Теория мультифизического подобия гидробионтов

Based on similarity theory, the similarity criterion of simulation test was derived and the experimental apparatus was established in accordance with the similarity criterion. The similarity criterion deduced by the dimensional theory has a much wider applicability than which deduced by differential physical equations. The experiment device of bottom hole assembly included absorber was designed in proportion of 1 to 10 according to the actual bottom hole assembly. Through the experiment device, the vibration of the drill string with absorber could be obviously observed. Moreover, analysis of the absorber performance experiments under the conditions of different WOB, speed, installation location and elastic stiffness could be carried out. Key words: Drill string vibration; Similarity criterion; Simulation; Experiment

A kinetic analysis of multistep electrochemical reactions involving partial diffusion transport of intermediates between the near-electrode layer and the bulk electrolyte is performed within theory of generalized variables (theory of similarity). Dimensionless complexes (similarity criteria) that characterize such reactions are obtained, and their values corresponding to the transport of intermediates are determined.

Abstrac. The article presents a theoretical approach to determining the main performance parameters of a forced-action three-shaft concrete mixer based on the application of similarity theory. A system of dimensionless similarity criteria has been developed, which enables the transfer from a basic laboratory model to a full-scale industrial machine. This method is proposed as a means of optimizing the design and operating parameters of concrete mixers for the preparation of stiff and low-mobility concrete mixes without costly full-scale experimentation. Problem. The intensification of technological processes in modern construction requires highly efficient and reliable mixing equipment. Determining the performance characteristics of a real-scale concrete mixer through experimentation can be resource-intensive and time-consuming. Therefore, the need arises for a universal method that allows predicting the operational parameters of the equipment at the design stage. Goal The goal of the study is to justify the applicability of similarity criteria for calculating the productivity and drive power of a three-shaft forced concrete mixer. The method aims to provide a mathematically grounded alternative to experimental determination by using a scaling approach based on geometric and dynamic similarity. Methodology. The study uses the principles of dimensional analysis and the theory of similarity, particularly Buckingham’s π-theorem, to derive a set of key similarity criteria. These criteria describe the interactions between the working elements of the mixer and the concrete mixture, taking into account density, elasticity, surface activity, gravitational and inertial forces. Using these dimensionless numbers, transition coefficients between the basic model and the full-scale machine were calculated. Based on them, formulas for determining productivity and required drive power were derived. Results. The research resulted in a set of validated equations for calculating the main performance indicators of a full-scale mixer based on known parameters of a prototype or laboratory model. The system of similarity criteria allows taking into account the influence of design and operating factors without direct testing. It was shown that the three-shaft design enables three-circuit material flow and increased mixing intensity across the entire volume. The proposed approach is recommended for use in the design of energy-efficient and productive mixers for construction applications.

This review investigates the performance and the feasibility of the integration of an algal reactor in recirculating aquaculture systems (RAS). The number of studies related to this topic is limited, despite the apparent benefit of algae that can assimilate part of the inorganic waste in RAS. We identified two major challenges related to algal integration in RAS: first, the practical feasibility for improving nitrogen removal performance by algae in RAS; second, the economic feasibility of integrating an algal reactor in RAS. The main factors that determine high algal nitrogen removal rates are light and hydraulic retention time (HRT). Besides these factors, nitrogen-loading rates and RAS configuration could be important to ensure algal performance in nitrogen removal. Since nitrogen removal rate by algae is determined by HRT, this will affect the size (area or volume) of the algal reactor due to the time required for nutrient uptake by algae and large surface area needed to capture enough light. Constraints related to design, space, light capture, and reactor management could incur additional cost for aquaculture production. However, the increased purification of RAS wastewater could reduce the cost of water discharge in places where this is subject to levees. We believe that an improved understanding of how to manage the algal reactor and technological advancement of culturing algae, such as improved algal reactor design and low-cost artificial light, will increase the practical and economic feasibility of algal integration in RAS, thus improving the potential of mass cultivation of algae in RAS.

Water quality (WQ) is the paramount element influencing fish well-being and productivity in aquaculture farming systems. The survival of fish is mostly reliant on the aquatic environment that sustains them. Consequently, it is vital to possess a comprehensive awareness of the WQ prerequisites for the fish. Optimal WQ in Recirculating Aquaculture Systems (RAS) is essential for cultivating species' effective development and survival. Currently, no laws dictate the parameters to be monitored in RAS, leaving each farmer to choose which parameters to monitor. Historically, WQ measurements have been assessed at certain intervals using portable sensors and laboratory tests, which may be labor-intensive. This study proposes an Effective Surveillance of Water Quality (ESWQ) in RAS using Intelligent Biosensors (IBS). This study examines essential water characteristics (temperature, pH, calcium, magnesium, and Dissolved Oxygen (DO)) for RAS and evaluates the IBS for monitoring these factors. This research provides a potential solution for RAS using IBS, which would enhance ESWQ aspects, facilitate data-driven decision-making, and enable more rapid adaptation to evolving RAS situations.

The article highlighted the necessity to determine the dependence of maximum pressure of wheel propellers on the parameters of tractor, wheel and the soil characteristics, for calculation the crop energy, which was lost due to the negative impact of the tractor wheels on the soil. Using the theory of similarity, the criteria of similarity was defined and several options of dependence of maximum pressure of tractor wheels on the soil were identified, taking into account various factors. The use of the similarity theory helped to reduce the number of factors for the design of experiments while maintaining the informative value of the title of the regression equation.

Design and operation analysis of electrical machines can be performed by using either full-size or different scale models. This paper deals with the development of electromagnetic field analysis and electrical circuit models of geometrically similar electrical machines based on similarity theory and scale factors. The proposed methodology can be exploited for the design of micro and nano scale electrical machines used in medical and other applications, as it allows the construction of up-scale models more suitable for laboratory measurements.

This paper presents the design of geometrically similar switched reluctance machines based on similarity theory and scale factors techniques. The fundamental theory for the development of the proposed methodology is described. The proposed methodology is used for the design of a particular 21.6 W three phase 6/4 pole switched reluctance motor, which can be used as a special electrical machine (pump’s driving motor) in an artificial heart. In addition, a sensitivity analysis using FEM was performed in order to confirm the accuracy of the proposed method.

Environmental impacts of genetic improvement of growth rate and feed conversion ratio in fish farming under rearing density and nitrogen output limitations

Recirculated aquaculture systems (RAS) have increased in preponderance in producing fish and shrimp protein. Yet, the economic sustainability of constraining RAS from negatively impacting aquatic ecosystems remains challenging. The future of RAS agriculture will eventually be settled by the relationship between water treatment costs and the impacts on downstream ecosystems. We present a user-friendly simulator of the costs of the treatment of water from RAS farms. This open-source freeware accounts for consumables and energy needed to protect the fish stock from ammonia and nitrite distress, as well as the cost of effluent treatments for specific nitrogen emission targets. This simulation platform uses information inflows about a RAS farm's layout, filters’ performance, toxicity limits, and operational costs. It monitors the budget of water, ammonium, ammonia, nitrite, and nitrate, as well as the cumulative costs of management decisions for controlling nitrogen inorganics. In combination with local environmental regulations, such an assessment is essential for making business projections that correspond with acceptable impacts on downstream ecosystems. This simulator helps determine whether a specific RAS farm is both financially sound and environmentally sustainable. Such analyses are key to constraining pollution in the surrounding ecosystems and contributing to the conservation of biodiversity.

In previous papers (1955–1957) a theory of biological similarity was established, assuming that the limits are the mechanical and the electrodynamical similarity criteria. The range of this theory lies between the coefficient of the time exponent (γ) for mechanical (0.5γ) and electrodynamical (1.0γ) similarities, being the mode 0.93γ. Moreover, for certain functions this restricted theoretical range should be extended to the hydrodynamical similarity criterion (2γ), so that the dimensionless numbers commonly used in Physics (Reynolds, Froude, Weber, etc.) can be included within the total range (0.5–2γ) of biological similarities. From dimensional analysis of physiological, functions it was possible to obtain, by means of dimensional and solution matrices, a group of “nondimensional numbers” by applying Buckingham's Pi-theorem. Nevertheless, only if a single similarity criterion was applied, the residual weight exponent was exactly zero; in all other instances the weight exponent was not zero, due to the existence of a range for biological similarities and to the statistical meaning of exponent (b) of the allometric equations. From the similarity criteria “invariant numbers” can be obtained, by means of which it is possible to establish correlations between numerous morphological and physiological characteristics of a particular system (circulation, respiration, metabolism, etc.).

A practical extension of the similarity and dimensional theory to the case of several similarity parameters is proposed. On this basis, for galaxies an explanation is given for the empirical correlations noticed in the last quarter of the 20th century: the Tully–Fisher relation, the concept of a fundamental plane, etc. For galaxies, apart from the virial, there is another similarity parameter whose choice is arbitrary. Here, it is introduced in the simplest form for an empirical determination:Π1 = U 0/U d, U 0 is the observed velocity, the scale U d = (GL)1/5, where L is the object luminosity, G is the gravitational constant.

Research on the evaluation criteria for safety state of train operation based on the scaled model

Polyculture offers an alternative to monoculture in recirculated aquaculture systems (RAS). Nevertheless, RAS polyculture can potentially result in beneficial as well as detrimental consequences. This places a premium on assessing consequences of a particular polyculture prior to its implementation in farming production. In fish aquaculture, most of previous assessments of polyculture consequences have been carried out through multi-trait approach by analysing independently species traits related to a single biological function. Yet, polyculture can impact many biological functions and the overall consequences are the result of multiple interactions from different functions. Therefore, an integrative analysis is required to synthesise the polyculture consequences at the multi-trait levels. Here we propose a multi-trait evaluation framework (i.e. considering traits related to multiple functions), for the polyculture consequence assessment. We analyse this framework through multivariate analysis prior integrating results for each trait. As test case, we used pikeperch (Sander lucioperca), reared in monoculture and in polyculture with European perch (Perca fluviatilis), common carp (Cyprinus carpio) and black-bass (Micropterus salmoides). Our results revealed the importance of applying multi-trait framework to obtain a reliable assessment of fish polycultures. The divergence that might occur in the expression of some traits in the same polyculture has been highlighted to support this argument. Through the integration method, it was possible to find the suitable combination(s) of fish and to exclude the unsuitable ones. For future researches, we suggest to support the multi-trait assessment by weighting the traits involved in the multivariate analysis.

BackgroundThe key limiting factor for recirculating aquaculture systems (RAS) is maintaining good water quality, which requires keeping the system free of bacterial pathogens. In this study, we investigated the potential of CaviPlasma water treatment technology for the industrial-scale disinfection of RAS water.MethodsWe focused on the remediation of model suspensions containing Aeromonas salmonicida, Aeromonas hydrophila, and Flavobacterium psychrophilum, which are important fish disease causative agents that represent significant health risks for reared fish. The CaviPlasma technology utilized is based on advanced oxidation processes induced by plasma discharge in fast-flowing liquids, synergized with the hydromechanical effects of cavitation.ResultsOur results demonstrated strong biocidal efficiency of CaviPlasma water treatment without chemical or medical additives. F. psychrophilum was completely eliminated immediately after treatment, even at the lowest plasma dose (8.4 kJ/L). Aeromonads displayed slightly higher resistance; instant elimination of aeromonads was achieved with a plasma dose of 25.2 kJ/L, or 33.6 kJ/L. However, during post-treatment incubation, the concentration of live aeromonads gradually decreased to zero, even at the lowest plasma dose.ConclusionsOur pilot study revealed that CaviPlasma technology is a promising sanitization method with potential for use in recirculation aquaculture systems (RAS). It offers approximately m3/h treatment performance and the potential to greatly limit the environmental burden and long-term side effects, such as acquired bacterial resistance due to persistent chemical residues associated with common sanitization technologies that utilize antibiotics or chemical treatment of RAS.