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Sari, Injilia Pebrina. « Study Of Signal Quality Relationship On The Number Of Clusters And Propagation Parameters In Mobile Comumunication ». Jurnal Mekintek : Jurnal Mekanikal, Energi, Industri, Dan Teknologi 11, no 2 (30 octobre 2020) : 53–58. http://dx.doi.org/10.35335/mekintek.v11i2.14.
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A suitable telecommunications system to support a mobile communication system is a wireless communication system, which is a radio communication system complete with transmitting antennas and radio equipment. To be able to cover such a wide coverage, the coverage area is divided into sub-areas called cells. A collection of several cells is called a cluster, and several clusters will form a mobile cellular communication network area. The number of clusters in an area is affected by changes in parameters, especially the pathloss from the propagation environment. Planning in designing a communication network is needed to be able to see how much influence the parameter changes, especially the propagation attenuation factor and the number of clusters, is to make a computer program for cell planning. From the cell planning program, it can be obtained that the value of c/i is influenced by changes in the value of J when the value of n is 3.9. The value of c/i when the value of J is 3 is 6.5321. The value of c/i when the value of J is 4 is 8.4062. The value of c/i when the value of J is 5 is 9.8599. The value of c/i when the value of J is 6 is 11.0476. The value of c/i when the value of J is 7 is 12.0518. The value of c/i when the value of J is 8 is 12.9217. The value of c/i when the value of J is 9 is 13.6889. The value of c/i is influenced by changes in the value of n when the value of J is 15. The value of c/i when the value of n is 3 is 17.0167. The value of c/i when the value of n is 3.2 is 18.6698. The value of c/i when the value of n is 3.4 is 20.3231. The value of c/i when the value of n is 3.6 is 21.9761. The value of c/i when the value of n is 3.8 is 23.6293. The value of c/i when the value of n is 3.9 is 24.4561. The greater the number of cells, the greater the value of the signal ratio ratio (c/i) in the propagation. The propagation attenuation value is directly proportional to the signal ratio ratio (c/i). The greater the number of cells and the propagation attenuation, the greater the signal ratio ratio (c/i). The greater the value of the signal ratio ratio (c/i), the better the received signal quality.
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Zheng, Zhongpeng, Chenbing Ni, Yun Yang, Yuchao Bai et Xin Jin. « Numerical Analysis of Serrated Chip Formation Mechanism with Johnson-Cook Parameters in Micro-Cutting of Ti6Al4V ». Metals 11, no 1 (6 janvier 2021) : 102. http://dx.doi.org/10.3390/met11010102.
Texte intégralRésumé :
Previous studies have reported significant differences in the Johnson-Cook (J-C) parameters of Ti6Al4V alloy. Thus, various serrated chip morphologies, cutting forces, and cutting temperatures are obtained when different constitutive parameters are used for numerical and simulation analyses, which decreases the reliability of the simulation model. Therefore, it is necessary to investigate and analyze simulation errors due to differences in the J-C parameters. In this study, the mechanism of the serrated chip formation of Ti6Al4V is thoroughly analyzed using the uniformly proportional J-C parameters. The serrated chip sensitivity, shear band spacing, serrated segmentation frequency, chip serration intensity, temperature field, strain energy, and cutting force is obtained. This study aims to improve the accuracy and reliability of the micro-cutting simulation models, as well as a reference for the selection of J-C constitutive parameters of simulation with Ti6Al4V manufactured with different heat treatments and additive manufacturing.
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Seshadri, R., et R. K. Kizhatil. « Robust Approximate Methods for Estimating Inelastic Fracture Parameters ». Journal of Pressure Vessel Technology 117, no 2 (1 mai 1995) : 115–23. http://dx.doi.org/10.1115/1.2842098.
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Robust approximate methods to estimate the inelastic energy release rate J, and the creep crack-growth parameter, C*, for cracked components are described in this paper. These methods use linear elastic finite element analysis in conjunction with the concepts of the generalized local stress strain (GLOSS) analysis and redistribution nodes (r-nodes), and are readily applicable to complex geometries and loadings. J-estimates obtained by the use of robust methods are found to be in good agreement with the results of elastic-plastic finite element analysis.
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Bartsch, Martin, Zhe-Feng Zhang, Christina Scheu, Manfred Rühle et Ulrich Messerschmidt. « Fracture parameters of chevron-notched Al2O3/Nb sandwich specimens ». International Journal of Materials Research 95, no 9 (1 septembre 2004) : 779–84. http://dx.doi.org/10.1515/ijmr-2004-0146.
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Abstract Fracture toughness tests were performed on Al2O3/Nb sandwich specimens using chevron-notched bending bars. These tests allow the independent determination of the fracture toughness K c at a defined crack velocity and the total work of fracture J c. The J c values are much greater than the data for the energy release rate G c following from K c. The fracture surfaces were studied by optical and scanning electron microscopy. The results are discussed in terms of the fracture toughness of cleavage in the Al2O3 and severe plastic deformation in the Nb sheet.
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Wang, Cunxian, Tao Suo, Yulong Li, Pu Xue et Zhongbin Tang. « A New Experimental and Numerical Framework for Determining of Revised J-C Failure Parameters ». Metals 8, no 6 (30 mai 2018) : 396. http://dx.doi.org/10.3390/met8060396.
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Böttcher, O., N. Heineking, M. Andolfatto et D. H. Sutter. « Molecular gᅩ-value, Magnetic Susceptibility Anisotropy, and Deuterium Quadrupole Coupling Constantin Deuterodiacetylene ». Zeitschrift für Naturforschung A 44, no 2 (1 février 1989) : 89–94. http://dx.doi.org/10.1515/zna-1989-0201.
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Abstract The rotational Zeeman effect in the J′ → J = 2 → 1 rotational transition and the deuterium quadrupole coupling effect in the J′→J = 1 → 0 transition have been observed for D - C = C - C = C - H using a microwave Fourier transform (MWFT)-spectrometer.The molecular parameters determined are: rotational constant B0= 4084.452 MHz, deuterium quadrupole coupling constant e q Q (D) = 217(6) kHz, molecular gᅩ-value = 0.0073(1) and molecular magnetic susceptibility anisotropy (Xᅩ - X||) = 11.5(7) 10-6 erg G-2mol-1.
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Itzler, M. A., et M. Tinkham. « Effective parameters j˜/sub c/ and λ˜J at commensurate fields in large Josephson junctions with periodic columnar defects ». IEEE Transactions on Appiled Superconductivity 5, no 2 (juin 1995) : 1091–94. http://dx.doi.org/10.1109/77.402741.
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Qiu, Xiaoli, Xianqiang Cheng, Penghao Dong, Huachen Peng, Yan Xing et Xin Zhou. « Sensitivity Analysis of Johnson-Cook Material Constants and Friction Coefficient Influence on Finite Element Simulation of Turning Inconel 718 ». Materials 12, no 19 (25 septembre 2019) : 3121. http://dx.doi.org/10.3390/ma12193121.
Texte intégralRésumé :
The Johnson-Cook (J-C) constitutive model, including five material constants (A, B, n, C, m), and the Coulomb friction coefficient (μ) are critical preprocessed data in machining simulations. Before they become reliable preprocessed data, investigating these parameters’ effect on simulation results benefits parameter-selecting. This paper aims to investigate the different influence of five settings of the J-C constitutive equation and Coulomb friction coefficient on the turning simulation results of Inconel 718 under low-high cutting conditions, including residual stress, chip morphology, cutting force and temperature. A three-dimensional (3-D) finite element model was built, meanwhile, the reliability of the model was verified by comparing the experiment with the simulation. Sensitivity analysis of J-C parameters and friction coefficient on simulation results at low-high cutting conditions was carried out by the hybrid orthogonal test. The results demonstrate that the simulation accuracy of Inconel 718 is more susceptible to strain hardening and thermal softening in the J-C constitutive model. The friction coefficient only has significant effects on axial and radial forces in the high cutting condition. The influences of the coefficient A, n, and m on the residual stress, chip thickness, cutting force and temperature are especially significant. As the cutting parameters increase, the effect of the three coefficients will change visibly. This paper provides direction for controlling simulation results through the adjustment of the J-C constitutive model of Inconel 718 and the friction coefficient.
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Kunchur, Milind N. « Evaluating Superconductors through Current Induced Depairing ». Condensed Matter 4, no 2 (17 juin 2019) : 54. http://dx.doi.org/10.3390/condmat4020054.
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The phenomenon of superconductivity occurs in the phase space of three principal parameters: temperature T, magnetic field B, and current density j. The critical temperature T c is one of the first parameters that is measured and in a certain way defines the superconductor. From the practical applications point of view, of equal importance is the upper critical magnetic field B c 2 and conventional critical current density j c (above which the system begins to show resistance without entering the normal state). However, a seldom-measured parameter, the depairing current density j d , holds the same fundamental importance as T c and B c 2 , in that it defines a boundary between the superconducting and normal states. A study of j d sheds unique light on other important characteristics of the superconducting state such as the superfluid density and the nature of the normal state below T c , information that can play a key role in better understanding newly-discovered superconducting materials. From a measurement perspective, the extremely high values of j d make it difficult to measure, which is the reason why it is seldom measured. Here, we will review the fundamentals of current-induced depairing and the fast-pulsed current technique that facilitates its measurement and discuss the results of its application to the topological-insulator/chalcogenide interfacial superconducting system.
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Wang, J., N. Ito, S. Pyon, T. Nishizaki et T. Tamegai. « Vortex Dynamics and Critical Current Densities in 90 K-phase and 60 K-phase YBa2Cu3O7−δ with Splayed Columnar Defects ». Journal of Physics : Conference Series 2323, no 1 (1 août 2022) : 012018. http://dx.doi.org/10.1088/1742-6596/2323/1/012018.
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Abstract Enhancement of critical current density (J c) was observed in YBa2Cu3O7−δ with splayed columnar defects (CDs). In the case of 90 K-phase YBa2Cu3O7−δ with splayed CDs, the enhanced J c drops suddenly at the depinning temperature of vortices from CDs (T dp), which is interpreted to be caused by the excitation of double kinks traversing neighboring CDs. In addition to the optimal 90 K-phase, where the superconductivity dominates, there is another stable 60 K-phase and other phases with different T c. This study reports temperature dependence of J c and the step-like decrease of J c in YBa2Cu3O7−δ with CDs and with different T c. Results show that the T dp is strongly related to the T c. However, additional entropic reduction of T dp may depend on parameters other than T c.
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Păun, Gheorghe, et Miroslav Novotný. « On Some Parameters Occurring in Certain Effective Constructions of Grammars ». Fundamenta Informaticae 10, no 1 (1 janvier 1987) : 69–80. http://dx.doi.org/10.3233/fi-1987-10105.
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J. Ostravský considered two classes of languages – BS and BC – and described an effective construction assigning a pure grammar Gjk(V,L) to any j∈{s,c}, to any language (V,L), and to any integer k⩾1. He proved that (V,L)∈Bj if and only if there exists k0⩾1 such that Gjk(V,L) = Gjk0(V,L) for any k⩾k0. The least integer k0 with this property is a complexity measure of the language (V,L)∈Bj. Besides this complexity measure, we study another one introduced in connection with the above mentioned construction. We compare the complexity of languages with the complexity of languages obtained by usual operations from the given ones.
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Mozokhina, Anastasia, Latifa Ait Mahiout et Vitaly Volpert. « Modeling of Viral Infection with Inflammation ». Mathematics 11, no 19 (27 septembre 2023) : 4095. http://dx.doi.org/10.3390/math11194095.
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Viral infection spreads in cell culture or tissue as a reaction–diffusion wave. It is characterized by three main parameters: virus replication number, Rv, which determines whether infection progresses, wave speed, c, which correlates with the virus virulence, and viral load, J(v), which determines the infection transmission rate. In this work, we study how the inflammation triggered by viral infection influences its progression. We obtain analytical expressions for Rv,c, and J(v) and show how they depend on the intensity of inflammation characterized by one or two parameters. Analytical and numerical results show that inflammation decreases the viral replication number, virus virulence, and infectivity, though there are different cases depending on the parameters of the model.
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Monteiro, Maria Lúcia G., Eliane T. Mársico et Carlos A. Conte-Junior. « Application of Active Packaging in Refrigerated Rainbow Trout (Oncorhynchus mykiss) Fillets Treated with UV-C Radiation ». Applied Sciences 10, no 17 (21 août 2020) : 5787. http://dx.doi.org/10.3390/app10175787.
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This study investigated the effects of oxygen-scavenger packaging and UV-C radiation at two doses, alone or in combination, on lipid oxidation (malondialdehyde levels), protein oxidation (carbonyl content), instrumental color and texture parameters in rainbow trout fillets stored at 4 ± 1 °C for 9 days. The treatments were AP (air packaging), OSP (oxygen-scavenger packaging), AUV1 (air packaging + UV-C at 0.102 J/cm2), OSUV1 (oxygen-scavenger packaging + UV-C at 0.102 J/cm2), AUV3 (air packaging + UV-C at 0.301 J/cm2), and OSUV3 (oxygen-scavenger packaging + UV-C at 0.301 J/cm2). Lipid oxidation, protein oxidation, lightness and yellowness increased, while redness, hardness and chewiness decreased during storage in all treatments (p < 0.05). OSP, OSUV1 and OSUV3 exhibited lower yellowness, total color difference (ΔE), lipid and protein oxidation, and higher redness, hardness and chewiness than air packaging (AP; p < 0.05), being similar to each other concerning these parameters throughout storage (p > 0.05). AUV3 showed higher lipid oxidation, protein oxidation, yellowness, ΔE, and lower redness, hardness and chewiness followed by AUV1 than AP (p < 0.05). UV-C at these doses was not adequate for refrigerated trout fillets by inducing oxidative degradation. O2 scavenger was effective in preventing the adverse effects from storage period and UV-C, independently of the dose, and could be a simple and powerful alternative to make feasible the industrial application of UV-C at 0.102 and 0.301 J/cm2 in refrigerated rainbow trout fillets, which has proven antimicrobial effect and it is a promising non-thermal technology for the fish production chain.
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Tian, Xiao, Jingjing Pei et Jingjing Rong. « Dynamic Mechanical Properties and Damage Parameters of Marine Pipelines Based on Johnson–Cook Model ». Journal of Marine Science and Engineering 11, no 9 (24 août 2023) : 1666. http://dx.doi.org/10.3390/jmse11091666.
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A comprehensive understanding of the dynamic behavior of materials and structures under impact loads is paramount for the design and maintenance of reliable marine pipelines and associated structures. However, there is a lack of comprehensive research on the full characterization of constitutive and failure models of carbon steels, which are commonly used in marine pipelines. In this paper, Q235 steel was subjected to quasi-static tensile tests at room temperature on smooth specimens to obtain the constitutive parameters using the Johnson–Cook (J-C) model. Subsequently, quasi-static tensile tests were conducted on notched specimens, and dynamic tensile tests were performed on smooth round bars to obtain stress triaxiality and failure strain. The acquired data were then utilized to fit the failure parameters using the Johnson–Cook (J-C) damage model, a widely accepted constitutive model employed in high-strain rate applications through the least squares method. Finally, the tensile test is numerically simulated based on the acquired experimental parameters. The obtained results reveal a remarkable agreement between the curve fitted by the J-C constitutive model and the experimental tensile curve. Additionally, a high degree of correlation between the load-displacement curves of the tests and simulations provides robust validation of the accuracy of the dynamic mechanical parameters for Q235 steel. These findings contribute valuable insights into the behavior of carbon steels commonly used in marine pipelines, enhancing the overall understanding of their response to impact loads and informing more reliable design and maintenance practices.
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Dong, Mengxia. « Existence of Extremal Functions for Higher-Order Caffarelli–Kohn–Nirenberg Inequalities ». Advanced Nonlinear Studies 18, no 3 (1 août 2018) : 543–53. http://dx.doi.org/10.1515/ans-2017-6037.
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Abstract Though there has been an extensive study on first-order Caffarelli–Kohn–Nirenberg inequalities, not much is known for the existence of extremal functions for higher-order ones. The higher-order derivative of the Caffarelli–Kohn–Nirenberg inequality established by Lin [14] states \bigg{(}\int_{\mathbb{R}^{N}}\lvert D^{j}u|^{r}\frac{dx}{|x|^{s}}\bigg{)}^{% \frac{1}{r}}\leq C\bigg{(}\int_{\mathbb{R}^{N}}\lvert D^{m}u|^{p}\frac{dx}{|x|% ^{\mu}}\bigg{)}^{\frac{a}{p}}\bigg{(}\int_{\mathbb{R}^{N}}\lvert u|^{q}\frac{% dx}{|x|^{\sigma}}\bigg{)}^{\frac{1-a}{q}}, where {C=C(p,q,r,\mu,\sigma,s,m,j)} and {p,q,r,\mu,\sigma,s,m,j} are parameters satisfying some balanced conditions. The main purpose of this paper is to establish the existence of extremal functions for a family of this higher-order derivatives of Caffarelli–Kohn–Nirenberg inequalities under numerous circumstances of parameters. Moreover, we study the compactness of the weighted Sobolev space for higher-order derivatives and prove that {\dot{H}^{m,p}_{\mu}(\Omega)\cap L^{q}_{\sigma}(\Omega)\hookrightarrow\dot{H}^% {j,r}_{s}(\Omega)} is a compact embedding within some range of the parameters.
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Suzuki, Akira. « No elementary embedding from v into v is definable from parameters ». Journal of Symbolic Logic 64, no 4 (décembre 1999) : 1591–94. http://dx.doi.org/10.2307/2586799.
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In 1970, Kenneth Kunen showed that there is no non-trivial elementary embedding of the universe V into itself [2] using the axiom of choice. Kunen remarked in his paper that the result can be formalized in Morse-Kelley theory of sets and classes. In this paper, we will work within ZF, Zermelo-Fraenkel axioms, and deal with embeddings definable with a formula and a parameter.In ZF, a “class” is usually synonymous with “property”, that is a class definable with a parameter, C = {x: φ(x,p)}, where φ is a formula in the language [∈}. Using this convention, let j be a class. Then “j is an elementary embedding of V into V” is not a single statement but a schema of statements “j preserves ψ” for each formula ψ. We prove that this schema is expressible in the language {∈} by a single formula:Lemma. An embedding j: V → V is elementary iff j preservesψ.Here ψ(α, ψ, a) is the property “a is an ordinal, φ is a formula and Vα.”The lemma is of course a schema of lemmas, one for each formula denning j and for each ψ to be preserved.Using this we prove our theorem in ZF (again, a schema of theorems.):Theorem 1.1. There is no nontrivial definable elementary embedding j: V → V.Many symbols and their definitions follow those used by Drake's book [1]. The formula Sat expresses the satisfaction relation . The formula Fmla(u) expresses that u is the Gödel-set for a formula.
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Fornasiero, Federico, et Sudev Naduvath. « On J-colorability of certain derived graph classes ». Acta Universitatis Sapientiae, Informatica 11, no 2 (1 décembre 2019) : 159–73. http://dx.doi.org/10.2478/ausi-2019-0011.
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Abstract A vertex v of a given graph G is said to be in a rainbow neighbourhood of G, with respect to a proper coloring C of G, if the closed neighbourhood N[v] of the vertex v consists of at least one vertex from every color class of G with respect to C. A maximal proper coloring of a graph G is a J-coloring of G such that every vertex of G belongs to a rainbow neighbourhood of G. In this paper, we study certain parameters related to J-coloring of certain Mycielski-type graphs.
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Hejna, Małgorzata, Kacper Świechowski, Waheed A. Rasaq et Andrzej Białowiec. « Study on the Effect of Hydrothermal Carbonization Parameters on Fuel Properties of Chicken Manure Hydrochar ». Materials 15, no 16 (13 août 2022) : 5564. http://dx.doi.org/10.3390/ma15165564.
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Economic development and population growth lead to the increased production of chicken manure, which is a problematic organic waste in terms of its amount, environmental threats, and moisture content. In this study, hydrothermal carbonization, an emerging way of waste disposal, was performed on chicken manure to produce an energy-rich material called hydrochar. The effects of hydrothermal carbonization temperature (180, 240, 300 °C) and process time (30, 90, 180 min) were summarized. Proximate and ultimate analysis, as well as low and high heating values were applied both on raw material and derived hydrochars. Additionally, the performance of the process was examined. The obtained results show that hydrothermal carbonization is a feasible method for chicken manure disposal and valorization. Although the process time did not influence the fuel properties of chicken manure considerably, a higher temperature led to a significantly higher heating value, reaching 23,880.67 ± 34.56 J × g−1 at 300 °C and 180 min with an improvement of ~8329 J × g−1 compared with raw chicken manure (15,551.67 J × g−1). Considering the energy gain value, the hydrochar derived at 240 °C in 30 min had the best result. Moreover, the energy consumption for this process was relatively low (124.34 ± 8.29 kJ × g−1). With its still feasible fuel properties and high heating value of 20,267.00 ± 617.83 kJ × g−1, it was concluded that these parameters of chicken manure hydrochar are the most beneficial and present a potential alternative for conventional fuel.
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Li, Yongkun, et Chao Wang. « Three Positive Periodic Solutions to Nonlinear Neutral Functional Differential Equations with Parameters on Variable Time Scales ». Journal of Applied Mathematics 2012 (2012) : 1–28. http://dx.doi.org/10.1155/2012/516476.
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Using two successive reductions: B-equivalence of the system on a variable time scale to a system on a time scale and a reduction to an impulsive differential equation and by Leggett-Williams fixed point theorem, we investigate the existence of three positive periodic solutions to the nonlinear neutral functional differential equation on variable time scales with a transition condition between two consecutive parts of the scale(d/dt)(x(t)+c(t)x(t-α))=a(t)g(x(t))x(t)-∑j=1nλjfj(t,x(t-vj(t))),(t,x)∈T0(x),Δt|(t,x)∈S2i=Πi1(t,x)-t,Δx|(t,x)∈S2i=Πi2(t,x)-x, whereΠi1(t,x)=t2i+1+τ2i+1(Πi2(t,x))andΠi2(t,x)=Bix+Ji(x)+x, i=1,2,…. λj (j=1,2,…,n)are parameters,T0(x)is a variable time scale with(ω,p)-property,c(t), a(t),vj(t),andfj(t,x) (j=1,2,…,n)areω-periodic functions oft,Bi+p=Bi, Ji+p(x)=Ji(x)uniformly with respect toi∈Z.
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Allikmäe, Anna-Mai, Robert Telpt, Jaak Nerut, Patrick Teppor, Peeter Valk, Miriam Koppel, Jaan Aruväli et Enn Lust. « (Digital Presentation) Synthesis of Proton Exchange Membrane Fuel Cell Catalyst and Optimization of Membrane Electrode Assembly Preparation Parameters ». ECS Meeting Abstracts MA2023-01, no 38 (28 août 2023) : 2296. http://dx.doi.org/10.1149/ma2023-01382296mtgabs.
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Reducing platinum content in proton exchange membrane fuel cells (PEMFCs) is one of the most essential development directions to secure the economic viability of PEMFC. Efforts are being made to synthesise new, more active catalysts and to optimise PEMFC assembly parameters. (1–4) The study aimed to synthesise 60 wt% Pt/C catalyst and optimise catalyst loading on the electrodes, gasket thickness and coating strategy. The catalyst was synthesised by depositing Pt nanoparticles on carbon black (Ketjenblack EC-300J) using ethylene glycol as a reducing agent and solvent (5–7). The studied catalyst was characterised by thermogravimetric analysis, X-ray diffraction and N2 sorption analysis. The synthesized catalyst material contained approximately 60 wt% of Pt, and the average platinum crystallite size was under 3 nm. The catalyst had a micro-mesoporous structure with a specific surface area of 320 m2 g−1. For electrochemical characterisation, the measurements were performed in H2/air PEMFC. Using an ultrasonic coating system, the catalyst was deposited on the Nafion membrane or gas diffusion layer. A suitable gasket thickness was found using electrochemical measurements. The catalyst loading was varied on the anode between 0.05 and 0.50 mg cm−2 and on the cathode between 0.40 and 1.00 mg cm−2, leaving the catalyst loading constant on the non-variable electrode. Electrodes thickness depended linearly on the catalyst loading. The results showed that electrochemically active surface area does not depend on catalyst loading. Varying catalyst loading on the anode did not show a decrease in electrochemical activity; thus, the anode catalyst loading could be reduced to 0.05 mg cm−2. However, the electrochemical activity decreased at low cathode catalyst loadings. It was found that the cathode catalyst loading can be reduced to 0.60 mg cm−2. Under optimised conditions, the electrochemical activity of the investigated material was excellent. The PEMFC current density was 0.81 A cm−2 at 670 mV, the maximum achieved power density 0.80 W cm−2 and the electrochemically active surface area 56 mPt 2 gPt −1. Acknowledgements This work was supported by the EU through the European Regional Development Fund TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011) and the Estonian Research Agency project (personal research support group grant project No. PRG676). References R. Alink, R. Singh, P. Schneider, K. Christmann, J. Schall, R. Keding, and N. Zamel, Molecules, 25, E1523 (2020). Á. Kriston, T. Xie, D. Gamliel, P. Ganesan, and B. N. Popov, Journal of Power Sources, 243, 958 (2013). J. Lee, C. Seol, J. Kim, S. Jang, and S. M. Kim, Energy Technol., 9, 2100113 (2021). H. A. Gasteiger, J. E. Panels, and S. G. Yan, Journal of Power Sources, 127, 162 (2004). Y. Shao, S. Zhang, R. Kou, X. Wang, C. Wang, S. Dai, V. Viswanathan, J. Liu, Y. Wang, and Y. Lin, Journal of Power Sources, 195, 1805 (2010). W. Li, C. Liang, W. Zhou, J. Qiu, Zhou, G. Sun, and Q. Xin, J. Phys. Chem. B, 107, 6292 (2003). R. Kou, Y. Shao, D. Mei, Z. Nie, D. Wang, C. Wang, V. V. Viswanathan, S. Park, I. A. Aksay, Y. Lin, Y. Wang, and J. Liu, J. Am. Chem. Soc., 133, 2541 (2011).
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Schwank, Mike, Reza Naderpour et Christian Mätzler. « “Tau-Omega”- and Two-Stream Emission Models Used for Passive L-Band Retrievals : Application to Close-Range Measurements over a Forest ». Remote Sensing 10, no 12 (22 novembre 2018) : 1868. http://dx.doi.org/10.3390/rs10121868.
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Microwave Emission Models (EM) are used in retrieval algorithms to estimate geophysical state parameters such as soil Water Content ( W C ) and vegetation optical depth ( τ ), from brightness temperatures T B p , θ measured at nadir angles θ at Horizontal and Vertical polarizations p = { H , V } . An EM adequate for implementation in a retrieval algorithm must capture the responses of T B p , θ to the retrieval parameters, and the EM parameters must be experimentally accessible and representative of the measurement footprint. The objective of this study is to explore the benefits of the multiple-scattering Two-Stream (2S) EM over the “Tau-Omega” (TO) EM considered as the “reference” to retrieve W C and τ from L-band T B p , θ . For sparse and low-scattering vegetation T B , E M p , θ simulated with E M = { TO , 2 S } converge. This is not the case for dense and strongly scattering vegetation. Two-Parameter (2P) retrievals 2 P R C = ( W C R C , τ R C ) are computed from elevation scans T B p , θ j = T B , TO p , θ j synthesized with TO EM and from T B p , θ j measured from a tower within a deciduous forest. Retrieval Configurations ( R C ) employ either E M = TO or E M = 2 S and assume fixed scattering albedos. W C R C achieved with the 2S RC is marginally lower ( ~ 1 m 3 m − 3 ) than if achieved with the “reference” TO RC, while τ R C is reduced considerably when using 2S EM instead of TO EM. Our study outlines a number of advantages of the 2S EM over the TO EM currently implemented in the operational SMOS and SMAP retrieval algorithms.
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Iqbal, MK, A. Nadeem et MT Butt. « Impact of process parameters on refused derived fuel pellets ». Bangladesh Journal of Scientific and Industrial Research 55, no 1 (21 avril 2020) : 73–82. http://dx.doi.org/10.3329/bjsir.v55i1.46734.
Texte intégralRésumé :
The objective of present study was to optimize the process conditions for the development of refused derived fuel (RDF) pellets from municipal solid waste (MSW) and biomass by using Response Surface Methodology (RSM). The three factors specifically moisture (20-45%), preheating temperature (50-120˚C) and pressure (500-1500 psi) were taken as center point. The experimental data of response variables were fitted into quadratic polynomial model using the multiple regression analysis and found it was statistically significant quadratic model and contour plot further revealed that moisture (20%), preheating temperature (120˚C) and hydraulic pressure (1000psi) were the best conditions. Moreover bulk density and durability of pellets increased due to temperature and pressure but decrease with moisture. The bulk density (BD) moisture durability (DU) size diameter carbon hydrogen sulpher chloride ash fixed carbon HHV (High heating value) LHV (Low heating value) and ash metal were also evaluated.
Bangladesh J. Sci. Ind. Res.55(1), 73-82, 2020
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Hong, Tran Thi, Phan Tien Dung et Vu Xuan Quang. « Judd Ofelt Analysis and Optical Properties of Rare Earth Doped Tellurite Glasses ». Communications in Physics 23, no 4 (19 février 2014) : 377. http://dx.doi.org/10.15625/0868-3166/23/4/3666.
Texte intégralRésumé :
In this work, the structural characteristic and photoluminescence properties were investigated in Eu\(^{3 + }\) ions-doped B\(_{2}\)O\(_{3}\)-TeO\(_{2}\) --ZnO-Na\(_{2}\)O glasses. These glasses were prepared by the melting method in air, after that thermal annealed 350\rc{}C, 450\rc{}C and 550\rc{}C for different times. The analysis results of structure on these glasses showed the formation of micro-crystals in host glass after thermal annealed process. The photoluminescence spectra of Eu\(^{3 + }\) ions in these samples were observed. The local vibration mode around Eu\(^{3 + }\) ions was investigated by the phonon side band associated with \(^{7}\)F\(_{0}\)- \(^{5}\)D\(_{2}\) transition of Eu\(^{3 + }\). Judd-Ofelt parameters have been evaluated from photoluminescence spectra and were to predict the luminescence intensity ratios of \(^{5}\)D\(_{0} \to ^{7}\)F\(_{J}\) (J=2, 4 and 6) to \(^{5}\)D\(_{0} \to ^{7}\)F\(_{1}\) transition. The obtained results have been used for calculating \(\Omega_{2}\), \(\Omega _{4}\), \(\Omega _{6}\) parameters by using Judd-Ofelt theory. These \(\Omega _{2}\), \(\Omega _{4}\), \(\Omega _{6}\) parameters allow to derive radiative properties of Eu\(^{3 + }\) ions in glass material such as transition probabilities, radiative lifetimes and peak stimulated emission cross-section for the \(^{5}\)D\(_{0} \to ^{7}\)F\(_{J}\) transitions.
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Hong, Tran Thi, Phan Tien Dung et Vu Xuan Quang. « Judd Ofelt Analysis and Optical Properties of Eu\(^{3 + }\) Doped Tellurite Glasses ». Communications in Physics 24, no 3S1 (13 novembre 2014) : 136–42. http://dx.doi.org/10.15625/0868-3166/24/3s1/5465.
Texte intégralRésumé :
In this work, the structural characteristic and photoluminescence properties of Eu\(^{3 + }\) doped B\(_{2}\)O\(_{3}\)-TeO\(_{2}\) -ZnO-Na\(_{2}\)O glasses were investigated. These glasses were prepared by a melting method in air, combined with thermal annealing at 350\(^{\circ}\)C, 450\(^{\circ}\)C and 550\(^{\circ}\)C for different duration times. The structural analysis results of these glasses revealed the formation of micro-crystals in the annealed host glass. The photoluminescence spectra of Eu\(^{3 + }\) doped in these samples were observed. The local vibration mode around Eu\(^{3 + }\) ions was investigated by the phonon side-band (PSB) associated with \(^{7}\!F_{0}-^{5}D_{2}\) transition of Eu\(^{3+}\). Judd-Ofelt parameters were then evaluated based on photoluminescence spectra and the luminescence intensity ratios of \(^{5}D_{0} \to ^{7}\!F_{J}\) (\(J=2, 4\) and 6) to \(^{5}D_{0} \to ^{7}\!F_{1}\) transition were predicted. The obtained results were then used to calculate \(\Omega _{2},\;\Omega _{4},\; \Omega _{6} \) parameters based on Judd-Ofelt theory. These \(\Omega _{2}\), \(\Omega _{4}\), \(\Omega _{6}\) parameters allow to derive radiative properties of Eu\(^{3 + }\) ions in glass material such as transition probabilities, radiative lifetimes and peak stimulated emission cross-section for the \(^{5}D_{0} \to ^{7}\!F_{J}\) transitions.
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Moris Devotta, Ashwin, P. V. Sivaprasad, Tomas Beno, Mahdi Eynian, Kjell Hjertig, Martin Magnevall et Mikael Lundblad. « A Modified Johnson-Cook Model for Ferritic-Pearlitic Steel in Dynamic Strain Aging Regime ». Metals 9, no 5 (8 mai 2019) : 528. http://dx.doi.org/10.3390/met9050528.
Texte intégralRésumé :
In this study, the flow stress behavior of ferritic-pearlitic steel (C45E steel) is investigated through isothermal compression testing at different strain rates (1 s−1, 5 s−1, and 60 s−1) and temperatures ranging from 200 to 700 °C. The stress-strain curves obtained from experimental testing were post-processed to obtain true stress-true plastic strain curves. To fit the experimental data to well-known material models, Johnson-Cook (J-C) model was investigated and found to have a poor fit. Analysis of the flow stress as a function of temperature and strain rate showed that among other deformation mechanisms dynamic strain aging mechanism was active between the temperature range 200 and 400 °C for varying strain rates and J-C model is unable to capture this phenomenon. This lead to the need to modify the J-C model for the material under investigation. Therefore, the original J-C model parameters A, B and n are modified using the polynomial equation to capture its dependence on temperature and strain rate. The results show the ability of the modified J-C model to describe the flow behavior satisfactorily while dynamic strain aging was operative.
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Mtebwa, Mahamudu. « Optimization of Pulsed Laser Deposition Parameters for Single-Crystalline (011) Oriented Tetragonal Pzt Thin Films ». Tanzania Journal of Engineering and Technology 41, no 4 (31 décembre 2022) : 183–91. http://dx.doi.org/10.52339/tjet.v41i4.858.
Texte intégralRésumé :
Recent advances in nanotechnology applications require the processing of high-quality thin films. A systematic study of the optimization of Pulsed deposition parameters for (110) oriented tetragonal PZT thin films is reported in this work. Prior to film deposition, a highly tetragonal Pb(Zr0.5, Ti0.95) or PZT 05/95 was selected to be deposited on (110) oriented Strontium titanate, SrTiO3 substrate, STO(110) to insure small compressive misfit strain. Unlike SRO, the LSOM bottom electrode was then successfully grown at 620 °C, 1.0 J/cm2 and a target-substrate distance of 3.9 cm. Finally, deposition parameters of PZT were progressively optimized through monitoring film morphological changes. Monocrystalline PZT films of different thicknesses with layer–by–layer growth mode were finally realized at a deposition temperature of 550 °C, laser energy of 1.0 J/cm2, background pressure of 200 mTorr O2, while deposition rate was 3 Hz and target-substrate distance of 3.1 cm. The optimal film growth rate was finally estimated to be 0.3 nm/100 Pulses.
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Prokopenko, O. S. « REGRESSION MODELS OF INDIVIDUAL CEPHALOMETRIC PARAMETERS IN UKRAINIAN YOUNG MEN AND YOUNG WOMEN WITH DIFFERENT FACIAL PROFILES ACCORDING TO SCHWARZ A.M., WHICH CAN BE ADJUSTED DURING SURGERY DEPENDING ON THE PARAMETERS THAT USUALLY DO NOT CHANGE ». Ukrainian Dental Almanac, no 2 (29 juin 2021) : 95–101. http://dx.doi.org/10.31718/2409-0255.2.2021.17.
Texte intégralRésumé :
For Ukrainian young men and young women with different facial profiles according to Schwarz A. M. with normal occlusion close to orthognathic occlusion and a harmonious face, regression models of teleroentgenographic parameters, which can be corrected during surgery (2 group of indicators) depending on the parameters that usually do not change (1 group of indicators) were constructed and analyzed.
In young men, 10 of 27 possible reliable regression models with a coefficient of determination greater than 0.6 (R2 = from 0,642 to 0,995) were constructed, and in young women – 13 models from 27 possible (R2 = from 0,619 to 0,956). Both for young men and young women, the most models of indicators of the second group are built for linear dimensions – both young men and young women have 7 models from 9 possible each.
The constructed regression equations of teleroentgenographic indicators included into the second group according to the Schwarz A. M. method the most often comprise the following indicators of the first group: in young men – ar-Go distances according to Burstone C. J., N-CC according to Ricketts R. M., N-Se according to Schwarz A. M. and indicator N-S:S-Ar' according to Bjork A.; in young women – indicator S-ar:ar-Go according to Jarabak J. R., distances N-S according to Jarabak J. R. and ar-Go according to Burstone C. J. and angle POr-NBa according to Ricketts R. M.
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Abedi, Amir, S. P. H. Marashi, K. Sohrabi, M. Marvastian et S. M. H. Mirbagheri. « The Effect of Heat Treatment Parameters on Microstructure and Toughness of Austempered Ductile Iron (ADI) ». Advanced Materials Research 264-265 (juin 2011) : 409–14. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.409.
Texte intégralRésumé :
In this investigation, the effect of heat treatment parameters on the microstructure and impact energy as a measure of toughness of the austempered ductile cast iron (ADI) was studied. Yblocks were casted from ductile cast iron with following composition: 3.2% C, 2.5% Si, 1.09% Ni, 0.87% Cu, 0.5% Mo and 0.16%Mn. Charpy specimens (un-notched) were machined from the straight part of Y-blocks. All of specimens were heat treated with different conditions. Some of them were austenitized at 900°C for 60 min and then austempered at 250, 300, 350 and 400°C for various durations. Then, hardness test, impact test, optical microscopy and X-ray diffraction (XRD) were performed on the heat treated ductile iron samples. The results reveal the highest impact energy (105 J) for the sample austenitized at 900°C and austempered at 350°C for 150 min. The microstructure of this sample consisted of 28% austenite and broad ferrite needles.
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Bergman, Ola, Björn Lindqvist et Sven Bengtsson. « Influence of Sintering Parameters on the Mechanical Performance of PM Steels Pre-Alloyed with Chromium ». Materials Science Forum 534-536 (janvier 2007) : 545–48. http://dx.doi.org/10.4028/www.scientific.net/msf.534-536.545.
Texte intégralRésumé :
Powder grades pre-alloyed with 1.5-3 wt% chromium are suitable for PM steel components in high performance applications. These materials can be successfully sintered at the conventional temperature 1120 °C, although well-monitored sintering atmospheres with low oxygen partial pressures (<10-17-10-18 atm) are required to avoid oxidation. Mechanical properties of the Cralloyed PM grades are enhanced by a higher sintering temperature in the range 1120-1250 °C, due to positive effects from pore rounding, increased density and more effective oxide reduction. A material consisting of Astaloy CrM, which is pre-alloyed with 3 wt% Cr and 0.5 wt% Mo, and 0.6 wt% graphite obtains an ultimate tensile strength of 1470 MPa combined with an impact strength of 31 J at density 7.1 g/cm3, after sintering at 1250 °C followed by cooling at 2.5 °C/s and tempering.
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Cecchetti, W., M. A. Cerruto, M. Dal Bianco, C. Milani et F. Zattoni. « A Four-Year Experience with Holmium-YAG Laser : Parameters of use ». Urologia Journal 74, no 3 (juillet 2007) : 155–59. http://dx.doi.org/10.1177/039156030707400306.
Texte intégralRésumé :
In the last years, laser has gained increasingly high popularity in Endourology The newer generation Ho-YAG lasers represent the most updated laser used in Urology, being able to successfully treat both urinary stones and soft tissue lesions. The aim of this work was to report a multicentre 4-year experience using the Ho-YAG laser in the treatment of stones and soft tissue lesions, in order to offer parameters and modalities of use in several different situations. Materials and Methods Two urological Centers were asked between 2002 and 2005 to use Coherent Versa Pulse 20 Ho-YAG laser source in the treatment of urinary stones in 212 patients, and urinary soft tissue lesions (urethra, ureter or bladder neck strictures or urinary tract tumors) in 56 patients. According to the various situations (either stone fragmentation or treatment of soft tissue lesions), pulse frequency and energy per impulse were differently dosed and set. Results The following parameters were identified as the starting points for the correct use of the Ho-YAG laser: a) lithotripsy with rigid endoscope: 365 μm fiber, 0.8 - 1.2 Joule (J) energy and 6–8 Hz frequency; 365 μm fiber, 0.8–1.2 J energy and 10–12 Hz frequency; 550 μm fiber, 1.0–1.5 J energy and 10–12 Hz frequency. b) lithotripsy with flexible endoscope: 270 μm fiber, 0.6–1.0 J energy and 6–10 Hz frequency. c) soft tissue resection in case of: c1) ureteral stricture, 365 μm fiber, 0.6 J energy and 14–16 Hz frequency; c2) urethral stricture, 365 μm fiber, 0.7 J energy and 16–18 Hz frequency; c3) upper urinary tract tumors, 365 μm fiber, 0.7 J energy and 16 Hz frequency; c4) bladder tumors 365 μm fiber, 0.8 J energy and 16–20 Hz frequency; c5) bladder neck strictures, 365 μm fiber, 1.0 J energy and 16–18 Hz frequency. Conclusions In the light of these parameters, Ho-YAG laser is a very handy instrument for the treatment of both urinary stones and soft tissue lesions, which allows to put aside the current tools used for the same purposes.
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Li, Yuanchao, Lu Mi, Haibin Wang, Yuanzuo Li et Jianping Liang. « Design, Electron Transfer Process, and Opto-Electronic Property of Solar Cell Using Triphenylamine-Based D-π-A Architectures ». Materials 12, no 1 (8 janvier 2019) : 193. http://dx.doi.org/10.3390/ma12010193.
Texte intégralRésumé :
A series of D-π-A type dyes were designed based on the experimentally synthesized A1 by introducing different functional groups on the donor and π-spacer, and the optical and electrical properties were calculated by using density functional theory (DFT) and time-dependent DFT (TD-DFT). P1–P6 present highest light harvesting efficiency (LHE), driving force of electron injection ( Δ G i n j e c t ), reorganization energy ( Δ G r e g ) and e V O C . These critical parameters have a close relationship with the short-circuit current density ( J S C ) and open-circuit photovoltage ( V O C ), and lead to P1–P6 will exhibit higher efficiency. D4 also exhibit superior properties in the driving force of electron injection ( Δ G i n j e c t ), reorganization energy ( Δ G r e g ), which will lead to a higher short-circuit current density ( J S C ). We hope that these results will be helpful for experiments to synthesize new and highly efficient dyes.
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Langenderfer, Martin, Eric Bohannan, Jeremy Watts, William Fahrenholtz et Catherine E. Johnson. « Relating detonation parameters to the detonation synthesis of silicon carbide ». Journal of Applied Physics 131, no 17 (7 mai 2022) : 175902. http://dx.doi.org/10.1063/5.0082367.
Texte intégralRésumé :
Detonation synthesis of silicon carbide (SiC) nanoparticles from carbon liberated by negatively oxygen balanced explosives was evaluated in a 23 factorial design to determine the effects of three categorical experimental factors: (1) cyclotrimethylene-trinitramine (RDX)/2,4,6-trinitrotoluene (TNT) ratio, (2) silicon (Si) additive concentration, and (3) Si particle size. These factors were evaluated at low and high levels as they relate to the detonation performance of the explosive and the solid Si-containing phases produced. Detonation velocity and Chapman–Jouguet (C–J) detonation pressure, which were measured using rate stick plate dent tests, were evaluated. Solid detonation product mass, silicon carbide product concentration, and residual silicon concentration were evaluated using the x-ray diffraction analysis. The factors of Si concentration and the RDX:TNT ratio were shown to affect detonation performance in terms of detonation velocity and C–J pressure by up to 10% and 22%, respectively. Increased concentration of Si in the reactants improved the average SiC concentration in the detonation products from 1.9 to 2.8 wt. %. Similarly, increasing the ratio of RDX to TNT further oxidized detonation products and reduced the average residual Si remaining after detonation from 8.6 to 2.8 wt. %. A 70:30 mass ratio mixture of RDX to TNT loaded with 10 wt. % < 44 μm silicon powder produced an estimated 1.33 g of nanocrystalline cubic silicon carbide from a 150-g test charge. Using a lower concentration of added silicon with a finer particle size reduced SiC yield in the residue to 0.38 g yet improved the SiC to residual Si ratio to 1.64:1.
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Golubeva, M. V., O. V. Sych, E. I. Khlusova, G. D. Motovilina, E. V. Sviatysheva, S. V. Rogozhkin et A. A. Lukyanchuk. « Structure changes of high-strength economically alloyed steel 09KhGN2MD (09CrMnNi2MoCu) when tempering ». Voprosy Materialovedeniya, no 1(93) (6 janvier 2019) : 15–26. http://dx.doi.org/10.22349/1994-6716-2018-93-1-15-26.
Texte intégralRésumé :
Purpose of the present investigation is to determine the optimal heat treatment parameters that ensure yield strength over 690 MPa in combination with toughness of at least 35 J/cm2at temperature –70°C in new economically alloyed cold-resistant steel. The effect of various quenching and tempering parameters on mechanical properties, structure of steel and fracture mode of samples after impact tests at temperature –70°C has been studied. The relationship between the properties, structure and fracture mode of steel samples is shown. The optimal heat treatment parameters of new economically alloyed cold-resistant steel are determined.
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Chalothorn, Dan, et James E. Faber. « Strain-dependent variation in collateral circulatory function in mouse hindlimb ». Physiological Genomics 42, no 3 (août 2010) : 469–79. http://dx.doi.org/10.1152/physiolgenomics.00070.2010.
Texte intégralRésumé :
The extent (density and diameter) of the native (preexisting) collateral circulation in healthy tissues and the capacity of collaterals to enlarge/remodel in obstructive arterial disease are important determinants of ischemic injury. Evidence suggests that these parameters vary widely from yet-to-be-identified genetic and environmental factors. Recently, a locus on chromosome 7 was linked to less recovery of perfusion after femoral artery ligation in BALB/c and A/J versus C57BL/6 mouse strains. Moreover, evidence suggested that BALB/c and A/J share an allele(s) at this locus that is different from C57BL/6 mice. Here we tested the hypothesis that differences in collateral extent and/or remodeling underlie these findings. Compared with C57BL/6, BALB/c and A/J strains have fewer native collaterals in hindlimb (also confirmed in brain)—associated with greater reduction in perfusion immediately after femoral ligation, slower recovery of perfusion, greater hindlimb use impairment, and worse ischemia. However, A/J also differed from BALB/c in a number of these parameters, including having more robust collateral remodeling. Analysis of A/J → C57BL/6 chromosome substitution strains confirmed that a difference in an allele(s) on chromosome 7 conferred most, but not all, of the magnitude of the differences in collateral function. Additional studies of C57BL/6 × BALB/c F1 mice demonstrated that alleles of the C57BL/6 strain exert dominance for collateral traits. Finally, negative results were obtained from studies examining a previously identified candidate gene potentially responsible for these differences—Bcl2-associated athanogene-3. These findings emphasize the major contribution of genetic background to variation in the collateral circulation and its capacity to lessen ischemia in obstructive disease.
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Du, Zhe, Yongguang Hu, Yongzong Lu, Jing Pang et Xinping Li. « Design of Structural Parameters of Cutters for Tea Harvest Based on Biomimetic Methodology ». Applied Bionics and Biomechanics 2021 (22 juillet 2021) : 1–8. http://dx.doi.org/10.1155/2021/8798299.
Texte intégralRésumé :
Owing to their sharp teeth, crickets can eat through new shoots of the stalks of tea plants. Inspired by the special geometrical structure of the teeth of crickets, this study designed a biomimetic cutter to reduce the force and energy required to cut the stalks of tea plants. Therefore, four biomimetic cutters were considered: a, b, c, and d. Cutter a was a traditional cutter used for comparison with the other three cutters, which were biomimetic. The cutters were manufactured using 3D printing technology and assessed by a texture tester at different loading speeds (5, 10, and 15 mm/s, respectively). The results show that cutter c delivered better performance compared to cutter a at loading speeds of 5, 10, and 15 mm/s, respectively. However, at 15 mm/s loading speed, the maximum cutting forces required for cutters b and c were 9.43% and 6.04% lower, respectively, than that for cutter a (9.021 N). Similarly, the energies consumed by cutters b and c were 13.8% and 4.24% lower than that consumed by cutter a (1.225 J). In addition, cutter c delivered the best results compared to others. Based on the study results, it was concluded that the biomimetic cutters can thus help to optimize the tea harvest.
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Zuo, Duo, Liang Liang, Teng Wu, Zhao Li, Weiliang Xiong et Run Wu. « Research on the design of new high-strength and high-toughness steel and its manufacturing parameters ». Journal of Physics : Conference Series 2390, no 1 (1 décembre 2022) : 012085. http://dx.doi.org/10.1088/1742-6596/2390/1/012085.
Texte intégralRésumé :
Abstract The lightweight of the steel structure can be achieved by the high strength and high toughness of steel. In this paper, the composition design and optimal manufacturing process of the experimental steel were investigated. The fine and uniform microstructure of tempered sorbite can be obtained under the conditions of TMCP (Thermo Mechanical Control Process), 920 °C quenching, and 650 °C tempering for the steel by micro-alloying with Nb, V, and Ti. The steel has properties as follows: yield strength of 1015 MPa, tensile strength of 1076 MPa, elongation of 14.5%, and -40 °C AKV 81 J. The parameters of quenching and tempering heat treatment have a decisive influence on the size and distribution of ferrite grains and precipitates of tempered sorbite.
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Escolar, D., Ma R. Haro, A. Saucedo, J. Ayuso, A. Jimenez et J. A. Alvarez. « Determining Acid Equilibrium Constants by Means of Chromatic Parameters ». Applied Spectroscopy 50, no 10 (octobre 1996) : 1290–94. http://dx.doi.org/10.1366/0003702963905024.
Texte intégralRésumé :
A method has been developed for the determination of acid-base equilibrium constants, which is applicable to compounds that absorb in the visible. The tristimulus (X, Y, Z) and the colorimetric coordinate values ( L, a, b) of the chromatic space CIELAB 1976 are calculated by means of the transmittances of the entire spectral range. The curves, in the a,b plane, of chromatic differences vs. pH intersect at a pH value agreeing with the p Ka; this configuration occurs because a chromatic equilibrium of both species takes place at this point, which corresponds to the chemical equilibrium. With this method, the acidity constants are found easily and quickly, and they yield very good results. The validity of the method has been tested with the acid-base indicator bromophenol blue, obtaining p Ka= 3.943 at 25 °C; this result is compared with those obtained through the usual spectrophotometric methods. Also, thermodynamic magnitudes obtained from p Ka values at different temperatures from 20 to 70 °C have been determined, resulting in Δ H0 = -(13.93 ± 0.88) kj mol−1 Δ S0 = -(122.6 ± 2.8) J K−1 mol−1.
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Misra, RK, et CW Rose. « An examination of the relationship between erodibility parameters and soil strength ». Soil Research 33, no 4 (1995) : 715. http://dx.doi.org/10.1071/sr9950715.
Texte intégralRésumé :
Erosion rate of soil by the impact of raindrops and overland flow of water is often considered to be affected by the shear strength of surface soil. Physically based erosion models indicate a link between defined erodibility parameters and soil strength. The objectives of this paper are to determine erodibility parameters with the process-based erosion model GUEST for a. krasnozem soil of two contrasting strengths, and to examine the influence of soil strength on erodibility parameters. Soil beds of width 1 m and length 5.8 m, with and without compaction, were exposed to simulated, constant rate rainfall. A range of slopes was used. Detachment trays of width 300 mm and downslope length 200 mm containing soils of identical strength were placed at the same slope and exposed to the same rain in order to determine the effects of rainfall-driven processes alone on erosion. Soil strength was measured with a hand vane tester and a pocket penetrometer to determine whether compaction was effective in modifying soil strength. Temporal variation in sediment concentrations (c) for the large soil beds and detachment trays was measured for each slope and soil strength. The settling velocity characteristic of soil, with and without exposure to rain, was determined with the modified bottom withdrawal tube technique. Values of c decreased with increase in soil strength. The relationship between c and slope was influenced by soil strength in a manner consistent with the theoretical expectation of the role of soil strength in controlling erosion. Rilling during erosion was absent only when the soil was compacted. The average settling velocity of the soil exposed to rain (i.e. its depositability) was significantly lower than for the same soil not subjected to rain, indicating a breakdown of soil aggregates as a result of raindrop impact. Rainfall detachability parameters (estimated with GUEST) Were lower when soil strength was high. Runoff-driven erodibility parameters, namely the specific energy of entrainment (J), increased and the approximate erodibility parameter (�) decreased with increase in soil strength. The Variation in these erodibility parameters with soil strength was consistent with the theory implemented in GUEST. Detailed analysis of the relative contribution of rainfall- and runoff-driven processes to c at varying stream powers and soil strengths indicated that, at high soil strength, uncertainty in the values of J and � is high because of the higher contribution to c of rainfall-driven rather than runoff-driven processes. The adequacy of in situ measurement of soil strength as an indicator of soil erodibility is discussed in relation to the results presented.
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Wiester, Mildred J., William P. Watkinson, Daniel L. Costa, Kay M. Crissman, Judy H. Richards, Darrell W. Winsett et Jerry W. Highfill. « Ozone toxicity in the rat. III. Effect of changes in ambient temperature on pulmonary parameters ». Journal of Applied Physiology 81, no 4 (1 octobre 1996) : 1691–700. http://dx.doi.org/10.1152/jappl.1996.81.4.1691.
Texte intégralRésumé :
Wiester, Mildred J., William P. Watkinson, Daniel L. Costa, Kay M. Crissman, Judy H. Richards, Darrell W. Winsett, and Jerry W. Highfill. Ozone toxicity in the rat. III. Effect of changes in ambient temperature on pulmonary parameters. J. Appl. Physiol. 81(4): 1691–1700, 1996.—Pulmonary toxicity of ozone (O3) was examined in adult male Fischer 344 rats exposed to 0.5 parts/million O3 for either 6 or 23 h/day over 5 days while maintained at an ambient temperature (Ta) of either 10, 22, or 34°C. Toxicity was evaluated by using changes in lung volumes and the concentrations of constituents of bronchoalveolar lavage fluid that signal lung injury and/or inflammation. Results indicated that toxicity increased as Tadecreased. Exposures conducted at 10°C were associated with the greatest decreases in body weight and total lung capacity and the greatest increases in lavageable protein, lysozyme, alkaline phosphatase activity, and percent neutrophils. O3 effects not modified by Ta included increases in residual volume and lavageable potassium, glucose, urea, and ascorbic acid. There was a progressive decrease in lavageable uric acid with exposure at 34°C. Most effects were attenuated during the 5 exposure days and/or returned to normal levels after 7 air recovery days, regardless of prior O3 exposure or Ta. It is possible that Ta-induced changes in metabolic rate may have altered ventilation and, therefore, the O3 doses among rats exposed at the three different Ta levels.
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Chen, Jiayi, Zhihang Zhao, Zhigang Liu et Yangyang Fu. « Effects of tunable circuit parameters on pulsed discharge and input-output characteristics of a XeCl excimer laser ». Journal of Physics D : Applied Physics 57, no 13 (4 janvier 2024) : 135202. http://dx.doi.org/10.1088/1361-6463/ad172c.
Texte intégralRésumé :
Abstract High-pressure, pulsed discharge-pumped XeCl excimer lasers are operating in the ultraviolet range at a wavelength of 308 nm. In this paper, a one-dimensional fluid model coupled to a magnetic pulse compression (MPC) excitation circuit and a laser gain model is established for describing the discharge and laser output characteristics of XeCl excimer lasers. The effects of the peaking capacitor C p (the terminal of the MPC circuit) on the discharge properties and input-output characteristics are explored. The results reveal that C p plays a key role in suppressing discharge pulse oscillation, which in turn influences the peak value and duration of the laser pulse. By optimizing the capacitance, a maximum excimer formation efficiency of 6.6% and a maximum laser output efficiency of 5% (output energy of 1.26 J) are obtained when C p = 1.12 C s , where C s is the storage capacitor in the MPC circuit.
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Saqib, Abdul A. N., Ansa Farooq, Maryam Iqbal, Jalees Ul Hassan, Umar Hayat et Shahjahan Baig. « A Thermostable Crude Endoglucanase Produced by Aspergillus fumigatus in a Novel Solid State Fermentation Process Using Isolated Free Water ». Enzyme Research 2012 (8 juillet 2012) : 1–6. http://dx.doi.org/10.1155/2012/196853.
Texte intégralRésumé :
Aspergillus fumigatus was grown on chopped wheat straw in a solid state fermentation (SSF) process carried out in constant presence of isolated free water inside the fermentation chamber. The system allowed maintaining a constant vapor pressure inside the fermentor throughout the fermentation process. Crude endoglucanase produced by A. fumigatus under such conditions was more thermostable than previously reported enzymes of the same fungal strain which were produced under different conditions and was also more thermostable than a number of other previously reported endoglucanases as well. Various thermostability parameters were calculated for the crude endoglucanase. Half lives (T1/2) of the enzyme were 6930, 866, and 36 min at 60°C, 70°C, and 80°C, respectively. Enthalpies of activation of denaturation (ΔHD*) were 254.04, 253.96, and 253.88 K J mole−1, at 60°C, 70°C and 80°C, respectively, whereas entropies of activation of denaturation (ΔSD*) and free energy changes of activation of denaturation (ΔGD*) were 406.45, 401.01, and 406.07 J mole−1 K−1 and 118.69, 116.41, and 110.53 K J mole−1 at 60°C, 70°C and 80°C, respectively.
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Zurnadzhy, Vadym, Vasily Efremenko, Hossam Halfa, Bohdan Efremenko, Alexander Azarkhov, Yuliia Chabak et Natalia Zaichuk. « Effect of Austempering Parameters on Microstructure and Tensile/Impact Behaviours of Micro-Alloyed TRIP-Assisted Steel ». Materials Science Forum 1098 (29 septembre 2023) : 3–12. http://dx.doi.org/10.4028/p-xgxbj9.
Texte intégralRésumé :
The article is aimed at studying the effect of austempering temperature below and above Ms temperature on the phase-structural state and mechanical properties of 0.2 wt.% C TRIP-assisted steel micro-added with Nb, V, Mo, Cr. The samples were austenitized at a temperature close to the Ac3 point (900 °C) and held at 300 °C (below Ms), 350 °C (close to Ms) and 400 °C (above Ms) for 5-20 min. The work was performed using optical microscopy (OM), transmission electron microscopy (TEM), X-ray diffraction, and tensile/impact testing. It was found that austempering at the aforementioned modes ensures the multiphase structure consisting of carbide-free bainite, tempered martensite, ferrite and retained austenite (in different combinations). The optimal was austempering at a temperature close to Ms which provided an advanced complex of tensile properties (PSE of 23.9 GPa×%) and V-notched impact toughness (95 J/cm2). TRIP-effect contributed to these properties while the strain hardening process tended to be prolonged with increasing the austempering temperature.
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Fukal, Jiří, Ondřej Páv, Miloš Buděšínský, Jakub Šebera et Vladimír Sychrovský. « The benchmark of 31P NMR parameters in phosphate : a case study on structurally constrained and flexible phosphate ». Physical Chemistry Chemical Physics 19, no 47 (2017) : 31830–41. http://dx.doi.org/10.1039/c7cp06969c.
Texte intégralRésumé :
A benchmark for structural interpretation of the 31P NMR shift and the 2JP,C spin–spin coupling in the phosphate group was obtained by means of theoretical calculations and measurements in diethylphosphate and 5,5-dimethyl-2-hydroxy-1,3,2-dioxaphosphinane 2-oxide.
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Dmitriev, M. O., A. V. Chernysh et T. V. Chugu. « Cephalometric studies of Ukrainian boys and girls with physiological bite by the method of Charles J. Burstone ». Biomedical and Biosocial Anthropology, no 30 (29 mars 2018) : 62–67. http://dx.doi.org/10.31393/bba30-2018-09.
Texte intégralRésumé :
The analysis of scientific literature points to significant ethnic, racial, age and sexualdifferences in cephalometric indices obtained by the method of C. J. Burstone, whichnecessitates conducting similar cephalometric studies among different age and sexgroups of the population of Ukraine with physiological bite. The purpose of the study isto establish and analyze the cephalometric parameters by the method of C. J. Burstonein boys and girls of the Podillia region of Ukraine with orthognathic bite. Primary lateralteleroentgenograms of 38 boys and 55 girls with normal occlusion close to orthognathicbite, obtained using the Veraviewepocs 3D device, Morita (Japan), were taken fromthe data bank of the research center of the National Pirogov Memorial MedicalUniversity, Vinnytsya. Cephalometric measurements were performed according to therecommendations of C. J. Burstone. The statistical processing of the obtained resultswas carried out in the licensed package "Statistica 6.0" using nonparametric methodsfor evaluating the obtained results. When comparing the cephalometric parametersused in the analysis of C. J. Burstone between boys and girls with orthognathic bite inboys, the values of the following distances are significantly higher: Ar-Pt (PosteriorSection of Cranial Base), Pt-N (Anterior Section of Cranial Base), N-ANS (AnteriorUpper Facial Height), ANS-Gn (Anterior Lower Facial Height), PNS-N (Posterior UpperFacial Height), 1l-MP (Distance of Incisal Edge of 1L to Palatal Plane), 6u-NF (Distanceof Mesial Cusp of 6u to Palatal Plane), 6l-MP (Distance of Mesial Cusp of 6l toMandibular Plane), ANS-PNS (Maxillary Length), Ar-Go (Ramus Length), Go-Pog(Mandibular Length), B-Pog (distance from point Pog to point B, parallel to mandibularplane) and A-B (Distance of A to B on Occl. Plane); and in girls - only angle OP-HP(Angle of Occl. to Horizontal Plane). More than half of the cephalometric parametersobtained in the boys and girls of Podillia with orthognathic bite have reliable or tendencydifferences with the magnitude of the parameters given by C. J. Burstone, whichconfirms the need to establish their regional standards for correct use in Ukraine.
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Hu, Xin, Lijing Xie, Feinong Gao et Junfeng Xiang. « On the Development of Material Constitutive Model for 45CrNiMoVA Ultra-High-Strength Steel ». Metals 9, no 3 (22 mars 2019) : 374. http://dx.doi.org/10.3390/met9030374.
Texte intégralRésumé :
For the implementation of simulations for large plastic deformation processes such as cutting and impact, the development of the constitutive models for describing accurately the dynamic plasticity and damage behaviors of materials plays a crucial role in the improvement of simulation accuracy. This paper focuses on the dynamic behaviors of 45CrNiMoVA ultra-high-strength torsion bar steel. According to investigation of the Split-Hopkinson pressure bar (SHPB) and Split-Hopkinson tensile bar (SHTB) tests at different strain rate and different temperatures, 45CrNiMoVA ultra-high-strength steel is characterized by strain hardening, strain-rate hardening and thermal softening effects. Based on the analysis on the mechanism of the experimental results and the limitation of classic Johnson-Cook (J-C) constitutive model, a modified J-C model by considering the phase transition at high temperature is established. The multi-objective optimization fitting method was used for fitting model parameters. Compared with the classic J-C constitutive model, the fitting accuracy of the modified J-C model significantly improved. In addition, finite element simulations for SHPB and SHTB based on the modified J-C model are conducted. The SHPB stress-strain curves and the fracture morphology of SHTB samples from simulations are in good agreement with those from tests.
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Larcombe, Alexander N., Philip C. Withers et Stewart C. Nicol. « Thermoregulatory, metabolic and ventilatory physiology of the eastern barred bandicoot (Perameles gunnii) ». Australian Journal of Zoology 54, no 1 (2006) : 9. http://dx.doi.org/10.1071/zo05071.
Texte intégralRésumé :
Thermoregulatory, metabolic and ventilatory parameters measured for the Tasmanian eastern barred bandicoot (Perameles gunnii) in thermoneutrality (ambient temperature = 30°C) were: body temperature 35.1°C, basal metabolic rate 0.55 mL O2 g–1 h–1, wet thermal conductance 2.2 mL O2 g–1 h–1 °C–1, dry thermal conductance 1.4 J g–1 h–1 °C–1, ventilatory frequency 24.8 breaths min–1, tidal volume 9.9 mL, minute volume of 246 mL min–1, and oxygen extraction efficiency 22.2%. These physiological characteristics are consistent with a cool/wet distribution, e.g. high basal metabolic rate (3.33 mL O2 g–0.75 h–1) for thermogenesis, low thermal conductance (0.92 J g–1 h–1 °C–1 at 10°C) for heat retention and intolerance of high ambient temperatures (≥35°C) with panting, hyperthermia and high total evaporative water loss (16.9 mg H2O g–1 h–1).
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Landa-Castro, Midori, Diego Gómez-Pérez, Maria Guadalupe Montes de Oca Yemha, Mario Romero-Romo, Mirella Gutierrez-Arzaluz et Manuel Palomar-Pardavé. « Influence of Temperature on the Kinetic Parameters of the Pd-Ni Electroplating Process from Ethaline ». ECS Transactions 110, no 1 (13 février 2023) : 273–80. http://dx.doi.org/10.1149/11001.0273ecst.
Texte intégralRésumé :
In the present work, the kinetic parameters from the electrodeposition of bimetallic Pd-Ni nanoparticles on the surface of a glassy carbon electrode (GCE) were studied. These parameters are P1 directly related to the diffusion coefficient (D), P2 related to the numerical density of active sites (N0) and the nucleation frequency (A). In addition, the type of nucleation that occurs in electrodeposition, instantaneous or progressive. The electrolytic medium used was an ethaline deep eutectic solvent (DES) for electrodeposition due to its good electrochemical properties. Cyclic voltammetry (CV) and potentiostatic current density transients (j-t) were performed at two temperatures, 25 and 70 °C. The j-t values were used to generate theoretical fittings using the Scharifker and Hills, and the Díaz-Morales models for bimetallic phases.
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Marečková, Michaela, et Miloš Barták. « Short-term responses of primary processes in PS II to low temperature are sensitively indicated by fast chlorophyll fluorescence kinetics in Antarctic lichen Dermatocarpon polyphyllizum ». Czech Polar Reports 7, no 1 (1 janvier 2017) : 74–82. http://dx.doi.org/10.5817/cpr2017-1-8.
Texte intégralRésumé :
In this study, we investigated the effects of low temperature on the fast chlorophyll fluo-rescence transient (OJIP) and OJIP-derived parameters in chlorolichen Dermatocarpon polyphyllizum expossed to a gradually decreasing temperature (22°C, 18°C, 14°C, 12°C, 10°C, 7°C and 4°C). The segments of lichen thalli were exposed to a certain temperature either in dark- and light-adapted state for 10 minutes in order to evaluate the effects on chlorophyll fluorescence parameters. The initial photochemical phase of the transient (O-J) due to reduction of the primary quinone acceptor (QA) was found temperature dependent. The K-step was apparent for the samples measured at the temperature above 12°C, but not below 10oC in light-adapted lichen thalli. With the thallus temperature decrease, majority of the chlorophyll fluorescence parameters derived from OJIP (ET0/RC, Psi_0, and DI0/RC) showed no change in light-adapted samples but a decrease in dark-adapted samples. The effects of dark- / light-adaptation of the lichen samples on the OJIP and OJIP-derived parameters was attributed to the differences in production/utilization of high-energy products of primary photochemical processes of photosynthesis in dark- and light-adapted state, respectively. The other parameters (ABS/RC, TR0/RC) showed a decrease with thallus temperature decrease both in light- and dark-adapted samples. The results suggest that fast chlorophyll fluorescence trasient is an useful tool to investigate temperature-dependent changes in photosystem II in chlorolichens, their photobionts, respectively.
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Savkina, Marta. « EQUALITY OF LS AND AITKEN ESTIMATIONS OF THE HIGHER COEFFICIENT OF THE LINEAR REGRESSION MODEL IN THE CASE OF CORRELATED DEVIATIONS ». Journal of Numerical and Applied Mathematics, no 2 (136) (2021) : 64–72. http://dx.doi.org/10.17721/2706-9699.2021.2.06.
Texte intégralRésumé :
At the paper a linear regression model whose function has the form $f(x) = ax + b$, $a$ and $b$ — unknown parameters, is studied. Approximate values (observations) of functions $f(x)$ are registered at equidistant points $x_0$, $x_1$,..., $x_n$ of a line segment. It is also assumed that the covariance matrix of deviations is the Toeplitz matrix. Among all Toeplitz matrices, a family of matrices is selected for which all diagonals parallel to the main, starting from the (k +1)-th, are zero, $k = n/2$, $n$ — even. Elements of the main diagonal are denoted by $λ$, elements of the k-th diagonal are denoted by $c$, elements of the j-th diagonal are denoted by $c_{k−j}$ , $j = 1, 2,..., k − 1$. The theorem proved at the paper states that if $c_j = (k/(k + 1))^j c$, $j = 1, 2,..., k−1$, that the LS estimation and the Aitken estimation of the $a$ parameter of this model coincide for any values $λ$ and $c$, which provide the positive definiteness of the resulting matrix.
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Klein, H., E. Klisch et G. Winnewisser. « Rotational Spectra of Phosphorus Monosulfide up to 1 THz ». Zeitschrift für Naturforschung A 54, no 2 (1 février 1999) : 137–45. http://dx.doi.org/10.1515/zna-1999-0208.
Texte intégralRésumé :
Abstract The submillimeter-wave rotational spectrum of the PS radical in the electronic and vibrational ground state (X2 ΠI/2 , X2Π3/2) was recorded with the Cologne terahertz spectrometer in the fre-quency region between 540 GHz and 1.07 THz, covering rotational quantum numbers from J = 30.5 to 60.5. The PS radical has been produced by discharging PSCl3 buffered with Ar. For all transitions the Λ-doubling was resolved for both the 2ΠI/2 and 2Π3/2 states. For some transitions with ΔF = 0 the hyperfine structure (hfs) caused by the P-atom could partially be resolved even for rather high J values. Analysis of the complete rotational data set of PS allows the derivation of a full set of molecular parameters, including the rotational constants B, D, H, the fine-structure constants A,γ , Dγ , the parameters for the Λ-doubling p, Dp , q, and the magnetic hyperfine constants a, b, c, d, CI. All parameters have been determined, whereby a, c, and the nuclear spin rotation-constant CI were obtained for the first time.