scholarly journals REPRÉSENTATIONS CONCEPTUELLES D'ÉTUDIANTS DU SECONDAIRE PROFESSIONNEL: PROPRIÉTÉS PHYSIQUES DE LA DIODE NON POLARISÉE / CONCEPTUAL REPRESENTATIONS OF STUDENTS PROFESSIONAL SECONDARY: PHYSICAL PROPERTIES OF THE NON-POLARIZED DIODE

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Abdeljalil Métioui
Keyword(s):  
Physical Properties ◽  
Secondary Level ◽  
Professional School ◽  
Conceptual Representations ◽  
Nous Permet ◽  
Propriétés Physiques ◽  
Scientific Norm ◽  
Physical Phenomena ◽  
First Time

Une méthode de recherche de type qualitatif a permis d’identifier les représentations conceptuelles d’étudiants du secondaire professionnel (17 à 20 ans) au Québec, en ce qui concerne les propriétés physiques d’un objet technique, à savoir une diode non polarisée. Nous procédons à cette reconstitution à partir de moyens classiques, tels le questionnaire écrit et les entretiens individuels. Cette étude nous permet, d’une part, de mettre en évidence ces conceptions et, d’autre part, de proposer quelques orientations didactiques. Notre recherche démontre qu’après un enseignement formel, les conceptions des élèves interrogés sont erronées comparativement à celles communément acceptées. Ces résultats mettent en lumière une mauvaise appropriation de notions telles que les porteurs de charges mobiles (électrons et trous) et les porteurs de charges fixes (ions). Following the guidelines of qualitative type research, we shall in this paper reconstitute the conceptual representations by secondary level students at the professional school (ages 17-20) of physical phenomena which subtend the physical properties of the non-biased diode. For the first time, this study shows that their conceptions of these phenomena are erroneous. In a second time, we identify the physical phenomena on which the educator should facilitate the students to construct conceptions that conform to the scientific norm. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0772/a.php" alt="Hit counter" /></p>

scholarly journals ASKAP observations of multiple rapid scintillators reveal a degrees-long plasma filament

2021 ◽  
Vol 502 (3) ◽  
pp. 3294-3311
Author(s):  
Yuanming Wang ◽  
Artem Tuntsov ◽  
Tara Murphy ◽  
Emil Lenc ◽  
Mark Walker ◽  
...  
Keyword(s):  
Physical Properties ◽  
Angular Width ◽  
Scattering Medium ◽  
Central Frequency ◽  
Linear Arrangement ◽  
Plasma Filament ◽  
Kinematic Models ◽  
Tidal Stream ◽  
First Time ◽  
Insight Into

ABSTRACT We present the results from an Australian Square Kilometre Array Pathfinder search for radio variables on timescales of hours. We conducted an untargeted search over a 30 deg2 field, with multiple 10-h observations separated by days to months, at a central frequency of 945 MHz. We discovered six rapid scintillators from 15-min model-subtracted images with sensitivity of $\sim\! 200\, \mu$Jy/beam; two of them are extreme intra-hour variables with modulation indices up to $\sim 40{{\ \rm per\ cent}}$ and timescales as short as tens of minutes. Five of the variables are in a linear arrangement on the sky with angular width ∼1 arcmin and length ∼2 degrees, revealing the existence of a huge plasma filament in front of them. We derived kinematic models of this plasma from the annual modulation of the scintillation rate of our sources, and we estimated its likely physical properties: a distance of ∼4 pc and length of ∼0.1 pc. The characteristics we observe for the scattering screen are incompatible with published suggestions for the origin of intra-hour variability leading us to propose a new picture in which the underlying phenomenon is a cold tidal stream. This is the first time that multiple scintillators have been detected behind the same plasma screen, giving direct insight into the geometry of the scattering medium responsible for enhanced scintillation.

scholarly journals Background Error in WRF Model

2020 ◽  
Vol 16 ◽  
Keyword(s):  
Data Assimilation ◽  
Physical Properties ◽  
Covariance Matrix ◽  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Wrf Model ◽  
Background Error ◽  
Numerical Weather ◽  
Error Covariance ◽  
First Time

WRF model have been tuned and tested over Georgia’s territory for years. First time in Georgia theprocess of data assimilation in Numerical weather prediction is developing. This work presents how forecasterror statistics appear in the data assimilation problem through the background error covariance matrix – B, wherethe variances and correlations associated with model forecasts are estimated. Results of modeling of backgrounderror covariance matrix for control variables using WRF model over Georgia with desired domain configurationare discussed and presented. The modeling was implemented in two different 3DVAR systems (WRFDA andGSI) and results were checked by pseudo observation benchmark cases using also default global and regional BEmatrixes. The mathematical and physical properties of the covariances are also reviewed.

scholarly journals The Physical and Thermodynamic Functions of Borides

2017 ◽  
Vol 18 (1) ◽  
pp. 58-63
Author(s):  
N.Yu. Filonenko
Keyword(s):  
Free Energy ◽  
Physical Properties ◽  
Thermodynamic Functions ◽  
Point Of View ◽  
Energy Potential ◽  
High Temperature Expansion ◽  
Temperature Dependences ◽  
Function Calculation ◽  
First Time ◽  
Good Agreement

In the paper the physical properties and thermodynamic functions of borides Х2В (Х=W, Mo, Mn, Fe, Co, Ni та Cr) are studied with accounting for fluctuation processes. We use the microstructure analysis, the X-ray structural and the durometric analyses to determine the physical properties of alloys. In the paper it is determined the phase composition and physical properties of borides. In this paper for the first time it is determined the thermodynamic functions of borides using the Hillert and Staffansson model with accounting for the first degree approximation of high-temperature expansion for the free energy potential of binary alloys. We obtain the temperature dependences for such thermodynamic functions as Gibbs free energy, entropy, enthalpy and heat capacity Ср along with their values at the formation temperature for Х2В (Х=W, Mo, Mn, Fe, Co, Ni та Cr). The approach under consideration enables to give more thorough from the thermodynamic point of view description of borides formed from the liquid. The outcomes of the thermodynamic function calculation for borides are in good agreement with experimental data and results of other authors.

scholarly journals Analysis of the migration of a pollutant in the soil structure

2019 ◽  
pp. 130-134
Author(s):  
Maria Popa ◽  
Loredana Irena Negoita
Keyword(s):  
Grain Size ◽  
Physical Properties ◽  
Petroleum Product ◽  
Soil Structure ◽  
Petroleum Products ◽  
Depth Of Penetration ◽  
Liquid Petroleum Product ◽  
Accidental Pollution ◽  
Experimental Laboratory ◽  
First Time

This paper presents a study on the migration into a soil structure of a pollutant, a liquid petroleum product. Accidental pollution with a liquid petroleum product can also be considered to crack a transport pipeline. This leads to the displacement of the pollutant in the soil structure, both horizontally and vertically. The study presents an analysis of the migration velocity in the soil structure, with certain physical properties, of both the soil and the pollutant petroleum product. The penetration of petroleum products to a certain depth in soil is influenced by its humidity, grain size and density, pollution intensity, viscosity and pollutant density. It was possible to calculate for the first time at the experimental laboratory level the depth of penetration of the pollutant.

Mental causation

2018 ◽  
Author(s):  
Barry Loewer
Keyword(s):  
Physical Properties ◽  
Mental Causation ◽  
Causal Relevance ◽  
Scientific Psychology ◽  
Causal Relations ◽  
Mental Properties ◽  
Mental Events ◽  
Physical Phenomena ◽  
Completeness Of Physics

Both folk and scientific psychology assume that mental events and properties participate in causal relations. However, considerations involving the causal completeness of physics and the apparent non-reducibility of mental phenomena to physical phenomena have challenged these assumptions. In the case of mental events (such as someone’s thinking about Vienna), one proposal has been simply to identify not ‘types’ (or classes) of mental events with types of physical events, but merely individual ‘token’ mental events with token physical ones, one by one (your and my thinking about Vienna may be ‘realized’ by different type physical states). The role of mental properties (such as ‘being about Vienna’) in causation is more problematic. Properties are widely thought to have three features that seem to render them causally irrelevant: (1) they are ‘multiply-realizable’ (they can be realized in an indefinite variety of substances); (2) many of them seem not to supervene on neurophysiological properties (differences in mental properties do not always depend merely on differences in neurophysiological ones, but upon relations people bear to things outside their skin); and (3) many of them (for example, ‘being painful’) seem inherently ‘subjective’ in a way that no objective physical properties seem to be. All of these issues are complicated by the fact that there is no consensus concerning the nature of causal relevance for properties in general.

scholarly journals The Molecular Outflow and CO Bullets in HH111

1997 ◽  
Vol 182 ◽  
pp. 141-152 ◽  
Author(s):  
J. Cernicharo ◽  
R. Neri ◽  
Bo Reipurth
Keyword(s):  
High Velocity ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Molecular Gas ◽  
Kinetic Temperature ◽  
Low Velocity ◽  
Molecular Outflow ◽  
Hh Objects ◽  
Physical Phenomena ◽  
First Time

We present high angular resolution observations of the molecular outflow associated with the optical jet and HH objects of the HH111 system. Interferometric observations in the CO J =2–1 and J =1–0 lines of the high velocity bullets associated with HH111 are presented for the first time. The molecular gas in these high velocity clumps has a moderate kinetic temperature and a mass of a few 10–4 M⊙ per bullet. We favor the view that HH jets and CO bullets, which represent different manifestations of the same physical phenomena, are driving the low-velocity molecular outflow.

General Mathematical Model of Multi-Arm Cooperating Robots With Elastic Interconnection at the Contact

1997 ◽  
Vol 119 (4) ◽  
pp. 707-717 ◽  
Author(s):  
Milovan Z˘ivanovic´ ◽  
Miomir Vukobratovic´
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Dynamic Environment ◽  
Six Degrees Of Freedom ◽  
General Mathematical Model ◽  
Cooperating Robots ◽  
Six Degree Of Freedom ◽  
Physical Phenomena ◽  
First Time ◽  
Object Dynamic

The procedure of modeling and the complete general form mathematical model of manipulators with six degrees of freedom in cooperative work are presented in the paper, together with the solution of undefiniteness problem with respect to force distribution. For the first time, a system of active spatial six-degree-of-freedom mechanisms elastically interconnected with the object (dynamic environment) is modeled. The reason for the emergence of the undefiniteness problem with respect to force is explained and the procedure for solving this problem given. Unlike the approaches given in the available literature, the undefiniteness problem with respect to force is solved in accordance with physical phenomena. The modeling procedure is illustrated by a simplified example.

Local Temperature Determination Using Elfs Spectroscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 997-998
Author(s):  
M. Qian ◽  
M. Sarikaya ◽  
E. A. Stern
Keyword(s):  
Fine Structure ◽  
Local Temperature ◽  
Temperature Changes ◽  
Structure Information ◽  
Temperature Determination ◽  
Simultaneous Imaging ◽  
Quantitative Measurements ◽  
High Resolution Tem ◽  
Physical Phenomena ◽  
First Time

ELFS spectroscopy (energy loss fine structure) is used to obtain local atomic structure information It can outperform XAFS (x-ray absorption fine structure) not only because of its low Z element sensitivity, but also because of its high spatial resolution and the capability of combining other high resolution TEM measurements. Although TEM continues to gain importance as an indispensable and unique tool to study nanoscale phenomena by providing simultaneous imaging, diffraction, and spectroscopy information, direct observation and quantitative measurements of physical phenomena are also desirable. This paper gives a first-time demonstration of such a measurement, namely local temperature determination in a TEM sample by ELFS.The principle is simple and as follows. One can measure, with ELFS, the atomic distances up to ±0.01 Å accuracy for the fist shell (typically around 2 Å ) and the second shell (around 3-4 Å). Atomic distances in a sample will change when its temperature changes, the phenomena that are coupled by the macroscopic temperature dependent lattice expansion.

scholarly journals Complex ceramic structures. I. Weberites

2009 ◽  
Vol 65 (3) ◽  
pp. 269-290 ◽  
Author(s):  
Lu Cai ◽  
Juan C. Nino
Keyword(s):  
Physical Properties ◽  
Ionic Radius ◽  
Structural Features ◽  
Stability Field ◽  
Bond Ionicity ◽  
Coordination Environment ◽  
Technological Potential ◽  
Axial Transformation ◽  
First Time ◽  
Selection Of

The weberite structure (A 2 B 2 X 7) is an anion-deficient fluorite-related superstructure. Compared with fluorites, the reduction in the number of anions leads to a decrease in the coordination number of the B cations (VI coordination) with respect to the A cations (VIII coordination), thus allowing the accommodation of diverse cations. As a result, weberite compounds have a broad range of chemical and physical properties and great technological potential. This article summarizes the structural features of weberite and describes the structure in several different ways. This is the first time that the stacking vector and stacking angle are used to represent the weberite structure. This paper also discusses the crystallographic relationship between weberite, fluorite and pyrochlore (another fluorite-related structure). The cation sublattices of weberite and pyrochlore are correlated by an axial transformation. It has been shown that the different coordination environment of anions is due to the alternating layering of the AB 3 and A 3 B close-packed cation layers. A stability field of weberite oxides is proposed in terms of the ratio of ionic radius of cations and relative bond ionicity. In addition, a selection of weberite compounds with interesting properties is discussed.

Low Thermal Budget Techniques For Controlling Stress In Si1-XGeX Deposited At 210°C

2006 ◽  
Vol 910 ◽  
Author(s):  
Sherif Sedky ◽  
Omar Mortagy ◽  
Ann Witvrouw
Keyword(s):  
Physical Properties ◽  
Strain Gradient ◽  
Silicon Germanium ◽  
Laser Annealing ◽  
Excimer Laser Annealing ◽  
High Hydrogen ◽  
High Laser ◽  
The Cost ◽  
Low Thermal Budget ◽  
First Time

AbstractThis work reports, for the first time, on the possibility of realizing surface micromachined silicon germanium structures at 210°C, which have extremely low strain gradient (μm-1). This extremely low strain gradient is obtained by tuning the physical properties of Si1-xGex, locally, without affecting the underlying layers, by excimer laser annealing. Tuning the laser annealing condition to optimize the physical properties of PECVD Si1-xGex is challenging, especially for films deposited at low temperatures (~ 250°C or lower) due to the high hydrogen content and the poor adhesion of these films. Furthermore, optimizing some properties might be at the cost of others. To clarify this issue, it is interesting to note that reducing the electrical resistivity implies using high laser pulse fluence. This however will increase mean stress, strain gradient and surface roughness as will be shown in this work.

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