Autor: Gutierrez, J. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Viscosity and creep compliance of polyoxymethylene copolymers of various average molecular weights
Lepkość i podatność na pełzanie kopolimerów polioksymetylenowych o różnych średnich ciężarach cząsteczkowych
Autorzy:: Gonzalez-Gutierrez, J.
Oblak, P.
Megen, Z. M.
Emri, I.
Tematy:: polyoxymethylene
molecular weight
viscosity
creep compliance
activation energy
polioksymetylen
ciężar cząsteczkowy
lepkość
podatność na pełzanie
energia aktywacji; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Powiązania:: https://bibliotekanauki.pl/articles/947533.pdf Link otwiera się w nowym oknie
Opis:: The effect of average molecular weight (M_w) of polyoxymethylene (POM) on melt viscosity and solid state creep compliance were investigated. Viscosity follows the power function of M_w. Creep compliance results indicate that time-temperature superposition applies to POM copolymers. Creep compliance in ashort time (0.25 s) is independent of M_w, but in a longer time (10 years) it follows an inverse power law relation with M_w, up to a critical value of M_w = 81 100, where creep compliance becomes independent of M_w. At intermediate time (17 min), similar to short one, no effect on susceptibility to creep compliance was observed. It was also stated that the activation energy is independent of M_w.
Zbadano wpływ średniego ciężaru cząsteczkowego (M_w) wybranych kopolimerów polioksymetylenowych (POM) na lepkość stopu i podatność na pełzanie próbki w stanie stałym. Stwierdzono, że w przypadku wszystkich badanych kopolimerów POM zależność lepkości od M_w opisuje funkcja potęgowa. Wyniki badań podatności na pełzanie wykazały zgodność z zasadą równoważności temperaturowo-czasowej. Podatność na pełzanie w krótkim czasie (0,25 s) była niezależna od M_w, natomiast w czasie dłuższym (10 lat) wielkość ta zmniejszała się ze zwiększaniem M_w, aż do wartości krytycznej M_c = 81 100, po której nie zależała już od M_w. W średnim czasie (17 min), podobnie jak w czasie krótkim, M_w nie wpływał na podatność na pełzanie. Zaobserwowano również, że energia aktywacji nie jest funkcją M_w.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Numerical and Experimental Analysis for Shape Improvement of a Cruciform Composite Laminates Specimen
Numeryczna i eksperymentalna analiza poprawy kształtu próbek o kształcie krzyżowym wykonanych z laminatu
Autorzy:: Gutiérrez, J. C.
Lozano, A.
Manzano, A.
Flores, M. S.
Tematy:: polymer-matrix composites
PMC
mechanical properties
finite element analysis
FEA
non-destructive testing
Biaxial testing
cruciform specimen
kompozyty z matrycą polimerową
właściwości mechaniczne
analiza metodą elementów skończonych
badania nieniszczące
testowanie dwuosiowe; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Powiązania:: https://bibliotekanauki.pl/articles/234347.pdf Link otwiera się w nowym oknie
Opis:: The use of composite materials has spread to different applications among which, those using thin sheet plates subjected to biaxial loads are commonly used in the car and aerospace industries. Hence, there is need of a reliable specimen to test these materials under biaxial loads. This reliability depends on measurements that are accurate and repeatable. Thus these measurements depend on the proper design of specimens. This paper reviews the development of cruciform specimens of carbon fibre composite materials and how the geometric shape has evolved. Based on this review, a new geometric shape is proposed. This improvement is based on numerical analysis of the specimen and tests results of experimental measurements carried out using a four piston rig in an orthogonal arrangement. Deformation is measured in the centre of the specimen using strain gauges. By obtaining the principal stresses, it was found that maximum stresses occur in the centre of the specimen.
Powszechnie stosowane są kompozyty poddawane testom dwuosiowym. Prawidłowe przeprowadzenie tego rodzaju testów jest trudne biorąc pod uwagę rozkład naprężeń badanych w próbce. Omówiono szereg struktur stosowanych dla uzyskania wyników dokładnych i powtarzalnych. Przeprowadzono analizę poprawy kształtu próbki rozpatrując laminat z udziałem włókien węglowych i żywicy epoksydowej. Przeprowadzono testy rozciągania dwuosiowego. Odkształcenia mierzono w centralnej części próbki stosując specjalne czujniki przesunięcia. Stwierdzono, że maksymalne naprężenia występują w środku próbki.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Notes on the identity of the male paralectotype of Thecla heodes and description of a new species : Strymon cryptodes sp. nov. from northern Peru (Lepidoptera: Lycaenidae)
Autorzy:: Boyer, P.
Pyrcz, Tomasz
Cerdeña Gutiérrez, J.
Bálint, Zs.
Florczyk, Klaudia
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 4.

Tytuł:: Brachiopods from the uppermost Lower Ordovician of Peru and their palaeogeographical significance
Autorzy:: Gutierrez-Marco, J C
Villas, E.
Tematy:: systematics
Peru
Celtic Province
Lower Ordovician
brachiopod
Ordovician
geological setting
paleogeography
Ahtiella
geographic setting
Brachiopoda
paleontology; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/22645.pdf Link otwiera się w nowym oknie
Opis:: The studied brachiopod assemblages from the uppermost Lower Ordovician beds of Peru are of very low diversity and are among the northernmost known strata of that age in South America. They have been collected at the Carcel Puncco canyon of the Inambari River, near San Gabán in the easternmost Eastern Cordillera. Of the six species described, Euorthisina orthiformis and Paralenorthis immitatrix were already known from the Bolivian outcrops of the same Andean Eastern Cordillera; two species are new: Ahtiella zarelae Villas sp. nov. and Paralenorthis carlottoi Villas sp. nov. The new species of Ahtiella, of late Floian age, represent the oldest record of the genus characteristic of Celtic assemblages. During the early Mid Ordovician the genus migrated eastward from this region into the north margin of proto−Avalonia and after that, in Llanvirn times, into Baltica. During the early Llanvirn Ahtiella also migrated westward reaching the Precordillera Argentina region. Brachiopod faunal affinities suggest that there was a closer proximity of Avalonia with the Central Andean Basin, in similar temperate latitudes, than with the Southwestern European Platform, placed in very high latitude. Paralenorthis does not give any palaeogeographical signal, since it is known from all latitudes and palaeocontinents. Nevertheless, the occurrence of Euorthisina reinforces the Gondwanan signature of the region, since this genus spread during the Arenig throughout the middle latitude belt at the Gondwana margins, although it also colonised sub−polar latitudes, coinciding with the Llanvirn transgression over North Gondwana.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Orthid brachiopods from the Middle Ordovician of the Central Iberian Zone, Spain
Autorzy:: Reyes-Abril, J
Villas, E.
Gutierrez-Marco, J.C.
Wydawca:: Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/20339.pdf Link otwiera się w nowym oknie
Opis:: The present study of a large collection of orthid brachiopods from Middle Ordovician (middle Darriwilian) strata of Spanish regions of the Central Iberian Zone of the Iberian Massif, as well as the type collection of Portuguese species from the same Zone, revealed the occurrence of five genera of the family Orthidae, two of them new, and to which most of the seven previously reported species of Orthis from the same areas can be assigned. Besides the two new genera and species Almadenorthis auriculata Reyes−Abril and Villas gen. et sp. nov., and Gutiorthis incurvata Reyes−Abril and Villas gen. et sp. nov., three further new species are erected: Paralenorthis estenaensis Reyes−Abril and Villas sp. nov., Paralenorthis lolae Reyes−Abril and Villas sp. nov., and Sivorthis calatravaensis Reyes−Abril and Villas sp. nov. Paralenorthis alata and Orthambonites sp. are also identified in the same beds. Orthis noctilio is ascribed to the genus Sivorthis, and the species Orthis lusitanica and Orthis miniensis are restricted to only their type specimens. Orthis duriensisis poorly described and illustrated, its type material missing, and actually it may belong to Sivorthis noctilio. These brachiopod taxa invaded the cold waters of the Afro−South European Gondwanan margin from lower latitudes, coincident with the mid Darriwilian transgression, as they belonged to a family that diversified in temperate and tropical seas during the early Mid Ordovician.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: A genetic algorithm for the maximum 2-packing set problem
Autorzy:: Trejo-Sánchez, Joel Antonio
Fajardo-Delgado, Daniel
Gutierrez-Garcia, J. Octavio
Tematy:: maximum 2-packing set
genetic algorithms
graph algorithms
algorytm genetyczny
algorytm grafowy; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/330154.pdf Link otwiera się w nowym oknie
Opis:: Given an undirected connected graph G = (V, E), a subset of vertices S is a maximum 2-packing set if the number of edges in the shortest path between any pair of vertices in S is at least 3 and S has the maximum cardinality. In this paper, we present a genetic algorithm for the maximum 2-packing set problem on arbitrary graphs, which is an NP-hard problem. To the best of our knowledge, this work is a pioneering effort to tackle this problem for arbitrary graphs. For comparison, we extended and outperformed a well-known genetic algorithm originally designed for the maximum independent set problem. We also compared our genetic algorithm with a polynomial-time one for the maximum 2-packing set problem on cactus graphs. Empirical results show that our genetic algorithm is capable of finding 2-packing sets with a cardinality relatively close (or equal) to that of the maximum 2-packing sets. Moreover, the cardinality of the 2-packing sets found by our genetic algorithm increases linearly with the number of vertices and with a larger population and a larger number of generations. Furthermore, we provide a theoretical proof demonstrating that our genetic algorithm increases the fitness for each candidate solution when certain conditions are met.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Two significant experiences related to radon in a high risk area in Spain
Autorzy:: Sainz, C.
Gutierrez-Villanueva, J. -L.
Fuente, I.
Quindos, L.
Soto, J.
Arteche, J. -L.
Quindos Poncela, L. S.
Tematy:: radon
workplace
mitigation
pilot house; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148910.pdf Link otwiera się w nowym oknie
Opis:: Radon is a natural radioactive gas and it is currently accepted as being responsible for lung cancer in some cases. One of the most important sources of indoor radon is from the soil. The radium content of soil is also a very important factor to be taken into account. The natural radiation map of Spain (MARNA) classifies the country into three regions with different levels of natural gamma radiation. There are some areas in Spain with high levels of natural radiation one of those is the province of Salamanca. Western part of this province presents a population of 20 000 inhabitants and 7% of the houses have an indoor radon concentration above 400 Bqźm–3. In this high risk area, the village of Villar de la Yegua is of special interest: 11% of the houses in this village have an indoor radon level below 400 Bqźm–3, 89 per cent have above 400 Bqźm–3 and 71 per cent of the houses have a radon concentration above 1000 Bqźm–3. An old uranium mine site close to this village has been selected for the construction of an experimental pilot house. It is a two story house located in the place with a very high 226Ra concentration in soil. Radon in soil at 1 m depth has an average level of 250 kBqźm–3. We present in this work the characteristics of the experimental unit located in this high risk area and we describe the zone where one of the Spanish villages with the highest radon concentration is located. This is a very interesting place for further research on indoor radon concentration and it is a unique opportunity of testing radon monitors, radon passive detectors and remedial actions for the mitigation of radon in real conditions. It is common to carry out intercomparison exercises under laboratory conditions. Nonetheless, it is not so common to develop these exercises in real conditions as we have in the experimental unit we present here. We offer in this work the possibility for other research groups of testing their equipments in this unit and we also show the evolution of the works carried out in the locality of Villar de la Yegua.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: The Laboratory of Natural Radiation (LNR) : a place to test radon instruments under variable conditions of radon concentration and climatic variables
Autorzy:: Quindós Poncela, L. S.
Sainz Fernández, C.
Gutiérrez-Villanueva, J.-L.
Fuente Merino, I.
Celaya González, C.
Quindós López, L.
Quindós López, J.
Fernández Lopez, E.
Fernández Villar, A.
Tematy:: active monitors
interlaboratory comparison
in-situ
radon; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/147764.pdf Link otwiera się w nowym oknie
Opis:: The publication of the new European Union Basic Safety Standards represents a remarkable milestone in the fi eld of radiological protection in terms of adding radon exposure to this framework. Therefore, the coming years will bring the need to measure radon not only in the workplaces but also in the living spaces as a direct outcome of the application of the new EU Directive. So, the importance of having reliable instruments is evident and interlaboratory exercises are becoming more and more popular. However, most of them are carried out under constant conditions of meteorological variables. We present in this paper a facility to broaden the interlaboratory comparisons further by adding the study of radon exposures under real conditions of changes in climatic parameters. In addition, the facility has the possibility to verify the response of radon monitors when the radon concentration changes several orders of magnitude in a short period of time. Our work shows some results of one of the interlaboratory exercises carried out in the premises, where the radon levels were rather homogeneous in the testing room.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Triple F—a comet nucleus sample return mission
Autorzy:: Blum, J.
Meierhenrich, U.
Fulle, M.
Palumbo, P.
Altwegg, K.
Hviid, S. F.
Aronica, A.
Mottola, S.
Zarnecki, J. C.
Barbieri, C.
Charnley, S.
Lomakin, I.
Sierks, H.
Bar-Nun, A.
Bredehöft, J.-H.
Epifani, E. M.
Korablev, O.
Goesmann, F.
Hilchenbach, M.
Kossacki, K.
Akim, E.
Yung, K. L.
Zolensky, M.
Szutowicz, S.
Ng, T. C.
Stroud, R. M.
Mennella, V.
Ehrenfreund, P.
Colangeli, L.
Cremonese, G.
Weiss, P.
Waniak, Wacław
Kührt, E.
Licandro, J.
Rickman, H.
Li, Z.-Y.
Biele, J.
Magni, G.
Pätzold, M.
Hartogh, P.
Markiewicz, W.
Basilevsky, A.
Schönbächler, M.
Zakharov, A.
Martynov, M.
Rodriguez, J.
Nazarov, M.
Bertrand, R.
Botta, O.
Gortsas, N.
Krüger, H.
Weissman, P.
Gerasimov, M.
Groussin, O.
Krause, C.
Ulamec, S.
Biver, N.
Rathke, A.
Lyon, I.
Capaccioni, F.
Kömle, N. I.
Srama, R.
Mall, U.
Wallis, M.
Benkhoff, J.
Bockelée-Morvan, D.
Henkel, T.
Busemann, H.
Capria, M. T.
Cloutis, E.
Ip, W.-H.
Lowry, S. C.
Tornow, C.
Ferri, F.
Keller, H. U.
Knollenberg, J.
Cottin, H.
Prialnik, D.
Grün, E.
Maurette, M.
Zelenyi, L.
Marov, M.
Esposito, F.
Jäckel, A.
Gutiérrez, P. J.
Korth, A.
Küppers, Michael
Wieler, R.
Crowther, S. A.
Horneck, G.
Kallenbach, R.
Mann, I.
Sandford, S.
Galimov, E.
Martins, Z.
Jessberger, E.
Kargl, G.
A’Hearn, M. F.
Ho, T.-M.
Roll, R.
Rengel, M.
Davidsson, B.
Wurz, P.
Nittler, L. R.
Ferrari, A. C.
Rost, D.
Crovisier, J.
Ball, A. J.
Lopez-Moreno, J. J.
Rotundi, A.
Green, S. F.
Gilmour, J.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 10.

Tytuł:: A force/position controller free of velocity measurement for robot manipulators with bounded torque input
Autorzy:: Chávez-Olivares, César A.
Mendoza-Gutiérrez, Marco O.
Bonilla-Gutiérrez, Isela
González-Galván, Emilio J.
Tematy:: force control
position control
Lyapunov stability
robot manipulator
saturation function; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/59111259.pdf Link otwiera się w nowym oknie
Opis:: Robot manipulators play a crucial role in various industrial and research settings, requiring precise and controlled interactions with their surroundings. Achieving this goal with fewer sensors offers advantages not only in terms of cost and decreased risk of failure but also enhances accuracy and long-term reliability. In this paper, we introduce a nonlinear force/position controller that eliminates the requirement for velocity measurements. This controller provides versatility by facilitating the generation of bounded control actions during robot-environment interactions, ensuring a higher level of safety for both the robot and its environment during the execution of tasks necessitating physical contact between them. The proposed approach is underpinned by a stability analysis in the Lyapunov sense and has been validated through a series of simulation and experimental tests.
Dostawca treści:: Biblioteka Nauki

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