bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Dependent Interval Distribution Parameters on Reliability Prediction
Authors: Cheng Yao , Du Xiaoping
Published: November 2017

Distributions of input variables of a limit-state function are required for reliability analysis. The distribution parameters are commonly estimated using samples. If some of the samples are in the form of intervals, the estimated distribution parameters will also be given in intervals. Traditional reliability methodologies assume that interval distribution parameters are independent, but as shown in this study, the parameters are actually dependent since they are estimated from the same set of samples. This study investigates the effect of the dependence of distribution parameters on the accuracy of reliability analysis results. The major approach is numerical simulation and optimization. This study indicates that the independent distribution parameter assumption makes the estimated reliability bounds wider than the true bounds due to interval samples. The reason is that the actual combination of the distribution parameters may not include the entire box-type domain assumed by the independent interval parameter assumption. The results of this study not only reveal the cause of the inaccuracy of the independent distribution parameter assumption, but also demonstrate a need of developing new reliability methods to accommodate dependent distribution parameters.
Linear and Nonlinear Aeroelastic Analysis of a High Aspect Ratio Wing
Authors: Bakhtiari-Nejad F. , Modarres A. H. , Dowell E. H. , Shahverdi H.
Published: November 2017

In this study, analysis and results of linear and nonlinear aeroelastic of a cantilever beam subjected to the airflow as a model of a high aspect ratio wing are presented. A third-order nonlinear beam model is used as structural model to take into account the effects of geometric structural nonlinearities. In order to model aerodynamic loads, Wagner state-space model has been used. Galerkin method is implemented to solve dynamic perturbation equations about a nonlinear static equilibrium state. The small perturbation flutter boundary is determined by these perturbation equations. The effect of geometric structural nonlinearity of the beam model on the flutter behavior is significant. As it is observed the system’s response to upper speed of flutter goes to limit cycle oscillations and also the oscillations lose periodicity and become chaotic.
Study of the Design Representation Methods for the Optimization of Multi-Layer Composite Structures
Authors: Xu Hongyi , Yang Junqi , Chuang Ching-Hung , Zhan Zhenfei
Published: November 2017

The purpose of multi-layer composite structure optimization is to find the optimal composite layout, such that superior structure performances and lightweight can be achieved. However, the existing optimization methods have a low efficiency when applied to the multi-component, multi-layer composite structure. Such low efficiency is caused by the high dimensionality and the inherent shortcomings of the existing design representation methods. In this work, two composite layout representation methods are compared to better understand their impacts on optimization. The root cause of the low efficiency is identified, and its influences are also quantified using three metrics. Furthermore, a new Representation-Switch Optimization (RSO) strategy is proposed. This strategy improves the search efficiency by switching the design representation methods during the optimization process. Three benchmark studies, two mathematical examples and one real engineering example, are conducted to demonstrate the impact of design representation methods on the optimization results, as well as the effectiveness of the proposed optimization strategy.
Period Motions and Limit Cycle in a Periodically Forced, Plunged Galloping Oscillator
Authors: Yu Bo , Luo Albert C. J.
Published: November 2017

In this paper, periodic motions of a periodically forced, plunged galloping oscillator are investigated. The analytical solutions of stable and unstable periodic motions are obtained by the generalized harmonic balance method. Stability and bifurcations of the periodic motions are discussed through the eigenvalue analysis. The saddle-node and Hopf bifurcations of periodic motions are presented through frequency-amplitude curves. The Hopf bifurcation generates the quasiperiodic motions. Numerical simulations of stable and unstable periodic motions are illustrated.
Adding Channel Security to a Fingerprint Verification Chain
Authors: Wenzl Matthias , Kluka Daniel
Published: November 2017

Authenticating persons using fingerprints is a widely accepted method in the field of access control, border control, prosecution and many others. Today, fingerprint modules with customizable firmware can be bought commercially off the shelf by hobbyists and small companies to be used in their applications and are usually locally separated from a controller implementing the feature extraction and comparison algorithms. As a matter of fact, the communication channel between the sensor and the controller module is susceptible to eavesdropping and man in the middle attacks. Nevertheless, adding communication channel security to such a system has a direct negative impact on the system’s response time, thus directly affecting user acceptance. The aim of this paper is to provide a comprehensive investigation on measures to counter run-time degredation when adding communication channel security on behalf of an existing fingerprint verification chain. We show that a combination of the elliptic curve Diffie-Hellman key exchange together with AES-256 and the use of parallelization using OpenMP on a controller node leads to an acceptable run time making key creation and exchange upon every fingerprint read request a suitable undertaking.
Optimization of a Compliant Endoscopic Radiofrequency Ablation Electrode
Authors: Hanks Bradley , Frecker Mary , Moyer Matthew
Published: November 2017

Radiofrequency ablation (RFA) is a common cancer treatment modality for patients who are ineligible for open surgery. There is a need for RFA electrodes that generate heating zones that closely match the geometry of typical tumors, especially for endoscopic ultrasound-guided (EUS) RFA. In this paper, the procedure for optimization of an RFA electrode is presented. First, a novel compliant electrode design is proposed. Next, a thermal ablation model is developed to predict the ablation zone surrounding an RFA electrode in biological tissue. Then, a multi-objective genetic algorithm is used to optimize two cases of the electrode geometry to match the region of destructed tissue to a spherical tumor of specified diameter. This optimization procedure is applied to an EUS-RFA ablation of pancreatic tissue. For a target 2.5cm spherical tumor, the optimal design parameters of the compliant electrode design were found. After simulating 40 generations of 50 designs per generation, both cases converged to optimal solutions. The objective functions were useful for simple electrode designs. For more complex electrode designs, the objective functions were unable to direct the design toward a 2.5cm sphere. The results of the optimization demonstrate how computational models combined with optimization can be used for systematic design of ablation electrodes. The optimization procedure may be applied to RFA of various tissue types for systematic design of electrodes that generate spherical ablation zones.
Network Analysis of Design Automation Literature
Authors: Guo Tinghao , Xu Jiarui , Sun Yue , Dong Yilin , Davis Neal E. , Allison James T.
Published: November 2017

In this paper we present a study of citation and co-authorship networks for articles from the ASME Design Automation Conference (DAC) during the years 2002–2015. We identify key authors, show that the co-authorship network exhibits the small world network property, and reveal other insights from network structure. Results from two topic modeling methods are presented. A frequency-based model was developed to explore DAC topic distribution and evolution. Citation analysis was also conducted for each core topic. A correlation matrix and association rule mining were used to discover topic relations and to gain insights for research gaps and recommendations. A recently developed unsupervised learning algorithm, propagation mergence (PM), was applied to the DAC citation network. Influential papers and major clusters were identified and visualizations are presented. The resulting insights may be beneficial to the engineering design research community, especially with respect to determining future directions and possible actions for improvement. The data set used here is limited. Expanding to include additional relevant conference proceedings and journal articles in the future would offer a more complete understanding of the engineering design research literature.
Restraint Systems in Tactical Vehicles: Uncertainty Study Involving Airbags, Seatbelts and Military Gear
Authors: Drignei Dorin , Mourelatos Zissimos P. , Zhamo Ervisa , Hu Jingwen , Chen Cong , Reed Matthew
Published: November 2017

Adding advanced safety features (e.g. airbags) to restraint systems in tactical vehicles could decrease the injury risk of their occupants. The impact of frontal crashes on the occupants has been assessed recently through experimental data and finite element models. However, the number of such experiments is relatively small due to high cost. In this paper, we conduct an uncertainty study to infer the advantage of including advanced safety features, if a larger number of experiments were possible. We introduce the concept of group injury risk distribution that allows us to quantify under uncertainty the injury risk associated with advanced safety features, while averaging out the effect of uncontrollable factors such as body size. Statistically, the group injury risk distribution is a mixture of individual injury risk distributions of design conditions in the group. We infer that advanced safety features reduce the injury risk by at least two thirds in frontal crashes.
Product Performance Evolution Prediction by Lotka-Volterra Equations
Authors: Zhang Guanglu , McAdams Daniel A. , Mohammadi Darani Milad , Shankar Venkatesh
Published: November 2017

During the development planning of a new product, designers rely on the prediction of the product performance to make business investments and frame design strategy. The S-curve model is commonly used for this purpose, but it has several drawbacks. A significant volume of product performance data doesn’t fit well with an S-curve. An S-curve model is also not capable of showing what factors shape the future performance of a product and how designers can change it. In this paper, Lotka-Volterra equations, which subsume both the logistic S-curve model and Moore’s Law, are used to describe the interaction between a product (system technology) and the components and elements (component technologies) that are combined to form the product. The equations are simplified by a relationship table and a maturation evaluation process as a two-step simplification. The historical performance data of the system and its components are fitted by the simplified Lotka-Volterra equations. The methods developed here allow designers to predict the performances of a product and its components quantitatively by the simplified Lotka-Volterra equations. The methods also shed light on the extent of performance impact from a specific module on a product, which is valuable for identifying the key features of a product and thus making outsourcing decisions. Smart phones are used as an example to demonstrate the two-step simplification. The data fitting method is validated by the time history performance data of airliners and turbofan aero-engines.
Towards the Development of an Elaboration Metric for Concept Sketches
Authors: Sevier Daniel C. , Jablokow Kathryn , McKilligan Seda , Daly Shanna R. , Baker Ian N. , Silk Eli M.
Published: November 2017

Assessment of elaboration in concept generation is critical, as it functions as a communication tool for the designer to iterate on solutions and to convey the generated ideas to other stakeholders involved in the early stages of the design process. Further, design educators may offer feedback to students about the elaborateness of their sketches, so they may fine-tune their techniques and optimize their sketch “literacy.” Although metrics exist for sketch complexity, product elaboration, and sketch quality, a gap remains in assessing elaboration. In this paper, we report on the development of an elaboration metric to evaluate concept representations as a means to facilitate greater understanding of designers’ ideas and their iterative improvement.
Design and Analysis of Reduced Degree of Freedom Modular Snake Robot
Authors: Racioppo Peter , Saab Wael , Ben-Tzvi Pinhas
Published: November 2017

This paper presents the design and analysis of an underactuated, cable driven mechanism for use in a modular robotic snake. The proposed mechanism is composed of a chain of rigid links that rotate on parallel revolute joints and are actuated by antagonistic cable pairs and a multi-radius pulley. This design aims to minimize the cross sectional area of cable actuated robotic snakes and eliminate undesirable nonlinearities in cable displacements. A distinctive feature of this underactuated mechanism is that it allows planar serpentine locomotion to be accomplished with only two modular units, improving the snake’s ability to conform to desired curvature profiles and minimizing the control complexity involved in snake locomotion. First, the detailed mechanism and cable routing scheme are presented, after which the kinematics and dynamics of the system are derived and a comparative analysis of cable routing schemes is performed, to assist with design synthesis and control. The moment of inertia of the mechanism is modeled, for future use in the implementation of three-dimensional modes of snake motion. Finally, a planar locomotion strategy for snake robots is devised, demonstrated in simulation, and compared with previous studies.
Review and Discussion on Model Reference Adaptive Control for Mechanical Mechanisms
Authors: Zhang Dan , Wei Bin
Published: November 2017

Traditional control systems are not able to properly balance out the load variation impact when robotic mechanisms carry and transport a variety of payloads. Adaptive control, particularly the model reference adaptive control (MRAC), is one of the ideal solutions that one can resort to address the mentioned problem. Adaptive control can be categorized into the following, model reference, self-tuning and gain-scheduled. Here, the authors mainly focus on the MRAC category. To the best of the authors’ knowledge, not so many recent papers can be found on MRAC for robotic manipulators because robotic manipulators are usually highly nonlinear and coupled systems, and sometimes it is not easy to design a stable MRAC in the robotic systems. This paper reviews and discusses the MRAC that is used in robotic manipulators and some issues of MRAC for robotic manipulators are presented as well. This review is able to give a general guideline for the future research in the MRAC of robotic manipulators.
Adaptive Surrogate Modeling for Multidisciplinary Reliability Analysis Under Time-Dependent Uncertainty
Authors: Hu Zhen , Mahadevan Sankaran
Published: November 2017

Multidisciplinary systems will remain in transient states when time-dependent interactions are present among the coupling variables. This brings significant challenges to time-dependent multidisciplinary system reliability analysis. This paper develops an adaptive surrogate modeling approach (ASMA) for multidisciplinary system reliability analysis under time-dependent uncertainty. The proposed framework consists of three modules, namely initialization, uncertainty propagation, and three-level global sensitivity analysis (GSA). The first two modules check the quality of the surrogate models and determine when and where we should refine the surrogate models. Approaches are then proposed to estimate the potential error of the failure probability estimate and determine the location of the new training point. In the third module (i.e. three-level GSA), a method is developed to decide which surrogate model to refine, through GSA at three different levels. These three modules are integrated together systematically and enable us to adaptively allocate the computational resources to refine different surrogate models in the system and thus achieve high accuracy and efficiency in time-dependent multidisciplinary system reliability analysis. Results of two numerical examples demonstrate the effectiveness of the proposed framework.
Preliminary Trial Results for the Redesigned STRIDER Platform With Sampling Capability From Different Depths
Authors: Joshi Rakesh , Bane Nathan , Derickson Justin , Williams Mark E. , Nagchaudhuri Abhijit
Published: November 2017

STRIDER: Semi-Autonomous Tracking Robot with Instrumentation for Data-Acquisition and Environmental Research, a semi-autonomous aquatic vessel, was envisioned for automated water sampling, data collection, and depth profiling to document water quality variables related to agricultural run-offs. Phase-I of the STRIDER project included the capability for STRIDER to collect water samples and water quality data on the surface of water bodies. This paper discusses the Phase-II efforts of the project, in which the previous design of STRIDER was adapted to extend its capabilities to include monitoring, depth profiling, and visualization of in-situ water quality data at various depths as well as collect water samples at each depth for bacterial analysis. At present, the vessel has been utilized for navigation to specified locations using remote control for collecting water quality data and water samples from the surface, as well as 2 feet and 4 feet below the surface at multiple UMES ponds. In a series of preliminary trial runs with the supervision of UMES faculty members and collaborators from the United States Department of Agriculture (USDA), STRIDER successfully collected 48 water samples for bacterial analysis at different locations and depths of ponds on the UMES campus. Design alternatives are being explored for more efficient water sampling capabilities.
Analysis of Cross Folding an Elastic Sheet
Authors: Hou Degao , Ma Jiayao , Chen Yan , You Zhong
Published: November 2017

Large antenna reflectors used in space have to be folded before launching. Silicone rubber is commonly used as antenna material due to its ability to maintain a shape without external supports upon deployment. However, localized vertices could appear during the folding process, which might lead to material yielding and unrecoverable deformation after deployment. In this paper, the cross folding process of a thin elastic sheet, a common folding method in packaging a reflective membrane, was studied numerically with the aim of eliminating material failure in the sheet. The deformation, stress distribution, and peak stress of the sheet and the dependency of those properties on geometrical parameters were systematically investigated. Based on these studies, two methods, i.e., central hole method and central slit method, were explored to reduce the peak stress caused by cross folding. The results showed that a central slit parallel to the first folding crease was the most effective in reducing the peak stress without causing significant damage to the antenna.
Variable Position and Force Control of a Pneumatically Actuated Knee Joint
Authors: Krause Jeremy , Bhounsule Pranav
Published: November 2017

Pneumatically powered prostheses have the ability to restore function and improve the quality of life by providing external power, thus decreasing human effort. However, such prostheses are expensive because they use high performance servo valves and complex control systems. To overcome this limitation, a pneumatic actuator is retrofitted with cheap solenoid valves and controlled by pulse width modulation for continuous control. High fidelity control is achieved by using a negative displacement configuration in which pressure is released on one side to create motion. The performance of the system is demonstrated using a series of position, force control experiments and ability to withstand external impulses. The pneumatic system is cheap, has high repeatability, and accuracy. The main limitation is that the speed of response is much slower than a positive displacement system but better design of the solenoid valve and use of predictive control has the potential to alleviate this issue.
Flat-Foldable Boxes of Thick Panels: Hinges and Supporters
Authors: Nara Chie , Hagiwara Ichiro , Yang Yang , Chen Xiaoshi
Published: November 2017

There are many commercial foldable products in our daily life, foldable umbrellas and airbags for cars are typical examples. These are made of materials which are thin and flexible; however, it is not easy to find such convenient foldable products made of thick and rigid materials, even for cardboard boxes. The main purpose of this paper is to propose a flat foldable box made of thick panels. By the Bellow theorem we know that any flat-foldable box cannot be designed as completely closed. This means the surface of a box should have hole(s) to move panels smoothly. We design boxes with thickness which can be continuously flat-foldable. We employ the Bennett linkage for the intersections of some edges to put suitable hinges. Moreover, using the advantage of thickness of the materials, we propose a new type of hinge which can be used for both rotating panels and keeping its standing position stable. We give an example of such box with thickness and show a simulation result.
Boundary Conditions and Craig-Bampton Substructuring Technique With Free-Free Modes
Authors: Orzechowski Grzegorz , Mikkola Aki M.
Published: November 2017

The floating frame of reference formulation allows for description of the kinematics of a deformable body using generalized coordinates that define the body local reference frame and deformations with respect to that frame. In practical applications, the formulation need to be used in conjunction with of a model order reduction approach. The paper investigates the usage of the model reduction through the Craig-Bampton method with the mean-axis reference frame conditions. Analysis involves static numerical examples of the beam structures, modeled using commercial packages with different boundary conditions and loads. It is shown that commonly employed orthonormalization technique dissolves the influence of the static correction modes in many assumed deformation modes of a deformable body. Consequently, a care should be taken in model validation when this popular approach for modeling flexible bodies is used.
Optimization of Wind Turbine Blades Considering the Specific Wind
Authors: Zheng Yuqiao , He Zhe , Cao Yongyong , Zhang Chengcheng
Published: November 2017

When designing a wind turbine blade, the goal is to attain the highest possible power output under specified atmospheric conditions.In this paper,the maximum likelihood estimation method was used to compute the hub height wind speed at 65m mathematical model based on the observation data of He xi Corridor wind at 10m height, taking He xi region of a certain type of 40m blade as an example, based on the Blade Element Momentum Theoty and tip loss, established the blade aerodynamic mathematic model, using the genetic algorithm on the blades. Each section of the chord, twist angle of wind energy utilization coefficient, girder cap layer thickness parameters were optimized, The aerodynamic performance and stress distribution are given out, the results showed that the optimized blade wind energy utilization coefficient is greatly improved and the quality of the blade is significantly reduced. It is suitable for wind the characteristics of the blade design condition performance supper than that of general blade.It provides a theoretical basis for the blade design.
A Rule-Based Decision Support System for Authoring Technical Instructions
Authors: Renu Rahul Sharan , Hanson Lynn
Published: November 2017

The objective of this research is to investigate the viability of a decision support system for technical instruction authors who write instructions in free text. The foundation for the decision support system relies on mapping computational linguistic metrics to guidelines for authoring technical instructions. For example, the guideline Limit each sentence to 25 words or fewer maps to the computational linguistic metrics Word Count. As another example, the guideline Begin each step with a command (an imperative verb) maps to the Location of first imperative verb metric. Testing the decision support system shows its effectiveness and suggests a need to expand the computational rule-base to include even more guidelines. Doing so can further enhance the usability of the decision support system in writing environments. Faculty and students in academia and employees in industry need such a system to improve the quality of written instructions, accelerate revisions, and enhance productivity. In summary, a rule-base for providing feedback to technical authors has been investigated and established. With this rule-base as a foundation, a decision support system has been developed and tested, and the source code has been made publically available.
Pseudo-Rigid-Body Models of Initially-Curved and Straight Beams for Designing Compliant Mechanisms
Authors: Kalpathy Venkiteswaran Venkatasubramanian , Su Hai-Jun
Published: November 2017

The use of pseudo-rigid-body models in the analysis and design of compliant mechanisms has opened up the possibility of using various types of flexible elements within the same framework. In this paper, an idea for combining initially curved and straight beams within compliant mechanisms is developed to create a set of equations that can be easily used to analyze various designs and topologies. A pseudo-rigid-body model with three revolute joints is derived to approximate the behavior of initially-curved compliant beams, to go with another model previously presented for straight beams. The general kinematic and static equations for a single-loop mechanism are shown. Finally, this setup is used for the early-stage design of a compliant constant force mechanism to illustrate its application and comparisons with Finite Element Analysis for validation.
Multi-Level Value-Driven Design Approaches for Product Family Design
Authors: Jung Sangjin , Simpson Timothy W. , Bloebaum Christina
Published: November 2017

Companies usually launch families of products into the market to provide value to different segments based on different customer needs; however, most of the research on Value-Driven Design (VDD) in the literature has focused on modeling value functions and optimizing the design of single products, not families of products. In order to increase profit and minimize total cost for product design and manufacturing, VDD should be applicable to product family design. In this work, we propose a multi-level VDD approach for product family design by extending multidisciplinary design optimization methods. The multi-level VDD is applied to a family of front-loading washing machines to validate the effectiveness of the proposed approach. With this example, we demonstrate that design problems that optimize traditional objective functions (e.g., cost, performance) at each level do not necessarily maximize value when compared to an appropriate VDD formulation. On the other hand, when the value function is set as an objective function throughout the organization (company, product family, and product level), we find that the VDD formulation provides the best value. Future work based on these promising findings is also discussed.
Application of the Magnetorheological Squeeze Film Dampers for Reducing Energy Losses in Supports of Rotors of Rotating Machines
Authors: Zapoměl Jaroslav , Ferfecki Petr
Published: November 2017

Unbalance of rotating parts is the main source of excitation of lateral oscillations of rotors, of increase of time varying forces transmitted to the rotor stationary part, and of energy losses generated in the support elements. The technological solution, which makes it possible to reduce these undesirable effects, consists in adding damping devices to the rotor supports. A simple dynamical analysis shows that to achieve their optimum performance their damping effect must be adaptable to the current operating speed. This is enabled by magnetorheological squeeze film dampers, the damping effect of which is controlled by the change of magnetic flux passing through the lubricating layer. The developed mathematical model of the magnetorheological squeeze film damper is based on assumptions of the classical theory of lubrication and on representing the magnetorheological oil by a bilinear material. The results of the carried out computational simulations show that the appropriate control of the damping force makes it possible to minimize the energy losses in a wide range of operating speeds. The development of a new mathematical model of the magnetorheological squeeze film damper, the extension of computational procedures, in which this model has been implemented, the confirmation that the magnetorheological dampers make it possible to reduce energy losses in the rotor supports, and learning more on influence of controllable dampers on behavior of rotor systems are the principal contributions of the presented paper. The carried out research highlights the possibility of reducing the energy losses by means of employing magnetorheological squeeze film dampers, which represents a new field of their prospective application.
Rigidly Foldable Quadrilateral Meshes From Angle Arrays
Authors: Lang Robert J. , Howell Larry
Published: November 2017

We present a design technique for generating rigidly foldable quadrilateral meshes, taking as input four arrays of direction angles and fold angles for horizontal and vertical folds. By starting with angles, rather than vertex coordinates, and enforcing the fold-angle-multiplier condition at each vertex, it is possible to achieve arbitrarily large and complex panel arrays that flex from unfolded to flatly folded with a single degree of freedom. Furthermore, the design technique is computationally simple, reducing for some cases to a simple linear programming problem. The resulting mechanisms have applications in architectural facades, furniture design, and more.
A Reconfigurable Compliant Four-Bar Mechanism With Multiple Operation Modes
Authors: Nayak Abhilash , Li Haiyang , Hao Guangbo , Caro Stéphane
Published: November 2017

Although reconfigurable rigid-body mechanisms have been extensively studied over two decades, their compliant counterparts have not received the similar attention yet. This paper aims to design a reconfigurable compliant four-bar mechanism with multiple operation modes. A planar equilateral four-bar mechanism is considered at its constraint singularity. The multiple operation modes of this linkage are kinematically exploited to design a reconfigurable compliant four-bar mechanism, which generates rotational or translational motions based on two actuated joints. Simulation is conducted to investigate the comprehensive kinematics of the reconfigurable compliant mechanism. A 3D printed prototype of the novel reconfigurable compliant mechanism at hand is presented.
Optimizing Periodic Response of Piezo-Driven, Nonlinear, Buckled Beams
Authors: Wilson James M. , Shukla Amit , Olson William
Published: November 2017

Many times, nonlinearities are seen as a burden in the design process as they can result in unpredictable and extremely sensitive response. As such, engineers make design changes to effectively minimize or completely eliminate the nonlinear behavior. In this paper, the periodic response of a buckled beams under piezo-excitation is considered. An optimization approach, as first demonstrated in [1], is utilized that achieves maximum amplitude, periodic, and stable responses of the beam systems. Case studies are presented that demonstrate the utility of this optimization approach to exploit the nonlinear dynamics to achieve desired responses.
Performance Assessment of Gear Condition Indicators in Detecting Progressive Gear Tooth Crack
Authors: Luo Yang , Baddour Natalie , Liang Ming
Published: November 2017

Gear condition indicators are one of the most important gear transmission fault detection and diagnosis techniques. Various kinds of condition indicators for different kinds of gear fault types (e.g. tooth crack, wear, eccentricity, etc.) have been proposed in the past several decades. However, their relative effectiveness, especially in light of some newly proposed indicators, on gear fault detection or diagnosis has not been fully evaluated. Performance assessment of gear fault condition indicators is not only helpful in designing new advanced indicators but also important for the development of a reliable Condition Based Maintenance (CBM) system. The objective of this paper is to verify and compare the relative performances of twenty-one selected gear condition indicators as applied to a progressive gear tooth crack under constant load and speed working conditions. The main goals are to identify which indicators are sensitive to the fault or have the capability to detect the initial tooth crack and therefore to recommend the most effective gear condition indicators. Dynamic simulations were used to generate the vibration signals which reflect the real underlying vibration behavior of the transmission system. Based on the simulated results, the performances of the selected indicators under noise-free as well as various signal to noise ratio conditions were evaluated and compared. Results indicate that many of the selected indicators are effective for the detection of the progressive tooth crack only under noise-free conditions, and the indicators that only consider time or frequency domain features, such as RMS, Kurtosis, energy ratio, sideband index, are generally less able to detect a tooth crack at an early stage compared to the methods based on reconstructed signals, such as the NA4, FM4, M6A, M8A.
Understanding the Importance of Post Occupancy Usage Trends During Concept-Stage Sustainable Building Design
Authors: Piacenza Joseph , Mayoral Salvador , Albarhami Bahaa , Lin Sean
Published: November 2017

As sustainable building mandates become more prevalent in new commercial and mixed use buildings, it is a challenge to create a broad, one-size-fits-all certification process. While designers can estimate energy usage with computational tools such as model based design, anticipating the post occupancy usage is more challenging. Understanding and predicting energy usage trends is especially complicated in unique mixed use building applications, such as university student housing buildings, where occupancy varies significantly as a function of enrollment, course scheduling, and student study habits. This research explores a computational modeling approach used to achieve LEED (Leadership in Energy and Environmental Design) Platinum certification for a student housing complex design. A case study is presented from the California State University, Fullerton (CSUF) campus, and examines the impact of post occupancy building usage trends, and diversity factor, defined as a building’s instantaneous energy usage normalized by the maximum allowable usage, on energy use estimates. The CSUF case model, which was originally created using EnergySoft’s EnergyPro 5 software, is examined. An annual predictive energy use comparison is performed in EnergyPro 5 using general building design mandates (i.e., ASHRAE 90.1, California Title 24), and CSUF case specific building usage details (e.g., student scheduling, diversity factor). In addition, the energy usage estimates of these two predictive models are compared to the actual usage data collected during the 2014 academic year. The results of this comparison show the benefits of considering post occupancy usage, and recommendations are presented for creating unique and application based computational models, early in the design process. This research has broad applications, and can extend to sustainable building design in other organizations, whose operational schedule falls outside of current prediction methods for sustainability mandates.
Driving Force Constraint Corner Smoothing Method for High-Speed Machine Tools
Authors: Li Bingran , Zhang Hui , Ye Peiqing
Published: November 2017

This paper presents a trajectory planning method for high-speed CNC machine tools. Generally, the kinematic parameters of a machine are limited to an agreed range in the trajectory planning process. However, a new single-step strategy trajectory planning method is proposed under a driving force limit condition. This method minimizes the acceleration and deceleration time when the speed changes. This kind of force limit method guarantees the tracking performance of a servo system. This paper proposes a method for time domain automatic feed rate adjustment to meet the requirements of the planning trajectory. In this method, two trajectory planning processes are provided. These processes are the two-axis straight line segment and the two-axis corner transfer segment planning process. An adapter for asymmetric contour error calculation method is then proposed, and the continuous G-code trajectory planning method is realized under this error calculation method. Finally, we compare our proposed algorithm with other algorithms through simulations and experiments, and then we prove the superiority of our proposed algorithm.
A Task-Driven Approach to Optimal Synthesis of Planar Four-Bar Linkages for Extended Burmester Problem
Authors: Deshpande Shrinath , Purwar Anurag
Published: November 2017

The classic Burmester problem is concerned with computing dimensions of planar four-bar linkages consisting of all revolute joints for five-pose problems. In the context of motion generation, each pose can be seen as a constraint that the coupler of a planar four-bar mechanism needs to interpolate or approximate through. We define extended Burmester problem as the one where all types of planar four-bars consisting of dyads of type RR, PR, RP, or PP (R: revolute, P: prismatic) and their dimensions need to be computed for n-geometric-constraints, where a geometric constraint can be an algebraically expressed constraint on the pose, or location of the fixed or moving pivots or something equivalent. In addition, we include both linear and non-linear and exact and approximate constraints. This extension also includes the problems where there is no solution to the classic Burmester problem, but designers would still like to design a four-bar that may come closest to capturing their intent. Such problems are representative of the problems that machine designers grapple with while designing linkage systems for a variety of constraints, which are not merely a set of poses.

Recently, we have derived a unified form of geometric constraints of all types of dyads (RR, RP, PR, and PP) in the framework of kinematic mapping and planar quaternions, which map to generalized manifolds (G-manifolds) in the image space of planar displacements. The given poses map to points in the image space. Thus, the problem of synthesis is reduced to minimizing the algebraic error of fitting between the image points and the G-manifolds. We have also created a simple, two-step algorithm using Singular Value Decomposition (SVD) for the least-squares fitting of the manifolds, which yields a candidate space of solution. By imposing two fundamental quadratic constraints on the candidate solutions, we are able to simultaneously determine both the type and dimensions of the planar four-bar linkages.

In this paper, we present 1) a unified approach for solving the extended Burmester problem by showing that all linear- and non-linear constraints can be handled in a unified way without resorting to special cases, 2) in the event of no or unsatisfactory solutions to the synthesis problem certain constraints can be relaxed, and 3) such constraints can be approximately satisfied by minimizing the algebraic fitting error using Lagrange Multiplier method. In doing so, we generalize our earlier formulation and present a new algorithm, which solves new problems including optimal approximate synthesis of Burmester problem with no exact solutions.
Selective Generalized Coordinates Partitioning Method for Multibody Systems With Non-Holonomic Constraints
Authors: Nada Ayman A. , Bashiri Abdullateef H.
Published: November 2017

The goal of this research work is to extend the method of generalized coordinates partitioning to include both holonomic and nonholonomic constraints. Furthermore, the paper proposes a method for selective coordinates for integration instead of identifying a set of independent coordinates at each integration step. The effectiveness of the proposed method is presented and compared with full-coordinates integration as well as generalized co-ordinates partitioning method. The proposed method can treat large-scale systems as one of the main advantages of multi-body systems.
Adaptive Fractional-Order Fault-Tolerant Tracking Control for UAV Based on High-Gain Observer
Authors: Yu Ziquan , Zhang Youmin , Qu Yaohong , Xing Zhewen
Published: November 2017

This paper is concerned with the fractional-order fault-tolerant tracking control design for unmanned aerial vehicle (UAV) in the presence of external disturbance and actuator fault. Based on the functional decomposition, the dynamics of UAV is divided into velocity subsystem and altitude subsystem. Altitude, flight path angle, pitch angle and pitch rate are involved in the altitude subsystem. By using an adaptive mechanism, the fractional derivative of uncertainty including external disturbance and actuator fault is estimated. Moreover, in order to eliminate the problem of explosion of complexity in back-stepping approach, the high-gain observer is utilized to estimate the derivatives of virtual control signal. Furthermore, by using a fractional-order sliding surface involved with pitch dynamics, an adaptive fractional-order fault-tolerant control scheme is proposed for UAV. It is proved that all signals of the closed-loop system are bounded and the tracking error can converge to a small region containing zero via the Lyapunov analysis. Simulation results show that the proposed controller could achieve good tracking performance in the presence of actuator fault and external disturbance.
Forward Kinematics of 3-RPS Parallel Mechanisms Using Conformal Geometric Algebra
Authors: Zhang Ying , Liao Qizheng , Wei Shimin , Li Duanling
Published: November 2017

In this paper, we propose a novel solution process for the forward kinematics of general 3-RPS parallel mechanisms based on conformal geometric algebra (CGA). First of all, the position of one of the three spherical joints is expressed in the rotational angle about the axis of one kinematic chain RPS. Secondly, the other two spherical joints can be determined by this angle via CGA operation. Thirdly, an explicit 16th-degree univariate polynomial equation is reduced from two geometric constraint equations. At last, one numerical example is employed to verify the solution procedure. The novelties of this paper lie in that (1) the modeling formulation and the elimination procedure have intrinsic geometric intuition due to the use of CGA and (2) the 16th-degree polynomial equation without extraneous roots is explicitly formulated and suitable for implementing the mathematics mechanization of this problem.
The Method of Modeling of a Novel 6-DOF Parallel Manipulator As a Generalized Virtual Road Vehicle for On-Board Equipment Test
Authors: Hu Yan , Gao Feng , Cao Rui , Zhao Xianchao
Published: November 2017

This paper presents a novel 6-DOF parallel manipulator for a new kind of vehicle motion simulation system, which is referred to as GVRV system. This system can realistically replicate the motion of any specified spot within the cabin of a real road vehicle in real time. Unlike traditional automobile testing platforms and vehicle motion simulators which are aimed at the vehicle, this system is aimed at the development of on-board equipment. The objective of this paper is to study how to do the modeling and motion planning work of this proposed manipulator to make it qualified as a generalized virtual road vehicle (GVRV) for on-board equipment test. First, the analytical characterization of the proposed 6-DOF parallel manipulator is presented. The forward and inverse kinematics problems of this manipulator are solved and its advantages such as high isotropy, well decoupling characteristic and no singular configuration within the demanded workspace are illustrated. Then, based on the full-size prototype of the manipulator, the whole GVRV system is built and described. By the study of the requirements for vehicle motion reproduction, the method of modeling is presented for this purpose. Finally, experiments are presented to demonstrate the validity of the model of the 6-DOF parallel manipulator for vehicle motion reproduction for use in on-board equipment test.
Product Family and Product Platform Benchmarking With Commonality and Variety Indices
Authors: Simpson Timothy W.
Published: November 2017

As companies are pressured to reduce costs and lead-times while increasing variety, the need to design products based on common platform “elements” is growing. Product family design has become an effective strategy to meet this challenge, but companies still struggle with assessing how “good” their product family is. Companies routinely benchmark their individual products, but they struggle with how to benchmark their platforms and product families against their competitors. A novel approach for product family benchmarking is introduced in this paper integrating commonality and variety indices to compare competing product families and their platform “elements”. An example involving two families of men’s razors is presented to illustrate the approach. Limitations of the approach and future work are also discussed.
Substitute Model for Crawler Track Units
Authors: Graneß Henry , Schlecht Berthold
Published: November 2017

Crawlers for mobilisation of working machines in rough terrain realize considerably high propel power. Furthermore, even heavy engineering structures cause only minor ground loading due to the wide contact patch of the crawler track plate. Typically, the driving speed of crawlers is low. Nevertheless, there is a significant speed droop during travel. The resulting vibrations and thus time variant loads eventuates in altered wear of the crawler’s components, as well as in damage of the travel gear drive and the superstructure of the vehicle. In this paper, a substitute model for crawler units is derived based on D’ALEMBERT’s principle. The model includes the most relevant phenomena of longitudinal crawler vehicle dynamics and hence permits to assess the time variant loads on the components thoroughly.
Concurrent Design of Active Control and Structural Modifications for Eigenstructure Assignment on a Cantilever Beam
Authors: Belotti Roberto , Richiedei Dario , Trevisani Alberto
Published: November 2017

This paper proposes the experimental application of a novel hybrid control technique to perform eigenstructure assignment in vibrating systems. The method takes advantage of the concurrent use of passive modifications of the elastic and inertial parameters, and of state-feedback active control. The system modifications are computed through the solution of a rank minimization problem to shape the space of the allowable eigenvectors that can be achieved through active control. The test consists of a cantilever beam, which is modified and controlled to feature a second vibrational mode whose vibrations are confined to the part of the beam near the free end. The beam is controlled through a piezoelectric actuator and a Kalman filter is adopted to estimate the state vector for state-feedback control. The method proposed is able to overcome the limitations of the use of either passive modifications or active control alone, by significantly enlarging the set of assignable eigenpairs in vibrating systems.