Automatic Stabilization Research Articles

Solving vehicle routing problems with intermediate stops using VRPSolver models

AbstractIn this article, we propose graph‐based models for several vehicle routing problems with intermediate stops: the capacitated multi‐trip vehicle routing problem with time windows, the multi‐depot vehicle routing problem with inter‐depot routes, the arc routing problem with intermediate facilities under capacity and length restrictions and the green vehicle routing problem. In these models, the set of feasible routes is represented by a set of resource constrained paths in one or several graphs. Intermediate stops are supported by the possibility to define negative resource consumption for some arcs. The models that we propose are then solved by VRPSolver, which implements a generic branch‐cut‐and‐price exact algorithm. Thus, a simple parameterization enables us to use several state‐of‐the‐art algorithmic components: automatic stabilization by dual price smoothing, limited‐memory rank‐1 cuts, reduced cost‐based arc elimination, enumeration of elementary routes, and hierarchical strong branching. For each problem, we numerically compare the proposed methodology with the best exact approach found in the literature. State‐of‐the‐art computational results were obtained for all problems except one.

Deep-Learning Image Stabilization for Adaptive Optics Ophthalmoscopy

An adaptive optics scanning laser ophthalmoscope (AOSLO) has the characteristics of a high resolution and a small field of view (FOV), which are greatly affected by eye motion. Continual eye motion will cause distortions both within the frame (intra-frame) and between frames (inter-frame). Overcoming eye motion and achieving image stabilization is the first step and is of great importance in image analysis. Although cross-correlation-based methods enable image registration to be achieved, the manual identification and distinguishing of images with saccades is required; manual registration has a high accuracy, but it is time-consuming and complicated. Some imaging systems are able to compensate for eye motion during the imaging process, but special hardware devices need to be integrated into the system. In this paper, we proposed a deep-learning-based algorithm for automatic image stabilization. The algorithm used the VGG-16 network to extract convolution features and a correlation filter to detect the position of reference in the next frame, and finally, it compensated for displacement to achieve registration. According to the results, the mean difference in the vertical and horizontal displacement between the algorithm and manual registration was 0.07 pixels and 0.16 pixels, respectively, with a 95% confidence interval of (−3.26 px, 3.40 px) and (−4.99 px, 5.30 px). The Pearson correlation coefficients for the vertical and horizontal displacements between these two methods were 0.99 and 0.99, respectively. Compared with cross-correlation-based methods, the algorithm had a higher accuracy, automatically removed images with blinks, and corrected images with saccades. Compared with manual registration, the algorithm enabled manual registration accuracy to be achieved without manual intervention.

Optimization of rwanda power system protection in power blackouts and cascading events

Rwanda's power system security is the most important in optimization of grid frequency to prevent power blackouts caused by load disturbances and power imbalances. To manually stabilize and restore network frequency, a tuned PID (Proportional, Integral, and Derivative) controller was used, but it was inefficient and unreliable. The objective of this article is to develop a system that can be used to balance generation—demand powers during power outages by alleviating grid frequency in load disturbance cascaded events. By balancing power generation and demand, the balanced steady-state approach was proposed and developed to restore and optimize grid frequency to its normal state. This technique used PID-Power System Automatic Stabilization (PID-PSAS) technique based on load frequency control. The load disturbances of ± 20%, ± 10%, and ± 5% of a 250 MW power load were considered. MATLAB/Simulink was utilized to model and simulate the Rwanda power and controller systems. The results showed that the frequency responses of single and two area western and northern grids were reduced to {13*10}^{-5} Hz, {15*10}^{-6} Hz, and 0.251 s for overshoot, steady-state error, and settling time respectively. The proposed control system performance of 99.86% success rate was achieved and compared with the current control techniques of 70.6% performance rate. A stable frequency was observed at any disturbances and more than 300 megawatt losses were mitigated. Finally, the developed control technique rapidly stabilize the frequency and balance the generation-demand powers after 0.251 s. Future works have to focus on 0 Hz of steady state errors using cyber-physical power optimization systems.Article HighlightsThe steadiness of connected loads and power utility supplyReduction of frequency instability and stead-state valuesPrevention and mitigation of power blackouts and power interruptions

The miEye: Bench-top super-resolution microscope with cost-effective equipment

Commercial super-resolution (SR) imaging systems require a high budget, while current more affordable open source microscopy systems lack modularity and sometimes are too complex or lack reliability. We present miEye – a cost-effective microscope designed for high-resolution wide-field fluorescence imaging. The build is constructed using a CNC milled aluminum microscope body and commercially available optomechanics, with open-source Python-based microscope control, data visualization, and analysis software integration. The data acquisition software works robustly with commonly used industrial-grade complementary metal oxide semiconductor (iCMOS) cameras, performs IR beam back-reflection-based automatic focus stabilization, and allows for laser control via an Arduino-based laser relay. The open-source nature of the design is aimed to facilitate adaptation by the community. The build can be constructed for a cost of roughly 50 k €. It contains SM-fiber and MM-fiber excitation paths that are easy to interchange and an adaptable emission path. Also, it ensures <5 nm/min stability of the sample on all axes, and allows achieving <30 nm lateral resolution for dSTORM and DNA-PAINT single-molecule localization microscopy (SMLM) experiments. Thus it serves as a cost-effective and adaptable addition to the open source microscopy community and potentially will allow high-quality SR imaging even for limited-budget research groups.

Multi-channel laser interferometer based on automatic frequency stabilization system for improving coordinate measurement accuracy

Multi-channel laser interferometer based on automatic frequency stabilization system for improving coordinate measurement accuracy

Financial Intermediation, Capital Accumulation, and Crisis Recovery

Abstract We integrate bank and bond financing into a two-sector neoclassical growth model and identify an automatic stabilization effect due to endogenous bank leverage adjustment. We show that although bank leverage amplifies shocks, the increase of leverage due to a decline in bank equity partially offsets the post crisis decline of bank lending and accelerates economic recovery by reducing the persistence of the bank lending channel. In this case, endogenous leverage adjustment is an automatic stabilizer. Regulatory state-independent capital limits and wage rigidities impair the re-allocation of capital between sectors and weaken this automatic stabilization. A quantitative analysis of the US during the Great Recession shows that the magnitude of automatic stabilization can be significant and informs about potentially high costs of strict capital regulation or wage rigidities during banking crises.

Synthesizing of a sliding control law for a hydraulic automatic stabilization system

The sliding mode control has the property of control independence from the characteristics of the unchangeable part of the automatic stabilization system (ASS). In the article, this mode is proposed to be applied to ASS to stabilize the horizontal working plane using two hydraulic cylinders. A model of this ASS has been developed. The paper synthesizes a sliding control law for ASS and simulates ASS operation on MATLAB-SIMULINK. The simulation results indicate that ASS is a stable system and works quite efficiently.

Influence of Electrohydrodynamic Flows on Intensification of the Heat- and Mass Transfer Processes. Part III. Electroconvection and Electrohydrodynamic Pumps in Cooling and Thermostating Systems

The efficiency of the electrohydrodynamic (EHD) cooling and thermostating systems of electronic and electrical devices is investigated. A design of electroconvective cooling of an X-ray generator is proposed, the effectiveness of which is confirmed on laboratory models and full-scale samples. The anode temperature was reduced by a factor of two, the duration of the emitter operation increased, the reliability of the device improved. Various methods of cooling a high-voltage transformer are presented allowing to increase the specific power, reduce the weigh, size parameters, and temperature of the coolant, augment the resource. Studies have been conducted to establish the possibility of thermostating the heat-emitting element (block) by EHD methods when both external and internal conditions change. The design of an EHD thermostat with an automatic thermal stabilization system has been developed and tested (the temperature is maintained with an accuracy of ± 0.05 °С). A frame with an EHD liquid circuit and an EHD thermostat has been designed, which allows to significantly reduce longitudinal temperature differences and its deformation. The high efficiency of EHD cooling methods is shown by an example of a block of light-emitting diodes, small elements and components of electronic equipment, the use of electrodes – wires with a perforated insulating coating when cooling flat heat-emitting surfaces; a sevenfold increase in the heat transfer coefficient is achieved.

A portable neutron gamma discrimination detector based on NaIL and SiPM

neutron-gamma detection technology is widely used in nuclear physics, high-energy physics, radiation medicine, and other fields. A NaIL scintillator coupled with a silicon photomultiplier (SiPM) can form a neutron-gamma detector with excellent discrimination, small size, and low cost. However, the performances of a NaIL scintillator and SiPM are affected by temperature, which leads to a shift in energy spectrum and deterioration in neutron-gamma discrimination. Most of the current studies have used digitizers to store data and analyze detector energy spectrum and waveform characteristics offline to eliminate temperature dependence. In this study, a small neutron-gamma detector was constructed using NaIL scintillators, SiPM, and circuits developed in the laboratory. Online calibration of the ARM processor eliminates the temperature dependence of the detector's energy spectrum and neutron-gamma discrimination. Automatic energy spectrum stabilization and good neutron-gamma discrimination were achieved in a wide temperature range. The test results show that the peak shift of the 137Cs 662 keV full-energy peak of the detector is reduced from 5.3% to 0.4% at 0–50°C. After the online correction of the temperature feedback PSD parameters, the figure of merit at 45°C is 40% higher than that before the correction, and the detector's figure of merit at 0–50°C is maintained above 3.4.

대잠전용 무인수상로봇의 자율운항시스템 설계를 위한 LQR 기반 경로추종 알고리즘 연구

This paper presents the usage of LQR-based intelligent path tracking methods to control the autonomous navigation system of an Unmanned Surface Robot (USR) in sea-clutter environmental fields. Since considerable interest in the Autonomous Navigation System (ANS) of USR in sea warfare has increased, the stability of the Autonomous Navigation System (ANS) control becomes of the utmost importance. When the USR moves in sea environments, the control stability of autonomous navigation systems becomes a major concern. The Path Tracking Controller (PTC) of USRs is one of the high potential subsystems that can be further improved to achieve more accurate, robust, and comfortable tracking performance. The stability of the PTC should be taken into consideration while performing the path tracking task in autonomous navigation. To solve the automatic waypoint tracking stability of independently-developed PTCs, a waypoint tracking controller is designed based on the Linear Quadratic Regulator (LQR) theory with the kinematic model of USRs. Then, a simulation analysis of the designed waypoint tracking controller is performed, and the results are compared at two different speeds. Additionally, complex waypoint tracking tests under realistic sea conditions are performed based on the designed waypoint tracking controller. Results show good tracking performance, which indicates that the designed waypoint tracking controller can adapt to high-speed USRs.

A custom designed modular, scalable test system for an efficient performance evaluation of thermoelectric devices

• A modular, scalable test rig capable of evaluating unicouple, devices and modules. • Ability to handle most thermoelectric (TE) performance evaluation criterion’s including real-world endurance high temperature thermal cycling, thermal soaking and identifying defective devices is demonstrated. • Evaluated three different TE systems viz. Bismuth Telluride, Skutterudites and Half Heusler alloys across different temperature gradients. • Single software platform interacting with DAQ with special features like automatic temperature stability control, high vacuum control, inert gas purging to minimize high temperature oxidation/sublimation of TE device. Reliable and efficient performance evaluation of thermoelectric (TE) elements and devices is critical for developing high performance and robust thermoelectric generator. Due to the inherent thermomechanical coupling, testing thermometric devices is a challenge and requires design of customized test rigs for a thorough evaluation. This article discusses design and development of a modular, scalable customized test rig for performance evaluation of TE devices of different proportions. Various standard TE specifications like harvested power, specific power, instantaneous device resistance, power–current relationships, device efficiency/competence measured against time/temperature difference can be readily evaluated. Further, the test rig is also employed for mimicking real-world endurance thermal cycling tests, high temperature thermal soaking and using measured data to potentially identifying defective devices which have not been addressed in detail before. All these test results together can help determine the effectiveness of TE materials in an actual real world application setting. The scalability and robustness aspects of the proposed test rig is demonstrated by evaluating three different classes of TE systems viz. Bismuth Telluride, Skutterudites and Half Heusler alloys across different temperature gradients and various TE material/legs, devices or modules. The test is capable of handling other TE material systems, geometric configurations and temperature gradients that are not discussed in this work.

Fiscal Consolidation and Automatic Stabilization: New Results

We derive a novel measure of household income stabilization and analyze how reforms of tax-benefit systems in the period 2007–2014 have affected the workings of automatic stabilizers in the EU-27. Our results reveal that the heterogeneity in automatic stabilizers across EU countries has become slightly smaller over the period under consideration. With a few exceptions, automatic stabilizers could operate freely in the early phase of the financial and economic crisis, but were constrained in several EU countries by subsequent fiscal consolidation measures. A comparison of our estimates of automatic stabilizers inherent in tax-benefit systems with macro measures such as changes in cyclically adjusted budget balances reveals that micro-based estimates provide more precise information about the degree of household income stabilization.

Расчет регулятора для многоканального объекта с нестационарными параметрами, содержащего звенья запаздывания

Nonstationary linear systems or linear systems with variable parameters are systems that are described by linear differential equations with variable coefficients. Consideration of the controller synthesis problems for such systems may be dictated by the need to satisfy a certain margin of the automatic control system stability to minor disturbances both from sensors reading the state of the system and from changes in the parameters of the controlled object itself over time. In addition, a real controlled object, in comparison with its mathematical model, quite often contains some uncertainties that should not significantly affect the quality of control.This work considers an example of synthesizing a multichannel controller that would provide a good control quality (stability margin) if the controlled object contains some uncertainties or if its mathematical model with accuracy up to certain parameters is unknown. In addition, the control task is complicated by a link of delay in the structure of the object (that is, there is a certain period of time when there is no reaction from the regulated object to the control action).A modified algorithm of polynomial matrix decomposition of the matrix transfer function of the system, taking into account the conservation of the delay link poles, is chosen as a method of controller synthesis. To demonstrate the algorithm operation, a linear model of the unstable controlled object with a multi-channel structure consisting of two input and two output channels is taken. The description of the object is used in the form of the matrix transfer function, which shows the interaction in the multi-channel control system and the relationship between channels. The object model contains cross-links representing direct input-output connections. The delay links are present in all channels and are approximated using the Pade series with a limited number of terms. The non-stationary parameters of the object were obtained due to the multiplicative interference modeled in the Simulink Matlab package.It is necessary to achieve certain quality indicators of the output vector process when controlling two input influences. To ensure a stable transition process from the system, the poles preservation of the delay link will be necessary. Then the controller calculated for the system with the delay link in the form of the Pade series is applied to the system with an "ideal" delay.

The Impact of Sensor Errors on Flight Stability

Sensors play a significant role in flight control systems. The accuracy of the measurements of state variables affects the quality and effectiveness of flight stabilization. When designing closed-loop systems, it is desirable to use sensors of the highest class and reliability, the signals of which will be as error-free as possible. False indications lead to malfunctioning of the stabilization system, and its operation does not meet the requirements set for it. There are many types of errors—bias, white noise, hysteresis, or bias drift—which affect the measurement signals from the sensors. One of the significant problems is assessing what maximum level of sensor errors stabilization system will still operate as required. In this paper, the impact of different sensor errors on flight stabilization was presented. The research was carried out using the example of an automatic flight stabilization system using aircraft trimming surfaces in a longitudinal control channel in Hardware-in-the-Loop simulations. The model simulates various types of sensor errors during flight, while the stabilization system is implemented in hardware interfaced with a real-time computer. The results of the simulations are presented and analyzed. Their comparison indicated which sensor errors affects the flight stability the most and how the effectiveness of the stabilization system changes as error increases. The presented results show changes in flight parameters due to added sensor errors. Depending on the accuracy class of the IMU, the errors more or less disrupt the operation of the system.

Pre-Flight Test Verification of Automatic Stabilization System Using Aircraft Trimming Surfaces

The new requirement of installing the flight stabilization system onboard the airplanes for performing the single-pilot flights in IFR rules was issued lately. It caused the necessity of developing such a system for small aircraft. The proposed system was developed using Model-Based Design then tuned and tested in Model, Pilot and Hardware in the Loop Simulations. The paper presents the next advanced stage of testing—verification in simulation and ground tests on the PZL-130 Orlik airplane. The implementation of this system does not modify the pilot’s primary manual controls. The newly introduced electrical trim is used for automatic stabilization but can be used at manual trimming as it was previously, depending on the chosen operation mode. The ground tests were planned according to civil aviation authority and aviation law requirements. Chosen results from simulated flights were analyzed and presented, confirming the effectiveness of the proposed system. The dedicated application allowing the test engineer to change stabilization system parameters during the flight on a touchscreen tablet was developed and described. The outcome of the stabilization system test campaign was a verification of its performance before the flight tests. The comparison of simulated and real flight data will allow identifying model deficiencies and flight stabilization system efficiency, which makes possible improvements implementation. Additionally, it appeared to be the cost-effective and less electrical energy-consuming automatic flight stabilization system for small aircraft. Such features benefit initiatives like Future Sky, More Electric Aircraft and aircraft stabilization system retrofit.

Підвищення точності регулювання напруги на конденсаторі активного фільтра

The control scheme of the active filter on the basis of the dq-theory with the block of automatic stabilization of voltage on the condenser containing the system of adaptive control of a delay in time and the filter of low frequencies is considered. The introduction of the delay can be implemented using a microcontroller that will automatically calculate the required delay factor and the output scale factor. The low-pass filter is tuned to the seventh harmonic, which allows you to adjust the delay in the range that provides the minimum value of the allowable error of voltage deviation. A study of the quality of voltage maintenance on the capacitor was also carried out using a set of measures. To improve the compensating capacity of the active filter, the sliding current averaging unit was set to the sixth harmonic in the case of a symmetrical load. The time response of the automatic voltage stabilization unit on the DC capacitor provides a stable charge / discharge process of the capacitor and a high level of compensation of higher harmonics without significant additional generation of active power in the network. It is shown that increasing the accuracy of voltage regulation on the capacitor of the power active filter allows to ensure the achievement of the minimum values of harmonic distortion and stable operation of the system. The transient reaction of the power active filter is determined by the control circuit of the output current of the filter. Therefore, its time response is chosen fast enough to track the current shape of the sinusoidal current. On the other hand, the speed of the control circuit of the capacitor voltage should not be too fast, and it is selected at least 10 times slower than the control circuit of the current filter current. Thus, these two control systems can be divided and designed as two independent systems and adjust each to individual characteristics.

РОЗРОБКА АЛГОРИТМУ ЗАГАЛЬНОЇ СТРАТЕГІЇ АВТОМАТИЗАЦІЇ ВИБОРУ КУРСУ УХИЛЕННЯ СУДНА

During ships maneuvering, the main cause of accidents is that navigators do not always objectively assess the situation and may make wrong decisions on the identification situation of a dangerous approach and a collision hazard. The automation of the deviation course choice is considered as the automation avoidance process. Purpose. The article highlights the tasks of formalizing the deviation course as a value of automatic control, and proposes the development of an algorithm for the strategy of changing the course. Methodology. Conducted processing of practical data of own vessel. The existing models of the ship's movement were analyzes, as well as the systems for the automatic stabilization of the ship. To construct the algorithm, the COLREGs–72 was decomposed with respect to the belonging of the initial situation of the vessels to one of the areas of mutual obligations. Findings. According to the results of the given theme, an algorithm of the general strategy of choosing the course of evasion of the vessel was developed, considering the requirements of COLREG–72 rules. It were considered the types of control of automatic regulators and their limitations at the initial and final moments of the ship's turn. It was found out. It is necessary to create a multilevel mathematical description, which will include subsystems of different levels, to build a model of an integrated control system. Originality. It was determined the efficiency of using the principle of execution of ship’s turns by the method of observation with a given influence by analyzing the existing models of ship’s movement. It was offered to use the range of acceptable values of courses during the development of the model of automation ship avoidance process. Practical value. An algorithm for the general strategy of automation of the avoidance course selection was developed.

Determining the Response Over Time, Current Amplification, Input and Output Resistance of a Parallel-Series Amplifier

Abstract The study determines the behavior type of the parallel-series amplifier and determines the amplification of the basic amplifier, the input and output resistance, as well as the amplification of the reaction network and the input and output resistance of the reaction network. With the help of the negative reaction, the designer can change the properties of the amplifier. Thus, a dynamic, automatic stability of the amplification system is obtained.

A New Payload Swing Angle Sensing Device and Its Accuracy.

Measuring the swing angle of a crane load is a relatively well-known but unsatisfactorily solved problem in technical practice. This measurement is necessary for the automatic stabilization of load swing without human intervention. This article describes a technically simple and new approach to solving this problem. The focus of this work is to determine the accuracy of the measuring device. The focus of this work remains on the design, the principle of operation of the equipment, and the determination of accuracy. The basic idea is to apply the strain gauge on an elastic, easily deformable component that is part of the device. One part of the elastic component is fixedly connected to the frame; the other part is connected to the crane rope by means of pulleys close to the rope. In this way, the bending of the elastic component in proportion to the swing angle of the payload is ensured.

Tax Buoyancy in Sub-Saharan Africa and its Determinants.

In this paper, we estimate short- and long-term tax buoyancy for 44 sub-Saharan African (SSA) countries during 1980–2017 using time series and panel techniques. We find that the long-term tax buoyancy is either one or slightly above one for most SSA countries. Fragile states have a lower short-term tax buoyancy reflecting their institutional weaknesses. Short-term buoyancy of personal income tax is significantly less than one. Both short- and long-run tax responses are lower than those reported in previous cross-country studies, which can be interpreted as a reduced power of both automatic stabilization in the short run and fiscal sustainability in the long run. We find that central government debt and shadow economy exert a downward pressure on tax buoyancy. An important implication of these results is that the current tax systems in SSA would not be able to generate domestic revenues to the extent needed for financing the Sustainable Development Goals (SDGs).