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Tytuł:
Methods for computer aiding the configuration and assessment of auxiliary mine transportation means
Autorzy:
Tokarczyk, Jarosław
Dudek, Marek
Powiązania:
https://bibliotekanauki.pl/articles/410003.pdf
Data publikacji:
2020
Wydawca:
STE GROUP
Tematy:
computer aiding system
suspended monorail transportation
traction calculations
underground mining
Opis:
Mine transportation of materials in underground mine workings is realized by mine underground railways as well as by suspended monorails or floor-mounted railway. Transportation is realized on tracks placed on the floor of working or on rails suspended to roadway support. Each transport operation must be preceded by a transport design project, made in accordance with obligatory legislation. A part of the project are traction calculations. Their implementation in a computer program allows for minimization of the possibility of errors during the configuration of suspended queues and conducting traction calculations, which consequently leads to improve the level of safety. The article discusses the modular Safe Trans Design system, supporting the design of auxiliary mine transportation. The system has been implemented in the mines of JSW S.A. The assumptions and structure of the system as well as algorithms of operation of the ‘configurator of transportation sets’ and ‘assessment and reporting module’ are presented. The method of creating an auxiliary mine transportation system project is presented. Safe Trans Design system is used in planning, organizational and training activities implemented as part of transport safety management in mining plants. Developed methods can be easily adapted to other legislations of hard coal producers’ countries, where suspended monorails are used in underground auxiliary mining transportation systems.
Źródło:
Management Systems in Production Engineering; 2020, 4 (28); 268-275
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Practical highly enantioselective synthesis of (R)- and (S)-(E)-4-hydroxynon-2-enal
Autorzy:
Komisarski, Marek
Kaczmarska, Zuzanna
Kuśmierek, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1040657.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
asymmetric synthesis
4-HNE enantiomers
(E)-4-hydroxynon-2-enal (4-HNE) synthesis
lipid peroxidation
Candida antarctica lipase
Opis:
Oxidative stress enhances lipid peroxidation (LPO) implicated in cancer promotion and progression. (E)-4-Hydroxynon-2-enal 1 (trans-4-hydroxy-2-nonenal, HNE) is one of the most abundant products of LPO. Reactions of HNE with DNA and proteins are responsible for its mutagenic and toxic effects. On the other hand, HNE is regarded as a key molecule in stress mediated cell cycle signaling. LPO generates racemic HNE (rac-1); however, it is expected that the individual enantiomers will behave differently in their interactions with cell components. The study of HNE stereochemistry in its chemical and biochemical interactions is hindered by the lack of expedient methods for preparation of pure enantiomers. This study presents one step synthesis of HNE in a cross-metathesis reaction between the commercially available oct-1-en-3-ol and acrolein in the presence of 2nd generation Grubbs catalyst. The use in the metathesis reaction of enantiomers of oct-1-en-3-ol obtained via Candida antarctica lipase resolution of the racemate allowed us to prepare of 4-(R)- and 4-(S)-enantiomers of HNE (R-1 and S-1, respectively) with excellent optical purity (97.5 and 98.4% ee, respectively) and good chemical yields (70%).
Źródło:
Acta Biochimica Polonica; 2009, 56, 1; 189-193
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Occurrence of insomnia among patients with diagnosed obstructive sleep apnea
Autorzy:
Daniłosio, Marek
Wysocki, Jarosław
Prus, Monika
Powiązania:
https://bibliotekanauki.pl/articles/1399733.pdf
Data publikacji:
2018
Wydawca:
Index Copernicus International
Tematy:
obstructive sleep apnea
insomnia
Athens insomnia scale
correlation with sleep variables
Opis:
Obstructive sleep apnea (OSA) is a common problem. Excessive daytime sleepiness raises a suspicion of OSA, which can be confirmed by polysomnography (PSG). Insomnia, in patients with OSA, often manifests itself as excessive daytime drowsiness. The incidence of insomnia among patients with OSA differs in different studies. Thus, we investigated the incidence of insomnia among our patients. We included 120 patients who underwent a workup due to a suspicion of OSA in the Polysomnography Laboratory, Department of Otolaryngology, Medical University of Warsaw, Poland. Patients completed the Athens Insomnia Scale (AIS). All-night PSG was done with 14-channel recordings (Grass®, USA). The severity of OSA was classified according to the apnea-hypopnea index (AHI) values. There were 96 patients with OSA and 24 patients without OSA who served as controls (their sleep disorders and daytime drowsiness were not caused by OSA). The total AIS scores tended to indicate insomnia in the entire sample and in all different subgroups. The mean AIS score was significantly different between the subgroups differing in the severity of apnea. The mean AIS score correlated significantly with sleep latency, latent sleep, and N2 latency. The mean AIS score did not correlate significantly with the AHI. In conclusion, in patients with OSA, insomnia, measured with the AIS, was associated with the severity of apnea, although this relationship was weak.
Źródło:
Polski Przegląd Otorynolaryngologiczny; 2018, 7, 1; 16-23
2084-5308
2300-7338
Pojawia się w:
Polski Przegląd Otorynolaryngologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Agreement between Epworth Sleepiness Scale and objective sleep parameters in patients with excessive daytime sleepiness
Autorzy:
Daniłosio, Marek
Wysocki, Jarosław
Prus, Monika
Powiązania:
https://bibliotekanauki.pl/articles/1400398.pdf
Data publikacji:
2017
Wydawca:
Index Copernicus International
Tematy:
obstructive sleep apnea
excessive daytime sleepiness
Epworth Sleepiness Scale
correlation with sleep parameters
Opis:
Obstructive sleep apnea (OSA) is a disease with a broad social impact. Excessive daytime sleepiness raises suspicion of OSA and together with polysomnography (PSG) is the basis for diagnosis. The Epworth Sleepiness Scale (ESS) is used for objective assessment of daytime sleepiness. Many authors underline a high predictive value of this scale in selecting patients at risk of OSA. Moreover, there is a high agreement between the ESS and PSG. However, some authors oppose the use of this scale. We wanted to verify this issue based on our own data. We enrolled 120 patients who were referred to the Polysomnographic Laboratory, Department of Otolaryngology, Medical University of Warsaw with a suspicion of obstructive sleep apnea. All patients filled out the Epworth Sleepiness Scale. Overnight PSG was performed with 14-channel recordings (Grassm USA), including EEG, EMG, and recordings of the movements of the chest and abdomen. Airflow through the airways was recorded with a nasal-oral temperature probe. PSG was assessed automatically and manually; sleep stages were coded manually for each 30-second interval by a technician. Severity of OSA was assessed based on AHI. There were 96 patients with confirmed OSA and a control group of 24 patients with exclusion of OSA but with different disorders causing excessive daytime sleepiness. The average ESS scores were not significantly different between the subgroups, between genders, and in patients with different severity of OSA. ESS scores did not correlate significantly with any of the tested PSG parameters. In conclusion, the ESS should be used as an additional and only ancillary tool in assessing patients with suspected OSA.
Źródło:
Polski Przegląd Otorynolaryngologiczny; 2017, 6, 3; 10-18
2084-5308
2300-7338
Pojawia się w:
Polski Przegląd Otorynolaryngologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of undeveloped hard coal deposits and estimation of hard coal reserves in the Upper Silesian Coal Basin, Poland
Autorzy:
Urych, Tomasz
Chećko, Jarosław
Rosa, Marek
Wątor, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1839036.pdf
Data publikacji:
2020
Wydawca:
Główny Instytut Górnictwa
Tematy:
coal resources
coal reserves
3D geological model
Petrel software
Upper Silesian Coal Basin
zasoby węgla
geologiczny model 3D
oprogramowanie Petrel
Górnośląskie Zagłębie Węglowe
Opis:
The article presents the results of works concerning evaluation of undeveloped deposits in the Upper Silesian Coal Basin and an estimation of hard coal reserves which can be developed by 2050. Evaluation of hard coal deposits was established on criterions choice and their score determination. On the basis of obtained the final score and after consultations with experts in the field of hard coal mining, there were selected three areas of undeveloped deposits with the amount of about 1.99 Gt (billion metric tons) of anticipated economic resources which can extend the coal reserve base located in the direct vicinity of operating hard coal mines. Additionally, one undeveloped coal deposit with estimated resources amounts to about 1.15 Gt was selected as a potential deposit whose resources could be included in the reserves of operating mines, up to the depth of 1,500 metres. Deposit areas were selected and hard coal reserves were estimated with a view to building new coal mines. For Oświęcim-Polanka deposit, there was built a 3D geological model with estimated the amount of 924 Mt (million metric tons) of anticipated economic resources of coal. An example of a deposit development with ventilation, extraction and transport/haulage underground roadways connecting coal seams with the surface are presented. The designed mine working was placed in the 3D geological deposit model which is a useful tool for designing spatial deposit management.
Źródło:
Journal of Sustainable Mining; 2020, 19, 4; 230-242
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of exposure of the operators on the contact with the plant protection products during the spraying process
Ocena narażenia operatorów na kontakt ze środkami ochrony roślin podczas przeprowadzania zabiegów opryskiwania
Autorzy:
Brennensthul, Marek
Cieniawska, Beata
Czarnecki, Jarosław
Ptak, Weronika
Powiązania:
https://bibliotekanauki.pl/articles/1333467.pdf
Data publikacji:
2020-12-31
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Maszyn Rolniczych
Tematy:
plant protection
spraying
personal protective equipment
ochrona roślin
opryskiwanie
środki ochrony osobistej
Opis:
Plant protection products are one of the most dangerous substances in the agricultural working environment. The application of plant protection products by the broken implements or by wrong techniques can create the threats both for the operators, other people and for natural environment. The objective of this research was the evaluation of exposure of the sprayer operator on the liquid spray. Research was conducted for two types of the manual handling sprayers (backsprayer and shoulder-sprayer). To evaluate the exposure level the water-sensitive papers were used – they were placed on the elements of the workwear and personal protective equipment of operators. It was conclude that the highest exposure concerned the upper limbs (especially forearms) and the chest. Moreover, on the flat crop higher exposure on the liquid spray was observed for the shoulder-sprayer while on the orchard crop the differences between the sprayers in aspect of expo-sure were insignificant.
Środki ochrony roślin są jednymi z najniebezpieczniejszych substancji w rolniczym środowisku pracy. Aplikacja środków ochrony roślin przy użyciu niesprawnego sprzętu lub nieprawidłową techniką może stanowić zagrożenie dla osoby wykonującej opryskiwanie, dla osób postronnych oraz dla środowiska naturalnego. Celem pracy była ocena narażenia opera-tora opryskiwacza na kontakt z cieczą roboczą przy wykonywaniu zabiegu opryskiwania. Badania przeprowadzono dla dwóch typów opryskiwaczy ręcznych: plecakowego i biodrowego. Do oceny stopnia narażenia wykorzystano papierki wodoczułe, które umieszczono na elementach odzieży roboczej i środkach ochrony indywidualnej operatora. Wykazano, że największe narażenie na kontakt z cieczą użytkową dotyczyło kończyn górnych (zwłaszcza przedramion) oraz klatki piersiowej. Ponadto wykazano, że podczas zabiegu na uprawie płaskiej większe narażenie na kontakt z cieczą wystąpiło przy użyciu opryskiwacza biodrowego, zaś przy opryskiwaniu uprawy sadowniczej nie stwierdzono istotnego wpływu typu opryskiwacza na pokrycie ciała operatora cieczą użytkową.
Źródło:
Journal of Research and Applications in Agricultural Engineering; 2020, 65, 2; 4-8
1642-686X
2719-423X
Pojawia się w:
Journal of Research and Applications in Agricultural Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of dissection on the mechanical properties of human ascending aorta and human ascending aorta aneurysm
Autorzy:
Kozuń, Marta
Płonek, Tomasz
Jasiński, Marek
Filipiak, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/306886.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
tętniak
rozwarstwienie
aorta
aneurysm
dissection
ascending aorta
blood vessel wall
Opis:
The aim of the presented work is to determine (i) mechanical properties of the ascending aorta wall (DAA) and the wall of the ascending aortic aneurysm (DAAA), in which spontaneous dissection resulting from the evolving disease occurred, and (ii) the strength of the interface between the layers in the above-mentioned vessels. Methods: The mechanical tests were divided into two steps. In the first step the mechanical properties of the of DAA and DAAA walls were examined on the basis of uniaxial stretching until rapture. In the next step the mechanical parameters of the interface between layers of DAA and DAAA walls were determined by the peeling test. Results: Higher values of tensile strength (max) and Young’s modulus (E) were obtained for the DAAA group, to which the dissecting wall of the ascending aortic aneurysm was classified. For circumferential samples, the difference between the DAAA and DAA groups was 39% in the case of tensile strength and 70% in the case of the Young’s modulus. Conclusions: Summarizing, the studies performed showed that the dissection process is different in the case of the ascending aortic aneurysm wall and the ascending aorta wall. The wall of the ascending aortic aneurysm is more susceptible to dissection, as evidenced by lower values of the mechanical parameters of the interface between the intima and the media-adventitia complex. The obtained results of mechanical properties tests confirm that dissection and aneurysm should be treated as separate disease entities that may coexist with each other.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 2; 127-134
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of fatigue life of riveted joints in helicopter airframes
Autorzy:
Rośkowicz, Marek
Godzimirski, Jan
Jasztal, Michał
Gąsior, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1841763.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
riveted joints
hybrid joint
fatigue life
titanium driven blind bolts with pin
ordinary mushroom head rivets
Opis:
Using original cold-formed rivets in repairs of airframes of helicopters is difficult due to no access to inside parts of the airframe. Thus, the main aim of the study was to investigate the possibility to use the blind rivets or hybrid joints by verification the fatigue performance of such joints that must be better than with original rivets. Riveted and hybrid joints have been experimentally tested under static and fatigue loads. Furthermore, numerical calculations of stress distribution for strapped joint have been conducted. The test results covered fatigue life of lap joints and models of repaired airframe sheets using ordinary mushroom head rivets ref. 3558A-4-10, titanium driven blind bolts with pin, ref. MBF2110AB-05-150 and modified hybrid joints. Using titanium driven blind bolts with pin instead of ordinary hammer-bucked rivets, can improve the fatigue life of element made of aluminum alloy AW 2024T3. There are advantages of replacing riveted joints with modified hybrid (rivet & adhesive) joints in threefold increase in fatigue life of repaired airframe structures.
Źródło:
Eksploatacja i Niezawodność; 2021, 23, 1; 165-175
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of fatigue life of riveted joints in helicopter airframes
Autorzy:
Rośkowicz, Marek
Godzimirski, Jan
Jasztal, Michał
Gąsior, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1841792.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
riveted joints
hybrid joint
fatigue life
titanium driven blind bolts with pin
ordinary mushroom head rivets
Opis:
Using original cold-formed rivets in repairs of airframes of helicopters is difficult due to no access to inside parts of the airframe. Thus, the main aim of the study was to investigate the possibility to use the blind rivets or hybrid joints by verification the fatigue performance of such joints that must be better than with original rivets. Riveted and hybrid joints have been experimentally tested under static and fatigue loads. Furthermore, numerical calculations of stress distribution for strapped joint have been conducted. The test results covered fatigue life of lap joints and models of repaired airframe sheets using ordinary mushroom head rivets ref. 3558A-4-10, titanium driven blind bolts with pin, ref. MBF2110AB-05-150 and modified hybrid joints. Using titanium driven blind bolts with pin instead of ordinary hammer-bucked rivets, can improve the fatigue life of element made of aluminum alloy AW 2024T3. There are advantages of replacing riveted joints with modified hybrid (rivet & adhesive) joints in threefold increase in fatigue life of repaired airframe structures.
Źródło:
Eksploatacja i Niezawodność; 2021, 23, 1; 165-175
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the impact of forces and acceleration during the riding and braking of a suspended monorail
Autorzy:
Tokarczyk, Jarosław Andrzej
Rotkegel, Marek
Pytlik, Andrzej
Niedworok, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/219866.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
transport podziemny
podwieszana kolejka szynowa
badania
underground transportation
suspended monorail
research
load
Opis:
This article presents the results of experimental studies aimed at identifying the forces and acceleration during the riding and braking action of a suspended monorail. The tests were conducted under in situ conditions, in a dip-heading “B” ZG SILTECH in Zabrze. The paper also discusses a test stand, a metering system, and presents the impact of changes in speed on forces in slings of the suspended route. The measurements of selected parameters were performed for three variants: the route, the emergency haulage braking and the braking trolley set braking. The results include waveforms of forces in route slings, and acceleration values acting on the operator and transported load.
Źródło:
Archives of Mining Sciences; 2020, 65, 2; 399-414
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of shoulder mobility in women over 60 years of age after one-sided mastectomy
Ocena funkcji barku u kobiet po 60. roku życia leczonych z powodu raka piersi
Autorzy:
Włoch, Anna
Żak, Marek
Opuchlik, Anna
Biskup, Małgorzata
Fabiś, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/1798677.pdf
Data publikacji:
2016
Wydawca:
Akademia Wychowania Fizycznego im. Bronisława Czecha w Krakowie
Tematy:
mastectomy
shoulder
muscle strength
Range of Motion (ROM)
aged
mastektomia
bark
siła mięśniowa
zakres ruchomości
osoby starsze
Opis:
The overall risk of contracting various diseases, including breast cancer, increases with age. An on-going process of population ageing challenges modern physiotherapy with the need to have functional capacity in older people appreciably enhanced. The issue of anthropometric assessment of the range of motion and shoulder muscle strength is presently much underrated in the physical rehabilitation management of women patients after radical one-sided mastectomy. The study aimed to assess the functional mobility of a shoulder expressed as a range of motion, in conjunction with the assessment of shoulder muscle strength, in women patients over 60 years of age after radical one-sided mastectomy. The study comprised 24 patients (mean age 65 years) recruited from the Department of Rehabilitation, Holy Cross Cancer Centre, Kielce. All patients had undergone modifi ed radical mastectomy using the Madden technique, and an adjuvant therapy. The shoulder range of motion, i.e. flexion, abduction, internal and external rotation, was evaluated by a goniometer. Elevation, protraction and retraction movements were evaluated using an anthropometric device. A dynamometer was applied to assess the strength of select muscle groups within the shoulder during elevation, protraction and retraction motions. Statistical analysis was made with the aid of STATISTICA 12.0 software, having adopted a 0.05 alpha level as statistically signifi cant. The movements of fl exion, abduction and external rotation of the upper extremity were signifi cantly reduced on the mastectomy side. The range of motion and muscle strength during shoulder elevation, protraction and retraction were significantly diminished on the operated side (12% - 14%), compared to the non-operated one. 1. Functional mobility of the shoulder was signifi cantly reduced on the mastectomy side. 2. Results of the present study highlight the need to extend the scope of rehabilitation regimens offered to older women after radical one-sided mastectomy.
Wstęp: Z wiekiem wzrasta ryzyko zachorowania na różne choroby, w tym raka piersi. Postępujący proces starzenia się społeczeństw wymaga od współczesnej fizjoterapii zwiększenia sprawności funkcjonalnej osób starszych. Problem antropometrycznego pomiaru zakresu ruchu oraz siły mięśni barku jest słabo dostrzegany w procesie usprawniania pacjentek po mastektomii. Cel pracy: Celem badania była ocena funkcji barku wyrażonej w zakresie ruchu i siły mięśniowej u pacjentek po 60. r.ż., po mastektomii. Materiał i metody: Do badania zakwalifikowano 24 pacjentki (średnia wieku: 65 lat) w Zakładzie Rehabilitacji Świętokrzyskiego Centrum Onkologii w Kielcach. Wszystkie pacjentki były poddane zmodyfikowanej radykalnej mastektomii metodą Maddena oraz odpowiedniemu leczeniu uzupełniającemu. W Zakładzie Rehabilitacji zbadano zakres ruchomości stawów ramienno-łopatkowych podczas zgięcia, odwiedzenia, rotacji wewnętrznej oraz rotacji zewnętrznej za pomocą goniometru. Ruchy unoszenia, wysuwania do przodu (protrakcja) oraz cofania (retrakcja) barku oceniano za pomocą antropometru. Dynamometrem zbadano siłę wybranych grup mięśni barku podczas unoszenia, wysuwania do przodu oraz cofania. Analizę statystyczną wykonano za pomocą pakietu STATISTICA 12.0, przyjęto poziom alfa = 0,05. Wyniki: Ruchy zgięcia, odwodzenia i rotacji zewnętrznej kończyny górnej były istotnie statystycznie ograniczone po stronie operowanej piersi. Zakres ruchu oraz siła mięśni barku podczas unoszenia, wysuwania do przodu i cofania były istotnie statystycznie mniejsze po stronie wykonanej mastektomii (12%-14%) w stosunku do strony zdrowej. Wnioski: 1. Funkcja barku u kobiet po 60. roku życia, po stronie operowanej piersi jest znacząco ograniczona. 2. Przedstawione badania wskazują na konieczność poszerzenia zakresu rehabilitacji chorych w starszym wieku po leczeniu raka piersi.
Źródło:
Medical Rehabilitation; 2016, 20(4); 13-16
1427-9622
1896-3250
Pojawia się w:
Medical Rehabilitation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Insight Into Vibration Sources in Turbines
Autorzy:
Moneta, Grzegorz
Jachimowicz, Jerzy
Pietrzakowski, Marek
Doligalski, Adam
Szwedowicz, Jarosław
Powiązania:
https://bibliotekanauki.pl/articles/2105187.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
vibrations
blade
gas turbine
turbine engine
strain gauge
tip timing
Additive Manufacturing
Opis:
Despite of nearly 100 years of turbine engine development and design, blade vibrations remain a great engineering challenge. The rotating turbine blades’ vibrations lead to cyclic oscillations, which result in alternating stress and strain in harsh environments of high temperature and pressure. In modern aeroengines, high hot flow velocities might generate erosion and corrosion pitting on the metal surfaces, that leverage remarkably mean stresses. The combination of both mean and alternating stresses can lead to unexpected engine failures, especially under resonance conditions. Then, alternating stress amplitudes can exceed the safety endurance limit, what accelerates the high cyclic fatigue leading quickly to catastrophic failure of the blade. Concerning the existing state-of-the-art and new market demands, this paper revises forced vibrations with respect to excitation mechanisms related to three design levels: (i) a component like the blade design, (ii) turbine stage design consisting of vanes and blades and (iii) a system design of a combustor and turbine. This work reviews the best practices for preventing the crotating turbine and compressor blades from High Cyclic Fatigue in the design process. Finally, an engine commissioning is briefly weighed up all the pros and cons to the experimental validations and needed measuring equipment.
Źródło:
Fatigue of Aircraft Structures; 2021, 13; 40--53
2081-7738
2300-7591
Pojawia się w:
Fatigue of Aircraft Structures
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sound Transmission Through a Thin Plate with Shaped Frequency Response
Autorzy:
Wrona, Stanislaw
Mazur, Krzysztof
Rzepecki, Jaroslaw
Chraponska, Anna
Pawelczyk, Marek
Powiązania:
https://bibliotekanauki.pl/articles/177996.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
structural control
frequency response shaping
vibrating plate
optimisation
modelling
Opis:
Thin plates, in the form of individual panels or whole device casings, often separate the noise source from its recipients. It would be very desirable if the panels could effectively block the sound transmission preventing noise from further propagation. This is especially challenging to achieve at low frequencies. A promising approach, intensively developed in the recent years, is to employ active control methods by adding sensors and actuators, and running a control algorithm. However, if the noise is narrow-band, an alternative passive solution originally developed by the authors can be applied. It is based on appropriately located passive elements which can be used to alter the frequency response of the vibrating structure thus improving its sound insulation properties. Such an approach is referred to as the frequency response shaping method. The purpose of this paper is to further develop this method and apply it to a device casing panel. The efficiency of the method is evaluated by simulation and real experiments. Appropriate cost functions and mathematical models are formulated and used to optimise the arrangement of passive elements mounted to the plate, enhancing its sound insulation properties at the given frequency range. The results are reported, and advantages and limits of the method are pointed out and discussed.
Źródło:
Archives of Acoustics; 2019, 44, 4; 731-738
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of traction properties and power of wheels used on various agricultural soils
Analiza właściwości trakcyjnych oraz mocy kół eksploatowanych na różnych podłożach rolniczych
Autorzy:
Czarnecki, Jarosław
Brennensthul, Marek
Białczyk, Włodzimierz
Ptak, Weronika
Gil, Łukasz
Powiązania:
https://bibliotekanauki.pl/articles/93888.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Inżynierii Rolniczej
Tematy:
farm tractor
traction
towing power
traction efficiency
power
ciągnik rolniczy
trakcja
siła uciągu
sprawność trakcyjna
moc
Opis:
The paper presents results of the research on traction properties of two tractor tyres used on two agricultural grounds. The first ground was a stubble and the second one cropland. The investigated tyres had the same structure (diagonal, with a traditional tyre tread but different external dimensions. The research was carried out in field conditions with the use of a stand aggregated with a farm tractor. Analysis covered traction efficiency, slide, towing power and power lost on the rolling resistance and wheel slide. Based on the obtained results it was concluded that on a ground with lower compaction, the values of power losses were higher and traction efficiency was lower. Moreover, it was proved that the value of the power lost for rolling resistance had a decisive impact on the values of traction efficiency.
W pracy przedstawiono wyniki badań właściwości trakcyjnych dwóch opon ciągnikowych eksploatowanych na dwóch podłożach rolniczych. Pierwszym podłożem było ściernisko, natomiast drugim gleba uprawna. Badane opony posiadały taka samą konstrukcję (diagonalne, o klasycznej rzeźbie bieżnika), lecz odmienne wymiary zewnętrzne. Badania przeprowadzono warunkach polowych z wykorzystaniem stanowiska agregatowanego z ciągnikiem rolniczym. Analizowanymi właściwościami były sprawność trakcyjna, poślizg, moc uciągu oraz moce tracone na opór przetaczania i poślizg koła. Na podstawie uzyskanych wyników stwierdzono, że na podłożu o mniejszej zwięzłości wartości strat mocy były wyższe, a sprawność trakcyjna niższa. Ponadto wykazano, że wartość mocy traconej na opór przetaczania miała dominujący wpływ na wartości sprawności trakcyjnej.
Źródło:
Agricultural Engineering; 2019, 23, 1; 13-23
2083-1587
Pojawia się w:
Agricultural Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FXLMS with Multiple Error Switching for Active Noise-Cancelling Casings
Autorzy:
Mazur, Krzysztof
Wrona, Stanislaw
Chraponska, Anna
Rzepecki, Jaroslaw
Pawelczyk, Marek
Powiązania:
https://bibliotekanauki.pl/articles/176371.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
active noise control
adaptive control
active casing
Opis:
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.
Źródło:
Archives of Acoustics; 2019, 44, 4; 775-782
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
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