Igor Iljin

Modelling of Mechanical Structure of Atomic Force Microscope

This paper dedicated of introduction of dynamic model of improved mechanical system of sensor of atomic force microscope. The subject of the research is enhancement of dynamic characteristics of cantilever - main mechanical part of sensor. These characteristics defines frequency of oscillations of mentioned cantilever and are main limitations of the speed of scanning procedure of the microscope. Modification of original dynamic system of atomic force microscope made adding nonlinear additional stiffness, created by stream of compressed air. In order to determine dynamic characteristics of modified system there are necessary to create corresponding dynamic model. Parameters of such model were defined using experimental research and theoretically from 3-D model of microscope cantilever. Solution of this model brings dependencies between air gap, pressure of compressed air and oscillation frequency of cantilever. Finally, results there are presented and conclusions are drawn.

Research of Modified Mechanical Sensor of Atomic Force Microscope

Atomic force microscope (AFM) is a remarkable device for nanoscale surface scanning. Among several positive features, speed of a scanning limits implementation of AFM. This paper proposes method that enables to increase a speed of scanning by modifying some features of mechanical sensor by adding a nonlinear force to lever of a mechanical sensor of AFM. Proposed method is modeled theoretically, using Simulink features by realizing original algorithm, and researched experimentally, using original modification of AFM sensor. Original results are obtained after a research is performed. Finally, comparison of results of original and modified AFM scans is made and corresponding conclusions are drawn.

Dynamic Reaction Forces of an Overhead Crane on Lifting

Abstract In the recent period, girder bridge cranes are replaced with double-beam overhead cranes with a rectangular cross-section of the beams. In addition, new materials are used for producing them thus applying other values of allowable loads and deformations. The paper focuses on two overhead cranes working for JSC Vilniaus kranai (Vilnius Cranes). The presented mathematical model provides an opportunity to assess the structural peculiarities of the above introduced cranes. The calculated results of dynamic loads appearing in the beginning and the end of the lifting process and having an impact on the lifting mechanism and metal structure are provided in the article.

Model of a Multi-Sectional Web Offset Printing Press Drive Section, Controlled by Electronic Shaft

For synchronization of sections of modern printing machines and equipment of such sections, driven by individual drives the system of “electronic shaft” is widely used. A development of the mathematical model of such a local drive, consisting of mechanical and electric-electronic parts as well as links between them, is provided. The model with an effective adaptive control block for increasing accuracy of the drive is provided in the form of a structural scheme. It, first of all, is usable for investigations of linear and nonlinear dynamic processes that take place in the mechanical part of the drive. Processes that take place in the electric drive are not detailed in this article. An example of the application of the model is provided.

Modification of the AFM Sensor by a Precisely Regulated Air Stream to Increase Imaging Speed and Accuracy in the Contact Mode

Increasing the imaging rate of atomic force microscopy (AFM) without impairing of the imaging quality is a challenging task, since the increase in the scanning speed leads to a number of artifacts related to the limited mechanical bandwidth of the AFM components. One of these artifacts is the loss of contact between the probe tip and the sample. We propose to apply an additional nonlinear force on the upper surface of a cantilever, which will help to keep the tip and surface in contact. In practice, this force can be produced by the precisely regulated airflow. Such an improvement affects the AFM system dynamics, which were evaluated using a mathematical model that is presented in this paper. The model defines the relationships between the additional nonlinear force, the pressure of the applied air stream, and the initial air gap between the upper surface of the cantilever and the end of the air duct. It was found that the nonlinear force created by the stream of compressed air (aerodynamic force) prevents the contact loss caused by the high scanning speed or the higher surface roughness, thus maintaining stable contact between the probe and the surface. This improvement allows us to effectively increase the scanning speed by at least 10 times using a soft (spring constant of 0.2 N/m) cantilever by applying the air pressure of 40 Pa. If a stiff cantilever (spring constant of 40 N/m) is used, the potential of vertical deviation improvement is twice is large. This method is suitable for use with different types of AFM sensors and it can be implemented practically without essential changes in AFM sensor design.

Modification of the AFM Sensor by the Precisely Regulated Air Stream to Increase the Imaging Speed and Accuracy

Increasing of the imaging rate of conventional atomic force microscopy (AFM) is almost impossible without impairing of the imaging quality, since the probe tip tends to lose contact with the sample. We propose to apply the additional nonlinear force on the upper surface of a cantilever, which will help to keep the tip and surface in contact. In practice this force can be produced by the precisely regulated airflow. Such an improvement affects the AFM system dynamics, which were evaluated using a mathematical model presented in this paper. The model defines the relationships between the additional nonlinear force, the pressure of the applied air stream and the initial air gap between the upper surface of the cantilever and the end of the air duct. It was found that the nonlinear force created by the stream of compressed air (aerodynamic force) prevents the contact loss caused by the high scanning speed or higher surface roughness, and at the same time has minimal influence on the interaction force, thus maintaining stable contact between the probe and the surface. This improvement allows to effectively increase the scanning speed by at least 10 times using a soft (spring constant of 0.2 N/m) cantilever by applying the air pressure of 40 Pa. If a stiff cantilever (spring constant of 40 N/m) is used, the potential of accuracy improvement reaches 92 times. This method is suitable for use with different types of AFM sensors and can be implemented practically without essential changes in AFM sensor design.

Research of the New Type of Compression Sensor

Measuring process of physical parameters for mechatronic system well developed and available sensors covers vast amount of interest area. Nevertheless, there are areas with some requests for sensors with special properties. Many applications require sensors, able to operate in harsh conditions.

An Investigation Into Fault Diagnosis in a Rotor-Bearing System with Dampers Used in Centrifugal Milk Separators

This paper deals with the problems encountered in the fault diagnosis in damped rotorbearing systems used in centrifugal milk separators. It is shown that direct bearing vibration measurements are more reliable than indirect (through rotor housing) vibration measurements. However, in most cases it is not possible to measure bearing vibrations directly. The factors causing large diagnostic measurement errors, such as the influence of the vibration damping system, step-up gear and electric motor noise are discussed in the paper. It is established that vibration measurements of the damping system are noninformative and cannot be used to diagnose faults in bearings. It is proposed to use the vibration spectra correlation to predict bearing failures in rotor-bearing systems of this type.

Modelling of Double-Pendulum Based Energy Harvester for Railway Wagon

Powering various electronic devices using mechanic energy harvester became ordinary solution for remotely installed ones. Recent installation of harvesters on surfaces with steady-state harmonic vibrations is well known. Harvesters, utilizing chaotic vibration for energy gaining, require define design and its dynamic parameters. Implementation of energy harvester on railroad cargo wagon for signaling and diagnostic information transfer requires special characteristics of such harvester. In such case, mostly vibrating surface in the cargo wagon is bogy, therefore vibration data for the harvester taken from real measurements of the bogy vibration on real railroad. In order to solve problem of harvester parameters, modelling using Simulink software performed. Dynamic model of harvester contains horizontal pendulum and electrical elements, serving of mechanical damper – electric energy transfer. Excitation of this system applied as kinematic excitement of pendulum pins, connected with harvester body. This model build using II type of Lagrange equation, pendulums built using special supporting springs, limiting pendulum active angles. Simulation of this model performed for 1 km of drive using measurements of newly build railway. Results of the modelling presented graphically and amount of gained energy evaluated by integrating resulting vibration. On basis of the results, conclusions are drawn and recommendations given.

Experimental Research of Improved Sensor of Atomic Force Microscope

Atomic force microscope (AFM) – is device widely used in many scientific fields for nano-scale surface scanning. AFM also can be used to probe mechanical stiffness, electrical conductance, resistivity, magnetism and other properties. The main limitation of AFM implementation is relatively low scanning speed. This speed depends from dynamical characteristics of AFM sensor and from surface roughness of scanned sample. Our research is focused on increasing scanning speed of AFM microscope assuming AFM mechanical sensor as sensitive dynamic system. Our proposed method enables increase of scanning speed by modifying some features of mechanical sensor by adding non-linear force to the surface of cantilever of AFM sensor. Proposed method is modelled theoretically using Simulink features. This paper presents research of mechanical sensor of AFM. After performed research, obtained results are presented on graphical form. At the end of paper discussion presented and conclusions are drawn.