Development of a Mathematical Model for a Workpiece Heating and Cooling in a Protective Medium while Treatment under Pressure

The paper reviews and develops the mathematical model of plastic flow during the hot-forming processes. A flat non-stationary temperature problem for a cross-section of a long solid (rolled product) of arbitrary shape with different heat transfer conditions along the perimeter of the cross-section was considered. Equations for calculation of the thermal conductivity coefficient and heat capacity of tungsten billets were obtained in the temperature range of 700 - 1500°C, based on the literature data. Analytical dependences in form of regression equations were obtained, allowing for computer calculations of physical specifications of 11x11 mm VA grade tungsten billets in form of temperature functions with accuracy sufficient for practical calculations.

China crackdown reshapes cryptocurrency landscape

Significance Chinese provinces have banned cryptocurrency 'mining' (the creation of new units of cryptocurrency using complex computer calculations), affecting over 90% of global capacity. Impacts Falling demand for bitcoin mining equipment may help relieve the global shortage of semiconductors. Relocation of mining to other countries will reduce or increase bitcoin's environmental footprint depending on the country's energy mix. While cracking down on private cryptocurrency activity, China's government will enhance its own blockchain and digital currency programmes.

TO ASSESSMENT OF THE VALUE OF DYNAMIC LOAD OF FORESTRY MACHINES FROM THE INSTALLATION PLACE OF ITS SAFETY DEVICES

An integral part of the drive elements of machines in forestry are devices that ensure their protection against breakdowns during overloads. Safety devices can be installed on various parts of the kinematic chain of the machine drive elements: at the beginning, at the end or in the middle, and can also be built into the working unit (body). It is most advisable to install fuses closer to the end of the drive lines of the kinematic chain of the machine. If torque safety devices are installed at the beginning or in the middle of the drive, they are not in the overload zone (more often, overload occurs next to the working unit or directly on it). Under these conditions, the drive links of the kinematic chain are subject to overloads of various magnitudes. With distance from the place of occurrence of overload, the value of the value of the dynamic moment decreases due to elastic deformations and friction losses in the drive links of the machine. Consequently, there is a breakdown or destruction of parts and components of the drive, and the fuse itself does not work. Thus, in this article, using a calculated mathematical model of the actuation process of safety devices using a computer, calculations were carried out to determine the values of dynamic loads and an assessment was given in the case of installing a fuse at the beginning and at the end of the kinematic chain of the machine drive

Research strategy for development of instrument and computer support for diagnosis and treatment of addictive patients considering the consequences of the covid-19 pandemic

The article states кesearch strategy for development of instrument and computer support for diagnosis and treatment of dependents of patients considering the consequences of the COVID-19 pandemic. Due to the growing worldwide number of addicted people and the deterioration of this situation due to the spread of the COVID-19 pandemic, it is important to introduce improved methods of computer diagnosis, treatment and follow-up of addicted patients and those suffering from on diseases of the central nervous system (CNS). These categories of patients make up a risk group. The proposed methods include the development of a computer database "Addictiveness", the accumulation and generalization of instrumental diagnostic data and the results of patients examinations of the development of a mathematical procedure for correlation "Brain Similarity", to identify signs of symptoms closeness of a dependent patient to one from the groups of already examined persons and those who underwent treatment. On the basis of mathematical methods "Procedure Brain Similarity" and the corresponding data of the database "Addictiveness" the creation of a software package of addicted patients precision diagnostics with computer calculations is provided. Scientific research results, relevant theoretical and experimental developments are the methodological basis for sufficiently qualified studies of a number of poorly studied human CNS phenomena, including not only diagnosis and treatment of addictive patients, but also understudied phenomena of extreme functions of cognitive brain activity

Evaluasi Topik Tersembunyi Berdasarkan Aspect Extraction menggunakan Pengembangan Latent Dirichlet Allocation

Recently, Sentiment Analysis is used for expression detection of products or services. Sentiment Analysis is one category type with a level of aspect focused on extracting product aspects. One of the common methods used for aspect extraction is Latent Dirichlet Allocation (LDA) using random topic identification, but this method has not been able to find an acceptable topic with some aspects having been found. Undeterminable topics are referred to as the hidden topics. This study purpose is to evaluate and compare the suitability of identifying hidden topics between human and computer evaluation. The study is also focused on aspect extraction using a variety of LDA innovations. The data used in this study used case studies on e-Commerce. Data were processed using feature selection and grouped using LDA development. Then the data results are processed using Latent Topic Identification based on subjective and objective evaluations. The identification of hidden topic results was evaluated using several semantic and lexicon tests. The evaluation results indicate the comparison of two hidden topic identification assessment values is quite relevant with the average difference in value reaching 6%. As a result, computer calculations assist humans in determining topics if each topic has a low coherence value.

Basis Set Selection for Calculation of Structural and Electronic Properties of Systems Incorporating a Superoxide Radical in an Aqueous Medium

In this work, computer simulation has been carried out, and the molecular parameters of oxygen and a superoxide ion have been calculated to select the most optimal basis set of functions for further quantum mechanical calculations that include the presence of reactive oxygen species. For each particle, the equilibrium bond lengths and averaged polarizabilities in a continuous dielectric aqueous medium are obtained with the Conductor-like Polarizable Continuum Model (CPCM) and Solvation Model based on Density (SMD). Calculations for the 16 basic sets are conducted using the Orca software package. The obtained numerical values are compared with experimental data. The electron affinity energy of the oxygen molecule is used as the main selection criterion. The total time of computer calculations for each basis set is considered, and the most optimal basis sets are selected. The basis sets 6-31+G(d), 6-311+G, def2-TZVPD, and aug-cc-pVDZ are recommended for numerical calculations of molecular systems incorporating molecular oxygen and superoxide radical as its reduction product.

Laser cavity with a Van der Pol dynamics

In this article, a beam within a ring phase conjugated laser is described by means of a Van der Pol bidimensional dynamic map using an ABCD matrix approach. Explicit expressions for the intracavity chaos-generating matrix elements were obtained; furthermore, computer calculations for different values of Van der Pol map’s parameters were made. The rich dynamic behavior displays periodicity when the parameter ¹ (which determines the non-inearity term) takes values around zero. These results were observed in phase diagrams and in diagrams of the optical thickness of the intracavity element.

Analysis of the stress state of the ribbed-ring metal dome under different methods of installation

A computer model of the frame of a ribbed-ring metal dome of steel I-beams with a span of 30,3 m and a height of 7,5 m with rigid connections at the joints have been developed. Based on the design scheme, auxiliary models of a partially complete dome frameworks were designed to study alternative installation methods, which differ from each other in the location scheme of temporary supports with hinge joints of bar elements over them. The installation computer models utilized the three schemes of temporary supports: central support, central support and 1 circular row of intermediate supports, central support and 3 circular rows of intermediate supports. Computer calculations were performed for the design model of the dome framework and for all installation models to evaluate the impact of the self-weight of the dome on the stress state of the elements of its framework. As a result of the research, graphs and diagrams were created, which reflect the level of installation stresses in the meridional ribs in comparison with their values in the design scheme. The necessity to perform calculations of the dome frameworks during the design according to the installation conditions is noted.

Analysis of the Problem of Natural Gas Waterlogging

The domestic gas industry has been set an ambitious goal in the form of a state programme for extensive gasification of Polish cities and towns. This provides for transition of the municipal thermal energy and of the municipal economy to natural gas. Ensuring of reliable and safe transport of the gaseous fuel is also a part of this programme. The article discusses the problems of transporting of the nitrogen-rich natural gas from the local mines, related to water of unknown origin appearing in it. The events that can confirm that there is a possibility of moisture condensation from the gas and its migration deep into the distribution network have been analysed. The actual level of moisture in the natural gas, which is already directly supplied to the consumers, has been experimentally tested. It has been proved by the computer calculations that in the conditions of high pressure in the network, there is a possibility of such condensation, depending on the external atmospheric conditions and physicochemical parameters of the gas. It has been proposed to change the existing designing & construction legal provisions in order to protect the gas networks against water accumulating in them in a better way.