bluuebunny/crossref_metadata_2025 huggingface dataset:
Micromechanics of Random Heterogeneous Materials: New Background, Opportunities and Prospects
Authors: Buryachenko Valeriy A.
Published: February 2017

One considers a linear heterogeneous media (e.g. filtration in porous media, composite materials, CMs, nanocomposites, peristatic CMs, and rough contacted surfaces). The idea of the effective field hypothesis (EFH, H1, see for references and details [1], [2]) dates back to Mossotti (1850) who pioneered the introduction of the effective field concept as a local homogeneous field acting on the inclusions and differing from the applied macroscopic one. It is proved that a concept of the EFH (even if this term is not mentioned) is a (first) background of all four groups of analytical methods in physics and mechanics of heterogeneous media (model methods, perturbation methods, self-consistent methods, and variational ones, see for refs. [1]). An operator form of the general integral equations (GIEs) is obtained which connects the driving fields and fluxes in a point being considered. Either the volume integral equations or boundary ones are used for these GIEs, new concept of the interface polarisation tensors are introduced. New GIEs present in fact the new (second) background (which does not use the EFH) of multi-scale analysis offering the opportunities for a fundamental jump in multiscale research of random heterogeneous media with drastically improved accuracy of local field estimations (with possible change of sign of predicted local fields).
Micromechanics of Random Structure Thermoperistatic Composites
Authors: Buryachenko Valeriy A.
Published: February 2017

In contrast to the classical local and nonlocal theories, the peridynamic equation of motion introduced by Silling (J. Mech. Phys. Solids 2000; 48: 175–209) is free of any spatial derivatives of displacement. The new general integral equations (GIE) connecting the displacement fields in the point being considered and the surrounding points of random structure composite materials (CMs) is proposed. For statistically homogeneous thermoperistatic media subjected to homogeneous volumetric boundary loading, one proved that the effective behaviour of this media is governing by conventional effective constitutive equation which is intrinsic to the local thermoelasticity theory. It was made by the most exploitation of the popular tools and concepts used in conventional thermoelasticity of CMs and adapted to thermoperistatics. A generalization of the Hills equality to peri-static composites is proved. The classical representations of effective elastic moduli through the mechanical influence functions for elastic CMs are generalized to the case of peristatics, and the energetic definition of effective elastic moduli is proposed. The general results establishing the links between the effective properties (effective elastic moduli, effective thermal expansion) and the corresponding mechanical and transformation influence functions are obtained by the use of the decomposition of local fields into load and residual fields. Effective properties of thermoperistatic CM are expressed through the introduced local stress polarization tensor averaged over the extended inclusion phase. This similarity opens a way for straightforward expansion of analytical micromechanics tools for locally elastic CMs to the new area of random structure peri-dynamic CMs. Detailed numerical examples for 1D case are considered.
Development of Analytical Model for Predicting Dual-Phase Ejector Performance
Authors: Elmore Emily , Al-Mutairi Khalid , Hussain Bilal , El-Gizawy A. Sherif
Published: February 2017

An analytical model is developed to extend the single-phase model to dual-phase applications. The introduced dual-phase model helps in predicting ejector performance, particularly pressure recovery and efficiency, to entrained fluids of a liquid/gas mixture. The empirical loss coefficients are replaced by analytical equations accounting for the geometry of and flow conditions within the individual ejector components. In order to verify the present analytical model predictions, liquid ejector performance is studied experimentally when the entrained fluid is both a single-phase liquid (water) and a dual-phase liquid/gas mixture (water/air). The results show consistently better agreement with the experimental data than those delivered by existing models, reducing the root mean square error of the pressure recovery prediction to less than 10% of its former value.
The Reduced Tolerance Allocation Problem
Authors: Shoukr David Sh. L. , Gadallah Mohamed H. , Metwalli Sayed M.
Published: February 2017

Tolerance allocation is a necessary and important step in product design and development. It involves the assignment of tolerances to different dimensions such that the manufacturing cost is minimum, while maintaining the tolerance stack-up conditions satisfied. Considering the design functional requirements, manufacturing processes, and dimensional and/or geometrical tolerances, the tolerance allocation problem requires intensive computational effort and time. An approach is proposed to reduce the size of the tolerance allocation problem using design of experiments (DOE). Instead of solving the optimization problem for all dimensional tolerances, it is solved for the significant dimensions only and the insignificant dimensional tolerances are set at lower control levels. A Genetic Algorithm is developed and employed to optimize the synthesis problem. A set of benchmark problems are used to test the proposed approach, and results are compared with some standard problems in literature.
Thermo-Fluid Characterizations of Ti-6Al-4V Melt Pool in Powder-Bed Electron Beam Additive Manufacturing
Authors: Rahman M. Shafiqur , Schilling Paul J. , Herrington Paul D. , Chakravarty Uttam K.
Published: February 2017

The powder-bed electron beam additive manufacturing (EBAM) process is one of the relatively new additive manufacturing (AM) technologies in which the metal powder is melted in a vacuum environment utilizing a high-energy heat source to fabricate metallic parts in a layer by layer manner. Different metallic alloys (especially, high entropy alloys such as Ti-6Al-4V) have been widely studied as a powder-bed material for the EBAM. Despite the unique advantages of designing complex geometry and tooling-free manufacturing, there are still considerable challenges in the EBAM, e.g., obtaining desired metallurgical behavior, part accuracy, reliability, and quality consistency. Therefore, a better understanding of the thermo-fluid and mechanical properties of the EBAM process is indispensable to meet the challenges. In this study, transient computational fluid dynamics (CFD) modeling of Ti-6Al-4V melt pool has been done using ANSYS Fluent 15.0 to characterize the process parameters associated with the EBAM process including the melt pool geometry, beam power, beam speed, beam diameter, and temperature profile along the melt scan. In fact, the dynamics and the solidification of the melt pool have been investigated numerically and results for cooling rate, variation in density, pressure, velocities, and liquid fraction have been obtained to illustrate the versatility of the analysis.
Design and Analysis of an Efficient Vaccine Cold Chain Box
Authors: Devrani Shitanshu , Pandey Sudhanshu , Chaturvedi Shubham , Sankar Krishnakumar , Patil Shantanu , Sridhar K.
Published: February 2017

Human health is one of the most important concerns for the governments around the world. Global organizations such as WHO (World Health Organization) and PATH (Program for Appropriate Technology in Health) have considerable interest in organizing vaccination programs and its cold chain delivery. The problem predominantly persists in Lower-middle income countries like India where due to inadequate infrastructure and lack of consistent Power supply, significant losses occur in the cold chain. Improvements are required to prevent the loss of costly and precious vaccines during the cold chain. India lacks a reliable power supply and the resulting power cuts interrupt the cold chain, leading to a loss of vaccine potency since they are not within the temperature range of 2–8 °C. This paper studies the current VCB (vaccine carrier box) and cold chain design through the aid of Computer modelling and simulations. Also a novel experimental setup to examine insulation R-value has been devised and studied. Based on this a new design approach is utilized to model a thermoelectric system and early designing is done through the aid of 3-D printing.
Coaxial Borehole Heat Exchanger Simulation With Power Generation Potential for Chachimbiro, Ecuador
Authors: Siguenza Diego , Wu Dawei , Soriano Guillermo
Published: February 2017

This work presents a virtual coaxial Borehole Heat Exchanger (BHE) energy balance simulation in Chachimbiro, Ecuador. The purpose of this study was to estimate the power generation and optimize the engineering parameters from a virtual coaxial BHE of 1500 meters depth on the mentioned site. The methodology used was the modeling simulation based on mass and energy balance through AMEsim software, and the parameters employed in the model considered the previous location surveys besides a sensitivity analysis of geometry, pipe materials, and BHE insulation depth. The results showed that a single coaxial BHE on Chachimbiro would have a thermal power potential between 3–4 MW, and its efficiency would mainly depend on the thermal conductivity of the pipes plus the insulation casing depth.
Factors Influencing Blast Attenuation on Walls With Foamed Concrete Boards
Authors: Shi Yijian
Published: February 2017

As a FEA method is used to simulate blast attenuation with a foamed concrete board (FCB), effects of different factors on simulation results are studied. These factors include different boundary conditions, FCB thicknesses, FCB densities, and element sizes. Understanding the effects of these factors are very important prior to practically using FCB for the purpose of the blast attenuation in a structure design. The effectiveness of the blast attenuation is measured by the reduction of peak pressure acting on a rigid wall (RW) that is immediately behind and adhered to FCB. The simulation results indicate that the pressure history on RW and the internal stress of FCB between a full model and its quarter one are about the same. Differences on the RW pressures between nonreflecting and free boundaries are relatively significant for the small size of FCB. The increase of density and thickness of FCB can result in a further reduction on the blast pressure if the existence of FCB can indeed reduce the peak pressure. Otherwise, the increase of the density and thickness may not result in a final reduction on the peak pressure. It seems that the pressure reduction by increasing the thickness of FCB is more efficient than by increasing its density. Nevertheless the combination of density and thickness increases should maximize the effectiveness of the blast attenuation. The size of FEA elements does affect the value of the peak pressure on RW. As the element size decreases, the peak pressure tends to change in value and delay in time. According to the trend of the peak pressure with varying the element size, a proper size for a practical application should be determined based on the following rule that besides the consideration of better accuracy on the simulation results, the element size that gives relatively higher peak pressure, or is considered as consistently conservative in a design, should be recommended. Finally, based on the findings, a design procedure for the blast attenuation is proposed.
Dynamic and Controlled Tuning of the Boiling Curve During Quenching
Authors: Shahriari Arjang , Hermes Mark , Bahadur Vaibhav
Published: February 2017

Boiling influences many industrial processes like quenching, desalination and steam generation. Boiling heat transfer at high temperatures is limited by the formation of a vapor layer between the solid and fluid. Low thermal conductivity of this vapor layer inhibits heat transfer. Electrowetting (EW) fields can breakdown this vapor layer to promote wetting, and this concept works for many quenching media including water and organic solvents. This work studies the suppression of this vapor layer and measures the resulting heat transfer enhancement during quenching of metals. We image the fluid-surface interactions and boiling patterns in the presence of an electrical voltage. EW fields replace film boiling with periodic wetting-rewetting cycles and thus fundamentally change the heat transfer mode. The increased wettability substantially reduces the cool down time. The cooling rate can by increased by as much as 3X. The results show that electric fields can dynamically tune the classical quenching curve. This study opens up new avenues to control the metallurgy of metals via electrical control of the cooling rate.
Micromechanics Modelling of Graphene Platelets Reinforced Polymer Composite Materials With Imperfect Interfaces
Authors: Azoti Wiyao Leleng , Elmarakbi Ahmed
Published: February 2017

This work investigates the elasto-plastic response of platelets-like inclusions reinforced polymer composites showing an imperfect interface. The solution of the heterogeneous material problem is solved through a kinematic integral equation. To account for the interfacial behaviour, a linear spring model LSM is adopted, leading to an expression of the modified Eshelby’s tensor. As a consequence, the interfacial contributions with respect to the strain concentration tensor within each phase as well as in the average strain field are described by a modified version of the Mori-Tanaka scheme for the overall response. The non-linear response is established in the framework of the J2 flow rule. An expression of the algorithmic tangent operator for each phase can be obtained and used as uniform modulus for homogenisation purpose. Numerical results are conducted on graphene platelets GPL-reinforced polymer PA6 composite for several design parameters such as GPL volume fraction, aspect ratio and the interfacial compliance. These results clearly highlight the impact of the aspect ratio as well as the volume fraction by a softening in the overall response when imperfection is considered at the interface. Present developments are analytical-based solutions. They constitute a theoretical framework for further multi-scale applications in automotive. The crashworthiness simulation incorporating an influence of the interfacial behaviour on the strain energy absorption SEA is of interest.
3D Printed Porous Dielectric Substrates for RF Applications
Authors: Tummala Vana Snigdha , Mian Ahsan , Chamok Nowrin H. , Ali Mohammod , Clifford Jallisa , Majumdar Prasun
Published: February 2017

In this study, dielectric properties of Acrylonitrile butadiene styrene (ABS) thermoplastic material with different fill-densities are investigated. Three separate sets of samples with dimensions of 25 mm × 25 mm × 5 mm were created at three different machine preset porosities using a LulzBot 3D printer. To understand the actual porosities of the samples, a 3D X-ray computed tomography microscope was used. The great advantage of this 3D microscopy is that it is fully non-destructive and requires no specimen preparation. Hence, the manufacturing defects and lattice variations can be quantified from image data. It is observed that the experimental pore densities are different from the factory preset values. This provides insight to further understand pore distribution-property relationships in these dielectric materials. Micro-strip patch antennas were then created on the 3D printed ABS substrates. The samples were then tested using a vector network analyzer (VNA) and resonant frequencies were measured. It is observed that the resonant frequency increases with an increase in porosity. These results clearly demonstrate the ability to control the dielectric constant of the 3D printed material based on prescribed fill density.
Multibody Dynamics Model of a Diesel Engine and Timing Gear Train With Experimental Validation
Authors: Foltz Adam D. , Wasfy Tamer M. , Ostergaard Erik , Piraner Ilya
Published: February 2017

High-powered Diesel engines typically use a timing gear train to couple/synchronize the camshaft rotation with the crankshaft and also to drive the accessories such as the fuel and oil pumps. In this paper a high-fidelity multibody dynamics model of a 6-cylinder inline Diesel engine and its timing gear train is presented. The multibody system representing the system is modeled using rigid bodies, torsional springs, revolute joints, prismatic joints, and rotational/linear actuators. A penalty model is used to impose joint and normal contact constraints. The normal contact penalty stiffness and damping techniques are used to model gear tooth stiffness and damping. The contact model detects contact between discrete points on the surface of a gear tooth (master contact surface) and a polygonal surface representation of the mating gear tooth (slave contact surface). A recursive bounding box/bounding sphere contact search algorithm is used to allow fast contact detection. Time-varying forces are applied to the cylinders to model the cylinder pressure variations due to combustion events as a function of the crank angle. The governing equations of motion are solved along with joint/constraint equations using a time-accurate explicit solution procedure. The model is partially validated by comparing its predictions of the torsional vibrations of a Diesel engine’s crankshaft and moving parts to experimental measurements. Emphasis is given on the practicality of the modeling methods to industry.
Prediction of Hysteresis of a Thermoplastic Polyurethane Using Coarse-Grained Molecular Dynamics
Authors: Uddin Md Salah , Ju Jaehyung
Published: February 2017

We predict hysteresis of a thermoplastic polyurethane (TPU) varying the configurations and weight % of hard segments from 34.90% to 62.30% using coarse-grained molecular dynamics (CGMD) simulations. Rate-dependent stress-strain responses of the molecular models are justified between energy equivalence constitutive modeling and atomic viral stresses. Uniaxial cyclic loading (tension/compression) of the coarse-grained (CG) models are performed using NPT ensembles (isothermal-isobaric) at the atmospheric condition to ensure no stresses in the other two directions except the loading directions. Engineering stresses are estimated from atomic viral stresses at different frequencies and up to various strain levels, whereas areas under the stress-strain curves give the hysteresis loss under cyclic deformations. We correlate the hysteresis losses of all of the models with their bulk moduli and Poisson’s ratios. By the end of the study, we may answer the following research questions: i) How much hysteresis loss increases due to increasing the weight% of hard segments from 34.90% to 62.30%? ii) How sensitive are the losses corresponding to strain amplitudes from 5% to 15% and frequencies from 1.67 × 1011 Hz to 5.0 × 1011 Hz? iii) In order to reduce the hysteresis loss, how much we have to compromise in bulk modulus and how much Poisson’s ratio will be increased corresponding to that compensation. This molecular simulation tool can be used to design new rubber materials with better mechanical properties and lower hysteresis losses without the trial and error based experimental work.
Numerical Study of Thermochemical Storage Using Ca(OH)2/CaO: High Temperature Applications
Authors: Ranjha Qasim A. , Vahedi Nasser , Oztekin Alparslan
Published: February 2017

Thermal energy storage by reversible gas-solid reaction has been selected as a thermochemical energy storage system. Simulations are conducted to investigate the dehydration of Ca(OH)2 and the hydration of CaO for thermal energy storage and retrieval, respectively. The rectangular packed bed is heated indirectly by air used as a heat transfer fluid (HTF) while the steam is transferred through the upper side of the bed. Transient mass transport and heat transfer equations coupled with chemical kinetics equations for a two dimensional geometry have been solved using finite element method. Numerical results have been validated by comparing against results of previous measurements and simulations. The effect of geometrical and operational parameters including the material properties on overall storage and retrieval process has been investigated. The co-current and counter-current flow arrangements for steam and heat transfer fluid have been considered.
High Temperature Thermochemical Energy Storage Using Packed Beds
Authors: Ranjha Qasim A. , Vahedi Nasser , Oztekin Alparslan
Published: February 2017

Thermal energy storage units are vital for development of the efficient solar power generation systems due to fluctuating nature of daily and seasonal solar radiations. Two available efficient and practical options to store and release solar energy at high temperatures are latent heat storage and thermochemical storage. Latent heat storage can operate only at single phase change temperature. This problem can be avoided by some of the thermochemical storage systems in which solar energy can be stored and released over a range of high temperature by endothermic and exothermic reactions. One such reaction system is reversible reaction involving dehydration of Ca(OH)2 and hydration of CaO. This system is considered in the present study to model a circular fixed bed reactor for storage and release of heat at high temperatures. Air is used as heat transfer fluid (HTF) flowing in an annular shell outside the bed for charging and discharging the bed. The bed is filled with CaO/Ca(OH)2 powders with particles diameter of the order 5μm. Three dimensional transient model has been developed and simulations are performed using finite elements based COMSOL Multiphysics. Conservation of mass and energy equations, coupled with reaction kinetics equations, are solved in the three dimensional porous bed and the heat transfer fluid channel. Parametric study is performed by varying HTF parameters, bed dimensions and process conditions. The results are verified through a qualitative comparison with experimental and simulation results in the literature for similar geometric configurations.
Designing an Unmanned Aerial Vehicle for Specific Aerial Applications of Insecticides and Herbicides
Authors: Mayeed Mohammed S. , Darveau Gabriel
Published: February 2017

In this study a gasoline powered hexa-copter unmanned aerial vehicle (UAV) has been designed as a solution to farmers’ need for a low cost, easy to maintain, long flight duration, and multi-purpose means of specific aerial applications for insecticides and herbicides.

Application of herbicides and pesticides by airplane is an example of how farmers have used technology to improve their bottom line and overall quality of life. Fields can now be sprayed in under an hour instead of consuming an entire day. However, if a producer has noxious weeds in only a small area, fixed-wing aerial application cannot be used as it is only accurate enough to do an entire field. Currently there is no solution for small scale, accurate, aerial herbicide application to meet this need. The currently available Yamaha Rmax UAV costs a tremendous amount of money and also requires a lot of money to maintain. Though it may be useful in large scale aerial spraying on the farm land, it would not be used in targeted specific areas as it is not efficient in specific applications.

The gasoline powered hexacopter UAV designed in this study is a low cost solution to farmers’ need for specific aerial applications of insecticides and herbicides. The UAV design can carry 2–3 gallons of herbicide (16.7–25.0 lbs.) for a flight time of more than 30 minutes without refueling. The design could be transported in a 60.3in × 56.7in pickup bed.

Structural and fatigue analyses are performed on the complete structure using state of the art software SolidWorks Simulation. The minimum factor of safety is obtained to be 10 based on maximum von Mises stress failure criteria. Under normal conditions with an estimated commercial use of 100 cycles per day it is observed that the design would survive for about 13 years without any fatigue failure. A drop test analysis is performed to ensure the design can survive a 5 feet freefall and a frequency analysis is also performed to observe the critical natural frequency of the structure. Flow simulations are performed on the 6 propellers/blades model using state of the art software SolidWorks Flow Simulation to observe the effect of vorticity interactions on the lift force. The design has been reasonably optimized based on maximizing the lift force.

With this new UAV design small scale and substantial farmers could afford a personal UAV for aerial applications with a small amount of capital whose absence hindered efficient and effective specific aerial application for many years.
Transient Electroosmotic Flow of Newtonian Fluids in a Microchannel With Heterogeneous Zeta Potentials at the Walls
Authors: Escandón Juan P. , Merino Eduardo G. , Hernández Clara G.
Published: February 2017

This paper presents an analytical study of the transient electroosmotic flow for Newtonian fluids through a parallel flat plate microchannel with heterogeneous zeta potentials. The dimensionless mathematical model is based on the Poisson-Boltzmann, mass and momentum conservation governing equations together with the lubrication theory. The distribution of the zeta potentials at the walls obeys to a sinusoidal function, which includes dimensional parameters as Δζ that controls the magnitude and polarity of the zeta potentials, being capable to produce slanted velocity profiles and inverse flows. On the other hand, the combination of the phase angle between the sinusoidal functions of the zeta potentials ω, the dimensionless parameter of their amplitude Δζ, and the parameter that controls the frequency of the sinusoidal functions m, induce additional perturbations on the flow, which is directly related to the dimensionless pressure distribution and to the transient flow field. The transient behavior characteristics of the electroosmotic flow are discussed in terms of the zeta potential variations. It is demonstrated that the results for the transient electroosmotic flow, predict the influence of the main dimensionless parameters above mentioned on the velocity profiles and the streamlines. This work about the perturbations on the electroosmotic flow by heterogeneous zeta potentials, contributes to a better understanding of the transport phenomena in microfluidic devices for future mixing applications.
Evaluation of the Risk Reduction Effectiveness in OSHA’s Workplace Atmosphere Sampling Activities
Authors: Gernand Jeremy M.
Published: February 2017

The Occupational Safety and Health Administration (OSHA) in the United States is responsible for the promulgation and enforcement of rules to protect and enhance worker safety in most medium and large commercial enterprises. To that end, the agency has collected and processed more than 240,000 atmospheric samples of chemicals and aerosols in a variety of workplaces in the past 30 years. Though the agency spends more than $500 million per year even in the face of increasing overall employment, there exist only targeted evaluations of OSHA sampling activity for specific issues like formaldehyde or silica in the published literature.

This paper presents a comprehensive analysis of this effort including assessment of the hazard potential distribution of sampled workplace atmospheres for all recorded pollutants over the time period from 1984 to 2011, the budgetary requirements of this activity over time in comparison to the assessed risk, and an evaluation of the probable effectiveness of such activity given changes in US industrial employment over that time period. The effectiveness of the sampling program is assessed according to specific criteria including the probability of detecting exceedances of the National Institute of Occupational Safety and Health (NIOSH) recommended exposure limit (REL) for individual pollutants, the trend in the overall hazard level of detected atmospheres, the coverage of industries by worker population, and the cost-efficiency of the program in identifying hazardous atmospheres. Special attention is given to lead, toluene, and various mineral- and metal-based particulate matter, which have all seen new rules implemented in the recent past.

Findings show that the number of samples per employed person has decreased markedly since the beginning of the study period and become less aligned with the changes in population distribution among US regions, however the probability of detecting a hazardous level of a chemical or aerosol pollutant has increased. Extrapolations of this information and the associated changes in industrial sector employment indicate that US workplace atmospheres are marginally less hazardous at the end of the study period than they were at the beginning.
A Vertical Axis Wave Turbine With Hydrofoil Blades
Authors: Yang Yingchen , Diaz Isaiah , Soto Quintero Sergio
Published: February 2017

This work discusses a new wave energy converter (WEC) design that, when deployed in waves, performs unidirectional rotation about a vertical shaft. The uniqueness of this new WEC design is on utilizing omnidirectional water flow generated by waves to drive a rotor to perform unidirectional rotation about a vertical axis. This unique feature circumvents the frequency-dependent issue of common WECs, and eliminate realignment needs to cope with dynamically changing wave propagation directions. The key component of the WEC is a rotor, which has a vertical shaft with a number of blades mounted to it. Each blade has a hydrofoil-shaped cross section and is in a bent shape along its span. The spanwise bending of the blades makes the rotor capable of gaining a unidirectional driving torque about the vertical shaft no matter in which spatial direction the local water is passing by. For validating the WEC design and gaining preliminary understanding, a very first rotor model without any parametric optimization was built. Two types of experiments were then carried out by employing this model. In the first type, the model was translated (with the shaft vertically aligned all the time) in still water along a horizontal direction (back and forth), a vertical direction (up and down), and a circular orbit in a vertical plane. In the second type, the model was exposed in waves generated in a wave flume. In all the experiments, well-established unidirectional rotation of the rotor about its vertical shaft has been observed. The hydrodynamic performance of the rotor in waves was further characterized through systematic experiments under various conditions.
Wireless Interrogation of a High Temperature Antenna Sensor Without Electronics
Authors: Mbanya Tchafa Franck , Yao Jun , Huang Haiying
Published: February 2017

This paper presents a novel interrogation mechanism for an antenna sensor subjected to high temperatures. In sensor node, an Ultra-wide Band (UWB) microstrip antenna was used as a wireless Tx/Rx transceiver to amplify the reflected interrogation signal from the temperature-sensing element, i.e. the patch antenna-sensor. A microstrip delay line was used to connect the Tx/Rx antenna and the antenna-sensor so that the reflected signal from the sensor node is delayed and can be separated from the background clutter using time-domain (T-D) gating technique. In this paper, the principle of operation of the proposed interrogation mechanism is first discussed, followed by the design and simulations of the sensor node circuitry. Finally, a temperature test was conducted to validate the wireless temperature sensing performance of the antenna sensor.
Smart Clutch: An Automated Clutch That Can Be Used in Manual Transmission Driven Vehicles
Authors: Srinath Nitin , Shashidhar Aditya , Shanthamurthy Prajwal G. , Reddy Vedanth , Bhadana Hitesh
Published: February 2017

There are two basic types of transmissions — manual and automatic. While manual transmissions have greater transmission efficiency and better overall driving experience, it is difficult and not as easy to handle as automatic transmissions mainly due to the presence of the clutch pedal. Automatic transmissions make life are a lot easier to operate but are less efficient. So, the aim of this project is to take the best of both worlds and combine it in one i.e. the experience of driving a manual with the ease of an automatic. For this, the intention is to use a pressure sensor to detect when the gears have to be changed and automatically disengage the clutch, hence removing the need for the clutch pedal.
Time-Domain Simulation of Ultrasound Propagation With Fractional Laplacian
Authors: Zhang Junjian , Ke Guoyi , Zheng Z. Charlie
Published: February 2017

The simulation is developed for the purpose of simulating ultrasound propagation through biological tissues. The simulation is based on the time-domain conservation laws with the governing equations for acoustic pressure and velocity, with frequency dependent absorption and dispersion effects. We use forward differencing for velocity and backward differencing for pressure on the non-fractional derivative operator terms in spatial discretization. The fractional Laplacian operators are treated as Riesz derivatives. The shifted standard Grunwald approximation method is used to solve fractional derivative operator terms. To accommodate complicated biological tissue geometries, an immersed boundary method is developed that enables a Cartesian computational grid mesh to be used. The results are compared with those for a non-absorption homogeneous medium to discuss absorption and dispersion effects of biological material.
Fatigue of Coiled Tubing and its Influencing Factors: A Comparative Study
Authors: Li Y. Q. , Gao X.-L. , Ni L. D. , Hu Q. F. , Xin Y. A.
Published: February 2017

Coiled tubing (CT) has been widely used in oil well drilling and servicing. The operation of coiled tubing requires it to travel through the reel and gooseneck repeatedly under high internal pressure loading, which leads to bending fatigue damage of coiled tubing. Hence, it is very important to understand the mechanisms of the fatigue damage and to predict the working life of coiled tubing. The fatigue damage of coiled tubing has been extensively studied by using experiments, finite element simulations, and analytical models. It has been found that most of the fatigue damage of coiled tubing happens under low cycle fatigue conditions. Both stress-based and strain-based models have been employed to describe the fatigue damage of coiled tubing. Due to the severe operating conditions of coiled tubing inside a well, corrosion, ovality, pre-bending, rotation, and mechanical damage should all be considered in the fatigue analysis of coiled tubing. In this paper, mechanisms and influencing factors for the coiled tubing fatigue damage are reviewed, and existing models for the fatigue of coiled tubing are comparatively studied.
Study on the Random Loads and Random Vibration Response of Ring Die Pellet Mill
Authors: Wu Kai , Sun Yu , Cao Chunping , Yang Dong
Published: February 2017

Ring die pellet mill has been widely used in feed industry because of its higher productivity, lower pollution. The random loads and the random vibration response of the machine were studied in this paper to solve the serious vibration during working. According to the operational principles of feeding, gelatinization and spreading process, the model of material thickness unevenness was proposed and the test of motor torque was conducted. According to the experimental and theoretical calculation results, the power spectral density curve model of material thickness unevenness was established. According to the pressure-density relationship in powder compaction process and the pressure distribution in deformation area, the interaction force between roller and ring die was figured out. On this basis, the random loads model was established. The rigid-flexible coupled model of ring die pellet mill was developed in the multi-body software. Dynamic simulations were done to study the random vibration response of ring die, the results revealed that the main vibration frequency of ring die was around the stirring frequency of conditioner blade, the second and third order resonance frequency. Then reasonable ways were proposed to reduce vibration, and were proved to be effective.
Design of a Power Waveform Capture Platform for Plug Load Monitoring
Authors: Hoffbeck Joseph , Dillon Heather , Hildebrand Stephen
Published: February 2017

Plug loads in consumer electronic products consume large quantities of energy, often without the knowledge of the user. To facilitate the development of smart plug strips and new building control systems, an open-source power waveform capture platform has been designed and tested. The system was developed to accurately and safely record the voltage and current waveforms for any plug load such as consumer electronic and electrical systems. The device incorporates a commercially available hardware platform that has been reprogrammed to record the voltage and current waveforms and transfer them in real-time to a computer for storage and further processing. The system samples the voltage and current waveforms with a sampling rate of 2048 Hz, and this detailed data can be used to identify the types of waveforms that are associated with various devices, as well as measure any power parameter of interest such as real power, energy, RMS volts, RMS current, power factor, frequency, etc. The system has been tested with several known electrical loads and has been found to perform well. The paper describes the hardware and software, the test setup, and the test results. Since the hardware is inexpensive (about $250) and the software is available for free from the authors, this system can be used by almost anyone to perform detailed studies of the power characteristics of electrical and electronic devices.
Varied System Geometry and Noise Implementation Applied to Nonlinear Model Tracking
Authors: Doughty Timothy A. , Cassidy Liam J. , Danforth Shannon M. , Pendowski Nicholas
Published: February 2017

The following is a study in nondestructive health monitoring wherein the physical system being studied is excited near resonance and mapped through its transition from health to failure. The system studied is a slender cantilever beam excited near its second natural frequency. For this study, no damage is initiated and so it comes in contrast to the more common techniques where the damage type and location allow for an element of control in instrumentation and analysis. The method implemented allows for health monitoring in situ, so it does not require stopping the event to do system testing, as is the case for many common approaches. Moreover, this method, implements a nonlinear model of the physical system, avoiding false flags that can be problematic for linear-based methods when applied to systems demonstrating healthy nonlinear behavior. The method, known as Nonlinear Model Tracking (NMT) uses a theoretical model of the system that includes a cubic nonlinear stiffness term. Experimentally, stimulus and response data are collected and used in Continuous Time-based system identification to estimate the system’s nonlinear stiffness coefficient. Harmonic fitting to the two recorded data sets allow for robust performance in the presence of noise and variations in the system geometry show that, even in cases where the nonlinear model is not accurate for the system being studied, the method works consistently. In many of the tests the method gives premonition of failure hours in advance, which would in many real world scenarios, gives users time to react safely. This study focusses particularly on varying inputs to the system and attempting to map changes in parameter estimation to stages of damage.
Modelling of Mechanical Systems With Friction Interfaces Considering Variable Normal Contact Load and Tangential Micro/Macro Slip
Authors: Li Dongwu , Xu Chao
Published: February 2017

Mechanical structures with frictionally constrained interfaces often involve complex contact kinematics induced by tangential and normal relative motions. The tangential motion induces stick-micro/macro slip friction and causes energy dissipation. The normal motion induces normal load variation and possible separation of the joint interfaces. For effective analysis of dynamics of jointed structures, a reduced friction contact model is needed to characterize the nonlinear, coupled normal and tangential contact behaviors precisely. However, most developed microslip friction contact models considers only constant normal load.

In this paper, an improved microslip friction model with normal load variation induced by normal motion is proposed. The tangential stick-micro/macro slip friction is modeled by continuous Iwan hysteretic model. This model is characterized by a slippage uniform distribution density function and a linear stiffness at stick state. The coupling relationship between tangential nonlinear restoring force and normal load variation is built. This leads to generalization of the original Iwan hysteretic friction model to consider the effect of variable normal load. The proposed model is applied to model a 7-dofs frictional damping experimental system. The results show that normal load variation and tangential microslip motion exert an important effect on prediction of friction contact behaviors. The proposed model is capable of generating asymmetric hysteresis loops and intermittent normal separation. The numerical simulation fit well with the experimental results for the 7-dofs frictional damping system, which validates the effectiveness and accuracy of the proposed model.
Numerical Simulations of Peristalsis in Unobstructed Human Ureters
Authors: Takaddus Ahmed Tasnub , Gautam Prashanta , Chandy Abhilash J.
Published: February 2017

Urine is transported from the kidney to the urinary bladder through the ureter by peristalsis and pressure gradients. The contractile force acting on the ureter wall has drawn considerable interest in the field of biomechanics. Backflow of urine from bladder to the kidney can occur due to failure of the ureterovesical (ureteral-bladder) junction or blockage in the ureter passage because of recurrent urinary tract infection and also due to formation of stone in kidney. To understand the nature of the flow as well as its effect on the ureter wall, two-way fluid-solid interaction (FSI) modeling of the ureter peristaltic flow at different pressure is required. A transient 2D axisymmetric numerical calculation of ureteral wall peristalsis and urine flow is performed with a fully-coupled monolithic solver using an arbitrary Lagrangian-Eulerian (ALE) method. The ureter is assumed to be a circular tube with successive compression waves traveling downstream. The incompressible Navier-Stokes equations are solved to calculate the laminar flow of urine. The ureter wall is modeled as a non-linear hyper-elastic, nearly incompressible material, by curve fitting the biaxial test data of a human ureter, obtained from literature. Displacement due to peristalsis on ureteral wall is created with a compressive force having a Gaussian bell-curve variation along the length of the ureter, and a certain wavelength specified according to the data found from previous studies. It is observed that, as the compression wave travels from the abdominal part of the ureter towards to the pelvis, it is more likely for urine reflux to occur due to the failure of the ureteropelvic junction rather than the ureterovesical junction.
Finite Element Simulation of PZT-Aided Interrogation of Composite Laminates Exhibiting Damage
Authors: Micheal Amany G. B. , Bahei-El-Din Yehia A.
Published: February 2017

Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due to the presence of multiple damage mechanisms in one or more plies. Simulation of the procedure using advanced computational techniques and material models helps in understanding the reliability of PWAS in sensing damage in fibrous laminates.

This paper combines the finite element method and micromechanical modeling of composites to simulate damage detection using surface mounted PWAS. The finite element solution is obtained by the ABAQUS code with user defined material properties, which reflect the underlying damage modes. The latter are obtained in a preprocessing exercise in which the composite laminate is first subjected to a given mechanical load level and the damage mechanisms in the plies are identified using transformation field analysis, TFA (Bahei-El-Din el al., 2010). In the present work, the Mori-Tanaka averaging model is utilized within the TFA and local failure modes, which are a function of the matrix average stresses were specified. Material properties of the individual plies, which correspond to the damage mechanisms introduced at the given load level are then determined numerically in terms of the overall moduli and utilized in the finite element solution of the laminate using ABAQUS.

The methodology is applied to a quasi-isotropic, symmetric laminated beam subjected to bending. In the finite element simulation, each fibrous composite ply of the laminated beam is modelled using shell elements while the surface mounted PWAS are modeled with 3D solid elements. The bending moment is applied to the beam intermittently to allow interrogation of the laminate by applying a transient electric pulse to the PWAS and allowing the beam to vibrate for a very short period of time, which is followed by reading the voltage response. The voltage readings are correlated to the damage mechanisms in the plies.
Design, Analysis and System-Level Modelling of a Single Axis Capacitive Accelerometer
Authors: Mohammed Zakriya , Waheed Owais Talaat , Elfadel Ibrahim (Abe) M. , Chatterjee Aveek , Rasras Mahmoud
Published: February 2017

The paper demonstrates the design and complete analysis of 1-axis MEMS capacitive accelerometer. The design is optimized for high linearity, high sensitivity, and low cross-axis sensitivity. The noise analysis is done to assure satisfactory performance under operating conditions. This includes the mechanical noise of accelerometer, noise due to interface electronics and noise caused by radiation. The latter noise will arise when such accelerometer is deployed in radioactive (e.g., nuclear power plants) or space environments. The static capacitance is calculated to be 4.58 pF/side. A linear displacement sensitivity of 0.012μm/g (g = 9.8m/s2) is observed in the range of ±15g. The differential capacitive sensitivity of the device is 90fF/g. Furthermore, a low cross-axis sensitivity of 0.024fF/g is computed. The effect of radiation is mathematically modelled and possibility of using these devices in radioactive environment is explored. The simulated noise floor of the device with electronic circuit is 0.165mg/Hz1/2.