Suppression of Crane-Load Oscillations Using Shape-Controlled Mechanical Filters

In the present study, control of ship board crane-load oscillations using a shape-controlled mechanical filter is investigated. The pivot point about which the load oscillations occur is constrained to follow an actively controlled surface, which is referred to as the mechanical filter. Planar load oscillations in the presence of ship roll motions are considered, and a nonlinear system with nonautonomous terms is used to describe the motions. For the case without shape control, it is shown that with only state feedback applied to the pivot point, it is not possible to stabilize the equilibrium position (i.e., absence of load oscillations and pivot motions). In the presence of shape control, it is shown that it is possible to have an equilibrium position even in the presence of persistent disturbances. A Lyapunov function-based analysis conducted to gain insight into the system dynamics is also presented. Through numerical simulations, it is verified that the equilibrium position is stable over a range of excitation frequencies. Efforts undertaken to examine the system dynamics in the presence of both state feedback applied to the pivot and shape control are also discussed.

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A Mechanical Filter Concept to Suppress Crane Load Oscillations

Volume 1D: 16th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc97/vib-4091 ◽

1997 ◽

Author(s):

B. Balachandran ◽

Y.-Y. Li

Keyword(s):

Nonlinear Dynamics ◽

Dynamical Systems ◽

Control Parameters ◽

Pivot Point ◽

Preliminary Results ◽

Scalar Control ◽

Load Response ◽

Mechanical Filter ◽

Circular Track ◽

Ship Roll

Abstract In this article, preliminary results obtained in the exploration of a mechanical filter concept for suppressing crane-load oscillations on a ship vessel are presented. The pivot point about which the load oscillates is constrained to follow a circular track in the considered filter. The governing dynamical systems for the cases with and without the filter are presented, and the nonlinear dynamics of these systems is studied with respect to quasi-static variation of different scalar control parameters. It is shown that the presence of the filter helps in eliminating some of the sub-critical bifurcations that may arise in the crane-load response during periodic ship-roll excitations.

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Synthesis of Platinum Nanocrystals within Iodine Ions Mediated

Journal of Nanomaterials ◽

10.1155/2018/1465760 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Jiamao Li ◽

Jingwei Hou ◽

Yu Gong ◽

Chengjian Xiao ◽

Lei Yue ◽

...

Keyword(s):

Shape Control ◽

Growth Process ◽

Growth Stage ◽

Nucleation Stage ◽

Platinum Nanocrystals ◽

High Resolution Tem ◽

Pt Nanocrystals ◽

High Concentrations ◽

Insight Into

A liquid-phase reducing method of synthesizing Pt nanocrystals was demonstrated, and dendrite-, cube-, and cuboctahedron-shaped Pt nanocrystals (NCs) with well-defined monomorphic were successfully synthesized through iodine ions mediated with the CTAB agent. When the KI concentration was increased to thirty times of K2PtCl4 at the nucleation stage, the high-quality Pt nanodendrites could be obtained. However, no matter how many KI were added at the growth age, only cube- and cuboctahedron-shaped Pt nanocrystals formed. The results of high-resolution TEM, EDX, and XRD indicated that the size and shape of Pt NCs could be turned by changing the concentration and time of KI. In the nucleation stage, it might be due to that some iodine ions adsorb on the surfaces of Pt NCs, which probably cause the rapid growth process resulting in the formation of Pt nanodendrites. In the growth stage, although high concentrations of I− ions could contribute to the shape control and generate bigger particles of Pt NCs, small Pt particles do not grow into dendrites. The insight into the role of I− ions in synthesis of Pt NCs reported here provided a viewpoint for clearly understanding the formation mechanism of anisotropic platinum nanostructures.

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Open Systems Formulation and Gaining Insight Using Lagrangian Bond Graphs

10.1115/imece2000-2371 ◽

2000 ◽

Author(s):

Robin C. Redfield

Keyword(s):

System Dynamics ◽

Open Systems ◽

Classical Method ◽

System Modeling ◽

Bond Graph ◽

Small Scale ◽

Bond Graphs ◽

Model Modification ◽

System Equations ◽

Insight Into

Abstract Models of a small-scale water rocket are developed as an example of open system modeling by both the bond graph approach and a more classical method. One goal of the development is to determine the benefits of the bond graph approach into affording insight into the system dynamics. Both modeling approaches yield equivalent differential equations as they should, while the bond graph approach yields significantly more insight into the system dynamics. If a modeling goal is to simply find the system equations and predict behavior, the classical approach may be more expeditious. If insight and ease of model modification are desired, the bond graph technique is probably the better choice. But then you have to learn it!

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Geometric performance parameters of three-point hitch linkage system of a 2WD Indian tractor

Research in Agricultural Engineering ◽

10.17221/79/2012-rae ◽

2016 ◽

Vol 61 (No. 1) ◽

pp. 47-53 ◽

Cited By ~ 2

Author(s):

G.V. Kumar Prasanna

Keyword(s):

Linkage Analysis ◽

Rear Axle ◽

Performance Parameters ◽

Effective Utilization ◽

Pivot Point ◽

Wheel Drive ◽

Weight Transfer ◽

Insight Into

Geometric performance parameters of three-point hitch system of a most sold model of a 2-wheel drive Indian tractor were determined by generating the path of upper and lower hitch points by kinematic linkage analysis. At various locations of pivot point of upper link and adjustments in the length of lift rods, hitch linkage system of the tractor fulfilled all the requirements specified by the standards for category-I and II hitches. An insight into the kinematic linkage analysis revealed that the hitch linkage of the selected tractor is the most suitable for operations with soil working implements. Attachment of upper link to the topmost pivot point reduced the change in orientation of implement during lifting and ensured better weight transfer from implement to the rear axle of tractor. The kinematic linkage analysis has the potential to identify the best settings of the hitch linkage system for the effective utilization of tractor power during various farm operations.

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Nonlinear Deflection Model for Corner-Supported, Thin Laminates Shape-Controlled With Moment Actuators

Volume 10: Mechanics of Solids and Structures, Parts A and B ◽

10.1115/imece2007-43069 ◽

2007 ◽

Author(s):

Jordan E. Massad ◽

Pavel M. Chaplya ◽

Jeffrey W. Martin ◽

Philip L. Reu ◽

Hartono Sumali

Keyword(s):

Shape Control ◽

Large Deflection ◽

Flexible Structures ◽

Piezoelectric Actuators ◽

Input Voltage ◽

Thin Plates ◽

Small Deflection ◽

Shape Controlled ◽

Rectangular Laminate ◽

Small Deformations

The shape control of thin, flexible structures has been studied primarily for edge-supported thin-plates. For applications such as electromagnetic wave reflectors, corner-supported configurations may prove more applicable since they allow for greater flexibility and larger achievable deflections when compared to edge-supported geometries under similar actuation conditions. Models of such structures provide insight for effective, realizable designs, enable design optimization, and provide a means of active shape control. Models for small deformations of corner-supported, thin laminates actuated by integrated piezoelectric actuators have been developed. However, membrane deflections expected for nominal actuation exceed those stipulated by linear, small deflection theories. In addition, large deflection models have been developed for membranes; however these models are not formulated for shape control. This paper extends a previously-developed linear model for a corner-supported thin, rectangular laminate to a more general large deflection model for a clamped-corner laminate composed of moment actuators and an array of actuating electrodes. First, a nonlinear model determining the deflected shape of a laminate given a distribution of actuation voltages is derived. Second, a technique is employed to formulate the model as a map between input voltage and deflection alone, making it suitable for shape control. Finally, comparisons of simulated deflections with measured deflections of a fabricated active laminate are investigated.

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Shape-Controlled Synthesis of Copper Indium Sulfide Nanostructures: Flowers, Platelets and Spheres

Nanomaterials ◽

10.3390/nano9121779 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1779

Author(s):

Jiajia Ning ◽

Stephen V. Kershaw ◽

Andrey L. Rogach

Keyword(s):

Shape Control ◽

Three Dimensional ◽

Semiconductor Nanostructures ◽

Sulfur Source ◽

Controlled Synthesis ◽

Indium Sulfide ◽

Copper Indium ◽

Series Of Experiments ◽

Shape Controlled ◽

Intermediate Amount

Colloidal semiconductor nanostructures have been widely investigated for several applications, which rely not only on their size but also on shape control. CuInS2 (often abbreviated as CIS) nanostructures have been considered as candidates for solar energy conversion. In this work, three-dimensional (3D) colloidal CIS nanoflowers and nanospheres and two-dimensional (2D) nanoplatelets were selectively synthesized by changing the amount of a sulfur precursor (tert-dodecanethiol) serving both as a sulfur source and as a co-ligand. Monodisperse CIS nanoflowers (~15 nm) were formed via the aggregation of smaller CIS nanoparticles when the amount of tert-dodecanethiol used in reaction was low enough, which changed towards the formation of larger (70 nm) CIS nanospheres when it significantly increased. Both of these structures crystallized in a chalcopyrite CIS phase. Using an intermediate amount of tert-dodecanethiol, 2D nanoplatelets were obtained, 90 nm in length, 25 nm in width and the thickness of a few nanometers along the a-axis of the wurtzite CIS phase. Based on a series of experiments which employed mixtures of tert-dodecanethiol and 1-dodecanethiol, a ligand-controlled mechanism is proposed to explain the manifold range of the resulting shapes and crystal phases of CIS nanostructures.

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Life Settlement Value Profiles across Different Death Rate Distributions

The Journal of Structured Finance ◽

10.3905/jsf.2018.24.3.100 ◽

2018 ◽

Keyword(s):

Death Rate ◽

Cost Of Capital ◽

Mortality Rates ◽

Cash Flows ◽

Pivot Point ◽

Specific Cost ◽

Fund Managers ◽

Life Settlements ◽

Asset Class ◽

Insight Into

The life settlement asset class is a recognized part of the alternative investment market. Our article offers insight into the behavior of portfolios of life settlement contracts. We focus on the value profiles of pools of life settlement contracts in the value/cost of capital space. A pool of life settlement contracts has a death rate distribution that will determine the amount of premiums that must be paid each period and the amount of death benefits that will be collected each period. Because value is determined by the timing, magnitude, and certainty of the cash flows generated by an asset, it is inexorably linked to the timing of the life settlers’ deaths. We show that when certain conditions are met, pools with fundamentally different underlying mortality rates and risk profiles, but with the same cost of capital, can have the same value (pivot point in the value/cost of capital space). This pivot point can be useful for fund managers seeking to modify a portfolio of life settlements under a specific cost-of-capital constraint.

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EUREKA

International Journal of System Dynamics Applications ◽

10.4018/ijsda.2012070105 ◽

2012 ◽

Vol 1 (3) ◽

pp. 139-177 ◽

Cited By ~ 1

Author(s):

Tarek K. Abdel-Hamid

Keyword(s):

System Dynamics ◽

Energy Regulation ◽

Nonlinear Feedback ◽

Feedback Systems ◽

Baseline Model ◽

Treatment And Prevention ◽

Human Energy ◽

Research Findings ◽

Dynamics Models ◽

Insight Into

Recent research findings reveal that human bioenergetics belongs to the class of multi-loop nonlinear feedback systems—the same class of systems that system dynamics aims to study. In this paper the author aims to demonstrate the utility of utilizing simple—bathtub like—system dynamics models to gain insight into human weight and energy regulation and (in the process) help debunk widespread misconceptions that are hindering prevention and treatment efforts. Specifically, the author presents a series of models, starting with one that captures conventional wisdom about human energy regulation. This baseline model is critiqued and its limitations—and pitfalls—exposed through model experimentation. The model is then incrementally refined in a spiral of modeling-experimentation-learning steps, to arrive at a structure that integrates emerging (advanced) conceptualization(s) of human weight/energy regulation. In the concluding section, the author builds upon the insights gained from this modeling exercise to propose recommendations for obesity treatment and prevention.

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