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The scroll compressor is a kind of positive-displacement compressor applied in refrigeration systems, heat pump systems, and air conditioner systems. Using the spring smoothing method and considering the heat transfer, the numerical simulation model of the scroll compressor is established under standard working conditions. The results show that the CFD model is well validated by the experiment result. The compressor performance and the working process are analyzed. The pre-compression and the over-compression phenomenon are also studied. Moreover, the temperature distribution and velocity distribution of gas flow in the compressor are illustrated. The result shows that the pre-compression can improve the performance of the scroll compressor and the optimization of the suction channel geometry can provide a smoother suction process. Under the combined effect of the pre-compression and heat transfer, the refrigerating capacity is increased by approximately 0.54 kW and the volume efficiency is increased by approximately 2.2%. The additional power loss due to over-compression is 47.6615 W, and the setting of over-compression discharges can reduce the pressure and power loss. This study is helpful to the performance prediction and the structural optimization of the scroll compressor. [ABSTRACT FROM AUTHOR]

Copyright of China Textile Leader is the property of China Textile Information Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the most effective vulnerability discovering method, fuzzing testing has been widely used in the field of network protocol security detection and has given birth to a large number of research results. No work has been done to provide a comprehensive summary and analysis of protocol fuzzing testing techniques. Firstly, reviews the development of protocol fuzzing testing and summarizes the work done by existing protocol fuzzing testing and its shortcomings according to its workflow: preprocessing, seed generation, execution process monitoring, and result analysis. After that, the challenges of protocol fuzzing testing techniques in different scenarios and the solutions are analyzed. Finally, the limitations of the current protocol testing methods and the future development directions are discussed. [ABSTRACT FROM AUTHOR]

A 3D scanner is a non-contact, non-destructive digital device that uses a light line/laser to accurately capture the shape of a physical object into Computer-Aided Design (CAD) data. It generates a point cloud or a set of data points in a coordinate system that accurately depicts a physical object's size and shape. The urge of human beings to build and recreate 3D objects is an essential requirement in the context of Industry 4.0. In Industry 4.0, 3D scanners are helpful for designing, assessing the minor features of any product, capturing freeform, and providing precise point clouds for complicated geometry and curved surfaces. Today advanced technologies are being introduced in industries, and 3D scanning technology is one of the latest emerging technologies. The situation has progressed significantly, and the ever-emerging world of 3D technology still disrupts a variety of sectors. This paper discusses 3D Scanning, its working process, and its adoption for reverse engineering and Industry 4.0 culture. Finally, this paper covers essential features, traits, and applications of 3D Scanning for Industry 4.0. Using different methods, 3D Scanning can collect information about an item, about an object's highness, breadth, and depth. 3D scanners are available on the market from high-end possibilities. They have different resolutions, and now they provide details of the scan to superimpose colour on an object, but the industry wants them to be developed for other quality attributes.

Abstract Background The ability to learn collaboratively and work in teams is an essential competency in both educational and healthcare settings, and collaborative student activities are acknowledged as being an important part of the pedagogical approach in higher education and teaching. The course that was the focus of this research, a 15-ECTS-credit online course in philosophy of science, ethics, and research methods, was offered online as part of 11 master’s-level health programmes at a university in Norway. Collaborative learning in combination with digital teaching tools was the preferred pedagogical approach in the online course. The aim of the study was to describe, explore and discuss how the students collaborated in small groups in an online course to learn. Methods We performed six focus groups and 13 individual interviews from February 2018 to May 2019, conducting a qualitative case study with a content analysis of the data collected. The participants were master students in the same faculty at a university in Norway. All the included participants had fulfilled the 15 ECTS credit course. Results Our study revealed that the collaboration in small groups resulted in three different working processes, depending on the students’ ability to be flexible and take responsibility for their own and common learning. The three different working processes that emerged from our data were 1. joint responsibility – flexible organization; 2. individual responsibility – flexible organization; and 3. individual responsibility – unorganized. None of the groups changed their working process during their course, even though some experienced their strategy as inadequate. Conclusions Our study showed that despite similar factors such as context, assignments and student autonomy, the students chose different collaboration strategies to accomplish the online course learning objectives. Each group chose their own working process, but only the strategy 1. joint responsibility – flexible organization seemed to promote collaboration, discussion, and team work to complete the complex assignments in the online course. The result from our study may be helpful in designing and planning future online courses; hence online learning requires a focus on how students collaborate and learn online, to gain knowledge and understanding through group discussion.

New views on elements that make an enterprise and its environment were brought by cybernetics. Every change that happens in any natural or organized system has a destructive character. The intensity of that force depends on resistance emitted toward change. With a new change, the dual action of technical progress manifests. Affirmative (progressive) and devaluating (regressive). Changes under the action of technical progress bring change in the functioning of organizational systems. Balance is at stake with elements that constitute one system as well as with enterprises and their surroundings. Cybernetics identifies the power and dynamics of change and stand to bring things and process into the primary state of equilibrium. Cybernetics must respect events of the environment in which organizational system exists and their influence on happenings in managing systems. Enterprise is not an isolated system but a legal bond of connections between certain parts of inner or outer parts. In this work, we will put an accent on elements that purposely or autonomously create changes. We will symbolically represent the surrounding in which the whole process of enterprise development is taking part, as well as a partial complex of that process which makes: the development of product, the development of market, the development of resources, the development of capacity, and the working processes. If the solution to newly created problems made by changes is wanted or known, the algorithm is always possible. [ABSTRACT FROM AUTHOR]

A 3D scanner is a non-contact, non-destructive digital device that uses a light line/laser to accurately capture the shape of a physical object into Computer-Aided Design (CAD) data. It generates a point cloud or a set of data points in a coordinate system that accurately depicts a physical object's size and shape. The urge of human beings to build and recreate 3D objects is an essential requirement in the context of Industry 4.0. In Industry 4.0, 3D scanners are helpful for designing, assessing the minor features of any product, capturing freeform, and providing precise point clouds for complicated geometry and curved surfaces. Today advanced technologies are being introduced in industries, and 3D scanning technology is one of the latest emerging technologies. The situation has progressed significantly, and the ever-emerging world of 3D technology still disrupts a variety of sectors. This paper discusses 3D Scanning, its working process, and its adoption for reverse engineering and Industry 4.0 culture. Finally, this paper covers essential features, traits, and applications of 3D Scanning for Industry 4.0. Using different methods, 3D Scanning can collect information about an item, about an object's highness, breadth, and depth. 3D scanners are available on the market from high-end possibilities. They have different resolutions, and now they provide details of the scan to superimpose colour on an object, but the industry wants them to be developed for other quality attributes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

After the launching of the health reform in the sphere of primary medical aid and a comparatively successful 20-years' accomplishment, a need has arisen for an update of the medical standards ratifying the activity of the general medical practice (2011). The study of the work of the general practitioner in an ergonomic aspect requires the construction of a reliable complex of methodological studies providing a realistic assessment of the organization of the working process and of basic psycho-physical functions in the daily and weekly dynamics, carried out on the background of a dominant attachment of the physician to the chosen area of expertise. The basic approaches for determination of the structure and expenses of the working time, or the efficiency coefficient (EC) respectively and intensity of labour involve the photochronometric- and the method of linear timing (also tracing the synchronization of the activity of the medical team); the spatial timing measuring the working trajectories, evidencing the degree of provision of functional working equipment and the objective conditions of labour. Sociological studies provide data on the style of communication with the patient and the occurrence of dilemmas of bioethical nature, as well as the strategies for their overcoming; sanitary and hygienic conditions of the working environment and their observation in accordance with the required criteria and indicators. The methodologies enable objective assessment of the workload and structure of the physician's working time and the resulting fatigue. Preconditions are created for the implementation of optimal organizational and technological operations in the provision of medical services, aiming to increase in the efficiency of the working process, and establishment of a physiological regime of labour in the general medical practice within the framework of the effective legislation.

Background: The ability to learn collaboratively and work in teams is an essential competency in both educational and healthcare settings, and collaborative student activities are acknowledged as being an important part of the pedagogical approach in higher education and teaching. The course that was the focus of this research, a 15-ECTS-credit online course in philosophy of science, ethics, and research methods, was offered online as part of 11 master's-level health programmes at a university in Norway. Collaborative learning in combination with digital teaching tools was the preferred pedagogical approach in the online course. The aim of the study was to describe, explore and discuss how the students collaborated in small groups in an online course to learn. Methods: We performed six focus groups and 13 individual interviews from February 2018 to May 2019, conducting a qualitative case study with a content analysis of the data collected. The participants were master students in the same faculty at a university in Norway. All the included participants had fulfilled the 15 ECTS credit course. Results: Our study revealed that the collaboration in small groups resulted in three different working processes, depending on the students' ability to be flexible and take responsibility for their own and common learning. The three different working processes that emerged from our data were 1. joint responsibility – flexible organization; 2. individual responsibility – flexible organization; and 3. individual responsibility – unorganized. None of the groups changed their working process during their course, even though some experienced their strategy as inadequate. Conclusions: Our study showed that despite similar factors such as context, assignments and student autonomy, the students chose different collaboration strategies to accomplish the online course learning objectives. Each group chose their own working process, but only the strategy 1. joint responsibility – flexible organization seemed to promote collaboration, discussion, and team work to complete the complex assignments in the online course. The result from our study may be helpful in designing and planning future online courses; hence online learning requires a focus on how students collaborate and learn online, to gain knowledge and understanding through group discussion. [ABSTRACT FROM AUTHOR]

This reflective article starts with a personal anecdote, a journey together with Erik Hansen on the Peloponnese to visit an old cypress. He describes Hansen's empathetic working method, which leads to a better understanding of the whole construction process of the temple. An essential part was the building of an evenly ascending slipway on the steep hillside, which could comply with the limits of the tractive force and the load put on the constructed track by the transport of the building blocks and wooden beams. This slipway was used to transport around 2,000 building blocks with a total volume of more than 3,000 m3. The total dragging operation included over 8,000 tons of blue-grey limestone. [ABSTRACT FROM AUTHOR]

The purpose of this article is to examine two main aspects of the control over the working process – technological and legal. In their interconnection they reflect the new means, through which the employers perform their functions on management and control over the workers and employees, and at the same time also is made legal analysis of the applicable and related Labour Law regulations. The reflection of the digitalization on the working legal relations is multidirectional and the authors put the focus on the employers control, presenting through the complex examination some of the advantages of the introduction of different controlling means for digital control and at the same time the related risks. The question of the necessity of new legal frame, guaranteeing the protection of the rights of workers and employees is also discussed. Based on the analysis are made some summaries, formed conclusions and proposals “de lege ferenda” for actualization of the Labour Law legislation in the part of the control.

The complexity of working time management has led in time to the need of using the concept “Full Time Equivalent” (FTE). Whether it is about planning services or physical production, one FTE is the equivalent of eight hours of work per day for an employee in a month. Each activity can be managed through a certain number of FTEs per month. Starting from this unit of measure, whether one has full-time or part-time employees, working time is brought to the same common denominator (for example: one needs 12 FTEs per month). This paper presents a measurement of a working process based on FTEs, which is an increasingly used practice in corporations. It describes the methodology for a particular activity that conducted to a specific time for each step of the entire process of work, and then the required FTEs is calculated according to this data. Since there are differences between the required FTEs according to the actual measurements of the process and the number of FTEs from the previous year according to the workload, possible arguments for these differences are discussed. Finally, there are highlighted the time-consuming steps in order to make the working process more efficient.

The objective of this study was to identify occupational exposure in the work process of nursing professionals, with radiopharmaceuticals marked with 68 Ga in a nuclear medicine service in municipality in the south of Brazil. Nursing professionals who work exclusively in the positron emission tomography/computed tomography participated in the study. The professionals were identified with the pseudonyms alpha and beta. Data collection took place through observation and prescribed documents in national and international regulatory standards, which were defined in four consecutive moments: observation of professionals during the procedure with the radionuclide 68 Ga, application of scripts related to the observed process, occupational dosimetry, and verification of the dose rate in the period from May to August 2019. Exposure increased by 20% with noted decreases in distance between the sources and radiosensitive structures (i.e., the eye lens and thyroid gland), increased exposure time, and improper use of available shielding. After evaluating the routine of nursing professionals and considering the high-energy parameters of 68 Ga, time, distance, shielding, and the high dose rate, it is suggested that the work process should be reevaluated and standardized, paying attention to critical points, as well as not having only the dosimetric reading as an evaluation parameter. [ABSTRACT FROM AUTHOR]

The creation of modern high-powered gas and gas-diesel engines is associated with the solution of two main tasks – the elimination of abnormal combustion and reduction of engine thermal factor. The paper discusses ways to reduce exhaust gas temperatures, methods to eliminate hot-tube ignition and detonation in single fuel gas engines. The ways of reducing exhaust gas temperatures, reducing the thermal factor of diesel injectors (pressure, duration of injection) and detonation issues in two-fuel gas-diesel engines are considered. The results of computational and experimental studies are presented. It is shown that due to the optimization of intake systems, fuel supply and control algorithms it is possible to significantly reduce the thermal stress of gas and gas-diesel engines, while ensuring the achievement of high values of the average effective cycle pressure up to 28 bar and the achievement of high volume power up to 43 kW/l.

The theoretical analysis of the working processes of the slow-moving long-range stage with variant cooling of different sections of the working chamber made it possible to determine the rational range of its cooled zones and the corresponding design parameters of the cooling jacket, which makes it possible to ensure the permissible temperature of the injected gas at minimum overall dimensions and mass

Copyright of Revista de Pesquisa: Cuidado é Fundamental is the property of Revista de Pesquisa: Cuidado e Fundamental Online and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diesel engines used in road transport and other power plants are the sources of environmental pollution. Therefore, it is necessary to search for new approaches to the working process organization that allow reducing emissions of harmful substances in exhaust gases: nitrogen oxides (NOx), carbon oxides (CO), hydrocarbons (THC) and particulate matter (PM). Problem. The most difficult problem to fulfil the standard requirements to the emission of harmful substances in exhausted gases of diesel engines is simultaneous reduction of nitrogen oxides (NOx) and particulate matter (PM), due to the fact that these parameters are inversely related. Goal. The purpose of the research is to improve the ecological and fuel-economic parameters owing to working process improvement, determine the engine rational adjustment parameters: fuel injection pressure; fuel injection advance angle; degree of recirculation of exhaust gases; design parameters: the shape of the combustion chamber and the configuration of the injector nozzle, the controlled exhaust gases recirculation (EGR) over the high pressure circuit with cooling of the bypassed exhaust gas. Methodology. To choose adjusting parameters of the fuel supply system and the EGR, modeling of working process at all characteristic points of the NRSC cycle is carried out. Results. The minimum NOx emission at a different PM level is realized by changing the fuel injection pressure, the fuel injection advance angle and the EGR degree that is in the lower range of the study boundaries. Reduction of specific effective fuel rate at the nominal mode has been obtained due to the used EGR at the level of 8-11%. Originality. Based on the results of the research, the regressive dependencies of the change in the evaluation parameters NOx, PM, ge on the adjusting parameters (fuel injection pressure, the fuel injection advance angle and the EGR degree) which contribute to reducing fuel consumption and decreasing emissions of harmful substances from exhaust gases have been constructed. Practical value. Adjustment parameters which ensure the particulate matter emission corresponding to the level of Stage 4 have been obtained.

This study experimentally confirms the intensification of kerosene combustion in the case where a mixture simulating steam reformation products in a model combustion chamber with a supersonic velocity of the flow at the inlet. It is shown that the used mixture has a higher chemical activity than ethylene. The use of steam reformation products of hydrocarbon or synthetic propellants in schemes with pulse-periodic combustion control increases combustion efficiency without the use of special design solutions for organizing initiation and stable combustion. [ABSTRACT FROM AUTHOR]

Over the past few decades reduction in pollutant emissions has become one of the main directions for further deve- lopment of engine technology. Solution of such problems has led to implementation of catalytic post-treatment systems, new technologies of fuel injection, technology for regulated phases of gas distribution, regulated turbocharger system and, lately, even system for variable compression ratio of engine. Usage of gaseous fuel, in particular gas-diesel process, may be one of the means to reduce air pollution caused by toxic substances and meet growing environmental standards and regulations. In this regard, an analysis of methods for organization of working process for a gas-diesel engine has been conducted in the paper. The paper describes parameters that influence on the nature of gas diesel process, it contains graphics of specific total heat consumption according to ignition portion of diesel fuel and dependence of gas-diesel indices on advance angle for igni-tion portion injection of the diesel fuel. A modern fuel system of gas-diesel engine ГД-243 has been demonstrated in the pa- per. The gas-diesel engine has better environmental characteristics than engines running on diesel fuel or gasoline. According to the European Natural & bio Gas Vehicle Association a significant reduction in emissions is reached at a 50%-substitution level of diesel fuel by gas fuel (methane) and in such a case there is a tendency towards even significant emission decrease. In order to ensure widespread application of gaseous fuel as fuel for gas-diesel process it is necessary to develop a new wor- king process, to improve fuel equipment, to enhance injection strategy and fuel supply control. A method for organization of working process for multi-fuel engine has been proposed on the basis of the performed analysis. An application has been submitted for a patent.

Engine knock has become the prime barrier to significantly improve power density and efficiency of the engines. To further look into the essence of the abnormal combustion, this work studies the working processes of normal combustion and knock combustion under practical engine operating conditions using a three-dimensional computation fluid dynamics (CFD) fluid software CONVERGE (Version 2.3.0, Convergent Science, Inc., Madison, USA). The results show that the tumble in the cylinder is gradually formed with the increase of the valve lift, enhances in the compression stroke and finally is broken due to the extrusion of the piston. The fuel droplets gradually evaporate and move to the intake side under the turbulent and high temperature in the cylinder. During the normal combustion process, the flame propagates faster on the intake side and it facilitates mixture in cylinder combustion. During the knock combustion simulation, the hotspots near the exhaust valve are observed, and the propagating detonation wave caused by multiple hotspots auto-ignition indicates significant effects on knock intensity of in-cylinder pressure. [ABSTRACT FROM AUTHOR]

The claw vacuum pump is regarded as the most potential pump type used as the vacuum system due to its remarkable advantages of oil-free, structure compact and high reliability. During operation, serious gas leakage between two conventional claw rotors occurs and then the pump efficiency decreases. With the aim for reducing gas leakage, a novel pair of gear-claw rotors were proposed, in which a new gear-type structure was generated to produce special twisting clearance between two claw rotors for preventing gas leakage, and then a new claw vacuum pump with high comprehensive performance was developed. A geometric model of the gear-claw rotor was established, and the impact of design parameters on the performance of the proposed rotor was analyzed. Furthermore, the transient flow and pressure distribution of the conventional and the proposed claw vacuum pumps were compared by means of numerical simulations. It is found that the volumetric efficiency and gas leakage velocity between two claw rotors in the conventional claw vacuum pump are 69.5% and 347.665 m/s, respectively; while the volumetric efficiency and gas leakage velocity between two gear-claw rotors in the proposed claw vacuum pump are 77.4% and 274.020 m/s, respectively. Compared with conventional claw rotors, the gas leakage velocity between two gear-claw rotors is reduced by 21.18%, and its volumetric efficiency is increased by 7.9%. The efficiency and sealing performance of the proposed gear-claw vacuum pump are significantly superior to those of the conventional claw pump. • Novel gear-claw rotors for preventing gas leakage were proposed and developed. • Efficiency of the proposed gear-claw vacuum pump was improved. • Optimal geometric parameters of proposed gear-claw rotors were obtained. • Gas leakage flow of the new gear-claw vacuum pump was simulated and predicted. [ABSTRACT FROM AUTHOR]

The topicality of the research is explained by the tendency of using information technologies and their implementation in the process of designing working machines and mechanisms. The possibility of comparing mathematical calculations with the virtual experiment as well as the need for computer modeling in cases where the working process of physical experiment is difficult has been considered in the given work. The consistency and formalization of the computer model of compact loader operating equipment, which makes it possible to identify the basic properties of the object under study (or a whole class) is considered.

The article describes a thermo-gas-dynamic model of small gas turbine engines. The model takes into account the influence of the engine size on the efficiency of work processes in the crucial components. Gas turbine engines are classified according to their size depending on the value of the gas generator mass flow rate corrected by the compressor exit parameters. An important feature of the working process in small gas turbine engines is that hydraulic losses in the flow section increase with the decrease in the engines size due to the increase of the boundary layer relative thickness. The efficiency of the compressor and turbine also decrease because of the increase in relative radial clearances. These factors are taken into account in computer modeling by making allowances for the initial values of compressor efficiency, fuel combustion efficiency, the total pressure loss coefficient and turbine efficiency. The suggested approaches were used to improve computer models of gas turbine engines. It is shown that reducing the engine size results in considerable decrease of the work process optimal parameters and specific parameters. Taking into account the influence of the engine size on the efficiency of its components widens the range of its applicability and improves the adequacy. Thus, the models provide a more adequate solution for the optimization of working process parameters and can be used for conceptual designing of small gas turbine engines.

This article presents the results of statistical modeling using experimental results obtained with an organic fertilizer spreading machine having a spreading device that consists of vertical helical rotors. Exposed statistical models are embodied in functions that connect input parameters, command parameters and output parameters of the process in order to estimate machine qualities and optimize the working process. It also shows global qualitative results, along with the profiling of some research methods on experiment groups characterized by different sets of values of the considered working regime parameters. [ABSTRACT FROM AUTHOR]

The working process of high-pressure SCR (HP-SCR) system is a kind of catalytic reaction process in the high-pressure exhaust flow, which involves urea decomposition reaction, catalytic reduction reaction of NOx and oxidizing reaction of NH3. Based on existing exhaust conditions of marine low-speed diesel engines, computational fluid dynamics (CFD) coupled with the chemical reaction kinetics, the catalytic process, and the working performance of the HP-SCR system were correspondingly studied in this paper. With the optimized scheme of the HP-SCR system, concentration uniformity, linear velocity, and total pressure loss were determined. Likewise, the concentration distribution of NH3, NO, and NO2 were obtained, and the catalytic kinetics of the NOx reduction reaction was analyzed. For the optimized scheme, the concentration of NH3 and the flow uniformity of the catalyst upwind section was met with the design requirements of the HP-SCR system, and the pressure loss of the SCR catalyst layer occupied about 40% of the total pressure loss. With NO, NO2, and NH3 existing together in the exhaust, both the standard SCR reaction and fast SCR reaction are competitive, and they mostly react along the first layer of catalyst. Finally, the weighted average value of the NOx emission behind the HP-SCR system was determined using the ISO8717 test cycle E3, and the value was 2.67 g/kWh, which met with the NOx limited requirement of the IMO Tier III. [ABSTRACT FROM AUTHOR]

Unevenness of working processes in diesel engine cylinders can happen for several reasons. The two most influential factors to this phenomenon, which are related to disturbances in the fuel injection process are: disturbances in terms of the current position (rotation angle) of the crankshaft when the fuel injection in one of the cylinders starts, so-called pre-injection angle, and disturbances in the quantity of fuel that is supplied to individual cylinders during one work cycle, the so-called cycle amounts of fuel. These disturbances are more prominent in classical, mechanical fuel injection systems (high-pressure pump, pump-injector, etc.), and very often can not be prevented during the out engine testing and the fuel injection system adjustments. The simulation of disturbances described under real operating conditions of diesel engines, and expanding the knowledge of their individual and joined impact on the working processes in cylinders, is not at all simple. However, today there are commercial software which have built-in modules based on the proven equations of thermodynamics, combustion theory and the theory of flow, which makes it possible to carry out these simulations by using a computer. One such software is AVL BOOST. The simulation results obtained using this and similar software can be more reliable than simulations in real conditions of the engine, because in the mechanical fuel injection system it is very difficult to quantify the degree of the disturbance which is to be simulated. The given results can be used to develop methods of identifying the impact of described disturbances on the mean indicated pressure of each cylinder, as well as the entire engine, a more accurate assessment of mechanical losses (degree of mechanical utility), etc.

Engine knock has become the prime barrier to significantly improve power density and efficiency of the engines. To further look into the essence of the abnormal combustion, this work studies the working processes of normal combustion and knock combustion under practical engine operating conditions using a three-dimensional computation fluid dynamics (CFD) fluid software CONVERGE (Version 2.3.0, Convergent Science, Inc., Madison, USA). The results show that the tumble in the cylinder is gradually formed with the increase of the valve lift, enhances in the compression stroke and finally is broken due to the extrusion of the piston. The fuel droplets gradually evaporate and move to the intake side under the turbulent and high temperature in the cylinder. During the normal combustion process, the flame propagates faster on the intake side and it facilitates mixture in cylinder combustion. During the knock combustion simulation, the hotspots near the exhaust valve are observed, and the propagating detonation wave caused by multiple hotspots auto-ignition indicates significant effects on knock intensity of in-cylinder pressure.

At gas distribution stations, a large amount of energy of compressed gases is lost. In such cases, the useful power is obtained with the aid of a turboexpander. The problem is that there is a great need for turboexpanders with a capacity of up to 500–700 kW. For these capacities, the turboexpander with the use of classical turbines turns out to be high-speed, complex, expensive, with a payback period that is more than two years. The solution of this problem is seen in the creation of turboexpander installations based on vortex machines. A promising type of vortex expansion machines are side channel machines. Results of studies of vortex hydraulic turbines with side channel showed high values of the efficiency. The goal of this research is study of the working process of vortex expansion machine with side channel by performing a computational experiment in the ANSYS CFX software package. The results of the research showed that the efficiency of vortex expansion machine with side channel is greater than in vortex expansion machine with peripheral channel (real experiment).

The experimental data on change according to speed characteristics of power indicator indexes of the four cylinder pneumatic engine D/S = 76/66 with a slide-valve air distributor at unchangeable temperature of compressed input air is considered.

The paper considers the problems related with the thermodynamic analysis of the conrod-free engine. A mathematical model of the intake system of the conrod-free engine is proposed, which takes into account the kinematics of the slider-crank mechanism. The computational model of the intake system of the engine with the slidercrank mechanism is presented. The model allowed determining dependencies of the mixture temperature in the intake pipeline on the rotation frequency of crankshaft and on the angle of opening of the throttle gate. The total pressure losses in the engine intake system are determined taking into account the kinematics of the slider-crank mechanism. The mathematical model of the intake system of engine allows evaluating the measures aimed at optimizing the engine design and increasing its fuel efficiency. [ABSTRACT FROM AUTHOR]

Multi-process working principle is one of the modern approaches to development of internal combustion engines. By combining the original features of the Otto and Diesel working processes, an improvement of the engine efficiency and ecological characteristics can be achieved. Examples for that are spark ignition engine with stratified charge as well as compression ignition engines with homogeneous charge. The experimental multi-process engine was developed as well as testing methodology, for the basic researches efficiency and ecological characteristics of the Otto/Diesel engine. This paper presents the results of the combination of Otto//Diesel working processes when the engine working with both conventional and bio-fuels. Results of initial tests of Otto/Diesel engine show a high potential to reduce particulate emissions. The investigation has shown certain disadvantages of the engine and the ways for theirs overcoming. [ABSTRACT FROM AUTHOR]

This paper describes a method for multicriteria optimization of parameters for both the engine core and engine family with modeling the engine operation as a part of aircraft system. [ABSTRACT FROM AUTHOR]