Study on the Resistance Characteristics of Heat Metering System Based on Electric Valve

2014 ◽  
Vol 492 ◽  
pp. 507-510
Author(s):  
Dong Jun Gong ◽  
Yao Zhang ◽  
Xing Ru Li ◽  
Li De Fang ◽  
Zi Hui Wei ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Theoretical Calculations ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Experiment System ◽  
Average Value ◽  
Parallel Pipeline ◽  
Heat Metering ◽  
The Relationship ◽  
Resistance Coefficients

Through theoretical calculations and derivation, the paper obtained the relationship between resistance coefficient and pressure difference, as well as flow rate. For the series pipeline, the flow in the series pipeline is the same, as a result, all the resistance in the series pipeline is the total resistance. For the parallel pipeline, the pressure difference is same, and the all the flow in parallel pipeline is the total flow. According to the real example, the paper identified the inlet pressure difference of the indoor system, the most unfavorable ring and the ratio frictional resistance. Based on the room heat load calculation, the paper determined the most unfavorable loop diameter of each pipe section. By calculating the resistance coefficients of the electric valve at opening, the resistance coefficients of the electric valve at closing were obtained. In the experiment system, the resistance coefficient average value when the electric valve is off was 101831.65, which is basically in line with the calculable value 10719.6, indicating that the existing parameters are much more reasonable.

The Relationship Between Frictional Resistance and Roughness for Surfaces Smoothed by Sanding

2002 ◽  
Vol 124 (2) ◽  
pp. 492-499 ◽  
Author(s):  
Michael P. Schultz
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Polished Surface ◽  
Average Height ◽  
Freestream Velocity ◽  
Number Range ◽  
Test Fixture ◽  
Plate Length ◽  
The Relationship

An experimental investigation has been carried out to document and relate the frictional resistance and roughness texture of painted surfaces smoothed by sanding. Hydrodynamic tests were carried out in a towing tank using a flat plate test fixture towed at a Reynolds number ReL range of 2.8×106−5.5×106 based on the plate length and freestream velocity. Results indicate an increase in frictional resistance coefficient CF of up to 7.3% for an unsanded, as-sprayed paint surface compared to a sanded, polished surface. Significant increases in CF were also noted on surfaces sanded with sandpaper as fine as 600-grit as compared to the polished surface. The results show that, for the present surfaces, the centerline average height Ra is sufficient to explain a large majority of the variance in the roughness function ΔU+ in this Reynolds number range.

scholarly journals Comparative modeling of hull form resistance for three ocean going vessels using methodical series

2015 ◽  
Vol 4 (4) ◽  
pp. 489 ◽  
Author(s):  
Nitonye Samson ◽  
Adumene Sidum
Keyword(s):  
Reynolds Number ◽  
Frictional Resistance ◽  
Comparative Modeling ◽  
Resistance Coefficient ◽  
Container Ship ◽  
Test Technique ◽  
Hull Form ◽  
Reynolds Number Increase ◽  
Friction Line ◽  
Resistance Coefficients

This paper presents a comparative estimation of the hull form resistance for Cargo ship, Ocean-going Tug and Container ship. The research study evaluates the influences of various ship hull parameters in relations to the vessel speeds and level of turbulence (Reynolds number). The modeling was done using MATLAB software and the model test technique based on the ITTC, ATTC, Granville and Hughes friction line application. The result shows that the hull form resistances follow the same trend in the ITTC, ATTC and Granville models, while the Hughes model gave a different trend with other techniques. It further revealed that as the speed increases by 10knots, the frictional resistance coefficients decrease by 11.86% for the ITTC & Granville models, and 12.03% for the Hughes model. For Ocean-going Tug and Container Ship, the frictional resistance coefficient decrease by 12.31% for the ITTC & Granville models, and 12.14% for the Hughes model. The Reynolds number increase by 62.52% for every 10knots increase in the speed of the Cargo ship and 62.23% for every 10knots increase in the speed of the Ocean going tug and Containership. At various experimental speeds, the results showed that for every 1 knots increase in the speed of the Containership, the effective power developed increases by 9.45%. This provides a technical and analytical guide on hull form resistance trend for engineers and ship operators.

Rolling resistance, vertical load and optimal number of wheels in human-powered vehicle design

2016 ◽  
Vol 231 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Paolo Baldissera ◽  
Cristiana Delprete
Keyword(s):  
Aerodynamic Drag ◽  
Rolling Resistance ◽  
Resistance Coefficient ◽  
Optimal Number ◽  
Vehicle Design ◽  
Definition Of ◽  
Human Powered ◽  
The Relationship ◽  
Resistance Coefficients ◽  
Strict Definition

Even if it makes a smaller contribution than aerodynamic drag, rolling resistance plays a non-negligible role in the efficiency of human-powered vehicles, whether they are designed for daily commuting or to set speed records. The literature, experimental evidence and models show that the rolling resistance coefficient of cycling wheels strongly depends on the supported load, suggesting that the number of wheels and the load distribution could play a role in vehicle design and in road-test data analysis. Starting with an in-depth look at the relationship between a single wheel and overall vehicle rolling resistance coefficients, an analysis is proposed and discussed with the aim of minimizing the rolling resistance of a vehicle. Finally, a parametric surface response model for rolling resistance is obtained as a function of wheel size and the number of wheels. The overall analysis overturns the popular assumption according to which ‘the more wheels, the more rolling resistance’, at least according to a strict definition of the phenomenon.

scholarly journals Numerical Calculation of the Tee Local Resistance Coefficient

2015 ◽  
Vol 9 (1) ◽  
pp. 876-881 ◽  
Author(s):  
Qin Zhang ◽  
Manlai Zhang ◽  
Zhihong Zhou ◽  
Shizhong Wei
Keyword(s):  
Cfd Simulation ◽  
Flux Ratio ◽  
Frictional Resistance ◽  
Resistance Coefficient ◽  
Head Loss ◽  
Local Resistance ◽  
Local Resistance Coefficient ◽  
Tee Junction ◽  
Resistance Coefficients

The local head loss of tee could be calculated with the determination of local resistance coefficient by CFD simulation and test. Based on the mesh-independent feature identified, the flow field inner tee was numerically simulated by the standard k - ε turbulent model and SIMPLEC algorithms, which has revealed the mainstream was obliged to turn to the opposite side of tee junction, and a rise in pressure drop between upstream and downstream was caused as a result. Furthermore, the frictional resistance coefficient was calculated for eliminating the frictional head loss of model, which decreased from 0.0207 to 0.0133 when the inlet velocity increased from 1 m/s to 12 m/s. Additionally, the local resistance coefficients of tee at flow conditions were attained, and the quadratic polynomial between the local resistance coefficient and flux ratio was presented due to the influence of branch on mainstream. Through the test, the simulation result has been compared and the effectiveness of simulation has been verified.

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).

scholarly journals Determination of vertical dimension of occlusion by using the phonetic vowel "O" and "E"

2015 ◽  
Vol 72 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Marko Igic ◽  
Nebojsa Krunic ◽  
Ljiljana Aleksov ◽  
Milena Kostic ◽  
Aleksandra Igic ◽  
...  
Keyword(s):  
Cognitive Functions ◽  
Complete Denture ◽  
Reference Points ◽  
Vertical Dimension ◽  
Entire Sample ◽  
Average Value ◽  
Significant Difference ◽  
The Relationship

Background/Aim. The vertical dimension of occlusion is a very important parameter for proper reconstruction of the relationship between the jaws. The literature describes many methods for its finding, from the simple, easily applicable clinically, to quite complicated, with the use of one or more devices for determination. The aim of this study was to examine the possibility of determining the vertical dimension of occlusion using the vocals ?O? and ?E? with the control of values o btained by applying cognitive functions. Methods. This investigation was performed with the two groups of patients. The first group consisted of 50 females and 50 males, aged 18 to 30 years. In this group the distance between the reference points (on top of the nose and chin) was measured in the position of the mandible in the vertical dimension of occlusion, the vertical dimension at rest and the pronunciation of the words ?OLO? and ?ELE?. Checking the correctness of the particular value for the word ?OLO? was also performed by the phonetic method with the application of cognitive exercises when the patients counted from 89 to 80. The obtained difference in the average values i n determining the vertical dimension of occlusion and the ?OLO? and ?ELE? in the first group was used as the reference for determining the vertical dimension of occlusion in the second group of patients. The second group comprised of 31 edentulous persons (14 females and 17 males), aged from 54 to 85 years who had been made a complete denture. Results. The average value obtained for the vertical dimension of rest for the entire sample was 2.16 mm, for the word ?OLO? for the entire sample was 5.51 mm and for the word ?ELE? for the entire sample was 7.47 mm. There was no statistically significant difference between the genders for the value of the vertical dimension at rest, ?ELE? and ?OLO?. There was a statistically significant difference between the values f or the vertical dimension at rest, ?OLO? and ?ELE? for both genders. There was a statistically significant correlation between the value for the vertical dimension at rest, ?OLO? and ?ELE?, for both groups of subjects. Conclusion. Determining the vertical dimension of occlusion requires 5.5 mm subtraction from the position of the mandible in pronunciation of the word ?OLO? or 7.5 mm in pronunciation of the word ?ELE?.

scholarly journals On Newcomb's method of investigating periodicities and its application to Brückner's weather cycle

1914 ◽  
Vol 90 (619) ◽  
pp. 349-355
Keyword(s):  
Thermal Radiation ◽  
The Other ◽  
New Method ◽  
Critical Examination ◽  
Numerical Work ◽  
Average Value ◽  
Other Hand ◽  
Relationship Of ◽  
The Relationship ◽  
Great Simplicity

During the last few years of his life Prof. Simon Newcomb was keenly interested in the problem of periodicities, and devised a new method for their investigation. This method is explained, and to some extent applied, in a paper entitled "A Search for Fluctuations in the Sun's Thermal Radiation through their Influence on Terrestrial Temperature." The importance of the question justifies a critical examination of the relationship of the older methods to that of Newcomb, and though I do not agree with his contention that his process gives us more than can be obtained from Fourier's analysis, it has the advantage of great simplicity in its numerical work, and should prove useful in a certain, though I am afraid, very limited field. Let f ( t ) represent a function of a variable which we may take to be the time, and let the average value of the function be zero. Newcomb examines the sum of the series f ( t 1 ) f ( t 1 + τ) + f ( t 2 ) f ( t 2 + τ) + f ( t 3 ) f ( t 3 + τ) + ..., where t 1 , t 2 , etc., are definite values of the variable which are taken to lie at equal distances from each other. If the function be periodic so as to repeat itself after an interval τ, the products are all squares and each term is positive. If, on the other hand, the periodic time be 2τ, each product will be negative and the sum itself therefore negative. It is easy to see that if τ be varied continuously the sum of the series passes through maxima and minima, and the maxima will indicated the periodic time, or any of its multiples.

Discussion on Household Heat Metering and Central Control of Heating System

2012 ◽  
Vol 512-515 ◽  
pp. 2863-2866
Author(s):  
Hong Bing Chen ◽  
Ping Wei
Keyword(s):  
Heat Supply ◽  
Energy Savings ◽  
Heating System ◽  
Total Heat ◽  
Central Control ◽  
Heat Metering ◽  
Basic Ideas ◽  
Relationship Of ◽  
The Relationship

Aiming at the current unreasonable heat charge policy, this paper describes the necessity of consumption-based heat bill system, introduces the basic ideas and problems of household heat metering and central control on total heat supply, and analyzes the relationship of household heat metering and central control. The study shows these two aspects should be well coordinated wit[h each other for better energy savings.

Depression impact on the sexual desire

2011 ◽  
Vol 26 (S2) ◽  
pp. 1549-1549
Author(s):  
M. Lourenço ◽  
L.P. Azevedo ◽  
J.L. Gouveia
Keyword(s):  
Sexual Desire ◽  
Depressive Symptomatology ◽  
Psychiatric Patients ◽  
Severe Depression ◽  
List Type ◽  
Sexual Performance ◽  
Average Value ◽  
Treatment Of Depression ◽  
The One ◽  
The Relationship

IntroductionDepression as a pathology and the side effects of pharmacology therapy have been pointed proven to be as responsible for the lack of sexual desire. Among the drugs used in the treatment of depression, anti-depressives are the ones mostly connected to sexual dysfunction.Aims /objectivesTo study the relationship between depression and its impact on the sexual desire in psychiatric patients.MethodsThe chosen sample is composed of 89 subjects, 73 females and 16 males, with ages ranging from 21 to 70 years, who present with depressive symptomatology (mild to moderate symptomatology (MMS) and severe symptomatology (SS).To each patient 3 instruments were applied: 1)Questionnaire used to collect demographic and clinical data from the sample;2)Instrument of estimation of the depression degree (BDI - Beck Depression Inventory);3)Instrument of valuation of the sexual desire (SDS - Sexual Desire Scale).ResultsDepression average value obtained with BDI was 25.58 (SD = 11.86). The majority was satisfied with their marital relationship (72.7% and 52.9%, respectively), and the group with most sexual damaged (actual sexual performance regarding sexual desire) being the one with severe depression (54.5% versus 82.4%, respectively). Regarding total SDS value, the group with MMD present with higher levels of sexual desire (M = 54.93; DP = 14.56) than the group with SD (M = 41.82; DP = 11.86).ConclusionsThis study presents an exploratory character and the obtained results revealed that depressive symptomatology severity is directly related with sexual desire, by saying the higher the depression's severity is the lower sexual desire will be.

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