Colloidal Oxide Nanoparticle Inks for Micrometer-Resolution Additive Manufacturing of Three-Dimensional Gas Sensors

Micrometer-resolution 3D printing of functional oxides is of growing importance for the fabrication of micro-electromechanical systems (MEMS) with customized 3D geometries. Comparing to conventional microfabrication methods, additive manufacturing presents new...

Defining the Main Parameters and Performances of the Elevator Motor

Contemporary tendencies relentlessly dictate the conditions for the appearance of a more qualitative, reliable and comfortable elevator chain for the rolling stock of a vertical motion. At the same time, the issues of energy saving and cost-effective use of resources gain currency against the background of rising prices for energy carriers and market prices for various elements that play an essential role in the availability of many electromechanical systems. Unfortunately, attention was paid to the availability of above problems in the elevator sector when the majority of the elevators (about 60% of them) outlived their technical service life that ensured the reliable operation. As a matter of fact, an amazingly important issue is relating to the embedment of reliable, durable and economically substantiated components of electromechanical systems into contemporary Ukrainian elevators. The purpose of the research done was to define the main parameters and performances of the asynchronous elevator motor of an ADB180M6 type. The motor is powered from the industrial network of 50 Hz and the frequency converter with the frequency of 50Hz and 16.6 Hz. This scientific paper uses the methods of physical investigations. The elevator motor test data satisfy the reliability parameters that make any elevator user feel comfortable. The main measurement data obtained for the engine No43886 of an ADB180M6 type powered from the frequency converter “Altivar” of 22kW with the motor speed of 910 rpm and 289 rpm satisfy the requirements of the regulatory documentation. The noise level is within satisfactory margins.

Towards Repeatable, Scalable Graphene Integrated Micro-Nano Electromechanical Systems (MEMS/NEMS)

The demand for graphene-based devices is rapidly growing but there are significant challenges for developing scalable and repeatable processes for the manufacturing of graphene devices. Basic research on understanding and controlling growth mechanisms have recently enabled various mass production approaches over the past decade. However, the integration of graphene with Micro-Nano Electromechanical Systems (MEMS/NEMS) has been especially challenging due to performance sensitivities of these systems to the production process. Therefore, ability to produce graphene-based devices on a large scale with high repeatability is still a major barrier to the commercialization of graphene. In this review article, we discuss the merits of integrating graphene into Micro-Nano Electromechanical Systems, current approaches for the mass production of graphene integrated devices, and propose solutions to overcome current manufacturing limits for the scalable and repeatable production of integrated graphene-based devices.

Problem statement for the analysis of electromechanical systems by simulation modeling methods

The article presents an approach to the complex analysis of electromechanical systems using specialized packages of applied simulation programs. It is shown that the choice of research methodology is due to the complexity and mutual influence of energy processes in electromechanical converters and the absence of verified analytical solutions.The main research stages are defined, including the construction of a geometric model of the object, determination of the problem type to be solved and relevant initial and boundary conditions, justification of defining criteria, modeling of electromagnetic, thermal and hydraulic processes and their analysis. The software packages are based on the classical equations of electrodynamics, heat transfer, energy, motion and continuity. Creation of three-dimensional solid parametric model is implemented in the T-FlexCAD system. The simulation experiment was carried out with the use of SolidWorksFlowSimulation system, that allows to process the initial array of design parameters in conditions of the multiphysics problem statement. The variables were ranked using Statistica, a statistical processing and data analysis program. Simulation results of energy exchange processes at varying geometry of defining design parameters allow to establish dependence of electromechanical system output characteristics on design and dimension relations of system elements parameters and to design high-efficiency electromechanical systems on this basis.

Dynamics of Electromechanical Systems Containing Long Elastic Couplings and Safety of Their Operation

The electromechanical systems under analysis include electric drives, working machines that perform specific tasks in the technological process, and working mechanisms that transmit mechanical power between the electric drive and the working machine. The vast majority of electric motors included in drive systems require rotational speed control. This task is most often performed with the use of closed-loop control structures based on speed controllers. A step or overly rapid change in the speed reference causes a temporary lock of the speed controller due to the applied limitations at its output. Particularly, unfavorable effects of such a lock can be observed in drive systems in which there is a long elastic coupling (transmission shaft) between the electric motor and the working machine. As a consequence, shaft torsion and accompanying twisting moments of considerable amplitudes appear. This article proposes an uncomplicated active torque limiter structure, which enables the uninterrupted operation of the speed controller thanks to the automatic adaptation of the rate of the speed reference change to any moment of inertia of the rotor and attached rotating masses. The results of the investigations confirm the effectiveness of the proposed structure.

Modeling a Microgravity System for Ground Testing of Transformable Space Structures

The article develops a mathematical model of a microgravity system that simulates the conditions of weightlessness during ground tests of spacecraft. The microgravity system consists of vertical and horizontal control channels, providing a link opening in a twodimensional coordinate system. The channels are two-mass electromechanical systems with elastic connections. To simulate the microgravity system, mathematical models of these channels are obtained. To check the adequacy of the obtained models in Simulink Matlab, we simulated the opening of a link of a mechanical system. As a result of modeling, the permissible indicators of the accuracy of simulating weightlessness were obtained.

Multiclass Incremental Learning for Fault Diagnosis in Induction Motors Using Fine-Tuning with a Memory of Exemplars and Nearest Centroid Classifier

Early detection of fault events through electromechanical systems operation is one of the most attractive and critical data challenges in modern industry. Although these electromechanical systems tend to experiment with typical faults, a common event is that unexpected and unknown faults can be presented during operation. However, current models for automatic detection can learn new faults at the cost of forgetting concepts previously learned. This article presents a multiclass incremental learning (MCIL) framework based on 1D convolutional neural network (CNN) for fault detection in induction motors. The presented framework tackles the forgetting problem by storing a representative exemplar set from past data (known faults) in memory. Then, the 1D CNN is fine-tuned over the selected exemplar set and data from new faults. Test samples are classified using nearest centroid classifier (NCC) in the feature space from 1D CNN. The proposed framework was evaluated and validated over two public datasets for fault detection in induction motors (IMs): asynchronous motor common fault (AMCF) and Case Western Reserve University (CWRU). Experimental results reveal the proposed framework as an effective solution to incorporate and detect new induction motor faults to already known, with a high accuracy performance across different incremental phases.

Design and Implementation of SOC-Based Noncontact-Type Level Sensing for Conductive and Nonconductive Liquids

In contrast to the existing electromechanical systems, the noncontact-type capacitive measurement allows for a chemically and mechanically isolated, continuous, and inherently wear-free measurement. Integration of the sensor directly into the container’s wall offers considerable savings potential because of miniaturization and installation efforts. This paper presents the implementation of noncontact (NC)-type level sensing techniques utilizing the Programmable System on Chip (PSoC). The hardware system developed based on the PSoC microcontroller is interfaced with capacitive-based printed circuit board (PCB) strip. The designer has the choice of placing the sensors directly on the container or close to it. This sensor technology can measure both the conductive and nonconductive liquids with equal accuracy.