Management Circuit Research Articles

Development of the information and analytical system of the university

Today, the introduction of analytical systems into the university management circuit has become a necessary and priority task of higher educational institutions. It was led by the desire of the university management to understand the nature of data to improve the quality of educational services and decision-making. This article discusses the analysis of information systems, comparison of business intelligence platforms, and approaches to designing information and analytical system within the university as one of the key elements of the university’s information infrastructure. The presented work describes the data architecture of the corporate information systems of al-Farabi Kazakh National University, designing and implementing an information and analytical system at the university and on the Microsoft Power BI cloud business analysis platform. This system integrates all the disparate data of the university’s corporate information systems and transactional data sources. Furthermore, the logic of data extraction, transformation, implementation of visual reporting in Power BI, and the model of role-based access to them are also described.

Self-Powered Sensing for Smart Agriculture by Electromagnetic-Triboelectric Hybrid Generator.

The lack of efficient, low-cost, distributed energy collection methods is a vital factor restricting the application of the Internet of Things (IoT) in smart agriculture. This paper proposes a method based on triboelectric nanogenerator and electromagnetic generator to realize self-powered IoT nodes and self-powered sensors at the same time. An energy harvesting and sensing device based on electromagnetic-triboelectric hybrid generator (ES-ETHG) is designed. The peak power of ES-ETHG is 32.4 mW, which can supply power to IoT nodes for a long time with power management circuits. In addition, ES-ETHG can critically measure wind speed and wind level within the range of 3-15 m/s, and accurately detect wind direction within 2 s. Furthermore, the self-powered distributed weather sensing system based on ES-ETHG is developed to realize the remote collection of wind speed, wind direction, temperature, and humidity. This work proposes a solution for developing self-powered IoT and sensor in the field of smart agriculture.

Effect of the inherent capacitance optimization on the output performance of triboelectric nanogenerators

Triboelectric nanogenerator (TENG) is a new category of efficient technologies for energy harvesting applications. It has been shown as a promising method for converting low-frequency mechanical motions into electrical energy. The amount of power generated and its optimization are the most important criteria in the design of TENGs. However, some important factors influencing the performance of TENGs are not well known. Here, the TENG inherent capacitance optimization was fully studied, and its impact on the output performance of the energy harvester was assessed. The inherent capacitance of most TENGs varies over time, limiting effective power transfer to the electrical load. Thus, an optimal series capacitor was incorporated into the TENG to stabilize the variations in its inherent capacitance and improve power generation performance. Moreover, this study theoretically demonstrated that this solution increases the system figure of merit, which defines the peak output power in a single cycle. With the addition of the optimal series capacitor into the TENG, the stored energy in a 1000 μF capacitor was increased up to 82.36%. According to the experiments, using a modified power management circuit can dramatically boost the harvested power. Compared to the direct usage of TENG without any interface circuit, using the proposed capacitance optimization method and modification of the power management circuit multiplied the stored energy in a 1000 μF capacitor by 173.9 times. The findings of this study highlight the importance of optimizing the inherent capacitance of the TENG as well as the load resistance, which has important implications for the optimization of TENGs. This method is expected to broaden the applications of TENG devices.

Performance and power management of droplets-based electricity generators

Harvesting energy from raindrops has attracted extensive efforts due to the wide distribution of precipitation and vast potential applications. Among the various approaches developed for this purpose, droplets-based electricity generators (DEGs) based on electrostatic induction have been becoming an outstanding option in the aspect of output voltage and instantaneous power density. Performance dependence of DEGs on the device configuration and the dominating factors have to be revealed for the further optimization. Here, we comprehensively investigated the performance of DEGs with three different configurations, i.e., bottom-electrode, top-electrode and double-electrode, and found that water-to-ground capacitance played an important role in determining the device output. Besides, the conductivity of water shows notable influence on the device performance, tap water with a conductivity around 300 μS/cm shows the highest efficiency in our measurements. Adapting an optimized power management circuit, the pulsed-like output of DEGs is converted to a constant voltage output of variable amplitudes, which is successfully used to charge a smart phone. Our results shed light on possible ways to further optimize the DEG configuration and their potential applications.

Preparation of β-Polyvinylidene Fluoride Film for Self-Charging Lithium-Ion Battery

—In recent years development of sustainable energy sources is getting extensive research interest due to the ever-growing demand for energy. As an alternative energy source to power small electronic devices, ambient energy harvesting from vibration or human body motion is considered to be a potential candidate. Despite the enormous progress in the field of battery research in terms of safety, lifecycle, and energy density in about three decades, it has not reached the level to conveniently power wearable electronic devices such as smart watches, bands, hearing aids, etc. For this reason, the development of self-charging power units with excellent flexibility, and integrated energy harvesting and storage is crucial. Self-powering is a key idea that makes possible the system to operate sustainably, which is now getting more acceptance in many fields in the area of sensor networks, internet of things (IoT) and implantable in-vivo medical devices.For solving this energy harvesting issue, the self-powering nanogenerators (NGs) were proposed and proved their high effectiveness. Usually, sustainable power is delivered through energy harvesting and storage devices by connecting them to the power management circuit, as for energy storage, Li-ion battery (LIB) is one of the most effective technologies. Through the movement of Li ions under the driving of an externally applied voltage source, the electrochemical reactions generate the anode and cathode, storing the electrical energy as the chemical energy. In this paper, we present a simultaneous process of converting the mechanical energy into chemical energy in a way that NG and LIB are combined as an all-in-one power system.The electrospinning method was used as an initial step for the development of such a system with β-PVDF separator. The obtained film showed promising voltage output at different stress frequencies. X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis showed a high percentage of β phase of PVDF polymer material. Moreover, it was found that the addition of 1 wt.% of BTO (Barium Titanate) results in higher quality fibers. When comparing pure PVDF solution with 20 wt.% content and the one with BTO added the latter was more viscous. Hence, the sample was electrospun uniformly without any beads. Lastly, to test the electrical output of such film, a particular testing device has been developed. With this device, the force of a finger tap can be applied at different frequencies, so that voltage generation across the surfaces of the film is validated. Further, this piezoelectric PVDF film can be used as a separator for LIB. Acknowledgements This work was supported by the project 240919FD3914 “Self-Charging Rechargeable Lithium-ion Battery” from Nazarbayev University, Kazakhstan.

A Dynamic Threshold Cancellation Technique for a High-Power Conversion Efficiency CMOS Rectifier.

Power conversion efficiency (PCE) has been one of the key concerns for power management circuits (PMC) due to the low output power of the vibrational energy harvesters. This work reports a dynamic threshold cancellation technique for a high-power conversion efficiency CMOS rectifier. The proposed rectifier consists of two stages, one passive stage with a negative voltage converter, and another stage with an active diode controlled by a threshold cancellation circuit. The former stage conducts the signal full-wave rectification with a voltage drop of 1 mV, whereas the latter reduces the reverse leakage current, consequently enhancing the output power delivered to the ohmic load. As a result, the rectifier can achieve a voltage and power conversion efficiency of over 99% and 90%, respectively, for an input voltage of 0.45 V and for low ohmic loads. The proposed circuit is designed in a standard 130 nm CMOS process and works for an operating frequency range from 800 Hz to 51.2 kHz, which is promising for practical applications.

All-in-One Self-Powered Human-Machine Interaction System for Wireless Remote Telemetry and Control of Intelligent Cars.

The components in traditional human–machine interaction (HMI) systems are relatively independent, distributed and low-integrated, and the wearing experience is poor when the system adopts wearable electronics for intelligent control. The continuous and stable operation of every part always poses challenges for energy supply. In this work, a triboelectric technology-based all-in-one self-powered HMI system for wireless remote telemetry and the control of intelligent cars is proposed. The dual-network crosslinking hydrogel was synthesized and wrapped with functional layers to fabricate a stretchable fibrous triboelectric nanogenerator (SF-TENG) and a supercapacitor (SF-SC), respectively. A self-charging power unit containing woven SF-TENGs, SF-SCs, and a power management circuit was exploited to harvest mechanical energy from the human body and provided power for the whole system. A smart glove designed with five SF-TENGs on the dorsum of five fingers acts as a gesture sensor to generate signal permutations. The signals were processed by the microcontroller and then wirelessly transmitted to the intelligent car for remote telemetry and control. This work is of paramount potential for the application of various terminal devices in self-powered HMI systems with high integration for wearable electronics.

Energy-Positive Activity Recognition - From Kinetic Energy Harvesting to Smart Self-Sustainable Wearable Devices.

Wearable, intelligent, and unobtrusive sensor nodes that monitor the human body and the surrounding environment have the potential to create valuable data for preventive human-centric ubiquitous healthcare. To attain this vision of unobtrusiveness, the smart devices have to gather and analyze data over long periods of time without the need for battery recharging or replacement. This article presents a software-configurable kinetic energy harvesting and power management circuit that enables self-sustainable wearable devices. By exploiting the kinetic transducer as an energy source and an activity sensor simultaneously, the proposed circuit provides highly efficient context-aware control features. Its mixed-signal nano-power context awareness allows reaching energy neutrality even in energy-drought periods, thus significantly relaxing the energy storage requirements. Furthermore, the asynchronous sensing approach also doubles as a coarse-grained human activity recognition frontend. Experimental results, using commercial micro-kinetic generators, demonstrate the flexibility and potential of this approach: the circuit achieves a quiescent current of 57 nA and a maximum load current of 300 mA, delivered with a harvesting efficiency of 79%. Based on empirically collected motion data, the system achieves an energy surplus of over 232 mJ per day in a wrist-worn application while executing activity recognition at an accuracy of 89% and a latency of 60 s.

A high voltage direct current droplet-based electricity generator inspired by thunderbolts

Relatively low output of alternating current (AC) pulsed electricity generated by impinging a water droplet on a hydrophobic surface is difficult for practical utilization. Though high peak power density has been achieved by using a delicate transistor-like architecture and further been simplified to single electrode, the output is still AC pulsed. Methods have been developed to achieve direct current (DC) output, but either an integrated mechanical switch or an air breakdown electrode is necessary. Furthermore, additional rectification, conversion and storage components are prerequisites for further application. Here we demonstrate a DC droplet-based electricity generator to eliminate the unavoidable energy loss by integrating the rectification, energy conversion and storage components into the same device, through a simple yet delicate structure. We show that the water droplet can not only act as a source of charge generation in the process of contact electrification and electrostatic induction, but also act as a charge shuttle by adjusting its gravity-driven movement to sequentially deliver negative charges to the top charge reservoirs and positive charges to the bottom charge reservoirs, outputting DC electricity. Then the water droplet returns to its initial neutral state. A high output voltage over 1600 V has been achieved without any power management circuit. 400 LEDs can be lightened up by a single droplet with volume of 80 μL, showing a great potential for real-life application on water energy harvesting.

An Autonomous Environmental Logging Microsystem (ELM) for Harsh Environments

This paper describes the design, implementation, and evaluation of an environmental logging microsystem (ELM) for operation at elevated pressure and in corrosive environments, at temperatures up to 125°C. The ELM units are intended to be deployed in large quantities, allowed to collect data, and then retrieved, interrogated, and re-charged. Powered by a rechargeable battery embedded within the system, each ELM incorporates pressure and temperature sensors, control electronics, optical communication elements, and power management and battery re-charging circuits. The pressure sensor is a customized capacitive transducer chip on a sapphire substrate; details are provided in a companion paper. The electronic components and battery used in ELM are selected on the basis of functionality and form factor; packaged components are selected for ease of assembly and for added protection against the environment. The pressure sensor, electronics and battery are assembled on a flexible circuit board, folded into a stack with dimensions 7.2 mm × 6.6 mm × 6.5 mm, and encapsulated in a steel tube filled with optically transparent silicone caulk. This encapsulation provides mechanical protection against shock and abrasion, as well as chemical protection against high salinity environments, while allowing the ambient pressure and temperature to be transferred to the sensing elements. Results are reported from high-temperature and high-pressure tests reaching 125°C and 7,250 psi in brine and other corrosive environments in laboratory conditions. Field tests that were conducted in a brine well to a maximum depth of 1,235 m are also described. The recorded data were post-processed to interpret the environmental pressure and temperature.

A Study on the Thermal Management Circuit for Brushless Permanent Motor-Battery System for Compact EV

A Study on the Thermal Management Circuit for Brushless Permanent Motor-Battery System for Compact EV

All-in-One High-Power-Density Vibrational Energy Harvester with Impact-Induced Frequency Broadening Mechanisms.

This paper proposes an electrostatic-piezoelectric-electromagnetic hybrid vibrational power generator with different frequency broadening schemes. Both the nonlinear frequency broadening mechanisms and the synergized effect of the electrostatic-piezoelectric-electromagnetic hybrid structures are investigated. The structure and performance of the composite generator are optimized to improve the response bandwidth and performance. We propose that the electrostatic power generation module and the electromagnetic power generation module be introduced into the cantilever beam to make the multifunctional cantilever beam, realizing small integrated output loss, high output voltage, and high current characteristics. When the external load of the electrostatic power generation module is 10 kΩ, its peak power can reach 3.6 mW; when the external load of the piezoelectric power generation module is 2 kΩ, its peak power is 2.2 mW; and when the external load of the electromagnetic power generation module is 170 Ω, its peak power is 0.735 mW. This means that under the same space utilization, the performance is improved by 90%. Moreover, an energy management circuit (ECM) at the rear end of the device is added, through the energy conditioning circuit, the device can directly export a 3.3 V DC voltage to supply power to most of the sensing equipment. In this paper, the hybrid generator’s structure and performance are optimized, and the response bandwidth and performance are improved. In general, the primary advantages of the device in this paper are its larger bandwidth and enhanced performance.

Research on efficient power management circuit for triboelectric nanogenerator (TENG)

In this research, we tested the electrical output characteristics under a different matching and verified the randomness of the output signal. We focused on the electrical characteristics of friction nanogenerators, analyzed the power management circuit, and then searched on the interaction of the friction nanogenerator with its power management circuit. With the use of synchronous switching technology integrated with a full-bridge rectifier and power management integrated circuit, the power conversion efficiency, especially for random discontinuous energy, was increased.

Influence of Natural Convection on Design of Thermal Diodes

Thermal diode, analogous to the electrical diode, is an emerging field of interest due to its potential application in thermal management, thermal shielding, and thermal circuits. Application of Phase Change Material (PCM) is among the different approaches proposed and analyzed to achieve high thermal rectification. However, these studies often limit the analysis to conduction heat transfer and neglect advection. In the present study, the influence of natural convection on conventional single PCM-based thermal diodes' thermal rectification has been analyzed. Natural convection enhances heat transfer in the inverse direction of gravity, augmenting thermal rectification of diodes with preferential flow in the opposite direction of gravity, whereas adversely affecting the performance of thermal diodes with preferential heat flow in the direction of gravity. Therefore, the design of thermal diode with preferential flow in gravity direction is modified to limit natural convection via the use of metal foam and baffles. The non-phase change material in a thermal diode with preferential flow in the direction inverse to the gravity is replaced with phase change material augmenting the natural convection because of the increase in length. The modified designs led to a mean thermal rectification enhancement of approximately 85% and 1275% in thermal diodes with preferential towards gravity and inverse to the gravity directions, respectively. A thermal rectification of more than 50 is achieved in a modified thermal rectifier for preferential flow in the direction inverse to the gravity.

State Management of National Resources at the Conceptual Level - Images and Meanings of State Symbols

This article is a further continuation of the work on the review of the basics of state management of national resources (state and use), in relation to its system - forming function-state policy and political symbols (the conceptual level of management). From the system positions of the general theory of classification and systematization, the functions of state management of national resources are considered and the role and place of each of them in a single universal management circuit is determined. The role and place of political symbols (a sub-function of the conceptual-strategic level) are considered on the basis of the proposed invariant structure of the typical contour of state management of the state of national resources (operational-tactical level). From the modern state symbols of the Russian Federation, the iconic image two - headed eagle is selected and its prototypes and the origins of their origin, which are located in ancient times, are considered. To consider the evolution of the iconic images of state symbols of modern Russia, it is proposed to systematize and analyze them at different historical stages, to this end, systematize and analyze the following Old Testament images of power (state symbols) of various countries of the world: non-predatory bird, bird of prey, griffin, two-headed eagle, systematize and analyze the sacred images of power double-headed eagle and griffin in the symbolism of the countries of the world with the identification of their sacred meanings-binary (binary). Conclusions are drawn about the common origins of the origin and distribution of these Old Testament images of state symbols in the countries of the Indo-European community, the systematization and analysis of the Old Testament images of power (state symbols) of various countries of the world: non-predatory bird, bird of prey, griffon, double - headed eagle allows us to trace the evolution of the origin and formation of the main state symbol of Russia double-headed eagle, at the heart of the Old Testament images of power griffin and double-headed eagle in the symbolism of the countries of the world lie the sacred meanings of the universal and fundamental principle of reality (world, reality, being) - the duality (duality) of opposite, proportionate and balanced entities.

Battery‐Less Power Management Circuit Powered by a Wearable Piezoelectric Energy Harvester

A system that aims to manage the energy harvested from the finger movement using a glove‐type garment is proposed. For this, five polyvinylidene difluoride (PVDF) film‐type sensors are mounted on different interphalangeal joints of the fingers. A 68 μF/25 V ceramic capacitor is used as a storage device. A battery‐less power management circuit (PMC) is proposed to isolate the capacitor from the load to reduce the current consumption while charging. When the voltage across the capacitor reaches a threshold voltage, the user decides when to transfer the energy to the electronic load. To test the proposed system, the harvested and conditioned energy is used to power both the PMC and a battery‐less cardiac pulse detection circuit, achieving an autonomy of 20 s. This time depends on the voltage stored in the capacitor and the current consumption of the load. Using the proposed wearable system, it is possible to store up to 700 μJ in the capacitor when a subject manipulates a computer or a cellular phone for 10 min. The proposed system is not limited to the activities presented herein because it can harvest the biomechanical energy from any activity that involves finger movements.

Adaptive impedance matching for power management circuit for a piezoelectric energy harvester on the bridge

A piezoelectric impact cantilever in the bridge and a self-powered low power management circuit with stable output voltage matched with a mechanical model are presented in this paper. Based on the piezoelectric effect, the low-frequency mechanical vibration is converted into high-frequency electrical signal oscillation. The generated voltage preserves into the low-power constant-voltage power management circuit, which can effectively store electric energy. The equivalent circuit model of vibration for a piezoelectric impact cantilever is obtained. The key of energy management circuit is to improve energy storage efficiency. When impedance matching is achieved, the efficiency is maximum. Since the equivalent impedance of piezoelectric material is different in the impact process and natural vibration process, this paper uses the delay link and D-trigger to form the peak detection circuit, which can distinguish two vibration processes. So different duty cycles are generated to control the buck-boost circuit to achieve adaptive impedance matching. It can be found that the efficiency reached more than 80 %. Compared with the traditional energy management circuit, the efficiency is increased by 18 %.

A new Mylar-based triboelectric energy harvester with an innovative design for mechanical energy harvesting applications

In this paper, an innovative origami structure is deployed to create a novel, flexible, lightweight, and low-cost triboelectric nanogenerator (Miura-Ori-TENG). For the first time, Mylar film is used as a supporting and flexible spring-like structure to develop the first Mylar-based origami TENG, eliminating the need for any external auxiliary system to ensure continuous operation of the TENG. Subsequently, a self-powered power management circuit with a novel self-controlled switching mechanism is designed and implemented for direct use of Miura-Ori-TENG electrical output and maximizing the harvested energy. The performance of the Miura-Ori-TENG and power management circuit are evaluated under different practical conditions. The open-circuit voltage and short-circuit current reached 308.6 V and 55.5 µA, respectively, with a peak power of 5.1 mW under a linear reciprocating motion with an operating frequency of 4 Hz. Moreover, open-circuit voltage, short-circuit current, and instant output power of 1050 V, 131 µA, and 40 mW are obtained using footsteps during human walking. Furthermore, in a 1000 µF capacitor charging experiment using the proposed power management circuit, the stored energy increased up to 117.5 times compared to a direct charging experiment. In order to prove that the Miura-Ori-TENG, in combination with the proposed power management circuit, could be used as a power source in many applications, its ability to charge the capacitors and rechargeable batteries and drive the electronics is shown with proof-of-concept demonstrations. The results of this study demonstrated potential applications of the Miura-Ori-TENG in converting rotational, vibrational, and impact kinetic energies into electrical energy, as well as the outstanding performance of the proposed power management circuit in managing the harvested energy.

Elastic‐Connection and Soft‐Contact Triboelectric Nanogenerator with Superior Durability and Efficiency

AbstractTriboelectric nanogenerator (TENG) has received tremendous attention in ambient energy harvesting, especially for ocean wave energy. However, the technology is generally challenged to obtain excellent durability and high efficiency simultaneously, which primarily overshadows their further industrial‐scale applications. Here, a dual‐mode and frequency multiplied TENG with ultrahigh durability and efficiency for ultralow frequency mechanical energy harvesting via the elastic connection and soft contact design is proposed. By introducing the spring and flexible dielectric fluff to the novel pendulum‐like structural design, the surface triboelectric charges of TENG are replenished in soft contact mode under the intermittent mechanical excitation, while the robustness and durability are enhanced in non‐contact working mode. The fabricated TENG results in a continuous electrical output for 65 s by one stimulus with a high energy conversion efficiency, as well as negligible change of output performance after a total of 2 000 000 cycles. Moreover, integrated with the power management circuit, the TENG array is demonstrated to drive the electronics by effectively harvesting wind and water wave energy as a sustainable energy source. This work paves a new pathway to enhance the robustness, durability, and efficiency of the TENG that resolves the bottleneck of its practical applications and industrialization.

Mathematical Models for Implementation of the Concept of Hard budget Restrictions in the budgetary system

The subject of the study is the processes of budget decentralization in the management of public finances, as well as mathematical methods and models for implementing the concept of hard budget restrictions in order to create conditions for the self-development of administrative-territorial units. The aim of the study is to develop adaptive economic and mathematical models for implementing the strategy of hard budget constraints implemented in the process of inter-budget regulation. The relevance of the study is due to the fact that currently the subject of acute discussion in the scientific community is the self-development of administrative-territorial entities and increasing their financial independence. In this regard, the focus of economic research is focused on the problems of budgetary decentralization as an engine of economic development, as well as the related topics of the use of mathematical tools for modeling decision support in this area. The created models are subject to the requirements of learnability, adaptability to changing conditions of environmental influences, and the ability to operate not only with quantitative, but also with qualitatively defined characteristics. The problem of mathematical modeling is solved by applying an interdisciplinary synthesis of the theories of stochastic automata operating in random environments and fuzzy logic. The proposed synthesis of theoretical and methodological devices is the novelty of the research. As a result , an economic and mathematical model of a fuzzy automaton is constructed for determining and quantifying the values of the norms for the distribution of tax revenues between budgets of different levels of the budget system. A fuzzy automaton interacts with a simulation model that reproduces budget flows and quantifies the decisions made by the automaton model. The practical significance of the research results lies in the program implementation of the developed models and their inclusion in the public finance management circuit. In the future , it is planned to create a mathematical model of the collective behavior of fuzzy automata models, the interaction of which solves the problem of coordinating the interests of budgets of different levels of the hierarchy in the distribution of tax revenues.