of brain tissue up to 30% strain. The material parameters obtained in this study will help to develop biofidelic human brain finite element models, which subsequently can be used to predict brain injuries under impact conditions.
Multifunctional Skin-Like Electronics for Long-Term Health Monitoring
Authors: Yeo Woon-Hong , Kim Yun-Soung , Lee Jongwoo , Rogers John A. 
Published: October 2013

Conductive gel-based wet electrodes along with the skin preparation have been widely used for the measurement of electrophysiological signals on the skin in a health monitoring system. The use of conductive gels is necessary to reduce the contact impedance between the skin surface and electrode. However, it can cause skin irritation or allergic reactions. This issue originates from the mismatch between the soft, curvy skin epidermis and the rigid, flat metal electrode.
To address the issues of conventional electronics, we introduce a new class of ‘skin-like’ electronic system. The electronics can be conformally laminated on the epidermis, such that it ensures high-quality data recording without conductive gels. The skin-like electronics incorporates electrophysiological-, temperature-, and strain sensors in the system for multimodal functionality. To provide robust wearability for a week, a medical spray bandage is utilized to shield the sensor on the skin. The multifunctional sensor measures physiological signals and they are recorded with a commercial wireless data acquisition system along with a releasable, skin-like connector. This novel, multifunctional electronics on the skin can potentially replace the irritable and cumbersome wet electrodes for portable, long-term health monitoring at home.
Sliding Vane Rotary Compressor Energy Optimization
Authors: Cipollone Roberto , Bianchi Giuseppe , Contaldi Giulio 
Published: October 2013

The reduction of the electrical energy for producing compressed air gives an important contribution to the overall energy saving in the industrial context. Among the different technologies, Sliding Vane Rotary Compressors (SVRC) demonstrate unforeseen potential in terms of energy saving due to some intrinsic features specifically related to this machine.
One of the most important contribution is given by cooling the air during compression; this could be achieved by a proper oil injection conceived for this purpose. A mathematical model describing the oil injection process is presented in this paper. It considers the main parameters which describe the spray formation, its penetration inside the cell till to the intersection with metallic surfaces and the resulting air cooling.
The influence of the most important design and operating injection parameters have been checked on the model and design rules are outlined in order to produce an oil injection potentially able to reduce mechanical work.
Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting-Nozzle With a Throat
Authors: Singh Sowmitra , Fourmeau Tiffany , Choi Jin-Keun , Chahine Georges 
Published: October 2013

This paper addresses the concept of thrust augmentation through bubble injection into an expanding-contracting nozzle with a throat. The presence of a throat in an expanding-contracting nozzle can result in flow transition from the subsonic regime to the supersonic regime (choked conditions) for a bubbly mixture flow, which may result in a substantial increase in jet thrust. This increase would primarily arise from the fact that the injected gas bubbles expand drastically in the supersonic region of the flow. In the current work, an analytical 1-D model is developed to capture choked bubbly flow in an expanding-contracting nozzle with a throat. The study intends to provide analytical/numerical confirmation to observed phenomena and to serve as a design tool to guide practical experiments aimed at creating and studying choked bubbly flows through nozzles.
Starting from the 1-D mixture continuity and momentum equations along with an equation of state for the bubbly mixture, expressions for mixture velocity and gas volume fraction were derived. Starting with a fixed geometry, an imposed upstream pressure and assuming choked flow in the nozzle, the derived expressions were iteratively solved to obtain the exit pressures and velocities for different injected gas volume fractions. The variation of thrust enhancement with the injected gas volume fraction was also studied. Additionally, the geometric parameters were varied (area of the exit, area of the throat) to understand the influence of the nozzle geometry on the thrust enhancement and on the flow conditions at the inlet. This parametric study provides a performance map that can be used to design a bubble augmented waterjet propulsor that can achieve and exploit supersonic flow. It was found that the optimum geometry for choked flows, unlike the optimum geometry under purely subsonic flows, had a dependence on the injected gas volume fraction. Furthermore, for the same injected gas volume fraction the optimum geometry for choked flows resulted in greater thrust enhancement compared to the optimum geometry for purely subsonic flows.
Polyhedral Space Curve Meshing Reducer With Multiple Output Shafts
Authors: Chen Yangzhi , Ding Jiang , Yao Chuanghai , Lv Yueling 
Published: October 2013

In recent years, a gear named Space Curve Meshing Wheel (SCMW) has been invented based on the meshing theory of space curves instead of classic space surfaces. Well improved in many aspects after its invention, it has been applied within the Space Curve Meshing Reducer (SCMR).
The design method of an invention named polyhedral SCMR is presented in this paper. With single input shaft and multiple output shafts, this SCMR has advantages like compact structure, flexible design and low cost. It is characterized by the application of the SCMW group containing one driving wheel and several driven wheels, whose rotation axes are concurrent at a point and radiate in polyhedral directions. A SCMW group can form a single-stage SCMR, while SCMW groups connected can form a multiple-stage SCMR. In this paper, geometric parameters of the polyhedral SCMR are defined, design formulas are derived, and an example is provided to illustrate the design process.
Modeling of Linear Atmospheric Plasma Reactor
Authors: Chugunov Svyatoslav , Akhatov Iskander 
Published: October 2013

Methods of materials deposition and coating based on atmospheric pressure plasma (APP) have gained significant attention these days. Keeping the setup operation at low cost, APP units provide quality pre-processing of chemical agents with subsequent delivery of activated materials onto the surface of interest. These units eliminate the need for vacuum chambers, simplify thermal control of the setup, and widen the range of applicable chemical precursors. Considering the above mentioned factors, the APP becomes a recognizable choice for industrial applications and laboratory use. Demonstrating advanced performance and possibilities, APP reactors are still a subject to certain challenges that have to be overcome with future research. Among them are clogging of output channels with processed material, accurate estimations of mixing zone for efficient material activation, and uniform on-demand distribution of activated material over the substrate. These problems are still waiting for elegant and effective solutions.
We investigate possibilities provided by use of a Linear Plasma Head — a portable APP reactor targeted for enhanced surface coatings. Currently we present our theoretical model of plasma generation in Linear Plasma Head. Numerical simulations are carried out using a parallel computational paradigm. The results and methods discussed in this paper yield with theory-based approach to building an advanced APP-based chemical reactor.
Bioadditive Manufacturing of Hybrid Tissue Scaffolds for Controlled Release Kinetics
Authors: Ozbolat Ibrahim T. , Khoda A. K. M. B. , Koc Bahattin 
Published: October 2013

Development of engineered tissue scaffolds with superior control over cell-protein interactions is still very much infancy. Advancing through heterogeneous multifold scaffolds with controlled release fashion enables synchronization of regenerating tissue with the release kinetics of loaded biomolecules. This might be an engineering challenge and promising approach for improved and efficient tissue regeneration. The most critical limitations: the selection of proper protein(s) incorporation, and precise control over concentration gradient and timing should be overcome. Hence, tissue scaffolds need to be fabricated in a way that proteins or growth factors should be incorporated and released in a specific spatial and temporal orientation to mimic the natural tissue regeneration process. Spatial and temporal control over heterogeneous porous tissue scaffolds can be achieved by controlling two important parameters: (i) internal architecture with enhanced fluid transport, and (ii) distribution of scaffold base material and loaded modifiers.
In this research, heterogeneous tissue scaffolds are designed considering both the parameters. Firstly, the three-dimensional porous structures of the scaffold are geometrically partition into functionally uniform porosity regions and controlled spatial micro-architecture has been achieved using a functionally gradient porosity function. The bio-fabrication of the designed internal porous architecture has been performed using a single nozzle bioadditive manufacturing system. The internal architecture scheme is developed to enhance fluid transport with continuous base material deposition.
Next, the hybrid tissue scaffolds are modeled with varying material characteristics to mediate the release of base material and enclosed biological modifiers are proposed based on tissue engineering requirements. The hybrid scaffolds are fabricated for spatial control of biomolecules and base material to synchronize the release kinetics with tissue regeneration. A pressure-assisted multi-chamber single nozzle bioadditive manufacturing system is used to fabricate hybrid scaffolds.
Characterization of Driving Patterns and Operations of Heavy Duty Vehicles in a Port Area and Their Influence on Exhaust Emissions and Fuel Consumption Evaluation Through Different Emission Models
Authors: Zamboni G. , Malfettani S. , André M. , Carraro C. , Marelli S. , Capobianco M. 
Published: October 2013

An experimental and theoretical investigation is being performed with a view to evaluate the contribution of Heavy duty vehicles (HDVs) to exhaust emissions and fuel consumption in urban areas involved by commercial shipping activities.
Reference is made to the city of Genoa, whose urban road network is influenced both by shipping activities and highway connections, as more than twenty accesses to port area and seven motorway exits are available within the urban area.
Different aspects were deepened in this study. Firstly, the HDV flows crossing highway exits, urban zones and port areas were assessed, as well as the relevant vehicle classes. Secondly, the typical urban trips linking highway exits to port gates and the HDV mission profiles within the port area were identified. Measurements of HDV instantaneous speed related to the urban trips were then planned aiming at the definition of the most representative speed patterns through a proper statistical data processing, enabling the application of Passenger Car and Heavy Duty Emission Model (PHEM) for the estimation of emission and fuel consumption factors for selected HDV classes.
The main results of the different investigation steps are presented and discussed in the paper, outlining the peculiar mission of HDVs in port area and the related emissive behavior.
Incorporating Public Policy Creation and Analysis Activities Into a Mechanical Engineering Curriculum
Authors: Reisel John R. 
Published: October 2013

While it is easy to recognize that mechanical engineers can lend their expertise to public policy makers as they create public policy related to science and technology, it is not as clear as to how to introduce mechanical engineering students to public policy activities. The undergraduate curricula in most mechanical engineering programs are considered full, and there are always additional topics that people wish to add. Educators are likely to hesitate before removing material from their programs in order to add material on public policy. Yet, there are techniques that can be used to incorporate aspects of public policy into a standard mechanical engineering curriculum without the removal of much, if any, current content.
In this paper, several techniques for introducing mechanical engineering students to the process of public policy creation will be discussed. While these methods will not make the students experts in policy, they can introduce students to the tools that they need to influence the public policy creation process. These techniques include a comprehensive semester-long project in a technical elective course, a short policy analysis paper for development in a required or elective course, incorporation of public policy considerations in a capstone design project, policy discussions or debates in relevant courses, and a focus on public policy development in extracurricular activities.
In their education, students should not only become technically proficient, but also learn how to track current events and trends, communicate their knowledge effectively, gain knowledge on applying proper engineering ethics, and be aware of the environmental and social context of their work. Through these knowledge areas and skills, students will gain the fundamental working knowledge that they need to influence public policy creation. It may be noted that these are also desirable outcomes for a student’s educational program as defined by ABET. Therefore, finding opportunities in a mechanical engineering program’s curriculum to address public policy creation activities also benefits the program by helping it more completely fulfill ABET accreditation requirements.
Improvement of Constant Temperature Anemometer and Measurement of Energy Spectra in a Plane Turbulent Jet
Authors: Terashima Osamu , Onishi Kazuhiro , Sakai Yasuhiko , Nagata Kouji 
Published: October 2013

A constant temperature anemometer (CTA) is a useful instrument for measuring the velocity fluctuations in turbulent flow. However, in our calibration test, the actual frequency response of a typical CTA was no more than 5 kHz under normal laboratory conditions: for example, the diameter of the hot wire is 5 μm and the free stream velocity is 20 m/s. Therefore, in some cases, a typical CTA is not enough to measure accurately turbulent velocity fluctuations for fine scale structures. In this paper, we present a rearranged CTA circuit to obtain a faster frequency response so that in turn fine-scale structures can be more accurately investigated.
A typical CTA circuit consists of a Wheatstone bridge and a feed back circuit. To improve the frequency response, the ratio of the electrical resistance of the Wheatstone bridge is set to 1 and two operational amplifiers with a gain-band width product of 100 MHz and a slew rate of 20 V/μs are used in the feedback circuit.
An experiment to estimate the frequency response of the rearranged CTA circuit is performed with a free stream velocity of 20 m/s and using hot wires of diameter 5 μm and 3 μm. Experimental results show that the roll-off frequency of the rearranged CTA circuit is improved from 5 kHz to 20 kHz for the 5 μm hot wire and from 6 kHz to 40 kHz for the 3 μm hot wire.
Velocity measurements are made using the rearranged CTA circuit in a plane turbulent jet where the value of the Taylor microscale λ is 3.2 mm and the Taylor-scale Reynolds number Reλ is 440. Measurements shows that the power spectrum obeys the reliable numerical profile derived by a LDIA (Lagrangian Direct-Interaction Approximation) theory until more than 0.20 of the non-dimensional wave number κ1η, which is a wider range in comparison with the results obtained when using a typical CTA circuit. Here, κ1 is the axial wave number and η is the Kolmogorov microscale.
Further, velocity measurements are performed taken using the rearranged CTA circuit with a square jet where the value of λ is 6.3 mm and Reλ is 1,720. Measurements shows that the power spectrum obeys the numerical profile by the LDIA theory in the range 0.04 < κ1η < 0.20, which is a much wider range than the results obtained when using a typical CTA circuit (0.04 < κ1η < 0.08).
These results indicate that the rearranged CTA circuit can be used to investigate fine-scale structures in turbulent flows more accurately.
On the Dynamics of Fractional Visco-Elastic Beams
Authors: Di Lorenzo Salvatore , Pinnola Francesco P. , Pirrotta Antonina 
Published: October 2013

With increasing advanced manufacturing process, visco-elastic materials are very attractive for mitigation of vibrations, provided that you may have advanced studies for capturing the realistic behavior of such materials.
Experimental verification of the visco-elastic behavior is limited to some well-known low order models as the Maxwell or Kelvin models. However, both models are not sufficient to model the visco-elastic behavior of real materials, since only the Maxwell type can capture the relaxation tests and the Kelvin the creep tests, respectively. Very recently, it has been stressed that the most suitable model for capturing the visco-elastic behavior is the spring-pot, characterized by a fractional constitutive law.
Based on this assumption, the quasi-static behavior has been investigated very recently, however for noise control there is a need of exploiting the dynamic behavior of such a fractional visco-elastic beam.
The present paper introduces the dynamic response of fractional visco-elastic Euler-Bernoulli beam under dynamic loads.
Numerical Optimization of Ejector Geometry Based on Non-Dimensional Parameters
Authors: Sharifi Navid , Boroomand Masoud , Sharifi Majid 
Published: October 2013

Supersonic steam ejectors are simple devices which can be used to compress a low pressure flow by a pressurized motive flow. “Compression ratio” and “entrainment ratio” are two major characteristics of the ejectors. One of the current challenging issues in ejector design is the correct size selection for different dimensions of ejectors to achieve the maximum entraining capability at a given compression ratio. The conventional design methods are based on varying shape parameters such as lengths, angles and diameters and pick a particular geometry which yields the best performance under a given boundary conditions.
In the current study, a new method of size selection for different geometrical parameters of ejectors will be introduced. The basis of this method is to define a non-dimensional volume in terms of ejector dimensions. The effect of varying this parameter on the characteristics of ejectors has been studied numerically via a CFD method. The numerical simulation has been performed on more than 400 ejector models with different geometries according to the finite-volume steady-state method. Steam was taken as the working fluid and it was assumed a real gas with a nonlinear relationship between pressure and density. The numerical results verified with experimental measurements obtained from a pilot model of steam ejector. This method enables us to develop the practical characteristic curves based on non-dimensional parameters which further leading to achieve an optimized size selection for design purposes.
Effects of Biased AC Electroosmotic Micro-Pumping on Symmetric and Asymmetric Electrode Arrays
Authors: Islam Nazmul 
Published: October 2013

This paper presents an analysis and experiment results that were conducted to assess the effect of combining an AC signal with a DC bias when generating the electric field on electrode arrays needed to impart electroosmosis within a microchannel. The analysis was done using COMSOL 3.5a in which currently available theoretical models for EO flows were embedded in the software and solved numerically. The simulation evaluate the effects of channel geometry, frequency of excitation, electrode array geometry, and AC signal with a DC bias on the flow imparted on an electrically conducting fluid.
For the AC driven flow, the simulation results indicate the existence of an optimized frequency of excitation and an optimum geometry that lead to the maximum net forward flow of the pump. No relevant net flows were generated with the symmetric electrode arrays with a constant magnitude of AC voltage applied to both electrodes. However, superimposing a DC signal over the AC signal on the same symmetric electrode array lead to a noticeable net forward flow of 18.70 μL/min. On the other hand asymmetric electrode pattern can generate flow in both cases and can improve the microflow inside the micro-channel. Experimental flow measurements were performed on several electrode array configurations manufactured using typical MEMS fabrication techniques. The experimental results are in good agreement with the simulation data. They confirm that using an asymmetric electrode array excited by an AC signal with a DC bias leads to a significant improvement in flow rates in comparison to the flow rates obtained in an asymmetric electrode array configuration excited just with an AC signal.