bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy Harvesting With a Piezoelectric THUNDER
Authors: Wang Fengxia , Wu Wei , Lozowski Andy , Alizadehyazdi Vahid , Abedini Amin 
Published: March 2016

In this work the energy harvesting performance of a piezoelectric curved energy generator (THUNDER) is studied via experimental and analytical methods. The analytical model of the THUNDER is created based on the linear mechanical electrical constitutive law of the piezoelectric material, the linear elastic constitutive law of the substrate, and the Euler-Bernoulli beam theory. With these linear modal functions, the Rayleigh-Ritz approach was used to then obtain the reduced mechanical electrical coupled modulation equations.
With above analytical model two types of energy harvest circuit are proposed and compared: 1) directly charging mode at low level excitation, and 2) memory stored optimal duty cycle step-down converter mode at high level excitation. The value of the optimal duty cycle is determined based on the characteristics of the vibration signals of the ambient vibration source. To reduce the energy consumption of the microcontroller, the optimum duty cycle values are stored in the microprocessor instead of doing onsite computing during energy harvesting process. For the purpose of designing a low power cost mechanical switch to control the operation of both modes, the threshold voltage between these two operation modes is converted into threshold displacement.
Reliability-Based Component Design
Authors: Osakue Edward E. , Anetor Lucky , Odetunde Christopher 
Published: March 2016

This paper uses the lognormal probability function to modify deterministic design equations into probabilistic design, thereby transforming the traditional safety factor into a reliability factor. The reliability factor is related to the coefficients of variation (covs) of design parameters and a failure probability. An approximation of the reliability factor for initial sizing is defined as probabilistic design factor. The serviceability design model parameters are treated as random variables characterized by mean values and covs. The cov of the design model is obtained by using first order Taylor series expansion. Multiple serviceability criteria such as bending strength, lateral torsional stability, transverse deflection, and fillet weld strength are considered.
The results from this study compare favorably with previous ones and sometimes give solutions with lower weight. In the first example, the solution in the present approach deviates on the conservative side from the previous one by 2.6% for 99.9% reliability and 3.8% for 99.997% reliability. These results are practically the same, suggesting that the method presented is reasonable and accurate. In the second example, the beam in the new solution has 23.65% lower volume or weight and the weld bead volume is lower by 8.4%. This suggests possible substantial cost reductions. From the sizes of the beam and weld bead, it can be concluded that the “factor of reliability” approach of this study and the stochastic Monte Carlo simulation method used previously are in good agreement.
Due to the very good results from the examples considered, it seems reasonable to say that the “factor of reliability” method presented is a satisfactory model. The approach has the advantage of being much less computationally intensive and requires no specialized software or skills. These features can lead to cost savings in design projects. Design sizes from this method may be used to create solid models which can be optimized using FEM (Finite Element Method). In addition, and from an instructional perspective, the method could be used to introduce undergraduate engineering students to probabilistic design approaches.
Computational Simulation Study on the Viscous Drag of the Automotive Wet Clutch for Prediction and Control
Authors: Sung In-Ha , Ryu Jin Seok 
Published: March 2016

The reduction of drag torque is an important issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because viscous automatic transmission fluid flow narrow gap between friction plate and separate plate. The main purpose of this study is to observe the effects of the various parameters on the drag torque using finite element simulation.
In this study, the simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. Depth of groove on the friction plate plays an important role in controlling drag torque peak. An increase in the depth of groove causes a decrease in shear stress; thus, the drag torque also decreases according to Newton’s law of viscosity.
Also, an observation of the effect of the angle of groove pattern shape shows that the drag torque changes with groove pattern shape. Therefore, the optimum angle of the groove pattern should be determined carefully, considering both the clutch performance and drag reduction.
It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.
Mechatronics Implementation of Inverse Dynamics-Based Controller for an Off-Road UGV
Authors: Salama Mostafa , Vantsevich Vladimir V. 
Published: March 2016

This paper presents a project developed at the University of Alabama at Birmingham (UAB) aimed to design, implement, and test an off-road Unmanned Ground Vehicle (UGV) with individually controlled four drive wheels that operate in stochastic terrain conditions.
An all-wheel drive off-road UGV equipped with individual electric dc motors for each wheel offers tremendous potential to control the torque delivered to each individual wheel in order to maximize UGV slip efficiency by minimizing slip power losses. As previous studies showed, this can be achieved by maintaining all drive wheels slippages the same. Utilizing this approach, an analytical method to control angular velocities of all wheels was developed to provide the same slippages of the four wheels. This model-based method was implemented in an inverse dynamics-based control algorithm of the UGV to overcome stochastic terrain conditions and minimize wheel slip power losses and maintain a given velocity profile.
In this paper, mechanical and electrical components and control algorithm of the UGV are described in order to achieve the objective. Optical encoders built-in each dc motor are used to measure the actual angular velocity of each wheel. A fifth wheel rotary encoder sensor is attached to the chassis to measure the distance travel and estimate the longitudinal velocity of the UGV. In addition, the UGV is equipped with four electric current sensors to measure the current draw from each dc motor at various load conditions. Four motor drivers are used to control the dc motors using National Instruments single-board RIO controller. Moreover, power system diagrams and controller pinout connections are presented in detail and thus explain how all these components are integrated in a mechatronic system.
The inverse dynamics control algorithm is implemented in real-time to control each dc motors individually. The integrated mechatronics system is distinguished by its robustness to stochastic external disturbances as shown in the previous papers. It also shows a promising adaptability to disturbances in wheel load torques and changes in stochastic terrain properties. The proposed approach, modeling and hardware implementation opens up a new way to the optimization and control of both unmanned ground vehicle dynamics and vehicle energy efficiency by optimizing and controlling individual power distribution to the drive wheels.
Prediction of Rice Husk Particulate-Filled Polymer Composite Properties Using a Representative Volume Element (RVE) Model
Authors: Pochanard Pandhita , Saigal Anil 
Published: March 2016

In this study, a numerical representative volume element (RVE) model was used to predict the mechanical properties of a Rice Husk Particulate (RHP)-Epoxy composite for use as an alternative material in non-critical applications. Seven different analytical models Counto, Ishai-Cohen, Halpin-Tsai, Nielsen, Nicolais, Modified Nicolais and Pukanszky were used as comparison tools for the numerical model.
The mechanical properties estimated for 0%, 10% and 30% RHP-Epoxy composites using the numerical and analytical models are in general agreement with each other. Using the analytical models, it was calculated that an increase in volume percentage of RHP to 30% led to continual reduction in elastic Young’s modulus and ultimate tensile strength of the composite. The numerical RVE models also predicted a similar trend between filler volume percentage and material properties.
Overall, the results of this study suggest that RHP can be used to reduce the composite raw material costs by replacing the more expensive polymer content with agricultural waste products with limited compromise to the composite’s mechanical properties.
Evaluation of Rotational Speed Control System for Water Driven Spindle With Disturbance Observer
Authors: Hayashi Akio , Nakao Yohichi 
Published: March 2016

In ultra-precision machining to produce various precision products such as lenses or mirrors, the single-point diamond cutting is mainly carried out to achieve the high accuracy and high quality machined surfaces. Thus, the precise rotation accuracy is required to the spindle of the ultra-precision machining tool.
The water driven spindle had been developed for the precision machining tool spindle. This spindle is driven by the torque of water flow power. Then, the rotational speed can be controlled by supplied flow rate of water. However, the rotational spindle speed during cutting operation is changed due to the influence of the cutting forces during the machining processes. The change in the rotational speed causes the change in the cutting speed, as a result, it degrades the machined surface quality as well.
In order to reveal and reduce the influence of this phenomenon, the mathematical model of the rotational speed control system for water driven spindle was derived. This rotational speed control system consists of the water driven spindle and the flow control valve. From the simulation results using a derived transfer function of the rotational speed control system, it is clarified that the rotational speed changes depending on the external load torque.
Then, based on the mathematical model, the feedback rotational speed control system with a conventional P-I controller is designed. The effectiveness of the proposed feedback control system is verified by the turning tests. Furthermore, a disturbance observer to minimize the influence of cutting forces on the rotational speed was added to the feedback control system.
As a result, this paper shows the performance of the rotational speed control system.
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.
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.
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.
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.
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.