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    Tytuł:
    Single–server queueing system with limited queue, random volume customers and unlimited sectorized memory buffer
    Autorzy:
    Ziółkowski, Marcin
    Tikhonenko, Oleg
    Powiązania:
    https://bibliotekanauki.pl/articles/2173725.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    single-server queueing system
    queueing systems with random volume customers
    sectorized memory buffer
    total volume vector
    Laplace-Stieltjes transform
    system kolejkowy z jednym serwerem
    system kolejkowy z losowymi klientami
    bufor pamięci sektorowany
    wektor objętości całkowity
    transformata Laplace'a-Stieltjesa
    Opis:
    In the present paper, we analyze the model of a single–server queueing system with limited number of waiting positions, random volume customers and unlimited sectorized memory buffer. In such a system, the arriving customer is additionally characterized by a non– negative random volume vector whose indications usually represent the portions of unchanged information of a different type that are located in sectors of unlimited memory space dedicated for them during customer presence in the system. When the server ends the service of a customer, information immediately leaves the buffer, releasing resources of the proper sectors. We assume that in the investigated model, the service time of a customer is dependent on his volume vector characteristics. For such defined model, we obtain a general formula for steady–state joint distribution function of the total volume vector in terms of Laplace-Stieltjes transforms. We also present practical results for some special cases of the model together with formulae for steady–state initial moments of the analyzed random vector, in cases where the memory buffer is composed of at most two sectors. Some numerical computations illustrating obtained theoretical results are attached as well.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 6; art. no. e143647
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    M/G→ /n/0 Erlang queueing system with heterogeneous servers and non-homogeneous customers
    Autorzy:
    Ziółkowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/199840.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    multi-server queueing systems
    queueing systems with non-homogeneous customers
    queueing systems with heterogeneous servers
    total volume distribution
    Laplace–Stieltjes transform
    system kolejkowania
    transformata Laplace'a-Stieltjesa
    dystrybucja
    Opis:
    In the present paper, we investigate a multi-server queueing system with heterogeneous servers, unlimited memory space, and non-homogeneous customers. The arriving customers appear according to a stationary Poisson process. Service time distribution functions may be different for every server. Customers are additionally characterized by some random volume. On every server, the service time of the customer depends on their volume. The number of customers distribution function is obtained in the classical model of the system. In the model with non-homogeneous customers, the stationary total volume distribution function is determined in the term of Laplace–Stieltjes transform. The stationary first and second moments of a total customers volume are calculated. An analysis of some special cases of the model and some numerical examples are also included.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 1; 59-66
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Energetyczne określenie twardości Brinella
    Energy-based determination of Brinell hardnes
    Autorzy:
    Zatorski, Z.
    Biernat, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/221917.pdf
    Data publikacji:
    2014
    Wydawca:
    Akademia Marynarki Wojennej. Wydział Dowodzenia i Operacji Morskich
    Tematy:
    twardość Brinella
    energie właściwe odkształceń
    materiały sprężysto-plastyczne
    odkształcenia całkowite sprężyste
    Brinell hardness
    proper energies of strains
    materials elastic-plastic
    volume of total
    Opis:
    W artykule zweryfikowano energetycznie twardość Brinella materiałów konstrukcyjnych. Badania realizowano w Akademii Marynarki Wojennej w Gdyni przy użyciu oprzyrządowanych maszyn wytrzymałościowych MTS 810.12 i FU 1000. Analiza wykresów siła — głębokość odcisku służyła do wyznaczenia energii właściwych odkształceń sprężystych, plastycznych i całkowitych absorbowanych przez materiał. Energie właściwe wyznaczono przez podzielenie odpowiednich wartości energii przez objętość odkształceń całkowitych, sprężystych oraz plastycznych odcisku.
    This article presents energy-based verification of Brinell hardness in construction materials. The investigations were conducted at the Naval Academy in Gdynia using testing machines MTS 810.12 and FU 1000. The analysis of force-indentation depth diagrams was used to determine proper energies of elastic, plastic and total strains being absorbed by the material. In order to determine the proper energies the appropriate energy values were divided by the volume of total, elastic and plastic strains of the indentation.
    Źródło:
    Zeszyty Naukowe Akademii Marynarki Wojennej; 2014, R. 55 nr 4 (199), 4 (199); 103-116
    0860-889X
    Pojawia się w:
    Zeszyty Naukowe Akademii Marynarki Wojennej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Expected volumes of requests in systems of the queueing network with a limited number of waiting places
    Autorzy:
    Zając, P.
    Matalytski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/121834.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
    Tematy:
    sieci HM
    sieci kolejkowe
    system kolejkowy
    bezprzewodowy punkt dostępu
    HM-networks
    queueing network
    single-line queueing system
    queueing system
    queuing time
    limited queue
    demands total volume
    wireless access point
    volume of requests
    Opis:
    We present a method of finding the expected volume of requests in HM-network with homogeneous requests and bypass of the queueing systems of requests. The case was considered when the volume changes associated with the transitions between the states of the network are deterministic functions, depending on the state of the network and time, and the systems are single line. It is assumed that the probability of the states of the network systems, the parameters of the entrance flow of the requests and the service depend on the time.
    Źródło:
    Scientific Issues of Jan Długosz University in Częstochowa. Mathematics; 2017, 22; 141-160
    2450-9302
    Pojawia się w:
    Scientific Issues of Jan Długosz University in Częstochowa. Mathematics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Repetitive apneas reduce nonlinear dynamical complexity of the human cardiovascular control system
    Autorzy:
    Trzebski, A.
    Smietanowski, M.
    Zebrowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/70116.pdf
    Data publikacji:
    2001
    Wydawca:
    Polskie Towarzystwo Fizjologiczne
    Tematy:
    total peripheral resistance
    arterial chemoreceptor
    apnea
    man
    stroke volume
    hypertension
    cardiac output
    nonlinear dynamics
    cardiovascular control
    blood pressure
    Źródło:
    Journal of Physiology and Pharmacology; 2001, 52, 1
    0867-5910
    Pojawia się w:
    Journal of Physiology and Pharmacology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Queueing systems with random volume customers and a sectorized unlimited memory buffer
    Autorzy:
    Tikhonenko, Oleg
    Ziółkowski, Marcin
    Kempa, Wojciech M.
    Powiązania:
    https://bibliotekanauki.pl/articles/2055163.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    queueing system
    random volume customers
    sectorized memory buffer
    total volume vector
    Laplace transform
    Laplace–Stieltjes transform
    multivariate L’Hospital rule
    system kolejkowania
    wektor objętości
    transformata Laplace'a
    transformata Laplace'a-Stieltjesa
    Opis:
    In the present paper, we concentrate on basic concepts connected with the theory of queueing systems with random volume customers and a sectorized unlimited memory buffer. In such systems, the arriving customers are additionally characterized by a non-negative random volume vector. The vector’s indications can be understood as the sizes of portions of information of a different type that are located in the sectors of memory space of the system during customers’ sojourn in it. This information does not change while a customer is present in the system. After service termination, information immediately leaves the buffer, releasing its resources. In analyzed models, the service time of a customer is assumed to be dependent on his volume vector characteristics, which has influence on the total volume vector distribution. We investigate three types of such queueing systems: the Erlang queueing system, the single-server queueing system with unlimited queue and the egalitarian processor sharing system. For these models, we obtain a joint distribution function of the total volume vector in terms of Laplace (or Laplace-Stieltjes) transforms and formulae for steady-state initial mixed moments of the analyzed random vector, in the case when the memory buffer is composed of two sectors. We also calculate these characteristics for some practical case in which the service time of a customer is proportional to the customer’s length (understood as the sum of the volume vector’s indications). Moreover, we present some numerical computations illustrating theoretical results.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2021, 31, 3; 471--486
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Multiline queueing system with random time limitations and limited buffer space
    Autorzy:
    Tikhonenko, O.
    Zając, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/122703.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    total demands volume
    system buffer capacity
    loss probability
    Stieltjes convolution
    system kolejkowy
    splot Stieltjesa
    pojemność bufora
    Opis:
    In the paper, we investigate multi-server queueing systems with demands of random space requirements (volumes), in which buffer space is limited by constant value and queueing ore (and) service time are limited by exponentially distributed random variables. For such systems, stationary demands number distribution and loss probability are determined. Some numerical results are attached as well.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 4; 99-106
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance evaluation of an M/G/n-type queue with bounded capacity and packet dropping
    Autorzy:
    Tikhonenko, O.
    Kempa, W. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/331288.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    AQM algorithm
    finite buffer
    loss probability
    total packet volume
    queue size distribution
    aktywne zarządzanie kolejką
    prawdopodobieństwo straty
    rozkład wielkości kolejki
    Opis:
    A queueing system of the M/G/n-type, n ≥ 1, with a bounded total volume is considered. It is assumed that the volumes of the arriving packets are generally distributed random variables. Moreover, the AQM-type mechanism is used to control the actual buffer state: each of the arriving packets is dropped with a probability depending on its volume and the occupied volume of the system at the pre-arrival epoch. The explicit formulae for the stationary queue-size distribution and the loss probability are found. Numerical examples illustrating theoretical formulae are given as well.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2016, 26, 4; 841-854
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance evaluation of unreliable system with infinite number of servers
    Autorzy:
    Tikhonenko, O.
    Ziółkowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/201519.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    queueing systems with non-homogeneous customers
    unreliable queueing systems
    total volume
    loss probability
    Laplace–Stieltjes transform
    Opis:
    In the paper, we investigate queueing system M/G/∞ with non-homogeneous customers. By non-homogeneity we mean that each customer is characterized by some arbitrarily distributed random volume. The arriving customers appear according to a stationary Poisson process. Service time of a customer is proportional to his its volume. The system is unreliable, which means that all its servers can break simultaneously and then the repair period goes on for random time having an arbitrary distribution. During this period, customers present in the system and arriving to it are not served. Their service continues immediately after repair period termination. Time intervals of the system in good repair mode have an exponential distribution. For such system, we determine steady-state sojourn time and total volume of customers present in it distributions. We also estimate the loss probability for the similar system with limited total volume. An analysis of some special cases and some numerical examples are attached as well.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 2; 289-297
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Single-server queueing system with external and internal customers
    Autorzy:
    Tikhonenko, O.
    Ziółkowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/199838.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    single-server queueing system with non-homogeneous customers
    random volume customers
    loss probability
    total volume distribution
    Laplace transform
    Laplace-Stieltjes transform
    RAM memory space
    prawdopodobieństwo straty
    transformacja Laplace'a
    transformata Laplace'a-Stieltjesa
    pamięć RAM
    Opis:
    In the paper, we investigate a single-server queueing system with unlimited memory space and non-homogeneous customers (calls) of the two following types: 1) external customers that are served by the system under consideration, 2) internal customers that arrive and interrupt the service process only when an external customer is being served. The external customers appear according to a stationary Poisson process. Customers of each of the above-mentioned types are characterized by some random volume. The customer service time depends arbitrarily on its volume. Two schemes of customer service organization are analyzed. The non-stationary and stationary distributions of the total volume of customers present in the system are determined in terms of Laplace and Laplace-Stieltjes transforms. The stationary first and second moments of total customers volume are also calculated. The obtained results are used to approximate loss characteristics in analogous systems with limited buffer space. Numerical examples illustrating theoretical results are attached as well.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 4; 539-551
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Juvenile wood volume and its proportion to stem volume vs. selected biometric features of Scots pine [Pinus sylvestris L.] trees
    Autorzy:
    Pazdrowski, W
    Tomczak, A.
    Kupczyk, G.
    Jelonek, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/57743.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    breast height diameter
    tree height
    Scotch pine
    total stem volume
    determination coefficient
    juvenile wood
    Pinus sylvestris
    tree
    wood
    forest site type
    Opis:
    The aim of the study was to determine whether there is a correlation between breast height diameter, tree height and stem total volume of Scots pines, on the one hand, and volume and proportion of juvenile wood, on the other. The investigations comprised pure pine stands of the IInd, IIIrd, IVth and Vth age classes developed in conditions of fresh mixed coniferous forest. A distinct curvilinear correlation was found between volume and proportion of juvenile wood in tree stems and breast height diameter, height and stem total volume. Because of high values of determination coefficients (R2), which characterised the above-mentioned correlations, it seems appropriate to use these regularities to assess the quality of the timber raw material regarding the proportions of its volume and juvenile wood in stems of Scots pine trees.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2005, 74, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ocena przyrostu całkowitej objętości nerek u dzieci i młodych dorosłych z wielotorbielowatością nerek o autosomalnie dominującym typie dziedziczenia w trakcie 12-miesięcznej obserwacji – doniesienie wstępne
    12-month assessment of increase in total kidney volume in children and young adults with autosomal dominant polycystic kidney disease – a pilot study
    Autorzy:
    Pawlak-Bratkowska, Monika
    Afshari, Susan
    Grzelak, Piotr
    Podgórki, Michał
    Wosiak, Agnieszka
    Młudzik, Agnieszka
    Michalak, Krzysztof
    Kostrzewa, Marta
    Faltin, Kamil
    Tkaczyk, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/1036277.pdf
    Data publikacji:
    2017
    Wydawca:
    Śląski Uniwersytet Medyczny w Katowicach
    Tematy:
    dzieci
    adpkd
    całkowita objętość nerek
    torbielowatość
    progresja choroby
    children
    total kidney volume
    polycystic
    disease progression
    Opis:
    WSTĘP: Autosomalna dominująca wielotorbielowatość nerek (ADPKD – autosomal dominant polycystic kidney disease) to najczęstsza z dziedziczonych monogenowo chorób nerek. Stanowi przyczynę schyłkowej niewydolności nerek u 5–10% dorosłych leczonych nerkozastępczo. Dawniej uważana była za chorobę ludzi dorosłych, lecz od czasu upowszechnienia badań ultrasonograficznych zaczęto obserwować jej występowanie także u dzieci. MATERIAŁ I METODY: Grupę badaną stanowiło 19 pacjentów z prawidłową czynnością nerek (w wieku 1,8–18,8 roku w trakcie kontroli, 12 dziewczynek, 7 chłopców) chorujących na ADPKD. Spośród pacjentów 15 spełniało ultrasonograficzne kryteria rozpoznania choroby, a 4 nie spełniało kryteriów, przy czym były to dzieci z dodatnim wywiadem rodzinnym w kierunku ADPKD, a w USG stwierdzono minimum 2 torbiele. Całkowita objętość nerek (TKV), określona jako suma objętości obu nerek, została odniesiona do powierzchni ciała pacjenta (TKV/BSA). Dzieci badane były średnio co 12 miesięcy. WYNIKI: W badanej grupie stwierdzono istotny statystycznie roczny przyrost całkowitej objętości nerek (w 2015 r. 296,71 ± 178,67 cm3 vs. 350,38 ± 195,86 cm3 w 2016 r.; p = 0,019) oraz także TKV w odniesieniu do powierzchni ciała (w 2015 r. 191,23 ± 86,29 cm3/m2 vs. 221,15 ± 96,99 cm3/m2 w 2016 r.; p = 0,037). Nie uwidoczniono różnic w tempie przyrost całkowitej objętości nerek w zależności od płci (dziewczynki 32,45 ± 51,88 cm3/m2/rok vs. chłopcy 25,56 ± 71,00 cm3/m2/rok; p = 0,81) oraz ze względu na zaawansowanie choroby, ocenianej jako liczba stwierdzonych w badaniu ultrasonograficznym torbieli w obrębie nerek (< 5 torbieli 30,77 ± 61,6 cm3/m2/rok vs. ≥ 5 torbieli 29,41 ± 58,22 cm3/m2/rok; p = 0,96). WNIOSKI: U dzieci i młodych dorosłych z ADPKD można zaobserwować zwiększenie względnej całkowitej objętości nerek (w odniesieniu do BSA) już w trakcie 12-miesięcznej obserwacji.
    INTRODUCTION: Autosomal dominant polycystic kidney disease (ADPKD) is the most common type of monogenic kidney disease. It is the cause of ESRD in 5–10% of adult patients who undergo renal replacement therapy. Owing to the increasing use of ultrasonography, occurrence of the disease has been observed among children. MATERIAL AND METHODS: The research group consisted of 19 patients with normal kidney function (12 girls and 7 boys aged 1.8–18.8 at the moment of examination) who suffered from ADPKD. 15 patients met the ultrasonographic criteria of the diagnosis. Although the remaining 4 patients did not meet the criteria, they had a strong family history of ADPKD and underwent USG which revealed at least 2 cysts. For each patient, the Total Kidney Volume (TKV), defined as the sum volume of both kidneys, was juxtaposed with BSA. The children underwent the examination approximately every 12 months. RESULTS: The members of the research group manifested a statistically significant annual increase in TKV (in 2015, 296.71 ± 178.67 cm3 versus 350.38 ± 195.86 cm3 in 2016, p = 0.019), as well as TKV in relation to body surface (in 2015, 191.23 ± 86.29 cm3/m2 versus 221.15 ± 96.99 cm3/m2 in 2016, p = 0.037). There were no apparent differences in the rate of total TKV increase which would depend either on the patient's gender (girls 32.45 ± 51.88 cm3/m2/year versus boys 25.56 ± 71.00 cm3/m2/year, p = 0.81), or on the number of renal cysts revealed by USG (< 5 cysts 30.77 ± 61.6 cm3/m2/year versus ≥ 5 cysts 29.41 ± 58.22 cm3/m2/year, p = 0.96). CONCLUSION: In children and young adults with ADPKD, the increase in total kidney volume (in relation to BSA) can be observed after a 12-month observation.
    Źródło:
    Annales Academiae Medicae Silesiensis; 2017, 71; 109-115
    1734-025X
    Pojawia się w:
    Annales Academiae Medicae Silesiensis
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Enhancement of tribological properties and characteristic of polymer matrix composite (UHMWPE reinforced with short fibres of polyester) for Total Disc Replacement (TDR)
    Autorzy:
    Obaid, M. N.
    Radhi, S. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818822.pdf
    Data publikacji:
    2020
    Wydawca:
    Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
    Tematy:
    total disc replacement
    UHMWPE
    polyester fibres
    tribological
    contact angle
    crystalline degree
    roughness
    melting temperature
    volume loss
    całkowita wymiana dysku
    całkowita endoprotezoplastyka krążka międzykręgowego
    włókna poliestrowe
    tribologia
    kąt zwilżania
    stopień krystaliczności
    chropowatość
    temperatura topnienia
    utrata objętości
    Opis:
    Purpose: The number of people suffering from Degenerative Disc Disease (DDD) is increasing. The disease causes heavy pain and restrict a number of day-to-day life activities. In extreme cases, the degraded disc is removed under total disc replacement which is usually made up of Ultra-High Molecular Weight Polyethylene (UHMWPE). The material has astounding biocompatible characteristics mechanical properties and wear resistance. However, these characteristics are insufficient in arthroplasty application. Therefore, research investigations are ongoing to improve tribological properties through reinforcement that may result in a composite material of UHMWPE. Thus the current study is aimed at reinforcing UHMWPE with short fibres of polyesters to enhance the tribological properties and surface characteristic so as to improve wear resistance and nourish the fibroblast cells on synthetic disc. Design/methodology/approach: The researcher prepared UHMWPE composite material, reinforced with different weight fractions of short polyester fibres (2, 4, 6, 8 and 10% following hot press method. Further pin-on-disc device was used to study the tribological properties (coefficient of friction and volume of wear). The study tested surface roughness and surface characteristics by atomic force microscopy (AFM) device, hardness by shore D device, contact angle to study the effect of polyester short fibres on wettability of UHMWPE surface and tested the thermal properties and crystalline degree using Differential Scanning Calorimetry measurement (DSC) device. Findings: The results infer that the wear resistance got improved when using 2% w.t polyester though it got decreased initially. However, the value was still more than neat UHMWPE. There was a decrease observed in coefficient of friction, but after 4 w.t% polyester, the coefficient of friction got increased due to increasing percentage of fibres which make it harder and stiff compared to UHMWPE. There was a decline observed in surface roughness due to alignment of the fibres with smooth surface. The contact angle got increased in a moderate range while the roughness enhanced the growth of fibroblast cell. The hardness of composite material got increased, because the fibres turned stiffer and harder than the matrix. DSC results infer the improvements in thermal stability due to high thermal properties of polyester fibres compared to UHMWPE. The degree of crystallinity got increased which in turn enhanced wear resistance, especially at 6 w.t % polyester fibres. There was a mild increase observed in density since the density of polyester is higher than polymer. Research limitations/implications: The major challenge was the dispersion of fibres. Uniform distribution of fibres within the matrix (UHMWPE) was achieved through two steps of mixing processes such as mechanical mixture and twin extruder. In future studies, fatigue tests must be conducted to study the behaviour of prepared composite materials under fatigue cycle. Practical implications: A significant objective is how to connect among different properties to obtain good improvement in tribological and surface properties so as to enhance wear resistance and growth of fibrolase cells. Originality/value: In this study, polymeric short fibres were used as reinforcement with polymeric matrix to enhance the wettability of fibres with matrix. In this way, the bonding among them got increased which supports the tribological, surface, and crystalline behaviour.
    Źródło:
    Journal of Achievements in Materials and Manufacturing Engineering; 2020, 102, 2; 55--65
    1734-8412
    Pojawia się w:
    Journal of Achievements in Materials and Manufacturing Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of Total Tumor Volume, Size and Number of Colorectal Liver Metastases in Prediction of Survival in Patients after Liver Resection
    Autorzy:
    Hołówko, Wacław
    Grąt, Michał
    Wronka, Karolina Maria
    Stypułkowski, Jan
    Roszkowski, Rafał
    Studnicki, Paweł
    Krawczyk, Marek
    Powiązania:
    https://bibliotekanauki.pl/articles/1395543.pdf
    Data publikacji:
    2015-02-01
    Wydawca:
    Index Copernicus International
    Tematy:
    colorectal liver metastases
    liver resection
    total tumor volume
    Opis:
    Liver is the most common location of the colorectal cancer metastases occurrence. Liver resection is the only curative method of treatment. Unfortunately it is feasible only in 25% of patients with colorectal liver metastases, often because of the extensiveness of the disease. The aim of the study was to evaluate the predictive value of total tumor volume, size and number of colorectal liver metastases in patients treated with right hemihepatectomy. Material and methods. A retrospective analysis was performed in a group of 135 patients with colorectal liver metastases, who were treated with right hemihepatectomy. Total tumor volume was estimated based on the formula (4/3)πr3. Moreover, the study included an analysis of data on the number and size of tumors, radicality of the resection, time between primary tumor resection and liver resection, pre-operative blood serum concentration of carcinoembryonal antigen (CEA) and carcinoma antigen Ca19-9. The predictive value of the factors was evaluated by applying a Cox proportional hazards model and the area under the ROC curve. Results. The univariate analysis has shown the predictive value of size of the largest tumor (p=0.033; HR=1.065 per each cm) on the overall survival, however no predictive value of number of tumors (p=0.997; HR=1.000) and total tumor volume (p=0.212; HR=1.002) was observed. The multivariate analysis did not confirm the predictive value of the size of the largest tumor (p=0.141; HR=1.056). In the analysis of ROC curves, AUROC for the total tumor volume, the size of the largest tumor and the number of tumors were 0.629, 0.608, 0.520, respectively. Conclusions. Total tumor volume, size and number of liver metastases are not independent risk factors for the worse overall survival of patients with colorectal liver metastases treated with liver resection, therefore increased values of these factors should not be a contraindication for surgical treatment
    Źródło:
    Polish Journal of Surgery; 2015, 87, 2; 53-58
    0032-373X
    2299-2847
    Pojawia się w:
    Polish Journal of Surgery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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