bluuebunny/crossref_metadata_2025 huggingface dataset:
Objectively measured sedentary time and diabetes mellitus in a general Japanese population: The Hisayama Study
Authors: Honda Takanori , Kishimoto Hiro , Mukai Naoko , Hata Jun , Yoshida Daigo , Hirakawa Yoichiro , Shibata Mao , Ohara Tomoyuki , Kumagai Shuzo , Ninomiya Toshiharu
Published: November 2018

Aims/Introduction

The present study aimed to examine cross‐sectional associations between objectively measured sedentary time and the prevalence of diabetes mellitus in a general Japanese population, and to elucidate possible mediating roles of diet, obesity and insulin resistance in this relationship.

Materials and Methods

A total of 1,758 community‐dwelling individuals aged 40–79 years wore an accelerometer for ≥7 days and underwent a comprehensive health examination in 2012. Diabetes mellitus was diagnosed by a 75‐g oral glucose tolerance test. The associations of sedentary time with the presence of diabetes mellitus and the levels of the homeostasis model assessment of insulin resistance were estimated by logistic and linear regression models.

Results

After adjustment for demographic and lifestyle factors including moderate‐to‐vigorous physical activity, participants who spent ≥10 h in sedentary time had a significantly higher odds ratio of the presence of diabetes than those who spent <6 h in sedentary time (odds ratio 1.84, 95% confidence interval 1.02–3.31). This significant association remained after adjusting for overall and central obesity (as measured by body mass index and waist circumference), but weakened after adjusting for dietary energy intake or homeostasis model assessment of insulin resistance. Sedentary time was positively associated with homeostasis model assessment of insulin resistance levels among non‐diabetic participants after adjusted for obesity or energy intake (P for trend <0.01).

Conclusions

Longer sedentary time was associated with a higher prevalence of diabetes mellitus in a general Japanese population. Insulin resistance appeared to be mainly involved in this association. These results highlight the importance of public health strategies targeting reductions in sedentary time for the primary prevention of diabetes mellitus.
Meta‐Analytic Research in Management: Contemporary Approaches, Unresolved Controversies, and Rising Standards
Authors: Combs James G. , Crook T. Russell , Rauch Andreas
Published: November 2018

Early meta‐analyses in management research sought primarily to resolve seemingly conflicting findings by estimating a relationship’s population‐level effect size. Since then, management researchers have adopted increasingly sophisticated approaches that permit new theorizing, testing and comparing sophisticated models, and identifying boundary conditions. We summarize three of these approaches – i.e., qualitative meta‐analysis (QMA), meta‐analytic structural equation modeling (MASEM), and meta‐analytic regression analysis (MARA) – along with the special issue papers that adopt each approach. We conclude by raising three unresolved controversies that we believe deserve more attention and by offering our thoughts about how to maximize a meta‐analytic study’s chances for publication and impact.
Effects of preoperative cisapride on postoperative aspiration pneumonia in dogs with laryngeal paralysis
Authors: Ogden J. , Ovbey D. , Saile K.
Published: November 2018

Objectives

Retrospective evaluation of a preoperative prokinetic protocol using a constant‐rate infusion of a serotonin 5‐HT4 receptor agonist, cisapride, and its association with frequency of postoperative aspiration pneumonia in dogs undergoing unilateral arytenoid lateralisation as compared to a historical population at the same institution.

Materials and Methods

Medical records of dogs undergoing unilateral arytenoid lateralisation for laryngeal paralysis were reviewed for historical findings, imaging findings, anaesthesia and surgery durations, perioperative medications and if surgery was performed as an emergency. Aspiration pneumonia events in the first 72 hours after surgery were recorded. The study group received a preoperative cisapride constant‐rate infusion; historical ‘controls’ did not receive the cisapride protocol.

Results

One of 50 dogs in the cisapride group and six of 52 dogs in the historical group developed aspiration pneumonia within the immediate postoperative period. The cisapride protocol was largely well tolerated. A markedly lower rate of aspiration pneumonia in patients administered butorphanol with acepromazine preoperatively and buprenorphine postoperatively was noted, but the overall low frequency of aspiration pneumonia and variation in case management protocols precluded definitive conclusions with respect to optimal perioperative drug choices.

Clinical Significance

Laryngeal paralysis is commonly treated by unilateral arytenoid lateralisation, and aspiration pneumonia is one of the most serious potential complications of this procedure. This study suggests that further investigation of a cisapride constant‐rate infusion to prevent this complication is warranted.
Retrospective analysis after endoscopic urethral injections of glutaraldehyde‐cross‐linked‐collagen or dextranomer/hyaluronic acid copolymer in bitches with urinary incontinence
Authors: Lüttmann K. , Merle R. , Nickel R.
Published: November 2018

Objectives

To evaluate the outcome of endoscopic injection of two different bulking agents, glutaraldehyde cross‐linked collagen and dextranomer/hyaluronic acid copolymer into the urethral submucosa in female dogs with urinary incontinence caused by urethral sphincter mechanism incompetence.

Materials and Methods

Retrospective review of records and follow‐up communication with owners of dogs that received an endoscopically guided urethral bulking procedure. In each dog, either cross‐linked collagen (2007 to 2011) or dextranomer/hyaluronic acid copolymer (2012 to 2015) was used. At least three injections were made in a circular arrangement in the midurethral region until the urethral lumen was closed.

Results

Complete questionnaires were available from 50 of 100 pet owners. The mean interval between the treatment and interview was 67 (range: 57 to 114) months in the cross‐linked collagen group and 19 (range: 2 to 48) months in the dextranomer/hyaluronic acid copolymer group. The mean duration of continence was 45∙8 months (range: 12 to 84 months) in the cross‐linked collagen group and 20∙5 months (range: 12 to 48 months) in the dextranomer/hyaluronic acid copolymer group. The success rate at 6 months or more after the procedure was 71% after the injection of cross‐linked collagen and 58% after injection of dextranomer/hyaluronic acid copolymer. One minor complication (transient haematuria) occurred in one dog. There were no major complications.

Clinical Significance

Urethral injection of dextranomer/hyaluronic acid copolymer in bitches with urethral sphincter mechanism incompetence is a useful alternative to cross‐linked collagen injection, which is no longer available in the European market. Dextranomer/hyaluronic acid copolymer injection is a minimally invasive alternative to surgical procedures and has a low complication rate.
Urinary incontinence in male dogs under primary veterinary care in England: prevalence and risk factors
Authors: Hall J. L. , Owen L. , Riddell A. , Church D. B. , Brodbelt D. C. , O'Neill D. G.
Published: November 2018

Objective

To estimate prevalence and identify demographic risk factors for urinary incontinence in male dogs.

Methods and Methods

The study population included all dogs within the VetCompass database from September 1, 2009 to July 7, 2013. Electronic patient records were searched for urinary incontinence cases; demographic and clinical information were extracted and analysed.

Results

Of 109,428 male dogs attending 119 clinics in England, there were an estimated 1027 dogs diagnosed with urinary incontinence, giving a prevalence of 0.94% (95% confidence interval: 0.88 to 1.00). Breeds with highest odds of incontinence in male dogs (compared with mixed breed dogs) included the bull mastiff (odds ratio: 17.21, 95% confidence interval: 6.65 to 44.56, case=5, non‐case=314, P<0.001), Irish red setter (odds ratio: 12.79, 95% confidence interval: 4.83 to 33.84, case=5, non‐case=142, P<0.001), fox terrier (odds ratio: 9.60, 95% confidence interval: 3.68 to 25.05, case=5, non‐case=176, P < 0.001), bulldog (odds ratio: 5.72, 95% confidence interval: 2.24 to 14.59, case=5, non‐case=929, P<0.001) and boxer (odds ratio: 3.65, 95% confidence interval: 1.84 to 7.25, case=10, non‐case=1470, P<0.001). Increased odds of urinary incontinence were associated with greater age (age 9 to 12 years, odds ratio: 10.46, 95% confidence interval: 6.59 to 16.62, n=12,348, P<0.001) and being insured (odds ratio: 1.96, 95% confidence interval: 1.53 to 2.51, n=26,202, P<0.001). There was no association with castration or bodyweight using multi‐variable analysis.

Clinical Significance

The overall prevalence of urinary incontinence in male dogs is approximately 1%, which may be higher than expected given the sparsity of reports describing this problem. In contrast to bitches, neutering and bodyweight were not associated with greater odds of urinary incontinence, which is important when giving neutering advice.
Myenteric ganglionitis and intestinal leiomyositis in a Jack Russell terrier
Authors: Kopke M. A. , Ruaux C. G. , Gal A.
Published: November 2018

A 9‐year, 6‐month old spayed female Jack Russell terrier presented with a 3‐week history of intermittent vomiting, diarrhoea and weight loss. Serum biochemistry demonstrated severe panhypoproteinaemia, mild hypocalcaemia and mild hypocholesterolaemia, consistent with protein‐losing enteropathy. Full‐thickness biopsies obtained from the stomach and different sections of small intestine demonstrated histological features of both myenteric ganglionitis and early intestinal leiomyositis. Complete resolution of clinical signs occurred within 1 week of implementing immunosuppressive therapy. At the time of writing, 9 months following diagnosis, the dog remains in remission.
Wine astringency reduces flavor intensity of Brussels sprouts
Authors: Carpenter Guy , Cleaver Leanne , Blakeley Matthew , Hasbullah Nurulezah , Houghton Jack , Gardner Alex
Published: November 2018

The bitterness of vegetables is a leading reason why they are avoided by children and some adults. Bitterness is perceived via TAS2R receptors located on the tongue. In contrast, astringency is a mouthfeel rather than a taste, and is perceived as a dry, puckering sensation. To date few reports have suggested any interactions between the two processes even though they often occur simultaneously in many real foods. In this study, we have used Brussels sprouts as an exemplar bitter vegetable and examined the influence of a number of different interventions on perceived intensity. Subjects rated the intensity of Brussels sprouts before and after three interventions: gravy, red wine, and water. Only red wine caused a significant (p < .0001) decrease in VAS scale, from 5.5 to 3.5 on a 10‐point labeled magnitude scale. The results suggest the astringency of the red wine affected the perception of bitter in the Brussels sprout. Some possible mechanisms are discussed.

Practical applications

This report reveals a possible insight into how bitterness is perceived in humans. By using astringency to affect salivary proteins, we suggest they may play a role in the detection of bitterness. This may be by helping to transport bitterness compounds to the taste bud receptors or a separate mechanism. Potentially this also opens up new ways to block bitterness.
Exchange rate regime and external adjustment: An empirical investigation for the US
Authors: Fuertes Alberto
Published: November 2018

This paper analyses the relationship between the US net external position and the exchange rate regime. I find a structural break in the US net external position at the end of the Bretton Woods system of fixed exchange rates that changed both the mean and variance of the series. On average, the US changed from a creditor to a debtor position and the variance of the external position increased during the floating period. This increase is to a large extent due to the valuation component of external adjustment that accounts for 54% of the variance of the US external position during the floating period but only 29% during the fixed exchange rate period. Further analysis shows that the exchange rate regime mainly affects the valuation channel of external adjustment. There is also evidence of another structural break in the US external position around the time of the introduction of the euro. Finally, I document asset pricing implications from the relationship between the exchange rate regime and the external adjustment process, as external imbalances predict the foreign exchange once the exchange rate regime is taken into account.
Does FDI increase productivity? The role of regulation in upstream industries
Authors: Papaioannou Sotiris K. , Dimelis Sophia P.
Published: November 2018

In view of substantial changes having taken place in the regulatory environment and in the light of the increasing role of inter industry linkages, we examine whether the total factor productivity (TFP) growth impact of foreign direct investment (FDI) is determined by regulation in upstream sectors. Econometric estimates illustrate that FDI exerts a positive impact on the growth of OECD industries which slows down as upstream regulation rises. To raise the reliability of our estimates, we use instruments for FDI and regulation that are as free as possible of endogenous association with TFP growth. Our instrumental variable estimates verify that the influence of FDI on TFP growth depends negatively on the level of upstream regulation. Non‐parametric estimates confirm that the highest impact of FDI takes place at the lowest levels of entry regulation and public ownership.
Development of In-Plane Truck Tire-Flooded Surface Interaction Models Using FEA-SPH Techniques
Authors: El-Sayegh Zeinab , El-Gindy Moustafa , Johansson Inge , Öijer Fredrik
Published: November 2018

The performance of a vehicle highly depends on the tire-terrain interaction characteristics. The terrain on which a vehicle operates can vary dramatically. This paper focuses on the evaluation of an in-plane truck tire performance running over the flooded surface. The truck tire is modeled using Finite Element Analysis (FEA) technique and validated against measured data. The water is modeled using Smoothed Particle Hydrodynamics (SPH), which includes water material properties. The tire-terrain interaction algorithm is defined using node-symmetric node-to-segment contact with edge treatment. The performance characteristics of the interaction include the rolling resistance coefficient, vertical, longitudinal tread and longitudinal tire stiffnesses. The simulations are repeated for several operating conditions such as inflation pressure, applied vertical load, and water depth. The flooded surface results are compared with previously published data. This work will be extended to include the prediction of the full in-plane and out-of-plane rigid ring tire model parameters while the tire is operating under various conditions.
Major-Axis Planning Method for Fabrication of High Aspect Ratio Structure Based on Two-Photon Photopolymerization Technology
Authors: Liao Chao-Yaug , Kao Chien-Min , Chen Po-Kai
Published: November 2018

The smallest forming unit in two-photon photopolymerization (TPP) micro-manufacturing technology is the voxel, the appearance of which resembles a spheroid. Traditional TPP micro-manufacturing is planned using the minor-axis dimension of a spheroid, which is smaller than its major-axis, thus, the spatial resolution can achieve submicron level. TPP can be used to manufacture microstructures with complex shapes. However, such fine spatial resolution inevitably lowers the overall manufacturing speed. For a microstructure with a height of hundred micrometers, the prolonged manufacturing time substantially increases the risk of manufacturing failure. Whereas typical methods use the minor-axis dimension for manufacturing planning, this study developed a novel major-axis planning (MAP) method that uses the longest dimension of the voxel. In this study, the MAP was realized in a 4-axis micro-manufacturing system (i.e., a rotation axis was added to the 3-axis motion stage). Specifically, a specially designed L-type glass substrate was first placed on the rotation axis and was rotated 90°, rendering the working plane parallel to laser beams. Subsequently, horizontal laser scanning was performed, during which the laser focus moved from the working plane horizontally, to polymerize a high-aspect-ratio structure. The commercial polymer OrmoComp was used with the MAP; only 10 s was required to fabricate a microstructure that had a height of 100 μm and an aspect ratio of 17. This study verified that TPP micro-manufacturing on a voxel’s major axis can fabricate microstructures. Moreover, the L-type glass substrate can be controlled programmably to rotate an L-type glass substrate for 4-axis TPP micro-manufacturing in the future.
Design and Numerical Investigation of Rudder With Leading-Edge Protuberances
Authors: Zhu Wencai , Gao Hongtao
Published: November 2018

The marine rudder with leading-edge protuberances is numerically investigated by SST k-ω turbulence model in present investigations. The newly designed rudder has a sinusoidal leading-edge profile along the spanwise direction. The numerical results show that the newly designed rudder helps to improve the lift coefficient of the rudder. The efficiency of the rudder is improved by adopting the leading-edge protuberances. The results are analyzed by means of streamlines and pressure coefficient. The leading-edge protuberances can delay or overcome the stall. The effect of leading-edge protuberances on the pressure coefficient of pressure surface is very small. However, the pressure coefficient of the suction surface is changed in the vicinity of leading-edge.
Study on the Normal Contact Stiffness of Rough Surface in Mixed Lubrication
Authors: Xiao Huifang , Sun Yunyun , Zhou Xiaojun , Chen Zaigang
Published: November 2018

In this paper, a general contact stiffness model is proposed to study the mixed lubricated contact between a rough surface and a rigid flat plate, which is the equivalent model for the contact between two rough surfaces and is the general case for engineering contact interfaces. The total interfacial contact stiffness is composed of the dry rough surface contact stiffness and the liquid lubricant contact stiffness. The GW model is used for surface topography description and the contact stiffness of a single asperity is derived from the Hertz contact theory. The whole dry rough contact stiffness is obtained by multiple the single asperity contact stiffness with the number of contact asperities, which is derived based on the statistical model. The liquid film stiffness is derived based on a spring model. The stiffness contributions from the asperity contact part and lubricant layer part are separated and analyzed.
Development of a Three-Dimensional Printer for Water-Soluble Biomaterial Printing
Authors: Su Chih-Yuan , Wang Gou-Jen
Published: November 2018

In this study, a three-dimensional bioscaffold printer was developed to fabricate biocompatible scaffolds from water-soluble materials for application in cell studies. A gelatin/sodium alginate solution was used to produce the scaffolds via a fused deposition modelling (FDM) printing method using the modified 3D printer. Modifications and improvements to the material feeding system, printing head, and printing platform were made, with additional optimization of the printing parameters, such as the feed rate, printing rate, and printing head size to investigate the precision and accuracy of two-dimensional and 3D bioscaffold printing. In addition to modifications of the feeding system from the original solid to the new liquid state material, a heating probe and coil were added to maintain the liquid phase. The printing nozzle was also altered to allow for the feed material and a cross-linking agent to mix prior to printing; enabling cross-linked scaffolds to be produced. Furthermore, the printing surface was integrated with a filter to allow for excess fluid to drain from the scaffold after printing and cross-linking. The results of this study revealed that the optimal printing parameters for producing a 2D 15.3 mm × 15.3 mm square was with a printing head-platform distance of 4 mm, material feed rate of 5 mL/min, printing rate of 35 mm/s and a printing head diameter of 0.4 mm. In addition, it was found that the printing speed and the printed image size and resolution are correlated, as such, the smallest dimensions able to be printed is 10.3 mm × 10.3 mm, with a line width of 1 mm. In regards to 3D scaffolds, the printed scaffolds had dimensions of 20 mm × 20.15 mm with a height of 7.5 mm; which were found to support the growth of mouse fibroblast cells.
Hybrid Control of Rotating Beams Using Pattern Search Based Optimization Technique
Authors: Vashisht Rajiv Kumar , Peng Qingjin
Published: November 2018

Rotating beams are quite common in rotating machinery e.g. fans of compressors in an airplane. This paper presents the experimental, hybrid, structural vibration control of flexible structures to enhance the vibration behavior of rotating beams. Smart materials have been used as sensors as well as actuators. Passive constrained layer damping (PCLD) treatment is combined with stressed layer damping technique to enhance the damping characteristics of the flexible beam. To further enhance the damping parameters, a closed form robust feedback controller is applied to reduce the broadband structural vibrations of the rotating beam. The feed forward controller is designed by combing with the feedback controller using a pattern search based optimization technique. The hybrid controller enhances the performance of the closed loop system. Experiments have been conducted to validate the effectiveness of the presented technique.
Efficient CNC Machining of Freeform Surfaces From Point Cloud
Authors: Dhanda Mandeep , Pande S. S.
Published: November 2018

This paper reports the development of an efficient tool path planning strategy for CNC machining of freeform surfaces directly from their representation in the form of point cloud. A grid based adaptive isoplanar tool path planning system has been designed and implemented for 3axis CNC machine using ball end mill. Inverse tool offset algorithm (IOM) is used to compute initial uniform CL (Cutter Location) grid points. From these CL points, surface slope and curvature are estimated and the forward and side step errors likely to be produced during machining are computed. The grid is subsequently refined through segmentation if the error values exceed the user defined tolerances. Adaptive grid refinement is continued iteratively till the error values converge below the prescribed tolerance limits. The grid (CL) points are sequenced to generate the final tool path. The software system developed takes the input part model as point cloud and generates post-processed CNC part program in the ISO format. The CNC part programs were extensively tested for various case studies on the commercial CNC simulator as well on the actual CNC machine. The results were compared with those from the commercial software for the same process conditions. Our system was found to generate more efficient tool paths in terms of enhanced productivity, part quality and reduced memory requirement.
Commonality and Product Family Design Integrated With Inventory Decisions
Authors: Takai Shun
Published: November 2018

Commonality or the use of the same components among products in a product family has been considered an effective approach to designing a product family; however, simultaneous optimization of commonality, product family design, and inventory decisions has not been comprehensively studied. In this paper, we propose a framework to simultaneously optimize commonality, product family design, and inventory decisions by incorporating inventory-related costs in the profit formula. Design of beverage containers is used as an illustrative example to demonstrate the proposed framework.
Type Synthesis of 3-RSR Equivalent 2R1T Parallel Mechanisms
Authors: Chen Ziming , Li Yanwen , Huang Zhen , Kong Xianwen
Published: November 2018

Parallel mechanisms (PMs) with two rotational and one translational (2R1T) degrees of freedom (DOFs) have attracted much attention these years. The 2R1T PMs can be divided into various categories due to different motion patterns, such as the UP equivalent PMs, the RPR equivalent PMs, the PU equivalent PMs and the 3-PPS equivalent PMs. In this paper, the 2R1T PMs have the same motion characteristics with the 3-RSR PM are studied and synthesized. This kind of PMs can be called as 3-RSR equivalent 2R1T PMs. The 3-RSR equivalent 2R1T PMs can realize both continuous rotations about fixed axes and continuous translation along fixed directions. The constraint and motion characteristics of the 3-RSR equivalent 2R1T PMs are analyzed. The design of the branches for the 3-RSR equivalent 2R1T PMs is dealt with using the screw theory and the subchains. A group of novel 3-RSR equivalent 2R1T PMs are obtained.
On Algorithms and Heuristics for Constrained Least-Squares Fitting of Circles and Spheres to Support Standards
Authors: Shakarji Craig M. , Srinivasan Vijay
Published: November 2018

Constrained least-squares fitting has gained considerable popularity among national and international standards committees as the default method for establishing datums on manufactured parts. This has resulted in the emergence of several interesting and urgent problems in computational coordinate metrology. Among them is the problem of fitting inscribing and circumscribing circles (in two-dimensions) and spheres (in three-dimensions) using constrained least-squares criterion to a set of points that are usually described as a ‘point-cloud.’ This paper builds on earlier theoretical work, and provides practical algorithms and heuristics to compute such circles and spheres. Representative codes that implement these algorithms and heuristics are also given to encourage industrial use and rapid adoption of the emerging standards.
Range Model of Electric Vehicles With Multi-Speed Transmissions
Authors: Liauw Yuhanes D. S. , Roozegar Mehdi , Zou Ting , Morozov Alexei , Angeles Jorge
Published: November 2018

Range-prediction models of electric vehicles (EVs) are essential for vehicle designers because range is still a major problem in EVs. Most range models are only available for EVs with fixed gearing. However, recent developments in EVs incorporate multi-speed transmissions (MSTs). Furthermore, transmissions are modeled only with a constant efficiency in most EV range-prediction simulation results available in the literature. For this reason, a simple and accurate range model for EVs with MSTs is proposed in this paper. In order to predict the range of EVs with MSTs accurately, the transmission efficiency is estimated by means of the transmission mathematical model. The efficiency results are verified with a comprehensive model that has been validated experimentally. A case study pertaining to the GM EV1 with a two-speed novel modular transmission is provided. Moreover, simulation results under constant efficiency are included to show the advantages of the proposed model in range-prediction. Our simulation results show that a more accurate range-prediction can be obtained by means of the proposed model.
Scaled Boundary Finite Element Method for Modeling of Impedance Based Structural Health Monitoring of 2D Structure
Authors: Sepehry Naserodin , Bakhtiari-Nejad Firooz , Zhu Weidong
Published: November 2018

Impedance based structural health monitoring using piezoelectric material is a high frequency method for detection of tiny damage. For modeling of structure in high frequency using conventional finite element method very fine mesh is needed. For large structure, this leads to very large mass and stiffness matrices. So very high RAM is needed to save these matrices and simulation time would be very low. In this paper a method combined finite element method and boundary element method named scaled boundary finite element method is studied for health and cracked 2D structure. Impedance of healthy and cracked structure is compared and verified by finite element method. A good agreement is presented and very low degree of freedom is obtained compared with finite element method.
Multi-Disciplinary Optimization of Space Experimental Device Using Radial Basis Function in ModelCenter
Authors: Wang Lyu , Yun Yuan , Zhang Bin , Zhang Tao
Published: November 2018

The multi-disciplinary optimization of actuators which is the key component of a Nested Flying Vehicle (NFV) is done through ModelCenter. The NFV is operated inside the space station for space science experiments. The conceptual design of the NFV has been done with expensive simulation models. However, the optimization result of the NFV using the genetic algorithm led to an unaccepted time consumption. In order to solve those problems, a self-programmed optimizer which is embedded the Radial Basis Function (RBF)-based optimization strategy is developed and integrated to ModelCenter and applied to the electromagnetic actuators of NFV. The optimizer helps to integrate more metamodel-based optimization algorithms and enhance the optimization ability of ModelCenter. By comparing with the optimization algorithms supplied by ModelCenter, the RBF-based optimization strategy proposed in this paper costs less time and results in an acceptable design. The conceptual design of the NFV, the methodology of RBF-based optimization strategy and the key components of optimizer are introduced in this paper.
Three Formulations of Sling Load Dynamics for UAV Motion Planning and Control
Authors: Cicchino Alexander , Sharf Inna
Published: November 2018

In this paper, the sling load dynamics of an aerial vehicle carrying a payload are investigated by employing three formulations of the governing equations. They are the hybrid formulation where the system exists in either a taut cable or slack cable configuration, with appropriate treatment of the transition between the two; the linear complementarity problem (LCP) formulation where the cable constraints are imposed as linear complementarity conditions and finally, the lumped parameter formulation where the cable is modelled with a series of spring-mass elements. The hybrid and LCP formulations neglect the elasticity of the cable while the lumped parameter model explicitly accounts for the elastic properties of the cable, albeit in a discrete way. The importance of the incorporation of elastic properties of the cable on the system is investigated for the variation in solution space of the payload. The three formulations are compared numerically, for information on the computational cost, motion of the payload, and tension profile, for several aerial maneuvers, including an aggressive obstacle avoidance with a window clearance flight.
Uncertainty Analysis for Time- and Space-Dependent Responses With Random Variables
Authors: Wei Xinpeng , Du Xiaoping
Published: November 2018

The performance of a product varies with respect to time and space if the associated limit-state function is a function of time and space. This study develops an uncertainty analysis method that quantifies the effect of random input variables on the performance (response) over time and space. The first order reliability method (FORM) is used to approximate the extreme value of the response with respect to space at discretized instants of time. Then the response becomes a Gaussian stochastic process that is fully defined by the mean, variance, and autocorrelation functions obtained from FORM, where a sequential single loop procedure is performed for spatial and random variables. The method is successfully applied to the reliability analysis of a crank-slider mechanism, which operates in a specified period of time and space.
A Partial Safety Factor Method for System Reliability Prediction With Outsourced Components
Authors: Hu Zhengwei , Du Xiaoping
Published: November 2018

System reliability is usually predicted with the assumption that all component states are independent. This assumption is particularly useful for systems with outsourced components. The assumption, however, may produce large errors in the system reliability prediction since many component states are strongly dependent. The purpose of this study is to develop an accurate system reliability method that can produce complete joint probability density function (PDF) of all the component states, thereby leading to accurate system reliability predictions. The proposed method works for systems whose failures are caused by excessive loading. In addition to the component reliability, system designers also ask for partial safety factors for shared loadings from component suppliers. The information is then sufficient for building a system-level joint PDF. Algorithms are designed for a component supplier to generate partial safety factors, which enables accurate system reliability predictions without requiring proprietary information from component suppliers.
Effect of Geometric Error of Inner Raceway on Motion of Cylindrical Roller Bearings Under Radial Load
Authors: Jishun Li , Yongjian Yu , Yujun Xue , Yuankun Zhou , Zhiqiang Guan
Published: November 2018

The motion error of bearing depends highly on the geometric profile of bearing components. Therefore, it is crucial to establish a correlation between the geometric error of bearing components and the motion error of an assembled bearing, which is required for designing and manufacturing bearings with high accuracy of motion. In this paper, authors derived a geometric compatibility equation for cylindrical roller bearing considering the geometric error of bearing inner raceway. Based on the load balance and the geometric compatibility derived, a mathematical model of motion accuracy is established, and the model is also validated. The effect of geometric error such as the amplitude of roundness error and dimension error of bearing inner raceway, and radial clearance on the bearing motion error is investigated. Results show that the motion error of the bearing increases with the amplitude of the roundness error of inner raceway, and reduces with the increase of radial load. The results indicated that the motion accuracy can be improved by controlling the distribution of machining tolerance of bearing components.
Simulation of Machining Operations Using the Virtual Machine Tool Concept
Authors: Cugnon Frédéric , Berglind Luke , Plakhotnik Denys , Armendia Mikel
Published: November 2018

This paper focusses on the dynamic modeling of the machine tool including its Computer Numeric Control (CNC), and its interaction with the machining process. To properly simulate modern machine tools in machining condition, which show close interaction between the dynamic behavior of the mechanical structure, drives, and the CNC, we use an integrated methodology that combines control and MBS capabilities in a nonlinear FEA solver called SAMCEF Mecano. To fully capture the dynamic behavior of the machine, force interactions between the cutting tool and the workpiece are also considered. A strong coupling between the mechatronic model of the machine tool and a machining simulation tool is implemented. A specialized cutting force element has been developed. It considers the dynamics of the tool tip combined with the tool workpiece engagement to generate cutting forces. The use of such digital twin model is demonstrated considering some industrial machining operations.
RobEcolo: Optimal Design of a Wooden Five-Bar Mechanism
Authors: Kaci Lila , Briot Sébastien , Boudaud Clément , Martinet Philippe
Published: November 2018

Eco-design of robots has almost never be en explored in the past. This work investigates the potential of using bio-sourced materials, which have almost no environmental impact, instead of metals for robot design. Also, wood is one of the best candidates because of its interesting mechanical properties. However, wood performance / dimensions vary with the atmospheric conditions / external solicitations. Thus, it is challenging to design a stiff and accurate wooden industrial robot.

Therefore, the objective of this paper is to describe a new design methodology leading to the design a wooden five-bar mechanism reliable in terms of accuracy and stiffness. The design optimization problem is solved in cascade. The first optimization process proposes to use a control-based design approach in order to compute the optimal primary geometric parameters of the robot (lengths of the links). This approach takes into account the sensor-based controller performance during the design phase. The second optimization process deals with the issue of the variability of the wood mechanical performance. It is based on a reliable topology optimization approach and allows for finding the shape of the robot links for which the impact of this variability in terms of deformation is minimized. Theoretical developments are described, solved and the obtained results allowed the prototyping of an industrial wooden five-bar mechanism.
Origami-Based Design of Conceal-and-Reveal Systems
Authors: DeFigueiredo Bryce P. , Tolman Kyler A. , Crampton Erica , Pehrson Nathan A. , Magleby Spencer P. , Howell Larry L.
Published: November 2018

This work introduces a type of motion termed “conceal-and-reveal” which is characterized by a state that protects a payload, a state that exposes the payload, and continuous motion between these two states. As techniques for thick, rigid origami-based engineering design are being developed, origami is becoming increasingly more attractive as inspiration for complex systems. This paper proposes a process for designing origami-based conceal-and-reveal systems, which can be generalized to design other thick, rigid origami-based systems. The process is demonstrated through the development of three conceal-and-reveal systems that present a luxury product to the consumer. The three designs also confirm that multiple origami crease patterns represent viable approaches to achieving conceal-and-reveal motion.
L-System-Generated Topology Optimization of Compliant Mechanisms Using Graph-Based Interpretation
Authors: Bielefeldt Brent R. , Hartl Darren J. , Akleman Ergun
Published: November 2018

Traditional topology optimization techniques, such as density-based and level set methods, have proven successful in identifying potential design configurations but suffer from rapidly increasing design space dimensionality and convergence to local minima. A heuristic alternative to these approaches couples a genetic algorithm with a Lindenmayer System (L-System), which encodes design variables and governs the development of the structure when coupled with some sort of interpreter. This work discusses the development of a graph-based interpretation scheme referred to as Spatial Interpretation for the Development of Reconfigurable Structures (SPIDRS). This framework allows for the effective exploration of the design space using a limited number of design variables. The theory and implementation of this method are detailed, and a compliant mechanism case study is presented to demonstrate the ability of SPIDRS to generate structures capable of achieving multiple design goals.
Strategic-Level Robust Optimal Design Method of Product Family and Supply Chain Network
Authors: Toi Masato , Sawai Kana , Nomaguchi Yutaka , Fujita Kikuo
Published: November 2018

Manufacturing firms must meet a wide variety of customer needs flexibly and effectively. Thus, simultaneous design of the product family and the supply chain network is required. This design problem must be assessed in terms of strategic-level decision making under uncertainties without any detailed and fixed information on the design conditions. We therefore propose a mathematical framework by considering the optimal profitability and robustness against destructive incidences. This paper discusses the design problem structure and formulates it as a mixed-integer programming problem. A computational method is configured for solving the optimization problem, in which only profitability is considered as the objective. A procedure to assess the robustness of the profitability-oriented optimal solution is proposed by evaluating the Pareto optimality among the nominal optimal solution and its competitive solutions. A case study of a coffee maker product family design problem is demonstrated to verify the proposed framework.
A Novel Adaptive Topology Optimization Method Considering Unnecessary Element Removal and Progressive Mesh Refinement
Authors: Bai Yingchun , Kim Il Yong , Lin Cheng
Published: November 2018

This paper proposes an adaptive topology optimization (TO) approach considering unnecessary element removal and progressive element refinement. A two-stage density filtering for element removal is developed to relax the design space for next iteration, and therefore make a trade-off between solution quality and optimization efficiency. An isolated element detection and deletion is also conducted between element removal and element refinement operation to guarantee the numerical stability. Two 2D numerical examples and one 3D design problems are investigated to demonstrate the effectiveness of the proposed method. Based on the numerical tests, the applicability range of the proposed method and recommended range of element density threshold are provided as well.
Similarity of Tessellated Solid Models for Engineering Applications
Authors: Renu Rahul S. , Sousa Christopher
Published: November 2018

The objective of this research is to investigate the performance of a solid model similarity assessment method. This method is used to assess the similarity of tessellated solid models, where the tessellated geometry is in the form of triangles — specifically, the method compares STL files. A histogram of (triangle) tessellation areas is generated for each solid model being compared. The difference in the histograms of two solid models indicates their dissimilarity. The performance of the solid model similarity assessment method is evaluated by varying tessellation resolutions, and by varying histogram bin sizes. The solid model similarity assessment method is also compared to methods from literature. The comprehensive testing was performed using 867 solid models from the Engineering Shape Benchmark. It is found that the method was robust in its sensitivity to histogram bin sizes, and robust in its sensitivity to tessellation resolution. It is found that for small retrieval sizes, precision is relatively high. It is also found that this method outperformed methods from literature when comparing models that are rectangular, flat, thin, and/or cubic. Additionally, shortcomings of this method and related future work is identified.
Efficient Identification of Promising Regions in High-Dimensional Design Spaces With Multilevel Materials Design Applications
Authors: Morris Clinton , Seepersad Carolyn C.
Published: November 2018

Design space exploration can reveal the underlying structure of design problems of interest. In a set-based approach, for example, exploration can identify sets of designs or regions of the design space that meet specific performance requirements. For some problems, promising designs may cluster in multiple regions of the design space, and the boundaries of those clusters may be irregularly shaped and difficult to predict. Visualizing the promising regions can clarify the design space structure, but design spaces are typically high-dimensional, making it difficult to visualize the space in three dimensions. Techniques have been introduced to map high-dimensional design spaces to low-dimensional, visualizable spaces. Before the promising regions can be visualized, however, the first task is to identify how many clusters of promising designs exist in the high-dimensional design space. Unsupervised machine learning methods, such as spectral clustering, have been utilized for this task. Spectral clustering is generally accurate but becomes computationally intractable with large sets of candidate designs. Therefore, in this paper a technique for accurately identifying clusters of promising designs is introduced that remains viable with large sets of designs. The technique is based on spectral clustering but reduces its computational impact by leveraging the Nyström Method in the formulation of self-tuning spectral clustering. After validating the method on a simplified example, it is applied to identify clusters of high performance designs for a high-dimensional negative stiffness metamaterials design problem.
Design Space Exploration in Sparse, Mixed Continuous/Discrete Spaces via Synthetically Enhanced Classification
Authors: Wiest Tyler , Seepersad Carolyn Conner , Haberman Michael
Published: November 2018

Exploration of a design space is the first step in identifying sets of high-performing solutions to complex engineering problems. For this purpose, Bayesian network classifiers (BNCs) have been shown to be effective for mapping regions of interest in the design space, even when those regions of interest exhibit complex topologies. However, identifying sets of desirable solutions can be difficult with a BNC when attempting to map a space where high-performance designs are spread sparsely among a disproportionately large number of low-performance designs, resulting in an imbalanced classifier. In this paper, a method is presented that utilizes probabilities of class membership for known training points, combined with interpolation between those points, to generate synthetic high-performance points in a design space. By adding synthetic design points into the BNC training set, a designer can rebalance an imbalanced classifier and improve classification accuracy throughout the space. For demonstration, this approach is applied to an acoustics metamaterial design problem with a sparse design space characterized by a combination of discrete and continuous design variables.
Synthesis of Gear-Linkage Mechanisms by Topology Optimization
Authors: Yim Neung Hwan , Kang Seok Won , Kim Yoon Young
Published: November 2018

This work is concerned with a new mechanism synthesis method for the simultaneous determination of the type, number and dimension of mechanisms by topology optimization. Earlier topology optimization methods can synthesize linkage mechanisms that consist only of links and joints. The proposed synthesis method is a gradient-based topology optimization method useful for the synthesis of planar mechanisms consisting of linkages and gears. To formulate the topology optimization based method, we propose two superposed design spaces as a ground structure: the linkage and gear design spaces. The gear design space is discretized by newly proposed gear blocks while the linkage design space by rigid blocks. The zero-length springs with variable stiffness are used to control the connectivity of blocks, which in turns determines the configuration of the synthesized mechanism. After the proposed topology-optimization-based synthesis formulation is presented, its effectiveness and validity are checked with various synthesis examples.