Friction and resistance coefficients by end launching

2015 ◽  
pp. 561-565
Author(s):  
K Žiha ◽  
T Uroda ◽  
R Fabris ◽  
M Ivančević
Keyword(s):  
Resistance Coefficients

Time Dependances of the Resistance Coefficients of Polymeric Materials

INEOS OPEN ◽  
2020 ◽  
Vol 3 ◽  
Author(s):  
A. V. Matseevich ◽  
◽  
A. A. Askadskii ◽  
Keyword(s):  
Time Dependence ◽  
Physical Mechanism ◽  
Polymeric Materials ◽  
Resistance Coefficient ◽  
Constant Stress ◽  
Time To Rupture ◽  
Structure Sensitive ◽  
Material Durability ◽  
Resistance Coefficients ◽  
Extremal Character

One of the possible approaches to the analysis of a physical mechanism of time dependence for the resistance coefficients of materials is suggested. The material durability at the constant stress is described using the Zhurkov and Gul' equations and the durability at the alternating stress—using the Bailey criterion. The low strains lead to structuring of a material that is reflected in a reduction of the structure-sensitive coefficient in these equations. This affords 20% increase in the durability. The dependence of the resistance coefficient assumes an extremal character; the maximum is observed at the time to rupture lg tr ≈ 2 (s).

THE PROBLEM OF IDENTIFICATION OF HYDRAULIC RESISTANCE COEFFICIENTS IN MAKISTRAL GAS PIPELINE

2021 ◽  
pp. 6-11
Author(s):  
G. Gasymov
Keyword(s):  
Hydraulic Resistance ◽  
Group Identification ◽  
Numerical Approach ◽  
Transportation Systems ◽  
Gas Pipeline ◽  
Closed Loops ◽  
Hydraulic Network ◽  
Resistance Coefficients ◽  
Operating Regimes

A numerical approach, based on obtaining design formulas for the determination of hydraulic resistance coefficients of sites in pipeline transportation systems in the presence of the results of observations over a gas pipeline operating regimes, is proposed. The representation of the hydraulic network in the form of a directed graph allows to essentially reduce the number of equations in the system down to the number of closed loops. In the software implementation of the method described, for the solution of practical problems, group identification of the hydraulic resistance coefficients is provided for every eventuality.

Tribological Characteristics of Thermomechanically Processed 7075 Al Alloy Through Nano-scratch Characterization

2021 ◽  
pp. 135065012110397
Author(s):  
Souriddha Sanyal ◽  
Ashoktaru Chakraborty ◽  
Angshuman Sarkar ◽  
Susanta K Pradhan ◽  
Utpal Madhu ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Tribological Characteristics ◽  
Temperature Deformation ◽  
Al Alloy ◽  
Thermal Treatments ◽  
Plastic Energy ◽  
Recovery Resistance ◽  
Aa 7075 ◽  
Hardness Values ◽  
Resistance Coefficients

Age-hardenable Al–Zn–Mg–Cu (AA 7075) alloys can be fortified by precipitation solidifying because of precipitation of the MgZn2 intermetallic stages. Furthermore, grain refinement and high dislocation density can also be opted for strengthening purposes. A low-temperature deformation enhances the dislocation density and also facilitates the grains recovery to strengthen the component. The present study combines artificial aging (at 120 °C) and sub-zero (∼−20 ˚C) temperature rolling to achieve strengthening. Various sequences and combinations of these mechanical and thermal treatments are performed and the effects of these treatments on the tribological characteristics of the alloy are studied by nano-scratch measurements. The tribological characteristics are indicated by coefficient of friction ( μ), plastic energy ( PE), recovery index ( η), recovery resistance parameter ( Rs), etc. of each sample. The widths of the scratch are further utilized to calculate the scratch hardness values ( Hs), wear resistance coefficients ( Rw) and the coefficient of wear ( K) with the help of Archard's equation.

scholarly journals The geometric parameters of plants on the spur dykes in a selected section of the Odra River

2018 ◽  
Vol 45 ◽  
pp. 00110
Author(s):  
Magda Hudak
Keyword(s):  
Water Surface ◽  
Flow Resistance ◽  
Water Levels ◽  
Flow Conditions ◽  
Plant Structure ◽  
Central Section ◽  
Quantitative Characteristics ◽  
Odra River ◽  
The Impact ◽  
Resistance Coefficients

Spur dykes are structures for regulating rivers. They are designed for medium water levels, when spur dyke tops are above the water surface. In the central section of the Odra River the water level is changeable, and the spur dykes work in different hydrological conditions: as non-submerged and submerged. Correct recognition of the plant structure growing on the spur dykes is of great importance in the context of the subsequent allocation of its measure related to the hydraulic action, among others coefficients of resistance of plant zones and refers mainly to grasses. In hydraulic calculations, it is required to determine the value of flow resistance coefficients. In such a departure, the flow is omitted in the area occupied by vegetation. Therefore, it is necessary to know the quantitative characteristics of overgrowth. Vegetation should be presented in the form of a model reflecting the impact of plants growing on the spur dykes and their impact on the water flow conditions in the river. Literature data are not very numerous and are still awake unsatisfied. The paper presents the results of research on the density of vegetation on the Odra River in the Nowa Sól region.

scholarly journals The inverse coefficient problem of heat transfer in layered nanostructures

2017 ◽  
Vol 20 (3) ◽  
pp. 213-219
Author(s):  
K. K. Abgarian ◽  
R. G. Noskov ◽  
D. L. Reviznikov
Keyword(s):  
Heat Transfer ◽  
Inverse Problem ◽  
Thermal Resistance ◽  
Transfer Problem ◽  
Dominant Role ◽  
Rapid Development ◽  
Problem Solution ◽  
Microwave Range ◽  
Contact Thermal Resistance ◽  
Resistance Coefficients

The rapid development of electronics leads to the creation and use of electronic components of small dimensions, including nanoelements of complex, layered structure. The search for effective methods for cooling electronic systems dictates the need for the development of methods for the numerical analysis of heat transfer in nanostructures. A characteristic feature of energy transfer in such systems is the dominant role of contact thermal resistance at interlayer interfaces. Since the contact resistance depends on a number of factors associated with the technology of heterostructures manufacturing, it is of great importance to determine the corresponding coefficients from the results of temperature measurements.The purpose of this paper is to evaluate the possibility of reconstructing the thermal resistance coefficients at the interfaces between layers by solving the inverse problem of heat transfer.The complex of algorithms includes two major blocks — a block for solving the direct heat transfer problem in a layered nanostructure and an optimization block for solving the inverse problem. The direct problem was formulated in an algebraic (finite difference) form under the assumption of a constant temperature within each layer, which is due to the small thickness of the layers. The inverse problem was solved in the extreme formulation, the optimization was carried out using zero-order methods that do not require the calculation of the derivatives of the optimized function. As a basic optimization algorithm, the Nelder—Mead method was used in combination with random restarts to search for a global minimum.The results of the identification of the contact thermal resistance coefficients obtained in the framework of a quasi-real experiment are presented. The accuracy of the identification problem solution is estimated as a function of the number of layers in the heterostructure and the «measurements» error.The obtained results are planned to be used in the new technique of multiscale modeling of thermal regimes of the electronic component base of the microwave range, when identifying the coefficients of thermal conductivity of heterostructure.

Numerical Simulation of the Resistance and Self-Propulsion Model Tests

2018 ◽  
Author(s):  
Adrian Lungu
Keyword(s):  
Complex Structure ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Local Flow ◽  
Complex Investigation ◽  
Grid Convergence ◽  
Flow Features ◽  
Sinkage And Trim ◽  
Thrust And Torque ◽  
Resistance Coefficients

The paper proposes a series of numerical investigations performed to test and demonstrate the capabilities of a RANS solver in the area of complex ship flow simulations. Focus is on a complete numerical model for hull, propeller and rudder that can account for the mutual interaction between these components. The paper presents the results of a complex investigation of the flow computations around the hull model of the 3600 TEU MOERI containership (KCS hereafter). The resistance for the hull equipped with rudder, the POW computations as well as the self-propulsion simulation are presented. Comparisons with the experimental data provided at the Tokyo 2015 Workshop on CFD in Ship Hydrodynamics are given to validate the numerical approach in terms of the total and wave resistance coefficients, sinkage and trim, thrust and torque coefficients, propeller efficiency and local flow features. Verification and validation based on the grid convergence tests are performed for each computational case. Discussions on the efficiency of the turbulence models used in the computations as well as on the main flow features are provided aimed at clarifying the complex structure of the flow around the stern.

An Experimental Study of the Viscous Resistance of a 0,564-CB Form

1979 ◽  
Vol 23 (02) ◽  
pp. 140-156
Author(s):  
P. N. Joubert ◽  
P. H. Hoffmann
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Skin Friction ◽  
Resistance Coefficient ◽  
Viscous Resistance ◽  
Local Skin ◽  
Friction Resistance ◽  
Local Skin Friction ◽  
The University ◽  
Resistance Coefficients

Wind tunnel tests were performed to determine the viscous resistance and its components for a 0.564-CB model from the BSRA Trawler Series. It was found that the sum of the pressure and skin friction resistance coefficients agreed well with the viscous resistance coefficient determined from drag balance tests. The range of Reynolds number examined was from 1.15 × 106 to 5.17 × 106. The results for the viscous resistance and its components were fitted using least-squares methods to various equations. The results were also compared with the results of previous tests done at the University of Melbourne on models of Lucy Ash-. ton and a 0.80-CB tanker. It was found that the skin friction and viscous resistance coefficients had curves of quite different position and slope. Local skin friction distribution showed noteworthy differences, especially at the stern, with high values at the keel and low values approaching the waterline.

Temperature dependence of the resistance, impedance and capacitance of semitransparent PTB7-Th and PCBM sensor

2019 ◽  
Vol 33 (12) ◽  
pp. 1950110
Author(s):  
Muhammad Riaz ◽  
Khasan S. Karimov ◽  
Jameel-Un Nabi
Keyword(s):  
Light Intensity ◽  
Temperature Dependence ◽  
Temperature Sensor ◽  
Visual Control ◽  
Capacitance Measurement ◽  
Experimental Conditions ◽  
Temperature Resistance ◽  
Graphene Composite ◽  
Temperature Dependences ◽  
Resistance Coefficients

The temperature dependences of resistance, impedance and capacitance of semitransparent sensor having structure ITO/PTB7-Th:PC[Formula: see text]BM/Graphene composite (semisurface type) were investigated. The transparency of the sensor was 58–60%. The dependences of the resistance, impedance and capacitance at different frequencies 100 Hz, 1 kHz, 10 kHz, 100 kHz and 200 kHz and temperature in the range of 23.8–80[Formula: see text]C for the sensor were studied. It was observed that as the temperature increased from 23.8[Formula: see text]C to 80[Formula: see text]C, the resistance and impedance (at 1 kHz) of the samples decreased, on average, by a factor of 3.51 and 3.79, respectively. At same experimental conditions (1 kHz), the capacitances of the samples also decreased by a factor of 9.6. It was also noted that as frequency increased from 100 Hz to 200 kHz, the impedance of the sensor decreased by a factor of 21 and 12, at temperatures 24[Formula: see text]C and 58[Formula: see text]C, respectively. Under the same conditions, the capacitance decreased by a factor of 30 and 28, respectively. The temperature resistance coefficients were measured to be −1.31%/[Formula: see text]C, −1.30%/[Formula: see text]C, −1.27%/[Formula: see text]C, −0.84%/[Formula: see text]C, −0.72%/[Formula: see text]C and −0.33%/[Formula: see text]C for R, Z (100 Hz), Z (1 kHz), Z (10 kHz), Z (100 kHz) and Z (200 kHz), respectively. For capacitance measurement, the temperature capacitance coefficients were measured as −1.39%/[Formula: see text]C, −1.38%/[Formula: see text]C, −1.37%/[Formula: see text]C, −1.36%/[Formula: see text]C and −1.34%/[Formula: see text]C, respectively. The semitransparent PTB7-Th- and PC[Formula: see text]BM-based temperature sensor can be used for measurement of the temperature as a teaching aid in situations where visual control of illumination and light intensity is required.

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