scholarly journals The properties of flow of liquid He ll

1939 ◽  
Vol 172 (951) ◽  
pp. 467-491 ◽  
Keyword(s):  
Cross Section ◽  
Average Velocity ◽  
Radial Flow ◽  
Square Root ◽  
Parallel Plates ◽  
A Value ◽  
Upper Limit ◽  
Flow Through ◽  
The Subject

The problem of the viscosity of liquid He ll has been the subject of several recent investigations. In their experiments, Misener, Burton and others at Toronto (1935 a, b ) and later MacWood (1938) at Leiden used the methods of oscillating cylinder and disk respectively. Kapitza (1938) employed radial flow between parallel plates, and Giauque, Stout and Barieau (1938), Burton (1938), and the present authors (1938 a, b ) have used the method of flow through capillaries. There has been wide disagreement among the investigators with regard to the magnitude of the viscosity, and the determination of the value by the different investigators varies from an upper limit of 5 × 10 -9 c.g.s. units, as found by Kapitza (1938), to a value of 10 -5 c.g.s. units, as observed by Burton (1938). In addition to this the present authors reported (1938 a ) that, at least for long, narrow capillaries, the flow of liquid He ll appeared to be non-classical in that the velocity of flow bore a relation to the pressure, which corresponded neither to laminar nor turbulent conditions. Flow is classically defined as laminar when the average velocity over the cross-section of the tube is directly proportional to the hydrostatic pressure which produces the flow. At sufficiently high velocity, the flow ceases to be laminar; it becomes turbulent and the velocity is then proportional to the square root of the pressure. It was observed that for He ll in long, narrow capillaries the velocity became almost independent of pressure and the suggestion was advanced that this might be attributed to slip on the walls of the capillary.

scholarly journals Upper-limit determination of resonant trielectronic recombination cross-section for krypton using crystal channeling

2000 ◽  
Vol 61 (2) ◽  
Author(s):  
M. Chevallier ◽  
C. Cohen ◽  
N. Cue ◽  
D. Dauvergne ◽  
J. Dural ◽  
...  
Keyword(s):  
Cross Section ◽  
Upper Limit

scholarly journals On the measurement of the dielectric constants of liquids, with a determination of the dielectric constant of benzene

1929 ◽  
Vol 123 (792) ◽  
pp. 664-685 ◽  
Keyword(s):  
Dielectric Constant ◽  
Physical Properties ◽  
Dielectric Constants ◽  
Experimental Conditions ◽  
The Past ◽  
A Value ◽  
The Subject ◽  
Important Indication

It has long been recognised that the dielectric constant of a substance gives an important indication of its constitution, and the classical papers of Nernst and Drude giving methods for the determination of dielectric constants, have been followed by a long series of papers giving the dielectric constants of several hundreds of pure liquids and solutions. Since the publication of Debye’s dipole theory in 1912, the literature of the subject has become even more voluminous than before. In surveying the mass of data one is struck by the very large discrepancies which exist in the values obtained by different observers for any one substance, and it is very difficult to decide whether they are due to the difficulty of pre­paring and purifying the substance, differences in experimental conditions such as frequency of the applied E. M. F., or errors in the methods of measure­ment. In order to make it possible to compare the results of different observers, and to provide a fundamental basis for new measurements, it is important that the value of at least one standard liquid should be known with unquestion­able accuracy. The object of the present investigation was to provide such a value. Benzene was chosen as the standard liquid since it has been very widely used in the past, and it is used as a standard in the measurement of other physical properties.

A determination of the effective viscosity for the Brinkman–Forchheimer flow model

1994 ◽  
Vol 258 ◽  
pp. 355-370 ◽  
Author(s):  
R. C. Givler ◽  
S. A. Altobelli
Keyword(s):  
Effective Viscosity ◽  
Average Velocity ◽  
Flow Model ◽  
High Porosity ◽  
Rigid Foam ◽  
Nmr Techniques ◽  
Flow Through ◽  
Forchheimer Flow ◽  
Average Velocity Profile

The effective viscosity μe for the Brinkman–Forchheimer flow (BFF) model has been determined experimentally for steady flow through a wall-bounded porous medium. Nuclear magnetic resonance (NMR) techniques were used to measure non-invasively the ensemble-average velocity profile of water flowing through a tube filled with an open-cell rigid foam of high porosity (ϕ = 0.972). By comparing these data with the BFF model, for which all remaining parameters were measured independently, it was determined that μe = (7.5+3.4−2.4)μf, where μf was the viscosity of the fluid. The Reynolds number, based upon the square root of the permeability, was 17.

Inlet and Outlet Pressure-Drop Effects on the Determination of Permeability and Form Coefficient of a Porous Medium

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
C. Naaktgeboren ◽  
P. S. Krueger ◽  
J. L. Lage
Keyword(s):  
Porous Medium ◽  
Pressure Drop ◽  
Parallel Plates ◽  
Pressure Drops ◽  
Outlet Pressure ◽  
Medium Length ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
Definition Of

The determination of permeability K and form coefficient C, defined by the Hazen-Dupuit-Darcy (HDD) equation of flow through a porous medium, requires the measurement of the total pressure drop caused by the porous medium (i.e., inlet, core, and outlet) per unit of porous medium length. The inlet and outlet pressure-drop contributions, however, are not related to the porous medium length. Hence, for situations in which these pressure drops are not negligible, e.g., for short or very permeable porous media core, the definition of K and C via the HDD equation becomes ambiguous. This aspect is investigated analytically and numerically using the flow through a restriction in circular pipe and parallel plates channels. Results show that inlet and outlet pressure-drop effects become increasingly important when the inlet and outlet fluid surface-fraction φ decreases and the Reynolds number Re increases for both laminar and turbulent flow regimes. A conservative estimate of the minimum porous medium length beyond which the core pressure drop predominates over the inlet and outlet pressure drop is obtained by considering a least restrictive porous medium core. Finally, modified K and C are proposed and predictive equations, accurate to within 2.5%, are obtained for both channel configurations with Re ranging from 10−2 to 102 and φ from 6% to 95%.

scholarly journals NORMATIVE VALUE OF APPROACHES TO THE STUDY OF PROCREATION

2021 ◽  
pp. 333-341
Author(s):  
Tatiana A. Sidorova ◽  
Keyword(s):  
Social Regulation ◽  
Human Reproduction ◽  
Social Sciences And Humanities ◽  
A Value ◽  
Cultural Conditioning ◽  
Demographic Processes ◽  
The Subject ◽  
Methodological Approaches ◽  
Normative Value

The article analyzes the approaches and methods used when studying procreation, which is understood to mean human reproduction in the value-based aspects. The latest trends in childbearing are becoming the subject of not only demography but also various studies in social sciences and humanities. In scientific and mundane discourses, the term «reproduction» prevails in the designation of procreation. The concept of «procreation» is appropriate to use in the axiological approach since it contains an indication of the ways of understanding (description, cognition, designation in language and discourse) human reproduction included in the process of creation, not production, of man. The emphasis on the value-semantic determinism of procreation allows us to note the correlation what and how is studied about childbearing and the way the obtained knowledge affects reproductive aspirations and intentions. There are distinguished pronatal and antenatal orientations in the methodological approaches to the study of modern procreative processes. Procreative understanding is associated with a pronatal position in the motivation and social regulation of childbearing. The author concludes about normative value of different approaches and methods in research for procreation. Scientific discourse normalizes the perception of the latest trends in the childbearing area. The article indicates that qualitative methods in the study of procreation are in demand since they allow one to describe the dynamic and subjective moments in its phenomena and do not lay claim to the universality of the established patterns, which corresponds to the recognition of cultural conditioning and value-based dependence in demographic processes. The paper critically assesses the idea of universality of rationalization criteria in the study of childbirth, which is widespread among demographers. When proceeding from the idea of a value-based determination of procreation, it is necessary to take into account and normalize irrational factors in the motivation of childbearing.

MULTIPIONIC FINAL STATES AT CELSIUS/WASA

2005 ◽  
Vol 20 (02n03) ◽  
pp. 668-670
Author(s):  
◽  
C. PAULY ◽  
L. DEMIRÖRS ◽  
V. KLOSE ◽  
W. SCOBEL ◽  
...  
Keyword(s):  
Cross Section ◽  
Simultaneous Measurement ◽  
Dalitz Plot ◽  
Slope Parameter ◽  
Final States ◽  
World Average ◽  
Upper Limit ◽  
The World ◽  
Preliminary Determination

The simultaneous measurement of prompt and resonant 3π0 production at CELSIUS/WASA is used to deduce an upper limit for the pp→pp3π0 cross section of σ=1μb for Tp=1360 MeV . A preliminary determination of the slope parameter α for the η→3π0 Dalitz plot based on ca. 11700 events agrees in sign with the world average.

scholarly journals Determination of the voltage drop on a high-current vacuum arc discharge under conditions of a limited cross-section of the plasma flow

2021 ◽  
Vol 2064 (1) ◽  
pp. 012019
Author(s):  
A G Rousskikh ◽  
A S Zhigalin ◽  
V I Oreshkin ◽  
P Artyomov
Keyword(s):  
Cross Section ◽  
Plasma Flow ◽  
Voltage Drop ◽  
Arc Discharge ◽  
Vacuum Arc ◽  
High Current ◽  
Plasma Gun ◽  
Flow Through ◽  
Arc Current

Abstract The work is devoted to the study of the high-current vacuum arc discharge characteristics under conditions of a limited cross-section of the plasma flow. The experiments were carried out on the IMRI-5 setup with a sinusoidal arc current amplitude of 300–350 kA and a rise time of 500 ns. Aluminum rods with diameters from 3 to 7 mm were used as a cathode. The plasma flow was formed in a channel whose diameter was equal to that of the cathode. The features of the formation of a plasma jet with various configurations of the used plasma gun are described. The electrophysical parameters of the arc discharge are presented. Theoretical estimates of the voltage drop across the high-current arc during the outflow of a plasma flow through holes with a limited diameter are provided.

scholarly journals The Momentum Transfer Cross Section for Electrons in Helium Derived from Drift Velocities at 77°K

1970 ◽  
Vol 23 (5) ◽  
pp. 667 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
AG Robertson
Keyword(s):  
Energy Range ◽  
Momentum Transfer ◽  
Cross Section ◽  
Scattering Length ◽  
Direct Determination ◽  
A Value ◽  
Energy Dependent ◽  
Momentum Transfer Cross Section

Drift velocities of electrons in helium at 76.8�K have been measured for 8 X lO−20 ≤ E/N ≤ 2 X lO−17 V cm2. From these data, and the earlier measurements of Crompton, Elford, and Jory made at 293�K, the energy-dependent momentum transfer cross section has been determined for electrons with energies between 0.008 and 6 eV. The present cross section agrees with that of Crompton, Elford, and Jory to within 1 %. The extension of the energy range to 8 meV permits a direct determination of the scattering length, for which a value of 1.19 ao is obtained.

scholarly journals IMPLEMENTASI SISTEM MANAJEMEN MUTU (SMM) ISO 9001:2008 DI SMK MA’ARIF 1 WATES KULON PROGO

2017 ◽  
Vol 9 (2) ◽  
pp. 152
Author(s):  
Maryadi Maryadi ◽  
Lantip Diat Prasojo
Keyword(s):  
Quality Management ◽  
Quality Management System ◽  
Iso 9001 ◽  
Mixed Design ◽  
Supplier Relationships ◽  
Implementation Quality ◽  
A Value ◽  
The Subject ◽  
Implementation Level

AbstrakTujuan penelitian adalah untuk mengetahui implementasi SMM ISO 9001:2008, hambatan dan penyelesaiannya dalam implementasi SMM ISO 9001:2008. Penelitian ini menggunakan desain campuran untuk mendeskripsikan implementasi SMM ISO 9001:2008. Penelitian dilakukan di SMK Ma’arif 1 Wates dengan subjek kepala sekolah, wakil kepala, QMR, guru, orang tua siswa, dan siswa. Objek penelitian adalah SMM ISO 9001:2008. Pengumpulan data menggunakan lembar pengamatan dokumen, kuesioner dan wawancara. Tingkat implementasi SMM ISO dinyatakan dalam bentuk persentase. Hasil penelitian ini menyimpulkan bahwa di SMK Ma’arif 1 Wates, implementasi SMM ISO 9001:2008 memperoleh nilai fokus pada pelanggan 83,95%, kepemimpinan 65,53%, partisipasi karyawan 76,67%, pendekatan proses 72%, pendekatan sistem 75%, perbaikan berkelanjutan 75,13%, pendekatan faktual 64%, hubungan pemasok 74,64%. Hambatan yang terjadi dalam implementasi SMM ISO 9001:2008 adalah pada pendekatan faktual dalam pengambilan keputusan kurang efektif. Penyelesaian hambatan tersebut adalah dengan melakukan penetapan data, penghimpunan data yang sesuai dan efektif, dan analisis data kefektifan sistem manajemen mutu.Kata kunci: implementasi, Sistem Manajemen Mutu (SMM) ISO 9001:2008AbstractThe purpose of this study is to determine the implementation of QMS ISO 9001: 2008, the constraints and the solutions in the implementation of QMS ISO 9001: 2008. This study used a mixed design to describe the implementation of QMS ISO 9001: 2008. The setting was SMK Ma’arif 1 Wates with the subject principals, deputy head, QMR, teachers, parents, and students. The objects of this study were QMS ISO 9001: 2008. The data was collected through the observation sheet documents, questionnaires and interviews. The ISO QMS implementation level was in a percentage. The results of this study show that in SMK Ma’arif 1 Wates, implementation of QMS ISO 9001: 2008 obtained a value of customer focus 83.95%, leadership 65.53%, employee participation 76.67%, process approach 72%, system approach 75 %, continual improvement75.13%, factual approach 64%, and supplier relationships 74.64%. The constraint that occurs in the implementation of QMS ISO 9001: 2008 is in the management principle of factual approach to decision making, and the solution is the determination of the data, appropriate and effective data collection, and the analysis of the effectiveness of the quality management system.Keywords: implementation, Quality Management System (QMS) ISO 9001: 2008

Low-energy displacement damage and the effect on the AEM of Ceramics

1990 ◽  
Vol 48 (4) ◽  
pp. 822-823
Author(s):  
D. G. Howitt ◽  
D.L. Medlin ◽  
M. M. Cluckie
Keyword(s):  
Carbon Atom ◽  
Cross Section ◽  
High Voltage ◽  
Analytical Electron Microscopy ◽  
Threshold Energy ◽  
Ceramic Materials ◽  
Small Displacement ◽  
A Value ◽  
Beam Currents

The observation that the signal from light elements such as carbon, oxygen, and nitrogen decreases in strength with time is to be expected for displacement in ceramic materials at high voltage, not only because the momentum transfer from an electron is more favorable, but also because the lattices are often full of defects. Even though the sensitivities of these materials can be below that of close parked metals at high voltage, during analytical electron microscopy the beam currents are sufficiently intense that the effect can be substantial. The loss rates for the signal are however quite predictable in the early stages and need not interfere with quantitative assessments of composition.An example of the loss of carbon signal from titanium carbide is shown in Figure 1 and a determination of the overall cross-section for carbon loss at 100 keV indicates a value close to 0.3 barns. This is about the cross-section for carbon displacement at 20 eV which is a conservative estimate of the binding energy for carbon in the lattice. Early experiments on vanadium carbide (Venables, 1969) indicate a similar overall cross-section however the threshold energy for the electrons to induce the damage is about only 5 eV. These results are consistent with the transfer of about 5 eV from an incident electron inducing a very small displacement of the carbon atom, of the order of an interatomic distance, with a damage cross-section of about 200 barns. Since the process needs to be repeated several times before the carbon atom is lost from the specimen the measured cross-section is proportionality reduced.

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