Design, modeling, and pressure control of a 300-kW-class hydraulic pump/motor loading system with energy regeneration

During operation, both of a residual static and dynamic load can be applied to the structural members, and in the case of an emergency impact, such as the sudden structural member removal, the dynamic additional loading arises in the structural elements. Ultimate deformations and strength of concrete and reinforced concrete under this loading mode significantly differ from their values under static or dynamic loading mode. This paper presents the results of experimental and theoretical determination of the concrete stress–strain curve parameters for varying levels of the initial static load and loading modes. The differential equation of the concrete deformation model for the static-dynamic loading mode and its solution at various levels of the initial static stress were obtained. It was established that the maximum permissible time of impact on a concrete specimen under dynamic additional loading and the ultimate strength of concrete depend on the level of the initial static load. Numerical analysis and specimens’ tests shown that parameters of the concrete stress–strain curves under static-dynamic loading mode substantially depend on the level of initial relative stresses in concrete.KeywordsConcreteStatic-dynamic loadingStress–strain curveSpecial limiting stateDeformation modelProgressive collapseExperimentNumerical analysis

After underground coal mining, rocks are often subjected to tensile damage by the interaction of dynamic and static loadings. The process of rock fracture development under dynamic and static loadings will be released in the form of acoustic energy to form an acoustic signal. In addition, the acoustic signals in dynamic loading differ from that in static loading. Therefore, this study conducted three-point bending experiments with continuous dynamic loading and dynamic–static coupling loading on semi-circular red sandstone specimens. The acoustic signals during red sandstone specimens’ tensile damage were monitored in real-time. The results show that red sandstone’s tensile strength and deformation are enhanced under dynamic–static coupling loading. The red sandstone has a more effective acoustic emission hit rate, energy rate, and r during tensile damage under continuous dynamic loading. In dynamic loading, macroscopic fractures are developed in red sandstone, which has few acoustic emission events but releases strong acoustic signals. In static loading, the pores inside the red sandstone are compacted, the rock particles are rearranged, and the tiny fractures are closed, and its acoustic emission events are many but low in energy. In addition, the rock particles in the front area of the static loading fracture are tightly cemented, which increases the difficulty of separating the rock particles in the front area of the fracture under dynamic loading. Then weakening the red sandstone fracture development process and suppressing its acoustic signals. The research results provide more insight into the differences in tensile damage processes in red sandstone under the interaction of dynamic and static loadings.

Due to the increasing penetration of renewable energy sources (RES), frequency regulation has become more challenging. In electrical power network, the load frequency control (LFC) mechanism is a very crucial function for keeping an equilibrium between the power generation and load to avoid frequency deviation (FD). The paper aims to implement an effective LFC scheme for a hybrid AC/DC microgrid (MG) system comprising of wind turbine generator (WTG) and battery energy storage system (BESS). Proportional integral double derivative (PIDD) controllers are used to implement the LFC scheme. The controller parameters are computed using a teaching-learning-based optimization (TLBO) algorithm. The responses acquired using PIDD controllers are compared with the responses obtained using Proportional integral (PI) and Proportional integral derivative (PID) controllers. A critical analysis reveals that the PIDD controller shows better dynamic responses in terms of settling time and magnitude of oscillations compared to the PI and PID controllers. Furthermore, the robustness of the proposed PIDD based LFC scheme is ascertained under different system loadings.

The study was concerned with the human spinal column reaction to axial static and dynamic loading. Fresh segments of the column from dorsal vertebra XI to lumber vertebra II were exposed to axial static (20 mm/min) and dynamic (200 and 500 mm/min) loading. Measured variables included load value, whole segment deformation, anterior surfaces of intervertebral disk Th(XI)-Th(XII) and dorsal vertebra XII, and acoustic emission signals indicative of spongy bone microdestruction. It was found that vertebral body deformation augmented less in comparison with the intervertebral disk and that central parts of the spinal end plates compress greater than peripheral. This difference was more considerable due to static loading rather than dynamic. To produce deformation of a spinal segment by dynamic loading same as by the static one, it is necessary to overcome a stronger resistance of a larger number of trabecular bones. Herefrom it follows that, first, to cause an equal segment compression the dynamic load must be heavier than static and, which is of paramount practical significance, dynamic strength of the column is markedly higher than static. Secondly, spinal stiffness during impact is higher as compared with the static condition. Thirdly, same degree of deformation due to dynamic loading should result in a larger volume of microdestructions comparing with static loading, which is testified by a reliable difference in the number of AE signals accumulated prior to fracture. The number of AE signals amounts to 444.2 ± 308.2 and 85.0 ± 36.6 in case of the dynamic and static loading, respectively (p < 0.05 according to Student's t-criterion).

Modern design standards of developed countries have significant differences in the design provisions for determining the bearing capacity of monolithic reinforced concrete slabs for punching and do not fully take into account the features of design solutions and operating conditions. The available design positions are designed for the static loading mode of structures. The stress-strain state of plates for punching under dynamic load is currently little studied, and as a result, there are no methods for determining the bearing capacity of plates for punching under dynamic loading. The article presents the results of experimental and theoretical studies of the bearing capacity of plates under static and dynamic loads. The methodology of experimental studies and the design of prototypes, equipment for conducting power tests are described, the results of studies on the penetration of fragments of the interface of flat reinforced concrete monolithic slabs with a column under dynamic and static loading are presented. A comparison of the destructive load for samples tested under dynamic loading with the destructive load for samples tested under static load is presented. The factors affecting the strength of the plates during punching under dynamic loading are determined. Proposals have been developed to improve the methodology for calculating the strength of flat reinforced concrete slabs when pushing through static and dynamic loads.

Measures of absolute and relative growth modulation were used to determine the effects of static and dynamic asymmetric loading of vertebrae in the rat tail. To quantify the differences between static and dynamic asymmetric loading in vertebral bone growth modulation. The creation and correction of vertebral wedge deformities have been previously described in a rat-tail model using static loading. The effects of dynamic loading on growth modulation in the spine have not been characterized. A total of 36 immature Sprague-Dawley rats were divided among four different groups: static loading (n = 12, 0.0 Hz), dynamic loading (n = 12, 1.0 Hz), sham operated (n = 6), and growth controls (n = 6). An external fixator was placed across the sixth and eighth caudal vertebrae as the unviolated seventh caudal vertebra was evaluated for growth modulation. Static or dynamic asymmetric loads were applied at a loading magnitude of 55% body weight. After 3 weeks of loading, growth modulation was assessed using radiographic measurements of vertebral wedge angles and vertebral body heights. The dynamically loaded rats had a final average wedge deformity of 15.2+/- 6.4 degrees, which was significantly greater than the statically loaded rats whose final deformity averaged 10.3 degrees +/- 3.7 degrees (P < 0.03). The deformity in both groups was statistically greater than the sham-operated (1.1+/- 2.0 degrees) and growth control rats (0.0+/- 1.0 degrees) (P < 0.001). The longitudinal growth was significantly lower on the concavity compared with the convexity in both the dynamically (0.34 +/- 0.23 mm vs. 0.86 +/- 0.23 mm) and statically (0.46 +/- 0.19 mm vs. 0.83 +/- 0.32 mm) loaded rats (P < 0.001). These growth rates were significantly less than the sham operated and growth control rats (P < 0.001). A variety of fusionless scoliosis implant strategies have been proposed that use both rigid and flexible implants to modulate vertebral bone growth. The results from this study demonstrate that dynamic loading of the vertebrae provides the greatest growth modulation potential.

Improvement of Synergistic Extraction of Neodymium Ions via Robust Model Predictive Control

In order to simulate the vibrating condition of composite insulators in breeze, and carry out its fatigue test under loading and vibrating conditions, the electro-hydraulic loading and testing technology for the composite insulators is researched in this study. A compound electro-hydraulic loading system is first designed, including two subsystems, the static proportional loading system and the dynamic servo loading system. Then, the working principle based on this system is analyzed, and the mathematic model of electro-hydraulic servo system is also built, proved to be an inertial element with high gain. The control method based on proportional–derivative-type iterative learning control has been applied to such a dynamic servo loading system, to achieve the high-precision control for dynamic load force with repetitive regularity. Both mathematic simulation and actual experiments have been designed and carried out, and their results proved that the load principle and the control method are feasible and applicable and have the ability of achieving high-precision control effects. Based on this discussed electro-hydraulic technology, an actual electro-hydraulic loading and testing system for different kinds of composite insulators has been researched and developed, with the advanced technology indices of six loading channels, 20 kN maximum dynamic force, 0.3 kN force control precision and 100 Hz maximum vibrating frequency.

Electricity is a very essential need for every element of society in this modern era, with electricity, various kinds of work can be easily done. However, in electricity distribution, there are often disturbances that can be detrimental to consumers, One of the power lines that usually experiences interference is the Low Voltage Network (JTR) line. JTR is a transmission network with a low voltage classification between 220 volts and 280 volts. In this transmission, various kinds of disturbances often occur, such as overvoltage and voltage drops. In this research, the author discusses the overvoltage protection system using Proportional Integral Derivative (PID) control. PID control is a simple control method that several researchers have developed to overcome various electrical problems in this modern era. For this reason, the researcher will develop PID as a protection system to overcome overvoltage disturbances in JTR transmissions. The appropriate PID parameter value to overcome overvoltage in this study is the value Kp = 5; Ki = 0,3 Kd = 0.01, where the system is able to protect the overvoltage according to the setpoint value 220 volts.

The method of experimental analysis of concrete and reinforced concrete elements is given in order to determine the parameters of concrete deformation under static loading to a given level, followed by a single dynamic high-speed loading by a shock load. Tests of samples are carried out by means of mode static-dynamic loading, which is carried out using a specially designed device that allows you to fix a given level of static loading of the test specimen and load it from this level by a shock load with the specified dynamic parameters. The developed method static-dynamic tests, the priority of which is protected by a patent of the Russian Federation, allows to experimentally determine the parameters for diagrams of deformation of concrete such as dynamic modulus of deformation, dynamic strength of concrete, the ultimate strain of concrete at different conditions considering static and dynamic loading, and the change of the coefficient of dynamic strength of concrete under different levels of initial static load. The analysis of test results the first series of concrete prisms and deformation the strength and time parameters for tested samples and also obtained using ultrasonic PULSAR 2.1 of stress changes and volume deformation of concrete under these modes of loading.

The characteristics of the condition to initiate ductile crack of steels has been quantitatively estimated using the “two-parameters, that is, equivalent plastic strain and stress triaxiality, criterion”. It has been demonstrated by authors using round-bar specimens with circumferential notch in single tension that the critical strain to initiate ductile crack from specimen center depends considerably on stress triaxiality, but surface cracking of notch root is in accordance with constant strain condition.This study provides the fundamental clarification of the effect of strength mis-matching, which can elevate plastic constraint due to heterogeneous plastic straining, loading mode and loading rate on critical condition to initiate ductile crack from notch root using two-parameters. The crack initiation testing using charpy type bend specimens with strength mis-matching near the notch were conducted under static and dynamic loading. To analyze the stress/strain state in the specimens especially under dynamic loading, thermal elastic-plastic dynamic FE-analysis considering the temperature rise was used. It has been shown that the strength mis-matching would not enhance the stress triaxiality at the notch root of bending specimen. The critical condition to initiate ductile crack from notch root for strength mis-matched bend specimens under both static and dynamic loading would be almost the same as that for homogeneous tensile specimens with circumferential sharp notch under static loading. It follows from these results that the ductile cracking from notch root surface under static and dynamic loading would be estimated by “critical plastic strain criteria” even if the strength mis-matching exists near the notch root

This paper presents a comparison between two stabilizing average output feedback controllers implemented on a field programmable gate array (FPGA) facility. A generalized proportional integral (GPI) controller and a proportional integral derivative (PID) controller are implemented using an FPGA, and their respective performances are duly compared. The GPI controller is found to present a better dynamic response than the PID controller in terms of the settling time while exhibiting a greater degree of robustness regarding disturbance rejection represented by severe changes in static and dynamic loads. The average controllers and their corresponding pulsewidth modulation actuators are implemented using a Spartan 3E1600 FPGA.

Microseismic events commonly occur during the excavation of long wall panels and often cause rock-burst accidents when the roadway is influenced by dynamic loads. In this paper, the Fast Lagrangian Analysis of Continua in 3-Dimensions (FLAC3D) software is used to study the deformation and rock-burst potential of roadways under different dynamic and static loads. The results show that the larger the dynamic load is, the greater the increase in the deformation of the roadway under the same static loading conditions. A roadway under a high static load is more susceptible to deformation and instability when affected by dynamic loads. Under different static loading conditions, the dynamic responses of the roadway abutment stress distribution are different. When the roadway is shallow buried and the dynamic load is small, the stress and elastic energy density of the coal body in the area of the peak abutment stress after the dynamic load are greater than the static calculations. The dynamic load provides energy storage for the coal body in the area of the peak abutment stress. When the roadway is deep, a small dynamic load can still cause the stress in the coal body and the elastic energy density to decrease in the area of the peak abutment stress, and a rock-burst is more likely to occur in a deep mine roadway with a combination of a high static load and a weak dynamic load. When the dynamic load is large, the peak abutment stress decreases greatly after the dynamic loading, and under the same dynamic loading conditions, the greater the depth the roadway is, the greater the elastic energy released by the dynamic load. Control measures are discussed for different dynamic and static load sources of rock-burst accidents. The results provide a reference for the control of rock-burst disasters under dynamic loads.

This paper investigates the stiffness of a magnetic bearing that is subjected to the combined action of static and dynamic loads. Since their sum cannot exceed the saturation load, a large static load will imply that the bearing can carry only a small dynamic load. This smaller dynamic load together with the practical vibration amplitude define a practical upper bound to the dynamic stiffness. This paper also presents approximate design formulas and curves for this stiffness capacity as a function of the ratio of dynamic and static loads. In addition, it indicates that vibrations larger than a certain gap fraction can destabilize the magnetic bearing. This gap fraction, called the critical gap fraction, depends on the dynamic and static load ratio. For example, if the dynamic load is half of the static load, the use of more than 25 percent of gap can destabilize the bearing.

Pavement surfaces are not ideally even, which causes dynamic loads of vehicle axles. Distribution of dynamic loads of a given axle is similar to normal distribution and can be described by static load and dynamic load coefficient. The dynamic load coefficient depends on road profile, vehicle speed, properties of suspensions and static load of axle. While for a given road section road profile remains constant, vehicle speed and suspension properties are subject to limited variations, the static loads of particular axle vary significantly. The weigh-in-motion systems are the source of data on static loads, which are characterized by axle load spectra. The axle load spectra are the key data input for pavement design. The article presents a new approach to inclusion of the dynamic loads in axle load spectra. The theoretical explanation is supported by sample calculations. A one-kilometer road section was selected for calculations and its profile was measured using laser road surface profilograph. The dynamic loads were then calculated using the quarter car model and parameters appropriate for heavy vehicle suspensions. This part of calculations proved that dynamic loads significantly increase for less loaded axles. Dynamic axle load spectra were calculated based on static axle load spectra and function of dynamic load coefficient. The load equivalency factors and truck factors were calculated using the fourth power equation and considering both static and dynamic axle load spectra. Contribution of dynamic loads to pavement failure equals up to 19% for the considered example of road profile, which is characterized by IRI = 1.54 m/km.