bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental osmolality influences sperm motility activation in an anuran amphibian
Authors: Byrne P. G. , Dunne C. , Munn A. J. , Silla A. J.
Published: January 2015

Evolutionary theory predicts that selection will favour sperm traits that maximize fertilization success in local fertilization environments. In externally fertilizing species, osmolality of the fertilization medium is known to play a critical role in activating sperm motility, but there remains limited evidence for adaptive responses to local osmotic environments. In this study, we used a split‐sample experimental design and computer‐assisted sperm analysis to (i) determine the optimal medium osmolality for sperm activation (% sperm motility and sperm velocity) in male common eastern froglets (Crinia signifera), (ii) test for among‐population variation in percentage sperm motility and sperm velocity at various activation‐medium osmolalities and (iii) test for among‐population covariation between sperm performance and environmental osmolality. Frogs were obtained from nine populations that differed in environmental osmolality, and sperm samples of males from different populations were subjected to a range of activation‐medium osmolalities. Percentage sperm motility was optimal between 10 and 50 mOsm kg−1, and sperm velocity was optimal between 10 and 100 mOsm kg−1, indicating that C. signifera has evolved sperm that can function across a broad range of osmolalities. As predicted, there was significant among‐population variation in sperm performance. Furthermore, there was a significant interaction between activation‐medium osmolality and environmental osmolality, indicating that frogs from populations with higher environmental osmolality produced sperm that performed better at higher osmolalities in vitro. This finding may reflect phenotypic plasticity in sperm functioning, or genetic divergence resulting from spatial variation in the strength of directional selection. Both of these explanations are consistent with evolutionary theory, providing some of the first empirical evidence that local osmotic environments can favour adaptive sperm motility responses in species that use an external mode of fertilization.
The AvrE superfamily: ancestral type III effectors involved in suppression of pathogen‐associated molecular pattern‐triggered immunity
Authors: Degrave Alexandre , Siamer Sabrina , Boureau Tristan , Barny Marie‐Anne
Published: January 2015

The AvrE superfamily of type III effectors (T3Es) is widespread among type III‐dependent phytobacteria and plays a crucial role during bacterial pathogenesis. Members of the AvrE superfamily are vertically inherited core effectors, indicating an ancestral acquisition of these effectors in bacterial plant pathogens. AvrE‐T3Es contribute significantly to virulence by suppressing pathogen‐associated molecular pattern (PAMP)‐triggered immunity. They inhibit salicylic acid‐mediated plant defences, interfere with vesicular trafficking and promote bacterial growth in planta. AvrE‐T3Es elicit cell death in both host and non‐host plants independent of any known plant resistance protein, suggesting an original interaction with the plant immune system. Recent studies in yeast have indicated that they activate protein phosphatase 2A and inhibit serine palmitoyl transferase, the first enzyme of the sphingolipid biosynthesis pathway. In this review, we describe the current picture that has emerged from studies of the different members of this fascinating large family.
The enzymatic activities of brain catechol‐O‐methyltransferase (COMT) and methionine sulphoxide reductase are correlated in a COMT Val/Met allele‐dependent fashion
Authors: Moskovitz Jackob , Walss‐Bass Consuelo , Cruz Dianne A. , Thompson Peter M. , Hairston Jenaqua , Bortolato Marco
Published: January 2015

Aims

The enzyme catechol‐O‐methyltransferase (COMT) plays a primary role in the metabolism of catecholamine neurotransmitters and is implicated in the modulation of cognitive and emotional responses. The best characterized single nucleotide polymorphism (SNP) of the COMT gene consists of a valine (Val)‐to‐methionine (Met) substitution at codon 108/158. The Met‐containing variant confers a marked reduction in COMT catalytic activity. We recently showed that the activity of recombinant COMT is positively regulated by the enzyme Met sulphoxide reductase (MSR), which counters the oxidation of Met residues of proteins. The current study was designed to assess whether brain COMT activity may be correlated to MSR in an allele‐dependent fashion.

Methods

COMT and MSR activities were measured from post‐mortem samples of prefrontal cortices, striata and cerebella of 32 subjects by using catechol and dabsyl‐Met sulphoxide as substrates, respectively. Allelic discrimination of COMT Val108/185Met SNP was performed using the Taqman 5'nuclease assay.

Results

Our studies revealed that, in homozygous carriers of Met, but not Val alleles, the activity of COMT and MSR was significantly correlated throughout all tested brain regions.

Conclusion

These results suggest that the reduced enzymatic activity of Met‐containing COMT may be secondary to Met sulphoxidation and point to MSR as a key molecular determinant for the modulation of COMT activity.
HIV presenting with a maxillary alveolus tumour
Authors: Dunphy L. , Halsnad M. , Praveen P.
Published: January 2015

Since the advent of human immunodeficiency virus (HIV) in 1981, the availability of highly active anti‐retroviral therapy has transformed this condition from a death sentence to a highly manageable condition. Unfortunately, a large proportion present late, resulting in increased mortality and morbidity and ultimately an increased risk of forward transmission. Oral manifestations are among the earliest and most important indicators of infection, suggesting a decreased CD4 T‐cell count and an increased viral load. In the UK, a large proportion of patients are diagnosed with a CD4 count <350 cells/mm3, which is below the recommended threshold for commencing HIV treatment. This case reinforces the importance of considering HIV in the differential diagnosis of an oral lesion, consolidates our knowledge of oral lesions associated with immune suppression and discusses the implications of late diagnosis.
Electrical Dysfunction Associated with Conductor Externalization of a Silicone Left Ventricular Lead
Authors: MENDENHALL G. STUART , SABA SAMIR
Published: January 2015

The St. Jude Medical QuickFlex LV lead family (St. Jude Medical, Inc., St. Paul, MN, USA) has been placed under advisory by the manufacturer due to a reported small number of cases of outer insulation failure and conductor externalization. There have been no reports of alteration of any electrical parameters associated with externalization. In this report, a sudden drop of impedance and rise in capture threshold of the left ventricular ring electrode is described, associated with the corresponding externalization of the inner conductor cables confirmed on physical examination. Flexion or torsion of lead was demonstrative of forces favoring externalization of inner conductor cables. Saline bath testing revealed a reproducible, transient reduction in lead resistance associated with conductor externalization. Close monitoring of electrical performance of this lead family is indicated.
Role of microRNAs in plant drought tolerance
Authors: Ferdous Jannatul , Hussain Syed S. , Shi Bu‐Jun
Published: January 2015

Drought is a normal and recurring climate feature in most parts of the world and plays a major role in limiting crop productivity. However, plants have their own defence systems to cope with adverse climatic conditions. One of these defence mechanisms is the reprogramming of gene expression by microRNAs (miRNAs). miRNAs are small noncoding RNAs of approximately 22 nucleotides length, which have emerged as important regulators of genes at post‐transcriptional levels in a range of organisms. Some miRNAs are functionally conserved across plant species and are regulated by drought stress. These properties suggest that miRNA‐based genetic modifications have the potential to enhance drought tolerance in cereal crops. This review summarizes the current understanding of the regulatory mechanisms of plant miRNAs, involvement of plant miRNAs in drought stress responses in barley (Hordeum vulgare L.), wheat (Triticum spp.) and other plant species, and the involvement of miRNAs in plant‐adaptive mechanisms under drought stress. Potential strategies and directions for future miRNA research and the utilization of miRNAs in the improvement of cereal crops for drought tolerance are also discussed.
Vicious Regresses, Conceptual Analysis, and Strong Awareness Internalism
Authors: Stoutenburg Gregory
Published: January 2015

That a philosophical thesis entails a vicious regress is commonly taken to be decisive evidence that the thesis is false. In this paper, I argue that the existence of a vicious regress is insufficient to reject a proposed analysis provided that certain constraints on the analysis are met. When a vicious regress is present, some further consequence of the thesis must be established that, together with the presence of the vicious regress, shows the thesis to be false. The argument is provided largely through the examination of Michael Bergmann's (2006) vicious regress argument against strong awareness internalism and a partial defense of that thesis against Bergmann.
Survival in rheumatoid arthritis‐associated pulmonary arterial hypertension compared with idiopathic pulmonary arterial hypertension
Authors: Sadeghi Saghar , Granton John T. , Akhavan Pooneh , Pasarikovski Christopher R. , Roos Adrienne M. , Thenganatt John , Moric Jakov , Johnson Sindhu R.
Published: January 2015

Background and objective

In this study, we evaluated survival in rheumatoid arthritis‐associated pulmonary arterial hypertension (RA‐PAH) compared with idiopathic pulmonary arterial hypertension (IPAH) patients, and evaluate differences in disease severity and treatment.

Methods

We conducted a retrospective cohort study of RA‐PAH and IPAH at the University Health Network Pulmonary Hypertension Programme, Toronto, Canada. The primary outcome was time to all‐cause mortality. We evaluated survival using Kaplan–Meier curves. Using a propensity score‐matched cohort, we used Cox proportional hazards models to estimate survival.

Results

Screening 1385 patients identified 18 RA‐PAH and 155 IPAH patients. RA‐PAH patients had an older median age of onset (64.0 vs 53.7 years) and lower baseline mean pulmonary arterial pressure (mPAP) (41 vs 50 mm Hg, P = 0.02). RA‐PAH patients tended to have a higher proportion of females (83% vs 70%, relative risk 0.55, 95% confidence interval (CI): 0.19–1.57), lower proportion with baseline World Health Organization functional class III/IV (39% vs 52%), lower median baseline brain natriuretic peptide (58.4 vs 95.0 pg/mL) and longer baseline 6‐min walk distance (440 vs 397 m). There were 35 deaths, 2/18 (11%) RA‐PAH patients and 33/155 (21%) IPAH patients. The unadjusted 1‐year survival was 93% for RA‐PAH and 94% for IPAH. In the matched cohort, there were seven deaths: 2/18 (11%) RA‐PAH and 5/18 (28%) IPAH patients, hazard ratio 1.53 (95% CI: 0.15–2.84). Separation of survival curves did not achieve statistical significance, log–rank 0.56.

Conclusions

Compared with IPAH patients, RA‐PAH patients have an older age of onset and lower baseline mPAP. RA‐PAH patients have comparable survival to IPAH patients.
Trends in Arteriovenous Fistula Use at Dialysis Initiation After Automated eGFR Reporting
Authors: Sood Manish M. , Akbari Ayub , Hiebert Brett , Hiremath Swapnil , Komenda Paul , Rigatto Claudio , Zimmerman Deborah , Tangri Navdeep
Published: January 2015

The purpose of this study was to examine trends in the presence of an arteriovenous fistula (AVF) at dialysis initiation before and after eGFR reporting. All incident dialysis patients from four Canadian provinces that implemented province‐wide, automated laboratory reporting of eGFR with known vascular access at dialysis initiation were included in the study (N = 25,201) from 2001 to 2010. The primary outcome was the change in proportion of patients with an AVF at dialysis initiation using an interrupted time series and adjusted multilevel logistic regression models. AVF usage at dialysis initiation decreased gradually over the study period from 19.0% to 14.6%. After implementation of automated eGFR reporting, there was attenuation in the decline in AVF usage in models adjusted for case‐mix, facility, and the downward trajectory in AVF use over time. The adjusted odds ratio for initiating dialysis with an AVF 1 year post‐eGFR reporting compared to pre‐eGFR reporting was more pronounced in older patients (age tertile >73; OR: 1.40; 95% CI: 1.04–1.90). Laboratory‐based eGFR reporting was associated with a possible attenuation in the decline of AVF at dialysis initiation and this was more pronounced in older patients.
Body hair counts during hair length reduction procedures: a comparative study between Computer Assisted Image Analysis after Manual Processing (CAIAMP) and Trichoscan™
Authors: Van Neste D. J. J.
Published: January 2015

Purpose

To compare two measurement methods for body hair.

Methods

Calibration of computer assisted image analysis after manual processing (CAIAMP) showed variation <4% for thickness and <2.3% for densities. Images from 6 body sites with ‘good natural contrast between hair and skin’ were taken before hair dye, after hair dye or after hair length reduction without hair extraction or destruction. Data in the same targets were compared with Trichoscan™ quoted for ‘unambiguous evaluation of the hair growth after shaving’.

Results

CAIAMP detected a total of 337 hair and showed no statistically significant differences with the three procedures confirming ‘good natural contrast between hair and skin’ and that reduction methods did not affect hair counts.

While CAIAMP found a mean number of 19 thick hair (≥30 μm) before dye, 18 after dye and 20 after hair reduction, Trichoscan™ found in the same sites respectively 44, 73 and 61. Trichoscan™ generated counts differed statistically significantly from CAIAMP‐data. Automated analyses were considered un‐specifically influenced by hair medulla and natural or artificial skin background.

Conclusion

Quality control including all steps of human intervention and measurement technology are mandatory for body hair measurements during experimental or clinical trials on body hair grooming, shaving or removal.
HLA‐B*46:60, a novel variant of HLA‐B*46:01:01, detected in a Taiwanese unrelated hematopoietic stem cell donor by sequence‐based typing
Authors: Yang K. L. , Lee S. K. , Hung J. H. , Lin P. Y.
Published: January 2015

One nucleotide replacement at residue 89 of HLA‐B*46:01:01 results in a novel allele, HLA‐B*46:60.
Investigation of Buoyancy Effects on Heat Transfer Characteristics of Supercritical Carbon Dioxide in Heating Mode
Authors: Pidaparti Sandeep R. , McFarland Jacob A. , Mikhaeil Mark M. , Anderson Mark H. , Ranjan Devesh
Published: January 2015

Experiments were performed to investigate the effects of buoyancy on heat transfer characteristics of supercritical carbon dioxide in heating mode. Turbulent flows with Reynolds numbers up to 60,000, at operating pressures of 7.5, 8.1, and 10.2 MPa, were tested in a round tube. Local heat transfer coefficients were obtained from measured wall temperatures over a large set of experimental parameters that varied inlet temperature from 20 to 55°C, mass flux from 150 to 350  kg/m2s, and a maximum heat flux of 65  kW/m2. Horizontal, upward, and downward flows were tested to investigate the unusual heat transfer characteristics due to the effect of buoyancy and flow acceleration caused by large variation in density. In the case of upward flow, severe localized deterioration in heat transfer was observed due to reduction in the turbulent shear stress and is characterized by a sharp increase in wall temperature. In the case of downward flow, turbulent shear stress is enhanced by buoyancy forces, leading to an enhancement in heat transfer. In the case of horizontal flow, flow stratification occurred, leading to a circumferential variation in wall temperature. Thermocouples mounted 180° apart on the tube revealed that the wall temperatures on the top side are significantly higher than the bottom side of the tube. Buoyancy factor calculations for all the test cases indicated that buoyancy effects cannot be ignored even for horizontal flow at Reynolds numbers as high as 20,000. Experimentally determined Nusselt numbers are compared to existing correlations available in the literature. Existing correlations predicted the experimental data within ±30%, with maximum deviation around the pseudocritical point.
Speciknee: An Engineering Software Tool for Design of Simple Four-Bar Prosthesis Joints for Above-Knee Amputees
Authors: Thompson Thomas J. , Watson Erkai
Published: January 2015

This paper presents the vector analysis used to develop an educational computer design tool which could enable prosthetists and mechanical designers to tailor the motion of low-cost, four-bar prosthetic knees to the sizes and needs of individual amputees. In designing a prosthetic knee joint, it is important to control the position of the lower leg in three angles of flexion and to control its center of rotation in the standing position. In 2010 [1] this problem was analyzed using vector methods, and an algorithm was written which produced curves displaying pivot locations which solve the problem exactly. Since then, a software tool called Speciknee has been developed by building on the core vector computational method and adding a user-friendly operator interface through which a designer could input individual patient needs, select pivot points along the set of curves where prosthetic joint pivots could be placed, and animate the mechanism.
Nonlinear Vibrations of Rectangular Mooney-Rivlin Membrane Resting on a Nonlinear Elastic Foundation
Authors: Soares Renata M. , Gonçalves Paulo B.
Published: January 2015

The aim of the present work is to investigate the nonlinear vibration response of a pre-stretched rectangular hyperelastic membrane resting on a nonlinear elastic foundation. The membrane is composed of an isotropic, homogeneous and hyperelastic material, which is modeled as a Mooney-Rivlin incompressible material. The elastic foundation is described by a Winkler type nonlinear model with cubic nonlinearity. First the exact solution of the membrane under a biaxial stretch is obtained. Then the equations of motion of the pre-stretched membrane resting on the nonlinear foundation are derived. From the linearized equations, the natural frequencies and mode shapes of the membrane are obtained analytically. Then the natural modes are used to approximate the nonlinear deformation field using the Galerkin method. The results compare well with the results evaluated for the same membrane using a nonlinear finite element formulation. The results show the strong influence of the initial stretching ratio and foundation parameters on the linear and nonlinear oscillations and stability of the membrane.
Torque Distribution Control for Multi-Wheeled Combat Vehicle
Authors: Ragheb Hossam , El-Gindy Moustafa , Kishawy Hossam
Published: January 2015

Multi-wheeled combat vehicles behavior depends not only on the available total driving torque but also on its distribution among the drive axles/wheels. In turn, this distribution is largely regulated by the drivetrain layout and its torque distribution devices.

In this paper, a multi-wheeled (8×4) combat vehicle bicycle model has been developed and used to obtain the desired yaw rate and lateral acceleration to become reference for the design of the controllers. PID controllers were designed as upper and lower layers of the controllers. The upper controller develops the corrective yaw moment, which is the input to the lower controller to manage the independent torque distribution (torque vectoring) among the driving wheels. Several simulation maneuvers have been performed at different vehicle speeds using Matlab/Simulink-TruckSim to investigate the proposed torque vectoring control strategy. The simulation results with the proposed controller showed a significant improvement over conventional driveline, especially at severe maneuvers.
Vibration Control of Autoparametric System Using SMA Spring and MR Dampers in the Pendula Joins
Authors: Sado Danuta , Pietrzakowski Marek , Kęcik Krzysztof
Published: January 2015

This work is concerned with the problem of nonlinear dynamical motion of a non-ideal autoparametric system with two active elements — shape memory alloys (SMA) spring and the magnetorheological (MR) pin joint dampers in the neighbourhood internal and external resonance. A polynomial constitutive model was assumed to describe the behaviour of SMA’s spring and there was observed the pseudoelastic effects associated with martensitic phase transformations. The simplified resistance moment generated by the MR pin joint can be approximated using the hyperbolic tangent function. The influence of damping forces in MR dampers on the phenomenon of energy transfer and pseudoelastic effects associated with the martensitic phase transformation was studied. It was shown that in this type system one mode of vibrations might excite or damp another mode, and that except different kinds of periodic vibrations there may also appear chaotic vibrations. For the identification of the responses of the system various techniques, including chaos techniques such as bifurcation diagrams and time histories, power spectral densities (FFT), Poincarè maps and exponents of Lyapunov may be used. The SMA spring and MR damper can be used to change the dynamic behaviour of the autoparametric system giving reliable semiactive control possibilities.
Parametric Instability in Planetary Gears With Frequency-Modulated Time-Varying Mesh Stiffness
Authors: Qiu Xinghui , Han Qinkai , Chu Fulei
Published: January 2015

A rotational model of planetary gears is developed which incorporates mesh stiffness variation and input speed fluctuations. Gear mesh stiffness is approximated by rectangle wave and different harmonic orders are considered. Because of speed fluctuations, the mesh stiffness is frequency modulated. The parametric instability associated with frequency-modulated time-varying stiffness is numerically investigated. The operating conditions leading to parametric instability are identified using Floquet theory and numerical integration. Whether the general laws derived for steady speed to suppress particular instabilities are applicable for fluctuating speed is verified. The effects of speed fluctuations on parametric instability are examined.
Vibrations due to Impact in a Non Ideal Mechanical System With a Non-Linear Hertzian Contact Model
Authors: Navarro Helio A. , Balthazar Jose M. , Brasil Reyolando M. L. R. F.
Published: January 2015

This work analyses the post impact behavior of a mechanical system consisting of an oscillator and an unbalanced non–ideal electrical motor. The impact between the mechanical system and a rigid wall is based on the assumption that the impacting bodies undergo local deformations. The method used in the present work is similar to the Discrete Element Method for particle systems modeled with a “soft–sphere” mechanism. The contact forces are modeled using a nonlinear damped Hertzian Spring-Dashpot system. The mathematical model of the mechanical system is represented by a set of nonlinear ordinary differential equations. The transient and steady-state responses are discussed. As the motor is considered a non ideal energy source, the Sommerfeld effect is also analyzed. The impact model is first applied for a single freely falling particle and then in the proposed mechanical system. Non-dimensional expressions for the contact force and numerical simulations of the mechanical system behavior are also presented.
Evolution of Meso-Structures for Non-Pneumatic Tire Development: A Case Study
Authors: Fazelpour Mohammad , Summers Joshua D.
Published: January 2015

The evolution of meso-structures in the development of the shear band of Michelin’s non-pneumatic tire, the Tweel, is presented in this paper. Designers and researchers at Clemson University worked on a research projects with Michelin to support NIST efforts in fuel efficiency improvement and NASA efforts in manned exploration systems. The goal of each was to replace the elastomeric material of shear band with materials which can tolerate harsh temperatures and shear loads or to replace the materials with linear elastic low-hysteretic loss materials. The concepts initially proposed by ideation method were prototyped for physical testing. A case study examining the documentation reports for each project is conducted to provide a reflective understanding of how the evolution in the projects occurred. The goal of developing this retrospective is to try to identify guidelines and approaches that could be integrated into a designer driven systematic approach for custom design of meso-structures.
Manufacturability Feedback and Model Correction for Additive Manufacturing
Authors: Nelaturi Saigopal , Kim Walter , Rangarajan Arvind , Kurtoglu Tolga
Published: January 2015

Additive manufacturing, or 3d printing, is the process of building three dimensional solid shapes by accumulating material laid out in sectional layers. Additive manufacturing has been recognized for enabling production of complex custom parts that are difficult to manufacture otherwise. However, the dependence on build orientation and physical limitations of printing processes invariably lead to geometric deviations between manufactured and designed shapes that are usually evaluated after manufacture. In this paper, we formalize the measurement of such deviations in terms of a printability map that simulates the printing process and partitions each printed layer into disjoint regions with distinct local measures of size. We show that manufacturing capabilities such as printing resolution, and material specific design recommendations such as minimal feature sizes may be coupled in the printability map to evaluate expected deviations before manufacture. Furthermore, we demonstrate how partitions with size measures below required resolutions may be modified using properties of the medial axis transform, and use the corrected printability map to construct a representation of the manufactured model. We conclude by discussing several applications of the printability map for additive manufacturing.
Cued Active Learning: An Initial Study
Authors: Orsborn Seth , Hutcheson Ryan
Published: January 2015

It has become common knowledge that effective teaching requires more than just the rote dissemination of knowledge. By using active learning, teachers involve the students in the learning process. As the students subjectively handle the class material, their comprehension and retention improves. In the classroom, teachers commonly prompt actively learning through a verbal cue such as, “We are now going to break into groups.” This forces the student to switch from a receptive mental state to an active mental state.

We theorize that this verbal, short duration transition from lecture to active learning, especially in large classroom settings, is not sufficient to make this transition quickly and thus limits how active students are in the active learning session. In this paper we present a technique and exploratory study results for cueing active learning through a representative icon in a visual lecture presentation. This cue enables the students to mentally prepare themselves for actively learning during a more passive part of the lecture. The results of our exploratory study demonstrate that the cued active learning did not conclusively correlate with average student performance, but that it did show a decrease in the standard deviation of performance, thereby demonstrating an improvement in the comprehension of the students that were more likely to perform lower than average. The results of this study will be used to conduct a more formal study including direct measurement of lecture participation by students.
Rigid-Body Parameters for Molecular Docking Applications
Authors: Chirikjian Gregory S.
Published: January 2015

In mechanisms and robotics it is common to describe motions relative to a ground link, or robot base, and the position and orientation of the distal link (or robot hand) is viewed as a rigid-body motion relative to this fixed world frame. Assessing preferred relative rigid-body position and orientation in interacting biomolecules (such as proteins) often uses this approach as well by artificially calling one molecule the ground, and considering the motions of another molecule relative to it. But since both molecules are floating, it is not as natural to take this perspective as it is in the field of mechanisms and robotics. Therefore, this paper introduces a ‘symmetrical’ parameterization of relative biomolecular motions in which the structure of the equations is the same when each molecule views the other. In this way, there is no bias in terms of labeling one molecule as being fixed and the other as moving. The properties of this new parameterization are evaluated and compared with traditional ones known to the kinematics community.
The Use of Wavelets Analysis to Characterize the Dynamic Behavior of Energy Transfer Vibrational Systems
Authors: Iliuk Itamar , Balthazar José M. , Tusset Angelo M. , Piccirillo Vinicius , Brasil Reyolando M. L. R. F. , Piqueira José R. C.
Published: January 2015

This paper describes the use of wavelet analysis for identification of regular and irregular behavior of dynamical systems. We are focused in single and double-well potential energy harvesting systems that present either periodic or chaotic behavior. To identify the behavior of dynamical systems is of major importance in predicting possible energy harvesting from that system. Using Morlet wavelets, the oscillatory motions of a set of systems were identified with good accuracy. The visualization of the scalograms and global energy spectrum are very useful tools to validate the type of motion found, periodic, quasi-periodic or chaotic. Wavelet analysis can be used to find which amplitude and frequency of operation that generates more energy for each model. Wavelet analysis is a technique used as a tool to assist the validation of the presence of chaos in dynamic systems, together with well consolidated techniques as Lyapunov exponents and Poincare maps.
A Robust Surrogate Modeling Approach for Material Selection in Sustainable Design of Products
Authors: Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Wileden Jack , Lewis Kemper
Published: January 2015

A sustainable solution should holistically optimize all objectives related to the environment and a product’s cost and performance. As such, it should explicitly address material selection, which significantly affects environmental impacts and other objectives of a product design. While Life Cycle Assessment (LCA) provides credible methods to account for environmental impacts, current methods are not efficient enough for use at the early design stages to prune the entire design space without requiring execution of costly LCA analysis for each design scenario. Alternatively, surrogate modeling approaches can facilitate efficient concept selection during early design stages. However, material properties consist of discrete data sets, thus posing a significant challenge in the construction of surrogate models for numerical optimization.

In this work, we address the unique challenges of material selection in sustainable product design in some important ways. Salient features of the robust surrogate modeling approach include achieving manageable dimensionality of LCA with a minimal loss of the important information by the consolidation of significant factors into categorized groups, as well as subsequent efficiency enhancement by a streamlined process that avoids the construction of full LCA. This novel approach combines efficiency of use with a mathematically rigorous representation of any pertinent objectives across an entire design space. To this end, we introduce an adapted two stage sampling approach in surrogate model construction based on a feasible approximation of a Latin Hypercube design at the first stage. The development and implementation of the method are illustrated with the aid of an automotive disc brake design, and the results are discussed in the context of robust optimal material selection in early sustainable product design.
Nonlinear Dynamics and Application of the Four Dimensional Autonomous Hyper-Chaotic System
Authors: Kai Ge , Zhang Wei
Published: January 2015

In this paper, we establish a dynamic model of the hyper-chaotic finance system which is composed of four sub-blocks: production, money, stock and labor force. We use four first-order differential equations to describe the time variations of four state variables which are the interest rate, the investment demand, the price exponent and the average profit margin. The hyper-chaotic finance system has simplified the system of four dimensional autonomous differential equations. According to four dimensional differential equations, numerical simulations are carried out to find the nonlinear dynamics characteristic of the system. From numerical simulation, we obtain the three dimensional phase portraits that show the nonlinear response of the hyper-chaotic finance system. From the results of numerical simulation, it is found that there exist periodic motions and chaotic motions under specific conditions. In addition, it is observed that the parameter of the saving has significant influence on the nonlinear dynamical behavior of the four dimensional autonomous hyper-chaotic system.
Electromagnetic Design of In-Vehicle Reactor Using a Level-Set Based Topology Optimization Method
Authors: Yamasaki Shintaro , Kawamoto Atsushi , Saito Akira , Kuroishi Masakatsu , Fujita Kikuo
Published: January 2015

In this paper, we propose a level-set based topology optimization method for designing a reactor, which is used as a part of the DC-DC converter in electric and hybrid vehicles. Since it realizes a high-power driving motor and its performance relies on its component, i.e., reactor core, it is valuable to establish a reasonable design method for the reactor core. Boundary tracking type level-set topology optimization is suitable for this purpose, because the shape and topology of the target structure is clearly represented by the zero boundary of the level-set function, and the state variables are accurately computed using the zero boundary tracking mesh. We formulate the design problem on the basis of electromagnetics, and derive the design sensitivities. The derived sensitivities are linked with boundary tracking type level-set topology optimization, and as a result, a useful structural optimization method for the reactor core design problem is developed.
Prototyping for the Product Experience: An Example in the Household Appliances Industry
Authors: Bordegoni Monica , Cugini Umberto , Ferrise Francesco , Graziosi Serena
Published: January 2015

The objective of the paper is to present a case study to exploit interactive Virtual Prototypes (iVPs) for investigating the way humans experience products. This method can be used for “prototyping” new product experiences, for monitoring users’ emotional reactions during the interaction and finally, for practically redesigning these experiences on the basis of the users’ feedback. Products considered here are domestic appliances, where the experience consists of the interaction with their physical interfaces.
Bifurcation Analysis of a Non-Linear On-Board Rotor-Bearing System
Authors: Dakel Mzaki , Baguet Sébastien , Dufour Régis
Published: January 2015

The non-linear dynamic behavior of an on-board rotor mounted on hydrodynamic journal bearings and subject to rigid base excitations is investigated in this work. The proposed finite element rotor model takes into account the geometric asymmetry of shaft and/or rigid disk and considers six types of base deterministic motions (rotations and translations) and non-linear fluid film forces obtained from the Reynolds equation. The equations of motion contain time-varying parametric coefficients because of the geometric asymmetry of the rotor and the base rotations. In the case when sinusoidal excitations of the rotor base lead to periodic (harmonic and sub-harmonic) responses, an optimized shooting algorithm based on the non-linear Newmark time integration scheme is employed to solve the equations of motion. The non-linear phenomena observed in the on-board rotor-bearing system, such as period-doubling motion and chaos, are characterized by means of bifurcation diagrams, rotor orbits and Poincaré maps.
An Overview of Several Formulations for Dry and Lubricated Revolute Joint Clearances in Planar Rigid-Multi-Body Mechanical Systems
Authors: Flores Paulo , Lankarani Hamid M.
Published: January 2015

The influence of the revolute joint model on the dynamic response of planar multibody mechanical systems is studied in this work. In the sequel of this process, under the framework of the multibody formalisms, a general methodology for modeling the main kinematic aspects of dry revolute joint clearances is revisited. The numerical models for normal and tangential contact forces developed at the clearance joints are also discussed, which are based on the Hertzian contact theory and dry Coulomb’s friction law, respectively. The fundamental kinematic and dynamic issues of the modeling lubricated revolute joints are presented in this work in order to compare them with the dry revolute joint approach. In a simple manner, the lubrication forces are obtained by integrating the pressure distribution evaluated with the aid of Reynolds’ equation corresponding to the dynamic regime. The intra-joint forces developed for both dry and lubricated cases are evaluated based on the state of variable of the system and subsequently included into the dynamic equations of motion of the multibody system as external generalized forces. The main assumptions and procedures adopted throughout this work are demonstrated through simulations of a planar slider-crank mechanism, which includes dry and lubricated revolute joint with clearance. Finally, some experimental data is also presented and analyzed.
Adding and Subtracting Energy to Body Motion: Phase Oscillator
Authors: Kerestes Jason , Sugar Thomas G. , Holgate Matthew
Published: January 2015

We are developing methods to add a bounded amount of energy to assist body motion. Energy is added based on the phase angle of the limb to create a “phase oscillator.” The energy is added assisting motion creating an oscillatory behavior. An anti-phase angle can be used to subtract energy from body motion as well. Using a “phase oscillator” controller, a powered hip exoskeleton assisted a runner and demonstrated a reduction in metabolic cost.
Determination of Variable Stiffness of a Human Elbow for Human-Robot Interaction
Authors: Boyarsky Michael , Heenan Megan , Beardsley Scott , Voglewede Philip
Published: January 2015

This paper aims to emulate human motion with a robot for the purpose of improving human-robot interaction (HRI). In order to engineer a robot that demonstrates functionally similar motion to humans, aspects of human motion such as variable stiffness must be captured. This paper successfully determined the variable stiffness humans use in the context of a 1 DOF disturbance rejection task by optimizing a time-varying stiffness parameter to experimental data in the context of a neuro-motor Simulink model. The significant improved agreement between the model and the experimental data in the disturbance rejection task after the addition of variable stiffness demonstrates how important variable stiffness is to creating a model of human motion. To enable a robot to emulate this motion, a predictive stiffness model was developed that attempts to reproduce the stiffness that a human would use in a given situation. The predictive stiffness model successfully decreases the error between the neuro-motor model and the experimental data when compared to the neuro-motor model with a constant stiffness value.
Bayesian Network Classifiers and Design Flexibility Metrics for Set-Based, Multiscale Design With Materials Design Applications
Authors: Matthews Jordan , Klatt Timothy , Seepersad Carolyn C. , Haberman Michael , Shahan David
Published: January 2015

A set-based approach is presented for solving multi-scale or multi-level design problems. The approach incorporates Bayesian network classifiers (BNC) for mapping design spaces at each level and flexibility metrics for intelligently narrowing the design space as the design process progresses. The approach is applied to a hierarchical composite materials design problem, specifically, the design of composite materials with macroscopic mechanical stiffness and loss properties surpassing those of conventional composites. This macroscopic performance is achieved by embedding small volume fractions of negative stiffness (NS) inclusions in a host material. To design these materials, the set-based, multilevel design approach is coupled with a hierarchical modeling strategy that spans several scales, from the behavior of microscale NS inclusions to the effective properties of a composite material containing those inclusions and finally to the macroscopic performance of components. The approach is shown to increase the efficiency of multi-level design space exploration, and it is particularly appropriate for top-down, performance-driven design, as opposed to bottom-up, trial-and-error modeling. The design space mappings also build intuitive knowledge of the problem and promising regions of the design space, such that it is almost trivial to identify designs that yield preferred system-level performance.
Combination of Compositional Verification and Model Checking for Safety Assessment of Complex Engineered Systems
Authors: Mehrpouyan Hoda , Giannakopoulou Dimitra , Tumer Irem Y. , Hoyle Chris , Brat Guillaume
Published: January 2015

This paper presents a novel safety specification and verification approach based on the compositional reasoning and model checking algorithms. The behavioral specification of each component and subsystem is modeled to describe the overall structure of the design. Then, these specifications are analyzed to determine the least number of component redundancies that are required to tolerate and prevent catastrophic system failure. The framework utilizes Labelled Transition Systems (LTS) formalism to model the behavior of components and subsystems. Furthermore, compositional analysis is used to reason about the components’ constraints (or assumptions) on their environments and the properties (or guarantees) of their output. This identification of local safety properties of components and subsystems leads to satisfaction of the desired safety requirements for the global system. A model of quad-redundant Electro-Mechanical Actuator (EMA) is constructed and, in an iterative approach, its safety properties are analyzed. Experimental results confirm the feasibility of the proposed approach for verifying the safety issues associated with complex systems in the early stages of the design process.
An Inductive Approach to Teaching Interdisciplinary Design Outside of the Curriculum
Authors: Kim Charles , Tranquillo Joseph
Published: January 2015

The KEEN Winter Interdisciplinary Design Experience (K-WIDE) is an immersive co-curricular program that exposes students to authentic open-ended design inductively. K-WIDE occurs outside of the curriculum and does not bear any credit. Students do not receive any pay for the program, and their only motivation is to learn about design. We believe that our pedagogical approach which immerses students in intensive design, provides opportunities to learn and apply hands-on skills, and encourages critical reflection is effective in leading participants to become global systems thinkers. Students gain important skills in looking at problems from a wide range of perspectives to consider the societal impact of potential solutions while also being conversant in technical engineering to ensure the viability of a concept. In this paper we present the general pedagogical approach and provide some examples of the effect the program is having on students.
Cloth Napkin Singulation System
Authors: Banik Shuvra , Hoberock Lawrence L.
Published: January 2015

Manual wrapping of silverware pieces in napkins in large food service establishments is a repetitive, tedious, time-consuming and labor-intensive process, which can be improved by automation. This paper describes the design, development, construction, and evaluation of an automated cloth napkin singulation system, a major subsystem of an automated silverware wrapping system, which is capable of singulating individual cloth napkins from a stack of napkins to feed the wrapping system. The system employs automatically renewable adhesive tape to pick napkins from the stack and linear actuated mechanisms to remove a napkin from the tape and pass it along a moving conveyor. The cycle is repeated until all napkins in the feed stack have been singulated. The system was tested for 100 napkin cycles, and the average singulation efficiency of the system was found to be 96%, which is a 14% increase over previous napkin singulator devices. The average singulation time for each napkin cycle was 1.3 minutes, but this time can easily be decreased by employing higher speed mechanism drive motors.
T-Spline Based Local Refinement for Mesh Independent Analysis
Authors: Burla Ravi K. , Kumar Ashok V.
Published: January 2015

Structured background mesh with regular shaped uniform elements is easy to generate automatically. Analysis using such a mesh is possible with an independent CAD model representing the geometry by using Implicit Boundary Method. This avoids mesh generation difficulties and enables new types of elements that use B-spline approximations instead of the traditional Lagrange interpolations. But the background mesh should ideally have higher resolution in areas where the solution has large gradients. In this paper, T-spline basis functions are used to locally refine a structured mesh. T-splines allow construction of elements with T-junctions maintaining the continuity of the field variable across element boundaries and hence ensure that compatibility conditions are satisfied. T-spline elements are constructed for linear and cubic basis. Essential boundary conditions are applied using implicit boundary method, which allows boundary conditions to be imposed even when there are no nodes on the boundary. T-spline elements are shown to represent constant and linear solution exactly. The mesh refinement technique is evaluated using two dimensional elasticity problem involving stress concentration.
Vascular Fluid Damping of Flexible Multifunctional Composite Cantilevers: Experiment, Modeling and Analysis
Authors: Gaucher-Petitdemange Matthias , Wang Ya , Masoumi Masoud , Inman Daniel J.
Published: January 2015

Passive structural damping treatments based on viscoelastic polymers of elastomers are widely used in practice and have been the focus of numerous research studies and papers. Here we examine a multifunctional structure with vascular channels and investigate how the fluid in the channels provides damping to the system. While the vibration and stability of flow through a pipe has been extensively examined, internal fluid induced passive damping has not been well investigated in literature. Motivated by research in using vascular channels to provide self-cooling and autonomous healing of multifunctional composites, here we investigate the material and mechanical parameter dependence effects of internal fluid damping using an experimental study, modeling and numerical analysis of the dynamics of flexible cantilever beam conveying three types of internal vascular fluid flows.