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Protect the surface of the concrete floor
To protect the concrete floor, which is operated in the normal mode, or is subject to wear in areas with high traffic, there are several ways to protect the surface.
   Comparable ways: their cost, appearance and ability to perform the task to protect.
   In this article, we consider three ways to finish and protect the floor. Each of them has its advantages and disadvantages.
  
   Thin fil...

Finishing compositions based on water glass. Part 3
When used as part of exhaustion moderator comes coagulation and solidification of liquid glass. However, due to the presence in the composition of Portland cement with a finishing time is an increase strength of the coating due to hydration of cement minerals. Thus from colloids formed during the coagulation liquid glass are actively assigned to the water for hydration of cement, a porous media formed tumors filled Portland cement, which leads to...

Finishing compositions based on water glass. Part 2
Studies in Berlin Institute Federal institute for Materials Research and Testing, show that the average density of 1730 kg/m3 brick large proportion of pores having a size in excess of 1 micron is more than 90% [3] and they are responsible for the increased migration of fluids through brickwork.
   Most fully meet these requirements structure obtained by coagulation and water-soluble potassium silicate forming silica with a high sp...

Modernization and repair of self-propelled machines. (3)
Hardening electrolysis BORATING hinge pins and bushings mates working equipment hydraulic excavators EO-4121 (EA-4321) gives an increase in wear resistance 4-6 times compared to the bulk quenching details.
   Taking into account the high wear resistance of brazed blades, hardened sintered alloys (see Table 1), are recommended for carbide knives dumps graders DZ-122 and RS-98, combined machine E-405 based on KAMAZ, for front dumps a t...

Specialized exhibition Architecture. Construction (END)
Mari-lime brick and gas silicate blocks
   JSC "MZSK" produces silicate brick and a half, color (white, yellow, black, red, blue, green, brown).
   For the production of silica brick used quartz sand from quarries near the plant. Limestone enters the factory with Dobryatinskogo deposit Vladimir region. Silicate brick (Table 1) is used for masonry exterior and interior walls of buildings and structures, as well as ...

Geophysical processes primers and security. Part 5
In the center of Moscow can distinguish vertical structure comprising a crashing into the Earth`s crust magma elongated cylinder (Fig. 2) [5]. In the center section marked lack of extensive vertical zone converted waves ("blind spot"), going from the depths of 70-80 km to 7.5 km. Such "blind spots" are characteristic of the earth`s crust with the introduction of monolithic dense mantle rocks such as gabbro, diabase, etc. In such a zone Tashkent e...

Finishing compositions based on water glass. Part 1
The quality of the decoration of buildings for new construction and reconstruction depend not only on their aesthetic, but also the operational parameters, as good-quality finish - a guarantee of durable service basic designs, long maintenance-free operation, the costs for maintenance and care. Traditional binders used for the production of finishing compositions, liquid glass is widely used, but it has some drawback: coatings based on it gaining...

On possible amendments to the equation Griffiths
Griffith presented a picture of destruction allowed to formulate the problem of determining conditions of the beginning of crack propagation and find its general solution.
   As seen from the above schemes, in the process of crack propagation material directly adjacent to it "coasts" unloaded relaxes. This means that the stress and strain it decreases, and the elastic energy stored earlier in this area of ​​the body is re...

Construction skyscrapers - the requirements of modernity. Part 4
The program is a high-rise building in Moscow
   The project is now a high-rise building in Moscow is implemented in two main areas: the construction of business center "Moscow City" and implementation of the program of the Government of Moscow "New Ring of Russia."
   1. Moscow international business center "Moscow - City"
   The project includes the construction of buildings on the territory of abou...

Degree project - beginning of the road. (3)
Given the great diversity of subject matter and content of diplomas in various specialties, the jury is faced with great difficulties in determining the winners - "Who better violinist or a dancer?". Nevertheless, often based on emotional perception and can estimate the relevance and novelty, and the author`s contribution to the thesis project or job. Absolute winners in recent years have been graduates of Rostov CSO GASU St. Petersburg, Nizhny N...

 

 
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 Optimization  aerodynamic  calculations  duct  ventilation  systems

Existing techniques aerodynamic calculation is based on the selection of duct diameters on their recommended speed range which is generally determined by technical and economic requirements and depends on the purpose of the ventilation system. Availability ranges recommended speeds determines the calculated ambiguity of options corresponding to different values ​​of air velocity in the areas and regions respectively differing diameters ventilation network. Values ​​are calculated options to meet the requirements for the recommended air velocity values ​​will be different diameters sites, and possibly loss of air pressure in the system and the cost of its manufacture. This makes it necessary to develop methods of optimization of aerodynamic calculation to facilitate the search of optimal settlement option, corresponding to the minimum reduced cost.
   Known analytical solution to this problem [1, 2], based on the determination of the optimal diameter of the duct or air velocity at which satisfies the requirements (1), allow to perform with sufficient accuracy within the optimization of the constraints, in particular for a network consisting of one settlement area, and can not be extended to branched ventilation network without making simplifying assumptions, making it difficult to find a common analytical solutions.
   As a result of the analysis of the process of energy transport by air ducts, we have developed a method for optimizing the aerodynamic calculation of ventilation branched networks of arbitrary configuration. The basis of this method consists of two optimality conditions calculating ventilation network, providing the minimum of (1).
   Condition (2) an important corollary - the maximum air velocity in ducts should be in areas with maximum air flow and minimum - in areas with minimum consumption. This conclusion is confirmed by the selection rules of thumb air velocities in the areas which according to the air velocity in the duct should be increased to a maximum value at the maximum to the end portions of the joining portion on the fan.
   Equation (2) is a necessary and sufficient condition for choosing the best option from a variety of settlement options with equal loss of air pressure in the ducts or the same material consumption.
   Accounting requirements (2) and (3) is recommended as follows:
   before the appointment of the duct diameter by the formula (3) is determined by the desired value of the optimization parameter qi;
   after the appointment diameter plots and determine the loss of air pressure is determined by the actual value of qi for each site;
   Match the desired and actual values ​​of qi indicates the optimal choice of the diameter of the area;
   significant difference in the required and actual values ​​of the optimization parameter in the area, its diameter must be changed, while, if the actual value is greater than required, the diameter of the area must be increased, and if the actual value is less than required - reduce.
   The above optimization conditions (2) and (3) are applicable to both the circular duct and the rectangular cross-sectional shape.
  

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