scholarly journals РЕКОМЕНДАЦИИ ПО ПРОЕКТИРОВАНИЮ ГИДРОСТАТОДИНАМИЧЕСКИХ ПОДШИПНИКОВ СКОЛЬЖЕНИЯ СДВОЕННОГО ТИПА

2020 ◽  
pp. 100-105
Author(s):  
Владимир Иосифович Назин
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Layer ◽  
High Reliability ◽  
Experimental Studies ◽  
Working Fluid ◽  
Stable Operation ◽  
Static And Dynamic Characteristics ◽  
Start Up ◽  
Bearing Materials

The task is to develop recommendations for the design of dual-type hydrostatodynamic plain bearings based on the existing experience in designing this type of plain bearings, as well as based on many theoretical and experimental studies performed by the author of this work. The number of the most necessary parameters for the design of dual-type hydrostatodynamic bearings is determined. Particular attention was paid to the development of recommendations for additional parameters specific to the design of double type plain bearings. Attention is paid to the selection of double-type bearing materials and it is shown that the problem of selecting materials for hydrostatic dynamic bearings is not so relevant, however, sometimes in start-up and shutdown modes, as well as in emergencies, to ensure high reliability of the designed machine, it is necessary to pay attention to the choice of bearing materials. The influence of various forms of chambers on the static and dynamic characteristics of hydrostatodynamic bearings is analyzed and it is shown that the greatest distribution in practice, they got rectangular cameras. It is shown that the flow regime of the working fluid also significantly affects both the static and dynamic characteristics of the bearing. It is noted that even with a non-rotating rotor in a hydrostatodynamic bearing, the most turbulent mode of flow of the working fluid is most often observed. The influence of the thickness of the working fluid layer on increasing the rigidity of the supports and expanding the range of stable operation is considered. It is shown that with a decrease in the clearance in the bearing, its bearing capacity increases and the range of stable operation expands, however, this increases the friction power loss, increases the likelihood of clogging of the slit bearing path, and also increases the requirements for the quality of manufacture of the bearing working surfaces. It is recommended that in the double hydrostatodynamic bearing in the outer and inner parts to assign the same clearances. It is shown that in a dual hydrostatodinamic bearing, the existing recommendation on the number of chambers can lead in some cases to large working fluid flow.

Experimental Study on the Static and Dynamic Characteristics of Screw Grooved Seals

1988 ◽  
Vol 110 (3) ◽  
pp. 326-331 ◽  
Author(s):  
H. Kanki ◽  
T. Kawakami
Keyword(s):  
Dynamic Characteristics ◽  
Load Capacity ◽  
Experimental Studies ◽  
Test Method ◽  
Test Facility ◽  
Test Results ◽  
Heavy Duty ◽  
Static And Dynamic Characteristics ◽  
Basic Characteristics ◽  
Annular Seals

Screw grooved annular seals are used in many heavy duty pumps such as boiler feed pumps. These annular seals have a significant effect on rotordynamic characteristics of the pumps. Studies on the dynamic characteristics of plain and circumferentially grooved annular seals have been published by many researchers. However, published works on screw grooved seals are few, and pump designers have not fully recognized the basic characteristics of screw grooved seals. Extensive experimental studies have been conducted for determining the basic characteristics of screw grooved seals. The leakage characteristics, load capacity, and dynamic characteristics for rotordynamic analysis were determined by using a specially designed test facility and test method. The test results were compared to the results of plain seals [3] and the basic differences were extracted for effective application of screw grooved seals.

scholarly journals On Characteristics of Symbolic Execution in the Problem of Assessing the Quality of Obfuscating Transformations

2021 ◽  
Vol 28 (1) ◽  
pp. 38-51
Author(s):  
Petr D. Borisov ◽  
Yury V. Kosolapov
Keyword(s):  
Machine Learning ◽  
Dynamic Characteristics ◽  
Symbolic Execution ◽  
Specific Class ◽  
Static Characteristics ◽  
Learning Methods ◽  
Static And Dynamic Characteristics ◽  
Machine Learning Methods ◽  
Relevant Task

Obfuscation is used to protect programs from analysis and reverse engineering. There are theoretically effective and resistant obfuscation methods, but most of them are not implemented in practice yet. The main reasons are large overhead for the execution of obfuscated code and the limitation of application only to a specific class of programs. On the other hand, a large number of obfuscation methods have been developed that are applied in practice. The existing approaches to the assessment of such obfuscation methods are based mainly on the static characteristics of programs. Therefore, the comprehensive (taking into account the dynamic characteristics of programs) justification of their effectiveness and resistance is a relevant task. It seems that such a justification can be made using machine learning methods, based on feature vectors that describe both static and dynamic characteristics of programs. In this paper, it is proposed to build such a vector on the basis of characteristics of two compared programs: the original and obfuscated, original and deobfuscated, obfuscated and deobfuscated. In order to obtain the dynamic characteristics of the program, a scheme based on a symbolic execution is constructed and presented in this paper. The choice of the symbolic execution is justified by the fact that such characteristics can describe the difficulty of comprehension of the program in dynamic analysis. The paper proposes two implementations of the scheme: extended and simplified. The extended scheme is closer to the process of analyzing a program by an analyst, since it includes the steps of disassembly and translation into intermediate code, while in the simplified scheme these steps are excluded. In order to identify the characteristics of symbolic execution that are suitable for assessing the effectiveness and resistance of obfuscation based on machine learning methods, experiments with the developed schemes were carried out. Based on the obtained results, a set of suitable characteristics is determined.

scholarly journals EXPERIMENTAL RESOURCE STAND RESEARCH OF THE GOLDEN DIVISION DISTRIBUTOR

2019 ◽  
pp. 80-86
Author(s):  
Volodymyr Rutkevych
Keyword(s):  
Hydraulic Drive ◽  
Operating Conditions ◽  
Working Fluid ◽  
Stable Operation ◽  
Initial Stage ◽  
Flow Divider ◽  
Main Components ◽  
Working Bodies ◽  
Cost Characteristics

The article discusses and analyzes the operating conditions of a modern hydraulic drive. Despite the difficult operating conditions of modern agricultural machinery (difficult working conditions, frequent changes in the technological load on the working bodies, low quality of the working fluid, increased dust content and temperature fluctuations), the hydraulic drive is its main reliable element. The basis of hydraulic drives is hydraulic spool type devices, they remain the main components of a modern hydraulic drive, are able to increase energy, dynamic, cost characteristics and increase the reliability and durability of this drive. The advantages, disadvantages and directions of improvement of this drive are noted. The modern directions of development of the hydraulic drive aimed at increasing the reliability, durability and adaptability to changing the technological load on the working bodies are considered. A booth design is proposed that allows to investigate a resource study of the developed spool splitter of a forage stem feeder. As a result of the research at the initial stage, some shortcomings in the structural implementation of the developed spool of the flow divider at the time up to 2·104 cycles were revealed. After analyzing the operating conditions and making changes to the design of the stem feeder spacer spacer and retesting, the spacer spacer showed stable operation, with more than 6.6·105 load cycles.

scholarly journals ОСОБЛИВОСТІ ТЕРМОІМПУЛЬСНОГО ОЧИЩЕННЯ ПОВЕРХОНЬ І КРОМОК ДЕТАЛЕЙ ВІД ЗАБРУДНЕНЬ ПІСЛЯ МЕХАНІЧНОЇ ОБРОБКИ

2018 ◽  
pp. 36-46
Author(s):  
Алексей Васильевич Лосев ◽  
Игорь Валерьевич Бычков ◽  
Вячеслав Викторович Коллеров ◽  
Анна Сергеевна Селезнева
Keyword(s):  
Experimental Studies ◽  
Cost Effective ◽  
Operating Conditions ◽  
Working Fluid ◽  
Body Parts ◽  
Hydraulic Systems ◽  
Cost Component ◽  
Internal Surfaces ◽  
And Control

The requirements for the quality of aviation technology are decisive in the creation of technological systems that ensure the industrial purity of products. But the cost component of the finishing and stripping technologies is also important, the value of which depends on the chosen method of removing liquids, for example, from hydraulic units of aircraft. Reliable and cost-effective manufacture of parts with specific geometric and technological properties is the main goal of industrial production. In a market economy, the production of competitive products is a necessity, and it is always the choice of a rational, stable price-quality ratio. The quality of engineering products is a multifactorial problem, depending on the complex of systemic organizational and technological measures. In the production of aircraft technology, quality assurance is associated with dependability and a guaranteed resource that is vital due to specific operating conditions. One of the most important measures to ensure the reliability and guaranteed life of aviation products is to ensure industrial cleanliness. Cleaning from microparticles, macro- and micro-hauler surfaces and edges of parts after mechanical types of processing is included in the complex of these measures. The most problematic is the cleaning of body parts with a complex configuration of external and internal surfaces. The need to remove liquids and other technological pollution is explained by functional, ergonomic and aesthetic reasons. If ergonomic and aesthetic factors do not affect the technical characteristics of products, then the functional ones are directly related to the operability of machines and mechanisms. Functional causes are the prevention of failures of hydraulic distribution and control devices, as well as the prevention of increased wear of critical parts occurring when friction pairs of solid metal particles enter the gaps, difficulties in assembling and positioning, reducing fatigue strength and so on. Burrs cause turbulence in the flow of gas or liquid, disrupting the flow uniformity. It is obvious that the mutually influencing processes occurring in the hydraulic systems of machines, in violation of working conditions, lead to an increase in negative phenomena. The peculiarity of the use of purification technologies is the need to remove liquids from 100% of the parts included in the autonomous system of mechanisms. If at least one detail is left untreated, then the working fluid, when in contact with contaminated surfaces, washes away these contaminants and spreads them throughout the system, while the most sensitive elements are damaged. The reasons for the need to clean the surface and edges of parts from technological contamination are given. A brief review of the results of modeling and research on the removal of burrs in the environment of detonating gas mixtures has been performed. The features of the thermopulse process are considered and the results of numerical and experimental studies are presented. A comparative analysis of the energy intensity of removing burrs of various metals is shown.

scholarly journals Mini crusher-shredder for farms

2021 ◽  
Vol 264 ◽  
pp. 04038
Author(s):  
Komil Astanakulov ◽  
Fakhriddin Karshiev ◽  
Shokir Gapparov ◽  
Dilshod Khudaynazarov ◽  
Shavkat Azizov
Keyword(s):  
Rotation Angle ◽  
High Reliability ◽  
Experimental Studies ◽  
Mathematical Planning ◽  
Quality Performance ◽  
Working Bodies ◽  
Planning Of Experiments ◽  
Good Visibility ◽  
Rotary Type

The purpose of the study is to substantiate the parameters of a mini crusher-shredder for processing coarse feed stalks in farms. The feasibility of using a mini crusher-shredder for processing coarse feed in the conditions of farms and farms with a small number of animals, which has a rotary-type shredder that combines the operations of grinding and crushing, is justified. The research uses the laws and rules of mathematical statistics, mathematical planning of experiments, and the methods given in existing regulatory documents. Experimental studies were carried out to study the influence of the rotor parameters of the mini crusher-shredder on its quality performance. A compact crusher-shredder has been developed, which has good visibility of the working bodies, high reliability, and quality of work due to zootechnical requirements. Experimental studies have established that when using a hammer of a flat-turned shape with a lower sharpening and a rotation angle of 60 or more, high-quality grinding of the stems is provided.

Risk Assessment Studies of Gasketed and Non-Gasketed Bolted Pipe Joints

2002 ◽  
Author(s):  
Muhammad Abid ◽  
David H. Nash
Keyword(s):  
Risk Assessment ◽  
Structural Integrity ◽  
High Reliability ◽  
Experimental Studies ◽  
Pressure Vessels ◽  
General Observation ◽  
Excellent Service ◽  
Pipe Joints ◽  
The Right

Over many years much effort has been made to develop design codes for pressure vessels, pipe-work, flanges and so on to design a system of high structural integrity. In-spite of the efforts the reliability of the system can be adversely affected for many reasons. Poor construction practices, incorrect selection of components such as gasket, improper quality of bolts and surface treatment, incorrect tooling, wrong application, underestimated joint size due to incorrect loading consideration, incorrect use of code, lack of thought to plant use, or a change of use during the life of a plant may make a joint unsuitable. The list is not exhaustive and not all the possible causes of failure may become apparent during commissioning. Failure of a pipe joint means the achievement of a leak rate below a certain maximum limit or the gross failure of the pipeline in which structural integrity is lost. So the high reliability of a system can be obtained if the right joint is selected for an application and factors that affect the reliability should be considered carefully. A very limited work has been done for the risk assessment of bolted pipe joints. At first, the most comprehensive work is done by Det Norske Veritas (DNV) regarding risk assessment of pipe joints. In addition, Webjorn and Thompson have also performed comparative reliability studies for these joints. Both DNV and Webjorn concluded that compact flange joints show better functional safety than conventional gasketed flange joints. Thomson concluded that both the joints are of high integrity and perform well in excellent service under appropriate installation and maintenance conditions. All above studies have been performed based on information and observations. Present author has performed detailed failure mode and effects analysis (FMEA) in the light of above-mentioned studies, idustrial surveys, analysis, experimental work and subsequent observations. The aim of the study was to increase the reliability knowledge about the gasketed and non-gasketed flanged pipe joints and thereby to increase the basis for finding the optimal pipe connection based on general observation and experimental studies performed.

Invited PaperTemperature dependence of SiGe HBT static and dynamic characteristics

1998 ◽  
Vol 08 (PR3) ◽  
pp. Pr3-81-Pr3-86
Author(s):  
F. Aniel ◽  
N. Zerounian ◽  
A. Gruhle ◽  
C. Mähner ◽  
G. Vernet ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Static And Dynamic Characteristics ◽  
Sige Hbt

The system of indicators of the quality of the carbon-carbon composite materials and technologies of their production

2018 ◽  
pp. 127-132
Author(s):  
T. N. Antipova ◽  
D. S. Shiroyan
Keyword(s):  
Composite Material ◽  
Low Cost ◽  
Experimental Studies ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Optimal Number ◽  
Laboratory Equipment ◽  
Carbon Composite Material ◽  
Carbon Composite Materials

The system of indicators of quality of carbon-carbon composite material and technological operations of its production is proved in the work. As a result of the experimental studies, with respect to the existing laboratory equipment, the optimal number of cycles of saturation of the reinforcing frame with a carbon matrix is determined. It was found that to obtain a carbon-carbon composite material with a low cost and the required quality indicators, it is necessary to introduce additional parameters of the pitch melt at the impregnation stage.

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