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Number of results: 84
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Abstract

The article presents the use of the Mamdani fuzzy reasoning model to develop a proposal of a system controlling partnering relations in construction projects. The system input variables include: current assessments of particular partnering relation parameters, the weights of these parameters’ impact on time, cost, quality and safety of implementation of construction projects, as well as the importance of these project assessment criteria for its manager. For each of the partnering relation parameters, the project’s manager will receive controlrecommendations. Moreover, the parameter to be improved first will be indicated. The article contains a calculation example of the system’s operations.
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Abstract

Due to different reasons a significant modal shift from railway to road transport took place over last decades. The basic reasons are pointed in the paper introduction together with contradicting transport policy taking into account environmental and economical challenges. Political vision to stimulate modal shift from road and air to railway cannot become true without achieving railway technical and operational interoperability. Paper describes wide range of technical barriers between individual intraoperable railway systems in civil engineering structures, traction power supply, control command and signalling and the ways, which are being applied to ensure stepwise converging of the technical solutions taking into account safety and technical compatibility, as well as other essential requirements, namely: reliability, accessibility, health and environment.
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Abstract

This article presents a hybrid control system for a group of mobile robots. The components of this system are the supervisory controller(s), employing a discrete, event-driven model of concurrent robot processes, and robot motion controllers, employing a continuous time model with event-switched modes. The missions of the robots are specified by a sequence of to-be visited points, and the developed methodology ensures in a formal way their correct accomplishment.
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Abstract

The rules and guidelines for integrated pest management specified in Annex III, sections 2 and 3, state “General principles of integrated pest management”: Harmful organisms must be monitored by adequate methods and tools, where available. Such adequate tools should include observations in the field as well as scientifically sound warnings, forecasting and early diagnostic systems, where feasible, as well as advice from professionally qualified advisors. As part of Multiannual Programs, the Institute of Plant Protection – NRI in Poznań has been carrying out work and research for many years to develop or modify guidelines for monitoring short- and long-term forecasting of pest occurrence on crops. These guidelines are extremely helpful for farmers and advisers in determining the optimum date of chemical control of pests on plants. Regularly revised and improved the guidelines deal with pests which currently pose a threat to crops. They are developed according to the latest scientific findings and are successfully promoted among professional users and agricultural advisors. These guidelines are standardized to include descriptions of species, life cycles, symptoms of damage/infestation of crops, methods of observation targeted at warning of the need for plant protection treatments, and threshold values of harmfulness. All guidelines include extensive photographic material. Guidelines for the monitoring of pests on orchard plants, vegetables and others are prepared at the Institute of Soil Science and Plant Cultivation − NRI in Puławy and the Institute of Pomology in Skierniewice. Guidelines for about 80 pests of crops are available for public use in the on-line Pest Warning System (Platforma Sygnalizacji Agrofagów, www.agrofagi.com.pl).
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Abstract

Research activities of Polish research groups in a period of 2015–2019 on reference frames and reference networks are reviewed and summarised in this paper. The summary contains the results concerning the implementation of latest resolutions on reference systems of the International Union of Geodesy and Geophysics and the International Union of Astronomy with special emphasis on the changes in the Astronomical Almanac of the Institute of Geodesy and Cartography, Warsaw. It further presents the status of the implementation of the European Terrestrial Reference System 1989 (ETRS89) in Poland, monitoring the terrestrial reference frame, operational work of GNSS permanent IGS/EPN stations in Poland, operational work of the laser ranging station in Poland of the International Laser Ranging Service (ILRS), active GNSS station network for the realization of ETRS89 in Poland, validation of recent ETRS89 realization, expressed in ETRF2000 in Poland, and maintenance of the vertical control in Poland (PL-KRON86-NH). Extensive research activities are observed in the field of maintenance and modernization of gravity control not only in Poland, but also in Sweden and in Denmark, as well as establishment of gravity control in Ireland based on absolute gravity survey. The magnetic control in Poland was also regularly maintained. The bibliography of the related works is given in references.
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Abstract

This paper addresses the state-variable stabilising control of the power system using such series FACTS devices as TCPAR installed in the tie-line connecting control areas in an interconnected power system. This stabilising control is activated in the transient state and is supplementary with respect to the main steady-state control designed for power flow regulation. Stabilising control laws, proposed in this paper, have been derived for a linear multi-machine system model using direct Lyapunov method with the aim to maximise the rate of energy dissipation during power swings and therefore maximisation their damping. The proposed control strategy is executed by a multi-loop controller with frequency deviations in all control areas used as the input signals. Validity of the proposed state-variable control has been confirmed by modal analysis and by computer simulation for a multi-machine test system.
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Abstract

The paper presents application of guidance system for small, smart mortar missile. The presented control system is simple and inexpensive. It is based on a set of one time used impulse control engines and linear coordinator rotating with controlled object. Engines are mounted around the missile. There are no movable devices on the projectile board. The correcting impulses from rocket engines are perpendicular to main symmetry axis of the flying object and influence directly the centre of gravity of the guided missile. In the paper, authors describe the whole control system of the missile. Particular attention is focused on seeker and control devices. Numerical analysis presents some cases of the missile controlled flights.
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Abstract

In the paper, the authors describe and solve the problem of optimum control of selected vibration forms in mechanical systems. Two illustrative examples have been used to present the procedure for determination of the optimum controller coefficients. In the first example, a simplified mechanical system is considered, while in the second one – a rotor with magnetic bearing. In both cases, the integral performance indices have been defined in order to minimize the vibration level at selected points of the structures. The system with the magnetic bearing is structurally unstable. For this reason, the authors present the way of finding the weight coefficients of integral performance index for unstable, multi-degrees-of-freedom system. In that way, the selected modal forms attain the previously assumed dynamic properties and the performance index takes the minimum value. The results of numerical analysis show that the proposed way is efficient and makes it possible to control selected forms of vibration in the system.
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Abstract

The issues of medical robots have been approached for 12 years in the Institute of Machine Tools and Production Engineering of the Technical University of Lodz. In the last two years, the scope of research related to the miniaturization of surgical tools, automated changing of these tools with the use of a tool depot designed for this purpose, equipping the robot in the sense of touch and developing the software which provides ergonomic and intuitive robot control with the use of all its functions. In the telemanipulator control, strong emphasis is placed on the intuitiveness of control, which is hard to be ensured due to the fact that the robot tool is observed by a laparoscopic camera, whose orientation and position may vary. That is the reason for developing a new algorithm. It copies the increments of the position and orientation measured in relation to the monitor coordinate system onto the robot tool movement and orientation, which are measured in relation to the camera coordinates system. In this algorithm it is necessary to solve inverse kinematics, which has a discontinuity. Avoiding the discontinuity is achieved by mapping the solution with the cosine function. It causes smooth pass through the area of discontinuity in this way avoiding the singularity.
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Abstract

In this paper, the authors consider the influence of axial load on the stability of shells of revolution subjected to external pressure. Shells of different geometry are investigated with emphasis to barrelled shells. The variable quantities are length L and meridional radius of curvature R1 of a shell. The constant parameters are: thickness of the shell h, mass ms and reference radius r0. The material of shells is steel. Numerical calculations were performed in the ABAQUS system. All the shells considered in this paper were subjected to axial compression to determine the force corresponding to the loss of stability in such conditions. A part of this force is then used to preload shell before the buckling analysis in the conditions of external pressure is started. The buckling shapes for shells of different geometry are presented with and without the influence of axial load. The ability of controlling the buckling strength and shape is discussed.
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Abstract

Passive noise reduction methods require thick and heavy barriers to be effective for low frequencies and those clasical ones are thus not suitable for reduction of low frequency noise generated by devices. Active noise-cancelling casings, where casing walls vibrations are actively controlled, are an interesting alternative that can provide much higher low-frequency noise reduction. Such systems, compared to classical ANC systems, can provide not only local, but also global noise reduction, which is highly expected for most applications. For effective control of casing vibrations a large number of actuators is required. Additionally, a high number of error sensors, usually microphones that measure noise emission from the device, is also required. All actuators have an effect on all error sensors, and the control system must take into account all paths, from each actuator to each error sensor. The Multiple Error FXLMS has very high computational requirements. To reduce it a Switched-Error FXLMS, where only one error signal is used at the given time, have been proposed. This, however, significantly reduces convergence rate. In this paper an algorithm that uses multiple errors at once, but not all, is proposed. The performance of various algorithm variants is compared using simulations with the models obtained from real active-noise cancelling casing.
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Abstract

Fast and accurate grid signal frequency estimation is a very important issue in the control of renewable energy systems. Important factors that influence the estimation accuracy include the A/D converter parameters in the inverter control system. This paper presents the influence of the number of A/D converter bits b, the phase shift of the grid signal relative to the time window, the width of the time window relative to the grid signal period (expressed as a cycle in range (CiR) parameter) and the number of N samples obtained in this window with the A/D converter on the developed estimation method results. An increase in the number b by 8 decreases the estimation error by approximately 256 times. The largest estimation error occurs when the signal module maximum is in the time window center (for small values of CiR) or when the signal value is zero in the time window center (for large values of CiR). In practical applications, the dominant component of the frequency estimation error is the error caused by the quantization noise, and its range is from approximately 8×10-10 to 6×10-4.
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Abstract

Vibration intensity in mobile machines depends on the road roughness profile, ride velocity and dissipative properties of machine components. To reduce vibrations of a mobile machine with a boom equipment one of the available passive methods, utilizing a hydropnematic system for boom support to improve flexibility, the system incorporating throttling valves. Energy dissipation in a hydropneumatic system controls the decay of vibrations of the machine body and equipment. In the range of large velocities, passive methods prove inadequate. When ride velocity is to be increased, at the same time the required safety features and stabilization of the position of machine equipment are to be provided, further dynamic analyses are fully merited to identify processes taking place in the driving system. The final result should be the synthesis of the LQR control system to modulate the loading characteristics of the motor and to control the flow in a hydraulic boom-support system.
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Abstract

The summary of research activities concerning reference frames and reference networks performed in Poland in a period of 2011–2014 is presented. It contains the results of research on implementation of IUGG2011 and IAU2012 resolutions on reference systems, implementation of the ETRS89 in Poland, operational work of permanent IGS/ EUREF stations in Poland, operational work of ILRS laser ranging station in Poland, active GNSS station networks in Poland, maintenance of vertical control in Poland, maintenance and modernization of gravity control, and maintenance of magnetic control in Poland. The bibliography of the related works is given in references.
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Abstract

The paper presents the mathematical model of an autonomous induction generator with the AC load circuit and the converter control system of the voltage magnitude at the terminals of stator generator. The control algorithm and the structure of the control system are described. The simulation results of the control system are presented and discussed.
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Abstract

The development of digital signal processors and the increase in their computing capabilities bring opportunities to employ algorithms with multiple variable parameters in active noise control systems. Of particular interest are the algorithms based on artificial neural networks. This paper presents an active noise control algorithm based on a neural network and a nonlinear input-output system identification model. The purpose of the algorithm is an active noise control system with a nonlinear primary path. The algorithm uses the NARMAX system identification model. The neural network employed in the proposed algorithm is a multilayer perceptron. The error backpropagation rule with adaptive learning rate is employed to update the weight of the neural network. The performance of the proposed algorithm has been tested by numerical simulations. Results for narrow-band input signals and nonlinear primary path are presented below.
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Abstract

The development of accurate computer control of a 3 MV Van de Graaff accelerator operation is described. The developed system comprises the accelerator turn-on and turn-off procedures during a normal run, which includes the setting of the terminal voltage, ion source light up, beam focusing and control of ion beam current and energy during operation. In addition, the computer monitors the vacuum and is able to make a detail register of the most important events during a normal run. The computer control system uses a LabVIEW application for interaction with the operator and an I/O board that interfaces the computer and the accelerator system. For everyday operating conditions the control implemented is able to turn-on and off the machine in about the same time as a specialized technician. In addition, today more users can make experiments in the accelerator without the help of a specialized operator, which in turns increases the number of hours during which the accelerator can be used.
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Abstract

The paper presents construction and control system of the climbing robot Safari designed at the Poznan University of Technology for inspection of high building walls, executed in order to evaluate their technical condition. Because such tasks are uncomfortable and very dangerous for humans, this mobile machine gives a possibility to observe and examine the state of the surface on which it is moving. The robot is a construction developed for walking on flat but uneven vertical and horizontal surfaces. Its on-board equipment provides ability to remotely examine and record images reflecting the robot’s surroundings. At the beginning of the paper, several concepts of existing climbing robots (four-legged, six-legged, sliding platform) are outlined. Next, the mechanical system of the Safari robot is presented with special emphasis on its kinematic equations and description of movement stages. Then, the on-board manipulator as well as the sensor and control systems are described.
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Abstract

The article presents a numerical model of the concrete heat accumulator for solar heating systems. Model uses control volume finite element method with an explicit solution method for time integration. The use of an explicit method is an essential advantage in the simulation of time-dependent changes in temperature of the air at the accumulator inlet. The study compares the results of numerical model calculations of the accumulator heating with experimental measurements and with computational fluid dynamics modeling. The comparison shows a good correlation between the results of calculation using the model and the results of measurements.
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Abstract

In the paper, the authors present construction stages of simulation models worked out using SolidWorks and Matlab/Simulink environments. As examples of simulation models, a laboratory truck crane and a forest crane have been shown. These models allow for visualization of movements, tracking of the trajectory, velocity and acceleration of any point of the system.
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Abstract

The paper presents a solution of the control system for fatigue test stand MZGS-100 PL, comprising the integrated Real-Time controller based on FPGA (Field-Programmable Gate Array) technology with LabVIEW software. The described control system performs functions such as continuous regulation of speed induction motor, measuring strain of the lever machine and the test specimen, displacement of the polyharmonic vibrator, as well as the elimination of interferences, overload protection and emergency stop of the machine. The fatigue test stand also allows to set the pseudo-random history of energy parameter W(t).
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