Type synthesis of 90°/180° dual-function upenders for large shell units of nuclear reactor

In this paper, unit vectors collinear with the axes of large shell units of nuclear reactors were used to represent the poses of the workpieces. Based on the motion operator interpretation of the rotation matrix, 60 kinds of rotation matrix permutations with 90° turns as the step length to achieve 180° flipping of the workpiece were obtained. After eliminating invalid permutations and merging homogenous permutations, class I, II, and III flipping motion models were obtained. By calculating the Lie algebra of each step of rigid body motion in the flipping motion model, the twist and the motion pair property for each step were obtained. By means of the permutation and combination theory, the sequence of the motion pairs for different configurations was determined, and the rules between sequential transformations and axis changes of the motion pairs under the initial configuration were stipulated. Three classes of 19 initial configurations of 90°/180° dual-function upenders were constructed. For three of them, taking into account the characteristics of the axial dimension variation of workpieces, prismatic pairs were added along the workpiece’s axis (vector), and 15 overall configurations of 90°/180° dual-function upenders were synthesized. This provides the basic theoretical support for the innovative design of upenders with independent intellectual property rights.

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Impaired Scaling of Step Length in Parkinsonian Postural Instability

10.1101/2020.08.25.20179945 ◽

2020 ◽

Author(s):

Robert A McGovern ◽

Juan C Cortes ◽

Anne P Wilson ◽

Guy M McKhann ◽

Pietro Mazzoni

Keyword(s):

Motor Control ◽

Normal Pressure ◽

Step Length ◽

Body Motion ◽

Control Group ◽

Linear Scaling ◽

Body Acceleration ◽

Postural Perturbations ◽

Length Scaling ◽

Partial Compensation

Background: Postural stepping is an important strategy for recovery of balance in response to postural perturbations. It is disrupted by Parkinson's disease (PD) and other conditions. The nature of this disruption remains poorly understood. Understanding the motor control nature of this impairment can guide the development of novel interventions. Objectives: To identify the motor control abnormalities responsible for parkinsonian impairment of postural stepping. Methods: We studied four groups of participants: control, aged, PD, and normal-pressure hydrocephalus (NPH). We performed kinematic analysis of postural stepping by recording participants' body motion during a modified version of the clinical pull test, which was performed multiple times with different amounts of pulling forcefulness. Results: Successful postural stepping in the control group was accompanied by linear scaling of their first step's length and latency to the body's initial motion: more forceful pulls caused larger initial body acceleration, which resulted in longer steps that began earlier. PD patients exhibited reduced scaling of step length: they maintained normal reaction time but took steps that were inadequately short. Reduced step length scaling was present, but less severe, in aged individuals, and was more severe in NPH patients. Aged individuals and PD patients exhibited partial compensation for reduced step length scaling: their step length included a component that was independent of initial body acceleration, which was absent in control and NPH groups. Conclusions: the impairment of postural stepping caused by PD and related conditions is due to inadequate scaling of movement amplitude and is thus a form of hypokinesia.

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Accuracy of a System for Measuring Three-Dimensional Torso Kinematics during Manual Materials Handling

Journal of Applied Biomechanics ◽

10.1123/jab.20.2.185 ◽

2004 ◽

Vol 20 (2) ◽

pp. 185-194

Author(s):

Rebecca J. Giorcelli ◽

Richard E. Hughes ◽

Richard S. Current ◽

John R. Myers

Keyword(s):

Measurement System ◽

Measurement Errors ◽

Three Dimensional ◽

Rotation Matrix ◽

Body Motion ◽

Lateral Bending ◽

Test Fixture ◽

Motion Measurement ◽

Materials Handling ◽

Value Decomposition

This paper describes a procedure developed and validated to assess the accuracy of an infrared-based motion measurement system used to perform a kinematic analysis of the torso with respect to the pelvis during simulated lifting tasks. Two rigid reflective marker triads were designed and fabricated for attachment to the thorax over the 6th thoracic vertebra and the pelvis. System accuracy was assessed for planar rotation as well as rotations about multiple orthogonal axes. A test fixture was used to validate known triad orientations. The spatial coordinates of these triads were collected at 120 Hz using a ProReflex motion measurement system. Single value decomposition was used to estimate a rotation matrix describing the rigid body motion of the thorax triad relative to the sacral triad at each point in time. Euler angles corresponding to flexion, lateral bending, and twisting were computed from the rotation matrix. All measurement error residuals for flexion, lateral bending, and twisting were below 1.75°. The estimated mean measurement errors were less than 1° in all three planes. These results suggest that the motion measurement system is reliable and accurate to within approximately 1.5° for the angles examined.

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Analysis and Model-Based Control of Servomechanisms With Friction

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.1849245 ◽

2004 ◽

Vol 126 (4) ◽

pp. 911-915 ◽

Cited By ~ 20

Author(s):

Evangelos G. Papadopoulos ◽

Georgios C. Chasparis

Keyword(s):

Rigid Body ◽

Function Analysis ◽

Friction Model ◽

Body Motion ◽

System Response ◽

Friction Compensation ◽

Kinetic Friction ◽

Motion Models ◽

Model Based ◽

Best Response

Friction is responsible for several servomechanism limitations, and their elimination is always a challenge for control engineers. In this paper, model-based feedback compensation is studied for servomechanism tracking tasks. Several kinetic friction models are employed and their parameters identified experimentally. The effects of friction compensation on system response are examined using describing function analysis. A number of control laws including classical laws, rigid body motion models, and friction compensation are compared experimentally in large-displacement tasks. Results show that the best response is obtained using a controller that incorporates a rigid body model and a friction model based on an accurate description of identified kinetic friction effects.

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Human Motion Modeling With a Robotics Method: Analysis of a Person Riding a Bus

ASME 2008 Dynamic Systems and Control Conference, Parts A and B ◽

10.1115/dscc2008-2192 ◽

2008 ◽

Cited By ~ 1

Author(s):

Ashish D. Deshpande ◽

Jonathan E. Luntz

Keyword(s):

Equations Of Motion ◽

Human Motion ◽

Contact Forces ◽

Body Motion ◽

Control Analysis ◽

Motion Modeling ◽

Open Chain ◽

Motion Models ◽

Performance Requirements ◽

And Control

Deriving models of human body motion is important for prosthetics, rehabilitation and development of humanoids. We present a method that simplifies the derivation of equations of motion of human movements. We illustrate our approach by deriving motion models of a person riding in a moving bus. Our approach simplifies the derivation of dynamics as only open chain dynamics are to be derived. The kinematic constraints are then introduced to represent a complete system model in which the contact forces appear explicitly. We then constrain the contact forces based on the performance requirements to determine the feasibility of motions, which is difficult to determine with the traditional methods. Our model allows for the design and control analysis, specifically, the derivation of the relationship between the change in rider’s posture and the feasibility of motions.

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Development of dynamic motion models of SPACE code for ocean nuclear reactor analysis

Nuclear Engineering and Technology ◽

10.1016/j.net.2021.09.025 ◽

2021 ◽

Author(s):

Byoung Jae Kim ◽

Seung Wook Lee

Keyword(s):

Nuclear Reactor ◽

Dynamic Motion ◽

Motion Models

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In situ TEM studies of irradiation effects for materials improvement

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086568 ◽

1991 ◽

Vol 49 ◽

pp. 452-453

Author(s):

Charles W. Allen

Keyword(s):

Nuclear Reactor ◽

Austenitic Stainless Steels ◽

High Energy ◽

Point Of View ◽

In Situ Tem ◽

Irradiation Effects ◽

Tem Analysis ◽

Radiation Induced ◽

Analytical Tools

Irradiation effects studies employing TEMs as analytical tools have been conducted for almost as many years as materials people have done TEM, motivated largely by materials needs for nuclear reactor development. Such studies have focussed on the behavior both of nuclear fuels and of materials for other reactor components which are subjected to radiation-induced degradation. Especially in the 1950s and 60s, post-irradiation TEM analysis may have been coupled to in situ (in reactor or in pile) experiments (e.g., irradiation-induced creep experiments of austenitic stainless steels). Although necessary from a technological point of view, such experiments are difficult to instrument (measure strain dynamically, e.g.) and control (temperature, e.g.) and require months or even years to perform in a nuclear reactor or in a spallation neutron source. Consequently, methods were sought for simulation of neutroninduced radiation damage of materials, the simulations employing other forms of radiation; in the case of metals and alloys, high energy electrons and high energy ions.

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Eds Of Radioactive Particles By Self-Induced Fluorescence

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013479x ◽

1990 ◽

Vol 48 (2) ◽

pp. 238-239

Author(s):

Gregory L. Finch ◽

Richard G. Cuddihy

Keyword(s):

Electron Beam Irradiation ◽

Nuclear Reactor ◽

X Rays ◽

Reactor Accident ◽

Internal Radiation ◽

X Ray ◽

External Sources ◽

X Irradiation ◽

Available Information ◽

Individual Particles

The elemental composition of individual particles is commonly measured by using energydispersive spectroscopic microanalysis (EDS) of samples excited with electron beam irradiation. Similarly, several investigators have characterized particles by using external monochromatic X-irradiation rather than electrons. However, there is little available information describing measurements of particulate characteristic X rays produced not from external sources of radiation, but rather from internal radiation contained within the particle itself. Here, we describe the low-energy (< 20 KeV) characteristic X-ray spectra produced by internal radiation self-excitation of two general types of particulate samples; individual radioactive particles produced during the Chernobyl nuclear reactor accident and radioactive fused aluminosilicate particles (FAP). In addition, we compare these spectra with those generated by conventional EDS.Approximately thirty radioactive particle samples from the Chernobyl accident were on a sample of wood that was near the reactor when the accident occurred. Individual particles still on the wood were microdissected from the bulk matrix after bulk autoradiography.

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Japanese nuclear reactor under-designed for earthquake?

Nature ◽

10.1038/news070716-3 ◽

2007 ◽

Author(s):

David Cyranoski

Keyword(s):

Nuclear Reactor

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Becoming the Nuclear-Front-End

PROKLA Zeitschrift für kritische Sozialwissenschaft ◽

10.32387/prokla.v47i189.59 ◽

2017 ◽

Vol 47 (189) ◽

Author(s):

Patrick Schukalla

Keyword(s):

Nuclear Reactor ◽

Chemical Elements ◽

High Technology ◽

Power Production ◽

Uranium Mining ◽

Nuclear Industry ◽

Current State ◽

Front End ◽

Production And Consumption ◽

Uranium Exploration

Uranium mining often escapes the attention of debates around the nuclear industries. The chemical elements’ representations are focused on the nuclear reactor. The article explores what I refer to as becoming the nuclear front – the uranium mining frontier’s expansion to Tanzania, its historical entanglements and current state. The geographies of the nuclear industries parallel dominant patterns and the unevenness of the global divisions of labour, resource production and consumption. Clearly related to the developments and expectations in the field of atomic power production, uranium exploration and the gathering of geological knowledge on resource potentiality remains a peripheral realm of the technopolitical perceptions of the nuclear fuel chain. Seen as less spectacular and less associated with high-technology than the better-known elements of the nuclear industry the article thus aims to shine light on the processes that pre-figure uranium mining by looking at the example of Tanzania.

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