Synthesis of Dynamical Structure of the Hydraulic Breaker With a Vibration-Free Handle

2007 ◽  
Author(s):  
I. J. Sokolov ◽  
V. I. Babitsky ◽  
N. A. Halliwell
Keyword(s):  
Dynamic Structure ◽  
Dynamical Structure ◽  
Optimal Regime ◽  
Hydraulic Power ◽  
New Approach ◽  
Optimal Dynamic ◽  
Proper Modification ◽  
Effective Use ◽  
Multi Body ◽  
Percussion Machine

An approach to the synthesis of a dynamical structure of the hand-held percussion machine with a vibration-free handle is presented. This is based on the consideration of the optimal dynamic conversion of energy in hand-held percussion machines founded as a solution of the equivalent problem of the optimal control [1]. For an accomplishment of the optimal regime a proper dynamic structure of the percussion machine as a multi-body vibro-impact system with one body (casing/handle) being free of vibration is found and investigated. Computer simulations and initial experiments validated the new approach. The main feature of the proposed design realising the synthesised structure is the use of a mechanism with zero differential stiffness. A hydro-pneumatic unit with zero stiffness was developed and tested. Theoretical recommendations have been applied to a commercial hydraulic breaker. A proper modification of the design and effective use of existing hydraulic power source provided a significant improvement in performance.

scholarly journals Hydrodynamic Analysis of Self-Propulsion Performance of Wave-Driven Catamaran

2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Weixin Zhang ◽  
Ye Li ◽  
Yulei Liao ◽  
Qi Jia ◽  
Kaiwen Pan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Dynamic Model ◽  
Dynamic Structure ◽  
Ocean Waves ◽  
Static State ◽  
Small Surface ◽  
Propulsion Performance ◽  
Multi Body ◽  
Body Dynamic

The wave-driven catamaran is a small surface vehicle driven by ocean waves. It consists of a hull and hydrofoils, and has a multi-body dynamic structure. The process of moving from static state to autonomous navigation driven by ocean waves is called “self-propulsion”, and reflects the ability of the wave-driven catamaran to absorb oceanic wave energy. Considering the importance of the design of the wave-driven catamaran, its self-propulsion performance should be comprehensively analysed. However, the wave-driven catamaran’s multi-body dynamic structure, unpredictable dynamic and kinematic responses driven by waves make it difficult to analyse its self-propulsion performance. In this paper, firstly, a multi-body dynamic model is established for wave-driven catamaran. Secondly, a two-phase numerical flow field containing water and air is established. Thirdly, a numerical simulation method for the self-propulsion process of the wave-driven catamaran is proposed by combining the multi-body dynamic model with a numerical flow field. Through numerical simulation, the hydrodynamic response, including the thrust of the hydrofoils, the resistance of the hull and the sailing velocity of the wave-driven catamaran are identified and comprehensively analysed. Lastly, the accuracy of the numerical simulation results is verified through a self-propulsion test in a towing tank. In contrast with previous research, this method combines multi-body dynamics with computational fluid dynamics (CFD) to avoid errors caused by artificially setting the motion mode of the catamaran, and calculates the real velocity of the catamaran.

scholarly journals Currency Risk Hedging With Time-Varying Correlations

2011 ◽  
Vol 1 (4) ◽  
Author(s):  
Binbin Guo
Keyword(s):  
Foreign Currency ◽  
Dynamic Structure ◽  
Multivariate Garch ◽  
Time Varying ◽  
Currency Risk ◽  
Risk Hedging ◽  
Hedging Strategies ◽  
Multivariate Garch Model ◽  
The Us ◽  
Optimal Dynamic

<p class="MsoNormal" style="text-align: justify; margin: 0in 0.5in 0pt;"><span style="font-family: Times New Roman; font-size: x-small;">This paper studies currency risk hedge when volatilities and correlations of forward currency contracts and underlying assets returns are all time-varying.<span style="mso-spacerun: yes;">&nbsp; </span>A multivariate GARCH model with time-varying correlations is adopted to fit the dynamic structure of the conditional volatilities and correlations. The conditional risk-minimizing hedge strategies are estimated for an international portfolio of the US, UK and Switzerland stocks, for the period of February of 1973 to March of 2002. The empirical results show that the optimal dynamic hedging strategies can capture partially the currency fluctuations, and greatly reduce the currency risk and enhance the risk-adjusted returns of the portfolio with significant foreign currency exposures. </span></p>

NEW APPROACH TO THE DISTRIBUTION OF COURT COSTS IN CASES OF CHALLENGING THE RESULTS OF DETERMINING THE CADASTRAL VALUE

2021 ◽  
Vol 11 (2) ◽  
pp. 188-204
Author(s):  
D.G. FILCHENKO ◽  
I.G. FILCHENKO
Keyword(s):  
Dispute Settlement ◽  
Civil Law ◽  
Practical Interest ◽  
Civil Procedure ◽  
Main Role ◽  
New Approach ◽  
Effective System ◽  
Effective Use

This study is determined by the theoretical and practical interest in the study of issues related to the protection of the rights of participants in transport obligations. The need for research is dictated by the direct needs of the subjects of the relevant legal relations in the actual exercise of rights, as well as in connection with the search for the most effective use of existing civil law forms of protection of violated rights of participants in transport obligations. Turning to general theoretical problems, in particular, to the concept of protection of rights, it is concluded that this is common to civil law and civil procedure. The authors state that the specifics of transport obligations determine the specifics of protecting the rights of their participants, where the main role is given to the non-jurisdictional form of protection. The authors pay special attention to the claims procedure for dispute settlement, supporting the position that this procedure is inter-industry in nature. At the same time, it is proposed to use other conciliation procedures along with the claim procedure (or after) before applying to the court, which, in turn, according to the authors, will allow building an effective system for protecting the violated rights of participants in transport obligations.

New Approach of Pressure Losses in Hydraulic Power Systems

2021 ◽  
Author(s):  
Carmen-Anca Safta ◽  
Sanda-Carmen Georgescu ◽  
Liliana Dumitrescu
Keyword(s):  
Power Systems ◽  
Hydraulic Power ◽  
New Approach ◽  
Pressure Losses

Control of the stroke of hydraulic cylinders in hydraulic lifting mechanisms of installation equipment

2021 ◽  
Author(s):  
B.M. Novozhilov
Keyword(s):  
Angular Displacement ◽  
Hydraulic Cylinder ◽  
Mutual Position ◽  
Launch Vehicles ◽  
Hydraulic Power ◽  
Correct Operation ◽  
New Approach ◽  
Displacement Sensors ◽  
Urgent Task ◽  
Angular Coordinates

For the correct operation of hydraulic lifting mechanisms of the installation equipment of rocket and space complexes, it is necessary to ensure the synchronous movement of the rods of hydraulic power cylinders operating in parallel when performing working operations. Therefore, the urgent task is to develop synchronization systems that, along with ensuring the consistency of travel speeds, also provide the consistency of the mutual position of hydraulic cylinder rods. To solve this problem, we introduce a new approach which makes use of indirect methods for determining the working stroke of hydraulic power cylinders according to the results of measuring the angular or linear coordinates of the power elements of the mechanism. The first method is based on measuring the angular coordinates of the power elements of the lifting mechanism using angular displacement sensors - angular encoders. As for the second method, it relies on measuring the stroke of an additional link of variable length by means of magnetostrictive and cable linear position sensors. The paper briefly describes the device and the principle of operation of the sensors, and gives recommendations for the construction of measuring transducers as part of the lifting mechanism of the installation equipment. The new approach to solving the problem of controlling the stroke of hydraulic power cylinders in lifting mechanisms can be used in the development of advanced installation equipment for launch vehicles of heavy and superheavy classes.

Stochastic Multi-Objective Optimisation of a Gearbox Synchroniser and Selector Mechanism

2003 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Giampiero Mastinu ◽  
Massimo Caudano
Keyword(s):  
System Model ◽  
Objective Functions ◽  
Performance Indices ◽  
Global Approximation ◽  
Stochastic Perturbations ◽  
New Approach ◽  
Multi Objective ◽  
Design Solutions ◽  
Shift Action ◽  
Multi Body

In the paper a new approach is presented for the design of the synchroniser and selector mechanism of a road vehicle gearbox. The main aim is to improve shiftability and driver comfort. The new approach is based not only on the theory of multi-objective optimisation but also on robust design. A multi-body physical system model of the synchroniser and selector mechanism has been developed and vaildated experimentally. The physical model is stochastic being many of the system parameters defined by stochastic processes. The fifty-eight parameters of the system model have been tuned in order to achieve the desired dynamic behaviour of the synchroniser and selector mechanism during a reference shift action, defined by nine performance indices. The new approach is characterised both by the optimisation of the objective functions (corresponding to system performance indices) and by the reduction (or minimisation) of the sensitivity (variance) of the performance indices to stochastic perturbations. Such variances are computed (very quickly) by means of an original procedure based on the global approximation of the objective functions. Additionally, with respect to the mentioned features, the new approach is based on both a special study to explore all of the feasible design solutions, and on a global sensitivity procedure to analyse (in a stochastic context) the influence of each design variable on each objective function. Pareto-optimal design solutions for different levels of “robustness” have been computed in a very short time. The optimisation method has been applied with successful results. A number of optimised synchronisers and selector mechanisms have been defined, all of them featuring relevant improvements in terms of performance and robustness with respect to the reference system, already effective and under production.

A New Approach to Effective Use of Design Rationale in Practice

2003 ◽  
Vol 9 (2) ◽  
pp. 62-69 ◽  
Author(s):  
Jeffrey M. Molavi ◽  
Raymond McCall ◽  
Anthony Songer
Keyword(s):  
Design Rationale ◽  
New Approach ◽  
Effective Use

Generalized Vector-Network Formulation for the Dynamic Simulation of Multibody Systems

1986 ◽  
Vol 108 (4) ◽  
pp. 322-329 ◽  
Author(s):  
M. J. Richard ◽  
R. Anderson ◽  
G. C. Andrews
Keyword(s):  
Multibody Systems ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Rigid Bodies ◽  
New Approach ◽  
System Description ◽  
Nonlinear Equations Of Motion ◽  
Systematic Formulation ◽  
Multi Body ◽  
Entire Procedure

This paper describes the vector-network approach which is a comprehensive mathematical model for the systematic formulation of the nonlinear equations of motion of dynamic three-dimensional constrained multi-body systems. The entire procedure is a basic application of concepts of graph theory in which laws of vector dynamics have been combined. The main concepts of the method have been explained in previous publications but the work described herein is an appreciable extension of this relatively new approach. The method casts simultaneously the three-dimensional inertia equations associated with each rigid body and the geometrical expressions corresponding to the kinematic restrictions into a symmetrical format yielding the differential equations governing the motion of the system. The algorithm is eminently well suited for the computer-aided simulation of arbitrary interconnected rigid bodies; it serves as the basis for a “self-formulating” computer program which can simulate the response of a dynamic system, given only the system description.

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