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EN
The major goal of this research is to create a reliable model for predicting the mechanical properties of composite material with fatigue failure and to determine how changing the fiber orientation and the layer arrangement with regard to the applied loading direction affects the mechanical characteristics of the result components in order to establish the service life with health monitoring of these structures. A multilayer composite consisting of five layers which represent shell structure, with the middle layer reinforced by carbon fiber and the top and bottom layers reinforced by glassfiber random mate and unidirectional glassfiber. According to the tensile test results, the orientation (2 L- GF- (0°/90°)s) had the maximum tension load (13 kN) due to the asymmetrical arrangement of layers and identical distribution of the load within layers, whereas the orientation (2 L- GF-0°) had the lowest tension load (5.6 kN) compared with other fiber orientations. The compression strength of the orientation 4 (2 L- GF- (0°/90°)2) with (1.72 kN) and orientation 7 (2 L- (90°/ RGF)s with (1.7 kN) is greater than that of the other orientations. The specimen fails in the test at about (519318 cycles) with time (352 minute) for orientation number 3.
PL
W artykule przedstawiono zastosowanie mikrokontrolerów STM32 do przetwarzania sygnałów biomedycznych w czasie rzeczywistym, ze szczególnym uwzględnieniem wykorzystania bibliotek CMSIS-DSP. Opisano podstawy przetwarzania sygnału fotopletyzmograficznego (PPG) i elektrokardiograficznego (EKG), przedstawiono strukturę biblioteki CMSIS-DSP i koncepcję przetwarzania sygnałów w mikrokontrolerach oraz przedstawiono przykładową implementację algorytmów DSP. Przedstawiono również wybrane elementy optymalizacji opracowanych algorytmów obliczeniowych, zwracając uwagę na efektywne zarządzanie zasobami pamięci i mikroprocesora. Zaproponowane rozwiązania mogą mieć zastosowanie w systemach elektroniki noszonej do monitorowania parametrów życiowych człowieka, np. pomiaru saturacji krwi tlenem i do obliczania zmienności rytmu serca.
EN
The article presents applications of STM32 microcontrollers for real-time biomedical signal processing, with particular emphasis on the use of CMSIS-DSP libraries. The basics of photoplethysmographic (PPG) and electrocardiographic (ECG) signal processing are discussed, the structure of the CMSIS-DSP library and the concept of signal processing in microcontrollers are presented and an example implementation of DSP algorithms is provided. Computational algorithm optimization elements are also presented, focusing on efficient memory and processor resource management. The proposed solutions can be applied in wearable electronics systems for monitoring human life parameters, such as blood oxygen saturation measurement and heart rate variability calculations.
EN
This article characterises the methodology for the endoscopic testing of a laboratory diesel engine used for testing marine fuels. The ‘Shadow’ measurement method used in the XLG3 type EVEREST digital endoscope, for quantitative and qualitative identification of detected surface defects, was approximated. Representative endoscopic images of the elements limiting the working space of the research engine are demonstrated, having been recorded during the usable quality testing of newly produced, low-sulphur marine fuels, so-called ‘modified fuels’. The main purpose of the endoscopic examinations was the final verification of the tested fuel’s suitability for feeding full-size marine engines.
EN
During this work, the roof of the car was used as an engineering application to study and monitor the occurrence of failures under the influence of various loads. The shells are made of multilayer composite materials using epoxy resin reinforced with carbon fiber and aluminium oxide granules as reinforcing materials to increase the impact resistance that vehicles may be exposed to while driving, in addition to other loads and conditions such as vibration and constant exposure to moisture and sunlight. The simulation program was used the finite elements method through software Abaqus program in addition to the program MATLAB v.2020a to process the data obtained from the method that used in this study. The results showed that the specified failure criteria work well for predicting the overall structural response such as strain, stress, maximum force and displacement. The losses of energy of impact collision increase as an increase in impact velocity. The dissipation of energy which depend on the stress and strain distribution during elastic deformations. The effect of thickness of the lamina plays an important role in health monitoring the structure.
EN
In current society, smart clothing technology has become a critical way to improve the life quality of the elderly. This work conducted a category product evaluation and user demand system through the bibliometrics method, product evaluation analysis, focus group interviews and questionnaires. Based on the system, we designed smart clothing from the aspects of the clothing structure, hardware, software program and intelligent terminal platform to meet the needs of disabled elderly people and their caregivers in multiple scenarios. According to the test results of the smart clothing, the average error of temperature and humidity monitoring is 0.20℃ and 2.88%RH. The time of putting on-taking off clothing in 6 representative daily scenarios was reduced by 51.67%. The daily body checking times, uncomfortable behaviours, and the anxiety of caregivers was decreased by 42.31%, 28.52% and 74.37%. Compared with ordinary clothing, six of the eight comfort performances are basically the same, and two are slightly worse.
EN
The common damage in engineering structures, especially in functionally graded materials, such as failure resulting from fiber breaking or cracking in the matrix or deboning between fibers and matrix, as well as the delamination between the composite material plies and between its layers, may be due to thermal effects, vibration, load concentration as a result of stress and strain for provides information’s about structural health monitoring. Virtual energy method such as Hamilton's was used to investigate the effect of the design parameters such as side to thickness and modular as well as material graduation index ratio on the stress-strain relationships, displacement, resultants of stresses, and resultants of mid plane strain. The analysis and simulation of the FGM shells is done in this paper utilizing MATLAB19 code and ABAQUS20 programs. The distribution of characteristics across shell thickness had also been determined using a power law. Normal stress was varied gradually from 5.74 MPa to 9.55 MPa with material index (n) from 0 to 10 respectively, while shear stress varied from 4.2 to 8.23 MPa for the same value of (n). The strain percent increased slightly from 0.00059 to 0.0012 with displacement 0.22 and 1.2 respectively for the same value of (n).
7
Content available Health monitoring in landing gears
EN
Every mechanical construction loses its properties in time due to the usage wear that leads to malfunctions and, in the end, to failure. Widely used method of failure time prediction base on extended laboratory tests where a device is tested against fatigue and wear. This method is well established but is expensive, time-consuming, and costly. Another way of failure prediction is to calculate it using advanced algorithms what is faster and cheaper but less accurate than actual tests. Furthermore, both methods are not optimal due to the principle of operation based on simplified assumptions. In such cases, it is common to make the lifespan of the safety wise devices for example landing gears much less than real in case of fatal failure not covered by the predictions. This can lead to much higher price and maintenance costs of the landing gear. Nowadays the worldwide trend is to monitor the behaviour of the devices in real time and predict failure using actual state. There are several methods of health monitoring, most of them including sensors, acquisition systems and computer software for analysis. In this article, authors describe possible landing gears health monitoring methods based on authors’ laboratory experience in sensor appliance and test data analysis. The authors also present their idea of adding health monitoring to existing landing gears where no dedicated infrastructure was initially designed.
8
Content available remote Challenges in causal inference from Personal Monitoring Devices
EN
Personal Monitoring Devices (PMDs) collect im- mense amount of data about health and wellness of hundreds of millions of people. One of the obstacles of the prevailing data analytics approaches to PMDs' data is limited value of correlation-based conclusions in a health context. Causal inference seems a natural solution, but general causal inference methodologies are difficult to apply to PMDs data due to size and complexity of observational data. Some methods, such as randomized trials, are largely infeasible in PMDs' context due to lack of control over the investigated population. In this paper, we overview existing approaches to causal inference including recent works that attempt to take advantage of time series data to automatically derive causality using extended difference- in-deference or Granger methods. We then outline challenges and opportunities for causal inference in the health context. Finally, we propose a following challenge: can we establish a new standard of evidence and a study design process that: (1) allows for drawing causal conclusions from large observational datasets and (2) can suggest interventions to enforce causal links discovered in the data.
9
Content available Shoe insert embedded foot pressure monitoring system
EN
The article presents the technical solution of the shoe insert, which can measure the foot pressure on the ground, and the proposal of an algorithm, which based on the received data of a shoe insert, decides whether the investigated person walks or runs. The algorithm is characterized by low computational complexity, which allows it to be used in mobile devices.
PL
W artykule przedstawiono propozycję rozwiązania technicznego wkładki do obuwia służącej do pomiaru nacisku stopy na podłoże oraz propozycję algorytmu, który na podstawie otrzymanych danych z czujników tensometrycznych wkładki podejmuje decyzję, czy badana osoba idzie czy biegnie. Algorytm charakteryzuje się małą złożonością obliczeniową, co pozwala na jego zastosowanie w urządzeniach mobilnych.
PL
W artykule przedstawiono projekt systemu, przeznaczonego do zdalnego i ciągłego monitorowania zmian ciśnienia tętniczego krwi oraz wyniki badań testowych. Przedstawiony system złożony jest z osobistego urządzenia pomiarowego, punktu dostępowego do sieci Internet oraz ogólnodostępnego serwera danych. Istotnym elementem projektowanego systemu jest metoda ciągłego pomiaru zmian ciśnienia krwi, polegająca na określaniu czasu propagacji fali tętna. Czas ten wyznaczany jest pomiędzy charakterystycznym punktem sygnału elektrokardiograficznego (EKG) i sygnału fotopletyzmograficznego (PPG). W artykule przedstawiono wyniki badań testowych, dotyczących wyznaczania punktów charakterystycznych sygnału EKG i PPG metodą autokorelacyjną oraz wyniki pomiaru zmian czasu propagacji fali tętna.
EN
The article presents the design of the system for remote and continuous monitoring of changes in blood pressure and also results of the test. Presented system consists of a personal measuring device, the access point to the Internet and widely available data server. An important element of the designed system is a method for continuous measurement of changes in blood pressure, which based on determining the pulse wave transit time. This time is calculated between the specific point electrocardiogram (ECG) signal and the photoplethysmographic signal (PPG). The article presents the results of test on the determination of specific points of the ECG signal and the PPG based on autocorrelation method and the results of measuring changes in pulse wave transit time.
PL
Jedną z nieniszczących metod detekcji uszkodzeń konstrukcji jest obserwacja zmian jej parametrów dynamicznych. Postacie drgań swobodnych i odpowiadające im częstotliwości można otrzymać w wyniku analizy modalnej na podstawie pomiaru przyspieszeń wybranych punktów układu, będących odpowiedzią na znane wymuszenie. Zmiany parametrów dynamicznych zależą nie tylko od stanu konstrukcji, ale również od czynników zewnętrznych towarzyszących pomiarom. W artykule przedstawiono wpływ temperatury na zmiany parametrów dynamicznych układu na przykładzie dwukondygnacyjnej, stalowej ramy portalowej oraz porównano ich wielkość ze zmianami wywołanymi symulowanym uszkodzeniem w postaci luzowania łączników w połączeniach rygiel-słup.
EN
One of the non-destructive testing methods is damage detection based on changes in dynamic parameters of the structure. For this purpose modal analysis could be used, where natural frequencies and forms are calculated using measured data. During experiment an examined structure is excited by external force with known value, and its vibration (accelerations in some selected points) are measured. This method was used in presented research. Unfortunately not only material characteristics or geometric and static feature of the system have an influence of the dynamic parameters. Also the external conditions during measurements can change the dynamic response of the structure. The aim of this subject was checking, is temperature affect on the dynamic parameters and how big are the changes, the source of which is the temperature. To evaluate the scale of described changes, in a laboratory model of two-storey steel portal frame, in each of beam-tocolumn connection separately, four from eight bolts were loosed. This action had to simulate the damage of the structure. In this paper the effects of temperature and simulated damages were compared.
PL
W pracy zaprezentowano wybrane wyniki monitorowania struktury samolotu PZL–130 Orlik TC II w trakcie pełnoskalowej próby zmęczeniowej. W strukturze samolotu rozmieszczono sieć czujników piezoelektrycznych PZT, podłączoną do dedykowanego systemu komputerowego, umożliwiającego zdalne monitorowanie konstrukcji. W pracy przedstawiono opis wielokanałowego urządzenia rejestrującego sygnały uzyskane z przetworników piezoelektrycznych oraz wyniki uzyskane w wybranych punktach pomiarowych na różnych etapach rozwoju pęknięć zmęczeniowych. Proponowane sposób monitorowania konstrukcji oparty jest na tzw. wskaźnikach uszkodzeń zachowujących znikomą informację o przebiegu czasowym rejestrowanych sygnałów, związanych z ich energią. W pracy przedstawiono opis wykorzystywanych charakterystyk sygnałowych oraz sposobów wnioskowania o obecności i rozwoju pęknięć zmęczeniowych. Opracowane techniki zostały zweryfikowane na podstawie danych uzyskanych w trakcie pełnoskalowej próby zmęczeniowej. Uzyskane wyniki potwierdzają zalety korzystania z systemu monitorowania uszkodzeń w oparciu o przetworniki PZT, zwłaszcza w lokalizacjach trudno dostępnych dla standardowych technik badań nieniszczących.
EN
This paper presents an approach to the health monitoring of the PZL–130 TC II Orlik aircraft structure during the full scale fatigue test (FSFT). A network of PZT piezoelectric transducers was assembled on the aircraft structure and a dedicated hardware enabling remote control and pro-grammed measurement performance was elaborated. A multichannel acquisition system of large dataset of measurements from the ‘hot-spot’ locations of the sensors on different stages of the fatigue tests is described in the paper. In the adopted approach a set of Damage Indices (DI’s), carrying marginal signal information content and correlated with the total energy received by a given sensor are proposed. The paper provides the description of elaborated techniques for the signal processing and inference about the damage presence. Damage detection capabilities are exemplified by data collected from selected network nodes where damages were found during the project run and the results of their monitoring will be highlighted. The necessity of the use of NDE assisted technology for early damage detection has been proven within the project, especially for the ‘hard to access’ locations in the aircraft structure.
PL
Most składa się z trzech sekcji: estakady południowej E1 w postaci 11-przęsłowej (40 + 2×52 + 56 + 6 ×60 + 50 m) belki z betonu sprężonego o przekroju skrzynkowym, mostu głównego z betonu sprężonego o konstrukcji podwieszonej do jednego pylonu wysokości 122 m, z przęsłami rozpiętości 50 + 2×256 + 50 m, estakady północnej E3 w postaci 9-przęsłowej (50 + 7 × 60+ 50 m) belki ciągłej z betonu sprężonego. Omówiono rozwiązanie materiałowe i konstrukcyjne pylonu, ustroju nośnego oraz podwieszenia, a także zastosowany system stałej kontroli elektronicznej konstrukcji mostu podwieszonego.
EN
The bridge is 1742 m long and consists of: E1 south flyover 610 m long (40+2x52+56+6x60+50 m). It is a continuous eleven span prestressed concrete box structure, main bridge 612 m long (50+2x256+50 m) with two separate decks connected to a single concrete H-shaped pylon and E3 north flyover 520 m long (50+7x60+50 m), continuous girders made of prestressed concrete. Superstructure, construction of the pylon and cable system as well as structural health monitoring system installed on the bridge has been described.
EN
This study seeks the development of adaptive composites capable to monitor and actively damp vibrations. In the proposed material, vibrations measurements are performed by an embedded low finesse optical fibre extrinsic Fabry–Pérot interferometer, while active damping will be performed by embedded piezoelectric ceramics. This paper focuses on the development of the monitoring procedure. The proposed interrogation procedure for the low finesse optical fibre extrinsic Fabry–Pérot interferometer was successfully used to monitor the composite plate when submitted to four-point bending dynamic tests at different frequencies. The embedding of both sensing and actuating components in carbon-fibre reinforced composite laminates is also presented. In the case of the actuator, the efficiency of the embedding process was merely analysed from the capability of the piezoelectric ceramic to monitor dynamic strain of the composite using the PZT piezoelectric inverse effect.
15
Content available remote On the problem of unknown history in health monitoring
EN
A crucial feature in health monitoring of already existing structures is to be seen particularly in identifying their topical internal structural parameters and controlling their remaining bearing capacity in the course of ageing processes. This is commonly carried out by measuring the deformations/strains caused by test-loading and calculating the parameters on the basis of the metered data. In the case of elastic response of materials, the information on the parameters is directly related to the time of measurement; in the case of visco-elastic response, however, the history of the time-depending structural response during the period between initial loading and initiating the test-measurements is generally unknown. The problem exists, then, to separate the superimposed strains due to the existing state and to the test-load. For solving the problem, at first the relevant relations between stress/strain and the visco-clastic parameters are considered. Then a procedure will be described how to determine the strain state owing to the test-load only and to calculate the relevant parameters as functions of time. According to the principle of time-shift invariance, the results describe the time-depending response of the viscoelastic material, no matter at which time the loads are applied. The presented method will be illustrated by two simple but instructive examples.
PL
Sprawą o zasadniczym znaczeniu w monitorowaniu stanu istniejących konstrukcji jest identyfikacja aktualnych parametrów strukturalnych i kontrola nośności, jaką struktura zachowała w przebiegu procesu starzenia. Wykonuje się to zwykle przez pomiary deformacji/odkształceń wywołanych przez obciążenia testujące i obliczanie parametrów na podstawie danych pomiarowych. W przypadku materiałów, których odpowiedź ma charakter sprężysty, informacja o parametrach jest bezpośrednio związana z czasem pomiaru. Jednak, w przypadku odpowiedzi lepkosprężystej, historia czasowo-zależnej odpowiedzi strukturalnej w okresie pomiędzy obciążeniem wstępnym i inicjalizacją pomiarów testujących jest na ogół nieznana. Powstaje więc problem jak odseparować odkształcenia wynikające z istniejącego stanu od powodowanych obciążeniem testowym. Dla rozwiązania tego problemu, rozpatrzone będą na wstępie relacje między naprężeniami i odkształceniami a parametrami lepkosprężystości. Następnie przedstawiony będzie opis procedury pozwalającej wyznaczyć stan odkształceń powstały tylko w wyniku obciążenia testowego i obliczyć właściwe parametry jako funkcje czasu. Zgodnie z zasadą niezmienniczości względem przesunięcia w czasie, otrzymany wynik opisuje czasowo-zależną odpowiedź materiału lepkosprężystego, niezależnie od momentu, w którym zostały przyłożone obciążenia. Zaprezentowana metoda będzie zilustrowana dwoma prostymi, lecz pouczającymi przykładami.
16
Content available A new vibroacoustic method for shaft crack detection
EN
Various excitation techniques have been developed to extract information on dynamic state of rotating machinery. This paper will address the effectiveness of selected excitations and analysed signals towards health monitoring of rotating machines from the shaft crack point of view. The computer simulation study is based on the uncracked and cracked Jeffcott rotor models and the efficiency of the selected approaches is examined. As the excitation we have considered the rotor unbalance, additional harmonic forces, and input conditions. The combined resonances as diagnostic indicators of the cracked shaft are good seen in the total frequency spectrum in the case when we consider the difference between the spectra of cracked and uncracked shaft. We have also introduced a new model of the rotor which allows us to use different method of signal processing for the crack detection and the evaluation of its deep. So more, in such model we can take into account the number of excitation planes and directions of the applied forces, the choice of the analysed signals (e.g. transient, steady-state).
PL
Pękanie wału prowadzi do asymetrii jego sztywności. Według modelu pękania Mayesa sztywność zmienia się w sposób kosinusoidalny. Tego typu wymuszenie parametryczne prowadzi do kombinowanych rezonansów. Większość autorów badą zachowanie się dynamiczne wirnika w otoczeniu takiego rezonansu. W niniejszym artykule do badań diagnostycznych przyjęto model Jeffcotta dynamiki wirnika. Wyprowadzono równania ruchu uszkodzonego i nieuszkodzonego wału. Analizę drgań tego nieliniowego modelu przeprowadzono z wykorzystaniem metody małego parametru. Zaproponowano podejście transmitancyjne do modelowania uszkodzenia. Przeanalizowano możliwość pobudzania drgań maszyny z wykorzystywaniem różnych typów sygnałów. Z wielu możliwych rozwiązań prowadzących do uzyskania informacji diagnostycznej wybrano do dalszych badań model reprezentowany przez funkcję odpowiedzi częstotliwościowej. Różnica pomiędzy dynamiką uszkodzonego i nieuszkodzonego wirnika została użyta do uwypuklenia pików rezonansów kombinowanych w widmie drganiowym. Na bazie tych wymuszeń określono symptomy, z wykorzystaniem których można budować wskaźniki diagnostyczne. Rozważania analityczne poparto badaniami symulacyjnymi.
EN
The King Mongkut's Institute of Technology North Bangkok (KMITNB), founded in 1959 with the support of the government of the Federal Republic of Germany, is one of the premier higher education institutions in Thailand with a strong base in applied sciences, technology and engineering. The faculty of engineering, the largest of the four faculties of the institute, was founded with an aim to provide a range of professional engineering education service to meet the community and industry at the early phase of industrialization in Thailand. The degrees were established to fill a need for better-educated engineers in the practice of engineering as well as in research and development. The Machinery Health Monitoring and Tribology Laboratory (MHM and Tribo. Lab.) forms part of the Production Engineering Department, Faculty of Engineering. Currently, machinery health monitoring research is combined with tribology studies. In general terms, the current activities of the condition monitoring and tribology research group include: condition monitoring studies relating to oil and wear debris analysis, hydraulic failure studies as related to contaminants, routine oil, wear debris and contamination analysis for industry, developments of new and improved condition monitoring techniques, especially used oil, wear debris and contamination analysis, fundamental of friction, lubrication and wear studies, maintenance strategy studies for productivity improvement.
18
Content available remote Remote health monitoring system for the elderly living alone
EN
We have recently developed a health monitoring system for the elderly living alone. We monitored their in-house movements without restricting. We placed pyroelectric infrared sensors in each room of their houses so that monitoring will last longer easily. The secondary purpose of this system is to reduce anxiety of both the elderly and their family members living separately. Subjects of either sex were four in all and in their eighties. Continuous monitoring was performed for 40 months. We found that each one had his/her specific pattern of in-house movements. Therefore, we were able to estimate their health condition by checking the staying periods at specific rooms such as a lavatory or exercise comparing with the previous data statistically. If there is an abnormal result after analysis, we have to inform the family of the incident. Final decision should be made by his/her family, not by automatically relying on the computer software. After inquiring with the subject or his/her neighbours by telephone, family members may call an ambulance, if necessary.
EN
This paper describes a trial of monitoring fracture processes of SiC fiber reinforced aluminum composites with embedded optical fiber. It was embedded in composites reinforced with SiC fiber of different volume fractions by the interphase forming/bonding method using copper insert. These composites were tensile tested with measuring optical transmission loss. The results show that breakage of optical fiber starts at smaller strain than that of SiC fiber. The embedded optical fiber works as an optical path even after severe multiple fractures. Optical transmission loss is dependent on the number of optical fiber breakages. As fracture of SiC fiber enhances that of optical fiber and is reflected on optical transmission loss, fractures of SiC fibers can be detected by monitoring of optical transmission loss. It can also reflect the type of fracture process of the composite, that is, cumulative or non-cumulative.
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