Voltage stabilization of a controlled autonomous magnetoelectric generator with a magnetic shunt and permanent magnet excitation

The paper presents the results of testing and research of the characteristics of a controlled autonomous magnetoelectric synchronous generator with a magnetic shunt. Structurally, the studied generator is a modified asynchronous machine in which the rotor is made with permanent magnets and an additional system in the form of a magnetic shunt. By adjusting the winding current of the magnetic shunt, the output voltage of the generator is regulated. The following characteristics were investigated: the no-load characteristic during operation with permanent magnets and when the winding current of the magnetic shunt changes with forward and reverse polarity. Also, the external characteristic for active and active-inductive loads; the control characteristic when the load current changes at a constant generator voltage. Analysis of the obtained characteristics makes it possible to determine the limits of regulation of the external characteristic, which is ≈40 % relative to the main magnetic flux. The obtained regulation depth allows maintaining the stability of the external characteristic for power factors not exceeding 0.9, which is the usual passport value for autonomous power plants based on synchronous generators. Comparison of the data of research conducted on the experimental setup shows sufficient convergence for engineering and practical tasks. The maximum quantitative difference is 9.3 %, which suggests the adequacy of the previously developed mathematical model. The control characteristic, constructed experimentally at constant generator voltage, is the control law of the magnetic shunt winding for the studied generator. The investigated version of a synchronous generator with a magnetic shunt should be used for autonomous power plants, renewable energy systems, and autonomous power supply systems.

Cavitation Flow Simulation and Experiment Research in Inducer

The inducer is a kind of special axial pump, which is widely used in industry communities, such as aerospace delivery systems and medical equipment. Inducer hydraulic performance is impacted sensitively by flow field cavitation. The external characteristic parameters of the turbopump are closely related to the cavitation in the inducer. The generation and changes of the cavitation in the inducer are the root cause of the drop in the turbopump head. The authors first take a low-temperature liquid rocket engine inducer as the research object, bring the numerical calculation and the visual test method to show the law of the generation and change of cavitation in the inducer and its correspondence with the external characteristic parameters of the turbopump, which explain the quantitative correspondence between the cavitation mode of the inducer and the macroscopic external characteristic curves of wheel pumps from a microscopic perspective. The numerical calculation method of cavitation flow field is introduced and the visualization test method is implemented to a proposed platform. The experimental results show that the numerical calculation results are in good agreement with the visualization test results, which indicate that the actual numerical method is practical and feasible for the calculation of the cavitation flow field in inducers. Finally, the pressure fluctuation frequency characteristic is obtained through the experimental and calculation post-process.

Senescence: General aspects about morphophysiology in the process of oral aging

Objective: This study aimed to perform an expository review about the aging process of oral tissues, correlating the information available in the literature to a conceptual and terminological view. For this purpose, a search was performed in the literature with reference to SCIELO, MEDLINE and Health Portals databases. Methods: The methodology used was the bibliographic, an explanatory research, combined with a contextualization of the data, where the main intention was to make science in the scope of qualitative methods and techniques of research. Where the inclusion criteria were availability of the full text of the study, to demonstrate clarity in the methodological detail used and to be available in Portuguese or English. Conclusion: Through the perquirition performed in this study, it was possible to discuss in an enriching way the proposed theme, encompassing several physiological aspects, morphological and external characteristic, while main actors in the process of Oral senescence.

Numerical Research on Performance of High-Speed Partial Emission Pump

The high-speed partial emission pump is a small flow and high-head pump, which has been widely used. To study the main factors affecting the performance of high-speed partial emission pumps, numerical simulation methods were used to calculate the performance parameters of high-speed partial emission pumps with and without inducers, and the external characteristic parameters were verified through comparison test values. The results show that the head of the high-speed partial emission pump with inducer is nearly 15 m higher than that of the high-speed partial emission pump without inducer. Considering the influence of air in the high-speed partial emission pump on the working performance, the two-phase flow with different flow rates, different particle sizes, and different concentrations was calculated, and the different liquid phase distributions, liquid phase velocity vector diagrams, and external characteristic curve were compared. The results show that under the same flow condition, the gas-phase particle diameter has the most severe influence on the external characteristic.

Attributive function of the instrumental case in the dialects of Transcarpathia (noun and adverbial position)

The article is devouted to the attributive function of the instrumental case in the dialects of Transcarpathia region. The article clarifies the structural and semantic features of the attributive in the form of the instrumental case in the dialects of the Transcarpathia. The attributives, which are called signs of individual actions, situations of objective reality, are considered. The functional essence of the attributive creative in the adjective and adverbial positions is highlighted. The purpose of this article is to highlight the formal syntactic features and semantic manifestations of the peripheral zone of attributiveness, namely, the intrinsic attributive with possessive semantics, with the semantics of comparison, adverbial attributives with the semantics of the mode of action in the form of the instrumental case. Attributive syntaxemes in the studied dialects characterize various situations and retain semantic and morphological connections with output words, phrases and sentences. They can be synonymous with nouns in other indirect cases or verb constructions in the forms of subordinate attributive sentences. Their property to convey variable, temporary, situational signs is associated with a specific subject correlation by the attributive in the form of the instrumental case. Achieving this goal involves solving the following tasks: 1) to establish the original semantically elementary sentence that underlies the attributive syntaxeme, the lexical meanings of the supporting and dependent components; 2) find out the functional and semantic meaning of the attributive syntaxeme. Within the framework of the attributive components in the form of the instrumental case, groups distinguished, among which: the names of the characteristic features of a person's appearance, the names of the methods of production processes, the names of the external characteristics of movement in space, parts of clothing, shoes, parts of objects household items, characteristics as a result of an action, the name of a generalized characteristic of an action and a situation as a whole, an external characteristic of a person or animal, the name of an external characteristic of a plant, the name of a qualitative characteristic of an individual action, and the like.

Efficiency of direct current catenary distance protection with adaptation to traction mode

The paper considers efficiency of distance protection with adaptation to rectifier converters of traction substations with different number of pulsations. The authors have revealed the influence of inclination of the external characteristic of rectifier converters on total efficiency of protection. They have also introduced notions for indicators of efficiency of distance protection with adaptation: сoefficient that determines the increase ratio of peak operating current; coefficient that determines the decrease ratio of minimal voltage on traction substation buses; coefficient that determines the increase ratio of maximal peak power of catenary feeder realized by 3.3 kV direct current. The paper presents methods of their calculation.

Analytical Solutions for Bending of Nanoscaled Bars Based on Eringen’s Nonlocal Differential Law

The one-dimensional nanoscaled bar is commonly seen in current nanodevices, and it plays a significant role in nanoelectromechanical system (NEMS) and related nanotechnology. Motivated by this, the paper is concerned with the bending and stability of a nanoscaled bar especially a flexible bar subjected to vertical concentrated, vertical linearly distributed, and horizontal concentrated forces simultaneously. The theoretical model is developed by employing Eringen’s nonlocal differential law. Hence, the nonlocal differential constitutions in terms of stress and bending moment at a nanoscale are applied to the classical equilibrium formulation in order to construct the nonlocal constitutive model and then determine the analytical solutions for bending of such a nanoscale bar. Subsequently, the effect of a nonlocal scale on the midpoint deflections and internal forces is shown numerically, and the internal and external characteristic length scales are also examined. It is revealed that the capacity of resisting compression decreases with increasing the nonlocal effect since the internal characteristic scale cannot be neglected by comparing with the external characteristic scale. There exists a threshold value for bending stiffness. Both the midpoint deflection and bending moment vary monotonously when the material bending stiffness exceeds the threshold value, while the mechanical quantities fluctuate when the bending stiffness is less than its threshold value, namely, for a flexible nanoscaled bar. Accordingly, two different kinds of nonlocal predictions and the related disputes are resolved in the context of Eringen’s nonlocal differential law. The work is expected to be useful for the design, application, and optimization of nanoscaled bars sustaining bending with linear vertical and horizontal forces.

External characteristic analysis and stator parameter optimization for a torque converter

The performance of a flattened hydraulic torque converter is optimized with orthogonal experiment and response surface method, considering parameters of its stator blade, defined with nonuniform rotational B-splines. The optimization model, with maximum of the stalling torque ratio as an objective, is determined through an external characteristic statistical analysis under the new European Driving Cycle condition. The optimization results show that the stall torque ratio is increased by 10.83%, while the highest efficiency is above 84%.