excess pressure
Recently Published Documents


TOTAL DOCUMENTS

183
(FIVE YEARS 59)

H-INDEX

20
(FIVE YEARS 2)

Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 21
Author(s):  
Mohamad Zeidan ◽  
Avi Ostfeld

This study presents the potential of integrating Hydrams in modern water distribution systems (WDSs) for managing excess pressure and reducing energy costs. Hydrams, which are also termed Hydraulic ram pumps in the literature, is a cyclic water pump powered by hydropower, generally used to pump drinking and irrigation water in mountainous and rural areas having short of power. The Hydrams is introduced as a sustainable low-cost alternative solution to the more conventional pressure reducing valves (PRVs) approach for managing pressure zones in WDSs. Unlike PRVs, where the pressure is lost and not put into good use, Hydrams mitigate excess pressure at high-pressure zones and direct it to much-needed low-pressure zones. In addition, Hydrams are cheap, simple, environmentally friendly, and require little maintenance. The proposed approach integrates a Hydram in parallel to the original centrifugal pump, where they can be operated interchangeably according to the system’s hydraulic needs. Nevertheless, it is vital to correctly size the Hydram at the feed line and accompany it with a proper storage tank at the low-pressure zone. The storage tank serves as a buffer between the intermittent water supply and consumer demand pattern. Moreover, the tank introduces flexibility into the system that allows more sustainable operating schedules. Two case study applications of increasing complexity are presented to demonstrate the potential of this Hybrid system, later referred to as Hybrid Pumping Unit (HPU). The Hydram and tank sizing is done by a simple heuristic approach, while the operation of the system is dictated by a genetic algorithm. The results demonstrate the potential of integrated Hydrams in reducing excess pressures and energy costs.


Volcanica ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 189-201
Author(s):  
Richard Walker ◽  
Tara Stephens ◽  
Catherine Greenfield ◽  
Simon Gill ◽  
David Healy ◽  
...  

Inferences about sheet intrusion emplacement mechanisms have been built largely on field observations of intrusion tip zones: magmatic systems that did not grow beyond their observed state. Here we use finite element simulation of elliptical to superelliptical crack tips, representing observed natural sill segments, to show the effect of sill tip shape in controlling local stress concentrations, and the potential propagation pathways. Stress concentration magnitude and distribution is strongly affected by the position and magnitude of maximum tip curvature κmax. Elliptical tips concentrate stress in-plane with the sill, promoting coplanar growth. Superelliptical tips concentrate maximum tensile stress (σmax) and shear stress out-of-plane of the sill, which may promote non-coplanar growth, vertical thickening, or coplanar viscous indentation. We find that σmax =  Pe(1+ 2(√[aκmax]), where Pe is magma excess pressure and a is sill half length. At short length-scales, blunted tips locally generate large tensile stresses; at longer length-scales, elliptical-tipped sills become more efficient at concentrating stress than blunt sills.


2021 ◽  
Author(s):  
Maxim Viktorovich Miklyaev ◽  
Ivan Vyacheslavovich Denisov ◽  
Ivan Mikhailovich Gavrilin

Abstract Well construction in the Volga-Ural Region faces different sorts of complications, the most common ones being the loss of drilling fluids and rockslides. Such complications may cause considerable financial losses due to non-productive time (NPT) and longer well construction periods. Moreover, there are complications, which might occur both during well construction and during its exploitation. The commonest complications are sustained casing pressure (SCP) and annular flow. The complications, which occur when operating a well, also have a negative effect on the economic efficiency of well operation and call for additional actions, for example, repair and insulation works, which require well shutdown and killing, though a desired outcome still cannot be guaranteed; moreover, it is possible that several different operations may have to be carried out. In addition, the occurrence of SCP during well life is one of the most crucial problems that may cause well abandonment due to high risks posed by its operation. It is known that the main reasons for SCP are as follows: Channels in cement stone Casing leaks Leaks in wellhead connections To resolve the problem of cement stone channeling, several measures were taken, such as revising cement slurry designs, cutting time for setting strings on slips, applying two-stage cementing, etc. These measures were not successful, besides, they caused additional expenses for extra equipment (for example, a cementer). In order to reduce the risk of cement stone channeling, a cementing method is required that will allow to apply excess pressure on cement slurry during the period of transition and early strength development. To achieve this goal, a well-known method of controlled pressure cementing may be applied. Its main drawback, however, is that it requires much extra equipment, thus increasing operation expenses. In addition, the abovementioned method allows affecting the cement stone only during the operation process and / or during the waiting on cement (WOC) time. Upon receiving the results of the implemented measures and considering the existing technologies and evaluating the economic efficiency, the need was flagged for developing a combined cementing method. The goal of this method is to modify the production string cementing method with a view to applying excess pressure on cement stone during strength development and throughout the well lifecycle. The introduction of this lining method does not lead to an increase in well construction costs and considerably reduces the risks of losing a well from the production well stock.


Author(s):  
L.P. Vogman ◽  

The statistics of fires and explosions of ammonia in the sphere of its circulation (production, storage, use) indicate the relevance of studies aimed at preventing emergency situations, localization, and elimination of accidents consequences. Equally important are studies on the development of assessments of accidents consequences associated with the release and spillage of ammonia from the equipment in various aggregate state. When ammonia is released, the resulting mixture of the product with air can vary in density from the formation of gas-air clouds with a density below the air density to buoyancy and excess air density, depending on the release conditions (pressure and temperature in the equipment; the sizes of the hole through which ammonia enters the surrounding space; the location of the hole in the equipment (gas or liquid phase). When the liquid ammonia leaks out, the spills are formed, from the surface of which the product evaporates especially rapidly in the first moments after the spill. Based on the computational and analytical studies, the design schemes and formulas were proposed for determining the parameters of the explosion: excess pressure and impulse of the undisturbed (incident) and reflected from the obstacles of the blast wave, as well as the nature of the destruction depending on the distance from the epicenter of the explosion, caused by the depressurization of equipment with ammonia. An accident scenario is considered, according to which the ammonia with a mass of 100 kg, when depressurizing, breaks out from the equipment of an industrial refrigerator. Ammonia vapors mix with the air to form a cloud that ignites and explodes. As an example, the overpressure and impulse during explosion of ammonia at a distance of 30 m from the epicenter of the explosion were determined. According to the empirical formula for estimating the distances from the epicenter of the explosion to a given place, the levels of the consequences of building destruction (complete, medium, small, moderate damage) can be established.


2021 ◽  
Author(s):  
N. Kana ◽  
R. Morad ◽  
M. Akbari ◽  
M. Henini ◽  
J. Niemela ◽  
...  

Abstract While room temperature bulk mercury is liquid, it is solid in its nanoconfiguration (Ønano−Hg ≤ 2.4 nm). Conjugating the nanoscale size effect and the Laplace-driven surface excess pressure, Hg nanoparticles of Ønano−Hg ≤ 2.4 nm embedded in a 2-D turbostratic BN host matrix exhibited net crystallization at room temperature via the experimentally observed (101) & (003) diffraction Bragg peaks of the solid Hg rhombohedric α-phase. The observed crystallization is correlated to a surface atomic ordering of 7 to 8 reticular atomic planes of the rhombohedric α-phase. Such a novel size effect on the phase transition phenomena in Hg is conjugated to a potential Hg waste storage technology. Considering the vapor pressure of bulk Hg, RT solid nano-Hg confinement represents a viable green approach for Hg waste storage derived from modern halogen-efficient light technology.


2021 ◽  
Vol 23 (1) ◽  
pp. 258-269
Author(s):  
R. Huseinov ◽  
Yu. Panchuk

The article purpose is to analyze the danger of man-made explosions and provide calculation methods for determining the mechanism of the occurrence of an explosion during forensic examinations of the study of the circumstances and mechanism of man-made explosions. The relevance of the article is caused by the fact that present-day production and everyday life cannot dispense with the usage of combustible and explosive substances. The particular attention to be paid to emergency prevention related to explosives, as well as the research to determine the mechanism of man-made explosions. The research on the mechanism of man-made explosions will make it possible to determine the technical cause of their occurrence, to analyze for what reason and for whose fault the event occurred, and also what measures should be taken to minimize the likelihood of such situations occurence. It is noted that in order to obtain reliable conclusions about the mechanism of man-made explosions, it is necessary to use scientifically based methods and methodologies allowing us to assess the extent of destruction. The degree of destruction of surrounding building structures and harm to people depends on overpressure caused as the result of a significant expansion of the explosion products and their spread to all directions from the center of explosion. The most frequent causes of explosions in the explosive object are: destruction and damage to production tanks, equipment and pipelines; deviation from production regulations (excess pressure and temperature of equipment operating mode), low-quality control of equipment and work while conducting require work, and untimely or poor-quality maintenance of technological equipment. The main calculation methods for the research of the man-made explosions in open areas, indoors, and limited space are given, which will allow to systematize the research process and analyze the flow of explosions in specific situations, and to establish a mechanism for their occurrence when conducting forensic examinations of the circumstances and mechanism of man-made explosions.


Author(s):  
Denys Serediuk ◽  
Yuriy Pelikan ◽  
Oleksandr Bas ◽  
Roman Manulyak

The article describes the implemented system of pneumatic lifting of the bell of the state primary standard gas volume and volume flow rate units. The system is composed of unified elements of industrial air preparation. There are elements for air purification in front of the compressor, dehumidifier, refrigerator dryer. With the use of a pneumatic system, the bell can be filled with prepared air with different values of excess pressure. The system is installed as a backup to the current to increase security. Pneumatic lifting of the bell allows you to connect a set of cylinders with pure inert gases or mixtures thereof to determine the impact on the gas meters metrological characteristics.


Author(s):  
Prof. Dinesh Parve

This paper report are design of autoloader center less grinding To reduce the man power during the total process of Top Link Crank Shaft. To reduce the Muri (for loading the 0.750 kg's part one by one in centre less grinding manually). Due to manual loading process production is depend on operator. , Delay for loading job or excess pressure applied on job during Grinding Incomplete grinding , Chances of accident , Extra load on centre less grinding machine (Grinding Wheel, Control Wheel & Carbide Plate).


2021 ◽  
pp. 58-64
Author(s):  
M. A. Ilgamov ◽  
A. G. Khakimov

An elastic rod of circular or rectangular section is rigidly fixed on both ends. The applicability of classical equations for the deformation of thin elements like rods, plates and shells to describe the stated problem is assessed using such integral characteristics, as eigenfrequencies. The assembly pressure is uniform, specifically atmospheric, and acts also on the areas of strip edges. It is assumed that there are no strains in this case. Excess pressures act only on the strip’s surface. The self-weight of the strip is neglected. Accounting for the attached mass of the surrounding medium and radiation penetrating into it shows that pressures in the upper and lower parts of the rod differ. But these factors are not taken into account, which can be justified in case of light gases. Since the relative axial lengthening at the boundaries equals zero in case of rigid clamping, it will also equal zero along the entire length in the absence of external axial forces. Frequency equations have been derived in case of the action of the surrounding pressure and also uniformly distributed and attached point masses. The influence of the excess pressure of the surrounding medium on the frequency spectrum of the rod oscillations is determined by the non-dimensional parameter that increases with an increase in pressure and the rod length and decreases with an increase of bending rigidity. At the negative excess pressure (vacuuming) this parameter reverses its sign, and the frequencies become lower. With an increase in both distributed and attached point mass the eigenfrequencies of oscillations decrease due to the rod invariable bending rigidity. The displacement of the point mass towards the center results in a decrease in odd eigenfrequencies, while even eigenfrequencies remain the same. Using the first frequency measured we can determine the excess pressure acting on the rod’s surface. Using two frequencies of bending oscillations we can determine the attached point mass and its coordinate. These results can be used when simulating the performance of resonators, including micro and nano ones.


Author(s):  
Kunihiko Aizawa ◽  
Francesco Casanova ◽  
Phillip E. Gates ◽  
David M. Mawson ◽  
Kim M. Gooding ◽  
...  

The parameters derived from reservoir-excess pressure analysis have prognostic utility in several populations. However, evidence in type 2 diabetes (T2DM) remains scarce. We determined if these parameters were associated with T2DM and whether they would predict cardiovascular events in individuals with T2DM. We studied 306 people with T2DM with cardiovascular disease (CVD; DMCVD, 70.4±7.8 years), 348 people with T2DM but without CVD (diabetes mellitus, 67.7±8.4 years), and 178 people without T2DM or CVD (control group [CTRL], 67.2±8.9 years). Reservoir-excess pressure analysis–derived parameters, including reservoir pressure integral, peak reservoir pressure, excess pressure integral, systolic rate constant, and diastolic rate constant, were obtained by radial artery tonometry. Reservoir pressure integral was lower in DMCVD diabetes mellitus and than CTRL. Peak reservoir pressure was lower, and excess pressure integral was greater in DMCVD diabetes mellitus than and CTRL. Systolic rate constant was lower in a stepwise manner among groups (DMCVD< diabetes mellitus <CTRL). Diastolic rate constant was greater in DMCVD than CTRL. In the subgroup of individuals with T2DM (n=642), 14 deaths (6 cardiovascular and 9 noncardiovascular causes), and 108 cardiovascular events occurred during a 3-year follow-up period. Logistic regression analysis revealed that reservoir pressure integral (odds ratio, 0.59 [95% CI, 0.45–0.79]) and diastolic rate constant (odds ratio, 1.60 [95% CI, 1.25–2.06]) were independent predictors of cardiovascular events during follow-up after adjusting for conventional risk factors (both P <0.001). Further adjustments for potential confounders had no influence on associations. These findings demonstrate that altered reservoir-excess pressure analysis–derived parameters are associated with T2DM. Furthermore, baseline values of reservoir pressure integral and diastolic rate constant independently predict cardiovascular events in individuals with T2DM, indicating the potential clinical utility of these parameters for risk stratification in T2DM.


Sign in / Sign up

Export Citation Format

Share Document