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1

Optomechanical industrial-level camera modifications for repeatable thermal image drift

Adamczyk Marcin, Nimura Kohei

Opto-Electronics Review

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2024

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Vol. 32, No. 2

art. no. e150185

EN

Thermal image drift is observed in prevalent industrial-level cameras because their optomechanical design is not optimised to reduce this phenomenon. In this paper, the effect of temperature on industrial-level cameras is investigated, focusing on the thermal image drift resulting from ambient temperature changes and warming-up process. Standard methods for reducing thermal image drift are reviewed, concentrating on the lack of repeatability aspect of this drift. Repeatable thermal image drift is crucial for applying a compensation model as random thermal deformations in sensors cannot be compensated. Moreover, the possible cause of this issue is explored, and novel optomechanical camera modifications are proposed that maintain the thermal degrees of freedom for the deforming sensor, limiting the lack of repeatability aspect of thermal image drift to a low level. The improvement is verified by conducting experiments using a specialised test stand equipped with an invar frame and thermal chamber. Considering the results from the application of the polynomial compensation model, the standard deviation of the central shifts of image drift is reduced by ×3.99, and the absolute range of image drift is reduced by ×2.53.

2

Temperature Effect on Buckling Properties of Thin-Walled Composite Profile Subjected to Axial Compression

Falkowicz Katarzyna, Kuciej Michał, Święch Łukasz

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 3

305--313

EN

This study investigates the influence of temperature variations on the buckling properties of thin-walled omega-profiles fabricated from carbon-epoxy composite materials. Utilizing a MTS testing machine, compression tests were conducted on these profiles at temperatures ranging from -20°C to 80°C, in 20°C increments. The primary objective was to assess how temperature fluctuations impact the buckling load and load-bearing capacity of these composite profiles under axial compression. The experimental setup allowed for precise measurement of load-displacement and load-deflection characteristics, and the critical load at which buckling initiation occurred. Observations revealed that the buckling resistance of the profiles exhibited a complex dependence on temperature. At lower temperatures, the composite material demonstrated enhanced stiffness and strength, marginally increasing buckling resistance. Conversely, at elevated temperatures, a noticeable degradation in mechanical properties was observed, leading to a reduced buckling load and altered failure modes. To complement the experimental findings, a comprehensive finite element (FE) analysis was conducted for sample in room temperature. The FE model, developed to replicate the experimental conditions closely, employed an eigenvalue-based approach to predict the buckling initiation and progression accurately. The presented results are the results of only preliminary tests and they will be expand about more samples number as well as to determine material properties for various temperatures.

3

Study on temperature characteristics of multi-tower cable-stayed bridge

Chengyuan Liu, Zhuowei Han, Wei Li, Lin Zhao

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

535--548

EN

Temperature effects have a great influence on the mechanical behavior of cable-stayed bridges, especially for long-span bridges, which have significant time-varying and spatial effects. In this paper, the temperature characteristics of multi-tower cable-stayed bridge are obtained by data acquisition with wireless acquisition module. The test results show that: the daily temperature-time curves of atmospheric temperature and structural temperature are similar to sine waves with obvious peaks and troughs; structure temperature and atmospheric temperature have obvious hysteresis; longitudinal displacement, transverse displacement and vertical of mid-span beam are negatively correlated with atmospheric temperature; the temperature distribution of the cable tower is not uniform, and the maximum temperature difference of the section is 23.7°C considering 98% of the upper limit value; the longitudinal, transverse and vertical displacement of cable tower and the cable force is negatively correlated with atmospheric temperature, and the relationship between cable force and atmospheric temperature is a cubic function rather than linear function.

4

Study of temperature field in large-span steel structure under radiation-thermal-fluid coupling

Jiang Pengcheng

Archives of Civil Engineering

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2023

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Vol. 69, nr 1

661--674

EN

The non-uniformity of temperature field distribution of long-span steel structure is proportional to the intensity of solar radiation. Based on the background of Guangzhou Baiyun Station large-span complex steel roof structure, this paper studies the non-uniform temperature field distribution of large-span steel structure under the Summer Solstice daily radiation-thermal-fluid coupling action based on Star-ccm+ finite element software, and uses Spa2000 software to analyze the stress and deformation of steel roof under temperature action. Combined with the on-site temperature monitoring, the maximum difference with the measured value is 2.5°C compared with the numerical simulation results, which verifies the validity of the finite element simulation. The results show that: from 8:00, with the increase of solar altitude angle, the intensity of solar radiation increases, the temperature rises, and the temperature distribution of large-span steel structure becomes more and more non-uniform. From14:00 to18:00, the solar radiation weakens, and the temperature distribution tends to be uniform. Finally, reasonable construction suggestions and measures are proposed to reduce the adverse effects of temperature effects, which can provide theoretical references for the safe construction and normal operation of large-span steel structures located in the subtropics.

5

Numerical identification of Preisach distribution function including temperature effects

Chelghoum Leila

Archives of Electrical Engineering

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2022

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Vol. 71, nr 2

297--309

EN

Magnetic hysteresis occurs in most electrical engineering devices once soft ferromagnetic materials are exposed to relatively high temperatures. According to several scientific studies, magnetic properties are strongly influenced by temperature. The development of models that can accurately describe the thermal effect on ferromagnetic materials is still an issue that inspires researchers. In this paper, the effect of temperature on magnetic hysteresis for ferromagnetic materials is investigated using a self-developed numerical method based on the Preisach distribution function identification. It employs a parameter depending on both temperature and the Curie temperature. This approach is of the macroscopic phenomenological type, where the variation of the magnetization (in direct connection with the Preisach triangle) is related to the observed macroscopic hysteretic behavior. The isotropic character of the material medium is predominant. The technique relies on a few experimental data extracted from the first magnetization curve provided by metallurgists. The ultimate goal is to provide a simple and robust magnetic behavior modeling tool for designers of electrical devices. Temperature is introduced at the stage of identifying the distribution function of the Preisach model. This method is validated by the agreement between the experimental data and the simulation results. The developed method is very accurate and efficient in modeling the hysteresis of ferromagnetic materials in engineering particularly for systems with ferromagnetic components and electromagnetic-thermal coupling.

6

Temperature effect on frequencies of a tapered triangular plate

Khodiya Akash, Sharma Amit

Journal of Applied Mathematics and Computational Mechanics

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2021

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Vol. 20, nr 1

37-48

EN

The two dimensional temperature effect on the vibration is computed for the first time for a clamped triangular plate with two dimensional thickness. In the study we focused on isosceles, right-angled and scalene triangles only. The first three modes of vibration are computed on different variations of plate parameters using the Rayleigh-Ritz method. The objective of the study is to reduce the frequency of the plates. A comparative study of the frequencies with other available results well presents the objective of the study.

7

Temperature Effect on Performance of Different Solar Cell Technologies

Adeeb Jehad, Farhan Alaa, Al-Salaymeh Ahmed

Journal of Ecological Engineering

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2019

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Vol. 20, nr 5

249--254

EN

One of the main parameters that affect the solar cell performance is cell temperature; the solar cell output decreases with the increase of temperature. Therefore, it is important to select the proper solar cell technology that performs better at a specified location considering its average temperatures. In addition, the solar cell performance is directly reflected on the overall economics of the project. This paper is proposed to evaluate the variations in the performance of different solar cell technologies related to the temperature in Amman, Jordan. Field data of weather station and three PV systems (Poly-crystalline, Mono-crystalline and Thin-film) of identical design parameters were collected from Test Field Project at Applied Science Private University, Shafa Badran, Amman, Jordan. These data were analysed in the following way. estimated specific energy yield (kWh/kWp) for the three different PV systems was calculated depending on the measured value of solar irradiance and technical specifications of the installed solar panels and inverters, then the actual energy yield at different temperatures over one year was compared with the estimated value, so the deviations could be determined and actual temperature coefficients for energy yield could be calculated, knowing that the three PV Systems have identical design parameters (tilt angle, azimuth angle, type and dimensions of mounting structure and inverter size) and same cleaning method and schedule. It was found that the thin-film solar panels are less affected by temperature with temperature coefficient of -0.0984%, and -0.109%, -0.124% for Mono-crystalline and Poly-crystalline respectively. These results can be implemented in the preliminary design steps, specifically in the selection of the solar cell technology to be installed in a specific location.

8

Temperature impact on delayed fracture of creep-resistant steels welds

Skulskyi V., Nimko M.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 88, nr 1

5--11

EN

Purpose: Phenomenon of delayed fracture (or cold cracks formation) of hardenable steels weldments had been widely investigated. But temperature dependence of cracking susceptibility remained discussable, because there was no strict vision of temperature border for the cracking risk appearance, when joints are cooling after welding completion. The proposed paper aimed at assessment of dangerous temperature range at which delayed fracture, mainly for the steels with martensite formation, becomes most probable. Design/methodology/approach: The “Implant” test, conducted under isothermal conditions at the temperatures selected within the range from 160 to 20°C on cooling of the completed test weld joint, was used. Basing on the obtained thermokinetic characteristics of the cracking, the activation energy E of the fracture process was calculated. Comparing of the found E values with the close values of E for the known processes developing in steels, the explanation of the revealed cracking behaviour at different temperatures was proposed. Findings: Delayed cracking of the martensitic weld joints has started to manifest at the temperatures lower than 140°C. Dependence of the cracking period from the temperature is described by C-type curve with the minimum cracking duration within 80-100°C. Using the approach of the activation energy assessment for different temperature ranges (140 to 100°C and 80 to 20°C), the effect of the diffusible hydrogen and a martensite decay on the cracking thermokinetics was considered. Research limitations/implications: Additional investigations of the fine microstructure after different stages of the low-temperature martensite decay could be necessary for deepening understanding of a role of this process in the low-temperature heterogeneity formation and cracking susceptibility. Practical implications: Results widen data on weldability of actual for industry steels and give a ground for consideration of the technological approaches for their welding. Originality/value: Temperature border of the cold cracking risk is specified for the weldments of some commercial steels.

9

Effects of temperature during ultrasonic conditioning in quartz-amine flotation

Gungoren C., Ozdemir O., Ozkan S. G.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

687--698

EN

In this study, the effect of ultrasound on flotation recovery of quartz-amine flotation was investigated in terms of temperature influence. For this purpose, an ultrasonic probe was used for conditioning quartz surfaces in presence of dodecylamine hydrochloride (DAH), and the change in the temperature was recorded. The temperature-controlled ultrasonic conditioning tests were also carried out at various ultrasonic powers (30, 90, and 150 W) to investigate the effect of increasing temperature on the quartz-DAH flotation. The results showed that temperature of the suspension sharply increased from 23 up to 75 °C at the end of 10 min of conditioning at 150 W ultrasonic power. The flotation results for the temperature controlled and uncontrolled samples indicated that the flotation recovery increased from 45 to 65% by 90 W ultrasonic power. However, higher ultrasonic power levels affected the flotation recovery negatively. On the other hand, the ultrasonic application decreased the flotation recovery at all ultrasonic power levels in the temperature-controlled tests. Finally, the shape analysis was also performed for the particles treated with the ultrasound at various ultrasonic powers. As a conclusion, the positive effect of ultrasound on the quartz-amine flotation recovery could be related to temperature increase during conditioning.

10

Magneto-thermo-mechanical buckling analysis of Mindlin plate reinforced with FG-carbon nanotubes

Kolahchi R., Esmailpour M., Safari M.

Archives of Civil Engineering

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2016

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Vol. 62, nr 3

89--104

EN

A buckling analysis of temperature-dependent embedded plates reinforced by single-walled carbon nanotubes (SWCNTs) subjected to a magnetic field is investigated. The SWCNTs are distributed as uniform (UD) and three types of functionally graded nanotubes (FG), in which the material properties of the nano-composite plate are estimated based on the mixture rule. The surrounding temperature-dependent elastic medium is simulated as Pasternak foundation. Based on the orthotropic Mindlin plate theory, the governing equations are derived using Hamilton's principle. The buckling load of the structure is calculated based on an exact solution by the Navier method. The influences of elastic medium, magnetic field, temperature and distribution type, and volume fractions of SWCNT are shown on the buckling of the plate. Results indicate that CNT distribution close to the top and bottom are more efficient than that distributed near the mid-plane for increasing the stiffness of the plates.

PL

Badana jest analiza wyboczenia wbudowanych płyt zależnych od temperatury wzmacnianych jednościennymi nanorurkami węglowymi (SWCNT) poddawanych polu magnetycznemu. Nanorurki SWCNT są rozpowszechniane jako jednolite (UD), a także istnieją trzy typy rozmieszczenia FG (FGA, FGO, FGX). W celu uzyskania równoważnych właściwości materiałowych nanokompozytów dwufazowych (tj. polimer jako matryca i nanorurka węglowa jako wzmocnienie), stosuje się zasadę mieszaniny. Do modelowania matematycznego obecnej struktury stosuje ortotropową teorię płyty Mindlina. W tej teorii odkształcenie normalne i przy ścinaniu są rozpatrywane w kategoriach przemieszczenia punktu materiału na płaszczyźnie środkowej i obrotów normalnej i środkowej płaszczyzny w kierunku osi X i Y. W celu uzyskania obowiązujących równań, stosowana jest metoda energetyczna i zasada Hamiltona. Całkowita energia potencjalna płytki CNTRC to suma energii odkształcenia i pracy wykonanej przez ośrodek elastomerowy i pole magnetyczne. W przypadku energii odkształcenia, zależności przemieszczania w wyniku naprężenia są definiowane w celu uproszczenia. Ośrodek sprężysty zależny od temperatury otoczenia jest stymulowany jako podłoże Pasternaka ze stałą sprężyny i ścinania. Ponieważ ośrodek elastomerowy jest stosunkowo miękki, zakłada się, że sztywność fundamentu jest zależna od temperatury. Ponadto, w przypadku płytki poddawanej stałemu polu magnetycznemu, bierze się pod uwagę przyłożoną siłę masową oraz ocenia się elementy siły Lorentza na jednostkę płytki. Na koniec, korzystając z zasady Hamiltona i integrując wg części, uzyskuje się obowiązujące równania w zakresie wypadkowych naprężeń. Następnie, obliczając wypadkową naprężenia pod względem przemieszczenia i obrotów, uzyskuje się ostateczną formę obowiązujących równań.

11

Rozszerzona metoda konduktometryczna w badaniach procesu hydratacji cementu glinowego

Nowacka M., Pacewska B.

Cement Wapno Beton

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2015

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R. 20/82, nr 4

225--234

PL

Badano wpływ temperatury i współczynnika w/c na przebieg hydratacji dwóch rodzajów cementów glinowych (ciemno-szarego i białego), głównie w oparciu o pomiary konduktometryczne. W tym celu skonstruowane naczyńko pomiarowe, które pozwalało na jednoczesny pomiar przewodnictwa elektrycznego i temperatury zaczynu. Wykonano ponadto pomiary kalorymetryczne i oznaczono skład zaczynu metodą analizy termicznej. Uzyskanych wyniki wykazały, że temperatura, w której przebiega hydratacja, decyduje o długości okresu indukcji, podczas gdy stosunek w/c = 0,35 lub 0,5 nie ma wpływu na szybkość procesu. Duże ciepło hydratacji zwiększa temperaturę zaczynu, co może spowodować konwersję nietrwałych hydratów glinianu wapnia w fazę C3AH6.

EN

The effect of temperature and w/c ratio on the hydration of two types of calcium aluminate cement (dark grey and white) was examined, mainly by conductometric measurements. For this purpose a specific cell was designed to monitor the electrical conductivity simultaneously with the temperature of cement paste versus time. Moreover, the calorimetric measurement was performed and the composition of the hydrated pastes was examined by thermal analysis. The results were showing that the temperature at which the hydration occurs determines the duration of the induction period, while w/c ratio equal 0.35 or 0.5 has no effect on the rate of this process. Furthermore, the heat of hydration is increasing the temperature of cement paste, which can cause the conversion of metastable calcium aluminate hydrates to C3AH6 phase.

12

Effect of temperature on the physical precursors of rock block failure

Baddari K., Frolov A.D., Tourtchine V., Makdeche S., Rahmoune F.

Acta Geophysica

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2012

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Vol. 60, no. 4

1007-1029

EN

The influence of temperature (25-400 °C) on the variations of mechanical, acoustic, electric and electromagnetic precursors of rock failure has been shown experimentally. The most significant variations were detected in the principal parameters of the acoustic and electromagnetic emissions whose impulse energy underwent a fast growth. However, the general character of hierarchical evolution stages of micro and macrofailure was practically unchanged. This has been confirmed by the so-called concentration parameter of rupture, which is theoretically calculated and checked in experiments; its space-time variations preceding the occurrence and progression of macrofailure are slightly depending on the rock temperature effect. This has been shown through the convolution of some physical precursors in a complex parameter whose variation showed an approaching of macrofailure, which remains slightly influenced by changes in temperature. Our results are interpreted in relation to physics of superficial earthquakes and precursors.

13

Temperature dependence of turn-on time delay of semiconductor laser diode : theoretical analysis

Ab Rahman M. S., Hassan M. R.

Opto-Electronics Review

|

2010

|

Vol. 18, No. 4

458-466

EN

Temperature dependence of the turn-on time delay (ton) of uncooled semiconductor laser diodes biased below and above threshold is analyzed in presence of data pattern effect. We show that even when the laser is biased at or slightly above threshold, the increase in temperature of operation will lead to increase in the threshold carrier (Nth) and consequently the laser diode will be biased below the threshold again and a significant value of ton will be produced. Thus, knowledge about a value of dc-bias current required to achieve zero ton within wide range of temperature degrees is important when considering uncooled laser diode in high-speed optical communication systems. The temperature dependence of ton is calculated according to the temperature dependence of Nth and Auger recombination coefficient (C) and not by the well-know exponentional relationship of threshold current with temperature. The temperature dependence of Nth is calculated according to the temperature dependence of laser cavity parameters. Advanced analytical model is derived in term of carrier density, recombination coefficients and the injection current (Iinj). The validity of proposed model is confirmed by a numerical method. In addition, approximated models are included where under specified assumptions the proposed model reduces to the well-known approximate models of ton. According to our typical values and at a specified value of modulation current, the dc-bias one (Iib) should be increased from Iib = Ith to Iib ≈ 1.25 and 1.5Ith in order to achieve approximately zero ton when the temperature increases from 25°C to 55°C and 85°C, respectively.

14

Influence of temperature on breakdown voltage of 10 MeV electron beam irradiated LDPE and HDPE

Borhani M., Ziaie F., Bolorizadeh M., Mirjalili G.

Nukleonika

|

2006

|

Vol. 51, nr 3

179-182

EN

The paper presents measurements of the breakdown (dielectric strength) and dielectric constant of the low density polyethylene (LDPE) and high density polyethylene (HDPE) thin sheets, which were irradiated with a 10 MeV electron beam in the range of 0-470 kGy using a Rhodotron accelerator system. The tests were performed at temperatures ranging from 20°C to 110°C. Variation of the measured parameters vs. radiation absorbed dose and temperature were discussed.

15

Study on the stability of microcrystalline chitosan systems with selected non-steroidal anti-inflammatory drugs

Bodek K.H.

Polimery

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2004

|

T. 49, nr 1

29-35

EN

The stabilities of microcrystalline chitosan (MCCh) systems with selected non-steroidal anti-inflammatory drugs (NSAIDs) were investigated after storage at ambient temperature for 12 months or at 60 and 80 °C for 5 h. Diclofenac (DA) and ketoprofen (KTA) in free acid form were used as model drugs in this study. For both the MCCh-drug (DA, KTA) systems, the intensity of bands corresponding to chitosan and drug slightly decreased as the temperature increased. X-ray diffraction and differential scanning calorimetry (DSC) showed that KTA in the microcrystalline chitosan systems remained in the amorphous state in contrary to DA, which was present in crystalline state. The interactions between DA and MCCh are not as strong and develop with time. The interaction between KTA and polymer (decrease in drug crystallnity) in stored systems is similar to those in freshly prepared samples. The amorphic form of KTA is present throughout the whole storage time. Slight decrease in KTA release rate was observed for MCCh film stored at 80 °C. These results suggest that microcrystalline chitosan is a suitable carrier for drugs of different solubility.

PL

Zbadano interakcję nośnika polimerowego [zawierającego grupy aminowe mikrokrystalicznego chitozanu, MCCh, wzór (I)] z niesteroidowymi substancjami przeciwzapalnyrni [diklofenakiem, DA, wzór (II) i ketoprofenem, KTA, wzór (III)], wybranymi jako modelowe substancje lecznicze o charakterze kwasu. Celem pracy było określenie wpływu czasu przechowywania, temperatury i charakteru oddziaływania tego nośnika z lekiem na szybkość uwalniania substancji leczniczej z MCCh (rys. 5). Charakter wspomnianego oddziaływania oceniano metodami IR (rys. 1 i 2), DSC (rys. 3) oraz rentgenograficzną (rys. 4). Uzyskane wyniki świadczą o tym, że specyficzne oddziaływania pomiędzy lekiem o charakterze kwasu i polimerem zawierającym wolne grupy aminowe prowadzą do tworzenia trwałych połączeń, charakteryzujących się lepszą rozpuszczalnością. Czas przechowywania i temperatura nie wpływają w istotny sposób na ilość uwolnionego KTA z układu z MCCh, aczkolwiek nośnik ten zmienia pierwotną strukturę krystaliczną KTA na amorficzną, która jest obecna przez cały czas przechowywania. Natomiast w przypadku DA o znacznie mniejszej rozpuszczalności w wodzie stwierdzono poprawę uwalniania (rozpuszczalności) dopiero pod wpły-wem przechowywania, chociaż przechowywanie tylko nieznacznie zmienia krystaliczność DA. Można stwierdzić, że w tym przypadku oddziaływania pomiędzy polimerem i lekiem nie są mocne i zależą od czasu przechowywania. Mikrokrystaliczna odmiana chitozanu ze względu na specyficzny charakter interakcji z niesteroidowymi substancjami przeciwzapalnymi jest więc korzystnym nośnikiem.

16

Effect of temperature on microstructure stability of aluminium alloys.

Richert M., Boczkal S., Białek A., Leszczyńska B.

Archives of Materials Science

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2004

|

Vol. 25, nr 4

379-384

EN

In this work, the investigations of the AlMg5 and AlCu4Zr alloys deformed by the Cyclic Extrusion Compression (CEC) method, in the range of true strains phi = 0.4 - 14, were performed. The microstructure and microhardness of deformed samples were studied. In both investigated alloys the microstructure, showing nanometric dimensions with large misorientation between nanograins, was found. The average microhardness, of both alloys, after deformation phi = 14, reached the mean value of about 110 žHV100. The samples deformed by the CEC method were annealed at temperatures: 150 degrees C for 80 s and 300 degrees C for 130 s. The performed investigations indicate that annealing of nanostructure alloys AlMg5 and AlCu4Zr for a short time 80 s at 150degrees C did not induce any substantial changes in microhardness and microstructure. The microhardness was still comparable with the microhardness of the deformed alloys. This suggests some low temperature stability of microstructures of nanomaterials, produced by the CEC method. However with the increase of the annealing temperature to 300 degrees C and the annealing time to 130 s, a considerable lowering of sample microhardness was found.

17

Ozone synthesis under barrier discharge at high and low concentrations

Petryk J., Jodzis S., Zarębski W.

Polish Journal of Chemical Technology

|

2002

|

Vol. 4, nr 2

28-32

EN

The influence of discharge parameters on the obtained ozone concentration has been analysed by means of a simple model of synthesis under silent discharge conditions. The overall rate of ozone synthesis decreases with an increase in the ozone concentration. The maximum content of ozone is obtained when in specified conditions the rate of the reaction, in which ozone is formed will be equal with that of the reactions causing its decomposition. It has been found that for the model assumed, the temperature is the main parameter which influences the maximum ozone concentrations. The calculation models are often simplified, with omitting the endothermic effect of the ozone synthesis and without taking into account the rise in average molar specific heat of a gas mixture resulting from the presence of ozone in it besides oxygen. Calculations taking into account and then omitting the above parameters were carried out. It appears that their influence is insignificant, so the simplification of the model does not cause a significant error. This especially refers to the synthesis at low concentrations of ozone. Many times it has been experimentally found that at low ozone concentrations the better process efficiency, i.e. a little higher ozone concentration is obtained when the synthesis proceeds at a higher temperature (with maintaining the other experiment conditions invariable). This anomaly has been explained on the basis of experimental results and calculations using a simple model of the process. model of synthesis under silent discharge conditions. The overall rate of ozone synthesis decreases with an increase in the ozone concentration. The maximum content of ozone is obtained when in specified conditions the rate of the reaction, in which ozone is formed will be equal with that of the reactions causing its decomposition. It has been found that for the model assumed, the temperature is the main parameter which influences the maximum ozone concentrations. The calculation models are often simplified, with omitting the endothermic effect of the ozone synthesis and without taking into account the rise in average molar specific heat of a gas mixture resulting from the presence of ozone in it besides oxygen. Calculations taking into account and then omitting the above parameters were carried out. It appears that their influence is insignificant, so the simplification of the model does not cause a significant error. This especially refers to the synthesis at low concentrations of ozone. Many times it has been experimentally found that at low ozone concentrations the better process efficiency, i.e. a little higher ozone concentration is obtained when the synthesis proceeds at a higher temperature (with maintaining the other experiment conditions invariable). This anomaly has been explained on the basis of experimental results and calculations using a simple model of the process.

18

The Influence of (O, N)-Deuteration on the Crystal and Molecular Structure, Thermal Stability and Spectroscopic Properties of 1,3-Propanediammonium Hydrogenphosphate Monohydrate

Bartoszak-Adamska E., Figlerowicz M., Wiewiórowski M., Gustaffson T., Olovsson I., Jaskolski M.

Polish Journal of Chemistry

|

2000

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Vol. 74, nr 3

393-402

EN

Exchange of mobile hydrogen atoms in 1,3-propanediammonium hydrogenphosphate for deuterium (OH-OD, NH-ND) affects the thermal stability of the salt. Additionally, (O,N)-deuteration induces some unexpected changes in the -CH2-vibrations in the IR spectrum of this compound. The structure of the title compound has been determined by single crystal X-ray diffraction analysis at 290 K (protonated as well as deuterated crystals) and at 25 K (deuterated crystal). In all cases, the crystals are monoclinic, space group, P21/c. The 1,3-propanediammonium dication has the extended all-trans conformation. The structure contains a three-dimensional network of hydrogen bonds, in which all available proton donors are engaged. The phosphate groups are linked through relatively strong H bonds to form infinite chains along c. The water molecule is closely associated with these chains by donating H bonds to two consecutive phosphate units along the chain.

19

Effect of temperature on the soil nematode Cephalobus persegnis in a laboratory culture

Makarevskaja Z.

Polish Journal of Ecology

|

1998

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Vol. 46, no 2

197-205

EN

Soil nematodes Cephalobus persegnis (Bastian 1865) originating from a laboratory culture maintained at 20 stopni C cultured for three successive generations at 15 stopni C, 21 stopni C, or 15/21 stopni C for 12 hours in each temperature. Transfer of the nematodes to 15 stopni C markedly depressed their fecundity and growth of F1 worms. In next generations fecundity restored while size of the nematodes increased significantly. Similar though less pronounced changes were observed also at 15/21 stopni C. No marked changes were found at 21 stopni C. The temperature the nematodes were cultured at did not influence their respiration rate measured at 21 stopni C. The latter depended on the weight of the nematodes.