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Torrefaction is considered as a method for producing biofuels with improved characteristics compared to those of the “raw” biomass (higher calorific value, moisture resistance, better grindability). The torrefaction process is an endothermic process that is usually carried out in a gaseous atmosphere in the absence of oxygen. To reduce the required heat input, it is proposed to employ the oxidative torrefaction and conduct the process in a fluidized bed agitated with flue gases containing less than 6% oxygen. Preliminary studies of the oxidative torrefaction of sunflower husks, including thermogravimetric analysis of the treated material, have shown that the heat treatment time for the biomass should be at least 5 min. A fluidized bed is a reactor with ideal mixing of the treated material where uniform treatment of raw material particles cannot generally be attained. To overcome this disadvantage of the fluidization technique and achieve the required residence time for biomass in a fluidized bed during a continuous torrefaction process, it was proposed to equip a torrefaction reactor with a series of vertical baffles spaced at 50 mm. These baffles induce a loop-like flow of the processed biomass from the inlet to the outlet of the reactor. To investigate the residence time for husk particles in the reactor, a tracer, which was colored to husk particles' color with a water-soluble dye which did not change the weight and size of the particles, was injected into the bed of uncolored particles. Tracer samples were taken every 30 s at the outlet of the reactor and were analyzed using a special procedure to determine the fraction of colored particles in each sample. This enabled us to gauge the time during which the colored particles injected into the fluidized bed reached the point of their discharge from the bed. Studies performed in a “cold” model of the reactor showed that a series of vertical baffles in the bed can provide the required residence time for biomass in a reactor including commercial reactors. Plates can provide the necessary biomass residence time in the reactor.

The present article is to select the key parameters of a shunt active filter in the conditions of centralized and distributed power supply systems. The main equations which reflect the dependences of shunt active filter key parameters with network and load characteristics are presented. A mathematical model of a generalized industrial electric network with a variable value of internal impedance with a nonlinear load and shunt active filter was developed by means of the Matlab Simulink software environment. During simulation the generalized dependences of shunt active filter key parameters from the value of internal network impedance were obtained which allow to select and properly tune the mentioned filter key parameters according to the power supply mode defined by the type of a source: centralized or distributed. The obtained results also allow to maintain the required level of power quality and electromagnetic compatibility by means of a shunt active filter during emergency power supply modes when switching from a centralized to a distributed power supply source.

The paper investigates the local thickness distribution of a wall liquid film in a curvilinear channel. The research technique on experimental water-air stand with a curvilinear working channel is described. The results of measurements of the local thickness of the liquid film on the upper and lower walls of the channel for two flow velocities are obtained at various flow rates. © Published under licence by IOP Publishing Ltd. This work was supported by the grant Russian Foundation for Basic Research No. 17–38–50069.

Introduction. The article presents an analysis of researches on the operation of public transport vehicles with an electric drive. Electric buses have been tested in megacities, and despite the advantages, problems were identi- fied both in the selection of the charging type, technological features and with the availability and operation of the charging infrastructure. The operation process is associated with a number of technical restrictions, which in prac- tice make it difficult to select routes for the electric bus operation. The aim of the study is to develop an algorithm for selecting a rational regular urban route for the electric bus operation and to test it on the example of the route network of Tyumen.Materials and methods. A structural diagram of the factors influencing the selection of the route for the electric bus operation has been formed. As a result of processing expert assessments, the most significant factors were identified. The diagram of the interconnections of these factors is identified and limitations for the algorithm are for- mulated based on the theory of systems analysis. The algorithm for selecting the rational regular urban route for the electric bus operation has been developed. It enables creating the simulation model for selecting a rational regular urban route for the operation of an electric bus.Results. The diagram of factors influencing the selection of a rational regular urban route for the operation of an electric bus, taking into account their mutual relations, has been formed. The algorithm and simulation model for se- lecting a rational regular urban route for the operation of an electric bus has been developed. Several urban routes in Tyumen were assessed for the rationality of the introduction of electric buses.Discussion and conclusions. Evaluation of five regular urban routes in Tyumen using the developed algorithm and the simulation model revealed three rational routes, and also showed the inefficiency of the other two. It due to the discrepancy between the duration of the charging session and breaks in operation, as well as the insufficient charge level of the traction battery to ensure the required autonomous movement of the vehicle. In the course of the continuation of these studies, the developed algorithm will be supplemented with the stage of economic assess- ment of routes for the operation of electric buses.

Abstract An ideal tracker which follows the sun both north-south and east-west is designed and constructed. It is suitable for mounting a linear concentrator, focusing parabolic concentrator or photovoltaic array of aperture area 2 m2. The apparatus is built with two axes equational mount and controlled by a microprocessor system. The tracking is carried out by utilizing the astronomical coordinates of the sun. As such the present system gives improved tracking capability over the conventional sensor controlled tracker systems. The performance of the tracking system was studied with photovoltaic array mounted on it and tracking error of less than one degree was achieved. This tracking error can be reduced further by proper software.

The research deals with the issue of slums, urban sprawl on agriculture land and its impact on the city of Baghdad. This topic needs close attention because it has become a problem facing the city of Baghdad through recruiting agricultural lands and converting them to residential homes in addition to the transgression on the state lands and building abuses. This research deals with the causes of slums, irregular urban sprawl and risks of excesses on land uses of land in Baghdad. In this research, we try to know the extent to which these problems have affected the city of Baghdad. The research methodology based on the descriptive methodology to clarify the factors affecting urban sprawl at the expense of agricultural land, using studies in government and service institutions and images from satellites to clarify the size of urban sprawl over periods after the 2003 war. Finally, a conclusion and future solutions were set to solve these problems.

Mining and mineral processing industry adversely affects ecosystems and communities in nearby areas, including high freshwater consumption and scarcity. That is why the emerging global trend is to use sea water in flotation to recover valuable minerals from finely disseminated base metals ores. Recent studies investigate sea water flotation of copper, molybdenum, nickel sulphides and pyrite, while flotation of sphalerite, the main valuable mineral for zinc production, remains uncovered. This paper examines the feasibility of sphalerite flotation by conventional collectors in artificial sea water using a bubble-particles technique and frothless flotation tests. Potassium isopropyl xanthate (PIPX) and sodium isopropyl dithiophosphate (SIDTP) were used as collectors, and copper sulphate was introduced as the activator, while zinc sulphate and sodium sulphide were used as depressants. We examined the most common size fractions of sphalerite: medium (−74 + 44 μm) and fines (−44 μm). The findings showed the feasibility of sphalerite flotation in artificial sea water. We also established correlations between the rate of bubble-particle attachment and the sphalerite flotation recovery resulting in the growth of flotation recovery with the increase of the bubble-particle attachment rate. The results can be used as guidelines in choosing flotation reagents for sphalerite flotation in sea water. Another practical application of the results is the potential for sustainable development of the industrial sector, ecosystems and societies due to the replacement of fresh water by sea water, although further technological and environmental studies are required.

Technical operation of lifting and transport equipment is one of the key problems of ports and terminals. The functions of technical operation include maintenance and repair of lifting and transport equipment. The imperfection of the maintenance and repair system leads to downtime of lifting and transport equipment, which affects the cost of loading and unloading operations. The main requirements for technical operation are to ensure the quality and speed of loading and unloading operations with minimal operating costs. One of the indicators for assessing the quality of technical operation is the coefficient of technical readiness, which shows that the probability that the lifting and transport equipment will be in a working state at any time, except for periods in which operation is not provided. These periods include the time when the lifting and transport equipment is being maintained and repaired. Technical operation strategy is selected based on the technical readiness coefficient.