Evolution of flexibility and rigidity in retaliatory punishment.

Science.gov (United States)

Morris, Adam; MacGlashan, James; Littman, Michael L; Cushman, Fiery

2017-09-26

Natural selection designs some social behaviors to depend on flexible learning processes, whereas others are relatively rigid or reflexive. What determines the balance between these two approaches? We offer a detailed case study in the context of a two-player game with antisocial behavior and retaliatory punishment. We show that each player in this game-a "thief" and a "victim"-must balance two competing strategic interests. Flexibility is valuable because it allows adaptive differentiation in the face of diverse opponents. However, it is also risky because, in competitive games, it can produce systematically suboptimal behaviors. Using a combination of evolutionary analysis, reinforcement learning simulations, and behavioral experimentation, we show that the resolution to this tension-and the adaptation of social behavior in this game-hinges on the game's learning dynamics. Our findings clarify punishment's adaptive basis, offer a case study of the evolution of social preferences, and highlight an important connection between natural selection and learning in the resolution of social conflicts.

An Experimental Comparison Between Flexible and Rigid Airfoils at Low Reynolds Numbers

Science.gov (United States)

Uzodinma, Jaylon; Macphee, David

2017-11-01

This study uses experimental and computational research methods to compare the aerodynamic performance of rigid and flexible airfoils at a low Reynolds number throughout varying angles of attack. This research can be used to improve the design of small wind turbines, micro-aerial vehicles, and any other devices that operate at low Reynolds numbers. Experimental testing was conducted in the University of Alabama's low-speed wind tunnel, and computational testing was conducted using the open-source CFD code OpenFOAM. For experimental testing, polyurethane-based (rigid) airfoils and silicone-based (flexible) airfoils were constructed using acrylic molds for NACA 0012 and NACA 2412 airfoil profiles. Computer models of the previously-specified airfoils were also created for a computational analysis. Both experimental and computational data were analyzed to examine the critical angles of attack, the lift and drag coefficients, and the occurrence of laminar boundary separation for each airfoil. Moreover, the computational simulations were used to examine the resulting flow fields, in order to provide possible explanations for the aerodynamic performances of each airfoil type. EEC 1659710.

Dynamic Model and Vibration Power Flow of a Rigid-Flexible Coupling and Harmonic-Disturbance Exciting System for Flexible Robotic Manipulator with Elastic Joints

Directory of Open Access Journals (Sweden)

Yufei Liu

2015-01-01

Full Text Available This paper investigates the dynamic of a flexible robotic manipulator (FRM which consists of rigid driving base, flexible links, and flexible joints. With considering the motion fluctuations caused by the coupling effect, such as the motor parameters and mechanism inertias, as harmonic disturbances, the system investigated in this paper remains a parametrically excited system. An elastic restraint model of the FRM with elastic joints (FRMEJ is proposed, which considers the elastic properties of the connecting joints between the flexible arm and the driving base, as well as the harmonic disturbances aroused by the electromechanical coupling effect. As a consequence, the FRMEJ accordingly remains a flexible multibody system which conveys the effects of rigid-flexible couple and electromechanical couple. The Lagrangian function and Hamilton’s principle are used to establish the dynamic model of the FRMEJ. Based on the dynamic model proposed, the vibration power flow is introduced to show the vibration energy distribution. Numerical simulations are conducted to investigate the effect of the joint elasticities and the disturbance excitations, and the influences of the structure parameters and motion parameters on the vibration power flow are studied. The results obtained in this paper contribute to the structure design, motion optimization, and vibration control of FRMs.

Intra-patient comparison of parietal pleural biopsies by rigid forceps, flexible forceps and cryoprobe obtained during medical thoracoscopy: a prospective series of 80 cases with pleural effusion.

Science.gov (United States)

Wurps, H; Schönfeld, N; Bauer, T T; Bock, M; Duve, C; Sauer, R; Mairinger, T; Griff, S

2016-07-07

There is only few data available on the use of cryotechnique during medical thoracoscopy. Medical thoracoscopy was performed in consecutive patients with pleural effusion. Prospectively, biopsies were taken by rigid forceps, flexible forceps and cryoprobe. Specimen size, depth and diagnostic yield were compared. 80 Patients were included. 408 biopsies were taken (205 rigid biopsies, 104 flexible biopsies, 99 cryobiopsies). Mean surface area of rigid biopsies was 22.6 ± 20.4 mm(2) (flexible biopsies: 7.1 ± 9.3 mm(2), cryobiopsies: 14.4 ± 12.8 mm(2)). Rigid biopsies were significantly larger than cryobiopsies (p < 0.001) and flexible biopsies (p < 0.001), crybiopsies were significantly larger than flexible biopsies (p < 0.01). A deep biopsy containing fatty tissue was harvested in 63 % of rigid biopsies (cryobiopsy: 49.5 % flexible biopsy: 39.5 %). In 79/80 cases (98.7 % 95 % CI cannot be calculated) a diagnosis was obtained by rigid biopsy (cryobiopsy: 73/80 cases (91.3 % 95 % CI 86.0 - 96.5 %), flexible biopsy: 74/80 cases (92.5 % 95 % CI 88.6 - 97.4 %)). Diagnostic yield achieved with cryobiopsies was inferior to the yield of rigid biopsies (Difference: 12.7 %), but non-inferior to flexible biopsies (Difference: 6.5 %). Cryobiopsies in medical thoracoscopy are safe with high diagnostic yield, non-inferior to flexible biopsies with increased tissue quantity and quality. Cryotechnique can develop an important role in medical thoracoscopy in the near future when rigid thoracoscopy is not available.

Conditional bistability, a generic cellular mnemonic mechanism for robust and flexible working memory computations.

Science.gov (United States)

Rodriguez, Guillaume; Sarazin, Matthieu; Clemente, Alexandra; Holden, Stephanie; Paz, Jeanne T; Delord, Bruno

2018-04-30

Persistent neural activity, the substrate of working memory, is thought to emerge from synaptic reverberation within recurrent networks. However, reverberation models do not robustly explain fundamental dynamics of persistent activity, including high-spiking irregularity, large intertrial variability, and state transitions. While cellular bistability may contribute to persistent activity, its rigidity appears incompatible with persistent activity labile characteristics. Here, we unravel in a cellular model a form of spike-mediated conditional bistability that is robust, generic and provides a rich repertoire of mnemonic computations. Under asynchronous synaptic inputs of the awakened state, conditional bistability generates spiking/bursting episodes, accounting for the irregularity, variability and state transitions characterizing persistent activity. This mechanism has likely been overlooked because of the sub-threshold input it requires and we predict how to assess it experimentally. Our results suggest a reexamination of the role of intrinsic properties in the collective network dynamics responsible for flexible working memory. SIGNIFICANCE STATEMENT This study unravels a novel form of intrinsic neuronal property, i.e. conditional bistability. We show that, thanks of its conditional character, conditional bistability favors the emergence of flexible and robust forms of persistent activity in PFC neural networks, in opposition to previously studied classical forms of absolute bistability. Specifically, we demonstrate for the first time that conditional bistability 1) is a generic biophysical spike-dependent mechanism of layer V pyramidal neurons in the PFC and that 2) it accounts for essential neurodynamical features for the organisation and flexibility of PFC persistent activity (the large irregularity and intertrial variability of the discharge and its organization under discrete stable states), which remain unexplained in a robust fashion by current models

Rigid two-axis MEMS force plate for measuring cellular traction force

International Nuclear Information System (INIS)

Takahashi, Hidetoshi; Jung, Uijin G; Shimoyama, Isao; Kan, Tetsuo; Tsukagoshi, Takuya; Matsumoto, Kiyoshi

2016-01-01

Cellular traction force is one of the important factors for understanding cell behaviors, such as spreading, migration and differentiation. Cells are known to change their behavior according to the mechanical stiffness of the environment. However, the measurement of cell traction forces on a rigid environment has remained difficult. This paper reports a micro-electromechanical systems (MEMS) force plate that provides a cellular traction force measurement on a rigid substrate. Both the high force sensitivity and high stiffness of the substrate were obtained using piezoresistive sensing elements. The proposed force plate consists of a 70 µ m  ×  15 µ m  ×  5 µ m base as the substrate for cultivating a bovine aortic smooth muscle cell, and the supporting beams with piezoresistors on the sidewall and the surface were used to measure the forces in both the horizontal and vertical directions. The spring constant and force resolution of the fabricated force plate in the horizontal direction were 0.2 N m −1 and less than 0.05 µ N, respectively. The cell traction force was measured, and the traction force increased by approximately 1 µ N over 30 min. These results demonstrate that the proposed force plate is applicable as an effective traction force measurement. (paper)

Dynamic Behavior of Wind Turbine by a Mixed Flexible-Rigid Multi-Body Model

Science.gov (United States)

Wang, Jianhong; Qin, Datong; Ding, Yi

A mixed flexible-rigid multi-body model is presented to study the dynamic behavior of a horizontal axis wind turbine. The special attention is given to flexible body: flexible rotor is modeled by a newly developed blade finite element, support bearing elasticities, variations in the number of teeth in contact as well as contact tooth's elasticities are mainly flexible components in the power train. The couple conditions between different subsystems are established by constraint equations. The wind turbine model is generated by coupling models of rotor, power train and generator with constraint equations together. Based on this model, an eigenproblem analysis is carried out to show the mode shape of rotor and power train at a few natural frequencies. The dynamic responses and contact forces among gears under constant wind speed and fixed pitch angle are analyzed.

Force-controlled robotic assembly processes of rigid and flexible objects methodologies and applications

CERN Document Server

Ghalyan, Ibrahim Fahad Jasim

2016-01-01

This book provides comprehensive and integrated approaches for rigid and flexible object assembly. It presents comparison studies with the available force-guided robotic processes and covers contact-state modeling, scheme control strategies, and position searching algorithms. Further, it includes experimental validations for different assembly situations, including those for the assembly of industrial parts taken from the automotive industry. .

[Effectiveness comparison of flexible fixation and rigid fixation in treatment of ankle pronation-external rotation fractures with distal tibiofibular syndesmosis].

Science.gov (United States)

Li, Yuewei; Zhang, Minghui; Li, Xiaorong; Chen, Xiaoyong; Deng, Jianlong

2017-07-01

To compare the effectiveness of flexible fixation and rigid fixation in the treatment of ankle pronation-external rotation fractures with distal tibiofibular syndesmosis. A retrospective analysis was made on the clinical data of 50 patients with ankle pronation-external rotation fractures and distal tibiofibular syndesmosis treated between January 2013 and December 2015. Suture-button fixation was used in 23 patients (flexible fixation group) and cortical screw fixation in 27 patients (rigid fixation group). There was no significant difference in age, gender, weight, side, fracture type, and time from trauma to surgery between 2 groups ( P >0.05). The operation time, medial clear space (MCS), tibiofibular clear space (TFCS), tibiofibular overlap (TFO), American Orthopaedic Foot and Ankle Society (AOFAS) score, and Foot and Ankle Disability Index (FADI) score were compared between 2 groups. The operation time was (83.0±9.1) minutes in the flexible fixation group and was (79.6±13.1) minutes in the rigid fixation group, showing no significant difference ( t =1.052, P =0.265). All patients achieved healing of incision by first intention. The patients were followed up 12-20 months (mean, 14 months). The X-ray films showed good healing of fracture in 2 groups. There was no screw fracture, delayed union or nounion. The fracture healing time was (12.1±2.5) months in the flexible fixation group and was (11.3±3.2) months in the rigid fixation group, showing no significant difference between 2 groups ( t =1.024, P =0.192). Reduction loss occurred after removal of screw in 2 cases of the rigid fixation group. At last follow-up, there was no significant difference in MCS, TFCS, TFO, AOFAS score and FADI score between 2 groups ( P >0.05). Suture-button fixation has similar effectiveness to screw fixation in ankle function and imaging findings, and flexible fixation has lower risk of reduction loss of distal tibiofibular syndesmosis than rigid fixation.

Comparison of outcomes of tricuspid annuloplasty with 3D-rigid versus flexible prosthetic ring for functional tricuspid regurgitation secondary to rheumatic mitral valve disease.

Science.gov (United States)

Wang, Haiping; Liu, Xiancheng; Wang, Xin; Lv, Zhenqian; Liu, Xiaojun; Xu, Ping

2016-11-01

Annuloplasty bands and rings are widely used for repairing functional tricuspid regurgitation (FTR). However, the question regarding which is the ideal annuloplasty device remains unclear. The aim of this study was to compare the efficacy and mid-term durability of tricuspid ring annuloplasty for FTR secondary to rheumatic mitral valve disease using flexible Cosgrove-Edwards band and the rigid Edwards MC3 ring (Edwards Lifesciences, LLC, Irvine, CA, USA). We retrospectively collected the clinical data of those who underwent mitral valve replacement (MVR) in concomitant with tricuspid ring annuloplasty from 2009 to 2013. The flexible band was used in 46 patients (flexible group), and the 3D rigid ring was used in 60 patients (rigid group). Echocardiographic evaluation of tricuspid function was performed preoperatively and postoperatively. The grade of TR was significantly improved compared to preoperative values in two groups. There was no significant difference regarding postoperative TR grade between the two groups at 1 week and 2-3 months but there was statistical significant difference at postoperative 6-12 months, and 2-3 years. During the follow up period, 25 of 46 patients (54.3%) in flexible group and 22 of 60 patients (30.3%) in rigid group developed recurrent TR. Freedom from recurrent TR in flexible group is significant lower than rigid group in each postoperative follow up period. These findings suggest that 3D rigid ring annuloplasty might be more effective for tricuspid ring annuloplasty in FTR in mid-term postoperative periods when compared to flexible band.

From Wage Rigidities to Labour Market Rigidities: A Turning-Point in Explaining Equilibrium Unemployment?

OpenAIRE

Marco Guerrazzi; Nicola Meccheri

2009-01-01

This paper offers a critical discussion of the concept of labour market rigidity relevant to explaining unemployment. Starting from Keynes’s own view, we discuss how the concept of labour market flexibility has changed over time, involving nominal or real wage flexibility, contract flexibility or labour market institution flexibility. We also provide a critical assessment of the factors that lead the search framework highlighting labour market rigidities (frictions) to challenge the more wide...

Multiscale weighted colored graphs for protein flexibility and rigidity analysis

Science.gov (United States)

Bramer, David; Wei, Guo-Wei

2018-02-01

Protein structural fluctuation, measured by Debye-Waller factors or B-factors, is known to correlate to protein flexibility and function. A variety of methods has been developed for protein Debye-Waller factor prediction and related applications to domain separation, docking pose ranking, entropy calculation, hinge detection, stability analysis, etc. Nevertheless, none of the current methodologies are able to deliver an accuracy of 0.7 in terms of the Pearson correlation coefficients averaged over a large set of proteins. In this work, we introduce a paradigm-shifting geometric graph model, multiscale weighted colored graph (MWCG), to provide a new generation of computational algorithms to significantly change the current status of protein structural fluctuation analysis. Our MWCG model divides a protein graph into multiple subgraphs based on interaction types between graph nodes and represents the protein rigidity by generalized centralities of subgraphs. MWCGs not only predict the B-factors of protein residues but also accurately analyze the flexibility of all atoms in a protein. The MWCG model is validated over a number of protein test sets and compared with many standard methods. An extensive numerical study indicates that the proposed MWCG offers an accuracy of over 0.8 and thus provides perhaps the first reliable method for estimating protein flexibility and B-factors. It also simultaneously predicts all-atom flexibility in a molecule.

Simulating coupled dynamics of a rigid-flexible multibody system and compressible fluid

Science.gov (United States)

Hu, Wei; Tian, Qiang; Hu, HaiYan

2018-04-01

As a subsequent work of previous studies of authors, a new parallel computation approach is proposed to simulate the coupled dynamics of a rigid-flexible multibody system and compressible fluid. In this approach, the smoothed particle hydrodynamics (SPH) method is used to model the compressible fluid, the natural coordinate formulation (NCF) and absolute nodal coordinate formulation (ANCF) are used to model the rigid and flexible bodies, respectively. In order to model the compressible fluid properly and efficiently via SPH method, three measures are taken as follows. The first is to use the Riemann solver to cope with the fluid compressibility, the second is to define virtual particles of SPH to model the dynamic interaction between the fluid and the multibody system, and the third is to impose the boundary conditions of periodical inflow and outflow to reduce the number of SPH particles involved in the computation process. Afterwards, a parallel computation strategy is proposed based on the graphics processing unit (GPU) to detect the neighboring SPH particles and to solve the dynamic equations of SPH particles in order to improve the computation efficiency. Meanwhile, the generalized-alpha algorithm is used to solve the dynamic equations of the multibody system. Finally, four case studies are given to validate the proposed parallel computation approach.

Dynamics of Rigid Bodies and Flexible Beam Structures

DEFF Research Database (Denmark)

Nielsen, Martin Bjerre

of rigid bodies and flexible beam structures with emphasis on the rotational motion. The first part deals with motion in a rotating frame of reference. A novel approach where the equations of motion are formulated in a hybrid state-space in terms of local displacements and global velocities is presented...... quaternion parameters or nine convected base vector components. In both cases, the equations of motion are obtained via Hamilton’s equations by including the kinematic constraints associated with the redundant rotation description by means of Lagrange multipliers. A special feature of the formulation...... of the global components of the position vectors and associated convected base vectors for the element nodes. The kinematics is expressed in a homogeneous quadratic form and the constitutive stiffness is derived from complementary energy of a set of equilibrium modes, each representing a state of constant...

Rigid-flexible coupling dynamics of three-dimensional hub-beams system

International Nuclear Information System (INIS)

Liu Jinyang; Lu Hao

2007-01-01

In the previous research of the coupling dynamics of a hub-beam system, coupling between the rotational motion of hub and the torsion deformation of beam is not taken into account since the system undergoes planar motion. Due to the small longitudinal deformation, coupling between the rotational motion of hub and the longitudinal deformation of beam is also neglected. In this paper, rigid-flexible coupling dynamics is extended to a hub-beams system with three-dimensional large overall motion. Not only coupling between the large overall motion and the bending deformation, but also coupling between the large overall motion and the torsional deformation are taken into account. In case of temperature increase, the longitudinal deformation caused by the thermal expansion is significant, such that coupling between the large overall motion and the longitudinal deformation is also investigated. Combining the characteristics of the hybrid coordinate formulation and the absolute nodal coordinate formulation, the system generalized coordinates include the relative nodal displacement and the slope of each beam element with respect to the body-fixed frame of the hub, and the variables related to the spatial large overall motion of the hub and beams. Based on precise strain-displacement relation, the geometric stiffening effect is taken into account, and the rigid-flexible coupling dynamic equations are derived using velocity variational principle. Finite element method is employed for discretization. Simulation of a hub-beams system is used to show the coupling effect between the large overall motion and the torsional deformation as well as the longitudinal deformation. Furthermore, conservation of energy in case of free motion is shown to verify the formulation

Roll type conducting polymer legs for rigid-flexible thermoelectric generator

Directory of Open Access Journals (Sweden)

Teahoon Park

2017-07-01

Full Text Available A roll-type conducting polymer film was explored as a flexible organic p-type thermoelectric leg using poly(3,4-ethylenedioxythiophene (PEDOT doped with tosylate. The PEDOT films were prepared through solution casting polymerization and rolled up for a roll-type leg. Due to the high flexibility, the roll-type PEDOT leg enabled easy contact to both top and bottom electrodes. Simulation on the dynamic heat transfer and convective cooling for a vertically roosted rod- and roll-type PEDOT leg showed that the temperature difference (ΔT between the hot and cold sides of the leg was much higher in the roll than that of the rod. The PEDOT legs were integrated with n-type Bi2Te3 blocks, to give a 36-couple rigid-flexible thermoelectric generator (RF-TEG. The maximum output voltage from the 36-couple RF-TEG under a ΔT of 7.9 K was determined as 36.7 mV along with a high output power of 115 nW. A wearable RF-TEG was prepared upon the combination of the 36-couple RF-TEG with an arm warmer, to afford an output voltage of 10.6 mV, which was generated constantly and steadily from human wrist heat.

Planar rigid-flexible coupling spacecraft modeling and control considering solar array deployment and joint clearance

Science.gov (United States)

Li, Yuanyuan; Wang, Zilu; Wang, Cong; Huang, Wenhu

2018-01-01

Based on Nodal Coordinate Formulation (NCF) and Absolute Nodal Coordinate Formulation (ANCF), this paper establishes rigid-flexible coupling dynamic model of the spacecraft with large deployable solar arrays and multiple clearance joints to analyze and control the satellite attitude under deployment disturbance. Considering torque spring, close cable loop (CCL) configuration and latch mechanisms, a typical spacecraft composed of a rigid main-body described by NCF and two flexible panels described by ANCF is used as a demonstration case. Nonlinear contact force model and modified Coulomb friction model are selected to establish normal contact force and tangential friction model, respectively. Generalized elastic force are derived and all generalized forces are defined in the NCF-ANCF frame. The Newmark-β method is used to solve system equations of motion. The availability and superiority of the proposed model is verified through comparing with numerical co-simulations of Patran and ADAMS software. The numerical results reveal the effects of panel flexibility, joint clearance and their coupling on satellite attitude. The effects of clearance number, clearance size and clearance stiffness on satellite attitude are investigated. Furthermore, a proportional-differential (PD) attitude controller of spacecraft is designed to discuss the effect of attitude control on the dynamic responses of the whole system.

Liquid crystallinity in flexible and rigid rod polymers

International Nuclear Information System (INIS)

Pickett, Galen T.; Schweizer, Kenneth S.

2000-01-01

We apply an anisotropic version of the polymer reference interaction site model (PRISM) integral equation description of flexible polymers to analyze athermal liquid crystallinity. The polymers are characterized by a statistical segment length, σ o , and by a physical hard-core thickness, d, that prevents the overlap of monomers on different chains. At small segment densities, ρ, the microscopic length scale d is irrelevant (as it must be in the universal semidilute regime), but becomes important in concentrated solutions and melts. Under the influence of the excluded volume interactions alone, the chains undergo a lyotropic, first-order isotropic-nematic transition at a concentration dependent upon the dimensionless ''aspect ratio,'' σ o /d. The transition becomes weaker as d→0, becoming second order, as has been previously shown. We extend the theory to describe the transition of rigid, thin rods, and discuss the evolution of the anisotropic liquid structure in the ordered phase. (c) 2000 American Institute of Physics

Toxicity of pyrolysis gases from some cellular polymers

Science.gov (United States)

Hilado, C. J.; Machado, A. M.

1978-01-01

Various samples of cellular polymers were evaluated for toxicity of pyrolysis gases, using the screening test method developed at the University of San Francisco. The cellular polymer samples included polyimide, polymethacrylimide, polybismaleimide, polyurethane, polyisocyanurate, polyethylene, polychloroprene, polyvinyl chloride, polystyrene, polysiloxane, and polyphosphazene. The cellular polymers exhibited varying levels of toxicity under these test conditions. Among the rigid cellular polymers, times to death were shortest with the imide type foams and longest with polyvinyl chloride and polystyrene. Among the flexible cellular polymers, times to death were shortest with polyimide and polyester, and longest with polychloroprene and polysiloxane. Increased char yield was not necessarily associated with reduced toxicity.

The Role of MreB in Escherichia Coli's Cellular Rigidity

Science.gov (United States)

Shaevitz, Joshua W.

2009-03-01

Bacteria possess homologs of all three classes of eukaryotic cytoskeletal proteins. These filamentous proteins have been shown to localize proteins essential for a number of cell-biological processes in prokaryotes such as cell growth and division. However, to date, there has been no direct evidence that the cytoskeleton in bacteria bears mechanical loads or can generate physical forces than are used by the cell. I will present evidence from combined fluorescence and force microscopy measurements that MreB, an actin homolog, is responsible for half of Escherichia coli's cellular rigidity. These data support an interpretation in which the cytoskeleton, the peptidoglycan cell wall and a large turgor pressure work together to give gram-negative cells their mechanical properties.

Higher order coupling between rigid-body and elastic motion in flexible mechanisms

International Nuclear Information System (INIS)

Esat, I.I.; Ianakiev, A.

1995-01-01

The paper presents an investigation of the influence of the higher order coupling terms between the rigid-body and elastic motion into flexible mechanism dynamics. The configuration of the mechanical system is obtained by using the so called hybrid coordinates. The kinematic description of the mechanism was obtained using the D-H 4 x 4 transformation matrices. The elastic deformation of each point of the mechanism is described by the finite element modeling (FEM) type interpolation scheme. The dynamic model of the flexible mechanism consists due to the hybrid coordinates of two groups of differential equations. The first group describes the manipulator transport motion and the second group describes the vibration. In this paper the authors evaluated the contribution of the coupling terms between the two groups of differential equations and selected only those with high contribution

Laparoscopic - assisted transpyelic rigid nephroscopy - simple alternative when flexible ureteroscopy is not available

Directory of Open Access Journals (Sweden)

Marcos Tobias-Machado

Full Text Available ABSTRACT Introduction: In special situations such as malrotated or ectopic kidneys and UPJ stenosis treatment of renal lithiasis can be challenging. In these rare cases laparoscopy can be indicated. Objective: Describe the Laparoscopic-assisted rigid nephroscopy performed via transpyelic approach and report the feasibility. Patients and methods: We present two cases of caliceal lithiasis. The first is a patient that ESWL and previous percutaneous lithotripsy have failed, with pelvic kidney where laparoscopic dissection of renal pelvis was carried out followed by nephroscopy utilizing the 30 Fr rigid nephroscope to remove the calculus. Ideal angle between the major axis of renal pelvis and the rigid nephroscope to allow success with this technique was 60-90 grades. In the second case, the kidney had a dilated infundibulum. Results: The operative time was 180 minutes for both procedures. No significant blood loss or perioperative complications occurred. The bladder catheter was removed in the postoperative day 1 and Penrose drain on day 2 when patients were discharged. The convalescence was completed after 3 weeks. Patients were stone free without symptons in one year of follow-up. Conclusions: Laparoscopic-assisted rigid nephroscopy performed via tranpyelic approach can be done safely with proper patient selection and adherence to standard laparoscopic surgical principles. This approach is an alternative in cases where flexible endoscope is not available and when standard procedure is unlikely to produce a stone-free status.

Flexible displays, rigid designs?

DEFF Research Database (Denmark)

Hornbæk, Kasper

2015-01-01

Rapid technological progress has enabled a wide range of flexible displays for computing devices, but the user experience--which we're only beginning to understand--will be the key driver for successful designs.......Rapid technological progress has enabled a wide range of flexible displays for computing devices, but the user experience--which we're only beginning to understand--will be the key driver for successful designs....

Performance of a rigid and a flexible adhesive in lumber joints subjected to moisture content changes

Science.gov (United States)

G. P. Krueger; R. F. Blomquist

1964-01-01

Experimental work was undertaken to investigate the extent and magnitude of deterioration that can occur in typical plywood-to-lumber glue joints subjected to stresses resulting from changes in the moisture content of the wood, and to compare the performance of a somewhat flexible or deformable adhesive to that of a rigid adhesive in these joints. Results showed that...

Rigid body formulation in a finite element context with contact interaction

Science.gov (United States)

Refachinho de Campos, Paulo R.; Gay Neto, Alfredo

2018-03-01

The present work proposes a formulation to employ rigid bodies together with flexible bodies in the context of a nonlinear finite element solver, with contact interactions. Inertial contributions due to distribution of mass of a rigid body are fully developed, considering a general pole position associated with a single node, representing a rigid body element. Additionally, a mechanical constraint is proposed to connect a rigid region composed by several nodes, which is useful for linking rigid/flexible bodies in a finite element environment. Rodrigues rotation parameters are used to describe finite rotations, by an updated Lagrangian description. In addition, the contact formulation entitled master-surface to master-surface is employed in conjunction with the rigid body element and flexible bodies, aiming to consider their interaction in a rigid-flexible multibody environment. New surface parameterizations are presented to establish contact pairs, permitting pointwise interaction in a frictional scenario. Numerical examples are provided to show robustness and applicability of the methods.

Translational and rotational diffusion of flexible PEG and rigid dendrimer probes in sodium caseinate dispersions and acid gels

NARCIS (Netherlands)

Salami, S.; Rondeau-Mouro, C.; Barhoum, M.; Duynhoven, van J.P.M.; Mariette, F.

2014-01-01

The dynamics of rigid dendrimer and flexible PEG probes in sodium caseinate dispersions and acid gels, including both translational diffusion and rotational diffusion, were studied by NMR. Above the onset of the close-packing limit (C ~ 10 g/100 g H2O), translational diffusion of the probe depended

Rigid dietary control, flexible dietary control, and intuitive eating: Evidence for their differential relationship to disordered eating and body image concerns.

Science.gov (United States)

Linardon, Jake; Mitchell, Sarah

2017-08-01

This study aimed to replicate and extend from Tylka, Calogero, and Daníelsdóttir (2015) findings by examining the relationship between rigid control, flexible control, and intuitive eating on various indices of disordered eating (i.e., binge eating, disinhibition) and body image concerns (i.e., shape and weight over-evaluation, body checking, and weight-related exercise motivations). This study also examined whether the relationship between intuitive eating and outcomes was mediated by dichotomous thinking and body appreciation. Analysing data from a sample of 372 men and women recruited through the community, this study found that, in contrast to rigid dietary control, intuitive eating uniquely and consistently predicted lower levels of disordered eating and body image concerns. This intuitive eating-disordered eating relationship was mediated by low levels of dichotomous thinking and the intuitive eating-body image relationship was mediated by high levels of body appreciation. Flexible control predicted higher levels of body image concerns and lower levels of disordered eating only when rigid control was accounted for. Findings suggest that until the adaptive properties of flexible control are further elucidated, it may be beneficial to promote intuitive eating within public health approaches to eating disorder prevention. In addition to this, particular emphasis should also be made toward promoting body acceptance and eradicating a dichotomous thinking style around food and eating. Copyright © 2017 Elsevier Ltd. All rights reserved.

Flexible Design for α-Duplex Communications in Multi-Tier Cellular Networks

KAUST Repository

Alammouri, Ahmad; Elsawy, Hesham; Alouini, Mohamed-Slim

2016-01-01

the foreseen FD gains. This paper presents flexible and tractable modeling framework for multi-tier cellular networks with FD BSs and FD/HD UEs. The presented model is based on stochastic geometry and accounts for the intrinsic vulnerability of uplink

Screen printing as a scalable and low-cost approach for rigid and flexible thin-film transistors using separated carbon nanotubes.

Science.gov (United States)

Cao, Xuan; Chen, Haitian; Gu, Xiaofei; Liu, Bilu; Wang, Wenli; Cao, Yu; Wu, Fanqi; Zhou, Chongwu

2014-12-23

Semiconducting single-wall carbon nanotubes are very promising materials in printed electronics due to their excellent mechanical and electrical property, outstanding printability, and great potential for flexible electronics. Nonetheless, developing scalable and low-cost approaches for manufacturing fully printed high-performance single-wall carbon nanotube thin-film transistors remains a major challenge. Here we report that screen printing, which is a simple, scalable, and cost-effective technique, can be used to produce both rigid and flexible thin-film transistors using separated single-wall carbon nanotubes. Our fully printed top-gated nanotube thin-film transistors on rigid and flexible substrates exhibit decent performance, with mobility up to 7.67 cm2 V(-1) s(-1), on/off ratio of 10(4)∼10(5), minimal hysteresis, and low operation voltage (transistors (bent with radius of curvature down to 3 mm) and driving capability for organic light-emitting diode have been demonstrated. Given the high performance of the fully screen-printed single-wall carbon nanotube thin-film transistors, we believe screen printing stands as a low-cost, scalable, and reliable approach to manufacture high-performance nanotube thin-film transistors for application in display electronics. Moreover, this technique may be used to fabricate thin-film transistors based on other materials for large-area flexible macroelectronics, and low-cost display electronics.

Association of grey matter changes with stability and flexibility of prediction in akinetic-rigid Parkinson's disease.

Science.gov (United States)

Trempler, Ima; Binder, Ellen; El-Sourani, Nadiya; Schiffler, Patrick; Tenberge, Jan-Gerd; Schiffer, Anne-Marike; Fink, Gereon R; Schubotz, Ricarda I

2018-06-01

Parkinson's disease (PD), which is caused by degeneration of dopaminergic neurons in the midbrain, results in a heterogeneous clinical picture including cognitive decline. Since the phasic signal of dopamine neurons is proposed to guide learning by signifying mismatches between subjects' expectations and external events, we here investigated whether akinetic-rigid PD patients without mild cognitive impairment exhibit difficulties in dealing with either relevant (requiring flexibility) or irrelevant (requiring stability) prediction errors. Following our previous study on flexibility and stability in prediction (Trempler et al. J Cogn Neurosci 29(2):298-309, 2017), we then assessed whether deficits would correspond with specific structural alterations in dopaminergic regions as well as in inferior frontal cortex, medial prefrontal cortex, and the hippocampus. Twenty-one healthy controls and twenty-one akinetic-rigid PD patients on and off medication performed a task which required to serially predict upcoming items. Switches between predictable sequences had to be indicated via button press, whereas sequence omissions had to be ignored. Independent of the disease, midbrain volume was related to a general response bias to unexpected events, whereas right putamen volume correlated with the ability to discriminate between relevant and irrelevant prediction errors. However, patients compared with healthy participants showed deficits in stabilisation against irrelevant prediction errors, associated with thickness of right inferior frontal gyrus and left medial prefrontal cortex. Flexible updating due to relevant prediction errors was also affected in patients compared with controls and associated with right hippocampus volume. Dopaminergic medication influenced behavioural performance across, but not within the patients. Our exploratory study warrants further research on deficient prediction error processing and its structural correlates as a core of cognitive symptoms

Matrix rigidity regulates cancer cell growth and cellular phenotype.

Directory of Open Access Journals (Sweden)

Robert W Tilghman

2010-09-01

Full Text Available The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness of the microenvironment and how this response varies among cancer cell lines.In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: "rigidity dependent" (those which show an increase in cell growth as extracellular rigidity is increased, and "rigidity independent" (those which grow equally on both soft and stiff substrates. Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug.These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models.

Matrix Rigidity Regulates Cancer Cell Growth and Cellular Phenotype

Science.gov (United States)

Tilghman, Robert W.; Cowan, Catharine R.; Mih, Justin D.; Koryakina, Yulia; Gioeli, Daniel; Slack-Davis, Jill K.; Blackman, Brett R.; Tschumperlin, Daniel J.; Parsons, J. Thomas

2010-01-01

Background The mechanical properties of the extracellular matrix have an important role in cell growth and differentiation. However, it is unclear as to what extent cancer cells respond to changes in the mechanical properties (rigidity/stiffness) of the microenvironment and how this response varies among cancer cell lines. Methodology/Principal Findings In this study we used a recently developed 96-well plate system that arrays extracellular matrix-conjugated polyacrylamide gels that increase in stiffness by at least 50-fold across the plate. This plate was used to determine how changes in the rigidity of the extracellular matrix modulate the biological properties of tumor cells. The cell lines tested fall into one of two categories based on their proliferation on substrates of differing stiffness: “rigidity dependent” (those which show an increase in cell growth as extracellular rigidity is increased), and “rigidity independent” (those which grow equally on both soft and stiff substrates). Cells which grew poorly on soft gels also showed decreased spreading and migration under these conditions. More importantly, seeding the cell lines into the lungs of nude mice revealed that the ability of cells to grow on soft gels in vitro correlated with their ability to grow in a soft tissue environment in vivo. The lung carcinoma line A549 responded to culture on soft gels by expressing the differentiated epithelial marker E-cadherin and decreasing the expression of the mesenchymal transcription factor Slug. Conclusions/Significance These observations suggest that the mechanical properties of the matrix environment play a significant role in regulating the proliferation and the morphological properties of cancer cells. Further, the multiwell format of the soft-plate assay is a useful and effective adjunct to established 3-dimensional cell culture models. PMID:20886123

Comportement comparé de conduites rigides et flexibles ensouillées au voisinage de sols gelés Comparative Behavior of Rigid and Flexible Pipes Buried in the Vicinity of Frozen Ground

Directory of Open Access Journals (Sweden)

Putot C.

2006-11-01

Full Text Available Au cours des dernières années, les activités pétrolières à terre comme en mer, tant en Alaska qu'au Canada, se sont maintenues à un niveau raisonnable. En octobre 1987, le premier champ pétrolier offshore a été mis en exploitation en mer de Beaufort (Endicott. Bien que l'industrie soit principalement dans une phase d'exploration, des besoins vont progressivement se manifester en matière de lignes de collecte et d'injection. La détermination du tracé de conduites en offshore arctique ainsi que leur dimensionnement nécessite la prise en compte de facteurs très spécifiques : le raclage des glaces dérivantes impose une profondeur minimum d'ensouillage, ce qui accroît, malgré l'isolation des conduites, la proportion de chaleur communiquée au pergélisol (ou permafrost en dégel : les tassements différentiels résultant de la variabilité de composition des sols peuvent provoquer des déformations, voire des instabilités des conduites tout à fait inacceptables. Il est assez intuitif de penser que les conduites flexibles accommoderont plus facilement les mouvements de sol que les rigides. L'objet de cet article est de proposer une méthode d'analyse assez souple permettant de jauger facilement cet avantage. In recent years, onshore and offshore petroleum activities, in both Alaska and Canada, have continued on a reasonable level. In October 1987 the first offshore oil field began production in the Beaufort Sea (Endicott. Although the industry is mainly in an exploration phase, needs will steadily appear with regard to gathering and injection line. . The determination to lay flowlines in offshore arctic areas as well as their sizing require that very specific factors be taken into consideration. Scouring by drifting ice requires a minimum depth of burial. Despite the insulation of pipes, this burial increases the proportion of heat communicated to melting permafrost. The differential compaction resulting from the variability of

A new method using insert-based systems (IBS) to improve cell behavior study on flexible and rigid biomaterials

OpenAIRE

Grenade, Charlotte; Moniotte, Nicolas; Rompen, Eric; Vanheusden, Alain; Mainjot, Amélie; De Pauw-Gillet, Marie-Claire

2016-01-01

In vitro studies about biomaterials biological properties are essential screening tests. Yet cell cultures encounter difficulties related to cell retention on material surface or to the observation of both faces of permeable materials. The objective of the present study was to develop a reliable in vitro method to study cell behavior on rigid and flexible/permeable biomaterials elaborating two specific insert-based systems (IBS-R and IBS-F respectively). IBS-R was designed as a specific cylin...

Numerical investigation of optimal yaw misalignment and collective pitch angle for load imbalance reduction of rigid and flexible HAWT blades under sheared inflow

International Nuclear Information System (INIS)

Jeong, Min-Soo; Cha, Myung-Chan; Kim, Sang-Woo; Lee, In

2015-01-01

Wind shear can strongly influence the cyclic loading on horizontal axis wind turbine blades. These load fluctuation causes a variation of power output and introduces fatigue load. Thus, individual pitch controllers have been developed that are focused on the load alleviations, however, comes at a price of actuator requirements for control. Moreover, these controllers are unable to apply to already existing wind turbines with active yaw and collective pitch control system. Therefore, the investigations for minimizing load imbalance through the adjustments of yaw misalignment and collective pitch angle are implemented for the rigid and flexible blades under the sheared inflow. By applying the optimization process based on a sequential quadratic programming approach, the optimal yaw and pitch angle can be estimated. Then, the numerical simulations for predicting the performance are performed. The results showed that the fluctuation range of the root flapwise bending moment for the rigid blades can be reduced by 84.5%, whereas the vibratory bending moment for the flexible blades can be reduced by up to approximately 82.4% in the best case. Therefore, the magnitudes of load imbalance can be minimized by the adjustment of the optimal yaw misalignment and collective pitch angle without any power loss. - Highlights: • We propose a novel method for the reduction of load imbalance under sheared inflow. • We estimate optimal yaw misalignment and collective pitch angle through optimization. • Numerical results of performance are predicted for rigid and flexible blades. • By applying optimal angles, load variations are reduced without any power loss

Rigid versus Flexible Ligands on Carbon Nanotubes for the Enhanced Sensitivity of Cobalt Ions

Energy Technology Data Exchange (ETDEWEB)

Gou, Pingping; Kraut, Nadine D.; Feigel, Ian Matthew; Star, Alexander

2013-02-26

Carbon nanotubes have shown great promise in the fabrication of ultra-compact and highly sensitive chemical and biological sensors. Additional chemical functionalization schemes can controllably improve selectivity of the carbon nanotube-based sensors; however the exact transduction mechanism is still under debate. In this article we detail the synthesis and selective response of single-walled carbon nanotubes (SWNTs) functionalized with polyazomethine (PAM) polymer towards the application of a specific trace metal ion detector. The response of the polymer system was compared to shape persistent macrocycle (MAC) comprised of identical ion coordination ligands. While ion detection with rigid MAC/SWNT chemiresistor was comparable to bare SWNT, flexible PAM offers significant SWNT signal amplification, allowing for picomolar detection of Co{sup 2+} ions with both selectivity and a fast response. We hypothesized that rearrangement of the flexible PAM on the SWNT network is a sensing mechanism which allows for ultrasensitive detection of metal ions. The electron transfer and polymer rearrangement on the SWNT was studied by a combination of optical spectroscopy and electrical measurements - ultimately allowing for a better understanding of fundamental mechanisms that prompt device response.

The diagnostic role of thoracoscope in undiagnosed pleural effusion: Rigid versus flexible

Directory of Open Access Journals (Sweden)

Mostafa Mahmoud Abdel Mageid Shaheen

2014-07-01

Conclusions: Thoracoscopy using either fibreoptic bronchoscope or rigid thoracoscope is safe and well tolerated. Rigid thoracoscope has a higher diagnostic yield, easier handling, better orientation and is less expensive. Nevertheless, fibreoptic bronchoscope is an alternative technique if rigid thoracoscopy is not available.

Large-amplitude and narrow-band vibration phenomenon of a foursquare fix-supported flexible plate in a rigid narrow channel

Energy Technology Data Exchange (ETDEWEB)

Liu Lifang, E-mail: liu_lifang1106@yahoo.cn [School of Nuclear Science and Engineering, North China Electric Power University, Zhuxinzhuang, Dewai, Beijing 102206 (China); Lu Daogang, E-mail: ludaogang@ncepu.edu.cn [School of Nuclear Science and Engineering, North China Electric Power University, Zhuxinzhuang, Dewai, Beijing 102206 (China); Li Yang, E-mail: qinxiuyi@sina.com [School of Nuclear Science and Engineering, North China Electric Power University, Zhuxinzhuang, Dewai, Beijing 102206 (China); Zhang Pan, E-mail: zhangpan@ncepu.edu.cn [School of Nuclear Science and Engineering, North China Electric Power University, Zhuxinzhuang, Dewai, Beijing 102206 (China); Niu Fenglei, E-mail: niufenglei@ncepu.edu.cn [School of Nuclear Science and Engineering, North China Electric Power University, Zhuxinzhuang, Dewai, Beijing 102206 (China)

2011-08-15

Highlights: > FIV of a foursquare fix-supported flexible plate exposed to axial flow was studied. > Special designed test section and advanced measuring equipments were adopted. > The narrow-band vibration phenomenon with large amplitude was observed. > Line of plate's vibration amplitude and flow rate was investigated. > The phenomenon and the measurement error were analyzed. - Abstract: An experiment was performed to analyze the flow-induced vibration behavior of a foursquare fix-supported flexible plate exposed to the axial flow within a rigid narrow channel. The large-amplitude and narrow-band vibration phenomenon was observed in the experiment when the flow velocity varied with the range of 0-5 m/s. The occurring condition and some characteristics of the large-amplitude and narrow-band vibrations were investigated.

Fluidelastic instability of a flexible tube in a rigid normal square array subjected to uniform two-phase cross-flows

International Nuclear Information System (INIS)

Axisa, F.; Villard, B.; Antunes, J.

1989-01-01

During the last decade several researchers, investigated fluidelastic instability in tube arrays by restricting the problem to a single degree of freedom system. This is a very attractive idea because of obvious theoretical and experimental simplifications. Nevertheless, it has still to be clarified how far such results can be applied to fully flexible arrays. This paper is presenting a few experimental data obtained on a rigid normal square array subjected to uniform air-water cross flows, at various homogeneous void fractions α H from O to 1. Fluidelastic instability was clearly observed in air and in water. However instability was progressively vanishing in two-phase flow, when α H was increased. Such a result is contrasting with those obtained on fully flexible arrays

Rigid aromatic linking moiety in cationic lipids for enhanced gene transfection efficiency.

Science.gov (United States)

Wang, Bing; Zhao, Rui-Mo; Zhang, Ji; Liu, Yan-Hong; Huang, Zheng; Yu, Qing-Ying; Yu, Xiao-Qi

2017-08-18

Although numerous cationic lipids have been developed as non-viral gene vectors, the structure-activity relationship (SAR) of these materials remains unclear and needs further investigation. In this work, a series of lysine-derived cationic lipids containing linkages with different rigidity were designed and synthesized. SAR studies showed that lipids with rigid aromatic linkage could promote the formation of tight liposomes and enhance DNA condensation, which is essential for the gene delivery process. These lipids could give much higher transfection efficiency than those containing more flexible aliphatic linkage in various cell lines. Moreover, the rigid aromatic linkage also affords the material higher serum tolerance ability. Flow cytometry assay revealed that the target lipids have good cellular uptake, while confocal microscopy observation showed weaker endosome escape than Lipofectamine 2000. To solve such problem and further increase the transfection efficiency, some lysosomotropic reagents were used to improve the endosome escape of lipoplex. As expected, higher transfection efficiency than Lipofectamine 2000 could be obtained via this strategy. Cytotoxicity assay showed that these lipids have lower toxicity in various cell lines than Lipofectamine 2000, suggesting their potential for further application. This work demonstrates that a rigid aromatic linkage might distinctly improve the gene transfection abilities of cationic lipids and affords information to construct safe and efficient gene vector towards practical application. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

A new method using insert-based systems (IBS) to improve cell behavior study on flexible and rigid biomaterials.

Science.gov (United States)

Grenade, Charlotte; Moniotte, Nicolas; Rompen, Eric; Vanheusden, Alain; Mainjot, Amélie; De Pauw-Gillet, Marie-Claire

2016-12-01

In vitro studies about biomaterials biological properties are essential screening tests. Yet cell cultures encounter difficulties related to cell retention on material surface or to the observation of both faces of permeable materials. The objective of the present study was to develop a reliable in vitro method to study cell behavior on rigid and flexible/permeable biomaterials elaborating two specific insert-based systems (IBS-R and IBS-F respectively). IBS-R was designed as a specific cylindrical polytetrafluoroethylene (PTFE) system to evaluate attachment, proliferation and morphology of human gingival fibroblasts (HGFs) on grade V titanium and lithium disilicate glass-ceramic discs characteristics of dental prostheses. The number of cells, their covering on discs and their morphology were determined from MTS assays and microscopic fluorescent images after 24, 48 and 72 h. IBS-F was developed as a two components system to study HGFs behavior on guided bone regeneration polyester membranes. The viability and the membrane barrier effect were evaluated by metabolic MTS assays and by scanning electron microscopy. IBS-R and IBS-F were shown to promote (1) easy and rapid handling; (2) cell retention on biomaterial surface; (3) accurate evaluation of the cellular proliferation, spreading and viability; (4) use of non-toxic material. Moreover IBS-F allowed the study of the cell migration through degradable membranes, with an access to both faces of the biomaterial and to the bottom of culture wells for medium changing.

Structural modulation and luminescent properties of four Cd{sup II} coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

Energy Technology Data Exchange (ETDEWEB)

Xia, Liang; Dong, Wen-Wen, E-mail: dongww1@126.com; Ye, Xiao; Zhao, Jun; Li, Dong-Sheng, E-mail: lidongsheng1@126.com

2016-10-15

To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d{sup 10} coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt){sub 2}]{sub n} (1), [Cd{sub 3}(4-pzpt){sub 2}(suc){sub 2}]{sub n} (2), [Cd{sub 2}(4-Hpzpt)(nbc){sub 2}(H{sub 2}O)]{sub n} (3) and ([Cd{sub 2}(4-pzpt){sub 2}(tfbdc)(H{sub 2}O){sub 4}]·H{sub 2}O){sub n} (4) (H{sub 2}suc=1,2-ethanedicarboxylic acid, H{sub 2}nbc=hthalene-1,4-dicarboxylic acid, H{sub 2}tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 4{sup 4}-sql layer, which is extended to a 3D network via nonclassical C–H{sup …}N hydrogen bonds. Compound 2 possesses a 6-connected pcu-4{sup 12}0.6{sup 3} net composed of trinuclear Cd{sup II}-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·5{sup 3}·7{sup 2})(5{sup 3}·6·7·9)(4{sup 2}·5{sup 5}·6·7{sup 2}). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 6{sup 3}-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O–H{sup …}N and O–H{sup …}O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated. - Graphical abstract: Four new Cd{sup II} coordination architectures constructed from the primary ligand 4-Hpzpt and flexible/rigid dicarboxylate coligands. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. And more, the thermal stability and luminescence are discussed. - Highlights: �

Rigid-only versus combined rigid and flexible percutaneous nephrolithotomy (PNL)

DEFF Research Database (Denmark)

Cracco, Cecilia M; Knoll, Thomas; Liatsikos, Evangelos N

2017-01-01

/or flexible ureteroscopy) for the treatment of large and/or complex upper urinary tract calculi, with regard to efficacy and safety. EVIDENCE ACQUISITION: Ovid MedLine (R), PubMed, Scopus and Web of Science databases were searched in August 2016 to identify relevant studies. Article selection was performed...

Office flexible cystoscopy.

Science.gov (United States)

Kavoussi, L R; Clayman, R V

1988-11-01

Since the development of the first purpose-built flexible cystoscope in 1984, flexible cystoscopy has become an accepted diagnostic and therapeutic modality. Indeed, it is estimated that more than 10 per cent of practicing urologists are already familiar with this technology. The flexible cystoscope has markedly extended the urologist's ability to examine the bladder, and it has become a valuable adjunct to the rigid cystoscope. Although the operation of this instrument is vastly different from that of its rigid counterpart, with practice, the technique can be learned. After experience is obtained with diagnostic flexible cystoscopy, the urologist will likely prefer this new instrument for bladder inspection, as it provides for a more thorough yet less morbid and less expensive examination. In the future, the development of improved and smaller instrumentation will further extend the therapeutic indications for flexible cystoscopy. Indeed, advances in laser technology are already providing the urologist with 300- to 600-micron (0.9 to 1.8F) flexible probes capable of incision (KTP laser), fulguration (Nd:YAG laser), and stone disintegration (tunable dye laser). Lastly, the skills obtained in using the flexible cystoscope are all readily applicable to the development of dexterity with the already available flexible nephroscope and the more recently developed flexible ureteroscope.

Translational and rotational diffusion of flexible PEG and rigid dendrimer probes in sodium caseinate dispersions and acid gels.

Science.gov (United States)

Salami, Souad; Rondeau-Mouro, Corinne; Barhoum, Myriam; van Duynhoven, John; Mariette, François

2014-09-01

The dynamics of rigid dendrimer and flexible PEG probes in sodium caseinate dispersions and acid gels, including both translational diffusion and rotational diffusion, were studied by NMR. Above the onset of the close-packing limit (C ∼ 10 g/100 g H2 O), translational diffusion of the probe depended on its flexibility and on the fluctuations of the matrix chains. The PEG probe diffused more rapidly than the spherical dendrimer probe of corresponding hydrodynamic radius. The greater conformational flexibility of PEG facilitated its motion through the crowded casein matrix. Rotational diffusion was, however, substantially less hindered than the translational diffusion and depended on the local protein-probe friction which became high when the casein concentration increased. The coagulation of the matrix led to the formation of large voids, which resulted in an increase in the translational diffusion of the probes, whereas the rotational diffusion of the probes was retarded in the gel, which could be attributed to the immobilized environment surrounding the probe. Quantitative information from PFG-NMR and SEM micrographs have been combined for characterizing microstructural details in SC acid gels. © 2014 Wiley Periodicals, Inc.

Calculations of critical micelle concentration by dissipative particle dynamics simulations: the role of chain rigidity.

Science.gov (United States)

Lee, Ming-Tsung; Vishnyakov, Aleksey; Neimark, Alexander V

2013-09-05

Micelle formation in surfactant solutions is a self-assembly process governed by complex interplay of solvent-mediated interactions between hydrophilic and hydrophobic groups, which are commonly called heads and tails. However, the head-tail repulsion is not the only factor affecting the micelle formation. For the first time, we present a systematic study of the effect of chain rigidity on critical micelle concentration and micelle size, which is performed with the dissipative particle dynamics simulation method. Rigidity of the coarse-grained surfactant molecule was controlled by the harmonic bonds set between the second-neighbor beads. Compared to flexible molecules with the nearest-neighbor bonds being the only type of bonded interactions, rigid molecules exhibited a lower critical micelle concentration and formed larger and better-defined micelles. By varying the strength of head-tail repulsion and the chain rigidity, we constructed two-dimensional diagrams presenting how the critical micelle concentration and aggregation number depend on these parameters. We found that the solutions of flexible and rigid molecules that exhibited approximately the same critical micelle concentration could differ substantially in the micelle size and shape depending on the chain rigidity. With the increase of surfactant concentration, primary micelles of more rigid molecules were found less keen to agglomeration and formation of nonspherical aggregates characteristic of flexible molecules.

Identifying Floppy and Rigid Regions in Proteins

Science.gov (United States)

Jacobs, D. J.; Thorpe, M. F.; Kuhn, L. A.

1998-03-01

In proteins it is possible to separate hard covalent forces involving bond lengths and bond angles from other weak forces. We model the microstructure of the protein as a generic bar-joint truss framework, where the hard covalent forces and strong hydrogen bonds are regarded as rigid bar constraints. We study the mechanical stability of proteins using FIRST (Floppy Inclusions and Rigid Substructure Topography) based on a recently developed combinatorial constraint counting algorithm (the 3D Pebble Game), which is a generalization of the 2D pebble game (D. J. Jacobs and M. F. Thorpe, ``Generic Rigidity: The Pebble Game'', Phys. Rev. Lett.) 75, 4051-4054 (1995) for the special class of bond-bending networks (D. J. Jacobs, "Generic Rigidity in Three Dimensional Bond-bending Networks", Preprint Aug (1997)). This approach is useful in identifying rigid motifs and flexible linkages in proteins, and thereby determines the essential degrees of freedom. We will show some preliminary results from the FIRST analysis on the myohemerythrin and lyozyme proteins.

Flexible Foam Model.

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Michael K.; Lu, Wei-Yang; Werner, Brian T.; Scherzinger, William M.; Lo, Chi S.

2018-03-01

Experiments were performed to characterize the mechanical response of a 15 pcf flexible polyurethane foam to large deformation at different strain rates and temperatures. Results from these experiments indicated that at room temperature, flexible polyurethane foams exhibit significant nonlinear elastic deformation and nearly return to their original undeformed shape when unloaded. However, when these foams are cooled to temperatures below their glass transition temperature of approximately -35 o C, they behave like rigid polyurethane foams and exhibit significant permanent deformation when compressed. Thus, a new model which captures this dramatic change in behavior with temperature was developed and implemented into SIERRA with the name Flex_Foam to describe the mechanical response of both flexible and rigid foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments. Next, development of the Flex Foam model for flexible polyurethane and other flexible foams is described. Selection of material parameters are discussed and finite element simulations with the new Flex Foam model are compared with experimental results to show behavior that can be captured with this new model.

Effect of Link Flexibility on tip position of a single link robotic arm

Science.gov (United States)

Madhusudan Raju, E.; Siva Rama Krishna, L.; Mouli, Y. Sharath Chandra; Nageswara Rao, V.

2015-12-01

The flexible robots are widely used in space applications due to their quick response, lower energy consumption, lower overall mass and operation at high speed compared to conventional industrial rigid link robots. These robots are inherently flexible, so that the kinematics of flexible robots can't be solved with rigid body assumptions. The flexibility in links and joints affects end-point positioning accuracy of the robot. It is important to model the link kinematics with precision which in turn simplifies modelling of dynamics of flexible robots. The main objective of this paper is to evaluate the effect of link flexibility on a tip position of a single link robotic arm for a given motion. The joint is assumed to be rigid and only link flexibility is considered. The kinematics of flexible link problem is evaluated by Assumed Modes Method (AMM) using MAT LAB Programming. To evaluate the effect of link flexibility (with and without payload) of robotic arm, the normalized tip deviation is found for flexible link with respect to a rigid link. Finally, the limiting inertia for payload mass is found if the allowable tip deviation is 5%.

Mitral stenosis due to pannus overgrowth after rigid ring annuloplasty.

Science.gov (United States)

Oda, Takeshi; Kato, Seiya; Tayama, Eiki; Fukunaga, Shuji; Akashi, Hidetoshi; Aoyagi, Shigeaki

2010-03-01

Although mitral stenosis (MS) due to pannus overgrowth after mitral valve repair for rheumatic mitral regurgitation (MR) is not uncommon, it is extremely rare in relation to non-rheumatic mitral regurgitation. Whilst it has been suggested that the rigid annuloplasty ring induces pannus overgrowth in the same manner as the flexible ring, to date only in cases using the flexible ring has pannus formation been confirmed by a pathological examination after redo surgery. The case is described of a woman who had undergone mitral valve repair using a 28 mm rigid ring three years previously because of non-rheumatic MR, and subsequently suffered from MS due to pannus formation over the annuloplasty ring. To the present authors' knowledge, this is the first report of MS due to pannus formation after mitral valve repair using a rigid annuloplasty ring to treat non-rheumatic MR documented at reoperation.

Indirect Inverse Substructuring Method for Multibody Product Transport System with Rigid and Flexible Coupling

Directory of Open Access Journals (Sweden)

Jun Wang

2015-01-01

Full Text Available The aim of this paper is to develop a new frequency response function- (FRF- based indirect inverse substructuring method without measuring system-level FRFs in the coupling DOFs for the analysis of the dynamic characteristics of a three-substructure coupled product transport system with rigid and flexible coupling. By enforcing the dynamic equilibrium conditions at the coupling coordinates and the displacement compatibility conditions, a closed-form analytical solution to inverse substructuring analysis of multisubstructure coupled product transport system is derived based on the relationship of easy-to-monitor component-level FRFs and the system-level FRFs at the coupling coordinates. The proposed method is validated by a lumped mass-spring-damper model, and the predicted coupling dynamic stiffness is compared with the direct computation, showing exact agreement. The method developed offers an approach to predict the unknown coupling dynamic stiffness from measured FRFs purely. The suggested method may help to obtain the main controlling factors and contributions from the various structure-borne paths for product transport system.

A High Performance Computing Approach to the Simulation of Fluid Solid Interaction Problems with Rigid and Flexible Components (Open Access Publisher’s Version)

Science.gov (United States)

2014-08-01

enhances flow incompressibility [20]. This correction takes into account the velocity of neighboring markers through a mean velocity evaluated within...interactions between individual markers; i.e., the right hand side of Eqs. (7) and (8), are accounted for, the total rigid body force and torque due to the...coordinate formulation. In: Proceedings of the ASME 2005 IDETC/ CIE . Orlando, Florida (2005). [35] Shabana A.: Flexible multibody dynamics: Review of

Bio-Inspired Flexible Cellular Actuating Systems

Science.gov (United States)

2013-11-21

S. Hong, “Robust adaptive boundary control of a flexible marine riser with vessel dynamics,” Automatica, vol. 47, pp. 722–732, 2011. [22] D. H...conditionally accepted. [6] W. He, S. S. Ge, B. V. E. How, Y. S. Choo, and K. S. Hong, “Robust adaptive boundary control of a flexible marine riser ... flexible robotic actuators, often represented by a distributed parameter system or a partial differential equation. We establish a model-guided

The Role of Rigidity in Adaptive and Maladaptive Families Assessed by FACES IV: The Points of View of Adolescents.

Science.gov (United States)

Everri, Marina; Mancini, Tiziana; Fruggeri, Laura

Previous studies using Olson's Circumplex Model and FACES IV, the self-report assessing family functioning, did not clarify the role of rigidity, a dimension of this model. Rigidity emerged as ambiguous: it was considered either as a functional or as a dysfunctional dimension. Building upon the results of previous studies, we provided a contribution intended to disambiguate the role of rigidity considering adolescents' perceptions and using a non-a priori classification analysis. 320 Italian adolescents (13-21 years) participated in this study and responded to a questionnaire containing scales of the study variables. A latent class analysis was performed to identify the association of rigidity with the other dimensions of Olson's model and with indicators of adaptive family functioning in adolescence: parental monitoring and family satisfaction. We found six clusters corresponding to family typologies and having different levels of functioning. Rigidity emerged as adaptive in the typologies named rigidly balanced and flexibly oscillating; it was associated with positive dimensions of family functioning, i.e. flexibility, cohesion, parental monitoring, and high levels of family satisfaction. Differently, when rigidity was associated with disengagement, low cohesion and flexibility, and lack of parental supervision, emerged as maladaptive. This was the case of two typologies: the rigidly disengaged and the chaotically disengaged. Adolescents of these families reported the lowest levels of satisfaction. In the two last typologies, the flexibly chaotic and the cohesively disorganized, rigidity indicated a mid-range functionality as these families were characterized by emotional connectedness but lack of containment. Clinical implications are discussed.

Thermostability in rubredoxin and its relationship to mechanical rigidity

Science.gov (United States)

Rader, A. J.

2010-03-01

The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors.

Thermostability in rubredoxin and its relationship to mechanical rigidity

International Nuclear Information System (INIS)

Rader, A J

2010-01-01

The source of increased stability in proteins from organisms that thrive in extreme thermal environments is not well understood. Previous experimental and theoretical studies have suggested many different features possibly responsible for such thermostability. Many of these thermostabilizing mechanisms can be accounted for in terms of structural rigidity. Thus a plausible hypothesis accounting for this remarkable stability in thermophilic enzymes states that these enzymes have enhanced conformational rigidity at temperatures below their native, functioning temperature. Experimental evidence exists to both support and contradict this supposition. We computationally investigate the relationship between thermostability and rigidity using rubredoxin as a case study. The mechanical rigidity is calculated using atomic models of homologous rubredoxin structures from the hyperthermophile Pyrococcus furiosus and mesophile Clostridium pasteurianum using the FIRST software. A global increase in structural rigidity (equivalently a decrease in flexibility) corresponds to an increase in thermostability. Locally, rigidity differences (between mesophilic and thermophilic structures) agree with differences in protection factors

Risk of perforation using rigid oesophagoscopy in the distal part of oesophagus

DEFF Research Database (Denmark)

Wennervaldt, Kasper; Melchiors, Jacob

2012-01-01

Endoscopic examination and treatment of disorders in the oesophagus have been a part of the otolaryngological specialty since the introduction of the rigid endoscope. Today, both flexible and rigid oesophagoscopy (RO) is used to that end. The aim of this study was to evaluate the safety of the RO....

Tile-based rigidization surface parametric design study

Science.gov (United States)

Giner Munoz, Laura; Luntz, Jonathan; Brei, Diann; Kim, Wonhee

2018-03-01

Inflatable technologies have proven useful in consumer goods as well as in more recent applications including civil structures, aerospace, medical, and robotics. However, inflatable technologies are typically lacking in their ability to provide rigid structural support. Particle jamming improves upon this by providing structures which are normally flexible and moldable but become rigid when air is removed. Because these are based on an airtight bladder filled with loose particles, they always occupy the full volume of its rigid state, even when not rigidized. More recent developments in layer jamming have created thin, compact rigidizing surfaces replacing the loose volume of particles with thinly layered surface materials. Work in this area has been applied to several specific applications with positive results but have not generally provided the broader understanding of the rigidization performance as a function of design parameters required for directly adapting layer rigidization technology to other applications. This paper presents a parametric design study of a new layer jamming vacuum rigidization architecture: tile-based vacuum rigidization. This form of rigidization is based on layers of tiles contained within a thin vacuum bladder which can be bent, rolled, or otherwise compactly stowed, but when deployed flat, can be vacuumed and form a large, flat, rigid plate capable of supporting large forces both localized and distributed over the surface. The general architecture and operation detailing rigidization and compliance mechanisms is introduced. To quantitatively characterize the rigidization behavior, prototypes rigidization surfaces are fabricated and an experimental technique is developed based on a 3-point bending test. Performance evaluation metrics are developed to describe the stiffness, load-bearing capacity, and internal slippage of tested prototypes. A set of experimental parametric studies are performed to better understand the impact of

Mental set and creative thought in social conflict : Threat rigidity versus motivated focus

NARCIS (Netherlands)

De Dreu, Carsten K. W.; Nijstad, Bernard A.

According to the traditional threat-rigidity reasoning, people in social conflict will be less flexible, less creative, more narrow-minded, and more rigid in their thinking when they adopt a conflict rather than a cooperation mental set. The authors propose and test an alternative, motivated focus

Dynamics of parallel robots from rigid bodies to flexible elements

CERN Document Server

Briot, Sébastien

2015-01-01

This book starts with a short recapitulation on basic concepts, common to any types of robots (serial, tree structure, parallel, etc.), that are also necessary for computation of the dynamic models of parallel robots. Then, as dynamics requires the use of geometry and kinematics, the general equations of geometric and kinematic models of parallel robots are given. After, it is explained that parallel robot dynamic models can be obtained by decomposing the real robot into two virtual systems: a tree-structure robot (equivalent to the robot legs for which all joints would be actuated) plus a free body corresponding to the platform. Thus, the dynamics of rigid tree-structure robots is analyzed and algorithms to obtain their dynamic models in the most compact form are given. The dynamic model of the real rigid parallel robot is obtained by closing the loops through the use of the Lagrange multipliers. The problem of the dynamic model degeneracy near singularities is treated and optimal trajectory planning for cro...

How does symmetry impact the flexibility of proteins?

Science.gov (United States)

Schulze, Bernd; Sljoka, Adnan; Whiteley, Walter

2014-02-13

It is well known that (i) the flexibility and rigidity of proteins are central to their function, (ii) a number of oligomers with several copies of individual protein chains assemble with symmetry in the native state and (iii) added symmetry sometimes leads to added flexibility in structures. We observe that the most common symmetry classes of protein oligomers are also the symmetry classes that lead to increased flexibility in certain three-dimensional structures-and investigate the possible significance of this coincidence. This builds on the well-developed theory of generic rigidity of body-bar frameworks, which permits an analysis of the rigidity and flexibility of molecular structures such as proteins via fast combinatorial algorithms. In particular, we outline some very simple counting rules and possible algorithmic extensions that allow us to predict continuous symmetry-preserving motions in body-bar frameworks that possess non-trivial point-group symmetry. For simplicity, we focus on dimers, which typically assemble with twofold rotational axes, and often have allosteric function that requires motions to link distant sites on the two protein chains.

Natural flexible dermal armor.

Science.gov (United States)

Yang, Wen; Chen, Irene H; Gludovatz, Bernd; Zimmermann, Elizabeth A; Ritchie, Robert O; Meyers, Marc A

2013-01-04

Fish, reptiles, and mammals can possess flexible dermal armor for protection. Here we seek to find the means by which Nature derives its protection by examining the scales from several fish (Atractosteus spatula, Arapaima gigas, Polypterus senegalus, Morone saxatilis, Cyprinius carpio), and osteoderms from armadillos, alligators, and leatherback turtles. Dermal armor has clearly been developed by convergent evolution in these different species. In general, it has a hierarchical structure with collagen fibers joining more rigid units (scales or osteoderms), thereby increasing flexibility without significantly sacrificing strength, in contrast to rigid monolithic mineral composites. These dermal structures are also multifunctional, with hydrodynamic drag (in fish), coloration for camouflage or intraspecies recognition, temperature and fluid regulation being other important functions. The understanding of such flexible dermal armor is important as it may provide a basis for new synthetic, yet bioinspired, armor materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Granular flow down a flexible inclined plane

Directory of Open Access Journals (Sweden)

Sonar Prasad

2017-01-01

Full Text Available Discrete and continuous systems are commonly studied individually, but seldom together. Indeed, granular flows are typically studied through flows over a rigid base. Here, we investigate the behaviour of granular flows over an inclined, flexible base. The flexible base is modeled as a rigid platform mounted on springs and has one degree of freedom. The base vibrations are introduced by the flow. We simulate such flows through a discrete element method and compare with experiments. We find that a flexible base increased the upper limit of the inclination up to which a steady flow is possible by at least 3 degrees. This stabilized zone may have important implications in applications such as conveyor belts and chutes.

Inspection and monitoring techniques for un-bonded flexible risers and pipelines

OpenAIRE

Simonsen, Anders

2014-01-01

Master's thesis in Offshore technology Un-bonded flexible pipelines and risers are an alternative to conventional rigid steel pipes. The use of flexible pipes has enabled development of several offshore fields that seemed unfeasible with the use of rigid pipes due to extensive seabed preparation and large dynamic motions. The lack of knowledge and integrity management tools for flexible pipes is a limiting factor and cause pipelines and risers to be replaced before their service life has ...

Specificity and affinity quantification of flexible recognition from underlying energy landscape topography.

Directory of Open Access Journals (Sweden)

Xiakun Chu

2014-08-01

Full Text Available Flexibility in biomolecular recognition is essential and critical for many cellular activities. Flexible recognition often leads to moderate affinity but high specificity, in contradiction with the conventional wisdom that high affinity and high specificity are coupled. Furthermore, quantitative understanding of the role of flexibility in biomolecular recognition is still challenging. Here, we meet the challenge by quantifying the intrinsic biomolecular recognition energy landscapes with and without flexibility through the underlying density of states. We quantified the thermodynamic intrinsic specificity by the topography of the intrinsic binding energy landscape and the kinetic specificity by association rate. We found that the thermodynamic and kinetic specificity are strongly correlated. Furthermore, we found that flexibility decreases binding affinity on one hand, but increases binding specificity on the other hand, and the decreasing or increasing proportion of affinity and specificity are strongly correlated with the degree of flexibility. This shows more (less flexibility leads to weaker (stronger coupling between affinity and specificity. Our work provides a theoretical foundation and quantitative explanation of the previous qualitative studies on the relationship among flexibility, affinity and specificity. In addition, we found that the folding energy landscapes are more funneled with binding, indicating that binding helps folding during the recognition. Finally, we demonstrated that the whole binding-folding energy landscapes can be integrated by the rigid binding and isolated folding energy landscapes under weak flexibility. Our results provide a novel way to quantify the affinity and specificity in flexible biomolecular recognition.

Durable bistable auxetics made of rigid solids

Science.gov (United States)

Shang, Xiao; Liu, Lu; Rafsanjani, Ahmad; Pasini, Damiano

2018-02-01

Bistable Auxetic Metamaterials (BAMs) are a class of monolithic perforated periodic structures with negative Poisson's ratio. Under tension, a BAM can expand and reach a second state of equilibrium through a globally large shape transformation that is ensured by the flexibility of its elastomeric base material. However, if made from a rigid polymer, or metal, BAM ceases to function due to the inevitable rupture of its ligaments. The goal of this work is to extend the unique functionality of the original kirigami architecture of BAM to a rigid solid base material. We use experiments and numerical simulations to assess performance, bistability and durability of rigid BAMs at 10,000 cycles. Geometric maps are presented to elucidate the role of the main descriptors of BAM architecture. The proposed design enables the realization of BAM from a large palette of materials, including elastic-perfectly plastic materials and potentially brittle materials.

Genus Ranges of 4-Regular Rigid Vertex Graphs.

Science.gov (United States)

Buck, Dorothy; Dolzhenko, Egor; Jonoska, Nataša; Saito, Masahico; Valencia, Karin

2015-01-01

A rigid vertex of a graph is one that has a prescribed cyclic order of its incident edges. We study orientable genus ranges of 4-regular rigid vertex graphs. The (orientable) genus range is a set of genera values over all orientable surfaces into which a graph is embedded cellularly, and the embeddings of rigid vertex graphs are required to preserve the prescribed cyclic order of incident edges at every vertex. The genus ranges of 4-regular rigid vertex graphs are sets of consecutive integers, and we address two questions: which intervals of integers appear as genus ranges of such graphs, and what types of graphs realize a given genus range. For graphs with 2 n vertices ( n > 1), we prove that all intervals [ a, b ] for all a genus ranges. For graphs with 2 n - 1 vertices ( n ≥ 1), we prove that all intervals [ a, b ] for all a genus ranges. We also provide constructions of graphs that realize these ranges.

Role of Pectoral Fin Flexibility in Robotic Fish Performance

Science.gov (United States)

Bazaz Behbahani, Sanaz; Tan, Xiaobo

2017-08-01

Pectoral fins play a vital role in the maneuvering and locomotion of fish, and they have become an important actuation mechanism for robotic fish. In this paper, we explore the effect of flexibility of robotic fish pectoral fins on the robot locomotion performance and mechanical efficiency. A dynamic model for the robotic fish is presented, where the flexible fin is modeled as multiple rigid elements connected via torsional springs and dampers. Blade element theory is used to capture the hydrodynamic force on the fin. The model is validated with experimental results obtained on a robotic fish prototype, equipped with 3D-printed fins of different flexibility. The model is then used to analyze the impacts of fin flexibility and power/recovery stroke speed ratio on the robot swimming speed and mechanical efficiency. It is found that, in general, flexible fins demonstrate advantages over rigid fins in speed and efficiency at relatively low fin-beat frequencies, while rigid fins outperform flexible fins at higher frequencies. For a given fin flexibility, the optimal frequency for speed performance differs from the optimal frequency for mechanical efficiency. In addition, for any given fin, there is an optimal power/recovery stroke speed ratio, typically in the range of 2-3, that maximizes the speed performance. Overall, the presented model offers a promising tool for fin flexibility and gait design, to achieve speed and efficiency objectives for robotic fish actuated with pectoral fins.

Rigidity, Chaos and Integration: Hemispheric Interaction and Individual Differences in Metaphor Comprehension

Directory of Open Access Journals (Sweden)

Miriam eFaust

2014-07-01

Full Text Available Neurotypical individuals cope flexibly with the full range of semantic relations expressed in human language, including metaphoric relations. This impressive semantic ability may be associated with distinct and flexible patterns of hemispheric interaction, including higher right hemisphere (RH involvement for processing novel metaphors. However, this ability may be impaired in specific clinical conditions, such as Asperger syndrome and schizophrenia. The impaired semantic processing is accompanied by different patterns of hemispheric interaction during semantic processing, showing either reduced (in Asperger or excessive (in schizophrenia RH involvement. This paper interprets these individual differences using the terms Rigidity, Chaos and Integration, which describe patterns of semantic memory network states that either lead to semantic well-being or are disruptive of it. We argue that these semantic network states lie on a rigidity-chaos semantic continuum. We define these terms via network science terminology and provide network, cognitive and neural evidence to support our claim. This continuum includes LH hyper-rigid semantic memory state on one end (e.g., in persons with Asperger syndrome, and RH chaotic and over-flexible semantic memory state on the other end (e.g., in persons with schizophrenia. In between these two extremes lie different states of semantic memory structure which are related to individual differences in semantic creativity. We suggest that efficient semantic processing is achieved by semantic integration, a balance between semantic rigidity and semantic chaos. Such integration is achieved via intra-hemispheric communication. However, impairments to this well-balanced and integrated pattern of hemispheric interaction, e.g., when one hemisphere dominates the other, may lead to either semantic rigidity or semantic chaos, moving away from semantic integration and thus impairing the processing of metaphoric language.

A geometrically controlled rigidity transition in a model for confluent 3D tissues

Science.gov (United States)

Merkel, Matthias; Manning, M. Lisa

2018-02-01

The origin of rigidity in disordered materials is an outstanding open problem in statistical physics. Previously, a class of 2D cellular models has been shown to undergo a rigidity transition controlled by a mechanical parameter that specifies cell shapes. Here, we generalize this model to 3D and find a rigidity transition that is similarly controlled by the preferred surface area S 0: the model is solid-like below a dimensionless surface area of {s}0\\equiv {S}0/{\\bar{V}}2/3≈ 5.413 with \\bar{V} being the average cell volume, and fluid-like above this value. We demonstrate that, unlike jamming in soft spheres, residual stresses are necessary to create rigidity. These stresses occur precisely when cells are unable to obtain their desired geometry, and we conjecture that there is a well-defined minimal surface area possible for disordered cellular structures. We show that the behavior of this minimal surface induces a linear scaling of the shear modulus with the control parameter at the transition point, which is different from the scaling observed in particulate matter. The existence of such a minimal surface may be relevant for biological tissues and foams, and helps explain why cell shapes are a good structural order parameter for rigidity transitions in biological tissues.

Fabrication of digital microfluidic devices on flexible paper-based and rigid substrates via screen printing

Science.gov (United States)

Yafia, Mohamed; Shukla, Saurabh; Najjaran, Homayoun

2015-05-01

In this work, a new fabrication method is presented for digital microfluidic (DMF) devices in which the electrodes are generated using the screen printing technique. This method is applicable to both rigid and flexible substrates. The proposed screen printing approach, as a batch printing technique, is advantageous to the widely reported DMF fabrication methods in terms of fabrication time, cost and capability of mass production. Screen printing provides an effective means for printing different types of conductive materials on a variety of substrates. Specifically, screen printing of conductive silver and carbon based inks is performed on paper, glass and wax paper. As a result, the fabricated DMF devices are characterized by being flexible, disposable and incinerable. Hence, the main advantage of screen printing carbon based inks on paper substrates is more pronounced for point-of-care applications that require a large number of low cost DMF chips, and laboratory setups that lack sophisticated microfabrication facilities. The resolution of the printed DMF electrodes generated by this technique is examined for proof of concept using manual screen printing, but higher resolution screens and automated machines are available off-the-shelf, if needed. Another contribution of this research is the improved actuation techniques that facilitate droplet transport in electrode configurations with relatively large electrode spacing to alleviate the disadvantage of lower resolution screens. Thus, we were able to reduce the cost of fabrication significantly without compromising the DMF performance. The paper-based devices have already shown to be effective in continuous microfluidics domain, so the investigation of their applicability in DMF systems is worthwhile. With this in mind, successful integration of a paper-based microchannel with paper-based digital microfluidic chip is demonstrated in this work.

Fabrication of digital microfluidic devices on flexible paper-based and rigid substrates via screen printing

International Nuclear Information System (INIS)

Yafia, Mohamed; Shukla, Saurabh; Najjaran, Homayoun

2015-01-01

In this work, a new fabrication method is presented for digital microfluidic (DMF) devices in which the electrodes are generated using the screen printing technique. This method is applicable to both rigid and flexible substrates. The proposed screen printing approach, as a batch printing technique, is advantageous to the widely reported DMF fabrication methods in terms of fabrication time, cost and capability of mass production. Screen printing provides an effective means for printing different types of conductive materials on a variety of substrates. Specifically, screen printing of conductive silver and carbon based inks is performed on paper, glass and wax paper. As a result, the fabricated DMF devices are characterized by being flexible, disposable and incinerable. Hence, the main advantage of screen printing carbon based inks on paper substrates is more pronounced for point-of-care applications that require a large number of low cost DMF chips, and laboratory setups that lack sophisticated microfabrication facilities. The resolution of the printed DMF electrodes generated by this technique is examined for proof of concept using manual screen printing, but higher resolution screens and automated machines are available off-the-shelf, if needed. Another contribution of this research is the improved actuation techniques that facilitate droplet transport in electrode configurations with relatively large electrode spacing to alleviate the disadvantage of lower resolution screens. Thus, we were able to reduce the cost of fabrication significantly without compromising the DMF performance. The paper-based devices have already shown to be effective in continuous microfluidics domain, so the investigation of their applicability in DMF systems is worthwhile. With this in mind, successful integration of a paper-based microchannel with paper-based digital microfluidic chip is demonstrated in this work. (note)

[Flexibility of cognitive activity depends on its context].

Science.gov (United States)

Kostandov, É A

2010-01-01

The main purpose of this survey is to explain the importance of set-shifting for a flexible cognitive activity. Working memory overload may result in set-shifting slowdown, i.e., in a more rigid set and in a less flexible cognitive activity. This effect displays itself in an increase of erroneous perceptions of external stimuli. Set rigidity level also depends on the cognitive activity context (i.e., on the type of external stimuli the person has to deal with). We analyzed EEG-coherence function and induced synchronization/desynchronization responses in theta (4-7 Hz) and low alpha (8-10 Hz) bands. Basing on these data, we discuss the role of tonic and phasic forms of cortico-hippocampal and fronto-thalamic systems' activation in cognitive activity flexibility.

Cellular mechanics and motility

Science.gov (United States)

Hénon, Sylvie; Sykes, Cécile

2015-10-01

The term motility defines the movement of a living organism. One widely known example is the motility of sperm cells, or the one of flagellar bacteria. The propulsive element of such organisms is a cilium(or flagellum) that beats. Although cells in our tissues do not have a flagellum in general, they are still able to move, as we will discover in this chapter. In fact, in both cases of movement, with or without a flagellum, cell motility is due to a dynamic re-arrangement of polymers inside the cell. Let us first have a closer look at the propulsion mechanism in the case of a flagellum or a cilium, which is the best known, but also the simplest, and which will help us to define the hydrodynamic general conditions of cell movement. A flagellum is sustained by cellular polymers arranged in semi-flexible bundles and flagellar beating generates cell displacement. These polymers or filaments are part of the cellular skeleton, or "cytoskeleton", which is, in this case, external to the cellular main body of the organism. In fact, bacteria move in a hydrodynamic regime in which viscosity dominates over inertia. The system is thus in a hydrodynamic regime of low Reynolds number (Box 5.1), which is nearly exclusively the case in all cell movements. Bacteria and their propulsion mode by flagella beating are our unicellular ancestors 3.5 billion years ago. Since then, we have evolved to form pluricellular organisms. However, to keep the ability of displacement, to heal our wounds for example, our cells lost their flagellum, since it was not optimal in a dense cell environment: cells are too close to each other to leave enough space for the flagella to accomplish propulsion. The cytoskeleton thus developed inside the cell body to ensure cell shape changes and movement, and also mechanical strength within a tissue. The cytoskeleton of our cells, like the polymers or filaments that sustain the flagellum, is also composed of semi-flexible filaments arranged in bundles, and also in

Maxwell rigidity and topological constraints in amorphous phase-change networks

International Nuclear Information System (INIS)

Micoulaut, M.; Otjacques, C.; Raty, J.-Y.; Bichara, C.

2011-01-01

By analyzing first-principles molecular-dynamics simulations of different telluride amorphous networks, we develop a method for the enumeration of radial and angular topological constraints, and show that the phase diagram of the most popular system Ge-Sb-Te can be split into two compositional elastic phases: a tellurium rich flexible phase and a stressed rigid phase that contains most of the materials used in phase-change applications. This sound atomic scale insight should open new avenues for the understanding of phase-change materials and other complex amorphous materials from the viewpoint of rigidity.

Flexible Polyhedral Surfaces with Two Flat Poses

Directory of Open Access Journals (Sweden)

Hellmuth Stachel

2015-05-01

Full Text Available We present three types of polyhedral surfaces, which are continuously flexible and have not only an initial pose, where all faces are coplanar, but pass during their self-motion through another pose with coplanar faces (“flat pose”. These surfaces are examples of so-called rigid origami, since we only admit exact flexions, i.e., each face remains rigid during the motion; only the dihedral angles vary. We analyze the geometry behind Miura-ori and address Kokotsakis’ example of a flexible tessellation with the particular case of a cyclic quadrangle. Finally, we recall Bricard’s octahedra of Type 3 and their relation to strophoids.

The effect of chordwise flexibility on flapping foil propulsion in quiescent fluid

Science.gov (United States)

Shinde, Sachin; Arakeri, Jaywant

2010-11-01

Motivated to understand the role of wing flexibility of flying creatures during hovering, we experimentally study the effect of chordwise flexibility on the flow generated in quiescent fluid by a sinusoidally pitching rigid symmetrical foil with a flexible flap attached at the trailing edge. This foil produces a narrow, coherent jet containing reverse Karman vortex street, and a corresponding thrust. The thrust and flow is similar to that produced by a hovering bird or insect, however the mechanism seems to be different from known hovering mechanisms. Novelty of the present hovering mechanism is that the thrust generation is due to the coordinated pushing action of rigid foil and flexible flap. We identify the flow and vortex generation mechanism. This foil produces jet flows over a range of flapping frequencies and amplitudes. In contrast, the foil without flap i.e. with rigid trailing edge produces a weak, divergent jet that meanders randomly. Appending a flexible flap to the foil suppresses jet-meandering and strengthens the jet. Flexibility of flap is crucial in determining the flow structure. This study is useful in designing MAVs and thrusters.

Flexible circuits with integrated switches for robotic shape sensing

Science.gov (United States)

Harnett, C. K.

2016-05-01

Digital switches are commonly used for detecting surface contact and limb-position limits in robotics. The typical momentary-contact digital switch is a mechanical device made from metal springs, designed to connect with a rigid printed circuit board (PCB). However, flexible printed circuits are taking over from the rigid PCB in robotics because the circuits can bend while carrying signals and power through moving joints. This project is motivated by a previous work where an array of surface-mount momentary contact switches on a flexible circuit acted as an all-digital shape sensor compatible with the power resources of energy harvesting systems. Without a rigid segment, the smallest commercially-available surface-mount switches would detach from the flexible circuit after several bending cycles, sometimes violently. This report describes a low-cost, conductive fiber based method to integrate electromechanical switches into flexible circuits and other soft, bendable materials. Because the switches are digital (on/off), they differ from commercially-available continuous-valued bend/flex sensors. No amplification or analog-to-digital conversion is needed to read the signal, but the tradeoff is that the digital switches only give a threshold curvature value. Boundary conditions on the edges of the flexible circuit are key to setting the threshold curvature value for switching. This presentation will discuss threshold-setting, size scaling of the design, automation for inserting a digital switch into the flexible circuit fabrication process, and methods for reconstructing a shape from an array of digital switch states.

Job flexibility in Latin America: A comparative analysis

Directory of Open Access Journals (Sweden)

Manuel Alejandro Ibarra Cisneros

2010-01-01

Full Text Available Most of studies about labor flexibility show a partial image of the situation of Latin America labor markets. They are limited to confirm, the existence of high degrees of rigidity and the necessity to conduct labor reforms to the margin of specific national circumstances. The design of a synthetic labor rigidity indicator using methodology considered by the oecd, through a factor analysis for countries of IberoAmerica, allows obtaining certain advances in relation to this debate. The results establish the high importance of the rigidity in the procedures of collective dismissal, over normative aspects related to fixed term contracts. Finally, it is establish the little relation between flexibility levels and results in terms of economic development, putting into question the assertions that try to extrapolate strategies of flexibilization like isolated measurement to facilitate the economic progress of a country.

The effect of chain flexibility and chain mobility on radiation crosslinking reactions of polymers

International Nuclear Information System (INIS)

Sun Jiazhen

2003-01-01

Flexibility of polymer chains is an important factor to effects of radiation crosslinking of the polymer. Polymers with flexible chains are easier to be crosslinked, with lower dose of gelation, than polymers with more rigid chains. And it is known that most polymers with abnormal rigidity can be radiation-crosslinked only at high temperatures when the molecular chains get enough mobility. The flexibility of polymer chains also influences the relationship between degree of degradation and radiation dose. A chain flexibility factor β has been introduced to modify the Charlesby-Pinner equation of sol-fraction and radiation dose. The new relationship equation applies to a wider range of polymers in radiation crosslinking. Studies also show that for flexible polymers with lower T g and molecular internal rotating factor, mechanism of radiation crosslinking is mainly in H type, whereas for rigid polymers with higher T g and molecular internal rotating factor, mechanism of radiation crosslinking is mainly in T type

Integration of car-body flexibility into train-track coupling system dynamics analysis

Science.gov (United States)

Ling, Liang; Zhang, Qing; Xiao, Xinbiao; Wen, Zefeng; Jin, Xuesong

2018-04-01

The resonance vibration of flexible car-bodies greatly affects the dynamics performances of high-speed trains. In this paper, we report a three-dimensional train-track model to capture the flexible vibration features of high-speed train carriages based on the flexible multi-body dynamics approach. The flexible car-body is modelled using both the finite element method (FEM) and the multi-body dynamics (MBD) approach, in which the rigid motions are obtained by using the MBD theory and the structure deformation is calculated by the FEM and the modal superposition method. The proposed model is applied to investigate the influence of the flexible vibration of car-bodies on the dynamics performances of train-track systems. The dynamics performances of a high-speed train running on a slab track, including the car-body vibration behaviour, the ride comfort, and the running safety, calculated by the numerical models with rigid and flexible car-bodies are compared in detail. The results show that the car-body flexibility not only significantly affects the vibration behaviour and ride comfort of rail carriages, but also can has an important influence on the running safety of trains. The rigid car-body model underestimates the vibration level and ride comfort of rail vehicles, and ignoring carriage torsional flexibility in the curving safety evaluation of trains is conservative.

Structural modulation and luminescent properties of four CdII coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

Science.gov (United States)

Xia, Liang; Dong, Wen-Wen; Ye, Xiao; Zhao, Jun; Li, Dong-Sheng

2016-10-01

To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d10 coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt)2]n (1), [Cd3(4-pzpt)2(suc)2]n (2), [Cd2(4-Hpzpt)(nbc)2(H2O)]n (3) and {[Cd2(4-pzpt)2(tfbdc)(H2O)4]·H2O}n (4) (H2suc=1,2-ethanedicarboxylic acid, H2nbc=hthalene-1,4-dicarboxylic acid, H2tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 44-sql layer, which is extended to a 3D network via nonclassical C-H…N hydrogen bonds. Compound 2 possesses a 6-connected pcu-4120.63 net composed of trinuclear CdII-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·53·72)(53·6·7·9)(42·55·6·72). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 63-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O-H…N and O-H…O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated.

Rigidity of a spherical capsule switches the localization of encapsulated particles between inner and peripheral regions under crowding condition: Simple model on cellular architecture

Energy Technology Data Exchange (ETDEWEB)

Shew, Chwen-Yang, E-mail: chwenyang.shew@csi.cuny.edu; Kondo, Kenta [Department of Chemistry, College of Staten Island, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314 (United States); Yoshikawa, Kenichi [Faculty of Life and Medical Sciences, Doshisha University, Kyoto 610-0394 (Japan)

2014-01-14

We have investigated the inhomogeneous interior of confined spherical cavities as capsules containing encapsulated binary hard sphere mixtures for different compositions and cavity wall rigidity. Such a greatly simplified model manifests the effects of macromolecular crowding arising from excluded volume interactions in a tiny cell or a cellular nucleus. By fixing the number of large particles, the level of crowding is adjusted by changing the amount of small hard spheres in the cavity. For a rigid cavity, large spheres tend to pack in liquid-like order apart from the surface to the center of the cavity as the crowding level is increased. Whereas, for a soft cavity, larger spheres tend to blend with small spheres in the peripheral region at near the boundary of the cavity, and are susceptible to be depleted from the interior of the cavity as the cavity becomes more crowded. These results may help future elucidation of the thermodynamic pathways to stabilize the inhomogeneous structure of mixtures confined in cavities, such as the derepression of genome materials around the interior rim of the nucleus in a cancerous cell.

Rigidity of a spherical capsule switches the localization of encapsulated particles between inner and peripheral regions under crowding condition: Simple model on cellular architecture

International Nuclear Information System (INIS)

Shew, Chwen-Yang; Kondo, Kenta; Yoshikawa, Kenichi

2014-01-01

We have investigated the inhomogeneous interior of confined spherical cavities as capsules containing encapsulated binary hard sphere mixtures for different compositions and cavity wall rigidity. Such a greatly simplified model manifests the effects of macromolecular crowding arising from excluded volume interactions in a tiny cell or a cellular nucleus. By fixing the number of large particles, the level of crowding is adjusted by changing the amount of small hard spheres in the cavity. For a rigid cavity, large spheres tend to pack in liquid-like order apart from the surface to the center of the cavity as the crowding level is increased. Whereas, for a soft cavity, larger spheres tend to blend with small spheres in the peripheral region at near the boundary of the cavity, and are susceptible to be depleted from the interior of the cavity as the cavity becomes more crowded. These results may help future elucidation of the thermodynamic pathways to stabilize the inhomogeneous structure of mixtures confined in cavities, such as the derepression of genome materials around the interior rim of the nucleus in a cancerous cell

Enhanced mechanical properties of linear segmented shape memory poly(urethane-urea) by incorporating flexible PEG400 and rigid piperazine

Science.gov (United States)

Zhang, Xiao-Yan; Ma, Yu-Fei; Li, Yong-Gang; Wang, Pin-Pin; Wang, Yuan-Liang; Luo, Yan-Feng

2012-12-01

The goal of this study is to design and synthesize a linear segmented shape memory poly(urethane-urea) (SMPUU) that possesses near-body-temperature shape memory temperature ( T tran) and enhanced mechanical properties by incorporating flexible poly(ethylene glycol) 400 (PEG400) to form poly(D,L-lactic acid)-based macrodiols (PDLLA-PEG400-PDLLA) and then rigid piperazine (PPZ) as a chain extender to form the desired SMPUUs (PEG400-PUU-PPZ). PEG400 increased M n while maintaining a lower T g of PDLLA-PEG400-PDLLA, which together with PPZ improved the mechanical properties of PEG400-PUU-PPZ. The obtained optimum SMPUU with enhanced mechanical properties ( σ y = 24.28 MPa; ɛ f = 698%; U f = 181.5 MJ/m3) and a T g of 40.62°C exhibited sound shape memory properties as well, suggesting a promising SMPUU for in vivo biomedical applications.

Coupling dynamic analysis of spacecraft with multiple cylindrical tanks and flexible appendages

Science.gov (United States)

Wu, Wen-Jun; Yue, Bao-Zeng; Huang, Hua

2016-02-01

This paper is mainly concerned with the coupling dynamic analysis of a complex spacecraft consisting of one main rigid platform, multiple liquid-filled cylindrical tanks, and a number of flexible appendages. Firstly, the carrier potential function equations of liquid in the tanks are deduced according to the wall boundary conditions. Through employing the Fourier-Bessel series expansion method, the dynamic boundaries conditions on a curved free-surface under a low-gravity environment are transformed to general simple differential equations and the rigid-liquid coupled sloshing dynamic state equations of liquid in tanks are obtained. The state vectors of rigid-liquid coupled equations are composed with the modal coordinates of the relative potential function and the modal coordinates of wave height. Based on the Bernoulli-Euler beam theory and the D'Alembert's principle, the rigid-flexible coupled dynamic state equations of flexible appendages are directly derived, and the coordinate transform matrixes of maneuvering flexible appendages are precisely computed as time-varying. Then, the coupling dynamics state equations of the overall system of the spacecraft are modularly built by means of the Lagrange's equations in terms of quasi-coordinates. Lastly, the coupling dynamic performances of a typical complex spacecraft are studied. The availability and reliability of the presented method are also confirmed.

A DNA Origami Mechanical Device for the Regulation of Microcosmic Structural Rigidity.

Science.gov (United States)

Wan, Neng; Hong, Zhouping; Wang, Huading; Fu, Xin; Zhang, Ziyue; Li, Chao; Xia, Han; Fang, Yan; Li, Maoteng; Zhan, Yi; Yang, Xiangliang

2017-11-01

DNA origami makes it feasible to fabricate a tremendous number of DNA nanostructures with various geometries, dimensions, and functionalities. Moreover, an increasing amount of research on DNA nanostructures is focused on biological and biomedical applications. Here, the reversible regulation of microcosmic structural rigidity is accomplished using a DNA origami device in vitro. The designed DNA origami monomer is composed of an internal central axis and an external sliding tube. Due to the external tube sliding, the device transforms between flexible and rigid states. By transporting the device into the liposome, the conformational change of the origami device induces a structural change in the liposome. The results obtained demonstrate that the programmed DNA origami device can be applied to regulate the microcosmic structural rigidity of liposomes. Because microcosmic structural rigidity is important to cell proliferation and function, the results obtained potentially provide a foundation for the regulation of cell microcosmic structural rigidity using DNA nanostructures. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexibility Considerations on the Hydrodynamic Loading on a Vertical Wedge Drop

Science.gov (United States)

Ren, Zhongshu; Wang, Zhaoyuan; Judge, Carolyn; Stern, Fred; Ikeda, Christine

2017-11-01

High-speed craft operating at in waves frequently become airborne and slam into the water surface. This fluid-structure interaction problem is important to understand in order to increase the operating envelope of these craft. The goals of the current work are to investigate both the hydrodynamic loads and the resulting structural response on a planing hull. A V-shaped wedge is dropped vertically into calm water. The hydrodynamic pressure is measured using pressure sensors at discrete points on the hull. Two hulls are studied: one is rigid and one is flexible. Predictions of the hydrodynamic loading are made using Wagner's theory, Vorus's theory, and simulations in CFDShip Iowa. These predictions assume the structure is completely rigid. These predictions of the pressure coefficient match well with the rigid hull, as expected. The spray root is tracked in the rigid experimental set and compared with the theoretical and computational models. The pressure coefficient measured on the flexible hull shows discrepancies with the predictions due to the fluid-structure interaction. These discrepancies are quantified and interpreted in light of the structural flexibility. Funding for this work is from the Office of Naval Research Grant Number N00014-16-1-3188.

Dealing with Flexible Modes in 6 DOFs Robust Servo Control

NARCIS (Netherlands)

Oomen, T.A.E.; Bosgra, O.H.; Angelis, G.Z.

2007-01-01

Control of high performance multi-input multi-output electromechanical systems with flexible dynamics is investigated. Present feedforward and feedback control design approaches mainly focus on rigid-body plant behaviour. To achieve higher performance, flexible dynamics should be explicitly

Fabrication of rigid and flexible refractive-index-matched flow phantoms for flow visualisation and optical flow measurements

Science.gov (United States)

Geoghegan, P. H.; Buchmann, N. A.; Spence, C. J. T.; Moore, S.; Jermy, M.

2012-05-01

A method for the construction of both rigid and compliant (flexible) transparent flow phantoms of biological flow structures, suitable for PIV and other optical flow methods with refractive-index-matched working fluid is described in detail. Methods for matching the in vivo compliance and elastic wave propagation wavelength are presented. The manipulation of MRI and CT scan data through an investment casting mould is described. A method for the casting of bubble-free phantoms in silicone elastomer is given. The method is applied to fabricate flexible phantoms of the carotid artery (with and without stenosis), the carotid artery bifurcation (idealised and patient-specific) and the human upper airway (nasal cavity). The fidelity of the phantoms to the original scan data is measured, and it is shown that the cross-sectional error is less than 5% for phantoms of simple shape but up to 16% for complex cross-sectional shapes such as the nasal cavity. This error is mainly due to the application of a PVA coating to the inner mould and can be reduced by shrinking the digital model. Sixteen per cent variation in area is less than the natural patient to patient variation of the physiological geometries. The compliance of the phantom walls is controlled within physiologically realistic ranges, by choice of the wall thickness, transmural pressure and Young's modulus of the elastomer. Data for the dependence of Young's modulus on curing temperature are given for Sylgard 184. Data for the temperature dependence of density, viscosity and refractive index of the refractive-index-matched working liquid (i.e. water-glycerol mixtures) are also presented.

Scaling of the dynamics of flexible Lennard-Jones chains

DEFF Research Database (Denmark)

Veldhorst, Arno; Dyre, J. C.; Schrøder, Thomas

2014-01-01

functions of excess entropy) which has been observed in simulations of both molecular and polymeric systems. Doing molecular dynamics simulations of flexible Lennard-Jones chains (LJC) with rigid bonds, we here provide the first detailed test of the isomorph theory applied to flexible chain molecules. We...

Aerodynamic Optimization Based on Continuous Adjoint Method for a Flexible Wing

Directory of Open Access Journals (Sweden)

Zhaoke Xu

2016-01-01

Full Text Available Aerodynamic optimization based on continuous adjoint method for a flexible wing is developed using FORTRAN 90 in the present work. Aerostructural analysis is performed on the basis of high-fidelity models with Euler equations on the aerodynamic side and a linear quadrilateral shell element model on the structure side. This shell element can deal with both thin and thick shell problems with intersections, so this shell element is suitable for the wing structural model which consists of two spars, 20 ribs, and skin. The continuous adjoint formulations based on Euler equations and unstructured mesh are derived and used in the work. Sequential quadratic programming method is adopted to search for the optimal solution using the gradients from continuous adjoint method. The flow charts of rigid and flexible optimization are presented and compared. The objective is to minimize drag coefficient meanwhile maintaining lift coefficient for a rigid and flexible wing. A comparison between the results from aerostructural analysis of rigid optimization and flexible optimization is shown here to demonstrate that it is necessary to include the effect of aeroelasticity in the optimization design of a wing.

Flexible control of cellular encapsulation, permeability, and release in a droplet-templated bifunctional copolymer scaffold.

Science.gov (United States)

Chen, Qiushui; Chen, Dong; Wu, Jing; Lin, Jin-Ming

2016-11-01

Designing cell-compatible, bio-degradable, and stimuli-responsive hydrogels is very important for biomedical applications in cellular delivery and micro-scale tissue engineering. Here, we report achieving flexible control of cellular microencapsulation, permeability, and release by rationally designing a diblock copolymer, alginate-conjugated poly(N-isopropylacrylamide) (Alg-co-PNiPAM). We use the microfluidic technique to fabricate the bifunctional copolymers into thousands of mono-disperse droplet-templated hydrogel microparticles for controlled encapsulation and triggered release of mammalian cells. In particular, the grafting PNiPAM groups in the synthetic cell-laden microgels produce lots of nano-aggregates into hydrogel networks at elevated temperature, thereafter enhancing the permeability of microparticle scaffolds. Importantly, the hydrogel scaffolds are readily fabricated via on-chip quick gelation by triggered release of Ca 2+ from the Ca-EDTA complex; it is also quite exciting that very mild release of microencapsulated cells is achieved via controlled degradation of hydrogel scaffolds through a simple strategy of competitive affinity of Ca 2+ from the Ca-Alginate complex. This finding suggests that we are able to control cellular encapsulation and release through ion-induced gelation and degradation of the hydrogel scaffolds. Subsequently, we demonstrate a high viability of microencapsulated cells in the microgel scaffolds.

Public policies targeting labour market rigidities

Directory of Open Access Journals (Sweden)

Andreea Claudia ŞERBAN

2013-02-01

Full Text Available Labour market rigidity becomes an issue of increasing importance under conditions of shocks associated with the economic crisis due to the need to increase the adaptability and responsiveness to them. Thus, labour market policies must be directed towards mitigating rigidities caused by institutional or demographic factors or certain mismatch between demand and supply of education qualifications. This paper highlights the major role of the active labour market policies targeting the increase of labour flexibility, stressing the importance and impact on the ability to adapt quickly and effectively to macroeconomic shocks. Located on a declining trend in the years preceding the crisis, spending on labour market policies increased in 2009 in all the Member States of the European Union. Spending differences are significant between countries, Romania being at the lowest end of the European Union. This requires special attention because the increased adaptability of workers through training, as active measure, is of major importance considering the increased speed of changes in the labour market.

Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics.

Science.gov (United States)

Ye, Dong; Ding, Yajiang; Duan, Yongqing; Su, Jiangtao; Yin, Zhouping; Huang, Yong An

2018-05-01

Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facilitating Transitional Processes in Rigid Institutional Regimes for Water Management and Wetland Conservation: Experience from the Guadalquivir Estuary

Directory of Open Access Journals (Sweden)

Pablo F. Méndez

2012-03-01

Full Text Available Traditional policies for water resources management and wetland conservation are often based on command-and-control approaches. The latter tend to drive the human-wetland-water system into pathological states, characterized by more vulnerable ecosystems and rigid institutions for governance. The overcoming of these states may rest in the development of flexible and adaptive institutional regimes that rely on adaptive governance and management. Because past factors might constrain the implementation of more flexible adaptive approaches to management, it is important to understand the historical mechanisms underlying the genesis of institutional rigidity. We first present the results of a historical analysis of Doñana, which can be characterized as a pathological water socio-ecosystem governed through rigid institutional regimes for water resources management and wetland conservation. In a second step, we analyze the advances achieved during a recent, large-scale restoration program for the Doñana wetlands, which adhered explicitly to the tenets of adaptive management. Our analysis indicated that the historical persistence of command-and-control approaches has been a path-dependent process that led to the emergence of a rigid institutional regime and caused it to enter a rigidity trap. However, the achievements of the restoration program suggest that a more flexible and adaptive regime could be developed through the introduction of adaptive management at the operational levels, using specifically tailored action research programs. To conclude, we speculate that the research strategy outlined could be extended to comply with, or complement, the requirements of the EU's Water Framework Directive in other European water socio-ecosystems.

Pharmacological targeting of membrane rigidity: implications on cancer cell migration and invasion

International Nuclear Information System (INIS)

Braig, Simone; Stoiber, Katharina; Zahler, Stefan; Vollmar, Angelika M

2015-01-01

The invasive potential of cancer cells strongly depends on cellular stiffness, a physical quantity that is not only regulated by the mechanical impact of the cytoskeleton but also influenced by the membrane rigidity. To analyze the specific role of membrane rigidity in cancer progression, we treated cancer cells with the Acetyl-CoA carboxylase inhibitor Soraphen A and revealed an alteration of the phospholipidome via mass spectrometry. Migration, invasion, and cell death assays were employed to relate this alteration to functional consequences, and a decrease of migration and invasion without significant impact on cell death has been recorded. Fourier fluctuation analysis of giant plasma membrane vesicles showed that Soraphen A increases membrane rigidity of carcinoma cell membranes. Mechanical measurements of the creep deformation response of whole intact cells were performed using the optical stretcher. The increase in membrane rigidity was observed in one cell line without changing the creep deformation response indicating no restructuring of the cytoskeleton. These data indicate that the increase of membrane rigidity alone is sufficient to inhibit invasiveness of cancer cells, thus disclosing the eminent role of membrane rigidity in migratory processes. (paper)

Comparison of rigid and flexible endoscopy for removing esophageal foreign bodies in an emergency.

Science.gov (United States)

Tseng, Chia-Chen; Hsiao, Tzu-Yu; Hsu, Wei-Chung

2016-08-01

Despite the effectiveness of endoscopies in removing ingested foreign bodies (FBs) impacted in the esophagus, the merits and limitations of flexible endoscopy (FE) and rigid endoscopy (RE) remain unclear. Therefore, this study compares the advantages and disadvantages of both endoscopic procedures from a clinical perspective. A retrospective review was made of 273 patients suspected of esophageal FBs in emergency consultations of a tertiary medical referral center from March 2010 to March 2014. All patients received routine physical examinations, otolaryngological examinations, and X-rays of the neck and chest. The door-to-endoscopy time, procedure time, postendoscopic hospital stay, successful removal rates, and complications were analyzed as well. In this study, the most common esophageal FBs were fish and animal bones (76%) in adults and coins (74%) in children. The patients with existing esophageal FBs had significantly more frequent symptoms of dysphagia and signs of linear opacity as detected with lateral neck radiography than those without FB. Additionally, the door-to-endoscopy time, procedure time, and postendoscopic hospital stay was significantly shorter in FE patients than in RE patients. However, both RE and FE patients had high rates of successful FB removal (95%) and low complication rates (2%). Both FE and RE remove esophageal FBs successfully, as evidenced by their high success rates, low complication rates, and high detection rates. Although FE under local anesthesia is a less time-consuming procedure for adults, RE under general anesthesia may be preferable for children and can serve as an alternative to FE. Copyright © 2015. Published by Elsevier B.V.

The Direct Effect of Flexible Walls on Fontan Connection Fluid Dynamics

Science.gov (United States)

Tree, Mike; Fagan, Kiley; Yoganathan, Ajit

2014-11-01

The current standard treatment for sufferers of congenital heart defects is the palliative Fontan procedure. The Fontan procedure results in an anastomosis of major veins directly to the branched pulmonary arteries bypassing the dysfunctional ventricle. This total cavopulmonary connection (TCPC) extends life past birth, but Fontan patients still suffer long-term complications like decreased exercise capacity, protein-losing enteropathy, and pulmonary arteriovenous malformations (PAVM). These complications have direct ties to fluid dynamics within the connection. Previous experimental and computation studies of Fontan connection fluid dynamics employed rigid vessel models. More recent studies utilize flexible models, but a direct comparison of the fundamental fluid dynamics between rigid and flexible vessels only exists for a computational model, without a direct experimental validation. Thus, this study was a direct comparison of fluid dynamics within a rigid and two compliant idealized TCPCs. 2D particle image velocimetry measurements were collected at the connection center plane. Results include power loss, hepatic flow distribution, fluid shear stress, and flow structure recognition. The effect of flexible walls on these values and clinical impact will be discussed.

A method for regulating strong nonlinear vibration energy of the flexible arm

Directory of Open Access Journals (Sweden)

Yushu Bian

2015-07-01

Full Text Available For an oscillating system, large amplitude indicates strong vibration energy. In this article, modal interaction is used as a useful means to regulate strong nonlinear vibration energy of the flexible arm undergoing rigid motion. A method is put forward to migrate and dissipate vibration energy based on modal interaction. By means of multiple-scale perturbation analysis, it is proven that internal resonance can be successfully established between modes of the flexible arm and the vibration absorber. Through examples and analyses, it is verified that this control method is effective in regulating strong vibration energy and can be used to suppress strong nonlinear vibration of the flexible arm undergoing rigid motion.

Flexible biochips for detection of biomolecules

NARCIS (Netherlands)

Peter, M.; Schüler, T.; Furthner, F.; Rensing, P.A.; Heck, G.T. van; Schoo, H.F.M.; Möllier, R.; Fritzsche, W.; Breemen, A.J.J.M. van; Meinders, E.R.

2009-01-01

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll

Providing a Flexible, Learner-Centred Programme: Challenges for Educators

Science.gov (United States)

Cornelius, Sarah; Gordon, Carole

2008-01-01

This paper presents a case study of the implementation of a flexible learner-centred programme of study which blends face-to-face and online learning. The programme was developed to be flexible in terms of content and study strategies, whilst remaining within more rigid organisational structures and processes. This paper outlines the programme and…

A Vibration Control Method for the Flexible Arm Based on Energy Migration

Directory of Open Access Journals (Sweden)

Yushu Bian

2015-01-01

Full Text Available A vibration control method based on energy migration is proposed to decrease vibration response of the flexible arm undergoing rigid motion. A type of vibration absorber is suggested and gives rise to the inertial coupling between the modes of the flexible arm and the absorber. By analyzing 1 : 2 internal resonance, it is proved that the internal resonance can be successfully created and the exchange of vibration energy is existent. Due to the inertial coupling, the damping enhancement effect is revealed. Via the inertial coupling, vibration energy of the flexible arm can be dissipated by not only the damping of the vibration absorber but also its own enhanced damping, thereby effectively decreasing vibration. Through numerical simulations and analyses, it is proven that this method is feasible in controlling nonlinear vibration of the flexible arm undergoing rigid motion.

Flexible thermoelectric generator using bulk legs and liquid metal interconnects for wearable electronics

International Nuclear Information System (INIS)

Suarez, Francisco; Parekh, Dishit P.; Ladd, Collin; Vashaee, Daryoosh; Dickey, Michael D.; Öztürk, Mehmet C.

2017-01-01

Highlights: •Flexible thermoelectric generator (TEG) with bulk legs. •Flexible thermoelectric generator with liquid metal interconnects. •Flexible TEG with potential to match the performance of rigid TEGs. •Flexible TEG for wearable electronics. -- Abstract: Interest in wearable electronics for continuous, long-term health and performance monitoring is rapidly increasing. The reduction in power levels consumed by sensors and electronic circuits accompanied by the advances in energy harvesting methods allows for the realization of self-powered monitoring systems that do not have to rely on batteries. For wearable electronics, thermoelectric generators (TEGs) offer the unique ability to continuously convert body heat into usable energy. For body harvesting, it is preferable to have TEGs that are thin, soft and flexible. Unfortunately, the performances of flexible modules reported to date have been far behind those of their rigid counterparts. This is largely due to lower efficiencies of the thermoelectric materials, electrical or thermal parasitic losses and limitations on leg dimensions posed by the synthesis techniques. In this work, we present an entirely new approach and explore the possibility of using standard bulk legs in a flexible package. Bulk thermoelectric legs cut from solid ingots are far superior to thermoelectric materials synthesized using other techniques. A key enabler of the proposed technology is the use of EGaIn liquid metal interconnects, which not only provide extremely low interconnect resistance but also stretchability with self-healing, both of which are essential for flexible TE modules. The results suggest that this novel approach can finally produce flexible TEGs that have the potential to challenge the rigid TEGs and provide a pathway for the realization of self-powered wearable electronics.

Thermophysical properties of supercritical water and bond flexibility.

Science.gov (United States)

Shvab, I; Sadus, Richard J

2015-07-01

Molecular dynamics results are reported for the thermodynamic properties of supercritical water using examples of both rigid (TIP4P/2005) and flexible (TIP4P/2005f) transferable interaction potentials. Data are reported for pressure, isochoric and isobaric heat capacities, the thermal expansion coefficient, isothermal and adiabatic compressibilities, Joule-Thomson coefficient, speed of sound, self-diffusion coefficient, viscosities, and thermal conductivity. Many of these properties have unusual behavior in the supercritical phase such as maximum and minimum values. The effectiveness of bond flexibility on predicting these properties is determined by comparing the results to experimental data. The influence of the intermolecular potential on these properties is both variable and state point dependent. In the vicinity of the critical density, the rigid and flexible potentials yield very different values for the compressibilities, heat capacities, and thermal expansion coefficient, whereas the self-diffusion coefficient, viscosities, and thermal conductivities are much less potential dependent. Although the introduction of bond flexibility is a computationally expedient way to improve the accuracy of an intermolecular potential, it can be counterproductive in some cases and it is not an adequate replacement for incorporating the effects of polarization.

Flexible wings in flapping flight

Science.gov (United States)

Moret, Lionel; Thiria, Benjamin; Zhang, Jun

2007-11-01

We study the effect of passive pitching and flexible deflection of wings on the forward flapping flight. The wings are flapped vertically in water and are allowed to move freely horizontally. The forward speed is chosen by the flapping wing itself by balance of drag and thrust. We show, that by allowing the wing to passively pitch or by adding a flexible extension at its trailing edge, the forward speed is significantly increased. Detailed measurements of wing deflection and passive pitching, together with flow visualization, are used to explain our observations. The advantage of having a wing with finite rigidity/flexibility is discussed as we compare the current results with our biological inspirations such as birds and fish.

Role of active site rigidity in activity: MD simulation and fluorescence study on a lipase mutant.

Directory of Open Access Journals (Sweden)

Md Zahid Kamal

Full Text Available Relationship between stability and activity of enzymes is maintained by underlying conformational flexibility. In thermophilic enzymes, a decrease in flexibility causes low enzyme activity while in less stable proteins such as mesophiles and psychrophiles, an increase in flexibility is associated with enhanced enzyme activity. Recently, we identified a mutant of a lipase whose stability and activity were enhanced simultaneously. In this work, we probed the conformational dynamics of the mutant and the wild type lipase, particularly flexibility of their active site using molecular dynamic simulations and time-resolved fluorescence techniques. In contrast to the earlier observations, our data show that active site of the mutant is more rigid than wild type enzyme. Further investigation suggests that this lipase needs minimal reorganization/flexibility of active site residues during its catalytic cycle. Molecular dynamic simulations suggest that catalytically competent active site geometry of the mutant is relatively more preserved than wild type lipase, which might have led to its higher enzyme activity. Our study implies that widely accepted positive correlation between conformation flexibility and enzyme activity need not be stringent and draws attention to the possibility that high enzyme activity can still be accomplished in a rigid active site and stable protein structures. This finding has a significant implication towards better understanding of involvement of dynamic motions in enzyme catalysis and enzyme engineering through mutations in active site.

Reliably Modeling the Mechanical Stability of Rigid and Flexible Metal-Organic Frameworks.

Science.gov (United States)

Rogge, Sven M J; Waroquier, Michel; Van Speybroeck, Veronique

2018-01-16

, however, it is unclear which set of properties are suited and reliable for a given application, as a comprehensive comparison for a broad variety of MOFs is absent, impeding the widespread use of these theoretical frameworks. Herein, we fill this gap by critically assessing the performance of the three computational models on a broad set of MOFs that are representative for current applications. These materials encompass the mechanically rigid UiO-66(Zr) and MOF-5(Zn) as well as the flexible MIL-47(V) and MIL-53(Al), which undergo pressure-induced phase transitions. It is observed that the Born stability criteria and pressure-versus-volume equations of state give complementary insight into the macroscopic and microscopic origins of instability, respectively. However, interpretation of the Born stability criteria becomes increasingly difficult when less symmetric materials are considered. Moreover, pressure fluctuations during the simulations hamper their accuracy for flexible materials. In contrast, the pressure-versus-volume equations of state are determined in a thermodynamic ensemble specifically targeted to mitigate the effects of these instantaneous fluctuations, yielding more accurate results. The critical Account presented here paves the way toward a solid computational framework for an extensive presynthetic screening of MOFs to select those that are mechanically stable and can be postsynthetically densified before their use in targeted applications.

Flexible transparent electrode

Science.gov (United States)

Demiryont, Hulya; Shannon, Kenneth C., III; Moorehead, David; Bratcher, Matthew

2011-06-01

This paper presents the properties of the EclipseTECTM transparent conductor. EclipseTECTM is a room temperature deposited nanostructured thin film coating system comprised of metal-oxide semiconductor elements. The system possesses metal-like conductivity and glass-like transparency in the visible region. These highly conductive TEC films exhibit high shielding efficiency (35dB at 1 to 100GHz). EclipseTECTM can be deposited on rigid or flexible substrates. For example, EclipseTECTM deposited on polyethylene terephthalate (PET) is extremely flexible that can be rolled around a 9mm diameter cylinder with little or no reduction in electrical conductivity and that can assume pre-extension states after an applied stress is relieved. The TEC is colorless and has been tailored to have high visible transmittance which matches the eye sensitivity curve and allows the viewing of true background colors through the coating. EclipseTECTM is flexible, durable and can be tailored at the interface for applications such as electron- or hole-injecting OLED electrodes as well as electrodes in flexible displays. Tunable work function and optical design flexibility also make EclipseTECTM well-suited as a candidate for grid electrode replacement in next-generation photovoltaic cells.

Reversibly Bistable Flexible Electronics

KAUST Repository

Alfaraj, Nasir

2015-05-01

Introducing the notion of transformational silicon electronics has paved the way for integrating various applications with silicon-based, modern, high-performance electronic circuits that are mechanically flexible and optically semitransparent. While maintaining large-scale production and prototyping rapidity, this flexible and translucent scheme demonstrates the potential to transform conventionally stiff electronic devices into thin and foldable ones without compromising long-term performance and reliability. In this work, we report on the fabrication and characterization of reversibly bistable flexible electronic switches that utilize flexible n-channel metal-oxide-semiconductor field-effect transistors. The transistors are fabricated initially on rigid (100) silicon substrates before they are peeled off. They can be used to control flexible batches of light-emitting diodes, demonstrating both the relative ease of scaling at minimum cost and maximum reliability and the feasibility of integration. The peeled-off silicon fabric is about 25 µm thick. The fabricated devices are transferred to a reversibly bistable flexible platform through which, for example, a flexible smartphone can be wrapped around a user’s wrist and can also be set back to its original mechanical position. Buckling and cyclic bending of such host platforms brings a completely new dimension to the development of flexible electronics, especially rollable displays.

Analysis of the spatial structure of rigid polyphenylene dendrimers by small-angle neutron scattering

International Nuclear Information System (INIS)

Rosenfeldt, S.; Dingenouts, N.; Poetschke, D.; Ballauff, M.; Berresheim, A.J.; Muellen, K.; Lindner, P.; Saalwaechter, K.

2005-01-01

The analysis of the spatial structure of a rigid polyphenylene dendrimer G4-M of fourth generation by small-angle neutron scattering (SANS) is presented. This dendrimer is composed of phenyl units and is therefore devoid of any flexible unit. The scattering intensity of dilute solutions of the dendrimer was measured by SANS at different contrast which was adjusted by mixtures of protonated and deuterated toluene. Hence, the method of contrast variation could be applied and the data yield the scattering function extrapolated to infinite contrast. The comparison of this data with simulations demonstrates that the scaffold of the dendrimer is rigid as expected from its chemical structure. The positions of the various units setting up consecutive shells of the dendrimer are relatively well localized and the entire structure cannot be modeled in terms of spherically symmetric models. No backfolding of the terminal groups can occur and the model calculations demonstrate that higher generations of this dendritic scaffold must exhibit a dense shell and a congestion of the terminal groups. This finding is directly corroborated by recent solid-state NMR data. All results show that the rigid dendrimer investigated here presents the first example for a dendritic structure whose segment density does not have its maximum at the center. Rigid scaffolds are therefore the only way to achieve the goal of a 'dense-shell' dendrimer whereas flexible scaffolds leads invariably to the 'dense-core' case

WP 115 - More flexibility for more innovation? Evidence from the Netherlands

OpenAIRE

Blind, K.

2011-01-01

Labor market flexibility continues to be one of economics, politics and society highly debated topic. In recent years, the impact of increased labor market flexibility on research and innovation has gained more and more attention. Previous studies have shown, depending on the measurement of flexibility as well as on the data that both positive and negative influences can be found. However, the financial flexibility in terms of wage rigidities has hardly been explored empirically. With the use...

Education for Flexible Personality

Directory of Open Access Journals (Sweden)

Bogomir Novak

1998-12-01

Full Text Available Flexible personality transforms both cultural environment and itself. Post-modern personality is both contemplative and active. On one hand, it is subject to inner imagination of a creative act, and on the other hand, to creation of a tangible product What is more, flexible personality is also autonomous, mature, healthy and well balanced, as well as stable and responsive to the demand for change. Due to ever quicker changes, flexible personality is a must. And it is a task. The impact of professional work of adults on the education of children, however, is being conditioned by the exrigid family and rigid enterprises or institutions in which adults are employed. Nevertheless, flexible educational style is not repressive, as it used to be, nor permissive and totally concentrated on the child. It is a choice between the two qualities. The educators' style is dependent on their attitude towards life (play and self-education and not only towards work. Nowadays, flexibility is a way towards quality management of social and personal changes.

Designing heavy metal oxide glasses with threshold properties from network rigidity.

Science.gov (United States)

Chakraborty, Shibalik; Boolchand, P; Malki, M; Micoulaut, M

2014-01-07

Here, we show that a new class of glasses composed of heavy metal oxides involving transition metals (V2O5-TeO2) can surprisingly be designed from very basic tools using topology and rigidity of their underlying molecular networks. When investigated as a function of composition, such glasses display abrupt changes in network packing and enthalpy of relaxation at Tg, underscoring presence of flexible to rigid elastic phase transitions. We find that these elastic phases are fully consistent with polaronic nature of electronic conductivity at high V2O5 content. Such observations have new implications for designing electronic glasses which differ from the traditional amorphous electrolytes having only mobile ions as charge carriers.

Flexible rotor balancing by the influence coefficient method: Multiple critical speeds with rigid or flexible supports

Science.gov (United States)

Tessarzik, J. M.

1975-01-01

Experimental tests were conducted to demonstrate the ability of the influence coefficient method to achieve precise balance of flexible rotors of virtually any design for operation through virtually any speed range. Various practical aspects of flexible-rotor balancing were investigated. Tests were made on a laboratory quality machine having a 122 cm (48 in.) long rotor weighing 50 kg (110 lb) and covering a speed range up to 18000 rpm. The balancing method was in every instance effective, practical, and economical and permitted safe rotor operation over the full speed range covering four rotor bending critical speeds. Improved correction weight removal methods for rotor balancing were investigated. Material removal from a rotating disk was demonstrated through application of a commercially available laser.

Within-Winter Flexibility in Muscle Masses, Myostatin, and Cellular Aerobic Metabolic Intensity in Passerine Birds.

Science.gov (United States)

Swanson, David L; King, Marisa O; Culver, William; Zhang, Yufeng

Metabolic rates of passerine birds are flexible traits that vary both seasonally and among and within winters. Seasonal variation in summit metabolic rates (M sum = maximum thermoregulatory metabolism) in birds is consistently correlated with changes in pectoralis muscle and heart masses and sometimes with variation in cellular aerobic metabolic intensity, so these traits might also be associated with shorter-term, within-winter variation in metabolic rates. To determine whether these mechanisms are associated with within-winter variation in M sum , we examined the effects of short-term (ST; 0-7 d), medium-term (MT; 14-30 d), and long-term (LT; 30-yr means) temperature variables on pectoralis muscle and heart masses, pectoralis expression of the muscle-growth inhibitor myostatin and its metalloproteinase activators TLL-1 and TLL-2, and pectoralis and heart citrate synthase (CS; an indicator of cellular aerobic metabolic intensity) activities for two temperate-zone resident passerines, house sparrows (Passer domesticus) and dark-eyed juncos (Junco hyemalis). For both species, pectoralis mass residuals were positively correlated with ST temperature variables, suggesting that cold temperatures resulted in increased turnover of pectoralis muscle, but heart mass showed little within-winter variation for either species. Pectoralis mRNA and protein expression of myostatin and the TLLs were only weakly correlated with ST and MT temperature variables, which is largely consistent with trends in muscle masses for both species. Pectoralis and heart CS activities showed weak and variable trends with ST temperature variables in both species, suggesting only minor effects of temperature variation on cellular aerobic metabolic intensity. Thus, neither muscle or heart masses, regulation by the myostatin system, nor cellular aerobic metabolic intensity varied consistently with winter temperature, suggesting that other factors regulate within-winter metabolic variation in these birds.

Does flexible tunnel drilling affect the femoral tunnel angle measurement after anterior cruciate ligament reconstruction?

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Muller, Bart; Hofbauer, Marcus; Atte, Akere; van Dijk, C Niek; Fu, Freddie H

2015-12-01

To quantify the mean difference in femoral tunnel angle (FTA) as measured on knee radiographs between rigid and flexible tunnel drilling after anatomic anterior cruciate ligament (ACL) reconstruction. Fifty consecutive patients that underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a flexible reamer were included in this study. The control group was comprised of 50 patients all of who underwent primary anatomic ACL reconstruction with a single femoral tunnel drilled with a rigid reamer. All femoral tunnels were drilled through a medial portal to ensure anatomic tunnel placement. The FTA was determined from post-operative anterior-to-posterior (AP) radiographs by two independent observers. A 5° difference between the two mean FTA was considered clinically significant. The average FTA, when drilled with a rigid reamer, was 42.0° ± 7.2°. Drilling with a flexible reamer resulted in a mean FTA of 44.7° ± 7.0°. The mean difference of 2.7° was not statistically significant. The intraclass correlation coefficient for inter-tester reliability was 0.895. The FTA can be reliably determined from post-operative AP radiographs and provides a useful and reproducible metric for characterizing femoral tunnel position after both rigid and flexible femoral tunnel drilling. This has implications for post-operative evaluation and preoperative treatment planning for ACL revision surgery. IV.

Flexible Design for α-Duplex Communications in Multi-Tier Cellular Networks

KAUST Repository

AlAmmouri, Ahmad

2016-06-13

Backward compatibility is an essential ingredient for the success of new technologies. In the context of inband full-duplex (FD) communication, FD base stations (BSs) should support half-duplex (HD) users’ equipment (UEs) without sacrificing the foreseen FD gains. This paper presents flexible and tractable modeling framework for multi-tier cellular networks with FD BSs and FD/HD UEs. The presented model is based on stochastic geometry and accounts for the intrinsic vulnerability of uplink transmissions. The results show that FD UEs are not necessarily required to harvest rate gains from FD BSs. In particular, the results show that adding FD UEs to FD BSs offers a maximum of 5% rate gain over FD BSs and HD UEs case if multi-user diversity is exploited, which is a marginal gain compared to the burden required to implement FD transceivers at the UEs’ side. To this end, we shed light on practical scenarios where HD UEs operation with FD BSs outperforms the operation when both the BSs and UEs are FD and we find a closed form expression for the critical value of the self-interference attenuation power required for the FD UEs to outperform HD UEs.

Flexibility-Rigidity Coordination of the Dense Exopolysaccharide Matrix in Terrestrial Cyanobacteria Acclimated to Periodic Desiccation.

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Liu, Wen; Cui, Lijuan; Xu, Haiyan; Zhu, Zhaoxia; Gao, Xiang

2017-11-15

A dense exopolysaccharide (EPS) matrix is crucial for cyanobacterial survival in terrestrial xeric environments, in which cyanobacteria undergo frequent expansion and shrinkage processes during environmental desiccation-rehydration cycles. However, it is unclear how terrestrial cyanobacteria coordinate the structural dynamics of the EPS matrix upon expansion and shrinkage to avoid potential mechanical stress while benefiting from the matrix. In the present study, we sought to answer this question by investigating the gene expression, protein dynamics, enzymatic characteristics, and biological roles of WspA, an abundantly secreted protein, in the representative terrestrial cyanobacterium Nostoc flagelliforme The results demonstrated that WspA is a novel β-galactosidase that facilitates softening of the EPS matrix by breaking the polysaccharide backbone under substantial moisture or facilitates the thickening and relinkage of the broken matrix during the drying process, and thus these regulations are well correlated with moisture availability or desiccation-rehydration cycles. This coordination of flexibility and rigidity of the cyanobacterial extracellular matrix may contribute to a favorable balance of cell growth and stress resistance in xeric environments. IMPORTANCE How the exopolysaccharide matrix is dynamically coordinated by exoproteins to cope with frequent expansion and shrinkage processes in terrestrial colonial cyanobacteria remains unclear. Here we elucidated the biochemical identity and biological roles of a dominant exoprotein in these regulation processes. Our study thus gained insight into this regulative mechanism in cyanobacteria to combat periodic desiccation. In addition, the filamentous drought-adapted cyanobacterium Nostoc flagelliforme serves as an ideal model for us to explore this issue in this study. Copyright © 2017 American Society for Microbiology.

Dynamics and control of robotic spacecrafts for the transportation of flexible elements

International Nuclear Information System (INIS)

Wen, Hao; Chen, Ti; Yu, Bensong; Jin, Dongping

2016-01-01

The technology of robotic spacecrafts has been identified as one of the most appealing solutions to the on-orbit construction of large space structures in future space missions. As a prerequisite of a successful on-orbit construction, it is needed to use small autonomous spacecrafts for the transportation of flexible elements. To this end, the paper presents an energy-based scheme to control a couple of robotic spacecrafts carrying a flexible slender structure to its desired position. The flexible structure is modelled as a long beam based on the formulation of absolute nodal coordinates to account for the geometrical nonlinearity due to large displacement. Meanwhile, the robotic spacecrafts are actuated on their rigid-body degrees of freedom and modelled as two rigid bodies attached to the flexible beam. The energy-based controller is designed using the technique of energy shaping and damping injection such that translational and rotational maneuvers can be achieved with the suppression of the flexible vibrations of the beam. Finally, numerical case studies are performed to demonstrate the proposed schemes. (paper)

Free form CMOS electronics: Physically flexible and stretchable

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto; Sevilla, Galo T.; Hussain, Aftab M.; Ghoneim, Mohamed T.; Hanna, Amir; Kutbee, Arwa T.; Nassar, Joanna M.; Cruz, Melvin

2015-01-01

Free form (physically flexible and stretchable) electronics can be used for applications which are unexplored today due to the rigid and brittle nature of the state-of-the-art electronics. Therefore, we show integration strategy to rationally design

Nonlinear mechanics of non-rigid origami: an efficient computational approach

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Liu, K.; Paulino, G. H.

2017-10-01

Origami-inspired designs possess attractive applications to science and engineering (e.g. deployable, self-assembling, adaptable systems). The special geometric arrangement of panels and creases gives rise to unique mechanical properties of origami, such as reconfigurability, making origami designs well suited for tunable structures. Although often being ignored, origami structures exhibit additional soft modes beyond rigid folding due to the flexibility of thin sheets that further influence their behaviour. Actual behaviour of origami structures usually involves significant geometric nonlinearity, which amplifies the influence of additional soft modes. To investigate the nonlinear mechanics of origami structures with deformable panels, we present a structural engineering approach for simulating the nonlinear response of non-rigid origami structures. In this paper, we propose a fully nonlinear, displacement-based implicit formulation for performing static/quasi-static analyses of non-rigid origami structures based on `bar-and-hinge' models. The formulation itself leads to an efficient and robust numerical implementation. Agreement between real models and numerical simulations demonstrates the ability of the proposed approach to capture key features of origami behaviour.

Simulations of Micropumps Based on Tilted Flexible Fibers

Science.gov (United States)

Hancock, Matthew; Elabbasi, Nagi; Demirel, Melik

2015-11-01

Pumping liquids at low Reynolds numbers is challenging because of the principle of reversibility. We report here a class of microfluidic pump designs based on tilted flexible structures that combines the concepts of cilia (flexible elastic elements) and rectifiers (e.g., Tesla valves, check valves). We demonstrate proof-of-concept with 2D and 3D fluid-structure interaction (FSI) simulations in COMSOL Multiphysics®of micropumps consisting of a source for oscillatory fluidic motion, e.g. a piston, and a channel lined with tilted flexible rods or sheets to provide rectification. When flow is against the rod tilt direction, the rods bend backward, narrowing the channel and increasing flow resistance; when flow is in the direction of rod tilt, the rods bend forward, widening the channel and decreasing flow resistance. The 2D and 3D simulations involve moving meshes whose quality is maintained by prescribing the mesh displacement on guide surfaces positioned on either side of each flexible structure. The prescribed displacement depends on structure bending and maintains mesh quality even for large deformations. Simulations demonstrate effective pumping even at Reynolds numbers as low as 0.001. Because rod rigidity may be specified independently of Reynolds number, in principle, rod rigidity may be reduced to enable pumping at arbitrarily low Reynolds numbers.

Flexible nanoscale high-performance FinFETs

KAUST Repository

Sevilla, Galo T.

2014-10-28

With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics.

Constraint Network Analysis (CNA): a Python software package for efficiently linking biomacromolecular structure, flexibility, (thermo-)stability, and function.

Science.gov (United States)

Pfleger, Christopher; Rathi, Prakash Chandra; Klein, Doris L; Radestock, Sebastian; Gohlke, Holger

2013-04-22

For deriving maximal advantage from information on biomacromolecular flexibility and rigidity, results from rigidity analyses must be linked to biologically relevant characteristics of a structure. Here, we describe the Python-based software package Constraint Network Analysis (CNA) developed for this task. CNA functions as a front- and backend to the graph-based rigidity analysis software FIRST. CNA goes beyond the mere identification of flexible and rigid regions in a biomacromolecule in that it (I) provides a refined modeling of thermal unfolding simulations that also considers the temperature-dependence of hydrophobic tethers, (II) allows performing rigidity analyses on ensembles of network topologies, either generated from structural ensembles or by using the concept of fuzzy noncovalent constraints, and (III) computes a set of global and local indices for quantifying biomacromolecular stability. This leads to more robust results from rigidity analyses and extends the application domain of rigidity analyses in that phase transition points ("melting points") and unfolding nuclei ("structural weak spots") are determined automatically. Furthermore, CNA robustly handles small-molecule ligands in general. Such advancements are important for applying rigidity analysis to data-driven protein engineering and for estimating the influence of ligand molecules on biomacromolecular stability. CNA maintains the efficiency of FIRST such that the analysis of a single protein structure takes a few seconds for systems of several hundred residues on a single core. These features make CNA an interesting tool for linking biomacromolecular structure, flexibility, (thermo-)stability, and function. CNA is available from http://cpclab.uni-duesseldorf.de/software for nonprofit organizations.

Design, Prototyping and Control of a Flexible Cystoscope for Biomedical Applications

Science.gov (United States)

Sozer, Canberk; Ghorbani, Morteza; Alcan, Gokhan; Uvet, Huseyin; Unel, Mustafa; Kosar, Ali

2017-07-01

Kidney stone and prostate hyperplasia are very common urogenital diseases all over the world. To treat these diseases, one of the ESWL (Extracorporeal Shock Wave Lithotripsy), PCNL (Percutaneous Nephrolithotomy), cystoscopes or open surgery techniques can be used. Cystoscopes named devices are used for in-vivo intervention. A flexible or rigid cystoscope device is inserted into human body and operates on interested area. In this study, a flexible cystoscope prototype has been developed. The prototype is able to bend up to ±40°in X and Y axes, has a hydrodynamic cavitation probe for rounding sharp edges of kidney stone or resection of the filled prostate with hydrodynamic cavitation method and contains a waterproof medical camera to give visual feedback to the operator. The operator steers the flexible end-effector via joystick toward target region. This paper presents design, manufacturing, control and experimental setup of the tendon driven flexible cystoscope prototype. The prototype is 10 mm in outer diameter, 70 mm in flexible part only and 120 mm in total length with flexible part and rigid tube. The experimental results show that the prototype bending mechanism, control system, manufactured prototype parts and experimental setup function properly. A small piece of real kidney stone was broken in targeted area.

Improved HEPA Filter Technology for Flexible and Rigid Containment Barriers

International Nuclear Information System (INIS)

Pinson, Paul Arthur

1998-01-01

Safety and reliability in glovebox operations can be significantly improved and waste packaging efficiencies can be increased by inserting flexible, lightweight, high capacity HEPA filters into the walls of plastic sheet barriers. This HEPA filter/barrier technology can be adapted to a wide variety of applications: disposable waste bags, protective environmental barriers for electronic equipment, single or multiple use glovebag assemblies, flexible glovebox wall elements, and room partitions. These reliable and inexpensive filtered barriers have many uses in fields such as radioactive waste processing, HVAC filter changeout, vapor or grit blasting, asbestos cleanup, pharmaceutical, medical, biological, and electronic equipment containment. The applications can result in significant cost savings, improved operational reliability and safety, and total waste volume reduction. This technology was developed at the Argonne National Laboratory-West (ANL-W) in 1993 and has been used at ANL-W since then at the TRU Waste Characterization Chamber Gloveboxes. Another 1998 AGS Conference paper titled ''TRU Waste Characterization Gloveboxes'', presented by Mr. David Duncan of ANL-W, describes these boxes

Modeling of flexible reciprocating compressor considering the crosshead subsidence

Science.gov (United States)

Xue, Xiaogang; Liu, Shulin; Sun, Xin

2018-01-01

Crank-slider mechanisms are important parts of heavy duty machines, including reciprocating compressors, combustion motors. This paper targets on the dynamic response of the crosshead in a reciprocating compressor, taking into consideration the crosshead deviation from the original level. The traditional model of the compressor is usually a slider-mechanism system without considering the deflection of the crosshead, thus neglecting the influence of the piston rod, which has some flexible features. In this paper, a rigid-flexible model of slider-crank is described theoretically, using the commercial software MATLAB, where the crank, connecting rod and crosshead are treated as rigid bodies, while the piston rod connected to the crosshead is considered as a flexible body. The dynamic response of the mechanism with the crosshead subsidence is discussed detailedly in this paper. After calculated theoretically, the MATLAB simulation showed that the dynamic response of the crosshead will be greatly influenced if the crosshead subsided from the original level. Also, the influence of the crosshead subsidence was also investigated, and some extra vibration of the crosshead arises.

Flexible and Stretchable Microneedle Patches with Integrated Rigid Stainless Steel Microneedles for Transdermal Biointerfacing.

Science.gov (United States)

Rajabi, Mina; Roxhed, Niclas; Shafagh, Reza Zandi; Haraldson, Tommy; Fischer, Andreas Christin; Wijngaart, Wouter van der; Stemme, Göran; Niklaus, Frank

2016-01-01

This paper demonstrates flexible and stretchable microneedle patches that combine soft and flexible base substrates with hard and sharp stainless steel microneedles. An elastomeric polymer base enables conformal contact between the microneedle patch and the complex topography and texture of the underlying skin, while robust and sharp stainless steel microneedles reliably pierce the outer layers of the skin. The flexible microneedle patches have been realized by magnetically assembling short stainless steel microneedles into a flexible polymer supporting base. In our experimental investigation, the microneedle patches were applied to human skin and an excellent adaptation of the patch to the wrinkles and deformations of the skin was verified, while at the same time the microneedles reliably penetrate the surface of the skin. The unobtrusive flexible and stretchable microneedle patches have great potential for transdermal biointerfacing in a variety of emerging applications such as transdermal drug delivery, bioelectric treatments and wearable bio-electronics for health and fitness monitoring.

Force measurements of flexible tandem wings in hovering and forward flights

International Nuclear Information System (INIS)

Zheng, Yingying; Wu, Yanhua; Tang, Hui

2015-01-01

Aerodynamic forces, power consumptions and efficiencies of flexible and rigid tandem wings undergoing combined plunging/pitching motion were measured in a hovering flight and two forward flights with Strouhal numbers of 0.6 and 0.3. Three flexible dragonfly-like tandem wing models termed Wing I, Wing II, and Wing III which are progressively less flexible, as well as a pair of rigid wings as the reference were operated at three phase differences of 0°, 90° and 180°. The results showed that both the flexibility and phase difference have significant effects on the aerodynamic performances. In both hovering and forward flights at a higher oscillation frequency of 1 Hz (St = 0.6), the Wing III model outperformed the other wing models with larger total horizontal force coefficient and efficiency. In forward flight at the lower frequency of 0.5 Hz (St = 0.3), Wing III, rigid wings and Wing II models performed best at 0°, 90° and 180° phase difference, respectively. From the time histories of force coefficients of fore- and hind-wings, different peak values, phase lags, and secondary peaks were found to be the important reasons to cause the differences in the average horizontal force coefficients. Particle image velocimetry and deformation measurements were performed to provide the insights into how the flexibility affects the aerodynamic performance of the tandem wings. The spanwise bending deformation was found to contribute to the horizontal force, by offering a more beneficial position to make LEV more attached to the wing model in both hovering and forward flights, and inducing a higher-velocity region in forward flight. (paper)

Orangutans (Pongo spp.) may prefer tools with rigid properties to flimsy tools.

Science.gov (United States)

Walkup, Kristina R; Shumaker, Robert W; Pruetz, Jill D

2010-11-01

Preference for tools with either rigid or flexible properties was explored in orangutans (Pongo spp.) through an extension of D. J. Povinelli, J. E. Reaux, and L. A. Theall's (2000) flimsy-tool problem. Three captive orangutans were presented with three unfamiliar pairs of tools to solve a novel problem. Although each orangutan has spontaneously used tools in the past, the tools presented in this study were novel to the apes. Each pair of tools contained one tool with rigid properties (functional) and one tool with flimsy properties (nonfunctional). Solving the problem required selection of a rigid tool to retrieve a food reward. The functional tool was selected in nearly all trials. Moreover, two of the orangutans demonstrated this within the first test trials with each of the three tool types. Although further research is required to test this statistically, it suggests either a preexisting preference for rigid tools or comprehension of the relevant features required in a tool to solve the task. The results of this study demonstrate that orangutans can recognize, or learn to recognize, relevant tool properties and can choose an appropriate tool to solve a problem. (PsycINFO Database Record (c) 2010 APA, all rights reserved).

Metallization and biopatterning on ultra-flexible substrates via dextran sacrificial layers.

Directory of Open Access Journals (Sweden)

Peter Tseng

Full Text Available Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS layers (elastic moduli down to 3 kPa utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials.

Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers

Science.gov (United States)

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70∶1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Flexible Aperture Tuning Solution for Cellular Main Antenna in Metallic Back Cover Mobile Phone

Directory of Open Access Journals (Sweden)

Yew Choon Mark Tan

2017-10-01

Full Text Available Metal housing has been used extensively on portable communication devices such as on mobile phones and tablets. The choice of metal housing ranges from metallic rim to metallic back cover. This metal housing tends to improve the outlook appearance of the mobile devices, and add mechanical strength towards the mobile devices. However, from the aspect of the communication antenna, the metal housing often posts great challenges towards the flexibility in antenna design and reduction in antenna performance. This paper presents an approach to overcome the challenges by integrating the metal housing of the mobile phone as part of the antenna, along with the introduction of tunable antenna concept to provide different forms of Aperture Tuning to the Cellular Main Antenna, to satisfy its wide frequency band coverages for the 2nd, 3rd and 4th Generation (2G, 3G and 4G mobile network.

Broad-scale small-world network topology induces optimal synchronization of flexible oscillators

International Nuclear Information System (INIS)

Markovič, Rene; Gosak, Marko; Marhl, Marko

2014-01-01

The discovery of small-world and scale-free properties of many man-made and natural complex networks has attracted increasing attention. Of particular interest is how the structural properties of a network facilitate and constrain its dynamical behavior. In this paper we study the synchronization of weakly coupled limit-cycle oscillators in dependence on the network topology as well as the dynamical features of individual oscillators. We show that flexible oscillators, characterized by near zero values of divergence, express maximal correlation in broad-scale small-world networks, whereas the non-flexible (rigid) oscillators are best correlated in more heterogeneous scale-free networks. We found that the synchronization behavior is governed by the interplay between the networks global efficiency and the mutual frequency adaptation. The latter differs for flexible and rigid oscillators. The results are discussed in terms of evolutionary advantages of broad-scale small-world networks in biological systems

Space robots with flexible appendages: Dynamic modeling, coupling measurement, and vibration suppression

Science.gov (United States)

Meng, Deshan; Wang, Xueqian; Xu, Wenfu; Liang, Bin

2017-05-01

For a space robot with flexible appendages, vibrations of flexible structure can be easily excited during both orbit and/or attitude maneuvers of the base and the operation of the manipulators. Hence, the pose (position and attitude) of the manipulator's end-effector will greatly deviate from the desired values, and furthermore, the motion of the manipulator will trigger and exacerbate vibrations of flexible appendages. Given lack of the atmospheric damping in orbit, the vibrations will last for quite a while and cause the on-orbital tasks to fail. We derived the rigid-flexible coupling dynamics of a space robot system with flexible appendages and established a coupling model between the flexible base and the space manipulator. A specific index was defined to measure the coupling degree between the flexible motion of the appendages and the rigid motion of the end-effector. Then, we analyzed the dynamic coupling for different conditions, such as modal displacements, joint angles (manipulator configuration), and mass properties. Moreover, the coupling map was adopted and drawn to represent the coupling motion. Based on this map, a trajectory planning method was addressed to suppress structure vibration. Finally, simulation studies of typical cases were performed, which verified the proposed models and method. This work provides a theoretic basis for the system design, performance evaluation, trajectory planning, and control of such space robots.

Understanding geological processes: Visualization of rigid and non-rigid transformations

Science.gov (United States)

Shipley, T. F.; Atit, K.; Manduca, C. A.; Ormand, C. J.; Resnick, I.; Tikoff, B.

2012-12-01

Visualizations are used in the geological sciences to support reasoning about structures and events. Research in cognitive sciences offers insights into the range of skills of different users, and ultimately how visualizations might support different users. To understand the range of skills needed to reason about earth processes we have developed a program of research that is grounded in the geosciences' careful description of the spatial and spatiotemporal patterns associated with earth processes. In particular, we are pursuing a research program that identifies specific spatial skills and investigates whether and how they are related to each other. For this study, we focus on a specific question: Is there an important distinction in the geosciences between rigid and non-rigid deformation? To study a general spatial thinking skill we employed displays with non-geological objects that had been altered by rigid change (rotation), and two types of non-rigid change ("brittle" (or discontinuous) and "ductile" (or continuous) deformation). Disciplinary scientists (geosciences and chemistry faculty), and novices (non-science faculty and undergraduate psychology students) answered questions that required them to visualize the appearance of the object before the change. In one study, geologists and chemists were found to be superior to non-science faculty in reasoning about rigid rotations (e.g., what an object would look like from a different perspective). Geologists were superior to chemists in reasoning about brittle deformations (e.g., what an object looked like before it was broken - here the object was a word cut into many fragments displaced in different directions). This finding is consistent with two hypotheses: 1) Experts are good at visualizing the types of changes required for their domain; and 2) Visualization of rigid and non-rigid changes are not the same skill. An additional important finding is that there was a broad range of skill in both rigid and non-rigid

Cellular and molecular investigations of the adhesion and mechanics of Listeria monocytogenes

Science.gov (United States)

Eskhan, Asma Omar

Atomic force microscopy has been used to quantify the adherence and mechanical properties of an array of L. monocytogenes strains and their surface biopolymers. First, eight L. monocytogenes strains that represented the two major lineages of the species were compared for their adherence and mechanics at cellular and molecular levels. Our results indicated that strains of lineage' II were characterized by higher adhesion and Young's moduli, longer and more rigid surface biopolymers and lower specific and nonspecific forces when compared to lineage' I strains. Additionally, adherence and mechanical properties of eight L. monocytogenes epidemic and environmental strains were probed. Our results pointed to that environmental and epidemic strains representative of a given lineage were similar in their adherence and mechanical properties when investigated at a cellular level. However, when the molecular properties of the strains were considered, epidemic strains were characterized by higher specific and nonspecific forces, shorter, denser and more flexible biopolymers compared to environmental strains. Second, the role of environmental pH conditions of growth on the adhesion and mechanics of a pathogenic L. monocytogenes EGDe was investigated. Our results pointed to a transition in the adhesion energies for cells cultured at pH 7. In addition, when the types of molecular forces that govern the adhesion were quantified using Poisson statistical approach and using a new proposed method, specific hydrogen-bond energies dominated the bacterial adhesion process. Such a finding is instrumental to researchers designing methods to control bacterial adhesion. Similarly, bacterial cells underwent a transition in their mechanical properties. We have shown that cells cultured at pH 7 were the most rigid compared to those cultured in lower or higher pH conditions of growth. Due to transitions observed in adherence and mechanics when cells were cultured at pH 7, we hypothesized that

Development of a Flexible Non-Metal Electrode for Cell Stimulation and Recording

Directory of Open Access Journals (Sweden)

Cihun-Siyong Alex Gong

2016-09-01

Full Text Available This study presents a method of producing flexible electrodes for potentially simultaneously stimulating and measuring cellular signals in retinal cells. Currently, most multi-electrode applications rely primarily on etching, but the metals involved have a certain degree of brittleness, leaving them prone to cracking under prolonged pressure. This study proposes using silver chloride ink as a conductive metal, and polydimethysiloxane (PDMS as the substrate to provide electrodes with an increased degree of flexibility to allow them to bend. This structure is divided into the electrode layer made of PDMS and silver chloride ink, and a PDMS film coating layer. PDMS can be mixed in different proportions to modify the degree of rigidity. The proposed method involved three steps. The first segment entailed the manufacturing of the electrode, using silver chloride ink as the conductive material, and using computer software to define the electrode size and micro-engraving mechanisms to produce the electrode pattern. The resulting uniform PDMS pattern was then baked onto the model, and the flow channel was filled with the conductive material before air drying to produce the required electrode. In the second stage, we tested the electrode, using an impedance analyzer to measure electrode cyclic voltammetry and impedance. In the third phase, mechanical and biocompatibility tests were conducted to determine electrode properties. This study aims to produce a flexible, non-metallic sensing electrode which fits snugly for use in a range of measurement applications.

Flexible thermoplastic composite of Polyvinyl Butyral (PVB and waste of rigid Polyurethane foam

Directory of Open Access Journals (Sweden)

Marilia Sônego

2015-04-01

Full Text Available This study reports the preparation and characterization of composites with recycled poly(vinyl butyral (PVB and residue of rigid polyurethane foam (PUr, with PUr contents of 20, 35 and 50 wt %, using an extruder equipped with a Maillefer single screw and injection molding. The components of the composites were thermally characterized using differential scanning calorimetry (DSC and thermogravimetry. The composites were evaluated by melt flow index (MFI, tensile and hardness mechanical tests and scanning electron microscopy (SEM. Tg determined by DSC of PVB sample (53 °C indicated the presence of plasticizer (Tg of pure PVB is 70 °C. MFI of the composites indicated a viscosity increase with the PUr content and, as the shear rate was held constant during injection molding, higher viscosities promoted higher shear stresses in the composites, thereby causing breaking or tearing of the PUr particles. The SEM micrographs showed low adhesion between PVB and PUr and the presence of voids, both inherent in the rigid foam and in the interphase PVB-PUr. The SEM micrographs also showed that PVB/PUr (50/50 composite exhibited the smallest particle size and a more homogeneous and compact structure with fewer voids in the interface. The stiffness of the composites increases with addition of the PUr particles, as evidenced in the mechanical tests.

Rigid multibody system dynamics with uncertain rigid bodies

Energy Technology Data Exchange (ETDEWEB)

Batou, A., E-mail: anas.batou@univ-paris-est.fr; Soize, C., E-mail: christian.soize@univ-paris-est.fr [Universite Paris-Est, Laboratoire Modelisation et Simulation Multi Echelle, MSME UMR 8208 CNRS (France)

2012-03-15

This paper is devoted to the construction of a probabilistic model of uncertain rigid bodies for multibody system dynamics. We first construct a stochastic model of an uncertain rigid body by replacing the mass, the center of mass, and the tensor of inertia by random variables. The prior probability distributions of the stochastic model are constructed using the maximum entropy principle under the constraints defined by the available information. The generators of independent realizations corresponding to the prior probability distribution of these random quantities are further developed. Then several uncertain rigid bodies can be linked to each other in order to calculate the random response of a multibody dynamical system. An application is proposed to illustrate the theoretical development.

Free form CMOS electronics: Physically flexible and stretchable

KAUST Repository

Hussain, Muhammad Mustafa

2015-12-07

Free form (physically flexible and stretchable) electronics can be used for applications which are unexplored today due to the rigid and brittle nature of the state-of-the-art electronics. Therefore, we show integration strategy to rationally design materials, processes and devices to transform advanced complementary metal oxide semiconductor (CMOS) electronics into flexible and stretchable one while retaining their high performance, energy efficiency, ultra-large-scale-integration (ULSI) density, reliability and performance over cost benefit to expand its applications for wearable, implantable and Internet-of-Everything electronics.

Ligand Binding Induces Conformational Changes in Human Cellular Retinol-binding Protein 1 (CRBP1) Revealed by Atomic Resolution Crystal Structures.

Science.gov (United States)

Silvaroli, Josie A; Arne, Jason M; Chelstowska, Sylwia; Kiser, Philip D; Banerjee, Surajit; Golczak, Marcin

2016-04-15

Important in regulating the uptake, storage, and metabolism of retinoids, cellular retinol-binding protein 1 (CRBP1) is essential for trafficking vitamin A through the cytoplasm. However, the molecular details of ligand uptake and targeted release by CRBP1 remain unclear. Here we report the first structure of CRBP1 in a ligand-free form as well as ultra-high resolution structures of this protein bound to either all-trans-retinol or retinylamine, the latter a therapeutic retinoid that prevents light-induced retinal degeneration. Superpositioning of human apo- and holo-CRBP1 revealed major differences within segments surrounding the entrance to the retinoid-binding site. These included α-helix II and hairpin turns between β-strands βC-βD and βE-βF as well as several side chains, such as Phe-57, Tyr-60, and Ile-77, that change their orientations to accommodate the ligand. Additionally, we mapped hydrogen bond networks inside the retinoid-binding cavity and demonstrated their significance for the ligand affinity. Analyses of the crystallographic B-factors indicated several regions with higher backbone mobility in the apoprotein that became more rigid upon retinoid binding. This conformational flexibility of human apo-CRBP1 facilitates interaction with the ligands, whereas the more rigid holoprotein structure protects the labile retinoid moiety during vitamin A transport. These findings suggest a mechanism of induced fit upon ligand binding by mammalian cellular retinol-binding proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Development of a set of equations for incorporating disk flexibility effects in rotordynamical analyses

Science.gov (United States)

Flowers, George T.; Ryan, Stephen G.

1991-01-01

Rotordynamical equations that account for disk flexibility are developed. These equations employ free-free rotor modes to model the rotor system. Only transverse vibrations of the disks are considered, with the shaft/disk system considered to be torsionally rigid. Second order elastic foreshortening effects that couple with the rotor speed to produce first order terms in the equations of motion are included. The approach developed in this study is readily adaptable for usage in many of the codes that are current used in rotordynamical simulations. The equations are similar to those used in standard rigid disk analyses but with additional terms that include the effects of disk flexibility. An example case is presented to demonstrate the use of the equations and to show the influence of disk flexibility on the rotordynamical behavior of a sample system.

Dynamics modeling for a rigid-flexible coupling system with nonlinear deformation field

International Nuclear Information System (INIS)

Deng Fengyan; He Xingsuo; Li Liang; Zhang Juan

2007-01-01

In this paper, a moving flexible beam, which incorporates the effect of the geometrically nonlinear kinematics of deformation, is investigated. Considering the second-order coupling terms of deformation in the longitudinal and transverse deflections, the exact nonlinear strain-displacement relations for a beam element are described. The shear strains formulated by the present modeling method in this paper are zero, so it is reasonable to use geometrically nonlinear deformation fields to demonstrate and simplify a flexible beam undergoing large overall motions. Then, considering the coupling terms of deformation in two dimensions, finite element shape functions of a beam element and Lagrange's equations are employed for deriving the coupling dynamical formulations. The complete expression of the stiffness matrix and all coupling terms are included in the formulations. A model consisting of a rotating planar flexible beam is presented. Then the frequency and dynamical response are studied, and the differences among the zero-order model, first-order coupling model and the new present model are discussed. Numerical examples demonstrate that a 'stiffening beam' can be obtained, when more coupling terms of deformation are added to the longitudinal and transverse deformation field. It is shown that the traditional zero-order and first-order coupling models may not provide an exact dynamic model in some cases

Rigidity in routines and the development of resistance to change in individuals with Prader-Willi syndrome.

Science.gov (United States)

Haig, E L; Woodcock, K A

2017-05-01

Individuals with Prader-Willi syndrome (PWS) commonly show debilitating resistance to change, which has been linked to cognitive deficits in task switching. Anecdotal reports suggest that exposure to flexibility in routines during development may be beneficial for limiting subsequent resistance to change in people with PWS, which is consistent with a beneficial role of such exposure on the development of task switching, highlighted in typical children. Here, we aim to investigate the development of resistance to change in individuals with PWS and hypothesise that exposure to increased rigidity in routines will be associated with increased subsequent resistance to change. An author-compiled informant report interview and two previously validated questionnaires were administered to the caregivers of 10 individuals with PWS (5-23 years). The interview examined rigidity in routines and resistance to change across life stages defined by easily distinguishable events (before school, during primary school, during secondary school, after school, currently), using open-ended and structured yes/no and 5-point Likert questions. Open-ended data were coded using an author-compiled system. Responses from two additional informants and data from the questionnaires were used to assess inter-informant reliability and concurrent validity of the structured questions. The validity of the interview was supported by acceptable inter-rater reliability of the open-ended coding system and inter-informant reliability, internal consistency and concurrent validity of structured questions. Descriptive analyses of ratings of behaviour change showed a pattern of increasing resistance to change over the life course for the four oldest individuals, who had all been exposed to substantial rigidity in routines before and during primary school. Furthermore, only one individual - currently in primary school - was exposed to very little rigidity in routines before and during primary school, and he had

Flexible spin-orbit torque devices

Energy Technology Data Exchange (ETDEWEB)

Lee, OukJae; You, Long; Jang, Jaewon; Subramanian, Vivek [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Salahuddin, Sayeef [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2015-12-21

We report on state-of-the-art spintronic devices synthesized and fabricated directly on a flexible organic substrate. Large perpendicular magnetic anisotropy was achieved in ultrathin ferromagnetic heterostructures of Pt/Co/MgO sputtered on a non-rigid plastic substrate at room temperature. Subsequently, a full magnetic reversal of the Co was observed by exploiting the spin orbit coupling in Pt that leads to a spin accumulation at the Pt/Co interface when an in-plane current is applied. Quasi-static measurements show the potential for operating these devices at nano-second speeds. Importantly, the behavior of the devices remained unchanged under varying bending conditions (up to a bending radius of ≈ ±20–30 mm). Furthermore, the devices showed robust operation even after application of 10{sup 6} successive pulses, which is likely sufficient for many flexible applications. Thus, this work demonstrates the potential for integrating high performance spintronic devices on flexible substrates, which could lead to many applications ranging from flexible non-volatile magnetic memory to local magnetic resonance imaging.

Flexible spin-orbit torque devices

International Nuclear Information System (INIS)

Lee, OukJae; You, Long; Jang, Jaewon; Subramanian, Vivek; Salahuddin, Sayeef

2015-01-01

We report on state-of-the-art spintronic devices synthesized and fabricated directly on a flexible organic substrate. Large perpendicular magnetic anisotropy was achieved in ultrathin ferromagnetic heterostructures of Pt/Co/MgO sputtered on a non-rigid plastic substrate at room temperature. Subsequently, a full magnetic reversal of the Co was observed by exploiting the spin orbit coupling in Pt that leads to a spin accumulation at the Pt/Co interface when an in-plane current is applied. Quasi-static measurements show the potential for operating these devices at nano-second speeds. Importantly, the behavior of the devices remained unchanged under varying bending conditions (up to a bending radius of ≈ ±20–30 mm). Furthermore, the devices showed robust operation even after application of 10 6 successive pulses, which is likely sufficient for many flexible applications. Thus, this work demonstrates the potential for integrating high performance spintronic devices on flexible substrates, which could lead to many applications ranging from flexible non-volatile magnetic memory to local magnetic resonance imaging

On the synthesis of a bio-inspired dual-cellular fluidic flexible matrix composite adaptive structure based on a non-dimensional dynamics model

International Nuclear Information System (INIS)

Li, Suyi; Wang, K W

2013-01-01

A recent study investigated the dynamic characteristics of an adaptive structure concept featuring dual fluidic flexible matrix composite (F 2 MC) cells inspired by the configuration of plant cells and cell walls. This novel bio-inspired system consists of two F 2 MC cells with different fiber angles connected through internal fluid circuits. It was discovered that the dual F 2 MC cellular structure can be characterized as a two degree of freedom damped mass–spring oscillator, and can be utilized as a vibration absorber or an enhanced actuator under different operation conditions. These results demonstrated that the concept is promising and further investigations are needed to develop methodologies for synthesizing future multi-cellular F 2 MC structural systems. While interesting, the previous study focused on specific case studies and analysis. That is, the outcome did not provide insight that could be generalized, or tools for synthesizing a multiple F 2 MC cellular structure. This paper attempts to address this important issue by developing a non-dimensional dynamic model, which reveals good physical insights as well as identifying crucial constitutive parameters for F 2 MC cellular design. Working with these parameters, rather than physical variables, can greatly simplify the mathematics involved in the study. A synthesis tool is then developed for the dual-cellular structure, and it is found that for each set of achievable target poles and zero, there exist multiple F 2 MC cellular designs, forming a design space. The presented physical insights and synthesis tool for the dual-cellular structure will be the building blocks for future investigation on cellular structures with a larger number of cells. (paper)

RapidRMSD: Rapid determination of RMSDs corresponding to motions of flexible molecules.

Science.gov (United States)

Neveu, Emilie; Popov, Petr; Hoffmann, Alexandre; Migliosi, Angelo; Besseron, Xavier; Danoy, Grégoire; Bouvry, Pascal; Grudinin, Sergei

2018-03-15

The root mean square deviation (RMSD) is one of the most used similarity criteria in structural biology and bioinformatics. Standard computation of the RMSD has a linear complexity with respect to the number of atoms in a molecule, making RMSD calculations time-consuming for the large-scale modeling applications, such as assessment of molecular docking predictions or clustering of spatially proximate molecular conformations. Previously we introduced the RigidRMSD algorithm to compute the RMSD corresponding to the rigid-body motion of a molecule. In this study we go beyond the limits of the rigid-body approximation by taking into account conformational flexibility of the molecule. We model the flexibility with a reduced set of collective motions computed with e.g. normal modes or principal component analysis. The initialization of our algorithm is linear in the number of atoms and all the subsequent evaluations of RMSD values between flexible molecular conformations depend only on the number of collective motions that are selected to model the flexibility. Therefore, our algorithm is much faster compared to the standard RMSD computation for large-scale modeling applications. We demonstrate the efficiency of our method on several clustering examples, including clustering of flexible docking results and molecular dynamics (MD) trajectories. We also demonstrate how to use the presented formalism to generate pseudo-random constant-RMSD structural molecular ensembles and how to use these in cross-docking. We provide the algorithm written in C ++ as the open-source RapidRMSD library governed by the BSD-compatible license, which is available at http://team.inria.fr/nano-d/software/RapidRMSD/. The constant-RMSD structural ensemble application and clustering of MD trajectories is available at http://team.inria.fr/nano-d/software/nolb-normal-modes/. sergei.grudinin@inria.fr. Supplementary data are available at Bioinformatics.

Preliminary clinical report of flexible videoarthroscopy in diagnostic knee and hip arthroscopy.

Science.gov (United States)

Bouaicha, Samy; Dora, Claudio; Puskas, Gabor J; Koch, Peter P; Wirth, Stephan H; Meyer, Dominik C

2012-01-01

Compared to rigid arthroscopic optics, a flexible camera system offers theoretically significant advantages: It has the potential to adapt to the naturally curved surface of joints, to move within the joint without stress to the cartilage or capsule and thereby to reduce the number of portals needed. Former studies evaluated flexible fiberoptic systems which were insufficient regarding image resolution. This is the first report on a new flexible videoendoscope with the so called "chip-on-the-tip" technology used in human joints. With a plasma sterilized 3.9 diameter flexible video endoscopy system (Visera ENF V, OLYMPUS) commonly used in diagnostic rhino-laryngoscopy, we performed preliminary testing in cadaveric knee joints. After successful feasibility testing we utilized the tool in two qualitative diagnostic knee and five hip arthroscopies in combination with conventional rigid 30° and 70° arthroscopes (STORZ). Qualitative evaluation showed superior visualisation of the posterior aspects of the knee joint as insertion of the posterior medial and lateral meniscal horn, tibial insertion of the posterior cruciate ligament and the posterolateral capsulo-ligamentous corner with acceptable image resolution and clarity compared to the rigid arthroscope. In the hip, it was possible to pass around the femoral neck, avoiding additional portals. There seemed to be virtually no risk for cartilage damage at all. Difficulties of the system were scope handling, navigation and orientation within the joint as well as potential damage to the tool itself. This is to our knowledge the first report on flexible videoarthroscopy. Some of the expectations were met, such as to reach virtually every corner the joint with minimal risk for the cartilage or other joint structures and with acceptable image quality. However, there are many significant disadvantages which question the routine use of such a videoendoscopic system with its present technical features. © 2012 – IOS Press and

High Performance Electronics on Flexible Silicon

KAUST Repository

Sevilla, Galo T.

2016-09-01

Over the last few years, flexible electronic systems have gained increased attention from researchers around the world because of their potential to create new applications such as flexible displays, flexible energy harvesters, artificial skin, and health monitoring systems that cannot be integrated with conventional wafer based complementary metal oxide semiconductor processes. Most of the current efforts to create flexible high performance devices are based on the use of organic semiconductors. However, inherent material\\'s limitations make them unsuitable for big data processing and high speed communications. The objective of my doctoral dissertation is to develop integration processes that allow the transformation of rigid high performance electronics into flexible ones while maintaining their performance and cost. In this work, two different techniques to transform inorganic complementary metal-oxide-semiconductor electronics into flexible ones have been developed using industry compatible processes. Furthermore, these techniques were used to realize flexible discrete devices and circuits which include metal-oxide-semiconductor field-effect-transistors, the first demonstration of flexible Fin-field-effect-transistors, and metal-oxide-semiconductors-based circuits. Finally, this thesis presents a new technique to package, integrate, and interconnect flexible high performance electronics using low cost additive manufacturing techniques such as 3D printing and inkjet printing. This thesis contains in depth studies on electrical, mechanical, and thermal properties of the fabricated devices.

320-nm Flexible Solution-Processed 2,7-dioctyl[1] benzothieno[3,2-b]benzothiophene Transistors

OpenAIRE

Ren, Hang; Tang, Qingxin; Tong, Yanhong; Liu, Yichun

2017-01-01

Flexible organic thin-film transistors (OTFTs) have received extensive attention due to their outstanding advantages such as light weight, low cost, flexibility, large-area fabrication, and compatibility with solution-processed techniques. However, compared with a rigid substrate, it still remains a challenge to obtain good device performance by directly depositing solution-processed organic semiconductors onto an ultrathin plastic substrate. In this work, ultrathin flexible OTFTs are success...

Dimensional Metrology of Non-rigid Parts Without Specialized Inspection Fixtures =

Science.gov (United States)

Sabri, Vahid

Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures and technological advances. Functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We will focus here on the geometric inspection of non-rigid (flexible) parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a free-state condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the installation and inspection processes are expensive and time-consuming. Our aim in this thesis is therefore to develop an inspection method which eliminates the need for specialized fixtures. This is done by acquiring a point cloud from the part in a free-state condition using a contactless measuring device such as optical scanning and comparing it with the CAD model for the deviation identification. Using a non-rigid registration method and finite element analysis, we numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of displacement boundary conditions for simulating unfixed parts. In addition, we propose a numerical method for dimensional metrology of non-rigid parts in a free-state condition based on the arc length measurement by calculating the geodesic distance using the Fast Marching Method (FMM). In this thesis, we apply our developed methods on industrial non-rigid parts with free-form surfaces simulated with different types of

Design of flexible skin based on a mixed cruciform honeycomb

Science.gov (United States)

Rong, Jiaxin; Zhou, Li

2017-04-01

As the covering of morphing wings, flexible skin is required to provide adequate cooperation deformation, keep the smoothness of the aerodynamic configuration and bear the air load. The non-deformation direction of flexible skin is required to be restrained to keep the smoothness during morphing. This paper studies the deformation mechanisms of a cruciform honeycomb under zero Poisson's ratio constraint. The morphing capacity and in-plane modulus of the cruciform honeycomb are improved by optimizing the shape parameters of honeycomb unit. To improve the out-of-plane bending capacity, a zero Poisson's ratio mixed cruciform honeycomb is proposed by adding ribs into cruciform honeycomb, which can be used as filling material of flexible skin. The mechanical properties of the mixed honeycomb are studied by theoretical analysis and simulation. The local deformation of flexible skin under air load is also analyzed. Targeting the situation of non-uniform air load, a gradient density design scheme is referred. According to the design requirements of the variable camber trailing edge wing flexible skin, the specific design parameters and performance parameters of the skin based on the mixed honeycomb are given. The results show that the zero Poisson's ratio mixed cruciform honeycomb has a large bending rigidity itself and can have a better deformation capacity in-plane and a larger bending rigidity out-of-plane by optimizing the shape parameters. Besides, the designed skin also has advantages in driving force, deformation capacity and quality compared with conventional skin.

Flexible MEMS: A novel technology to fabricate flexible sensors and electronics

Science.gov (United States)

Tu, Hongen

This dissertation presents the design and fabrication techniques used to fabricate flexible MEMS (Micro Electro Mechanical Systems) devices. MEMS devices and CMOS(Complementary Metal-Oxide-Semiconductor) circuits are traditionally fabricated on rigid substrates with inorganic semiconductor materials such as Silicon. However, it is highly desirable that functional elements like sensors, actuators or micro fluidic components to be fabricated on flexible substrates for a wide variety of applications. Due to the fact that flexible substrate is temperature sensitive, typically only low temperature materials, such as polymers, metals, and organic semiconductor materials, can be directly fabricated on flexible substrates. A novel technology based on XeF2(xenon difluoride) isotropic silicon etching and parylene conformal coating, which is able to monolithically incorporate high temperature materials and fluidic channels, was developed at Wayne State University. The technology was first implemented in the development of out-of-plane parylene microneedle arrays that can be individually addressed by integrated flexible micro-channels. These devices enable the delivery of chemicals with controlled temporal and spatial patterns and allow us to study neurotransmitter-based retinal prosthesis. The technology was further explored by adopting the conventional SOI-CMOS processes. High performance and high density CMOS circuits can be first fabricated on SOI wafers, and then be integrated into flexible substrates. Flexible p-channel MOSFETs (Metal-Oxide-Semiconductor Field-Effect-Transistors) were successfully integrated and tested. Integration of pressure sensors and flow sensors based on single crystal silicon has also been demonstrated. A novel smart yarn technology that enables the invisible integration of sensors and electronics into fabrics has been developed. The most significant advantage of this technology is its post-MEMS and post-CMOS compatibility. Various high

[Functional characteristics of flexible supporting structures for heart valve bioprosthesis].

Science.gov (United States)

Dobrova, N B; Agafonov, A V; Barbarash, L S; Zavalishin, N N; Neniukov, A K

1984-01-01

Hydraulic characteristics of heart valve bioprostheses mounted on supporting structures of various rigidity have been studied under physiologic conditions. An actual mobility of the supporting structures made of different polymers is determined. Static and dynamic components of the support displacements have been shown to develop as the bioprosthesis is under the load, the dynamic component being strongly dependent upon the rigidity of fastening the bioprosthesis on the axis. It is noted that considerable improvements in hydraulic characteristics of bioprostheses are achieved through the use of flexible supporting structures.

Stability Result For Dynamic Inversion Devised to Control Large Flexible Aircraft

Science.gov (United States)

Gregory, Irene M.

2001-01-01

High performance aircraft of the future will be designed lighter, more maneuverable, and operate over an ever expanding flight envelope. One of the largest differences from the flight control perspective between current and future advanced aircraft is elasticity. Over the last decade, dynamic inversion methodology has gained considerable popularity in application to highly maneuverable fighter aircraft, which were treated as rigid vehicles. This paper is an initial attempt to establish global stability results for dynamic inversion methodology as applied to a large, flexible aircraft. This work builds on a previous result for rigid fighter aircraft and adds a new level of complexity that is the flexible aircraft dynamics, which cannot be ignored even in the most basic flight control. The results arise from observations of the control laws designed for a new generation of the High-Speed Civil Transport aircraft.

A modal analysis of flexible aircraft dynamics with handling qualities implications

Science.gov (United States)

Schmidt, D. K.

1983-01-01

A multivariable modal analysis technique is presented for evaluating flexible aircraft dynamics, focusing on meaningful vehicle responses to pilot inputs and atmospheric turbulence. Although modal analysis is the tool, vehicle time response is emphasized, and the analysis is performed on the linear, time-domain vehicle model. In evaluating previously obtained experimental pitch tracking data for a family of vehicle dynamic models, it is shown that flexible aeroelastic effects can significantly affect pitch attitude handling qualities. Consideration of the eigenvalues alone, of both rigid-body and aeroelastic modes, does not explain the simulation results. Modal analysis revealed, however, that although the lowest aeroelastic mode frequency was still three times greater than the short-period frequency, the rigid-body attitude response was dominated by this aeroelastic mode. This dominance was defined in terms of the relative magnitudes of the modal residues in selected vehicle responses.

Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

Science.gov (United States)

Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

2012-01-01

Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

Rigid Residue Scan Simulations Systematically Reveal Residue Entropic Roles in Protein Allostery.

Directory of Open Access Journals (Sweden)

Robert Kalescky

2016-04-01

Full Text Available Intra-protein information is transmitted over distances via allosteric processes. This ubiquitous protein process allows for protein function changes due to ligand binding events. Understanding protein allostery is essential to understanding protein functions. In this study, allostery in the second PDZ domain (PDZ2 in the human PTP1E protein is examined as model system to advance a recently developed rigid residue scan method combining with configurational entropy calculation and principal component analysis. The contributions from individual residues to whole-protein dynamics and allostery were systematically assessed via rigid body simulations of both unbound and ligand-bound states of the protein. The entropic contributions of individual residues to whole-protein dynamics were evaluated based on covariance-based correlation analysis of all simulations. The changes of overall protein entropy when individual residues being held rigid support that the rigidity/flexibility equilibrium in protein structure is governed by the La Châtelier's principle of chemical equilibrium. Key residues of PDZ2 allostery were identified with good agreement with NMR studies of the same protein bound to the same peptide. On the other hand, the change of entropic contribution from each residue upon perturbation revealed intrinsic differences among all the residues. The quasi-harmonic and principal component analyses of simulations without rigid residue perturbation showed a coherent allosteric mode from unbound and bound states, respectively. The projection of simulations with rigid residue perturbation onto coherent allosteric modes demonstrated the intrinsic shifting of ensemble distributions supporting the population-shift theory of protein allostery. Overall, the study presented here provides a robust and systematic approach to estimate the contribution of individual residue internal motion to overall protein dynamics and allostery.

Flexible and tunable silicon photonic circuits on plastic substrates

Science.gov (United States)

Chen, Yu; Li, Huan; Li, Mo

2012-09-01

Flexible microelectronics has shown tremendous promise in a broad spectrum of applications, especially those that cannot be addressed by conventional microelectronics in rigid materials and constructions. These unconventional yet important applications range from flexible consumer electronics to conformal sensor arrays and biomedical devices. A recent paradigm shift in implementing flexible electronics is to physically transfer highly integrated devices made in high-quality, crystalline semiconductors on to plastic substrates. Here we demonstrate a flexible form of silicon photonics using the transfer-and-bond fabrication method. Photonic circuits including interferometers and resonators have been transferred onto flexible plastic substrates with preserved functionalities and performance. By mechanically deforming, the optical characteristics of the devices can be tuned reversibly over a remarkably large range. The demonstration of the new flexible photonic systems based on the silicon-on-plastic (SOP) platform could open the door to many future applications, including tunable photonics, optomechanical sensors and biomechanical and bio-photonic probes.

A deformation model of flexible, HAMR objects for accurate propagation under perturbations and the self-shadowing effects

Science.gov (United States)

Channumsin, Sittiporn; Ceriotti, Matteo; Radice, Gianmarco

2018-02-01

A new type of space debris in near geosynchronous orbit (GEO) was recently discovered and later identified as exhibiting unique characteristics associated with high area-to-mass ratio (HAMR) objects, such as high rotation rates and high reflection properties. Observations have shown that this debris type is very sensitive to environmental disturbances, particularly solar radiation pressure, due to the fact that its motion depends on the actual effective area, orientation of that effective area, reflection properties and the area-to-mass ratio of the object is not stable over time. Previous investigations have modelled this type of debris as rigid bodies (constant area-to-mass ratios) or discrete deformed body; however, these simplifications will lead to inaccurate long term orbital predictions. This paper proposes a simple yet reliable model of a thin, deformable membrane based on multibody dynamics. The membrane is modelled as a series of flat plates, connected through joints, representing the flexibility of the membrane itself. The mass of the membrane, albeit low, is taken into account through lump masses at the joints. The attitude and orbital motion of this flexible membrane model is then propagated near GEO to predict its orbital evolution under the perturbations of solar radiation pressure, Earth's gravity field (J2), third body gravitational fields (the Sun and Moon) and self-shadowing. These results are then compared to those obtained for two rigid body models (cannonball and flat rigid plate). In addition, Monte Carlo simulations of the flexible model by varying initial attitude and deformation angle (different shape) are investigated and compared with the two rigid models (cannonball and flat rigid plate) over a period of 100 days. The numerical results demonstrate that cannonball and rigid flat plate are not appropriate to capture the true dynamical evolution of these objects, at the cost of increased computational time.

Tuning of magnetic frustration in S = 1 / 2 Kagomé lattices {[Cu3(CO3)2(bpe)3](CLO4)2}n and {[Cu3(CO3)2(bpy)3](CLO4)2}n through rigid and flexible ligands

Science.gov (United States)

Ajeesh, M. O.; Yogi, A.; Padmanabhan, M.; Nath, R.

2015-04-01

Single crystalline and polycrystalline samples of S = 1 / 2 Kagomé lattices { [Cu3(CO3)2(bpe)3 ](CLO4)2 } n and { [Cu3(CO3)2(bpy)3 ](CLO4)2 } n, respectively were synthesized. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. Both compounds crystalize in a hexagonal structure (space group P-6) consisting of CuO4 Kagomé layers in the ab-plane but linked along c direction through either rigid bpy or flexible bpe ligands to form 3D frame works. Magnetic measurements reveal that both the compounds undergo ferromagnetic ordering (TC) at low temperatures and the TC and the extent of frustration could be tuned by changing the nature of the pillar ligands. {[Cu3(CO3)2(bpe)3](CLO4)2}n which is made up of flexible bpe ligands has a TC of 5.7 K and a Curie-Weiss temperature (θCW) of -39.7 K giving rise to a frustration parameter of |θCW | /TC ≃ 6.96. But the replacement of bpe by a more rigid and electronically delocalized bpy ligand leads to an enhanced TC ≃ 9.3 K and a reduced frustration parameter of |θCW | /TC ≃ 3.54.

Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity

International Nuclear Information System (INIS)

Shrestha, Utsab R.; Bhowmik, Debsindhu; Van Delinder, Kurt W.; Mamontov, Eugene; O’Neill, Hugh

2017-01-01

Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.

Collective Excitations in Protein as a Measure of Balance Between its Softness and Rigidity

Energy Technology Data Exchange (ETDEWEB)

Shrestha, Utsab R. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Bhowmik, Debsindhu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Computational Science and Engineering Division; Van Delinder, Kurt W. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy; Mamontov, Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division; O’Neill, Hugh [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Zhang, Qiu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biology and Soft Matter Division; Alatas, Ahmet [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source; Chu, Xiang-Qiang [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy

2017-01-12

Here, we elucidate the protein activity from the perspective of protein softness and flexibility by studying the collective phonon-like excitations in a globular protein, human serum albumin (HSA), and taking advantage of the state-of-the-art inelastic X-ray scattering (IXS) technique. Such excitations demonstrate that the protein becomes softer upon thermal denaturation due to disruption of weak noncovalent bonds. On the other hand, no significant change in the local excitations is detected in ligand- (drugs) bound HSA compared to the ligand-free HSA. These results clearly suggest that the protein conformational flexibility and rigidity are balanced by the native protein structure for biological activity.

Efficient dynamic simulation of flexible link manipulators with PID control

NARCIS (Netherlands)

Aarts, Ronald G.K.M.; Jonker, Jan B.; Mook, D.T.; Balachandran, B.

2001-01-01

For accurate simulations of the dynamic behavior of flexible manipulators the combination of a perturbation method and modal analysis is proposed. First, the vibrational motion is modeled as a first-order perturbation of a nominal rigid link motion. The vibrational motion is then described by a set

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

International Nuclear Information System (INIS)

Fletcher, Rachel E.; Wells, Stephen A.; Leung, Ka Ming; Edwards, Peter P.; Sartbaeva, Asel

2015-01-01

Framework materials possess intrinsic flexibility which can be investigated using geometric simulation. We review framework flexibility properties in energy materials and present novel results on the flexibility window of the EMT zeolite framework containing 18-crown-6 ether as a structure directing agent (SDA). Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves – as in the case of silicates, where the geometry of the SiO 4 tetrahedral group is much more strongly constrained than the Si—O—Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the ‘rigid unit mode’ (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the ‘flexibility window’ phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework

Capital-Skill Complementarity and Rigid Relative Wages

DEFF Research Database (Denmark)

Rose Skaksen, Jan; Sørensen, Anders

2004-01-01

be countercyclical. The labor market is competitivein the United States and therefore relative wages of skilled labor are expected to becountercyclical. We find that the business cycle development of the two economiesis consistent with capital-skill complementarity.Keywords: capital-skill complementarity, relative......The relative demand for skills has increased considerably in many OECD countriesduring recent decades. This development is potentially explained by capital-skillcomplementarity and high growth rates of capital equipment. When productionfunctions are characterized by capital-skill complementarity......, relative wages and employmentof skilled labor are countercyclical because capital equipment is a quasi-fixed factor in the short run. The exact behavior of the two variables depends onrelative wage flexibility. Relative wages are rigid in Denmark, implying that the employmentshare of skills should...

On Integrity of Flexible Displays

Science.gov (United States)

Bouten, Piet C. P.

Nowadays two display types are dominant in the display market: the bulky cathode ray tube (CRT) and liquid crystal displays (LCD). Both types use glass as substrate material. The LCD display is the dominant player for mobile applications, in for instance mobile phones and portable computers. In the development of displays and their applications a clear interest exists to replace the rigid rectangular display cells by free-shaped, curved or even roll-up cells. These types of applications require flexible displays.

Heterostructured ZnS/InP nanowires for rigid/flexible ultraviolet photodetectors with enhanced performance.

Science.gov (United States)

Zhang, Kai; Ding, Jia; Lou, Zheng; Chai, Ruiqing; Zhong, Mianzeng; Shen, Guozhen

2017-10-19

Heterostructured ZnS/InP nanowires, composed of single-crystalline ZnS nanowires coated with a layer of InP shell, were synthesized via a one-step chemical vapor deposition process. As-grown heterostructured ZnS/InP nanowires exhibited an ultrahigh I on /I off ratio of 4.91 × 10 3 , a high photoconductive gain of 1.10 × 10 3 , a high detectivity of 1.65 × 10 13 Jones and high response speed even in the case of very weak ultraviolet light illumination (1.87 μW cm -2 ). The values are much higher than those of previously reported bare ZnS nanowires owing to the formation of core/shell heterostructures. Flexible ultraviolet photodetectors were also fabricated with the heterostructured ZnS/InP nanowires, which showed excellent mechanical flexibility, electrical stability and folding endurance besides excellent photoresponse properties. The results elucidated that the heterostructured ZnS/InP nanowires could find good applications in next generation flexible optoelectronic devices.

Roll-to-roll slot-die coating of 400 mm wide, flexible, transparent Ag nanowire films for flexible touch screen panels.

Science.gov (United States)

Kim, Dong-Ju; Shin, Hae-In; Ko, Eun-Hye; Kim, Ki-Hyun; Kim, Tae-Woong; Kim, Han-Ki

2016-09-28

We report fabrication of large area Ag nanowire (NW) film coated using a continuous roll-to-roll (RTR) slot die coater as a viable alternative to conventional ITO electrodes for cost-effective and large-area flexible touch screen panels (TSPs). By controlling the flow rate of shear-thinning Ag NW ink in the slot die, we fabricated Ag NW percolating network films with different sheet resistances (30-70 Ohm/square), optical transmittance values (89-90%), and haze (0.5-1%) percentages. Outer/inner bending, twisting, and rolling tests as well as dynamic fatigue tests demonstrated that the mechanical flexibility of the slot-die coated Ag NW films was superior to that of conventional ITO films. Using diamond-shape patterned Ag NW layer electrodes (50 Ohm/square, 90% optical transmittance), we fabricated 12-inch flexible film-film type and rigid glass-film-film type TSPs. Successful operation of flexible TSPs with Ag NW electrodes indicates that slot-die-coated large-area Ag NW films are promising low cost, high performance, and flexible transparent electrodes for cost-effective large-area flexible TSPs and can be substituted for ITO films, which have high sheet resistance and are brittle.

Roll-to-roll slot-die coating of 400 mm wide, flexible, transparent Ag nanowire films for flexible touch screen panels

Science.gov (United States)

Kim, Dong-Ju; Shin, Hae-In; Ko, Eun-Hye; Kim, Ki-Hyun; Kim, Tae-Woong; Kim, Han-Ki

2016-09-01

We report fabrication of large area Ag nanowire (NW) film coated using a continuous roll-to-roll (RTR) slot die coater as a viable alternative to conventional ITO electrodes for cost-effective and large-area flexible touch screen panels (TSPs). By controlling the flow rate of shear-thinning Ag NW ink in the slot die, we fabricated Ag NW percolating network films with different sheet resistances (30-70 Ohm/square), optical transmittance values (89-90%), and haze (0.5-1%) percentages. Outer/inner bending, twisting, and rolling tests as well as dynamic fatigue tests demonstrated that the mechanical flexibility of the slot-die coated Ag NW films was superior to that of conventional ITO films. Using diamond-shape patterned Ag NW layer electrodes (50 Ohm/square, 90% optical transmittance), we fabricated 12-inch flexible film-film type and rigid glass-film-film type TSPs. Successful operation of flexible TSPs with Ag NW electrodes indicates that slot-die-coated large-area Ag NW films are promising low cost, high performance, and flexible transparent electrodes for cost-effective large-area flexible TSPs and can be substituted for ITO films, which have high sheet resistance and are brittle.

Singular formalism and admissible control of spacecraft with rotating flexible solar array

Directory of Open Access Journals (Sweden)

Lu Dongning

2014-02-01

Full Text Available This paper is concerned with the attitude control of a three-axis-stabilized spacecraft which consists of a central rigid body and a flexible sun-tracking solar array driven by a solar array drive assembly. Based on the linearization of the dynamics of the spacecraft and the modal identities about the flexible and rigid coupling matrices, the spacecraft attitude dynamics is reduced to a formally singular system with periodically varying parameters, which is quite different from a spacecraft with fixed appendages. In the framework of the singular control theory, the regularity and impulse-freeness of the singular system is analyzed and then admissible attitude controllers are designed by Lyapunov’s method. To improve the robustness against system uncertainties, an H∞ optimal control is designed by optimizing the H∞ norm of the system transfer function matrix. Comparative numerical experiments are performed to verify the theoretical results.

Smart Material-Actuated Flexible Tendon-Based Snake Robot

Directory of Open Access Journals (Sweden)

Mohiuddin Ahmed

2016-05-01

Full Text Available A flexible snake robot has better navigation ability compare with the existing electrical motor-based rigid snake robot, due to its excellent bending capability during navigation inside a narrow maze. This paper discusses the modelling, simulation and experiment of a flexible snake robot. The modelling consists of the kinematic analysis and the dynamic analysis of the snake robot. A platform based on the Incompletely Restrained Positioning Mechanism (IRPM is proposed, which uses the external force provided by a compliant flexible beam in each of the actuators. The compliant central column allows the configuration to achieve three degrees of freedom (3DOFs with three tendons. The proposed flexible snake robot has been built using smart material, such as electroactive polymers (EAPs, which can be activated by applying power to it. Finally, the physical prototype of the snake robot has been built. An experiment has been performed in order to justify the proposed model.

The two-body problem of a pseudo-rigid body and a rigid sphere

DEFF Research Database (Denmark)

Kristiansen, Kristian Uldall; Vereshchagin, M.; Gózdziewski, K.

2012-01-01

n this paper we consider the two-body problem of a spherical pseudo-rigid body and a rigid sphere. Due to the rotational and "re-labelling" symmetries, the system is shown to possess conservation of angular momentum and circulation. We follow a reduction procedure similar to that undertaken...... in the study of the two-body problem of a rigid body and a sphere so that the computed reduced non-canonical Hamiltonian takes a similar form. We then consider relative equilibria and show that the notions of locally central and planar equilibria coincide. Finally, we show that Riemann's theorem on pseudo......-rigid bodies has an extension to this system for planar relative equilibria....

Dynamic response and stability of semi-rigid frames

Science.gov (United States)

Abu-Yasein, Omar Ali

This dissertation presents a method to determine the load capacity as well as end member forces and deformations of frames with partial rigid joint connections by using the direct stiffness method. The connections are modeled as rotational springs attached at the ends of framed members. The lumped mass method, which is an approximate method, and the distributed mass method, which is an exact method, are also presented to compute the natural frequency of frames. The effects of the axial forces and the flexibility of joint connections are both included. Furthermore, the time-dependent response of semi-rigid frames subjected to periodic axial forces is formulated. The harmonic function is approximated by dividing the periodic function into n intervals and the periodic axial forces are evaluated at each time interval as constant forces using 'piecewise approximation'. The regions of instability of frames with different joint stiffness were determined using the characteristic equation method. The time-dependent part of the differential equation for free vibration of a framed member subjected to a harmonic force can be written in the form of the Mathieu-Hill equation where all characteristics of the Mathieu-Hill equation solutions can be used to determine the boundaries of instability regions.

Propulsion via flexible flapping in granular media

Science.gov (United States)

Peng, Zhiwei; Ding, Yang; Pietrzyk, Kyle; Elfring, Gwynn; Pak, On Shun

2017-11-01

Biological locomotion in nature is often achieved by the interaction between a flexible body and its surrounding medium. The interaction of a flexible body with granular media is less understood compared with viscous fluids partially due to its complex rheological properties. In this work, we explore the effect of flexibility on granular propulsion by considering a simple mechanical model in which a rigid rod is connected to a torsional spring that is under a displacement actuation using a granular resistive force theory. Through a combined numerical and asymptotic investigation, we characterize the propulsive dynamics of such a flexible flapper in relation to the actuation amplitude and spring stiffness, and we compare these dynamics with those observed in a viscous fluid. In addition, we demonstrate that the maximum possible propulsive force can be obtained in the steady propulsion limit with a finite spring stiffness and large actuation amplitude. These results may apply to the development of synthetic locomotive systems that exploit flexibility to move through complex terrestrial media. Funding for Z.P. and Y.D. was partially provided by NSFC 394 Grant No. 11672029 and NSAF-NSFC Grant No. U1530401.

Wind-Induced Reconfigurations in Flexible Branched Trees

Science.gov (United States)

Ojo, Oluwafemi; Shoele, Kourosh

2017-11-01

Wind induced stresses are the major mechanical cause of failure in trees. We know that the branching mechanism has an important effect on the stress distribution and stability of a tree in the wind. Eloy in PRL 2011, showed that Leonardo da Vinci's original observation which states the total cross section of branches is conserved across branching nodes is the best configuration for resisting wind-induced fracture in rigid trees. However, prediction of the fracture risk and pattern of a tree is also a function of their reconfiguration capabilities and how they mitigate large wind-induced stresses. In this studies through developing an efficient numerical simulation of flexible branched trees, we explore the role of the tree flexibility on the optimal branching. Our results show that the probability of a tree breaking at any point depends on both the cross-section changes in the branching nodes and the level of tree flexibility. It is found that the branching mechanism based on Leonardo da Vinci's original observation leads to a uniform stress distribution over a wide range of flexibilities but the pattern changes for more flexible systems.

Study of a zero Poisson’s ratio honeycomb used for flexible skin

Science.gov (United States)

Rong, Jiaxin; Zhou, Li

2017-04-01

Flexible skin used in morphing wings is required to provide adequate cooperation deformation as well as bear the air load. Besides, according to the requirement of smoothness, the non-deformation direction of flexible skin needs to be restrained. This paper studies the mechanical properties of a cruciform honeycomb under a zero Poisson’s ratio constraint. The in-plane morphing capacity of the honeycomb is improved by optimizing the shape parameters of the honeycomb unit. To improve the out-of-plane bending capacity, a zero Poisson’s ratio mixed cruciform honeycomb with additional ribs is proposed. The mechanical properties of the mixed honeycomb are studied by theoretical analysis and simulation. Based on the design requirements of variable-camber trailing-edge flexible skin, the specific design parameters and performance parameters of the skin based on the mixed honeycomb are given. The results show that the zero Poisson’s ratio mixed cruciform honeycomb has high bending rigidity itself and can have better deformation capacity in-plane and higher bending rigidity out-of-plane by optimizing the shape parameters. The designed skin also has advantages in driving force, deformation capacity and quality over conventional skin.

Thermal shock induced dynamics of a spacecraft with a flexible deploying boom

Science.gov (United States)

Shen, Zhenxing; Li, Huijian; Liu, Xiaoning; Hu, Gengkai

2017-12-01

The dynamics in the process of deployment of a flexible extendible boom as a deployable structure on the spacecraft is studied. For determining the thermally induced vibrations of the boom subjected to an incident solar heat flux, an axially moving thermal-dynamic beam element based on the absolute nodal coordinate formulation which is able to precisely describe the large displacement, rotation and deformation of flexible body is presented. For the elastic forces formulation of variable-length beam element, the enhanced continuum mechanics approach is adopted, which can eliminate the Poisson locking effect, and take into account the tension-bending-torsion coupling deformations. The main body of the spacecraft, modeled as a rigid body, is described using the natural coordinates method. In the derived nonlinear thermal-dynamic equations of rigid-flexible multibody system, the mass matrix is time-variant, and a pseudo damping matrix which is without actual energy dissipation, and a heat conduction matrix which is relative to the moving speed and the number of beam element are arisen. Numerical results give the dynamic and thermal responses of the nonrotating and spinning spacecraft, respectively, and show that thermal shock has a significant influence on the dynamics of spacecraft.

Rigid Body Sampling and Individual Time Stepping for Rigid-Fluid Coupling of Fluid Simulation

Directory of Open Access Journals (Sweden)

Xiaokun Wang

2017-01-01

Full Text Available In this paper, we propose an efficient and simple rigid-fluid coupling scheme with scientific programming algorithms for particle-based fluid simulation and three-dimensional visualization. Our approach samples the surface of rigid bodies with boundary particles that interact with fluids. It contains two procedures, that is, surface sampling and sampling relaxation, which insures uniform distribution of particles with less iterations. Furthermore, we present a rigid-fluid coupling scheme integrating individual time stepping to rigid-fluid coupling, which gains an obvious speedup compared to previous method. The experimental results demonstrate the effectiveness of our approach.

Deployment Testing of Flexible Composite Hinges in Bi-Material Beams

Science.gov (United States)

Sauder, Jonathan F.; Trease, Brian

2016-01-01

Composites have excellent properties for strength, thermal stability, and weight. However, they are traditionally highly rigid, and when used in deployable structures require hinges bonded to the composite material, which increases complexity and opportunities for failure. Recent research in composites has found by adding an elastomeric soft matrix, often silicone instead of an epoxy, the composite becomes flexible. This work explores the deployment repeatability of silicone matrix composite hinges which join rigid composite beams. The hinges were found to have sub-millimeter linear deployment repeatability, and sub-degree angular deployment repeatability. Also, an interesting relaxation effect was discovered, as a hinges deployment error would decrease with time.

Fixing the Phillips curve: The case of downward nominal wage rigidity in the US

OpenAIRE

Reitz, Stefan; Slopek, Ulf D.

2012-01-01

Whereas microeconomic studies point to pronounced downward rigidity of nominal wages in the US economy, the standard Phillips curve neglects such a feature. Using a stochastic frontier model we find macroeconomic evidence of a strictly nonnegative error in an otherwise standard Phillips curve in post-war data on the US nonfinancial corporate sector. This error depends on growth in the profit ratio, output, and trend productivity, which should all determine the flexibility of wage adjustments....

Rigidity and resistance of larval- and adult schistosomes-medium interface

Energy Technology Data Exchange (ETDEWEB)

Migliardo, Federica, E-mail: fmigliardo@unime.it [Department of Physics and Earth Sciences, University of Messina, 98166 Messina (Italy); Tallima, Hatem; El Ridi, Rashika [Zoology Department, Faculty of Science, Cairo University, Cairo 12613 (Egypt)

2014-03-28

Graphical abstract: - Highlights: • Schistosoma larvae and worms are studied by neutron scattering. • Measurements on larvae were repeated after one day and by increasing temperature. • The flexibility properties of larvae and adult parasites are compared. • The parasite rigidity is related to their resistance to the hostile environment. • Insight into the parasite defense mechanisms to the immune system attack is achieved. - Abstract: Schistosomiasis is second only to malaria in prevalence and severity, and is still a major health problem in many tropical countries worldwide with about 200–300 million cases and with more than 800 million people at risk of infection. Based on these data, the World Health Organization recommends fostering research efforts for understanding at any level the mechanisms of the infection and then decreasing the social and economical impact of schistosomiasis. A key role is played by the parasite apical lipid membrane, which is entirely impervious to the surrounding elements of the immune system. We have previously demonstrated that the interaction between schistosomes and surrounding medium is governed by a parasite surface membrane sphingomyelin-based hydrogen barrier. In the present article, the elastic contribution to the total motion as a function of the exchanged wave-vector Q and the mean square displacement values for Schistosoma mansoni larvae and worms and Schistosomahaematobium worms have been evaluated by quasi elastic neutron scattering (QENS). The results point out that S. mansoni larvae show a smaller mean square displacement in comparison to S. mansoni and S. haematobium worms. These values increased by repeating the measurements after one day. These differences, which are analogous to those observed for the diffusion coefficient we previously evaluated, are interpreted in terms of rigidity of the parasite-medium interaction. S. mansoni larvae are the most rigid systems, while S. haematobium worms are the most

Effect of flexibility on the growth of concentration fluctuations in a suspension of sedimenting fibers: Particle simulations

Energy Technology Data Exchange (ETDEWEB)

Manikantan, Harishankar; Saintillan, David [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States)

2016-01-15

Three-dimensional numerical simulations are performed to study the stability of a sedimenting suspension of weakly flexible fibers. It is well known that a suspension of rigid rods sedimenting under gravity at low Reynolds number is unstable to concentration fluctuations owing to hydrodynamic interactions. Flexible fibers, however, reorient while settling and even weak flexibility can alter their collective dynamics. In our recent work [Manikantan et al., “The instability of a sedimenting suspension of weakly flexible fibres,” J. Fluid Mech. 756, 935–964 (2014)], we developed a mean-field theory to predict the linear stability of such a system. Here, we verify these predictions using accurate and efficient particle simulations based on a slender-body model. We also demonstrate the mechanisms by which flexibility-induced reorientation alters suspension microstructure, and through it, its stability. Specifically, we first show that the anisotropy of the base state in the case of a suspension of flexible fibers has a destabilizing effect compared to a suspension of rigid rods. Second, a conflicting effect of flexibility is also shown to suppress particle clustering and slow down the growth of the instability. The relative magnitude of filament flexibility and rotational Brownian motion dictates which effect dominates, and our simulations qualitatively follow theoretically predicted trends. The mechanism for either effects is tied to the flexibility-induced reorientation of particles, which we illustrate using velocity and orientation statistics from our simulations. Finally, we also show that, in the case of an initially homogeneous and isotropic suspension, flexibility always acts to suppress the growth of the instability.

Effect of flexibility on the growth of concentration fluctuations in a suspension of sedimenting fibers: Particle simulations

International Nuclear Information System (INIS)

Manikantan, Harishankar; Saintillan, David

2016-01-01

Three-dimensional numerical simulations are performed to study the stability of a sedimenting suspension of weakly flexible fibers. It is well known that a suspension of rigid rods sedimenting under gravity at low Reynolds number is unstable to concentration fluctuations owing to hydrodynamic interactions. Flexible fibers, however, reorient while settling and even weak flexibility can alter their collective dynamics. In our recent work [Manikantan et al., “The instability of a sedimenting suspension of weakly flexible fibres,” J. Fluid Mech. 756, 935–964 (2014)], we developed a mean-field theory to predict the linear stability of such a system. Here, we verify these predictions using accurate and efficient particle simulations based on a slender-body model. We also demonstrate the mechanisms by which flexibility-induced reorientation alters suspension microstructure, and through it, its stability. Specifically, we first show that the anisotropy of the base state in the case of a suspension of flexible fibers has a destabilizing effect compared to a suspension of rigid rods. Second, a conflicting effect of flexibility is also shown to suppress particle clustering and slow down the growth of the instability. The relative magnitude of filament flexibility and rotational Brownian motion dictates which effect dominates, and our simulations qualitatively follow theoretically predicted trends. The mechanism for either effects is tied to the flexibility-induced reorientation of particles, which we illustrate using velocity and orientation statistics from our simulations. Finally, we also show that, in the case of an initially homogeneous and isotropic suspension, flexibility always acts to suppress the growth of the instability

Rigidly foldable origami gadgets and tessellations

Science.gov (United States)

Evans, Thomas A.; Lang, Robert J.; Magleby, Spencer P.; Howell, Larry L.

2015-01-01

Rigidly foldable origami allows for motion where all deflection occurs at the crease lines and facilitates the application of origami in materials other than paper. In this paper, we use a recently discovered method for determining rigid foldability to identify existing flat-foldable rigidly foldable tessellations, which are also categorized. We introduce rigidly foldable origami gadgets which may be used to modify existing tessellations or to create new tessellations. Several modified and new rigidly foldable tessellations are presented. PMID:26473037

Broadband and flexible acoustic focusing by metafiber bundles

Science.gov (United States)

Sun, Hong-Xiang; Chen, Jia-He; Ge, Yong; Yuan, Shou-Qi; Liu, Xiao-Jun

2018-06-01

We report a broadband and flexible acoustic focusing through metafiber bundles in air, in which each metafiber consists of eight circular and narrow rectangular cavities. The fractional bandwidth of the acoustic focusing could reach about 0.2, which arises from the eigenmodes of the metafiber structure. Besides, owing to the flexible characteristic of the metafibers, the focus position can be manipulated by bending the metafiber bundles, and the metafiber bundles could bypass rigid scatterers inside the lens structure. More interestingly, the acoustic propagation and focusing directions can be changed by using a designed right-angled direction converter fabricated by the metafibers, and a waveform converter and a focusing lens of the cylindrical acoustic source are realized based on the metafiber bundles. The proposed focusing lens has the advantages of broad bandwidth, flexible structure, and high focusing performance, showing great potentials in versatile applications.

Shaft flexibility effects on aeroelastic stability of a rotating bladed disk

Science.gov (United States)

Khader, Naim; Loewy, Robert

1989-01-01

A comprehensive study of Coriolis forces and shaft flexibility effects on the structural dynamics and aeroelastic stability of a rotating bladed-disk assembly attached to a cantilever, massless, flexible shaft is presented. Analyses were performed for an actual bladed-disk assembly, used as the first stage in the fan of the 'E3' engine. In the structural model, both in-plane and out-of-plane elastic deformation of the bladed-disk assembly were considered relative to their hub, in addition to rigid disk translations and rotations introduced by shaft flexibility. Besides structural coupling between blades (through the flexible disk), additional coupling is introduced through quasisteady aerodynamic loads. Rotational effects are accounted for throughout the work, and some mode shapes for the whole structure are presented at a selected rpm.

Flexible Multi-Numerology Systems for 5G New Radio

OpenAIRE

Yazar, Ahmet; Peköz, Berker; Arslan, Hüseyin

2018-01-01

The physical layer of 5G cellular communications systems is designed to achieve better flexibility in an effort to support diverse services and user requirements. OFDM waveform parameters are enriched with flexible multi-numerology structures. This paper describes the differences between Long Term Evolution (LTE) systems and new radio (NR) from the flexibility perspective. Research opportunities for multi-numerology systems are presented in a structured manner. Finally, inter-numerology inter...

Design of a flexible tactile sensor for classification of rigid and deformable objects

DEFF Research Database (Denmark)

Drimus, Alin; Kootstra, Gert; Bilberg, Arne

2014-01-01

of the sensor in an active object-classification system. A robotic gripper with two sensors mounted on its fingers performs a palpation procedure on a set of objects. By squeezing an object, the robot actively explores the material properties, and the system acquires tactile information corresponding......For both humans and robots, tactile sensing is important for interaction with the environment: it is the core sensing used for exploration and manipulation of objects. In this paper, we present a novel tactile-array sensor based on flexible piezoresistive rubber.We describe the design of the sensor...... and data acquisition system.We evaluate the sensitivity and robustness of the sensor, and show that it is consistent over time with little relaxation. Furthermore, the sensor has the benefit of being flexible, having a high resolution, it is easy to mount, and simple to manufacture. We demonstrate the use...

Flexible technology for Electronics: Its Derivatives and Possibilities

OpenAIRE

Deovrat Phal; Akshay Narkar

2014-01-01

With the inkjet printing technology becoming more popular, integration of circuits developed on flexible substrates which are easily embedded inside the machine as against the rigid PCB circuits is becoming more prevalent. Much of the research has been done in applications of such circuits in human body implants or for other low cost applications. This paper concentrates particularly on applications of such circuits in the field of consumer electronics, disposable electronics,...

Effects of Flexible Dry Electrode Design on Electrodermal Activity Stimulus Response Detection.

Science.gov (United States)

Haddad, Peter A; Servati, Amir; Soltanian, Saeid; Ko, Frank; Servati, Peyman

2017-12-01

The focus of this research is to evaluate the effects of design parameters including surface area, distance between and geometry of dry flexible electrodes on electrodermal activity (EDA) stimulus response detection. EDA is a result of the autonomic nervous system being stimulated, which causes sweat and changes the electrical characteristics of the skin. Standard silver/silver chloride (Ag/AgCl) EDA electrodes are rigid and lack conformability in contact with skin. In this study, flexible dry Ag/AgCl EDA electrodes were fabricated on a compliant substrate, used to monitor EDA stimulus responses and compared to results simultaneously collected by rigid dry Ag/AgCl electrodes. A repeatable fabrication process for flexible Ag/AgCl electrodes has been established. Surface area, distance between and geometry of electrodes are shown to affect the detectability of the EDA response and the minimum number of sweat glands to be covered by the electrodes has been estimated at 140, or more, in order to maintain functionality. The optimal flexible EDA electrode is a serpentine design with a 0.15 cm 2 surface area and a 0.20 cm distance with an average Pearson correlation coefficient of . Fabrication of flexible electrodes is described and an understanding of the effects of electrode designs on the EDA stimulus response detection has been established and is potentially related to the coverage of sweat glands. This work presents a novel systematic approach to understand the effects of electrode designs on monitoring EDA which is of importance for the design of wearable EDA monitoring devices.

Matrix rigidity induces osteolytic gene expression of metastatic breast cancer cells.

Directory of Open Access Journals (Sweden)

Nazanin S Ruppender

Full Text Available Nearly 70% of breast cancer patients with advanced disease will develop bone metastases. Once established in bone, tumor cells produce factors that cause changes in normal bone remodeling, such as parathyroid hormone-related protein (PTHrP. While enhanced expression of PTHrP is known to stimulate osteoclasts to resorb bone, the environmental factors driving tumor cells to express PTHrP in the early stages of development of metastatic bone disease are unknown. In this study, we have shown that tumor cells known to metastasize to bone respond to 2D substrates with rigidities comparable to that of the bone microenvironment by increasing expression and production of PTHrP. The cellular response is regulated by Rho-dependent actomyosin contractility mediated by TGF-ß signaling. Inhibition of Rho-associated kinase (ROCK using both pharmacological and genetic approaches decreased PTHrP expression. Furthermore, cells expressing a dominant negative form of the TGF-ß receptor did not respond to substrate rigidity, and inhibition of ROCK decreased PTHrP expression induced by exogenous TGF-ß. These observations suggest a role for the differential rigidity of the mineralized bone microenvironment in early stages of tumor-induced osteolysis, which is especially important in metastatic cancer since many cancers (such as those of the breast and lung preferentially metastasize to bone.

Room temperature phosphorescence study on the structural flexibility of single tryptophan containing proteins

Science.gov (United States)

Kowalska-Baron, Agnieszka; Gałęcki, Krystian; Wysocki, Stanisław

2015-01-01

In this study, we have undertaken efforts to find correlation between phosphorescence lifetimes of single tryptophan containing proteins and some structural indicators of protein flexibility/rigidity, such as the degree of tryptophan burial or its exposure to solvent, protein secondary and tertiary structure of the region of localization of tryptophan as well as B factors for tryptophan residue and its immediate surroundings. Bearing in mind that, apart from effective local viscosity of the protein/solvent matrix, the other factor that concur in determining room temperature tryptophan phosphorescence (RTTP) lifetime in proteins is the extent of intramolecular quenching by His, Cys, Tyr and Trp side chains, the crystallographic structures derived from the Brookhaven Protein Data Bank were also analyzed concentrating on the presence of potentially quenching amino acid side chains in the close proximity of the indole chromophore. The obtained results indicated that, in most cases, the phosphorescence lifetimes of tryptophan containing proteins studied tend to correlate with the above mentioned structural indicators of protein rigidity/flexibility. This correlation is expected to provide guidelines for the future development of phosphorescence lifetime-based method for the prediction of structural flexibility of proteins, which is directly linked to their biological function.

Two-Link Flexible Manipulator Control Using Sliding Mode Control Based Linear Matrix Inequality

Science.gov (United States)

Zulfatman; Marzuki, Mohammad; Alif Mardiyah, Nur

2017-04-01

Two-link flexible manipulator is a manipulator robot which at least one of its arms is made of lightweight material and not rigid. Flexible robot manipulator has some advantages over the rigid robot manipulator, such as lighter, requires less power and costs, and to result greater payload. However, suitable control algorithm to maintain the two-link flexible robot manipulator in accurate positioning is very challenging. In this study, sliding mode control (SMC) was employed as robust control algorithm due to its insensitivity on the system parameter variations and the presence of disturbances when the system states are sliding on a sliding surface. SMC algorithm was combined with linear matrix inequality (LMI), which aims to reduce the effects of chattering coming from the oscillation of the state during sliding on the sliding surface. Stability of the control algorithm is guaranteed by Lyapunov function candidate. Based on simulation works, SMC based LMI resulted in better performance improvements despite the disturbances with significant chattering reduction. This was evident from the decline of the sum of squared tracking error (SSTE) and the sum of squared of control input (SSCI) indexes respectively 25.4% and 19.4%.

Investigation on the Acoustic Absorption of Flexible Micro-Perforated Panel with Ultra-Micro Perforations

Science.gov (United States)

Li, Guoxin; Tang, Xiaoning; Zhang, Xiaoxiao; Qian, Y. J.; Kong, Deyi

2017-11-01

Flexible micro-perforated panel has unique advantages in noise reduction due to its good flexibility compared with traditional rigid micro-perforated panel. In this paper, flexible micro-perforated panel was prepared by computer numerical control (CNC) milling machine. Three kinds of plastics including polyvinylchloride (PVC), polyethylene terephthalate (PET), and polyimide (PI) were taken as the matrix materials to prepare flexible micro-perforated panel. It has been found that flexible micro-perforated panel made of PET possessing good porosity and proper density, elastic modulus and poisson ratio exhibited the best acoustic absorption properties. The effects of various structural parameters including perforation diameter, perforation ratio, thickness and air gap have also been investigated, which would be helpful to the optimization of acoustic absorption properties.

Intracavitary radiotherapy of cervix carcinoma with flexible applicators after vesicovaginal interposition operation of the uterus

International Nuclear Information System (INIS)

Busch, M. II; Burmester, U.; Matthaei, D.; Duehmke, E.; Meden, H.; Kuhn, K.

1991-01-01

Advantages of new flexible intracervical applicators treating cervical cancer with high dose rate afterloading brachytherapy are reported: The insertion of the flexible applicator is usually possible without anesthesia and dilatation of the cervix. Therefore the treatment can be performed on an outpatient basis. The risks of perforation and infection are minimal. Dosimetry and documentation of the applicator geometry are possible, if the planning system allows the definition of individual curves of an individual applicator. We now prefer flexible applicators instead of rigid steel applicators treating cervix carcinoma. (orig.) [de

A local cellular model for growth on quasicrystals

International Nuclear Information System (INIS)

Chidyagwai, Prince; Reiter, Clifford A.

2005-01-01

The growth of real valued cellular automata using a deterministic algorithm on 2-dimensional quasicrystalline structures is investigated. Quasicrystals are intermediate between the rigid organization of crystals and disorganized random structures. Since the quasicrystalline structures may be highly symmetric or not, we are able to obtain highly organized and relatively random growth patterns. This deterministic growth produces dendrite, sector, stellar, regular polygons, round, and random DLA-like structures

Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

Science.gov (United States)

Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

2012-06-26

Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.

Granular shear flows of flexible rod-like particles

Science.gov (United States)

Guo, Y.; Curtis, J.; Wassgren, C.; Ketterhagen, W.; Hancock, B.

2013-06-01

Flexible particles are widely encountered in nature, e.g., stalks of plants, fiberglass particles, and ceramic nanofibers. Early studies indicated that the deformability of particles has a significant impact on the properties of granular materials and fiber suspensions. In this study, shear flows of flexible particles are simulated using the Discrete Element Method (DEM) to explore the effect of particle flexibility on the flow behavior and constitutive laws. A flexible particle is formed by connecting a number of constituent spheres in a straight line using elastic bonds. The forces/moments due to the normal, tangential, bending, and torsional deformation of a bond resist the relative movement between two bonded constituent spheres. The bond stiffness determines how difficult it is to make a particle deform, and the bond damping accounts for the energy dissipation in the particle vibration process. The simulation results show that elastically bonded particles have smaller coefficients of restitution compared to rigidly connected particles, due to the fact that kinetic energy is partially converted to potential energy in a contact between flexible particles. The coefficient of restitution decreases as the bond stiffness decreases and the bond damping coefficient increases. As a result, smaller stresses are obtained for granular flows of the flexible particles with smaller bond stiffness and larger bond damping coefficient.

Development of a flexible and bendable vibrotactile actuator based on wave-shaped poly(vinyl chloride)/acetyl tributyl citrate gels for wearable electronic devices

Science.gov (United States)

Park, Won-Hyeong; Bae, Jin Woo; Shin, Eun-Jae; Kim, Sang-Youn

2016-11-01

The paradigm of consumer electronic devices is being shifted from rigid hand-held devices to flexible/wearable devices in search of benefits such as enhanced usability and portability, excellent wear characteristics, and more functions in less space. However, the fundamental incompatibility of flexible/wearable devices and a rigid actuator brought forth a new issue obstructing commercialization of flexible/wearable devices. In this paper, we propose a new wave-shaped eco-friendly PVC gel, and a new flexible and bendable vibrotactile actuator that could easily be applied to wearable electronic devices. We explain the vibration mechanism of the proposed vibrotactile actuator and investigate its influence on the content of plasticizer for the performance of the proposed actuator. An experiment for measuring vibrational amplitude was conducted over a wide frequency range. The experiment clearly showed that the proposed vibrotactile actuator could create a variety of haptic sensations in wearable devices.

Fluid elastic instability tests on an array of tubes preferentially flexible in the flow direction

International Nuclear Information System (INIS)

Mureithi, N.W.; Zhang, C.; Pettigrew, M.J.

2004-01-01

The present work is motivated by the observation that, in the presence of flat bar supports (AVBs), U-tubes in steam generators and heat exchangers are not positively restrained in the in-plane direction. The stability behavior of a rotated triangular array is investigated in detail in the work presented here. Tubes within the array are flexible only in the flow direction. Tests are conducted with a fully flexible array, a single flexible tube, and a finite number of flexible tubes at several locations within the otherwise rigid array. In all cases tube flexibility is purely in the flow direction. The fully flexible array is shown to undergo fluid-elastic instability. Despite the unidirectional flexibility constraint, the critical instability velocity is of the same order of magnitude when compared with previous tests on an unconstrained fully flexible array. A single flexible tube, on the other hand, is found to be stable. Results of tests on partially flexible array configurations are also presented. (authors)

Encountered-Type Haptic Interface for Representation of Shape and Rigidity of 3D Virtual Objects.

Science.gov (United States)

Takizawa, Naoki; Yano, Hiroaki; Iwata, Hiroo; Oshiro, Yukio; Ohkohchi, Nobuhiro

2017-01-01

This paper describes the development of an encountered-type haptic interface that can generate the physical characteristics, such as shape and rigidity, of three-dimensional (3D) virtual objects using an array of newly developed non-expandable balloons. To alter the rigidity of each non-expandable balloon, the volume of air in it is controlled through a linear actuator and a pressure sensor based on Hooke's law. Furthermore, to change the volume of each balloon, its exposed surface area is controlled by using another linear actuator with a trumpet-shaped tube. A position control mechanism is constructed to display virtual objects using the balloons. The 3D position of each balloon is controlled using a flexible tube and a string. The performance of the system is tested and the results confirm the effectiveness of the proposed principle and interface.

Rigidity and symmetry

CERN Document Server

Weiss, Asia; Whiteley, Walter

2014-01-01

This book contains recent contributions to the fields of rigidity and symmetry with two primary focuses: to present the mathematically rigorous treatment of rigidity of structures, and to explore the interaction of geometry, algebra, and combinatorics. Overall, the book shows how researchers from diverse backgrounds explore connections among the various discrete structures with symmetry as the unifying theme.  Contributions present recent trends and advances in discrete geometry, particularly in the theory of polytopes. The rapid development of abstract polytope theory has resulted in a rich theory featuring an attractive interplay of methods and tools from discrete geometry, group theory, classical geometry, hyperbolic geometry and topology.  The volume will also be a valuable source as an introduction to the ideas of both combinatorial and geometric rigidity theory and its applications, incorporating the surprising impact of symmetry. It will appeal to students at both the advanced undergraduate and gradu...

Elastomeric Cellular Structure Enhanced by Compressible Liquid Filler

Science.gov (United States)

Sun, Yueting; Xu, Xiaoqing; Xu, Chengliang; Qiao, Yu; Li, Yibing

2016-05-01

Elastomeric cellular structures provide a promising solution for energy absorption. Their flexible and resilient nature is particularly relevant to protection of human bodies. Herein we develop an elastomeric cellular structure filled with nanoporous material functionalized (NMF) liquid. Due to the nanoscale infiltration in NMF liquid and its interaction with cell walls, the cellular structure has a much enhanced mechanical performance, in terms of loading capacity and energy absorption density. Moreover, it is validated that the structure is highly compressible and self-restoring. Its hyper-viscoelastic characteristics are elucidated.

Superhydrophobicity enhancement through substrate flexibility

Science.gov (United States)

Vasileiou, Thomas; Gerber, Julia; Prautzsch, Jana; Schutzius, Thomas; Poulikakos, Dimos

2017-11-01

Inspired by manifestations in nature, micro/nanoengineering superhydrophobic surfaces has been the focus of much work. Generally, hydrophobicity is increased through the combined effects of surface texturing and chemistry; being durable, rigid substrate materials are the norm. However, many natural and technical materials are flexible, and the resulting effect on hydrophobicity has been largely unexplored. Here, we show that the rational tuning of flexibility can work collaboratively with the surface micro/nanotexture to enhance liquid repellency performance, defined by impalement and breakup resistance, contact time reduction, and restitution coefficient increase. Reduction in substrate stiffness and areal density imparts immediate acceleration and intrinsic responsiveness to impacting droplets, mitigating the collision and lowering the impalement probability by 60 % without the need for active actuation. We demonstrate the above discoveries with materials ranging from thin steel or polymer sheets to butterfly wings. Partial support of the Swiss National Science Foundation under Grant 162565 and the European Research Council under Advanced Grant 669908 (INTICE) is acknowledged.

Does flexible tunnel drilling affect the femoral tunnel angle measurement after anterior cruciate ligament reconstruction?

NARCIS (Netherlands)

Muller, Bart; Hofbauer, Marcus; Atte, Akere; van Dijk, C. Niek; Fu, Freddie H.

2015-01-01

To quantify the mean difference in femoral tunnel angle (FTA) as measured on knee radiographs between rigid and flexible tunnel drilling after anatomic anterior cruciate ligament (ACL) reconstruction. Fifty consecutive patients that underwent primary anatomic ACL reconstruction with a single femoral

On the dynamics of semi-rigid chains

International Nuclear Information System (INIS)

Rodriguez Talavera, R.; Alexander-Katz, R.

1993-01-01

The dynamics of a semi-rigid polymer chain is studied. The force structure of the chain is derived from the statistics generated through a Wiener measure whose end-to-end distance is that of a Kratky-Porod chain. Additionally, the dissipative terms in the equation of motion will contain, besides the usual Stokes' term, a non-local friction term (internal viscosity) which is quadratic in the normal mode q, in order to take into account the resistance to changes in curvature. The analytical shape of this term is the same as the one introduced by Edwards and Freed. We show that this model of stiff chain reproduces both asymptotic limits: the flexible and the rod limits for the elastic moduli. A form for the internal viscosity coefficient is deduced from a phenomenological approach, which has the right solvent viscosity dependency as obtained by MacInnes. (Author)

Thermally-Induced Structural Disturbances of Rigid Panel Solar Arrays

Science.gov (United States)

Johnston, John D.; Thornton, Earl A.

1997-01-01

The performance of a significant number of spacecraft has been impacted negatively by attitude disturbances resulting from thermally-induced motions of flexible structures. Recent examples of spacecraft affected by these disturbances include the Hubble Space Telescope (HST) and the Upper Atmosphere Research Satellite (UARS). Thermally-induced structural disturbances occur as the result of rapid changes in thermal loading typically initiated as a satellite exits or enters the Earth's shadow. Temperature differences in flexible appendages give rise to structural deformations, which in turn result in disturbance torques reacting back on the spacecraft. Structures which have proven susceptible to these disturbances include deployable booms and solar arrays. This paper investigates disturbances resulting from thermally-induced deformations of rigid panel solar arrays. An analytical model for the thermal-structural response of the solar array and the corresponding disturbance torque are presented. The effect of these disturbances on the attitude dynamics of a simple spacecraft is then investigated using a coupled system of governing equations which includes the effects of thermally-induced deformations. Numerical results demonstrate the effect of varying solar array geometry on the dynamic response of the system.

Analysing the effects of rigid and flexible aircraft dynamics on the ejection of a large store

CSIR Research Space (South Africa)

Jamison, Kevin

2011-09-01

Full Text Available duration ? ERU forces + store weight release causes aircraft ?g-jump? ? Period of ERU force is short enough to excite wing vibration modes ? ERU force/time & front/back force balance important for determining store separation rates from aircraft... ? Constrained motion in other DOF ? Used mass, inertias, CG of aircraft without Katleho ? Used trimmed forces of aircraft with Katleho ? Assumes delay in pilot response to g-jump ? CSIR 2011 Slide 14 Aircraft rigid accelerations Aircraft mass...

Dynamic modeling and hierarchical compound control of a novel 2-DOF flexible parallel manipulator with multiple actuation modes

Science.gov (United States)

Liang, Dong; Song, Yimin; Sun, Tao; Jin, Xueying

2018-03-01

This paper addresses the problem of rigid-flexible coupling dynamic modeling and active control of a novel flexible parallel manipulator (PM) with multiple actuation modes. Firstly, based on the flexible multi-body dynamics theory, the rigid-flexible coupling dynamic model (RFDM) of system is developed by virtue of the augmented Lagrangian multipliers approach. For completeness, the mathematical models of permanent magnet synchronous motor (PMSM) and piezoelectric transducer (PZT) are further established and integrated with the RFDM of mechanical system to formulate the electromechanical coupling dynamic model (ECDM). To achieve the trajectory tracking and vibration suppression, a hierarchical compound control strategy is presented. Within this control strategy, the proportional-differential (PD) feedback controller is employed to realize the trajectory tracking of end-effector, while the strain and strain rate feedback (SSRF) controller is developed to restrain the vibration of the flexible links using PZT. Furthermore, the stability of the control algorithm is demonstrated based on the Lyapunov stability theory. Finally, two simulation case studies are performed to illustrate the effectiveness of the proposed approach. The results indicate that, under the redundant actuation mode, the hierarchical compound control strategy can guarantee the flexible PM achieves singularity-free motion and vibration attenuation within task workspace simultaneously. The systematic methodology proposed in this study can be conveniently extended for the dynamic modeling and efficient controller design of other flexible PMs, especially the emerging ones with multiple actuation modes.

Formation of vortex pairs with hinged rigid flaps at the nozzle exit

Science.gov (United States)

Das, Prashant; Govardhan, Raghuraman; Arakeri, Jaywant

2013-11-01

Biological flows related to aquatic propulsion using pulsed jets, or flow through the valves in a human heart, have received considerable attention in the last two decades. Both these flows are associated with starting jets that occur through biological tissue/membranes that are flexible. Motivated by these flows, we explore in the present work, the effect of passive flexibility of the nozzle exit on vortex generation from a starting jet. The starting jet is generated using a two-dimensional piston cylinder mechanism, the cross-section of the cylinder being rectangular with large aspect ratio. The fluid is pushed out of this cylinder or channel using a computer controlled piston. We introduce flexibility at the channel exit by hinging rigid flaps, which are initially parallel to the channel. The hinge used is such that it provides negligible stiffness or damping, thus allowing for the maximum opening of the flaps due to fluid forces. Using this system, we study both the flap kinematics and the vorticity dynamics downstream of the channel exit. Visualizations show large flap motions as the piston starts and this dramatically changes the vorticity distribution downstream of the flaps, with the formation of up to three different kinds of vortex pairs. This idealized configuration opens new opportunities to look at the effect of flexibility in such biological flows.

Effect of flexibility on flapping wing characteristics under forward flight

International Nuclear Information System (INIS)

Zhu, Jianyang; Jiang, Lin; Zhou, Chaoying; Wang, Chao

2014-01-01

Through two-dimensional numerical simulation and by solving the unsteady incompressible Navier–Stokes (NS) equations, coupled with the structural dynamic equation for the motion of the wing, the effect of flexibility on flapping wing characteristics during forward flight is systematically studied. The flapping wing is considered as a cantilever, which performs the translational and rotational motion at its leading edge, and the other part is passively deformed by the aerodynamic force. The frequency ratio ω* and mass ratio m* are defined and used to characterize the flexibility of the flapping wing. It has been found that an optimal range of the frequency ratio exists in which the flexible wing possesses both a larger propulsive efficiency and lifting efficiency than their rigid counterpart. Also, the flexible wing with the smaller mass ratio may be of benefit to generate thrust, while the larger mass ratio may be of benefit to generate lift. In addition, a stronger leading edge vortex and reattachment vortex are observed around the appropriate flexibility wing’s surface, which therefore leads to better aerodynamic characteristics. (paper)

Dimensionality controls cytoskeleton assembly and metabolism of fibroblast cells in response to rigidity and shape.

Directory of Open Access Journals (Sweden)

Mirjam Ochsner

2010-03-01

Full Text Available Various physical parameters, including substrate rigidity, size of adhesive islands and micro-and nano-topographies, have been shown to differentially regulate cell fate in two-dimensional (2-D cell cultures. Cells anchored in a three-dimensional (3-D microenvironment show significantly altered phenotypes, from altered cell adhesions, to cell migration and differentiation. Yet, no systematic analysis has been performed that studied how the integrated cellular responses to the physical characteristics of the environment are regulated by dimensionality (2-D versus 3-D.Arrays of 5 or 10 microm deep microwells were fabricated in polydimethylsiloxane (PDMS. The actin cytoskeleton was compared for single primary fibroblasts adhering either to microfabricated adhesive islands (2-D or trapped in microwells (3-D of controlled size, shape, and wall rigidity. On rigid substrates (Young's Modulus = 1 MPa, cytoskeleton assembly within single fibroblast cells occurred in 3-D microwells of circular, rectangular, square, and triangular shapes with 2-D projected surface areas (microwell bottom surface area and total surface areas of adhesion (microwell bottom plus wall surface area that inhibited stress fiber assembly in 2-D. In contrast, cells did not assemble a detectable actin cytoskeleton in soft 3-D microwells (20 kPa, regardless of their shapes, but did so on flat, 2-D substrates. The dependency on environmental dimensionality was also reflected by cell viability and metabolism as probed by mitochondrial activities. Both were upregulated in 3-D cultured cells versus cells on 2-D patterns when surface area of adhesion and rigidity were held constant.These data indicate that cell shape and rigidity are not orthogonal parameters directing cell fate. The sensory toolbox of cells integrates mechanical (rigidity and topographical (shape and dimensionality information differently when cell adhesions are confined to 2-D or occur in a 3-D space.

Birationally rigid varieties

CERN Document Server

Pukhlikov, Aleksandr

2013-01-01

Birational rigidity is a striking and mysterious phenomenon in higher-dimensional algebraic geometry. It turns out that certain natural families of algebraic varieties (for example, three-dimensional quartics) belong to the same classification type as the projective space but have radically different birational geometric properties. In particular, they admit no non-trivial birational self-maps and cannot be fibred into rational varieties by a rational map. The origins of the theory of birational rigidity are in the work of Max Noether and Fano; however, it was only in 1970 that Iskovskikh and Manin proved birational superrigidity of quartic three-folds. This book gives a systematic exposition of, and a comprehensive introduction to, the theory of birational rigidity, presenting in a uniform way, ideas, techniques, and results that so far could only be found in journal papers. The recent rapid progress in birational geometry and the widening interaction with the neighboring areas generate the growing interest ...

Numerical study on the power extraction performance of a flapping foil with a flexible tail

Science.gov (United States)

Wu, J.; Shu, C.; Zhao, N.; Tian, F.-B.

2015-01-01

The numerical study on the power extraction performance of a flapping foil with a flexible tail is performed in this work. A NACA0015 airfoil is arranged in a two-dimensional laminar flow and imposed with a synchronous harmonic plunge and pitch rotary motion. A flat plate that is attached to the trailing edge of the foil is utilized to model a tail, and so they are viewed as a whole for the purpose of power extraction. In addition, the tail either is rigid or can deform due to the exerted hydrodynamic forces. To implement numerical simulations, an immersed boundary-lattice Boltzmann method is employed. At a Reynolds number of 1100 and the position of the pitching axis at third chord, the influences of the mass and flexibility of the tail as well as the frequency of motion on the power extraction are systematically examined. It is found that compared to the foil with a rigid tail, the efficiency of power extraction for the foil with a deformable tail can be improved. Based on the numerical analysis, it is indicated that the enhanced plunging component of the power extraction, which is caused by the increased lift force, directly contributes to the efficiency improvement. Since a flexible tail with medium and high masses is not beneficial to the efficiency improvement, a flexible tail with low mass together with high flexibility is recommended in the flapping foil based power extraction system.

On the Modularity of the Intrinsic Flexibility of the µ Opioid Receptor: A Computational Study

Science.gov (United States)

Fossépré, Mathieu; Leherte, Laurence; Laaksonen, Aatto; Vercauteren, Daniel P.

2014-01-01

The µ opioid receptor (µOR), the principal target to control pain, belongs to the G protein-coupled receptors (GPCRs) family, one of the most highlighted protein families due to their importance as therapeutic targets. The conformational flexibility of GPCRs is one of their essential characteristics as they take part in ligand recognition and subsequent activation or inactivation mechanisms. It is assessed that the intrinsic mechanical properties of the µOR, more specifically its particular flexibility behavior, would facilitate the accomplishment of specific biological functions, at least in their first steps, even in the absence of a ligand or any chemical species usually present in its biological environment. The study of the mechanical properties of the µOR would thus bring some indications regarding the highly efficient ability of the µOR to transduce cellular message. We therefore investigate the intrinsic flexibility of the µOR in its apo-form using all-atom Molecular Dynamics simulations at the sub-microsecond time scale. We particularly consider the µOR embedded in a simplified membrane model without specific ions, particular lipids, such as cholesterol moieties, or any other chemical species that could affect the flexibility of the µOR. Our analyses highlighted an important local effect due to the various bendability of the helices resulting in a diversity of shape and volume sizes adopted by the µOR binding site. Such property explains why the µOR can interact with ligands presenting highly diverse structural geometry. By investigating the topology of the µOR binding site, a conformational global effect is depicted: the correlation between the motional modes of the extra- and intracellular parts of µOR on one hand, along with a clear rigidity of the central µOR domain on the other hand. Our results show how the modularity of the µOR flexibility is related to its pre-ability to activate and to present a basal activity. PMID:25549261

Regulation and Flexibility of the Croatian Labour Market

OpenAIRE

Vedran Sosic

2004-01-01

The Croatian Labor Code was significantly reformed in 2003 as a result of extensive negotiations lasting about two years. Proponents of the reform emphasized the supposed rigidity of the labor market, resulting from restrictive employment protection legislation, as a main rationale for the reform. Critics believed that the labor market is much more flexible than often thought due to inadequate enforcement of legislation. This study aims to assess the level of labor market dynamics by construc...

High-performance green flexible electronics based on biodegradable cellulose nanofibril paper.

Science.gov (United States)

Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

2015-05-26

Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.

A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

Energy Technology Data Exchange (ETDEWEB)

Nazockdast, Ehssan, E-mail: ehssan@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Center for Computational Biology, Simons Foundation, New York, NY 10010 (United States); Rahimian, Abtin, E-mail: arahimian@acm.org [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Zorin, Denis, E-mail: dzorin@cs.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Shelley, Michael, E-mail: shelley@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Center for Computational Biology, Simons Foundation, New York, NY 10010 (United States)

2017-01-15

We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid–structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler–Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber–fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a

A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

International Nuclear Information System (INIS)

Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

2017-01-01

We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid–structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler–Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber–fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a

A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

Science.gov (United States)

Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

2017-01-01

We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid-structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler-Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber-fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of

Reliability analysis of stiff versus flexible piping

International Nuclear Information System (INIS)

Lu, S.C.

1985-01-01

The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. The authors then investigated a couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design. They concluded that these changes substantially reduce calculated piping responses and allow piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements. Furthermore, the more flexible piping redesigns are capable of exhibiting reliability levels equal to or higher than the original stiffer design. An investigation of the malfunction of pipe whip restraints confirmed that the malfunction introduced higher thermal stresses and tended to reduce the overall piping reliability. Finally, support and component reliabilities were evaluated based on available fragility data. Results indicated that the support reliability usually exhibits a moderate decrease as the piping flexibility increases. Most on-line pumps and valves showed an insignificant reduction in reliability for a more flexible piping design

Rigidity of Glasses and Macromolecules

Science.gov (United States)

Thorpe, M. F.

1998-03-01

The simple yet powerful ideas of percolation theory have found their way into many different areas of research. In this talk we show how RIGIDITY PERCOLATION can be studied at a similar level of sophistication, using a powerful new program THE PEBBLE GAME (D. J. Jacobs and M. F. Thorpe, Phys. Rev. E) 53, 3682 (1996). that uses an integer algorithm. This program can analyse the rigidity of two and three dimensional networks containing more than one million bars and joints. We find the total number of floppy modes, and find the critical behavior as the network goes from floppy to rigid as more bars are added. We discuss the relevance of this work to network glasses, and how it relates to experiments that involve the mechanical properties like hardness and elasticity of covalent glassy networks like Ge_xAs_ySe_1-x-y and dicuss recent experiments that suggest that the rigidity transition may be first order (Xingwei Feng, W. J.Bresser and P. Boolchand, Phys. Rev. Lett 78), 4422 (1997).. This approach is also useful in macromolecules and proteins, where detailed information about the rigid domain structure can be obtained.

Matrix remodeling between cells and cellular interactions with collagen bundle

Science.gov (United States)

Kim, Jihan; Sun, Bo

When cells are surrounded by complex environment, they continuously probe and interact with it by applying cellular traction forces. As cells apply traction forces, they can sense rigidity of their local environment and remodel the matrix microstructure simultaneously. Previous study shows that single human carcinoma cell (MDA-MB-231) remodeled its surrounding extracellular matrix (ECM) and the matrix remodeling was reversible. In this study we examined the matrix microstructure between cells and cellular interaction between them using quantitative confocal microscopy. The result shows that the matrix microstructure is the most significantly remodeled between cells consisting of aligned, and densified collagen fibers (collagen bundle)., the result shows that collagen bundle is irreversible and significantly change micromechanics of ECM around the bundle. We further examined cellular interaction with collagen bundle by analyzing dynamics of actin and talin formation along with the direction of bundle. Lastly, we analyzed dynamics of cellular protrusion and migrating direction of cells along the bundle.

Floating substructure flexibility of large-volume 10MW offshore wind turbine platforms in dynamic calculations

DEFF Research Database (Denmark)

Borg, Michael; Hansen, Anders Melchior; Bredmose, Henrik

2016-01-01

to the extent that it becomes relevant to include in addition to the standard rigid body substructure modes which are typically described through linear radiation-diffraction theory. This paper describes a method for the inclusion of substructural flexibility in aero-hydro-servo-elastic dynamic simulations...

Analysis of flexible structures under lateral impact

International Nuclear Information System (INIS)

Ramirez, D. F.; Razavi, H.

2012-01-01

Three methods for analysis of flexible structures under lateral impact are presented. The first proposed method (Method A) consists of: (1) modifying an available deceleration on a rigid target with conservation principles to account for structural flexibility; and (2) transient nonlinear analysis of the structure with the corrected forcing function. The second proposed method (Method B) is similar to Method A in obtaining the forcing function but it solves the equations of motion of an idealized two-degree-of-freedom system instead of directly using conservation principles. The last method simply provides the maximum force in the structure using the conservation of energy and linear momentum. A coupled simulation is also performed in LS-DYNA and compared against the proposed methods. A case study is presented to illustrate the applicability of all three methods and the LS-DYNA simulation. (authors)

Rigidity-tuning conductive elastomer

Science.gov (United States)

Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

2015-06-01

We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE-PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ˜6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE-PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE-PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation.

Rigidity-tuning conductive elastomer

International Nuclear Information System (INIS)

Shan, Wanliang; Diller, Stuart; Tutcuoglu, Abbas; Majidi, Carmel

2015-01-01

We introduce a conductive propylene-based elastomer (cPBE) that rapidly and reversibly changes its mechanical rigidity when powered with electrical current. The elastomer is rigid in its natural state, with an elastic (Young’s) modulus of 175.5 MPa, and softens when electrically activated. By embedding the cPBE in an electrically insulating sheet of polydimethylsiloxane (PDMS), we create a cPBE–PDMS composite that can reversibly change its tensile modulus between 37 and 1.5 MPa. The rigidity change takes ∼6 s and is initiated when a 100 V voltage drop is applied across the two ends of the cPBE film. This magnitude of change in elastic rigidity is similar to that observed in natural skeletal muscle and catch connective tissue. We characterize the tunable load-bearing capability of the cPBE–PDMS composite with a motorized tensile test and deadweight experiment. Lastly, we demonstrate the ability to control the routing of internal forces by embedding several cPBE–PDMS ‘active tendons’ into a soft robotic pneumatic bending actuator. Selectively activating the artificial tendons controls the neutral axis and direction of bending during inflation. (paper)

Flexible Multibody Systems Models Using Composite Materials Components

International Nuclear Information System (INIS)

Neto, Maria Augusta; Ambr'osio, Jorge A. C.; Leal, Rog'erio Pereira

2004-01-01

The use of a multibody methodology to describe the large motion of complex systems that experience structural deformations enables to represent the complete system motion, the relative kinematics between the components involved, the deformation of the structural members and the inertia coupling between the large rigid body motion and the system elastodynamics. In this work, the flexible multibody dynamics formulations of complex models are extended to include elastic components made of composite materials, which may be laminated and anisotropic. The deformation of any structural member must be elastic and linear, when described in a coordinate frame fixed to one or more material points of its domain, regardless of the complexity of its geometry. To achieve the proposed flexible multibody formulation, a finite element model for each flexible body is used. For the beam composite material elements, the sections properties are found using an asymptotic procedure that involves a two-dimensional finite element analysis of their cross-section. The equations of motion of the flexible multibody system are solved using an augmented Lagrangian formulation and the accelerations and velocities are integrated in time using a multi-step multi-order integration algorithm based on the Gear method

Symmetry numbers for rigid, flexible, and fluxional molecules: theory and applications.

Science.gov (United States)

Gilson, Michael K; Irikura, Karl K

2010-12-16

The use of molecular simulations and ab initio calculations to predict thermodynamic properties of molecules has become routine. Such methods rely upon an accurate representation of the molecular partition function or configurational integral, which in turn often includes a rotational symmetry number. However, the reason for including the symmetry number is unclear to many practitioners, and there is also a need for a general prescription for evaluating the symmetry numbers of flexible molecules, i.e., for molecules with thermally active internal degrees of freedom, such as internal rotors. Surprisingly, we have been unable to find any complete and convincing explanations of these important issues in textbooks or the journal literature. The present paper aims to explain why symmetry numbers are needed and how their values should be determined. Both classical and quantum approaches are provided.

Dynamic bending of bionic flexible body driven by pneumatic artificial muscles(PAMs) for spinning gait of quadruped robot

Science.gov (United States)

Lei, Jingtao; Yu, Huangying; Wang, Tianmiao

2016-01-01

The body of quadruped robot is generally developed with the rigid structure. The mobility of quadruped robot depends on the mechanical properties of the body mechanism. It is difficult for quadruped robot with rigid structure to achieve better mobility walking or running in the unstructured environment. A kind of bionic flexible body mechanism for quadruped robot is proposed, which is composed of one bionic spine and four pneumatic artificial muscles(PAMs). This kind of body imitates the four-legged creatures' kinematical structure and physical properties, which has the characteristic of changeable stiffness, lightweight, flexible and better bionics. The kinematics of body bending is derived, and the coordinated movement between the flexible body and legs is analyzed. The relationship between the body bending angle and the PAM length is obtained. The dynamics of the body bending is derived by the floating coordinate method and Lagrangian method, and the driving force of PAM is determined. The experiment of body bending is conducted, and the dynamic bending characteristic of bionic flexible body is evaluated. Experimental results show that the bending angle of the bionic flexible body can reach 18°. An innovation body mechanism for quadruped robot is proposed, which has the characteristic of flexibility and achieve bending by changing gas pressure of PAMs. The coordinated movement of the body and legs can achieve spinning gait in order to improve the mobility of quadruped robot.

Neurobiology: motor control of flexible octopus arms.

Science.gov (United States)

Sumbre, Germán; Fiorito, Graziano; Flash, Tamar; Hochner, Binyamin

2005-02-10

Animals with rigid skeletons can rely on several mechanisms to simplify motor control--for example, they have skeletal joints that reduce the number of variables and degrees of freedom that need to be controlled. Here we show that when the octopus uses one of its long and highly flexible arms to transfer an object from one place to another, it employs a vertebrate-like strategy, temporarily reconfiguring its arm into a stiffened, articulated, quasi-jointed structure. This indicates that an articulated limb may provide an optimal solution for achieving precise, point-to-point movements.

Partially flexible MEMS neural probe composed of polyimide and sucrose gel for reducing brain damage during and after implantation

International Nuclear Information System (INIS)

Jeon, Myounggun; Yoon, Eui-Sung; Cho, Il-Joo; Cho, Jeiwon; Jung, Dahee; Kim, Yun Kyung; Shin, Sehyun

2014-01-01

This paper presents a flexible microelectromechanical systems (MEMS) neural probe that minimizes neuron damage and immune response, suitable for chronic recording applications. MEMS neural probes with various features such as high electrode densities have been actively investigated for neuron stimulation and recording to study brain functions. However, successful recording of neural signals in chronic application using rigid silicon probes still remains challenging because of cell death and macrophages accumulated around the electrodes over time from continuous brain movement. Thus, in this paper, we propose a new flexible MEMS neural probe that consists of two segments: a polyimide-based, flexible segment for connection and a rigid segment composed of thin silicon for insertion. While the flexible connection segment is designed to reduce the long-term chronic neuron damage, the thin insertion segment is designed to minimize the brain damage during the insertion process. The proposed flexible neural probe was successfully fabricated using the MEMS process on a silicon on insulator wafer. For a successful insertion, a biodegradable sucrose gel is coated on the flexible segment to temporarily increase the probe stiffness to prevent buckling. After the insertion, the sucrose gel dissolves inside the brain exposing the polyimide probe. By performing an insertion test, we confirm that the flexible probe has enough stiffness. In addition, by monitoring immune responses and brain histology, we successfully demonstrate that the proposed flexible neural probe incurs fivefold less neural damage than that incurred by a conventional silicon neural probe. Therefore, the presented flexible neural probe is a promising candidate for recording stable neural signals for long-time chronic applications. (paper)

CT-3DRA registration for radiosurgery treatments: a comparison among rigid, affine and non rigid approaches

International Nuclear Information System (INIS)

Stancanello, J.; Loeckx, D.; Francescon, P.; Calvedon, C.; Avanzo, M.; Cora, S.; Scalchi, P.; Cerveri, P.; Ferrigno, G.

2004-01-01

This work aims at comparing rigid, affine and Local Non Rigid (LNR) CT-3D Rotational Angiography (CT-3DRA) registrations based on mutual information. 10 cranial and 1 spinal cases have been registered by rigid and affine transformations; while LNR has been applied to the cases where residual deformation must be corrected. An example of CT-3DRA registration without regularization term and an example of LNR using the similarity criterion and the regularization term as well as 3D superposition of the 3DRA before and after the registration without the regularization term are presented. All the registrations performed by rigid transformation converged to an acceptable solution. The results about the robustness test in axial direction are reported. Conclusions: For cranial cases, affine transformation endowed with threshold-segmentation pre-processing can be considered the most favourable solution for almost all registrations; for some cases, LNR provides more accurate results. For the spinal case rigid transformation is the most suitable when immobilizing patient during examinations; in this case the increase of accuracy by using LNR registrations seems to be not significant

New flexible endoscope for otologic application

Science.gov (United States)

Marchan, Mark L.

1993-07-01

Endoscopy has become an important procedure in many medical specialties. For the Otologist, however, space limitations within the ear have restricted development of endoscopic procedures. The desire for minimally invasive techniques in Otology has demonstrated itself through the work of numerous physicians who have performed procedures ranging from diagnostic inspection of the middle ear to viewing the interior of the cochlea. To assist in performing such endoscopic procedures, Xomed-Treace has developed a line of flexible fiberoptic endoscopes for use by the Otologist. These scopes combine illumination and imaging fiber bundles within a small diameter unit ranging in size from 0.8 mm to 1.2 mm. The 1.2 mm scope is produced with an angled, rigid stainless steel sheath. The 0.8 mm scope is flexible with the ability to articulate 120 degree(s) in one direction. The fiberscopes have been designed for the Otologist to produce a good resolution image while allowing ease of operation through ergonomics and consideration of the surgical anatomy.

In silico single-molecule manipulation of DNA with rigid body dynamics.

Directory of Open Access Journals (Sweden)

Pascal Carrivain

2014-02-01

Full Text Available We develop a new powerful method to reproduce in silico single-molecule manipulation experiments. We demonstrate that flexible polymers such as DNA can be simulated using rigid body dynamics thanks to an original implementation of Langevin dynamics in an open source library called Open Dynamics Engine. We moreover implement a global thermostat which accelerates the simulation sampling by two orders of magnitude. We reproduce force-extension as well as rotation-extension curves of reference experimental studies. Finally, we extend the model to simulations where the control parameter is no longer the torsional strain but instead the torque, and predict the expected behavior for this case which is particularly challenging theoretically and experimentally.

Torsional Rigidity of Minimal Submanifolds

DEFF Research Database (Denmark)

Markvorsen, Steen; Palmer, Vicente

2006-01-01

We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...

Wage flexibility in Britain: some micro and macro evidence

OpenAIRE

Mark E Schweitzer

2007-01-01

This paper uses the British New Earnings Survey (NES) to derive both macro and micro measures of wage rigidities. The data set spans the 1975-2000 period, with wage observations covering approximately 1% of the British workforce. Using this data set, we consider whether wages have become more flexible in recent years. Evidence drawn from macroeconomic wage equation estimates suggests that, while the relationship between wages and unemployment seems to have changed, the responsiveness of wages...

Modern trunnions are more flexible: a mechanical analysis of THA taper designs.

Science.gov (United States)

Porter, David A; Urban, Robert M; Jacobs, Joshua J; Gilbert, Jeremy L; Rodriguez, José A; Cooper, H John

2014-12-01

There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in contemporary THAs. Although taper corrosion involves a complex interplay of many factors, a previous study suggested that a decrease in flexural rigidity of the femoral trunnion may be associated with an increased likelihood of corrosion at retrieval. By analyzing a large revision retrieval database of femoral stems released during a span of three decades, we asked: (1) how much does flexural rigidity vary among different taper designs; (2) what is the contribution of taper geometry alone to flexural rigidity of the femoral trunnion; and (3) how have flexural rigidity and taper length changed with time in this group of revised retrievals? A dual-center retrieval analysis of 85 modular femoral stems released between 1983 and 2012 was performed, and the flexural rigidity and length of the femoral trunnions were determined. These stems were implanted between 1991 and 2012 and retrieved at revision or removal surgery between 2004 and 2012. There were 10 different taper designs made from five different metal alloys from 16 manufacturers. Digital calipers were used to measure taper geometries by two independent observers. Median flexural rigidity was 228 N-m(2); however, there was a wide range of values among the various stems spanning nearly an order of magnitude between the most flexible (80 N-m(2)) and most rigid (623 N-m(2)) trunnions, which was partly attributable to the taper geometry and to the material properties of the base alloy. There was a negative correlation between flexural rigidity and length of the trunnion and release date of the stem. There is wide variability in flexural rigidity of various taper designs, with a trend toward trunnions becoming shorter and less rigid with time. This temporal trend may partly explain why taper corrosion is being seen with increasing frequency in modern THAs.

The Influence of Chordwise Flexibility on the Flow Structure and Streamwise Force of a Sinusoidally Pitching Airfoil

Science.gov (United States)

Olson, David Arthur

Many natural flyers and swimmers need to exploit unsteady mechanisms in order to generate sufficient aerodynamic forces for sustained flight and propulsion. This is, in part, due to the low speed and length scales at which they typically operate. In this low Reynolds number regime, there are many unanswered questions on how existing aerodynamic theory for both steady and unsteady flows can be applied. Additionally, most of these natural flyers and swimmers have deformable wing/fin structures, three dimensional wing planforms, and exhibit complex kinematics during motion. While some biologically-inspired studies seek to replicate these complex structures and kinematics in the laboratory or in numerical simulations, it becomes difficult to draw explicit connections to the existing knowledge base of classical unsteady aerodynamic theory due to the complexity of the problems. In this experimental study, wing kinematics, structure, and planform are greatly simplified to investigate the effect of chordwise flexibility on the streamwise force (thrust) and wake behavior of a sinusoidally pitching airfoil. The study of flexibility in the literature has typically utilized flat plates with varying thicknesses or lengths to change their chordwise flexibility. This choice introduces additional complexities when comparing to the wealth of knowledge originally developed on streamlined aerodynamic shapes. The current study capitalizes on the recent developments in 3D printer technology to create accurate shapes out of materials with varying degrees of flexibility by creating two standard NACA 0009 airfoils: one rigid and one flexible. Each of the two airfoils are sinusoidally pitched about the quarter chord over a range of oscillation amplitudes and frequencies while monitoring the deformation of the airfoil. The oscillation amplitude is selected to be small enough such that leading edge vortices do not form, and the vortical structures in the wake are formed from the trailing

Modeling and Simulation of Variable Mass, Flexible Structures

Science.gov (United States)

Tobbe, Patrick A.; Matras, Alex L.; Wilson, Heath E.

2009-01-01

The advent of the new Ares I launch vehicle has highlighted the need for advanced dynamic analysis tools for variable mass, flexible structures. This system is composed of interconnected flexible stages or components undergoing rapid mass depletion through the consumption of solid or liquid propellant. In addition to large rigid body configuration changes, the system simultaneously experiences elastic deformations. In most applications, the elastic deformations are compatible with linear strain-displacement relationships and are typically modeled using the assumed modes technique. The deformation of the system is approximated through the linear combination of the products of spatial shape functions and generalized time coordinates. Spatial shape functions are traditionally composed of normal mode shapes of the system or even constraint modes and static deformations derived from finite element models of the system. Equations of motion for systems undergoing coupled large rigid body motion and elastic deformation have previously been derived through a number of techniques [1]. However, in these derivations, the mode shapes or spatial shape functions of the system components were considered constant. But with the Ares I vehicle, the structural characteristics of the system are changing with the mass of the system. Previous approaches to solving this problem involve periodic updates to the spatial shape functions or interpolation between shape functions based on system mass or elapsed mission time. These solutions often introduce misleading or even unstable numerical transients into the system. Plus, interpolation on a shape function is not intuitive. This paper presents an approach in which the shape functions are held constant and operate on the changing mass and stiffness matrices of the vehicle components. Each vehicle stage or component finite element model is broken into dry structure and propellant models. A library of propellant models is used to describe the

Flexible diodes for radio frequency (RF) electronics: a materials perspective

KAUST Repository

Semple, James; Georgiadou, Dimitra G; Wyatt-Moon, Gwenhivir; Gelinck, Gerwin; Anthopoulos, Thomas D.

2017-01-01

Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.

Flexible diodes for radio frequency (RF) electronics: a materials perspective

KAUST Repository

Semple, James

2017-10-30

Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.

Flexible diodes for radio frequency (RF) electronics: a materials perspective

Science.gov (United States)

Semple, James; Georgiadou, Dimitra G.; Wyatt-Moon, Gwenhivir; Gelinck, Gerwin; Anthopoulos, Thomas D.

2017-12-01

Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.

Flexible thin film magnetoimpedance sensors

International Nuclear Information System (INIS)

Kurlyandskaya, G.V.; Fernández, E.; Svalov, A.; Burgoa Beitia, A.; García-Arribas, A.; Larrañaga, A.

2016-01-01

Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti] 3 /Cu/[FeNi/Ti] 3 films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

Flexible thin film magnetoimpedance sensors

Energy Technology Data Exchange (ETDEWEB)

Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Fernández, E. [BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Svalov, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Burgoa Beitia, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); García-Arribas, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain)

2016-10-01

Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti]{sub 3}/Cu/[FeNi/Ti]{sub 3} films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

Nondestructive determination of the load bearing capacity of rigid pavement structures. Zerstoerungsfreie Tragfaehigkeitsbestimmung fuer starre Deckenkonstruktionen

Energy Technology Data Exchange (ETDEWEB)

Heinrich, U. (Bauakademie, IHLGB, Berlin (Germany))

1991-01-01

Actual parameters of the bearing capacity of traffic areas are in case of intensive use an indispensable necessity for the determination of the remaining use value with the aim to optimize reinforcing layers and reconstruction periods. Until now there is only one adequate measuring method for flexible layers. With the Rollig load test (RLT) initial data can be gained for the calculation of the load bearing capacity of rigid pavement structures. The method is described with the example of an airplane runway. (BWI).

Dynamic Modeling and Vibration Analysis for the Vehicles with Rigid Wheels Based on Wheel-Terrain Interaction Mechanics

Directory of Open Access Journals (Sweden)

Jianfeng Wang

2015-01-01

Full Text Available The contact mechanics for a rigid wheel and deformable terrain are complicated owing to the rigid flexible coupling characteristics. Bekker’s equations are used as the basis to establish the equations of the sinking rolling wheel, to vertical load pressure relationship. Since vehicle movement on the Moon is a complex and on-going problem, the researcher is poised to simplify this problem of vertical loading of the wheel. In this paper, the quarter kinetic models of a manned lunar rover, which are both based on the rigid road and deformable lunar terrain, are used as the simulation models. With these kinetic models, the vibration simulations were conducted. The simulation results indicate that the quarter kinetic model based on the deformable lunar terrain accurately reflects the deformable terrain’s influence on the vibration characteristics of a manned lunar rover. Additionally, with the quarter kinetic model of the deformable terrain, the vibration simulations of a manned lunar rover were conducted, which include a parametric analysis of the wheel parameters, vehicle speed, and suspension parameters. The results show that a manned lunar rover requires a lower damping value and stiffness to achieve better vibration performance.

Analysis of Switched-Rigid Floating Oscillator

Directory of Open Access Journals (Sweden)

Prabhakar R. Marur

2009-01-01

Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.

Sub-cellular damage by copper in the cnidarian Zoanthus robustus.

Science.gov (United States)

Grant, A; Trompf, K; Seung, D; Nivison-Smith, L; Bowcock, H; Kresse, H; Holmes, S; Radford, J; Morrow, P

2010-09-01

Sessile organisms may experience chronic exposure to copper that is released into the marine environment from antifoulants and stormwater runoff. We have identified the site of damage caused by copper to the symbiotic cnidarian, Zoanthus robustus (Anthozoa, Hexacorallia). External changes to the zoanthids were apparent when compared with controls. The normally flexible bodies contracted and became rigid. Histological examination of the zoanthid tissue revealed that copper had caused sub-cellular changes to proteins within the extracellular matrix (ECM) of the tubular body. Collagen in the ECM and the internal septa increased in thickness to five and seven times that of controls respectively. The epithelium, which stained for elastin, was also twice as thick and tough to cut, but exposure to copper did not change the total amount of desmosine which is found only in elastin. We conclude that copper stimulated collagen synthesis in the ECM and also caused cross-linking of existing proteins. However, there was no expulsion of the symbiotic algae (Symbiodinium sp.) and no effect on algal pigments or respiration (44, 66 and 110 microg Cu L(-1)). A decrease in net photosynthesis was observed only at the highest copper concentration (156 microg Cu L(-1)). These results show that cnidarians may be more susceptible to damage by copper than their symbiotic algae. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Torsional rigidity, isospectrality and quantum graphs

International Nuclear Information System (INIS)

Colladay, Don; McDonald, Patrick; Kaganovskiy, Leon

2017-01-01

We study torsional rigidity for graph and quantum graph analogs of well-known pairs of isospectral non-isometric planar domains. We prove that such isospectral pairs are distinguished by torsional rigidity. (paper)

Attitude dynamics and control of spacecraft with a partially filled liquid tank and flexible panels

Science.gov (United States)

Liu, Feng; Yue, Baozeng; Zhao, Liangyu

2018-02-01

A liquid-filled flexible spacecraft is essentially a time-variant fully-coupled system, whose dynamics characteristics are closely associated with its motion features. This paper focuses on the mathematical modelling and attitude control of the spacecraft coupled with fuel sloshing dynamics and flexible solar panels vibration. The slosh motion is represented by a spherical pendulum, whose motion description method is improved by using split variable operation. Benefiting from this improvement, the nonlinear lateral sloshing and the rotary sloshing as well as the rigid motion of a liquid respect to the spacecraft can be approximately described. The assumed modes discretization method has been adopted to approximate the elastic displacements of the attached panels, and the coupled dynamics is derived by using the Lagrangian formulation. A variable substitution method is proposed to obtain the apparently-uncoupled mathematical model of the rigid-flexible-liquid spacecraft. After linearization, this model can be directly used for designing Lyapunov output-feedback attitude controller (OFAC). With only torque actuators, and attitude and rate sensors installed, this kind of attitude controller, as simulation results show, is capable of not only bringing the spacecraft to the desired orientation, but also suppressing the effect of flex and slosh on the attitude motion of the spacecraft.

Numerical And Experimental Analysis Of The Process Of Aviation Drawpiece Forming Using Rigid And Rubber Punch With Various Properties

Directory of Open Access Journals (Sweden)

Kut S.

2015-09-01

Full Text Available This paper presents the results of the numerical analysis and experimental research of the forming process of aviation drawpiece made from 0.6 mm thick Inconel 625 sheet metal. First phase of testing was conducted using rigid steel tools for drawpiece forming. Results of conducted simulations show that during rigid tool forming, the middle of the drawpiece losses stability. In consequence, rigid tool forming leads to the formation of unacceptable wrinkles on the drawpiece. Subsequent experimental research confirmed wrinkles of the metal drawpiece in this area. It was assumed that in order to eliminate this negative phenomenon, minor changes in technology and tool construction would have to be made. The drawpiece will be shaped by means of a flexible tool, than re-shaped using rigid tools. In the second phase of the research, tooling design changes have been made. They consisted of replacing the steel punch with a specially designed stamp susceptible for deformation. FEM numerical simulations were performed for flexible punch forming made of polyurethane elastomer with different hardness (50, 70, 85 and 90 Sh A. On their basis, the effect on the mechanical characteristics of the elastomeric drawing process and the formation of wrinkles was shown. They can be effectively eliminated by the use of a punch with hardness of 90 Sh A, which has also been confirmed by experimental research. In addition, the paper presents a comparative analysis of the deformations in selected actual drawpiece areas and in the elastomeric punch with hardness 90 Sh A computer model. The actual drawpiece deformation schedule and the values were determined using photogrammetric system Argus v.6.3., while the computer modeled drawpiece was based on FEM calculations performed in the MARC / Mentat system. In conclusion the difficulties as well as the advantages and disadvantages in determining the deformation of sheet metal parts were indicated using photogrammetric system

Ultrastretchable and flexible copper interconnect-based smart patch for adaptive thermotherapy

KAUST Repository

Hussain, Aftab M.; Lizardo, Ernesto B.; Sevilla, Galo T.; Nassar, Joanna M.; Hussain, Muhammad Mustafa

2014-01-01

Unprecedented 800% stretchable, non-polymeric, widely used, low-cost, naturally rigid, metallic thin-film copper (Cu)-based flexible and non-invasive, spatially tunable, mobile thermal patch with wireless controllability, adaptability (tunes the amount of heat based on the temperature of the swollen portion), reusability, and affordability due to low-cost complementary metal oxide semiconductor (CMOS) compatible integration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrastretchable and flexible copper interconnect-based smart patch for adaptive thermotherapy

KAUST Repository

Hussain, Aftab M.

2014-12-03

Unprecedented 800% stretchable, non-polymeric, widely used, low-cost, naturally rigid, metallic thin-film copper (Cu)-based flexible and non-invasive, spatially tunable, mobile thermal patch with wireless controllability, adaptability (tunes the amount of heat based on the temperature of the swollen portion), reusability, and affordability due to low-cost complementary metal oxide semiconductor (CMOS) compatible integration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Should flexible ureteroscope be added to our armamentarium to treat stone disease?

Directory of Open Access Journals (Sweden)

Anand Dharaskar

2008-01-01

Full Text Available The field of Urology in Medicine has witnessed tremendous advancement in technology and in accordance with it. Endourology has taken a leap ahead in terms of stone management. Most of the stones could be treated with semi-rigid ureteroscopy, percutaneous nephrolithotomy (PNL and ESWL and some would need Flexible ureteroscopy. Flexible ureteroscopy has been primarily indicated to treat ESWL resistant renal stones but with changes in the technology of incorporating secondary active deflection and availability of laser fibres, its horizon for indications to treat stones is being widened. Though Flexible ureteroscopy is being used to treat stones of various sizes and locations, its cost effectiveness is debatable. Should it be used ubiquitously to treat stones amenable to PNL or ESWL is a big question we need to answer. As of now true indications of Flexible ureteroscopy are limited and there is an urgent need for a randomized trial to compare its efficacy with ESWL and PNL for renal and upper ureteric stones.

Exploring the magnetization dynamics of NiFe/Pt multilayers in flexible substrates

Energy Technology Data Exchange (ETDEWEB)

Corrêa, M.A., E-mail: marciocorrea@dfte.ufrn.br [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dutra, R.; Marcondes, T.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Mori, T.J.A. [Laboratório Nacional de Luz Síncrotron, Rua Giuseppe Máximo Scolfaro, 1000, Guará, 13083-100 Campinas, SP (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil)

2016-09-15

Highlights: • Magnetic properties of multilayers grown onto flexible substrates were investigated. • Experimental and theoretical magnetization dynamics results are presented. • The flexible substrates become promising candidate for rf-frequency devices. - Abstract: We investigate the structural and magnetic properties, and the magnetization dynamics in Ni{sub 81}Fe{sub 19}/Pt multilayer systems grown onto rigid and flexible substrates. The structural characterization shows evidence of a superlattice behavior, while the quasi-static magnetization characterization reveal a weak magnetic anisotropy induced in the multilayers. The magnetization dynamics is investigated through the magnetoimpedance effect. We employ a theoretical approach to describe the experimental magnetoimpedance effect and verify the influence of the effective damping parameter on the magnetization dynamics. Experimental data and theoretical results are in agreement and suggest that the multilayers present high effective damping parameter. Moreover, our experiments raise an interesting issue on the possibility of achieving considerable MI% values, even for systems with weak magnetic anisotropy and high damping parameter grown onto flexible substrates.

Vibration control of a flexible structure with electromagnetic actuators

DEFF Research Database (Denmark)

Gruzman, Maurício; Santos, Ilmar

2016-01-01

This work presents the model of a shear-frame-type structure composed of six flexible beams and three rigid masses. Fixed on the ground, outside the structure, two voltage-controlled electromagnetic actuators are used for vibration control. To model the flexible beams, unidimensional finite...... elements were used. Nonlinear equations for the actuator electromagnetic force, noise in the position sensor, time delays for the control signal update and voltage saturation were also considered in the model. For controlling purposes, a discrete linear quadratic regulator combined with a predictive full......-order discrete linear observer was employed. Results of numerical simulations, where the structure is submitted to an impulsive disturbance force and to a harmonic force, show that the oscillations can be significantly reduced with the use of the electromagnetic actuators....

Rigidity of monodromies for Appell's hypergeometric functions

Directory of Open Access Journals (Sweden)

Yoshishige Haraoka

2015-01-01

Full Text Available For monodromy representations of holonomic systems, the rigidity can be defined. We examine the rigidity of the monodromy representations for Appell's hypergeometric functions, and get the representations explicitly. The results show how the topology of the singular locus and the spectral types of the local monodromies work for the study of the rigidity.

Case report: Inhaled foreign body mismanaged as TB, finally removed using a rigid bronchoscopy after 6 years of impaction

Directory of Open Access Journals (Sweden)

Justin Rubena Lumaya

2016-02-01

Full Text Available Foreign body aspiration is an important cause of mortality in children aged less than three years. Foreign body (FB inhalation can pose diagnostic and therapeutic challenges, especially in longstanding cases and complications such as recurrent pneumonia, lung collapse and lung abscess may develop. We report a case of an 11-year old boy with foreign body impacted in his bronchus for six years, which was mistakenly managed as pulmonary tuberculosis. Radiological evidence confirmed the diagnosis and a rigid bronchoscopy was used to remove the metallic foreign body. The standard of care for the management of a FB in a bronchus is a rigid bronchoscopy; however flexible bronchoscopy can be used, especially in adults. A thorough history with radiological evidence are essential and sometimes, followed by a diagnostic bronchoscopy.

Technical considerations for flexible piping design in nuclear power plants

International Nuclear Information System (INIS)

Lu, S.C.; Chou, C.K.

1985-01-01

The overall objective of this research project is to develop a technical basis for flexible piping designs which will improve piping reliability and minimize the use of pipe supports, snubbers, and pipe whip restraints. The current study was conducted to establish the necessary groundwork based on the piping reliability analysis. A confirmatory piping reliability assessment indicated that removing rigid supports and snubbers tends to either improve or affect very little the piping reliability. A couple of changes to be implemented in Regulatory Guide (RG) 1.61 and RG 1.122 aimed at more flexible piping design were investigated. It was concluded that these changes substantially reduce calculated piping responses and allows piping redesigns with significant reduction in number of supports and snubbers without violating ASME code requirements

Flexible electret energy harvesters with parylene electret on PDMS substrates

International Nuclear Information System (INIS)

Chiu, Yi; Wu, Shih-Hsien

2013-01-01

Currently, most vibrational energy harvesters have rigid and resonant structures to harvest energy from periodic motions in specific directions. However, in some situations the motion is random and aperiodic; or the targeted energy source is the strain energy in deformation, rather than the kinetic energy in vibration. Therefore we propose and demonstrate a PDMS-based flexible energy harvester with parylene-C electret that can be attached to any deformable surfaces to harvest the stain energy caused by external deformation. The proposed flexible harvester was fabricated and characterized. The measured power at 20 Hz is 0.18 μW and 82 nW in the compression and bending modes, respectively. Such a harvester has the potential for wearable and implantable electronics applications

Aggregation of flexible polyelectrolytes: Phase diagram and dynamics.

Science.gov (United States)

Tom, Anvy Moly; Rajesh, R; Vemparala, Satyavani

2017-10-14

Similarly charged polymers in solution, known as polyelectrolytes, are known to form aggregated structures in the presence of oppositely charged counterions. Understanding the dependence of the equilibrium phases and the dynamics of the process of aggregation on parameters such as backbone flexibility and charge density of such polymers is crucial for insights into various biological processes which involve biological polyelectrolytes such as protein, DNA, etc. Here, we use large-scale coarse-grained molecular dynamics simulations to obtain the phase diagram of the aggregated structures of flexible charged polymers and characterize the morphology of the aggregates as well as the aggregation dynamics, in the presence of trivalent counterions. Three different phases are observed depending on the charge density: no aggregation, a finite bundle phase where multiple small aggregates coexist with a large aggregate and a fully phase separated phase. We show that the flexibility of the polymer backbone causes strong entanglement between charged polymers leading to additional time scales in the aggregation process. Such slowing down of the aggregation dynamics results in the exponent, characterizing the power law decay of the number of aggregates with time, to be dependent on the charge density of the polymers. These results are contrary to those obtained for rigid polyelectrolytes, emphasizing the role of backbone flexibility.

Productivity and employee satisfaction in flexible workplaces

NARCIS (Netherlands)

van der Voordt, Theo

2004-01-01

In the early 1990s, a few organisations in the Netherlands began to experiment with flexible workplaces. Traditional cellular offices and the open‐plan offices or team‐oriented bullpen spaces in which everyone had their own fixed workplace were no longer a matter of course. Making use of modern

The discrete null space method for the energy-consistent integration of constrained mechanical systems. Part III: Flexible multibody dynamics

International Nuclear Information System (INIS)

Leyendecker, Sigrid; Betsch, Peter; Steinmann, Paul

2008-01-01

In the present work, the unified framework for the computational treatment of rigid bodies and nonlinear beams developed by Betsch and Steinmann (Multibody Syst. Dyn. 8, 367-391, 2002) is extended to the realm of nonlinear shells. In particular, a specific constrained formulation of shells is proposed which leads to the semi-discrete equations of motion characterized by a set of differential-algebraic equations (DAEs). The DAEs provide a uniform description for rigid bodies, semi-discrete beams and shells and, consequently, flexible multibody systems. The constraints may be divided into two classes: (i) internal constraints which are intimately connected with the assumption of rigidity of the bodies, and (ii) external constraints related to the presence of joints in a multibody framework. The present approach thus circumvents the use of rotational variables throughout the whole time discretization, facilitating the design of energy-momentum methods for flexible multibody dynamics. After the discretization has been completed a size-reduction of the discrete system is performed by eliminating the constraint forces. Numerical examples dealing with a spatial slider-crank mechanism and with intersecting shells illustrate the performance of the proposed method

Liquid-phase tuning of porous PVDF-TrFE film on flexible substrate for energy harvesting

Science.gov (United States)

Chen, Dajing; Chen, Kaina; Brown, Kristopher; Hang, Annie; Zhang, John X. J.

2017-04-01

Emerging wearable and implantable biomedical energy harvesting devices demand efficient power conversion, flexible structures, and lightweight construction. This paper presents Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) micro-porous structures, which can be tuned to specific mechanical flexibilities and optimized for piezoelectric power conversion. Specifically, the water vapor phase separation method was developed to control microstructure formation, pore diameter, porosity, and mechanical flexibility. Furthermore, we investigated the effects of the piezoelectric layer to supporting layer Young's modulus ratio, through using both analytical calculation and experimentation. Both structure flexibility and stress-induced voltage were considered in the analyses. Specification of electromechanical coupling efficiency, made possible by carefully designed three-dimensional porous structures, was shown to increase the power output by five-fold relative to uncoupled structures. Therefore, flexible PVDF-TrFE films with tunable microstructures, paired with substrates of different rigidities, provide highly efficient designs of compact piezoelectric energy generating devices.

Research on The Construction of Flexible Multi-body Dynamics Model based on Virtual Components

Science.gov (United States)

Dong, Z. H.; Ye, X.; Yang, F.

2018-05-01

Focus on the harsh operation condition of space manipulator, which cannot afford relative large collision momentum, this paper proposes a new concept and technology, called soft-contact technology. In order to solve the problem of collision dynamics of flexible multi-body system caused by this technology, this paper also proposes the concepts of virtual components and virtual hinges, and constructs flexible dynamic model based on virtual components, and also studies on its solutions. On this basis, this paper uses NX to carry out model and comparison simulation for space manipulator in 3 different modes. The results show that using the model of multi-rigid body + flexible body hinge + controllable damping can make effective control on amplitude for the force and torque caused by target satellite collision.

Effects of structural flexibility of wings in flapping flight of butterfly.

Science.gov (United States)

Senda, Kei; Obara, Takuya; Kitamura, Masahiko; Yokoyama, Naoto; Hirai, Norio; Iima, Makoto

2012-06-01

The objective of this paper is to clarify the effects of structural flexibility of wings of a butterfly in flapping flight. For this purpose, a dynamics model of a butterfly is derived by Lagrange's method, where the butterfly is considered as a rigid multi-body system. The panel method is employed to simulate the flow field and the aerodynamic forces acting on the wings. The mathematical model is validated by the agreement of the numerical result with the experimentally measured data. Then, periodic orbits of flapping-of-wings flights are parametrically searched in order to fly the butterfly models. Almost periodic orbits are found, but they are unstable. Deformation of the wings is modeled in two ways. One is bending and its effect on the aerodynamic forces is discussed. The other is passive wing torsion caused by structural flexibility. Numerical simulations demonstrate that flexible torsion reduces the flight instability.

Effects of structural flexibility of wings in flapping flight of butterfly

International Nuclear Information System (INIS)

Senda, Kei; Yokoyama, Naoto; Obara, Takuya; Kitamura, Masahiko; Hirai, Norio; Iima, Makoto

2012-01-01

The objective of this paper is to clarify the effects of structural flexibility of wings of a butterfly in flapping flight. For this purpose, a dynamics model of a butterfly is derived by Lagrange’s method, where the butterfly is considered as a rigid multi-body system. The panel method is employed to simulate the flow field and the aerodynamic forces acting on the wings. The mathematical model is validated by the agreement of the numerical result with the experimentally measured data. Then, periodic orbits of flapping-of-wings flights are parametrically searched in order to fly the butterfly models. Almost periodic orbits are found, but they are unstable. Deformation of the wings is modeled in two ways. One is bending and its effect on the aerodynamic forces is discussed. The other is passive wing torsion caused by structural flexibility. Numerical simulations demonstrate that flexible torsion reduces the flight instability. (paper)

Pressure-actuated cellular structures

International Nuclear Information System (INIS)

Pagitz, M; Hol, J M A M; Lamacchia, E

2012-01-01

Shape changing structures will play an important role in future engineering designs since rigid structures are usually only optimal for a small range of service conditions. Hence, a concept for reliable and energy-efficient morphing structures that possess a large strength to self-weight ratio would be widely applicable. We propose a novel concept for morphing structures that is inspired by the nastic movement of plants. The idea is to connect prismatic cells with tailored pentagonal and/or hexagonal cross sections such that the resulting cellular structure morphs into given target shapes for certain cell pressures. An efficient algorithm for computing equilibrium shapes as well as cross-sectional geometries is presented. The potential of this novel concept is demonstrated by several examples that range from a flagellum like propulsion device to a morphing aircraft wing.

Enhancing wind turbines efficiency with passive reconfiguration of flexible blades

Science.gov (United States)

Cognet, Vincent P. A.; Thiria, Benjamin; Courrech Du Pont, Sylvain; MSC Team; PMMH Team

2015-11-01

Nature provides excellent examples where flexible materials are advantageous in a fluid stream. By folding, leaves decrease the drag caused by air stream; and birds' flapping is much more efficient with flexible wings. Motivated by this, we investigate the effect of flexible blades on the performance of a wind turbine. The effect of chordwise flexible blades is studied both experimentally and theoretically on a small wind turbine in steady state. Four parameters are varied: the wind velocity, the resisting torque, the pitch angle, and the blade's bending modulus. We find an optimum efficiency with respect to the bending modulus. By tuning our four parameters, the wind turbine with flexible blades has a high-efficiency range significantly larger than rigid blades', and, furthermore enhances the operating range. These results are all the more important as one of the current issues concerning wind turbines is the enlargement of their operating range. To explain these results, we propose a simple two-dimensional model by discretising the blade along the radius. We take into account the variation of drag and lift coefficients with the bending ability. This model matches experimental observations and demonstrates the contribution of the reconfiguration of the blade. Matiere et Systemes Complexes.

Cellular potts models multiscale extensions and biological applications

CERN Document Server

Scianna, Marco

2013-01-01

A flexible, cell-level, and lattice-based technique, the cellular Potts model accurately describes the phenomenological mechanisms involved in many biological processes. Cellular Potts Models: Multiscale Extensions and Biological Applications gives an interdisciplinary, accessible treatment of these models, from the original methodologies to the latest developments. The book first explains the biophysical bases, main merits, and limitations of the cellular Potts model. It then proposes several innovative extensions, focusing on ways to integrate and interface the basic cellular Potts model at the mesoscopic scale with approaches that accurately model microscopic dynamics. These extensions are designed to create a nested and hybrid environment, where the evolution of a biological system is realistically driven by the constant interplay and flux of information between the different levels of description. Through several biological examples, the authors demonstrate a qualitative and quantitative agreement with t...

Hydrodynamics of a three-dimensional self-propelled flexible plate

Science.gov (United States)

Ryu, Jaeha; Sung, Hyung Jin

2017-11-01

A three-dimensional self-propelled flexible plate in a quiescent flow was simulated using the immersed boundary method. The clamped leading edge of the flexible plate was forced into a vertical oscillation, while free to move horizontally. To reveal the hydrodynamics of the plate, the averaged cruising speed (UC) , the input power (P) , and the swimming efficiency (η) were analyzed as a function of the bending rigidity (γ) and the flapping frequency (f) . The velocity field around the plate and the exerted force on the plate were demonstrated to find out the dynamic interaction between the plate and the surrounding fluid. The kinematics of the plate, the maximum angle of attack (ϕmax) , and the mean effective length (Leff) were examined accounting for the hydrodynamics of the self-propelled flexible plate. The vortical structures around the plate were visualized, and the influence of the tip vortex on the swimming efficiency was explored qualitatively and quantitatively. This work was supported by the Creative Research Initiatives (No. 2017-013369) program of the National Research Foundation of Korea (MSIP).

Surgical treatment of double thoracic adolescent idiopathic scoliosis with a rigid proximal thoracic curve.

Science.gov (United States)

Sudo, Hideki; Abe, Yuichiro; Abumi, Kuniyoshi; Iwasaki, Norimasa; Ito, Manabu

2016-02-01

There is limited consensus on the optimal surgical strategy for double thoracic adolescent idiopathic scoliosis (AIS). Recent studies have reported that pedicle screw constructs to maximize scoliosis correction cause further thoracic spine lordosis. The objective of this study was to apply a new surgical technique for double thoracic AIS with rigid proximal thoracic (PT) curves and assess its clinical outcomes. Twenty one consecutive patients with Lenke 2 AIS and a rigid PT curve (Cobb angle ≥30º on side-bending radiographs, flexibility ≤30 %) treated with the simultaneous double-rod rotation technique (SDRRT) were included. In this technique, a temporary rod is placed at the concave side of the PT curve. Then, distraction force is applied to correct the PT curve, which reforms a sigmoid double thoracic curve into an approximate single thoracic curve. As a result, the PT curve is typically converted from an apex left to an apex right curve before applying the correction rod for PT and main thoracic curve. All patients were followed for at least 2 years (average 2.7 years). The average main thoracic and PT Cobb angle correction rate at the final follow-up was 74.7 and 58.0 %, respectively. The average preoperative T5-T12 thoracic kyphosis was 9.3°, which improved significantly to 19.0° (p corrected using SDRRT for Lenke 2 AIS with a rigid PT curve.

A new technique of deploying dynamic y stent using flexible bronchoscope, video laryngoscope, and laryngeal mask airway.

Science.gov (United States)

Obeidat, Shadi; Badin, Shadi; Khawaja, Imran

2010-04-01

Dynamic Y stents are used in tracheobronchial obstruction, tracheal stenosis, and tracheomalacia. Placement may be difficult and is usually accomplished using a rigid grasping forceps (under fluoroscopic guidance) or a rigid bronchoscope. We report using a new stent placement technique on an elderly patient with a central tracheobronchial tumor. It included using a flexible bronchoscope, video laryngoscope, and laryngeal mask airway. The new technique we used has the advantages of continuous direct endoscopic visualization during stent advancement and manipulation, and securing the airways with a laryngeal mask airway at the same time. This technique eliminates the need for intraoperative fluoroscopy.

CNA web server: rigidity theory-based thermal unfolding simulations of proteins for linking structure, (thermo-)stability, and function.

Science.gov (United States)

Krüger, Dennis M; Rathi, Prakash Chandra; Pfleger, Christopher; Gohlke, Holger

2013-07-01

The Constraint Network Analysis (CNA) web server provides a user-friendly interface to the CNA approach developed in our laboratory for linking results from rigidity analyses to biologically relevant characteristics of a biomolecular structure. The CNA web server provides a refined modeling of thermal unfolding simulations that considers the temperature dependence of hydrophobic tethers and computes a set of global and local indices for quantifying biomacromolecular stability. From the global indices, phase transition points are identified where the structure switches from a rigid to a floppy state; these phase transition points can be related to a protein's (thermo-)stability. Structural weak spots (unfolding nuclei) are automatically identified, too; this knowledge can be exploited in data-driven protein engineering. The local indices are useful in linking flexibility and function and to understand the impact of ligand binding on protein flexibility. The CNA web server robustly handles small-molecule ligands in general. To overcome issues of sensitivity with respect to the input structure, the CNA web server allows performing two ensemble-based variants of thermal unfolding simulations. The web server output is provided as raw data, plots and/or Jmol representations. The CNA web server, accessible at http://cpclab.uni-duesseldorf.de/cna or http://www.cnanalysis.de, is free and open to all users with no login requirement.

320-nm Flexible Solution-Processed 2,7-dioctyl[1] benzothieno[3,2-b]benzothiophene Transistors.

Science.gov (United States)

Ren, Hang; Tang, Qingxin; Tong, Yanhong; Liu, Yichun

2017-08-09

Flexible organic thin-film transistors (OTFTs) have received extensive attention due to their outstanding advantages such as light weight, low cost, flexibility, large-area fabrication, and compatibility with solution-processed techniques. However, compared with a rigid substrate, it still remains a challenge to obtain good device performance by directly depositing solution-processed organic semiconductors onto an ultrathin plastic substrate. In this work, ultrathin flexible OTFTs are successfully fabricated based on spin-coated 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) films. The resulting device thickness is only ~320 nm, so the device has the ability to adhere well to a three-dimension curved surface. The ultrathin C8-BTBT OTFTs exhibit a mobility as high as 4.36 cm² V -1 s -1 and an on/off current ratio of over 10⁶. These results indicate the substantial promise of our ultrathin flexible C8-BTBT OTFTs for next-generation flexible and conformal electronic devices.

Development of a cryogenic flexible pipe for the transfer of liquefied natural gas; Mise au point d'un flexible cryogenique pour le transfert du gaz naturel liquefie

Energy Technology Data Exchange (ETDEWEB)

Rigaud, J.; Gerez, J.M.; Dieumegard, C. [Coflexip Stena Offshore, 75 - Paris (France)

2000-07-01

For historical reasons, the liquefaction of natural gas is performed with onshore equipments and LNG tanker-ships are loaded and unloaded using rigid articulated arms. When these operations are performed in harbors, the movement of the ship with respect to the pier are relatively limited. Today, several companies aim at liquefying natural gas using floating facilities. The loading of tanker-ships is performed offshore, and thus movements between the ship and the floating facility are enhanced. The use of a flexible pipe can be an interesting alternative solution to the articulated arm. This article describes the state-of-the-art of the LNG flexible technology developed by Coflexip Stena Offshore and the progress of the program of development of a cryogenic flexible: structure, fittings, safety (leaks detection), thermal calculations, optimization of the corrugated hose profile, pressure drops, fatigue tests and service life, materials development, prototype and real tests. (J.S.)

Numerical Analysis of Small Deformation of Flexible Helical Flagellum of Swimming Bacteria

Science.gov (United States)

Takano, Yasunari; Goto, Tomonobu

Formulations are conducted to numerically analyze the effect of flexible flagellum of swimming bacteria. In the present model, a single-flagellate bacterium is assumed to consist of a rigid cell body of the prolate spheroidal shape and a flexible flagellum of the helical form. The resistive force theory is applied to estimate the force exerted on the flagellum. The torsional as well as the bending moments determine the curvature and the torsion of the deformed flagellum according to the Kirchhoff model for an elastic rod. The unit tangential vector along the deformed flagellum is calculated by applying evolution equations for space curves, and also a deformed shape of the flagellum is obtained.

Analysis and Optimisation of Carcass Production for Flexible Pipes

DEFF Research Database (Denmark)

Nielsen, Peter Søe

Un-bonded flexible pipes are used in the offshore oil and gas industry worldwide transporting hydrocarbons from seafloor to floating production vessels topside. Flexible pipes are advantageous over rigid pipelines in dynamic applications and during installation as they are delivered in full length......-axial tension FLC points were attained. Analysis of weld fracture of duplex stainless steel EN 1.4162 is carried out determining strains with GOM ARAMIS automated strain measurement system, which shows that strain increases faster in the weld zone than the global strain of the parent material. Fracture...... is the analysis and optimisation of the carcass manufacturing process by means of a fundamental investigation in the fields of formability, failure modes / mechanisms, Finite Element Analysis (FEA), simulative testing and tribology. A study of failure mechanisms in carcass production is performed by being present...

Flexible Composite-Material Pressure Vessel

Science.gov (United States)

Brown, Glen; Haggard, Roy; Harris, Paul A.

2003-01-01

A proposed lightweight pressure vessel would be made of a composite of high-tenacity continuous fibers and a flexible matrix material. The flexibility of this pressure vessel would render it (1) compactly stowable for transport and (2) more able to withstand impacts, relative to lightweight pressure vessels made of rigid composite materials. The vessel would be designed as a structural shell wherein the fibers would be predominantly bias-oriented, the orientations being optimized to make the fibers bear the tensile loads in the structure. Such efficient use of tension-bearing fibers would minimize or eliminate the need for stitching and fill (weft) fibers for strength. The vessel could be fabricated by techniques adapted from filament winding of prior composite-material vessels, perhaps in conjunction with the use of dry film adhesives. In addition to the high-bias main-body substructure described above, the vessel would include a low-bias end substructure to complete coverage and react peak loads. Axial elements would be overlaid to contain damage and to control fiber orientation around side openings. Fiber ring structures would be used as interfaces for connection to ancillary hardware.

Too close and too rigid: applying the Circumplex Model of Family Systems to first-generation family firms.

Science.gov (United States)

Michael-Tsabari, Nava; Lavee, Yoav

2012-06-01

Despite growing research interest in family businesses, little is known about the characteristics of the families engaging in them. The present paper uses Olson's (Journal of Psychotherapy & the Family, 1988, 4(12), 7-49; Journal of Family Therapy, 2000, 22, 144-167) Circumplex Model of Marital and Family Systems to look at first-generation family firms. We describe existing typologies of family businesses and discuss similarities between the characteristics of first-generation family firms and the rigidly enmeshed family type described in the Circumplex Model. The Steinberg family business (Gibbon & Hadekel (1990) Steinberg: The breakup of a family empire. ON, Canada: MacMillan) serves to illustrate the difficulties of rigidly enmeshed first-generation family firms. Implications for understanding troubled family businesses are discussed together with guidelines for the assessment of a family business in crisis and for intervention: enhancing open communication; allowing for more flexible leadership style, roles, and rules; and maintaining a balance between togetherness and separateness. © 2012 American Association for Marriage and Family Therapy.

Hyperspectral Imaging Using Flexible Endoscopy for Laryngeal Cancer Detection

Directory of Open Access Journals (Sweden)

Bianca Regeling

2016-08-01

Full Text Available Hyperspectral imaging (HSI is increasingly gaining acceptance in the medical field. Up until now, HSI has been used in conjunction with rigid endoscopy to detect cancer in vivo. The logical next step is to pair HSI with flexible endoscopy, since it improves access to hard-to-reach areas. While the flexible endoscope’s fiber optic cables provide the advantage of flexibility, they also introduce an interfering honeycomb-like pattern onto images. Due to the substantial impact this pattern has on locating cancerous tissue, it must be removed before the HS data can be further processed. Thereby, the loss of information is to minimize avoiding the suppression of small-area variations of pixel values. We have developed a system that uses flexible endoscopy to record HS cubes of the larynx and designed a special filtering technique to remove the honeycomb-like pattern with minimal loss of information. We have confirmed its feasibility by comparing it to conventional filtering techniques using an objective metric and by applying unsupervised and supervised classifications to raw and pre-processed HS cubes. Compared to conventional techniques, our method successfully removes the honeycomb-like pattern and considerably improves classification performance, while preserving image details.

Soft soils reinforced by rigid vertical inclusions

Directory of Open Access Journals (Sweden)

Iulia-Victoria NEAGOE

2013-12-01

Full Text Available Reinforcement of soft soils by rigid vertical inclusions is an increasingly used technique over the last few years. The system consists of rigid or semi-rigid vertical inclusions and a granular platform for the loads transfer from the structure to the inclusions. This technique aims to reduce the differential settlements both at ground level as below the structure. Reinforcement by rigid inclusions is mainly used for foundation works for large commercial and industrial platforms, storage tanks, wastewater treatment plants, wind farms, bridges, roads, railway embankments. The subject is one of interest as it proves the recently concerns at international level in research and design; however, most studies deal more with the static behavior and less with the dynamic one.

A study on self-excited sloshing due to the fluid discharge over a flexible weir

International Nuclear Information System (INIS)

Nagakura, Hiroshi; Kaneko, Shigehiko.

1995-01-01

An analytical model for the fluid-elastic instability as observed in Super-Phenix-1 LMFBR is proposed. This fluid-structure system is constituted by the flexible weir and adjoining fluid plenums, and the fluid is discharged from the upstream plenum to the downstream plenum over a flexible weir. The characteristic equation of the system is derived for the case in which the weir vibrates at the frequency of the downstream plenum sloshing. The effects of the fluid level difference between the upstream and the downstream plenum and weir rigidity are examined, and the mechanism for instability is discussed. (author)

Laterally excited flexible tanks with nonuniform density liquid

International Nuclear Information System (INIS)

Tang, Yu

1996-01-01

A study of the dynamic responses of flexible tanks containing nonuniform liquid under horizontal base excitations is presented. The system considered is an upright, circular cylindrical tank filled with an incompressible and inviscid liquid in which the density increases with the liquid depth. Only the impulsive components of response are considered in this study since the convective components can be computed by considering the tank to be rigid. It is shown in this study that for tanks with height-to-radius ratios between 0.3 and 1.2, the response quantities may be estimated utilizing the rigid tank solutions. Also, it is found that the pressure distribution along the tank wall is not sensitive to the detailed distribution function of the liquid density, and that the base shear and moments for the tank with nonuniform liquid can be estimated conservatively by assuming that the tank is filled with an equivalent uniform liquid density that preserves the total liquid weight. Finally, a simple equation for evaluating the fundamental natural frequency of the system is proposed

Flight Dynamics of Flexible Aircraft with Aeroelastic and Inertial Force Interactions

Science.gov (United States)

Nguyen, Nhan T.; Tuzcu, Ilhan

2009-01-01

This paper presents an integrated flight dynamic modeling method for flexible aircraft that captures coupled physics effects due to inertial forces, aeroelasticity, and propulsive forces that are normally present in flight. The present approach formulates the coupled flight dynamics using a structural dynamic modeling method that describes the elasticity of a flexible, twisted, swept wing using an equivalent beam-rod model. The structural dynamic model allows for three types of wing elastic motion: flapwise bending, chordwise bending, and torsion. Inertial force coupling with the wing elasticity is formulated to account for aircraft acceleration. The structural deflections create an effective aeroelastic angle of attack that affects the rigid-body motion of flexible aircraft. The aeroelastic effect contributes to aerodynamic damping forces that can influence aerodynamic stability. For wing-mounted engines, wing flexibility can cause the propulsive forces and moments to couple with the wing elastic motion. The integrated flight dynamics for a flexible aircraft are formulated by including generalized coordinate variables associated with the aeroelastic-propulsive forces and moments in the standard state-space form for six degree-of-freedom flight dynamics. A computational structural model for a generic transport aircraft has been created. The eigenvalue analysis is performed to compute aeroelastic frequencies and aerodynamic damping. The results will be used to construct an integrated flight dynamic model of a flexible generic transport aircraft.

Electrochemical synthesis of polyaniline in the presence of poly(amidosulfonic acid)s with different rigidity of polymer backbone and characterization of the films obtained

International Nuclear Information System (INIS)

Nekrasov, A.A.; Gribkova, O.L.; Eremina, T.V.; Isakova, A.A.; Ivanov, V.F.; Tverskoj, V.A.; Vannikov, A.V.

2008-01-01

We have studied electrochemical matrix polymerization of aniline in the presence of poly(amidosulfonic acid)s of different nature: poly(2-acrylamido-2-methyl-1-propanosulfonic acid) (PAMPSA, flexible backbone); poly(p,p'-(2,2'-disulfoacid)-diphenylene-iso-phthalamid) (i-PASA, semi-rigid backbone); poly(p,p'-(2,2'-disulfoacid)-diphelylene-tere-phthalamid) (t-PASA, rigid backbone). Also, we have investigated spectral and electrochemical properties of the films obtained, as well as their surface morphology. The matrix polymerization results in the formation of interpolymer complexes of polyaniline (PANI) and the above-cited polyacids. The acceleration of aniline electropolymerization in the presence of poly(amidosulfonic acid)s was observed due to association of aniline molecules to sulfonic groups of the polyacid and higher local concentration of protons near the polyacid backbone. The rigid-chain polyacids interfere with the normal course of the electropolymerization, which manifests itself in the changes of the shape of time dependences of absorbance and charge. Cyclic voltammetry and spectroelectrochemical experiments showed that the formation of interpolymer complex with rigid-chain polyacids distorts spectroelectrochemical characteristics of PANI. This evidently results from steric hindrances in the formation of quinoid units

Impact Vibration Attenuation for a Flexible Robotic Manipulator through Transfer and Dissipation of Energy

Directory of Open Access Journals (Sweden)

Yushu Bian

2013-01-01

Full Text Available Due to the presence of system flexibility, impact can excite severe large amplitude vibration responses of the flexible robotic manipulator. This impact vibration exhibits characteristics of remarkable nonlinearity and strong energy. The main goal of this study is to put forward an energy-based control method to absorb and attenuate large amplitude impact vibration of the flexible robotic manipulator. The method takes advantage of internal resonance and is implemented through a vibration absorber based on the transfer and dissipation of energy. The addition of the vibration absorber to the flexible arm generates a coupling effect between vibration modes of the system. By means of analysis on 2:1 internal resonance, the exchange of energy is proven to be existent. The impact vibrational energy can be transferred from the arm to the absorber and dissipated through the damping of the absorber. The results of numerical simulations are promising and preliminarily verify that the method is feasible and can be used to combat large amplitude impact vibration of the flexible manipulator undergoing rigid motion.

Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

KAUST Repository

Nassar, Joanna M.; Hussain, Aftab M.; Rojas, Jhonathan Prieto; Hussain, Muhammad Mustafa

2014-01-01

Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

Transfer-less flexible and transparent high-κ/metal gate germanium devices on bulk silicon (100)

KAUST Repository

Nassar, Joanna M.

2014-08-01

Flexible wearable electronics have been of great interest lately for the development of innovative future technology for various interactive applications in the field of consumer electronics and advanced healthcare, offering the promise of low-cost, lightweight, and multifunctionality. In the pursuit of this trend, high mobility channel materials need to be investigated on a flexible platform, for the development of flexible high performance devices. Germanium (Ge) is one of the most attractive alternatives for silicon (Si) for high-speed computational applications, due its higher hole and electron mobility. Thus, in this work we show a cost effective CMOS compatible process for transforming conventional rigid Ge metal oxide semiconductor capacitors (MOSCAPS) into a mechanically flexible and semi-transparent platform. Devices exhibit outstanding bendability with a bending radius of 0.24 cm, and semi-transparency up to 30 %, varying with respect to the diameter size of the release holes array.

Slip Morphology of Elastic Strips on Frictional Rigid Substrates.

Science.gov (United States)

Sano, Tomohiko G; Yamaguchi, Tetsuo; Wada, Hirofumi

2017-04-28

The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which-when the bending elasticity dominates over the effect of gravity-are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and the coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law and find excellent quantitative agreement with simulations and controlled physical experiments. We also discuss the effect of gravity in order to bridge the difference in the qualitative behaviors of stiff strips and flexible strings or ropes. Our study thus complements recent work on elastic rope coiling and takes a significant step towards establishing a unified understanding of how a thin elastic object interacts vertically with a solid surface.

Literature Review on Dynamic Cellular Manufacturing System

Science.gov (United States)

Nouri Houshyar, A.; Leman, Z.; Pakzad Moghadam, H.; Ariffin, M. K. A. M.; Ismail, N.; Iranmanesh, H.

2014-06-01

In previous decades, manufacturers faced a lot of challenges because of globalization and high competition in markets. These problems arise from shortening product life cycle, rapid variation in demand of products, and also rapid changes in manufcaturing technologies. Nowadays most manufacturing companies expend considerable attention for improving flexibility and responsiveness in order to overcome these kinds of problems and also meet customer's needs. By considering the trend toward the shorter product life cycle, the manufacturing environment is towards manufacturing a wide variety of parts in small batches [1]. One of the major techniques which are applied for improving manufacturing competitiveness is Cellular Manufacturing System (CMS). CMS is type of manufacturing system which tries to combine flexibility of job shop and also productivity of flow shop. In addition, Dynamic cellular manufacturing system which considers different time periods for the manufacturing system becomes an important topic and attracts a lot of attention to itself. Therefore, this paper made attempt to have a brief review on this issue and focused on all published paper on this subject. Although, this topic gains a lot of attention to itself during these years, none of previous researchers focused on reviewing the literature of that which can be helpful and useful for other researchers who intend to do the research on this topic. Therefore, this paper is the first study which has focused and reviewed the literature of dynamic cellular manufacturing system.

Treatment of Zenker's diverticulum through a flexible endoscope with a transparent oblique-end hood attached to the tip and a monopolar forceps

NARCIS (Netherlands)

Christiaens, P.; de Roock, W.; van Olmen, A.; Moons, V.; D'Haens, G.

2007-01-01

Zenker's diverticulum was commonly treated by means of external transcervical diverticulectomy, myotomy or diverticulopexy, or by means of an endoscopic myotomy through a rigid endoscope. Gastroenterologists first described flexible endoscopic therapy for Zenker's diverticulum in 1995. In our

Free Vibration Analysis of a Spinning Flexible DISK-SPINDLE System Supported by Ball Bearing and Flexible Shaft Using the Finite Element Method and Substructure Synthesis

Science.gov (United States)

JANG, G. H.; LEE, S. H.; JUNG, M. S.

2002-03-01

Free vibration of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft is analyzed by using Hamilton's principle, FEM and substructure synthesis. The spinning disk is described by using the Kirchhoff plate theory and von Karman non-linear strain. The rotating spindle and stationary shaft are modelled by Rayleigh beam and Euler beam respectively. Using Hamilton's principle and including the rigid body translation and tilting motion, partial differential equations of motion of the spinning flexible disk and spindle are derived consistently to satisfy the geometric compatibility in the internal boundary between substructures. FEM is used to discretize the derived governing equations, and substructure synthesis is introduced to assemble each component of the disk-spindle-bearing-shaft system. The developed method is applied to the spindle system of a computer hard disk drive with three disks, and modal testing is performed to verify the simulation results. The simulation result agrees very well with the experimental one. This research investigates critical design parameters in an HDD spindle system, i.e., the non-linearity of a spinning disk and the flexibility and boundary condition of a stationary shaft, to predict the free vibration characteristics accurately. The proposed method may be effectively applied to predict the vibration characteristics of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft in the various forms of computer storage device, i.e., FDD, CD, HDD and DVD.

A numerical simulation of VIV on a flexible circular cylinder

International Nuclear Information System (INIS)

Xie Fangfang; Deng Jian; Zheng Yao; Xiao Qing

2012-01-01

In this paper, numerical simulations of a flexible circular cylinder subjected to a vortex-induced vibration (VIV) are conducted. The Reynolds number for simulations is fixed at 1000. The finite volume method is applied for modeling fluid flow with the moving meshes feature. The dynamic response of a flexible cylinder fixed at both ends is modeled by the Euler–Bernoulli beam theory. The comparison between two-dimensional (2D) simulations and 3D simulations for the flexible cylinder shows that the maximum response amplitude of the cross-flow oscillation is about 0.57D for 2D rigid cylinders (modeled by a spring–damper–mass model) and 1.03D for flexible cylinders, respectively. The results from 3D simulations are closer to previous experimental results. Furthermore, the results obtained with various frequency ratios show that different wake patterns exist according to the frequency ratio, such as 2S mode, 2P mode and some more complicated modes. The wake pattern is different at various sections along the cylinder length, due to the fact that the two ends of the beam are fixed. The vibration of the flexible cylinder can also greatly alter the three dimensionality in the wake, which is our research in future work, especially in the transition region for Reynolds number ranging from 170 to 300. (paper)

Polyimide-Epoxy Composites with Superior Bendable Properties for Application in Flexible Electronics

Science.gov (United States)

Lee, Sangyoup; Yoo, Taewon; Han, Youngyu; Kim, Hanglim; Han, Haksoo

2017-08-01

The need for flexible electronics with outstanding bending properties is increasing due to the demand for wearable devices and next-generation flexible or rollable smartphones. In addition, the requirements for flexible or rigid-flexible electronics are sharply increasing to achieve the design of space-saving electronic devices. In this regard, coverlay (CL) film is a key material used in the bending area of flexible electronics, albeit infrequently. Because flexible electronics undergo folding and unfolding numerous times, CL films with superior mechanical and bending properties are required so that the bending area can endure such severe stress. However, because current CL films are only used for a designated bending area in the flexible electronics panel, their highly complicated and expensive manufacturing procedure is a disadvantage. In addition, the thickness of CL films must be decreased to satisfy the ongoing requirement for increasingly thin products. However, due to the limitations of the two-layer structure of existing CL films, the manufacturing process cannot be made more cost effective by simply applying more thin film onto the board. To address this problem, we have developed liquid coverlay inks (LCIs) with superior bendable properties, in comparison with CL films, when applied onto flexible electronics using a screen-printing method. The results show that LCIs have the potential to become one of the leading candidates to replace existing CL films because of their lower cost and faster manufacturing process.

Participatory sensing as an enabler for self-organisation in future cellular networks

International Nuclear Information System (INIS)

Imran, Muhammad Ali; Onireti, Oluwakayode; Imran, Ali

2013-01-01

In this short review paper we summarise the emerging challenges in the field of participatory sensing for the self-organisation of the next generation of wireless cellular networks. We identify the potential of participatory sensing in enabling the self-organisation, deployment optimisation and radio resource management of wireless cellular networks. We also highlight how this approach can meet the future goals for the next generation of cellular system in terms of infrastructure sharing, management of multiple radio access techniques, flexible usage of spectrum and efficient management of very small data cells

An efficient structural finite element for inextensible flexible risers

Science.gov (United States)

Papathanasiou, T. K.; Markolefas, S.; Khazaeinejad, P.; Bahai, H.

2017-12-01

A core part of all numerical models used for flexible riser analysis is the structural component representing the main body of the riser as a slender beam. Loads acting on this structural element are self-weight, buoyant and hydrodynamic forces, internal pressure and others. A structural finite element for an inextensible riser with a point-wise enforcement of the inextensibility constrain is presented. In particular, the inextensibility constraint is applied only at the nodes of the meshed arc length parameter. Among the virtues of the proposed approach is the flexibility in the application of boundary conditions and the easy incorporation of dissipative forces. Several attributes of the proposed finite element scheme are analysed and computation times for the solution of some simplified examples are discussed. Future developments aim at the appropriate implementation of material and geometric parameters for the beam model, i.e. flexural and torsional rigidity.

Inclusion of Structural Flexibility in Design Load Analysis for Wave Energy Converters: Preprint

Energy Technology Data Exchange (ETDEWEB)

Guo, Yi [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); van Rij, Jennifer A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-08-14

Hydroelastic interactions, caused by ocean wave loading on wave energy devices with deformable structures, are studied in the time domain. A midfidelity, hybrid modeling approach of rigid-body and flexible-body dynamics is developed and implemented in an open-source simulation tool for wave energy converters (WEC-Sim) to simulate the dynamic responses of wave energy converter component structural deformations under wave loading. A generalized coordinate system, including degrees of freedom associated with rigid bodies, structural modes, and constraints connecting multiple bodies, is utilized. A simplified method of calculating stress loads and sectional bending moments is implemented, with the purpose of sizing and designing wave energy converters. Results calculated using the method presented are verified with those of high-fidelity fluid-structure interaction simulations, as well as low-fidelity, frequency-domain, boundary element method analysis.

Reduced labor and condensed schedules with cellular concrete solutions

Energy Technology Data Exchange (ETDEWEB)

Lavis, D. [CEMATRIX Inc., Calgary, AB (Canada)

2008-07-01

This paper discussed the use of cellular concrete materials in oil sands tank base foundation systems, shallow buried utility insulation systems, roadways, slabs, and buried modules. The concrete is formed from Portland cement, water, specialized pre-formed foaming agents, and air mixed in controlled proportions. Fly ash and polypropylene or glass fibers can also be used as additions. Cellular concrete can often be used to speed up construction and minimize labour requirements. Cellular concrete can be cast-in-place, and has soil-stabilizing and self-compacting features. The concrete can be produced and placed on-site at rates exceeding 120 cubic meters per hour. Cellular concrete can be pumped into place over long distances through flexible hoses. A case study comparing the cellular concrete to traditional plastic foam insulation was used to demonstrate the equivalency and adequacy of insulation, structural properties and installation costs. The study showed that although the cellular concrete had a high installation cost, greater compressive strength was gained. The concrete was self-levelling and did not require compaction or vibration. The use of the cellular concrete resulted in an accelerated construction schedule. 6 refs., 2 tabs., 6 figs.

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF FLEXIBLE BURIED PIPE DEFORMATION BEHAVIOR UNDER VARIOUS BACKFILL CONDITIONS

Directory of Open Access Journals (Sweden)

Niyazi Uğur TERZİ

2009-01-01

Full Text Available Deformation characteristics of polyethylene based flexible pipes are different than rigid pipes such as concrete and iron pipes. Deflection patterns and stress-strain behaviors of flexible pipes have strict relation between the engineering properties of backfill and its settlement method. In this study, deformation behavior of a 100 mm HDPE flexible pipe under vertical loads is investigated in laboratory conditions. Steel test box, pressurized membrane, raining system, linear position transducers and strain gauge rosettes are used in the laboratory tests. In order to analyze the buried pipe performance; Masada Derivation Formula which is mostly used by designers is employed. According to the test and mathematical studies, it is understood that relative density of backfill and its settlement method is a considerable effect on buried pipe performance and Masada Derivation method is very efficient for predicting the pipe performance.

Optimum Wing Shape of Highly Flexible Morphing Aircraft for Improved Flight Performance

Science.gov (United States)

Su, Weihua; Swei, Sean Shan-Min; Zhu, Guoming G.

2016-01-01

In this paper, optimum wing bending and torsion deformations are explored for a mission adaptive, highly flexible morphing aircraft. The complete highly flexible aircraft is modeled using a strain-based geometrically nonlinear beam formulation, coupled with unsteady aerodynamics and six-degrees-of-freedom rigid-body motions. Since there are no conventional discrete control surfaces for trimming the flexible aircraft, the design space for searching the optimum wing geometries is enlarged. To achieve high performance flight, the wing geometry is best tailored according to the specific flight mission needs. In this study, the steady level flight and the coordinated turn flight are considered, and the optimum wing deformations with the minimum drag at these flight conditions are searched by utilizing a modal-based optimization procedure, subject to the trim and other constraints. The numerical study verifies the feasibility of the modal-based optimization approach, and shows the resulting optimum wing configuration and its sensitivity under different flight profiles.

Quantitative evaluation of flexibility in undergraduate engineering curricula in the United Arab Emirates

Directory of Open Access Journals (Sweden)

Naif A. Darwish

2016-03-01

Full Text Available In academia, smooth progression of students significantly depends on the way curricula are developed and organized. Curricula or study plans with high degree of interconnectivity between courses, multiple prerequisites, and hierarchically structured courses tend to complicate the smooth progress of the enrolled students. In this work, a rigorous quantitative relaxation indicator, developed and published elsewhere by the first author, has been applied to quantify the degree of stiffness and rigidity in undergraduate engineering curricula at the American University of Sharjah (AUS, the University of Sharjah (UOS, United Arab Emirates University (UAEU, and the Petroleum Institute (PI, which are the leading universities in the United Arab Emirates. Results indicate high rigidity (low relaxation indices due to high degree of interconnectivity between courses, specifically in the second year of the study plans. The chemical engineering curriculum at PI exhibited the least flexibility due to very strong pre-and-co-requisite ties while the civil & environmental curriculum at UAEU showed the highest flexibility. The curricula considered require immediate attention and reorganization in order to facilitate smooth sequential progress of the students from one semester to another. A list of courses that require relaxation of strong pre-and corequisites ties has been presented for each curriculum.

Flexible histone tails in a new mesoscopic oligonucleosome model.

Science.gov (United States)

Arya, Gaurav; Zhang, Qing; Schlick, Tamar

2006-07-01

We describe a new mesoscopic model of oligonucleosomes that incorporates flexible histone tails. The nucleosome cores are modeled using the discrete surface-charge optimization model, which treats the nucleosome as an electrostatic surface represented by hundreds of point charges; the linker DNAs are treated using a discrete elastic chain model; and the histone tails are modeled using a bead/chain hydrodynamic approach as chains of connected beads where each bead represents five protein residues. Appropriate charges and force fields are assigned to each histone chain so as to reproduce the electrostatic potential, structure, and dynamics of the corresponding atomistic histone tails at different salt conditions. The dynamics of resulting oligonucleosomes at different sizes and varying salt concentrations are simulated by Brownian dynamics with complete hydrodynamic interactions. The analyses demonstrate that the new mesoscopic model reproduces experimental results better than its predecessors, which modeled histone tails as rigid entities. In particular, our model with flexible histone tails: correctly accounts for salt-dependent conformational changes in the histone tails; yields the experimentally obtained values of histone-tail mediated core/core attraction energies; and considers the partial shielding of electrostatic repulsion between DNA linkers as a result of the spatial distribution of histone tails. These effects are crucial for regulating chromatin structure but are absent or improperly treated in models with rigid histone tails. The development of this model of oligonucleosomes thus opens new avenues for studying the role of histone tails and their variants in mediating gene expression through modulation of chromatin structure.

Anisotropic thermal expansion in flexible materials

Science.gov (United States)

Romao, Carl P.

2017-10-01

A definition of the Grüneisen parameters for anisotropic materials is derived based on the response of phonon frequencies to uniaxial stress perturbations. This Grüneisen model relates the thermal expansion in a given direction (αi i) to one element of the elastic compliance tensor, which corresponds to the Young's modulus in that direction (Yi i). The model is tested through ab initio prediction of thermal expansion in zinc, graphite, and calcite using density functional perturbation theory, indicating that it could lead to increased accuracy for structurally complex systems. The direct dependence of αi i on Yi i suggests that materials which are flexible along their principal axes but rigid in other directions will generally display both positive and negative thermal expansion.

A semi-analytical bearing model considering outer race flexibility for model based bearing load monitoring

Science.gov (United States)

Kerst, Stijn; Shyrokau, Barys; Holweg, Edward

2018-05-01

This paper proposes a novel semi-analytical bearing model addressing flexibility of the bearing outer race structure. It furthermore presents the application of this model in a bearing load condition monitoring approach. The bearing model is developed as current computational low cost bearing models fail to provide an accurate description of the more and more common flexible size and weight optimized bearing designs due to their assumptions of rigidity. In the proposed bearing model raceway flexibility is described by the use of static deformation shapes. The excitation of the deformation shapes is calculated based on the modelled rolling element loads and a Fourier series based compliance approximation. The resulting model is computational low cost and provides an accurate description of the rolling element loads for flexible outer raceway structures. The latter is validated by a simulation-based comparison study with a well-established bearing simulation software tool. An experimental study finally shows the potential of the proposed model in a bearing load monitoring approach.

49 CFR 587.18 - Dimensions of fixed rigid barrier.

Science.gov (United States)

2010-10-01

... TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS Offset Deformable Barrier § 587.18 Dimensions of fixed rigid barrier. (a) The fixed rigid barrier has a mass of not... 49 Transportation 7 2010-10-01 2010-10-01 false Dimensions of fixed rigid barrier. 587.18 Section...

RIGIDITY, SENSITIVITY AND QUALITY OF ATTACHMENT - THE ROLE OF MATERNAL RIGIDITY IN THE EARLY SOCIOEMOTIONAL DEVELOPMENT OF PREMATURE-INFANTS

NARCIS (Netherlands)

BUTCHER, PR; KALVERBOER, A; MINDERAA, RB; VANDOORMAAL, EF; TENWOLDE, Y

1993-01-01

The associations between a mother's rigidity, her sensitivity in early (3 month) interaction and the quality of her premature infant's attachment at 13 months were investigated. Rigidity as a personality characteristic was not found to be significantly associated with sensitivity or quality of

Flat flexible polymer heat pipes

International Nuclear Information System (INIS)

Oshman, Christopher; Li, Qian; Liew, Li-Anne; Yang, Ronggui; Bright, Victor M; Lee, Y C

2013-01-01

Flat, flexible, lightweight, polymer heat pipes (FPHP) were fabricated. The overall geometry of the heat pipe was 130 mm × 70 mm × 1.31 mm. A commercially available low-cost film composed of laminated sheets of low-density polyethylene terephthalate, aluminum and polyethylene layers was used as the casing. A triple-layer sintered copper woven mesh served as a liquid wicking structure, and water was the working fluid. A coarse nylon woven mesh provided space for vapor transport and mechanical rigidity. Thermal power ranging from 5 to 30 W was supplied to the evaporator while the device was flexed at 0°, 45° and 90°. The thermal resistance of the FPHP ranged from 1.2 to 3.0 K W −1 depending on the operating conditions while the thermal resistance for a similar-sized solid copper reference was a constant at 4.6 K W −1 . With 25 W power input, the thermal resistance of the liquid–vapor core of the FPHP was 23% of a copper reference sample with identical laminated polymer material. This work shows a promising combination of technologies that has the potential to usher in a new generation of highly flexible, lightweight, low-cost, high-performance thermal management solutions. (paper)

Direct fabrication of rigid microstructures on a metallic roller using a dry film resist

International Nuclear Information System (INIS)

Jiang, Liang-Ting; Huang, Tzu-Chien; Chang, Chih-Yuan; Ciou, Jian-Ren; Yang, Sen-Yeu; Huang, Po-Hsun

2008-01-01

This paper presents a novel method to fabricate a metallic roller mold with microstructures on its surface using a dry film resist (DFR). The DFR is laminated uniformly onto the curvy surface of a copper roller. After that, the micro-scale photoresist on the surface of the roller can be patterned by non-planar lithography using a flexible film photomask, followed by ferric chloride wet etching to obtain the desired microstructures. This method overcomes the uniformity issue of photoresist coating on rollers, and solves the molds sliding problem during the embossing process because the microstructures are fabricated directly on the roller surface. Furthermore, the rigid metallic roller mold has excellent strength durability and temperature endurance, which can be used in roller hot embossing with a high embossing pressure. The fabricated microstructure roller mold is used as a mold in the hybrid extrusion roller embossing process and successfully fabricates uniform micro-scale prominent line arrays on PC films. This result proves that the roller fabricated by this method can be successfully used in roller embossing for microstructure mass production. The excellent flatness of dry film resist laminating is the key in this fabrication process. The flexible film photomask can be easily designed using CAD software; this roller fabrication method enhances the design flexibility and reduces the cost and time

Molecular model for solubility of gases in flexible polymers

DEFF Research Database (Denmark)

Neergaard, Jesper; Hassager, Ole; Szabo, Peter

1999-01-01

We propose a model for a priori prediction of the solubility of gases in flexible polymers. The model is based on the concept of ideal solubility of gases in liquids. According to this concept, the mole fraction of gases in liquids is given by Raoult's law with the total pressure and the vapor...... pressure of the gas, where the latter may have to be extrapolated. However, instead of considering each polymer molecule as a rigid structure, we estimate the effective number of degrees of freedom from an equivalent freely jointed bead-rod model for the flexible polymer. In this model, we associate...... the length of the rods with the molecular weight corresponding to a Kuhn step. The model provides a tool for crude estimation of the gas solubility on the basis of only the monomer unit of the polymer and properties of the gas. A comparison with the solubility data for several gases in poly...

FINITE ELEMENT ANALYSIS OF CONCRETE FILLER INFLUENCE ON DYNAMIC RIGIDITY OF HEAVY MACHINE TOOL PORTAL

Directory of Open Access Journals (Sweden)

Yu. V. Vasilevich

2016-01-01

Full Text Available Virtual testing of portal machine tool has been carried out with the help of finite elements method (FEM. Static, modal and harmonic analyses have been made for a heavy planer. The paper reveals influence of concrete filler on machine tool dynamic flexibility. A peculiar feature of the simulation is concrete filling of a high-level transverse beam. Such approach oes look a typical one for machine-tool industry. Concrete has been considered as generalized material in two variants. It has been established that concrete application provides approximately 3-fold increase in machine tool rigidity per each coordinate. In this regard it is necessary to arrange closure of rigidity contour by filling all the cavities inside of the portal. Modal FEA makes it possible to determine that concrete increases comparatively weakly (1.3–1.4-fold frequencies of resonance modes. Frequency of the lowest mode rises only from 30.25 to 42.86 Hz. The following most active whole-machine eigenmodes have been revealed in the paper: “Portal pecking”, “Parallelogram” and “Traverse pecking”. In order to restrain the last mode it is necessary to carry out concrete filling of the traverse, in particular. Frequency-response characteristics and curves of dynamic rigidity for a spindle have been plotted for 0–150 Hz interval while using harmonic FEM. It has been determined that concrete increases dynamic machine tool rigidity by 2.5–3.5-fold. The effect is obtained even in the case when weakly damping concrete (2 % is used. This is due to distribution of vibrational energy flow along concrete and along cast iron as well. Thus energy density and vibration amplitudes must decrease. The paper shows acceptability for internal reinforcement of high-level machine tool parts (for example, portal traverses and fillers are applied for this purpose. Traverse weighting is compensated by additional torsional, shear and bending rigidity. The machine tool obtains the

Multiscale evaluation of cellular adhesion alteration and cytoskeleton remodeling by magnetic bead twisting.

Science.gov (United States)

Isabey, Daniel; Pelle, Gabriel; André Dias, Sofia; Bottier, Mathieu; Nguyen, Ngoc-Minh; Filoche, Marcel; Louis, Bruno

2016-08-01

Cellular adhesion forces depend on local biological conditions meaning that adhesion characterization must be performed while preserving cellular integrity. We presently postulate that magnetic bead twisting provides an appropriate stress, i.e., basically a clamp, for assessment in living cells of both cellular adhesion and mechanical properties of the cytoskeleton. A global dissociation rate obeying a Bell-type model was used to determine the natural dissociation rate ([Formula: see text]) and a reference stress ([Formula: see text]). These adhesion parameters were determined in parallel to the mechanical properties for a variety of biological conditions in which either adhesion or cytoskeleton was selectively weakened or strengthened by changing successively ligand concentration, actin polymerization level (by treating with cytochalasin D), level of exerted stress (by increasing magnetic torque), and cell environment (by using rigid and soft 3D matrices). On the whole, this multiscale evaluation of the cellular and molecular responses to a controlled stress reveals an evolution which is consistent with stochastic multiple bond theories and with literature results obtained with other molecular techniques. Present results confirm the validity of the proposed bead-twisting approach for its capability to probe cellular and molecular responses in a variety of biological conditions.

A coarse-grained model for the simulations of biomolecular interactions in cellular environments

International Nuclear Information System (INIS)

Xie, Zhong-Ru; Chen, Jiawen; Wu, Yinghao

2014-01-01

The interactions of bio-molecules constitute the key steps of cellular functions. However, in vivo binding properties differ significantly from their in vitro measurements due to the heterogeneity of cellular environments. Here we introduce a coarse-grained model based on rigid-body representation to study how factors such as cellular crowding and membrane confinement affect molecular binding. The macroscopic parameters such as the equilibrium constant and the kinetic rate constant are calibrated by adjusting the microscopic coefficients used in the numerical simulations. By changing these model parameters that are experimentally approachable, we are able to study the kinetic and thermodynamic properties of molecular binding, as well as the effects caused by specific cellular environments. We investigate the volumetric effects of crowded intracellular space on bio-molecular diffusion and diffusion-limited reactions. Furthermore, the binding constants of membrane proteins are currently difficult to measure. We provide quantitative estimations about how the binding of membrane proteins deviates from soluble proteins under different degrees of membrane confinements. The simulation results provide biological insights to the functions of membrane receptors on cell surfaces. Overall, our studies establish a connection between the details of molecular interactions and the heterogeneity of cellular environments

Persistency and flexibility of complex brain networks underlie dual-task interference.

Science.gov (United States)

Alavash, Mohsen; Hilgetag, Claus C; Thiel, Christiane M; Gießing, Carsten

2015-09-01

Previous studies on multitasking suggest that performance decline during concurrent task processing arises from interfering brain modules. Here, we used graph-theoretical network analysis to define functional brain modules and relate the modular organization of complex brain networks to behavioral dual-task costs. Based on resting-state and task fMRI we explored two organizational aspects potentially associated with behavioral interference when human subjects performed a visuospatial and speech task simultaneously: the topological overlap between persistent single-task modules, and the flexibility of single-task modules in adaptation to the dual-task condition. Participants showed a significant decline in visuospatial accuracy in the dual-task compared with single visuospatial task. Global analysis of topological similarity between modules revealed that the overlap between single-task modules significantly correlated with the decline in visuospatial accuracy. Subjects with larger overlap between single-task modules showed higher behavioral interference. Furthermore, lower flexible reconfiguration of single-task modules in adaptation to the dual-task condition significantly correlated with larger decline in visuospatial accuracy. Subjects with lower modular flexibility showed higher behavioral interference. At the regional level, higher overlap between single-task modules and less modular flexibility in the somatomotor cortex positively correlated with the decline in visuospatial accuracy. Additionally, higher modular flexibility in cingulate and frontal control areas and lower flexibility in right-lateralized nodes comprising the middle occipital and superior temporal gyri supported dual-tasking. Our results suggest that persistency and flexibility of brain modules are important determinants of dual-task costs. We conclude that efficient dual-tasking benefits from a specific balance between flexibility and rigidity of functional brain modules. © 2015 Wiley

Floating substructure flexibility of large-volume 10MW offshore wind turbine platforms in dynamic calculations

International Nuclear Information System (INIS)

Borg, Michael; Hansen, Anders Melchior; Bredmose, Henrik

2016-01-01

Designing floating substructures for the next generation of 10MW and larger wind turbines has introduced new challenges in capturing relevant physical effects in dynamic simulation tools. In achieving technically and economically optimal floating substructures, structural flexibility may increase to the extent that it becomes relevant to include in addition to the standard rigid body substructure modes which are typically described through linear radiation-diffraction theory. This paper describes a method for the inclusion of substructural flexibility in aero-hydro-servo-elastic dynamic simulations for large-volume substructures, including wave-structure interactions, to form the basis of deriving sectional loads and stresses within the substructure. The method is applied to a case study to illustrate the implementation and relevance. It is found that the flexible mode is significantly excited in an extreme event, indicating an increase in predicted substructure internal loads. (paper)

Cracking of open traffic rigid pavement

Directory of Open Access Journals (Sweden)

Niken Chatarina

2017-01-01

Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.

Validated simulator for space debris removal with nets and other flexible tethers applications

Science.gov (United States)

Gołębiowski, Wojciech; Michalczyk, Rafał; Dyrek, Michał; Battista, Umberto; Wormnes, Kjetil

2016-12-01

In the context of active debris removal technologies and preparation activities for the e.Deorbit mission, a simulator for net-shaped elastic bodies dynamics and their interactions with rigid bodies, has been developed. Its main application is to aid net design and test scenarios for space debris deorbitation. The simulator can model all the phases of the debris capturing process: net launch, flight and wrapping around the target. It handles coupled simulation of rigid and flexible bodies dynamics. Flexible bodies were implemented using Cosserat rods model. It allows to simulate flexible threads or wires with elasticity and damping for stretching, bending and torsion. Threads may be combined into structures of any topology, so the software is able to simulate nets, pure tethers, tether bundles, cages, trusses, etc. Full contact dynamics was implemented. Programmatic interaction with simulation is possible - i.e. for control implementation. The underlying model has been experimentally validated and due to significant gravity influence, experiment had to be performed in microgravity conditions. Validation experiment for parabolic flight was a downscaled process of Envisat capturing. The prepacked net was launched towards the satellite model, it expanded, hit the model and wrapped around it. The whole process was recorded with 2 fast stereographic camera sets for full 3D trajectory reconstruction. The trajectories were used to compare net dynamics to respective simulations and then to validate the simulation tool. The experiments were performed on board of a Falcon-20 aircraft, operated by National Research Council in Ottawa, Canada. Validation results show that model reflects phenomenon physics accurately enough, so it may be used for scenario evaluation and mission design purposes. The functionalities of the simulator are described in detail in the paper, as well as its underlying model, sample cases and methodology behind validation. Results are presented and

Bionics in textiles: flexible and translucent thermal insulations for solar thermal applications.

Science.gov (United States)

Stegmaier, Thomas; Linke, Michael; Planck, Heinrich

2009-05-13

Solar thermal collectors used at present consist of rigid and heavy materials, which are the reasons for their immobility. Based on the solar function of polar bear fur and skin, new collector systems are in development, which are flexible and mobile. The developed transparent heat insulation material consists of a spacer textile based on translucent polymer fibres coated with transparent silicone rubber. For incident light of the visible spectrum the system is translucent, but impermeable for ultraviolet radiation. Owing to its structure it shows a reduced heat loss by convection. Heat loss by the emission of long-wave radiation can be prevented by a suitable low-emission coating. Suitable treatment of the silicone surface protects it against soiling. In combination with further insulation materials and flow systems, complete flexible solar collector systems are in development.

Effect of torus wall flexibility on hydro-structural interaction in BWR containment system

International Nuclear Information System (INIS)

Lu, S.C.H.; McCauley, E.W.; Holman, G.S.

1979-01-01

The MARK I boiling water reactor (BWR) containment system is comprised of a light-bulb-shaped reactor compartment connected through vent pipes to a torus-shaped and partially water-filled pressure suppression chamber, or the wetwell. During either a normally occurring safety relief valve (SRV) discharge or a hypothetical loss-of-coolant accident (LOCA), air or steam is forced into the wetwell water pool for condensation and results in hydrodynamically induced loads on the torus shell. An analytical program is described which employs the finite element method to investigate the influence of torus wall flexibility on hydrodynamically induced pressure and the resultant force on the torus shell surface. The shell flexibility is characterized by the diameter-to-thickness ratio which is varied from the perfectly rigid case to the nominal plant condition. The general conclusion reached is that torus wall flexibility decreases both the maximum pressure seen by the shell wall and the total vertical load resulted from the hydrodynamically induced pressure

A flexible ligand-based wavy layered metal-organic framework for lithium-ion storage.

Science.gov (United States)

An, Tiance; Wang, Yuhang; Tang, Jing; Wang, Yang; Zhang, Lijuan; Zheng, Gengfeng

2015-05-01

A substantial challenge for direct utilization of metal-organic frameworks (MOFs) as lithium-ion battery anodes is to maintain the rigid MOF structure during lithiation/delithiation cycles. In this work, we developed a flexible, wavy layered nickel-based MOF (C20H24Cl2N8Ni, designated as Ni-Me4bpz) by a solvothermal approach of 3,3',5,5'-tetramethyl-4,4'-bipyrazole (H2Me4bpz) with nickel(II) chloride hexahydrate. The obtained MOF materials (Ni-Me4bpz) with metal azolate coordination mode provide 2-dimensional layered structure for Li(+) intercalation/extraction, and the H2Me4bpz ligands allow for flexible rotation feature and structural stability. Lithium-ion battery anodes made of the Ni-Me4bpz material demonstrate excellent specific capacity and cycling performance, and the crystal structure is well preserved after the electrochemical tests, suggesting the potential of developing flexible layered MOFs for efficient and stable electrochemical storage. Copyright © 2015 Elsevier Inc. All rights reserved.

Flexible Structural Design for Side-Sliding Force Reduction for a Caterpillar Climbing Robot

Directory of Open Access Journals (Sweden)

Weina Cui

2012-11-01

Full Text Available Due to sliding force arising from the closed chain mechanism among the adhering points of a climbing caterpillar robot (CCR, a sliding phenomenon will happen at the adhering points, e.g., the vacuum pads or claws holding the surface. This sliding force makes the attachment of the climbing robot unsteady and reducesthe motion efficiency. According to the new bionic research on the soft-body structure of caterpillars, some flexible structures made of natural rubber bars are applied in CCRs correspondingly as an improvement to the old rigid mechanical design of the robotic structure. This paper firstly establishes the static model of the sliding forces, the distortion of flexible bars and the driving torques of joints. Then, a method to reduce the sliding force by exerting a compensating angle to an active joint of the CCR is presented. The analyses and experimental results indicate that the flexible structure and the compensating angle method can reduce the sliding forces remarkably.

Effects of torus wall flexibility on forces in the Mark I Boiling Water Reactor Pressure Suppression System. Part I

International Nuclear Information System (INIS)

Martin, R.W.; McCauley, E.W.

1977-09-01

The authors investigated the effects of torus wall flexibility in the pressure suppression system of a Mark I boiling water reactor (BWR) when the torus wall is subjected to hydrodynamic loadings. Using hypothetical models, they examined these flexibility effects under two hydrodynamic loading conditions: (1) a steam relief valve (SRV) discharge pulse, and (2) a loss-of-coolant accident (LOCA) chugging pulse. In the analyses of these events they used a recently developed two-dimensional finite element computer code. Taking the basic geometry and dimensions of the Monticello Mark I BWR nuclear power plant (in Monticello, Minnesota, U.S.A.), they assessed the effects of flexibility in the torus wall by changing values of the inside-diameter-to-wall-thickness ratio. Varying the torus wall thickness (t) with respect to the inside diameter (D) of the torus, they assigned values to the ratio D/t ranging from 0 (infinitely rigid) to 600 (highly flexible). In the case of a modeled steam relief valve (SRV) discharge pulse, they found the peak vertical reaction force on the torus was reduced from that of a rigid wall response by a factor of 3 for the most highly flexible, plant-simulated wall (D/t = 600). The reduction factor for a modeled loss-of-coolant accident (LOCA) chugging pulse was shown to be 1.5. The two-dimensional analyses employed overestimate these reduction factors but have provided, as intended, definition of the effect of torus boundary stiffness. In the work planned for FY79, improved modeling of the structure and of the source is expected to result in factors more directly applicable to actual pressure suppression systems

Flexibility of working hours in the 24-hour society.

Science.gov (United States)

Costa, G

2006-01-01

The 24-hour Society undergoes an ineluctable process towards a social organisation where time constraints are no more restricting human life. The borders between working and social times are no more fixed and rigidly determined, and the value of working time changes according to the different economic and social effects you may consider. Shift and night work, irregular and flexible working hours, together with new technologies, are the milestone of this epochal passage. What are the advantages and disadvantages for the individual, the companies, and the society? What is the cost/benefit ratio in terms of health and social well-being? Coping properly with this process means avoiding a passive acceptance of it with consequent maladjustments at both individual and social level, but adopting effective preventive and compensative strategies aimed at building up a more sustainable society. Flexible working times now appear to be one of the best ways to cope with the demands of the modern life, but there are different points of view about labour and temporal 'flexibility" between employers and employees. For the former it means a prompt adaptation to market demands and technological innovations; for the latter it is a way to improve working and social life, by decreasing work constraints and increasing control and autonomy. Although it can be easily speculated that individual-based 'flexibility" should improve health and well-being, and especially satisfaction, whereas company-based flexibility" might interfere negatively, the effective consequences on health and well-being have still to be analysed properly.

Reversible Rigidity Control Using Low Melting Temperature Alloys

Science.gov (United States)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-03-01

Inspired by nature, materials able to achieve rapid rigidity changes have important applications for human body protection in military and many other areas. This talk presents the fabrication and design of soft-matter technologies that exhibit rapid reversible rigidity control. Fabricated with a masked deposition technique, the soft-matter composite contains liquid-phase and phase-changing metal alloys embedded in a soft and highly stretchable elastomer. The composite material can reversibly change its rigidity by three orders of magnitude and sustain large deformation.

Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish.

Directory of Open Access Journals (Sweden)

Mari Kojima

Full Text Available A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH and poly(dimethylsiloxane (PDMS having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min. We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3 and dentate gyrus (DG.

Fabrication of ferroelectric polymer nanostructures on flexible substrates by soft-mold reverse nanoimprint lithography

International Nuclear Information System (INIS)

Song, Jingfeng; Lu, Haidong; Gruverman, Alexei; Ducharme, Stephen; Li, Shumin; Tan, Li

2016-01-01

Conventional nanoimprint lithography with expensive rigid molds is used to pattern ferroelectric polymer nanostructures on hard substrate for use in, e.g., organic electronics. The main innovation here is the use of inexpensive soft polycarbonate molds derived from recordable DVDs and reverse nanoimprint lithography at low pressure, which is compatible with flexible substrates. This approach was implemented to produce regular stripe arrays with a spacing of 700 nm from vinylidene fluoride co trifluoroethylene ferroelectric copolymer on flexible polyethylene terephthalate substrates. The nanostructures have very stable and switchable piezoelectric response and good crystallinity, and are highly promising for use in organic electronics enhanced or complemented by the unique properties of the ferroelectric polymer, such as bistable polarization, piezoelectric response, pyroelectric response, or electrocaloric function. The soft-mold reverse nanoimprint lithography also leaves little or no residual layer, affording good isolation of the nanostructures. This approach reduces the cost and facilitates large-area, high-throughput production of isolated functional polymer nanostructures on flexible substrates for the increasing application of ferroelectric polymers in flexible electronics. (paper)

Fabrication of ferroelectric polymer nanostructures on flexible substrates by soft-mold reverse nanoimprint lithography.

Science.gov (United States)

Song, Jingfeng; Lu, Haidong; Li, Shumin; Tan, Li; Gruverman, Alexei; Ducharme, Stephen

2016-01-08

Conventional nanoimprint lithography with expensive rigid molds is used to pattern ferroelectric polymer nanostructures on hard substrate for use in, e.g., organic electronics. The main innovation here is the use of inexpensive soft polycarbonate molds derived from recordable DVDs and reverse nanoimprint lithography at low pressure, which is compatible with flexible substrates. This approach was implemented to produce regular stripe arrays with a spacing of 700 nm from vinylidene fluoride co trifluoroethylene ferroelectric copolymer on flexible polyethylene terephthalate substrates. The nanostructures have very stable and switchable piezoelectric response and good crystallinity, and are highly promising for use in organic electronics enhanced or complemented by the unique properties of the ferroelectric polymer, such as bistable polarization, piezoelectric response, pyroelectric response, or electrocaloric function. The soft-mold reverse nanoimprint lithography also leaves little or no residual layer, affording good isolation of the nanostructures. This approach reduces the cost and facilitates large-area, high-throughput production of isolated functional polymer nanostructures on flexible substrates for the increasing application of ferroelectric polymers in flexible electronics.

Determination of Weight Suspension Rigidity in the Transport-Erector Aggregates

Directory of Open Access Journals (Sweden)

V. A. Zverev

2016-01-01

Full Text Available The aim is to determine weight suspension rigidity in aggregates designed to perform technological transport-erector operations at the miscellaneous launch complexes.We consider the weight suspension comprising the following distinctive structural components: the executive weight-lowering mechanism, polyspast mechanism, rope, traverse, and rods. A created structural dynamic model of suspension allowed us to define weight suspension rigidity. Within the framework of design analysis of a dynamic model we determined the rigidity of its structural units, i.e. traverse, rope, and polyspast.Known analytical relationships were used to calculate the rope rigidity. To determine rigidity of polyspast and traverse have been created special models based on the finite element method. For each model deformation in the specific points under the test load have been defined. Data obtained were used to determine trigidity of traverses and polyspast, and also rigidity of suspension in total. The rigidity models of polispast mechanism and traverse have been developed and calculated using the software complex "Zenit-95".As the research results, the paper presents a dynamic model of the weight suspension of the transport-erector aggregate, the finite element models of the polispast mechanism and traverse, an algorithm for determining the weight suspension rigidity and relevant analytical relationships.Independent calculation of weight suspension rigidity enables us to simplify further dynamic calculation of the aggregate-weight system because it allows attaining a simpler model of the aggregate-weight system that uses the weight suspension model as an element of equivalent rigidity. Despite this simplification the model allows us to determine correctly weight movement parameters and overloads in the aggregate-weight system in the process of technical operations.

Influence of flock coating on bending rigidity of woven fabrics

Science.gov (United States)

Ozdemir, O.; Kesimci, M. O.

2017-10-01

This work presents the preliminary results of our efforts that focused on the effect of the flock coating on the bending rigidity of woven fabrics. For this objective, a laboratory scale flocking unit is designed and flocked samples of controlled flock density are produced. Bending rigidity of the samples with different flock densities are measured on both flocked and unflocked sides. It is shown that the bending rigidity depends on both flock density and whether the side to be measured is flocked or not. Adhesive layer thickness on the bending rigidity is shown to be dramatic. And at higher basis weights, flock density gets less effective on bending rigidity.

Intelligent control system Cellular Robotics Approach to Nuclear Plant control and maintenance

International Nuclear Information System (INIS)

Fukuda, Toshio; Sekiyama, Kousuke; Xue Guoqing; Ueyama, Tsuyoshi.

1994-01-01

This paper presents the concept of Cellular Robotic System (CEBOT) and describe the strategy of a distributed sensing, control and planning as a Cellular Robotics Approach to the Nuclear Plant control and maintenance. Decentralized System is effective in large plant and The CEBOT possesses desirable features for realization of Nuclear Plant control and maintenance because of its flexibility and adaptability. Also, as related on going research work, self-organizing manipulator and communication issues are mentioned. (author)

On the Influence of Hull Girder Flexibility on the Wave

DEFF Research Database (Denmark)

Seng, Sopheak; Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

2012-01-01

Numerical predictions and model test results of the wave induced bending moments in a 9,400 TEU post-Panamax container vessel are presented for two regular wave scenarios. Different numerical procedures have been applied: a linear and non-linear time-domain strip theory and a direct calculation (...... (CFD) solving the Navier-Stokes equations with the free surface captured by a volume-of-fluid (VOF) method. In all procedures the flexibility of the hull girder is modelled as a non-uniform Timoshenko beam. It is observed that the non-linear models agree well with the model tests...... and as there is no occurrence of severe slamming in the cases considered, the inexpensive non-linear strip theory is as accurate as the direct CFD calculation method. In a comparison with the results using the rigid body assumption, the increase in the vertical bending moment (VBM) amidships due to the flexibility of the hull...... girder is found to be approximately 7% (peak-to-peak amplitude) in general. The non-linear responses, however, contain over-harmonic frequencies which may coincide with the natural frequency of the two-node vertical bending mode inducing resonance. In that case the hull girder flexibility causes...

Role of intrachain rigidity in the plasticization of intrinsically microporous triptycene-based polyimide membranes in mixed-Gas CO2/CH4 separations

KAUST Repository

Swaidan, Raja

2014-11-11

Based on high-pressure pure- and mixed-gas (50:50) CO2/CH4 separation properties of two intrinsically microporous triptycene-based polyimides (TPDA-TMPD and TPDA-6FpDA), the intrachain rigidity central to "conventional PIM" design principles is not a singular solution to intrinsic plasticization resistance. Despite the significant intrachain rigidity in TPDA-TMPD, a 300% increase in PMIX(CH4), 50% decrease in α(CO2/CH4) from 24 to 12, and continuous increase in PMIX(CO2) occurred from 4 to 30 bar. On the other hand, the more flexible and densely packed TPDA-6FpDA exhibited a slight upturn in PMIX(CO2) at 20 bar similar to a dense cellulose acetate (CA) film, also reported here, despite a 4-fold higher CO2 sorption capacity. Microstructural investigations suggest that the interconnected O2- and H2-sieving ultramicroporosity of TPDA-TMPD is more sensitive to slight CO2-induced dilations and is the physical basis for a more extensive and accelerated plasticization. Interchain rigidity, potentially by interchain interactions, is emphasized and may be facilitated by intrachain mobility.

Strategies for spatial and technological flexibility

Directory of Open Access Journals (Sweden)

Cristiana Cellucci

2014-10-01

Full Text Available The design of housing sys- tems is today challenged by a highly uncertain context, dominated by the rapid development of functional and technological obsolescence in inherited housing models. The design of housing systems should first and foremost optimise the longevity of the sub-systems and be able to offset the process of obsolescence which is concomitant to both the current use of materials and components devised to fail after a short period, and to rigid spatial models that are incapable of adapting to changes in the household’s needs over time. This research examines flexibility as a fundamental requirement to be incorporated in the Life Cycle of the house, through the use of strategies that affect both the form and the technological system that governs its structure.

Soft-matter composites with electrically tunable elastic rigidity

International Nuclear Information System (INIS)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-01-01

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium–indium–tin (Galinstan ® ) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy. (paper)

Soft-matter composites with electrically tunable elastic rigidity

Science.gov (United States)

Shan, Wanliang; Lu, Tong; Majidi, Carmel

2013-08-01

We use a phase-changing metal alloy to reversibly tune the elastic rigidity of an elastomer composite. The elastomer is embedded with a sheet of low-melting-point Field’s metal and an electric Joule heater composed of a serpentine channel of liquid-phase gallium-indium-tin (Galinstan®) alloy. At room temperature, the embedded Field’s metal is solid and the composite remains elastically rigid. Joule heating causes the Field’s metal to melt and allows the surrounding elastomer to freely stretch and bend. Using a tensile testing machine, we measure that the effective elastic modulus of the composite reversibly changes by four orders of magnitude when powered on and off. This dramatic change in rigidity is accurately predicted with a model for an elastic composite. Reversible rigidity control is also accomplished by replacing the Field’s metal with shape memory polymer. In addition to demonstrating electrically tunable rigidity with an elastomer, we also introduce a new technique to rapidly produce soft-matter electronics and multifunctional materials in several minutes with laser-patterned adhesive film and masked deposition of liquid-phase metal alloy.

Rigid body motion in stereo 3D simulation

International Nuclear Information System (INIS)

Zabunov, Svetoslav

2010-01-01

This paper addresses the difficulties experienced by first-grade students studying rigid body motion at Sofia University. Most quantities describing the rigid body are in relations that the students find hard to visualize and understand. They also lose the notion of cause-result relations between vector quantities, such as the relation between torque and angular momentum. Consequently, the understanding of physical laws and conservation principles in free rigid body motion is hampered. This paper presents the capabilities of a 3D simulation, which aims to clarify these questions to the students, who are taught mechanics in the general physics course. The rigid body motion simulations may be observed at http://ialms.net/sim/, and are intended to complement traditional learning practices, not replace them, as the author shares the opinion that no simulation may fully resemble reality.

A miniature rigid/flex salinity measurement device fabricated using printed circuit processing techniques

International Nuclear Information System (INIS)

Broadbent, H A; Ketterl, T P; Reid, C S

2010-01-01

The design, fabrication and initial performance of a single substrate, miniature, low-cost conductivity, temperature, depth (CTD) sensor board with interconnects are presented. In combination these sensors measure ocean salinity. The miniature CTD device board was designed and fabricated as the main component of a 50 mm × 25 mm × 25 mm animal-attached biologger. The board was fabricated using printed circuit processes and consists of two distinct regions on a continuous single liquid crystal polymer substrate: an 18 mm × 28 mm rigid multi-metal sensor section and a 72 mm long flexible interconnect section. The 95% confidence intervals for the conductivity, temperature and pressure sensors were demonstrated to be ±0.083 mS cm −1 , 0.01 °C, and ±0.135 dbar, respectively.

Rigid Origami via Optical Programming and Deferred Self-Folding of a Two-Stage Photopolymer.

Science.gov (United States)

Glugla, David J; Alim, Marvin D; Byars, Keaton D; Nair, Devatha P; Bowman, Christopher N; Maute, Kurt K; McLeod, Robert R

2016-11-02

We demonstrate the formation of shape-programmed, glassy origami structures using a single-layer photopolymer with two mechanically distinct phases. The latent origami pattern consisting of rigid, high cross-link density panels and flexible, low cross-link density creases is fabricated using a series of photomask exposures. Strong optical absorption of the polymer formulation creates depth-wise gradients in the cross-link density of the creases, enforcing directed folding which enables programming of both mountain and valley folds within the same sheet. These multiple photomask patterns can be sequentially applied because the sheet remains flat until immersed into a photopolymerizable monomer solution that differentially swells the polymer to fold and form the origami structure. After folding, a uniform photoexposure polymerizes the absorbed solution, permanently fixing the shape of the folded structure while simultaneously increasing the modulus of the folds. This approach creates sharp folds by mimicking the stiff panels and flexible creases of paper origami while overcoming the traditional trade-off of self-actuated materials that require low modulus for folding and high modulus for mechanical robustness. Using this process, we demonstrate a waterbomb base capable of supporting 1500 times its own weight.

Sensing of substratum rigidity and directional migration by fast-crawling cells

Science.gov (United States)

Okimura, Chika; Sakumura, Yuichi; Shimabukuro, Katsuya; Iwadate, Yoshiaki

2018-05-01

Living cells sense the mechanical properties of their surrounding environment and respond accordingly. Crawling cells detect the rigidity of their substratum and migrate in certain directions. They can be classified into two categories: slow-moving and fast-moving cell types. Slow-moving cell types, such as fibroblasts, smooth muscle cells, mesenchymal stem cells, etc., move toward rigid areas on the substratum in response to a rigidity gradient. However, there is not much information on rigidity sensing in fast-moving cell types whose size is ˜10 μ m and migration velocity is ˜10 μ m /min . In this study, we used both isotropic substrata with different rigidities and an anisotropic substratum that is rigid on the x axis but soft on the y axis to demonstrate rigidity sensing by fast-moving Dictyostelium cells and neutrophil-like differentiated HL-60 cells. Dictyostelium cells exerted larger traction forces on a more rigid isotropic substratum. Dictyostelium cells and HL-60 cells migrated in the "soft" direction on the anisotropic substratum, although myosin II-null Dictyostelium cells migrated in random directions, indicating that rigidity sensing of fast-moving cell types differs from that of slow types and is induced by a myosin II-related process.

Analysis of Flexible Car Body of Straddle Monorail Vehicle

Science.gov (United States)

Zhong, Yuanmu

2018-03-01

Based on the finite element model of straddle monorail vehicle, a rigid-flexible coupling dynamic model considering vehicle body’s flexibility is established. The influence of vertical stiffness and vertical damping of the running wheel on the modal parameters of the car body is analyzed. The effect of flexible car body on modal parameters and vehicle ride quality is also studied. The results show that when the vertical stiffness of running wheel is less than 1 MN / m, the car body bounce and pitch frequency increase with the increasing of the vertical stiffness of the running wheel, when the running wheel vertical stiffness is 1MN / m or more, car body bounce and pitch frequency remained unchanged; When the vertical stiffness of the running wheel is below 1.8 MN / m, the vehicle body bounce and pitch damping ratio increase with the increasing of the vertical stiffness of the running wheel; When the running wheel vertical stiffness is 1.8MN / m or more, the car body bounce and pitch damping ratio remained unchanged; The running wheel vertical damping on the car body bounce and pitch frequency has no effect; Car body bounce and pitch damping ratio increase with the increasing of the vertical damping of the running wheel. The flexibility of the car body has no effect on the modal parameters of the car, which will improve the vehicle ride quality index.

Flexible surface acoustic wave respiration sensor for monitoring obstructive sleep apnea syndrome

Science.gov (United States)

Jin, Hao; Tao, Xiang; Dong, Shurong; Qin, Yiheng; Yu, Liyang; Luo, Jikui; Deen, M. Jamal

2017-11-01

Obstructive sleep apnea syndrome (OSAS) has received much attention in recent years due to its significant harm to human health and high morbidity rate. A respiration monitoring system is needed to detect OSAS, so that the patient can receive treatment in a timely manner. Wired and wireless OSAS monitoring systems have been developed, but they require a wire connection and batteries to operate, and they are bulky, heavy and not user-friendly. In this paper, we propose the use of a flexible surface acoustic wave (SAW) microsensor to detect and monitor OSAS by measuring the humidity change associated with the respiration of a person. SAW sensors on rigid 128° YX LiNbO3 substrate are also characterized for this application. Results show both types of SAW sensors are suitable for OSAS monitoring with good sensitivity, repeatability and reliability, and the response time and recovery time for the flexible SAW sensors are 1.125 and 0.75 s, respectively. Our work demonstrates the potential for an innovative flexible microsensor for the detection and monitoring of OSAS.

Development of patterned carbon nanotubes on a 3D polymer substrate for the flexible tactile sensor application

International Nuclear Information System (INIS)

Hu, Chih-Fan; Fang, Weileun; Su, Wang-Shen

2011-01-01

This study reports an improved approach to implement a carbon nanotube (CNT)-based flexible tactile sensor, which is integrated with a flexible print circuit (FPC) connector and is capable of detecting normal and shear forces. The merits of the presented tactile sensor by the integration process are as follows: (1) 3D polymer tactile bump structures are naturally formed by the use of an anisotropically etched silicon mold; (2) planar and 3D distributed CNTs are adopted as piezoresistive sensing elements to enable the detection of shear and normal forces; (3) the processes of patterning CNTs and metal routing can be easily batch fabricated on rigid silicon instead of flexible polymer; (4) robust electrical routing is realized using parylene encapsulation to avoid delamination; (5) patterned CNTs, electrical routing and FPC connector are integrated and transferred to a polydimethylsiloxane (PDMS) substrate by a molding process. In application, the CNT-based flexible tactile sensor and its integration with the FPC connector are implemented. Preliminary tests show the feasibility of detecting both normal and shear forces using the presented flexible sensor.

Highly efficient Cu(In,Ga)Se2 solar cells grown on flexible polymer films.

Science.gov (United States)

Chirilă, Adrian; Buecheler, Stephan; Pianezzi, Fabian; Bloesch, Patrick; Gretener, Christina; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Perrenoud, Julian; Seyrling, Sieghard; Verma, Rajneesh; Nishiwaki, Shiro; Romanyuk, Yaroslav E; Bilger, Gerhard; Tiwari, Ayodhya N

2011-09-18

Solar cells based on polycrystalline Cu(In,Ga)Se(2) absorber layers have yielded the highest conversion efficiency among all thin-film technologies, and the use of flexible polymer films as substrates offers several advantages in lowering manufacturing costs. However, given that conversion efficiency is crucial for cost-competitiveness, it is necessary to develop devices on flexible substrates that perform as well as those obtained on rigid substrates. Such comparable performance has not previously been achieved, primarily because polymer films require much lower substrate temperatures during absorber deposition, generally resulting in much lower efficiencies. Here we identify a strong composition gradient in the absorber layer as the main reason for inferior performance and show that, by adjusting it appropriately, very high efficiencies can be obtained. This implies that future manufacturing of highly efficient flexible solar cells could lower the cost of solar electricity and thus become a significant branch of the photovoltaic industry.

Effect of rigid inclusions on sintering

International Nuclear Information System (INIS)

Rahaman, M.N.; De Jonghe, L.C.

1988-01-01

The predictions of recent theoretical studies on the effect of inert, rigid inclusions on the sintering of ceramic powder matrices are examined and compared with experimental data. The densification of glass matrix composites with inclusion volume fractions of ≤0.15 can be adequately explained by Scherer's theory for viscous sintering with rigid inclusions. Inclusions cause a vast reduction in the densification rates of polycrystalline matrix composites even at low inclusion volume fractions. Models put forward to explain the sintering of polycrystalline matrix composites are discussed

Rigid-Plastic Post-Buckling Analysis of Columns and Quadratic Plates

DEFF Research Database (Denmark)

Jönsson, Jeppe

2008-01-01

the compressive load as a function of the transverse displacement. An estimate of the magnitude of the transverse displacement prior to the forming of the collapse mechanism is introduced into the compressive load function, determined by the virtual work equation, thereby revealing a qualified estimate...... yield lines accommodate differential rotations of rigid parts and the area “collapse” yield lines accommodate local area changes of the rigid parts thereby preserving compatibility of the rigid parts of a plate. The approach will be illustrated for rigid plastic column analysis and for a quadratic plate...

About deformation and rigidity in relativity

International Nuclear Information System (INIS)

Coll, Bartolome

2007-01-01

The notion of deformation involves that of rigidity. In relativity, starting from Born's early definition of rigidity, some other ones have been proposed, offering more or less interesting aspects but also accompanied of undesired or even pathological properties. In order to clarify the origin of these difficulties presented by the notion of rigidity in relativity, we analyze with some detail significant aspects of the unambiguous classical, Newtonian, notion. In particular, the relative character of its kinetic definition is pointed out, allowing to predict and to understand the limitations imposed by Herglotz-Noether theorem. Also, its equivalent dynamic definition is obtained and, in contrast, its absolute character is shown. But in spite of this absolute character, the dynamic definition is shown to be not extensible to relativity. The metric deformation of Minkowski space by the presence of a gravitational field is interpreted as a universal deformation, and it is shown that, under natural conditions, only a simple deformation law is possible, relating locally, but in an one-to-one way, gravitational fields and gauge classes of two-forms. We argue that fields of unit vectors associated to the internal gauge class of two-forms of every space-time (and, in particular, of Minkowski space-time) are the relativistic analogues of the classical accelerated observers, i.e. of the classical rigid motions. Some other consequences of the universal law of gravitational deformation are commented

Dual Quaternion Variational Integrator for Rigid Body Dynamic Simulation

OpenAIRE

Xu, Jiafeng; Halse, Karl Henning

2016-01-01

In rigid body dynamic simulations, often the algorithm is required to deal with general situations where both reference point and inertia matrix are arbitrarily de- fined. We introduce a novel Lie group variational integrator using dual quaternion for simulating rigid body dynamics in all six degrees of freedom. Dual quaternion is used to represent rigid body kinematics and one-step Lie group method is used to derive dynamic equations. The combination of these two becomes the first Lie group ...

The Almost Periodic Rigidity of Crystallographic Bar-Joint Frameworks

Directory of Open Access Journals (Sweden)

Ghada Badri

2014-04-01

Full Text Available A crystallographic bar-joint framework, C in Rd, is shown to be almost periodically infinitesimally rigid if and only if it is strictly periodically infinitesimally rigid and the rigid unit mode (RUM spectrum, Ω (C, is a singleton. Moreover, the almost periodic infinitesimal flexes of C are characterised in terms of a matrix-valued function, ΦC(z, on the d-torus, Td, determined by a full rank translation symmetry group and an associated motif of joints and bars.

Wobbling motion: A γ-rigid or γ-soft mode?

International Nuclear Information System (INIS)

Casten, R.F.; McCutchan, E.A.; Beausang, C.W.; Zamfir, N.V.; Zhang Jingye

2003-01-01

For even-even nuclei, it is shown that the predicted B(E2) values from the odd spin states of the quasi-γ band in a γ-soft nucleus to the yrast band are quite similar to those predicted for the one-phonon wobbling mode of a rigidly triaxial nucleus. This suggests that the observation of wobbling points to axial asymmetry, but not necessarily to rigid triaxiality. However, another observable that does distinguish γ-soft from γ-rigid structure is identified

Low-Temperature Presynthesized Crystalline Tin Oxide for Efficient Flexible Perovskite Solar Cells and Modules.

Science.gov (United States)

Bu, Tongle; Shi, Shengwei; Li, Jing; Liu, Yifan; Shi, Jielin; Chen, Li; Liu, Xueping; Qiu, Junhao; Ku, Zhiliang; Peng, Yong; Zhong, Jie; Cheng, Yi-Bing; Huang, Fuzhi

2018-05-02

Organic-inorganic metal halide perovskite solar cells (PSCs) have been emerging as one of the most promising next generation photovoltaic technologies with a breakthrough power conversion efficiency (PCE) over 22%. However, aiming for commercialization, it still encounters challenges for the large-scale module fabrication, especially for flexible devices which have attracted intensive attention recently. Low-temperature processed high-performance electron-transporting layers (ETLs) are still difficult. Herein, we present a facile low-temperature synthesis of crystalline SnO 2 nanocrystals (NCs) as efficient ETLs for flexible PSCs including modules. Through thermal and UV-ozone treatments of the SnO 2 ETLs, the electron transporting resistance of the ETLs and the charge recombination at the interface of ETL/perovskite were decreased. Thus, the hysteresis-free highly efficient rigid and flexible PSCs were obtained with PCEs of 19.20 and 16.47%, respectively. Finally, a 5 × 5 cm 2 flexible PSC module with a PCE of 12.31% (12.22% for forward scan and 12.40% for reverse scan) was fabricated with the optimized perovskite/ETL interface. Thus, employing presynthesized SnO 2 NCs to fabricate ETLs has showed promising for future manufacturing.

Analysis of flexible-membrane aerofoils by a method of velocity singularities

International Nuclear Information System (INIS)

Mateescu, D.; Newman, B.G.

1985-01-01

Two dimensional sails were originally treated as flexible, impervious, inextensible membranes. These methods are developed in the context of thin aerofoil theory, the membrane being replaced by a vortex sheet and the boundary conditions satisfied at the corresponding positions on the aerofoil chord. The present present methos is developed as a linear potential theory, although it may be further extended to include non-linear and viscous effects. The new analysis is based on the method of velocity singularities associated with the changes in aerofoil slope developed for rigid aerofoils; it eliminates the need of formally solving an integral equation

Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

Science.gov (United States)

Ghoneim, M. T.; Hussain, M. M.

2015-08-01

Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ˜260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures.

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring.

Science.gov (United States)

Servati, Amir; Zou, Liang; Wang, Z Jane; Ko, Frank; Servati, Peyman

2017-07-13

Advances in flexible electronic materials and smart textile, along with broad availability of smart phones, cloud and wireless systems have empowered the wearable technologies for significant impact on future of digital and personalized healthcare as well as consumer electronics. However, challenges related to lack of accuracy, reliability, high power consumption, rigid or bulky form factor and difficulty in interpretation of data have limited their wide-scale application in these potential areas. As an important solution to these challenges, we present latest advances in novel flexible electronic materials and sensors that enable comfortable and conformable body interaction and potential for invisible integration within daily apparel. Advances in novel flexible materials and sensors are described for wearable monitoring of human vital signs including, body temperature, respiratory rate and heart rate, muscle movements and activity. We then present advances in signal processing focusing on motion and noise artifact removal, data mining and aspects of sensor fusion relevant to future clinical applications of wearable technology.

Rigid Spine Syndrome among Children in Oman

Directory of Open Access Journals (Sweden)

Roshan Koul

2015-08-01

Full Text Available Objectives: Rigidity of the spine is common in adults but is rarely observed in children. The aim of this study was to report on rigid spine syndrome (RSS among children in Oman. Methods: Data on children diagnosed with RSS were collected consecutively at presentation between 1996 and 2014 at the Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A diagnosis of RSS was based on the patient’s history, clinical examination, biochemical investigations, electrophysiological findings, neuro-imaging and muscle biopsy. Atrophy of the paraspinal muscles, particularly the erector spinae, was the diagnostic feature; this was noted using magnetic resonance imaging of the spine. Children with disease onset in the paraspinal muscles were labelled as having primary RSS or rigid spinal muscular dystrophy. Secondary RSS was classified as RSS due to the late involvement of other muscle diseases. Results: Over the 18-year period, 12 children were included in the study, with a maleto- female ratio of 9:3. A total of 10 children were found to have primary RSS or rigid spinal muscular dystrophy syndrome while two had secondary RSS. Onset of the disease ranged from birth to 18 months of age. A family history was noted, with two siblings from one family and three siblings from another (n = 5. On examination, children with primary RSS had typical features of severe spine rigidity at onset, with the rest of the neurological examination being normal. Conclusion: RSS is a rare disease with only 12 reported cases found at SQUH during the study period. Cases of primary RSS should be differentiated from the secondary type.

A Contextual Behavior Science Framework for Understanding How Behavioral Flexibility Relates to Anxiety.

Science.gov (United States)

Palm Reed, Kathleen M; Cameron, Amy Y; Ameral, Victoria E

2017-09-01

There is a growing literature focusing on the emerging idea that behavioral flexibility, rather than particular emotion regulation strategies per se, provides greater promise in predicting and influencing anxiety-related psychopathology. Yet this line of research and theoretical analysis appear to be plagued by its own challenges. For example, middle-level constructs, such as behavioral flexibility, are difficult to define, difficult to measure, and difficult to interpret in relation to clinical interventions. A key point that some researchers have made is that previous studies examining flexible use of emotion regulation strategies (or, more broadly, coping) have failed due to a lack of focus on context. That is, examining strategies in isolation of the context in which they are used provides limited information on the suitability, rigid adherence, or effectiveness of a given strategy in that situation. Several of these researchers have proposed the development of new models to define and measure various types of behavioral flexibility. We would like to suggest that an explanation of the phenomenon already exists and that we can go back to our behavioral roots to understand this phenomenon rather than focusing on defining and capturing a new process. Indeed, thorough contextual behavioral analyses already yield a useful account of what has been observed. We will articulate a model explaining behavioral flexibility using a functional, contextual framework, with anxiety-related disorders as an example.

Quantum mechanics of a generalised rigid body

International Nuclear Information System (INIS)

Gripaios, Ben; Sutherland, Dave

2016-01-01

We consider the quantum version of Arnold’s generalisation of a rigid body in classical mechanics. Thus, we quantise the motion on an arbitrary Lie group manifold of a particle whose classical trajectories correspond to the geodesics of any one-sided-invariant metric. We show how the derivation of the spectrum of energy eigenstates can be simplified by making use of automorphisms of the Lie algebra and (for groups of type I) by methods of harmonic analysis. We show how the method can be extended to cosets, generalising the linear rigid rotor. As examples, we consider all connected and simply connected Lie groups up to dimension 3. This includes the universal cover of the archetypical rigid body, along with a number of new exactly solvable models. We also discuss a possible application to the topical problem of quantising a perfect fluid. (paper)

Nonlinear model and attitude dynamics of flexible spacecraft with large amplitude slosh

Science.gov (United States)

Deng, Mingle; Yue, Baozeng

2017-04-01

This paper is focused on the nonlinearly modelling and attitude dynamics of spacecraft coupled with large amplitude liquid sloshing dynamics and flexible appendage vibration. The large amplitude fuel slosh dynamics is included by using an improved moving pulsating ball model. The moving pulsating ball model is an equivalent mechanical model that is capable of imitating the whole liquid reorientation process. A modification is introduced in the capillary force computation in order to more precisely estimate the settling location of liquid in microgravity or zero-g environment. The flexible appendage is modelled as a three dimensional Bernoulli-Euler beam and the assumed modal method is employed to derive the nonlinear mechanical model for the overall coupled system of liquid filled spacecraft with appendage. The attitude maneuver is implemented by the momentum transfer technique, and a feedback controller is designed. The simulation results show that the liquid sloshing can always result in nutation behavior, but the effect of flexible deformation of appendage depends on the amplitude and direction of attitude maneuver performed by spacecraft. Moreover, it is found that the liquid sloshing and the vibration of flexible appendage are coupled with each other, and the coupling becomes more significant with more rapid motion of spacecraft. This study reveals that the appendage's flexibility has influence on the liquid's location and settling time in microgravity. The presented nonlinear system model can provide an important reference for the overall design of the modern spacecraft composed of rigid platform, liquid filled tank and flexible appendage.

Use of flexible engineered cementitious composite in buildings

International Nuclear Information System (INIS)

Khitab, A.; Nadeem, M.; Hussain, S.

2011-01-01

This article describes the applications and benefits of a recently developed smart building material namely Engineered cementitious composite (ECC), also known as flexible or bendable concrete. Conventional concretes have a strain capacity of only 0.1 percent and are highly brittle and rigid. This lack of bend ability is a major cause of failure under strain and has been a pushing factor in the development of an elegant material which is capable to exhibit an enhanced flexibility. An ECC has a strain capacity of more than 3 percent and thus acts more like a ductile metal rather than like a brittle glass. The aim of this paper is to highlight a probable success of ECC in terms of industrial and commercial use in Pakistan. With the introduction of flexible concrete in building technology, it is likely to have safer and more durable construction. The material is expected to display reduced detrimental impacts on the natural environment. A bendable concrete is composed of all the ingredients of a traditional concrete minus coarse aggregates or crushed stones and is reinforced with micro mechanically designed polymer fibers. The mechanism of action of the micro-polymeric fibers in concrete has also been emphasized. The principles of mix designs of the mortar incorporating fibers to make an ECC have also been explained. It has also been mentioned in detail as how this technology can be used to enhance the flexibility of some modern concrete types like flowing concrete, self-compacting concrete, and lightweight concrete. ECC is a green construction material. The possible benefits like environment friendliness, cost effectiveness, and durability have been also been elucidated in the paper. (author)

Dynamic Analysis of Planar 3-RRR Flexible Parallel Robots with Dynamic Stiffening

Directory of Open Access Journals (Sweden)

Qinghua Zhang

2014-01-01

Full Text Available In consideration of the second-order coupling quantity of the axial displacement caused by the transverse displacement of flexible beam, the first-order approximation coupling model of planar 3-RRR flexible parallel robots is presented, in which the rigid body motion constraints, elastic deformation motion constraints, and dynamic constraints of the moving platform are considered. Based on the different speed of the moving platform, numerical simulation results using the conventional zero-order approximation coupling model and the proposed firstorder approximation coupling model show that the effect of “dynamic stiffening” term on dynamic characteristics of the system is insignificant and can be neglected, and the zero-order approximation coupling model is enough precisely for catching essentially dynamic characteristics of the system. Then, the commercial software ANSYS 13.0 is used to confirm the validity of the zero-order approximation coupling model.

Customizable rigid head fixation for infants: technical note.

Science.gov (United States)

Udayakumaran, Suhas; Onyia, Chiazor U

2016-01-01

The need and advantages of rigid fixation of the head in cranial surgeries are well documented (Berryhill et al., Otolaryngol Head Neck Surg 121:269-273, 1999). Head fixation for neurosurgical procedures in infants and in early years has been a challenge and is fraught with risk. Despite the fact that pediatric pins are designed, rigid head fixation involving direct application of pins to the head of infants and slightly older children is still generally not safe (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). Yet, there are some surgeries in which some form of rigid fixation is required (Agrawal and Steinbok, Childs Nerv Syst 22:1473-1474, 2006). We describe a simple technique to achieve rigid fixation of the head in infants for neurosurgical procedures. This involves applying a head band made of Plaster of Paris (POP) around the head and then applying the fixation pins of the fixation frame directly on to the POP. We have used this technique of head fixation successfully for infants with no complications.

"Mind the trap": mindfulness practice reduces cognitive rigidity.

Directory of Open Access Journals (Sweden)

Jonathan Greenberg

Full Text Available Two experiments examined the relation between mindfulness practice and cognitive rigidity by using a variation of the Einstellung water jar task. Participants were required to use three hypothetical jars to obtain a specific amount of water. Initial problems were solvable by the same complex formula, but in later problems ("critical" or "trap" problems solving was possible by an additional much simpler formula. A rigidity score was compiled through perseverance of the complex formula. In Experiment 1, experienced mindfulness meditators received significantly lower rigidity scores than non-meditators who had registered for their first meditation retreat. Similar results were obtained in randomized controlled Experiment 2 comparing non-meditators who underwent an eight meeting mindfulness program with a waiting list group. The authors conclude that mindfulness meditation reduces cognitive rigidity via the tendency to be "blinded" by experience. Results are discussed in light of the benefits of mindfulness practice regarding a reduced tendency to overlook novel and adaptive ways of responding due to past experience, both in and out of the clinical setting.

Flexible Cu(In,Ga)Se2 thin-film solar cells for space application

International Nuclear Information System (INIS)

Otte, Karsten; Makhova, Liudmila; Braun, Alexander; Konovalov, Igor

2006-01-01

Thin film solar cells (TFSC) with Cu(In,Ga)Se 2 (CIGS) as absorber layer have been produced on rigid glass substrates for the terrestrial market. There exist, however, different investigations for manufacturing of TFSC on flexible substrates in order to achieve very thin and highly flexible (rollable) solar cells. Besides their capability to open new terrestrial market segments, they are considered as competitive candidates for future flexible thin film space power generators compared to traditional crystalline solar cells. This paper explains the advantages of flexible TFSC for usage in space, including:-low mass and storage volume, -high power/mass ratio [>100 W/kg at array level], -high radiation resistance against proton and electron radiation and, -lower production costs. These cells can be produced on flexible conductive and insulating substrate materials and have efficiency potentials of up to 15%. We report on the current development steps to adopt the TFSC technology to space requirements as well as the first European industrial approach to the roll-to-roll production of flexible CIGS-TFSC on polyimide as substrate material. Stability issues in space environment concern not only the TFSC itself, but all system components such as interconnects, cell assembly and flexible blankets. The adhesion of the back-contact to the substrate, the emissivity control in the infrared wavelength range, the electrical contacting and interconnection as well as flexible encapsulation are currently under investigation and are discussed in the paper. The production costs for TFSC for space application can be further reduced by sharing resources for the production of flexible TFSC for the terrestrial market; namely by using both, the existing terrestrial investment in production facilities as well as the synergies in R and D

Rigidity of outermost MOTS: the initial data version

Science.gov (United States)

Galloway, Gregory J.

2018-03-01

In the paper Commun Anal Geom 16(1):217-229, 2008, a rigidity result was obtained for outermost marginally outer trapped surfaces (MOTSs) that do not admit metrics of positive scalar curvature. This allowed one to treat the "borderline case" in the author's work with R. Schoen concerning the topology of higher dimensional black holes (Commun Math Phys 266(2):571-576, 2006). The proof of this rigidity result involved bending the initial data manifold in the vicinity of the MOTS within the ambient spacetime. In this note we show how to circumvent this step, and thereby obtain a pure initial data version of this rigidity result and its consequence concerning the topology of black holes.

APPLICATION OF RIGID LINKS IN STRUCTURAL DESIGN MODELS

Directory of Open Access Journals (Sweden)

Sergey Yu. Fialko

2017-09-01

Full Text Available A special finite element modelling rigid links is proposed for the linear static and buckling analysis. Unlike the classical approach based on the theorems of rigid body kinematics, the proposed approach preserves the similarity between the adjacency graph for a sparse matrix and the adjacency graph for nodes of the finite element model, which allows applying sparse direct solvers more effectively. Besides, the proposed approach allows significantly reducing the number of nonzero entries in the factored stiffness matrix in comparison with the classical one, which greatly reduces the duration of the solution. For buckling problems of structures containing rigid bodies, this approach gives correct results. Several examples demonstrate its efficiency.

High frequency permeameter with semi-rigid pick-up coil

International Nuclear Information System (INIS)

Shin, Sung-Yong; Shin, Kwang-Ho . E-mail : khshin@star.ks.ac.kr; Kim, Jong-sung; Kim, Young-Hak; Lim, Sang-Ho; Sa-gong, Geon

2006-01-01

In this study, we propose the application of semi-rigid cable loop as a single turn shielded loop pick-up coil for the high frequency permeameter. Since the semi-rigid cable pick-up coil has simple structure, it is very easy to make the pick-up coil with bending and conventional soldering. The permeability of cobalt base amorphous ribbon was investigated using the developed permeameter for demonstrating its performance. The permeability of the amorphous ribbon was driven from the S-parameters measured using a network analyzer and permameter having the semi-rigid pick-up coil

Flexibility of Supply Chain in Industrialised Building System (IBS

Directory of Open Access Journals (Sweden)

Kassim U.

2014-01-01

Full Text Available It is irrefutable that the construction industry is in need of a highly technological construction method or system for the simple aim of giving it a push it deserves. In Malaysia this technologically enhanced method is known as the Indutrialised Building System (IBS. Concerted efforts have been made for the past decade by various responsible parties especially by the government. Therefore, the IBS ‘Road Map’ 2003–2010 was introduced and now continues with the IBS ‘road map’ 2011-2015. However, its performance is still at its infancy, which target is only at an initial stage. This study seeks to identify and analyse the factor of the IBS’ system’s supply chain flexibility as a factor on the success of the system itself. It has been a suspicion that there exists a condition and situation where the supply chain is too rigid and is not flexible in fulfilling the needs and demands of the IBS development in Malaysia. This inflexible situation has brought about a broad range of problems and has stood in the way of the development of the industrialised building system, despite it being introduced since 1964, or 49 years ago. Flexibility in the IBS supply chain is very important and is associated with other industries like transportation, manufacturing industry, and others. Up until now, we have yet to discover any special studies related to the flexibility in the IBS supply chain in this country. Responding to this challenge, this research is hoped to be able to provide sufficient feedback to the solution to the IBS supply chain flexibility issue. The researcher is confident that the poor system flow of supply chain has impeded the advancement of the Industrialised Building System that has long been open to debate.

Utility of semi-rigid thoracoscopy in undiagnosed exudative pleural effusion.

Science.gov (United States)

Nattusamy, Loganathan; Madan, Karan; Mohan, Anant; Hadda, Vijay; Jain, Deepali; Madan, Neha Kawatra; Arava, Sudheer; Khilnani, Gopi C; Guleria, Randeep

2015-01-01

Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed pleural effusion. Literature on its utility from developing countries is limited. We herein describe our initial experience on the utility of semi-rigid thoracoscopy from a tertiary care teaching and referral center in north India. We also perform a systematic review of studies reporting the utility of semi-rigid thoracoscopy from India. The primary objective was to evaluate the diagnostic utility of semi-rigid thoracoscopy in patients with undiagnosed exudative pleural effusion. Semi-rigid thoracoscopy was performed under local anesthesia and conscious sedation in the bronchoscopy suite. A total of 48 patients underwent semi-rigid thoracoscopy between August 2012 and December 2013 for undiagnosed pleural effusion. Mean age was 50.9 ± 14.1 years (range: 17-78 years). Pre-procedure clinico-radiological diagnoses were malignant pleural effusion [36 patients (75%)], tuberculosis (TB) [10 (20.83%) patients], and empyema [2 patients (4.17%)]. Patients with empyema underwent the procedure for pleural biopsy, optimal placement of intercostal tube and adhesiolysis. Thoracoscopic pleural biopsy diagnosed pleural malignancy in 30 (62.5%) patients and TB in 2 (4.17%) patients. Fourteen (29.17%) patients were diagnosed with non-specific pleuritis and normal pleura was diagnosed on a pleural biopsy in 2 (4.17%) patients. Overall, a definitive diagnosis of either pleural malignancy or TB was obtained in 32 (66.7%) patients. Combined overall sensitivity, specificity, positive predictive value and negative predictive value of thoracoscopic pleural biopsy for malignant pleural effusion were 96.77%, 100%, 100% and 66.67%, respectively. There was no procedure-related mortality. On performing a systematic review of literature, four studies on semi-rigid thoracoscopy from India were identified. Semi-rigid thoracoscopy is a safe and efficacious procedure in patients with undiagnosed exudative

AUTOMATED LOW-COST PHOTOGRAMMETRY FOR FLEXIBLE STRUCTURE MONITORING

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C. H. Wang

2012-07-01

Full Text Available Structural monitoring requires instruments which can provide high precision and accuracy, reliable measurements at good temporal resolution and rapid processing speeds. Long-term campaigns and flexible structures are regarded as two of the most challenging subjects in monitoring engineering structures. Long-term monitoring in civil engineering is generally considered to be labourintensive and financially expensive and it can take significant effort to arrange the necessary human resources, transportation and equipment maintenance. When dealing with flexible structure monitoring, it is of paramount importance that any monitoring equipment used is able to carry out rapid sampling. Low cost, automated, photogrammetric techniques therefore have the potential to become routinely viable for monitoring non-rigid structures. This research aims to provide a photogrammetric solution for long-term flexible structural monitoring purposes. The automated approach was achieved using low-cost imaging devices (mobile phones to replace traditional image acquisition stations and substantially reduce the equipment costs. A self-programmed software package was developed to deal with the hardware-software integration and system operation. In order to evaluate the performance of this low-cost monitoring system, a shaking table experiment was undertaken. Different network configurations and target sizes were used to determine the best configuration. A large quantity of image data was captured by four DSLR cameras and four mobile phone cameras respectively. These image data were processed using photogrammetric techniques to calculate the final results for the system evaluation.

Handover management in dense cellular networks: A stochastic geometry approach

KAUST Repository

Arshad, Rabe; Elsawy, Hesham; Sorour, Sameh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2016-01-01

Cellular operators are continuously densifying their networks to cope with the ever-increasing capacity demand. Furthermore, an extreme densification phase for cellular networks is foreseen to fulfill the ambitious fifth generation (5G) performance requirements. Network densification improves spectrum utilization and network capacity by shrinking base stations' (BSs) footprints and reusing the same spectrum more frequently over the spatial domain. However, network densification also increases the handover (HO) rate, which may diminish the capacity gains for mobile users due to HO delays. In highly dense 5G cellular networks, HO delays may neutralize or even negate the gains offered by network densification. In this paper, we present an analytical paradigm, based on stochastic geometry, to quantify the effect of HO delay on the average user rate in cellular networks. To this end, we propose a flexible handover scheme to reduce HO delay in case of highly dense cellular networks. This scheme allows skipping the HO procedure with some BSs along users' trajectories. The performance evaluation and testing of this scheme for only single HO skipping shows considerable gains in many practical scenarios. © 2016 IEEE.

Handover management in dense cellular networks: A stochastic geometry approach

KAUST Repository

Arshad, Rabe

2016-07-26

Cellular operators are continuously densifying their networks to cope with the ever-increasing capacity demand. Furthermore, an extreme densification phase for cellular networks is foreseen to fulfill the ambitious fifth generation (5G) performance requirements. Network densification improves spectrum utilization and network capacity by shrinking base stations\\' (BSs) footprints and reusing the same spectrum more frequently over the spatial domain. However, network densification also increases the handover (HO) rate, which may diminish the capacity gains for mobile users due to HO delays. In highly dense 5G cellular networks, HO delays may neutralize or even negate the gains offered by network densification. In this paper, we present an analytical paradigm, based on stochastic geometry, to quantify the effect of HO delay on the average user rate in cellular networks. To this end, we propose a flexible handover scheme to reduce HO delay in case of highly dense cellular networks. This scheme allows skipping the HO procedure with some BSs along users\\' trajectories. The performance evaluation and testing of this scheme for only single HO skipping shows considerable gains in many practical scenarios. © 2016 IEEE.

Algebraic Methods for Counting Euclidean Embeddings of Rigid Graphs

NARCIS (Netherlands)

I.Z. Emiris; E.P. Tsigaridas; A. Varvitsiotis (Antonios); E.R. Gasner

2009-01-01

textabstract The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture embeddability by polynomial systems

Rigid body dynamics of mechanisms

CERN Document Server

Hahn, Hubert

2003-01-01

The second volume of Rigid Body Dynamics of Mechanisms covers applications via a systematic method for deriving model equations of planar and spatial mechanisms. The necessary theoretical foundations have been laid in the first volume that introduces the theoretical mechanical aspects of mechatronic systems. Here the focus is on the application of the modeling methodology to various examples of rigid-body mechanisms, simple planar ones as well as more challenging spatial problems. A rich variety of joint models, active constraints, plus active and passive force elements is treated. The book is intended for self-study by working engineers and students concerned with the control of mechanical systems, i.e. robotics, mechatronics, vehicles, and machine tools. The examples included are a likely source from which to choose models for university lectures.

CAB-Align: A Flexible Protein Structure Alignment Method Based on the Residue-Residue Contact Area.

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Genki Terashi

Full Text Available Proteins are flexible, and this flexibility has an essential functional role. Flexibility can be observed in loop regions, rearrangements between secondary structure elements, and conformational changes between entire domains. However, most protein structure alignment methods treat protein structures as rigid bodies. Thus, these methods fail to identify the equivalences of residue pairs in regions with flexibility. In this study, we considered that the evolutionary relationship between proteins corresponds directly to the residue-residue physical contacts rather than the three-dimensional (3D coordinates of proteins. Thus, we developed a new protein structure alignment method, contact area-based alignment (CAB-align, which uses the residue-residue contact area to identify regions of similarity. The main purpose of CAB-align is to identify homologous relationships at the residue level between related protein structures. The CAB-align procedure comprises two main steps: First, a rigid-body alignment method based on local and global 3D structure superposition is employed to generate a sufficient number of initial alignments. Then, iterative dynamic programming is executed to find the optimal alignment. We evaluated the performance and advantages of CAB-align based on four main points: (1 agreement with the gold standard alignment, (2 alignment quality based on an evolutionary relationship without 3D coordinate superposition, (3 consistency of the multiple alignments, and (4 classification agreement with the gold standard classification. Comparisons of CAB-align with other state-of-the-art protein structure alignment methods (TM-align, FATCAT, and DaliLite using our benchmark dataset showed that CAB-align performed robustly in obtaining high-quality alignments and generating consistent multiple alignments with high coverage and accuracy rates, and it performed extremely well when discriminating between homologous and nonhomologous pairs of proteins

CAB-Align: A Flexible Protein Structure Alignment Method Based on the Residue-Residue Contact Area.

Science.gov (United States)

Terashi, Genki; Takeda-Shitaka, Mayuko

2015-01-01

Proteins are flexible, and this flexibility has an essential functional role. Flexibility can be observed in loop regions, rearrangements between secondary structure elements, and conformational changes between entire domains. However, most protein structure alignment methods treat protein structures as rigid bodies. Thus, these methods fail to identify the equivalences of residue pairs in regions with flexibility. In this study, we considered that the evolutionary relationship between proteins corresponds directly to the residue-residue physical contacts rather than the three-dimensional (3D) coordinates of proteins. Thus, we developed a new protein structure alignment method, contact area-based alignment (CAB-align), which uses the residue-residue contact area to identify regions of similarity. The main purpose of CAB-align is to identify homologous relationships at the residue level between related protein structures. The CAB-align procedure comprises two main steps: First, a rigid-body alignment method based on local and global 3D structure superposition is employed to generate a sufficient number of initial alignments. Then, iterative dynamic programming is executed to find the optimal alignment. We evaluated the performance and advantages of CAB-align based on four main points: (1) agreement with the gold standard alignment, (2) alignment quality based on an evolutionary relationship without 3D coordinate superposition, (3) consistency of the multiple alignments, and (4) classification agreement with the gold standard classification. Comparisons of CAB-align with other state-of-the-art protein structure alignment methods (TM-align, FATCAT, and DaliLite) using our benchmark dataset showed that CAB-align performed robustly in obtaining high-quality alignments and generating consistent multiple alignments with high coverage and accuracy rates, and it performed extremely well when discriminating between homologous and nonhomologous pairs of proteins in both

Correlation between membrane fluidity cellular development and stem cell differentiation

KAUST Repository

Noutsi, Pakiza

2016-12-01

Cell membranes are made up of a complex structure of lipids and proteins that diffuse laterally giving rise to what we call membrane fluidity. During cellular development, such as neuronal differentiation, cell membranes undergo dramatic structural changes induced by proteins such as ARC and Cofilin among others in the case of synaptic modification. In this study we used the generalized polarization (GP) property of fluorescent probe Laurdan using two-photon microscopy to determine membrane fluidity as a function of time and for various cell lines. A low GP value corresponds to a higher fluidity and a higher GP value is associated with a more rigid membrane. Four different cell lines were monitored such as hN2, NIH3T3, HEK293 and L6 cells. As expected, NIH3T3 cells have more rigid membrane at earlier stages of their development. On the other hand neurons tend to have the highest membrane fluidity early in their development emphasizing its correlation with plasticity and the need for this malleability during differentiation. This study sheds light on the involvement of membrane fluidity during neuronal differentiation and development of other cell lines.

Tapping Into Rate Flexibility: Musical Training Facilitates Synchronization Around Spontaneous Production Rates

Science.gov (United States)

Scheurich, Rebecca; Zamm, Anna; Palmer, Caroline

2018-01-01

The ability to flexibly adapt one’s behavior is critical for social tasks such as speech and music performance, in which individuals must coordinate the timing of their actions with others. Natural movement frequencies, also called spontaneous rates, constrain synchronization accuracy between partners during duet music performance, whereas musical training enhances synchronization accuracy. We investigated the combined influences of these factors on the flexibility with which individuals can synchronize their actions with sequences at different rates. First, we developed a novel musical task capable of measuring spontaneous rates in both musicians and non-musicians in which participants tapped the rhythm of a familiar melody while hearing the corresponding melody tones. The novel task was validated by similar measures of spontaneous rates generated by piano performance and by the tapping task from the same pianists. We then implemented the novel task with musicians and non-musicians as they synchronized tapping of a familiar melody with a metronome at their spontaneous rates, and at rates proportionally slower and faster than their spontaneous rates. Musicians synchronized more flexibly across rates than non-musicians, indicated by greater synchronization accuracy. Additionally, musicians showed greater engagement of error correction mechanisms than non-musicians. Finally, differences in flexibility were characterized by more recurrent (repetitive) and patterned synchronization in non-musicians, indicative of greater temporal rigidity. PMID:29681872

Tapping Into Rate Flexibility: Musical Training Facilitates Synchronization Around Spontaneous Production Rates

Directory of Open Access Journals (Sweden)

Rebecca Scheurich

2018-04-01

Full Text Available The ability to flexibly adapt one’s behavior is critical for social tasks such as speech and music performance, in which individuals must coordinate the timing of their actions with others. Natural movement frequencies, also called spontaneous rates, constrain synchronization accuracy between partners during duet music performance, whereas musical training enhances synchronization accuracy. We investigated the combined influences of these factors on the flexibility with which individuals can synchronize their actions with sequences at different rates. First, we developed a novel musical task capable of measuring spontaneous rates in both musicians and non-musicians in which participants tapped the rhythm of a familiar melody while hearing the corresponding melody tones. The novel task was validated by similar measures of spontaneous rates generated by piano performance and by the tapping task from the same pianists. We then implemented the novel task with musicians and non-musicians as they synchronized tapping of a familiar melody with a metronome at their spontaneous rates, and at rates proportionally slower and faster than their spontaneous rates. Musicians synchronized more flexibly across rates than non-musicians, indicated by greater synchronization accuracy. Additionally, musicians showed greater engagement of error correction mechanisms than non-musicians. Finally, differences in flexibility were characterized by more recurrent (repetitive and patterned synchronization in non-musicians, indicative of greater temporal rigidity.

Production, properties, and applications of hydrocolloid cellular solids.

Science.gov (United States)

Nussinovitch, Amos

2005-02-01

Many common synthetic and edible materials are, in fact, cellular solids. When classifying the structure of cellular solids, a few variables, such as open vs. closed cells, flexible vs. brittle cell walls, cell-size distribution, cell-wall thickness, cell shape, the uniformity of the structure of the cellular solid and the different scales of length are taken into account. Compressive stress-strain relationships of most cellular solids can be easily identified according to their characteristic sigmoid shape, reflecting three deformation mechanisms: (i) elastic distortion under small strains, (ii) collapse and/or fracture of the cell walls, and (iii) densification. Various techniques are used to produce hydrocolloid (gum) cellular solids. The products of these include (i) sponges, obtained when the drying gel contains the occasionally produced gas bubbles; (ii) sponges produced by the immobilization of microorganisms; (iii) solid foams produced by drying foamed solutions or gels containing oils, and (iv) hydrocolloid sponges produced by enzymatic reactions. The porosity of the manufactured cellular solid is subject to change and depends on its composition and the processing technique. The porosity is controlled by a range of methods and the resulting surface structures can be investigated by microscopy and analyzed using fractal methods. Models used to describe stress-strain behaviors of hydrocolloid cellular solids as well as multilayered products and composites are discussed in detail in this manuscript. Hydrocolloid cellular solids have numerous purposes, simple and complex, ranging from dried texturized fruits to carriers of vitamins and other essential micronutrients. They can also be used to control the acoustic response of specific dry food products, and have a great potential for future use in countless different fields, from novel foods and packaging to medicine and medical care, daily commodities, farming and agriculture, and the environmental, chemical

The role of tip deflection on the thrust produced by rigid flapping fins

Science.gov (United States)

Huera-Huarte, Francisco; Gharib, Morteza

2015-11-01

It is well known that flexibility plays an important role in the propulsion performance and efficiency of oscillating fin based propulsion systems. Compliance is one of the aspects that has received more attention, as it seems to be a common feature in nature's flyers and swimmers. Active control strategies are also common in nature. We will show how by deflecting only the last 10% of length of a rigid fin, at the tip, the thrust can be changed dramatically. This can be thought as an alternative to passive flexibility for controlling very efficiently the momentum transfer in the wake and therefore the thrust generation when flapping. A series of experiments have been carried with a robotic fin that allowed the control of its flapping kinematics as well as the control of the motions of its tip independently. We will be showing situations in which the tip was kept at a certain fixed position during a power stroke, and others in which it moved either in-phase or out-of-phase with the fin. The observed thrust and wake dynamics will be discussed for all these situations. The authors would like to acknowledge the financial support provided by the Gordon and Betty Moore Foundation and by the Spanish Ministerio de Economia y competitividad (MINECO) through grant DPI2012-37904. Visiting Associate in Aerospace, California Institute of Technology.

Prezzi rigidi, prezzi flessibili e inflazione. (Rigid prices, flexible prices and inflation

Directory of Open Access Journals (Sweden)

P. SYLOS LABINI

2013-12-01

Full Text Available Sebbene il concetto di un livello generale dei prezzi è di qualche utilità limitata a studi puramente statistici e descrittivi , è pericoloso e ingannevole nel campo delle analisi teoriche che mirano a spiegare variazioni di prezzo . Qualsiasi analisi fruttuosa deve distinguere tra i vari tipi di mercati e merci in quanto, nel breve e lungo termine, i meccanismi di formazione dei prezzi e variazione dipendono dagli stessi. In questo lavoro , l'autore dedica particolare attenzione alla dicotomia tra materie prime e merci . Un'altra dicotomia è introdotta con riferimento al mercato del lavoro . La base logica per la doppia dicotomia è data dal grado di flessibilità , rispetto alla domanda , di prezzi e redditi .Although the concept of a general price level is of some limited use in purely statistical and descriptive studies, it is dangerous and deceptive in the field of theoretical analyses which aim at explaining price variations. Any fruitful analysis must distinguish between various types of markets and goods since, in the short and long run, the mechanisms of price formation and variation are dependent on such. In this work, the author devotes special attention to the dichotomy of raw materials and manufactures, a regards goods. Another dichotomy is introduced with reference to the labour market. The logical basis for the double dichotomy is given by the degree of flexibility, in relation to demand, of prices and earnings.JEL: E31

Conformational Flexibility of Proteins Involved in Ribosome Biogenesis: Investigations via Small Angle X-ray Scattering (SAXS

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Dritan Siliqi

2018-02-01

Full Text Available The dynamism of proteins is central to their function, and several proteins have been described as flexible, as consisting of multiple domains joined by flexible linkers, and even as intrinsically disordered. Several techniques exist to study protein structures, but small angle X-ray scattering (SAXS has proven to be particularly powerful for the quantitative analysis of such flexible systems. In the present report, we have used SAXS in combination with X-ray crystallography to highlight their usefulness at characterizing flexible proteins, using as examples two proteins involved in different steps of ribosome biogenesis. The yeast BRCA2 and CDKN1A-interactig protein, Bcp1, is a chaperone for Rpl23 of unknown structure. We showed that it consists of a rigid, slightly elongated protein, with a secondary structure comprising a mixture of alpha helices and beta sheets. As an example of a flexible molecule, we studied the SBDS (Shwachman-Bodian-Diamond Syndrome protein that is involved in the cytoplasmic maturation of the 60S subunit and constitutes the mutated target in the Shwachman-Diamond Syndrome. In solution, this protein coexists in an ensemble of three main conformations, with the N- and C-terminal ends adopting different orientations with respect to the central domain. The structure observed in the protein crystal corresponds to an average of those predicted by the SAXS flexibility analysis.

Dyadic flexibility and positive affect in parent–child coregulation and the development of child behavior problems

Science.gov (United States)

LUNKENHEIMER, ERIKA S.; OLSON, SHERYL L.; HOLLENSTEIN, TOM; SAMEROFF, ARNOLD J.; WINTER, CHARLOTTE

2018-01-01

Parent–child dyadic rigidity and negative affect contribute to children’s higher levels of externalizing problems. The present longitudinal study examined whether the opposite constructs of dyadic flexibility and positive affect predicted lower levels of externalizing behavior problems across the early childhood period. Mother–child (N = 163) and father–child (n = 94) dyads engaged in a challenging block design task at home when children were 3 years old. Dynamic systems methods were used to derive dyadic positive affect and three indicators of dyadic flexibility (range, dispersion, and transitions) from observational coding. We hypothesized that the interaction between dyadic flexibility and positive affect would predict lower levels of externalizing problems at age 5.5 years as rated by mothers and teachers, controlling for stability in externalizing problems, task time, child gender, and the child’s effortful control. The hypothesis was supported in predicting teacher ratings of child externalizing from both mother–child and father–child interactions. There were also differential main effects for mothers and fathers: mother–child flexibility was detrimental and father–child flexibility was beneficial for child outcomes. Results support the inclusion of adaptive and dynamic parent–child coregulation processes in the study of children’s early disruptive behavior. PMID:23786697

Associative memory through rigid origami

Science.gov (United States)

Murugan, Arvind; Brenner, Michael

2015-03-01

Mechanisms such as Miura Ori have proven useful in diverse contexts since they have only one degree of freedom that is easily controlled. We combine the theory of rigid origami and associative memory in frustrated neural networks to create structures that can ``learn'' multiple generic folding mechanisms and yet can be robustly controlled. We show that such rigid origami structures can ``recall'' a specific learned mechanism when induced by a physical impulse that only need resemble the desired mechanism (i.e. robust recall through association). Such associative memory in matter, seen before in self-assembly, arises due to a balance between local promiscuity (i.e., many local degrees of freedom) and global frustration which minimizes interference between different learned behaviors. Origami with associative memory can lead to a new class of deployable structures and kinetic architectures with multiple context-dependent behaviors.

Functionally rigid bistable [2]rotaxanes

DEFF Research Database (Denmark)

Nygaard, Sune; Leung, Ken C-F; Aprahamian, Ivan

2007-01-01

defines an unambiguous distance of 1.5 nm over which the ring moves between the MPTTF and NP units. The degenerate NP/NP [2]rotaxane was used to investigate the shuttling barrier by dynamic 1H NMR spectroscopy for the movement of the CBPQT4+ ring across the new rigid spacer. It is evident from...... better control over the position of the ring component in the ground state but also for control over the location of the CBPQT4+ ring during solution-state switching experiments, triggered either chemically (1H NMR) or electrochemically (cyclic voltammetry). In this instance, the use of the rigid spacer......Two-station [2]rotaxanes in the shape of a degenerate naphthalene (NP) shuttle and a nondegenerate monopyrrolotetrathiafulvalene (MPTTF)/NP redox-controllable switch have been synthesized and characterized in solution. Their dumbbell-shaped components are composed of polyether chains interrupted...

Rigid external maxillary distraction and rhinoplasty for pyknodysostosis.

Science.gov (United States)

Varol, Altan; Sabuncuoglu, Fidan Alakus; Sencimen, Metin; Akcam, Timur; Olmez, Hüseyin; Basa, Selçuk

2011-05-01

This article reports the treatment of an 33-year-old female patient with pyknodysostosis by rigid external distraction II midface distraction system. The patient with pyknodysostosis described in this report had severe midfacial hypoplasia. Correction of this by use of routine orthognathic surgery would require osteosynthesis and bone grafting. Risk of infection and/or nonunion after such a surgical procedure was considered too great, and therefore the possibility of treatment by distraction osteogenesis of the maxilla was evaluated. The rigid external distraction II midface distraction system was used to relocate the hypoplastic maxilla at anterior-inferior projection. Distraction osteogenesis should be considered as the primary reconstructive method for maxillofacial deformities in patients with sclerosing bone dysplasias, since this is the second reported case treated successfully with rigid external distraction.

Colonization of bone matrices by cellular components

Science.gov (United States)

Shchelkunova, E. I.; Voropaeva, A. A.; Korel, A. V.; Mayer, D. A.; Podorognaya, V. T.; Kirilova, I. A.

2017-09-01

Practical surgery, traumatology, orthopedics, and oncology require bioengineered constructs suitable for replacement of large-area bone defects. Only rigid/elastic matrix containing recipient's bone cells capable of mitosis, differentiation, and synthesizing extracellular matrix that supports cell viability can comply with these requirements. Therefore, the development of the techniques to produce structural and functional substitutes, whose three-dimensional structure corresponds to the recipient's damaged tissues, is the main objective of tissue engineering. This is achieved by developing tissue-engineering constructs represented by cells placed on the matrices. Low effectiveness of carrier matrix colonization with cells and their uneven distribution is one of the major problems in cell culture on various matrixes. In vitro studies of the interactions between cells and material, as well as the development of new techniques for scaffold colonization by cellular components are required to solve this problem.

Rigid origami vertices: conditions and forcing sets

Directory of Open Access Journals (Sweden)

Zachary Abel

2016-04-01

Full Text Available We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly.  We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case.  We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.

Type number and rigidity of fibred surfaces

International Nuclear Information System (INIS)

Markov, P E

2001-01-01

Infinitesimal l-th order bendings, 1≤l≤∞, of higher-dimensional surfaces are considered in higher-dimensional flat spaces (for l=∞ an infinitesimal bending is assumed to be an analytic bending). In terms of the Allendoerfer type number, criteria are established for the (r,l)-rigidity (in the terminology of Sabitov) of such surfaces. In particular, an (r,l)-infinitesimal analogue is proved of the classical theorem of Allendoerfer on the unbendability of surfaces with type number ≥3 and the class of (r,l)-rigid fibred surfaces is distinguished

Evaluating a method for automated rigid registration

DEFF Research Database (Denmark)

Darkner, Sune; Vester-Christensen, Martin; Larsen, Rasmus

2007-01-01

to point distance. T-test for common mean are used to determine the performance of the two methods (supported by a Wilcoxon signed rank test). The performance influence of sampling density, sampling quantity, and norms is analyzed using a similar method.......We evaluate a novel method for fully automated rigid registration of 2D manifolds in 3D space based on distance maps, the Gibbs sampler and Iterated Conditional Modes (ICM). The method is tested against the ICP considered as the gold standard for automated rigid registration. Furthermore...

Scaling of the dynamics of flexible Lennard-Jones chains

DEFF Research Database (Denmark)

Veldhorst, Arno; Dyre, Jeppe C.; Schrøder, Thomas

2015-01-01

The previous paper [A. A. Veldhorst et al., J. Chem. Phys. 141, 054904 (2014)] demonstrated that the isomorph theory explains the scaling properties of a liquid of flexible chains consisting of ten Lennard-Jones particles connected by rigid bonds. We here investigate the same model with harmonic......, dynamics, and the excess entropy are invariant. The Lennard-Jones chain liquid with harmonic bondsdoes have curves in the phase diagram along which the structure and dynamics are invariant. The excess entropy is not invariant on these curves, which we refer to as “pseudoisomorphs.” In particular......, this means that Rosenfeld’s excess-entropy scaling (the dynamics being a function of excess entropy only) does not apply for the Lennard-Jones chain with harmonic bonds...

Analytical modeling of mode selection and power control for underlay D2D communication in cellular networks

KAUST Repository

Elsawy, Hesham

2014-11-01

Device-to-device (D2D) communication enables the user equipments (UEs) located in close proximity to bypass the cellular base stations (BSs) and directly connect to each other, and thereby, offload traffic from the cellular infrastructure. D2D communication can improve spatial frequency reuse and energy efficiency in cellular networks. This paper presents a comprehensive and tractable analytical framework for D2D-enabled uplink cellular networks with a flexible mode selection scheme along with truncated channel inversion power control. The developed framework is used to analyze and understand how the underlaying D2D communication affects the cellular network performance. Through comprehensive numerical analysis, we investigate the expected performance gains and provide guidelines for selecting the network parameters.

Lateral rigidity of cracked concrete structures

International Nuclear Information System (INIS)

Castellani, A.; Chesi, C.

1979-01-01

Numerical results are discussed on the lateral rigidity of reinforced concrete structures with a given crack distribution. They have been favourably checked with experimental results for cylindrical shells under the effect of a thermal gradient producing vertical cracking or vertical plus horizontal cracking. The main effects characterizing the concrete behaviour are: (1) The shear transfer across a crack; (2) The shear transfer degradation after cyclic loading; (3) The tension stiffening provided by the concrete between crack and crack, in the normal stress transfer; (4) The temperature effect on the elastic moduli of concrete, when cracks are of thermal origin. Only the 1st effect is discussed on an experimental basis. Two broad cathegories of reinforced concrete structures have been investigated in this respect: shear walls of buildings and cylindrical containment structures. The main conclusions so far reached are: (1) Vertical cracks are unlikely to decrease the lateral rigidity to less than 80% of the original one, and to less than 90% when they do not involve the entire thickness of the wall; (2) The appearence of horizontal cracks can reduce the lateral rigidity by some 30% or more; (3) A noticeable but not yet evaluated influence is shown by cyclic loading. (orig.)

An analytical model and scaling of chordwise flexible flapping wings in forward flight.

Science.gov (United States)

Kodali, Deepa; Kang, Chang-Kwon

2016-12-13

Aerodynamic performance of biological flight characterized by the fluid structure interaction of a flapping wing and the surrounding fluid is affected by the wing flexibility. One of the main challenges to predict aerodynamic forces is that the wing shape and motion are a priori unknown. In this study, we derive an analytical fluid-structure interaction model for a chordwise flexible flapping two-dimensional airfoil in forward flight. A plunge motion is imposed on the rigid leading-edge (LE) of teardrop shape and the flexible tail dynamically deforms. The resulting unsteady aeroelasticity is modeled with the Euler-Bernoulli-Theodorsen equation under a small deformation assumption. The two-way coupling is realized by considering the trailing-edge deformation relative to the LE as passive pitch, affecting the unsteady aerodynamics. The resulting wing deformation and the aerodynamic performance including lift and thrust agree well with high-fidelity numerical results. Under the dynamic balance, the aeroelastic stiffness decreases, whereas the aeroelastic stiffness increases with the reduced frequency. A novel aeroelastic frequency ratio is derived, which scales with the wing deformation, lift, and thrust. Finally, the dynamic similarity between flapping in water and air is established.

High-Performance Flexible Magnetic Tunnel Junctions for Smart Miniaturized Instruments

KAUST Repository

Amara, Selma.

2018-04-04

Flexible electronics is an emerging field in many applications ranging from in vivo biomedical devices to wearable smart systems. The capability of conforming to curved surfaces opens the door to add electronic components to miniaturized instruments, where size and weight are critical parameters. Given their prevalence on the sensors market, flexible magnetic sensors play a major role in this progress. For many high-performance applications, magnetic tunnel junctions (MTJs) have become the first choice, due to their high sensitivity, low power consumption etc. MTJs are also promising candidates for non-volatile next-generation data storage media and, hence, could become central components of wearable electronic devices. In this work, a generic low-cost regenerative batch fabrication process is utilized to transform rigid MTJs on a 500 {\\\\mu}m silicon wafer substrate into 5 {\\\\mu}m thin, mechanically flexible silicon devices, and ensuring optimal utilization of the whole substrate. This method maintains the outstanding magnetic properties, which are only obtained by deposition of the MTJ on smooth high-quality silicon wafers. The flexible MTJs are highly reliable and resistive to mechanical stress. Bending of the MTJ stacks with a diameter as small as 500 {\\\\mu}m is possible without compromising their performance and an endurance of over 1000 cycles without fatigue has been demonstrated. The flexible MTJs were mounted onto the tip of a cardiac catheter with 2 mm in diameter without compromising their performance. This enables the detection of magnetic fields and the angle which they are applied at with a high sensitivity of 4.93 %/Oe and a low power consumption of 0.15 {\\\\mu}W, while adding only 8 {\\\\mu}g and 15 {\\\\mu}m to the weight and diameter of the catheter, respectively.

Connections rigidity effect on probability of fracture in steel moment frames

Directory of Open Access Journals (Sweden)

Gholamreza Abdollahzadeh

2017-08-01

Full Text Available Connections in steel moment frames are idealized in full pinned and full rigid conditions. Because with this assumption, in spite of real behavior of connection, real story drifts are less anticipated and maybe frame is designed without performance of bracing. There are several methods for modeling actual behavior of semi rigid connections. In this method a connection with certain rigidity is modeled by a rotational spring with corresponding stiffness. This stiffness is achieved by certain formula. In other words, each percent of rigidity corresponds to one rotational spring stiffness. In this research in order to evaluate the real behavior of connection in analysis and designing process and fracture probability one frame including four stories and one bay with three types of connection has been modeled and designed in ETABS. Each model has an individual rigidity which is equal to 10, 75 and 90 percent. With respect to maximum drift and different PGA in roof, probabilities of low, medium, high and complete fracture were calculated. For this purpose, with applying different PGA to modeled frames, amounts of drift in the roof are achieved. Then these values are compared with given values in American code. Finally, investigation showed that when rigidity in frame connections increases, the probability of frame fracture decreases. In other words, fully rigid assumption of connection in analysis process leads to decreasing in real probability of fracture in frames which is a noticeable risk in building designing processes.

Rigid-plastic seismic design of reinforced concrete structures

DEFF Research Database (Denmark)

Costa, Joao Domingues; Bento, R.; Levtchitch, V.

2007-01-01

structural strength with respect to a pre-defined performance parameter using a rigid-plastic response spectrum, which is characteristic of the ground motion alone. The maximum strength demand at any point is solely dependent on the intensity of the ground motion, which facilitates the task of distributing......In this paper a new seismic design procedure for Reinforced Concrete (R/C) structures is proposed-the Rigid-Plastic Seismic Design (RPSD) method. This is a design procedure based on Non-Linear Time-History Analysis (NLTHA) for systems expected to perform in the non-linear range during a lifetime...... earthquake event. The theoretical background is the Theory of Plasticity (Rigid-Plastic Structures). Firstly, a collapse mechanism is chosen and the corresponding stress field is made safe outside the regions where plastic behaviour takes place. It is shown that this allows the determination of the required...

Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

Energy Technology Data Exchange (ETDEWEB)

Ghoneim, M. T.; Hussain, M. M., E-mail: muhammadmustafa.hussain@kaust.edu.sa [Integrated Nanotechnology Lab, Electrical Engineering, Computer Electrical Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)

2015-08-03

Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ∼260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures.

Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

International Nuclear Information System (INIS)

Ghoneim, M. T.; Hussain, M. M.

2015-01-01

Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ∼260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures

Study of harsh environment operation of flexible ferroelectric memory integrated with PZT and silicon fabric

KAUST Repository

Ghoneim, Mohamed T.

2015-08-05

Flexible memory can enable industrial, automobile, space, and smart grid centered harsh/extreme environment focused electronics application(s) for enhanced operation, safety, and monitoring where bent or complex shaped infrastructures are common and state-of-the-art rigid electronics cannot be deployed. Therefore, we report on the physical-mechanical-electrical characteristics of a flexible ferroelectric memory based on lead zirconium titanate as a key memory material and flexible version of bulk mono-crystalline silicon (100). The experimented devices show a bending radius down to 1.25 cm corresponding to 0.16% nominal strain (high pressure of ∼260 MPa), and full functionality up to 225 °C high temperature in ambient gas composition (21% oxygen and 55% relative humidity). The devices showed unaltered data retention and fatigue properties under harsh conditions, still the reduced memory window (20% difference between switching and non-switching currents at 225 °C) requires sensitive sense circuitry for proper functionality and is the limiting factor preventing operation at higher temperatures.

Frequency Analysis of Wing-Rotor System Considering Flexibility in Capsule Based on High-Accurate Method

Science.gov (United States)

Zhang, Xiayang; Zhu, Ming; Zhao, Meijuan; Wu, Zhe

2018-05-01

Based on a typical wing-rotor thrust model on the airship, the dynamic influence of the gyroscopic effects from the tip rotor acting on the overall coupled system has been analyzed. Meanwhile, the flexibility at the capsule boundary has been studied, as well. Hamilton's principle is employed to derive the general governing equations and the numerical Rayleigh-Ritz method is finally chosen in actual frequency computations. A new set of shape functions are put forward and verified which take most of the couplings among dimensions into account. The parameter studies are also conducted to make deep investigations. The results demonstrate that the inherent frequencies are significantly affected by the rotor speed and the flexible capsule condition. When rotor revolves, the modal shapes have reached into complex states and the components of each mode will change with the increment of rotor speed. The flexibility will also greatly reduce the entire frequencies compared with the rigid case. It is also demonstrated that the inherent property will be significantly affected by the mounting geometry, rotor inertia, the structural stiffness, and rotor speed.

Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.

Energy Technology Data Exchange (ETDEWEB)

Neilsen, Michael K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Scherzinger, William M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hinnerichs, Terry D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lo, Chi S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-06-01

Numerous experiments were performed to characterize the mechanical response of several different rigid polyurethane foams (FR3712, PMDI10, PMDI20, and TufFoam35) to large deformation. In these experiments, the effects of load path, loading rate, and temperature were investigated. Results from these experiments indicated that rigid polyurethane foams exhibit significant volumetric and deviatoric plasticity when they are compressed. Rigid polyurethane foams were also found to be very strain-rate and temperature dependent. These foams are also rather brittle and crack when loaded to small strains in tension or to larger strains in compression. Thus, a new Unified Creep Plasticity Damage (UCPD) model was developed and implemented into SIERRA with the name Foam Damage to describe the mechanical response of these foams to large deformation at a variety of temperatures and strain rates. This report includes a description of recent experiments and experimental findings. Next, development of a UCPD model for rigid, polyurethane foams is described. Selection of material parameters for a variety of rigid polyurethane foams is then discussed and finite element simulations with the new UCPD model are compared with experimental results to show behavior that can be captured with this model.

Systematic study of the structure of alternate pyromellitimide-PEO copolymers: Influence of the chain flexibility

International Nuclear Information System (INIS)

Djurado, David; Curtet, Jean Pierre; Bee, Marc; Michot, Christophe; Armand, Michel

2007-01-01

The structure of a family of copolyimides in which are alternating stiff/redox pyromellitimide units and flexible/solvating polyethyleneoxide (PEO) strands were studied by using wide angle and small angle X-ray scattering techniques and is fully discussed. It is shown that the rich variety of structures exhibited by these compounds can be understood by considering the dramatic change of flexibility of the chain induced by the variation of the length of the PEO strand compared to that of the pyromellimide segment. In this respect, concerning the compounds which exhibit fully amorphous structures a better understanding of their structural behavior can be obtained in the framework of Flory's theory of semi-rigid polymers. In this approach, the degree of flexibility of the chain is mainly resulting from the relative amount of flexible units constituting the repetition unit of the polymer chain. The final structural mode adopted by each compound in the solid state is then directly a consequence of this intrinsic property of the chain. The introduction of a lithium salt in contact with the copolymer chains induces some structure changes which can also be explained by the modification of the degree of flexibility of the chain. It is found that the best performances in terms of electroactivity and mixed conduction are precisely obtained with the only compound which keeps full amorphicity in absence and in presence of the lithium salt

Elasticity of Relativistic Rigid Bodies?

Science.gov (United States)

Smarandache, Florentin

2013-10-01

In the classical Twin Paradox, according to the Special Theory of Relativity, when the traveling twin blasts off from the Earth to a relative velocity v =√{/3 } 2 c with respect to the Earth, his measuring stick and other physical objects in the direction of relative motion shrink to half their lengths. How is that possible in the real physical world to have let's say a rigid rocket shrinking to half and then later elongated back to normal as an elastic material when it stops? What is the explanation for the traveler's measuring stick and other physical objects, in effect, return to the same length to their original length in the Stay-At-Home, but there is no record of their having shrunk? If it's a rigid (not elastic) object, how can it shrink and then elongate back to normal? It might get broken in such situation.

Rigidity spectrum of Forbush decrease

International Nuclear Information System (INIS)

Sakakibara, S.; Munakata, K.; Nagashima, K.

1985-01-01

Using data from neutron monitors and muon telescopes at surface and underground stations, the average rigidity spectrum of Forbush decreases (Fds) during the period of 1978-1982 were obtained. Thirty eight Ed-events are classified into two groups, Hard Fd and Soft FD according to size of Fd at the Sakashita station. It is found that a spectral form of a fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable than that of a power-exponential type or of a power type with an upper limiting rigidity. The best fitted spectrum of the fractional-power type is expressed by gamma sub1 = 0.37, gamma sub2 = 0.89 and P subc = 10 GV for Hard Fd and gamma sub1 = 0.77, gamma sub2 = 1.02 and P sub c - 14GV for Soft Fd

A computational approach to modeling cellular-scale blood flow in complex geometry

Science.gov (United States)

Balogh, Peter; Bagchi, Prosenjit

2017-04-01

We present a computational methodology for modeling cellular-scale blood flow in arbitrary and highly complex geometry. Our approach is based on immersed-boundary methods, which allow modeling flows in arbitrary geometry while resolving the large deformation and dynamics of every blood cell with high fidelity. The present methodology seamlessly integrates different modeling components dealing with stationary rigid boundaries of complex shape, moving rigid bodies, and highly deformable interfaces governed by nonlinear elasticity. Thus it enables us to simulate 'whole' blood suspensions flowing through physiologically realistic microvascular networks that are characterized by multiple bifurcating and merging vessels, as well as geometrically complex lab-on-chip devices. The focus of the present work is on the development of a versatile numerical technique that is able to consider deformable cells and rigid bodies flowing in three-dimensional arbitrarily complex geometries over a diverse range of scenarios. After describing the methodology, a series of validation studies are presented against analytical theory, experimental data, and previous numerical results. Then, the capability of the methodology is demonstrated by simulating flows of deformable blood cells and heterogeneous cell suspensions in both physiologically realistic microvascular networks and geometrically intricate microfluidic devices. It is shown that the methodology can predict several complex microhemodynamic phenomena observed in vascular networks and microfluidic devices. The present methodology is robust and versatile, and has the potential to scale up to very large microvascular networks at organ levels.

An evaluation of canonical forms for non-rigid 3D shape retrieval

OpenAIRE

Pickup, David; Liu, Juncheng; Sun, Xianfang; Rosin, Paul L.; Martin, Ralph R.; Cheng, Zhiquan; Lian, Zhouhui; Nie, Sipin; Jin, Longcun; Shamai, Gil; Sahillioğlu, Yusuf; Kavan, Ladislav

2018-01-01

Canonical forms attempt to factor out a non-rigid shape’s pose, giving a pose-neutral shape. This opens up the\\ud possibility of using methods originally designed for rigid shape retrieval for the task of non-rigid shape retrieval.\\ud We extend our recent benchmark for testing canonical form algorithms. Our new benchmark is used to evaluate a\\ud greater number of state-of-the-art canonical forms, on five recent non-rigid retrieval datasets, within two different\\ud retrieval frameworks. A tota...

Network flexibility of the IRIDIUM (R) Global Mobile Satellite System

Science.gov (United States)

Hutcheson, Jonathan; Laurin, Mala

1995-01-01

The IRIDIUM system is a global personal communications system supported by a constellation of 66 low earth orbit (LEO) satellites and a collection of earth-based 'gateway' switching installations. Like traditional wireless cellular systems, coverage is achieved by a grid of cells in which bandwidth is reused for spectral efficiency. Unlike any cellular system ever built, the moving cells can be shared by multiple switching facilities. Noteworthy features of the IRIDIUM system include inter-satellite links, a GSM-based telephony architecture, and a geographically controlled system access process. These features, working in concert, permit flexible and reliable administration of the worldwide service area by gateway operators. This paper will explore this unique concept.

Blast wave interaction with a rigid surface

International Nuclear Information System (INIS)

Josey, T.; Whitehouse, D.R.; Ripley, R.C.; Dionne, J.P.

2004-01-01

A simple model used to investigate blast wave interactions with a rigid surface is presented. The model uses a constant volume energy source analogue to predict pressure histories at gauges located directly above the charge. A series of two-dimensional axi-symmetric CFD calculations were performed, varying the height of the charge relative to the ground. Pressure histories, along with isopycnic plots are presented to evaluate the effects of placing a charge in close proximity to a rigid surface. When a charge is placed near a solid surface the pressure histories experienced at gauges above the charge indicate the presence of two distinct pressure peaks. The first peak is caused by the primary shock and the second peak is a result of the wave reflections from the rigid surface. As the distance from the charge to the wall is increased the magnitude of the second pressure peak is reduced, provided that the distance between the charge and the gauge is maintained constant. The simple model presented is able to capture significant, predictable flow features. (author)

Towards Flexible Self-powered Micro-scale Integrated Systems

KAUST Repository

Rojas, Jhonathan Prieto

2014-04-01

Today’s information-centered world leads the ever-increasing consumer demand for more powerful, multifunctional portable devices. Additionally, recent developments on long-lasting energy sources and compliant, flexible systems, have introduced new required features to the portable devices industry. For example, wireless sensor networks are in urgent need of self-sustainable, easy-to-deploy, mobile platforms, wirelessly interconnected and accessible through a cloud computing system. The objective of my doctoral work is to develop integration strategies to effectively fabricate mechanically flexible, energy-independent systems, which could empower sensor networks for a great variety of new exciting applications. The first module, flexible electronics, can be achieved through several techniques and materials. Our main focus is to bring mechanical flexibility to the state-of-the-art high performing silicon-based electronics, with billions of ultra-low power, nano-sized transistors. Therefore, we have developed a low-cost batch fabrication process to transform standard, rigid, mono-crystalline silicon (100) wafer with devices, into a thin (5-20 m), mechanically flexible, optically semi-transparent silicon fabric. Recycling of the remaining wafer is possible, enabling generation of multiple fabrics to ensure lowcost and optimal utilization of the whole substrate. We have shown mono, amorphous and poly-crystalline silicon and silicon dioxide fabrics, featuring industry’s most advanced high-/metal-gate based capacitors and transistors. The second module consists on the development of efficient energy scavenging systems. First, we have identified an innovative and relatively young technology, which can address at the same time two of the main concerns of human kind: water and energy. Microbial fuel cells (MFC) are capable of producing energy out the metabolism of bacteria while treating wastewater. We have developed two micro-liter MFC designs, one with carbon

Transforming (perceived rigidity in environmental law through adaptive governance: a case of Endangered Species Act implementation

Directory of Open Access Journals (Sweden)

Hannah Gosnell

2017-12-01

Full Text Available The Endangered Species Act (ESA is often portrayed as a major source of instability and crisis in river basins of the U.S. West, where the needs of listed fish species frequently clash with agriculture dependent on federal irrigation projects subject to ESA Section 7 prohibitions on federal agency actions likely to jeopardize listed species or adversely modify critical habitat. Scholarship on Section 7 characterizes the process as unwaveringly rigid, the legal "hammer" forcing federal agencies to consider endangered species' needs when proposing operations and management plans for federally funded irrigation. In this paper, we identify barriers to an integrated approach to Section 7 implementation and characterize a set of strategies for overcoming its rigidity that may have broader applicability. We draw on lessons derived from the Klamath Basin along the Oregon-California border, where cross-scale processes and venues involving interagency collaboration among leaders in the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and the U.S. Bureau of Reclamation supported efforts to replace an ecologically and socially fragmented Upper Basin/Lower Basin approach to ESA implementation fraught with conflict. The result was the nation's first joint biological opinion (BiOp, which effectively institutionalized an adaptive, flexible, integrated approach to water sharing among competing interests. Keys to success included existing collaborative capacity related to shifting stakeholder networks, trust, and relationships and a shift in local agency culture facilitated by empathic leadership leading to a greater sense of shared responsibility for Section 7 compliance. A collaborative hydrologic modeling process enhanced participatory capacity, facilitated transformative social and technical learning, and cultivated greater understanding of the social-ecological system among key stakeholders. The 2013 joint BiOp exemplifies both

Perencanaan dan Analisis Biaya Investasi antara Perkerasan Kaku dengan Perkerasan Lentur pada Jalur Trans Jakarta Busway: Studi Kasus pada Trans Jakarta Busway Koridor 8 antara Halte Pondok Indah 2 hingga Halte Permata Hijau

Directory of Open Access Journals (Sweden)

Eduardi Prahara

2012-12-01

Full Text Available Types of rigid pavement for road has been widely used in Indonesia, ranging from toll roads to the outer town road. Rigid pavement is considered more powerful than the flexible pavement. In other words, rigid pavement is expected to have a longer service life and minimal maintenance. The construction cost for rigid pavement is more expensive compared to flexible pavement. While the need for rigid pavement maintenance is cheaper than for flexible pavement. Seen from investment point of view, rigid pavement is more profitable than flexible pavement, because the annual fee required for rigid pavement is less. Due to the comparations, an analysis is performed in this study to select which type of pavement is best used in the future.

Room to high temperature measurements of flexible SOI FinFETs with sub-20-nm fins

KAUST Repository

Diab, Amer El Hajj

2014-12-01

We report the temperature dependence of the core electrical parameters and transport characteristics of a flexible version of fin field-effect transistor (FinFET) on silicon-on-insulator (SOI) with sub-20-nm wide fins and high-k/metal gate-stacks. For the first time, we characterize them from room to high temperature (150 °C) to show the impact of temperature variation on drain current, gate leakage current, and transconductance. Variation of extracted parameters, such as low-field mobility, subthreshold swing, threshold voltage, and ON-OFF current characteristics, is reported too. Direct comparison is made to a rigid version of the SOI FinFETs. The mobility degradation with temperature is mainly caused by phonon scattering mechanism. The overall excellent devices performance at high temperature after release is outlined proving the suitability of truly high-performance flexible inorganic electronics with such advanced architecture.

Functional integrity of flexible n-channel metal–oxide–semiconductor field-effect transistors on a reversibly bistable platform

Energy Technology Data Exchange (ETDEWEB)

Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan P.; Hussain, Muhammad M., E-mail: MuhammadMustafa.Hussain@kaust.edu.sa [Integrated Nanotechnology Laboratory, Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Aljedaani, Abdulrahman B. [High-Speed Fluids Imaging Laboratory, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)

2015-10-26

Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal–oxide–semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

Geometric nonlinear effects on the planar dynamics of a pivoted flexible beam encountering a point-surface impact

International Nuclear Information System (INIS)

Li Qing; Wang Tianshu; Ma Xingrui

2009-01-01

Flexible-body modeling with geometric nonlinearities remains a hot topic of research by applications in multibody system dynamics undergoing large overall motions. However, the geometric nonlinear effects on the impact dynamics of flexible multibody systems have attracted significantly less attention. In this paper, a point-surface impact problem between a rigid ball and a pivoted flexible beam is investigated. The Hertzian contact law is used to describe the impact process, and the dynamic equations are formulated in the floating frame of reference using the assumed mode method. The two important geometric nonlinear effects of the flexible beam are taken into account, i.e., the longitudinal foreshortening effect due to the transverse deformation, and the stress stiffness effect due to the axial force. The simulation results show that good consistency can be obtained with the nonlinear finite element program ABAQUS/Explicit if proper geometric nonlinearities are included in the floating frame formulation. Specifically, only the foreshortening effect should be considered in a pure transverse impact for efficiency, while the stress stiffness effect should be further considered in an oblique case with much more computational effort. It also implies that the geometric nonlinear effects should be considered properly in the impact dynamic analysis of more general flexible multibody systems

Functional integrity of flexible n-channel metal–oxide–semiconductor field-effect transistors on a reversibly bistable platform

International Nuclear Information System (INIS)

Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan P.; Hussain, Muhammad M.; Aljedaani, Abdulrahman B.

2015-01-01

Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal–oxide–semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties

Functional integrity of flexible n-channel metal–oxide–semiconductor field-effect transistors on a reversibly bistable platform

KAUST Repository

Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan Prieto; Aljedaani, Abdulrahman B.; Hussain, Muhammad Mustafa

2015-01-01

Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal–oxide–semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

Functional integrity of flexible n-channel metal-oxide-semiconductor field-effect transistors on a reversibly bistable platform

Science.gov (United States)

Alfaraj, Nasir; Hussain, Aftab M.; Torres Sevilla, Galo A.; Ghoneim, Mohamed T.; Rojas, Jhonathan P.; Aljedaani, Abdulrahman B.; Hussain, Muhammad M.

2015-10-01

Flexibility can bring a new dimension to state-of-the-art electronics, such as rollable displays and integrated circuit systems being transformed into more powerful resources. Flexible electronics are typically hosted on polymeric substrates. Such substrates can be bent and rolled up, but cannot be independently fixed at the rigid perpendicular position necessary to realize rollable display-integrated gadgets and electronics. A reversibly bistable material can assume two stable states in a reversible way: flexibly rolled state and independently unbent state. Such materials are used in cycling and biking safety wristbands and a variety of ankle bracelets for orthopedic healthcare. They are often wrapped around an object with high impulsive force loading. Here, we study the effects of cumulative impulsive force loading on thinned (25 μm) flexible silicon-based n-channel metal-oxide-semiconductor field-effect transistor devices housed on a reversibly bistable flexible platform. We found that the transistors have maintained their high performance level up to an accumulated 180 kN of impact force loading. The gate dielectric layers have maintained their reliability, which is evidenced by the low leakage current densities. Also, we observed low variation in the effective electron mobility values, which manifests that the device channels have maintained their carrier transport properties.

Rigidity of the magic pentagram game

Science.gov (United States)

Kalev, Amir; Miller, Carl A.

2018-01-01

A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

Rigidity of the magic pentagram game.

Science.gov (United States)

Kalev, Amir; Miller, Carl A

2018-01-01

A game is rigid if a near-optimal score guarantees, under the sole assumption of the validity of quantum mechanics, that the players are using an approximately unique quantum strategy. Rigidity has a vital role in quantum cryptography as it permits a strictly classical user to trust behavior in the quantum realm. This property can be traced back as far as 1998 (Mayers and Yao) and has been proved for multiple classes of games. In this paper we prove ridigity for the magic pentagram game, a simple binary constraint satisfaction game involving two players, five clauses and ten variables. We show that all near-optimal strategies for the pentagram game are approximately equivalent to a unique strategy involving real Pauli measurements on three maximally-entangled qubit pairs.

Elastic properties of rigid fiber-reinforced composites

Science.gov (United States)

Chen, J.; Thorpe, M. F.; Davis, L. C.

1995-05-01

We study the elastic properties of rigid fiber-reinforced composites with perfect bonding between fibers and matrix, and also with sliding boundary conditions. In the dilute region, there exists an exact analytical solution. Around the rigidity threshold we find the elastic moduli and Poisson's ratio by decomposing the deformation into a compression mode and a rotation mode. For perfect bonding, both modes are important, whereas only the compression mode is operative for sliding boundary conditions. We employ the digital-image-based method and a finite element analysis to perform computer simulations which confirm our analytical predictions.

Next generation non-vacuum, maskless, low temperature nanoparticle ink laser digital direct metal patterning for a large area flexible electronics.

Science.gov (United States)

Yeo, Junyeob; Hong, Sukjoon; Lee, Daehoo; Hotz, Nico; Lee, Ming-Tsang; Grigoropoulos, Costas P; Ko, Seung Hwan

2012-01-01

Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition- and photolithography-based conventional metal patterning processes. The "digital" nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm) and high-performance flexible organic field effect transistor arrays.

Next generation non-vacuum, maskless, low temperature nanoparticle ink laser digital direct metal patterning for a large area flexible electronics.

Directory of Open Access Journals (Sweden)

Junyeob Yeo

Full Text Available Flexible electronics opened a new class of future electronics. The foldable, light and durable nature of flexible electronics allows vast flexibility in applications such as display, energy devices and mobile electronics. Even though conventional electronics fabrication methods are well developed for rigid substrates, direct application or slight modification of conventional processes for flexible electronics fabrication cannot work. The future flexible electronics fabrication requires totally new low-temperature process development optimized for flexible substrate and it should be based on new material too. Here we present a simple approach to developing a flexible electronics fabrication without using conventional vacuum deposition and photolithography. We found that direct metal patterning based on laser-induced local melting of metal nanoparticle ink is a promising low-temperature alternative to vacuum deposition- and photolithography-based conventional metal patterning processes. The "digital" nature of the proposed direct metal patterning process removes the need for expensive photomask and allows easy design modification and short turnaround time. This new process can be extremely useful for current small-volume, large-variety manufacturing paradigms. Besides, simple, scalable, fast and low-temperature processes can lead to cost-effective fabrication methods on a large-area polymer substrate. The developed process was successfully applied to demonstrate high-quality Ag patterning (2.1 µΩ·cm and high-performance flexible organic field effect transistor arrays.

Rigid pricing and rationally inattentive consumer

Czech Academy of Sciences Publication Activity Database

Matějka, Filip

158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: RVO:67985998 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015

Gold nanoparticle-embedded silk protein-ZnO nanorod hybrids for flexible bio-photonic devices

Science.gov (United States)

Gogurla, Narendar; Kundu, Subhas C.; Ray, Samit K.

2017-04-01

Silk protein has been used as a biopolymer substrate for flexible photonic devices. Here, we demonstrate ZnO nanorod array hybrid photodetectors on Au nanoparticle-embedded silk protein for flexible optoelectronics. Hybrid samples exhibit optical absorption at the band edge of ZnO as well as plasmonic energy due to Au nanoparticles, making them attractive for selective UV and visible wavelength detection. The device prepared on Au-silk protein shows a much lower dark current and a higher photo to dark-current ratio of ∼105 as compared to the control sample without Au nanoparticles. The hybrid device also exhibits a higher specific detectivity due to higher responsivity arising from the photo-generated hole trapping by Au nanoparticles. Sharp pulses in the transient photocurrent have been observed in devices prepared on glass and Au-silk protein substrates due to the light induced pyroelectric effect of ZnO, enabling the demonstration of self-powered photodetectors at zero bias. Flexible hybrid detectors have been demonstrated on Au-silk/polyethylene terephthalate substrates, exhibiting characteristics similar to those fabricated on rigid glass substrates. A study of the performance of photodetectors with different bending angles indicates very good mechanical stability of silk protein based flexible devices. This novel concept of ZnO nanorod array photodetectors on a natural silk protein platform provides an opportunity to realize integrated flexible and self-powered bio-photonic devices for medical applications in near future.

Initial Development of an Electronic Testis Rigidity Tester

Directory of Open Access Journals (Sweden)

Petros Mirilas

2011-01-01

Full Text Available We aimed to develop our previously presented mechanical device, the Testis Rigidity Tester (TRT, into an electronic system (Electronic Testis Rigidity Tester, ETRT by applying tactile imaging, which has been used successfully with other solid organs. A measuring device, located at the front end of the ETRT incorporates a tactile sensor comprising an array of microsensors. By application of a predetermined deformation of 2 mm, increased pressure alters linearly the resistance of each microsensor, producing changes of voltage. These signals were amplified, filtered, and digitized, and then processed by an electronic collector system, which presented them as a color-filled contour plot of the area of the testis coming into contact with the sensor. Testis models of different rigidity served for initial evaluation of ETRT; their evacuated central spaces contained different, increasing glue masses. An independent method of rigidity measurement, using an electric weight scale and a micrometer, showed that the more the glue injected, the greater the force needed for a 2-mm deformation. In a preliminary test, a single sensor connected to a multimeter showed similar force measurement for the same deformation in these phantoms. For each of the testis models compressed in the same manner, the ETRT system offered a map of pressures, represented by a color scale within the contour plot of the contact area with the sensor. ETRT found certain differences in rigidity between models that had escaped detection by a blind observer. ETRT is easy to use and provides a color-coded “insight“ of the testis internal structure. After experimental testing, it could be valuable in intraoperative evaluation of testes, so that the surgeon can decide about orchectomy or orcheopexy.

Acoustic levitation with self-adaptive flexible reflectors.

Science.gov (United States)

Hong, Z Y; Xie, W J; Wei, B

2011-07-01

Two kinds of flexible reflectors are proposed and examined in this paper to improve the stability of single-axis acoustic levitator, especially in the case of levitating high-density and high-temperature samples. One kind is those with a deformable reflecting surface, and the other kind is those with an elastic support, both of which are self-adaptive to the change of acoustic radiation pressure. High-density materials such as iridium (density 22.6 gcm(-3)) are stably levitated at room temperature with a soft reflector made of colloid as well as a rigid reflector supported by a spring. In addition, the containerless melting and solidification of binary In-Bi eutectic alloy (melting point 345.8 K) and ternary Ag-Cu-Ge eutectic alloy (melting point 812 K) are successfully achieved by applying the elastically supported reflector with the assistance of a laser beam.

Design, simulation and characterization of a MEMS inertia switch with flexible CNTs/Cu composite array layer between electrodes for prolonging contact time

International Nuclear Information System (INIS)

Wang, Yang; Yang, Zhuoqing; Xu, Qiu; Chen, Wenguo; Ding, Guifu; Zhao, Xiaolin

2015-01-01

This paper reports an inertia switch with a flexible carbon nanotubes/copper (CNTs/Cu) composite array layer between movable and fixed electrodes, which achieves a longer contact time compared to the traditional design using rigid-to-rigid impact between electrodes. The CNTs/Cu layer is fabricated using the composite electroplating method, and the whole device is completed by multi-layer metal electroplating based on the micro-electro-mechanical systems (MEMS) process. The dynamic responses of the designed inertia switch and the contact impact between a single CNT and a fixed electrode/another CNT have both been simulated by the ANSYS finite-element-method (FEM). It is shown that the contact time of the designed inertia switch is about 100 µs under the applied 80 g half-sine-shaped acceleration in the sensing direction. Finally, the fabricated MEMS inertia switch with the flexible CNTs/Cu composite array layer between electrodes has been evaluated by a dropping hammer system. The test contact time is about112 µs, which has a good agreement with the simulation and is much longer than that of the traditional design. (paper)

Signature of Thermal Rigidity Percolation

International Nuclear Information System (INIS)

Huerta, Adrián

2013-01-01

To explore the role that temperature and percolation of rigidity play in determining the macroscopic properties, we propose a model that adds translational degrees of freedom to the spins of the well known Ising hamiltonian. In particular, the Ising model illustrate the longstanding idea that the growth of correlations on approach to a critical point could be describable in terms of the percolation of some sort of p hysical cluster . For certain parameters of this model we observe two well defined peaks of C V , that suggest the existence of two kinds of p hysical percolation , namely connectivity and rigidity percolation. Thermal fluctuations give rise to two different kinds of elementary excitations, i.e. droplets and configuron, as suggested by Angell in the framework of a bond lattice model approach. The later is reflected in the fluctuations of redundant constraints that gives stability to the structure and correlate with the order parameter

Rigid pricing and rationally inattentive consumer

Czech Academy of Sciences Publication Activity Database

Matějka, Filip

158 B, July (2015), s. 656-678 ISSN 0022-0531 Institutional support: PRVOUK-P23 Keywords : rational inattention * imperfect information * nominal rigidity Subject RIV: AH - Economics Impact factor: 1.097, year: 2015

Accuracy limit of rigid 3-point water models

Science.gov (United States)

Izadi, Saeed; Onufriev, Alexey V.

2016-08-01

Classical 3-point rigid water models are most widely used due to their computational efficiency. Recently, we introduced a new approach to constructing classical rigid water models [S. Izadi et al., J. Phys. Chem. Lett. 5, 3863 (2014)], which permits a virtually exhaustive search for globally optimal model parameters in the sub-space that is most relevant to the electrostatic properties of the water molecule in liquid phase. Here we apply the approach to develop a 3-point Optimal Point Charge (OPC3) water model. OPC3 is significantly more accurate than the commonly used water models of same class (TIP3P and SPCE) in reproducing a comprehensive set of liquid bulk properties, over a wide range of temperatures. Beyond bulk properties, we show that OPC3 predicts the intrinsic charge hydration asymmetry (CHA) of water — a characteristic dependence of hydration free energy on the sign of the solute charge — in very close agreement with experiment. Two other recent 3-point rigid water models, TIP3PFB and H2ODC, each developed by its own, completely different optimization method, approach the global accuracy optimum represented by OPC3 in both the parameter space and accuracy of bulk properties. Thus, we argue that an accuracy limit of practical 3-point rigid non-polarizable models has effectively been reached; remaining accuracy issues are discussed.

Flexible digital x-ray technology for far-forward remote diagnostic and conformal x-ray imaging applications

Science.gov (United States)

Smith, Joseph; Marrs, Michael; Strnad, Mark; Apte, Raj B.; Bert, Julie; Allee, David; Colaneri, Nicholas; Forsythe, Eric; Morton, David

2013-05-01

Today's flat panel digital x-ray image sensors, which have been in production since the mid-1990s, are produced exclusively on glass substrates. While acceptable for use in a hospital or doctor's office, conventional glass substrate digital x-ray sensors are too fragile for use outside these controlled environments without extensive reinforcement. Reinforcement, however, significantly increases weight, bulk, and cost, making them impractical for far-forward remote diagnostic applications, which demand rugged and lightweight x-ray detectors. Additionally, glass substrate x-ray detectors are inherently rigid. This limits their use in curved or bendable, conformal x-ray imaging applications such as the non-destructive testing (NDT) of oil pipelines. However, by extending low-temperature thin-film transistor (TFT) technology previously demonstrated on plastic substrate- based electrophoretic and organic light emitting diode (OLED) flexible displays, it is now possible to manufacture durable, lightweight, as well as flexible digital x-ray detectors. In this paper, we discuss the principal technical approaches used to apply flexible display technology to two new large-area flexible digital x-ray sensors for defense, security, and industrial applications and demonstrate their imaging capabilities. Our results include a 4.8″ diagonal, 353 x 463 resolution, flexible digital x-ray detector, fabricated on a 6″ polyethylene naphthalate (PEN) plastic substrate; and a larger, 7.9″ diagonal, 720 x 640 resolution, flexible digital x-ray detector also fabricated on PEN and manufactured on a gen 2 (370 x 470 mm) substrate.

Polypyrrole/carbon nanotube nanocomposite enhanced the electrochemical capacitance of flexible graphene film for supercapacitors

Science.gov (United States)

Lu, Xiangjun; Dou, Hui; Yuan, Changzhou; Yang, Sudong; Hao, Liang; Zhang, Fang; Shen, Laifa; Zhang, Luojiang; Zhang, Xiaogang

2012-01-01

The flexible electrodes have important potential applications in energy storage of portable electronic devices for their powerful structural properties. In this work, unique flexible films with polypyrrole/carbon nanotube (PPy/CNT) composite homogeneously distributed between graphene (GN) sheets are successfully prepared by flow-assembly of the mixture dispersion of GN and PPy/CNT. In such layered structure, the coaxial PPy/CNT nanocables can not only enlarge the space between GN sheets but also provide pseudo-capacitance to enhance the total capacitance of electrodes. According to the galvanostatic charge/discharge analysis, the mass and volume specific capacitances of GN-PPy/CNT (52 wt% PPy/CNT) are 211 F g-1 and 122 F cm-3 at a current density of 0.2 A g-1, higher than those of the GN film (73 F g-1 and 79 F cm-3) and PPy/CNT (164 F g-1 and 67 F cm-3). Significantly, the GN-PPy/CNT electrode shows excellent cycling stability (5% capacity loss after 5000 cycles) due to the flexible GN layer and the rigid CNT core synergistical releasing the intrinsic differential strain of PPy chains during long-term charge/discharge cycles.

Analysis to determine the maximum dimensions of flexible apertures in sensored security netting products.

Energy Technology Data Exchange (ETDEWEB)

Murton, Mark; Bouchier, Francis A.; vanDongen, Dale T.; Mack, Thomas Kimball; Cutler, Robert P; Ross, Michael P.

2013-08-01

Although technological advances provide new capabilities to increase the robustness of security systems, they also potentially introduce new vulnerabilities. New capability sometimes requires new performance requirements. This paper outlines an approach to establishing a key performance requirement for an emerging intrusion detection sensor: the sensored net. Throughout the security industry, the commonly adopted standard for maximum opening size through barriers is a requirement based on square inchestypically 96 square inches. Unlike standard rigid opening, the dimensions of a flexible aperture are not fixed, but variable and conformable. It is demonstrably simple for a human intruder to move through a 96-square-inch opening that is conformable to the human body. The longstanding 96-square-inch requirement itself, though firmly embedded in policy and best practice, lacks a documented empirical basis. This analysis concluded that the traditional 96-square-inch standard for openings is insufficient for flexible openings that are conformable to the human body. Instead, a circumference standard is recommended for these newer types of sensored barriers. The recommended maximum circumference for a flexible opening should be no more than 26 inches, as measured on the inside of the netting material.

Verification of the Rigidity of the Coulomb Field in Motion

Science.gov (United States)

Blinov, S. V.; Bulyzhenkov, I. É.

2018-06-01

Laplace, analyzing the stability of the Solar System, was the first to calculate that the velocity of the motion of force fields can significantly exceed the velocity of light waves. In electrodynamics, the Coulomb field should rigidly accompany its source for instantaneous force action in distant regions. Such rigid motion was recently inferred from experiments at the Frascati Beam Test Facility with short beams of relativistic electrons. The comments of the authors on their observations are at odds with the comments of theoreticians on retarded potentials, which motivates a detailed study of the positions of both sides. Predictions of measurements, based on the Lienard-Wiechert potentials, are used to propose an unambiguous scheme for testing the rigidity of the Coulomb field. Realization of the proposed experimental scheme could independently refute or support the assertions of the Italian physicists regarding the rigid motion of Coulomb fields and likewise the nondual field approach to macroscopic reality.

Flexible palladium-based H2 sensor with fast response and low leakage detection by nanoimprint lithography.

Science.gov (United States)

Lim, Su Hui; Radha, Boya; Chan, Jie Yong; Saifullah, Mohammad S M; Kulkarni, Giridhar U; Ho, Ghim Wei

2013-08-14

Flexible palladium-based H2 sensors have a great potential in advanced sensing applications, as they offer advantages such as light weight, space conservation, and mechanical durability. Despite these advantages, the paucity of such sensors is due to the fact that they are difficult to fabricate while maintaining excellent sensing performance. Here, we demonstrate, using direct nanoimprint lithography of palladium, the fabrication of a flexible, durable, and fast responsive H2 sensor that is capable of detecting H2 gas concentration as low as 50 ppm. High resolution and high throughput patterning of palladium gratings over a 2 cm × 1 cm area on a rigid substrate was achieved by heat-treating nanoimprinted palladium benzyl mercaptide at 250 °C for 1 h. The flexible and robust H2 sensing device was fabricated by subsequent transfer nanoimprinting of these gratings into a polycarbonate film at its glass transition temperature. This technique produces flexible H2 sensors with improved durability, sensitivity, and response time in comparison to palladium thin films. At ambient pressure and temperature, the device showed a fast response time of 18 s at a H2 concentration of 3500 ppm. At 50 ppm concentration, the response time was found to be 57 s. The flexibility of the sensor does not appear to compromise its performance.

Financial Constraints and Nominal Price Rigidities

DEFF Research Database (Denmark)

Menno, Dominik Francesco; Balleer, Almut; Hristov, Nikolay

This paper investigates how financial market imperfections and the frequency of price adjustment interact. Based on new firm-level evidence for Germany, we document that financially constrained firms adjust prices more often than their unconstrained counterparts, both upwards and downwards. We show...... that these empirical patterns are consistent with a partial equilibrium menu-cost model with a working capital constraint. We then use the model to show how the presence of financial frictions changes profits and the price distribution of firms compared to a model without financial frictions. Our results suggest...... that tighter financial constraints are associated with higher nominal rigidities, higher prices and lower output. Moreover, in response to aggregate shocks, aggregate price rigidity moves substantially, the response of inflation is dampened, while output reacts more in the presence of financial frictions...

Molecular dynamics of CYP2D6 polymorphisms in the absence and presence of a mechanism-based inactivator reveals changes in local flexibility and dominant substrate access channels.

Directory of Open Access Journals (Sweden)

Parker W de Waal

Full Text Available Cytochrome P450 enzymes (CYPs represent an important enzyme superfamily involved in metabolism of many endogenous and exogenous small molecules. CYP2D6 is responsible for ∼ 15% of CYP-mediated drug metabolism and exhibits large phenotypic diversity within CYPs with over 100 different allelic variants. Many of these variants lead to functional changes in enzyme activity and substrate selectivity. Herein, a molecular dynamics comparative analysis of four different variants of CYP2D6 was performed. The comparative analysis included simulations with and without SCH 66712, a ligand that is also a mechanism-based inactivator, in order to investigate the possible structural basis of CYP2D6 inactivation. Analysis of protein stability highlighted significantly altered flexibility in both proximal and distal residues from the variant residues. In the absence of SCH 66712, *34, *17-2, and *17-3 displayed more flexibility than *1, and *53 displayed more rigidity. SCH 66712 binding reversed flexibility in *17-2 and *17-3, through *53 remained largely rigid. Throughout simulations with docked SCH 66712, ligand orientation within the heme-binding pocket was consistent with previously identified sites of metabolism and measured binding energies. Subsequent tunnel analysis of substrate access, egress, and solvent channels displayed varied bottle-neck radii. Taken together, our results indicate that SCH 66712 should inactivate these allelic variants, although varied flexibility and substrate binding-pocket accessibility may alter its interaction abilities.

Flexible indium-gallium-zinc-oxide Schottky diode operating beyond 2.45 GHz.

Science.gov (United States)

Zhang, Jiawei; Li, Yunpeng; Zhang, Binglei; Wang, Hanbin; Xin, Qian; Song, Aimin

2015-07-03

Mechanically flexible mobile phones have been long anticipated due to the rapid development of thin-film electronics in the last couple of decades. However, to date, no such phone has been developed, largely due to a lack of flexible electronic components that are fast enough for the required wireless communications, in particular the speed-demanding front-end rectifiers. Here Schottky diodes based on amorphous indium-gallium-zinc-oxide (IGZO) are fabricated on flexible plastic substrates. Using suitable radio-frequency mesa structures, a range of IGZO thicknesses and diode sizes have been studied. The results have revealed an unexpected dependence of the diode speed on the IGZO thickness. The findings enable the best optimized flexible diodes to reach 6.3 GHz at zero bias, which is beyond the critical benchmark speed of 2.45 GHz to satisfy the principal frequency bands of smart phones such as those for cellular communication, Bluetooth, Wi-Fi and global satellite positioning.

Rigid supersymmetry with boundaries

Energy Technology Data Exchange (ETDEWEB)

Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics

2008-01-15

We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)

Frontal Tasks and Behavior in Rigid or Tremor-Dominant Parkinson Disease.

Science.gov (United States)

Moretti, Rita; Milner, Vera; Caruso, Paola; Gazzin, Silvia; Rumiati, Raffaella

2017-08-01

Parkinson disease (PD) is not an unambiguous entity, and there is a general consensus for the statement that an akinetic-rigid dominant type of presentation has a worse prognosis, in the follow-up. The aim of our study was to examine the differences in frontal tasks and behavior, in 2 PD naive groups: the rigid and the tremor-dominant types of presentation, according to motor scores. Our study has showed some important differences in frontal tasks and in behavior, performing more apathy, aggressiveness, and irritability in the rigid type, and more depression and anxiety in the tremor-dominant type. The former group causes the caregiver more distress and has a very rapid disease progression. It can be argued that rigid type PD presentation needs specific dedicated cares and more strong clinical attention.

Non-rigid image registration using bone growth model

DEFF Research Database (Denmark)

Bro-Nielsen, Morten; Gramkow, Claus; Kreiborg, Sven

1997-01-01

Non-rigid registration has traditionally used physical models like elasticity and fluids. These models are very seldom valid models of the difference between the registered images. This paper presents a non-rigid registration algorithm, which uses a model of bone growth as a model of the change...... between time sequence images of the human mandible. By being able to register the images, this paper at the same time contributes to the validation of the growth model, which is based on the currently available medical theories and knowledge...

Inspection des pieces flexibles sans gabarit de conformation

Science.gov (United States)

Aidibe, Ali

In this thesis, we focus on the automation of the fixtureless geometric inspection of non-rigid (or compliant) parts. The primary objective of this project is to handle virtually this type of component and their point cloud, which represents a scan taken in a Free State condition, by eliminating the use of very expensive and complicated specialized fixtures posing productivity problems for manufacturing companies. This topic is a very high interest in the transport sector and, more specifically, in the aerospace one in order to significantly improve its productivity and its degree of competitiveness. The thesis is organized by articles. The study is divided over four phases. The first three phases will be represented by three journal papers and the fourth phase is presented as an appendix. The first phase of this work is intended to improve the identification module of an existing inspection mathematical tool " IDI: The Iterative Displacement Inspection " which has been developed by the research team working under the supervision of professor Tahan at ETS. The identification module aims to distinguish between defects that are due to the manufacturing process and deformations that are due to the flexibility of the part (gravity and residual stress effects). We propose to replace the original module with a new one which is based on the extreme value statistical analysis. We demonstrate that the new module remarkably reduces the type I and type II errors. In addition, unlike the identification method of the IDI, the proposed one does not require a user-specified threshold based on a trial and error process. In the second phase of this study, we propose an original approach to measure the flexibility/rigidity of the mechanical components. We introduce a factor that represents the ratio between the maximum displacement resulting from the deformation of the part and its profile tolerance and we present the results in a logarithmic scale. Three different regions were

Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

Science.gov (United States)

Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

2016-05-01

Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V-1 sec-1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

Switch loop flexibility affects substrate transport of the AcrB efflux pump

International Nuclear Information System (INIS)

Muller, Reinke T.; Travers, Timothy; Cha, Hi-jea; Phillips, Joshua L.

2017-01-01

The functionally important switch-loop of the trimeric multidrug transporter AcrB separates the access and deep drug binding pockets in every protomer. This loop, comprising 11 amino acid residues, has been shown to be crucial for substrate transport, as drugs have to travel past the loop to reach the deep binding pocket and from there are transported outside the cell via the connected AcrA and TolC channels. It contains four symmetrically arranged glycine residues suggesting that flexibility is a key feature for pump activity. Upon combinatorial substitution of these glycine residues to proline, functional and structural asymmetry was observed. Proline substitutions on the PC1 proximal side completely abolished transport and reduced backbone flexibility of the switch loop, which adopted a conformation restricting the pathway towards the deep binding pocket. Here, two phenylalanine residues located adjacent to the substitution sensitive glycine residues play a role in blocking the pathway upon rigidification of the loop, since the removal of the phenyl rings from the rigid loop restores drug transport activity.

Scaling law and enhancement of lift generation of an insect-size hovering flexible wing

Science.gov (United States)

Kang, Chang-kwon; Shyy, Wei

2013-01-01

We report a comprehensive scaling law and novel lift generation mechanisms relevant to the aerodynamic functions of structural flexibility in insect flight. Using a Navier–Stokes equation solver, fully coupled to a structural dynamics solver, we consider the hovering motion of a wing of insect size, in which the dynamics of fluid–structure interaction leads to passive wing rotation. Lift generated on the flexible wing scales with the relative shape deformation parameter, whereas the optimal lift is obtained when the wing deformation synchronizes with the imposed translation, consistent with previously reported observations for fruit flies and honeybees. Systematic comparisons with rigid wings illustrate that the nonlinear response in wing motion results in a greater peak angle compared with a simple harmonic motion, yielding higher lift. Moreover, the compliant wing streamlines its shape via camber deformation to mitigate the nonlinear lift-degrading wing–wake interaction to further enhance lift. These bioinspired aeroelastic mechanisms can be used in the development of flapping wing micro-robots. PMID:23760300

Towards Sub-Microarsecond Rigid Earth Nutation Series in the Hamiltonian Theory

National Research Council Canada - National Science Library

Souchay, Jean; Folgueira, M

2000-01-01

...) are based on the works of Kinoshita (1977) and Wahr (1979). In Kinoshita's work, the rigid Earth nutation series were calculated by the application of the Hamiltonian canonical equations to the rotation of the rigid and elliptical Earth...

Design, development, and application of precast and prestressed concrete system for rigid pavement in Indonesia

Science.gov (United States)

Nurjaman, Hari; Faizal, Lutfi; Suaryana, Nyoman; Hariandja, Binsar; Gambiro, Purnomo, Wicaksono, Siswo

2017-11-01

The performance of highways in Indonesia until today is yet to be optimum. Flexible or rigid pavement construction generally do not reach designed service lives, either due to the fact that the construction do not meet specifications or unavoidable excessive load. Precast and prestressed concrete system has been applied since 2007, but unfortunately the application has not been optimum due to the fact that the construction method is not integrally carried out. This paper deals with a construction concept that developed in 2015-2017. The concept applies green construction based on integrated manufacture industry, starting from design, construction, function, maintenance and demolition. The concept is applied on the three highway sub-layers, i.e., sub grade, sub base, and surface, and drainage system. Sub grade improvement may use soil dislocation, chemical improvement or concrete matress. Sub base material uses foam mortar, which is material easy in quality control compared to conventional materials. Pavement material uses precast and prestressed concrete components with controlled quality, quickly function as flexible pavement, and moreover, may anticipate excessive loadings. Cost estimation is carried out integrated by life cycle cost: initial investment, obstruction while construction, and maintenance cost during operation. This innovation has passed tests in technical construction method aspects as well as construction work in 2015-2017, so it is available to support infrastructure construction acceleration which achieves quality demanded to date.

Botulinum toxin in myotonia congenita: it does not help against rigidity and pain.

Science.gov (United States)

Dressler, Dirk; Adib Saberi, Fereshte

2014-05-01

Botulinum toxin (BT) is a potent local muscle relaxant with analgetic properties. Myotonia congenita (MC) is a genetic disorder producing muscle rigidity and pain. BT injected into the trapezius produced mild paresis, but no effect on rigidity and pain. There were no signs of systemic effects. Lack of BT efficacy on MC rigidity confirms its origin from muscle membrane dysfunction rather than from inappropriate neuromuscular activation. Lack of BT efficacy on pain could be caused by lack of anti-rigidity effect. It could also be due to separate non-muscular pain mechanisms unresponsive to BT.

A Markov Process Inspired Cellular Automata Model of Road Traffic

OpenAIRE

Wang, Fa; Li, Li; Hu, Jianming; Ji, Yan; Yao, Danya; Zhang, Yi; Jin, Xuexiang; Su, Yuelong; Wei, Zheng

2008-01-01

To provide a more accurate description of the driving behaviors in vehicle queues, a namely Markov-Gap cellular automata model is proposed in this paper. It views the variation of the gap between two consequent vehicles as a Markov process whose stationary distribution corresponds to the observed distribution of practical gaps. The multiformity of this Markov process provides the model enough flexibility to describe various driving behaviors. Two examples are given to show how to specialize i...

Unexpected DNA affinity and sequence selectivity through core rigidity in guanidinium-based minor groove binders.