Unseren, M.A.
1994-04-01
A general framework for solving the dynamic load distribution when two manipulators hold a rigid object is proposed. The underspecified problem of solving for the contact forces and torques based on the object`s equations of motion is transformed into a well specified problem. This is accomplished by augmenting the object`s equations of motion with additional equations which relate a new vector variable quantifying the internal contact force and torque degrees of freedom (DOF) as a linear function of the contact forces and torques. The resulting augmented system yields a well specified solution for the contact forces and torques in which they are separated into their motion inducing and internal components. A particular solution is suggested which enables the designer to conveniently specify what portion of the payload`s mass each manipulator is to bear. It is also shown that the results of the previous work are just a special case of the general load distribution framework described here.
Interactive Perception of Rigid and Non-Rigid Objects
Bryan Willimon
2012-12-01
Full Text Available This paper explores the concept of interactive perception, in which sensing guides manipulation, in the context of extracting and classifying unknown objects within a cluttered environment. In the proposed approach, a pile of objects lies on a flat background, and the goal of the robot is to isolate, interact with, and classify each object so that its properties can be obtained. The algorithm considers each object to be classified using color, shape, and flexibility. The approach works with a variety of objects relevant to service robot applications, including both rigid objects such as bottles, cans, and pliers as well as non‐rigid objects such as soft toy animals, socks, and shoes. Experiments on a number of different piles of objects demonstrate the ability of efficiently isolating and classifying each item through interaction.
Unseren, M.A.
1994-04-01
A rigid body model for the entire system which accounts for the load distribution scheme proposed in Part 1 as well as for the dynamics of the manipulators and the kinematic constraints is derived in the joint space. A technique is presented for expressing the object dynamics in terms of the joint variables of both manipulators which leads to a positive definite and symmetric inertia matrix. The model is then transformed to obtain reduced order equations of motion and a separate set of equations which govern the behavior of the internal contact forces. The control architecture is applied to the model which results in the explicit decoupling of the position and internal contact force-controlled degrees of freedom (DOF).
Non-Rigid Object Tracking by Anisotropic Kernel Mean Shift
无
2007-01-01
Mean shift, an iterative procedure that shifts each data point to the average of data points in its neighborhood, has been applied to object tracker. However, the traditional mean shift tracker by isotropic kernel often loses the object with the changing object structure in video sequences, especially when the object structure varies fast. This paper proposes a non-rigid object tracker by anisotropic kernel mean shift in which the shape, scale, and orientation of the kernels adapt to the changing object structure. The experimental results show that the new tracker is self-adaptive and approximately twice faster than the traditional tracker, which ensures the robustness and real time of tracking.
Stick it! Articulated tracking using spatial rigid object priors
Hauberg, Søren; Pedersen, Kim Steenstrup
2010-01-01
Articulated tracking of humans is a well-studied field, but most work has treated the humans as being independent of the environment. Recently, Kjellstrom et al. showed how knowledge of interaction with a known rigid object provides constraints that lower the degrees of freedom in the model. While...
Packing entropy of extended, hard, rigid objects on a lattice
Li, Wenshuo; Freed, Karl F.; Nemirovsky, Adolfo M.
1993-06-01
We present a systematic method of evaluating the packing entropy for a set of mutually avoiding extended, hard, rigid objects on a lattice. The method generalizes a simple algebraic representation of the lattice cluster theory developed by Freed and co-workers for systems composed of flexible objects. The theory provides a power series expansion in z-1 for the corrections to the zeroth order mean field approximation partition function, where z is the lattice coordination number. We illustrate the general theory by calculating the packing entropy of four-unit rigid ``square'' objects on a hypercubic lattice as a function of the volume fraction of the squares. As a particular limiting case, we also evaluate for the packing entropy of two, three, and four squares on a two-dimensional square lattice and find agreement with the cluster expansion.
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. .
Analysis and optimization of assembly variations for non-rigid parts
无
2005-01-01
Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembly deformation. The relationship between the parts' variation and the variation of the key points in final assembly for quality control is set up by calculating the spring back deformation after assembly. Moreover, the optimization method for non-rigid assembly variations based on finite element analysis is presented. The optimal objective is to reduce the manufacturing cost. The approach is implemented by using ANSYS and MATLAB. The test example shows that the proposed method is effective and applicable.
B. Sepehri
2007-06-01
Full Text Available Introduction: One of the most common syndromes in Parkinson's disease (PD is rigidity. Currently, an index is used to evaluate the level of PD by the clinical measurement of rigidity in the upper extremity. The index uses a subjective method called Unified Parkinson's Disease Rating System (UPDRS. The subjective nature of this method makes the influence of physician in the measurement of rigidity possible. Hence, the development of a new standard method based on objective indices is needed. Materials and Methods: In this research, a new device was fabricated and used to measure the viscous and elastic indices and the range of motion during passive movement of elbow joint. The relation between each index and the level of illness was analyzed. The parameters were measured on 41 patients and 11 controls. The indices were extracted using Matlab-R14 software and the statistical analysis was performed using Spss-13. Results: Although there were significant differences in both the viscous and elastic indices between the pair groups and also among the UPDRS groups, but better correlations of the viscous ones and UPDRS were found. The range of motion by itself has no good correlation with the level of the disease. Discussion and Conclusion: Based on the obtained results, it can be inferred that using viscous indices of rigidity may have an advantage over the elastic ones for the evaluation of Parkinson’s disease. Upon conducting more trials and also considering the sub indices in different parts of the range of motion, the method used here may become a standard objective method for the evaluation of Parkinson's disease.
3D Rigid-Plastic Finite Element Analysis for Skew Rolling Process of the Stepped Part
Gang FANG; Pan ZENG
2003-01-01
Based on rigid-plastic finite element method, a skew rolling process of stepped part is simulated. Considering nodesaving and effective remeshing, the tetrahedron solid elements are used to discrete workpiece. The workpiece material adopts rigid-plastic m
Real-time Animation Technique for a Kind of Non-rigid Objects
无
2003-01-01
A real-time animation technique for a kind of non-rigid objects, flexible and thin objects, is proposed, which can update with stability the state of n mass points of the mass-spring (MS) model with time complexity of O(n). The new implicit numerical integration technique of the authors, which is based on a simple approximation of the linear system, has great advantages over the existing implicit integration methods. Moreover, experiment shows that the new technique is highly efficient in animating a kind of non-rigid objects, and suitable for the draping module of the 3D garment CAD system.
Risk of perforation using rigid oesophagoscopy in the distal part of oesophagus
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....
Online learning and fusion of orientation appearance models for robust rigid object tracking
Marras, Ioannis; Alabort, Joan; Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja
2013-01-01
We present a robust framework for learning and fusing different modalities for rigid object tracking. Our method fuses data obtained from a standard visual camera and dense depth maps obtained by low-cost consumer depths cameras such as the Kinect. To combine these two completely different modalitie
Online learning and fusion of orientation appearance models for robust rigid object tracking
Marras, Ioannis; Tzimiropoulos, Georgios; Zafeiriou, Stefanos; Pantic, Maja
2014-01-01
We introduce a robust framework for learning and fusing of orientation appearance models based on both texture and depth information for rigid object tracking. Our framework fuses data obtained from a standard visual camera and dense depth maps obtained by low-cost consumer depth cameras such as the
An evaluation of a simple dynamical model for impacts between rigid objects
Molino Minero, Erik; López García, Mariano; Manuel Lázaro, Antonio; Carlosena García, Alfonso; Roset Juan, Francesc Xavier
2009-01-01
The main purpose of this work is to propose a dynamical model for simulating the response of different metallic objects when impacted by another rigid body. In addition, a methodology for estimating the model parameters is presented and discussed. Results from real experiments shows that by assuming certain characteristics on impacting objects, the dynamic model can reproduce the transient dynamics during contact time. Peer Reviewed
Parts, Cavities, and Object Representation in Infancy
Hayden, Angela; Bhatt, Ramesh S.; Kangas, Ashley; Zieber, Nicole
2011-01-01
Part representation is not only critical to object perception but also plays a key role in a number of basic visual cognition functions, such as figure-ground segregation, allocation of attention, and memory for shapes. Yet, virtually nothing is known about the development of part representation. If parts are fundamental components of object shape…
Classification of rigid and deformable objects using a novel tactile sensor
Drimus, Alin; Kootstra, Gert; Bilberg, Arne;
2011-01-01
. A real time acquisition system scans the data from the array which is then further processed. We validate the properties of the sensor in an application that classifies a number of household objects while performing a palpation procedure with a robotic gripper. Based on the haptic feedback, we classify...... various rigid and deformable objects. We represent the array of tactile images for each grasped object to a time series of features and use this as the input for a KNN classifier. Dynamic time warping is used for calculating distances between different time series of features. In the end, we compare...
Fast pixel-wise adaptive visual tracking of non-rigid objects.
Duffner, Stefan; Garcia, Christophe
2017-03-01
In this paper, we present a new algorithm for realtime single-object tracking in videos in unconstrained environments. The algorithm comprises two different components that are trained "in one shot" at the first video frame: a detector that makes use of the generalised Hough transform with colour and gradient descriptors, and a probabilistic segmentation method based on global models for foreground and background colour distributions. Both components work at pixel level and are used for tracking in a combined way adapting each other in a cotraining manner. Moreover, we propose an adaptive shape model as well as a new probabilistic method for updating the scale of the tracker. Through effective model adaptation and segmentation, the algorithm is able to track objects that undergo rigid and non-rigid deformations and considerable shape and appearance variations. The proposed tracking method has been thoroughly evaluated on challenging benchmarks, and outperforms state-ofthe- art tracking methods designed for the same task. Finally, a very efficient implementation of the proposed models allows for extremely fast tracking.
Collision detection and modeling of rigid and deformable objects in laparoscopic simulator
Dy, Mary-Clare; Tagawa, Kazuyoshi; Tanaka, Hiromi T.; Komori, Masaru
2015-03-01
Laparoscopic simulators are viable alternatives for surgical training and rehearsal. Haptic devices can also be incorporated with virtual reality simulators to provide additional cues to the users. However, to provide realistic feedback, the haptic device must be updated by 1kHz. On the other hand, realistic visual cues, that is, the collision detection and deformation between interacting objects must be rendered at least 30 fps. Our current laparoscopic simulator detects the collision between a point on the tool tip, and on the organ surfaces, in which haptic devices are attached on actual tool tips for realistic tool manipulation. The triangular-mesh organ model is rendered using a mass spring deformation model, or finite element method-based models. In this paper, we investigated multi-point-based collision detection on the rigid tool rods. Based on the preliminary results, we propose a method to improve the collision detection scheme, and speed up the organ deformation reaction. We discuss our proposal for an efficient method to compute simultaneous multiple collision between rigid (laparoscopic tools) and deformable (organs) objects, and perform the subsequent collision response, with haptic feedback, in real-time.
Vuong, Quoc C; Friedman, Alinda; Read, Jenny C A
2012-03-16
Shape and motion are two dominant cues for object recognition, but it can be difficult to investigate their relative quantitative contribution to the recognition process. In the present study, we combined shape and non-rigid motion morphing to investigate the relative contributions of both types of cues to the discrimination of dynamic objects. In Experiment 1, we validated a novel parameter-based motion morphing technique using a single-part three-dimensional object. We then combined shape morphing with the novel motion morphing technique to pairs of multipart objects to create a joint shape and motion similarity space. In Experiment 2, participants were shown pairs of morphed objects from this space and responded "same" on the basis of motion-only, shape-only, or both cues. Both cue types influenced judgments: When responding to only one cue, the other cue could be ignored, although shape cues were more difficult to ignore. When responding on the basis of both cues, there was an overall bias to weight shape cues more than motion cues. Overall, our results suggest that shape influences discrimination more than motion even when both cue types have been made quantitatively equivalent in terms of their individual discriminability.
Rens Wientjes
Full Text Available Rigid endoscopes degrade during clinical use due to sterilization, ionizing radiation and mechanical forces. Despite visual checks on functionality at the department of sterilization, surgeons are still confronted with suboptimal instruments as it is difficult to assess this degradation in an objective manner. To guarantee that endoscopes have sufficient optical quality for minimal invasive surgery, an experimental opto-electronic test bench has been developed in order to be used at the department of sterilization. Transmission of illumination fibres and lens contrast values are stored in a database to enable empirical criteria to reject endoscope for further clinical usage or to accept endoscopes after repair. Results of the test bench are given for an eight month period, where a trained operator performed 1599 measurements on 46 different types. Stability of the system, trends in quality of clinical endoscopes, and effect of repair or replacement were assessed. Although the period was too short to draw firm conclusions, a slow downwards trend in quality of clinically used endoscopes could be observed. Also, endoscopes generally improve in quality after repair or replacement, while endoscope replacement seems to slightly outperform endoscope repair. To optimize the measurement process, a new system is being developed requiring less user interaction and measuring more optical parameters of an endoscope. By commercializing this system, we hope that measurements at different hospitals will give improved insight which acceptance and rejection criteria to use and which factors (usage, cleaning protocol, and brands determine the economic lifetime of endoscopes.
Maxwell-Lorentz Dynamics for Rigid Charges - Classical Absorber Electrodynamics Part I
Bauer, G; Dürr, D
2010-01-01
This is the first part of our mathematical survey on the equations of motion of classical absorber electrodynamics, which shall be introduced and discussed briefly. Its basic equations of motion are the Maxwell-Lorentz (ML) equations of classical electrodynamics excluding the self-interaction term. We briefly explain that it is capable of describing the phenomenon of radiation reaction as well as the irreversible effect of radiation. We provide a global existence and uniqueness result for solutions to the ML equations (with as well as without self-interaction) which allows for finitely many non-rotating, rigid charges with possibly negative masses and a class of infinite energy (i.e. not square-integrable) fields. This result is the foundation of the second part (Part II) where it is applied to prove an existence theorem of the famous Wheeler-Feynman (WF) delay differential equations on finite but arbitrarily large time intervals.
Design of a flexible tactile sensor for classification of rigid and deformable objects
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...... to the resulting pressure. Based on a k-nearest neighbor classifier and using dynamic time warping to calculate the distance between different time series, the system is able to successfully classify objects. Our sensor demonstrates similar classification performance to the Weiss Robotics tactile sensor, while...
How Do Object Size and Rigidity Affect Reaching and Grasping in Infants with Down Syndrome?
de Campos, Ana Carolina; Francisco, Kelly Regina; Savelsbergh, Geert J. P.; Rocha, Nelci Adriana Cicuto Ferreira
2011-01-01
Reaching and grasping skills have been described to emerge from a dynamic interaction between intrinsic and extrinsic factors. The purpose of the present study was to investigate the interaction between such an intrinsic factor, Down syndrome, and extrinsic factors, such as different object properties. Seven infants with Down syndrome and seven…
How Do Object Size and Rigidity Affect Reaching and Grasping in Infants with Down Syndrome?
de Campos, Ana Carolina; Francisco, Kelly Regina; Savelsbergh, Geert J. P.; Rocha, Nelci Adriana Cicuto Ferreira
2011-01-01
Reaching and grasping skills have been described to emerge from a dynamic interaction between intrinsic and extrinsic factors. The purpose of the present study was to investigate the interaction between such an intrinsic factor, Down syndrome, and extrinsic factors, such as different object properties. Seven infants with Down syndrome and seven…
3D Visual Data-Driven Spatiotemporal Deformations for Non-Rigid Object Grasping Using Robot Hands.
Mateo, Carlos M; Gil, Pablo; Torres, Fernando
2016-05-05
Sensing techniques are important for solving problems of uncertainty inherent to intelligent grasping tasks. The main goal here is to present a visual sensing system based on range imaging technology for robot manipulation of non-rigid objects. Our proposal provides a suitable visual perception system of complex grasping tasks to support a robot controller when other sensor systems, such as tactile and force, are not able to obtain useful data relevant to the grasping manipulation task. In particular, a new visual approach based on RGBD data was implemented to help a robot controller carry out intelligent manipulation tasks with flexible objects. The proposed method supervises the interaction between the grasped object and the robot hand in order to avoid poor contact between the fingertips and an object when there is neither force nor pressure data. This new approach is also used to measure changes to the shape of an object's surfaces and so allows us to find deformations caused by inappropriate pressure being applied by the hand's fingers. Test was carried out for grasping tasks involving several flexible household objects with a multi-fingered robot hand working in real time. Our approach generates pulses from the deformation detection method and sends an event message to the robot controller when surface deformation is detected. In comparison with other methods, the obtained results reveal that our visual pipeline does not use deformations models of objects and materials, as well as the approach works well both planar and 3D household objects in real time. In addition, our method does not depend on the pose of the robot hand because the location of the reference system is computed from a recognition process of a pattern located place at the robot forearm. The presented experiments demonstrate that the proposed method accomplishes a good monitoring of grasping task with several objects and different grasping configurations in indoor environments.
3D Visual Data-Driven Spatiotemporal Deformations for Non-Rigid Object Grasping Using Robot Hands
Mateo, Carlos M.; Gil, Pablo; Torres, Fernando
2016-01-01
Sensing techniques are important for solving problems of uncertainty inherent to intelligent grasping tasks. The main goal here is to present a visual sensing system based on range imaging technology for robot manipulation of non-rigid objects. Our proposal provides a suitable visual perception system of complex grasping tasks to support a robot controller when other sensor systems, such as tactile and force, are not able to obtain useful data relevant to the grasping manipulation task. In particular, a new visual approach based on RGBD data was implemented to help a robot controller carry out intelligent manipulation tasks with flexible objects. The proposed method supervises the interaction between the grasped object and the robot hand in order to avoid poor contact between the fingertips and an object when there is neither force nor pressure data. This new approach is also used to measure changes to the shape of an object’s surfaces and so allows us to find deformations caused by inappropriate pressure being applied by the hand’s fingers. Test was carried out for grasping tasks involving several flexible household objects with a multi-fingered robot hand working in real time. Our approach generates pulses from the deformation detection method and sends an event message to the robot controller when surface deformation is detected. In comparison with other methods, the obtained results reveal that our visual pipeline does not use deformations models of objects and materials, as well as the approach works well both planar and 3D household objects in real time. In addition, our method does not depend on the pose of the robot hand because the location of the reference system is computed from a recognition process of a pattern located place at the robot forearm. The presented experiments demonstrate that the proposed method accomplishes a good monitoring of grasping task with several objects and different grasping configurations in indoor environments. PMID
3D Visual Data-Driven Spatiotemporal Deformations for Non-Rigid Object Grasping Using Robot Hands
Carlos M. Mateo
2016-05-01
Full Text Available Sensing techniques are important for solving problems of uncertainty inherent to intelligent grasping tasks. The main goal here is to present a visual sensing system based on range imaging technology for robot manipulation of non-rigid objects. Our proposal provides a suitable visual perception system of complex grasping tasks to support a robot controller when other sensor systems, such as tactile and force, are not able to obtain useful data relevant to the grasping manipulation task. In particular, a new visual approach based on RGBD data was implemented to help a robot controller carry out intelligent manipulation tasks with flexible objects. The proposed method supervises the interaction between the grasped object and the robot hand in order to avoid poor contact between the fingertips and an object when there is neither force nor pressure data. This new approach is also used to measure changes to the shape of an object’s surfaces and so allows us to find deformations caused by inappropriate pressure being applied by the hand’s fingers. Test was carried out for grasping tasks involving several flexible household objects with a multi-fingered robot hand working in real time. Our approach generates pulses from the deformation detection method and sends an event message to the robot controller when surface deformation is detected. In comparison with other methods, the obtained results reveal that our visual pipeline does not use deformations models of objects and materials, as well as the approach works well both planar and 3D household objects in real time. In addition, our method does not depend on the pose of the robot hand because the location of the reference system is computed from a recognition process of a pattern located place at the robot forearm. The presented experiments demonstrate that the proposed method accomplishes a good monitoring of grasping task with several objects and different grasping configurations in indoor
Robust 3D Object Tracking from Monocular Images using Stable Parts.
Crivellaro, Alberto; Rad, Mahdi; Verdie, Yannick; Yi, Kwang Moo; Fua, Pascal; Lepetit, Vincent
2017-05-26
We present an algorithm for estimating the pose of a rigid object in real-time under challenging conditions. Our method effectively handles poorly textured objects in cluttered, changing environments, even when their appearance is corrupted by large occlusions, and it relies on grayscale images to handle metallic environments on which depth cameras would fail. As a result, our method is suitable for practical Augmented Reality applications including industrial environments. At the core of our approach is a novel representation for the 3D pose of object parts: We predict the 3D pose of each part in the form of the 2D projections of a few control points. The advantages of this representation is three-fold: We can predict the 3D pose of the object even when only one part is visible; when several parts are visible, we can easily combine them to compute a better pose of the object; the 3D pose we obtain is usually very accurate, even when only few parts are visible. We show how to use this representation in a robust 3D tracking framework. In addition to extensive comparisons with the state-of-the-art, we demonstrate our method on a practical Augmented Reality application for maintenance assistance in the ATLAS particle detector at CERN.
Mitchell, Robert W.; Clark, Heather
2015-01-01
Young children asked to pretend to use a series of absent objects typically pantomime by using a body part as the object (BPO) rather than by acting as if using an imaginary object (IO). This replication of Lyons's work (1983, 1986) examines whether different pretend contexts when requesting pantomimes influence children's use of IO and BPO…
Pösch, Andreas; Schlobohm, Jochen; Matthias, Steffen; Reithmeier, Eduard
2017-02-01
Routine maintenance is mandatory for safe and efficient operation of complex machines, such as airplane turbines. Occasional special events, like bird strike, entail extraordinary inspection works. Hereby, inside machine parts are hard to reach, oftentimes occluded by other parts and not directly accessible for visual inspection. Disassembly of machine parts is time-consuming and expensive and, therefore undesired. This leaves distal imaging, i.e. endoscopy, to be the only practical option for defect detection. Ordinary endoscopes, which provide two dimensional intensity image data, are insufficient to fully assess the risks caused by small three dimensional defects. As a solution to this issue, we have developed and implemented two different systems for three dimensional endoscopic measurement based on structured light projection which are capable of recording high resolution and high accuracy point cloud data. A measurement standard deviation of roughly 20 μm is achieved within a field of measurement of 20 × 30 × 30mm3 .
Visual object agnosia as a problem in integrating parts and part relations.
Saumier, Daniel; Arguin, Martin; Lefebvre, Christine; Lassonde, Maryse
2002-01-01
Current models of vision generally assume that the recognition of visual objects is achieved by encoding their component parts, as well as the spatial relations among parts. The current study examined how the processing of parts and their configurations may be affected in visual agnosia due to brain damage. Both a visual agnosic patient (AR) and healthy control subjects performed a visual search task in which they had to discriminate between targets and distractors that varied according to whether they shared their parts and/or their configuration. The results show that AR's visual search rates are disproportionally slow when targets and distractors share the same configuration than when they have different configurations. AR is also found to be disproportionately slow in discriminating targets and distractors that share identical parts when the targets and distractors share the same configuration. With differently configured targets and distractors, AR shows no part sharing effect. For controls, in contrast, the part and configuration sharing effects occur independently of one another. It is concluded that AR's object recognition deficit arises from difficulties in discriminating objects that share their configuration, and from an abnormal dependency of part information processing upon object configuration.
Wheeler-Feynman Equations for Rigid Charges - Classical Absorber Electrodynamics Part II
Bauer, G; Dürr, D
2010-01-01
This is the second part of our mathematical survey on the equations of motion of classical absorber electrodynamics. Here we study the equations of Wheeler-Feynman (WF) electrodynamics, which describe the interaction of finitely many charges by both the advanced and retarded Li\\'enard-Wiechert fields. These equations are non-linear and involve retarded as well as advanced arguments and belong to the class of delay (or functional) differential equations. Such delayed arguments do not permit a direct application of standard PDE techniques. We introduce a general strategy to handle existence and uniqueness questions for such functional differential equations. We observe that any WF solution gives rise to a solution to the Maxwell-Lorentz equations without self-interaction (ML-SI), which are a set of non-linear PDEs without delay that have been studied in Part I. In other words, WF solutions are special solutions among all solutions of the ML-SI equations. Hence, WF solutions arise as solutions to the ML-SI equat...
MODELING OF CONVECTIVE STREAMS IN PNEUMOBASIC OBJECTS (Part 2
B. M. Khroustalev
2015-01-01
Full Text Available The article presents modeling for investigation of aerodynamic processes on area sections (including a group of complex constructional works for different regimes of drop and wind streams and temperature conditions and in complex constructional works (for different regimes of heating and ventilation. There were developed different programs for innovation problems solution in the field of heat and mass exchange in three-dimensional space of pres- sures-speeds-temperatures of оbjects.The field of uses of pneumobasic objects: construction and roof of tennis courts, hockey pitches, swimming pools , and also exhibitions’ buildings, circus buildings, cafes, aqua parks, studios, mobile objects of medical purposes, hangars, garages, construction sites, service sta- tions and etc. Advantages of such objects are the possibility and simplicity of multiple instal- lation and demolition works. Their large-scale implementation is determined by temperature- moisture conditions under the shells.Analytical and calculating researches, real researches of thermodynamic parameters of heat and mass exchange, multifactorial processes of air in pneumobasic objects, their shells in a wide range of climatic parameters of air (January – December in the Republic of Belarus, in many geographical latitudes of many countries have shown that the limit of the possibility of optimizing wind loads, heat flow, acoustic effects is infinite (sports, residential, industrial, warehouse, the military-technical units (tanks, airplanes, etc.. In modeling of convective flows in pneumobasic objects (part 1 there are processes with higher dynamic parameters of the air flow for the characteristic pneumobasic object, carried out the calculation of the velocity field, temperature, pressure at the speed of access of air through the inflow holes up to 5 m/sec at the moments of times (20, 100, 200, 400 sec. The calculation was performed using the developed mathematical
Unseren, M.A.
1997-04-20
The paper reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restrict the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.
Near real-time measurement of forces applied by an optical trap to a rigid cylindrical object
Glaser, Joseph; Hoeprich, David; Resnick, Andrew
2014-07-01
An automated data acquisition and processing system is established to measure the force applied by an optical trap to an object of unknown composition in real time. Optical traps have been in use for the past 40 years to manipulate microscopic particles, but the magnitude of applied force is often unknown and requires extensive instrument characterization. Measuring or calculating the force applied by an optical trap to nonspherical particles presents additional difficulties which are also overcome with our system. Extensive experiments and measurements using well-characterized objects were performed to verify the system performance.
Rigid-Plastic Post-Buckling Analysis of Columns and Quadratic Plates
Jönsson, Jeppe
2008-01-01
The objective of this paper is to show the application of a novel approach to the rigid plastic hinge and yield line theory in post-buckling analysis of slender plates and columns. The upper bound theorem of plasticity theory and the associated flow law of plasticity are used to find...... of the post-buckling behaviour. The rigid plastic theory of plates, referred to as yield line theory, involves large rigid parts of the plate mutually rotating about yielding hinge lines, however in order to accommodate in plane plastic deformations area “collapse” yield lines have been introduced. The hinge...... 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...
Objective assessment of mammography systems. Part I. Method
Hessler, C.; Depeursinge, C.; Grecescu, M.; Pochon, Y.; Raimondi, S.; Valley, J.F.
1985-07-01
The authors have developed an experimental method for simultaneous determination of dose and image parameters in mammography. A global and objective quality concept, the image quality index, is proposed and its reliability demonstrated by tests of reproducibility. Objective quality tests and subjective evaluation by radiologists showed good correlation.
Brandes, Susanne; Mokhtari, Zeinab; Essig, Fabian; Hünniger, Kerstin; Kurzai, Oliver; Figge, Marc Thilo
2015-02-01
Time-lapse microscopy is an important technique to study the dynamics of various biological processes. The labor-intensive manual analysis of microscopy videos is increasingly replaced by automated segmentation and tracking methods. These methods are often limited to certain cell morphologies and/or cell stainings. In this paper, we present an automated segmentation and tracking framework that does not have these restrictions. In particular, our framework handles highly variable cell shapes and does not rely on any cell stainings. Our segmentation approach is based on a combination of spatial and temporal image variations to detect moving cells in microscopy videos. This method yields a sensitivity of 99% and a precision of 95% in object detection. The tracking of cells consists of different steps, starting from single-cell tracking based on a nearest-neighbor-approach, detection of cell-cell interactions and splitting of cell clusters, and finally combining tracklets using methods from graph theory. The segmentation and tracking framework was applied to synthetic as well as experimental datasets with varying cell densities implying different numbers of cell-cell interactions. We established a validation framework to measure the performance of our tracking technique. The cell tracking accuracy was found to be >99% for all datasets indicating a high accuracy for connecting the detected cells between different time points.
Corso, Francesco Dal; Bigoni, Davide
2016-01-01
An infinite class of nonuniform antiplane shear fields is considered for a linear elastic isotropic space and (non-intersecting) isotoxal star-shaped polygonal voids and rigid inclusions perturbing these fields are solved. Through the use of the complex potential technique together with the generalized binomial and the multinomial theorems, full-field closed-form solutions are obtained in the conformal plane. The particular (and important) cases of star-shaped cracks and rigid-line inclusions (stiffeners) are also derived. Except for special cases (addressed in Part II), the obtained solutions show singularities at the inclusion corners and at the crack and stiffener ends, where the stress blows-up to infinity, and is therefore detrimental to strength. It is for this reason that the closed-form determination of the stress field near a sharp inclusion or void is crucial for the design of ultra-resistant composites.
Objective assessment of mammography systems. Part II. Implementation
Hessler, C.; Depeursinge, C.; Grecescu, M.; Pochon, Y.; Raimondi, S.; Valley, J.F.
1985-07-01
A quality control program for mammography units was carried out, based on objective tests of image quality and dose. Results are reported for 31 units, including correlation between various parameters. Satisfactory results were obtained in the case of 21 installations; for the other 10, comparison between measured quality parameters and those of the reference system suggested ways in which quality might be improved.
Food safety objective: an integral part of food chain management
Gorris, L.G.M.
2005-01-01
The concept of food safety objective has been proposed to provide a target for operational food safety management, leaving flexibility in the way equivalent food safety levels are achieved by different food chains. The concept helps to better relate operational food safety management to public
Food safety objective: an integral part of food chain management
Gorris, L.G.M.
2005-01-01
The concept of food safety objective has been proposed to provide a target for operational food safety management, leaving flexibility in the way equivalent food safety levels are achieved by different food chains. The concept helps to better relate operational food safety management to public healt
Sequencing of contents and learning objects - part II
Miguel Zapata Ros
2006-01-01
Full Text Available Esta es la segunda parte del artículo del mismo nombre publicado en el número anterior de RED. En él planteamos una visión de la selección y de la secuenciación de contenidos de enseñanza, en el contexto de la planificación curricular, desde la perspectiva de las corrientes del pensamiento constructivista. Señalamos la importancia de contar, en el campo de la formación apoyada en redes, con herramientas y criterios autónomos que guíen este proceso desde unas bases propias, externas y con preeminencia sobre las que derivan de la configuración de las herramientas tecnológicas, y desde la necesidad de contar con estándares de formato de intercambio de datos Si en general este planteamiento es importante adquiere especial relevancia en el contexto del e-learning de propósito general, tanto en el de formación como en el e-learning empresarial o en el universitario. Y por supuesto en el contexto de la formación reglada y de formación informal, o de la no reglada. También señalamos las necesidades que plantea la industria del e-learning en la actualidad en relación con el diseño instruccional de objetos de aprendizaje, necesidades que constituyen una prioridad y un desafío. En la primera parte desarrollamos la perspectiva constructivista y la conceptualización de servicios y herramientas tecnológicas como recursos educativos, así como una revisión de los conceptos vinculados con el e-learning, objetos de aprendizaje, OAR y reusabilidad. En esta parte abordaremos la fundamentación de las teorías que rigen los procedimientos de selección de contenidos, los presupuestos básicos y la descripción de las técnicas de secuenciación. En particular nos centraremos en tres de ellas: La técnica de análisis de contenidos, la técnica de análisis de la tarea y la Teoría de la Elaboración. Por último como conclusión, en la tercera parte, intentaremos abordar, no en su resolución sino solo en su propuesta como enunciado
MODELING OF CONVECTIVE FLOWS IN PNEUMOBASED OBJECTS. Part 1
B. M. Khrustalyov
2014-01-01
Full Text Available A computer modeling process of three-dimensional forced convection proceeding from computation of thermodynamic parameters of pneumo basic buildings (pneumo supported structures is presented. The mathematical model of numerical computation method of temperature and velocity fields, pressure profile in the object is developed using the package Solid works and is provided by grid methods on specified software. Special Navier–Stokes, Clapeyron–Mendeleev, continuity and thermal-conductivity equations are used to calculate parameters in the building with four supply and exhaust channels. Differential equations are presented by algebraic equation systems, initial-boundary conditions are changed by differential conditions for mesh functions and their solutions are performed by algebraic operations. In this article the following is demonstrated: in pneumo basic buildings convective and heat flows are identical structures near the surfaces in unlimited space, but in single-multiply shells (envelopescirculation lines take place, geometrical sizes of which depend on thermal-physical characteristics of gas(airin envelopes, radiation reaction with heated surfaces of envelopes with sphere, earth surface, neighboring buildings. Natural surveys of pneumo-basic buildings of different purposes were carried out in Minsk, in different cities of Belarus and Russia, including temperature fields of external and internal surfaces of air envelopes, relative humidity, thermal (heatflows, radiation characteristics and others.The results of research work are illustrated with diagrams of temperature, velocity, density and pressure dependent on coordinates and time.
A pinned or free-floating plate on a thin viscous film. Part 1: A rigid plate
Trinh, Philippe H; Stone, Howard A
2013-01-01
We investigate a pinned or free-floating rigid plate lying on the free surface of a thin film of viscous fluid, which itself lies on top of a horizontal substrate that is moving to the right at a constant speed. Examples of situations in which this can occur include blade coating and the motion of a contact lens on the tear film of the eye after a blink. In contrast to the extensive previous work on fixed and clamped plates, in the present work we allow the plate to change both its position and orientation in response to the flow. Asymptotic and numerical analyses are described, and, in particular, we explain, in appropriate dimensionless terms, the role of the speed of the substrate, surface tension, viscosity and, in the case of a pinned plate, the prescribed pressure in the reservoir of fluid upstream of the plate, in determining the possible equilibrium configurations.
Taylor, Michael C; Laber, Terry L; Kish, Paul E; Owens, Glynn; Osborne, Nikola K P
2016-07-01
This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non-absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed.
Corso, Francesco Dal; Bigoni, Davide
2016-01-01
Notch stress intensity factors and stress intensity factors are obtained analytically for isotoxal star-shaped polygonal voids and rigid inclusions (and also for the corresponding limit cases of star-shaped cracks and stiffeners), when loaded through remote inhomogeneous (self-equilibrated, polynomial) antiplane shear stress in an infinite linear elastic matrix. Usually these solutions show stress singularities at the inclusion corners. It is shown that an infinite set of geometries and loading conditions exist for which not only the singularity is absent, but the stress vanishes ('annihilates') at the corners. Thus the material, which even without the inclusion corners would have a finite stress, remains unstressed at these points in spite of the applied remote load. Moreover, similar conditions are determined in which a star-shaped crack or stiffener leaves the ambient stress completely unperturbed, thus reaching a condition of 'quasi-static invisibility'. Stress annihilation and invisibility define optimal...
Musioł, Marta; Sikorska, Wanda; Adamus, Grazyna; Janeczek, Henryk; Richert, Jozef; Malinowski, Rafal; Jiang, Guozhan; Kowalczuk, Marek
2016-06-01
This paper presents a forensic engineering study on the biodegradation behaviour of prototype packaging thermoformed from PLA-extruded film and plain PLA film under industrial composting conditions. Hydrolytic degradation in water was conducted for reference. The effects of composting duration on changes in molar mass, glass transition temperature and degree of crystallinity of the polymeric material were monitored using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The chemical structure of water soluble degradation products of the polymeric material was determined using nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS). The results show that the biodegradation process is less dependent on the thermoforming process of PLA and more dependent on the composting/degradation conditions that are applied. The increase in the dispersity index, leading to the bimodal molar mass distribution profile, suggests an autocatalytic hydrolysis effect at the early stage of the composting process, during which the bulk hydrolysis mechanism dominantly operates. Both the prototype PLA-packaging and PLA rigid film samples were shown to have a gradual increase in opacity due to an increase in the degree of crystallinity. Copyright © 2016 Elsevier Ltd. All rights reserved.
Pål Johan From
2012-04-01
Full Text Available This paper presents the explicit dynamic equations of a mechanical system. The equations are presented so that they can easily be implemented in a simulation software or controller environment and are also well suited for system and controller analysis. The dynamics of a general mechanical system consisting of one or more rigid bodies can be derived from the Lagrangian. We can then use several well known properties of Lie groups to guarantee that these equations are well defined. This will, however, often lead to rather abstract formulation of the dynamic equations that cannot be implemented in a simulation software directly. In this paper we close this gap and show what the explicit dynamic equations look like. These equations can then be implemented directly in a simulation software and no background knowledge on Lie theory and differential geometry on the practitioner's side is required. This is the first of two papers on this topic. In this paper we derive the dynamics for single rigid bodies, while in the second part we study multibody systems. In addition to making the equations more accessible to practitioners, a motivation behind the papers is to correct a few errors commonly found in literature. For the first time, we show the detailed derivations and how to arrive at the correct set of equations. We also show through some simple examples that these correspond with the classical formulations found from Lagrange's equations. The dynamics is derived from the Boltzmann--Hamel equations of motion in terms of local position and velocity variables and the mapping to the corresponding quasi-velocities. Finally we present a new theorem which states that the Boltzmann--Hamel formulation of the dynamics is valid for all transformations with a Lie group topology. This has previously only been indicated through examples, but here we also present the formal proof. The main motivation of these papers is to allow practitioners not familiar with
窗口自适应更新的柔性目标视频跟踪%Visual Tracking with Window Updating of Non-rigid Object
李翠君; 王成儒
2012-01-01
运动人体目标的跟踪一直是视频监控中研究的重点.本文主要侧重柔性目标变形的方面,以HSI颜色模型进行模板的学习,在当前帧中得到模板,并且统计每一帧图像的信息量,然后在一下帧中进行Kalman预测.将预测到的区域与模板比较判断之后再决定是否更新模板,减少了一定的计算量,为了约束窗口的变化,引入信息量的概念,信息量由HSI颜色空间的I的特征点计算得到.这样,一直更新模板和窗口直至准确有效地跟踪人体目标.实验表明,在人体发生较大形变的过程中,会持续的跟踪人体,不会发生跟踪丢失的问题.%The human tracking is the key in the video surveillance. This text focuses on non-rigid objects, learning based on the HSI color model template. Each pixel of the template is modeled using two components with H and S. Get template from the current frame, statistic the information of every frame, and predict in the next frame using Kalman filter. Decide whether to update the template after comparing the forecast region and the template, reducing the amount of calculation. And for restraining the tracking window, information which is calculated from the color I is introduced. After that, the template and the window will be updated. The experimental results show that the proposed method achieves continuously tracking, and resolve the problem with the object disappeared.
Late development of metric part-relational processing in object recognition.
Jüttner, Martin; Petters, Dean; Wakui, Elley; Davidoff, Jules
2014-08-01
Four experiments with unfamiliar objects examined the remarkably late consolidation of part-relational relative to part-based object recognition (Jüttner, Wakui, Petters, Kaur, & Davidoff, 2013). Our results indicate a particularly protracted developmental trajectory for the processing of metric part relations. Schoolchildren aged 7 to 14 years and adults were tested in 3-Alternative-Forced-Choice tasks to judge the correct appearance of upright and inverted newly learned multipart objects that had been manipulated in terms of individual parts or part relations. Experiment 1 showed that even the youngest tested children were close to adult levels of performance for recognizing categorical changes of individual parts and relative part position. By contrast, Experiment 2 demonstrated that performance for detecting metric changes of relative part position was distinctly reduced in young children compared with recognizing metric changes of individual parts, and did not approach the latter until 11 to 12 years. A similar developmental dissociation was observed in Experiment 3, which contrasted the detection of metric relative-size changes and metric part changes. Experiment 4 showed that manipulations of metric size that were perceived as part (rather than part-relational) changes eliminated this dissociation. Implications for theories of object recognition and similarities to the development of face perception are discussed.
The Bouma law of crowding, revised: critical spacing is equal across parts, not objects.
Rosen, Sarah; Chakravarthi, Ramakrishna; Pelli, Denis G
2014-12-10
Crowding is the inability to identify an object among flankers in the periphery. It is due to inappropriate incorporation of features from flanking objects in perception of the target. Crowding is characterized by measuring critical spacing, the minimum distance needed between a target and flankers to allow recognition. The existing Bouma law states that, at a given point and direction in the visual field, critical spacing, measured from the center of a target object to the center of a similar flanking object, is the same for all objects (Pelli & Tillman, 2008). Because flipping an object about its center preserves its center-to-center spacing to other objects, according to the Bouma law, crowding should be unaffected. However, because crowding is a result of feature combination, the location of features within an object might matter. In a series of experiments, we find that critical spacing is affected by the location of features within the flanker. For some flankers, a flip greatly reduces crowding even though it maintains target-flanker spacing and similarity. Our results suggest that the existing Bouma law applies to simple one-part objects, such as a single roman letter or a Gabor patch. Many objects consist of multiple parts; for example, a word is composed of multiple letters that crowd each other. To cope with such complex objects, we revise the Bouma law to say that critical spacing is equal across parts, rather than objects. This accounts for old and new findings.
Bautista-Rodriquez, C.M.; Rosas-Paleta, M.G.A.; Tapia-Pachuca, A.B. [Alter Energias Group, Puebla (Mexico); Rivera-Marquez, J.A. [Benemerita Univ. Autonoma de Puebla, Puebla (Mexico). Faculty of Chemical Engineering; Garcia de la Vega, J.R. [Uhde Engineering de Mexico, Mexico City (Mexico)
2010-07-15
During the operation of a proton exchange membrane fuel cell (PEMFC), several mass transport phenomena develop, generating a mechanical-physics resistance to some extent, implying limitations during operation. In a conventional fuel cell, the feeding reactive gases to the sites of reaction are performed by a series of elements, such as channels in the polar plates, diffusion layer on the electrodes and the active layer where it realizes the electrochemical semi reaction. Previous studies have reported and demonstrated the generation of gradients of concentration in reagents between the channels of distribution and diffusion layer, representing a limiting in the transport of reagents to the active sites as well as resistance to the mass transport of reagents as a result of the presence of water product in the pores of electrodes. This paper focused on lowering the resistance to mass transport by applying a rigid gas diffusion media with many macropores as distributor of reagents. The objective was to encourage the mass transport phenomena to the active sites on the electrodes. This paper described the experiment and presented the results of the study. The experiment involved the application of a rigid gas diffusion media as a reagents distributor with a serpentine channel distributor, both manufactured with mixes of carbon and graphite powder. The study showed that in general, the GDMR became a diffusion layer, integrating a composite electrode with the graphitized paper and catalyst coated membrane assembly. Under conditions of variable cathodic pressure, the response of the GDMR became a combined distribution plate (conductive and diffusion mass transport), favouring the increase in current density and power developed by the PEMFC in pressure function. 33 refs., 2 tabs., 14 figs.
Developmental Trajectories of Part-Based and Configural Object Recognition in Adolescence
Juttner, Martin; Wakui, Elley; Petters, Dean; Kaur, Surinder; Davidoff, Jules
2013-01-01
Three experiments assessed the development of children's part and configural (part-relational) processing in object recognition during adolescence. In total, 312 school children aged 7-16 years and 80 adults were tested in 3-alternative forced choice (3-AFC) tasks. They judged the correct appearance of upright and inverted presented familiar…
Whole versus Part Presentations of the Interactive 3D Graphics Learning Objects
Azmy, Nabil Gad; Ismaeel, Dina Ahmed
2010-01-01
The purpose of this study is to present an analysis of how the structure and design of the Interactive 3D Graphics Learning Objects can be effective and efficient in terms of Performance, Time on task, and Learning Efficiency. The study explored two treatments, namely whole versus Part Presentations of the Interactive 3D Graphics Learning Objects,…
NACF Rocha
2006-09-01
Full Text Available CONTEXTUALIZAÇÃO: Estudos têm identificado que as propriedades dos objetos induzem os ajustes no alcance; no entanto, poucos investigaram a influência específica do tamanho e rigidez dos objetos em lactentes jovens. OBJETIVO: Verificar se lactentes de 4 a 6 meses realizam ajustes proximais e distais ao alcançarem objetos de diferentes tamanhos e rigidez. MÉTODOS: Nove lactentes saudáveis foram posicionados em uma cadeira inclinada a 50º. Quatro objetos foram apresentados, um rígido grande (RG, um rígido pequeno (RP, um maleável grande (MG e um maleável pequeno (MP, por um período de 1 minuto cada. Em um total de 384 alcances, foram analisados os ajustes proximais (alcance uni e bimanual e distais (orientação da mão horizontal, vertical e oblíqua; mão aberta, fechada e semi-aberta e o sucesso do alcance dos objetos. RESULTADOS: Constatou-se ajuste bimanual para o objeto RG e unimanual para os demais. A orientação da mão oblíqua foi predominante no toque dos objetos, enquanto para a preensão dos mesmos, a predominância foi a vertical, principalmente para o objeto RG. A orientação horizontal não foi observada na preensão do objeto RG. A mão semi-aberta foi mais freqüente no início do alcance para todos os objetos, enquanto no toque do objeto RG a mão aberta foi predominante. O sucesso do alcance foi maior para os objetos maleáveis (MG, MP do que para os rígidos (RG e RP. CONCLUSÃO: Lactentes jovens estudados são capazes de planejar e ajustar seus movimentos baseados na percepção das propriedades físicas dos objetos, o que sugere interação percepção-ação.BACKGROUND: Studies have identified that object properties lead to adjustments to reaching. However, few have investigated the specific influence of object size and rigidity among young infants. OBJECTIVE: To verify whether four to six-month-old infants make proximal and distal adjustments when reaching for objects of different sizes and rigidity. METHOD
Unseren, M.A.
1997-09-01
The report reviews a method for modeling and controlling two serial link manipulators which mutually lift and transport a rigid body object in a three dimensional workspace. A new vector variable is introduced which parameterizes the internal contact force controlled degrees of freedom. A technique for dynamically distributing the payload between the manipulators is suggested which yields a family of solutions for the contact forces and torques the manipulators impart to the object. A set of rigid body kinematic constraints which restricts the values of the joint velocities of both manipulators is derived. A rigid body dynamical model for the closed chain system is first developed in the joint space. The model is obtained by generalizing the previous methods for deriving the model. The joint velocity and acceleration variables in the model are expressed in terms of independent pseudovariables. The pseudospace model is transformed to obtain reduced order equations of motion and a separate set of equations governing the internal components of the contact forces and torques. A theoretic control architecture is suggested which explicitly decouples the two sets of equations comprising the model. The controller enables the designer to develop independent, non-interacting control laws for the position control and internal force control of the system.
Contextual Hierarchical Part-Driven Conditional Random Field Model for Object Category Detection
Lizhen Wu
2012-01-01
Full Text Available Even though several promising approaches have been proposed in the literature, generic category-level object detection is still challenging due to high intraclass variability and ambiguity in the appearance among different object instances. From the view of constructing object models, the balance between flexibility and discrimination must be taken into consideration. Motivated by these demands, we propose a novel contextual hierarchical part-driven conditional random field (CRF model, which is based on not only individual object part appearance but also model contextual interactions of the parts simultaneously. By using a latent two-layer hierarchical formulation of labels and a weighted neighborhood structure, the model can effectively encode the dependencies among object parts. Meanwhile, beta-stable local features are introduced as observed data to ensure the discriminative and robustness of part description. The object category detection problem can be solved in a probabilistic framework using a supervised learning method based on maximum a posteriori (MAP estimation. The benefits of the proposed model are demonstrated on the standard dataset and satellite images.
Impairments in part-whole representations of objects in two cases of integrative visual agnosia.
Behrmann, Marlene; Williams, Pepper
2007-10-01
How complex multipart visual objects are represented perceptually remains a subject of ongoing investigation. One source of evidence that has been used to shed light on this issue comes from the study of individuals who fail to integrate disparate parts of visual objects. This study reports a series of experiments that examine the ability of two such patients with this form of agnosia (integrative agnosia; IA), S.M. and C.R., to discriminate and categorize exemplars of a rich set of novel objects, "Fribbles", whose visual similarity (number of shared parts) and category membership (shared overall shape) can be manipulated. Both patients performed increasingly poorly as the number of parts required for differentiating one Fribble from another increased. Both patients were also impaired at determining when two Fribbles belonged in the same category, a process that relies on abstracting spatial relations between parts. C.R., the less impaired of the two, but not S.M., eventually learned to categorize the Fribbles but required substantially more training than normal perceivers. S.M.'s failure is not attributable to a problem in learning to use a label for identification nor is it obviously attributable to a visual memory deficit. Rather, the findings indicate that, although the patients may be able to represent a small number of parts independently, in order to represent multipart images, the parts need to be integrated or chunked into a coherent whole. It is this integrative process that is impaired in IA and appears to play a critical role in the normal object recognition of complex images.
An objective signature for visual binding of face parts in the human brain.
Boremanse, Adriano; Norcia, Anthony M; Rossion, Bruno
2013-09-10
Whether and how the parts of a visual object are grouped together to form an integrated ("holistic") representation is a central question in cognitive neuroscience. Although the face is considered to be the quintessential example of holistic representation, this issue has been the subject of much debate in face perception research. The implication of holistic processing is that the response to the whole cannot be predicted from the sum of responses to the parts. Here we apply techniques from nonlinear systems analysis to provide an objective measure of the nonlinear integration of parts into a whole, using the left and right halves of a face stimulus as the parts. High-density electroencephalogram (EEG) was recorded in 15 human participants presented with two halves of a face stimulus, flickering at different frequencies (5.88 vs. 7.14 Hz). Besides specific responses at these fundamental frequencies, reflecting part-based responses, we found intermodulation components (e.g., 7.14 - 5.88 = 1.26 Hz) over the right occipito-temporal hemisphere, reflecting nonlinear integration of the face halves. Part-based responses did not depend on the relative alignment of the two face halves, their spatial separation, or whether the face was presented upright or inverted. By contrast, intermodulations were virtually absent when the two halves were spatially misaligned and separated. Inversion of the whole face configuration also reduced specifically the intermodulation components over the right occipito-temporal cortex. These observations indicate that the intermodulation components constitute an objective, configuration-specific signature of an emergent neural representation of the whole face that is distinct from that generated by the parts themselves.
康山林
2001-01-01
A generalized form of perpendicular axe theorem about moment of inertia, which canbe applicable to solid objects in three - dimension space, is proposed in this paper. It is very simple and convenient to calculate, with the generalized form of perpendicular axe theorem, moment of inertia of rigid objects that the mass distribution is symmetry.%本文给出计算刚体转动惯量的垂直轴定理的一种推广形式，可适用于三维的立体刚体；在刚体的质量分布具有一定的对称性的情况下计算刚体转动惯量十分方便。
Gortler, Steven J; Liu, Ligang; Thurston, Dylan P
2010-01-01
We study the properties of affine rigidity of a hypergraph and prove a variety of fundamental results. First, we show that affine rigidity is a generic property (i.e., depends only on the hypergraph, not the particular embedding). Then we prove that a graph is generically neighborhood affinely rigid in d-dimensional space if it is (d+1)-vertex-connected. We also show neighborhood affine rigidity of a graph implies universal rigidity of its squared graph. Our results, and affine rigidity more generally, have natural applications in point registration and localization, as well as connections to manifold learning.
Steven J. Gortler
2013-12-01
Full Text Available We study the properties of affine rigidity of a hypergraph and prove a variety of fundamental results. First, we show that affine rigidity is a generic property (i.e., depends only on the hypergraph, not the particular embedding. Then we prove that a graph is generically neighborhood affinely rigid in d-dimensional space if it is (d+1-vertex-connected. We also show neighborhood affine rigidity of a graph implies universal rigidity of its squared graph. Our results, and affine rigidity more generally, have natural applications in point registration and localization, as well as connections to manifold learning.
Rijkhoff, Jan
2010-01-01
This article argues that in addition to the major flexible lexical categories in Hengeveld’s classification of parts of speech systems (Contentive, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members...
Xu, Kuan-Man; Wong, Takmeng; Wielicki, Bruce A.; Parker, Lindsay
2006-01-01
Three boundary-layer cloud object types, stratus, stratocumulus and cumulus, that occurred over the Pacific Ocean during January-August 1998, are identified from the CERES (Clouds and the Earth s Radiant Energy System) single scanner footprint (SSF) data from the TRMM (Tropical Rainfall Measuring Mission) satellite. This study emphasizes the differences and similarities in the characteristics of each cloud-object type between the tropical and subtropical regions and among different size categories and among small geographic areas. Both the frequencies of occurrence and statistical distributions of cloud physical properties are analyzed. In terms of frequencies of occurrence, stratocumulus clouds dominate the entire boundary layer cloud population in all regions and among all size categories. Stratus clouds are more prevalent in the subtropics and near the coastal regions, while cumulus clouds are relatively prevalent over open ocean and the equatorial regions, particularly, within the small size categories. The largest size category of stratus cloud objects occurs more frequently in the subtropics than in the tropics and has much larger average size than its cumulus and stratocumulus counterparts. Each of the three cloud object types exhibits small differences in statistical distributions of cloud optical depth, liquid water path, TOA albedo and perhaps cloud-top height, but large differences in those of cloud-top temperature and OLR between the tropics and subtropics. Differences in the sea surface temperature (SST) distributions between the tropics and subtropics influence some of the cloud macrophysical properties, but cloud microphysical properties and albedo for each cloud object type are likely determined by (local) boundary-layer dynamics and structures. Systematic variations of cloud optical depth, TOA albedo, cloud-top height, OLR and SST with cloud object sizes are pronounced for the stratocumulus and stratus types, which are related to systematic
Gillis, M Meredith; Garcia, Sarah; Hampstead, Benjamin M
2016-09-15
A recent model by Postma and colleagues posits that the encoding of object location associations (OLAs) requires the coordination of several cognitive processes mediated by ventral (object perception) and dorsal (spatial perception) visual pathways as well as the hippocampus (feature binding) [1]. Within this model, frontoparietal network recruitment is believed to contribute to both the spatial processing and working memory task demands. The current study used functional magnetic resonance imaging (fMRI) to test each step of this model in 15 participants who encoded OLAs and performed standard n-back tasks. As expected, object processing resulted in activation of the ventral visual stream. Object in location processing resulted in activation of both the ventral and dorsal visual streams as well as a lateral frontoparietal network. This condition was also the only one to result in medial temporal lobe activation, supporting its role in associative learning. A conjunction analysis revealed areas of shared activation between the working memory and object in location phase within the lateral frontoparietal network, anterior insula, and basal ganglia; consistent with prior working memory literature. Overall, findings support Postma and colleague's model and provide clear evidence for the role of working memory during OLA encoding.
Piper, Jim; Ikeda, Yoshihiro; Fujisawa, Yasuko; Ohno, Yoshiharu; Yoshikawa, Takeshi; O'Neil, Alison; Poole, Ian
2012-03-01
We objectively evaluate a straightforward registration method for correcting respiration-induced movement of abdominal organs in CT perfusion studies by measuring the distributions of alignment errors between corresponding landmark pairs. We introduce the concept and describe the advantages of using the surface-normal component of distance between pairs of corresponding landmarks selected so that their surface normal is in one of the three coordinate axis directions, and show that such landmarks can be precisely placed with respect to the surface normal. Using a large population of landmark pairs on a substantial quantity of 4D dynamic contrast-enhanced CT volume data, we quantify the average alignment errors of abdominal organs that remain uncorrected by registration.
Learning-Based Tracking of Complex Non-Rigid Motion
Qiang Wang; Hai-Zhou Ai; Guang-You Xu
2004-01-01
This paper describes a novel method for tracking complex non-rigid motions by learning the intrinsic object structure.The approach builds on and extends the studies on non-linear dimensionality reduction for object representation,object dynamics modeling and particle filter style tracking.First,the dimensionality reduction and density estimation algorithm is derived for unsupervised learning of object intrinsic representation,and the obtained non-rigid part of object state reduces even to 2-3 dimensions.Secondly the dynamical model is derived and trained based on this intrinsic representation.Thirdly the learned intrinsic object structure is integrated into a particle filter style tracker.It is shown that this intrinsic object representation has some interesting properties and based on which the newly derived dynamical model makes particle filter style tracker more robust and reliable.Extensive experiments are done on the tracking of challenging non-rigid motions such as fish twisting with selfocclusion,large inter-frame lip motion and facial expressions with global head rotation.Quantitative results are given to make comparisons between the newly proposed tracker and the existing tracker.The proposed method also has the potential to solve other type of tracking problems.
Parameter Estimation of a Delay Time Model of Wearing Parts Based on Objective Data
Y. Tang
2015-01-01
Full Text Available The wearing parts of a system have a very high failure frequency, making it necessary to carry out continual functional inspections and maintenance to protect the system from unscheduled downtime. This allows for the collection of a large amount of maintenance data. Taking the unique characteristics of the wearing parts into consideration, we establish their respective delay time models in ideal inspection cases and nonideal inspection cases. The model parameters are estimated entirely using the collected maintenance data. Then, a likelihood function of all renewal events is derived based on their occurring probability functions, and the model parameters are calculated with the maximum likelihood function method, which is solved by the CRM. Finally, using two wearing parts from the oil and gas drilling industry as examples—the filter element and the blowout preventer rubber core—the parameters of the distribution function of the initial failure time and the delay time for each example are estimated, and their distribution functions are obtained. Such parameter estimation based on objective data will contribute to the optimization of the reasonable function inspection interval and will also provide some theoretical models to support the integrity management of equipment or systems.
Fernanda P. S. Silva
2011-02-01
whether these adjustments change in older infants. OBJECTIVES: The aim of this study was to determine whether the size and rigidity of objects influence the proximal and distal adjustments to reaching of infants of 6, 7, 8 and 36 months of age. METHODS: Nine healthy infants were presented with: one large rigid, one small rigid, one large malleable and one small malleable object. The movements were videotaped and later analyzed qualitatively with regard to proximal (unimanual and bimanual reaching and distal adjustments (horizontal, vertical and oblique hand orientation, opened, half-open and closed hand and with regard to grasping of these objects (with and without. Friedman test and Dunn multiple comparisons were applied and 0.05 was considered as a significant difference. RESULTS: Infants of 36 months of age performed more unimanual reaching than younger infants. Additionally, at all ages, unimanual reaching was particularly performed for small objects. At 36 months of age infants guided the hand horizontally to touch and grasp the objects, while at 6 and 7 months the hand orientation was oblique to touch and vertical to grasp the objects, regardless of the object's properties. Over the months, both at the beginning and at the end of reaching, the hands became more open, especially to touch the large rigid object, and infants increasingly performed reaching with successful grasping, especially for malleable or small objects. CONCLUSIONS: From 6 to 36 months of age, the reaching became more refined and the infants adjusted to the different properties of the objects which were observed through changes in the proximal and distal adjustments.
Suellen A. Bottesini
2010-09-01
Full Text Available O estudo teve por objetivo analisar a preferência manual de crianças ao alcançar objetos de diferentes tamanhos nas idades de 4, 6, 8 e 36 meses. Para tanto, nove crianças saudáveis foram posicionadas em uma cadeira reclinada para trás a 50º com a horizontal e a elas foram apresentados quatro objetos de rigidez e tamanhos distintos. Foram coletados longitudinalmente 524 alcances aos 4, 6, 8 e 36 meses, sendo analisadas as variáveis mão preferida no alcance e índice de contribuição para os alcances bimanuais. Constatou-se que a mão preferida no alcance no decorrer dos meses foi a direita e que somente aos 6 meses o tamanho dos objetos influenciou a preferência manual: as crianças fizeram preferencialmente alcances com a mão direita para objetos pequenos, e mão esquerda para os grandes. Nos alcances bimanuais, constatou-se que, em geral, a mão que primeiro toca o objeto é a mão mais ativa durante todo o movimento de alcançar. Provavelmente porque a rigidez seja menos visualmente percebida do que o tamanho, só este influencia o alcance aos 6 meses, idade em que o lactente refina o movimento de alcance. O tamanho o influencia aos 6 meses, idade em que o movimento de alcançar se encontra em fase de refinamento: objetos pequenos que exigem maior precisão foram alcançados com a mão direita (mão preferida; e objetos grandes, que não exigem precisão para serem apreendidos, foram alcançados com a mão esquerda.The purpose of this study was to analyse infants' and toddlers' manual preference in reaching objects of different sizes and rigidity at the ages of 4, 6, 8, and 36 months. Four objects of different size and stiffness were presented to nine healthy infants leaning on a chair at 50º. A total of 524 reaching movements were analysed longitudinally to verify manual preference and the index of contribution of each hand for bimanual reaching. Results showed preference of the right hand for reaching objects; only at the age
An investigation of body part as object (BPO) responses in normal and brain-damaged adults.
Duffy, R J; Duffy, J R
1989-07-01
A test of simple pantomime was administered to three groups of adults and comparisons were made across groups of the incidence of subjects who exhibited body part as object (BPO) responses and of the mean frequency of occurrence of BPO in each group. The three groups were left-hemisphere-damaged aphasics (N = 28), right-hemisphere-damaged (N = 24), and normal controls (N = 28). The results indicated no significant differences among groups on the BPO measures. Also, to test the strength of association between the frequency of occurrence of BPO and measures of limb apraxia and severity of aphasia for the left-hemisphere-damaged aphasic group, correlation coefficients were obtained. The correlations were low and nonsignificant. The results of this investigation do not support the common clinical assumption that the occurrence of BPO during the performance of simple pantomimes is pathognomic for left-hemisphere pathology or associated with limb apraxia.
Parts and Relations in Young Children's Shape-Based Object Recognition
Augustine, Elaine; Smith, Linda B.; Jones, Susan S.
2011-01-01
The ability to recognize common objects from sparse information about geometric shape emerges during the same period in which children learn object names and object categories. Hummel and Biederman's (1992) theory of object recognition proposes that the geometric shapes of objects have two components--geometric volumes representing major object…
Clark, Timothy B P
2011-01-01
In this paper we investigate the class of rigid monomial ideals. We give a characterization of the minimal free resolutions of certain classes of these ideals. Specifically, we show that the ideals in a particular subclass of rigid monomial ideals are lattice-linear and thus their minimal resolution can be constructed as a poset resolution. We then use this result to give a description of the minimal free resolution of a larger class of rigid monomial ideals by using $\\mathcal{L}(n)$, the lattice of all lcm-lattices of monomial ideals with $n$ generators. By fixing a stratum in $\\mathcal{L}(n)$ where all ideals have the same total Betti numbers we show that rigidity is a property which is upward closed in $\\mathcal{L}(n)$. Furthermore, the minimal resolution of all rigid ideals contained in a fixed stratum is shown to be isomorphic to the constructed minimal resolution.
Quantum charged rigid membrane
Cordero, Ruben [Departamento de Fisica, Escuela Superior de Fisica y Matematicas del I.P.N., Unidad Adolfo Lopez Mateos, Edificio 9, 07738 Mexico, D.F. (Mexico); Molgado, Alberto [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Zacatecas Zac. (Mexico); Rojas, Efrain, E-mail: cordero@esfm.ipn.mx, E-mail: amolgado@fisica.uaz.edu.mx, E-mail: efrojas@uv.mx [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)
2011-03-21
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach, we observed that the theory comprises the management of both first- and second-class constraints. We thus show that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits us to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
Quantum charged rigid membrane
Cordero, Ruben; Rojas, Efrain
2010-01-01
The early Dirac proposal to model the electron as a charged membrane is reviewed. A rigidity term, instead of the natural membrane tension, involving linearly the extrinsic curvature of the worldvolume swept out by the membrane is considered in the action modeling the bubble in the presence of an electromagnetic field. We set up this model as a genuine second-order derivative theory by considering a non-trivial boundary term which plays a relevant part in our formulation. The Lagrangian in question is linear in the bubble acceleration and by means of the Ostrogradski-Hamiltonian approach we observed that the theory comprises the management of both first- and second-class constraints. We show thus that our second-order approach is robust allowing for a proper quantization. We found an effective quantum potential which permits to compute bounded states for the system. We comment on the possibility of describing brane world universes by invoking this kind of second-order correction terms.
HOMOLOGY RIGIDITY OF GRASSMANNIANS
Li Fang; Duan Haibao
2009-01-01
Applying the theory of GrSbner basis to the Schubert presentation for the cohomology of Grassmannians [2], we extend the homology rigidity results known for the classical Grassmaniaas to the exceptional cases.
[Conditions for going back to work on a part-time basis as a therapeutic objective].
Manaouil, Cécile; Graser, Marie; Jardé, Olivier
2003-07-12
AFTER MEDICAL ASSESSMENT: In the general system, therapeutic part-time work is a temporary disposition which allows a progressive readaptation to work. In principle, when an employee goes back to work, daily sickness benefits stop being paid by the Social Security Service. The decision to go back to work on a part-time basis is conditioned by a preliminary medical estimation which justifies the fact that it is impossible for the patient to go on with his professional occupation on a full-time basis or which shows the need for a progressive resumption. THE ATTENDING PHYSICIAN: During the part-time resumption, he has to continue to fill-out the sick leave certificates and add the comment "part-time work resumption". After an industrial accident or an occupational disease (work stoppage/occupational disease), on the extension medical certificate, the doctor should check the "work resumption" box, and add "therapeutic part-time job". The doctor should not produce a final medical certificate but only extension certificates. A part-time work resumption cannot be prescribed after the consolidation date, which stops the payment of the daily sickness benefits granted for a work disease. THE ROLE OF THE EMPLOYER: In principle, the employer has to subject the employee to a work resumption medical consultation by the company doctor. If a medical control authorization from the Social Security and the ability certificate for the part-time work resumption provided by the company doctor are produced, the employee has to be employed on a part-time basis by the employer, excepting when this is not compatible with the firm's activity. CIVIL SERVICE: Part-time work resumption is a therapeutic part-time job (50% only), and cannot follow after an ordinary sick leave. Its allocation depends on the medial committee decision after a long sick leave, or the reform commission decision after an industrial accident or an occupational disease.
Improving the efficiency of hospital porter services, part 1: study objectives and results.
Odegaard, Fredrik; Chen, Li; Quee, Ryan; Puterman, Martin L
2007-01-01
This article is the first of a 2-part series reporting the results of a 7-month study of porter operations at Vancouver General Hospital, Vancouver, British Columbia, Canada. Part 1 describes the importance of efficient porter services, the system's operation at the time of the study, the challenges faced in carrying out the study, the performance measures developed, the recommendations, and the outcomes. Part 2 describes the simulation model that measured the impact of system changes and the linear programming model developed to improve porter schedules.
Analysis of Switched-Rigid Floating Oscillator
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.
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...
Pal, Tanmoy; Bhattacharjee, Somendra M.
2016-05-01
The temperature dependence of DNA flexibility is studied in the presence of stretching and unzipping forces. Two classes of models are considered. In one case the origin of elasticity is entropic due to the polymeric correlations, and in the other the double-stranded DNA is taken to have an intrinsic rigidity for bending. In both cases single strands are completely flexible. The change in the elastic constant for the flexible case due to thermally generated bubbles is obtained exactly. For the case of intrinsic rigidity, the elastic constant is found to be proportional to the square root of the bubble number fluctuation.
Troiano, Giovanni Maria
Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape-changing inte......Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape...
Meiqin Suo
2017-07-01
Full Text Available In this study, an integrated solving method is proposed for interval multi-objective planning. The proposed method is based on fuzzy linear programming and an interactive two-step method. It cannot only provide objectively optimal values for multiple objectives at the same time, but also effectively offer a globally optimal interval solution. Meanwhile, the degree of satisfaction related to different objective functions would be obtained. Then, the integrated solving method for interval multi-objective planning is applied to a case study of planning multi-water resources joint scheduling under uncertainty in the eastern part of Handan, China. The solutions obtained are useful for decision makers in easing the contradiction between supply of multi-water resources and demand from different water users. Moreover, it can provide the optimal comprehensive benefits of economy, society, and the environment.
Meson, Alejandro M., E-mail: meson@iflysib.unlp.edu.ar; Vericat, Fernando, E-mail: vericat@iflysib.unlp.edu.ar [CONICET-UNLP, Instituto de Fisica de Liquidos y Sistemas Biologicos (IFLYSIB) (Argentina)
2011-12-15
We analyze when a multifractal spectrum can be used to recover the potential. This phenomenon is known as multifractal rigidity. We prove that for a certain class of potentials the multifractal spectrum of local entropies uniquely determines their equilibrium states. This leads to a classification which identifies two systems up to a change of variables.
Electrostatics of Rigid Polyelectrolytes
Wong, G.C.L.
2009-06-04
The organization of rigid biological polyelectrolytes by multivalent ions and macroions are important for many fundamental problems in biology and biomedicine, such as cytoskeletal regulation and antimicrobial sequestration in cystic fibrosis. These polyelectrolytes have been used as model systems for understanding electrostatics in complex fluids. Here, we review some recent results in theory, simulations, and experiments.
Electoral Stability and Rigidity
Levy, Michael Y
2016-01-01
Some argue that political stability is best served through a two-party system. This study refutes this. The author mathematically defines the stability and rigidity of electoral systems comprised of any quantity of electors and parties. In fact, stability is a function of the quantity of electors - i.e., the number of occupied seats at the table. As the number of electors increases, the properties of an electorate are increasingly well resolved, and well described by those of an electorate that is least excessive -- that is to say an electorate that is closest to equilibrium. Further, electoral rigidity is a function of the quantity of parties and their probabilities of representation. An absolutely rigid system admits no fluctuations -- whatever happens to one elector will happen to all electors. As the quantity of parties increases so does the number of party lines, and with it the quantity of alternatives with which to respond to an external stimulus. Rigidity is significant in a social system that places ...
Witjes, J.A.; Moonen, P.M.J.; Heijden, A.G. van der
2005-01-01
INTRODUCTION AND OBJECTIVE: Several studies have shown that rigid fluorescence cystoscopy (RFC) with hexaminolevulinate (HAL) is superior to standard rigid white light (RWLC) cystoscopy in diagnosing bladder tumours, with a clinically relevant impact on the patient's management. These studies, howev
Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅰ: Experimental Study of Bird Impact
无
2007-01-01
The conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided.
Khan, Kamran Z; Gaunt, Kathryn; Ramachandran, Sankaranarayanan; Pushkar, Piyush
2013-09-01
The organisation, administration and running of a successful OSCE programme need considerable knowledge, experience and planning. Different teams looking after various aspects of OSCE need to work collaboratively for an effective question bank development, examiner training and standardised patients' training. Quality assurance is an ongoing process taking place throughout the OSCE cycle. In order for the OSCE to generate reliable results it is essential to pay attention to each and every element of quality assurance, as poorly standardised patients, untrained examiners, poor quality questions and inappropriate scoring rubrics each will affect the reliability of the OSCE. The validity will also be influenced if the questions are not realistic and mapped against the learning outcomes of the teaching programme. This part of the Guide addresses all these important issues in order to help the reader setup and quality assure their new or existing OSCE programmes.
Model-based beam control for illumination of remote objects, part II: laboratory testbed
Basu, Santasri; Voelz, David; Chandler, Susan M.; Lukesh, Gordon W.; Sjogren, Jon
2004-10-01
When a laser beam propagates through the atmosphere, it is subject to corrupting influences including mechanical vibrations, turbulence and tracker limitations. As a result, pointing errors can occur, causing loss of energy or signal at the target. Nukove Scientific Consulting has developed algorithms to estimate these pointing errors from the statistics of the return photons from the target. To prove the feasibility of this approach for real-time estimation, an analysis tool called RHINO was developed by Nukove. Associated with this effort, New Mexico State University developed a laboratory testbed, the ultimate objective being to test the estimation algorithms under controlled conditions and to stream data into RHINO to prove the feasibility of real-time operation. The present paper outlines the description of this testbed and the results obtained through RHINO when the testbed was used to test the estimation approach.
Evaluation of Genetic Algorithm Concepts using Model Problems. Part 1; Single-Objective Optimization
Holst, Terry L.; Pulliam, Thomas H.
2003-01-01
A genetic-algorithm-based optimization approach is described and evaluated using a simple hill-climbing model problem. The model problem utilized herein allows for the broad specification of a large number of search spaces including spaces with an arbitrary number of genes or decision variables and an arbitrary number hills or modes. In the present study, only single objective problems are considered. Results indicate that the genetic algorithm optimization approach is flexible in application and extremely reliable, providing optimal results for all problems attempted. The most difficult problems - those with large hyper-volumes and multi-mode search spaces containing a large number of genes - require a large number of function evaluations for GA convergence, but they always converge.
Achtemeier, Gary L.; Ochs, Harry T., III
1988-01-01
The variational method of undetermined multipliers is used to derive a multivariate model for objective analysis. The model is intended for the assimilation of 3-D fields of rawinsonde height, temperature and wind, and mean level temperature observed by satellite into a dynamically consistent data set. Relative measurement errors are taken into account. The dynamic equations are the two nonlinear horizontal momentum equations, the hydrostatic equation, and an integrated continuity equation. The model Euler-Lagrange equations are eleven linear and/or nonlinear partial differential and/or algebraic equations. A cyclical solution sequence is described. Other model features include a nonlinear terrain-following vertical coordinate that eliminates truncation error in the pressure gradient terms of the horizontal momentum equations and easily accommodates satellite observed mean layer temperatures in the middle and upper troposphere. A projection of the pressure gradient onto equivalent pressure surfaces removes most of the adverse impacts of the lower coordinate surface on the variational adjustment.
Obituary--rigid contact lenses.
Efron, Nathan
2010-10-01
Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace.
Evaluation of Genetic Algorithm Concepts Using Model Problems. Part 2; Multi-Objective Optimization
Holst, Terry L.; Pulliam, Thomas H.
2003-01-01
A genetic algorithm approach suitable for solving multi-objective optimization problems is described and evaluated using a series of simple model problems. Several new features including a binning selection algorithm and a gene-space transformation procedure are included. The genetic algorithm is suitable for finding pareto optimal solutions in search spaces that are defined by any number of genes and that contain any number of local extrema. Results indicate that the genetic algorithm optimization approach is flexible in application and extremely reliable, providing optimal results for all optimization problems attempted. The binning algorithm generally provides pareto front quality enhancements and moderate convergence efficiency improvements for most of the model problems. The gene-space transformation procedure provides a large convergence efficiency enhancement for problems with non-convoluted pareto fronts and a degradation in efficiency for problems with convoluted pareto fronts. The most difficult problems --multi-mode search spaces with a large number of genes and convoluted pareto fronts-- require a large number of function evaluations for GA convergence, but always converge.
T. N. Berezina
2013-04-01
Full Text Available We propose a new procedure for objective measurement of positive emotion in students in various situations of educational environment. We introduce the concept of “true emotions” – those causing changes in body functional state and affecting its smell. We argue that emotionally safe learning environment should provide a genuine emergence of positive emotions and reduce the likelihood of genuine negative emotions. We provide data of experimental research of genuine positive emotions in three main situations of student life: training classes (lecture, imaginary situations of joy (trainings, student life activities, real-life situations outside the school. It is shown that in the 0.4–0.5% of imaginary situations and real-life situations, students’ functional state changes, thus giving rise to alcohol-like substances exhaling. We describe these situations (food enjoying, meeting with someone you love, pain control, art perception, etc.. We point out that in the control series of measurements, when the students were in a neutral functional state (on a lecture, no alcohol-like substance in the breath were observed.
Compliant mechanism road bicycle brake: a rigid-body replacement case study
Olsen, Brian M [Los Alamos National Laboratory; Howell, Larry L [NON LANL; Magleby, Spencer P [NON LANL
2011-01-19
The design of high-performance bicycle brakes is complicated by the competing design objectives of increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace current rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.
Radiology as part of an objective structured clinical examination on clinical skills
Berk, I.A.H. van den, E-mail: i.a.h.van_den_berk@lumc.nl [Department of Radiology, Leiden University Medical Centre, Postbus 9600, 2300 RC Leiden (Netherlands); Ridder, J.M.M. van de, E-mail: J.M.M.vandeRidder@umcutrecht.nl [School of Medical Sciences, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Schaik, J.P.J. van, E-mail: J.P.J.vanSchaik@umcutrecht.nl [Department of Radiology, University Medical Centre Utrecht, Heidelberglaan 100 E01-132, 3584 CX Utrecht (Netherlands)
2011-06-15
Introduction: An objective structured clinical examination (OSCE) assessess clinical competence in a standardised and context related manner. Compared with written tests, OSCE's are more susceptible to reliability errors because of the use of multiple cases and multiple examiners. In the pre-clinical phase of the medical curriculum of the University Medical Centre Utrecht, an OSCE is organised as a medical consult. We evaluated the radiology station. Method: Four questions were formulated: {center_dot}What is the internal consistency of the items of the radiology station? {center_dot}How do the scores on the radiology station compare with the scores on the test excluding radiology? {center_dot}How do different cases differ in scores? {center_dot}What are the differences in score between the examiners? We analysed the OSCE results of second year medical students in 2004. Results: Two hundred and sixty-five students were examined in the OSCE in 2004. Ninty-three Students were examined in the radiology station. Cronbach's alpha coefficient for the radiology station was 0.92. The average score for the radiology station was 3.8 (0.87). The average score for the test without radiology was 3.9 (0.32). The range of the average scores for the six different cases was 0.5 (3.6-4.1). The range of the average scores for the five examiners was 1.0 (3.3-4.3). Conclusion: The internal consistency of the items in the radiology station is good. The average score for the radiology station is similar to that of the other stations. The range of the scores between the different cases was relatively small. The range of the scores between the different examiners was clearly larger.
He, Chenxu; Wylie, William
2011-01-01
In this paper we study the space of solutions to an overdetermined linear system involving the Hessian of functions. We show that if the solution space has dimension greater than one, then the underlying manifold has a very rigid warped product structure. This warped product structure will be used to study warped product Einstein structures in our paper "The space of virtual solutions to the warped product Einstein equation".
The Myth of Objectivity: Implicit Racial Bias and the Law (Part 2
Willem Hendrik Gravett
2017-04-01
Full Text Available The centrality of race to our history and the substantial racial inequalities that continue to pervade society ensure that "race" remains an extraordinarily salient and meaningful social category. Explicit racial prejudice, however, is only part of the problem. Equally important - and likely more pervasive - is the phenomenon of implicit racial prejudice: the cognitive processes whereby, despite even our best intentions, the human mind automatically classifies information in racial categories and against disfavoured social groups. Empirical research shows convincingly that these biases against socially disfavoured groups are (i pervasive; (ii often diverge from consciously reported attitudes and beliefs; and (iii influence consequential behaviour towards the subjects of these biases. The existence of implicit racial prejudices poses a challenge to legal theory and practice. From the standpoint of a legal system that seeks to forbid differential treatment based upon race or other protected traits, if people are in fact treated differently, and worse, because of their race or other protected trait, then the fundamental principle of anti-discrimination has been violated. It hardly matters that the source of the differential treatment is implicit rather than conscious bias. This article investigates the relevance of this research to the law by means of an empirical account of how implicit racial bias could affect the criminal trial trajectory in the areas of policing, prosecutorial discretion and judicial decision-making. It is the author's hypothesis that this mostly American research also applies to South Africa. The empirical evidence of implicit biases in every country tested shows that people are systematically implicitly biased in favour of socially privileged groups. Even after 1994 South Africa – similar to the US – continues to be characterised by a pronounced social hierarchy in which Whites overwhelmingly have the highest social
Rigidity Constraints for Large Mesh Deformation
Yong Zhao; Xin-Guo Liu; Qun-Sheng Peng; Hu-Jun Bao
2009-01-01
It is a challenging problem of surface-based deformation to avoid apparent volumetric distortions around largely deformed areas. In this paper, we propose a new rigidity constraint for gradient domain mesh deformation to address this problem. Intuitively the proposed constraint can be regarded as several small cubes defined by the mesh vertices through mean value coordinates. The user interactively specifies the cubes in the regions which are prone to volumetric distortions, and the rigidity constraints could make the mesh behave like a solid object during deformation. The experimental results demonstrate that our constraint is intuitive, easy to use and very effective.
Andrea Baraldi
2012-09-01
Full Text Available According to existing literature and despite their commercial success, state-of-the-art two-stage non-iterative geographic object-based image analysis (GEOBIA systems and three-stage iterative geographic object-oriented image analysis (GEOOIA systems, where GEOOIA/GEOBIA, remain affected by a lack of productivity, general consensus and research. To outperform the degree of automation, accuracy, efficiency, robustness, scalability and timeliness of existing GEOBIA/GEOOIA systems in compliance with the Quality Assurance Framework for Earth Observation (QA4EO guidelines, this methodological work is split into two parts. The present first paper provides a multi-disciplinary Strengths, Weaknesses, Opportunities and Threats (SWOT analysis of the GEOBIA/GEOOIA approaches that augments similar analyses proposed in recent years. In line with constraints stemming from human vision, this SWOT analysis promotes a shift of learning paradigm in the pre-attentive vision first stage of a remote sensing (RS image understanding system (RS-IUS, from sub-symbolic statistical model-based (inductive image segmentation to symbolic physical model-based (deductive image preliminary classification. Hence, a symbolic deductive pre-attentive vision first stage accomplishes image sub-symbolic segmentation and image symbolic pre-classification simultaneously. In the second part of this work a novel hybrid (combined deductive and inductive RS-IUS architecture featuring a symbolic deductive pre-attentive vision first stage is proposed and discussed in terms of: (a computational theory (system design; (b information/knowledge representation; (c algorithm design; and (d implementation. As proof-of-concept of symbolic physical model-based pre-attentive vision first stage, the spectral knowledge-based, operational, near real-time Satellite Image Automatic Mapper™ (SIAM™ is selected from existing literature. To the best of these authors’ knowledge, this is the first time a
Parkinson's disease rigidity: relation to brain connectivity and motor performance
Nazanin eBaradaran
2013-06-01
Full Text Available Objective: 1 To determine the brain connectivity pattern associated with clinical rigidity scores in Parkinson's disease (PD and 2 to determine the relation between clinically-assessed rigidity and quantitative metrics of motor performance.Background: Rigidity, the resistance to passive movement, is exacerbated in PD by asking the subject to move the contralateral limb, implying that rigidity involves a distributed brain network. Rigidity mainly affects subjects when they attempt to move; yet the relation between clinical rigidity scores and quantitative aspects of motor performance are unknown.Methods: Ten clinically diagnosed PD patients (off medication and ten controls were recruited to perform an fMRI squeeze-bulb tracking task that included both visually guided and internally guided features. The direct functional connectivity between anatomically defined regions of interest was assessed with Dynamic Bayesian Networks (DBNs. Tracking performance was assessed by fitting Linear Dynamical System (LDS models to the motor performance, and was compared to the clinical rigidity scores. A cross-validated Least Absolute Shrinkage and Selection Operator (LASSO regression method was used to determine the brain connectivity network that best predicted clinical rigidity scores.Results: The damping ratio of the LDS models significantly correlated with clinical rigidity scores (p < 10-4. An fMRI connectivity network in subcortical and primary and premotor cortical regions accurately predicted clinical rigidity scores (p < 10-5. Conclusions: A widely distributed cortical/subcortical network is associated with rigidity observed in PD patients, which reinforces the importance of altered functional connectivity in the pathophysiology of PD. PD subjects with higher rigidity scores tend to have less overshoot in their tracking performance, and damping ratio may represent a robust, quantitative marker of the motoric effects of increasing rigidity.
Saye, Robert
2017-09-01
In this two-part paper, a high-order accurate implicit mesh discontinuous Galerkin (dG) framework is developed for fluid interface dynamics, facilitating precise computation of interfacial fluid flow in evolving geometries. The framework uses implicitly defined meshes-wherein a reference quadtree or octree grid is combined with an implicit representation of evolving interfaces and moving domain boundaries-and allows physically prescribed interfacial jump conditions to be imposed or captured with high-order accuracy. Part one discusses the design of the framework, including: (i) high-order quadrature for implicitly defined elements and faces; (ii) high-order accurate discretisation of scalar and vector-valued elliptic partial differential equations with interfacial jumps in ellipticity coefficient, leading to optimal-order accuracy in the maximum norm and discrete linear systems that are symmetric positive (semi)definite; (iii) the design of incompressible fluid flow projection operators, which except for the influence of small penalty parameters, are discretely idempotent; and (iv) the design of geometric multigrid methods for elliptic interface problems on implicitly defined meshes and their use as preconditioners for the conjugate gradient method. Also discussed is a variety of aspects relating to moving interfaces, including: (v) dG discretisations of the level set method on implicitly defined meshes; (vi) transferring state between evolving implicit meshes; (vii) preserving mesh topology to accurately compute temporal derivatives; (viii) high-order accurate reinitialisation of level set functions; and (ix) the integration of adaptive mesh refinement. In part two, several applications of the implicit mesh dG framework in two and three dimensions are presented, including examples of single phase flow in nontrivial geometry, surface tension-driven two phase flow with phase-dependent fluid density and viscosity, rigid body fluid-structure interaction, and free
Saye, Robert
2017-09-01
In this two-part paper, a high-order accurate implicit mesh discontinuous Galerkin (dG) framework is developed for fluid interface dynamics, facilitating precise computation of interfacial fluid flow in evolving geometries. The framework uses implicitly defined meshes-wherein a reference quadtree or octree grid is combined with an implicit representation of evolving interfaces and moving domain boundaries-and allows physically prescribed interfacial jump conditions to be imposed or captured with high-order accuracy. Part one discusses the design of the framework, including: (i) high-order quadrature for implicitly defined elements and faces; (ii) high-order accurate discretisation of scalar and vector-valued elliptic partial differential equations with interfacial jumps in ellipticity coefficient, leading to optimal-order accuracy in the maximum norm and discrete linear systems that are symmetric positive (semi)definite; (iii) the design of incompressible fluid flow projection operators, which except for the influence of small penalty parameters, are discretely idempotent; and (iv) the design of geometric multigrid methods for elliptic interface problems on implicitly defined meshes and their use as preconditioners for the conjugate gradient method. Also discussed is a variety of aspects relating to moving interfaces, including: (v) dG discretisations of the level set method on implicitly defined meshes; (vi) transferring state between evolving implicit meshes; (vii) preserving mesh topology to accurately compute temporal derivatives; (viii) high-order accurate reinitialisation of level set functions; and (ix) the integration of adaptive mesh refinement. In part two, several applications of the implicit mesh dG framework in two and three dimensions are presented, including examples of single phase flow in nontrivial geometry, surface tension-driven two phase flow with phase-dependent fluid density and viscosity, rigid body fluid-structure interaction, and free
Khan, Kamran Z; Ramachandran, Sankaranarayanan; Gaunt, Kathryn; Pushkar, Piyush
2013-09-01
The Objective Structured Clinical Examination (OSCE) was first described by Harden in 1975 as an alternative to the existing methods of assessing clinical performance (Harden et al. 1975). The OSCE was designed to improve the validity and reliability of assessment of performance, which was previously assessed using the long case and short case examinations. Since then the use of the OSCE has become widespread within both undergraduate and postgraduate clinical education. We recognise that the introduction of the OSCE into an existing assessment programme is a challenging process requiring a considerable amount of theoretical and practical knowledge. The two parts of this Guide are designed to assist all those who intend implementing the OSCE into their assessment systems. Part I addresses the theoretical aspects of the OSCE, exploring its historical development, its place within the range of assessment tools and its core applications. Part II offers more practical information on the process of implementing an OSCE, including guidance on developing OSCE stations, choosing scoring rubrics, training examiners and standardised patients and managing quality assurance processes. Together we hope these two parts will act as a useful resource both for those choosing to implement the OSCE for the first time and also those wishing to quality assure their existing OSCE programme.
Torsional Rigidity of Minimal Submanifolds
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...... for the torsional rigidity are actually attained and give conditions under which the geometric average of the stochastic mean exit time for Brownian motion at infinity is finite....
Rigid collapsible dish structure
Palmer, William B. (Inventor); Giebler, Martin M. (Inventor)
1982-01-01
A collapsible dish structure composed of a plurality of rows of rigid radial petal assemblies concentric with the axis of the dish. The petal assemblies consist of a center petal and two side petals, the center petal hinged on an axis tangent to a circle concentric with the axis of the dish and the side petals hinged to the center petal at their mating edge. The center petal is foldable inwardly and the side petals rotate about their hinges such that the collapsed dish structure occupies a much smaller volume than the deployed dish. Means of controlling the shape of the dish to compensate for differential expansion of the deployed dish are also provided.
McGrath, Paul L
2014-01-01
In this thesis, I examine in detail the properties of rigid quasilocal frames (RQF), which have been proposed as a geometrically natural way to define spatially extended reference frames in general relativity. I also explore their usefulness, in particular, as a tool for constructing completely general conservation laws that do not rely on the presence of spacetime symmetries and include both matter and gravitational contributions without the need for any ad hoc structures such as pseudotensors. In doing so, I show how the RQF approach affords a deeper understanding of the nature of gravitational fluxes via the equivalence principle. Finally, I apply the RQF formalism to explore Ehrenfest's rotating disk paradox, a generalization of Archimedes' law to curved spacetime, tidal interactions for Earth's and Jupiter's moons, and more.
Troiano, Giovanni Maria
to convey particular information (e.g., big-isurgent, loud-is-up). The second work presents a large-scale analysis of 340 Sci-Fi movies that identifies instances of shape-changing interfaces. Results from the analysis reveals emergent behavioral patterns of shape change, namely Reconfiguration......Deformable and shape-changing interfaces are rapidly emerging in the field of human-computer interaction (HCI). Deformable interfaces provide users with newer input possibilities such as bending, squeezing, or stretching, which were impossible to achieve with rigid interfaces. Shape......-changing interfaces can reconfigure their shape dynamically, providing users with new affordances and output modalities. This thesis contributes to both the field of deformable interfaces and shape-changing interfaces through empirical research. In the area of deformable interfaces, this thesis presents two studies...
Pulling rigid bodies through granular material
Kubik, Ryan; Dressaire, Emilie
2016-11-01
The need for anchoring systems in granular materials such as sand is present in the marine transportation industry, e.g. to layout moorings, keep vessels and docks fixed in bodies of water, build oil rigs, etc. The holding power of an anchor is associated with the force exerted by the granular media. Empirical evidence indicates that the holding power depends on the size and shape of the anchoring structure. In this model study, we use a two-dimensional geometry in which a rigid body is pulled through a granular media at constant velocity to determine the drag and lift forces exerted by a granular medium on a moving object. The method allows measuring the drag force and recording the trajectory of the rigid object through the sand. We systematically vary the size and geometry of the rigid body, the properties of the granular medium and the extraction speed. For different initial positions of a cylindrical object pulled horizontally through the medium, we record large variations in magnitude of the drag and a significant lift force that pulls the object out of the sand.
Criteria for Hull-Machinery Rigidity Compatibility,
1981-05-01
articulated double-reduction gear design permits a * greater variety of arrangements with essentially the same rotating parts by rolling the pinion and...Additional intercostal girders are to be fitted within the double bottom to ensure the satisfactory distribution of the weight and the rigidity of the...and 124 arranged to distribute the loads effectively into the adjacent structure. Extra intercostal girders, effect- ively attached, are to be fitted
Tautochrone and Brachistochrone Shape Solutions for Rocking Rigid Bodies
Glaschke, Patrick
2016-01-01
Rocking rigid bodies appear in several shapes in everyday life: As furniture like rocking chairs and rocking cradles or as toys like rocking horses or tilting dolls. The familiar rocking motion of these objects, a non-linear combination of a rigid rotation and a translation of the center of mass, gives rise to a number of interesting dynamical properties. However, their study has received little attention in the literature. This work presents a comprehensive introduction to the dynamics of rocking rigid bodies, including a concise derivation of the equations of motion as well as a general inversion procedure to construct rocking rigid body shapes with specified dynamical properties. Moreover, two novel rigid body shapes are derived - the tautochrone shape and the brachistochrone shape - which represent an intriguing generalization of the well-know tautochrone and brachistochrone curves. In particular, tautochrone shapes offer an alternative construction of a tautochrone pendulum, in addition to Huygens' cyclo...
Understanding geological processes: Visualization of rigid and non-rigid transformations
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
International rigid contact lens prescribing.
Efron, Nathan; Morgan, Philip B; Helland, Magne; Itoi, Motozumi; Jones, Deborah; Nichols, Jason J; van der Worp, Eef; Woods, Craig A
2010-06-01
Rigid lenses have been fitted less since the introduction of soft lenses nearly 40 years ago. Data that we have gathered from annual contact lens fitting surveys conducted in Australia, Canada, Japan, the Netherlands, Norway, the UK and the USA between 2000 and 2008 facilitate an accurate characterization of the pattern of the decline of rigid lens fitting during the first decade of this century. There is a trend for rigid lenses to be utilized primarily for refitting those patients who are already successful rigid lens wearers-most typically older females being refit with higher Dk materials. Rigid lenses are generally fitted on a full-time basis (four or more days of wear per week) without a planned replacement schedule. Orthokeratology is especially popular in the Netherlands, but is seldom prescribed in the other countries surveyed.
Rigid-only versus combined rigid and flexible percutaneous nephrolithotomy (PNL)
Cracco, Cecilia M; knoll, thomas; Liatsikos, Evangelos N
2017-01-01
. Appraisal of reliable outcomes of such PNL techniques would better guide intraoperative choices and optimize surgical results. Therefore our objective was to systematically review relevant literature comparing the outcomes of rigid-only PNL and combined flexible PNLs (adding flexible nephroscopy and......INTRODUCTION: Percutaneous nephrolithotomy (PNL) is usually performed worldwide with a rigid-only antegrade approach. Daily practice suggests that adding flexible nephroscopy and/or ureteroscopy to conventional rigid PNL might improve its efficacy and safety, but available evidence is weak....../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...
Rigid Spine Syndrome among Children in Oman
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.
Akinetic rigid syndrome: An overview
Gupta Praveen
2007-01-01
Full Text Available Akinetic-rigid syndromes can be caused by diverse etiologies. It is vital to separate idiopathic Parkinson′s disease from other neurodegenerative diseases and causes of secondary parkinsonism as it has significant therapeutic implications. However even specialists may misdiagnose nonidiopathic parkinsonism as Parkinson′s disease in a quarter of cases. Often the history may be nonspecific and all investigations may be normal. The diagnosis may thus rest entirely on clinical features. The etiological diagnosis of Akinetic rigid syndrome has critical therapeutic and prognostic implications. Therefore we will review the various etiologies of akinetic rigid syndrome and highlight critical clinical features to aid in differential diagnosis.
Development of laser ruler in rigid laryngoscope.
Lee, Young-Ok; Kim, Byoung-Chul; Lee, Jung-Hoon; Lee, Jin-Choon; Lee, Byung-Joo; Wang, Soo-Geun; Ro, Jung-Hoon; Jeon, Gye-Rok; Shin, Bum-Joo
2011-12-01
The objective of this study was to develop a new device that provides a simple, noninvasive method of measuring accurate lesion size while using an endoscope. We developed a rigid laryngoscope with a built-in laser-ruler using a one-light emitting diode and an acrylic plate. The invention incorporates a built-in laser diode that projects an auto-parallel beam into the optical path of the rigid laryngoscope to form two spots in the field of view. While the interspot distance remains consistent despite changes in focal plane, magnification, or viewing angle of the laryngoscope, projection to an uneven surface introduces certain variations in the shape, and size of the spots, and the distance between the two spots. The device enables a laryngologist to easily measure the distance between landmarks, as well as the change in real size, and the progressive change of vocal fold lesions in an outpatient setting.
Skeletal Rigidity of Phylogenetic Trees
Cheng, Howard; Li, Brian; Risteski, Andrej
2012-01-01
Motivated by geometric origami and the straight skeleton construction, we outline a map between spaces of phylogenetic trees and spaces of planar polygons. The limitations of this map is studied through explicit examples, culminating in proving a structural rigidity result.
Wage rigidity and job creation
Haefke, Christian; Sonntag, Marcus; Rens, Thijs van
2013-01-01
Recent research in macroeconomics emphasizes the role of wage rigidity in accounting for the volatility of unemployment fluctuations. We use worker-level data from the CPS to measure the sensitivity of wages of newly hired workers to changes in aggregate labor market conditions. The wage of new hires, unlike the aggregate wage, is volatile and responds almost one-to-one to changes in labor productivity. We conclude that there is little evidence for wage rigidity in the data.
Sripati, Arun P; Olson, Carl R
2010-06-09
It is commonly thought that neurons in monkey inferotemporal cortex are conjunction selective--that a neuron will respond to an image if and only if it contains a required combination of parts. However, this view is based on the results of experiments manipulating closely adjacent or confluent parts. Neurons may have been sensitive not to the conjunction of parts as such but to the presence of a unique feature created where they abut. Here, we compare responses to two sets of images, one composed of spatially separate and the other of abutting parts. We show that the influences of spatially separate parts combine, to a very close approximation, according to a linear rule. Nonlinearities are more prominent--although still weak--in responses to images composed of abutting parts.
Rigid multibody system dynamics with uncertain rigid bodies
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.
North Carolina State Dept. of Community Colleges, Raleigh.
A two-part articulation instructional objective guide for drafting (graphic communications) is provided. Part I contains summary information on seven blocks (courses) of instruction. They are as follow: introduction; basic technical drafting; problem solving in graphics; reproduction processes; freehand drawing and sketching; graphics composition;…
Crystal Frameworks, Matrix-valued Functions and Rigidity Operators
Power, S C
2011-01-01
An introduction and survey is given of some recent work on the infinitesimal dynamics of \\textit{crystal frameworks}, that is, of translationally periodic discrete bond-node structures in $\\mathbb{R}^d$, for $ d=2,3,...$. We discuss the rigidity matrix, a fundamental object from finite bar-joint framework theory, rigidity operators, matrix-function representations and low energy phonons. These phonons in material crystals, such as quartz and zeolites, are known as rigid unit modes, or RUMs, and are associated with the relative motions of rigid units, such as ~SiO$_4$ tetrahedra in the tetrahedral polyhedral bond-node model for quartz. We also introduce semi-infinite crystal frameworks, bi-crystal frameworks and associated multi-variable Toeplitz operators.
Lawson, Rebecca
2014-02-01
The limits of generalization of our 3-D shape recognition system to identifying objects by touch was investigated by testing exploration at unusual locations and using untrained effectors. In Experiments 1 and 2, people found identification by hand of real objects, plastic 3-D models of objects, and raised line drawings placed in front of themselves no easier than when exploration was behind their back. Experiment 3 compared one-handed, two-handed, one-footed, and two-footed haptic object recognition of familiar objects. Recognition by foot was slower (7 vs. 13 s) and much less accurate (9 % vs. 47 % errors) than recognition by either one or both hands. Nevertheless, item difficulty was similar across hand and foot exploration, and there was a strong correlation between an individual's hand and foot performance. Furthermore, foot recognition was better with the largest 20 of the 80 items (32 % errors), suggesting that physical limitations hampered exploration by foot. Thus, object recognition by hand generalized efficiently across the spatial location of stimuli, while object recognition by foot seemed surprisingly good given that no prior training was provided. Active touch (haptics) thus efficiently extracts 3-D shape information and accesses stored representations of familiar objects from novel modes of input.
Rigidly foldable origami gadgets and tessellations.
Evans, Thomas A; Lang, Robert J; Magleby, Spencer P; Howell, Larry L
2015-09-01
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.
Rigidly foldable origami gadgets and tessellations
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
Catalin STRIMBEI
2006-01-01
Full Text Available There are some significant theoretical and technological approaches on the issue of object-relational "impedance mismatch" between applications' abstract model and database structures. Two characteristics of those approaches we think that are questionable: first of all it is so called “flat” nature of relational systems and model, and then there is the drawback of the storage of (object oriented semantics on the application level, thus severe limiting the data (object sharing and, at the same time, virtually broking the data independence principle of database systems architecture. In this paper we will try to outline an approach to address to some in a concrete manner.
This document may be of assistance in applying the Title V air operating permit regulations. This document is part of the Title V Petition Database available at www2.epa.gov/title-v-operating-permits/title-v-petition-database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.
Rijkhoff, Jan
2008-01-01
, Non-Verb, Modifier), there are also flexible word classes within the rigid lexical category Noun (Set Noun, Sort Noun, General Noun). Members of flexible word classes are characterized by their vague semantics, which in the case of nouns means that values for the semantic features Shape...
Rigidity-tuning conductive elastomer
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.
Rigid coupling is also flexible
Appleberry, W. T.
1978-01-01
Spring-loaded coupling is rigid under light loads and swivels under higher loads. Break-out point can be set at any desired value by selecting appropriate preload springs. Coupling requires no cushions or elastomeric joints that limit temperature range.
Optimized imaging using non-rigid registration
Berkels, Benjamin, E-mail: berkels@aices.rwth-aachen.de [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Binev, Peter, E-mail: binev@math.sc.edu [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Mathematics, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Blom, Douglas A., E-mail: doug.blom@sc.edu [NanoCenter, 1212 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Dahmen, Wolfgang, E-mail: dahmen@igpm.rwth-aachen.de [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Institut für Geometrie und Praktische Mathematik, RWTH Aachen, Templergraben 55, 52056 Aachen (Germany); Sharpley, Robert C., E-mail: rcsharpley@gmail.com [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Mathematics, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Vogt, Thomas, E-mail: tvogt@mailbox.sc.edu [Interdisciplinary Mathematics Institute, 1523 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); NanoCenter, 1212 Greene Street, University of South Carolina, Columbia, SC 29208 (United States); Department of Chemistry and Biochemistry, 631 Sumter Street, University of South Carolina, Columbia, SC 29208 (United States)
2014-03-01
The extraordinary improvements of modern imaging devices offer access to data with unprecedented information content. However, widely used image processing methodologies fall far short of exploiting the full breadth of information offered by numerous types of scanning probe, optical, and electron microscopies. In many applications, it is necessary to keep measurement intensities below a desired threshold. We propose a methodology for extracting an increased level of information by processing a series of data sets suffering, in particular, from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process. An important role is played by a non-rigid pixel-wise registration method that can cope with low signal-to-noise ratios. This is accompanied by formulating objective quality measures which replace human intervention and visual inspection in the processing chain. Scanning transmission electron microscopy of siliceous zeolite material exhibits the above-mentioned obstructions and therefore serves as orientation and a test of our procedures. - Highlights: • Developed a new process for extracting more information from a series of STEM images. • An objective non-rigid registration process copes with distortions. • Images of zeolite Y show retrieval of all information available from the data set. • Quantitative measures of registration quality were implemented. • Applicable to any serially acquired data, e.g. STM, AFM, STXM, etc.
Beerends, J.G.; Schmidmer, C.; Berger, J.; Obermann, M.; Ullman, R.; Pomy, J.; Keyhl, M.
2013-01-01
In this and the companion paper Part I, the authors present the Perceptual Objective Listening Quality Assessment (POLQA), the third-generation speech quality measurement algorithm, standardized by the International Telecommunication Union in 2011 as Recommendation P.863. This paper describes the
Fadel, I.; van der Meijde, M.; Kerle, N.; Lauritsen, N.
2015-03-01
Non-uniqueness of satellite gravity interpretation has traditionally been reduced by using a priori information from seismic tomography models. This reduction in the non-uniqueness has been based on velocity-density conversion formulas or user interpretation of the 3D subsurface structures (objects) based on the seismic tomography models and then forward modelling these objects. However, this form of object-based approach has been done without a standardized methodology on how to extract the subsurface structures from the 3D models. In this research, a 3D object-oriented image analysis (3D OOA) approach was implemented to extract the 3D subsurface structures from geophysical data. The approach was applied on a 3D shear wave seismic tomography model of the central part of the East African Rift System. Subsequently, the extracted 3D objects from the tomography model were reconstructed in the 3D interactive modelling environment IGMAS+, and their density contrast values were calculated using an object-based inversion technique to calculate the forward signal of the objects and compare it with the measured satellite gravity. Thus, a new object-based approach was implemented to interpret and extract the 3D subsurface objects from 3D geophysical data. We also introduce a new approach to constrain the interpretation of the satellite gravity measurements that can be applied using any 3D geophysical model.
Rigid subsets of symplectic manifolds
Entov, Michael
2007-01-01
We show that there is an hierarchy of intersection rigidity properties of sets in a closed symplectic manifold: some sets cannot be displaced by symplectomorphisms from more sets than the others. We also find new examples of rigidity of intersections involving, in particular, specific fibers of moment maps of Hamiltonian torus actions, monotone Lagrangian submanifolds (following the previous work of P.Albers) as well as certain, possibly singular, sets defined in terms of Poisson-commutative subalgebras of smooth functions. In addition, we get some geometric obstructions to semi-simplicity of the quantum homology of symplectic manifolds. The proofs are based on the Floer-theoretical machinery of partial symplectic quasi-states.
Rigidity spectrum of Forbush decrease
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 Sakashita station. It is found that a spectral form of fractional-power type (P to the-gamma sub 1 (P+P sub c) to the -gamma sub2) is more suitable for the present purpose than that of power-exponential type or of power type with an upper limiting rigidity. The best fitted spectrum of 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.
Rigid body dynamics of mechanisms
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.
Dynamics of Rigid Bodies and Flexible Beam Structures
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...
Chandler, Susan M.; Lukesh, Gordon W.; Voelz, David; Basu, Santasri; Sjogren, Jon
2004-10-01
On September 1, 2003, Nukove Scientific Consulting, together with partner New Mexico State University (NMSU), began work on a Phase I Small Business Technology TRansfer (STTR) grant from the Air Force Office of Scientific Research (AFOSR). The purpose of the grant was to show the feasibility of taking Nukove's pointing estimation technique from a post-processing tool for estimation of laser system characteristics to a real-time tool usable in the field. Nukove's techniques for pointing, shape, and OCS estimation do not require an imaging sensor nor a target board, thus estimates may be made very quickly. To prove feasibility, Nukove developed an analysis tool RHINO (Real-time Histogram Interpretation of Numerical Observations) and successfully demonstrated the emulation of real-time, frame-by-frame estimation of laser system charcteristics, with data streamed into the tool and the estimates displayed as they are made. The eventual objective will be to use the frame-by-frame estimates to allow for feedback to a fielded system. Closely associated with this, NMSU has developed a laboratory testbed to illuminate test objects, collect the received photons, and stream the data into RHINO. The two coupled efforts clearly demonstrate the feasibility of real-time pointing control of a laser system.
Nandipati, Giridhar, E-mail: giridhar.nandipati@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States); Setyawan, Wahyu; Heinisch, Howard L. [Pacific Northwest National Laboratory, Richland, WA (United States); Roche, Kenneth J. [Pacific Northwest National Laboratory, Richland, WA (United States); Department of Physics, University of Washington, Seattle, WA 98195 (United States); Kurtz, Richard J. [Pacific Northwest National Laboratory, Richland, WA (United States); Wirth, Brian D. [University of Tennessee, Knoxville, TN (United States)
2015-07-15
The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.
Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.
2015-07-01
The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibits an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.
Understanding rigid body motion in arbitrary dimensions
Leyvraz, Francois
2014-01-01
Why would anyone wish to generalize the already unappetizing subject of rigid body motion to an arbitrary number of dimensions? At first sight, the subject seems to be both repellent and superfluous. The author will try to argue that an approach involving no specifically three-dimensional constructs is actually easier to grasp than the traditional one and might thus be generally useful to understand rigid body motion both in three dimensions and in the general case. Specific differences between the viewpoint suggested here and the usual one include the following: here angular velocities are systematically treated as antisymmetric matrices, a symmetric tensor $I$ quite different from the moment of inertia tensor plays a central role, whereas the latter is shown to be a far more complex object, namely a tensor of rank four. A straightforward way to define it is given. The Euler equation is derived and the use of Noether's theorem to obtain conserved quantities is illustrated. Finally the equation of motion for ...
Hamiltonian dynamics of several rigid bodies interacting with point vortices
Weissmann, Steffen
2013-01-01
We introduce a Hamiltonian description for the dynamics of several rigid bodies interacting with point vortices in an inviscid, incompressible fluid. We adopt the idea of Vankerschaver et al. (2009) to derive the Hamiltonian formulation via symplectic reduction of a canonical Hamiltonian system on a principle fibre bundle. On the reduced phase space we determine the magnetic symplectic form directly, without resorting to the machinery of mechanical connections on principle fibre bundles. We derive the equations of motion for the general case, and also for the special Lie-Poisson case of a single rigid body and zero total vorticity. Finally we give a partly degenerate Lagrangian formulation for the system.
Effects of Part- and Whole-Object Primes on Early MEG Responses to Mooney Faces and Houses.
Steinberg Lowe, Mara; Lewis, Gwyneth A; Poeppel, David
2016-01-01
Results from neurophysiological experiments suggest that face recognition engages a sensitive mechanism that is reflected in increased amplitude and decreased latency of the MEG M170 response compared to non-face visual targets. Furthermore, whereas recognition of objects (e.g., houses) has been argued to be based on individual features (e.g., door, window), face recognition may depend more on holistic information. Here we analyzed priming effects of component and holistic primes on 20 participants' early MEG responses to two-tone (Mooney) images to determine whether face recognition in this context engages "featural" or "configural" processing. Although visually underspecified, the Mooney images in this study elicited M170 responses that replicate the typical face vs. house effect. However, we found a distinction between holistic vs. component primes that modulated this effect dependent upon compatibility (match) between the prime and target. The facilitatory effect of holistic faces and houses for Mooney faces and houses, respectively, suggests that both Mooney face and house recognition-both low spatial frequency stimuli-are based on holistic information.
Simple Riemannian surfaces are scattering rigid
Wen, Haomin
2015-01-01
Scattering rigidity of a Riemannian manifold allows one to tell the metric of a manifold with boundary by looking at the directions of geodesics at the boundary. Lens rigidity allows one to tell the metric of a manifold with boundary from the same information plus the length of geodesics. There are a variety of results about lens rigidity but very little is known for scattering rigidity. We will discuss the subtle difference between these two types of rigidities and prove that they are equiva...
Non-rigid precession of magnetic stars
Lander, S K
2016-01-01
Stars are, generically, rotating and magnetised objects with a misalignment between their magnetic and rotation axes. Since a magnetic field induces a permanent distortion to its host, it provides effective rigidity even to a fluid star, leading to bulk stellar motion which resembles free precession. This bulk motion is however accompanied by induced interior velocity and magnetic field perturbations, which are oscillatory on the precession timescale. Extending previous work, we show that these quantities are described by a set of second-order perturbation equations featuring cross-terms scaling with the product of the magnetic and centrifugal distortions to the star. For the case of a background toroidal field, we reduce these to a set of differential equations in radial functions, and find a method for their solution. The resulting magnetic-field and velocity perturbations show complex multipolar structure and are strongest towards the centre of the star.
Geometry, rigidity, and group actions
Farb, Benson; Zimmer, Robert J
2011-01-01
The study of group actions is more than a hundred years old but remains to this day a vibrant and widely studied topic in a variety of mathematic fields. A central development in the last fifty years is the phenomenon of rigidity, whereby one can classify actions of certain groups, such as lattices in semi-simple Lie groups. This provides a way to classify all possible symmetries of important spaces and all spaces admitting given symmetries. Paradigmatic results can be found in the seminal work of George Mostow, Gergory Margulis, and Robert J. Zimmer, among others.The p
Wage rigidity and job creation
Christian Haefke; Marcus Sonntag; Thijs van Rens
2007-01-01
Recent research in macroeconomics emphasizes the role of wage rigidity in accounting for the volatility of unemployment fluctuations. We use worker-level data from the CPS to measure the sensitivity of wages of newly hired workers to changes in aggregate labor market conditions. The wage of new hires, unlike the aggregate wage, is volatile and responds almost one-to-one to changes in labor productivity. We conclude that there is little evidence for wage stickiness in the data. We also show, h...
Wage Rigidity and Job Creation
Haefke, Christian; Sonntag, Marcus; Rens, Thijs van
2012-01-01
Recent research in macroeconomics emphasizes the role of wage rigidity in accounting for the volatility of unemployment fluctuations. We use worker-level data from the CPS to measure the sensitivity of wages of newly hired workers to changes in aggregate labor market conditions. The wage of new hires, unlike the aggregate wage, is volatile and responds almost one-to-one to changes in labor productivity. We conclude that there is little evidence for wage stickiness in the data. We also show, h...
Wage Rigidity and Job Creation
Christian Haefke; Marcus Sonntag; Thijs van Rens
2012-01-01
Recent research in macroeconomics emphasizes the role of wage rigidity in ac- counting for the volatility of unemployment fluctuations. We use worker-level data from the CPS to measure the sensitivity of wages of newly hired workers to changes in aggregate labor market conditions. The wage of new hires, unlike the aggregate wage, is volatile and responds almost one-to-one to changes in labor productivity. We conclude that there is little evidence for wage stickiness in the data. We also show,...
Complications of rigid internal fixation.
Campbell, Chris A; Lin, Kant Y
2009-03-01
Over the past 20 years, there have been many advances in the development of bone fixation systems used in the practice of craniomaxillofacial surgery. As surgical practices have evolved, the complications of each technologic advance have changed accordingly. Interfragmentary instability of interosseous wiring has been replaced by the risk of exposure, infection, and palpability of plate and screw fixation systems. The improved rigidity of plate fixation requires anatomic alignment of fracture fragments. Failure to obtain proper alignment has led to the phenomenon known as "open internal fixation" of fracture fragments without proper reduction. The size of the plates has decreased to minimize palpability and exposure. However limitations in their application have been encountered due to the physiologic forces of the muscles of mastication and bone healing. In the pediatric population, the long-standing presence of plates in the cranial vault resulted in reports of transcranial migration and growth restriction. These findings led to the development of resorbable plating systems, which are associated with self-limited plate palpability and soft tissue inflammatory reactions. Any rigid system including these produces growth restriction in varying amounts. In this discussion, we review the reported complication rates of miniplating and microplating systems as well as absorptive plating systems in elective and traumatic craniofacial surgery.
Hsu, Shu-Wei
2010-01-01
We present a method for directly modeling piles of objects in multi-body simulations. Piles of objects represent some of the more interesting, but also most time-consuming portion of simulation. We propose a method for reducing computation in many of these situations by explicitly modeling the piles that the objects may form into. By modeling pile behavior rather than the behavior of all individual objects, we can achieve realistic results in less time, and without directly modeling the frictional component that leads to desired pile shapes. Our method is simple to implement and can be easily integrated with existing rigid body simulations. We observe notable speedups in several rigid body examples, and generate a wider variety of piled structures than possible with strict impulse-based simulation. © 2010 ACM.
FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION
WU Long-hua; YANG Xiao-li
2011-01-01
The bending rigidity of submerged vegetation is closely related with vegetative drag force.This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation.Based on the dimensional analysis method,the factors influencing the bending rigidity of individual submerged vegetation were analyzed.The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation,and a relative bending rigidity expression for submerged vegetation was obtained by means of multiple linear regression method.The results show that the submerged vegetation has three states under different inflow conditions,and the each critical relative bending rigidity of individual submerged vegetation was determined for the different states of submerged vegetation.
Rigid Ideals and Radicals of Ore Extensions
Chan Yong Hong; Tai Keun Kwak; S. Tariq Rizvi
2005-01-01
For an endomorphism σ of a ring R, Krempa called σ a rigid endomorphism if aσ(a) = 0 implies a= 0 for a ∈ R. A ring R is called rigid if there exists a rigid endomorphism of R. In this paper, we extend the σ-rigid property of a ring R to an ideal of R. For a σ-ideal Ⅰ of a ring R, we call Ⅰ a σ-rigid ideal if aσ(a) ∈Ⅰ implies a ∈Ⅰ for a ∈ R. We characterize σ-rigid ideals and study related properties. The connections of the prime radical and the upper nil radical of R with the prime radical and the upper nil radical of the Ore extension R[x; σ, δ], respectively, are also investigated.
Toxicity evaluation and hazard review for Rigid Foam
Archuleta, M.M.; Stocum, W.E.
1994-02-01
Rigid Foam is a chemical delay foam used to completely encapsulate an object or to block access to an area. Prior studies have indicated that the final foam product is essentially non-toxic. The purpose of this study was to evaluate and summarize the current chemical and toxicological data available on the components of Rigid Foam and to update the information available on the toxicity of the final Rigid Foam product. Since the possibility exists for a partial deployment of Rigid Foam where only one of the components is released, this study also examined the toxicity of its chemical constituents. Rigid Foam is composed of an {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} Component. The {open_quotes}A{close_quotes} component is primarily a polymeric isocyanate and the {open_quotes}B{close_quotes} component is a mixture of polyols. In addition to the primary constituents, dichlorodifluoromethane and trichlorofluoromethane are present as blowing agents along with catalysts and silicone surfactants necessary for foaming. The pre-deployed {open_quotes}A{close_quotes} and {open_quotes}B{close_quotes} components are stored in separate vessels and are brought together in static mixing nozzles for dispersal. The results of this evaluation indicate that a completely deployed Rigid Foam under normal conditions is essentially non-toxic as determined previously. However, in the event of a partial deployment or deployment of an individual component directly at an unprotected individual, the degree of hazard is increased due to the toxic and corrosive nature of the individual constituents. The health hazard would depend on the properties of the material to which the person was exposed.
Hansson, L F; Norheim, O F; Ruyter, K W
1994-08-01
This article is an attempt to evaluate the Oregon plan from the perspective of a Scandinavian national health care system. The Nordic welfare states are marked by a strong emphasis on equality. As an example of an egalitarian system we present the Norwegian health care model in part one. In part two, the arguments in favor of a one tier system in Norway are presented and compared to Oregon's two tier system. Although we argue, in part three, that a comparison of the degree of explicitness in the prioritization process shows that Norway has much to learn from Oregon, we do believe that the Norwegian system has some attractive elements that may function as an important corrective. In part four we present the Norwegian Guidelines for priority-setting and discuss the weight assigned to the severity of disease criterion. It is argued that the exclusion of information about the severity of disease partly explains the counterintuitive ranking of treatment-condition pairs in Oregon's initial method based on the principle of health maximization. A normative analysis of the conflicting norms of efficiency and equality of results is called for. The final part of the paper is devoted to the problem of rigidity. Henry J. Aaron has argued that the Oregon system is insensitive to inter-individual variations within each diagnosis-treatment pair. This objection is a severe one, since the system might end up treating patients unfairly on the individual level. To overcome this problem, we suggest a selection rule that should be more capable of dealing with the problem of rigidity.
Rigidity and flexibility of biological networks
Gaspar, Merse E
2012-01-01
The network approach became a widely used tool to understand the behaviour of complex systems in the last decade. We start from a short description of structural rigidity theory. A detailed account on the combinatorial rigidity analysis of protein structures, as well as local flexibility measures of proteins and their applications in explaining allostery and thermostability is given. We also briefly discuss the network aspects of cytoskeletal tensegrity. Finally, we show the importance of the balance between functional flexibility and rigidity in protein-protein interaction, metabolic, gene regulatory and neuronal networks. Our summary raises the possibility that the concepts of flexibility and rigidity can be generalized to all networks.
Rigidizing Inflatable Deployable Dwelling (RIDD) Project
National Aeronautics and Space Administration — By combining thin thermoplastic films, woven Vectran reinforcements, and heat a reliable, deployable, rigidizing space habitat can be created. Although much research...
Luigi Boschetti
2012-09-01
Full Text Available According to literature and despite their commercial success, state-of-the-art two-stage non-iterative geographic object-based image analysis (GEOBIA systems and three-stage iterative geographic object-oriented image analysis (GEOOIA systems, where GEOOIA/GEOBIA, remain affected by a lack of productivity, general consensus and research. To outperform the Quality Indexes of Operativeness (OQIs of existing GEOBIA/GEOOIA systems in compliance with the Quality Assurance Framework for Earth Observation (QA4EO guidelines, this methodological work is split into two parts. Based on an original multi-disciplinary Strengths, Weaknesses, Opportunities and Threats (SWOT analysis of the GEOBIA/GEOOIA approaches, the first part of this work promotes a shift of learning paradigm in the pre-attentive vision first stage of a remote sensing (RS image understanding system (RS-IUS, from sub-symbolic statistical model-based (inductive image segmentation to symbolic physical model-based (deductive image preliminary classification capable of accomplishing image sub-symbolic segmentation and image symbolic pre-classification simultaneously. In the present second part of this work, a novel hybrid (combined deductive and inductive RS-IUS architecture featuring a symbolic deductive pre-attentive vision first stage is proposed and discussed in terms of: (a computational theory (system design, (b information/knowledge representation, (c algorithm design and (d implementation. As proof-of-concept of symbolic physical model-based pre-attentive vision first stage, the spectral knowledge-based, operational, near real-time, multi-sensor, multi-resolution, application-independent Satellite Image Automatic Mapper™ (SIAM™ is selected from existing literature. To the best of these authors’ knowledge, this is the first time a symbolic syntactic inference system, like SIAM™, is made available to the RS community for operational use in a RS-IUS pre-attentive vision first stage
Nonlinear dynamics mathematical models for rigid bodies with a liquid
Lukovsky, Ivan A
2015-01-01
This book is devoted to analytically approximate methods in the nonlinear dynamics of a rigid body with cavities partly filled by liquid. It combines several methods and compares the results with experimental data. It is useful for experienced and early-stage readers interested in analytical approaches to fluid-structure interaction problems, the fundamental mathematical background and modeling the dynamics of such complex mechanical systems.
Assumptions and Axioms: Mathematical Structures to Describe the Physics of Rigid Bodies
Butler, Philip H; Renaud, Peter F
2010-01-01
This paper challenges some of the common assumptions underlying the mathematics used to describe the physical world. We start by reviewing many of the assumptions underlying the concepts of real, physical, rigid bodies and the translational and rotational properties of such rigid bodies. Nearly all elementary and advanced texts make physical assumptions that are subtly different from ours, and as a result we develop a mathematical description that is subtly different from the standard mathematical structure. Using the homogeneity and isotropy of space, we investigate the translational and rotational features of rigid bodies in two and three dimensions. We find that the concept of rigid bodies and the concept of the homogeneity of space are intrinsically linked. The geometric study of rotations of rigid objects leads to a geometric product relationship for lines and vectors. By requiring this product to be both associative and to satisfy Pythagoras' theorem, we obtain a choice of Clifford algebras. We extend o...
Some more Non-arithmetic Rigid groups
Lubotzky, Alexander
2011-01-01
In "Non arithmetic super rigid groups: counter examples to Platonov's conjecture" Bass and Lubotzky gave a counter example to Platonov's conjecture by presenting an example of a linear group with super-rigidity which is not an arithmetic lattice. In this note, a much richer class of such groups is presented with a somewhat simpler proof.
Are better conductors more rigid?
Eom, Young-Ho; Jeong, Hawoong; Orland, Henri; Yi, Juyeon
2006-10-01
The variation of the bending stiffness of various materials is studied from the point of view of the electronic band characteristics. As far as the electronically generated bending stiffness κe (which we refer to as electro-stiffness) is concerned, the relevant factors are the orbital overlap t, the gap width u between the valence band and the conduction band, and the electron filling fraction γ. A perturbative calculation leads to the approximate expression κe ~ t2/√u2 + t2. This shows that materials with a large overlap and narrow band gap should be stiffer. The electro-stiffness also depends on the electron filling-fraction. We find that κe(γ) <= κe(1/2). These kinds of behavior are confirmed by numerical calculations. In addition, we study the variation in the projected length of flexible molecules under a voltage bias. The nonlinear variation of the bending rigidity is shown to give rise to a length contraction or dilation, depending on the voltage bias.
Deformable registration of multi-modal data including rigid structures
Huesman, Ronald H.; Klein, Gregory J.; Kimdon, Joey A.; Kuo, Chaincy; Majumdar, Sharmila
2003-05-02
Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result
Héraud, Jean-Loup; Lautesse, Philippe; Ferlin, Fabrice; Chabot, Hugues
2017-05-01
Our work extends a previous study of epistemological presuppositions in teaching quantum physics in upper scientific secondary school in France. Here, the problematic reference of quantum theory's concepts is treated at the ontological level (the counterintuitive nature of quantum objects). We consider the approach of using narratives describing possible alternative worlds to address the issue. These possible worlds are based on the counterfactual logic developed in the work of D. Lewis. We will show that the narratives written by G. Gamow describe such possible worlds. Some parts of these narratives are found in textbooks in France. These worlds are governed by laws similar to but importantly different from those in our real world. They allow us to materialize properties inaccessible to everyday experience. In this sense, these fiction stories make ontological propositions concerning the nature and structure of the fundamental elements of our physical universe.
Flow past 2-D Hemispherical Rigid Canopies
Carnasciali, Maria-Isabel
2013-11-01
The flow past a 2-dimensional rigid hemispherical shape is investigated using PIV. Flow field measurements and images were generated with the use of a Thermoflow® apparatus. Results of this study are compared to prior work (APS DFD 2012 Session E9.00003) which employed CFD to investigate the flow in the near wake of hemispherical parachutes. The various sized gaps/open areas were positioned at distinct locations. The work presented here is part of a larger research project to investigate flow fields in deceleration devices and parachutes. Understanding the pitch-stability of parachutes is essential for accurate design and implementation of these deceleration devices but they present a difficult system to analyze. The flexibility of the parachute fabric results in large variations in the parachute geometry leading to complex fluid-structure interactions. Such flow, combined with flow through gaps and open areas, has been postulated to shed alternating vortices causing pitching/oscillations of the canopy. The results presented provide some insight into which geometric features affect vortex shedding and may enable the redesign of the baseline parachute to minimize instabilities.
The theory of pseudo-rigid bodies
Cohen, Harley
1988-01-01
This monograph concerns the development, analysis, and application of the theory of pseudo-rigid bodies. It collects together our work on that subject over the last five years. While some results have appeared else where, much of the work is new. Our objective in writing this mono graph has been to present a new theory of the deformation of bodies, one that has not only a firm theoretical basis, but also the simplicity to serve as an effective tool in practical problems. Consequently, the main body of the treatise is a multifaceted development of the theory, from foundations to explicit solutions to linearizations to methods of approximation. The fact that this variety of aspects, each examined in considerable detail, can be collected together in a single, unified treat ment gives this theory an elegance that we feel sets it apart from many others. While our goal has always been to give a complete treatment of the theory as it now stands, the work here is not meant to be definitive. Theories are not ent...
Algorithms for Graph Rigidity and Scene Analysis
Berg, Alex Rune; Jordán, Tibor
2003-01-01
We investigate algorithmic questions and structural problems concerning graph families defined by `edge-counts'. Motivated by recent developments in the unique realization problem of graphs, we give an efficient algorithm to compute the rigid, redundantly rigid, M-connected, and globally rigid...... by showing that 2d-connected bipartite graphs are d-tight. We give a new algorithm for finding a maximal d-sharp subgraph. We also answer a question of Imai and show that finding a maximum size d-sharp subgraph is NP-hard....
A Numerical Method for Rigid-plastic FEM Analysis Basing on Mathematical Programming
Li Di; Lin Zhongqin; Chen Guanlong; Zhang Weigang; Li Shuhui
2004-01-01
The rigid-plastic analysis of mental forming simulation is formulated as a discrete nonlinear mathematical programming problem with equality and inequality constraints by means of the finite element technique. An iteration algorithm is used to solve this formulation, which distinguishes the integration points of the rigid zones and the plastic zones and solves a series of the quadratic programming to overcome the difficulties caused by the nonsmoothness and the nonlinearity of the objective function. This method has been used to carry out the rigid-plastic FEM analysis. An example is given to demonstrate the effectiveness of this method.
Characterization of Bird Impacts on a Rigid Plate: Part 1
1975-01-01
velocity 40 1. 27cm off center of impact. Prscinng page Madh vii r _ _ AFrFDL-TR-IS-5 LIST OF ILLUSTRATIONS (CON TD ) FIGURE PAGE 21. Impulse...velocity 234 rn/s ! I Shot No. 5190; velocity 129 m/1" B-9 AFFDL-TR-75-S APPENDIX C BIRD IMPACT CINE SEQUENCES AFFDL-TR-75-5 museu. woman nams.UUS Nae womenU
The ‘twin paradox’ in relativistic rigid motion
Ben-Ya'acov, Uri
2016-09-01
Relativistic rigid motion suggests a new version for the so-called ‘twin paradox’, comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being rigid, is simultaneously at rest, the twins’ ages, measured as the proper-times along their individual world lines, are different when they are located at remote parts of the spaceship. The age, or proper-time, difference depends on the distance at rest between the astronauts and the rapidity difference between start to end. The relation of the age difference with the relative Doppler shift of light signals transmitted between the astronauts and implications for the possibility to assign a common age (proper-time) to complex, spatially extended, relativistic systems are also discussed.
Yong Wang; Jian Kang
2015-01-01
In traditional inverse synthetic aperture radar (ISAR) imaging of moving targets with rotational parts, the micro-Doppler (m-D) effects caused by the rotational parts influence the quality of the radar images. Recently, L. Stankovic proposed an m-D removal method based on L-statistics, which has been proved effective and simple. The algorithm can extract the m-D effects according to different behaviors of signals induced by rotational parts and rigid bodies in time-frequency (T-F) domain. However, by removing m-D effects, some useful short time Fourier transform (STFT) samples of rigid bodies are also extracted, which induces the side lobe problem of rigid bodies. A parameter estimation method for rigid bodies after m-D removal is proposed, which can accurately re-cover rigid bodies and avoid the side lobe problem by only using m-D removal. Simulations are given to validate the effectiveness of the proposed method.
Effect of rigid cervical collar on tracheal intubation using Airtraq®
Padmaja Durga; Chiranjeevi Yendrapati; Geeta Kaniti; Narmada Padhy; Kiran Kumar Anne; Gopinath Ramachandran
2014-01-01
Background and Aims: Cervical spine immobilisation with rigid cervical collar imposes difficulty in intubation. Removal of the anterior part of the collar may jeopardize the safety of the cervical spine. The effect of restricted mouth opening and cervical spine immobilisation that result from the application of rigid cervical collar on intubation using Airtraq ® was evaluated. Methods: Seventy healthy adults with normal airways included in the study were intubated Using Airtraq® with (group C...
Ferry Kwakkel
2011-12-01
Full Text Available Given a closed Riemannian manifold (M, g, i.e. compact and boundaryless, there is a partition of its tangent bundle TM = ∪iΣi called the focal decomposition of TM. The sets Σi are closely associated to focusing of geodesics of (M, g, i.e. to the situation where there are exactly i geodesic arcs of the same length joining points p and q in M. In this note, we study the topological structure of the focal decomposition of a closed Riemannian manifold and its relation with the metric structure of the manifold. Our main result is that flat n-tori, n > 2, are focally rigid in the sense that if two flat tori are focally equivalent then the tori are isometric up to rescaling. The case n = 2 was considered before by F. Kwakkel.Dada uma variedade Riemanniana (M, g fechada, isto é, compacta e sem bordo, existe uma partição de seu fibrado tangente TM = ∪iΣi chamada decomposição focal de TM. Os conjuntos Σi estão intimamente associados ao modo como focalizam as geodésicas de (M,g, isto é, à situação em que existem exatamente i arcos de geodésica de mesmo comprimento unindo pontos p e q em M. Nesta nota, estudamos a estrutura topológica da decomposição focal de uma variedade Riemanniana fechada e sua relação com a estrutura métrica de M. Nosso principal resultado é que n-toros planos, n > 2, são focalmente rigidos, isto é, se dois toros planos são focalmente equivalentes, então os dois toros são isométricos módulo mudança de escala. O caso n = 2 foi considerado anteriormente por F. Kwakkel.
Public policies targeting labour market rigidities
Andreea Claudia ŞERBAN
2013-01-01
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 tar...
Using Elimination Theory to construct Rigid Matrices
Kumar, Abhinav; Patankar, Vijay M; N, Jayalal Sarma M
2009-01-01
The rigidity of a matrix A for target rank r is the minimum number of entries of A that must be changed to ensure that the rank of the altered matrix is at most r. Since its introduction by Valiant (1977), rigidity and similar rank-robustness functions of matrices have found numerous applications in circuit complexity, communication complexity, and learning complexity. Almost all nxn matrices over an infinite field have a rigidity of (n-r)^2. It is a long-standing open question to construct infinite families of explicit matrices even with superlinear rigidity when r=Omega(n). In this paper, we construct an infinite family of complex matrices with the largest possible, i.e., (n-r)^2, rigidity. The entries of an nxn matrix in this family are distinct primitive roots of unity of orders roughly exp(n^4 log n). To the best of our knowledge, this is the first family of concrete (but not entirely explicit) matrices having maximal rigidity and a succinct algebraic description. Our construction is based on elimination...
Helmich, Ingo; Holle, Henning; Rein, Robert; Lausberg, Hedda
2015-04-01
Divergent findings exist whether left and right hemispheric pre- and postcentral cortices contribute to the production of tool use related hand movements. In order to clarify the neural substrates of tool use demonstrations with tool in hand, tool use pantomimes without tool in hand, and body-part-as-object presentations of tool use (BPO) in a naturalistic mode of execution, we applied functional Near InfraRed Spectroscopy (fNIRS) in twenty-three right-handed participants. Functional NIRS techniques allow for the investigation of brain oxygenation during the execution of complex hand movements with an unlimited movement range. Brain oxygenation patterns were retrieved from 16 channels of measurement above pre- and postcentral cortices of each hemisphere. The results showed that tool use demonstration with tool in hand leads to increased oxygenation as compared to tool use pantomimes in the left hemispheric somatosensory gyrus. Left hand executions of the demonstration of tool use, pantomime of tool use, and BPO of tool use led to increased oxygenation in the premotor and somatosensory cortices of the left hemisphere as compared to right hand executions of either condition. The results indicate that the premotor and somatosensory cortices of the left hemisphere constitute relevant brain structures for tool related hand movement production when using the left hand, whereas the somatosensory cortex of the left hemisphere seems to provide specific mental representations when performing tool use demonstrations with the tool in hand.
Sequential Non-Rigid Structure from Motion Using Physical Priors.
Agudo, Antonio; Moreno-Noguer, Francesc; Calvo, Begona; Montiel, Jose M Martinez
2016-05-01
We propose a new approach to simultaneously recover camera pose and 3D shape of non-rigid and potentially extensible surfaces from a monocular image sequence. For this purpose, we make use of the Extended Kalman Filter based Simultaneous Localization And Mapping (EKF-SLAM) formulation, a Bayesian optimization framework traditionally used in mobile robotics for estimating camera pose and reconstructing rigid scenarios. In order to extend the problem to a deformable domain we represent the object's surface mechanics by means of Navier's equations, which are solved using a Finite Element Method (FEM). With these main ingredients, we can further model the material's stretching, allowing us to go a step further than most of current techniques, typically constrained to surfaces undergoing isometric deformations. We extensively validate our approach in both real and synthetic experiments, and demonstrate its advantages with respect to competing methods. More specifically, we show that besides simultaneously retrieving camera pose and non-rigid shape, our approach is adequate for both isometric and extensible surfaces, does not require neither batch processing all the frames nor tracking points over the whole sequence and runs at several frames per second.
A Convertible Spinal Orthosis for Controlled Torso Rigidity
Nicole I. Kern
2013-01-01
Full Text Available A traditional spinal orthosis in conjunction with a hip-knee-ankle-foot orthosis (HKAFO improves posture in persons with paraplegia during standing and walking. It also limits the wearer's range of motion when worn during other activities, such as vehicle transfer or sitting and reaching for objects. In order to regain full torso flexibility the user would need to remove the spinal orthosis which can be arduous and time consuming. A Convertible Spinal Orthosis (CSO that allows the user to switch between Locked rigid torso support and Unlocked free motion has been designed, fabricated and tested. It shows promise for increasing functionality, wear time and subject comfort. Analysis of movement has been performed with an able-bodied and a paraplegic subject wearing a rigid spinal orthosis, the CSO in both states, and without any bracing. Configuration state had the most impact on lateral bending. Mean values for the paraplegic subject of 27°, 38°, 48°, and 48° and for the able-bodied subject of 22°, 26°, 48°, and 45° were found for lateral bending of the upper torso relative to the thighs in the Rigid, Locked, Unlocked, and No-Brace states, respectively.
Relation between European and national identity and rigidity as a personality trait
Janičić Bojan B.
2005-01-01
Full Text Available The research presented in this paper is a part of the project “Condition, Factors and Development of European Identity in Serbia and Montenegro”, which started in 2002 with the financial support of the Ministry for Science and Protection of Environment of the Republic of Serbia. The research studied the relation between certain kinds of social identity ( European, i.e. national identity on the one hand, and the degree of rigidity of the subjects on the other. The sample consisted of 2685 inhabitants of Serbia and Montenegro, of both sexes, different levels of education and 18 to 43 years old. European, i.e. national identity was measured with the questionnaire EUROID2002, which consisted of 36 items related to different aspects of social identity. Factor analysis singled out five factors of social identity: pro-European orientation, advocating the preservation of national identity, confronting traditional values and technological civilization, globalization as a threatening factor for small and poor nations, and exclusive national attachment. Rigidity of the subjects was determined with the application of the RG-2 questionnaire which consists of 30 items related to the rigidity of thought in various life situations. Factor analysis singled out two factors of rigidity: rigidity toward oneself and others, as well as rigidity in one’s life habits. The relation between social identity and rigidity was determined with the technique of canonical analysis. Two significant canonical roots were singled out: the first canonical root includes two aspects of rigidity which were positively related to the factors implying a strongly pronounced national identity ( advocating the preservation of national identity and exclusive national attachment . The second canonical root indicates a positive relation between rigidity in life habits and traditional standpoints and fear of globalization.
Water retention of rigid soils from a two-factor model for clay
Chertkov, V Y
2014-01-01
Water retention is one of the key soil characteristics. Available models of soil water retention relate to the curve-fitting type. The objective of this work is to suggest a physical model of water retention (drying branch) for soils with a rigid matrix. "Physical" means the prediction based on the a priori measured or estimated soil parameters with a clear physical meaning. We rely on the two-factor model of clay that takes into account the factors of capillarity and shrinkage. The key points of the model to be proposed are some weak pseudo shrinkage that the rigid soils demonstrate according to their experimental water retention curves, and some specific properties of the rigid grain matrix. The three input parameters for prediction of soil water retention with the rigid grain matrix include inter-grain porosity, as well as maximum and minimum grain sizes. The comparison between measured and predicted sand water retention curves for four different sands is promising.
21 CFR 876.3630 - Penile rigidity implant.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Penile rigidity implant. 876.3630 Section 876.3630...) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Prosthetic Devices § 876.3630 Penile rigidity implant. (a) Identification. A penile rigidity implant is a device that consists of a pair of semi-rigid rods implanted in...
49 CFR 178.706 - Standards for rigid plastic IBCs.
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for rigid plastic IBCs. 178.706 Section... PACKAGINGS IBC Performance-Oriented Standards § 178.706 Standards for rigid plastic IBCs. (a) The provisions in this section apply to rigid plastic IBCs intended to contain solids or liquids. Rigid plastic...
The rigidity transition in random graphs
Kasiviswanathan, Shiva Prasad; Theran, Louis
2010-01-01
As we add rigid bars between points in the plane, at what point is there a giant (linear-sized) rigid component, which can be rotated and translated, but which has no internal flexibility? If the points are generic, this depends only on the combinatorics of the graph formed by the bars. We show that if this graph is an Erdos-Renyi random graph G(n,c/n), then there exists a sharp threshold for a giant rigid component to emerge. For c c_2, w.h.p. there is a giant rigid component. The constant c_2 \\approx 3.588 is the threshold for 2-orientability, discovered independently by Fernholz and Ramachandran and Cain, Sanders, and Wormald in SODA'07. We also give quantitative bounds on the size of the giant rigid component when it emerges, proving that it spans a (1-o(1))-fraction of the vertices in the (3+2)-core. Informally, the (3+2)-core is maximal induced subgraph obtained by starting from the 3-core and then inductively adding vertices with 2 neighbors in the graph obtained so far.
Flexible implementation of rigid solar cell technologies.
Hollowell, Andrew E.
2010-08-01
As a source of clean, remote energy, photovoltaic (PV) systems are an important area of research. The majority of solar cells are rigid materials with negligible flexibility. Flexible PV systems possess many advantages, such as being transportable and incorporable on diverse structures. Amorphous silicon and organic PV systems are flexible; however, they lack the efficiency and lifetime of rigid cells. There is also a need for PV systems that are light weight, especially in space and flight applications. We propose a solution to this problem by arranging rigid cells onto a flexible substrate creating efficient, light weight, and flexible devices. To date, we have created a working prototype of our design using the 1.1cm x 1cm Emcore cells. We have achieved a better power to weight ratio than commercially available PowerFilm{reg_sign}, which uses thin film silicon yielding .034W/gram. We have also tested our concept with other types of cells and verified that our methods are able to be adapted to any rigid solar cell technology. This allows us to use the highest efficiency devices despite their physical characteristics. Depending on the cell size we use, we can rival the curvature of most available flexible PV devices. We have shown how the benefits of rigid solar cells can be integrated into flexible applications, allowing performance that surpasses alternative technologies.
Rigidity loss in disordered network materials
Ellenbroek, Wouter G.; Hagh, Varda F.; Kumar, Avishek; Thorpe, M. F.; van Hecke, Martin
Weakly jammed sphere packings show a very peculiar elasticity, with a ratio of compression modulus to shear modulus that diverges as the number of contacts approaches the minimum required for rigidity. Creating artificial isotropic network materials with this property is a challenge: so far, the least elaborate way to generate them is to actually simulate weakly compressed repulsive spheres. The next steps in designing such networks hinge upon a solid understanding of what properties of the sphere-packing derived network are essential for its elasticity. We elucidate the topological aspects of this question by comparing the rigidity transition in these networks to that in other random spring network models, including the common bond-diluted triangular net and a self-stress-free variant of that. We use the pebble game algorithm for identifying rigid clusters in mechanical networks to demonstrate that the marginally rigid state in sphere packings is perfectly isostatic everywhere, and the addition or removal of a single bond creates a globally stressed or globally floppy network, respectively. By contrast, the other classes of random network random networks show a more localized response to addition and removal of bonds, and, correspondingly, a more gradual rigidity transition.
Subsea rigid jumper design and ⅤⅣ fatigue evaluation
Wang Jun
2013-01-01
The purpose of this paper is to present a design procedure for subsea rigid jumper system including strength and fatigue analysis.Special attention gives to a methodology based on DNV-RP-F105 to evaluate jumper fatigue damage caused by vortex induced vibration (ⅤⅣ).Jumper strength analysis is to determine the jumper configuration which can accommodate various load conditions and all possible span lengths driven by installation tolerances of connected subsea structures.Fatigue analysis includes two parts:thermal fatigue and ⅤⅣ fatigue.This paper presents the procedure of ⅤⅣ fatigue damage calculation.An example is given to illustrate above methodologies.
Torsional rigidity of submanifolds with controlled geometry
Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente
2009-01-01
We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds ^m$ with controlled radial mean curvature in ambient Riemannian manifolds ^n$ with a pole $ and with sectional curvatures bounded from above and from below, respectively. These bounds are given...... in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped product model spaces. Our main results are obtained using methods from previously established isoperimetric inequalities, as found in e.g. [MP4] and [MP5]. As in [MP4] we also characterize the geometry...... of those situations in which the bounds for the torsional rigidity are actually attained and study the behavior at infinity of the so-called geometric average of the mean exit time for Brownian motion....
Measuring the Acceleration of a Rigid Body
Peter G. Martin
1998-01-01
Full Text Available Two methods to measure the six-degree-of-freedom acceleration of a point on a rigid body are presented. The first, referred to as the periphery scheme, makes use of three clusters of accelerometers mounted orthogonal to each other and coincident with the axes of the point. One of the clusters consists of the three accelerometers attached to a cube-shaped triaxial angular rate sensor (ARS. The second method, called the compact cube scheme, uses a single 3-accelerometer/ARS cluster that may be mounted anywhere on the rigid body. During impact tests with an instrumented rigid body, both methods produced measurements that were highly correlated near the time of peak acceleration. Whereas the compact cube scheme was more economical and easier to implement, the periphery scheme produced results that were less disrupted by instrument signal errors and noisy environments.
On Saturnian cosmic ray cutoff rigidities
Sauer, H. H.
1980-03-01
It has been determined that Saturn possesses a relatively pure dipolar magnetic field through magnetometer measurements made by Ness et al. (1979, private comm.) and Smith et al. (1979). The paper briefly outlines the dipole geomagnetic cutoff theory and demonstrates the scaling required for its applicability to energetic particle measurements in the vicinity of Saturn. Since the cutoff rigidity is a function of viewing direction, the effective cutoff rigidity must be determined as an integration over the finite viewing angle of a physical detector.
Generic Rigidity Matroids with Dilworth Truncations
Tanigawa, Shin-ichi
2010-01-01
We prove that the linear matroid that defines generic rigidity of $d$-dimensional body-rod-bar frameworks (i.e., structures consisting of disjoint bodies and rods mutually linked by bars) can be obtained from the union of ${d+1 \\choose 2}$ graphic matroids by applying variants of Dilworth truncation $n_r$ times, where $n_r$ denotes the number of rods. This leads to an alternative proof of Tay's combinatorial characterizations of generic rigidity of rod-bar frameworks and that of identified body-hinge frameworks.
Rigid origami vertices: conditions and forcing sets
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.
Thin structured rigid body for acoustic absorption
Starkey, T. A.; Smith, J. D.; Hibbins, A. P.; Sambles, J. R.; Rance, H. J.
2017-01-01
We present a thin acoustic metamaterial absorber, comprised of only rigid metal and air, that gives rise to near unity absorption of airborne sound on resonance. This simple, easily fabricated, robust structure comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel.
Higgins, I V; Stringer, S M
2011-03-25
This paper investigates how the visual areas of the brain may learn to segment the bodies of humans and other animals into separate parts. A neural network model of the ventral visual pathway, VisNet, was used to study this problem. In particular, the current work investigates whether independent motion of body parts can be sufficient to enable the visual system to learn separate representations of them even when the body parts are never seen in isolation. The network was shown to be able to separate out the independently moving body parts because the independent motion created statistical decoupling between them.
Perception of shape and space across rigid transformations.
Schmidt, Filipp; Spröte, Patrick; Fleming, Roland W
2016-09-01
Objects in our environment are subject to manifold transformations, either of the physical objects themselves or of the object images on the retina. Despite drastic effects on the objects' physical appearances, we are often able to identify stable objects across transformations and have strong subjective impressions of the transformations themselves. This suggests the brain is equipped with sophisticated mechanisms for inferring both object constancy, and objects' causal history. We employed a dot-matching task to study in geometrical detail the effects of rigid transformations on representations of shape and space. We presented an untransformed 'base shape' on the left side of the screen and its transformed counterpart on the right (rotated, scaled, or both). On each trial, a dot was superimposed at a given location on the contour (Experiment 1) or within and around the shape (Experiment 2). The participant's task was to place a dot at the corresponding location on the right side of the screen. By analyzing correspondence between responses and physical transformations, we tested for object constancy, causal history, and transformation of space. We find that shape representations are remarkably robust against rotation and scaling. Performance is modulated by the type and amount of transformation, as well as by contour saliency. We also find that the representation of space within and around a shape is transformed in line with the shape transformation, as if shape features establish an object-centered reference frame. These findings suggest robust mechanisms for the inference of shape, space and correspondence across transformations.
Occlusion Handling in Videos Object Tracking: A Survey
Lee, B. Y.; Liew, L. H.; Cheah, W. S.; Wang, Y. C.
2014-02-01
Object tracking in video has been an active research since for decades. This interest is motivated by numerous applications, such as surveillance, human-computer interaction, and sports event monitoring. Many challenges related to tracking objects still remain, this can arise due to abrupt object motion, changing appearance patterns of objects and the scene, non-rigid object structures and most significant are occlusion of tracked object be it object-to-object or object-to-scene occlusions. Generally, occlusion in object tracking occur under three situations: self-occlusion, inter-object occlusion by background scene structure. Self-occlusion occurs most frequently while tracking articulated objects when one part of the object occludes another. Inter-object occlusion occurs when two objects being tracked occlude each other whereas occlusion by the background occurs when a structure in the background occludes the tracked objects. Typically, tracking methods handle occlusion by modelling the object motion using linear and non-linear dynamic models. The derived models will be used to continuously predicting the object location when a tracked object is occluded until the object reappears. Example of these method are Kalman filtering and Particle filtering trackers. Researchers have also utilised other features to resolved occlusion, for example, silhouette projections, colour histogram and optical flow. We will present some result from a previously conducted experiment when tracking single object using Kalman filter, Particle filter and Mean Shift trackers under various occlusion situation in this paper. We will also review various other occlusion handling methods that involved using multiple cameras. In a nutshell, the goal of this paper is to discuss in detail the problem of occlusion in object tracking and review the state of the art occlusion handling methods, classify them into different categories, and identify new trends. Moreover, we discuss the important
Lopdrup-Hjorth, Thomas
2015-01-01
This paper explores the erosion and problematization of ‘the organization’ as a demarcated entity. Utilizing Foucault's reflections on ‘state-phobia’ as a source of inspiration, I show how an organization-phobia has gained a hold within Organization Theory (OT). By attending to the history...... of this organization-phobia, the paper argues that OT has become increasingly incapable of speaking about its core object. I show how organizations went from being conceptualized as entities of major importance to becoming theoretically deconstructed and associated with all kinds of ills. Through this history......, organizations as distinct entities have been rendered so problematic that they have gradually come to be removed from the center of OT. The costs of this have been rather significant. Besides undermining the grounds that gave OT intellectual credibility and legitimacy to begin with, the organization-phobia...
Delayed Equation for Charged Rigid Nonrelativistic Ball
Vlasov, A A
2002-01-01
Simple expression for self-force acting on radiating rigid charged ball is derived (Sommerfeld ball). It is shown that appropriate delayed equation of motion has solutions in general differ from that for Sommerfeld sphere - there are no "radiationless" solutions, but there are oscillating without damping solutions though self-force has nonzero value.
Rigid body dynamics on the Poisson torus
Richter, Peter H.
2008-11-01
The theory of rigid body motion with emphasis on the modifications introduced by a Cardan suspension is outlined. The configuration space is no longer SO(3) but a 3-torus; the equivalent of the Poisson sphere, after separation of an angular variable, is a Poisson torus. Iso-energy surfaces and their bifurcations are discussed. A universal Poincaré section method is proposed.
Viscoelasticity of suspensions of long, rigid rods
Dhont, Jan K.G.; Briels, W.J.
2003-01-01
A microscopic theory for the viscoelastic behaviour of suspensions of rigid rods with excluded volume interactions is presented, which is valid in the asymptotic limit of very long and thin rods. Stresses arising from translational and rotational Brownian motion and direct interactions are calculate
The rigid orthogonal Procrustes rotation problem
Ten Berge, JMF
2006-01-01
The problem of rotating a matrix orthogonally to a best least squares fit with another matrix of the same order has a closed-form solution based on a singular value decomposition. The optimal rotation matrix is not necessarily rigid, but may also involve a reflection. In some applications, only rigi
Rigid rod anchored to infinite membrane.
Guo, Kunkun; Qiu, Feng; Zhang, Hongdong; Yang, Yuliang
2005-08-15
We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.
Quantification of the UPDRS Rigidity Scale.
Patrick, S K; Denington, A A; Gauthier, M J; Gillard, D M; Prochazka, A
2001-03-01
In the clinical setting, parkinsonian rigidity is assessed using subjective rating scales such as that of the Unified Parkinson's Disease Rating System (UPDRS). However, such scales are susceptible to problems of sensitivity and reliability. Here, we evaluate the reliability and validity of a device designed to quantify parkinsonian rigidity at the elbow and the wrist. The method essentially quantifies the clinical examination and employs small sensors to monitor forces and angular displacements imposed by the clinician onto the limb segment distal to the joint being evaluated. Force and displacement data are used to calculate elastic and viscous stiffnesses and their vectorial sum, mechanical impedance. Interexaminer agreement of measures of mechanical impedance in subjects with Parkinson's disease was comparable to that of clinical UPDRS scores. Examiners tended to overrate rigidity on the UPDRS scale during reinforcement manoeuvres. Mechanical impedance was nonlinearly related to UPDRS ratings of rigidity at the elbow and wrist; characterization of such relationships allows interpretation of impedance measurements in terms of the clinical rating scales.
Geometric integrators for stochastic rigid body dynamics
Tretyakov, Mikhail
2016-01-05
Geometric integrators play an important role in simulating dynamical systems on long time intervals with high accuracy. We will illustrate geometric integration ideas within the stochastic context, mostly on examples of stochastic thermostats for rigid body dynamics. The talk will be mainly based on joint recent work with Rusland Davidchak and Tom Ouldridge.
Rigid polyurethane and kenaf core composite foams
Rigid polyurethane foams are valuable in many construction applications. Kenaf is a bast fiber plant where the surface stem skin provides bast fibers whose strength-to-weight ratio competes with glass fiber. The higher volume product of the kenaf core is an under-investigated area in composite appli...
Cracking of open traffic rigid pavement
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.
Jacoby, Oscar; Kamke, Marc R.; Mattingley, Jason B.
2013-01-01
We have a remarkable ability to accurately estimate average featural information across groups of objects, such as their average size or orientation. It has been suggested that, unlike individual object processing, this process of "feature averaging" occurs automatically and relatively early in the course of perceptual processing,…
Saneyoshi, Ayako; Michimata, Chikashi
2009-01-01
Participants performed two object-matching tasks for novel, non-nameable objects consisting of geons. For each original stimulus, two transformations were applied to create comparison stimuli. In the categorical transformation, a geon connected to geon A was moved to geon B. In the coordinate transformation, a geon connected to geon A was moved to…
Utility of semi-rigid thoracoscopy in undiagnosed exudative pleural effusion
Loganathan Nattusamy
2015-01-01
Full Text Available Background: 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. Patients and Methods: 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. Results: 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. Conclusion: Semi-rigid thoracoscopy is a safe and
Zuo, Siyang; Masamune, Ken; Kuwana, Kenta; Tomikawa, Morimasa; Ieiri, Satoshi; Ohdaira, Takeshi; Hashizume, Makoto; Dohi, Takeyoshi
2011-01-01
Single port access (SPA) surgery is a laparoscopic procedure using only one transumbilical-placed port. Natural orifice transluminal endoscopic surgery (NOTES) offers the possibility of surgery without visible scars. To address the access and stability problems in SPA and NOTES, we developed a device called rigid-flexible outer sheath. This sheath can be switched between flexible and rigid modes by a novel pneumatic shapelocking mechanism, and it has a double curvature structure that enables it to flex in four directions at the distal end and three directions on the rigid-flexible shaft. The insertion part of the prototype is 300 mm long with a 20 mm outer diameter, and the part is equipped with four working channels. In vivo experiments using a swine show that the outer sheath has high potential for solving access and stability problems. We expect that the outer sheath will be useful for SPA and NOTES.
The two-body problem of a pseudo-rigid body and a rigid sphere
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....
Antiplane SH-deformations near a surface rigid foundation above a subsurface rigid circular tunnel
Lee, V. W.; Manoogian, M. E.; Chen, S.
2002-06-01
The problem on the dynamic response of a rigid embedded foundation in the presence of an underground rigid tunnel and subjected to excitation of incident anti-plane SH waves is analyzed. By using the exact analytical solution for the two-dimensional SH-wave propagation in and around both the surface rigid foundation and subsurface rigid tunnel, those aspects of the resulting ground motions that are of special interest and importance for seismic resistant design in earthquake analyses have been examined. The computed amplitudes of the resulting periodic ground motions display a very complicated wave-interference between the surface foundation and underground tunnel that lead to observed standing wave patterns, together with abrupt changes in the wave amplitudes and large amplification of the incident motions.
Dynamic compared to rigid fixation in lumbar spine: a systematic review
Ricardo Vieira Botelho
2014-01-01
Full Text Available Objective: The objective of this review is to reveal the quality of published data and the effect size of DPFs compared to rigid fixation in lumbar spine. Summary of background data: since 2002, several dynamic pedicle fixation (DPF systems have been developed with the aim to stabilize the spine without the undesirable effects of rigid lumbar spine fixation. Nearly ten years later, there are several studies on these dynamic systems. Methods: A systematic review was done in MEDLINE/PubMED, Embase, Cochrane Central Register of Randomized Trials and Google Scholar to assess the quality of published literature and the available studied outcomes in randomized controlled trials of DPF. Results: Only three papers described randomized trials studying DPF. One of them focused on protection of adjacent level disease provided by DPF. Conclusion: It was not possible to reveal any evidence for benefits using DPF compared to rigid fixation in surgery for lumbar spine.
Financial Constraints and Nominal Price Rigidities
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...
Rigid cohomology over Laurent series fields
Lazda, Christopher
2016-01-01
In this monograph, the authors develop a new theory of p-adic cohomology for varieties over Laurent series fields in positive characteristic, based on Berthelot's theory of rigid cohomology. Many major fundamental properties of these cohomology groups are proven, such as finite dimensionality and cohomological descent, as well as interpretations in terms of Monsky-Washnitzer cohomology and Le Stum's overconvergent site. Applications of this new theory to arithmetic questions, such as l-independence and the weight monodromy conjecture, are also discussed. The construction of these cohomology groups, analogous to the Galois representations associated to varieties over local fields in mixed characteristic, fills a major gap in the study of arithmetic cohomology theories over function fields. By extending the scope of existing methods, the results presented here also serve as a first step towards a more general theory of p-adic cohomology over non-perfect ground fields. Rigid Cohomology over Laurent Series Fields...
Adaptive Control of Rigid Body Satellite
Thawar T. Arif
2008-01-01
The minimal controller synthesis (MCS) is an extension of the hyperstable model reference adaptive control algorithm. The aim of minimal controller synthesis is to achieve excellent closed-loop control despite the presence of plant parameter variations, external disturbances, dynamic coupling within the plant and plant nonlinearities. The minimal controller synthesis algorithm was successfully applied to the problem of decentralized adaptive schemes. The decentralized minimal controller synthesis adaptive control strategy for controlling the attitude of a rigid body satellite is adopted in this paper. A model reference adaptive control strategy which uses one single three-axis slew is proposed for the purpose of controlling the attitude of a rigid body satellite. The simulation results are excellent and show that the controlled system is robust against disturbances.
Quantum mechanics of a generalised rigid body
Gripaios, Ben
2015-01-01
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. 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.
Lectures on formal and rigid geometry
Bosch, Siegfried
2014-01-01
A first version of this work appeared in 2005 as a Preprint of the Collaborative Research Center "Geometrical Structures in Mathematics" at the University of Münster. Its aim was to offer a concise and self-contained 'lecture-style' introduction to the theory of classical rigid geometry established by John Tate, together with the formal algebraic geometry approach launched by Michel Raynaud. These Lectures are now viewed commonly as an ideal means of learning advanced rigid geometry, regardless of the reader's level of background. Despite its parsimonious style, the presentation illustrates a number of key facts even more extensively than any other previous work. This Lecture Notes Volume is a revised and slightly expanded version of the original preprint and has been published at the suggestion of several experts in the field.
Flexible and rigid casting tape as a novel approach to offloading diabetic foot ulcers.
Malone, M; Gannass, A Al; Bowling, F
2011-07-01
Offloading diabetic ulceration is a key component to the success in healing ulcers on the plantar aspect of the foot. New advances in offloading techniques allow for differing approaches in sometimes complex diabetic foot pathologies with associated ulceration. This case study looks at the use of flexible and rigid casting technique as part of the treatment in offloading plantar foot ulceration.
Wu, Jinglai; Luo, Zhen; Zhang, Nong; Zhang, Yunqing; Walker, Paul D.
2017-02-01
This paper proposes an uncertain modelling and computational method to analyze dynamic responses of rigid-flexible multibody systems (or mechanisms) with random geometry and material properties. Firstly, the deterministic model for the rigid-flexible multibody system is built with the absolute node coordinate formula (ANCF), in which the flexible parts are modeled by using ANCF elements, while the rigid parts are described by ANCF reference nodes (ANCF-RNs). Secondly, uncertainty for the geometry of rigid parts is expressed as uniform random variables, while the uncertainty for the material properties of flexible parts is modeled as a continuous random field, which is further discretized to Gaussian random variables using a series expansion method. Finally, a non-intrusive numerical method is developed to solve the dynamic equations of systems involving both types of random variables, which systematically integrates the deterministic generalized-α solver with Latin Hypercube sampling (LHS) and Polynomial Chaos (PC) expansion. The benchmark slider-crank mechanism is used as a numerical example to demonstrate the characteristics of the proposed method.
Design of Overlays for Rigid Airport Pavements
1988-04-01
Renture, A., and Mindess , S. 1986. "The Effect of Concrete Strength on Crack Patterns," Cement and Concrete Research,_ Vol 16, Pergamon Press Ltd...34 Miscellaneous Paper S-74-30, US Army Engineer Waterways Experiment Station, Vicksburg, Miss. 22. Harr, M. E. 1977 . Mechanics of Particulate Media...of Civil -. Engineers, New York. 33. Hutchinson, R., and Vedros, P. 1977 . "Performance of Heavy-Load Port- land Cement Concrete (Rigid) Airfield
Rigidity of contractions on Hilbert spaces
Eisner, Tanja
2009-01-01
We study the asymptotic behaviour of contractive operators and strongly continuous semigroups on separable Hilbert spaces using the notion of rigidity. In particular, we show that a "typical" contraction $T$ contains the unit circle times the identity operator in the strong limit set of its powers, while $T^{n_j}$ converges weakly to zero along a sequence $\\{n_j\\}$ with density one. The continuous analogue is presented for isometric ang unitary $C_0$-(semi)groups.
Effectiveness of transverse grooves in rigid pavement
Gurney, G. F.; Bryden, J. E.
1982-10-01
Transverse grooves were installed at 11 intersection approaches on worn rigid pavement to reduce a high rate of wet road accidents. In most cases, accident reductions were experienced only at intersections with multiple negative operational characteristics, including higher approach speeds, limited sight distances, and frequent vehicle stopping for turns or stop signs. Intersections with no more than one negative characteristic generally did not benefit from grooving.
Héraud, Jean-Loup; Lautesse, Philippe; Ferlin, Fabrice; Chabot, Hugues
2017-01-01
Our work extends a previous study of epistemological presuppositions in teaching quantum physics in upper scientific secondary school in France. Here, the problematic reference of quantum theory's concepts is treated at the ontological level (the counterintuitive nature of quantum objects). We consider the approach of using narratives describing…
The rigid bi-functional sail, new concept concerning the reduction of the drag of ships
Țicu, I.; Popa, I.; Ristea, M.
2015-11-01
The policy of the European Union in the energy field, for the period to follow until 2020, is based on three fundamental objectives: sustainability, competitiveness and safety in energy supply. The “Energy - Climate Changes” program sets out a number of objectives for the EU for the year 2020, known as the “20-20-20 objectives”, namely: the reduction of greenhouse gas emissions by at least 20% from the level of those of 1990, a 20% increase in the share of renewable energy sources out of the total energy consumption as well as a target of 10% biofuels in the transports energy consumption. In this context, in order to produce or save a part of the propulsive power produced by the main propulsion machinery, by burning fossil fuels, we suggest the equipping of vessels designed for maritime transport with a bi-functional rigid sail. We consider that this device may have both the role of trapping wind energy and the role of acting as a deflector for reducing the resistance of the vessel's proceeding through the water by conveniently using the bow air current, as a result of the vessel's heading through the water with significant advantage in reducing the energy consumption for propulsion insurance.
Rigid geometry of curves and their Jacobians
Lütkebohmert, Werner
2016-01-01
This book presents some of the most important aspects of rigid geometry, namely its applications to the study of smooth algebraic curves, of their Jacobians, and of abelian varieties - all of them defined over a complete non-archimedean valued field. The text starts with a survey of the foundation of rigid geometry, and then focuses on a detailed treatment of the applications. In the case of curves with split rational reduction there is a complete analogue to the fascinating theory of Riemann surfaces. In the case of proper smooth group varieties the uniformization and the construction of abelian varieties are treated in detail. Rigid geometry was established by John Tate and was enriched by a formal algebraic approach launched by Michel Raynaud. It has proved as a means to illustrate the geometric ideas behind the abstract methods of formal algebraic geometry as used by Mumford and Faltings. This book should be of great use to students wishing to enter this field, as well as those already working in it.
Origin of Rigidity in Dry Granular Solids
Sarkar, Sumantra; Bi, Dapeng; Zhang, Jie; Behringer, R. P.; Chakraborty, Bulbul
2013-08-01
Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a nonuniform density pattern. In this work, we focus on the emergence of shear rigidity in a class of solids where this paradigm is challenged. Dry granular materials have no energetically or entropically preferred density modulations. We show that, in contrast to traditional solids, the emergence of shear rigidity in these granular solids is a collective process, which is controlled solely by boundary forces, the constraints of force and torque balance, and the positivity of the contact forces. We develop a theoretical framework based on these constraints, which connects rigidity to broken translational symmetry in the space of forces, not positions of grains. We apply our theory to experimentally generated shear-jammed states and show that these states are indeed characterized by a persistent, non-uniform density modulation in force space, which emerges at the shear-jamming transition.
DGP cosmology from rigid geodetic brane gravity
Cordero, Rubén; Molgado, Alberto; Rojas, Efrain
2011-01-01
We explore the cosmological implications provided by an effective geometrical action describing a codimension-one rigid brane embedded in a 5D fixed Minkowski spacetime, i.e., allowing for a term added to the geodetic brane action which depends on the extrinsic curvature of the worldvolume. In the geodetic brane gravity action we accommodate the rigidity of the brane through a linear term in the extrinsic curvature swept out by the brane. We study the resulting geodetic type equation of motion. Within a Friedmann-Robertson-Walker framework, we obtain a generalized Friedmann equation describing the associated cosmological evolution which in turn allowed us to illustrate explicitly the linkage between the geodetic brane theory and the rigidity content of this sort of branelike universes. We observe that, when the radiation-like energy contribution from the extra dimension is vanishing, this effective model leads to a self-(non-self)-accelerated expansion of the universe in dependence on the nature of the rigidi...
Lorenz, K S; Salama, P; Dunn, K W; Delp, E J
2012-02-01
Digital image analysis is a fundamental component of quantitative microscopy. However, intravital microscopy presents many challenges for digital image analysis. In general, microscopy volumes are inherently anisotropic, suffer from decreasing contrast with tissue depth, lack object edge detail and characteristically have low signal levels. Intravital microscopy introduces the additional problem of motion artefacts, resulting from respiratory motion and heartbeat from specimens imaged in vivo. This paper describes an image registration technique for use with sequences of intravital microscopy images collected in time-series or in 3D volumes. Our registration method involves both rigid and nonrigid components. The rigid registration component corrects global image translations, whereas the nonrigid component manipulates a uniform grid of control points defined by B-splines. Each control point is optimized by minimizing a cost function consisting of two parts: a term to define image similarity, and a term to ensure deformation grid smoothness. Experimental results indicate that this approach is promising based on the analysis of several image volumes collected from the kidney, lung and salivary gland of living rodents.
A method for measuring the inertia properties of rigid bodies
Gobbi, M.; Mastinu, G.; Previati, G.
2011-01-01
A method for the measurement of the inertia properties of rigid bodies is presented. Given a rigid body and its mass, the method allows to measure (identify) the centre of gravity location and the inertia tensor during a single test. The proposed technique is based on the analysis of the free motion of a multi-cable pendulum to which the body under consideration is connected. The motion of the pendulum and the forces acting on the system are recorded and the inertia properties are identified by means of a proper mathematical procedure based on a least square estimation. After the body is positioned on the test rig, the full identification procedure takes less than 10 min. The natural frequencies of the pendulum and the accelerations involved are quite low, making this method suitable for many practical applications. In this paper, the proposed method is described and two test rigs are presented: the first is developed for bodies up to 3500 kg and the second for bodies up to 400 kg. A validation of the measurement method is performed with satisfactory results. The test rig holds a third part quality certificate according to an ISO 9001 standard and could be scaled up to measure the inertia properties of huge bodies, such as trucks, airplanes or even ships.
Biochemical analysis of elastic and rigid cuticles of Cirsium horridulum.
Marga, F; Pesacreta, T C; Hasenstein, K H
2001-10-01
The cuticle is a complex structure of soluble lipids, lipid polymers and polysaccharides. In addition to its functions to reduce water loss and provide a protective barrier, its mechanical properties may be significant to plant growth and development. We investigated the cuticle of Cirsium horridulum Michx. because of its involvement in the thigmonastic contraction of staminal filaments. The staminal filaments and portions of the style are surrounded by a highly elastic cuticle in contrast to the rigid cuticle of the corolla and leaves. Our aim was to determine if the biochemical composition affected the elasticity of the cuticle. We discovered that the ratio of carbohydrates to lipids is 1:7 in floral parts but 2:1 in leaf cuticle. Esterified cutin components represented about 80% of the cuticle and di-hydroxyhexadecanoic acids were the major monomers of cutin, regardless of origin. The cutin of elastic tissues is characterized by a higher content of tri-hydroxy monomers than the cutin of rigid tissues. The data suggest that hydroxyl groups enhance the hydrophilic character of the cuticle and contribute to cuticular elasticity.
A general approach for modeling the motion of rigid and deformable ellipsoids in ductile flows
Jiang, Dazhi
2012-01-01
A general approach for modeling the motion of rigid or deformable objects in viscous flows is presented. It is shown that the rotation of a 3D object in a viscous fluid, regardless of the mechanical property and shape of the object, is defined by a common and simple differential equation, dQ/dt=-Θ˜Q, where Q is a matrix defined by the orientation of the object and Θ˜ is the angular velocity tensor of the object. The difference between individual cases lies only in the formulation for the angular velocity. Thus the above equation, together with Jeffery's theory for the angular velocity of rigid ellipsoids, describes the motion of rigid ellipsoids in viscous flows. The same equation, together with Eshelby's theory for the angular velocity of deformable ellipsoids, describes the motion of deformable ellipsoids in viscous flows. Both problems are solved here numerically by a general approach that is much simpler conceptually and more economic computationally, compared to previous approaches that consider the problems separately and require numerical solutions to coupled differential equations about Euler angles or spherical (polar coordinate) angles. A Runge-Kutta approximation is constructed for solving the above general differential equation. Singular cases of Eshelby's equations when the object is spheroidal or spherical are handled in this paper in a much simpler way than in previous work. The computational procedure can be readily implemented in any modern mathematics application that handles matrix operations. Four MathCad Worksheets are provided for modeling the motion of a single rigid or deformable ellipsoid immersed in viscous fluids, as well as the evolution of a system of noninteracting rigid or deformable ellipsoids embedded in viscous flows.
21 CFR 886.5916 - Rigid gas permeable contact lens.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...
A Cognitive Developmental Model of Rigidity in Senescence.
Lapsley, Daniel K.; Enright, Robert D.
1983-01-01
The rigidity construct is reinterpreted in terms of the cognitive developmental approach. A review reveals both cognitive and developmental themes, with an emphasis on the structural and operational properties of rigidity. Notes weaknesses of previous approaches to rigidity and discusses implications and predictions from the proposed model.…
Mefkur Bakan
2014-06-01
Full Text Available OBJECTIVE:Laryngoscopy and stimuli inside the trachea cause an intense sympatho-adrenal response. Remifentanil seems to be the optimal opioid for rigid bronchoscopy due to its potent and short-acting properties. The purpose of this study was to compare bolus propofol and ketamine as an adjuvant to remifentanil-based total intravenous anesthesia for pediatric rigid bronchoscopy.MATERIALS AND METHODS:Forty children under 12 years of age who had been scheduled for a rigid bronchoscopy were included in this study. After midazolam premedication, a 1 µg/kg/min remifentanil infusion was started, and patients were randomly allocated to receive either propofol (Group P or ketamine (Group K as well as mivacurium for muscle relaxation. Anesthesia was maintained with a 1 µg/kg/min remifentanil infusion and bolus doses of propofol or ketamine. After the rigid bronchoscopy, 0.05 µg/kg/min of remifentanil was maintained until extubation. Hemodynamic parameters, emergence characteristics, and adverse events were evaluated.RESULTS:The demographic variables were comparable between the two groups. The decrease in mean arterial pressure from baseline values to the lowest values during rigid bronchoscopy was greater in Group P (p= 0.049, while the reduction in the other parameters and the incidence of adverse events were comparable between the two groups. The need for assisted or controlled mask ventilation after extubation was higher in Group K.CONCLUSION:Remifentanil-based total intravenous anesthesia with propofol or ketamine as an adjuvant drug along with controlled ventilation is a viable technique for pediatric rigid bronchoscopy. Ketamine does not provide a definite advantage over propofol with respect to hemodynamic stability during rigid bronchoscopy, while propofol seems more suitable during the recovery period.
Competing $\\gamma$-rigid and $\\gamma$-stable vibrations in neutron rich Gd and Dy isotopes
Budaca, R
2015-01-01
An exactly separable version of the Bohr Hamiltonian which combines the $\\gamma$-stable and $\\gamma$-rigid axial vibration-rotation is used to describe the collective properties of few neutron rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape-phase space. While the $\\gamma$-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff $\\gamma$ oscillation hypothesis, the $\\beta$ vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables.
Yamashita, Hiromasa; Zuo, Siyang; Masamune, Ken; Liao, Hongen; Dohi, Takeyoshi
2009-01-01
We developed a nonmagnetic rigid and flexible outer sheath with pneumatic interlocking mechanism using flexible toothed links and a wire-driven bending distal end. The outer sheath can be switched between rigid and flexible modes easily depending on surgical scenes, and the angle of its distal end can be controlled by three nylon wires. All components of flexible parts are made of MRI-compatible nonmagnetic plastics. We manufactured the device with 300-mm long, 16-mm outer diameter, 7-mm inner diameter and 90-mm bending distal end. Holding power of the device in rigid mode was maximum 3.6 N, which was sufficient for surgical tasks in body cavity. In vivo experiment using a swine, our device performed smooth insertion of a flexible endoscope and a biopsy forceps into reverse side of the liver, intestines and spleen with a curved path. In conclusion, our device shows availability of secure approach of surgical instruments into deep cavity.
MUTUAL INFORMATION BASED 3D NON-RIGID REGISTRATION OF CT/MR ABDOMEN IMAGES
无
2001-01-01
A mutual information based 3D non-rigid registration approach was proposed for the registration of deformable CT/MR body abdomen images. The Parzen Windows Density Estimation (PWDE) method is adopted to calculate the mutual information between the two modals of CT and MRI abdomen images. By maximizing MI between the CT and MR volume images, the overlapping part of them reaches the biggest, which means that the two body images of CT and MR matches best to each other. Visible Human Project (VHP) Male abdomen CT and MRI Data are used as experimental data sets. The experimental results indicate that this approach of non-rigid 3D registration of CT/MR body abdominal images can be achieved effectively and automatically, without any prior processing procedures such as segmentation and feature extraction, but has a main drawback of very long computation time. Key words: medical image registration; multi-modality; mutual information; non-rigid; Parzen window density estimation
Seismic Analysis for Rigid-Framed Prestressed Reinforced Concrete Bridge in Tianjin Light Railway
丁阳; 李楠; 李忠献
2004-01-01
The seismic analysis of a rigid-framed prestressed concrete bridge in Tianjin Light Railway is performed. A 3-D dynamic finite element model of the bridge is established considering the weakening effect caused by the soft soil foundation. After the dynamic characteristics are calculated in terms of natural frequencies and modes, the seismic analysis is carried out using the modal response spectrum method and the time-history method, respectively. Based on the calculated results, the reasonable design values are finally suggested as the basis of the seismic design of the bridge, and meanwhile the problems encountered were also analyzed. Finally, some conclusions are drawn as: 1) Despite the superiority of rigid-framed prestressed concrete bridge, the upper and lower ends of the piers of the bridge are proved to be the crucial parts of the bridge, which are easily destroyed under designed earthquake excitations and should be carefully analyzed and designed; 2) The soft soil foundation can possibly result in rather weakening of the lateral rigidity of the rigid-framed bridge, and should be paid considerable attention; 3) The modal response spectrum method, combined with time-history method, is suggested for the seismic analysis in engineering design of the rigid-framed prestressed concrete bridge.
Antiplane SH-deformations near a surface rigid foundation above a subsurface rigid circular tunnel
无
2002-01-01
The problem on the dynamic response of a rigid embedded foundation in the presence of an underground rigidtunnel and subjected to excitation of incident anti-plane SH waves is analyzed. By using the exact analytical solution for thetwo-dimensional SH-wave propagation in and around both the surface rigid foundation and subsurface rigid tunnel, thoseaspects of the resulting ground motions that are of special interest and importance for seismic resistant design in earthquakeanalyses have been examined. The computed amplitudes of the resulting periodic ground motions display a very complicatedwave-interference between the surface foundation and underground tunnel that lead to observed standing wave patterns,together with abrupt changes in the wave amplitudes and large amplification of the incident motions.
Study of the kinematics of rigid body using the sliding vectors' theory
Llopis Cosin, Juan Vicente; Rubio Michavila, Constanza; Gasque Albalate, Maria; Quiles Casado, Susana De La Salud
2013-01-01
The sliding vector theory is a powerful tool for the study of the three parts of Classical Mechanics in vectorial formulation: Kinematics, Statics and Dynamics. Due to the great importance of the Vector Mechanics for their technical applications in engineering, this part of the Physics is studied in the first years of Engineering Degrees, as a fundamental topic included in the subjects of Physics. The rigid body model is the solid under study in Vectorial Mechanics. Firstly, in Ki...
Geometry-induced rigidity in nonspherical pressurized elastic shells.
Lazarus, A; Florijn, H C B; Reis, P M
2012-10-01
We present results from an experimental investigation of the indentation of nonspherical pressurized elastic shells with a positive Gauss curvature. A predictive framework is proposed that rationalizes the dependence of the local rigidity of an indented shell on the curvature in the neighborhood of the locus of indentation, the in-out pressure differential, and the material properties. In our approach, we combine classic theory for spherical shells with recent analytical developments for the pressurized case, and proceed, for the most part, by analogy, guided by our own experiments. By way of example, our results elucidate why an eggshell is significantly stiffer when compressed along its major axis, as compared to doing so along its minor axis. The prominence of geometry in this class of problems points to the relevance and applicability of our findings over a wide range of length scales.
Rigid performance requirements assure public safety by regulations
Nickell, R.E.; Glass, R.E.
1987-07-01
Title 10, Part 71 of the Code of Federal Regulations (10 CFR 71) provides a set of prescriptive performance test requirements for spent nuclear fuel and high-level waste transport packaging containment systems. The hypothetical accident conditions, which involve a sequence of impact, puncture, fire, and water immersion events, are referred to as rigid because of their extremely prescriptive nature. These hypothetical accident events have now been placed within the context of real transportation accidents, at least for conventional austenitic stainless steel/ lead gamma shielded cask designs. The assurance of public safety, including the issue of safety margin for very severe accident events is discussed in this paper for both conventional and innovative cask design concepts. A particular risk assessment approach that follows from work at the Lawrence Livermore National Laboratory is suggested.
Rigid performance requirements assure public safety by regulations
Nickell, R.E.; Glass, R.E.
1987-01-01
Title 10, Part 71 of the Code of Federal Regulations (10 CFR 71) provides a set of prescriptive performance test requirements for spent nuclear fuel and high-level waste transport packaging containment systems. The hypothetical accident conditions, which involve a sequence of impact, puncture, fire, and water immersion events, are referred to as rigid because of their extremely prescriptive nature. These hypothetical accident events have now been placed within the context of real transportation accidents, at least for conventional austenitic stainless steel/lead gamma shielded cask designs. The assurance of public safety, including the issue of safety margin for very severe accident events, is discussed in this paper for both conventional and innovative cask design concepts. A particular risk assessment approach that follows from work at the Lawrence Livermore National Laboratory is suggested. 6 refs., 2 figs.
Effects of silicon surfactant in rigid polyurethane foams
2008-03-01
Full Text Available The rigid polyurethane foams (RPUFs have been fabricated from high functional crude 4,4’-di-phenylmethane diisocyanate (CMDI and polypropylene glycols (PPGs for a wide range of surfactant concentration with an environmently friendly blowing agent (HFC 365mfc. Cream time, gel time, and tack-free time increased with the addition of surfactant. Foam density decreased rapidly to a minimum at 0.5 pphp (part per hundred polyol surfactant due to the increased blowing efficiency with surfactant. Surface tension rapidly decreased to an asymptotic value at 2 pphp surfactant. In accordance with this, cell size decreased and closed cell content increased rapidly to constant values at low surfactant concentrations (<1 pphp. The decrease of cell size was accompanied by the decrease of thermal conductivity to give a linear relatiohship between the two implying that the series model of heat transfer is applicable.
Local rigidity and physical trends in embedded Si nanocrystals
Kleovoulou, K.; Kelires, P. C.
2013-12-01
We investigate the problem of local rigidity of Si nanocrystals embedded in amorphous silica. By analyzing the elastic (bulk) modulus field into atomic contributions, we show that it is highly inhomogeneous. It consists of a hard region in the interior of the nanocrystals, with moduli ˜105 GPa, compared to 98 GPa for bulk Si, and of "superhard" (˜120 GPa) and "supersoft" (˜80 GPa) regions in the outer parts. Overall, the nanocrystal bulk modulus is significantly enhanced compared to the bulk, and its variation with size accurately follows a power-law dependence on the average bond length. The bulk modulus of the oxide matrix and of the interface region is nearly constant with size, with values 60 and 70 GPa, respectively. The average optical (homopolar) gap is directly linked to the elastic and bond-length variations.
Brownian dynamics of confined rigid bodies
Delong, Steven; Balboa Usabiaga, Florencio; Donev, Aleksandar, E-mail: donev@courant.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2015-10-14
We introduce numerical methods for simulating the diffusive motion of rigid bodies of arbitrary shape immersed in a viscous fluid. We parameterize the orientation of the bodies using normalized quaternions, which are numerically robust, space efficient, and easy to accumulate. We construct a system of overdamped Langevin equations in the quaternion representation that accounts for hydrodynamic effects, preserves the unit-norm constraint on the quaternion, and is time reversible with respect to the Gibbs-Boltzmann distribution at equilibrium. We introduce two schemes for temporal integration of the overdamped Langevin equations of motion, one based on the Fixman midpoint method and the other based on a random finite difference approach, both of which ensure that the correct stochastic drift term is captured in a computationally efficient way. We study several examples of rigid colloidal particles diffusing near a no-slip boundary and demonstrate the importance of the choice of tracking point on the measured translational mean square displacement (MSD). We examine the average short-time as well as the long-time quasi-two-dimensional diffusion coefficient of a rigid particle sedimented near a bottom wall due to gravity. For several particle shapes, we find a choice of tracking point that makes the MSD essentially linear with time, allowing us to estimate the long-time diffusion coefficient efficiently using a Monte Carlo method. However, in general, such a special choice of tracking point does not exist, and numerical techniques for simulating long trajectories, such as the ones we introduce here, are necessary to study diffusion on long time scales.
Rice, Betsy M; Larentzos, James P; Byrd, Edward F C; Weingarten, N Scott
2015-02-10
The Multiple Objective Evolutionary Strategies (MOES) algorithm was used to parametrize force fields having the form of the reactive models ReaxFF (van Duin, A. C. T.; Dasgupta, S.; Lorant, F.; Goddard, W. A. J. Phys. Chem. A 2001, 105, 9396) and ReaxFF-lg (Liu, L.; Liu, Y.; Zybin, S. V.; Sun, H.; Goddard, W. A. J. Phys. Chem. A 2011, 115, 11016) in an attempt to produce equal or superior ambient state crystallographic structural results for cyclotrimethylene trinitramine (RDX). Promising candidates were then subjected to molecular dynamics simulations of five other well-known conventional energetic materials to assess the degree of transferability of the models. Two models generated through the MOES search were shown to have performance better than or as good as ReaxFF-lg in describing the six energetic systems modeled. This study shows that MOES is an effective and efficient method to develop complex force fields.
Persistence-Driven Durotaxis: Generic, Directed Motility in Rigidity Gradients
Novikova, Elizaveta A.; Raab, Matthew; Discher, Dennis E.; Storm, Cornelis
2017-02-01
Cells move differently on substrates with different rigidities: the persistence time of their motion is higher on stiffer substrates. We show that this behavior—in and of itself—results in a net flux of cells directed up a soft-to-stiff gradient. Using simple random walk models with varying persistence and stochastic simulations, we characterize the propensity to move in terms of the durotactic index also measured in experiments. A one-dimensional model captures the essential features and highlights the competition between diffusive spreading and linear, wavelike propagation. Persistence-driven durokinesis is generic and may be of use in the design of instructive environments for cells and other motile, mechanosensitive objects.
Nematic Ordering of Rigid Rods in a Gravitational Field
Baulin, V A; Baulin, Vladimir A.; Khokhlov, Alexei R.
1999-01-01
The isotropic-to-nematic transition in an athermal solution of long rigid rods subject to a gravitational (or centrifugal) field is theoretically considered in the Onsager approximation. The new feature emerging in the presence of gravity is a concentration gradient which coupled with the nematic ordering. For rodlike molecules this effect becomes noticeable at centrifugal acceleration g ~ 10^3--10^4 m/s^2, while for biological rodlike objects, such as tobacco mosaic virus, TMV, the effect is important even for normal gravitational acceleration conditions. Rods are concentrated near the bottom of the vessel which sometimes leads to gravity induced nematic ordering. The concentration range corresponding to phase separation increases with increasing g. In the region of phase separation the local rod concentration, as well as the order parameter, follow a step function with height.
Characterization of low density rigid urethane foam
Larsen, F.N.
1978-10-01
The chemical and mechanical properties of a low density, rigid polyurethane foam material taken from a Joint Test Assembly (JTA) after 13 years of storage were measured. Chemical analyses confirmed the composition to be Bendix Rigifoam 6003-1.5, a pentaerythritol/epsilon-caprolactone/tolyene diisocyanate polyurethane foam. Comparison of data from testing thermal and mechanical characteristics with data from a currently manufactured foam of identical composition indicates no degradation of properties had occurred. This information gives added confidence to the stockpile lifetime integrity of the Rigifoam 6003-2 foam system designated for use in other programs.
Mechanical Characterization of Rigid Polyurethane Foams.
Lu, Wei-Yang
2014-12-01
Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.
Rigid Body Mechanics Mathematics, Physics and Applications
Heard, William B
2005-01-01
This textbook is a modern, concise and focused treatment of the mathematical techniques, physical theories and applications of rigid body mechanics, bridging the gap between the geometric and more classical approaches to the topic. It emphasizes the fundamentals of the subject, stresses the importance of notation, integrates the modern geometric view of mechanics and offers a wide variety of examples -- ranging from molecular dynamics to mechanics of robots and planetary rotational dynamics. The author has unified his presentation such that applied mathematicians, mechanical and astro-aerodyna
Diffraction of sound by nearly rigid barriers
Hadden, W. J., Jr.; Pierce, A. D.
1976-01-01
The diffraction of sound by barriers with surfaces of large, but finite, acoustic impedance was analyzed. Idealized source-barrier-receiver configurations in which the barriers may be considered as semi-infinite wedges are discussed. Particular attention is given to situations in which the source and receiver are at large distances from the tip of the wedge. The expression for the acoustic pressure in this limiting case is compared with the results of Pierce's analysis of diffraction by a rigid wedge. An expression for the insertion loss of a finite impedance barrier is compared with insertion loss formulas which are used extensively in selecting or designing barriers for noise control.
Mechanical Characterization of Rigid Polyurethane Foams
Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials
2014-12-01
Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.
Public policies targeting labour market rigidities
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.
Magnetic Control of Rigid Achiral Microswimmers
Cheang, U.; Meshkati, Farshad; Fu, Henry; Kim, Minjun
2013-11-01
We report control of rigid achiral microswimmers in low Reynolds number environments. A rotating magnetic field was used to actuate the microswimmers wirelessly by rotating the microswimmers, which produces propulsion. Previous magnetically actuated microswimmers in bulk fluids have been designed with either flexibility or chiral geometry; we show that simpler geometries with neither flexibility nor chirality can produce propulsion. The microswimmer consists of three magnetic beads conjugated using avidin-biotin linkages into an arc formation. We designed a magnetic field generator consisting of electromagnetic coils arranged in an approximate Helmholtz configuration. A highspeed camera provided realtime imaging of the microswimmers' motion in a PDMS chamber. The rigidity of the microswimmer was characterized by tracking the position of the individual beads and calculating their relative distances. As a function of field strength and rotation frequency, we observed changes in the rotational axis of the microswimmers and the corresponding effects on their velocities. The achiral microswimmers exhibited active propulsion and were controllable in both speed and direction, which demonstrates the possibility for future biomedical applications such as drug delivery.
Glycerol in micellar confinement with tunable rigidity
Lannert, Michael; Müller, Allyn; Gouirand, Emmanuel; Talluto, Vincenzo; Rosenstihl, Markus; Walther, Thomas; Stühn, Bernd; Blochowicz, Thomas; Vogel, Michael
2016-12-01
We investigate the glassy dynamics of glycerol in the confinement of a microemulsion system, which is stable on cooling down to the glass transition of its components. By changing the composition, we vary the viscosity of the matrix, while keeping the confining geometry intact, as is demonstrated by small angle X-ray scattering. By means of 2H NMR, differential scanning calorimetry, and triplet solvation dynamics we, thus, probe the dynamics of glycerol in confinements of varying rigidity. 2H NMR results show that, at higher temperatures, the dynamics of confined glycerol is unchanged compared to bulk behavior, while the reorientation of glycerol molecules becomes significantly faster than in the bulk in the deeply supercooled regime. However, comparison of different 2H NMR findings with data from calorimetry and solvation dynamics reveals that this acceleration is not due to the changed structural relaxation of glycerol, but rather due to the rotational motion of essentially rigid glycerol droplets or of aggregates of such droplets in a more fluid matrix. Thus, independent of the matrix mobility, the glycerol dynamics remains unchanged except for the smallest droplets, where an increase of Tg and, thus, a slowdown of the structural relaxation is observed even in a fluid matrix.
Shear-induced rigidity in athermal materials
Chakraborty, Bulbul; Sarkar, Sumantra
2014-03-01
In this talk, we present a minimal model of rigidity and plastic failure in solids whose rigidity emerges directly as a result of applied stresses. Examples include shear-jamming (SJ) in dry grains and discontinuous shear thickening (DST) of dense non-Brownian suspensions. Both SJ and DST states are examples of non-equilibrium, self-assembled structures that have evolved to support the load that created them. These are strongly-interacting systems where the interactions arise primarily from the strict constraints of force and torque balance at the local and global scales. Our model is based on a reciprocal-space picture that strictly enforces the local and global constraints, and is, therefore, best suited to capturing the strong correlations in these non-equilibrium systems. The reciprocal space is a tiling whose edges represent contact forces, and whose faces represent grains. A separation of scale between force fluctuations and displacements of grains is used to represent the positional disorder as quenched randomness on variables in the reciprocal space. Comparing theoretical results to experiments, we will argue that the packing fraction controls the strength of the quenched disorder. Sumantra Sarkar et al, Phys. Rev. Lett. 111, 068301 (2013)
Wallace, Julian M; Tjan, Bosco S
2011-05-25
Crowding occurs when stimuli in the peripheral fields become harder to identify when flanked by other items. This phenomenon has been demonstrated extensively with simple patterns (e.g., Gabors and letters). Here, we characterize crowding for everyday objects. We presented three-item arrays of objects and letters, arranged radially and tangentially in the lower visual field. Observers identified the central target, and we measured contrast energy thresholds as a function of target-to-flanker spacing. Object crowding was similar to letter crowding in spatial extent but was much weaker. The average elevation in threshold contrast energy was in the order of 1 log unit for objects as compared to 2 log units for letters and silhouette objects. Furthermore, we examined whether the exterior and interior features of an object are differentially affected by crowding. We used a circular aperture to present or exclude the object interior. Critical spacings for these aperture and "donut" objects were similar to those of intact objects. Taken together, these findings suggest that crowding between letters and objects are essentially due to the same mechanism, which affects equally the interior and exterior features of an object. However, for objects defined with varying shades of gray, it is much easier to overcome crowding by increasing contrast.
1978-12-01
objectives may direct students’ learning (Duchastel and Merrill, 1973; Kapfer , 1970; Kibler et al., 1974), since such objectives may provide...matter learning. Journal of Educational Psychology, 62(1): 67-70 (1971). Kapfer , P. G. Behavioral objectives and the curriculum processor. Educational
Abdulla Al Ansari
2013-09-01
Full Text Available Introduction: Penile prosthesis implantation is one of the treatment choices that is kept for patients who were not satisfied with other treatments. Although penile prosthesis satisfaction rates are higher, there are some dissatisfied patients. The patients’ reasons are mostly shortness and softness of implanted prosthesis. It was previously demonstrated that penile axial rigidity of more than 500 grams is enough for successful vaginal intromission. To our knowledge, there is no study comparing axial rigidity of penile prosthesis and satisfaction. Objectives: The aim of this study was to examine whether axial rigidity of penile prosthesis had impact on patient and partner satisfaction. Materials and Methods: We enrolled one hundred patients who were implanted penile prosthesis before to evaluate their penile axial rigidity. We used Rigidometry (by using the digital inflection rigidometer to assess the minimal axial pressure to bend the implanted penis. Results: We demonstrated that mean axial pressure to bend the implanted penis was 984.8 ± 268.7 grams. Overall satisfaction score with the penile prosthesis implant was 4.55 and 4.49 (out of 5 in patients and partners, respectively. In total, seven men were unsatisfied with their implant and reported a mean satisfaction score of 0.6 ± 0.48 (out of 5. All prostheses types showed good and more than 500 grams axial rigidity. The patients with Ambicor type, which were buckled at about 710.5 grams, showed worse satisfaction rates in comparison to other prostheses in two patients. Digital inflection rigidometer results of other penile prosthesis types in unsatisfied patient were 842.0, 872.0, 887.0 and 920 g. in CX700, Titan, Genesis and Titan OTR, respectively. Conclusion: We demonstrated that dissatisfaction rate was highest in Ambicor prosthesis implanted patients. Additionally, patients with 3-piece penile prosthesis were more satisfied than 2-piece or malleable ones, interestingly, although
Weak rigidity in almost-thermodynamic material schemes
del Olmo, V.; Olivert, J.
1985-06-01
To avoid the restrictions that the Born rigidity supposes for the motions in relativity, the definition of a weakly rigid almost-thermodynamic material scheme is proposed. From it the relativistic incompressibility condition given by Ferrando and Olivert is obtained. Moreover, it is proved that, for the weakly rigid irrotational and geodesic almost-thermodynamic material schemes, the scalar curvature of the Landau manifolds is constant along the streamlines.
Regulation of Breast Cancer Stem Cells by Tissue Rigidity
2015-06-01
alignment by second harmonic generation imaging (SHG) and used it as a surrogate marker for tissue rigidity. In agreement with previous publications6–8,44,45...AD ____________ __ Award Number: W81XWH-13-1-0133 TITLE: Regulation of Breast Cancer Stem Cells by Tissue Rigidity PRINCIPAL INVESTIGATOR: Adam J...CONTRACT NUMBER Regulation of Breast Cancer Stem Cell by Tissue Rigidity W81XWH-13-1-0133 Sb. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR
Dual Quaternion Variational Integrator for Rigid Body Dynamic Simulation
XU, JIAFENG; Halse, Karl Henning
2016-01-01
We introduce a symplectic dual quaternion variational integrator(DQVI) for simulating single rigid body motion in all six degrees of freedom. Dual quaternion is used to represent rigid body kinematics and one-step Lie group variational integrator is used to conserve the geometric structure, energy and momentum of the system during the simulation. The combination of these two becomes the first Lie group variational integrator for rigid body simulation without decoupling translations and rotati...
Rigid curves on $\\bar M_{0,n}$ and arithmetic breaks
Castravet, Ana-Maria
2011-01-01
A result of Keel and McKernan states that a hypothetical counterexample to the F-conjecture must come from rigid curves on $\\bar {M}_{0,n}$ that intersect the interior. We exhibit several ways of constructing rigid curves. In all our examples, a reduction mod p argument shows that the classes of the rigid curves that we construct can be decomposed as sums of F-curves.
Discrete Time Crystals: Rigidity, Criticality, and Realizations
Yao, N. Y.; Potter, A. C.; Potirniche, I.-D.; Vishwanath, A.
2017-01-01
Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.
Modeling Decomposition of Unconfined Rigid Polyurethane Foam
HOBBS,MICHAEL L.; ERICKSON,KENNETH L.; CHU,TZE YAO
1999-11-08
The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam that contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.
Modeling Decomposition of Unconfined Rigid Polyurethane Foam
CHU,TZE YAO; ERICKSON,KENNETH L.; HOBBS,MICHAEL L.
1999-11-01
The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam which contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.
Discrete Time Crystals: Rigidity, Criticality, and Realizations.
Yao, N Y; Potter, A C; Potirniche, I-D; Vishwanath, A
2017-01-20
Despite being forbidden in equilibrium, spontaneous breaking of time translation symmetry can occur in periodically driven, Floquet systems with discrete time-translation symmetry. The period of the resulting discrete time crystal is quantized to an integer multiple of the drive period, arising from a combination of collective synchronization and many body localization. Here, we consider a simple model for a one-dimensional discrete time crystal which explicitly reveals the rigidity of the emergent oscillations as the drive is varied. We numerically map out its phase diagram and compute the properties of the dynamical phase transition where the time crystal melts into a trivial Floquet insulator. Moreover, we demonstrate that the model can be realized with current experimental technologies and propose a blueprint based upon a one dimensional chain of trapped ions. Using experimental parameters (featuring long-range interactions), we identify the phase boundaries of the ion-time-crystal and propose a measurable signature of the symmetry breaking phase transition.
Rigidity of marginally outer trapped 2-spheres
Galloway, Gregory J
2015-01-01
In a matter-filled spacetime, perhaps with positive cosmological constant, a stable marginally outer trapped 2-sphere must satisfy a certain area inequality. Namely, as discussed in the paper, its area must be bounded above by $4\\pi/c$, where $c > 0$ is a lower bound on a natural energy-momentum term. We then consider the rigidity that results for stable, or weakly outermost, marginally outer trapped 2-spheres that achieve this upper bound on the area. In particular, we prove a splitting result for 3-dimensional initial data sets analogous to a result of Bray, Brendle and Neves [10] concerning area minimizing 2-spheres in Riemannian 3-manifolds with positive scalar curvature. We further show that these initial data sets locally embed as spacelike hypersurfaces into the Nariai spacetime. Connections to the Vaidya spacetime and dynamical horizons are also discussed.
Foam inflated rigidized structures for space applications
Lester, D. M.; Warner, M. J.; Blair, M.
1993-11-01
Large lightweight stowable structures that can be deployed in space without astronaut extra vehicular activity are vital to expanding space exploration and utilization. To meet this challenge Foam Inflated Rigidized (FIR) structures have been developed by Thiokol Corporation on the Air Forces's Gossamer Baggie Torus program. In this paper the development, proof of concept demonstration of an eight foot diameter octagonal torus, and design application of this technology for structural elements to stabilize the solar collector of a solar thermal rocket are discussed. A FIR structure uses foam to inflate and pre-stress a resin impregnated fabric skin. The predeployed foam used was a solvent swelled polymer that foams immediately when exposed to vacuum due to rapid solvent loss. This property allows a very simple deployment mechanism to be used in erecting these structures. Once inflated, the skin resin is cured using the available ultraviolet radiation. By using high strength and stiffness fiber materials a stiff, strong lightweight structure was produced.
On real structures on rigid surfaces
Kulikov, Vik S [Steklov Mathematical Institute, Russian Academy of Sciences (Russian Federation); Kharlamov, V M [Institut de Recherche Matematique Avanee Universite Louis Pasteur et CNRS 7 rue Rene Descartes (France)
2002-02-28
We construct examples of rigid surfaces (that is, surfaces whose deformation class consists of a unique surface) with a particular behaviour with respect to real structures. In one example the surface has no real structure. In another it has a unique real structure, which is not maximal with respect to the Smith-Thom inequality. These examples give negative answers to the following problems: the existence of real surfaces in each deformation class of complex surfaces, and the existence of maximal real surfaces in every complex deformation class that contains real surfaces. Moreover, we prove that there are no real surfaces among surfaces of general type with p{sub g}=q=0 and K{sup 2}=9. These surfaces also provide new counterexamples to the 'Dif = Def' problem.
Water dynamics in rigid ionomer networks
Osti, N. C.; Etampawala, T. N.; Shrestha, U. M.; Aryal, D.; Tyagi, M.; Diallo, S. O.; Mamontov, E.; Cornelius, C. J.; Perahia, D.
2016-12-01
The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.
Observational properties of rigidly rotating dust configurations
Ilyas, Batyr; Yang, Jinye
2016-01-01
We study the observational properties of a class of exact solutions of Einstein's field equations describing stationary, axially symmetric, rigidly rotating dust. We ask the question whether such solutions can describe astrophysical rotating dark matter clouds and we probe the possibility that they may constitute an alternative to supermassive black holes at the center of galaxies. We show that light emission from accretion disks in this space-time has several differences with respect to the emission of light from accretion disks around black holes. The shape of the iron K{\\alpha} line in the reflection spectrum of accretion disks can potentially distinguish this class of solution from the Kerr metric, but this may not be possible with current X-ray missions.
Static friction between rigid fractal surfaces.
Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming
2015-09-01
Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.
Acoustic propagation in a rigid torus
El-Raheb, M.; Wagner, P.
1982-01-01
The acoustic propagation in a rigid torus is analyzed using a Green's function method. Three types of surface elements are developed; a flat quadrilateral element used in modeling polygonal cavities, a curved conical element appropriate for surfaces with one curvature, and a toroidal element developed for such doubly curved surfaces as the torus. Curved elements are necessary since the acoustic pressure is sensitive to slope discontinuities between consecutive surface elements especially near cavity resonances. The acoustic characteristics of the torus are compared to those of a bend of square cross section for a frequency range that includes the transverse acoustic resonance. Two equivalences between the different sections are tested; the first conserves curvature and cross-sectional dimension while the second matches transverse resonance and duct volume. The second equivalence accurately matches the acoustic characteristics of the torus up to the cutoff frequency corresponding to a mode with two circumferential waves.
Field cracking performance of airfield rigid pavements
Yusuf Mehta
2017-08-01
Full Text Available This paper discusses cracking in airport pavements as studied in Construction Cycle 6 of testing carried out at the National Airport Pavement Testing Facility by the Federal Aviation Administration. Pavements of three different flexural strengths as well as two different subgrades, a soft bituminous layer and a more rigid layer known as econocrete, were tested. In addition to this, cracking near two types of isolated transition joints, a reinforced edge joint and a thickened edge joint, was considered. The pavement sections were tested using a moving load simulating that of an aircraft. It has been determined that the degree of cracking was reduced as the flexural strength of the pavement was increased and that fewer cracks formed over the econocrete base than over the bituminous base. In addition, the thickened edge transition joint was more effective in preventing cracking at the edges compared to the reinforced edge joint.
无
2003-01-01
A new rigid-plastic/rigid-viscoplastic (RP/RVP) FEM based on linear programming (LP) for plane-strain metal forming simulation is proposed. Compared with the traditional RP/RVP FEM based on iteration solution, it has some remarkable advantages, such as it's free of convergence problem and its convenience in contact, incompressibility constraint and rigid zone treatment. Two solution examples are provided to validate its accuracy and efficiency.
Studies of Rigid Rotor-Rigid Surface Scattering in Dynamical Lie Algebraic Method
WANG Xiao-Yan; DING Shi-Liang
2004-01-01
The dynamical Lie algebraic method is used for the description of statistical mechanics of rotationally inelastic molecule-surface scattering. It can give the time-evolution operators about the low power of a+ and a by solving a set of coupled nonlinear differential equations. For considering the contribution of the high power of a+ and a, we use the Magnus formula. Thus, with the time-evolution operators we can get the statistical average values of the measurable quantities in terms of the density operator formalism in statistical mechanics. The method is applied to the scattering of N2 (rigid rotor) by a flat, rigid surface to illustrate its general procedure. The results demonstrate that the method is useful for describing the statistical dynamics of gas-surface scattering.
Kim, Yeonkyu
2003-10-01
A system of differential equations governing the translational and rotational motion of a system model consisting of a rigid satellite and multiple MB suspended rigid flywheels in general configuration is developed. Flywheel modules are contained in a housing rigidly mounted on the satellite and floated by an active MB suspension system, therefore each flywheel module has six degrees of freedom (DOF) as well as the satellite module. Equations of motion for the satellite and flywheels are naturally coupled and the satellite rotational motion and translational motion are coupled. A nonlinear state feedback tracking control law, which is globally asymptotically stable, is developed following a Lyapunov stability theory for integrated power and attitude control using the MB suspended flywheels. The stability, robustness, and tracking and disturbance rejection performance of the present control law with respect to initial attitude error, system modeling error, an imbalance disturbance, is demonstrated by case studies. The satellite departure motion equation derived from the definition of the angular velocity error and the system dynamics equations is presented. Application study of existing power tracking algorithm with this control law shows perfect power tracking for both power charging from and power delivery to the satellite operations and the power tracking can be performed simultaneously with and independent of the attitude control function.
German, Senta; Harris, Jim
2017-01-01
In this article, the authors argue that the art-historical canon, however it is construed, has little relevance to the selection of objects for museum-based teaching. Their contention is that all objects are fundamentally agile and capable of interrogation from any number of disciplinary standpoints, and that the canon of museum education,…
Greulich, K.A.; Archuleta, M.M.
1996-06-01
New pour-in-place, low density, rigid polyurethane foam kits have been developed to mechanically stabilize damaged explosive ordnance. Although earlier foam systems used chlorofluorocarbons as blowing agents, the current versions rely on carbon dioxide generated by the reaction of isocynates with water. In addition, these kits were developed to manually generate small quantifies of rigid foam in the field with minimal or no protective equipment. The purpose of this study was to evaluate and summarize available hazard information for the components of these rigid foam kits and to provide recommendations for personal protective equipment to be used while performing the manual combination of the components. As with most rigid foam systems, these kits consist of two parts, one a mixture of isocyanates; the other, a combination of polyols, surfactants, and amine catalysts. Once completely deployed, the rigid foam is non-toxic. The components, however, have some important health effects which must be considered when establishing handling procedures.
Hu, Henglong; Lu, Yuchao; Zhang, Jiaqiao; Qin, Baolong; Wang, Yufeng; Zhang, Zongbiao
2017-01-01
Object To compare the safety and efficacy of rigid ureteroscopic lithotripsy (rigid URSL) and percutaneous nephrolithotomy (PCNL) in treating large proximal ureteral stones. Methods A systematic search of PubMed, EMBASE, Cochrane Library, and Web of Science databases was performed to find out relevant studies. After literature screening according to the predetermined inclusion and exclusion criteria, data of eligible studies was extracted and then a meta-analysis was conducted via RevMan 5.3 software. Results Five randomized controlled trials (RCTs), one prospective and four retrospective cohort studies involving 837 patients were included. Patients underwent rigid URSL were associated with shorter operation time (WMD, -23.66min; 95%CI, −45.00 to -2.32; p = 0.03), shorter hospital stay (WMD, -2.76d; 95%CI, −3.51 to −2.02; phematuria (RR, 0.38; 95%CI, 0.25 to 0.57; p < 0.0001). No significant difference was observed in terms of incidence of embolization, pain and ureterostenosis. When cohort studies or studies in which flexible ureteroscopy was used as an intraoperative auxiliary procedure were excluded, we both found that most of the results kept stable. Conclusions Both PCNL and rigid URSL are safe for patients with large proximal ureteral stones while PCNL is more effective in stone clearance. PMID:28182718
Numerical simulation of a moving rigid body in a rarefied gas
Shrestha, Samir; Tiwari, Sudarshan; Klar, Axel; Hardt, Steffen
2015-07-01
In this paper we present a numerical scheme to simulate a moving rigid body with arbitrary shape suspended in a rarefied gas. The rarefied gas is simulated by solving the Boltzmann equation using a DSMC particle method. The motion of the rigid body is governed by the Newton-Euler equations, where the force and the torque on the rigid body are computed from the momentum transfer of the gas molecules colliding with the body. On the other hand, the motion of the rigid body influences the gas flow in its surroundings. We validate the numerical scheme by considering a moving piston problem in 1D and the Einstein relation for Brownian motion of the suspended particle in 3D. In the piston problem it is shown that the equilibrium position of the moving piston converges to the analytical solution for a wide range of Knudsen numbers. In the case of Brownian motion the translational as well as the rotational degrees of freedom are taken into account. In this case it is shown that the numerically computed translational and rotational diffusion coefficients converge to the theoretical values. Finally, the motion of an object of complex shape under the influence of a thermophoretic force is investigated.
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.
Tobias-Machado, Marcos; Hidaka, Alexandre Kiyoshi; Nunes-Silva, Igor; Chagas, Carlos Alberto; Leal, Leandro Correa; Pompeo, Antonio Carlos Lima
2016-01-01
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. PMID:27564304
Degeneration, Rigidity and Irreducible Components of Hopf Algebras
Abdenacer Makhlouf
2005-01-01
The aim of this work is to discuss the concepts of degeneration, deformation and rigidity of Hopf algebras and to apply them to the geometric study of the varieties of Hopf algebras. The main result is the description of the n-dimensional rigid Hopf algebras and the irreducible components for n ＜ 14 and n = p2 with p a prime number.
Non-rigid registration by geometry-constrained diffusion
Andresen, Per Rønsholt; Nielsen, Mads
2001-01-01
Assume that only partial knowledge about a non-rigid registration is given: certain points, curves, or surfaces in one 3D image are known to map to certain points, curves, or surfaces in another 3D image. In trying to identify the non-rigid registration field, we face a generalized aperture problem...
Non-rigid image registration using bone growth model
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 b...
Rigid Body Motion in Stereo 3D Simulation
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…
Reinforced molecular recognition as an alternative to rigid receptors
Otto, Sijbren
2006-01-01
In theory, a perfectly rigid receptor will probably be an unbeatable binder. However, rigidity may not be easy to achieve in practice and it is certainly not Nature’s method to realise high affinity. In many proteins binding affinity is increased through non-covalent interactions within the protein.
Quadratic Twists of Rigid Calabi–Yau Threefolds Over
Gouvêa, Fernando Q.; Kiming, Ian; Yui, Noriko
2013-01-01
We consider rigid Calabi–Yau threefolds defined over Q and the question of whether they admit quadratic twists. We give a precise geometric definition of the notion of a quadratic twists in this setting. Every rigid Calabi–Yau threefold over Q is modular so there is attached to it a certain newfo...
Stability of rigid body rotation from a bond graph perspective
Breedveld, Peter
2009-01-01
This paper describes the history of the bond graph description of rigid body rotation dynamics and resolves a paradox that resulted from the common Euler Junction Structure (EJS) description of the exterior product in the Newton–Euler equation describing rigid body rotation [D.C. Karnopp, R.C. Rosen
Humbert, Richard
2010-01-01
A force acting on just part of an extended object (either a solid or a volume of a liquid) can cause all of it to move. That motion is due to the transmission of the force through the object by its material. This paper discusses how the force is distributed to all of the object by a gradient of stress or pressure in it, which creates the local…
Awada, M
1995-01-01
Recently we have shown that a phase transition occurs in the leading approximation of the large N limit in rigid strings coupled to long range Kalb-Ramond interactions. The disordered phase is essentially the Nambu-Goto-Polyakov string theory while The ordered phase is a new theory. In this part I letter we study the first subleading quantum corrections of the free rigid string and derive the renormalization group equation. We show that the theory is asymptotically free, thus the extrinsic curvature of the string drops out at large distance scales in the disordered phase. In part II we generalize the results of this letter to the interacting theory of rigid strings with the long range Kalb-Ramond interactions. We derive the renormalized mass gap equation and obtain the renormalized critical line. Our main and final result is that the phase transition does indeed survive quantum fluctuations.
Estimation of the ground shaking from the response of rigid bodies
Filomena de Silva
2016-12-01
Full Text Available The paper illustrates and compares simplified approaches to interpret the mechanisms of damage observed on rigid bodies in the cemetery of Amatrice, after the main shock (August 24, 2016, MW=6.0 of the Central Italy earthquake. The final goal of the work is to link the observed movements of the fallen objects to specific characteristics of the ground motion occurred at the specific site.
Rigidity-Preserving Team Partitions in Multiagent Networks.
Carboni, Daniela; Williams, Ryan K; Gasparri, Andrea; Ulivi, Giovanni; Sukhatme, Gaurav S
2015-12-01
Motivated by the strong influence network rigidity has on collaborative systems, in this paper, we consider the problem of partitioning a multiagent network into two sub-teams, a bipartition, such that the resulting sub-teams are topologically rigid. In this direction, we determine the existence conditions for rigidity-preserving bipartitions, and provide an iterative algorithm that identifies such partitions in polynomial time. In particular, the relationship between rigid graph partitions and the previously identified Z-link edge structure is given, yielding a feasible direction for graph search. Adapting a supergraph search mechanism, we then detail a methodology for discerning graphs cuts that represent valid rigid bipartitions. Next, we extend our methods to a decentralized context by exploiting leader election and an improved graph search to evaluate feasible cuts using only local agent-to-agent communication. Finally, full algorithm details and pseudocode are provided, together with simulation results that verify correctness and demonstrate complexity.
Rigidity sensing and adaptation through regulation of integrin types
Elosegui-Artola, Alberto; Bazellières, Elsa; Allen, Michael D.; Andreu, Ion; Oria, Roger; Sunyer, Raimon; Gomm, Jennifer J.; Marshall, John F.; Jones, J. Louise; Trepat, Xavier; Roca-Cusachs, Pere
2014-06-01
Tissue rigidity regulates processes in development, cancer and wound healing. However, how cells detect rigidity, and thereby modulate their behaviour, remains unknown. Here, we show that sensing and adaptation to matrix rigidity in breast myoepithelial cells is determined by the bond dynamics of different integrin types. Cell binding to fibronectin through either α5β1 integrins (constitutively expressed) or αvβ6 integrins (selectively expressed in cancer and development) adapts force generation, actin flow and integrin recruitment to rigidities associated with healthy or malignant tissue, respectively. In vitro experiments and theoretical modelling further demonstrate that this behaviour is explained by the different binding and unbinding rates of both integrin types to fibronectin. Moreover, rigidity sensing through differences in integrin bond dynamics applies both when integrins bind separately and when they compete for binding to fibronectin.
Hu, Jinyan; Li, Li; Yang, Yunfeng
2017-06-01
The hierarchical and successive approximate registration method of non-rigid medical image based on the thin-plate splines is proposed in the paper. There are two major novelties in the proposed method. First, the hierarchical registration based on Wavelet transform is used. The approximate image of Wavelet transform is selected as the registered object. Second, the successive approximation registration method is used to accomplish the non-rigid medical images registration, i.e. the local regions of the couple images are registered roughly based on the thin-plate splines, then, the current rough registration result is selected as the object to be registered in the following registration procedure. Experiments show that the proposed method is effective in the registration process of the non-rigid medical images.
Rigidity and Fluidity in Living and Nonliving Matter
Lopez, Jorge H.
Many of the standard equilibrium statistical mechanics techniques do not readily apply to non-equilibrium phase transitions such as the fluid-to-disordered solid transition found in repulsive particulate systems. Examples of repulsive particulate systems are sand grains and colloids. The first part of this thesis contributes to methods beyond equilibrium statistical mechanics to ultimately understand the nature of the fluid-to-disordered solid transition, or jamming, from a microscopic basis. In Chapter 2 we revisit the concept of minimal rigidity as applied to frictionless, repulsive soft sphere packings in two dimensions with the introduction of the jamming graph. Minimal rigidity is a purely combinatorial property encoded via Laman's theorem in two dimensions. It constrains the global, average coordination number of the graph, for instance. Minimal rigidity, however, does not address the geometry of local mechanical stability. The jamming graph contains both properties of global mechanical stability at the onset of jamming and local mechanical stability. We demonstrate how jamming graphs can be constructed using local rules via the Henneberg construction such that these graphs are of the constraint percolation type, where percolation is the study of connected structures in disordered networks. We then probe how jamming graphs destabilize, or become fluid-like, by deleting an edge/contact in the graph and computing the resulting rigid cluster distribution. We also uncover a new potentially diverging lengthscale associated with the random deletion of contacts. In Chapter 3 we study several constraint percolation models, such as k-core percolation and counter-balance percolation, on hyperbolic lattices to better understand the role of loops in such models. The constraints in these percolation models incorporate aspects of local mechanical rigidity found in jammed systems. The expectation is that since these models are indeed easier to analyze than the more
Modeling decomposition of rigid polyurethane foam
Hobbs, M.L.
1998-01-01
Rigid polyurethane foams are used as encapsulants to isolate and support thermally sensitive components within weapon systems. When exposed to abnormal thermal environments, such as fire, the polyurethane foam decomposes to form products having a wide distribution of molecular weights and can dominate the overall thermal response of the system. Decomposing foams have either been ignored by assuming the foam is not present, or have been empirically modeled by changing physical properties, such as thermal conductivity or emissivity, based on a prescribed decomposition temperature. The hypothesis addressed in the current work is that improved predictions of polyurethane foam degradation can be realized by using a more fundamental decomposition model based on chemical structure and vapor-liquid equilibrium, rather than merely fitting the data by changing physical properties at a prescribed decomposition temperature. The polyurethane decomposition model is founded on bond breaking of the primary polymer and formation of a secondary polymer which subsequently decomposes at high temperature. The bond breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA) from a single nonisothermal experiment with a heating rate of 20 C/min. Model predictions compare reasonably well with a separate nonisothermal TGA weight loss experiment with a heating rate of 200 C/min.
The rigidity of three flavor quark matter
Sharma, Rishi [Los Alamos National Laboratory; Mannarelli, Massimo [IEEC/CSIC
2008-01-01
Cold three flavor quark matter at large (but not asymptotically large) densities may exist in a crystalline color superconducting phase. These phases are characterized by a gap parameter {Delta} that varies periodieally in space, forming a crystal structure. A Ginzburg-Landau expansion in {Delta} shows that two crystal structures based on cubic symetry are particularly favorable, and may be the ground state of matter at densities present in neutron star cores. We derive the effective action for the phonon fields that describe space-and time-dependent fluctuations of the crystal structure formed by {Delta}, and obtain the shear modulus from the coefficients of the spatial derivative terms. Within a Ginzburg-Landau approximation, we find shear moduli which are 20 to 1000 times larger than those of neutron star crusts. This phase ofmatter is thus more rigid than any known material in the universe, but at the same time the crystalline color superconducting phase is also superftuid. These properties raise the possibility that the presence of this phase within neutron stars may have distinct implications for their phenomenology. For example, (some) pulsar glitches may originate in crystalline superconducting neutron star cores.
Heat transfer in suspensions of rigid particles
Brandt, Luca; Niazi Ardekani, Mehdi; Abouali, Omid
2016-11-01
We study the heat transfer in laminar Couette flow of suspensions of rigid neutrally buoyant particles by means of numerical simulations. An Immersed Boundary Method is coupled with a VOF approach to simulate the heat transfer in the fluid and solid phase, enabling us to fully resolve the heat diffusion. First, we consider spherical particles and show that the proposed algorithm is able to reproduce the correlations between heat flux across the channel, the particle volume fraction and the heat diffusivity obtained in laboratory experiments and recently proposed in the literature, results valid in the limit of vanishing inertia. We then investigate the role of inertia on the heat transfer and show an increase of the suspension diffusivity at finite particle Reynolds numbers. Finally, we vary the relativity diffusivity of the fluid and solid phase and investigate its effect on the effective heat flux across the channel. The data are analyzed by considering the ensemble averaged energy equation and decomposing the heat flux in 4 different contributions, related to diffusion in the solid and fluid phase, and the correlations between wall-normal velocity and temperature fluctuations. Results for non-spherical particles will be examined before the meeting. Supported by the European Research Council Grant No. ERC-2013- CoG-616186, TRITOS. The authors acknowledge computer time provided by SNIC (Swedish National Infrastructure for Computing).
CAMPBELL,PHILIP L.; PIERSON,LYNDON G.; WITZKE,EDWARD L.
1999-10-27
In the world of computers a trusted object is a collection of possibly-sensitive data and programs that can be allowed to reside and execute on a computer, even on an adversary's machine. Beyond the scope of one computer we believe that network-based agents in high-consequence and highly reliable applications will depend on this approach, and that the basis for such objects is what we call ''faithful execution.''
Ryöppy, Merja; Heiberg, Andreas
2015-01-01
possibilities to emerge. We present a study in which the Object Theatre approach is applied to redesign socially shared everyday products that are located in public places. This project demonstrates how Object Theatre offers a broad perspective form which to explore and present product interactions....... In particular, it emphasises the understanding of a product by relating and changing perspectives, and takes into account context of use and diverse social settings....
Query Load Balancing For Visible Object Extraction
Bukauskas, Linas; Bøhlen, Michael Hanspeter
2004-01-01
Interactive visual data explorations impose rigid real-time requirements on the extraction of visible objects. Often these requirements are met by deploying powerful hardware that maintains the entire data set in huge main memory structures. In this paper we propose an approach that retrieves...... objects along the path. The visible objects are retrieved incrementally, and it is possible to precisely control the query load and the number of retrieved objects. The minimal distance path method issues frequent queries and retrieves the lowest possible number of objects at each query point. The end...
Lammerding-Koeppel, Maria; Giesler, Marianne; Gornostayeva, Maryna; Narciss, Elisabeth; Wosnik, Annette; Zipfel, Stephan; Griewatz, Jan; Fritze, Olaf
2017-01-01
Objective: After adoption of the National Competency-based Learning Objectives Catalogue in Medicine [Nationaler Kompetenzbasierter Lernzielkatalog Medizin, NKLM], the German medical faculties are asked to test the learning obejctives recorded in it and evaluate them critically. The faculties require curricular transparency for competence-oriented transition of present curricula, which is best achieved by systematic curriculum mapping in comparison to the NKLM. Based on this inventory, curricula can be further developed target-oriented. Considerable resistance has to be expected when a complex existing curriculum is to be mapped for the first time and a faculty must be convinced of its usefulness. Headed by Tübingen, the faculties of Freiburg, Heidelberg, Mannheim and Tübingen rose to this task. This two-part article analyses and summarises how NKLM curriculum mapping was successful at the locations despite resistance. Part I presented the resources and structures that supported implementation. Part II focuses on factors that motivate individuals and groups of persons to cooperate in the faculties. Method: Both parts used the same method. In short, the joint project was systematically planned following the steps of project and change management and adjusted in the course of the process. From the beginning of the project, a Grounded-Theory approach was used to systematically collect detailed information on measures and developments at the faculties, to continually analyse them and to draw final conclusions. Results: At all sites, faculties, teachers, students and administrative staff were not per se willing to deal with the NKLM and its contents, and even less to map their present curricula. Analysis of the development reflected a number of factors that had either a negative effect on the willingness to cooperate when missing, or a positive one when present. These were: clear top-down and bottom-up management; continuous information of the faculty; user
Lammerding-Koeppel, Maria; Giesler, Marianne; Gornostayeva, Maryna; Narciss, Elisabeth; Wosnik, Annette; Zipfel, Stephan; Griewatz, Jan; Fritze, Olaf
2017-01-01
Objective: After adoption of the National Competency-based Learning Objectives Catalogue in Medicine [Nationaler Kompetenzbasierter Lernzielkatalog Medizin, NKLM], the German medical faculties are asked to test the learning obejctives recorded in it and evaluate them critically. The faculties require curricular transparency for competence-oriented transition of present curricula, which is best achieved by systematic curriculum mapping in comparison to the NKLM. Based on this inventory, curricula can be further developed target-oriented. Considerable resistance has to be expected when a complex existing curriculum is to be mapped for the first time and a faculty must be convinced of its usefulness. Headed by Tübingen, the faculties of Freiburg, Heidelberg, Mannheim and Tübingen rose to this task. This two-part article analyses and summarises how NKLM curriculum mapping was successful at the locations despite resistance. Part I presented the resources and structures that supported implementation. Part II focuses on factors that motivate individuals and groups of persons to cooperate in the faculties. Method: Both parts used the same method. In short, the joint project was systematically planned following the steps of project and change management and adjusted in the course of the process. From the beginning of the project, a Grounded-Theory approach was used to systematically collect detailed information on measures and developments at the faculties, to continually analyse them and to draw final conclusions. Results: At all sites, faculties, teachers, students and administrative staff were not per se willing to deal with the NKLM and its contents, and even less to map their present curricula. Analysis of the development reflected a number of factors that had either a negative effect on the willingness to cooperate when missing, or a positive one when present. These were: clear top-down and bottom-up management; continuous information of the faculty; user
Andersen, Bjørn Schiermer
2009-01-01
This article attempts to create a framework for understanding modern fashion phenomena on the basis of Durkheim's sociology of religion. It focuses on Durkheim's conception of the relation between the cult and the sacred object, on his notion of 'exteriorisation', and on his theory of the social...... symbol in an attempt to describe the peculiar attraction of the fashion object and its social constitution. However, Durkheim's notions of cult and ritual must undergo profound changes if they are to be used in an analysis of fashion. The article tries to expand the Durkheimian cult, radically enlarging...... it without totally dispersing it; depicting it as held together exclusively by the sheer 'force' of the sacred object. Firstly, the article introduces the themes and problems surrounding Durkheim's conception of the sacred. Next, it briefly sketches an outline of fashion phenomena in Durkheimian categories...
Dynamic spindle reflexes and the rigidity of Parkinsonism.
McLellan, D L
1973-06-01
The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.
DeVoe, Jiva
2011-01-01
A soup-to-nuts guide on the Objective-C programming language. Objective-C is the language behind Cocoa and Cocoa Touch, which is the Framework of applications written for the Macintosh, iPod touch, iPhone, and iPad platforms. Part of the Developer Reference series covering the hottest Apple topics, this book covers everything from the basics of the C language to advanced aspects of Apple development. You'll examine Objective-C and high-level subjects of frameworks, threading, networking, and much more.: Covers the basics of the C language and then quickly moves onto Objective-C and more advanc
I. Rheology of Weakly Flocculated Suspensions of Rigid Particles
Snabre, P.; Mills, P.
1996-12-01
A rheological law for hard spheres in purely hydrodynamic interaction is used to describe the steady state viscosity of weakly aggregated suspensions of rigid particles. The shear viscosity only involves the volume fraction and the maximum packing concentration of particles. Particle aggregation influences the parameters of the reference viscosity law. Within the framework of fractal aggregation, we introduce the volume fraction of aggregates and we derive the equilibrium mean radius of clusters from an effective medium approximation. The proposed rheological equation is close to the phenomenological Casson equation for soft clusters of fractal dimensionality D=2. In a second part, we present rheo-optical experiments for studying the break-up of red cell aggregates in a shear flow and for determining the critical disaggregation shear stress of the flowing suspension mainly representative of the surface adhesive energy between particles. The proposed microrheological model well describes viscometric data in the low shear regime and allows information about the shear induced restructuration and the lifetime of clusters. Nous utilisons une loi de viscosité pour des suspensions concentrées de sphères dures en interaction purement hydrodynamique pour décrire le comportement rhéologique des suspensions faiblement agrégées de particules rigides. La viscosité de cisaillement fait intervenir la fraction volumique et la concentration d'empilement des particules. La floculation des particules modifie les paramètres de la loi rhéologique. Dans le cadre de structures fractales, nous introduisons la fraction volumique effective des agrégats et nous déterminons la taille de d'équilibre des amas à partir d'une hypothèse de milieu effectif. La loi de viscosité se rapproche de la loi phénoménologique de Casson pour des aggrégats mous de dimension fractale D=2. Dans une seconde partie, nous présentons des expériences de réflectométrie sous cisaillement pour
Nematic order by elastic interactions and cellular rigidity sensing
Friedrich, B. M.; Safran, S. A.
2011-01-01
We predict spontaneous nematic order in an ensemble of active force generators with elastic interactions as a minimal model for early nematic alignment of short stress fibers in non-motile, adhered cells. Mean-field theory is formally equivalent to Maier-Saupe theory for a nematic liquid. However, the elastic interactions are long-ranged (and thus depend on cell shape and matrix elasticity) and originate in cell activity. Depending on the density of force generators, we find two regimes of cellular rigidity sensing for which orientational, nematic order of stress fibers depends on matrix rigidity either in a step-like manner or with a maximum at an optimal rigidity.
Stochastic modeling of uncertain mass characteristics in rigid body dynamics
Richter, Lanae A.; Mignolet, Marc P.
2017-03-01
This paper focuses on the formulation, assessment, and application of a modeling strategy of uncertainty on the mass characteristics of rigid bodies, i.e. mass, position of center of mass, and inertia tensor. These characteristics are regrouped into a 4×4 matrix the elements of which are represented as random variables with joint probability density function derived following the maximum entropy framework. This stochastic model is first shown to satisfy all properties expected of the mass and tensor of inertia of rigid bodies. Its usefulness and computational efficiency are next demonstrated on the behavior of a rigid body in pure rotation exhibiting significant uncertainty in mass distribution.
Observations on the partial breaking of N=2 rigid supersymmetry
Laura Andrianopoli
2015-05-01
Full Text Available We study the partial breaking of N=2 rigid supersymmetry for a generic rigid special geometry of n abelian vector multiplets in the presence of Fayet–Iliopoulos terms induced by the hyper-Kähler momentum map. By exhibiting the symplectic structure of the problem we give invariant conditions for the breaking to occur, which rely on a quartic invariant of the Fayet–Iliopoulos charges as well as on a modification of the N=2 rigid symmetry algebra by a vector central charge.
Isoperimetric inequality fortorsional rigidity in the complex plane
Salahudinov RG
2001-01-01
Full Text Available Suppose SZ is a simply connected domain in the complex plane. In (F.G. Avhadiev, Matem. Sborn., 189(12 (1998, 3–12 (Russian, Avhadiev introduced new geometrical functionals, which give two-sided estimates for the torsional rigidity of . In this paper we find sharp lower bounds for the ratio of the torsional rigidity to the new functionals. In particular, we prove that where is the torsional rigidity of , and is the conformal radius of at a point .
STATISTICAL MODELS FOR SEMI-RIGID NEMATIC POLYMERS
WANG Xinjiu
1995-01-01
Semi-rigid liquid crystal polymer is a class of liquid crystal polymers different from long rigid rod liquid crystal polymer to which the well-known Onsager and Flory theories are applied. In this paper, three statistical models for the semi-rigid nematic polymer were addressed. They are the elastically jointed rod model, worm-like chain model, and non-homogeneous chain model.The nematic-isotropic transition temperature was examined. The pseudo-second transition temperature is expressed analytically. Comparisons with the experiments were made and the agreements were found.
Application of the upper bound element technique with triangular rigid blocks in indentation
Bermudo, C.; Martín, F.; Sevilla, L.
2012-04-01
Present work develops the Triangular Rigid Blocks method (TRB) by means of the Upper Bound Element Technique (UBET) on indentation, a plastic deformation process. Boundary conditions of this process does not limit the vertical material flow in the opposite direction to the applied load, and the die-block has not effect on the entire top surface part, in contrast to previous studies developed on forging processes. The application of this method by studying the behaviour of different geometrical-kinematic alternatives allows obtaining a minimum load value that ensures the deformation of the part, with the possibility of inclusion of different parameters that govern and determine the deformation process.
洪军; 武殿梁; 李涤尘; 卢秉恒
2001-01-01
阐述了快速成型中与制作方向相关的质量与经济性问题，对制作方向的优化目标进行了定义，并依据该目标建立了制作方向多目标优化模型．针对悬臂变形、台阶效应、过固化及制作时间，分别构造了子目标函数，利用评价函数法，把制作方向优化的多个目标函数转化为一个数值目标的评价函数，并给出了优化模型的约束函数．最后，以该优化模型作为计算的理论依据，进行了应用实例的方向优化．计算结果表明：该模型准确地表达了快速成型中的制作方向优化问题，理论正确，方法可行．%The quality and cost related to the part building orientation are discussed and an optimization objective of the building orientation is defined. Considering the cantilever deformation, step-effect, over-curing and building time, the sub-objective functions are constructed. Using evaluation function, the multi-objective function is converted into an evaluation function with single objective and the constraint function of optimization model is formulated. Using this optimization model as the theoretical basis in computation, the orientation optimization of a practical case was done. The results show that this modal correctly represents the building-orientation optimization in stereolithography process, and the method is feasible.
Optimisation of grolishing freeform surfaces with rigid and semi-rigid tools
Yu, Guoyu; Wu, Hsing-Yu; Walker, David; Zheng, Xiao; Li, Hongyu; Dunn, Christina; Gray, Caroline
2016-07-01
After the formal acceptance of our fabrication of E-ELT segments, we aim to further accelerate the mass production by introducing an intermediate grolishing procedure using industrial robots, reducing the total process time by this much faster and parallel link. In this paper, we have presented research outputs on tool design, tool path generation, study of mismatch between rigid, semi-rigid tool and aspheric surface. It is indicated that the generation of mid-spatial frequency is proportional to the grit size and misfit between work piece and tool surfaces. Using a Non-Newtonian material tool with a spindle speed of 30 rpm has successfully reduce the mid-spatial error. The optimization of process parameters involve the study the combination effects of the above factors. These optimized parameters will result in a lookup table for reference of given input surface quality. Future work may include the higher spindle speed for grolishing with non- Newtonian tool looking for potential applications regarding to form correction, higher removal rate and edge control.
Mid-Level Vision and Recognition of Non-Rigid Objects.
1993-01-01
management of technology and beyond. Carlos Angulo , Ramon Lopez de Mantaras, Ignasi Juvells, Ton Sales, Josep Amat, Lluis Puigjaner, Teresa Riera, Didac Hita... knee in Figure 3.5). This problem has been addressed in the past [Zhong and Mallat 1990], [Lu and Jain 1989], [Clark 1988], [Geiger and Poggio 1987...2, and Canny. no 1 s s 4R 3 p " e 1 2 1 o e R 2+h2 22o R cosh( Rh 2o ) h sinh(Rh 2o ) !# ; (3:20) where o q R2 + h2 2Rh(1 e
Plastic Damage Model to Evaluate the Fracture Size of Semi-Rigid Base Pavement
Cao Peng
2013-01-01
Full Text Available A simple supported beam model has been presented to simulate the response of semi-rigid pavement structure, which are consistent of the upper layer, middle layer, bottom layer, base and sub base course, during the cycle vehicle loading. This mechanics model coupled with plastic-damage mechanics model could simulate the limit broken of the pavement structure in condition that soil base layer losing bearing capacity gradually. In the meanwhile, numerical calculations based on preceding mechanics model, using the FEM software ABAQUS, have been used to define the broken size of beam. The results indicated that: when the size of simple supported beam expanded to 10 m, brittle damage could happen immediately, Just the standard vehicle loading (about 0.7 Mpa has been implement once. Objective of this study is to provide a physical and rather concrete explanation for the style and concept of the semi-rigid pavement brittle broken.
Boundary value problem for the solution of magnetic cutoff rigidities and some special applications
Edmonds, Larry
1987-01-01
Since a planet's magnetic field can sometimes provide a spacecraft with some protection against cosmic ray and solar flare particles, it is important to be able to quantify this protection. This is done by calculating cutoff rigidities. An alternate to the conventional method (particle trajectory tracing) is introduced, which is to treat the problem as a boundary value problem. In this approach trajectory tracing is only needed to supply boundary conditions. In some special cases, trajectory tracing is not needed at all because the problem can be solved analytically. A differential equation governing cutoff rigidities is derived for static magnetic fields. The presense of solid objects, which can block a trajectory and other force fields are not included. A few qualititative comments, on existence and uniqueness of solutions, are made which may be useful when deciding how the boundary conditions should be set up. Also included are topics on axially symmetric fields.
Skow, Bradford
2015-01-01
Bradford Skow presents an original defense of the 'block universe' theory of time, often said to be a theory according to which time does not pass. Along the way, he provides in-depth discussions of alternative theories of time, including those in which there is 'robust passage' of time or 'objective becoming': presentism, the moving spotlight theory of time, the growing block theory of time, and the 'branching time' theory of time. Skow explains why the moving spotlight theory is the best of these arguments, and rebuts several popular arguments against the thesis that time passes. He surveys the problems that the special theory of relativity has been thought to raise for objective becoming, and suggests ways in which fans of objective becoming may reconcile their view with relativistic physics. The last third of the book aims to clarify and evaluate the argument that we should believe that time passes because, somehow, the passage of time is given to us in experience. He isolates three separate arguments thi...
无
2001-01-01
Compared with the traditional rigid-plastic/rigid-viscoplastic(RP/RVP) FEM(based on iteration solution),RP/RVP FEM based on linear programming (LP) has some remarkable advantages,such as it's free of convergence problem and its convenience in contact,rigid zone,and friction force treatment.The numerical model of RP/RVP FEM based on LP for axisymmetrical metal forming simulation is studied,and some related key factors and its treatment methods in formulation of constraint condition are proposed.Some solution examples are provided to validate its accuracy and efficiency.
Optimal matrix rigidity for stress fiber polarization in stem cells
Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.
2010-01-01
The shape and differentiation of human mesenchymal stem cells is especially sensitive to the rigidity of their environment; the physical mechanisms involved are unknown. A theoretical model and experiments demonstrate here that the polarization/alignment of stress-fibers within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix whose polarizability, unlike dead matter, depends on the feedback of cellular forces that develop in response to matrix stresses. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress-fibers parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress-fibers in stem cells. These findings offer a first physical insight for the dependence of stem cell differentiation on tissue elasticity. PMID:20563235
A Concise Introduction to Mechanics of Rigid Bodies Multidisciplinary Engineering
Huang, L
2012-01-01
A Concise Introduction to Mechanics of Rigid Bodies: Multidisciplinary Engineering presents concise, key concepts of kinematics and dynamics of rigid bodies. This compact volume bridges the steep gap between introductory texts on engineering mechanics, which focus on one and two dimensional motions of particles and rigid bodies, and advanced texts on multi-body dynamics in high dimension spaces found in multidisciplinary areas like mechatronics, robotics and biomechanics. In the book, rigid body motions in the spaces with different dimensions are described in addition to studies in a uniform framework supported by vector and matrix operations. Rigorous mathematic tools and explanations are provided to clarify the most complex concepts. This book also: Provides practical examples from different engineering areas, offering a link between theoretical fundamentals and everyday applications Offers simplified mathematical equations to clearly present essential theories in robotics and mechanics Presents statics...
Dynamical Equation of Post Newtonian Quasi-rigid Body
XU Chong-Ming; TAO Jin-He; HUANG Tian-Yi; WU Xue-Jun
2004-01-01
We derive the dynamical equation ofa post Newtonian (PN) quasi-rigid body from the general rotational equation of motion, I.e. The PN rotational equation of motion for a quasi-rigid body. It is emphasized that a rotational angular velocity vector and a figure axis besides the first post Newtonian (1PN) spin vector can be defined and realized for the model of a PN quasi-rigid body model constructed recently. Actually, we have shown that the moment of inertia tensor of a quasi-rigid body can be transformed into a diagonal form by an orthogonal transformation, which defines the principal axes of inertia of the body. As an example, its torque-free motion is discussed and a PN Poinsot configuration, which is similar to the Newtonian one with a small 1PN correction, is solved.
The role of rigidity in controlling material failure
Driscoll, Michelle M.; Chen, Bryan Gin-ge; Beuman, Thomas H.; Ulrich, Stephan; Nagel, Sidney R.; Vitelli, Vincenzo
2016-01-01
We investigate how material rigidity acts as a key control parameter for the failure of solids under stress. In both experiments and simulations, we demonstrate that material failure can be continuously tuned by varying the underlying rigidity of the material while holding the amount of disorder constant. As the rigidity transition is approached, failure due to the application of uniaxial stress evolves from brittle cracking to system-spanning diffuse breaking. This evolution in failure behavior can be parameterized by the width of the crack. As a system becomes more and more floppy, this crack width increases until it saturates at the system size. Thus, the spatial extent of the failure zone can be used as a direct probe for material rigidity. PMID:27621463
Resin Infusion Rigidized Inflatable Concept Development and Demonstration Project
National Aeronautics and Space Administration — Utilizing resin infusion to rigidize an inflatable structure and form fiber-reinforced composites on-orbit is a novel concept that builds on current NASA technology...
Genus Ranges of 4-Regular Rigid Vertex Graphs.
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 2n vertices (n > 1), we prove that all intervals [a, b] for all a genus ranges. For graphs with 2n - 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.
Sedimentation of Rigid Cylindrical Particles with Mechanical Contacts
LIN Jian-Zhong; WANG Ye-Long; James A. Olsen
2005-01-01
@@ A collision model of two cylindrical particles is put forward. Based on the model the sedimentation of rigid cylindrical particles with mechanical contacts is simulated numerically by using the lattice Boltzmann method.
Competing γ-rigid and γ-stable vibrations in neutron-rich Gd and Dy isotopes
Budaca, R.; Budaca, A.I. [Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele (Romania)
2015-10-15
An exactly separable version of the Bohr Hamiltonian which combines the γ-stable and γ-rigid axial vibration-rotation is used to describe the collective properties of few neutron-rich transitional nuclei. The coupling between the two types of collective motion is managed through a rigidity parameter which also influences the geometry of the shape phase space. While the γ-angular part of the problem associated to axially symmetric shapes is treated within the small angles approximation and the stiff γ oscillation hypothesis, the β vibration is described by means of a Davidson potential. The resulting model have three free parameters not counting the scale and was successfully applied for the description of the collective spectra for few heavier isotopes of Gd and Dy. In both cases a critical nucleus was identified through a discontinuous behavior in respect to the rigidity parameter and relevant experimental observables. (orig.)
21 CFR 874.4710 - Esophagoscope (flexible or rigid) and accessories.
2010-04-01
... generic type of device includes the flexible foreign body claw, flexible biopsy forceps, rigid biopsy curette, flexible biopsy brush, rigid biopsy forceps and flexible biopsy curette, but excludes...
Lens rigidity with trapped geodesics in two dimensions
Croke, Christopher B
2011-01-01
We consider the scattering and lens rigidity of compact surfaces with boundary that have a trapped geodesic. In particular we show that the flat cylinder and the flat M\\"obius strip are determined by their lens data. We also see by example that the flat M\\"obius strip is not determined by it's scattering data. We then consider the case of negatively curved cylinders with convex boundary and show that they are lens rigid.
Modeling the Collision with Friction of Rigid Bodies
Zabuga, A. G.
2016-09-01
Different models of a perfectly inelastic collision of rigid bodies in plane motion are compared. Formulas for the impact impulses are derived for the Kane-Levinson-Whittaker model based on the kinematic restitution factor, the Routh model based on the kinetic restitution factor, and the Stronge model based on the energy restitution factor. It is shown that these formulas coincide if the collision of rough rigid bodies in plane motion is perfectly inelastic
Flexible band versus rigid ring annuloplasty for functional tricuspid regurgitation
Kanji Kawachi
2010-09-01
Full Text Available We review and compare our experience with tricuspid ring annuloplasty between usage of the Cosgrove-Edwards flexible band and the MC3 rigid ring for repair of functional tricuspid regurgitation to determine the efficacy and mid-term durability of tricuspid annuloplasty. 117 patients with functional tricuspid regurgitation undergoing open heart surgery and tricuspid valve repair from May 2005 to December 2007 were reviewed. The flexible bands were used in thirty five patients before October 2006. Since then, the rigid rings were used in the next consecutive eighty two cases. Echocardiographic evaluation of tricuspid regurgitation was performed preoperatively and postoperatively in follow-up schedule. The degree of tricuspid regurgitation was reduced from 2.80±0.67 to 0.71±1.0 (regurgitation severity grade: 0 to 4 in the patients with flexible bands at discharge. It was from 2.68±0.70 to 0.22±0.60 in the patients with rigid rings. At thirty six months postoperative period, tricuspid regurgitation grades in patients with flexible bands and rigid rings were 0.80±0.95 and 0.36±0.77, respectively. Freedom from recurrent tricuspid regurgitation (grade 2 or 3 in patients with flexible bands and rigid rings were 68.6% and 87.8%, respectively. Recurrent tricuspid regurgitation was significantly lower in the patients with rigid rings. Although both flexible band and rigid ring annuloplasty provide low rate of recurrent tricuspid regurgitation, rigid ring annuloplasty might be more effective than flexible band annuloplasty for decreasing functional tricuspid regurgitation in immediate and mid-term postoperative periods.
Plasticity-rigidity cycles: A general adaptation mechanism
Csermely, Peter
2015-01-01
Successful adaptation helped the emergence of complexity. Alternating plastic- and rigid-like states were recurrently considered to play a role in adaptive processes. However, this extensive knowledge remained fragmented. In this paper I describe plasticity-rigidity cycles as a general adaptation mechanism operating in molecular assemblies, assisted protein folding, cellular differentiation, learning, memory formation, creative thinking, as well as the organization of social groups and ecosys...
Stochastic finite element applications in rigid pavement performance
Attoh-Okine, Nii O.
1999-05-01
Rigid pavement structures have uncertainties and variability in their structural layers and components. These variations and uncertainties are seldomly included in performance assessment and evaluation in pavement systems. This paper proposes to use Stochastic Finite Element Method (SFEM) in rigid pavement faulting and load transfer efficiency. The SFEM uses random parameters, as stochastic process namely random fields. These random fields are characterized, quantitatively by spatial functions of statistical moment like the mean, variance and covariance.
Murjas, Teresa
2012-01-01
Surviving Objects (2012) is a devised multi-media practice-as-research performance based on extensive interviews conducted with my elderly mother and recorded on a hand-held device. Our conversations concern her experiences as a child refugee following violent deportation by the Soviet Army from Eastern Poland to Siberia (1941), and her subsequent route, via Persia, to a British-run refugee camp in Northern Rhodesia, where she remained for 6 years before arriving in the UK. In order to aid my...
The rigidity dependence of Forbush decreases observed at the Earth
Lockwood, J.A.; Webber, W.R. (Univ. of New Hampshire, Durham (USA)); Debrunner, H. (Univ. of Bern (Switzerland))
1991-04-01
The rigidity dependence of the large Forbush decreases occurring on July 23, 1981, July 11, 1982, and February 6, 1986, has been determined using neutron monitor and IMP spacecraft data which cover the energy range from about 50 MeV to 30 GeV. The contribution of solar flare protons to the lower-energy data from the IMP cosmic ray telescopes was carefully removed. The authors found that the rigidity dependences of the magnitudes of the July 1981, July 1982, and February 1986 Forbush decreases for P {ge} 2 GV were given by exp ({minus}1/P{sup 0.75}), exp ({minus}1/P{sup 0.6}), and exp ({minus}1/P{sup 1.0}), respectively. For 0.5 {le} P {le} 2 GV the magnitude of the Forbush decreases in July 1981 and July 1982 was rigidity independent. The February 1986 event also appeared to be rigidity independent below {approximately}1 GV. The characteristic recovery time of these Forbush decreases was found to be not strongly rigidity dependent. These results on the rigidity dependence of Forbush decreases for 0.5 < P < 20 GV are discussed in the context of proposed models.
Non-rigid registration using higher-order mutual information
Rueckert, D.; Clarkson, M. J.; Hill, D. L. G.; Hawkes, D. J.
2000-03-01
Non-rigid registration of multi-modality images is an important tool for assessing temporal and structural changesbetween images. For rigid registration, voxel similarity measures like mutual information have been shown to alignimages from different modalities accurately and robustly. For non-rigid registration, mutual information can besensitive to local variations of intensity which in MR images may be caused by RF inhomogeneity. The reasonfor the sensitivity of mutual information towards intensity variations stems from the fact that mutual informationignores any spatial information. In this paper we propose an extension of the mutual information framework whichincorporates spatial information about higher-order image structure into the registration process and has the potentialto improve the accuracy and robustness of non-rigid registration in the presence of intensity variations. We haveapplied the non-rigid registration algorithm to a number of simulated MR brain images of a digital phantom whichhave been degraded by a simulated intensity shading and a known deformation. In addition, we have applied thealgorithm for the non-rigid registration of eight pre- and post-operative brain MR images which were acquired withan interventional MR scanner and therefore have substantial intensity shading due to RF field inhomogeneities. Inall cases the second-order estimate of mutual information leads to robust and accurate registration.
Yagi, Akihiko; Matsumiya, Kiyoshi; Masamune, Ken; Liao, Hongen; Dohi, Takeyoshi
2006-01-01
The objective of this paper is to develop an outer sheath for flexible endoscopic manipulators. This sheath can switch two states including flexible and rigid, and make a rigid curved path for inserting manipulators. The flexible mode can be curved into a required shape. The rigid mode can hold the shape of the sheath, and then keep the path for instruments. Through the managed path, the flexible manipulators become easy to reach the target. We proposed a serial multi joint model to realize the flexible mechanism. This model is composed of a set of frame units which are connected serially. Each unit can be rotated to a given angle around the center of the joint. We developed a slider-link mechanism and a gear stopper controlled by air pressure for rigid mode. We designed and fabricated the prototype with a diameter of 16 mm and length of 290 mm. The experiment showed that the device could be switched from the flexible mode to the rigid mode when the air pressure was over 150 kPa, and each joint could hold its angle against the maximum 400 mNm. The phantom experiment showed that the flexible devices are possible to transmit the wire tension to the endpoint of the manipulator without changing the curving shape with by the developed outer sheath device.
Lammerding-Koeppel, Maria; Giesler, Marianne; Gornostayeva, Maryna; Narciss, Elisabeth; Wosnik, Annette; Zipfel, Stephan; Griewatz, Jan; Fritze, Olaf
2017-01-01
Objective: After passing of the National Competency-based Learning Objectives Catalogue in Medicine (Nationaler Kompetenzbasierter Lernzielkatalog Medizin, [NKLM, retrieved on 22.03.2016]), the German medical faculties must take inventory and develop their curricula. NKLM contents are expected to be present, but not linked well or sensibly enough in locally grown curricula. Learning and examination formats must be reviewed for appropriateness and coverage of the competences. The necessary curricular transparency is best achieved by systematic curriculum mapping, combined with effective change management. Mapping a complex existing curriculum and convincing a faculty that this will have benefits is not easy. Headed by Tübingen, the faculties of Freiburg, Heidelberg, Mannheim and Tübingen take inventory by mapping their curricula in comparison to the NKLM, using the dedicated web-based MERLIN-database. This two-part article analyses and summarises how NKLM curriculum mapping could be successful in spite of resistance at the faculties. The target is conveying the widest possible overview of beneficial framework conditions, strategies and results. Part I of the article shows the beneficial resources and structures required for implementation of curriculum mapping at the faculties. Part II describes key factors relevant for motivating faculties and teachers during the mapping process. Method: The network project was systematically planned in advance according to steps of project and change management, regularly reflected on and adjusted together in workshops and semi-annual project meetings. From the beginning of the project, a grounded-theory approach was used to systematically collect detailed information on structures, measures and developments at the faculties using various sources and methods, to continually analyse them and to draw a final conclusion (sources: surveys among the project participants with questionnaires, semi-structured group interviews and
Lammerding-Koeppel, Maria
2017-02-01
Full Text Available Objective: After passing of the National Competency-based Learning Objectives Catalogue in Medicine (Nationaler Kompetenzbasierter Lernzielkatalog Medizin, [, retrieved on 22.03.2016], the German medical faculties must take inventory and develop their curricula. NKLM contents are expected to be present, but not linked well or sensibly enough in locally grown curricula. Learning and examination formats must be reviewed for appropriateness and coverage of the competences. The necessary curricular transparency is best achieved by systematic curriculum mapping, combined with effective change management. Mapping a complex existing curriculum and convincing a faculty that this will have benefits is not easy. Headed by Tübingen, the faculties of Freiburg, Heidelberg, Mannheim and Tübingen take inventory by mapping their curricula in comparison to the NKLM, using the dedicated web-based MER-database. This two-part article analyses and summarises how NKLM curriculum mapping could be successful in spite of resistance at the faculties. The target is conveying the widest possible overview of beneficial framework conditions, strategies and results. Part I of the article shows the beneficial resources and structures required for implementation of curriculum mapping at the faculties. Part II describes key factors relevant for motivating faculties and teachers during the mapping process.Method: The network project was systematically planned in advance according to steps of project and change management, regularly reflected on and adjusted together in workshops and semi-annual project meetings. From the beginning of the project, a grounded-theory approach was used to systematically collect detailed information on structures, measures and developments at the faculties using various sources and methods, to continually analyse them and to draw a final conclusion (sources: surveys among the project participants with questionnaires, semi-structured group interviews
Objects, materiality and meaning
Lenau, Torben Anker; Lindegaard, Hanne
2008-01-01
The present research work investigates the relation between physical objects, their materiality, understood as the physical substances they are made from, and the communication from the objects. In product design of physical objects the communicative aspects are just as important as the function ...... be written into the object. The materials are therefore carriers of communication, even though this is dependent of the cultural context and the environment which the object will be part of. However the designer has only minor influence on those.......The present research work investigates the relation between physical objects, their materiality, understood as the physical substances they are made from, and the communication from the objects. In product design of physical objects the communicative aspects are just as important as the function...... of the object, and the designers aim is therefore to tune both in order to achieve a desired goal. To do so the designer basically has 2 options: Alteration of the physical shape of the object and the selection of materials. Through the manipulation of shape and materials can symbolic and sensory information...
Fülöp, Tamás
2015-01-01
An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly, utilizing the Weyl-Matolcsi description of spacetime. This restricts the range of definable kinematic quantities heavily. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but a relaxed metric, too, that represents the natural geometric structure of the solid. The comparison of the instantaneous metric to the relaxed one is the basis of the definition of the elastic state variable, the elastic deformedness tensor. Thermal expansion is conceived as the temperature dependence of the relaxed metric. As opposed to this reversible type of change, plasticity means an irreversible change in the relaxed metric, and is describable via a plastic change rate tensor. The relat...
Dovey, James
2012-01-01
Objective-C is today's fastest growing programming language, at least in part due to the popularity of Apple's Mac, iPhone and iPad. Beginning Objective-C is for you if you have some programming experience, but you're new to the Objective-C programming language and you want a modern-and fast-way forwards to your own coding projects. Beginning Objective-C offers you a modern programmer's perspective on Objective-C courtesy of two of the best iOS and Mac developers in the field today, and gets you programming to the best of your ability in this important language. It gets you rolling fast into
EVolution: an edge-based variational method for non-rigid multi-modal image registration.
Denis de Senneville, B; Zachiu, C; Ries, M; Moonen, C
2016-10-21
Image registration is part of a large variety of medical applications including diagnosis, monitoring disease progression and/or treatment effectiveness and, more recently, therapy guidance. Such applications usually involve several imaging modalities such as ultrasound, computed tomography, positron emission tomography, x-ray or magnetic resonance imaging, either separately or combined. In the current work, we propose a non-rigid multi-modal registration method (namely EVolution: an edge-based variational method for non-rigid multi-modal image registration) that aims at maximizing edge alignment between the images being registered. The proposed algorithm requires only contrasts between physiological tissues, preferably present in both image modalities, and assumes deformable/elastic tissues. Given both is shown to be well suitable for non-rigid co-registration across different image types/contrasts (T1/T2) as well as different modalities (CT/MRI). This is achieved using a variational scheme that provides a fast algorithm with a low number of control parameters. Results obtained on an annotated CT data set were comparable to the ones provided by state-of-the-art multi-modal image registration algorithms, for all tested experimental conditions (image pre-filtering, image intensity variation, noise perturbation). Moreover, we demonstrate that, compared to existing approaches, our method possesses increased robustness to transient structures (i.e. that are only present in some of the images).
EVolution: an edge-based variational method for non-rigid multi-modal image registration
de Senneville, B. Denis; Zachiu, C.; Ries, M.; Moonen, C.
2016-10-01
Image registration is part of a large variety of medical applications including diagnosis, monitoring disease progression and/or treatment effectiveness and, more recently, therapy guidance. Such applications usually involve several imaging modalities such as ultrasound, computed tomography, positron emission tomography, x-ray or magnetic resonance imaging, either separately or combined. In the current work, we propose a non-rigid multi-modal registration method (namely EVolution: an edge-based variational method for non-rigid multi-modal image registration) that aims at maximizing edge alignment between the images being registered. The proposed algorithm requires only contrasts between physiological tissues, preferably present in both image modalities, and assumes deformable/elastic tissues. Given both is shown to be well suitable for non-rigid co-registration across different image types/contrasts (T1/T2) as well as different modalities (CT/MRI). This is achieved using a variational scheme that provides a fast algorithm with a low number of control parameters. Results obtained on an annotated CT data set were comparable to the ones provided by state-of-the-art multi-modal image registration algorithms, for all tested experimental conditions (image pre-filtering, image intensity variation, noise perturbation). Moreover, we demonstrate that, compared to existing approaches, our method possesses increased robustness to transient structures (i.e. that are only present in some of the images).
Design of Rigid and Flexible Pavements by Various Methods & Their Cost Analysis of Each Method
Saurabh Jain
2013-09-01
Full Text Available Highway and pavement design plays an important role in the DPR projects. The satisfactory performance of the pavement will result in higher savings in terms of vehicle operating costs and travel time, which has a bearing on the overall economic feasibility of the project. This paper discusses about the design methods that are traditionally being followed and examines the “Design of rigid and flexible pavements by various methods & their cost analysis by each method”. Flexible pavement are preferred over cement concrete roads as they have a great advantage that these can be strengthened and improved in stages with the growth of traffic and also their surfaces can be milled and recycled for rehabilitation. The flexible pavements are less expensive also with regard to initial investment and maintenance. Although Rigid pavement is expensive but have less maintenance and having good design period. The economic part are carried out for the design pavement of a section by using the result obtain by design method and their corresponding component layer thickness. It can be done by drawing comparisons with the standard way and practical way. This total work includes collection of data analysis various flexible and rigid pavement designs and their estimation procedure are very much useful to engineer who deals with highways.
Approximate Bayesian methods for kernel-based object tracking
Zivkovic, Z.; Cemgil, A.T.; Kröse, B.
2009-01-01
A framework for real-time tracking of complex non-rigid objects is presented. The object shape is approximated by an ellipse and its appearance by histogram based features derived from local image properties. An efficient search procedure is used to find the image region with a histogram most simila
钟来平; 陈关福
2004-01-01
Objective: To introduce the technique of subciliary incision and lateral cantholysis with tri-dimension reduction and rigid internal fixation to treat zygomatic complex fractures.Methods: The subciliary incision and lateral cantholysis combined with tri-dimension reduction and rigid internal fixation of zygomatic complex fractures with titanium microplates were applied in 56 patients with zygomatic complex fractures. Another lateral eyebrow incision or sublabial incision was used to simplify the operation.Results: The postoperative follow-up period ranged from 6 months to 5 years. During the follow-up period, all the patients had satisfying postoperative results. All clinical symptoms disappeared except the numbness in the infraorbital region in 2 patients. In 94.6% patients no complications such as obvious scar, ectropion, entropion or blepharoedema were found, only 5.4% of the patients had slight ectropion 6 months after operation.Conclusions: The subciliary incision and lateral cantholysis have many advantages such as invisible scar,sufficient exposure, minimal injury, and few complications and combined with rigid internal fixation with titanium microplates this technique could be used as one of the routine operation methods to treat zygomatic complex fractures.
The temporal dynamics of heading perception in the presence of moving objects.
Layton, Oliver W; Fajen, Brett R
2016-01-01
Many forms of locomotion rely on the ability to accurately perceive one's direction of locomotion (i.e., heading) based on optic flow. Although accurate in rigid environments, heading judgments may be biased when independently moving objects are present. The aim of this study was to systematically investigate the conditions in which moving objects influence heading perception, with a focus on the temporal dynamics and the mechanisms underlying this bias. Subjects viewed stimuli simulating linear self-motion in the presence of a moving object and judged their direction of heading. Experiments 1 and 2 revealed that heading perception is biased when the object crosses or almost crosses the observer's future path toward the end of the trial, but not when the object crosses earlier in the trial. Nonetheless, heading perception is not based entirely on the instantaneous optic flow toward the end of the trial. This was demonstrated in Experiment 3 by varying the portion of the earlier part of the trial leading up to the last frame that was presented to subjects. When the stimulus duration was long enough to include the part of the trial before the moving object crossed the observer's path, heading judgments were less biased. The findings suggest that heading perception is affected by the temporal evolution of optic flow. The time course of dorsal medial superior temporal area (MSTd) neuron responses may play a crucial role in perceiving heading in the presence of moving objects, a property not captured by many existing models.
Effect of rigid cervical collar on tracheal intubation using Airtraq®
Padmaja Durga
2014-01-01
Full Text Available Background and Aims: Cervical spine immobilisation with rigid cervical collar imposes difficulty in intubation. Removal of the anterior part of the collar may jeopardize the safety of the cervical spine. The effect of restricted mouth opening and cervical spine immobilisation that result from the application of rigid cervical collar on intubation using Airtraq ® was evaluated. Methods: Seventy healthy adults with normal airways included in the study were intubated Using Airtraq® with (group C and without rigid cervical collar (group NC. The ease of insertion of Airtraq ® into the oral cavity, intubation time, intubation difficulty score (IDS were compared using Wilcoxon sign ranked test and McNemar test, using SPSS version 13. Results: Intubation using Airtraq ® was successful in the presence of the cervical collar in 96% which was comparable to group without collar (P = 0.24. The restriction of mouth opening resulted in mild difficulty in insertion of Airtraq ® . The median Likert scale for insertion was - 1 in the group C and + 1 in group NC (P < 0.001. The intubation time was longer in group C (30 ± 14.3 s vs. 26.9 ± 14.8 s compared to group NC. The need for adjusting manoeuvres was 18.5% in group C versus 6.2% in group NC (P = 0.003 and bougie was required in 12 (18.5% and 4 (6.2% patients in group C and NC, respectively, to facilitate intubation (P = 0.02. The modified IDS score was higher in group C but there was no difference in the number of patients with IDS < 2. Conclusion: Tracheal intubation using Airtraq ® in the presence of rigid cervical collar has equivalent success rate, acceptable difficulty in insertion and mild increase in IDS.
Randomized trial comparing office flexible to rigid cystoscopy in women.
Quiroz, Lieschen H; Shobeiri, S Abbas; Nihira, Mikio A; Brady, Jordan; Wild, Robert A
2012-11-01
The objective of the study was to compare office rigid cystoscopy (RC) versus flexible cystoscopy (FC) in women. This was a prospective randomized trial comparing FC to RC. Aims were to assess 1-week post-procedural complications, compare procedure pain scores, and to assess physician perception of patient discomfort. Pain scores were assessed by visual analogue scale (VAS) and 5-point verbal descriptor scale (VDS). Chi-square was used for categorical comparison and t tests or Wilcoxon test for continuous variables. One hundred women were enrolled. The mean age of participants was 59.7 years (± SD 14.6), and 91 % were Caucasian. This was the first cystoscopy for 86 % of participants. On the 1-week post-procedure questionnaire (85 % response rate), participants in the FC group reported urinary frequency more often than in the RC group (p = 0.041). The FC group reported urgency with urination lasting 1-2 days (p = 0.030) and burning with urination lasting >3 days (p = 0.026), more than the RC group. These symptoms did not persist at 7 days. The duration of the procedure was slightly faster for the FC group (4.6 ± 1.8 min vs 5.7 ± 3.4 min, p = 0.046). Median VAS scores were 0.9 (0.1-2.72) for the FC group and 0.5 (0-2.4) for the RC group (p = 0.505). There were no significant differences between patient or physician perception of pain in either group. Urinary frequency and duration of urinary burning post procedure occurred more frequently in the FC group, although these symptoms were transient. Both office FC and RC are generally well tolerated in women with overall low morbidity.
An information theoretic approach for non-rigid image registration using voxel class probabilities.
D'Agostino, Emiliano; Maes, Frederik; Vandermeulen, Dirk; Suetens, Paul
2006-06-01
We propose two information theoretic similarity measures that allow to incorporate tissue class information in non-rigid image registration. The first measure assumes that tissue class probabilities have been assigned to each of the images to be registered by prior segmentation of both of them. One image is then non-rigidly deformed to match the other such that the fuzzy overlap of corresponding voxel object labels becomes similar to the ideal case whereby the tissue probability maps of both images are identical. Image similarity is assessed during registration by the divergence between the ideal and actual joint class probability distributions of both images. A second registration measure is proposed that applies in case a segmentation is available for only one of the images, for instance an atlas image that is to be matched to a study image to guide the segmentation thereof. Intensities in one image are matched to the fuzzy class labels in the other image by minimizing the conditional entropy of the intensities in the first image given the class labels in the second image. We derive analytic expressions for the gradient of each measure with respect to individual voxel displacements to derive a force field that drives the registration process, which is regularized by a viscous fluid model. The performance of the class-based measures is evaluated in the context of non-rigid inter-subject registration and atlas-based segmentation of MR brain images and compared with maximization of mutual information using only intensity information. Our results demonstrate that incorporation of class information in the registration measure significantly improves the overlap between corresponding tissue classes after non-rigid matching. The methods proposed here open new perspectives for integrating segmentation and registration in a single process, whereby the output of one is used to guide the other.
21 CFR 886.5918 - Rigid gas permeable contact lens care products.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...
Barriers to cooperation aid ideological rigidity and threaten societal collapse.
Jusup, Marko; Matsuo, Tadasu; Iwasa, Yoh
2014-05-01
Understanding the factors that promote, disrupt, or shape the nature of cooperation is one of the main tasks of evolutionary biology. Here, we focus on attitudes and beliefs supportive of in-group favoritism and strict adherence to moral consensus, collectively known as ideological rigidity, that have been linked with both ends of the political spectrum. The presence among the political right and the left is likely to make ideological rigidity a major determinant of the political discourse with an important social function. To better understand this function, we equip the indirect reciprocity framework--widely used to explain evaluation-mediated social cooperation--with multiple stylized value systems, each corresponding to the different degree of ideological rigidity. By running game theoretical simulations, we observe the competitive evolution of these systems, map conditions that lead to more ideologically rigid societies, and identify potentially disastrous outcomes. In particular, we uncover that barriers to cooperation aid ideological rigidity. The society may even polarize to the extent where social parasites overrun the population and cause the complete collapse of the social structure. These results have implications for lawmakers globally, warning against restrictive or protectionist policies.
Structural Rigidity of Paranemic (PX) and Juxtapose (JX) DNA Nanostructures
Santosh, Mogurampelly; 10.1016/j.bpj.2011.08.007
2011-01-01
Crossover motifs are integral components for designing DNA based nanostructures and nanomechanical devices due to their enhanced rigidity compared to the normal B-DNA. Although the structural rigidity of the double helix B-DNA has been investigated extensively using both experimental and theoretical tools, to date there is no quantitative information about structural rigidity and the mechanical strength of parallel crossover DNA motifs. We have used fully atomistic molecular dynamics simulations in explicit solvent to get the force-extension curve of parallel DNA nanostructures to characterize their mechanical rigidity. In the presence of mono-valent Na+ ions, we find that the stretch modulus (\\gamma_1) of the paranemic crossover (PX) and its topo-isomer JX DNA structure is significantly higher (~ 30%) compared to normal B-DNA of the same sequence and length. However, this is in contrast to the original expectation that these motifs are almost twice rigid compared to the double-stranded B-DNA. When the DNA mo...
Unified Creep Plasticity Damage (UCPD) Model for Rigid Polyurethane Foams.
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.
Maguinness, Corrina; Newell, Fiona N
2015-04-01
There is growing evidence to suggest that facial motion is an important cue for face recognition. However, it is poorly understood whether motion is integrated with facial form information or whether it provides an independent cue to identity. To provide further insight into this issue, we compared the effect of motion on face perception in two developmental prosopagnosics and age-matched controls. Participants first learned faces presented dynamically (video), or in a sequence of static images, in which rigid (viewpoint) or non-rigid (expression) changes occurred. Immediately following learning, participants were required to match a static face image to the learned face. Test face images varied by viewpoint (Experiment 1) or expression (Experiment 2) and were learned or novel face images. We found similar performance across prosopagnosics and controls in matching facial identity across changes in viewpoint when the learned face was shown moving in a rigid manner. However, non-rigid motion interfered with face matching across changes in expression in both individuals with prosopagnosia compared to the performance of control participants. In contrast, non-rigid motion did not differentially affect the matching of facial expressions across changes in identity for either prosopagnosics (Experiment 3). Our results suggest that whilst the processing of rigid motion information of a face may be preserved in developmental prosopagnosia, non-rigid motion can specifically interfere with the representation of structural face information. Taken together, these results suggest that both form and motion cues are important in face perception and that these cues are likely integrated in the representation of facial identity.
Rigid motion correction of dual opposed planar projections in single photon imaging
Angelis, G. I.; Ryder, W. J.; Gillam, J. E.; Boisson, F.; Kyme, A. Z.; Fulton, R. R.; Meikle, S. R.; Kench, P. L.
2017-05-01
Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomography problem, except that we wish to estimate the 2D planar projections rather than the 3D volume, where the angular sampling in all three axes depends on the rotational motion of the animal. In this study, we hypothesise that the motion corrected planar projections estimated by reconstructing an estimate of the 3D volume using an iterative motion compensating reconstruction algorithm and integrating it along the projection path, will closely match the true, motion-less, planar distribution regardless of the object motion. We tested this hypothesis for the case of rigid motion using Monte-Carlo simulations and experimental phantom data based on a dual opposed detector system, where object motion was modelled with 6 degrees of freedom. In addition, we investigated the quantitative accuracy of the regional activity extracted from the geometric mean of opposing motion corrected planar projections. Results showed that it is feasible to estimate qualitatively accurate motion-corrected projections for a wide range of motions around all 3 axes. Errors in the geometric mean estimates of regional activity were relatively small and within 10% of expected true values. In addition, quantitative regional errors were dependent on the observed motion, as well as on the surrounding activity of overlapping organs. We conclude that both qualitatively and quantitatively accurate motion-free projections of the tracer distribution in a rigidly moving object can be estimated from dual opposed detectors using a correction approach within an iterative reconstruction framework and we expect this approach can be extended to the case of non-rigid motion.
Flexible model and spectrum of non-rigid motion in LMF4 fluorides
Baranov, L. Ya.; Boldyrev, A. I.
A flexible model is used to simulate the spectrum of the non-rigid motion in the LiBF4 molecule. It is shown that there are many states having energies below the barrier of rearrangement which can be regarded as anharmonic bending vibrations. A one-well representation of the potential energy surface appears to be a fairly good approximation for describing this part of the spectrum. The tunnelling splittings at these levels are extremely small. At energies above the barrier the level pattern changes radically and highly excited states should be regarded as intramolecular hindered rotation. Differences between the spectra of LMH4 hydrides and LMF4 fluorides are discussed.
Chabab, M; Lahbas, A; Oulne, M
2016-01-01
In this paper, we present a theoretical study of a conjonction of $\\gamma$-rigid and $\\gamma$-stable collective motions in critical point symmetries of the phase transitions from spherical to deformed shapes of nuclei using exactly separable version of the Bohr Hamiltonian with deformation-dependent mass term. The deformation-dependent mass is applied simultaneously to $\\gamma$-rigid and $\\gamma$-stable parts of this famous collective Hamiltonian. Moreover, the $\\beta$ part of the problem is described by means of Davidson potential, while the $\\gamma$-angular part corresponding to axially symmetric shapes is treated by a Harmonic Osillator potential. The energy eigenvalues and normalized eigenfunctions of the problem are obtained in compact forms by making use of the asymptotic iteration method. The combined effect of the deformation-dependent mass and rigidity as well as harmonic oscillator stiffness parameters on the energy spectrum and wave functions is duly investigated. Also, the electric quadrupole tran...
Friction effects on lateral loading behavior of rigid piles
Zania, Varvara; Hededal, Ole
2012-01-01
The adequacy of the p -y curves used in the current practice for the design of rigid pile foundations with large diameter, like in the case of monopile foundations of offshore wind turbines, has been widely questioned. The current study aims at analyzing the lateral behavior of rigid piles, while...... taking into account the shear frictional resistance along the pile. For this purpose efficient three dimensional finite element models of different diameter have been developed. The increase of the side friction and of the diameter of the pile is shown to alter the failure pattern and increase...... the lateral capacity of the pile. The obtained p - y curves demonstrate the importance of the aforementioned parameters in the design of rigid piles, as the reduction of friction along the interface reduces not only the ultimate load but also the stiffness of the soil-pile response. Read More: http...
A concise introduction to mechanics of rigid bodies multidisciplinary engineering
Huang, L
2017-01-01
This updated second edition broadens the explanation of rotational kinematics and dynamics — the most important aspect of rigid body motion in three-dimensional space and a topic of much greater complexity than linear motion. It expands treatment of vector and matrix, and includes quaternion operations to describe and analyze rigid body motion which are found in robot control, trajectory planning, 3D vision system calibration, and hand-eye coordination of robots in assembly work, etc. It features updated treatments of concepts in all chapters and case studies. The textbook retains its comprehensiveness in coverage and compactness in size, which make it easily accessible to the readers from multidisciplinary areas who want to grasp the key concepts of rigid body mechanics which are usually scattered in multiple volumes of traditional textbooks. Theoretical concepts are explained through examples taken from across engineering disciplines and links to applications and more advanced courses (e.g. industrial rob...
WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION
YU Ming; XU Qiang
2006-01-01
Water-blown polyurethane rigid foams are getting more and more attention, because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction. However, the polyurethane rigid foams blown by water have serious defects, i.e. friability and resulting lower adhesion strength. Thus, the purpose of this study is to resolve the problems by chemical plastication. The maleate was added to polyol-premix containing water or to polyisocyanate,with both of which maleate does not react. To prove the reaction when polyol-premix and polyisocyanate were mixed, the model composite was synthesized and analyzed by IR, NMR and ESI (MS). Furthermore, a series of water-blown polyurethane rigid foams added different amount maleate were successfully prepared. By testing impact strength and adhesion strength of the foams, the actual effect of adding maleate was obtained.
Matrix rigidity optimizes the polarization of stem cells
Zemel, Assaf; Rehfeldt, Florian; Brown, Andre; Discher, Dennis; Safran, Samuel
2009-03-01
We present a theoretical model and experiments to explain the non-monotonic dependence of stress-fiber polarization in stem cells on matrix rigidity. The theory generalizes the treatment of elastic inclusions to ``living'' inclusions (cells) whose active polarizability, unlike non-living matter, depends on the feedback of cellular forces that develop in response to matrix stresses. We demonstrate experimentally that the stress fibers in adult mesenchymal stem cells, generally orient parallel to the long axis of the cells, with an anisotropy that depends non-monotonically on substrate stiffness. Consistent with these experiments, our theory predicts that the magnitude of the cellular force increases monotonically with the matrix rigidity while the polarization anisotropy shows a maximum that depends on the cell shape and the elastic modulus of the medium. These findings offer a mechanical correlate for the observation that stem cell differentiation optimizes in a range of matrix rigidities that depends on the tissue type.
Rigidity of transmembrane proteins determines their cluster shape
Jafarinia, Hamidreza; Jalali, Mir Abbas
2015-01-01
Protein aggregation in cell membrane is vital for majority of biological functions. Recent experimental results suggest that transmembrane domains of proteins such as $\\alpha$-helices and $\\beta$-sheets have different structural rigidity. We use molecular dynamics simulation of a coarse-grained model of protein-embedded lipid membranes to investigate the mechanisms of protein clustering. For a variety of protein concentrations, our simulations in thermal equilibrium conditions reveal that the structural rigidity of transmembrane domains dramatically affects interactions and changes the shape of the cluster. We have observed stable large aggregates even in the absence of hydrophobic mismatch which has been previously proposed as the mechanism of protein aggregation. According to our results, semi-flexible proteins aggregate to form two-dimensional clusters while rigid proteins, by contrast, form one-dimensional string-like structures. By assuming two probable scenarios for the formation of a two-dimensional tr...
A fast impulsive contact suite for rigid body simulation.
Schmidl, Harald; Milenkovic, Victor J
2004-01-01
A suite of algorithms is presented for contact resolution in rigid body simulation under the Coulomb friction model: Given a set of rigid bodies with many contacts among them, resolve dynamic contacts (collisions) and static (persistent) contacts. The suite consists of four algorithms: 1) partial sequential collision resolution, 2) final resolution of collisions through the solution of a single convex QP (positive semidefinite quadratic program), 3) resolution of static contacts through the solution of a single convex QP, 4) freezing of "stationary" bodies. This suite can generate realistic-looking results for simple examples yet, for the first time, can also tractably resolve contacts for a simulation as large as 1,000 cubes in an "hourglass." Freezing speeds up this simulation by more than 25 times. Thanks to excellent commercial QP technology, the contact resolution suite is simple to implement and can be "plugged into" any simulation algorithm to provide fast and realistic-looking animations of rigid bodies.
Development of probabilistic rigid pavement design methodologies for military airfields
Witczak, M. W.; Uzan, J.; Johnson, M.
1983-12-01
The current Corps of Engineers design procedures for rigid airfield pavements is based on the Westergaard free edge stress slab theory, and a proposed procedure is based on the multilayer elastic theory. These two design procedures have been expanded to airfield pavement designs expressed in probabilistic and reliability terms. Further developments were required in these procedures to make the analysis more practicable. Two major investigations were conducted: (1) Evaluation and use of the composite modulus of elasticity for layers beneath the rigid pavement, and (2) Evaluation of the maximum tensile stress at the bottom of the slab for different aircraft types. Derivations obtained from the investigation of the composite modulus and maximum tensile stress are reported and are included in computer programs for probabilistic/reliability analysis of rigid pavements. The approximate closed form (Taylor series expansion) is utilized. Example runs of the computer program are presented.
Clustering objects from multiple collections
Hollink, V.; van Someren, M.; de Boer, V.
2009-01-01
Clustering methods cluster objects on the basis of a similarity measure between the objects. In clustering tasks where the objects come from more than one collection often part of the similarity results from features that are related to the collections rather than features that are relevant for the
Clustering Objects from Multiple Collections
Hollink, V.; Someren, M. van; Boer, V. de
2009-01-01
Clustering methods cluster objects on the basis of a similarity measure between the objects. In clustering tasks where the objects come from more than one collection often part of the similarity results from features that are related to the collections rather than features that are relevant for the
Clustering objects from multiple collections
Hollink, V.; van Someren, M.; de Boer, V.
2009-01-01
Clustering methods cluster objects on the basis of a similarity measure between the objects. In clustering tasks where the objects come from more than one collection often part of the similarity results from features that are related to the collections rather than features that are relevant for the
A Model for Concurrent Objects
Sørensen, Morten U.
1996-01-01
We present a model for concurrent objects where obejcts interact by taking part in common events that are closely matched to form call-response pairs, resulting in resulting in rendez-vous like communications. Objects are built from primitive objects by parallel composition, encapsulation and hid...
Rigid Polyurethane Foam (RPF) Technology for Countermines (Sea) Program Phase II
WOODFIN,RONALD L.; FAUCETT,DAVID L.; HANCE,BRADLEY G.; LATHAM,AMY E.; SCHMIDT,C.O.
1999-10-01
This Phase II report documents the results of one subtask initiated under the joint Department of Energy (DOE)/Department of Defense (DoD) Memorandum of Understanding (MOU) for Countermine Warfare. The development of Rigid Polyurethane Foams for neutralization of mines and barriers in amphibious assault was the objective of the tasking. This phase of the program concentrated on formation of RPF in water, explosive mine simulations, and development of foam and fabric pontoons. Field experimentation was done primarily at the Energetic Materials Research and Testing Center (EMRTC) of the New Mexico Institute of Mining and Technology, Socorro, NM between February 1996 and September 1998.
Non-Rigid Medical Image Registration with Joint Histogram Estimation Based on Mutual Information
LU Xuesong; ZHANG Su; SU He; CHEN Yazhu
2007-01-01
A mutual information-based non-rigid medical image registration algorithm is presented. An approximate function of Harming windowed sinc is used as kernel function of partial volume (PV)interpolation to estimate the joint histogram, which is the key to calculating the mutual information. And a new method is proposed to compute the gradient of mutual information with respect to themodel parameters. The transformation of object is modeled by a free-form deformation (FFD) based on B-splines. The experiments on 3D synthetic and real image data show that the algorithm can con-verge at the global optimum and restrain the emergency of local extreme.
Nelson, P. A.; Jansen, A. N.
2006-11-28
We conducted a design study to compare the manufacturing costs at a level of 100,000 hybrid vehicle batteries per year for flexible package (Flex) cells and for rigid aluminum container (Rigid) cells. Initially, the Rigid cells were considered to have welded closures and to be deep-drawn containers of about the same shape as the Flex cells. As the study progressed, the method of fabricating and sealing the Rigid cells was expanded to include lower cost options including double seaming and other mechanically fastened closures with polymer sealants. Both types of batteries were designed with positive electrodes containing Li(Ni{sub 1/3}Co{sub 1/3}Mn{sub 1/3})O{sub 2} and graphite negative electrodes. The use of a different combination of lithium-ion electrodes would have little effect on the difference in costs for the two types of cells. We found that 20-Ah cells could be designed with excellent performance and heat rejection capabilities for either type of cell. Many parts in the design of the Flex cells are identical or nearly identical to those of the Rigid Cell, so for these features there would be no difference in the cost of manufacturing the two types of batteries. We judged the performance, size and weight of the batteries to be sufficiently similar that the batteries would have the same value for their application. Some of the design features of the Flex cells were markedly different than those of the deep-drawn and welded Rigid cells and would result in significant cost savings. Fabrication and processing steps for which the Flex cells appear to have a cost advantage over these Rigid cells are (1) container fabrication and sealing, (2) terminal fabrication and sealing, and (3) intercell connections. The costs of providing cooling channels adjacent to the cells and for module and battery hardware appear to favor Rigid cell batteries slightly. Overall, Flex cell batteries appear to have an advantage of about $1.20-$3.70 per cell for a 25-kW Battery of 20
Perceived rigidity in motion-in-depth increases with contour perspective.
Vienne, Cyril; Blondé, Laurent; Mamassian, Pascal
2014-01-01
When observers are asked to match the depth of an object according to its height, they often report systematic errors depending on viewing distance. Systematic biases can also arise while vergence distances are induced by binocular disparities. Observers of stereoscopic images tend to overestimate the depth of objects displayed in front of the screen, while the depth of objects displayed behind the screen plane is underestimated. This phenomenon creates a serious problem in that veridicality in depth perception appears distorted when one attempts to render the metrics of a captured 3-D world. These distortions could also subsist with structure-from-motion information and during motion-in-depth. Observers judged the circularity of transparent rotating cylinders that were either static or moving in depth. Crossed results show that participants could precisely retrieve the best modulation between presented depth and width. As this effect could be amplified with stimuli containing stronger perspective cues (ie contour perspective), participants judged the rigidity of spinning cubes, moving along the line of sight, which were either edges-defined or defined by randomly textured surfaces (dots). The results showed that, although depth constancy was not improved by contour perspective, perceived rigidity was increased by perspective when the best scaling estimate was displayed. This finding suggests that appropriate binocular disparity information in combination to monocular signal is necessary for stereoscopic depth perception.
Topology-Preserving Rigid Transformation of 2D Digital Images.
Ngo, Phuc; Passat, Nicolas; Kenmochi, Yukiko; Talbot, Hugues
2014-02-01
We provide conditions under which 2D digital images preserve their topological properties under rigid transformations. We consider the two most common digital topology models, namely dual adjacency and well-composedness. This paper leads to the proposal of optimal preprocessing strategies that ensure the topological invariance of images under arbitrary rigid transformations. These results and methods are proved to be valid for various kinds of images (binary, gray-level, label), thus providing generic and efficient tools, which can be used in particular in the context of image registration and warping.
Full Non-Rigid Group and Symmetry of Dimethyltrichlorophosphorus
ASHRAFI; AliReza
2005-01-01
In this work, a simple method is described, by means of which it is possible to calculate character tables for the symmetry group of molecules consisting of a number of NH3 groups attached to a rigid framework. The full non-rigid group (f-NRG) of dimethyltrichlorophosphorus with the symmetry group D3h was studied. It has been proven that it is a group of order 216 with 27 conjugacy classes and its character table computed. Finally, the Permutation-lnversion group of this molecule was calculated.
Kinematic Control of Free Rigid Bodies Using Dual Quaternions
Da-Peng Han; Qing Wei; Ze-Xiang Li
2008-01-01
This paper proposes a new type of control laws for free rigid bodies. The start point is the dual quaternion and its characteristics. The logarithm of a dual quaternion is defined, based on which kinematic control laws can be developed. Global exponential convergence is achieved using logarithmic feedback via a generalized proportional control law, and an appropriate Lyapunov function is constructed to prove the stability. Both the regulation and tracking problems are tackled. Omnidirectional control is discussed as a case study. As the control laws can handle the intercounection between the rotation and translation of a rigid body, they axe shown to be more applicable than the conventional method.
Buffers affect the bending rigidity of model lipid membranes.
Bouvrais, Hélène; Duelund, Lars; Ipsen, John H
2014-01-14
In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules.
Rigid 4D N=2 supersymmetric backgrounds and actions
Butter, Daniel; Lodato, Ivano
2015-01-01
We classify all N=2 rigid supersymmetric backgrounds in four dimensions with both Lorentzian and Euclidean signature that preserve eight real supercharges, up to discrete identifications. Among the backgrounds we find specific warpings of S^3 x R and AdS_3 x R, AdS_2 x S^2 and H^2 x S^2 with generic radii, and some more exotic geometries. We provide the generic two-derivative rigid vector and hypermultiplet actions and analyze the conditions imposed on the special Kahler and hyperkahler target spaces.
Shear-induced rigidity in spider silk glands
Koski, Kristie J.; McKiernan, Keri; Akhenblit, Paul; Yarger, Jeffery L.
2012-09-01
We measure the elastic stiffnesses of the concentrated viscous protein solution of the dehydrated Nephila clavipes major ampullate gland with Brillouin light scattering. The glandular material shows no rigidity but possesses a tensile stiffness similar to that of spider silk. We show, however, that with application of a simple static shear, the mechanical properties of the spider gland protein mixture can be altered irreversibly, lowering symmetry and enabling shear waves to be supported, thus, giving rise to rigidity and yielding elastic properties similar to those of the naturally spun (i.e., dynamically sheared) silk.
[Hygienic assessment of biologically rigid linear alkylbenzene sulfonates].
Bocharov, V V; Ryzhkova, O A
2010-01-01
It has been found that there are both biologically rigid and biologically soft homologues in the homologous series of linear alkylbenzene sulfonates (LABS). It is shown that absorption of LABS molecules from aqueous to activated sludge phase may serve as a determinant that should be used to refer a homologue to as rigid or soft surfactants. The biodegradability, detergency, and toxicity of LABS were ascertained to be related to the size of molecular alkyl molecular substitute. It has established that the fractional compositions of linear alkobenzenes should be changed for the synthesis of LABS that have the maximum detergency, a high biodegradability rate, and a low toxicity.
Rigidity of unilateral external fixators - A biomechanical study
P.T.P.W. Burgers (Paul); M.P.J.M. Riel (Marcel); L.M.M. Vogels (Lucas); R.W. Stam (Ronald); P. Patka (Peter); E.M.M. van Lieshout (Esther)
2011-01-01
textabstractIntroduction: External fixation is the primary choice of temporary fracture stabilisation for specific polytrauma patients. Adequate initial fracture healing requires sufficient stability at the fracture site. The purpose of this study was to compare the rigidity of the Dynafix DFS®Stand
Kinematic approach in the impact problem of rigid bodies
Sinopoli, A. (I.U.A.V., Venezia (Italy))
1989-11-01
The aim of this work is to analyze, by means of a kinematic approach, the problem of the impact between rigid bodies, when the surfaces involved in the impulsive phenomenon are of finite extent. The formulation here adopted permits to use the Gauss variational principle of least compulsion and to formulate the dynamic evolution of the system, after an impact, as a minimization problem. In this case, among all the possible subsequent motions, the real one is that which minimizes the kinetic energy connected to the sudden velocities variations. Interesting results are obtained in the case of the impact between a rigid column (either monolithic or made of several blocks) and a rigid ground. In particular, it can be shown that if previous motion of a rigid block is a rotation around its base corner edge, the motion after the impact is either a rototranslation or merely a translation, depending on the dimensional ratio. In any case, the subsequent motion is characterized by a component of sliding, so that the impact plays the role of filter between the possible degrees of freedom of the system and, at the same time, determines a possible coupling between rotation and translation. This conclusion is a novelty with respect to the results obtained in other papers (4-6), where a classical approach for the impact has been adopted.
Bending rigidity of type I collagen homotrimer fibrils
Han, Sejin; Leikin, Sergey; Losert, Wolfgang
2009-03-01
Normal type I collagen is an α1(I)2α2(I) heterotrimeric triple helix, but α1(I)3 homotrimers are also found in fetal tissues and various pathological conditions, e.g., causing bone fragility and reducing tendon tensile strength. It remains unclear whether homotrimers alter mechanical properties of individual fibrils or affect tissues by altering their organization at a higher level. To address this question, we investigated how homotrimers affect fibril bending rigidity. Homotrimer fibrils have been shown to be more loosely packed so that we expected them to be more susceptible to bending. However, homotrimer fibrils were more rigid despite being thinner and more hydrated. To quantify fibril rigidity, we analyzed their shape by Fourier decomposition, determined the correlation function for the direction along each fibril, and calculated the distribution of local fibril curvature. The estimated persistence length of homotrimer fibrils was 3 ˜ 10 times longer than for heterotrimer fibrils, indicating much higher bending rigidity of homotrimer fibrils.
Euler-Poincare Reduction of Externall Forced Rigid Body Motion
Wisniewski, Rafal; Kulczycki, P.
2004-01-01
. Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....
Euler-Poincaré Reduction of a Rigid Body Motion
Wisniewski, Rafal; Kulczycki, P.
2004-01-01
. Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincaré reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modelling, estimation and control of mechanical systems......-known Euler-Poincaré reduction to a rigid body motion with forcing....
Euler-Poincare Reduction of a Rigid Body Motion
Wisniewski, Rafal; Kulczycki, P.
2005-01-01
. Assuming that the system possesses symmetry and the configuration manifold corresponds to a Lie group, the Euler-Poincare reduction breaks up the motion into separate equations of dynamics and kinematics. This becomes of particular interest for modeling, estimation and control of mechanical systems......-known Euler-Poincare reduction to a rigid body motion with forcing....
Centrifuge modelling of rigid piles in soft clay
Klinkvort, R.T.; Poder, M.; Truong, P.
2016-01-01
of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...
Review of Intrathecal Baclofen Therapy for Spastic and Rigidity Disorders
Obringer, S. John; Coffey, Kenneth M.
2002-01-01
Intrathecal baclofen therapy, a treatment for cerebral palsy and other spastic and rigidity disorders, is showing promise as an effective intervention. This article synthesizes both the medical and rehabilitation conceptual literature to update educators and related service providers as to the efficacy of this intervention. Implications for…
Rigidity result on conjugacies of families of diffeomorphisms
李伟固; 章梅荣
1997-01-01
Embedding flows are used to obtain a rigidity result on strongly topological conjugacy of families of diffeomorphisms,i.e.families of C4(2≤r≤∞) diffeomorphisms,the strongly topologically conjugating homeomor-phisms near degenerate saddle-nodes will be differentiable on center manifolds of the saddle-nodes.
Rigid Biobased Building Blocks: Current Developments and Outlook
Es, van D.S.
2013-01-01
In this perspectives paper we will look at the state-of-the-art in rigid renewable building blocks for biobased materials, with a focus on two types of carbohydrate-based difunctional monomers, i.e.,isohexides and furan-2,5-dicarboxylic acid (FDCA).
The rigid-flexible nonlinear robotic manipulator: Modeling and control
Fenili, André; Balthazar, José Manoel
2011-05-01
The State-Dependent Riccati Equation (SDRE) control of a nonlinear rigid-flexible two link robotic manipulator is investigated. Different cases are considered assuming small deviations and large deviations from the desired final states. The nonlinear governing equations of motion are coupled, providing considerable excitation of all the nonlinear terms. The results present satisfactory final states but also undesirable overshoot.
Substructural Identification of Flexural Rigidity for Beam-Like Structures
Ki-Young Koo
2015-01-01
Full Text Available This study proposes a novel substructural identification method based on the Bernoulli-Euler beam theory with a single variable optimization scheme to estimate the flexural rigidity of a beam-like structure such as a bridge deck, which is one of the major structural integrity indices of a structure. In ordinary bridges, the boundary condition of a superstructure can be significantly altered by aging and environmental variations, and the actual boundary conditions are generally unknown or difficult to be estimated correctly. To efficiently bypass the problems related to boundary conditions, a substructural identification method is proposed to evaluate the flexural rigidity regardless of the actual boundary conditions by isolating an identification region within the internal substructure. The proposed method is very simple and effective as it utilizes the single variable optimization based on the transfer function formulated utilizing Bernoulli Euler beam theory for the inverse analysis to obtain the flexural rigidity. This novel method is also rigorously investigated by applying it for estimating the flexural rigidity of a simply supported beam model with different boundary conditions, a concrete plate-girder bridge model with different length of an internal substructure, a cantilever-type wind turbine tower structure with different type of excitation, and a steel box-girder bridge model with internal structural damages.
Calculating ensemble averaged descriptions of protein rigidity without sampling.
Luis C González
Full Text Available Previous works have demonstrated that protein rigidity is related to thermodynamic stability, especially under conditions that favor formation of native structure. Mechanical network rigidity properties of a single conformation are efficiently calculated using the integer body-bar Pebble Game (PG algorithm. However, thermodynamic properties require averaging over many samples from the ensemble of accessible conformations to accurately account for fluctuations in network topology. We have developed a mean field Virtual Pebble Game (VPG that represents the ensemble of networks by a single effective network. That is, all possible number of distance constraints (or bars that can form between a pair of rigid bodies is replaced by the average number. The resulting effective network is viewed as having weighted edges, where the weight of an edge quantifies its capacity to absorb degrees of freedom. The VPG is interpreted as a flow problem on this effective network, which eliminates the need to sample. Across a nonredundant dataset of 272 protein structures, we apply the VPG to proteins for the first time. Our results show numerically and visually that the rigidity characterizations of the VPG accurately reflect the ensemble averaged [Formula: see text] properties. This result positions the VPG as an efficient alternative to understand the mechanical role that chemical interactions play in maintaining protein stability.
[Lens prescription for rigid contact lenses in keratoconus].
Manea, Georgiana
2012-01-01
Rigid Gas-Permeable contact lenses is a less risky option for improving the quality of vision in corneal ectasias such as keratoconus. They reshape the corneal surface (flattens the cornea) so that in most cases, with a proper lens, the patient can reach a visual acuity of 20/20.
Design of the new rigid endoscope distortion measurement system
Zhai, Xiaohao; Liu, Xiaohua; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin; Wang, Yakun; Li, Yonghui; Zhou, Peng
2015-08-01
Endoscopic imaging quality affects industrial safety and medical security. Rigid endoscope distortion is of great signification as one of optical parameters to evaluate the imaging quality. This paper introduces a new method of rigid endoscope distortion measurement, which is different from the common methods with low accuracy and fussy operation. It contains a Liquid Crystal Display (LCD) to display the target, a CCD to obtain the images with distortion, and a computer to process the images. The LCD is employed instead of common white screen. The autonomous control system of LCD makes it showing the test target designed for distortion, and its parameter is known. LCD control system can change the test target to satisfy the different demand for accuracy, which avoids replacing target frequently. The test system also contains a CCD to acquire images in the exit pupil position of rigid endoscope. Rigid endoscope distortion is regarded as centrosymmetric, and the MATLAB software automatically measures it by processing the images from CCD. The MATLAB software compares target images with that without distortion on LCD and calculates the results. Relative distortion is obtained at different field of view (FOV) radius. The computer plots the curve of relative distortion, abscissa means radius of FOV, ordinate means relative distortion. The industry standard shows that, the distortion at 70% field of view is pointed on the curve, which can be taken as an evaluation standard. This new measuring method achieves advantages of high precision, high degree of intelligence, excellent repeatability and gets calculation results quickly.
Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior
Sagis, L.M.C.; Linden, van der E.
2001-01-01
In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly
Patient satisfaction related to rigid external distraction osteogenesis
van Eggermont, Bas; Jansma, J.; Bierman, M. W. J.; Stegenga, B.
2007-01-01
The aim of this study was to evaluate satisfaction with treatment among cleft lip and palate patients who underwent maxillary advancement using a rigid external distraction (RED) device. Nine patients (four boys, five girls), mean age 17.7 years (SD 4.0), were included in the study. Outcome measures
Transport coefficients for rigid spherically symmetric polymers or aggregates
Strating, P.; Wiegel, F.W.
1994-01-01
In this paper we investigate the transport properties for rigid spherically symmetric macromolecules, having a segment density distribution falling off as r- lambda . We calculate the rotational and translational diffusion coefficient for a spherically symmetric polymer and the shear viscosity for a
Non-rigid Reconstruction of Casting Process with Temperature Feature
Lin, Jinhua; Wang, Yanjie; Li, Xin; Wang, Ying; Wang, Lu
2017-09-01
Off-line reconstruction of rigid scene has made a great progress in the past decade. However, the on-line reconstruction of non-rigid scene is still a very challenging task. The casting process is a non-rigid reconstruction problem, it is a high-dynamic molding process lacking of geometric features. In order to reconstruct the casting process robustly, an on-line fusion strategy is proposed for dynamic reconstruction of casting process. Firstly, the geometric and flowing feature of casting are parameterized in manner of TSDF (truncated signed distance field) which is a volumetric block, parameterized casting guarantees real-time tracking and optimal deformation of casting process. Secondly, data structure of the volume grid is extended to have temperature value, the temperature interpolation function is build to generate the temperature of each voxel. This data structure allows for dynamic tracking of temperature of casting during deformation stages. Then, the sparse RGB features is extracted from casting scene to search correspondence between geometric representation and depth constraint. The extracted color data guarantees robust tracking of flowing motion of casting. Finally, the optimal deformation of the target space is transformed into a nonlinear regular variational optimization problem. This optimization step achieves smooth and optimal deformation of casting process. The experimental results show that the proposed method can reconstruct the casting process robustly and reduce drift in the process of non-rigid reconstruction of casting.
Rigidly connected magnetic lines: twisting and winding of magnetic lines
Prasad, G.
2017-10-01
The dynamical process of magnetic flux variation in a fluid's stream tube is described by constructing 1+1+ (2) decomposition of the gradient of fluid's 4-velocity. The necessary and sufficient conditions are obtained for a spacelike congruence to be a congruence of rigidly connected spacelike curves. The evolution of magnetic flux in a magnetic tube is explored under the assumptions that magnetic lines are rigidly connected and the chemical potential of the fluid is constant along a magnetic tube. The interplay between magnetic and stream tubes is demonstrated. It is shown that the growth of magnetic energy in a magnetic tube cannot exceed to that of a stream tube. It is found that the proper time variation of twist of magnetic lines is caused by gravitation inside a neutron star if magnetic lines are rigidly connected and charge neutrality condition holds. Helmholtz-like magnetic vorticity flux conservation in a magnetic tube constituted by rigidly connected geodetic magnetic lines is derived under the assumption that the charge neutrality condition holds. It is shown that the winding of frozen-in poloidal magnetic field due to differential rotation requires meridional circulation in an axisymmetric stationary hydromagnetic configuration.
"Mind the trap": mindfulness practice reduces cognitive rigidity.
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.
Vortex statistics for turbulence in a container with rigid boundaries
Clercx, H.J.H.; Nielsen, A.H.
2000-01-01
The evolution of vortex statistics for decaying two-dimensional turbulence in a square container with rigid no-slip walls is compared with a few available experimental results and with the scaling theory of two-dimensional turbulent decay as proposed by Carnevale et al. Power-law exponents...
Invariants of solvable rigid Lie algebras up to dimension 8
Campoamor-Stursberg, Rutwig [Depto Geometria y Topologia, Fac. CC Matematicas UCM, Madrid (Spain)]. E-mail: rutwig@nfssrv.mat.ucm.es
2002-08-02
The invariants of all complex solvable rigid Lie algebras up to dimension 8 are computed. Moreover we show, for rank 1 solvable algebras, some criteria to deduce the non-existence of nontrivial invariants or the existence of fundamental sets of invariants formed by rational functions of the Casimir invariants of the associated nilradical. (author)
Rigid-plastic seismic design of reinforced concrete structures
Costa, Joao Domingues; Bento, R.; Levtchitch, V.
2007-01-01
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...
Substrates with engineered step changes in rigidity induce traction force polarity and durotaxis.
Breckenridge, Mark T; Desai, Ravi A; Yang, Michael T; Fu, Jianping; Chen, Christopher S
2014-03-01
Rigidity sensing plays a fundamental role in multiple cell functions ranging from migration, to proliferation and differentiation(1-5). During migration, single cells have been reported to preferentially move toward more rigid regions of a substrate in a process termed durotaxis. Durotaxis could contribute to cell migration in wound healing and gastrulation, where local gradients in tissue rigidity have been described. Despite the potential importance of this phenomenon to physiology and disease, it remains unclear how rigidity guides these behaviors and the underlying cellular and molecular mechanisms. To investigate the functional role of subcellular distribution and dynamics of cellular traction forces during durotaxis, we developed a unique microfabrication strategy to generate elastomeric micropost arrays patterned with regions exhibiting two different rigidities juxtaposed next to each other. After initial cell attachment on the rigidity boundary of the micropost array, NIH 3T3 fibroblasts were observed to preferentially migrate toward the rigid region of the micropost array, indicative of durotaxis. Additionally, cells bridging two rigidities across the rigidity boundary on the micropost array developed stronger traction forces on the more rigid side of the substrate indistinguishable from forces generated by cells exclusively seeded on rigid regions of the micropost array. Together, our results highlighted the utility of step-rigidity micropost arrays to investigate the functional role of traction forces in rigidity sensing and durotaxis, suggesting that cells could sense substrate rigidity locally to induce an asymmetrical intracellular traction force distribution to contribute to durotaxis.
METHOD OF ACHIEVING ACCURACY OF THERMO-MECHANICAL TREATMENT OF LOW-RIGIDITY SHAFTS
Antoni Świć
2016-03-01
Full Text Available The paper presents a method combining the processes of straightening and thermal treatment. Technological processes with axial strain were considered, for the case of heated material and without its heating. The essence of the process in the case of heated material consisted in the fact that if under tension all longitudinal forces in the first approximation are uniform - the same strains are generated. The presented technological approach, aimed at reducing the curvature of axial-symmetrical parts, is acceptable as the process of rough, preliminary machining, in the case of shafts with the ratio L/D≤100 (L – shaft length, d – shaft diameter and without a tendency of strengthening. To improve the accuracy and stability of geometric form of low-rigidity parts, a method was developed that combines the processes of straightening and heat treatment. The method consists in that axial strain – tension, is applied to the shaft during heating, and during cooling the product is fixed in a fixture, the cooling rate of the shaft being several-fold greater than that of the fixture. A device is presented for the realisation of the method of controlling the process of plastic deformation of low-rigidity shafts. In the case of the presented device and the adopted calculation scheme, a method was developed that permits the determination of the length of shaft section and of the time of its cooling.
Malmsjö Malin
2011-07-01
Full Text Available Abstract Objectives Right ventricular heart rupture is a devastating complication associated with negative pressure wound therapy (NPWT in cardiac surgery. The use of a rigid barrier has been suggested to offer protection against this lethal complication, by preventing the heart from being drawn up and damaged by the sharp edges of the sternum. The aim of the present study was to investigate whether a rigid barrier protects the heart and lungs against injury during NPWT. Methods Sixteen pigs underwent median sternotomy followed by NPWT at -120 mmHg for 24 hours, in the absence (eight pigs or presence (eight pigs of a rigid plastic disc between the heart and the sternal edges. The macroscopic appearance of the heart and lungs was inspected after 12 and 24 hours of NPWT. Results After 24 hours of NPWT at -120 mmHg the area of epicardial petechial bleeding was 11.90 ± 1.10 cm2 when no protective disc was used, and 1.15 ± 0.19 cm2 when using the disc (p Conclusion Inserting a rigid barrier between the heart and the sternum edges offers protection against heart rupture and lung injury during NPWT.
Powell, Douglas; Muthumani, Anburaj; Xia, RuiPing
2016-01-01
Objective Quantify the effect of a continuous compared to discontinuous movement trajectory on parkinsonian rigidity and reflex responses to passive stretch and shortening. Methods Eighteen participants with Parkinson’s disease (PD) performed passive wrist flexion and extension movements through a 90° range of motion at 50 °/sec using continuous (CONT) and discontinuous (DISC) movement trajectories. Participants were tested in both the OFF-MED and ON-MED states. Rigidity was quantified by rigidity work score and slopes of the moment-angle plots during both flexion and extension. Reflex response was quantified by mean EMG amplitudes of forearm musculature. Results No differences were observed between CONT and DISC for rigidity (p = 0.18) or moment-angle plot slopes (Flexion: p = 0.97; Extension: p = 0.89). However, medication was associated with reductions in rigidity (p = 0.02) and increases in moment-angle plot slopes (Flexion: p = 0.03; Extension: p = 0.02). The CONT compared to DISC trajectory was associated with greater EMG amplitudes in the shortened muscles (p = 0.04) and smaller EMG ratios (p < 0.05) during flexion, and greater EMG amplitudes in the lengthened muscles (p = 0.02) during extension. Dopaminergic medication reduced EMG amplitudes in stretched muscles during extension (p < 0.05). Conclusions The nature of the movement trajectory (continuous vs. discontinuous) used during clinical assessment does not alter the presentation of rigidity in PD. Rigidity is reduced with the administration of dopaminergic medication, independent of movement trajectory. Significance These data suggest that the presentation of rigidity used in the determination of diagnosis, treatment and prognosis in PD will not be affected by the continuous nature of the movement trajectory used during clinical assessment.
Initial Development of an Electronic Testis Rigidity Tester
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.
Matrix rigidity regulates cancer cell growth and cellular phenotype.
Robert W Tilghman
Full Text Available 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.
Adobe Boxes: Locating Object Proposals Using Object Adobes.
Fang, Zhiwen; Cao, Zhiguo; Xiao, Yang; Zhu, Lei; Yuan, Junsong
2016-09-01
Despite the previous efforts of object proposals, the detection rates of the existing approaches are still not satisfactory enough. To address this, we propose Adobe Boxes to efficiently locate the potential objects with fewer proposals, in terms of searching the object adobes that are the salient object parts easy to be perceived. Because of the visual difference between the object and its surroundings, an object adobe obtained from the local region has a high probability to be a part of an object, which is capable of depicting the locative information of the proto-object. Our approach comprises of three main procedures. First, the coarse object proposals are acquired by employing randomly sampled windows. Then, based on local-contrast analysis, the object adobes are identified within the enlarged bounding boxes that correspond to the coarse proposals. The final object proposals are obtained by converging the bounding boxes to tightly surround the object adobes. Meanwhile, our object adobes can also refine the detection rate of most state-of-the-art methods as a refinement approach. The extensive experiments on four challenging datasets (PASCAL VOC2007, VOC2010, VOC2012, and ILSVRC2014) demonstrate that the detection rate of our approach generally outperforms the state-of-the-art methods, especially with relatively small number of proposals. The average time consumed on one image is about 48 ms, which nearly meets the real-time requirement.
Ditto, Thomas D.; Ritter, Joseph M.
2008-07-01
A new class of astronomical telescope with a primary objective grating (POG) has been studied as an alternative to mirrors. Nineteenth century POG telescopes suffered from low resolution and ambiguity of overlapping spectra as well as background noise. The present design uses a conventional secondary spectrograph to disambiguate all objects while enjoying a very wide instantaneous field-of-view, up to 40°. The POG competes with mirrors, in part, because diffraction gratings provide the very chromatic dispersion that mirrors defeat. The resulting telescope deals effectively with long-standing restrictions on multiple object spectrographs (MOS). The combination of a POG operating in the first-order, coupled to a spectrographic astronomical telescope, isolates spectra from all objects in the free spectral range of the primary. First disclosed as a concept in year 2002, a physical proof-of-principle is now reported. The miniature laboratory model used a 50 mm plane grating primary and was able to disambiguate between objects appearing at angular resolutions of 55 arcseconds and spectral spacings of 0.15 nm. Astronomical performance is a matter of increasing instrument size. A POG configured according to our specifications has no moving parts during observations and is extensible to any length that can be held flat to tolerances approaching float glass. The resulting telescope could record over one million spectra per night of objects in a line of right ascension. The novel MOS does not require pre-imaging to start acquisition of uncharted star fields. Problems are anticipated in calibration and integration time. We propose means to ameliorate them.
Free vibration of semi-rigid connected Reddy–Bickford piles embedded in elastic soil
Yusuf Yesilce; Hikmet H Catal
2008-12-01
The literature on free vibration analysis of Bernoulli–Euler and timoshenko piles embedded in elastic soil is plenty, but that of Reddy–Bickford piles partially embedded in elastic soil with/without axial force effect is fewer. The soil that the pile partially embedded in is idealized by Winkler model and is assumed to be two-layered. The pile part above the soil is called the ﬁrst region and the parts embedded in the soil are called the second and the third region, respectively. It is assumed that the behaviour of the material is linear-elastic, that axial force along the pile length to be constant and the upper end of the pile that is semi-rigid supported against rotation is modelled by an elastic spring. The governing differential equations of motion of the rectangular pile in free vibration are derived using Hamilton’s principle and Winkler hypothesis. The terms are found directly from the solutions of the differential equations that describe the deformations of the cross-section according to the high-order theory. The models have six degrees of freedom at the two ends, one transverse displacement and two rotations, and the end forces are a shear force and two end moments. Natural frequencies of the pile are calculated using transfer matrix and the secant method for non-trivial solution of linear homogeneous system of equations obtained due to values of axial forces acting on the pile, total and embedded lengths of the pile, the linear-elastic rotational restraining stiffness at the upper end of the pile and to the boundary conditions of the pile. Two different boundary conditions are considered in the study. For the ﬁrst boundary condition, the pile’s end at the ﬁrst region is semi-rigid connected and not restricted for horizontal displacement and the end at the third region is free and for the second boundary condition, the pile’s end at the ﬁrst region is semi-rigid connected and restricted for horizontal displacement and the end at the
PRESSURE AND PRESSURE GRADIENT IN AN AXISYMMETRIC RIGID VESSEL WITH STENOSIS
无
2006-01-01
Based on an improvement of the Karman-Pohlhausen's method, using nonlinear polynomial fitting and numerical integral, the axial distributions of pressure and its gradient in an axisymmetric rigid vessel with stenosis were obtained, and the distributions related to Reynolds number and the geometry of stenotic vessel were discussed. It shows that with the increasing of stenotic degree or Reynolds number, the fluctuation of pressure and its gradient in stenotic area is intense rapidly, and negative pressure occurs subsequently in the diverging part of stenotic area. Especially when the axial range of stenosis extends, the flow of blood in the diverging part will be more obviously changed.In higher Reynolds number or heavy stenosis, theoretical calculation is mainly in accordance with past experiments.
Synthesis of Transesterified Palm Olein-Based Polyol and Rigid Polyurethanes from this Polyol.
Arniza, Mohd Zan; Hoong, Seng Soi; Idris, Zainab; Yeong, Shoot Kian; Hassan, Hazimah Abu; Din, Ahmad Kushairi; Choo, Yuen May
Transesterification of palm olein with glycerol can increase the functionality by introducing additional hydroxyl groups to the triglyceride structure, an advantage compared to using palm olein directly as feedstock for producing palm-based polyol. The objective of this study was to synthesize transesterified palm olein-based polyol via a three-step reaction: (1) transesterification of palm olein, (2) epoxidation and (3) epoxide ring opening. Transesterification of palm olein yielded approximately 78 % monoglyceride and has an hydroxyl value of approximately 164 mg KOH g(-1). The effect of formic acid and hydrogen peroxide concentrations on the epoxidation reaction was studied. The relationships between epoxide ring-opening reaction time and residual oxirane oxygen content and hydroxyl value were monitored. The synthesized transesterified palm olein-based polyol has hydroxyl value between 300 and 330 mg KOH g(-1) and average molecular weight between 1,000 and 1,100 Da. On the basis of the hydroxyl value and average molecular weight of the polyol, the transesterified palm olein-based polyol is suitable for producing rigid polyurethane foam, which can be designed to exhibit desirable properties. Rigid polyurethane foams were synthesized by substituting a portion of petroleum-based polyol with the transesterified palm olein-based polyol. It was observed that by increasing the amount of transesterified palm olein-based polyol, the core density and compressive strength were reduced but at the same time the insulation properties of the rigid polyurethane foam were improved.
Floris H P van Velden
Full Text Available OBJECTIVES: Reusing baseline volumes of interest (VOI by applying non-rigid and to some extent (local rigid image registration showed good test-retest variability similar to delineating VOI on both scans individually. The aim of the present study was to compare response assessments and classifications based on various types of image registration with those based on (semi-automatic tumour delineation. METHODS: Baseline (n = 13, early (n = 12 and late (n = 9 response (after one and three cycles of treatment, respectively whole body [(18F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (PET/CT scans were acquired in subjects with advanced gastrointestinal malignancies. Lesions were identified for early and late response scans. VOI were drawn independently on all scans using an adaptive 50% threshold method (A50. In addition, various types of (non-rigid image registration were applied to PET and/or CT images, after which baseline VOI were projected onto response scans. Response was classified using PET Response Criteria in Solid Tumors for maximum standardized uptake value (SUV(max, average SUV (SUV(mean, peak SUV (SUV(peak, metabolically active tumour volume (MATV, total lesion glycolysis (TLG and the area under a cumulative SUV-volume histogram curve (AUC. RESULTS: Non-rigid PET-based registration and non-rigid CT-based registration followed by non-rigid PET-based registration (CTPET did not show differences in response classifications compared to A50 for SUV(max and SUV(peak, however, differences were observed for MATV, SUV(mean, TLG and AUC. For the latter, these registrations demonstrated a poorer performance for small lung lesions (<2.8 ml, whereas A50 showed a poorer performance when another area with high uptake was close to the target lesion. All methods were affected by lesions with very heterogeneous tracer uptake. CONCLUSIONS: Non-rigid PET- and CTPET-based image registrations may be used to classify response
Ahmad, Nasir Zaheer
2012-06-01
Rigid sigmoidoscopy is sometimes performed at first presentation in colorectal clinics. We assessed the feasibility of flexible sigmoidoscopy in similar situations by comparing it with rigid sigmoidoscopy as a first investigative tool.
Rigidity of complete noncompact bach-flat n-manifolds
Chu, Yawei; Feng, Pinghua
2012-11-01
Let (Mn,g) be a complete noncompact Bach-flat n-manifold with the positive Yamabe constant and constant scalar curvature. Assume that the L2-norm of the trace-free Riemannian curvature tensor R∘m is finite. In this paper, we prove that (Mn,g) is a constant curvature space if the L-norm of R∘m is sufficiently small. Moreover, we get a gap theorem for (Mn,g) with positive scalar curvature. This can be viewed as a generalization of our earlier results of 4-dimensional Bach-flat manifolds with constant scalar curvature R≥0 [Y.W. Chu, A rigidity theorem for complete noncompact Bach-flat manifolds, J. Geom. Phys. 61 (2011) 516-521]. Furthermore, when n>9, we derive a rigidity result for R<0.
Impedance of rigid bodies in one-dimensional elastic collisions
Santos, Janilo; Nelson, Osman Rosso
2012-01-01
In this work we study the problem of one-dimensional elastic collisions of billiard balls, considered as rigid bodies, in a framework very different from the classical one presented in text books. Implementing the notion of impedance matching as a way to understand eficiency of energy transmission in elastic collisions, we find a solution which frames the problem in terms of this conception. We show that the mass of the ball can be seen as a measure of its impedance and verify that the problem of maximum energy transfer in elastic collisions can be thought of as a problem of impedance matching between different media. This approach extends the concept of impedance, usually associated with oscillatory systems, to system of rigid bodies.
A symmetric splitting method for rigid body dynamics
E. Celledoni
2006-04-01
Full Text Available It has been known since the time of Jacobi that the solution to the free rigid body (FRB equations of motion is given in terms of a certain type of elliptic functions. Using the Arithmetic-Geometric mean algorithm, (1, these functions can be calculated efficiently and accurately. The overall approach yields a faster and more accurate numerical solution to the FRB equations compared to standard numerical ODE and symplectic solvers. In this paper we investigate the possibility of extending this approach to the case of rigid bodies subject to external forces. By using a splitting strategy similar to the one proposed in (14, we decompose the vector field of our problem in a FRB problem and another completely integrable vector field. We apply the method to the simulation of the heavy top.
Electrical conductivity of rigid polyurethane foam at high temperature
Johnson, R. T., Jr.
1982-08-01
The electrical conductivity of rigid polyurethane foam, used for electronic encapsulation, was measured during thermal decomposition to 3400 C. At higher temperatures the conductance continues to increase. With pressure loaded electrical leads, sample softening results in eventual contact between electrodes which produces electrical shorting. Air and nitrogen environments show no significant dependence of the conductivity on the atmosphere over the temperature range. The insulating characteristics of polyurethane foam below approx. 2700 C are similar to those for silicone based materials used for electronic case housings and are better than those for phenolics. At higher temperatures (greater than or equal to 2700 C) the phenolics appear to be better insulators to approx. 5000 C and the silicones to approx. 6000 C. It is concluded that the Sylgard 184/GMB encapsulant is a significantly better insulator at high temperature than the rigid polyurethane foam.
Tunable Thermoresponsiveness of Resilin via Coassembly with Rigid Biopolymers.
Whittaker, Jasmin L; Dutta, Naba K; Knott, Robert; McPhee, Gordon; Voelcker, Nicolas H; Elvin, Chris; Hill, Anita; Choudhury, Namita Roy
2015-08-18
The ability to tune the thermoresponsiveness of recombinant resilin protein, Rec1-resilin, through a facile coassembly system was investigated in this study. The effects of change in conformation and morphology with time and the responsive behavior of Rec1-resilin in solution were studied in response to the addition of a rigid model polypeptide (poly-l-proline) or a hydrophobic rigid protein (Bombyx mori silk fibroin). It was observed that by inducing more ordered conformations and increasing the hydrophobicity the lower critical solution temperature (LCST) of the system was tuned to lower values. Time and temperature were found to be critical parameters in controlling the coassembly behavior of Rec1-resilin in both the model polypeptide and more complex protein systems. Such unique properties are useful for a wide range of applications, including drug delivery and soft tissue engineering applications.
Rotating and rolling rigid bodies and the "hairy ball" theorem
Bormashenko, Edward; Kazachkov, Alexander
2017-06-01
Rotating and rolling rigid bodies exemplify a fascinating theorem of topology, jokingly called the "hairy ball" theorem, which demands that any continuous tangent vector field on the sphere has at least one point where the field is zero. We demonstrate via a gedanken experiment how drilling through a rotating ball, thereby converting it into a torus, leads to the elimination of zero-velocity points on the ball surface. Using the same reasoning, zero-velocity points can be removed from the surface of a drilled spinning top. We discuss the location of zero-velocity points on the surfaces of rigid bodies rolling with no slip and with slip. Observations made from different reference frames identify various zero-velocity points. Illustrative experiments visualizing zero-velocity points are presented.
A density-independent rigidity transition in biological tissues
Bi, Dapeng; Lopez, J. H.; Schwarz, J. M.; Manning, M. Lisa
2015-12-01
Cell migration is important in many biological processes, including embryonic development, cancer metastasis and wound healing. In these tissues, a cell’s motion is often strongly constrained by its neighbours, leading to glassy dynamics. Although self-propelled particle models exhibit a density-driven glass transition, this does not explain liquid-to-solid transitions in confluent tissues, where there are no gaps between cells and therefore the density is constant. Here we demonstrate the existence of a new type of rigidity transition that occurs in the well-studied vertex model for confluent tissue monolayers at constant density. We find that the onset of rigidity is governed by a model parameter that encodes single-cell properties such as cell-cell adhesion and cortical tension, providing an explanation for liquid-to-solid transitions in confluent tissues and making testable predictions about how these transitions differ from those in particulate matter.
One-DOF Superimposed Rigid Origami with Multiple States
Liu, Xiang; Gattas, Joseph M.; Chen, Yan
2016-11-01
Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of each individual pattern is preserved. This is enabled by the cross-crease vertex, a special configuration consisting of two pairs of collinear crease lines, which is proven here by means of a kinematic analysis to contain two independent 1-DOF rigid-foldable states. This enables many new origami-inspired engineering design possibilities, with two explored in depth: the compact folding of non-flat-foldable structures and sequent folding origami that can transform between multiple states without unfolding.
Early object relations into new objects.
Downey, T W
2001-01-01
. Pain deprived of meaning is buried as neurosis. As we see in John's story, experience that cannot be integrated at the time is locked away from whatever developmental progression has occurred. Intolerable affects and ideas require particular circumstances of object relation and verbalization such as are found in the context of psychoanalysis and arrived at through psychoanalytic interpretation. Or, as in John's case, they may give way only slowly and irregularly over long stretches of time, when subjected to life experiences in the company of new object relations. Broadly stated, the Freud-Dann paper helps us to appreciate that there are several pathways of protection and growth in the ego that involve the discovery or construction of new objects. Family-romance fantasies are a common manifestation of new-object phenomena. Transitional object phenomena are also related. For some individuals at a particular time or over a span of time, providing the right circumstances for the resumption of maturational and developmental growth is all it takes to make them whole. Changes in the adaptive ego are sufficient to alleviate the conflicts stemming from the neurotic ego. For others, depending upon the degree of their neurotic impairment, or for the same individual under other circumstances, therapeutic change in the deepest sense demands the relatively unconditional presence of the interactive and interpreting other. Children of the storm who come in for shelter and warmth may thrive, but they also require a means of getting at the storm in their core that has been internalized as part of the ego's survival mechanism. What can be extracted from the poignant story of the Bulldogs Bank children about current child-analytic technique? The psychoanalytic piano now may be more formally conceptualized as having white as well as black keys. Most analyses, adult and child, have been conducted as though the "black keys"--pressure to mastery through repetition and its subsequent
Oscillation of a rigid rod in the special relativity
Paiva, F M
2012-01-01
In the special relativity, a rigid rod slides upon itself, with one extremity oscillating harmonically. We discovered restrictions in the amplitude of the motion and in the length of the rod, essential to eliminate unphysical solutions. ------- Cxe la speciala relativeco, rigida stango movigxas sur si mem, kun unu fino oscilante harmonie. Ni malkovris limigajn kondicxojn pri la amplitudo de movado kaj pri la longo de stango, necesegaj por elimini ne-fizikajn solvojn.
Segmental rigidity and spinal myoclonus as a paraneoplastic syndrome.
Roobol, T H; Kazzaz, B. A.; Vecht, C. J.
1987-01-01
A 68 year old woman is described with persisting muscular rigidity of the left lower leg together with transient myoclonic jerking in the left quadriceps muscle. Six weeks after onset a small cell carcinoma of the lung became manifest. With radiotherapy and chemotherapy complete remission was achieved. Segmental muscular spasm improved at the same time. Necropsy revealed loss and degeneration of alpha-motor neuron cells at one side of the anterior horn of the lumbar enlargement. This case may...
One-DOF Superimposed Rigid Origami with Multiple States
Xiang Liu; Gattas, Joseph M.; Yan Chen
2016-01-01
Origami-inspired engineering design is increasingly used in the development of self-folding structures. The majority of existing self-folding structures either use a bespoke crease pattern to form a single structure, or a universal crease pattern capable of forming numerous structures with multiple folding steps. This paper presents a new approach whereby multiple distinct, rigid-foldable crease patterns are superimposed in the same sheet such that kinematic independence and 1-DOF mobility of...
Degenerations and limit Frobenius structures in rigid cohomology
Lauder, Alan G. B.
2011-01-01
We introduce a "limiting Frobenius structure" attached to any degeneration of projective varieties over a finite field of characteristic p which satisfies a p-adic lifting assumption. Our limiting Frobenius structure is shown to be effectively computable in an appropriate sense for a degeneration of projective hypersurfaces. We conjecture that the limiting Frobenius structure relates to the rigid cohomology of a semistable limit of the degeneration through an analogue of the Clemens-Schmidt e...
Anisotropy of torsional rigidity of sheet polymer composite materials
Startsev, O. V.; Kovalenko, A. A.; Nasonov, A. D.
1999-05-01
Wide application of polymer composite materials (PCM) in modern technology calls for detailed evaluation of their stress-strain properties in a broad temperature range. To obtain such information, we use the dynamic mechanical analysis and with the help of a reverse torsion pendulum measure the dynamic torsional rigidity of PCM bars of rectangular cross section in the temperature range up to 600 K. It is found that the temperature dependences of the dynamic rigidity of the calculated values of dynamic shear moduli are governed by the percentage and properties of the binder and fibers, the layout of fibers, the phase interaction along interfaces, etc. The principles of dynamic mechanical spectrometry are used to substantiate and analyze the parameters of anisotropy by which the behavior of a composite can be described in the temperature range including the transition of the binder from the glassy into a highly elastic state. For this purpose, the values of dynamic rigidity are measured under low-amplitude vibrations of the PCM specimens with a fiber orientation angle from 0 to 90°. It is shown that for unidirectional composites the dependence between the dynamic rigidity and the fiber orientation angle is of extreme character. The value and position of the peak depend on the type of the binder and fibers and change with temperature. It is found that the anisotropy degree of PCM is dictated by the molecular mobility and significantly changes in the temperature range of transition of the binder and reinforcement from the glassy into a highly elastic state (in the case of SVM fibers). The possibility of evaluating the anisotropy of composites with other reinforcement schemes, in particular, of orthogonally reinforced PCMs, is shown.
Regulation of Breast Cancer Stem Cell by Tissue Rigidity
2015-06-01
Gilman Drive, La Jolla, California 92093-0819, USA. 7Present address: Department of Immunology , The University of Texas MD Anderson Cancer Center, 7455...AD_________________ Award Number: W81XWH-13-1-0132 TITLE: Regulation of Breast Cancer Stem Cell by Tissue Rigidity PRINCIPAL INVESTIGATOR: Jing...for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of
A SYMPLECTIC ALGORITHM FOR DYNAMICS OF RIGID BODY
LU Ying-jie; REN Ge-xue
2006-01-01
For the dynamics of a rigid body with a fixed point based on the quaternion and the corresponding generalized momenta, a displacement-based symplectic integration scheme for differential-algebraic equations is proposed and applied to the Lagrange's equations based on dependent generalized momenta. Numerical experiments show that the algorithm possesses such characters as high precision and preserving system invariants.More importantly, the generalized momenta based Lagrange's equations show unique advantages over the traditional Lagrange's equations in symplectic integrations.
NOLB: Nonlinear Rigid Block Normal Mode Analysis Method
Hoffmann, Alexandre; Grudinin, Sergei
2017-01-01
International audience; We present a new conceptually simple and computationally efficient method for non-linear normal mode analysis called NOLB. It relies on the rotations-translations of blocks (RTB) theoretical basis developed by Y.-H. Sanejouand and colleagues. We demonstrate how to physically interpret the eigenvalues computed in the RTB basis in terms of angular and linear velocities applied to the rigid blocks and how to construct a non-linear extrapolation of motion out of these velo...
Elastic band ligation of hemorrhoids: Flexible gastroscope or rigid proctoscope?
M Cazemier; RJF Felt-Bersma; MA Cuesta; CJJ Mulder
2007-01-01
AIM: To compare rigid proctoscope and flexible endoscope for elastic band ligation of internal hemorrhoids.METHODS: Patients between 18 and 80 years old, with chronic complaints (blood loss, pain, itching or prolapse)of internal hemorrhoids of grade Ⅰ-Ⅲ, were randomized to elastic band ligation by rigid proctoscope or flexible endoscope (preloaded with 7 bands). Patients were retreated every 6 wk until the cessation of complaints.Evaluation by three-dimensional anal endosonography was performed.RESULTS: Forty-one patients were included (median age 52.0, range 27-79 years, 20 men). Nineteen patients were treated with a rigid proctoscope and twenty two with a flexible endoscope. Twenty-nine patients had grade Ⅰ hemorrhoids, 9 patients had grade Ⅱ hemorrhoids and 3 patients had grade Ⅲ hemorrhoids.All patients needed a minimum of 1 treatment and a maximum of 3 treatments. A median of 4.0 bands was used in the rigid proctoscope group and a median of 6.0 bands was used in the flexible endoscope group (P ＜ 0.05). Pain after ligation tended to be more frequent in patients treated with the flexible endoscope (first treatment: 3 vs 10 patients, P ＜ 0.05). Threedimensional endosonography showed no sphincter defects or alterations in submucosal thickness.CONCLUSION: Both techniques are easy to perform,well tolerated and have a good and fast effect. It is easier to perform more ligations with the flexible endoscope. Additional advantages of the flexible scope are the maneuverability and photographic documentation.However, treatment with the flexible endoscope might be more painful and is more expensive.
Bending rigid molecular rods: formation of oligoproline macrocycles.
Scully, Conor C G; Rai, Vishal; Poda, Gennadiy; Zaretsky, Serge; Burns, Darcy C; Houliston, R Scott; Lou, Tiantong; Yudin, Andrei K
2012-12-01
Bent but not broken: cyclic oligoprolines are accessed in a reaction that effectively bends rigid oligoproline peptides (see scheme; TBDMS=tert-butyldimethylsilyl). The stitching is accomplished during macrocyclization enabled by aziridine aldehydes and isocyanides. Molecular modeling studies suggest that electrostatic attraction between the termini of the linear peptide is pivotal for macrocyclization. The macrocycles were studied by circular dichroism with a polyproline II structure being observed in larger macrocycles.
On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue
Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.
2016-01-01
Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \
Potentials of Mean Force Between Rigid Solvated Polymers
FRINK, LAURA J.D.; SALINGER, ANDREW G.
1999-09-29
In this letter we discusses the first application of 3-dimensional nonlocal density functional calculations to the interactions of solvated rigid polymers. The three cases considered are cylindrical polymers, bead-chain polymers, and periodic polymers. We calculate potentials of mean force, and show that polymer surface structure plays a critical role in determining the solvation energy landscape which in turn controls routes to assembly of the macromolecules.
SEISMIC BEHAVIOR OF STEEL RIGID FRAME WITH IMPERFECT BRACE MEMBERS
AFZALI, Hamid; Yamao, Toshitaka; アフザリ, ハミッド; 山尾, 敏孝
2015-01-01
Model of a steel rigid frame made of thin-walled box section with existence of I-section brace member with initial overall and local imperfection adopted to investigate buckling effects on steel structural behavior as it was subjected to earthquake excitation. In order to take into account of the influence of local deflections on structural response, shell elements were employed to model brace member as well as base columns. Cross sections components with relatively high amplitude of buckling...
Rigid, Conjugated Macrocycles for High Performance Organic Photodetectors.
Zhang, Boyuan; Trinh, M Tuan; Fowler, Brandon; Ball, Melissa; Xu, Qizhi; Ng, Fay; Steigerwald, Michael L; Zhu, X-Y; Nuckolls, Colin; Zhong, Yu
2016-12-21
Organic photodetectors (OPDs) are attractive for their high optical absorption coefficient, broad wavelength tunability, and compatibility with lightweight and flexible devices. Here we describe a new molecular design that enables high performance organic photodetectors. We use a rigid, conjugated macrocycle as the electron acceptor in devices to obtain high photocurrent and low dark current. We make a direct comparison between the devices made with the macrocyclic acceptor and an acyclic control molecule; we find that the superior performance of the macrocycle originates from its rigid, conjugated, and cyclic structure. The macrocycle's rigid structure reduces the number of charged defects originating from deformed sp(2) carbons and covalent defects from photo/thermoactivation. With this molecular design, we are able to suppress dark current density while retaining high responsivity in an ultrasensitive nonfullerene OPD. Importantly, we achieve a detectivity of ∼10(14) Jones at near zero bias voltage. This is without the need for extra carrier blocking layers commonly employed in fullerene-based devices. Our devices are comparable to the best fullerene-based photodetectors, and the sensitivity at low working voltages (<0.1 V) is a record for nonfullerene OPDs.
Rigidity and retention of ceramic root canal posts.
Purton, D G; Love, R M; Chandler, N P
2000-01-01
Ceramic root-canal posts offer potential advantages over other types with respect to aesthetics and biocompatibility. Any post must be sufficiently rigid and retentive to withstand functional forces. Ceraposts (1.2 mm coronal diameter, ceramic, tapering, smooth posts) and Paraposts (1.25 mm, stainless-steel, parallel, serrated posts) were tested for rigidity by means of a three-point bending test. To test retention in roots, ceramic posts were cemented using one of three protocols: (1) glass-ionomer cement, (2) silane coupling agent and resin cement, or (3) sandblasted post surface, silane coupling agent, and resin cement. Stainless-steel posts were cemented with resin. The tensile force required to dislodge the posts, following four weeks of storage in water, was recorded. Data were compared using Student's t-test and Mann-Whitney U analysis. Ceraposts were significantly more rigid than Paraposts (p < 0.001). Paraposts cemented with resin were significantly more strongly retained than Ceraposts following any cementation protocol (p < 0.001). Retention of the ceramic posts was significantly greater with a silane coupling agent and resin cement than with glass-ionomer cement (p < 0.001). Sandblasting the ceramic posts produced variable results and needs further investigation before it could be recommended.
Cell movement is guided by the rigidity of the substrate
Lo, C. M.; Wang, H. B.; Dembo, M.; Wang, Y. L.
2000-01-01
Directional cell locomotion is critical in many physiological processes, including morphogenesis, the immune response, and wound healing. It is well known that in these processes cell movements can be guided by gradients of various chemical signals. In this study, we demonstrate that cell movement can also be guided by purely physical interactions at the cell-substrate interface. We cultured National Institutes of Health 3T3 fibroblasts on flexible polyacrylamide sheets coated with type I collagen. A transition in rigidity was introduced in the central region of the sheet by a discontinuity in the concentration of the bis-acrylamide cross-linker. Cells approaching the transition region from the soft side could easily migrate across the boundary, with a concurrent increase in spreading area and traction forces. In contrast, cells migrating from the stiff side turned around or retracted as they reached the boundary. We call this apparent preference for a stiff substrate "durotaxis." In addition to substrate rigidity, we discovered that cell movement could also be guided by manipulating the flexible substrate to produce mechanical strains in the front or rear of a polarized cell. We conclude that changes in tissue rigidity and strain could play an important controlling role in a number of normal and pathological processes involving cell locomotion.
On the Existence and Utility of Rigid Quasilocal Frames
Epp, Richard J; McGrath, Paul L
2013-01-01
The notion of a rigid quasilocal frame (RQF) provides a geometrically natural way to define a system in general relativity, and a new way to analyze the problem of motion. An RQF is defined as a two-parameter family of timelike worldlines comprising the boundary (topologically R x S^2) of the history of a finite spatial volume, with the rigidity conditions that the congruence of worldlines be expansion- and shear-free. In other words, the size and shape of the system do not change. In previous work, such systems in Minkowski space were shown to admit precisely the same six degrees of freedom of rigid body motion that we are familiar with in Newtonian space-time, without any constraints, circumventing a century-old theorem due to Herglotz and Noether. This is a consequence of the fact that a two-sphere of any shape always admits precisely six conformal Killing vector fields, which generate an action of the Lorentz group on the sphere. Here we review the previous work in flat spacetime and extend it in three di...
Spectral rigidity of automorphic orbits in free groups
Carette, Mathieu
2011-01-01
It is well-known that a point $T\\in cv_N$ in the (unprojectivized) Culler-Vogtmann Outer space $cv_N$ is uniquely determined by its \\emph{translation length function} $||.||_T:F_N\\to\\mathbb R$. A subset $S$ of a free group $F_N$ is called \\emph{spectrally rigid} if, whenever $T,T'\\in cv_N$ are such that $||g||_T=||g||_{T'}$ for every $g\\in S$ then $T=T'$ in $cv_N$. By contrast to the similar questions for the Teichm\\"uller space, it is known that for $N\\ge 2$ there does not exist a finite spectrally rigid subset of $F_N$. In this paper we prove that for $N\\ge 3$ the $Aut(F_N)$-orbit of an arbitrary nontrivial element in $F_N$ is spectrally rigid. We also show that for $F_2=F(a,b)$, the $Aut(F_2)$-orbit of every $g\\in F_2,g\
Stability design of structures with semi-rigid connections
Igić Tomislav
2010-01-01
Full Text Available The paper points out to the differences of the First order theory and Second order theory and of the significance in practical calculations. The paper presents theoretical foundations and expressions of calculations of impacts on the stability of structure, that is, review of the Second order theory in a bridge with members semi-rigid connections in joints. In the real structures in general and the especially in the prefabricated structures the connection of members in the nodes can be partially rigid which can be very significant for the changes in tension and deformation. If the influence of the normal forces is significant and the structure is slender then it is necessary to carry out a calculation according to the Second order theory because the balance between internal and external forces really established on the deformed configuration and displacements in strict formation are also unreal. The importance and significance of the calculations and distribution of impact according to the Second order theory were presented in numerical examples as well as the calculation of critical load as well as the buckling length of members with semi-rigid connections in joint.
Fundamental Study of Emulsions Stabilized by Soft and Rigid Particles.
Li, Zifu; Harbottle, David; Pensini, Erica; Ngai, To; Richtering, Walter; Xu, Zhenghe
2015-06-16
Two distinct uniform hybrid particles, with similar hydrodynamic diameters and comparable zeta potentials, were prepared by copolymerizing N-isopropylacrylamide (NIPAM) and styrene. These particles differed in their styrene to NIPAM (S/N) mass ratios of 1 and 8 and are referred to as S/N 1 and S/N 8, respectively. Particle S/N 1 exhibited a typical behavior of soft particles; that is, the particles shrank in bulk aqueous solutions when the temperature was increased. As a result, S/N 1 particles were interfacially active. In contrast, particle S/N 8 appeared to be rigid in response to temperature changes. In this case, the particles showed a negligible interfacial activity. Interfacial shear rheology tests revealed the increased rigidity of the particle-stabilized film formed at the heptane-water interface by S/N 1 than S/N 8 particles. As a result, S/N 1 particles were shown to be better emulsion stabilizers and emulsify a larger amount of heptane, as compared with S/N 8 particles. The current investigation confirmed a better performance of emulsion stabilization by soft particles (S/N 1) than by rigid particles (S/N 8), reinforcing the importance of controlling softness or deformability of particles for the purpose of stabilizing emulsions.
Peeling flexible beams in viscous fluids: Rigidity and extensional compliance
Dhong, Charles; Fréchette, Joëlle
2017-01-01
We describe small angle peeling measurements in completely submerged environments to study the coupling between viscous forces and the mechanical properties of the plates being peeled. During the experiments, the plates resist motion because of lubrication forces while van der Waals forces between the plates and the static surface are negligible. In particular, we study the role played by flexural rigidity in the force-displacement curves and in the energy release rate. We show that the coupling between the viscous forces and the flexural rigidity of the plates dictates the shape and magnitude of the force-displacement curves. We develop simple scaling relationships that combine the lubrication forces with an Euler-Bernoulli beam to extract how the peak force and energy release rates depend on the ratio between rigidity and viscosity, and show good agreement between the predictions and experimental results. We also show that increasing the extensional compliance leads to a decrease in both the force-displacement curve and in the energy release rate. We then demonstrate that this reduction can be interpreted in terms of a stress decay length.
Field-theoretic simulations of random copolymers with structural rigidity.
Mao, Shifan; MacPherson, Quinn; Qin, Jian; Spakowitz, Andrew J
2017-04-12
Copolymers play an important role in a range of soft-materials applications and biological phenomena. Prevalent works on block copolymer phase behavior use flexible chain models and incorporate interactions using a mean-field approximation. However, when phase separation takes place on length scales comparable to a few monomers, the structural rigidity of the monomers becomes important. In addition, concentration fluctuations become significant at short length scales, rendering the mean-field approximation invalid. In this work, we use simulation to address the role of finite monomer rigidity and concentration fluctuations in microphase segregation of random copolymers. Using a field-theoretic Monte-Carlo simulation of semiflexible polymers with random chemical sequences, we generate phase diagrams for random copolymers. We find that the melt morphology of random copolymers strongly depends on chain flexibility and chemical sequence correlation. Chemically anti-correlated copolymers undergo first-order phase transitions to local lamellar structures. With increasing degree of chemical correlation, this first-order phase transition is softened, and melts form microphases with irregular shaped domains. Our simulations in the homogeneous phase exhibit agreement with the density-density correlation from mean-field theory. However, conditions near a phase transition result in deviations between simulation and mean-field theory for the density-density correlation and the critical wavemode. Chain rigidity and sequence randomness lead to frustration in the segregated phase, introducing heterogeneity in the resulting morphologies.
DEFORMATION RIGIDITY OF ASSUMED STRESS MODES IN HYBRID ELEMENTS
ZHANG Can-hui; HUANG Qian; FENG Wei
2006-01-01
The new methods to determine the zero-energy deformation modes in the hybrid elements and the zero-energy stress modes in their assumed stress fields are presented by the natural deformation modes of the elements. And the formula of the additional element deformation rigidity due to additional mode into the assumed stress field is derived.Based on, it is concluded in theory that the zero-energy stress mode cannot suppress the zero-energy deformation modes but increase the extra rigidity to the nonzero-energy deformation modes of the element instead. So they should not be employed to assume the stress field. In addition, the parasitic stress modes will produce the spurious parasitic energy and result the element behaving over rigidity. Thus, they should not be used into the assumed stress field even though they can suppress the zero-energy deformation modes of the element. The numerical examples show the performance of the elements including the zero-energy stress modes or the parasitic stress modes.
Coarse-grained rigid blob model for soft matter simulations
Chao, Sheng D.; Kress, Joel D.; Redondo, Antonio
2005-06-01
We have developed a coarse-grained multiscale molecular simulation method for soft matter systems that directly incorporates stereochemical information. We divide the material into disjoint groups of atoms or particles that move as separate rigid bodies; we call these groups "rigid blobs," hence the name coarse-grained rigid blob model. The method is enabled by the construction of transferable interblob potentials that approximate the net intermolecular interactions, as obtained from ab initio electronic structure calculations, other all-atom empirical potentials, experimental data, or any combination of the above. We utilize a multipolar expansion to obtain the interblob potential-energy functions. The series, which contains controllable approximations that allow us to estimate the errors, approaches the original intermolecular potential as the number of terms increases. Using a novel numerical algorithm, we can calculate the interblob potentials very efficiently in terms of a few interaction moment tensors. This reduces the labor well beyond what is required in standard molecular-dynamics calculations and allows large-scale simulations for temporal scales commensurate with characteristic times of nano- and mesoscale systems. A detailed derivation of the formulas is presented, followed by illustrative applications to several systems showing that the method can effectively capture realistic microscopic details and can easily extend to large-scale simulations.
Representing plants as rigid cylinders in experiments and models
Vargas-Luna, Andrés; Crosato, Alessandra; Calvani, Giulio; Uijttewaal, Wim S. J.
2016-07-01
Simulating the morphological adaptation of water systems often requires including the effects of plants on water and sediment dynamics. Physical and numerical models need representing vegetation in a schematic easily-quantifiable way despite the variety of sizes, shapes and flexibility of real plants. Common approaches represent plants as rigid cylinders, but the ability of these schematizations to reproduce the effects of vegetation on morphodynamic processes has never been analyzed systematically. This work focuses on the consequences of representing plants as rigid cylinders in laboratory tests and numerical simulations. New experiments show that the flow resistance decreases for increasing element Reynolds numbers for both plants and rigid cylinders. Cylinders on river banks can qualitatively reproduce vegetation effects on channel width and bank-related processes. A comparative review of numerical simulations shows that Baptist's method that sums the contribution of bed shear stress and vegetation drag, underestimates bed erosion within sparse vegetation in real rivers and overestimates the mean flow velocity in laboratory experiments. This is due to assuming uniform flow among plants and to an overestimation of the role of the submergence ratio.
Molecular Rigidity and Entropy-Enthalpy Compensation in DNA Hybridization
Douglas, Jack; Vargas-Lara, Fernando
2015-03-01
Entropy-enthalpy compensation (EEC) is a general and relatively poorly understood pattern in the energetic parameters governing both binding constants and relaxation processes in condensed matter. After defining the basic phenomenology, we focus on how polymer additives, chain confinement, chain length variation affect a well-studied molecular binding process, the hybridization of duplex DNA. Our study is based on a coarse-grained model of DNA that does treat water explicitly. We find that both crowding due to polymer additives and geometrical confinement lead to a change of the effective chain rigidity and that changes in DNA generally lead to a pattern entropy-enthalpy compensation in the DNA association similar to experimental observations. Modulation of the rigidity of binding specifies by constraints associated with chain structure or environmental conditions can greatly influence both the location and cooperativity of molecular binding transition and the relative enthalpy and entropy contributions to the free energy of binding. Entropy-enthalpy compensation arises in numerous synthetic and biological molecular binding processes and we suggest that that changes in molecular rigidity might provide a common explanation of this ubiquitous phenomenon.
A comparison of neighbor search algorithms for large rigid molecules.
Artemova, Svetlana; Grudinin, Sergei; Redon, Stephane
2011-10-01
Fast determination of neighboring atoms is an essential step in molecular dynamics simulations or Monte Carlo computations, and there exists a variety of algorithms to efficiently compute neighbor lists. However, most of these algorithms are general, and not specifically designed for a given type of application. As a result, although their average performance is satisfactory, they might be inappropriate in some specific application domains. In this article, we study the case of detecting neighbors between large rigid molecules, which has applications in, e.g., rigid body molecular docking, Monte Carlo simulations of molecular self-assembly or diffusion, and rigid body molecular dynamics simulations. More precisely, we compare the traditional grid-based algorithm to a series of hierarchy-based algorithms that use bounding volumes to rapidly eliminate large groups of irrelevant pairs of atoms during the neighbor search. We compare the performance of these algorithms based on several parameters: the size of the molecules, the average distance between them, the cutoff distance, as well as the type of bounding volume used in the culling hierarchy (AABB, OBB, wrapped, or layered spheres). We demonstrate that for relatively large systems (> 100,000 atoms) the algorithm based on the hierarchy of wrapped spheres shows the best results and the traditional grid-based algorithm gives the worst timings. For small systems, however, the grid-based algorithm and the one based on the wrapped sphere hierarchy are beneficial. Copyright © 2011 Wiley Periodicals, Inc.
Drawing the Free Rigid Body Dynamics According to Jacobi
Pina, Eduardo G
2015-01-01
Guided by the Jacobi's work published the year before his death about the rotation of a rigid body, the behavior of the rotation matrix describing the dynamics of the free rigid body is studied. To illustrate this dynamics one draws on a unit sphere the trace of the three unit vectors, in the body system along the principal directions of inertia. A minimal set of properties of Jacobi's elliptic functions are used, those which allow to compute with the necessary precision the dynamics of the rigid body without torques, the so called Euler's top. Emphasis is on the paper published by Jacobi in 1850 on the explicit expression for the components of the rotation matrix. The tool used to compute the trajectories to be drawn are the Jacobi's Fourier series for {\\sl theta} and {\\sl eta} functions with extremely fast convergence. The Jacobi's {\\sl sn}, {\\sl cn} and {\\sl dn} functions, which are better known, are used also as ratios of {\\sl theta} functions which permit quick and accurate computation. Finally the main ...
Crack identification for rigid pavements using unmanned aerial vehicles
Bahaddin Ersoz, Ahmet; Pekcan, Onur; Teke, Turker
2017-09-01
Pavement condition assessment is an essential piece of modern pavement management systems as rehabilitation strategies are planned based upon its outcomes. For proper evaluation of existing pavements, they must be continuously and effectively monitored using practical means. Conventionally, truck-based pavement monitoring systems have been in-use in assessing the remaining life of in-service pavements. Although such systems produce accurate results, their use can be expensive and data processing can be time consuming, which make them infeasible considering the demand for quick pavement evaluation. To overcome such problems, Unmanned Aerial Vehicles (UAVs) can be used as an alternative as they are relatively cheaper and easier-to-use. In this study, we propose a UAV based pavement crack identification system for monitoring rigid pavements’ existing conditions. The system consists of recently introduced image processing algorithms used together with conventional machine learning techniques, both of which are used to perform detection of cracks on rigid pavements’ surface and their classification. Through image processing, the distinct features of labelled crack bodies are first obtained from the UAV based images and then used for training of a Support Vector Machine (SVM) model. The performance of the developed SVM model was assessed with a field study performed along a rigid pavement exposed to low traffic and serious temperature changes. Available cracks were classified using the UAV based system and obtained results indicate it ensures a good alternative solution for pavement monitoring applications.
1981-01-26
rials, the ordering of the chains, and the mechanical strenth of the resulting films or fibers . The basic goals are thus a molecular understanding of...polymers, cis and trans polybenzoxazoles (PBO) and polybenzothiazoles (PBT), form such phases, and energy calculations were therefore carried out to...Phys., 18, 000 (1981). 2. Phenylene Group Rotations and Nonplanar Conformations in Some Cis and Trans Polybenzoxazoles and Polybenzothiazoles, W. J
The Advanced Part of a Treatise on the Dynamics of a System of Rigid Bodies
Routh, Edward John
2013-03-01
Preface; 1. Moving axes and relative motion; 2. Oscillations about equilibrium; 3. Oscillations about a state of motion; 4. Motion of a body under no forces; 5. Motion of a body under any forces; 6. Nature of the motion given by linear equations and the conditions of stability; 7. Free and forced oscillations; 8. Determination of the constants of integration in terms of the initial conditions; 9. Calculus of finite differences; 10. Calculus of variations; 11. Precession and nutation; 12. Motion of the moon about its centre; 13. Motion of a string or chain; 14. Motion of a membrane; Notes.
ANALYSIS OF A PARTIALLY DEBONDED CONDUCTING RIGID ELLIPTICAL INCLUSION IN A PIEZOELECTRIC MATRIX
王旭; 沈亚鹏
2001-01-01
A closed-form full-field solution for the problem of a partially debonded conducting rigid elliptical inclusion embedded in a piezoelectric matrix is obtained by employing the eight-dimensional Stroh formula in conjunction with the techniques of conformal mapping, analytical continuation and singularity analysis. Some new identities and sums for anisotropic piezoelectric media are also derived, through which real-form expressions for the stresses and electric displacements along the interface as well as the rotation of the rigid inclusion can be obtained. As is expected, the stresses and electric displacements at the tips of the debonded part of the interface exhibit the same singular behavior as in the case of a straight Griffith interface crack between dissimilar piezoelectric media. Some numerical examples are presented to validate the correctness of the obtained solution and also to illustrate the generality of the exact solution and the effects of various electromechanical loading conditions, geometry parameters and material constants on the distribution of stresses and electric displacements along the interface.
Simulation of extension, radial and ulnar deviation of the wrist with a rigid body spring model.
Fischli, S; Sellens, R W; Beek, M; Pichora, D R
2009-06-19
A novel computational model of the wrist that predicts carpal bone motion was developed in order to investigate the complex kinematics of the human wrist. This rigid body spring model (RBSM) of the wrist was built using surface models of the eight carpal bones, the bases of the five metacarpal bones, and the distal parts of the ulna and radius, all obtained from computed tomography (CT) scans of a cadaver upper limb. Elastic contact conditions between the rigid bodies modeled the influence of the cartilage layers, and ligamentous structures were constructed using nonlinear, tension-only spring elements. Motion of the wrist was simulated by applying forces to the tendons of the five main wrist muscles modeled. Three wrist motions were simulated: extension, ulnar deviation and radial deviation. The model was tested and tuned by comparing the simulated displacement and orientation of the carpal bones with previously obtained CT-scans of the same cadaver arm in deviated (45 degrees ulnar and 15 degrees radial), and extended (57 degrees ) wrist positions. Simulation results for the scaphoid, lunate, capitate, hamate and triquetrum are presented here and provide credible prediction of carpal bone movement. These are the first reported results of such a model. They indicate promise that this model will assist in future wrist kinematics investigations. However, further optimization and validation are required to define and guarantee the validity of results.
Brazhe, A.; Fordsmann, J.; Lauritzen, M.
2017-01-01
Objectives: Correction for lateral displacements of the imaged area is often a necessary first step of processing calcium imaging data, especially in awake animal studies. We address two problems: (1) image displacements (warps) can be poorly described by simple rigid-body translations or shifts...
CHARACTERISTICS OF FLOW RESISTANCE IN OPEN CHANNELS WITH NON-SUBMERGED RIGID VEGETATION
WU Fu-sheng
2008-01-01
The flow resistance factors of non-submerged rigid vegetation in open channels were analyzed. The formulas of drag coefficient CD and equivalent Manning's roughness coefficient nd were derived by analyzing the force of the flow of non-submerged rigid vegetation in open channel. The flow characteristics and mechanism of non-submerged rigid vegetation in open channel were studied through flume experiments.
The diagnostic role of thoracoscope in undiagnosed pleural effusion: Rigid versus flexible
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.
Homogenization for rigid suspensions with random velocity-dependent interfacial forces
Gorb, Yuliya
2014-12-01
We study suspensions of solid particles in a viscous incompressible fluid in the presence of random velocity-dependent interfacial forces. The flow at a small Reynolds number is modeled by the Stokes equations, coupled with the motion of rigid particles arranged in a periodic array. The objective is to perform homogenization for the given suspension and obtain an equivalent description of a homogeneous (effective) medium, the macroscopic effect of the interfacial forces and the effective viscosity are determined using the analysis on a periodicity cell. In particular, the solutions uωε to a family of problems corresponding to the size of microstructure ε and describing suspensions of rigid particles with random surface forces imposed on the interface, converge H1-weakly as ε→0 a.s. to a solution of a Stokes homogenized problem, with velocity dependent body forces. A corrector to a homogenized solution that yields a strong H1-convergence is also determined. The main technical construction is built upon the Γ-convergence theory. © 2014 Elsevier Inc.
Developing rigid constraint for the estimation of pose and structure from a single image
魏宝刚; 刘永怀
2004-01-01
Pose and structure estimation from a single image is a fundamental problem in machine vision and multiple sensor fusion and integration.In this paper we propose using rigid constraints described in different coordinate frames to iteratively estimate structural and camera pose parameters.Using geometric properties of reflected correspondences we put forward a new concept,the reflected pole of a rigid transformation.The reflected pole represents a general analysis of transformations that can be applied to both 2D and 3D transformations.We demonstrate how the concept is applied to calibration by proposing an iterative method to estimate the structural parameters of objects.The method is based on a coarse-to-fine strategy in which initial estimation is obtained through a classical linear algorithm which is then refined by iteration.For a comparative study of performance,we also implemented an extended motion estimation algorithm(from 2D-2D to 3D-2D case)based on epipolar geometry.
Multibody Dynamic Stress Simulation of Rigid-Flexible Shovel Crawler Shoes
Samuel Frimpong
2016-06-01
Full Text Available Electric shovels are used in surface mining operations to achieve economic production capacities. The capital investments and operating costs associated with the shovels deployed in the Athabasca oil sands formation are high due to the abrasive conditions. The shovel crawler shoes interact with sharp and abrasive sand particles, and, thus, are subjected to high transient dynamic stresses. These high stresses cause wear and tear leading to crack initiation, propagation and premature fatigue failure. The objective of this paper is to develop a model to characterize the crawler stresses and deformation for the P&H 4100C BOSS during propel and loading using rigid-flexible multi-body dynamic theory. A 3-D virtual prototype model of the rigid-flexible crawler track assembly and its interactions with oil sand formation is simulated to capture the model dynamics within multibody dynamics software MSC ADAMS. The modal and stress shapes and modal loads due to machine weight for each flexible crawler shoes are generated from finite element analysis (FEA. The modal coordinates from the simulation are combined with mode and stress shapes using modal superposition method to calculate real-time stresses and deformation of flexible crawler shoes. The results show a maximum von Mises stress value of 170 MPa occurring in the driving crawler shoe during the propel motion. This study provides a foundation for the subsequent fatigue life analysis of crawler shoes for extending crawler service life.
Multiscale multiphysics and multidomain models--flexibility and rigidity.
Xia, Kelin; Opron, Kristopher; Wei, Guo-Wei
2013-11-21
The emerging complexity of large macromolecules has led to challenges in their full scale theoretical description and computer simulation. Multiscale multiphysics and multidomain models have been introduced to reduce the number of degrees of freedom while maintaining modeling accuracy and achieving computational efficiency. A total energy functional is constructed to put energies for polar and nonpolar solvation, chemical potential, fluid flow, molecular mechanics, and elastic dynamics on an equal footing. The variational principle is utilized to derive coupled governing equations for the above mentioned multiphysical descriptions. Among these governing equations is the Poisson-Boltzmann equation which describes continuum electrostatics with atomic charges. The present work introduces the theory of continuum elasticity with atomic rigidity (CEWAR). The essence of CEWAR is to formulate the shear modulus as a continuous function of atomic rigidity. As a result, the dynamics complexity of a macromolecular system is separated from its static complexity so that the more time-consuming dynamics is handled with continuum elasticity theory, while the less time-consuming static analysis is pursued with atomic approaches. We propose a simple method, flexibility-rigidity index (FRI), to analyze macromolecular flexibility and rigidity in atomic detail. The construction of FRI relies on the fundamental assumption that protein functions, such as flexibility, rigidity, and energy, are entirely determined by the structure of the protein and its environment, although the structure is in turn determined by all the interactions. As such, the FRI measures the topological connectivity of protein atoms or residues and characterizes the geometric compactness of the protein structure. As a consequence, the FRI does not resort to the interaction Hamiltonian and bypasses matrix diagonalization, which underpins most other flexibility analysis methods. FRI's computational complexity is of O
Jeng Hei Chow
2016-07-01
Full Text Available An implicit method of solving the six degree-of-freedom rigid body motion equations based on the second order Adams-Bashforth-Moulten method was utilised as an improvement over the leapfrog scheme by making modifications to the rigid body motion solver libraries directly. The implementation will depend on predictor-corrector steps still residing within the hybrid Pressure Implicit with Splitting of Operators - Semi-Implicit Method for Pressure Linked Equations (PIMPLE outer corrector loops to ensure strong coupling between fluid and motion. Aitken's under-relaxation is also introduced in this study to optimise the convergence rate and stability of the coupled solver. The resulting coupled solver ran on a free floating object tutorial test case when converged matches the original solver. It further allows a varying 70%–80% reduction in simulation times compared using a fixed under-relaxation to achieve the required stability.
De Ryck, L; Lauriks, W; Leclaire, P; Groby, J P; Wirgin, A; Depollier, C
2008-09-01
The present paper deals with the inverse scattering problem involving macroscopically inhomogeneous rigid frame porous media. It consists of the recovery, from acoustic measurements, of the profiles of spatially varying material parameters by means of an optimization approach. The resolution is based on the modeling of acoustic wave propagation in macroscopically inhomogeneous rigid frame porous materials, which was recently derived from the generalized Biot's theory. In practice, the inverse problem is solved by minimizing an objective function defined in the least-square sense by the comparison of the calculated reflection (and transmission) coefficient(s) with the measured or synthetic one(s), affected or not by additive Gaussian noise. From an initial guess, the profiles of the x-dependent material parameters are reconstructed iteratively with the help of a standard conjugate gradient method. The convergence rate of the latter and the accuracy of the reconstructions are improved by the availability of an analytical gradient.
Sound objects – Auditory objects – Musical objects
Hjortkjær, Jens
2015-01-01
The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects......’. In this paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent...
Sound objects – Auditory objects – Musical objects
Hjortkjær, Jens
2016-01-01
The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects......’. In this paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent...
An Adaptive Frame Skipping and VOP Interpolation Algorithm for Video Object Segmentation
YANGGaobo; ZHANGZhaoyang
2004-01-01
Video object segmentation is a key step for the successful use of MPEG-4. However, most of the current available segmentation algorithms are still far away from real-time performance. In order to improve the processing speed, an adaptive frame skipping and VOP interpolation algorithm is proposed in this paper. It adaptively determines the number of skipped frames based on the rigidity and motion complexity of video object. To interpolate the VOPs for skipped frames, a hi-directional projection scheme is adopted. Its principle is to perform a classification of those regions obtained by spatial segmentation for every frame in the sequence. It is valid for both rigid object and non-rigid object and can get good localization of object boundaries. Experimental results show that the proposed approach can improve the processing speed greatly while maintaining visually pleasant results.
Rigidity and pH dependent Morphology of Beta-Lactoglobulin Spherulites
Gayetsky, Lisa; Armstead, Douglas
2008-03-01
Beta-Lactoglobulin is a milk protein that will denature in acidic solution (less than 2.0 pH) and if heated for extended periods (greater than 18 hours) it will form radial structures called Spherulites. Spherulites, along with the amyloid fibrils that compose them, are of practical importance because they form in the human body and cause the amyloidosis diseases. Different amyloidosis are caused by different types of denatured proteins occurring in different parts of the body. Since it is believed that Spherulite formation is a generic protein characteristic, Beta-Lactoglobulin is a legitimate and easy to use protein to study these structures. In this study we are quantifying the shape of Beta-Lactoglobulin Spherulites to determine if the pH of the protein solution has an impact on the morphology due to side chain interactions or other causes. We are also testing the rigidity of these structures to determine the relevance of small shape changes.
Yield and Solidification of Yield-Stress Materials in Rigid Networks and Porous Structures
Sochi, Taha
2013-01-01
In this paper, we address the issue of threshold yield pressure of yield-stress materials in rigid networks of interconnected conduits and porous structures subject to a pressure gradient. We compare the results as obtained dynamically from solving the pressure field to those obtained statically from tracing the path of the minimum sum of threshold yield pressures of the individual conduits by using the threshold path algorithms. We refute criticisms directed recently to our previous findings that the pressure field solution generally produces a higher threshold yield pressure than the one obtained by the threshold path algorithms. Issues related to the solidification of yield stress materials in their transition from fluid phase to solid state have also been investigated and assessed as part of the investigation of the yield point.
Mathey Charlie
2015-01-01
Full Text Available The present work investigates on the influence of small geometrical defects on the behavior of slender rigid blocks. A comprehensive experimental campaign was carried out on one of the shake tables of CEA/Saclay in France. The tested model was a massive steel block with standard manufacturing quality. Release, free oscillations tests as well as shake table tests revealed a non-negligible out-of-plane motion even in the case of apparently plane initial conditions or excitations. This motion exhibits a highly reproducible part for a short duration that was used to calibrate a numerical geometrically asymmetrical model. The stability of this model when subjected to 2 000 artificial seismic horizontal bidirectional signals was compared to the stability of a symmetrical one. This study showed that the geometrical imperfections slightly increase the rocking and overturning probabilities under bidirectional seismic excitations in a narrow range of peak ground acceleration.
NOLB : Non-linear rigid block normal mode analysis method.
Hoffmann, Alexandre; Grudinin, Sergei
2017-04-05
We present a new conceptually simple and computationally efficient method for non-linear normal mode analysis called NOLB. It relies on the rotations-translations of blocks (RTB) theoretical basis developed by Y.-H. Sanejouand and colleagues. We demonstrate how to physically interpret the eigenvalues computed in the RTB basis in terms of angular and linear velocities applied to the rigid blocks and how to construct a non-linear extrapolation of motion out of these velocities. The key observation of our method is that the angular velocity of a rigid block can be interpreted as the result of an implicit force, such that the motion of the rigid block can be considered as a pure rotation about a certain center. We demonstrate the motions produced with the NOLB method on three different molecular systems and show that some of the lowest frequency normal modes correspond to the biologically relevant motions. For example, NOLB detects the spiral sliding motion of the TALE protein, which is capable of rapid diffusion along its target DNA. Overall, our method produces better structures compared to the standard approach, especially at large deformation amplitudes, as we demonstrate by visual inspection, energy and topology analyses, and also by the MolProbity service validation. Finally, our method is scalable and can be applied to very large molecular systems, such as ribosomes. Standalone executables of the NOLB normal mode analysis method are available at https://team.inria.fr/nano-d/software/nolb-normal-modes. A graphical user interfaces created for the SAMSON software platform will be made available at https: //www.samson-connect.net.
Cohomological rigidity of manifolds defined by 3-dimensional polytopes
Buchstaber, V. M.; Erokhovets, N. Yu.; Masuda, M.; Panov, T. E.; Park, S.
2017-04-01
A family of closed manifolds is said to be cohomologically rigid if a cohomology ring isomorphism implies a diffeomorphism for any two manifolds in the family. Cohomological rigidity is established here for large families of 3-dimensional and 6-dimensional manifolds defined by 3-dimensional polytopes. The class \\mathscr{P} of 3-dimensional combinatorial simple polytopes P different from tetrahedra and without facets forming 3- and 4-belts is studied. This class includes mathematical fullerenes, that is, simple 3- polytopes with only 5-gonal and 6-gonal facets. By a theorem of Pogorelov, any polytope in \\mathscr{P} admits in Lobachevsky 3-space a right-angled realisation which is unique up to isometry. Our families of smooth manifolds are associated with polytopes in the class \\mathscr{P}. The first family consists of 3-dimensional small covers of polytopes in \\mathscr{P}, or equivalently, hyperbolic 3-manifolds of Löbell type. The second family consists of 6-dimensional quasitoric manifolds over polytopes in \\mathscr{P}. Our main result is that both families are cohomologically rigid, that is, two manifolds M and M' from either family are diffeomorphic if and only if their cohomology rings are isomorphic. It is also proved that if M and M' are diffeomorphic, then their corresponding polytopes P and P' are combinatorially equivalent. These results are intertwined with classical subjects in geometry and topology such as the combinatorics of 3-polytopes, the Four Colour Theorem, aspherical manifolds, a diffeomorphism classification of 6-manifolds, and invariance of Pontryagin classes. The proofs use techniques of toric topology. Bibliography: 69 titles.
Classical models of affinely-rigid bodies with "thickness" in degenerate dimension
Kovalchuk, Vasyl
2009-01-01
The special interest is devoted to such situations when the material space of our object with affine degrees of freedom has generally lower dimension than the one of the physical space. In other words when we have the $m$-dimensional affinely-rigid body moving in the $n$-dimensional physical space, $m
Mazur, Alexey K.
1999-07-01
Internal coordinate molecular dynamics (ICMD) is a recent efficient method for modeling polymer molecules which treats them as chains of rigid bodies rather than ensembles of point particles as in Cartesian MD. Unfortunately, it is readily applicable only to linear or tree topologies without closed flexible loops. Important examples violating this condition are sugar rings of nucleic acids, proline residues in proteins, and also disulfide bridges. This paper presents the first complete numerical solution of the chain closure problem within the context of ICMD. The method combines natural implicit fixation of bond lengths and bond angles by the choice of internal coordinates with explicit constraints similar to Cartesian dynamics used to maintain the chain closure. It is affordable for large molecules and makes possible 3-5 times faster dynamics simulations of molecular systems with flexible rings, including important biological objects like nucleic acids and disulfide-bonded proteins.
Zhao, J. W.; Ding, G. H.; Yin, W. Y.; Yang, X. J.; Shi, W. C.; Zhang, X. L.
The objective of this study is to investigate the effect of hemodynamic parameters on the formation, growth and rupture of an aneurysm. Our simulation of the elastic and rigid aneurysm is based on a DSA or other clinic image. The simulatied results are that there are great differences in the distribution of velocity magnitude at some sections which are predicted by the two models. For the elastic wall model, the distribution of velocity magnitude of one outlet is obviously off-center, which influences the distribution of wall shear stress (WSS) and exchange of substance through the vessel wall. The currents of the distributions of WSS along the wall of aneurysm for the two models are similar. But there are obvious differences between the two models in the values especially at the neck of aneurysm. This study demonstrates obviously that the elastic wall model suits the simulation for growth and rupture of an aneurysm better.
Dynamics Research of rigid-flexible model of crank-rocker mechanism with Multi Clearance
Bo Shao Jun
2016-01-01
Full Text Available This paper takes the crank-rocker mechanism as the research object, purposed for the simulation of the motion pair with clearance utilizing the contact force model and the coulomb friction model, we build the virtual prototype of four-bar mechanism with clearance joints in the ADAMS. The article mainly contrasts the influence dynamics characteristics towards the mechanism multi-joint clearance between the rigid rocker and the flexible rocker. Considering the jointed arm’s flexibility, the four, five and six order modal of the rocker, generated by ANSYS as a neutral document, were imported into ADAMS for simulation. The result shows that Mechanism with four joint clearance increased the impact on the speed and the acceleration appeared greater fluctuation, the flexible rod has a buffer effect to the contact-impact forces, and the dynamic characteristics of fluctuations are improved.
Crosslinking of rigid PVC by ionizing radiation to improve its thermal properties
Garcia-Castaneda, C. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna 140, Saltillo Coahuila (Mexico); Benavides, R., E-mail: robertob@ciqa.m [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna 140, Saltillo Coahuila (Mexico); Martinez-Pardo, M.E. [Instituto Nacional de Investigaciones Nucleares, Apartado postal 18-1027, Col. Escandon, 11801 Mexico, D.F. (Mexico); Uribe, R.M. [Kent State University, College of Technology and Program on Electron Beam Technology, P.O. Box 5190, Kent, OH 44242-0001 (United States); Carrasco-Abrego, H. [Instituto Nacional de Investigaciones Nucleares, Apartado postal 18-1027, Col. Escandon, 11801 Mexico, D.F. (Mexico); Martinez, G. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna 140, Saltillo Coahuila (Mexico)
2010-03-15
Rigid PVC formulations containing two different stabilizer systems (tin and Ca/Zn) and TMPTMA as a crosslinking agent were treated with ionizing radiation (gamma and electron beam) at different doses and irradiation atmospheres. The objective was to increase thermal and mechanical properties of this material. Polyene formation was followed through the yellowing index (YI), the extent of crosslinking by gel percentage, thermal resistance by Vicat temperature and the mechanical properties by DMA. Both formulations became colored with irradiation, especially with gamma as a result of a longer treatment time; the gel formation and the Vicat temperature were also higher for gamma treated samples, suggesting that values were enhanced by oxidation. However, DMA elastic modulus traces were almost similar for both treatments. The main difference observed for Ca/Zn samples compared with traditional tin samples was the lower ability of the former system in protecting the material against processing conditions.
Relativistic particles with rigidity generating non-standard examples of Willmore-Chen hypersurfaces
Arroyo, Josu; Garay, Oscar J. [Departamento de Matematicas, Universidad del Pais Vasco, Bilbao (Spain)]. E-mails: mtparolj@lg.ehu.es; mtpgabeo@lg.ehu.es; Barros, Manuel [Departamento de Geometria y Topologia, Universidad de Granada, Granada (Spain)]. E-mail: mbarros@ugr.es
2002-08-16
We study a natural extension to higher dimensions of the Nambu-Goto-Polyakov action. In particular, those dynamical objects evolving with SO(3) symmetry in four dimensions. We show that this problem is strongly related to that of relativistic particles with rigidity of order three in a hyperbolic plane. The moduli space of solitonic solutions is completely determined in terms of the so-called rotation number. A quantization principle for closed solutions is also obtained and this gives a rational one-parameter family of Willmore-Chen hypersurfaces in the standard conformal structure of dimension four. Moreover, these are the first non-standard examples of this kind of hypersurfaces. (author)
Coordinating control of multiple rigid bodies based on motion primitives
Fan Wu; Zhi-Yong Geng
2012-01-01
This paper studies the problem of coordinated motion generation for a group of rigid bodies.Two classes of coordinated motion primitives,relative equilibria and maneuvers,are given as building blocks for generating coordinated motions.In a motion-primitive based planning framework,a control method is proposed for the robust execution of a coordinated motion plan in the presence of perturbations,The control method combines the relative equilibria stabilization with maneuver design,and results in a closeloop motion planning framework.The performance of the control method has been illustrated through a numerical simulation.
Control of the rigid body and dynamics with symmetry
Lum, Kai-Yew
This dissertation explores various problems in the control of the rigid body and related dynamical systems with symmetry, utilizing various modeling approaches and control techniques. We first derive a control law that asymptotically stabilizes an unbalanced top to the sleeping motion. We rewrite the classical Euler-Poisson equations by projecting the phase space onto IRsp5. The control law is based on the Hamilton-Jacobi-Bellman theory with zero dynamics and partial stability. Lyapunov techniques are used in the analysis. Next, the control of rotor imbalance with magnetic bearings is considered in the adaptive virtual autobalancing and adaptive autocentering approaches. We derive single-plane and two-plane balancing control algorithms that provide asymptotic estimates of the rotor imbalance, and that guarantee consistent performance under varying spin rate. These algorithms are based on emulation of the mechanical autobalancer. We discuss the theory based on linear analysis, and simulation and experimental results. We go on to investigate symmetry properties associated with mechanical control systems and certain nonlinear control systems. First, we generalize the classical Serret-Andoyer transformation for the free rigid body to left-invariant, hyperregular Hamiltonian systems on Tsp*SO(3), employing the notion of symplectic (Marsden-Weinstein) reduction. We then apply this result to the controlled rigid body, and show that for Hamiltonian controls that preserve the rigid body structure, the generalized Serret-Andoyer transformation yields a two dimensional representation of the closed-loop motion in canonical form. Applications to the stability analysis of relative equilibria and numerical integration are also discussed. Finally, we apply the concept of reduction to certain regulation problems on smooth manifolds. Following the works of Van der Schaft (1981) and Grizzle and Marcus (1985), we show that an output feedback regulation problem possessing certain
The market for large rigid haul trucks in surface mining
Gilewicz, P.
2002-04-15
Originally published in 2001 this updated report provides a definition of the market for large rigid haulers in surface mining. The analysis covers changes to the mining market segments buying these machines including the gains made by coal producers, retrenchment in copper mining, the consolidation taking place among gold mining companies, and the expansion of iron ore producers in Australia and Brazil. It includes a detailed accounting of 2001 truck shipments, and an analysis of trends in the Ultra-truck segment. It concludes with a revised forecast for shipments through 2006. 12 charts, 56 tabs., 2 apps.
Rigid connections between natural teeth and implants: a technical note.
Lindh, T; Gunne, J; Danielsson, S
1997-01-01
In the posterior partially edentulous jaw, implants may be used to supplement existing natural dentition. Frequently, the maxillary sinuses and the mandibular nerve preclude the fabrication of freestanding implant-retained prostheses. However, if an implant and a natural abutment are combined, a fixed prosthesis can be fabricated, restoring the arch into the premolar area. The histories of three patients with attachments connecting implant-retained ceramotitanium crowns with crowns on natural abutments are described. A design for a rigid custom-made attachment for the Brånemark system, using standard components with a machine-duplication, spark-erosion technique, is suggested.
On rigid supersymmetry and notions of holomorphy in five dimensions
Pan, Yiwen [C.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794 (United States); Schmude, Johannes [Department of Physics, Universidad de Oviedo, 33007, Oviedo (Spain)
2015-11-06
We study the equations governing rigid N=1 supersymmetry in five dimensions. If the supersymmetry spinor satisfies a reality condition, these are foliations admitting families of almost complex structures on the leaves. In other words, all these manifolds have families of almost Cauchy-Riemann (CR) structures. After deriving integrability conditions under which circumstances the almost CR structure defines a CR manifold or a transversally holomorphic foliation (THF), we discuss implications on localization. We also discuss potential global obstructions to the existence of solutions.
Simplified seismic fatigue evaluation for rigid steel connections
Ayman A.Shama; John B. Mander; Stuart. S. Chen
2003-01-01
A simplified fatigue-life model is proposed for assessing the seismic inelastic rotational capacity of steel connections. First relations are developed for rigid steel connections under lateral loading. Next this is extended to account for the effects of the welded steel moment frame (WSMF) connections of the so-called pre-Northridge type. The seismic fatigue theory is validated against experimental results. The experiments were conducted under increasing ductility amplitudcs until the onset of fracture. Miner' rule was used to convert the test results to given an equivalent constant amplitude cyclic fatigue life. Satisfactory agreement is obtained when comparing the experimental observations with the theoretical predictions.
Drift of rigidly rotating spirals under periodic and noisy illuminations.
Zhang, Hong; Wu, Ning-Jie; Ying, He-Ping; Hu, Gang; Hu, Bambi
2004-10-15
Under the weak deformation approximation, the motion of rigidly rotating spirals induced by periodic and noisy illuminations are investigated analytically. We derive an approximate but explicit formula of the spiral drift velocity directly from the original reaction-diffusion equation. With this formula we are able to explain the main features in the periodic and noisy illuminations induced spiral drift problems. Numerical computations of the Oregonator model are carried out as well, and they agree with the main qualitative conclusions of our analytical results.