bluuebunny/crossref_metadata_2025 huggingface dataset:
Wavelet Analysis for Spindle Vibration Signal Processing Under Non-Uniform Preload
Authors: Zhang Yanfei , Wang Sun’an , Li Xiaohu , Liu Guanghui
Published: March 2016

Skewing or dislocation installation of a bearing in a spindle will be subjected to uneven loads caused by machining error, assembly error and thermal deformation. Bending moment will be induced by the uneven force around the center of bearing. Non-uniform preload methodology is proposed in this paper aiming to stimulate the skewing installation in a spindle. Wavelet threshold technique for noise reduction and wavelet package method for feature extraction were introduced in order to identify the bearing posture through analyzing the vibration signal of the bearing. To validate the proposed method, the raw vibration signals are reconstructed, the eigenvector is structured and normalization processing is done between uniform preload and non-uniform preload conditions, respectively. The analysis results shows that the wavelet packet threshold de-noising technology can effectively eliminate the noise of the spindle vibration signal. The bearing posture identification and bearing preload identification are realized through the change of frequency energy.
Panorama of the Market Demand for Mechanical Engineers in South American Countries
Authors: Cardenas Ronald A. , Bello Kevin S. , Valle Alexander R. , Villota Elizabeth R. , Coronado Alberto M.
Published: March 2016

Many educational institutions employ surveys in order to identify what majors to offer or what competencies to emphasize in their curricula. Different from a survey, we present an analysis of the labor market needs based on data collected from job ads available in the Internet. Tools of natural language processing (NLP) and statistical techniques have been employed to handle the job ads. For Peru, Chile and Colombia, a detailed panorama of the market demand has been depicted: mechanical engineering appears among the top most demanded engineering majors and maintenance is its most frequent technical requirement; management (project, quality and operations) related requirements also rank high, together with a working knowledge of English. By using diverse visualization techniques we can also show the “social network” of a major, where friendship is defined by the amount of job ads shared by any two majors.
Effects of Surface Conditions for Different Climatic Zones in Turkey on Temperature Distribution in the Soil
Authors: Kayaci Nurullah , Demir Hakan , Atayılmaz Ş. Özgür , Ağra Özden
Published: March 2016

Ground Heat Exchangers (GHEs) are an important parts of Ground Source Heat Pump (GSHP) systems and its dimensions and burial depth should be calculated using an effective method considering surface conditions. Particularly, the cost of the assembly of GHE affects the choice of these systems. For efficiency of the GSHP system, the heat extracted from or dissipated to the soil should not be changed by time for longer period runs of GSHP systems. Typical values for Coefficient of Performance (COP) of Ground Source Heat Pumps (GSHPs) are up to 8 while it is 4 of air source heat pumps. Soil composition, density, moisture and burial depth of pipes affect the size of a GHE. The burial depth and the distance between the pipes are important for sizing the GHE. Because of the complexity of the boundary conditions, a numerical study was conducted to investigate the effects of time-dependent external weather conditions, burial depth, soil thermal properties and extracted heat from soil on temperature distribution in the soil. Heat transfer in the soil is time dependent three dimensional heat conduction with dynamical boundary conditions. The GHEs consist of pipes buried in the soil and are used for transferring heat between the soil and the heat exchanger pipes of GSHP. Numerical analysis performed in ANSYS software using a UDF for dynamical boundary conditions. In order to provide the periodic variation of air temperature boundary at upper surface condition was written a User Defined Function (UDF) and it can be interpreted in ANSYS Fluent. Likewise, a UDF was also written to give constant heat flux intermittently for the pipe inner surface. Temperature distribution in soil were obtained for different climatic zones and burial depths of 1–2 m. It was seen that the surface conditions of different climatic zones has great importance up to a critical value of burial depth.
Axial Balance of External Gear Pumps and Motors: Modelling and Discussing the Influence of Elastohydrodynamic Lubrication in the Axial Gap
Authors: Borghi Massimo , Zardin Barbara
Published: March 2016

This paper focuses on the analysis of hydraulically balanced external gear pumps, in particular on the lubricating gap between the bushes and the gears. This topic is of key importance for the optimization of the machine efficiency because it both influences the mechanical-viscous friction and the volumetric losses.

In this paper the intent is to investigate the role of the elastic deformation of the bushes surfaces, to compare the analysis done with rigid and elastic surfaces and finally to correlate the results with the design of the bushes balancing surfaces. A numerical procedure for the determination of the pressure distribution inside the gap bounded by gears sides and the bushes internal surfaces is presented and applied.

With respect to past works of the authors, the procedure has been integrated taking into account the elastic deformation of the internal surfaces of the bushes and the variation of the dynamic viscosity of fluid, two well recognized phenomena that can play a key role on the determination of the bushes behaviour and lubricating gap pressure distribution.

It is shown that, when the design of the bushes rear surfaces determines a strong balancing thrust, the bushes themselves need to tilt strongly with respect to the gears to generate an opportune widening thrust to avoiding contact with the gears. Useful suggestions for the bushes balancing surface design may be drawn from the analysis of the balancing maps reported in the paper, which illustrate the widening thrust magnitude and position in both the pure hydrodynamic and elasto-hydrodynamic cases, for different tilted positions and operating conditions.
3D Finite Element Stress Analysis of an Implant Supported Overdenture Under Bruxism and Lingualized Loading Conditions
Authors: Hasan Md Abu , Shiakolas Panos S.
Published: March 2016

Bruxism is a nonfunctional motor activity that is characterized by grinding and clenching of the teeth. It has been postulated that bruxism causes excessive occlusal load on the dental implant and its superstructures leading to biological and biomechanical complications. While many researchers suggest that grinding/clenching causes early implant complications and accelerated bone loss, others indicate that the long term effects are still unclear. The goal of this study is to analyze the effect of bruxism loading condition on the stress distribution of an implant supported overdenture (ISO) using finite element analysis (FEA) and compare the results with one of the most functionally efficient occlusion schemes in the clinical dentistry — lingualized occlusion. A high fidelity solid model of a mandibular denture encompassing lingual and buccal cusps, mesial and distal fossae supported by four implants and a connecting titanium prosthetic bar, resting on alveolar bone were modeled in SolidWorks 2013 following proper clinical guidelines and imported to ANSYS 15.0 for stress analysis. The results of the study demonstrate that the stress distribution in the implant prostheses and surrounding bone is significantly affected due to bruxism as compared to the lingualized loading. While the location of the maximum stress concentration was the same (neck of the posterior implants) for both loading conditions, there was an increase of approximately 115% von-Mises stress for bruxism loading condition as compared to the lingualized occlusion. The maximum principal stress in the cortical bone surpassed the ultimate tensile strength limit of the jaw bone implying possibility of bone resorption in the peri-implant area.
Towards a Theory Based Approach to Product Safety
Authors: Nordlund Mats
Published: March 2016

Accidents in industry, medical clinics, and transportation lead to loss of lives and property. The costs for such accidents are very high to society, industry and individuals. Recent examples of high profile accidents include the Fukushima disaster and several aircraft accidents. Accidents in hospitals cost as much as $29 Billion per year (WHO estimate) in additional hospitalization, disability, lost income, medical expenses and litigation.

Looking at different industries, safety levels are very different. For example, there is a one in a million chance of getting harmed while in an aircraft. In comparison, there is a one in 300 chance of a patient being harmed during health care.

Current best practices to increase product safety uses methods which were developed during the period between World War II and 1970. They are essentially based on heuristics around designing and operating systems that were a lot less integrated and complex than current systems, and contained a lot more human participation in the system. A few science-based approaches have began to emerge in recent years.

This paper presents the hypothesis that in addition to the benefits proven in traditional design practice, the design axioms can form a scientific basis for an effective method to analyze designs from a product safety perspective.

The main cause of the 2005 Buncefield overfill accident in the UK is analyzed using an axiomatic approach to safety. Using the rigor of axiomatic design, it is possible to identify the shortcomings in the design that caused the accident. The same approach is then applied to an alternative solution. The result of this analysis is that the new design should be much more reliable than the previous.

In the conclusion, it is shown that it is possible to develop a science base for product safety based on Axiomatic Design. It is shown that such a science based approach enables design practitioners to approach unfamiliar safety related situations in a systematic way to identify risks and propose alternative designs with a lower risk level.
Numerical Analysis of Liquid Breakup and Drop Generation in Low Velocity Jets
Authors: Rajendran Sucharitha , Jog Milind A. , Manglik Raj M.
Published: March 2016

Biological sprays and aerodynamically assisted bio-jets are increasingly employed in treatment of living cells and organisms for applications in regenerative medicine, tissue repair, and advanced therapeutics. The liquid used in biological applications cover a wide range of viscosities and surface tensions. Determining conditions that achieve steady and uniform drop distribution for a range of properties of the liquid jet is critical in advancing biological applications.

In this study, numerical simulations of jet breakup are carried out using a modified volume of fluid (VOF) approach to capture the interface. The interplay of viscosity and surface tension is studied by varying liquid properties. Simulations show that a high viscosity jet stretches and elongates before a liquid segment detaches. Based on the thickness of the liquid thread connecting the detaching drop to the main liquid stream, two fundamentally different modes of liquid pinch off have been predicted: thick-thin and thin-thick. In the thick-thin mode, the liquid jet has a growing drop at its edge. As this drop grows in size, the liquid stream stretches till the drop is pinched off the liquid stream. In the other mode in addition to the pinch off of drops from the jet, ligaments of liquid break off. The change in the breakup mode is primarily governed by the relative magnitude of the viscous force compared to surface tension with high viscous force leading to thin-thick liquid stretching and pinch off. Thick-thin stretching is seen to produce slow moving satellite drops that merge backwards with the oncoming drop, while thin-thick stretching is noticed to result in faster satellite drops that merge forwards. On the other hand when surface tension force dominates, non-merging satellite drops are formed that move with a speed close to the primary drops.
Gradient Index Devices for the Simultaneous Focusing of the Fundamental Modes in Thin Elastic Plates
Authors: Torrent Daniel , Pennec Yan , Djafari-Rouhani Bahram , Jin Yabin , Pan Yongdong
Published: March 2016

Gradient index devices for the simultaneous control of the S0 and A0 Lamb modes are presented and numerically analysed. It is found a special relationship between the refractive indexes for these two modes which allows their simultaneous control by means of graded phononic crystals and thickness variations of the plate. A flat gradient index lens and a circular Luneburg lens are designed. Numerical simulations show that the performance of these devices is good for the two modes in a broadband frequency region, and that this approach can be used to design more advanced refractive devices for the total control of guided vibrational modes.
Applying NURBs-Based Surrogate Models for Performance Forecasting in Manufacturing Systems
Authors: Anderson Daniel , Turner Cameron J.
Published: March 2016

Manufacturing companies require systems that can respond to disruptions and be reconfigured quickly. The use of simulation to improve efficiency is particularly common; however, realistic and accurate simulations are computationally expensive. To save on computational expense, a facility manager can make use of a computationally efficient surrogate model that approximates the response of the simulation. This work implements a novel method of approximating throughput of a simulated manufacturing environment using Non-Uniform Rational B-splines (NURBs) as the basis for surrogate models. In three scenario studies, NURBs-based surrogates accurately approximate simulation outputs, with surrogate model query times ranging from 2 to 4 orders of magnitude faster than estimated evaluation times for corresponding simulations. These findings indicate that NURBs-based surrogates are a promising method of approximating manufacturing simulations for performance forecasting.
An Experimental Investigation of the Primary Atomization of Viscoelastic Impinging Jets
Authors: Rodrigues Neil S. , Gao Jian , Chen Jun , Sojka Paul
Published: March 2016

The primary atomization of a viscoelastic liquid was experimentally investigated using a water-based solution of 0.1 wt.-% xanthan gum (XG). Shadowgraphy images were obtained to qualitatively study the impinging jet spray formation and Phase Doppler Anemometry (PDA) was used to measure the drop diameters and drop velocities. The viscoelastic behavior was observed to hinder atomization when the effect of the inertial force was relatively insignificant. However, increasing the inertial force led to the spray patterns transitioning towards the ligament structures and fully developed patterns. D10, D32, and MMD drop diameters were observed to decrease with increasing inertial force and were larger than mean diameters of a water spray at similar conditions. The mean axial drop velocity was observed to increase with increasing inertial force.
MPC Control of Dynamic PEM Fuel Cell System
Authors: Fontalvo Morales Victor Manuel , Sanjuan Marco , Gómez Vega Humberto
Published: March 2016

This paper presents, an open cathode fuel cell dynamic model and an advanced control system design that allows to study the transient response of the system and its nonlinearities. The model can be used to design control strategies and design test benches to test fuel cells stacks. A dynamic performance characterization is performed (transient response to disturbances or setpoint changes), and the information is used to propose the structure of a control system capable of incorporating expert information and transition in non-linear regions. The model used in the simulation takes account of three different phenomena: (a) mass transfer, (b) thermodynamics and (c) electrochemical. The fuel cell uses hydrogen and air to generate electricity. The hydrogen is supplied to the fuel cell anode and the air is supplied to the fuel cell cathode. This model allows the calculation of the pressure and mass flow circulating in the cell. Balances are presented for cathode, anode and membrane. The energy balance proposed includes the electrochemical reaction that is exothermic and the heat transfer to the air flowing through the cathode which has to supply the electrochemical reaction with the oxygen required and regulate the stack temperature. The ideal electric potential of a fuel cell is defined by the Nernst equation. The Nernst equation alone is not enough to describe the electrical potential during the actual operation of the system. The main sources of voltage loss are presented: Activation, electrical resistance and concentration. PEM control system is designed and simulated. A model–based algorithm is used to achieve different objectives than could lead to an improvement in the system performance. Results demonstrate that the predictions in voltage and current in the fuel cell stack are close to experimental data obtained from manufacturer. Constraints in the algorithm allow avoiding hazardous operational conditions and a decrease in controlled variable variance.
Falling Body Impact Behavior of Fiberglass Stepladders With Plastic Knee Braces
Authors: Wodin-Schwartz Sarah , Bove Robert , Verghese Paul , Kennedy Eugenia
Published: March 2016

According to estimates reported in the U.S. Consumer Product Safety Commission’s National Electronic Injury Surveillance System, there were greater than 10,000 stepladder related injuries treated in hospital emergency rooms nationwide per year in the period from 2009 through 2013. Research and experience have sought to correlate specific stepladder damage patterns to the causes of some injuries involving stepladders. Prior studies have associated a specific damage pattern — inward deformation of the stepladder’s front side rails — with impact loading of a user’s body onto the lower portion of a front side rail following a fall from the stepladder. Those prior studies were conducted using stepladders with metal knee braces and with the ladder cap simply supported during impact testing. Currently sold fiberglass stepladders often have plastic rather than metal knee braces. In our study, side rail impact testing was performed in order to evaluate how a design change from metal knee braces to plastic knee braces affects impact damage patterns in fiberglass stepladders. Biomechanics simulations were used to inform the selection of the weights used for impact testing and allowed the test results to be evaluated in the context of potential body contact scenarios that could produce equivalent loading of the side rail. Our study demonstrates that depending on the weight of the impacting body, fiberglass ladders with plastic knee braces show different dynamic responses to impact loading than do their metal counterparts. Additionally, the test methods in this study incorporate realistic dynamics in that the weight impacted the lower portion of the stepladder’s front side rail while the stepladder was actively tipping with only two of its feet in contact with the ground and with the top cap unsupported.

The results indicate that ladders with metal knee braces can permanently deform when impacted with loads less than that required to permanently deform the ladders tested with plastic knee braces. The absence of permanent side rail deformation in the plastic knee braced stepladders tested even after undergoing significant elastic deformation during testing gives rise to new questions about the potential for damage that is not observable based on a visual examination.
Effects of the Structural Layer Material and its Thickness on Positive Displacement Piezoelectric Micropump Performance
Authors: Sayar Ersin , Farouk Bakhtier
Published: March 2016

Structural dynamic and fluid flow analysis of positive displacement piezoelectric micropumps are carried out for microfluidic water transport applications. The micropump consists of trapezoidal prism inlet/outlet elements; the pump chamber; a thin structural layer and a piezoelectric transducer element. Governing equations for the flow fields; the structural-piezoelectric bi-layer membrane motions and electrical variables are considered. Two-way dynamic coupling of forces and displacements between the solid and the liquid domains in the systems are considered. The effects of the structural layer material selection and the thickness of thin structural layer on the structural deformation and fluid flow are investigated. The variation the structural layer material and its thickness enable the selection of the best micropump design among the investigated micropumps made of silicon and Pyrex glass while other parameters are kept unchanged. The change of the structural layer material is considered here through the variation of density, Young’s modulus and Poisson’s ratio. Optimum membrane thickness is also investigated aiming to generate higher rates of time-averaged flow for the selected micropump structural layer material. The present study is useful in the implementation of the micropumps into lab-on-a-chip microfluidic systems.
Experimental Study on Radiant Floor Heating System
Authors: Ngo C. C. , Alhabeeb B. A. , Balestrieri M.
Published: March 2016

Radiant floor heating systems have become popular due to their advantages over conventional heating systems in residential, commercial and industrial spaces. They are also used for snow and ice melting and turf conditioning applications. This paper presents a general study focuses on the design of radiant floor heating systems and investigates the effect of design parameters such as pipe spacing (ranging from 4 in. to 12 in.), pipe depth (ranging from 2.5 in. to 6.5 in.) and pipe temperature (45 °C, 65 °C and 85 °C) on the performance of radiant floor heating system embedded in different mediums (air, gravel and sand). The experimental results showed that a radiant heating system with pipes embedded at a shallow burial depth and placed closer together resulted with a more desired floor temperature distribution. The average floor temperature was also higher when the piping system was embedded in an air-filled space instead of a porous medium such as gravel or sand.
Compound Droplet Modelling of Circulating Tumor Cell Microfiltration
Authors: Zhang Zhifeng , Xu Jie , Chen Xiaolin
Published: March 2016

The Circulating Tumor Cell (CTC) is the cancer cell that has shed into the circulation system (i.e. cancer cell in the bloodstream). These CTCs are potential indicators for early cancer detection, which is critical for the whole process in cancer treatment. Among all new techniques, early detection of cancer from a single blood drop sample using the mechanical method by CTC microfiltration is promising for its simplicity, low cost, and ease of use. In the microfiltration of circulating tumor cells, the problem of a single CTC passing through a microfilter at a constant flow rate is a basic model for further device design and optimization. In our present paper, we developed a compound droplet model for the CTC passing through a microfilter. Numerically, we used the Volume of Fraction (VOF), three phase flow method. In this model, we take the blood, CTC cytoplasm and CTC nucleus as three individual fluids/phases. To build a more realistic model, the CTC cytoplasm and nucleus are taken as two fluids with their own surface tension coefficients and viscosities; the viscosity of the cytoplasm is considered as twice that of the bloodstream; the stiffness of the nucleus is set as four times that of the cytoplasm. Through the pressure signature and CTC deformation, the interaction between the compound droplet CTC, bloodstream, as well as the channel wall are studied numerically. As demonstrated in the previous Newtonian single droplet model, this critical passing pressure can be predicted by Young-Laplace equation. However, for the compound droplet model, no equation description is available. Through our study, the critical passing pressure, as well as the dynamic process of CTC passing pressure signature, is provided together with corresponding CTC deformation in each key stage. The pressure signature and deformation difference between the simple droplet model and compound droplet model are also compared. Additionally, the biological parameter, like the radius of cancer nucleus, is also an important parameter in the early cancer detection device design. In the following part of our study, we introduced a clinical parameter called N/C ratio, or nucleus/ cytoplasm ratio, which is a key parameter to discriminate between the healthy cell and tumor cell. By bringing this parameter into our study, the interaction among the nucleus, cytoplasm, bloodstream, as well as the wall of microfilter are studied for soft, medium and hard CTCs. In the end, the drawback of our method is also provided with advice for improvement.
Thermal Performance of Sierpinski Carpet Fractal Fins in a Natural Convection Environment
Authors: Calamas David , Dannelley Daniel , Keten Gyunay , Hines Philip
Published: March 2016

When certain fractal geometries are used in the design of fins or heat sinks the surface area available for heat transfer can be increased while system mass can be simultaneously decreased. In order to assess the thermal performance of fractal fins for application in the thermal management of electronic devices an experimental investigation was performed. The experimental investigation assessed the efficiency, effectiveness, and effectiveness per unit mass of straight rectangular fins inspired by the first four iterations of the Sierpinski carpet fractal pattern. The thermal performance of the fractal fins was investigated in a natural convection environment. While fin efficiency was found to decrease with fractal iteration fin effectiveness per unit mass increased with fractal iteration. In addition, a fractal fin inspired by the fourth iteration of the Sierpinski carpet fractal pattern was found to be more effective than a traditional straight rectangular fin of equal width, height, and thickness. When compared to a traditional straight rectangular fin, or the zeroth fractal iteration, a fin inspired by the fourth fractal iteration of the Sierpinski carpet fractal pattern was found to be 4.87% more effective, 15.19% less efficient, and 67.98% more effective per unit mass. The amount of the total heat transfer attributed to thermal radiation was also dependent on fractal iteration. Thermal radiation accounted for 45.52% of the total heat transfer for the baseline case, or zeroth fractal iteration. Thermal radiation accounted for 51.94%, 50.17%, 52.77%, and 66.62% of the total heat transfer for the first, second, third, and fourth fractal iteration respectively.
Analysis of In-Plane Compression and Bending of Honeycombs With Laminated Cell Walls
Authors: Wang Ruoshui , Wang Jyhwen
Published: March 2016

Using laminated composite cell walls in honeycomb structures can bring potential advantages such as increased specific stiffness, greater options for material selection, and very importantly, improved manufacturing efficiency. In this paper, the in-plane elastic responses of honeycomb structures with laminated composite cell wall are investigated. An analytical model was developed to obtain the effective elastic properties of the honeycombs based on the laminate properties of the cell wall. The derived homogenization properties were then used to predict the in-plane compression and bending behaviors of the structures. The predicted results were compared with those from finite element analysis of the full detailed honeycomb models. The results of the homogenized solid model, with significant computational cost savings, were in good agreement with those of honeycomb models with full geometric details. It was also demonstrated that the proposed model can be effectively and efficiently used for composite cell wall design and material selection.
Simulating Axial Force at the Substrate of Growing CNT Forests
Authors: Ajiboye Damola M. , Maschmann Matthew R.
Published: March 2016

A time-resolved carbon nanotube (CNT) forest synthesis model is used to examine the mechanical interactions of actively growing CNT forests. Discrete CNTs in the forest are modeled using linear elastic Euler-Bernoulli beam elements with three degrees of freedom at each node which corresponds to axial displacement, transverse displacement and rotation. The van der Waals force between adjacent CNTs is modeled as linear elastic spring elements and act to locally bond adjacent CNTs in contact. Special consideration is given to the axial forces that arise at the substrate of growing CNTs during the forest growth. While reaction forces are distributed in a spatiotemporal manner, we observe that reaction forces for the slowest growing CNTs are greatest, and in tension, while the fastest growing CNTs experience compressive reaction forces at the substrate.
Analysis of Numerical Simulation of Gas-Liquid Slug Flow Using Slug Tracking Model
Authors: Cavalli Stella C. P. , Cozin Cristiane , Barbuto Fausto A. A. , Morales Rigoberto E. M.
Published: March 2016

The distribution of the interfaces in gas-liquid two-phase flows in pipes can assume several shapes. Amongst those shapes, the slug flow pattern stands out as the most common one and occurs quite often in oil and gas production due to the flow rates and geometries used. This pattern is characterized by the succession of the so-called unit cells, that is, a flow structure composed of an aerated liquid slug and an elongated bubble surrounded by a liquid film. Due to its complexity, the study and understanding of this pattern’s behaviour becomes very important. The main methodologies used to describe slug flows are the steady-state one-dimensional models, based on the slug unit concept, and the transient approach, which takes the flow intermittence into account. The slug tracking model is one such transient approach, which considers slugs and elongated bubbles as separated bodies and analyzes the evolution along the flow and the interaction between those bodies. Whenever this model is numerically implemented, its initial conditions are important parameters that affect the results. The goal of this article is to study the influence of the initial conditions on slug flow simulation using the slug tracking model. A computer program written in Fortran95 using a slug tracking model to provide the characteristic parameters of slug flows such as the bubble and slug lengths and void fraction in the bubble region was built and used. The results were compared to experimental data and showed the important role the initial conditions play on the computational simulation of slug flow.
Thermoeconomic Design of Borehole Thermal Energy Storage Systems
Authors: Cosentino Sara , Sciacovelli Adriano , Verda Vittorio
Published: March 2016

Borehole thermal energy storage (BTES) is an option to provide large-scale seasonal storage of cold and heat in natural underground sites. Boreholes are used to transfer heat from the working fluid to the ground in charging phase and vice versa in discharging.

The design of boreholes influences system efficiency, installation costs and the charging time required to reach the design temperature in the ground. The latter can result too long but may be reduced significantly through the selection of an optimal design and a storage temperature that maximizes the efficiency. Nevertheless high performances are usually accompanied by high purchase and installation costs of the borehole exchangers. The increase in efficiency and the decrease of investment costs are two conflicting objectives that must be considered in the design stage to select the best configuration.

This work is focused on the optimal configuration of BTES in which the boreholes are used to charge the ground to the design temperature and to supply the thermal energy demand during the operation. Several designs are explored at two different levels of temperature in the storage.

A novel design strategy, based on energy, exergy and thermoeconomic analysis, is proposed to select the optimal configuration that guarantees a balance between expenditure on capital costs and exergy efficiency. This constitutes a novel approach which ensures high performances of BTES systems for long periods of operation, which is an interesting area of research that is currently not sufficiently explored.
Dynamic Divergence Mechanism in Shells With Internal Axial Flow
Authors: Karazis Kostas , Païdoussis Michael P.
Published: March 2016

Recent experimental studies have shown that supported tubes with internal fluid flow lose stability by dynamic divergence which is well modelled by the sloshing mechanism described in the work by Heil & Boyle and Heil & Hazel. In this study thin tubes supported at both ends subjected to axial internal fluid flow are investigated experimentally and numerically. Experiments for different L/R ratios were conducted for elastomer thin tubes clamped at both ends and subjected to internal air-flow. The numerical analysis is based on geometrically nonlinear structural equations coupled with potential flow theory to describe the fluid-structure interaction. The theoretical model employs the Donnell nonlinear shallow shell equations to describe the geometrically nonlinear structure. The clamped beam eigenfunctions are used to describe the axial variations of the shell deformation, automatically satisfying the boundary conditions and the circumferential continuity condition exactly. The fluid is assumed to be incompressible and inviscid. The partial differential equation of motion is discretized using the Galerkin method and the final set of ordinary differential equations is integrated numerically using pseudo-arclength continuation and collocation techniques and the Gear backward differentiation formula. The current study investigates experimentally the dynamics of tubes with L/R∼1, L/R∼2 and L/R∼3 in axial internal flow. The experimental results indicated that the tubes lost stability by dynamic divergence resembling the Heil & Boyle Type B oscillatory scenario discussed in Païdoussis (2014). For the L/R∼2 case the amplitude of the maximum shell deformation observed in the experiments was extracted using digitized images from the experiments. The numerical results were analyzed using bifurcation theory predicting that the tubes lose stability by static divergence exhibiting large hysteresis. The numerical results produced for all cases presented in this paper do not predict tube oscillatory solutions for the range of flow velocities considered in this analysis. For the L/R∼2 case, which was also modeled in this paper, the numerical results are in good agreement with experiments for the maximum tube amplitude.
Robustness Analysis of Algorithms to Estimate Constitutive Laws of Biological Filaments
Authors: Gray Jessica , Fatehiboroujeni Soheil , Goyal Sachin
Published: March 2016

The structure-function relationship of biological filaments is greatly impacted by their mesoscale mechanics that involves twisting and bending deformations. For example, the mechanics of DNA looping is a key driver in gene regulation. The continuum-rod models have emerged as efficient tools for simulating the nonlinear dynamics of such deformations. However, there is no direct way to derive or measure the constitutive law of biological filaments for their continuum modeling. Therefore, it is an active area of research to develop inverse algorithms based on a continuum rod model that can estimate the constitutive law from the atomistic configurations of the filament. This paper presents a set of such algorithms that can use data from the dynamic states of deformation obtained from atomistic simulations or other sources. Depending on the kinematic quantities that are computed from the configuration data, the inverse algorithms differ in their steps to estimate the internal restoring moments and forces. The paper investigates and compares the robustness of these inverse algorithms accounting for the effect of noise in the data.
Inverse Determination of Temperature Distribution in Partially Cooled Heat Generating Cylinder
Authors: Patil Sandeep , Chintamani Siddarth , Grisham James , Kumar Ratan , Dennis Brian H.
Published: March 2016

Inverse determination of the temperature distribution in the interior of a solid has been an area of interest in recent years. Conventional measurement devices, such as thermocouples or pyrometers, cannot be used to determine the interior temperature, but they can be used to determine the surface temperature. From this surface temperature, the temperature distribution in the interior can be estimated using an inverse method. If the maximum temperature is more than melting point of material then it may result in catastrophic accidents for some particular applications like nuclear fuel rods. Thus, knowledge of the temperature distribution on the interior is important.

In this paper, numerical solution approach involving finite volume method along with MATLAB Optimization Toolbox is used to determine the temperature distribution in the interior of a solid object.
Design and Analysis of Electric Bikes for Local Commutes
Authors: Moore Preston , Vande Velde Chase , Wagner Richard , Depcik Christopher
Published: March 2016

In today’s society, those who do not take advantage of public transportation services typically drive personal vehicles to school, work, and other locations of interest. Due to the required amount of physical exertion, walking or riding a bike is often avoided. This is concerning given that a large percentage of carbon and hazardous emissions emanate from motor vehicles. This creates a need for an alternative means of travel for shorter commutes with electric bikes (e-bikes) one potential solution. They have zero tailpipe emissions and significantly lower overall emissions relative to motorized vehicles; however, their cost often prevents them from being readily marketable. In order to address this issue, two undergraduate capstone design teams have constructed e-bikes using recycled and donated parts over the past two years.

In the first year, the runner from a pickup truck was scavenged from a junkyard and employed as the frame to provide for the greatest environmental benefit. However, this resulted in an odd bicycle shape because of limited material availability. As a result, the second years team decided to use a donated chrome moly tube as the frame while focusing on ergonomics and aesthetics. This second bike was designed so that a male rider of average height (5′10″ – 1.78 m) could complete commutes of several miles in relative comfort. Both e-bikes employ a direct drive motor (first year – front wheel; second year – back wheel) to provide assistance when needed, leaving the rider less fatigued. To promote further development in electric bike design, each team has made a considerable effort to record the design process with highlights presented in this effort. Furthermore, e-bike testing results are presented including center of mass calculations, braking distances, turning radii, and overall efficiencies quantified by the miles traveled using the same battery pack. This information will be used to compare the bikes against each other in order to illustrate bike attributes that are desired when an electric motor is employed.

The result is an appealing, cost-effective, and efficient electrical bike that will greatly reduce traffic related emissions should it become widely implemented. Given the issues related to transportation at a university (e.g., available parking) including the reticence of students to traverse long distances across campus to attend classes, it is believed that this effort can serve as a model example to other universities who might see e-bikes as a potential solution to reducing congestion and improving student attendance.
Design of a MRI-Visible and Radiopaque Drug Delivery Coating for Bioresorbable Stents
Authors: Goodfriend Amy C. , Welch Tré R. , Wang Jian , Nguyen Kytai T. , Johnson Romaine F. , Xu Chet C. , Veeram Reddy Surendranath R. , Nugent Alan , Richardson James , Forbess Joseph M.
Published: March 2016

Cardiovascular stents are currently being used for intraluminal stenting of the trachea for tracheomalacia treatment. These devices composed of permanent materials are controversial due to their limitations at internal reinforcement and biocompatibility, especially in pediatrics. We show in a pediatric tracheomalacia rabbit model, a poly-L-lactic acid (PLLA) Double Opposed Helical bioresorbable stent (DH) elicits a more mild inflammatory response in the malacic airway compared to a control metal stent. To further improve efficacy, a multi-drug delivery, bioresorbable coating was designed. The coating design controllably delivers ciprofloxacin (antibiotic) for one week and dexamethasone (anti-inflammatory agent) for three months. The bioresorbable polymeric components also demonstrate feasible visibility utilizing Magnetic Resonance Imaging (MRI). The local multi-drug delivery and imaging capabilities in this coating design in combination with the bioresorbable DH stent will result in a successful intervention specifically design for pediatric tracheomalacia. This design will eliminate long-term risks associated with current permanent devices and provide necessary theranostic agents to facilitate healing and monitor progress via non-invasive imaging techniques.
Crane Workspace Mapping via a Scanning Laser Rangefinder
Authors: Domingue Beau , Vaughan Joshua
Published: March 2016

Cranes are common tools used in industry globally. Significant work has been done to increase the safety of cranes, but danger still arises in the presence of operator error. This paper introduces a crane workspace mapping method via a scanning laser rangefinder to help prevent collisions due to an operator’s poor knowledge or view of the workspace. The developed mapping algorithm identifies obstacles within the crane workspace, then, generates and displays a 2D map of it. To demonstrate the proposed algorithm, an example map is generated for a small-scale bridge crane workspace.
Design and Analysis of Internal Gears With Different Rim Thickness and Shapes
Authors: Karpat F. , Ekwaro-Osire S. , Yilmaz T. G. , Dogan O. , Yuce C.
Published: March 2016

In recent years, thanks to their significant advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations, internal gears have been used in automotive and aerospace applications especially in planetary gear drives. Although internal gears have a number of advantages, they have not been studied sufficiently. Internal gears are manufactured by pinion type cutters which are nearly identical with pinion gear except the addendum factor which is 1.25 instead of 1. The tip geometry of a pinion type cutter which determines the fillet of internal gear tooth can be sharp or rounded. In this study, the design of internal gears were investigated by using a traditional approach. Mathematical equations of pinion type cutter were obtained by using differential geometry, then the equations of internal gear tooth were derived accurately by using coordinate transformations and relative motion between the pinion type cutter and internal gear blank. A computer program was generated to attain points of internal gear teeth and three dimensional design of complete gear. 20°-20° were used as pressure angle. To find optimum internal gear geometry, different rim thicknesses and shapes are tried out for finite element analyses. There were several parameters that were shown to effect the performance of the internal gears, with tooth stiffness being the most significant parameter. Tooth stiffness was also vitally influence the dynamic analysis. In order to compute gear tooth stiffness of the internal gear with various rim thicknesses and shapes, finite element analysis was used. A static analysis was performed to assess the gear bending stress and tooth displacement. Tetrahedral element type was selected for meshing. The internal gear outer ring was fixed and the force of 2500 N was applied on the tooth. According to the displacement values from the analysis internal gear tooth stiffness were calculated individually. Additionally, the effect of root bending stress with varying rim thickness, shapes, and root radius were investigated. The bending stresses were calculated according to ISO 6336 and using finite element analysis were shown to be in good agreement. It was shown that when the rim thickness and fillet radius were increased, the maximum bending stresses decreased considerably. As rim thickness was increased, the maximum bending stress decreased nearly 23%. It was also shown that as the fillet radius decreased, the maximum bending stress increased, whereas the rim stresses slightly changed. As the fillet radius was decreased, the maximum bending stress increased nearly 10%. It was also observed that when rim thickness was increased, the stress on the rim was decreased, whereas tooth stiffness was increased. However, fillet radius had no visible effect both on rim stress and tooth stiffness. Furthermore, it was shown that the rim shape had significant effect on rim stress.
Effect of Extended Surfaces on Temperature Distribution Inside a Fixed-Bed Biofuel Pyrolysis Batch Reactor
Authors: Tillmutt Kamau M. , Biney Paul O.
Published: March 2016

This paper investigates the improvements in the temperature distribution of biomass in an alternative design of fixed-bed biofuel batch reactor while undergoing fast pyrolysis, compared to the conventional design. The reactor furnace temperature was selected based on optimum pyrolysis temperature and appropriate convective heat transfer coefficient was computed and used with corresponding boundary conditions for transient thermal analysis using ANSYS software. For the 3-D model, about eighty-one thousand and sixty-eight thousand elements were used for the conventional design and alternative design, respectively; while for the 2-D model, about three thousand elements were used for both the conventional and alternative designs in the transient ANSYS heat transfer analysis. The results show that the alternative design, which includes the use of extended surfaces, improves the temperature distribution in the reactor by making it more uniform during the fast pyrolysis process. The implications of this are that the alternative design gives a greater yield of bio-oil per batch run, and steady-state conditions are reached within 40% of the time taken for the conventional design, which translates to a shorter process time and reduction in overall energy input, thereby making it a more efficient system.