Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 10
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

In the summer of 1977/78, materials for determining the age and growth rate of Pseudochaenichthys georgianus Norman, 1937 were obtained in the South Georgia region. The 11—51 cm long fishes were of the age 1+ to 13+. The curvilinear relationship between the body length and the otolith radius took an S shape. In the first four years annual increments are almost identical and start to decrease in the following years. Spawning may occur in the 5th or 6th year of life, and hatching of larvae from eggs laid in autumn (IV—VI) takes place at the end of winter (IX of X). Larvae and juvenile fish lead an exclusively pelagic life, while older fish feed in near-bottom layers: when resources are scare there they seek food in the pelagial.

Go to article

Authors and Affiliations

Juliusz Chojnacki
Piotr Palczewski
Download PDF Download RIS Download Bibtex

Abstract

Temperature gradient zone melting (TGZM) method was used to obtain bulk Si continuously for the efficient separation and purification of primary Si from the Si-Al alloy in this work. The effects of alloy thickness, temperature gradient and holding time in TGZM purification technology were investigated. Finally, the continuous growth of bulk Si without eutectic inclusions was obtained. The results showed that the growth rate of bulk Si was independent of the liquid zone thickness. When the temperature gradient was changed from 2.48 K/mm to 3.97 K/mm, the growth rate of bulk Si was enhanced from 7.9×10–5 mm/s to 2.47×10–4 mm/s, which was increased by about 3 times. The bulk Si could grow continuously and the growth rate was decreased with the increase of holding time from 1 h to 5 h. Meanwhile, low refining temperature was beneficial to the removal of impurities. With a precipitation temperature of 1460 K and a temperature gradient of 2.48 K/mm, the removal rates of Fe, P and B were 99.8%, 94.0% and 63.6%, respectively.

Go to article

Authors and Affiliations

Jiayan Li
Liang Wang
Jianjie Hao
Ping Ni
Yi Tan
Download PDF Download RIS Download Bibtex

Abstract

The present paper investigates the effects of variable-amplitude loads on fatigue crack growth rates for the 2024-T3 aluminium alloy on the basis of microfractographic analyses and its capacity to reconstruct load-time histories of failed components. For this purpose, there were applied three different variable-amplitude load sequences with single and multiple overloads and underloads. Subsequently, images of fatigue striations on components’ fracture surfaces were examined. The aforementioned loads were employed when simulating fatigue crack behaviour in aeronautical alloys.

Go to article

Authors and Affiliations

Zdzisław Bogdanowicz
Dorota Kocańda
Janusz Torzewski
Download PDF Download RIS Download Bibtex

Abstract

Plant responses to glyphosate applied at different doses were examined for one glyphosate resistant (R) and one glyphosate susceptible (S) population of Conyza albida and C. bonarienis. Growth rates and development stages of five R C. albida and three R C. bonarienis populations were also compared with those of their respective S counterparts to investigate the possible impact of the glyphosate resistance trait on their fitness. The GR50 values for C. albida R (3.94−5.22 kg a.i. · ha−1) and S (0.24−0.31 kg a.i. · ha−1) populations were higher than those of C. bonariensis R (0.60−1.51 kg a.i. · ha−1) and S (0.10−0.13 kg a.i. · ha−1). The growth rate (slope b) of one R C. albida population was lower than the respective S and other R populations, while growth rates of most R and S C. bonariensis populations were similar. Some R populations showed inconsistent differences in some development stages when compared to those of the S ones, which cannot be attributed to the glyphosate resistance trait.

Go to article

Authors and Affiliations

Philippos N. Mylonas
Costas N. Giannopolitis
Panagiotis G. Efthimiadis
Georgios C. Menexes
Ilias G. Eleftherohorinos
Download PDF Download RIS Download Bibtex

Abstract

The paper presents kinetic fatigue crack growth curve for IOHNAP steel, which is verified experimentally. An energy approach based on the M-integral range is shown. The tests have been carried out on plane specimens With notches under tension-compression for three values of stress ratio R. The J-integral is calculated analytically and by the finite element method. A relationship for the description of the whole kinetic crack growth curve including J-integral is presented. It is shown that at the constant loading and the change of stress ratio R from - 1 to O the fatigue crack growth rate increases. A relationship is proposed in the paper for description of the kinetic crack growth curve. It gives results that are consistent with experimental ones and those obtained with the use of the finite element method (FEM).
Go to article

Authors and Affiliations

Dariusz Rozumek
Download PDF Download RIS Download Bibtex

Abstract

Among the various thin film coating techniques, atomic layer deposition (ALD) has features of good controllability of the thickness, excellent step-coverage in 3-dimensional object even in the sub-nm thickness range at the relatively low deposition temperature. In this study, SnO2 thin films were grown by ALD in the variation of substrate temperatures from 150 to 250°C. Even such a low temperature may influence on the growth kinetics of the ALD reaction and thus the physical characteristics of thin films, such as crystallinity, film density and optical band gap, etc. We observed the decrease of the growth rate with increasing substrate temperature, at the same time, the density of the film was decreased with increasing temperature. Steric hindrance effect of the precursor molecule was attributed to the inverse relationship of the growth temperature and growth rate as well as the film density. Optical indirect band gap energy (~3.6 eV) of the ALD-grown amorphous SnO2 films grown at 150°C was similar with that of the literature value, while slightly lower band gap energy (~3.4 eV) was acquired at the films grown at higher temperature.
Go to article

Authors and Affiliations

Daeho Kim
Dong Ha Kim
Doh-Hyung Riu
Byung Joon Choi
Download PDF Download RIS Download Bibtex

Abstract

Round goby (Neogobius melanostomus (Pallas, 1814)) is an invasive species in the Oder River. In this study, age of 147 fish was determined using scales and otoliths, and the Fraser-Lee back-calculation method was used for population structure and theoretical length growth rates with 3 mathematical models of growth: von Bertalanffy, Ford–Walford and 2nd degree polynomial. Fish condition was determined using Fulton, Le Cren and Clark equations. Average total length and weight of fish was 162.00 mm and 83.00 g, respectively. Males were more abundant than females, representing 70% of the fish caught, and achieved greater total lengths and weights. Age 2+ dominated females and 3+ males age groups. Of the three mathematical models used to estimate fish growth, the 2nd degree polynomial model had the best fit to back-calculated lengths. Males had slightly higher growth rates than females in the first two years of life but comparable in subsequent years. The diet consisted of various benthic organisms that varied with fish age. The most frequently occurring food com-ponent was Dreissena polymorpha, which accounted for approximately 70% in the diet of fish with a body length greater than 191 mm.

Go to article

Authors and Affiliations

Agnieszka Rybczyk
ORCID: ORCID
Przemysław Czerniejewski
ORCID: ORCID
Sławomir Keszka
Mariola Janowicz
Adam Brysiewicz
ORCID: ORCID
Wawrzyniec Wawrzyniak
ORCID: ORCID
Download PDF Download RIS Download Bibtex

Abstract

The paper presents the results of tests on fatigue crack growth under bending in an elastic-plastic material. Specimens with rectangular sections and stress concentrator in the form of external one-sided sharp notch were used. The tests were performed under the stress ratios R = - I, - 0.5, O. The test results were described by the /'i ]-integral range and compared with the /'i K stress intensity factor range. It has been found that there is a good agreement between the test results and the empirical formula of fatigue crack growth rate, which includes the /'i ]-integral range.
Go to article

Authors and Affiliations

Dariusz Rozumek
Download PDF Download RIS Download Bibtex

Abstract

Fatigue crack growth for 2024-T3 Alclad aluminium alloy sheet being subjected to two load programs: a constant stress amplitude cyclic tension (R=O. l) (CA) and a variable amplitude tension with either a single or multiple overloads (OVL) periodically repeated is analysed in the paper. The latter load program corresponds to a simple flight simulation spectrum of wing structure of civil aircraft. The investigation was developed in order to learn about interaction between the applied load and formation of fatigue striations. Experimental results of surface crack growth rate provided by optical observations were compared with the rate determined on the basis of microfracture analysis. Good correspondence found under CA loading between the surface growth rate and the growth rate in the sheet depth means that the direction of specimen's cutting does not change essentially the crack growth behaviour. In the case of second loading (OVL) this factor influences the crack growth behaviour. Microfracture analysis revealed either retardation and acceleration of crack growth rate under OL V loading. This behaviour of growth rate results from a plastic zone formed in the front of crack tip and a crack closure effect.
Go to article

Authors and Affiliations

Dorota Kocańda
Stanisław Kocańda
Janusz Torzewski
Download PDF Download RIS Download Bibtex

Abstract

The article is devoted to the current scientific and practical problems of planning irrigation with phytomonitoring methods. In particular, it focuses on the methodological approach to tomato irrigation planning. The field experiment was laid by the method of systematic placement of elementary plots in four replicates. The PM-11Z phytomonitor was used to determine changes in stem diameter, juice flow, leaf temperature, and fruit growth.
On the basis of the experimental studies, parameters are defined for the start of watering with the positive, negative and zero water balance of the plant. It has been proved that when vegetative irrigation is planned with a positive plant water balance, the daily amplitude of stem contraction ( DCA) and the trend of the sap flow rate should be analysed. A fall in two consecutive morning stem diameter peaks ( MXSD) indicates a negative plant water balance, which is the starting point for watering. To assign watering with a zero water balance, it is necessary to use information from the fruit growth sensor and the juice flow rate. A decrease in their indications marks the need for the next watering.
Go to article

Authors and Affiliations

Andrii Shatkovskyi
1
ORCID: ORCID
Olexandr Zhuravlov
1
ORCID: ORCID
Volodymyr Vasiuta
1
ORCID: ORCID

  1. Institute of Water Problems and Land Reclamation of NAAS, 37, Vasyl’kivs’ka str., Kyiv, 03022 Ukraine

This page uses 'cookies'. Learn more