Structural Subsystems Research Articles

Electrical power management and optimization with nonlinear energy harvesting structures

In recent years, great advances in understanding the opportunities for nonlinear vibration energy harvesting systems have been achieved giving attention to either the structural or electrical subsystems. Yet, a notable disconnect appears in the knowledge on optimal means to integrate nonlinear energy harvesting structures with effective nonlinear rectifying and power management circuits for practical applications. Motivated to fill this knowledge gap, this research employs impedance principles to investigate power optimization strategies for a nonlinear vibration energy harvester interfaced with a bridge rectifier and a buck-boost converter. The frequency and amplitude dependence of the internal impedance of the harvester structure challenges the conventional impedance matching concepts. Instead, a system-level optimization strategy is established and validated through simulations and experiments. Through careful studies, the means to optimize the electrical power with partial information of the electrical load is revealed and verified in comparison to the full analysis. These results suggest that future study and implementation of optimal nonlinear energy harvesting systems may find effective guidance through power flow concepts built on linear theories despite the presence of nonlinearities in structures and circuits.

МЕТОДИЧНА СИСТЕМА ЯК ЗАСІБ ФОРМУВАННЯ ПСИХОЛОГО-ПЕДАГОГІЧНОЇ КОМПЕТЕНТНОСТІ МАЙБУТНІХ ОФІЦЕРІВ ДЕРЖАВНОЇ ПРИКОРДОННОЇ СЛУЖБИ УКРАЇНИ

Nowaday demands the high-level of professional competence of border guard officers, which includes the psychological and pedagogical competence. Formation of psychological and pedagogical competence begins during studying at a departmental institution of higher education and implies the implementation of a methodical system in the educational process that would contribute to the formation and development of the future border guard officer. The urgent issues are the development of a methodical system for the formation of psychological and pedagogical competence of this category of future specialists. The article gives an account of the goals, tasks, structure, stages, content and completeness of each structural subsystem of the author’s methodical system for the formation of psychological and pedagogical competence of future border guard officers. In the article the methodical system is represented as a set of three structural subsystems: target, informative and procedural-organizational. Each subsystem has its constituent elements, hierarchical dependencies, pursues certain goals and contains internal connections. On the basis of the analysis, generalization and systematization of the research material in the article, a graphical interpretation of the developed methodical system is presented. Implementation of the proposed methodical system into the educational process is possible only if a favorable learning environment is created which has high cognitive motivation, creative orientation, qualitative methodical and scientific-methodical preparation of pedagogical workers, implementation of interdisciplinary connections, innovative pedagogical approach based on the application of active teaching methods, a favorable atmosphere for the formation of psychologically and pedagogically important qualities of cadets, improvement of the teacher’s skills, effective targeted influence and pedagogical interaction with cadets, aspiration of future officers-border guards for professional growth and readiness to solve the psychological and pedagogical tasks of future professional activity. The presented methodical system became the central link of the theoretical model of formation of the investigated competence. The next step will be a description of the method of introducing the proposed methodical system into the educational process of the Academy of the State Border Guard Service of Ukraine.

Resonances of the Spatial Distribution of Dislocations upon Interaction with the Structural Order Parameter

The interaction of a structural subsystem with dislocations under the superposition of an elastic torsion strain and an additional uniaxial spatially nonuniform time-constant pressure is studied. The analysis is carried out within of Landau’s phenomenological theory with refusal of the approximation of constant magnitudes of irreducible vectors. The rise of spatial resonances of the dislocation density in these conditions is shown.

Magnetocaloric Effect and Magnetostriction in a Ni49.3Mn40.4In10.3 Heusler Alloy in AC Magnetic Fields

The magnetocaloric effect (MCE) and the magnetostriction in the Ni49.3Mn40.4In10.3 Heusler alloy have been measured in ac magnetic fields to 8 T. It is shown that the contributions of the magnetic and structural subsystems to MCE have opposite signs; in this case, the contribution of the magnetic subsystem is dominant. The anomalous temperature dependence of the magnetostriction during the magnetostructural phase transition (PT) is explained by competition of the processes of growing austenite phase nuclei and the striction processes in them.

Структурная надежность и методы повышения ресурса газотурбинных двигателей на основе обеспечения функционально-ориентированных свойств

In the paper presented there is carried out an analysis of peculiarities in the operation of structural elements and subsystems of gas turbine engine (GTE). A GTE structural reliability is investigated which is defined at the stage of aircraft engine design. There are shown structural logistic formulae of aircraft engine reliability. In the work there is offered a general approach to the life increase of GTE structural elements on the basis of functionally-directed properties. Basic principles for the support of functionally-directed properties of the GTE element base are shown. The ways to ensure a specified rated or limit GTE life on the basis of functionally-directed properties of elements are shown.

Магнитокалорический эффект и магнитострикция в сплаве Гейслера Ni-=SUB=-49.3-=/SUB=-Mn-=SUB=-40.4-=/SUB=-In-=SUB=-10.3-=/SUB=- в переменных магнитных полях

AbstractThe magnetocaloric effect (MCE) and the magnetostriction in the Ni_49.3Mn_40.4In_10.3 Heusler alloy have been measured in ac magnetic fields to 8 T. It is shown that the contributions of the magnetic and structural subsystems to MCE have opposite signs; in this case, the contribution of the magnetic subsystem is dominant. The anomalous temperature dependence of the magnetostriction during the magnetostructural phase transition (PT) is explained by competition of the processes of growing austenite phase nuclei and the striction processes in them.

Резонансы пространственного распределения дислокаций при взаимодействии со структурным параметром порядка

AbstractThe interaction of a structural subsystem with dislocations under the superposition of an elastic torsion strain and an additional uniaxial spatially nonuniform time-constant pressure is studied. The analysis is carried out within of Landau’s phenomenological theory with refusal of the approximation of constant magnitudes of irreducible vectors. The rise of spatial resonances of the dislocation density in these conditions is shown.

Computational Method of the Interior Aerodynamic Noise of the High-speed Train

The computational method of interior aerodynamic noise of the high-speed train was proposed based on the large eddy simulation (LES) and statistical energy analysis (SEA). Based on the SEA theory, the computation model of the interior aerodynamic noise was established, which included 422 car-body structural subsystems and 170 interior acoustic cavity subsystems. The fluctuating pressure spectrums on the car-body structural subsystems were obtained by the LES, and then the interior aerodynamic noise of the high-speed train was computed and analyzed. Computational results show that the sound pressure level of the drive’s cab cavity and passenger compartment cavity has low frequency characteristics for the linerweighted sound pressure level and has broadband characteristics for the A-weighted sound pressure level. For the A-weighted sound pressure level, the sound energy of the drive’s cab cavity is mainly distributed between 100~2000Hz, the sound energy of the passenger compartment cavity is mainly distributed between 50~2000Hz. The sound pressure level of the interior aerodynamic noise can be reduced for every frequency by improving interior sound absorption performance and increasing the damping of the car-body plate.

Dynamic characteristics of multifunctional structure for spacecraft

The minimum cost is an important aspect of the spacecraft design. A proposed approach is the multifunctional structure technology, which fully integrates subassemblies and performs both structural and other functions for spacecraft. By combining the structural and functional subsystems into a single unit, the mass and volume savings can be realized. In order to investigate the dynamical properties of the multifunctional structure, which contains viscoelastic components, sine-sweep tests and random vibrations are carried out in present paper. The experimental results show that the multifunctional structure could survive the vibration environment. The first resonance frequency decreases with increment of the testing levels, and the base frequency of the multifunctional structure is larger than 100 Hz for all tested loading cases, meeting the frequency requirement for most spacecraft platforms. The multifunctional structure in this paper has successfully combined the structural and battery function, indicating potential for future lightweight and cost-saving spacecraft application.

Effect of dislocations on the structural order parameter in a crystal upon torsional strain

The interaction of the structural subsystem with dislocations upon applying an elastic torsional strain has been studied. The consideration is performed in the terms of the Landau phenomenological theory with the refusal from the approximation that the irreducible vector magnitudes are constant. It is shown that additional spatial amplitude and frequency oscillations related to the change in the magnitudes of the structural order parameter and the dislocation density appear.

Flutter Analysis of Propfan–Open Rotors

This work aims at showing the importance of flutter predictions in the preliminary design of propfan–open rotors. Both single rotating propellers and contrarotating open rotors are investigated. The related structural subsystems are modeled through finite element analyses; the aerodynamic subsystems exploit a finite volume, full potential formulation suitable for unsteady transonic flows. An ad hoc technique is developed for simulating the flowfield around a contrarotating open rotor configuration. The effectiveness of the proposed aeroelastic analysis is successfully assessed for single propellers through comparisons with reference numerical and experimental data available in the literature, as well as against Euler flow-based solutions. The results for contrarotating open rotors cannot be validated because of the lack of corresponding open-literature data.

11.26: The seismic design of a building having a dual type structural system in Romania

ABSTRACTThe March 4, 1977 earthquake was the last major seismic event that struck Romania. 1,600 persons were killed, over 11,000 were injured, and 33,000 buildings collapsed or were severely damaged. The great majority of these injuries were in masonry and reinforced concrete buildings. The few existing steel structures behaved very well during the earthquake, excepting the situation when inadequate structural concepts were met. Even if the number of steel buildings was not so high, steel was used especially for long span roofs of industrial buildings. Starting with that period, the design practice proved that steel is an excellent material for seismic‐resistant structures thanks to its performance in terms of strength and ductility. The bulk of the paper consists in presenting the design of a dual type structural system having in the horizontal plane the shape of the letter “Y” and in the vertical plane two basements, a ground floor and 14 stories. Trying to realize a building virtually immune to earthquake action the superstructure of the building, of composite type, was conceived to have two different parts: (a) a reinforced concrete structural subsystem formed by the three structural cores placed in the peaks of the equilateral triangle, their main role being that of assuring the lateral strength of the building to the seismic loads; (b) a steel structural subsystem, having a structural role mainly towards the gravity loads. The steel structural subsystem is placed in the central zone of the building and is connected to the three reinforced concrete cores placed in the peaks of the equilateral triangle. It consists of three moment resisting frames and composite type floor structures. The paper also contains information about the results of some in‐situ dynamic investigations performed after each stage during the construction, in order to validate the structural models of analysis and the contribution of the steel structural subsystem on the overall dynamic characteristics of the building.

On Using Ilities of Non-Functional Properties for Subsystems and Components

The use of ilities for systems engineering of subsystems and components is investigated. Prior work on ilities has emphasized or restricted their application to system level, non-functional properties. The premise of this work is that ilities can be applied with benefit, and in some cases out of necessity, to lower levels of systems as well. The veracity of this premise is established by providing examples that demonstrate how some ilities are passed and used as a non-functional property of electrical and structural subsystems in aircraft. It is further demonstrated that flowing ilities down to the subsystem level is not only a useful practice for systems engineers, it can also be an essential step to ensure that customer needs are actually met by the system under design or service. Systems engineers often lack the detailed knowledge of the subsystems or components required to translate ilities into functional requirements. Thus, the system ilities are passed down and translated from non-functional to functional requirements by subject matter experts. We first discuss the definition, characteristics and scope of ilities. Then, we formulate the application of ilities at a subsystem level. Next, we show aircraft engineering examples for ilities applications. The application process is formalized with diagrams, and ilities’ relation to system architecture engineering is discussed. The work concludes with a summary and suggestions for future work.

Spatial resonance in ferromagnetics

Phenomenological Landau theory is used to study an interaction between structural and magnetic subsystems in a crystal in the vicinity of phase-transition lines. It is demonstrated that the twist-induced severe plastic deformation results in a forced onset of inhomogeneous distribution in the magnetic subsystem. A nonsinusoidal spatial modulation of magnetic and structural order parameter moduli is found to arise near the lines of magnetic or structural phase transition. The obtained results permit to construct various distributions of ferromagnetic vector in crystals under twist-induced severe plastic deformation.

Trade and Investment in the Global Economy

We develop a dynamic multi-country trade model with foreign direct investment (FDI) in the form of non-rival technology capital. The model nests structural gravity subsystems for FDI and trade, with accumulation/decumulation of phyisical and technology capital in transition to the steady state. The empirical importance of the FDI channel is demonstrated comparing actual aggregate cross-section data for 89 countries in 2011 to a hypothetical world without FDI. The gains from FDI amount to 9% of world’s welfare and to 11% of world’s trade, unevenly distributed among winners and losers. Net exports of FDI substitute for export trade in the results.

Sound Radiation Characteristics of a Rectangular Duct with Flexible Walls

Acoustic breakout noise is predominant in flexible rectangular ducts. The study of the sound radiated from the thin flexible rectangular duct walls helps in understanding breakout noise. The current paper describes an analytical model, to predict the sound radiation characteristics like total radiated sound power level, modal radiation efficiency, and directivity of the radiated sound from the duct walls. The analytical model is developed based on an equivalent plate model of the rectangular duct. This model has considered the coupled and uncoupled behaviour of both acoustic and structural subsystems. The proposed analytical model results are validated using finite element method (FEM) and boundary element method (BEM). Duct acoustic and structural modes are analysed to understand the sound radiation behaviour of a duct and its equivalence with monopole and dipole sources. The most efficient radiating modes are identified by vibration displacement of the duct walls and for these the radiation efficiencies have been calculated. The calculated modal radiation efficiencies of a duct compared to a simple rectangular plate indicate similar radiation characteristics.

Structural health monitoring system for Sutong Cable-stayed Bridge

Structural Health Monitoring System (SHMS) works as an efficient platform for monitoring the health status and performance deterioration of engineering structures during long-term service periods. The objective of its installation is to provide reasonable suggestions for structural maintenance and management, and therefore ensure the structural safety based on the information extracted from the real-time measured data. In this paper, the SHMS implemented on a world-famous kilometer-level cable-stayed bridge, named as Sutong Cable-stayed Bridge (SCB), is introduced in detail. The composition and core functions of the SHMS on SCB are elaborately presented. The system consists of four main subsystems including sensory subsystem, data acquisition and transmission subsystem, data management and control subsystem and structural health evaluation subsystem. All of the four parts are decomposed to separately describe their own constitutions and connected to illustrate the systematic functions. Accordingly, the main techniques and strategies adopted in the SHMS establishment are presented and some extension researches based on structural health monitoring are discussed. The introduction of the SHMS on SCB is expected to provide references for the establishment of SHMSs on long-span bridges with similar features as well as the implementation of potential researches based on structural health monitoring.

Modeling of a V-type mining support in an advanced engineering environment

Designing technical means using advanced computer systems requires the change in approaches to specific tasks carried out in this process. The solution of this problem is an integrative approach, which allows linking different operating ranges, various tools and complicated sets of requirements into a single operating design system. The elements of this integrative approach is the concept of splitting a technical mean system into three sub-system components. The first is structural sub-system containing solutions and their attributes regarding the structural concept of a designed system. The second is drive sub-system containing solutions of drive systems along with the parameters of their operation. Finally the last sub-system contains information relating to the control system and its settings. Systems attributes include such design features as the geometrical characteristics, material characteristics and assembly characteristics. The subject of the integrated design process is a mechanized mining support. As a part of the project the construction system of a mechanized mining support was divided on the three sub-systems. The structural subsystem includes a canopy, a burst shield and foot parts. Whereas the drive sub-system comprises includes the system of hydraulic props and hydraulic cylinders responsible for the functioning of the support. In the example, presented in the paper, is shown the system of hydraulic props where they are arranged in a V-system. These indicated two sub-systems form the structure of the support. It is complemented by the control sub-system basing on the use of control valves and separator valves and an operator control panel.

Institutional Ethnography

This paper introduces institutional ethnography (IE) as a useful and systematic process for examining organizations and work data through the lens of stakeholders, at different levels, and considering the different forces at play. Drawing from ethnomethodology, IE focuses on how everyday experience is socially organized. Ideological shifts have changed the view of research as purely technical and rational to one of social practice embedded in particular cultural, political, and historical contexts. Research has translated into partially unsuccessful practice because it negates individuals' unique experiences based on race, ethnicity, class, and gender, allowing for a monolithic view to become the given reality for all those who live in today's society. Because adult vocational education is practiced in a highly charged political context, amongst a nexus of interconnected and interdependent social processes such as federal and state legislation, program funding and planning, literacy work, and employment training, discourse sets the parameters for a person's ability or inability to navigate the structural and political subsystems that impact learning, teaching, and work. Power is critically important as an analytic focus which crosses boundaries providing researchers a view of social organization that illuminates practices that marginalize.

Development of an FPGA-based multipoint laser pyroshock measurement system for explosive bolts.

Pyroshock can cause failure to the objective of an aerospace structure by damaging its sensitive electronic equipment, which is responsible for performing decisive operations. A pyroshock is the high intensity shock wave that is generated when a pyrotechnic device is explosively triggered to separate, release, or activate structural subsystems of an aerospace architecture. Pyroshock measurement plays an important role in experimental simulations to understand the characteristics of pyroshock on the host structure. This paper presents a technology to measure a pyroshock wave at multiple points using laser Doppler vibrometers (LDVs). These LDVs detect the pyroshock wave generated due to an explosive-based pyrotechnical event. Field programmable gate array (FPGA) based data acquisition is used in the study to acquire pyroshock signals simultaneously from multiple channels. This paper describes the complete system design for multipoint pyroshock measurement. The firmware architecture for the implementation of multichannel data acquisition on an FPGA-based development board is also discussed. An experiment using explosive bolts was configured to test the reliability of the system. Pyroshock was generated using explosive excitation on a 22-mm-thick steel plate. Three LDVs were deployed to capture the pyroshock wave at different points. The pyroshocks captured were displayed as acceleration plots. The results showed that our system effectively captured the pyroshock wave with a peak-to-peak magnitude of 303 741 g. The contribution of this paper is a specialized architecture of firmware design programmed in FPGA for data acquisition of large amount of multichannel pyroshock data. The advantages of the developed system are the near-field, multipoint, non-contact, and remote measurement of a pyroshock wave, which is dangerous and expensive to produce in aerospace pyrotechnic tests.