Sharif Digital Repository

In this paper the principles of submarine dynamics modeling have been gathered as distinguished steps. Of course, in these few pages the details cannot be discussed and the formulae cannot be proved. The interested reader has to study more detailed references to attain a better perception of the subject. The paper, in addition to gathering and editing principles, has gone through offering simplifications in each part of modeling. Such simplifications will result in a good approximation of submarine dynamic behavior, which is exactly complicated in reality. In higher levels of modeling each part can be completed and details can be processed  

During voluntary flexion/extension of the head-neck system, the cervical spine undergoes a stepwise motion from upper to lower regions with a specific pattern. The motion of each vertebra is composed of a translation and rotation with respect to lower vertebrae, which may be considered as an absolute rotation about an axis called instantaneous axis of rotation (IAR). The location of this axis is different between normal and degenerated spines. A biomechanical computer model of the head and cervical vertebrae, including eight separate rigid links and nine spinal muscles as actuating elements was developed to evaluate and compare inter-segmental force-moments and muscle forces in normal,... 

Humanoid robots have recently been the subject of many new and interesting fields both in robotics research and industry. The wide variety of their applications in civic and hostile environments demand developing approperiate theoretical models for analysis. A dynamical model was developed to study the human jumping process, and the effect of factors like joint speeds and hand motion in jumping. An experiment was designed and setup to compare the theoretical model with experimental observations. Time histories of vertical force, mass center velocity and driving torques were also obtained. Using dynamical equations, the effect of joint speeds on the maximum values of these quantities is... 

Shape Memory Alloys (SMA's) are inherently non-linear devices exhibiting significant hysteresis in their stress-strain-temperature characteristic. We have used the variable sub-layer SMA model of Ikuta [3] to extract the advanced dynamic model of our proposed varying stress SMA actuator. A nonlinear finite element analysis was used to model the proposed bending spring in the actuator and the extended variable sub-layer model of Ikuta was considered to extract stress-displacement relations. Finally, these two models are combined with thermo dynamic model of SMA and a schematic flowchart is proposed to calculate SMA resultant strain under an arbitrary current input. At the end, we applied this... 

Achievement of industries in production and offering products depends on different factors like having an appropriate maintenance system. This issue should be reached through the most appropriate and practical methods. In this study, based on how the external parameters would influence the productivity of a maintenance system the researcher aims at designing a dynamic system model to analyze the productivity of a maintenance system using acquired information from a car device company by determination of the percentage of parameters and indexes and their influence on maintenance system productivity. The proposed model is simulated for a system with parameters of precise value according to... 

In this paper, a comprehensive model is used to describe dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton’s principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. Comparison between the modeling results and available experimental data shows that this model is very effective in predicting some design objectives such as step size and output force for this type of actuators  

This paper discusses the identification process of engine dynamics and presents derived transfer function models including; thrust, shaft speed, compressor exit pressure and turbine exit temperature in relation to the fuel flow. Model identification approach, presented in this paper, is the first to consider frequency-sweep signals to excite dynamics, as well as to utilise windowing and smoothing techniques to reduce random errors in the spectral estimates. Here, frequency sweep provides a fairly uniform spectral excitation and chirp-z transform warrants the exact determination of the frequency responses that are robust to the uncertainties. The identified models are also validated with the... 

Choreography description languages aim at specifying from a global point of view interactions among a set of services involved in a new system. From this specification, local implementations or peers can be automatically generated. Generation of peers that precisely implement the choreography specification is not always possible: This problem is known as realizability. When peers corresponding to this specification are being executed we may want to modify the choreography specification and reconfigure dynamically the system. This is the case for instance if we add or remove interactions due to the addition of functionalities to the system at hand or the loss of a service. In this article, we... 

In this paper, the thermo-dynamic analysis of contact-impact problem is presented in the large deformation of hyperelastic material based on the Taylor-Galerkin method. The technique is applied for the time domain discretization of thermo-dynamic governing equations in the advection-diffusion problems. The impenetrability condition and frictional contact constraints are fulfilled by imposing the augmented-Lagrange technique for nonmatching contact surfaces. The Taylor-Galerkin method is employed to describe the advection-diffusion effect in the numerical solution of parabolic equation of unsteady heat transfer condition. The effect of temperature is taken into account in the stress field by... 

In this paper we introduce a dynamical model for Phonocardiogram (PCG) signal which is capable of generating realistic synthetic PCG signals. This model is based on PCG morphology and consists of three ordinary differential equations and can represent various morphologies of normal PCG signals. Beat-to-beat variation in PCG morphology is significant so model parameters vary from beat to beat. This model is inspired of Electrocardiogram (ECG) dynamical model proposed by McSharry et al. and can be employed to assess biomedical signal processing techniques  

The understudy SURENA III humanoid robot was designed and fabricated at the Center of Advanced Systems and Technologies (CAST) located in the Universityof Tehran. In this paper, a full dynamic model of SURENA III in different walking phases including heel-offand heel-strike motions is presented. To this end, first a trajectory planning method based on robot kinematics is introduced. Then, the multi-body dynamics of the robot links are calculated using Lagrange and Kane approaches which are then verified. In this model, the power transmissionsystem is considered to be ideal. Afterward, system identification routine is adopted to model the dynamic behavior of the power transmission system. By... 

Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on... 

Unmanned helicopters have gained great importance during recent years due to their special abilities such as hover flight, vertical take-off and landing, maneuverability and superior agility. The advances in electronic devices technologies lead to more powerful and lighter processors to be used in avionic systems which have attracted more attention to these UAVs. The first steps of utilizing an unmanned helicopter are dynamic modeling, control system design and performing model-in-the-loop (MIL) and hardware-in-the-loop (HIL) tests which are presented in this paper. In this research, MIL and HIL tests of an unmanned helicopter are done using novel Linux-based flight control system built on... 

In this paper we present a novel planar structure of a snake-like robot. This structure enables passive locomotion in snake-like robots through an auxiliary link in joint and a torsional spring. Dynamic equations are derived, using Gibbs-Appell method. Kinematic model of the robot include numerous non-holonomic constraints, which can be omitted at the beginning by choosing proper coordinates to describe the model in Gibbs-Appell framework. In such a case, dynamic equations will be significantly simplified, resulting in significant reduction of simulation time. Simulation results show that, by proper selecting initial conditions, joint angles operate in a limit cycle and robot can locomote... 

In this paper dynamic modeling and direction control of a launching bed (L.B.) with 2 D.O.F. rotation around vertical and lateral axes, mounted on a vehicle moving on a rough road is investigated. The purpose of direction control is to bring the L.B. from any initial angle to a desired angle with respect to the reference frame and to keep it there. The vehicle model is a full car with bounce, yaw, roll and pitch degrees of freedom. The suspension system of the vehicle is considered to have passive elements and unsprung masses. The stiffness of the tires is also included in the model. To control the position of the launching bed, a servo-hydraulic system comprising of hydro-motors, gearboxes,... 

This paper concerns non-linear state estimation in a batch polymerization reactor where suspension polymerization of methyl methacrylate takes place. A kinetic model proposed in the literature is selected and its validity has been verified through an experimental set-up. Based on this model monomer conversion and average molecular weights of the polymer are estimated using only one output measurement (reactor temperature). The performance of the estimator, which has the structure of an extended Kalman filter, is examined through simulation and experimental studies in the presence of different levels of parameter uncertainties. The effects of adding 'fictitious noise' and parameter state' to... 

This paper presents the kinematics and dynamic modeling of a three-link (3-DOF) underwater manipulator where the effects of hydrodynamic forces are investigated. In our investigation, drag and added mass coefficients are not considered as constants. In contrast, the drag coefficient is a variable with respect to all relative parameters. Experiments were conducted to validate the hydrodynamic model for a one degree-of-freedom manipulator up to a three degrees-of-freedom manipulator. Finally, the numerical and experimental results are compared and thoroughly discussed