Valve Stroking to Control Water Hammer Transients Using Dynamic Programming

1987 ◽  
Vol 109 (1) ◽  
pp. 94-100 ◽  
Author(s):  
D. N. Contractor
Keyword(s):  
Dynamic Programming ◽  
Pressure Rise ◽  
The Other ◽  
Valve Closure ◽  
Time Period ◽  
Fluid Transients ◽  
Valve Opening ◽  
Closure Policy ◽  
Valve Operation ◽  
Control Water

Fluid transients in a pipeline caused by valve operation can be minimized by operating the valve in an optimally prescribed manner, in a given time of closure (tc > 2L/a). Dynamic programming is used to select the operation of the valve (i.e., set the valve-operating policy) over the time period tc so that the pressure rise at the valve (the objective function) is minimized. Constraints on the valve closure policy may also be specified, e.g., monotonic valve closure. Application of this method to a simple pipeline with a reservoir at one end and a valve at the other end shows that the pressure rise at the valve is lower than when the valve is closed linearly with time. The benefits of dynamic programming are shown to be greatest when the time of closure tc is small. The method has also been applied to valve opening, so that the pressure drop at the valve is a minimum.

The incumbent, challenger, and population during revolution and civil war

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Kjell Hausken ◽  
Mthuli Ncube
Keyword(s):  
Civil War ◽  
Public Goods ◽  
Arab Spring ◽  
The Other ◽  
Time Period ◽  
Geographic Regions

We consider revolutions and civil war involving an incumbent, a challenger, and the population. Revolutions are classified into eight outcomes. In four outcomes incumbent repression occurs (viewed as providing sub-threshold benefits such as public goods to the population). Accommodation occurs in the other four outcomes (benefits provision above a threshold). The incumbent and challenger fight each other. The incumbent may win and retain power or else lose, thereby causing standoff or coalition. In a standoff, which is costly, no one backs down and uncertainty exists about who is in power. In a coalition, which is less costly, the incumbent and challenger cooperate, compromise, and negotiate their differences. If the population successfully revolts against the incumbent, the challenger replaces the incumbent. Eighty-seven revolutions during 1961–2011, including the recent Arab spring revolutions, are classified into the eight outcomes. When repressive, the incumbent loses 46 revolutions, remains in power through 21 revolutions, and builds a coalition after 12 revolutions. When accommodative, the incumbent loses seven revolutions and builds a coalition after one revolution. The 87 revolutions are classified across geographic regions and by time-period.

Charts for water hammer in pipelines resulting from valve closure from full opening only

1985 ◽  
Vol 12 (2) ◽  
pp. 241-264 ◽  
Author(s):  
Bryan W. Karney ◽  
Eugen Ruus
Keyword(s):  
Good Accuracy ◽  
Pipe Wall ◽  
Pressure Head ◽  
Wall Friction ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Closure Time ◽  
Basic Parameters ◽  
Valve Opening ◽  
Open Position

Maximum pressure head rises, which result from total closure of the valve from an initially fully open position, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Uniform, equal-percentage, optimum, and parabolic closure arrangements are analysed. Basic parameters such as pipeline constant, relative closure time, and pipe wall friction are considered with closures from full valve opening only. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe with good accuracy for the closure arrangements considered. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the parabolic closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Uniform closure produces pressure head rise that usually lies between those produced by the parabolic and the equal-percentage closure arrangements, except for the range of low pressure head rise combined with low or zero friction, where the rise due to uniform closure approaches that produced by optimum closure.

Aerodynamics of Contra-Rotating Fans With Swept Blades

2015 ◽  
Author(s):  
K. Vijayraj ◽  
M. Govardhan
Keyword(s):  
Rotational Speed ◽  
Axial Flow ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
The Other ◽  
Flow Structures ◽  
Current Investigation ◽  
Rotating System ◽  
Stall Margin ◽  
Static Head

A Counter-Rotating System (CRS) is composed of a front rotor and a rear rotor which rotates in the opposite direction. Compared with traditional rotor-stator system, the rear rotor is used not only to recover the static head but also to supply energy to the fluid. Therefore, to achieve the same performance, the use of a CRS may lead to a reduction of the rotational speed and may generate better homogeneous flow downstream of the stage. On the other hand, the mixing area in between the two rotors induces complicated interacting flow structures. Blade sweep has attracted the turbomachinery blade designers owing to a variety of performance benefits it offers. However, the effect of blade sweep on the performance, stall margin improvements whether it is advantageous/disadvantageous to sweep one or both rotors has not been studied till now. In the current investigation blade sweep on the performance characteristics of contra rotating axial flow fans are studied. Two sweep schemes (axial sweeping and tip chord line sweeping) are studied for two sweep angles (20° and 30°). Effect of blade sweep on front rotor and rear rotor are dealt separately by sweeping one at a time. Both rotors are swept together and effect of such sweep scheme on the aerodynamic performance of the stage is also reported here. The performance of contra rotating fan is significantly affected by all these parameters. Blade sweep improved the pressure rise and stall margin of front rotors. Axially swept rotors are found to have higher pressure rise with reduced incidence losses near the tip for front rotors. Sweeping the rear rotor is not effective since the pressure rise is less than that of unswept rotor and also has less stall margin.

Torque Characteristics of a 122-Centimeter Butterfly Valve With a Hydro/Pneumatic Actuator

1981 ◽  
Vol 103 (3) ◽  
pp. 396-404 ◽  
Author(s):  
F. N. Lin ◽  
W. I. Moore ◽  
F. E. Lundy
Keyword(s):  
Hydraulic Resistance ◽  
Flow Resistance ◽  
Field Testing ◽  
Hydraulic Cylinder ◽  
The Other ◽  
Pneumatic Actuator ◽  
Butterfly Valve ◽  
Hydraulic Flow ◽  
Resistance Torque ◽  
Valve Opening

Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.

scholarly journals Using tropicamide and phenylephrine without cyclopentolate for pupil dilation in cataract surgery reduces postoperative intraocular pressure rise

2020 ◽  
Vol 17 (3) ◽  
pp. 285-289
Author(s):  
Rachel Xuan ◽  
Keith Ong
Keyword(s):  
Intraocular Pressure ◽  
Retrospective Study ◽  
Cataract Surgery ◽  
Medical Records ◽  
Pressure Rise ◽  
Pupil Dilation ◽  
The Other ◽  
Sample Population ◽  
Iop Elevation ◽  
Larger Sample

The aim of this retrospective study was to evaluate whether intraocular (IOP) elevation post-cataract surgery can be reduced by using tropicamide and phenylephrine only, without cyclopentolate. Medical records across two surgical facilities were analyzed. One surgical facility (Cohort A) used a combination of tropicamide, cyclopentolate, and phenylephrine preoperatively, while the other (Cohort B) used tropicamide and phenylephrine only. Of patients in Cohort A, 63.6% (n = 7) had a higher IOP in the operated eye, while it was only 27.3% (n = 3) in Cohort B. Therefore, it is preferable to exclude the use of cyclopentolate in the preoperative dilation regimen of patients undergoing cataract surgery. However, a study with a larger sample population is required to further evaluate the significance of these results.

scholarly journals Contribution to the research of the chemical intensity erosion in the western Serbia

2003 ◽  
Vol 83 (1) ◽  
pp. 7-14 ◽  
Author(s):  
Slavoljub Dragicevic ◽  
Predrag Manojlovic ◽  
Sanja Mustafic
Keyword(s):  
Analytical Method ◽  
River Basins ◽  
Meteorological Conditions ◽  
The Other ◽  
Entry And Exit ◽  
Chemical Erosion ◽  
Time Period ◽  
Erosion Intensity

Based on the research of the chemical erosion intensity in the upper course of Tamnava, the appearance of its negative value has been found. Further researches, that enclose the lower course, confirmed this fact. This research opened the important question about the causes of this phenomena. Analytical method eliminated all expected causes and led to conclusion that the reason for this should be found by using the more precise research of the mineralisation of the precipitations. It was necessary to continue the measurings of the precipitation mineralisation in the greater number of locations and in the wider time period, as well as in the different meteorological conditions, and after that to establish the subordination between the amount of precipitations and the entered TDS. Only after these additive researches we could be able to find out the relation between ''entry'' and ''exit'' and to find out the intensity of the chemical erosion in this, and in the other river basins. For now, we are able only to find out the carrying of TDS, as well as the reduction of the chemical evacuation for the non - carbonated part of the basin (corrected value).

scholarly journals Divorced and Unemployed: the Declining Association between Two Critical Lifecourse States in the UK, 1984-2017

2019 ◽  
Author(s):  
Lewis Robert Anderson ◽  
Christiaan Willem Simon Monden ◽  
Erzsebet Bukodi
Keyword(s):  
Gender Gap ◽  
Educational Inequality ◽  
Marital Dissolution ◽  
The Other ◽  
Cross Sectional ◽  
Time Period ◽  
Domains Of Life ◽  
Nationally Representative ◽  
And Gender ◽  
The Uk

Individuals exposed to both job loss and marital dissolution are likely to be highly disadvantaged, having experienced stresses and losses in the two primary domains of life. Moreover, recent literature finds that exposure to one event tends to increase risk of the other. However, next to nothing is known about the size or composition – or changes therein – of the divorced/separated and unemployed (DSU) subpopulation. Using large, nationally representative, repeated cross-sectional datasets extending back to 1984, we aim to fill this gap for the UK. We give a descriptive account of the prevalence and social distribution of DSU, and of the cross-sectional association between its two component states: among which groups, by education and gender, does being either divorced/separated or unemployed most strongly imply a heightened risk of also being the other, and how has this changed over time? We find stable and strong educational inequality in DSU, while the gender gap has narrowed and recently closed. The association between the two states is stronger among men; has weakened strikingly over the time period we consider, for both men and, especially, women; and is educationally stratified among men but not women. Contrary to expectations, higher-educated men in one of the two states are most likely to also be in the other. Possible explanations and further questions are discussed. In particular, we highlight the possibility that over this time period the divorced/separated have become more like the general population, rather than a negatively selected subgroup among whom unemployment is a particular risk.

scholarly journals GEOTECHNICAL CHARACTERISTICS OF EMBANKMENT ALONG THE RAILWAY ROUTE OF ENTITY BORDER OF FEDERATION OF BIH – MAGLAJ, SECTION km 103+500 MAGLAJ

2017 ◽  
Vol 1 (16) ◽  
Author(s):  
Neđo Đurić
Keyword(s):  
European Union ◽  
Laboratory Tests ◽  
Soil Depth ◽  
The Other ◽  
Geotechnical Characteristics ◽  
Time Period ◽  
European Union Countries ◽  
Improvement Measures ◽  
Train Speed

Railway route from entity border to Maglaj is on corridor V of railways that connects Adriatic seawith European Union countries. More precisely, it is on the railway Samac – Sarajevo that was builtduring the fifties. From Doboj to Zenica exist two tracks, one built in 1947. and the other thirty yearslater. In time, the railway worn out, since it was not maintained properly during its exploitation, soallowed train speed is 40 km/h. Reconstruction of railway had previously started on sections with aimto achieve the level of train speed to 120 km/h.Terrain research in order to overview quality of material on which the railway is laid, and immediateenvironment that has effect on railway route, were conducted by sections, from which section km103+500 – Maglaj is one of the most important considering characteristics of the terrain on which theroute passes. Research along railway route were conducted by using research trial pits from both sidesand in between tracks, to depth of entry in basic soil. Depth of research works is different for old andnew track, considering the way of construction in time period of 30 years. Beyond narrow corridor ofrailway route research of characteristics of the terrain were not conducted, because of inability toaccess due to mining. Results of terrain and laboratory tests showed geotechnical characteristics ofmaterial, based on which were given quality improvement measures for deposited materials, and basefor reconstruction of railway.

scholarly journals APPLICATION OF BENZYLADENINE (BA) IN THE FORM OF LANOLIN PASTE ON FLOWER-STALK BUDS SUCCESSFULLY INDUCED RE-BLOOMING OF HYBRID Phalaenopsis

2020 ◽  
Vol 8 (2) ◽  
pp. 383
Author(s):  
Mukhaila Iryani ◽  
Yusnita Yusnita ◽  
Dwi Hapsoro ◽  
Kukuh Setiawan ◽  
Agus Karyanto
Keyword(s):  
Plant Growth ◽  
The Other ◽  
Control Treatment ◽  
Bud Break ◽  
Flower Stalk ◽  
Moth Orchid ◽  
Randomized Design ◽  
Time Period ◽  
Long Time ◽  
Completely Randomized Design

Hybrid moth orchid (genus Phalaenopsis) is one of the most popular ornamentals in Indonesia. It has beautiful and long-lasting flowers, but cultivating this orchid is still become a challenging issues due to the need of specific condition to grow and long time period to re-blooming. Plant growth regulators (PGR) (i.e. Benzyladenine (BA)) has been widely documented as a flower-inducing substance in several orchids. However, the optimal concentration and its mechanism in inducing flower-stalk bud and re-blooming is still unclear. This research aimed to study the effects of BA application in the form of lanolin paste on hybrid Phalaenopsis flower-stalk buds. We conducted this study using completely randomized design with four replications at the greenhouse laboratory Faculty of Agriculture University of Lampung on August to December 2018. We divided the orchid into 5 group of BA concentration (0, 1000, 1500, 3000, or 6000 ppm). The sheath of the fourth or fifth buds of the flowers were carefully opened, then it smeared with BA. The percentage of bud break into flower spike or keiki, length of shoots or spike and number of open flowers were recorded until 10 weeks of observation. The results showed that, neither of the buds under the control treatment (without BA), 1000 ppm nor 1500 ppm BA broke and grew into keiki or spike. On the other hand, application of BA at 3000 ppm or 6000 ppm successfully induced 100% flower spikes on the buds treated. No keiki was formed in all buds treated. In addition, treatment of the buds with 6000 ppm BA produced longer flower spikes as well as more open flowers. We conclude that the application of BA (minimal 3000 ppm) successfully induced flower spike of  hybrid Phalaenopsis.

Steeped in Modernism: The Teapot as Manifesto in Early 20th Century Art

2016 ◽  
Author(s):  
Maya Bielinski
Keyword(s):  
Twentieth Century ◽  
20Th Century ◽  
Political History ◽  
Modern Art ◽  
The Other ◽  
Early 20Th Century ◽  
Avant Garde ◽  
Small Window ◽  
Time Period ◽  
20Th Century Art

The art manifesto, a written political, social, and artistic proclamation of an artistic movement, surged in popularity among avant‐garde art groups in the first half of the twentieth century. Many of the manifestos featured declarations for the synthesis of art and life as well as a call for social and political power for artists of both 'high' and 'low' art forms. Concurrently, new artistic interpretations of the humble teapot became suddenly ubiquitous. This inquiry explores how the teapot emerged as a dominant symbol for the goals of Modern Art movements, and includes an analysis of the teapot's socio‐political history, its ambiguous status between high and low art, and its role in the commercial sphere. By examining the teapots of Suprematism's Kazimir Malevich, Constructivism's Mariane Brandt,and Surrealism's Meret Oppenheim, this presentation will track ideas of functionality, the teapot as symbol, and aesthetics from 1923 to 1936. This small window in time offers an analysis of the extraordinary developments in teapots, and perhaps a glimpse of the paralleled momentum that occurred more generally in design, architecture, and the other arts in this time period.

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