bluuebunny/crossref_metadata_2025 huggingface dataset:
Information Fusion in Polar Coordinates
Authors: Hui Dong , Chirikjian Gregory
Published: December 2016

Many sensing modalities used in robotics collect information in polar coordinates. For mobile robots and autonomous vehicles these modalities include radar, sonar, and laser range finders. In the context of medical robotics, ultrasound imaging and CT both collect information in polar coordinates. Moreover, every sensing modality has associated noise. Therefore when the position of a point in space is estimated in the reference frame of the sensor, that position is replaced by a probability density expressed in polar coordinates. If the sensor moves from one location to another and the same point is sensed, then the two associated probabilities can be “fused” together to obtain a better estimate than either one individually. Here we derive the equations for this fusion process in polar coordinates. The result involves the computation of integrals of three Bessel functions. We derive new recurrence relations for the efficient computation of these Bessel-functon integrals to aid in the information-fusion process.
Bio-Inspired Heuristic for Decoupling Network Configuration in Air Transportation System-of-Systems Design Optimization
Authors: Chamseddine Ibrahim M. , Kokkolaras Michael
Published: December 2016

Previous work in air transportation system-of-systems design optimization considered integrated aircraft sizing, fleet allocation and route network configuration. The associated nested multidisciplinary formulation posed a numerically challenging optimization problem; therefore, direct search methods with convergence properties were used to solve it. However, the complexity of the blackbox is such that it impedes greatly the solution of larger-scale problems, where the number of considered nodes in the route network is high. The research presented here adopts a rule-based route network design inspired by biological transfer principles. This bio-inspired approach decouples the network configuration problem from the optimization loop, leading to significant numerical simplifications. The usefulness of the bio-inspired approach is demonstrated by comparing its results to those obtained using the nested formulation for a 15-city network. We then consider introduction of new aircraft as well as a larger problem with 20 cities.
Improvement of a Forward Dynamic MPC Based Human Gait Model
Authors: Wu Shaoli , Voglewede Philip A.
Published: December 2016

This paper develops an improvement to an existing forward dynamic human gait model. A human gait model was developed previously to assist virtual testing prostheses and orthoses. The model consists of a plant model and a controller model. The central tenet to the model is the model predictive control (MPC) algorithm, which is a highly robust controller. In the previous model, however, there are several drawbacks. First, the anthropometric and mechanical parameters in the parts of the model are specific to one person. Second, the simulation result of ground reaction force (GRF) is not realistic. In this paper, the anthropometric parameters are calculated based on commonly used models that approximate an average person’s size. As for the mechanical parameters, the spring and damper coefficients in the human joints and ground reaction force (GRF) system are estimated by using the parameter estimation module in MATLAB based on the experimental subject data. The paper concludes with a simulation results between the new improved model and the previous developed model.
Experimental and Numerical Investigation of Vision Impairment in Long-Term Exposure to Microgravity
Authors: Shao Guangbin , Li Longqiu , Zhang Hongtao , Zhou Xinrong , Li Tingting , Dong Hualei
Published: December 2016

Recently researches have reported the ocular structural and functional changes observed in astronauts after long-duration space flight, which includes optic disk edema, globe flattening, choroidal folds, hyperopic shifts and reduction of near visual acuity. This syndrome, which is called the Visual Impairment/Intracranial Pressure (VIIP) Syndrome, is reported due to the alterations of translaminar pressure and some other factors (concentration of CO2, genotype, B-vitamin status, androgens, etc.) in microgravity or in space station. On account of the shortage of measurement and limit of sample size in space experiments, the study of VIIP Syndrome was difficult to make progress. In this research, numerical analysis combined with animal experiment were performed. In the animal experiment, hindlimb suspension (HLS) model was used to simulate the cephalic liquid shifts of Sprague-Dawley (SD) rats in microgravity, as well as fundus photography and optical coherence tomography (OCT) were executed to detect the ocular structural changes. For both the experimental group and the control group, the illumination, temperature and feeding were strictly controlled, well the watering was unrestricted, during the long-term hinlimb suspension. The ocular structural changes and the physiological index including weight and intraocular pressure (IOP) were evaluated. A numerical model of eye was established, then finite element analysis was performed to study the biomechanical response of ocular structure due to the changes of translaminar pressure. We observed that the changes of the ocular structure in rats after the long-term hindlimb suspension were consistent with the finite element simulation results. The findings in this research showed the significance of animal experiment and numerical analysis for the study of VIIP Syndrome.
Robot Arm Platform for Additive Manufacturing Using Multi-Plane Toolpaths
Authors: Bin Ishak Ismayuzri , Fisher Joseph , Larochelle Pierre
Published: December 2016

This article discusses the concept of using an industrial robot arm platform for additive manufacturing. The concept being explored is the integration of existing additive manufacturing process technologies with an industrial robot arm to create a 3D printer with a multi-plane layering capability. The objective is to develop multi-plane toolpath motions that will leverage the increased capability of the robot arm platform compared to conventional gantry-style 3D printers. This approach enables print layering in multiple planes whereas existing conventional 3D printers are restricted to a single toolpath plane (e.g. x-y plane). This integration combines the fused deposition modeling techniques using an extruder head that is typically used in 3D printing and a 6 degree of freedom robot arm. Here, a Motoman SV3X is used as the platform for the robot arm. A higher level controller is used to control the robot and the extruder. To communicate with the robot, MotoCom SDK libraries is used to develop the interfacing software between the higher level controller and the robot arm controller. The integration of these systems enabled multi-plane toolpath motions to be utilized to produce 3D printed parts. A test block has been 3D printed using this integrated system.
Robust Optimization With Parameter and Model Uncertainties Using Gaussian Processes
Authors: Zhang Yanjun , Li Mian , Zhang Jun , Li Guoshu
Published: December 2016

Uncertainty is unavoidable in engineering design, which may result in variations in the objective functions and/or constraints. The former may degrade the designed performance while the latter can even change the feasibility of the obtained optimal solutions. Taking uncertainty into consideration, robust optimization (RO) algorithms aim to find optimal solutions that are also insensitive to uncertainty. Uncertainty may include variation in parameters and/or design variables, inaccuracy in simulation models used in design problems, and other possible errors. Most existing RO algorithms only consider uncertainty in parameters, but overlook that in simulation models by assuming that the simulation model used can always provide identical outputs to those of the real physical systems. In this paper, we propose a new RO framework using Gaussian processes, considering not only parameter uncertainty but also uncertainty in simulation models. The consideration of model uncertainty in RO will significantly reduce the risk for the obtained robust optimal designs becoming infeasible even the parameter uncertainty has been considered. Two test examples with different degrees of complexity are utilized to demonstrate the applicability and effectiveness of our proposed algorithm.
Energy Harvesting From Torsional Vibrations Using a Nonlinear Oscillator
Authors: Gunn Ben , Alevras Panagiotis , Theodossiades Stephanos
Published: December 2016

Harvesting ambient energy in a variety of systems and applications is a relatively recent trend, often referred to as Energy Harvesting. This can be typically achieved by harvesting energy (that would otherwise get wasted) through a physical process aiming to convert energy amounts to useful electrical energy. The harvested energy can be thermal, solar, wind, wave or kinetic energy, with the last class mainly referring to harvesting energy from vibrating components or structures. More often these oscillations are error states from the systems’ ideal function and through harvesting this potentially wasted energy could be reclaimed and become useful. Regardless of the generally low power output of the devices designed to harvest energy from vibrations, their use remains an attractive concept, which is mostly attributed to the growing use of modern electronic devices that exploit the low power requirements of semi-conductors. Energy Harvesting applications are often met in situations where a network of essential electronic devices, such as sensors in Structural Health Monitoring or bio-implantable devices, becomes hardly accessible. Harvesting ambient vibrations to power up these devices offers the option to utilize wireless sensors rendering these systems autonomous. Typical cases of systems, where ambient vibrations are ubiquitous are met in automotive and aerospace applications. Besides their potentially adverse impact, the energy carried by vibrating parts could be harvested, such that wireless sensors are powered. In this paper, a concept for harvesting torsional vibrations is proposed, based on a concept that employs magnetic levitation to establish a nonlinear Energy Harvester. Experience has shown that linear harvesters require resonant response to operate, often leading to low performance of the device when the excitation frequency deviates from resonance conditions. This is why harvesters with essential nonlinearity are preferred, since they are able to demonstrate high response levels over wider frequency regions. Herein, the conducted study aims to demonstrate the functionality of this concept for torsional systems. A mathematical model of the coupled nonlinear electromechanical system is established, seeking preliminary estimates of the harvested power. The compelling attribute of this system lies in the dependency of its linear natural frequency on the excitation frequency, which is found to cause multiple response peaks in the corresponding frequency spectra. Moreover, the selection of the static equilibrium of the levitating magnet is found to greatly influence the system’s response.
Vertical Track Geometry Monitoring Using Inertial Sensors and Complementary Filters
Authors: Escalona José L.
Published: December 2016

This paper describes a computational procedure to obtain the vertical railroad track irregularities using the signals of an accelerometer and a gyroscope (IMU, inertial measurement unit) installed on a bogie of a railway vehicle. The procedure is designed to be implemented in a real-time on-board track geometry measurement system. The paper includes algorithms for constant and variable forward velocity of the laboratory vehicle. In each case, individual numerical methods to obtain the track vertical irregularities from the accelerometer signal and the gyroscope signal are presented. In addition a sensors fusion algorithm based on the concept of complementary filters is presented. In the sensors fusion algorithm the gyroscope’s based irregularity is used to measured low spatial frequencies while the accelerometer’s based irregularity is used to measure the high spatial frequencies. The numerical examples are developed on the basis of a synthesized irregular track profile that is numerically obtained from a known PSD (power spectral density) used in the railway industry. In the numerical tests the measured acceleration and angular velocity are corrupted with a bias error and a Gaussian white noise to account for the sensors errors. The numerical results compare the original irregularity profile with the measured profile in the space and frequency domains using the PSD and coherence function. Results include the algorithms for a constant and a variable forward velocity of the laboratory vehicle. A good agreement is found.
Multibody Modeling of Wire Rope Reeving Systems With the ALE-ANCF Method
Authors: Escalona José L.
Published: December 2016

This paper presents an efficient finite element method for the discretization of wire ropes in multibody models of reeving systems. The method is based on line-parametrized Absolute Nodal Coordinate Formulation (ANCF) finite elements defined in the framework of an Arbitrary Lagrangian–Eulerian (ALE) description. In the ALE description the finite element nodes have variable material coordinates thus allowing the finite element to change its position within the flexible body. This property is very convenient to model wire ropes rolled in sheaves that have variable-length free spans, as usually occurs in hoisting machines. Following a previous publication by the author about the general method to model reeving systems, this paper presents a new 3D ALE-ANCF finite element that is able to describe the axial-torsional coupling behaviour of wire ropes. The constitutive model of these new elements is able to reproduce accurately experimental axial-torsion tests of non-rotating wire ropes. The new finite element method is applied to the modelling of the reeving system of a large crane and to investigate the tendency of the load to rotate around a vertical axis.
Monitoring of Stamping Process Using Ultrasonic Waves
Authors: Mishra S. , Kankar P. K. , Ishihama M.
Published: December 2016

Stamping is a core manufacturing process in automobile industry. The measurement of the press force in stamping process has been the major focus of the research in this area. However, it has been established that the press force is itself an integral of the pressure distribution over the contact surfaces. Also full potential of servo-control stamping machines has not yet been achieved due to lack of appropriate sensing functions. In this study, an effort has been made to monitor the stamping process with the help of ultrasonic waves. The waves are employed to obtain the contact conditions between the work piece and the die. It has been shown that the waveforms are affected not only by the workpiece material and its thickness but also by the angle of inclination. Results show that the reflected waves, being more sensitive than transmitted waves, are influenced by the change in work piece related parameters.
A Study on the Relationship Between the Variation of Rolling Parameters and the Vibration Characteristics of Twenty-High Rolling Mill
Authors: Yimin Shao , Meng Rao , Qihui Yang , Yuan Yilin
Published: December 2016

As a common defect in the production of high-quality steel strip, chatter marks are easily found on the strip surface which may resulting from inappropriate variation of rolling parameters of a twenty-high rolling mill and the quality of the strip surface can be significantly affected. Therefore, it is critical to understand the underlying relationship between the vibration mechanisms of chatter marks and rolling parameters, furthermore, an appropriate adjustment strategy of rolling parameters is needed to improve the quality of the strip surface. To addressing this problem, a dynamic model of the twenty-high rolling mill, coupling the vertical and horizontal vibrations (because of the variation in friction tension forces), is proposed to investigate the vibration characteristics under different rolling conditions. Based on this dynamic model, effects of rolling force, rolling speed and fluctuations of tension on the vibration of the twenty-high rolling mill are studied. Finally, a rolling parameter adjustment strategy is discussed and presented based on the research results.
Kinematics Analysis and Control of a Three-Fingered Metamorphic Robot Hand
Authors: Calzati Matteo , Zhang Ketao , Parenti Castelli Vincenzo , Dai Jian S.
Published: December 2016

This paper presents the kinematics analysis of a three-fingered metamorphic hand (Metahand) and the LabView based control system of the robotic hand. In this study, the structure of the Metahand composed of an articulated palm and three fingers is introduced first. With the design parameters of the hybrid structure of the Metahand, analytical modeling of both forward and inverse kinematics is revealed, leading to reachable workspace and trajectory of all three fingertips. In particular, the analytical modeling of inverse kinematics is further verified by a numeric method. Following the theoretical investigation, a complete prototype with integrated servomotors and electric circuit for control system are produced. Further, a control system with LabView software is developed to realize the kinematics based control algorithm. A number of grasping tests are implemented to demonstrate the dexterity of the three-fingered Metahand.
Optimization for Anisotropy in Additively Manufactured Lattice Structures
Authors: Stanković Tino , Mueller Jochen , Shea Kristina
Published: December 2016

The build orientation of fabricated parts is one the most influential factors affecting material properties in many Additive Manufacturing (AM) processes. Applications such as the optimization of lattice structures for AM, are particularly affected as knowledge of the anisotropy model of the material is crucial. The investigation in this paper shows the influence of material anisotropy and build orientation on the optimized lattice structure designs. First, a material property characterization study for both compression and tension states of a single material is carried out for the example of inkjet 3D printing. Then, a generalized optimality criteria method is extended for the optimal sizing of single material and fixed topology lattice structures with respect to displacement, stress and Euler buckling constraints. The stress and Euler buckling constraints are formulated as side constraints that are handled in combination with fully-stressed design recursion. The results demonstrate the effect of anisotropy on the optimized designs caused by individual struts’ build orientation. This demonstrates the need to include anisotropic models in the optimization in order to produce solutions that can be fabricated and tested.
Design of a Reconfigurable Modular Chain for Folding 3D Lattice Structures
Authors: Xu Zhe , McCann Connor , Dollar Aaron M.
Published: December 2016

A wide range of engineering applications, ranging from civil to space structures, could benefit from the ability to construct material-efficient lattices that are easily reconfigurable. The challenge preventing modular robots from being applied at large scales is mainly the high level of complexity involved in duplicating a large number of highly integrated module units. We believe that reconfigurability can be more effectively achieved at larger scales by separating the structural design from the rest of the functional components. To this end, we propose a modular chain-like structure of links and connector nodes that can be used to fold a wide range of 2D or 3D structural lattices that can be easily disassembled and reconfigured when desired. The node geometry consists of a diamond-like shape that is one twelfth of a rhombic dodecahedron, with magnets embedded on the faces to allow a forceful and self-aligning connection with neighboring links. After describing the concept and design, we demonstrate a prototype consisting of 350 links and experimentally show that objects with different shapes can be successfully approximated by our proposed chain design.
A Method to Assess the Environmental Profile of In-House Machining Processes
Authors: Germani Michele , Mandolini Marco , Marconi Marco , Mengarelli Marco
Published: December 2016

A growing interest toward sustainability actions at every level is characterizing the industrial sector. Following the environmental trend, further developments and improvements regarding the sustainability assessment of manufacturing processes is needed. With a particular focus on machining processes, the optimization of working parameters can represent a valid step forward in sustainable manufacturing.

This paper aims to provide companies with the needed tool to independently asses the environmental performance of their customized machining operations. The purpose of the presented work is then to demonstrate that energy consumption calculated with empirical mathematical models available in literature, gives the greatest contribution to the environmental impact for a selection of machining processes by means of Life Cycle Assessment (LCA). Such objective lead to a clear need of specific models for the calculation of environmental impact of machining processes instead of available LCA datasets. Available mathematical models are adopted to provide a realistic energy consumption profile by using processing time variables. Such values are calculated through 3D models whose are used to recognize the needed manufacturing operations together with relative processing times.

In order to validate the previous assumption, a couple of machining processes have been selected as reference and analyzed by setting up a detailed Life Cycle Inventory (LCI) model. Results shown that among the different inputs and outputs, the energy consumption carries the highest impact. Over 90% of the total impact for the chosen impact categories (Global Warming Potential and Eco-Costs) is attributable to the energy consumption meaning that, for the sake of simplification, the environmental profile of such operations is overlapped by its energy consumption.
Rigidly Deployable Origami Tubes Based on Kite-Shape Pattern
Authors: Lv Weilin , Ma Jiayao , Chen Yan , You Zhong
Published: December 2016

Deployable structures, whose geometry can change to satisfy practical requirements, have attracted a lot of interests from researchers. And a lot of work has been done on the deployable tubes based on origami patterns. In this paper, three new kinds of deployable tubes based on the well-known kite-shape pattern are proposed. The first kind is generalized kite-shape tubes which are obtained by adding parts composed of parallelogram planes to basic kite-shape tubes. By joining a kite-shape tube or its generalization and a tube with a parallelogram cross section and removing the common sides, a second kind of tubes whose cross section can be a polygon with an odd number of sides is developed. Finally, by misaligning two half kite-shape tubes through a transition zone, a third kind of deployable tubes in which the boundary crease lines between neighboring layers can be on different planes are presented. All the three kinds of new deployable tubes are rigid and have one degree of freedom and are ideal for engineering design and applications.
Control Allocation for Multi-Axle Hub Motor Driven Land Vehicles With Active Steering
Authors: Wang Qian , Goyal Jatin , Ayalew Beshah , Singh Amandeep
Published: December 2016

Multi-axle land vehicles with independent drive actuation on multiple axles offer improved stability and traction on various road surfaces. This is possible by exploiting the redundancy of the drive system to generate additional yaw moment and to maximize the utilization of individual tire-road contacts without significant extra power consumption by the drive motors. This paper aims at improving the efficiency of torque allocation with the addition of active steering while enhancing the dynamic performance of the independent hub motor driven multi-axle vehicles. The control algorithm outlined here employs a two-level scheme. The higher level computes the desired global control efforts that are needed to track the reference yaw rate and slip angle state responses generated by a reference vehicle model, and the lower level executes optimal control allocation with a cost function that simultaneously takes into account 1) maximization of the tire utilization on all axles considering dominant tire nonlinearities, and 2) minimization of the actuation efforts of the active steering system and the distributed motor torques. The validity of the proposed algorithm is verified via comparison of the simulations of the control allocation scheme applied to a high fidelity multi-axle vehicle under several aggressive test maneuvers with different actuation configurations. The results suggest that the addition of active steering provides lower actuator power consumption and tire usage while ensuring enhanced lateral and longitudinal dynamic performance for the vehicle.
Disassembly Knowledge Classification and Potential Application: A Preliminary Analysis on a Washing Machine
Authors: Favi Claudio , Germani Michele , Mandolini Marco , Marconi Marco
Published: December 2016

Circular economy is largely recognized as the univocal economic model that guarantees a long-term sustainability, decoupling the economic growth and the finite resources consumption. As a prerequisite, it requires to realize product closed-loop lifecycles. However, the management of the EoL phase during the design process is a complex task, due to the fact that it is the most far away phase, in terms of time, from the moment of the product conception. For this reason, usually, manufacturers and EoL stakeholders do not actively collaborate in optimizing the product lifecycle performances.

This paper wants to overcome this lack proposing a method to formalize, collect and classify the EoL knowledge. The main outcome is a structured database containing positive and negative knowledge about best practices and disassembly problems faced during dismantling activities. The knowledge classification rules are based both on product characteristics (e.g. product families, target components, assembly methods, etc.) and on other more general aspects (e.g. motivations of the disassembly, handling difficulties, etc.). Through the sharing of this knowledge, the gap between design departments and EoL stakeholders can be reduced with the aim to improve EoL performances and the overall resource efficiency.

This work is focused on an out-of-service washing machine case study. The product has been manually disassembled by expert operators, observing and rating the significant problems. Their interpretation has allowed to create a set of specific design guidelines, organized according to the defined rules. The classified knowledge has been used by non-expert designers (undergraduate students) as a tool to guide the re-design activities. Different design solutions (e.g. homogenization of screws, reduction of component number, etc.) have been implemented to configure a new washing machine version, improved from the disassemblability point of view. The obtained results have confirmed the usefulness of the disassembly knowledge sharing in supporting Design for EoL activities and, furthermore, in non-skilled operators training.

In conclusion, this research work contributes to the state of the art linking stakeholders involved in the Beginning of Life (BoL) with stakeholders responsible of the EoL management. Furthermore, the proposed work leads to relevant improvements in product lifecycle performances. The proposed knowledge database represents the needed resource to effectively extend the producer responsibility and to close the current gap between manufacturers and dismantlers.
Exploring the Differences Between Users’ and Designers’ Perceptions of App Interface Design: A Case Study of Illumination Dimming and Control Application
Authors: Fu Yu , Jiang Hao , Zhang Dongliang , Zhang Xusheng , Gero John S.
Published: December 2016

This paper presents a case study of comparing users’ and designers’ perceptions towards user interface (UI) designs of six smart household illumination and control apps. It is intended to provide users’ insights into app UI design during an interaction design project. The study consisted of three phases. (1) Familiarization: prototypes of six apps were demonstrated to each participant; (2) Eliciting participants’ overall preferences by ranking; and (3) Eliciting participants’ idiosyncratic perceptions using the Repertory Grid Technique (RGT). A multidimensional scaling (MDS) analysis of preference ranking indicated that designers and users differed in overall perceptions towards to the six UIs. The specifics of inter-group perceptual differences were examined by comparing the RGT-elicited perceptions, as well as exploring the relationships between UI design features, designers’ and users’ subjective evaluation, and their overall preferences. This case study illustrates the application of the explorative use of the RGT method as an inspirational tool during the design process.
Reliability Based Design Optimization by Using a SLP Approach and Radial Basis Function Networks
Authors: Strömberg Niclas
Published: December 2016

In this paper reliability based design optimization by using radial basis function networks (RBFN) as surrogate models is presented. The RBFN are treated as regression models. By taking the center points equal to the sampling points an interpolation is obtained. The bias of the network is taken to be known a priori or posteriori. In the latter case, the well-known orthogonality constraint between the weights of the RBFN and the polynomial basis functions of the bias is adopted. The optimization is performed by using a first order reliability method (FORM)-based sequential linear programming (SLP) approach, where the Taylor expansions are generated in intermediate variables defined by the iso-probabilistic transformation. In addition, the reliability constraints are expanded at the most probable points which are found by using Newton’s method. The Newton algorithm is derived by proposing an in-exact Jacobian. In such manner, a FORM-based LP-formulation in the standard normal space of problems with non-Gaussian variables is suggested. The solution from the LP-problem is mapped back to the physical space and the suggested procedure continues in a sequence until convergence is reached. This is implemented for five different distributions: normal, lognormal, Gumbel, gamma and Weibull. It is also presented how the FORM-based SLP approach can be corrected by using second order reliability methods (SORM) and Monte Carlo simulations. In particular, the SORM approach of Hohenbichler is studied. The outlined methodology is both efficient and robust. This is demonstrated by solving established benchmarks as well as finite element problems.
Kinematic Analysis and Dimensional Synthesis of a Meso-Gripper
Authors: Bai Guochao , Kong Xianwen , Ritchie James Millar
Published: December 2016

In recent years, applications in industrial assemblies within a size range from 0.5mm to 100mm are increasing due to the large demands for digital multimedia products. Research on grippers or robotic hands within the mesoscopic scale of this range has not been well explored. This paper proposes a mesoscopic scale gripper (meso-gripper) which has two modes: passive adjusting mode and an angled precision gripping mode. The gripper adjusts its shape automatically according to the appropriate mode. This form of gripping and the associated mechanism are novel in their implementation and operation. The meso-gripper which has metamorphic characteristics is generated by integrating a remote center of motion (RCM) mechanism with a cross four-bar (CFB) linkage. The dimensional synthesis of the gripper is outlined for a specified task-based gripping followed by the analysis of the synthesizing mechanism. A differential mechanism is adopted to increase the flexibility of the meso-gripper. Prototype is fabricated and tested using 3D printing technology to verify the feasibility of the design.
Brass Instruments Design Using Physics-Based Sound Simulation Models and Surrogate-Assisted Derivative-Free Optimization
Authors: Tournemenne Robin , Petiot Jean-François , Talgorn Bastien , Kokkolaras Michael
Published: December 2016

This paper presents a method for design optimization of brass wind instruments. The shape of a trumpet’s bore is optimized to improve intonation using a physics-based sound simulation model. This physics-based model consists of an acoustic model of the resonator (input impedance), a mechanical model of the excitator (the lips of a virtual musician) and a model of the coupling between the excitator and the resonator. The harmonic balance technique allows the computation of sounds in a permanent regime, representative of the shape of the resonator according to control parameters of the virtual musician. An optimization problem is formulated, in which the objective function to be minimized is the overall quality of the intonation of the different notes played by the instrument (deviation from the equal-tempered scale). The design variables are the physical dimensions of the resonator. Given the computationally expensive function evaluation and the unavailability of gradients, a surrogate-assisted optimization framework is implemented using the mesh adaptive direct search algorithm (MADS). Surrogate models are used both to obtain promising candidates in the search step of MADS and to rank-order additional candidates generated by the poll step of MADS. The physics-based model is then used to determine the next design iterate. Two examples (with two and five design optimization variables, respectively) are presented to demonstrate the approach. Results show that significant improvement of intonation can be achieved at reasonable computational cost. The implementation of this method for computer-aided instrument design is discussed, considering different objective functions or constraints based on intonation but also on the timbre of the instrument.
In Vitro Development of Microvessels Using a Scaffold of Cylindrical PLGA
Authors: Tung Yen-Ting , Wang Gou-Jen
Published: December 2016

The microvascular network is a simple but critical system that is responsible for various important biological mechanisms in the bodies of all animals. The ability to generate a functional microvessel in vitro not only makes it possible to engineer vital tissue of considerable size but also serves as a platform for biomedical studies. In this study, we propose a simple method for fabricating customized cylinder micro-scaffolds for the in vitro development of microvascular networks. By integrating micro-electro-mechanical systems techniques with thermal reflow, we design and fabricate a micro-scale hemi-cylinder photoresist template. Then, a replica mold of polydimethylsiloxane, produced by casting, is used to generate microvascular network scaffolds of poly(lactide-co-glycolide) (PLGA). We selected the human umbilical vein endothelial cell (HUVEC) as our model endothelial cell, seeded it onto both sides of the PLGA scaffold, and cultured it using a traditional approach with no pumping system. Results from fluorescent staining demonstrate that the scaffold was covered with HUVECs and that the desired microvascular network and pattern was generated in vitro. The proposed method enables the culture of cells on a scaffold using a conventional culture approach and allows continuous monitoring of cell conditions. The cell-covered scaffold can serve as a framework for building large tissues, while the formed microvascular network, after degradation of the biodegradable PLGA cylinder, can be used as the core of a vascular chip for in vitro circulation studies.
Buckling and Nonlinear Analysis of Conoidal Shells
Authors: Soares Renata M. , Gonçalves Paulo B.
Published: December 2016

Slender shell structures described by ruled surfaces have been frequently used in civil engineering and, among these slender shells, conoidal shells are frequently favored as roofing units to cover large column-free areas due to their ease of construction, aesthetic value and structural efficiency. This work studies the nonlinear post-buckling behavior of a conoidal shell, using commercial finite element software ABAQUS®. The problem is geometrically nonlinear due to the shell strong geometric nonlinearity, especially in the case of shallow shells used in practical applications where quadratic nonlinearities play an important role. A detailed parametric analysis is conducted to show the influence of the shell geometry on the buckling loads and natural frequencies and, especially, on the nonlinear post-buckling behavior and stability.
A Large-Scale On-Road Energy Harvester From Highway Vibration
Authors: Wang Lirong , Park Jinwoo , Zhou Wanlu , Zuo Lei
Published: December 2016

This paper is to develop a large-scale energy harvester for traffic monitoring systems by using a unique half-wave mechanical motion rectify mechanism. When vehicles pass over the energy harvesting device, the electrical energy can be produced by the mechanical motion even after the vehicle passed by, which solves the difficulty in regeneration energy from impulse vibration. Design approach and dynamics modeling are presented to reveal the working mechanism of the energy conversion. In-field test with a sedan car is carried out and the regenerated power up about 24 Watts can be produced, which is much larger than the existing highway energy harvester in the published literature. This large-scale energy harvesting mechanism using the proposed MMR mechanism can help to develop harvesting device to build up self-power energy source for highway transportation monitoring system.
Examination of Hydraulic Suspension Bushing Design Features Using Frequency Domain Models
Authors: Chai Tan , Singh Rajendra
Published: December 2016

Hydraulic bushings or mounts are commonly used in automotive suspension and powertrain systems to improve vehicle vibration and structure-borne noise features while influencing ride and handling properties. This article aims to analytically examine certain features of hydraulic suspension bushing designs using frequency domain models. First, a linear time-invariant model of a hydraulic bushing with an inertia track is used to examine the dynamic stiffness (magnitude and loss angle) performance up to about 60 Hz with a given excitation amplitude. Second, the effect of inertia track parameters on dynamic stiffness is examined, and the key differences between fluid-filled suspension bushing and hydraulic engine mount are investigated by comparing the fluid chamber compliance ratios. Finally, the frequency dependence of inertia track parameters is analyzed with a quasi-linear model and the measurements of a laboratory prototype device.
Frequency Response of Primary Resonance of Double Wall Carbon Nanotube Under Electrostatic Actuation
Authors: Caruntu Dumitru I. , Juarez Ezequiel
Published: December 2016

This paper deals with electrostatically actuated Double Walled Carbon Nanotubes (DWCNT) cantilever resonators. DWCNTs are modeled as Euler-Bernoulli cantilever beams. Electrostatic, damping, and van der Waals, forces act on the outer tube of the DWCNT, while only van der Waals force acts on the inner tube. A soft AC voltage provides the electrostatic actuation. Van der Waals forces are present between the carbon nanotubes, coupling the deflections of the tubes. The nonlinearities in the system are given by the electrostatic and van der Waals forces. The DWCNT undergoes nonlinear parametric dynamics. The Method of Multiple Scales (MMS) is employed to investigate the system under soft excitations and/or weak nonlinearities. A modal coordinate transformation, in which only the linear term of the van der Waals force are considered, and the Harmonic Balance Method (HBM), are used to solve the zero-order problem. Then the frequency-amplitude response is found in the case of primary resonance. The expected nonlinear dynamic behavior is important to improve DWCNT resonator sensitivity in the application of mass sensing.
Design of Complex Engineering Systems Using Multiagent Coordination
Authors: Soria Nicolás F. , Colby Mitchell K. , Tumer Irem Y. , Hoyle Christopher , Tumer Kagan
Published: December 2016

In complex engineering systems, complexity may arise by design, or as a by-product of the system’s operation. In either case, the root cause of complexity is the same: the unpredictable manner in which interactions among components modify system behavior. Traditionally, two different approaches are used to handle such complexity: (i) a centralized design approach where the impacts of all potential system states and behaviors resulting from design decisions must be accurately modeled; and (ii) an approach based on externally legislating design decisions, which avoid such difficulties, but at the cost of expensive external mechanisms to determine trade-offs among competing design decisions. Our approach is a hybrid of the two approaches, providing a method in which decisions can be reconciled without the need for either detailed interaction models or external mechanisms. A key insight of this approach is that complex system design, undertaken with respect to a variety of design objectives, is fundamentally similar to the multiagent coordination problem, where component decisions and their interactions lead to global behavior. The design of a race car is used as the case study. The results of this paper demonstrate that a team of autonomous agents using a cooperative coevolutionary algorithm can effectively design a Formula racing vehicle.
Nonlinear Phenomena in the Single-Mode Dynamics in an AFM Cantilever Beam
Authors: Ruzziconi Laura , Lenci Stefano , Younis Mohammad I.
Published: December 2016

This study deals with the nonlinear dynamics arising in an atomic force microscope cantilever beam. After analyzing the static behavior, a single degree of freedom Galerkin reduced order model is introduced, which describes the overall scenario of the structure response in a neighborhood of the primary resonance. Extensive numerical simulations are performed when both the forcing amplitude and frequency are varied, ranging from low up to elevated excitations. The coexistence of competing attractors with different characteristics is analyzed. Both the non-resonant and the resonant behavior are observed, as well as ranges of inevitable escape. Versatility of behavior is highlighted, which may be attractive in applications. Special attention is devoted to the effects of the tip-sample separation distance, since this aspect is of fundamental importance to understand the operation of an AFM. We explore the metamorphoses of the multistability region when the tip-sample separation distance is varied. To have a complete description of the AFM response, comprehensive behavior charts are introduced to detect the theoretical boundaries of appearance and disappearance of the main attractors. Also, extensive numerical simulations investigate the AFM response when both the forcing amplitude and the tip-sample separation distance are considered as control parameters. The main features are analyzed in detail and the obtained results are interpreted in terms of oscillations of the cantilever-tip ensemble. However, we note that all the aforementioned results represent the limit when disturbances are absent, which never occurs in practice.

Here comes the importance of overcoming local investigations and exploring dynamics from a global perspective, by introducing dynamical integrity concepts. To extend the AFM results to the practical case where disturbances exist, we develop a dynamical integrity analysis. After performing a systematic basin of attraction analysis, integrity profiles and integrity charts are drawn. The curves of constant percentage of integrity measure are detected, highlighting that they provide valuable quantitative information about the changes in the structural safety. Robustness as well as vulnerability to disturbances is examined. The practical range of existence of each branch is observed to be smaller, and sometimes remarkably smaller than the theoretical one. The issue of the dynamical integrity analysis in the AFM design is addressed, showing that these curves may be used to establish safety factors in order to operate the AFM according to the desired outcome, depending on the expected disturbances. Physical meaning and practical relevance of the nonlinear phenomena in the AFM engineering design are discussed.
Computational Modeling and Field Evaluation of an Innovative Solar Updraft Aeration System for Aquaculture in the Developing World
Authors: Sur Shakya , Mahmoud Ahmed , Ebrahimi Khabbazi Ali , Pavlov Elan , Bilton Amy M.
Published: December 2016

Throughout the Asia Pacific region, fish farming is a vital and growing source of food security and economic activity. Since 1970, aquaculture has maintained an average annual growth rate of 8.7% in the region. Currently, almost 90% of global aquaculture production currently takes place in Asia Pacific and over 20 million people are employed in the sector. This growth has been associated with a large increase in family-run backyard aquaculture and integrated agriculture-aquaculture reservoirs in areas like rural Vietnam. However, yields in those rural ponds have typically been low. This is largely due to lack of aeration systems, which introduce oxygen into the pond water and allow for greater stocking densities, healthier fish, and greater yields. Aeration systems typically are not employed in these remote communities due to high capital costs, lack of access to reliable electricity, and prohibitive maintenance costs. To address this need, a low-cost solar-thermal aeration system for implementation in resource-constrained settings was devised. The system consists of a metallic solar collector and a heat transfer column, which induces convective circulation in the water by dissipating heat to the cooler, deeper layers of the pond. As a result of the circulation produced by the device, oxygen generated by phytoplankton at the top of the pond is distributed throughout the water column, preventing oxygen losses to the atmosphere due to surface supersaturation and increasing the overall pond oxygen content. This paper presents the system models developed to validate the concept, including a Computational Fluid Dynamics (CFD) model and a diel Dissolved Oxygen (DO) simulation model. These models, when used in conjunction, can estimate the increase in DO to be expected by the introduction of passive aeration device. These models were tailored to represent two target test ponds in Bac Ninh, Vietnam. To calibrate the models, instrumentation measured relevant parameters including DO and water temperatures at various depths, wind speed, ambient air temperature, and solar irradiance. A description of the mechanical design, construction and installation of two full-scale prototypes is then discussed, and field results for the first month post-implementation are analyzed. The model and experimental results indicate that the device can improve the DO content at deep levels of the ponds (i.e. oxygen-depleted regions) and has the potential to improve aquaculture productivity in resource-constrained settings.