Control of Vibration Flow at the Joint of an L-Shaped Frame

2007 ◽  
Author(s):  
C. Mei
Keyword(s):  
Vibration Control ◽  
Control Strategy ◽  
Mechanical Systems ◽  
Structural Elements ◽  
Structural Components ◽  
Structural Element ◽  
Shaped Beam ◽  
Structural Joint ◽  
Structural Joints ◽  
Vibration Problems

There has been an increasing interest in vibration control in recent years. This is due to demands for mechanical structures to be lighter and faster. Lighter and faster structures are more prone to vibrations. Hence, there is an imperative need for practical solutions to vibration problems in complex practical mechanical systems. Regardless of the complexity of a structure, from wave vibration standpoint, it consists of only two basic types of structural components, namely, structural elements and structural joints. In this paper, a control strategy is developed for controlling vibrations flowing from one structural element to another through the structural joint. An L-shaped beam is studied as an example structure. Numerical results are given.

STRUCTURAL RELIABILITY ANALYSIS BASED ON P-BOXES

2020 ◽  
Vol 92 (6) ◽  
pp. 51-58
Author(s):  
S.A. SOLOVYEV ◽  
Keyword(s):  
Probability Distribution ◽  
Reliability Analysis ◽  
Structural Reliability ◽  
Epistemic Uncertainty ◽  
Random Variable ◽  
Strength Criterion ◽  
Structural Elements ◽  
Structural Element ◽  
Limit States ◽  
Distribution Shape

The article describes a method for reliability (probability of non-failure) analysis of structural elements based on p-boxes. An algorithm for constructing two p-blocks is shown. First p-box is used in the absence of information about the probability distribution shape of a random variable. Second p-box is used for a certain probability distribution function but with inaccurate (interval) function parameters. The algorithm for reliability analysis is presented on a numerical example of the reliability analysis for a flexural wooden beam by wood strength criterion. The result of the reliability analysis is an interval of the non-failure probability boundaries. Recommendations are given for narrowing the reliability boundaries which can reduce epistemic uncertainty. On the basis of the proposed approach, particular methods for reliability analysis for any structural elements can be developed. Design equations are given for a comprehensive assessment of the structural element reliability as a system taking into account all the criteria of limit states.

scholarly journals Inelastic displacement ratios for non-structural components in steel framed structures under forward-directivity near-fault strong-ground motion

2021 ◽  
Author(s):  
M. A. Bravo-Haro ◽  
J. R. Virreira ◽  
A. Y. Elghazouli
Keyword(s):  
Strong Ground Motion ◽  
Ground Motions ◽  
Structural Elements ◽  
Structural Components ◽  
Framed Structures ◽  
Inelastic Displacement ◽  
Near Fault ◽  
Forward Directivity ◽  
The Mean ◽  
Strong Ground

AbstractThis paper describes a detailed numerical investigation into the inelastic displacement ratios of non-structural components mounted within multi-storey steel framed buildings and subjected to ground motions with forward-directivity features which are typical of near-fault events. The study is carried out using detailed multi-degree-of-freedom models of 54 primary steel buildings with different structural characteristics. In conjunction with this, 80 secondary non-structural elements are modelled as single-degree-of-freedom systems and placed at every floor within the primary framed structures, then subsequently analysed through extensive dynamic analysis. The influence of ground motions with forward-directivity effects on the mean response of the inelastic displacement ratios of non-structural components are compared to the results obtained from a reference set of strong-ground motion records representing far-field events. It is shown that the mean demand under near-fault records can be over twice as large as that due to far-fault counterparts, particularly for non-structural components with periods of vibration lower than the fundamental period of the primary building. Based on the results, a prediction model for estimating the inelastic displacement ratios of non-structural components is calibrated for far-field records and near-fault records with directivity features. The model is valid for a wide range of secondary non-structural periods and primary building fundamental periods, as well as for various levels of inelasticity induced within the secondary non-structural elements.

scholarly journals Value Orientations in Education System: Approach, Interpretation, and Formation

2022 ◽  
Author(s):  
Diana Antoci ◽  
Keyword(s):  
Young People ◽  
Theoretical Study ◽  
Value Orientation ◽  
Value Orientations ◽  
Emotional States ◽  
Structural Elements ◽  
Structural Components ◽  
Pedagogical Model ◽  
Constitutive Components ◽  
Development And Validation

The implemented theoretical study has revealed various scientific positions aimed at: interpreting the concepts of value and value orientation; finding controversial positions and affinities in the use of “value” and “value orientation” concepts; identifyingambiguous positions on structural elements of value orientation and value formation mechanism. The purpose of undertakenresearch was theoretical, experimental and methodological in nature, outlining formation of value orientations in adolescence and youth ages.The developed definitions and determined structural components of value orientations allowed initiation of an experimental investigation of value orientations in adolescents and young people through which interrelation between the constitutive components of value orientation was confirmed, the specifics of values in adolescents and young people was emphasized. Outlining the specifics of value orientation structure led to identification of criteria, indicators and descriptors and to development and validation of a Questionnaire for Value Orientation Assessment. The results of experimental study laid the basis for development and recognition of a Pedagogical Model for formation of value orientations in adolescents and young people. The previously identified mechanism for formation of values and functioning of value orientations was transposed into the nucleus of the Pedagogical Model, which included the following components: behaviour, emotional states, attitudes, convictions, and values. In order to identify the methodology for forming value orientations in the formal, informal and non-formal educational environment, the principles of humanistic, constructivist and cognitivist education, strategies, conditions were highlighted, which ensure a dynamic progress in general development of the personality, implicitly of value orientations, and which is taken into account in framework ofa formative experiment.The data obtained from the validation of the developed Pedagogical Model confirmed its effectiveness and proved that it was a multidimensional one, which could be of great benefit to specialists in the field of Education Sciences and teachers from schools and higher educationalinstitutions.

scholarly journals Structural vehicle impact loading

2013 ◽  
Vol 11 (3) ◽  
pp. 285-292
Author(s):  
Dragoslav Stojic ◽  
Stefan Conic
Keyword(s):  
Impact Analysis ◽  
Impact Loads ◽  
Structural Elements ◽  
Structural Element ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Vehicle Impact ◽  
Dynamic Forces ◽  
Force Intensity

In contemporary design, vehicle impact into the structures is paid great attention since they can be dominant, depending on the type of structure. The key issue in the vehicle impact analysis is the proper determination of intensity and way of action of dynamic forces on the structural element and its behavior after the imparted load. The Eurocodes, in the annexes provide recommendations for determination of force intensity depending on mass and velocity of the colliding vehicle. Equivalent static loads causing approximate effects on the structural elements are used as quite approximate and efficient methods. The paper comprises the analysis of deformation of columns having the same characteristics, exposed to impact loads via the equivalent static loads, depending on the stress state in columns, and a comparative analysis has been done.

scholarly journals Emerging trends in vibration control of wind turbines: a focus on a dual control strategy

2015 ◽  
Vol 373 (2035) ◽  
pp. 20140069 ◽  
Author(s):  
Andrea Staino ◽  
Biswajit Basu
Keyword(s):  
Vibration Control ◽  
Wind Turbines ◽  
Control Strategy ◽  
Offshore Wind ◽  
Structural Vibration ◽  
Offshore Wind Turbine ◽  
Dual Control ◽  
Pitch Control ◽  
Emerging Trends ◽  
Control Schemes

The paper discusses some of the recent developments in vibration control strategies for wind turbines, and in this context proposes a new dual control strategy based on the combination and modification of two recently proposed control schemes. Emerging trends in the vibration control of both onshore and offshore wind turbines are presented. Passive, active and semi-active structural vibration control algorithms have been reviewed. Of the existing controllers, two control schemes, active pitch control and active tendon control, have been discussed in detail. The proposed new control scheme is a merger of active tendon control with passive pitch control, and is designed using a Pareto-optimal problem formulation. This combination of controllers is the cornerstone of a dual strategy with the feature of decoupling vibration control from optimal power control as one of its main advantages, in addition to reducing the burden on the pitch demand. This dual control strategy will bring in major benefits to the design of modern wind turbines and is expected to play a significant role in the advancement of offshore wind turbine technologies.

Solution of Dynamic Problems of Structural Elements Using Simple Polynomial Approximations

1991 ◽  
Author(s):  
Patricio A. A. Laura
Keyword(s):  
Orthogonal Polynomials ◽  
Optimization Procedure ◽  
Structural Elements ◽  
Dynamic Problems ◽  
Structural Element ◽  
Base Function ◽  
Polynomial Approximations ◽  
Deformable Bodies ◽  
Rational Procedure ◽  
Coordinate Functions

Abstract A survey of studies dealing with vibrating structural elements using simple polynomial approximations in connection with Rayleigh-Ritz or Galerkin-type methods is presented. The classical use of polynomials when solving dynamic problems of deformable bodies consists of constructing a set of coordinate functions in such a way that they satisfy at least the essential boundary conditions and that they represent “reasonably well” the deformation field of the structural element under study. An alternative and more rational procedure has been developed and used in recent years whereby orthogonal polynomials are used. A “base function” is constructed and then one generates a set of orthogonal polynomials using the Gram-Schmidt or equivalent procedure. The present paper presents comparisons of numerical results in the case of different types of vibrating structural elements Special emphasis is placed on Rayleigh’s optimization procedure which consists of taking one of the exponents of the polynomial coordinate functions as an optimization parameter “γ”. Since the calculated eigenvalues constitute upper bounds, by minimizing them with respect to “γ” one is able to optimize the eigenvalues.

scholarly journals Fish densities associated with structural elements of oil and gas platforms in southern California

2019 ◽  
Vol 95 (4) ◽  
pp. 639-656 ◽  
Author(s):  
Erin L Meyer-Gutbrod ◽  
Li Kui ◽  
Mary M Nishimoto ◽  
Milton S Love ◽  
Donna M Schroeder ◽  
...  
Keyword(s):  
Habitat Use ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Artificial Reef ◽  
Offshore Structures ◽  
Structural Elements ◽  
Structural Element ◽  
Young Of The Year

There are thousands of offshore oil and gas platforms worldwide that will eventually become obsolete, and one popular decommissioning alternative is the "rigs to reefs" conversion that designates all or a portion of the underwater infrastructure as an artificial reef, thereby reducing the burden of infrastructure removal. The unique architecture of each platform may influence the size and structure of the associated fish assemblage if different structural elements form distinct habitats for fishes. Using scuba survey data from 11 southern California platforms from 1995 to 2000, we examined fish assemblages associated with structural elements of the structure, including the major horizontal crossbeams outside of the jacket, vertical jacket legs, and horizontal crossbeams that span the jacket interior. Patterns of habitat association were examined among three depth zones: shallow (<16.8 m), midwater (16.8–26 m), and deep (>26 m); and between two life stages: young- of-the-year and non-young-of-the-year. Fish densities tended to be greatest along horizontal beams spanning the jacket interior, relative to either horizontal or vertical beams along the jacket exterior, indicating that the position of the habitat within the overall structure is an important characteristic affecting fish habitat use. Fish densities were also higher in transects centered directly over a vertical or horizontal beam relative to transects that did not contain a structural element. These results contribute to the understanding of fish habitat use on existing artificial reefs, and can inform platform decommissioning decisions as well as the design of new offshore structures intended to increase fish production.

Crystal structure of coalingite

1971 ◽  
Vol 38 (295) ◽  
pp. 286-294 ◽  
Author(s):  
J. Pastor-Rodriguez ◽  
H. F. W. Taylor
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Water Molecules ◽  
Structural Elements ◽  
Structural Element ◽  
X Ray ◽  
Octahedral Sites ◽  
Carbonate Ions ◽  
Disordered Layer ◽  
Ray Methods

SummaryThe crystal structure of coalingite (Mg10Fe2(OH)24(CO3)·2H2O) has been determined using single-crystal X-ray methods. The mineral is trigonal, with space group Rm, aH = 3·12, cH = 37·4 Å, Z = ½, and (0001) cleavage. The structure is of a layer type, and is based on a structural element about 12·5 Å thick in the c-direction and consisting of two brucite-like layers and one disordered layer containing carbonate ions and water molecules and resembling those in sjögrenite and pyroaurite. The unit cell comprises three of these structural elements stacked together in the c-direction. The Mg2+ and Fe3+ ions are randomly distributed among all the octahedral sites of the brucite-like layers. The structure closely resembles those of sjögrenite and pyroaurite, but has two brucite-like layers between each CO32−−H2O layer where these have one. There is a tendency to random interstratification, and the crystals appear to contain intergrown regions of brucite and of sjögrenite or pyroaurite. Coalingite-K probably has a similar structure, but with three brucite-like layers between each -H2O layer; its idealized formula is probably Mg16Fe2(OH)36(CO3).2H2O.

Hybrid Analytical Analysis in the Design of Mechatronic Systems

2015 ◽  
Vol 762 ◽  
pp. 243-248 ◽  
Author(s):  
Olimpiu Hancu ◽  
Mihaela Simion ◽  
Ciprian Lăpuşan
Keyword(s):  
Structural Analysis ◽  
Motion Analysis ◽  
Control Strategy ◽  
Mechatronic System ◽  
Hybrid Analysis ◽  
Structural Element ◽  
Mechatronic Systems ◽  
Resources Management ◽  
Optimal Approach ◽  
Multiple Task

Coupling the structural analysis with the motion analysis in one simulation (hybrid analysis) provides an important mechanism which allows an integrated and optimal approach in the design of mechatronic systems. Such a procedure which includes Matlab/Simulink calculus and visualization of main efforts variation in each structural element of a robot during an entire operational task, allowing coupling structural analysis with motion analysis and testing the virtual prototype on multiple task scenarios is detailed in this paper. Also, the utility of this analysis (information) and ways to improving the control strategy for resources management of an intelligent mechatronic system are emphasized.

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