Jędrzej Mączak

Research Study of the Micro Cogeneration System with Automatic Loading Unit

This article presents the test bench research of a micro cogeneration system with the Stirling engine with an automatic loading system. The tests were conducted for nitrogen as a working gas. The work presents the influence of the load current on the change of the working gas pressure in the working chamber and on the changing voltage on the electric machine. A significant number of repetitions allowed for a statistical rendering of the research description with the use of such measures as: kurtosis, coefficient of variation, coefficient of asymmetry, and of the function of the probability density. The research allows for determining whether the conducted experiment is reproducible and how the chosen parameters influence the character of the system’s work.

The Active Magnetorheological Support as an Element of Damping of Vibrations Transferred from the Ground to Large-Scale Structure Supports

The active support of a large-scale structure, made up of two elements was designed and manufactured. The first of them - piezoelectric actuator, enables the simulations of vibrations transferred from the ground to the structure. In order to minimize vibrations transmitted through the ground to the construction, the second element of the active support - a system based on magnetorheological dampers was used. The active support enables the simulations of vibrations from the ground using a piezoelectric stack controlled in a reverse feedback loop. Control signals of the feedback loop are: the volume of deformation and vibrations in the selected structures node.

Distributed System for Monitoring of the Large Scale Infrastructure Structures Based on Analysis of Changes of its Static and Dynamic Properties

The complexity and diversity of civil engineering structures impose requirements on the monitoring systems, which are difficult to be satisfied. In the paper the concept of the distributed diagnostic system capable of monitoring the technical state of critical elements of large infrastructure objects like steel trusses, supermarket buildings, exposition halls, bridges etc. is discussed. Adaptation of such systems is essential for online assessment of technical state of the infrastructure objects and could limit the possibility of catastrophic disasters with loss of people. As a source of information data from strain gauges, passive magnetic field sensors and acceleration sensors applied to the construction are considered. For the process of selection of sensors and diagnostic methods the mathematical model of the construction and the physical test stand were used.

Research on a Micro Cogeneration System with an Automatic Load-Applying Entity

The article concerns the testbed research of a micro cogeneration system based on a Stirling engine equipped with an automatic load-applying system. The article presents the influence that the load current has on acceleration of vibration of a micro cogeneration system’s body. The research was conducted while using nitrogen as the working gas. Significant number of tests offered the possibility of providing the description of the results in statistical terms while using such measures as kurtosis, coefficient of variation, the asymmetry coefficient as well as the probability density function. The research offers the possibility of concluding whether the completed experiment is repeatable as well as for determining the impact that selected load changes have on acceleration of the micro cogeneration system’s vibration.

Experimental Research of Electrochemical Energy Storage

The paper presents experimental research involving VRLA (Valve Regulated Lead Acid) AGM (Absorbed Glass Mat) batteries. Test-bench research was conducted in the conditions of constant load current. The paper presents the temperature increase on the battery’s terminals and body accompanying battery discharge in the conditions of a preset ambient temperature. The paper also presents the influence that various discharge current values had on growth of the temperature recorded on the battery’s terminals as well as the change of voltage on the battery’s terminals. Furthermore, the paper includes examination of the influence that changes of ambient temperature have on change of a battery’s useful capacity. The influence of the changes of ambient temperature was examined in a climatic chamber. Change of the battery’s internal resistance and the electromotive force, depending on the level of battery charging, are also presented. The analyses were conducted for a typical operating range of a electrochemical battery.

The Use of Fuzzy Logic in the Control of an Inverted Pendulum

Fuzzy logic control is an example of the type of developing the control algorithms using softcomputing, reflecting the imperfections of the real world. The main principle of this type of programming and, therefore, fuzzy logic is to use uncertainty and a part of the truth hidden in the received information in order to achieve the stability and the shortest possible time and simplicity of the implementation. The paper presents an example of using the fuzzy controller in order to maintain proper control of an inverted pendulum. Prepared model of an inverted pendulum pivotally mounted on a carriage represents a nonlinear dynamic object with two degrees of freedom. Control of the system is accomplished by force extortion of the corresponding displacement of the carriage. On the basis of derived equations of motion, the dynamic model of the system in Matlab/Simulink was prepared. At the stage of building a fuzzy controller, they proposed input and output linguistic variables with the respective functions of belonging and base rules. In this paper, the results of a simulation operation of the system of fuzzy logic were presented. Also the advantages and disadvantages of the proposed control method were discussed.

Experimental Research and Simulation Model of Electrochemical Energy Stores

The first part of the paper presents the results of experimental research involving VRLA (Valve Regulated Lead Acid) AGM (Absorbed Glass Mat) batteries, the lithium-ion batteries and lithium iron phosphate (LiFePO4) batteries. The experimental research was conducted in a static cycle (with constant load current). The paper presents the temperature increase on the battery’s terminals and body. The influence that various values of discharge current have on growth of temperature and change of voltage on the battery’s terminals is also presented. The second part of the paper contains the analytical relations which have been used for building the simulation model in the MATLAB&Simulink environment. The results obtained on the basis of the model have been validated against the results of experimental research.

Online Monitoring of Steel Constructions Using Passive Methods

In the chapter the possibilities of development of distributed diagnostic system capable of online structural health monitoring of civil engineering structures are discussed. Instead of commonly used methods of determining the technical state of the construction that are usually focused on searching for cracks, material heterogeneities and assessing concrete or steel degradation, the methods proposed for the system are based on the comparative strain gauge, acceleration and passive magnetic measurements. All this measurement methods are used for stress assessment in critical fragments that are vital for stability and durability of the structure. Evolution of defects in the construction causes measurable changes of stress distribution in critical joints of the construction. Additionally, materials that could cause threat of the catastrophic accident caused by fatigue wear, exceeding stress limits or emerging of plastic deformations have magnetic properties that could affect the local magnetic field. Stress limits could be then constantly supervised taking into account the range of permanent and elastic deformation, which would allow for early detection of threats. SHM data analysis is taking into consideration a series of magneto-mechanical and other phenomena occurring during the construction/machine’s operation and also actual magnetization conditions of the object examined in exterior magnetic field (Earth’s or derived from adjacent elements).

Application of Vision Based Damage Detection for Real Civil Engineering Structure

Structural Health Monitoring (SHM) is an emerging field of technology that involves the integration of sensors, data transmission, processing and analysis for detection, as well as localization and assessment of damage which can lead to its failure in the future [1,. In general, SHM methods can be divided into two groups: local and global ones. The second group can be applied if a global change in the geometry of a structure can be observed. In practice, the most commonly used methods of damage detection are based on the analysis of variations in various dynamic properties caused by damage [3,. However, the excitation of large structures can be costly and difficult. The acquisition of static deflection requires much less effort, which makes the damage detection methods based on changes in deflection curves more attractive for practical use [5-1. Damage detection and localization methods require a densely sampled deflection curve.

Dynamic model of a crankshaft assembly with two degrees of freedom

Nowadays, growing attention is directed towards energy efficiency and issues related to respecting energy. An extremely vital role at improving energy efficiency plays the cogeneration technologies. In the 2012/27/UE Directive [1], the gas turbines [2] in combination with heat recovery, combustion engines [3, 4], steam engines [4], fuel cells [5-7], microturbines [8], Rankine organic cycle [9, 10], Stirling engines [11-15], and others, were included among cogeneration technologies, in which electric energy is produced from waste heat in the combined process. In this work, the distributed generation sources have also been addressed. From the perspective of the article herein, the sources equipped with the crankshaft assembly have been particularly emphasised. This mechanism converts chemical energy of, among others, fuel or working element into mechanical energy (the piston reciprocating motion is converted into rotary motion of a crankshaft). In this work, the physical model of the crankshaft assembly has been shown, with two degrees of freedom. On the basis of analysis of the physical model (with the static mass reduction), a single-piston simulation model has been developed of the crankshaft assembly, using the Matlab&Simulink software. On the basis of the analysis of the system, the motion equations have been derived, which served the purpose of building the simulation model. Because of the conducted simulations, the curves of displacement, velocity, and piston acceleration have been presented, and, respectively, the angular displacement, angular velocity, and angular acceleration of the crankshaft. The constructed model should be seen as a part of a multi-piston working mechanism in a, for example, Stirling engine.