Centrifugal compressor anti-surge control system modelling

<span>From the middle of XX century, natural gas is an important mineral, widely used in the energy sector. Transportation of natural gas is carried out via gas pipeline networks and compression stations. One of the key features which need to be implemented for any centrifugal gas compressor is a surge protection. This article describes the method and develops software application intended for simulation and study of surge protection system of a centrifugal compressor used in modern gas compression stations. Within the article research method, modelling environment’s block diagram, proposed algorithms and results are described. For surge cases control and prediction, Anti-surge control block implemented which based on practical experience and centrifugal compressor theory. To avoid complicated energy balancing differential equations the volumetric flow calculation algorithm proposed which is used in combination with Redlich-Kwong equation of state. Developed software’s adequacy test performed through modeling of one-stage gas compression scheme at rated speed with comparison of parameters with reference commercial software and verification of the anti-surge control system.</span>

Models and Methods for Improving Performance of Wireless Computer Networks Based on the Decomposition of Lower Layers of the OSI Reference Model

The paper discusses models and methods for improving the performance of wireless computer networks built based on the decomposition of the lower levels of the OSI reference model. A method to improve the performance of networks is suggested, which functionally combines the physical and network layers, which improves its efficiency in marginal reception areas almost twice. A model of the block diagram of a device for improving data transmission quality in marginal reception areas or those with insufficient noise immunity is developed based on the so-called communication quality status monitoring, as well as a model of the block diagram of a wireless adaptive capacity reallocation router based on dynamic channels capacity reallocation, which allows adequately reallocating IS resources depending on traffic and user priority. Keywords— Bluetooth, FIFO discipline, IEEE 802.11, OSI/ISO reference model, wireless computer networks.

Colour Recognition Algorithm Based on Colour Mapping Knowledge for Wooden Building Image

In the cross-media image reproduction technology, the accurate transfer and reproduction of colour between different media are an important issue in the reproduction process, and the colour mapping technology is the key technology to effectively maintain the image details and improve the level of colour reproduction. Wooden structure in the image colour and colour piece is different, the image of each colour of visual perception is not independent, and every colour in the image pixels is affected by the surrounding pixels, but in the process of image map, without thinking of the pixel space, adjacent pixels of mutual influence in particular, do not let a person particularly be satisfied with the resulting map figure. In the process of image processing by traditional colour mapping algorithm, the colour distortion caused by colour component is ignored and the block diagram of colour mapping system is constructed. With the continuous development of mapping recognition algorithms, the maximum and minimum brightness values in the image are mapped to the maximum and minimum brightness values of the display device by linear mapping algorithm according to the flow of the established recognition algorithm. By establishing the colour adjustment method of the colour mapping image, the processing effect of the mapping algorithm is analysed. The results show that the brightness deviation of the image is reduced and the colour resolution is improved by the colour brightness compensation.

Performance reliability analysis of multi-state degraded system with improved Lz transform

Universal Generating Functions and Lz transformations have been widely used in the reliability modeling of multi-state systems. In order to solve the problem of complex calculations due to the dense random combination of multi-state performance parameters in the Lz transformation, a screening function is defined before the Lz transformation, and the screening function is combined with the performance threshold to screening the state performance parameters in advance, and the process is simplified through the screen matrix and the screen block diagram, effectively reduce the combined dimensions and quantity, improve the efficiency of reliability analysis, and combine with specific examples for application verification.

Quantitative risk assessment and safety databases in Romanian coal mining: preliminary systematic approach

Risk management is becoming increasingly more complex. Risk assessment, approached quantitatively, requires a factual database to define the likelihood of adverse health effects of workplace-related injuries and exposures, and it attempts to balance scientific knowledge with concerns of staff, investigators and administration. Practical guidance should be provided for Romanian coal mining companies to make progress in risk assessment process. Guidance is given on how to effectively introduce quantitative risk assessment in mining industry, the main goal being to highlight that the most valuable resource remains experience gained by effectively performing the process. Analyzing how various parameters are described/used, the paper aims to establish the place and role of quantitative risk analysis mining. Possibilities of developing safety/reliability database in coal mining are investigated. The block diagram describing the conceptual structure of a database on failures, safety of equipment and workers in the mining industry was developed. Because mining relies heavily on complex technologies - permanent mining facilities and large mobile equipment and support services - often located in isolated and hostile environments, the implementation of quantitative risk analysis and the development of a realistic database could be considered as a resilience business strategy and conversion of available knowledge into management actions.

Building a model of a problem situation in transport systems

The approach to construction of model of a problem situation in transport system is resulted, the block diagram of its algorithm is developed. It is revealed that the transition stage from the problem to the formulation of formal tasks is a problem situation, and the tasks can be solved in different ways, forming a set of strategies. It is noted that in the general case the result of operations is uncertain, which is caused by the uncertainty of the conditions of the operation and the action of factors of different nature. It is revealed that the acquisition of values of indicators that characterize one or another result of the operation is associated with the solution of the problem of modeling operations. The stages of the problem of studying the efficiency of the operation in the transport system are given. A number of assumptions are made about the process of obtaining results, which is associated with the formation of the operation model and obtaining efficiency estimates based on modeling results, as well as the process of analyzing the results, which involves solving the selection problem based on the established efficiency criterion or system of such criteria. It is found that the model of the problem situation in transport systems reflects the relationship of the main elements of the decision-making process and the sequence of formation of partial tasks and is built to cover the problem of decision-making as a whole, to present its main elements to be finalized. about the strategy of the operation. It is shown that the presence of a certain component as an independent element in the model of the problem situation assumes that the set of values of uncertain factors in the development of solutions will be either set externally, or finding these values will be an independent task. A list of actions for solving partial problems based on this model is presented. It is shown that in many practical cases it is observed that the a priori task of one of the main criteria of efficiency leads to the selection of some set of alternatives. Therefore, the choice of the best alternative requires the formation of a compound criterion, which includes both formal and informal prescriptions for making a judgment on the basis of which the selection or return and correction of elements of the model of the problem situation.

Analysis of Entrepreneurial Competency in East Java

Based on the 2018 Global Entrepreneurship Index’s data, globally, Indonesia is a country that has a low number of entrepreneurs, which position in 94 from 137 countries. Meanwhile, entrepreneurs have an important role in supporting the national economy in various aspects. Indirectly, they are required to have more competence to compete and survive longer. This research finds out the relevance of 30 characteristics in the three-cluster entrepreneurial competence block diagram for entrepreneurs in East Java. The authors use the qualitative method with the Miles and Huberman analysis technique. This data was collected by interviewing 11 entrepreneurs who have been selected based on the criteria. With the approach of Miles and Huberman, the researcher concluded that 11 entrepreneurs had 30 entrepreneurial characteristics and considered that these characters were important. The results identify that 30 characteristics in the three-cluster entrepreneurial competency block diagram are valid. In addition, the competence of entrepreneurs can be through a religious approach and the culture of the surrounding community. And during the pandemic, entrepreneurial competence is more relevant with the government and society support.

Implementasi Pengendalian Robot Mobil Pencari Target Dan Penghindar Rintangan

Robots are useful to help humans in performing jobs that require high precision, substantial labor, repetitive and dirty work, and high-risk or dangerous jobs. Those are the high-risk human jobs that a robot can do. Wheeled robots have the ability to go to the targeted position. Proportional control is used to control the movement of robots. In addition, the robot will also be equipped with PI control method to adjust the actual wheel speed of the robot. The block diagram of the obstacle-driven avoider robot consists of push button, rotary encoder, ultrasonic sensor, Atmega, IC L298D, DC Motor and Light. The results of the obstacle-driven avoider robot, wheeled robots have the ability to run in accordance with the desired black line. Proportional control is used to control the movement of robots. In addition, the robot will also be equipped with ultrasonic sensors to set the robot in avoiding obstacles. Based on the results of testing and analysis that have done, it is suggested that there is tool that can be provided to develop a more sophisticated technology like adding sensors or more features.

Elliptic Curve Pseudorandom Bit Generator with Maximum Period Sequences

Pseudo-random number generator is an important mechanism for cryptographic information protection. It can be used independently to generate special data or as the most important element of security of other mechanisms for cryptographic information protection. The application of transformations in a group of points of elliptic and hypereliptic curves is an important direction for the designing of cryptographically stable pseudo-random sequences generators. This approach allows us to build the resistant cryptographic algorithms in which the problem of finding a private key is associated with solving the discrete logarithm problem. This paper proposes a method for generating pseudo-random sequences of the maximum period using transformations on the elliptic curves. The maximum sequence period is provided by the use of recurrent transformations with the sequential formation of the elements of the point group of the elliptic curve. In this case, the problem of finding a private key is reduced to solving a theoretically complex discrete logarithm problem. The article also describes the block diagram of the device for generating pseudo-random sequences and the scheme for generating internal states of the generator.

DETERMINATION OF BOUNDARY CONDITIONS FOR THE RADIATION PATTERN OF A MICROELECTRO-OPTICAL INTELLIGENT PASSIVE INFRARED MOTION DETECTOR

In this paper, a block diagram of a microelectro-optical intelligent passive infrared motion detector is proposed. On the basis of the proposed structural scheme and analytically conducted synthetic processing of information from primary sources [5-17], boundary conditions for the directivity diagram of such a detector are determined. The analytical information collected in this article will be necessary for further modeling in computer-aided design with a view to new developments and improvements to existing motion detectors.