Hydraulics and hydraulic drives

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Final Rating.BAROTOV JAVOHIR (1)

Tashkent State Technical University named after Islam Karimov

Faculty of Mechanical Engineering

Group: 64A-19 MT




1. The basic equation of hydrostatics and its energetic meaning.
2. Water hammer in pipelines. Designs equation and methods for reducing water hammer. Zhukovsky's formula.
3. Local resistance. Theoretical and practical methods for calculating the coefficient of local resistance.
1. Fluid statics or hydrostatics is the branch of fluid mechanics that studies "fluids at hydrostatic equilibrium[1] and the pressure in a fluid or exerted by a fluid on an immersed body".[2]

Table of Hydraulics and Hydrostatics, from the 1728 Cyclopædia

It encompasses the study of the conditions under which fluids are at rest in stable equilibrium as opposed to fluid dynamics, the study of fluids in motion. Hydrostatics is a subcategory of fluid statics, which is the study of all fluids, both compressible or incompressible, at rest.

Hydrostatics is fundamental to hydraulics, the engineering of equipment for storing, transporting and using fluids. It is also relevant to geophysics and astrophysics (for example, in understanding plate tectonics and the anomalies of the Earth's gravitational field), to meteorology, to medicine (in the context of blood pressure), and many other fields.

Hydrostatics offers physical explanations for many phenomena of everyday life, such as why atmospheric pressure changes with altitude, why wood and oil float on water, and why the surface of still water is always level.

2.Water hammer is a phenomenon that can occur in any piping system where valves are used to control the flow of liquids or steam. Water hammer is the result of a pressure surge, or high-pressure shockwave that propagates through a piping system when a fluid in motion is forced to change direction or stop abruptly. This shockwave is also commonly referred to as a hydraulic shock or hydraulic surge, and may be characterized by a marked banging or knocking sound on the pipes immediately after shutoff.

Water hammer can occur when an open valve suddenly closes, causing the water to slam into it, or when a pump suddenly shuts down and the flow reverses direction back to the pump. Since water is incompressible, the impact of the water results in a shock wave that propagates at the speed of sound between the valve and the next elbow in the piping system or within the column of water after the pumpvisible. Since the velocity at any point in the flow has a single value (the flow cannot go in more than one direction at the same time), streamlines cannot cross. except at points where the velocity magnitude is zero, such as at a stagnation point
The transform is

{\displaystyle z=\zeta +{\frac {1}{\zeta }},}{\displaystyle z=\zeta +{\frac {1}{\zeta }},}

where {\displaystyle z=x+iy}z=x+iy is a complex variable in the new space and {\displaystyle \zeta =\chi +i\eta }{\displaystyle \zeta =\chi +i\eta } is a complex variable in the original space.

This transform is also called the Joukowsky transformation, the Joukowski transform, the Zhukovsky transform and other variations.

In aerodynamics, the transform is used to solve for the two-dimensional potential flow around a class of airfoils known as Joukowsky airfoils. A Joukowsky airfoil is generated in the complex plane ({\displaystyle z}z-plane) by applying the Joukowsky transform to a circle in the {\displaystyle \zeta }\zeta -plane. The coordinates of the centre of the circle are variables, and varying them .

3. The treatment for infections in hospitalized patients can be summarized in the timely start of empirical therapy, followed by adjustment on the basis of isolates and microbial susceptibilities. Initial therapy may be based on international guidelines. However, to know local frequencies of bacterial and fungal strains together with patterns of drug resistance should be a better approach to therapy. REGIMEN is a retrospective observational study of all consecutive recorded bacterial and fungal isolates, collected between October 2009 and August 2011 from patients admitted in a 53-bedded ward of internal medicine of a non-teaching Italian hospital. We investigated type of samples and of microorganisms, patterns of susceptibility and resistance to antibiotics, and in-hospital mortality. A total of 504 samples were examined (244 from urine, 189 from blood and 71 from skin and various exudates). Participants were old (mean age, 83 years), and so overall mortality was high (20 %). There were high frequencies of drug resistance; only 27.9 % of urinary gram-negatives and 52.6 % of blood gram-
negatives were susceptible to levofloxacin. Susceptibility profiles compatible with the presence of extended-spectrum beta-lactamases were present in 64.2 % of gram-negative strains, and 10.1 % were also resistant to carbapenems. ESKAPE organisms account for a third of all bacterial infections. Local patterns of drug resistance should influence empirical antibiotic therapy for patients admitted in internal medicine wards, where mortality is high.modifies the shape of the resulting airfoil.
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