Marat Dosaev

Methods of qualitative analysis in the problem of rigid body motion in medium

The present paper describes the application of methods of qualitative analysis in the classical problem of rigid body motion in medium. Three particular problems are used as examples: bolides flight, galloping of aeroelastic constructions, and behavior of horizontal axis wind turbine. It is shown that this approach reveals the general properties of the behavior of objects studied, such as impossibility of translational deceleration of bolides and the presence of hysteretic phenomena in the operation of wind turbines.

Modeling of oscillating wind turbine

The operating capacity of wind turbines of a new type is considered in which autorotation of the wind-receiving surface is replaced by oscillations of small amplitudes. It is shown that an oscillating wind turbine in its utilization of wind power falls between a three-blade Savonius rotor and a Darye rotor. The advantage of oscillating wind turbines is the possibility of significantly increasing the area of the wind-receiving surface without a noticeable growth of the area needed for the placement of the unit.

In Vivo Analysis of Trapeziometacarpal Joint Kinematics during Pinch Tasks

This study investigated how the posture of the thumb while performing common pinch movements and the levels of pinch force applied by the thumb affect the arthrokinematics of the trapeziometacarpal joint in vivo. Fifteen subjects performed the pinch tasks at the distal phalange (DP), proximal interphalangeal (PIP) joint, and metacarpophalangeal (MP) joint of the index finger with 0%, 50%, and 80% of maximal pinch forces by a single-axis load cell. 3D images of the thumb were obtained using the computed tomography. The results show that the reference points moved from the central region to the dorsal-radial region when changing from pinching the DP to the MP joint without pinching force being applied. Pinching with 80% of the maximum pinching force resulted in reference points being the closest to the volar-ulnar direction. Significant differences were seen between 0% and 50% of maximum pinch force, as well as between 0% and 80%, when pinching the MP joint in the distal-proximal direction. The effects of posture of the thumb and applied pinch force on the arthrokinematics of the joint were investigated with a 3D model of the trapeziometacarpal joint. Pinching with more than 50% of maximum pinch force might subject this joint to extreme displacement.

Bifurcation of operation modes of small wind power stations and optimization of their characteristics

Wind stations of small power (small WPS) are intended to ensure the operation of a small number of electric devices. Under these conditions, the connection of even a single additional consumer may result in operation disturbances. In [1, 2], a mathematical model of a small WPS operation was proposed, which allowed a qualitative explanation of the energy output hysteresis phenomenon experimentally observed under variation in the external load. In the present paper, on the basis of this model, we study the problems of existence and stability of steady-state modes and describe their attraction domains. We show that there exist different types of bifurcations of these modes, which result, in particular, in the onset of finite-amplitude periodic motions. For the first time, the performance of a power plant is estimated by the maximal consumption power criterion. The results are compared with the results obtained by other criteria.

Wind Turbine Based on Antiparallel Link Mechanism

A new type of wind turbine is proposed. A blade is attached to a connected rod of an antiparallel link mechanism. The blade interacts with air flow. A rotor of an electrical generator is fixed on an axis of a crank. The mathematical model of electro-mechanical system is constructed. The interaction between blade and flow is described using quasi-static approach. A working regime of the turbine corresponds to an attracting periodic trajectory of the dynamic system. Sufficient conditions of existence of such periodic trajectories are obtained by the Poincare-Pontryagin asymptotic method. Bifurcation diagrams are constructed. A prototype is tested in a wind tunnel.

Estimating Characteristics of a Contact Between Sensing Element of Medical Robot and Soft Tissue

A video tactile sensor is considered as a working instrument of medical robot. A problem of the contact of the silicon head of the tactile sensor with a multilayer soft tissue is considered. For contact with the two-layer tissue analytical dependencies of the load and the radius of contact on time are given for small values of indentation speed. The problem is solved numerically for contact of the head with a three-layer tissue, which simulates skin, muscle and bone. The results of the modelling are used to estimate the contact and internal stresses during indentation process of the working element of the medical robot into soft tissue. Aimed to prevent critical stresses and strains, using the data from video tactile sensor and force sensors of robot allow controlling an acting of the robot working element upon layered soft tissue.

Video-tactile pneumatic sensor for soft tissue elastic modulus estimation

BackgroundA new sensor for estimating elasticity of soft tissues such as a liver was developed for minimally invasive surgery application.MethodsBy measuring deformation and adjusting internal pressure of the pneumatic sensor head, the sensor can be used to do palpation (indentation) of tissues with wide range of stiffness. A video camera installed within the sensor shell is used to register the radius of the contact area. Based on finite element model simulations and the measured data, elastic modulus of the indented soft tissue can be calculated.Results and conclusionsThree phantom materials, namely plastic, silicone and gelatin, with varied stiffness were tested. The experimental results demonstrated that the new sensor can obtain highly reliable data with error less than 5%. The new sensor might be served as an instrument in laparoscopic surgery for diagnosis of pathological tissues or internal organs.

Periodical motions of a hinge mechanism type wind power system

A wind power system based on an antiparallel link mechanism is proposed. Mathematical model is constructed. Sufficient conditions of existence of attractive periodical motions are derived using the Poincare-Pontryagin theorem. Asymptotic bifurcation diagrams are constructed. Trapped power at periodical motions is estimated.

Pneumatic Video Tactile Sensor for Laparoscopic Surgery

The main purpose of the study is design of the innovative tool for determination of mechanical properties of soft biological tissues during minimally invasive surgical operations. This applied problem is closely related with fundamental problems of diagnostics of pathological conditions of soft biological tissues by means of the tactile sensor. In this paper, the contact interaction between the tactile sensor and the soft biological tissue is studied. The analysis of the stress-strain state of soft tissue is carried out using the solution of boundary value problem of contact mechanics. As a first approximation, the linear elastic model of biological tissue is used in formulation of the problem of contact interaction between biological tissues and the artificial tactile sensor. A method is proposed for determination of mechanical characteristics of the studied tissue basing on measurement of the air pressure in pneumatic chamber of the sensor and on processing of images of the contact area between the sensor head and the tissue. An approach is developed for measuring the axial displacement of the central point of the sensor head and using this information in the procedure of estimation of tissue properties, which extends the potential of the proposed method. The prototype of the miniature video pneumotactile sensor is constructed and tested. Results of these experiments are in good agreement with results of numerical simulations.

On wind turbine blade design optimization

A wind turbine with a horizontal rotation axis is considered in the stationary airflow. A problem of choosing the law of change of the setting angle of the cross section of the wind turbine blade and the value of the angular speed so that the wind energy utilization coefficient is maximal is discussed. Maximization of the respective functional is considered as a variational problem with a priori unknown parameter. Once it is solved numerically or analytically, the optimal value of this parameter is determined, with the sought variables given by rather simple formulas. The results are analyzed on a qualitative level. In particular, the setting angle is found to change monotonically along the blade, which is confirmed by practical wind turbine design. Examples of using the proposed approach to wind turbine blade design are considered.