Добірка наукової літератури з теми "Coil connection circuits"

Correct choice of coil parameters for resonant circuits in inductive power transmission systems is a relevant problem, as it significantly influences the efficiency and transmitted power in the systems and provides for optimization of these parameters. This paper presents a methodology of calculation of geometrical and electrical parameters and approach to choose the optimal number of turns in planar coils used in the wireless power transmission (WPT) system with parallel resonant circuit. Formulas are derived for calculation of active resistance and inductance of the coil, normalized to the specified design parameters of the coil. Connection is made between the design and electrical parameters of the coil, which allows choosing the optimal number of turns according to different criteria and guard conditions. The examples of practical use of the chosen approach with transmitting and receiving coils of WPT system are presented. The obtained results show that efficiency and transmitted power in the system are higher when using the coils with the calculated number of turns. The proposed approach may be used in selection of optimal design of loop coils in systems with fixed frequency, and in systems, whose operational frequency depends on the parameters of the resonant circuit.

A variety of electric components can be used to bridge connection to the nonlinear circuits, and continuous pumping and consumption of energy are critical for voltage balance between the output end. The realization and stability of synchronization are mainly dependent on the physical properties of coupling channel, which can be built by using different electric components such as resistor, capacitor, induction coil and even memristor. In this paper, a memristive nonlinear circuit developed from Chua circuit is presented for investigation of synchronization, and capacitor, induction coil are jointed with resistor for building artificial synapse which connects one output of two identical memristive circuits. The capacitance and inductance of the coupling channel are carefully adjusted with slight step increase to estimate the threshold of coupling intensity supporting complete synchronization. As a result, the saturation gain method applied to realize the synchronization between chaotic circuits and physical mechanism is presented.

Due to the poor conversion efficiency and signal-to-noise ratio (SNR) of Electromagnetic Acoustic Transducer (EMAT) testing, the defect detection sensitivity is limited, which restricts the extensive industrial applications. A finite element model for the testing process of a meander-coil EMAT was established that considers the simplified excitation and detection circuits for the EMAT. Based on this model, the effect of the connection methods (parallel or series) of the coils in the generating and receiving EMATs on their generating and receiving efficiency was investigated, and the simulation results were validated experimentally. Subsequently, the pulse compression technique with a 13-bit Barker code was used for the EMAT detection, and improvements of the SNR and range resolution were established through numerical simulation and experimental measurement. The results show that compared with the traditional EMAT design, which comprises single-layer transmitting and receiving coils, the conversion efficiency of the optimized EMAT with two excitation and receiving coils in the parallel connection can be improved by 52.8%. With the application of the Barker-coded pulse compression to detect the ultrasonic A-scan signal with no synchronous average, the SNR of the defect echo can be improved by 9.5 dB compared with the A-scan signal with 128 synchronous averages.

Multiple magnetic couplings used to increase the link distance in wireless power transfer systems (WPTSs) are not new. An efficient power transfer in conditions of an extended link distance requires a series connection of the intermediate coils. However, all four connections of the emitter and receiver coils are equally possible. This present paper conducts an extensive analysis of WPTSs utilizing three magnetic couplings. The type of connection of the emitter and receiver coils represented the criterion utilized for the WPTS optimization assessment. The first step requires the determination of the schematic of the sinusoidal equivalent circuit. Then, one synthesizes the functions describing the system performances (e.g., the amount of delivered active power or efficiency) by applying the entirely symbolic and or the hybrid symbolic-numerical formalism. The output of such functions consists of appropriate representation in the frequency domain, based upon Laplace state variable equations (SVE) or complex or Laplace modified nodal equations (MNE). The dependency of the WPTS performance on the number of magnetic couplings and their parameters included a study on resistive loss minimization. The minimization applies to the intermediate coils, whereas the outcomes are the active delivered power and the power transfer efficiency—the first study case aimed at a comparison between two distinct WPTSs: three magnetic couplings versus two. The second case of the study compared the WPTSs having a series connection of three magnetic couplings with those built with the emitter-receiver resonators in parallel. One determined the normalized sensitivities as frequency functions, which depend on circuit resistances, load resistance and the coupling factor between the second and the third coil. The optimization algorithms are suitable for computing optimal parameters of the given circuit to ensure maximum and minimum values of the performance value. Good simulation examples followed the proposed optimization techniques.

Purpose High-temperature (HT°) motors are made with inorganic coils wound with a ceramic-coated wire. They must be carefully designed because the HT° insulating materials have a lower breakdown voltages than the polymers used for insulating standard machines. Design/methodology/approach The voltage distribution between stator coils is computed with high-frequency (HF) equivalent circuits that consider the magnetic couplings and the stray capacitances. Two time scales are used for getting a fast computation of very short voltage spikes. For the first step, a medium time scale analysis is performed considering a simplified equivalent circuit made without any stray capacitance but with the full PWM pattern and the magnetic couplings. For the second step, a more detailed HF equivalent circuit computes voltage spikes during short critical time windows. Findings The computation made during the first step provides the critical time windows and the initial values of the state variables to the second one. The rise and fall time of the electronic switches have a minor influence on the maximum voltage stress. Conversely, the connection cable length and the common-mode capacitances have a large influence. Research limitations/implications HF equivalent circuits cannot be used with random windings but only to formed coils that have a deterministic position of turns. Practical implications The proposed method can be used designing of HT° machine windings fed by PWM inverter and for improving the coils of standard machine used in aircraft’s low-pressure environments. Originality/value The influence of grounding system of the DC link is considered for computing the voltage spikes in the motor windings.

Non-insulation high-temperature superconducting coils provide a much lower risk of burnout in fault/abnormal conditions, such as hot-spot quench and overcurrent. This study employs an equivalent circuit grid model, coupled with magnetic field calculation and the E–J power law of superconductors, to deeply and systematically investigate the overcurrent charging process in a double-pancake non-insulation coil. An evident saturation of the magnetic field in the axial direction of the coil was observed and verified by experiments. Experimentally, the entire process, including the behavior of the magnetic field, was consistent with the numerical results. Based on the verified model, two main points were addressed: (1) Transient current distribution inside the coil during overcurrent charging was studied. Potential quenching risks were found to be at the innermost and outermost turn near the electrodes, as well as the pancake-to-pancake connection part. (2) Magnetic field saturation, which is a unique phenomenon in non-insulation superconducting coils during overcurrent charging, was studied in detail and first quantitatively defined by a new concept “converged load factor”. Its relationship with turn-to-turn resistivity was revealed.

This paper deals with the winding arrangement of multi-phase fractional-slot permanent magnet (PM) synchronous machines (FSPMSMs), with emphasis on the enhancement of their open-circuit fault-tolerance capability. FSPMSMs are reputed by their attractive intrinsic fault-tolerance capability, which increases with the number of phases. Of particular interest is the open-circuit fault-tolerance capability, which could be significantly enhanced through the parallel connection of the coils or suitable combinations of the coils of each phase. Nevertheless, such an arrangement of the armature winding is applicable to a limited set of slot-pole combinations. The present work proposes a design approach that extends the slot-pole combinations to candidates that are characterized by a star of slots including three phasors per phase and per winding period. It has the merit of improving the tolerance against open-circuit faults along with an increase in the winding factor of multi-phase machines. Special attention is paid to characterization of the coil asymmetry required for the phase parallel arrangement. A case study, aimed at a finite element analysis (FEA)-based investigation of the open-circuit fault-tolerance of a five-phase FSPMSM, is treated in order to validate the analytical prediction.

Abstract This study finds the optimum coil resistance, rc.opt, which maximizes the signal-to-noise ratio (SNR) of an electromagnetic (EM) seismometer and amplifier combination. The optimum coil resistance is shown to be the product of a seismometer factor (SF) times the noise resistance, Rn, of the amplifier. The seismometer factors range from 1.13 to 3.66 for the nine EM seismometers considered. The minimum noise figure solution, in which the amplifier noise resistance is set equal to the coil resistance, is shown to correspond to the special case in which there is no damping resistor present. It is also shown that the optimum form for the noise resistance is a constant independent of frequency and that this feature can be approximated with FET-like components such as the MAT-02. Examples of using rc.opt are given using both the 5500-ohm and the 500-ohm 1-Hz L4-C seismometers paired with the OP-27 and LT1028 operational amplifiers, respectively. It is pointed out that, although the resulting amplitude signal-to-noise ratios (ASNRs) are approximately equal, it is best to choose the seismometer-amplifier pair having the larger generator constant because it results in a larger signal. Furthermore, if the coil resistance is not the optimum value, the resulting decrease in the ASNR is less if the coil resistance is chosen greater than the optimum rather than less. The deleterious effects of mismatching seismometer and amplifier are shown by comparing ASNRs for the GS-13 seismometer paired with three different amplifiers. The degradation in ASNR is found to be as large as a factor of 3. It is pointed out that mismatching would not be done purposely but can inadvertently occur when connecting an EM seismometer to a seismic recorder whose input noise resistance properties are unknown, as in generally the case. It is recommended that manufacturers of seismic recorders obtain the necessary input noise data from the component manufacturers and supply the input noise resistance to users. Finally, the three commonly used single-ended preamplifier circuits used for EM seismometers are compared in terms of their resulting ASNRs. The same seismometer and amplifier are used in all three circuits. For the GS-13/MAT-02 pair, the noninverting, parallel damping resistor circuit resulted in an ASNR that was 3.8 times larger than that for the inverting, parallel damping resistor circuit, and 3 times larger than that for the inverting, series damping resistor circuit.

In this paper, the fault current limiting (FCL) characteristics of a flux-coupled type superconducting fault current limiter (SFCL) with parallel connection between two windings in a DC system were analyzed. The flux-coupled type SFCL was composed of two coils connected in parallel and a superconducting element (SE), which was connected in series with the secondary coil. The flux-coupled type SFCL works in DC systems similar to those in AC systems. Before a fault occurs, the respective magnetic fluxes generated by the two coils connected in parallel offset each other, maintaining the voltage induced in the two coils at zero. In case of a fault, however, resistance is generated in the SE, preventing the magnetic fluxes generated by the two coils from offsetting each other. Thus, some voltage is induced in the two coils, and this starts to limit the fault current. DC short circuit tests were conducted, and the test results confirmed that the flux-coupled type SFCL with the two parallel connected coils was effective in limiting the fault current in a DC system. Additionally, the effect of the wiring direction of the two coils on the SFCL’s FCL performance and operating current, limiting impedance, and instantaneous power load was further analyzed, and as a result, the performance conditions of the SFCL in a DC system were determined.

In this paper, a DC fault short circuit was conducted to analyze the DC fault current limiting characteristics of a flux-coupling type superconducting fault current limiter (SFCL) that has two coils connected in series via one iron core. Similar to the AC power system, the flux-coupling type SFCL in a DC system, which has the two coils connected with each other in series and the secondary coil connected with the superconducting element in parallel, remains in the superconducting state before a short-circuit accident occurs. This results in magnetic flux getting generated by the two windings connected in series offsetting each other and the induced voltage at the two windings remaining at zero. However, in the event of a short-circuit accident on the DC line, a resistance is generated on the superconducting element, so that the magnetic flux generated at the two windings no longer offsets each other. Therefore, a voltage is induced on the two windings, and the fault current is limited accordingly. As a result of configuring a DC short-circuit device and experimenting with this SFCL, we could confirm the DC fault current limiting effect of a flux-coupling type SFCL with two windings connected in series. In addition, we could establish performance conditions of the flux-coupling type SFCL in a DC system by inferring the fault current, operating current, and limited impedance equations according to the connection direction of the flux-coupling type SFCL with two windings connected in series and by analyzing fault current limiting degree, power burden, magnetic flux, and energy consumption for each element composing the SFCL.

Дисертація на здобуття наукового ступеня доктор технічних наук за спеціальністю 05.09.01 "Електричні машини і апарати" (141 – електрична інженерія). – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2018 р. У дисертаційній роботі розглянуто проблеми створення мультифізичних моделей, що використовуються при дослідженні і проектуванні вакуумних вимикачів середньої напруги. Об'єкт дослідження – нестаціонарні електромагнітні процеси в неоднорідному, нелінійному, рухомому середовищі, що проводить електричний струм і включає в себе висококоерцитивні постійні магніти; процеси, пов'язані з теорією пружності, механікою твердого тіла, явищами в нестаціонарних теплових полях і теорією механіки суцільних середовищ. Предмет дослідження – вакуумні вимикачі з бістабільними поляризованими актуаторами та закономірності їхньої роботі в динамічних режимах; закономірності та механізм статичної і динамічної деформації контактної системи вимикача під впливом актуатора; здатність вимикача до вмикання та його термічна стійкість під дією аварійних надструмів; рідинні демпфери; електричні схеми керування актуатором. Методи дослідження – дослідження електромагнітних, механічних, теплових процесів і процесів течії рідини базуються на аналітичних і чисельних математичних моделях, які враховують найбільш суттєві лінійні та нелінійні взаємозв'язки між явищами. Чисельні розв'язання диференційних рівнянь в часткових похідних проводяться в спеціальних прикладних пакетах програм, достовірність результатів яких багаторазово перевірена і не викликає сумнівів, а також програмах, написаних здобувачем, які перевірені експериментально. В роботі отримані такі наукові результати. Вперше розроблена модель динаміки поляризованого бістабільного актуатора з постійними магнітами, що базується на розрахунках нестаціонарного електромагнітного поля в нелінійному неоднорідному середовищі, що проводить електричний струм та містить постійні магніти з урахуванням руху частин актуатора у взаємодії з нелінійними рівняннями електричного кола і руху. Розраховані параметри форсованого підключення актуаторів та надано рекомендації щодо конструкції та параметрів актуаторів. Розроблено мультифізичні моделі дослідження впливу параметрів актуаторів на статичні і динамічні механічні напруження в сильфоні вакуумної камери, отримані рекомендації з вибору оптимальної конструкції сильфона і його довговічності, розрахована його втомна витривалість. Розроблено модель впливу параметрів актуаторів на динамічні механічні напруження в контактній системі та механізмі вимикача, що базується на теорії пружності, завдяки чому була розрахована геометрія приводного вала та обраний його матеріал та підшипники. Вперше розроблено мультифізичні моделі, що дозволяють визначити вплив динамічних характеристик актуатора на здатність вимикача до вмикання аварійного надструму: визначена динаміка зіткнення і час вібрації контактів; вирішена теплова задача Стефана з урахуванням теплоти фазових переходів і визначена можлива сила зварювання контактів; надано рекомендації щодо зниження швидкості зіткнення контактів за рахунок застосування рідинного демпфера засновані на рівняннях Нав'є – Стокса і динаміки руху актуатора; розроблена модель нагріву і деформації контактної поверхні і на її основі надані рекомендації щодо розрахунків необхідної сили контактного натискання і геометрії контактів за умов термічної стійкості. Досліджено та проаналізовано оригінальні моделі схем підключення котушок актуатора до різних джерел електричної енергії, надано рекомендації щодо їх практичної реалізації. Результати дослідження були перевірені на макетах, дослідних зразках які підтвердили отримані рекомендації та висновки і використовувались при розробці вакуумних вимикачів. Впровадження основних наукових і практичних результатів дисертаційної роботи знайшло відображення: в договірній роботі з ТОВ «АВМ Ампер» договір № 33 / 98-12 між НТУ «ХПІ» та ТОВ «АВМ Ампер», «Вплив параметрів бістабільного поляризованого актуатора вакуумного вимикача на його здатність до вмикання», м. Кременчук; науково-дослідній та дослідно-конструкторській роботі, яка була виконаної на замовлення ТОВ НВП «Укренергокомплекс-2», «Бістабільні актуатори в установках контролю і розподілу потоків рідини», м. Харків та навчальному процесі. Акти впровадження додаються.
Dissertation for the degree of Doctor of Technical Sciences in specialty 05.09.01 "Electric Machines and Apparatus" (141 – Electrical Engineering). – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2018. In the dissertation work the problems of creation of multiphysical models used in the research and designing of medium voltage vacuum switching devices are considered. The object of the study is transient electromagnetic processes in a heterogeneous, nonlinear, moving medium conducting electric current and including high-coercive permanent magnets; processes related to the theory of elasticity, solid state mechanics, phenomena in non-stationary thermal fields, and the theory of continuum mechanics. Subject of research – vacuum switching devices with bistable polarized actuators; dynamics of actuators; static and dynamic deformation of the contact system of the circuit breaker and the mechanism under the influence of the actuator; the ability of the circuit breaker to switch on and the thermal stability of the circuit breaker under the influence of emergency overvoltage's; liquid dampers; electromagnetic actuator’s control circuit. Research methods – the investigations of electromagnetic, mechanical, thermal processes and fluid flow processes are based on analytical and numerical mathematical models that take into account the most significant linear and nonlinear interconnections between phenomena. Numerical solutions of partial differential equations are carried out using special application software packages, the reliability of which is repeatedly confirmed and does not cause doubts, as well as codes written by the applicant. The following scientific results have been obtained in the work. For the first time a model of dynamics of a polarized bistable actuator with permanent magnets has been developed based on calculations of transient electromagnetic field in a nonlinear non-uniform medium conducting electric current and containing permanent magnets taking into account the motion of parts of the actuator in conjunction with nonlinear equations of electric circuit and motion. The parameters of forced switching on of actuators are calculated and recommendations on the design and parameters of actuators are given. The multiphysical models of studying the influence of actuator parameters on static and dynamic mechanical stresses in a vacuum chamber bellows have been developed, recommendations have been obtained for choosing the optimal structure of a bellows and its durability, its fatigue endurance is calculated. A model of the influence of actuator parameters on dynamic mechanical stresses in the contact system and the switching mechanism based on the theory of elasticity was developed, due to which the geometry of the drive shaft was calculated and its material was chosen. For the first time, multiphysical models have been developed to determine the effect of the actuator's dynamic characteristics on the ability of the circuit breaker to activate the emergency overloads: shock dynamics and contact vibration time are defined; the Stefan thermal problem solved, the heat of phase transitions is taken into account, and the possible strength of contact welding is determined; recommendations for reducing the contact collision rate due to the use of a liquid damper based on the Navies-Stokes equation and dynamics of the actuator are given; the model of heating and deformation of the contact surface was developed and on its basis recommendations were given regarding calculations of the required force of contact pressure and the geometry of the contacts in the conditions of thermal stability. The original models of circuits connecting actuator coils to different sources of electric energy have been investigated and analyzed, and recommendations on their practical implementation have been given. The results of the study were checked on layouts, prototypes and used in the development of vacuum circuit breakers, tests of which models were confirmed by the obtained recommendations and conclusions. Implementation of the main scientific and practical results of the dissertation work was reflected: in agreement with «ABM Ampere», Kremenchk agreement No. 33/98-12 between NTU «KhPI» and «ABM Ampere» LLC «Influence of the parameters of a bistable polarized vacuum actuator of the circuit breaker on its ability to switch on», research and development work performed by order of Ukrenergokompleks-2 LLC, Kharkov «Bistable actuators in control plants and distribution of liquid flows», the acts of implementation are added.

Дисертація на здобуття наукового ступеня доктор технічних наук за спеціальністю 05.09.01 "Електричні машини і апарати" (141 – електрична інженерія). – Національний технічний університет "Харківський політехнічний інститут", м. Харків, 2018 р. У дисертаційній роботі розглянуто проблеми створення мультифізичних моделей, що використовуються при дослідженні і проектуванні вакуумних вимикачів середньої напруги. Об'єкт дослідження – нестаціонарні електромагнітні процеси в неоднорідному, нелінійному, рухомому середовищі, що проводить електричний струм і включає в себе висококоерцитивні постійні магніти; процеси, пов'язані з теорією пружності, механікою твердого тіла, явищами в нестаціонарних теплових полях і теорією механіки суцільних середовищ. Предмет дослідження – вакуумні вимикачі з бістабільними поляризованими актуаторами та закономірності їхньої роботі в динамічних режимах; закономірності та механізм статичної і динамічної деформації контактної системи вимикача під впливом актуатора; здатність вимикача до вмикання та його термічна стійкість під дією аварійних надструмів; рідинні демпфери; електричні схеми керування актуатором. Методи дослідження – дослідження електромагнітних, механічних, теплових процесів і процесів течії рідини базуються на аналітичних і чисельних математичних моделях, які враховують найбільш суттєві лінійні та нелінійні взаємозв'язки між явищами. Чисельні розв'язання диференційних рівнянь в часткових похідних проводяться в спеціальних прикладних пакетах програм, достовірність результатів яких багаторазово перевірена і не викликає сумнівів, а також програмах, написаних здобувачем, які перевірені експериментально. В роботі отримані такі наукові результати. Вперше розроблена модель динаміки поляризованого бістабільного актуатора з постійними магнітами, що базується на розрахунках нестаціонарного електромагнітного поля в нелінійному неоднорідному середовищі, що проводить електричний струм та містить постійні магніти з урахуванням руху частин актуатора у взаємодії з нелінійними рівняннями електричного кола і руху. Розраховані параметри форсованого підключення актуаторів та надано рекомендації щодо конструкції та параметрів актуаторів. Розроблено мультифізичні моделі дослідження впливу параметрів актуаторів на статичні і динамічні механічні напруження в сильфоні вакуумної камери, отримані рекомендації з вибору оптимальної конструкції сильфона і його довговічності, розрахована його втомна витривалість. Розроблено модель впливу параметрів актуаторів на динамічні механічні напруження в контактній системі та механізмі вимикача, що базується на теорії пружності, завдяки чому була розрахована геометрія приводного вала та обраний його матеріал та підшипники. Вперше розроблено мультифізичні моделі, що дозволяють визначити вплив динамічних характеристик актуатора на здатність вимикача до вмикання аварійного надструму: визначена динаміка зіткнення і час вібрації контактів; вирішена теплова задача Стефана з урахуванням теплоти фазових переходів і визначена можлива сила зварювання контактів; надано рекомендації щодо зниження швидкості зіткнення контактів за рахунок застосування рідинного демпфера засновані на рівняннях Нав'є – Стокса і динаміки руху актуатора; розроблена модель нагріву і деформації контактної поверхні і на її основі надані рекомендації щодо розрахунків необхідної сили контактного натискання і геометрії контактів за умов термічної стійкості. Досліджено та проаналізовано оригінальні моделі схем підключення котушок актуатора до різних джерел електричної енергії, надано рекомендації щодо їх практичної реалізації. Результати дослідження були перевірені на макетах, дослідних зразках які підтвердили отримані рекомендації та висновки і використовувались при розробці вакуумних вимикачів. Впровадження основних наукових і практичних результатів дисертаційної роботи знайшло відображення: в договірній роботі з ТОВ «АВМ Ампер» договір № 33 / 98-12 між НТУ «ХПІ» та ТОВ «АВМ Ампер», «Вплив параметрів бістабільного поляризованого актуатора вакуумного вимикача на його здатність до вмикання», м. Кременчук; науково-дослідній та дослідно-конструкторській роботі, яка була виконаної на замовлення ТОВ НВП «Укренергокомплекс-2», «Бістабільні актуатори в установках контролю і розподілу потоків рідини», м. Харків та навчальному процесі.
Dissertation for the degree of Doctor of Technical Sciences in specialty 05.09.01 "Electric Machines and Apparatus" (141 – Electrical Engineering). – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2018. In the dissertation work the problems of creation of multiphysical models used in the research and designing of medium voltage vacuum switching devices are considered. The object of the study is transient electromagnetic processes in a heterogeneous, nonlinear, moving medium conducting electric current and including high-coercive permanent magnets; processes related to the theory of elasticity, solid state mechanics, phenomena in non-stationary thermal fields, and the theory of continuum mechanics. Subject of research – vacuum switching devices with bistable polarized actuators; dynamics of actuators; static and dynamic deformation of the contact system of the circuit breaker and the mechanism under the influence of the actuator; the ability of the circuit breaker to switch on and the thermal stability of the circuit breaker under the influence of emergency overvoltage's; liquid dampers; electromagnetic actuator’s control circuit. Research methods – the investigations of electromagnetic, mechanical, thermal processes and fluid flow processes are based on analytical and numerical mathematical models that take into account the most significant linear and nonlinear interconnections between phenomena. Numerical solutions of partial differential equations are carried out using special application software packages, the reliability of which is repeatedly confirmed and does not cause doubts, as well as codes written by the applicant. The following scientific results have been obtained in the work. For the first time a model of dynamics of a polarized bistable actuator with permanent magnets has been developed based on calculations of transient electromagnetic field in a nonlinear non-uniform medium conducting electric current and containing permanent magnets taking into account the motion of parts of the actuator in conjunction with nonlinear equations of electric circuit and motion. The parameters of forced switching on of actuators are calculated and recommendations on the design and parameters of actuators are given. The multiphysical models of studying the influence of actuator parameters on static and dynamic mechanical stresses in a vacuum chamber bellows have been developed, recommendations have been obtained for choosing the optimal structure of a bellows and its durability, its fatigue endurance is calculated. A model of the influence of actuator parameters on dynamic mechanical stresses in the contact system and the switching mechanism based on the theory of elasticity was developed, due to which the geometry of the drive shaft was calculated and its material was chosen. For the first time, multiphysical models have been developed to determine the effect of the actuator's dynamic characteristics on the ability of the circuit breaker to activate the emergency overloads: shock dynamics and contact vibration time are defined; the Stefan thermal problem solved, the heat of phase transitions is taken into account, and the possible strength of contact welding is determined; recommendations for reducing the contact collision rate due to the use of a liquid damper based on the Navies-Stokes equation and dynamics of the actuator are given; the model of heating and deformation of the contact surface was developed and on its basis recommendations were given regarding calculations of the required force of contact pressure and the geometry of the contacts in the conditions of thermal stability. The original models of circuits connecting actuator coils to different sources of electric energy have been investigated and analyzed, and recommendations on their practical implementation have been given. The results of the study were checked on layouts, prototypes and used in the development of vacuum circuit breakers, tests of which models were confirmed by the obtained recommendations and conclusions. Implementation of the main scientific and practical results of the dissertation work was reflected: in agreement with «ABM Ampere», Kremenchk agreement No. 33/98-12 between NTU «KhPI» and «ABM Ampere» LLC «Influence of the parameters of a bistable polarized vacuum actuator of the circuit breaker on its ability to switch on», research and development work performed by order of Ukrenergokompleks-2 LLC, Kharkov «Bistable actuators in control plants and distribution of liquid flows».

Victorian England was both the world’s first industrial society and its most powerful global empire. Ecological Form coordinates those facts to show how one version of the Anthropocene first emerged into visibility in the nineteenth century. Many of that era’s most sophisticated observers recognized that the systemic interconnections and global scale of both empire and ecology posed challenges best examined through aesthetic form. Using “ecological formalism” to open new dimensions to our understanding of the Age of Coal, contributors reconsider Victorian literary structures in light of environmental catastrophe; coordinate “natural” questions with social ones; and underscore the category of form—as built structure, internal organizing logic, and generic code—as a means for generating environmental and therefore political knowledge. Together these essays show how Victorian thinkers deployed an array of literary forms, from the elegy and the industrial novel to the utopian romance and the scientific treatise, to think interconnection at world scale. They also renovate our understanding of major writers like Thomas Hardy, George Eliot, John Ruskin, and Joseph Conrad, even while demonstrating the centrality of less celebrated figures, including Dinabandhu Mitra, Samuel Butler, and Joseph Dalton Hooker, to contemporary debates about the humanities and climate change. As the essays survey the circuits of dispossession linking Britain to the Atlantic World, Bengal, New Zealand, and elsewhere—and connecting the Victorian era to our own—they advance the most pressing argument of Ecological Form, which is that past thought can be a resource for reimagining the present.

Abstract Transpiration cooling is able to provide more uniform coolant coverage than film cooling to effectively protect the component surface from contacting the hot gas. Due to numerous coolant ejection outlets within a small area at the target surface, the experimental thermo-fluid investigation on transpiration cooing becomes a significant challenge. Two classic methods to investigate film cooling, the steady-state foil heater method and the transient thermography technique, both fail for transpiration cooling because the foil heater would block numerous coolant outlets, and the semi-infinite solid conduction model no longer holds for porous plates. In this study, a micro-lithography method to fabricate a silver coil pattern on top of the additively manufactured polymer porous media as the surface heater was proposed. The circuit was deliberately designed to cover the solid surface in a combination of series connection and parallel connection to ensure the power in each unit cell area at the target surface was identical. With uniform heat flux generation, the steady-state tests were conducted to obtain distributions of a pair of parameters, adiabatic cooling effectiveness, and heat transfer coefficient (HTC). The results showed that the adiabatic cooling effectiveness could reach 0.65 with a blowing ratio lower than 0.5. Meanwhile, the heat transfer coefficient ratio (hf/h0) of transpiration cooling was close to 1 with a small blowing ratio at 0.125. A higher HTC ratio was observed for smaller pitch-to-diameter cases due to more turbulence intensity generated at the target surface.

The primary goal of this project is to design and test of a novel electromagnetic induction (EMI) system that is capable of converting ambient vibration energy into valuable electric energy for use in powering "smart" actuation systems. The principle of the EMI system is based on the Faraday's Law of Induction: the magnitude of the electromotive force (emf) induced in a circuit is proportional to the rate of change of the magnetic flux that cuts across the circuit. The converted electric energy (i.e., emf) from the EMI system will power a semi-active damping control device called a Magnetorheological (MR) damper. The project has been separated into two phases: (1) Optimal design of EMIs, (2) Performance evaluation of MR-EMIs. To identify an "optimal" EMI configuration, several prototype EMIs were designed and constructed. The performance of each EMI was then experimentally evaluated using a spring-mass system. The effects of the number of turns, coil length, number of phases and type of phase connection of the EMIs were evaluated by comparing maximum output voltages. Analysis of the output voltages revealed that generally increases in the number of turns and the number of phases causes an increase in the output voltage while increases in length caused decreases in voltage. In the second phase of the project, a prototype was built that integrated the EMI systems with an existing MR damper, making an MR-EMI system. The dynamic performance of the MR-EMI was experimentally evaluated using a dynamic force frame and a load cell. The results revealed that the current EMI design generated a force equivalent to that produced by a 2 volt battery.