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A study on the load characteristics of the modified gear planetary gear systems is conducted to address the issue of uneven loads between planetary gears due to manufacturing and installation errors, which result in deviations between the radial and circumferential installation positions of planetary gears and non-offset values. Based on the theory of rotor dynamics, the time-varying stiffness and the radial and circumferential offsets of the planetary gears are considered, and the five-degree-of-freedom dynamic model of the planetary gear transmission system with addendum modification is established. The response and frequency spectrum of the system are solved by the Runge-Kutta method. The load distribution characteristics of the planet gears under different radial offsets, circumferential offsets, and comprehensive offsets are analyzed. The influence of the radial and circumferential offset of the planetary gear on the load distribution of the planetary gear transmission system is discussed, and the variation law of the load vibration amplitude of the planetary gear transmission system with addendum modification under the time and frequency is obtained. The simulation results show that the load characteristics of the planetary gear train considering the error are quite different from those in theory. Its vibration amplitude of the planetary gear transmission system is greatly affected by the radial offset, and the large radial offset has the greatest impact on the load of the planetary gear. Small deflections of the planetary gear during installation can lead to large changes in the load characteristics. The planetary gear transmission system load test platform is built, the frequency-doubling vibration response signal of the planetary reducer housing is tested, and the relation between the planetary gear transmission system load force and vibration response is obtained. The amplitude variation trend in the experimental results is similar to that in the simulation analysis, and the correctness of the established model and solution method is verified.

The difference in power demand and the driver's operation in various operation stages make the loader have the problem of low energy utilization. Changeable operating objects and drastically changing loads have exacerbated the difficulty of energy-saving research in different operating stages of loaders. Therefore, based on identifying the operation stage and analyzing the load characteristics under typical working conditions of the loader, this paper proposes a shovel-loading cooperative control strategy. Specifically, the Drag Reduction Insertion (DRI) in the shoveling stage is realized based on learning the driving intention. Based on different operation stages, the load characteristics of different materials for shovel-loading are deeply analyzed, and the prediction research of the power output characteristics of the power unit is carried out. The shovel-loading cooperative control solves the problem of the poor economy caused by different power requirements in different operation stages and significantly reduces the impact of the driver's operating experience. • A cooperative control strategy for shovel-loading of loader is proposed. • Accurate identification of the operational stages are completed. • The DRI in the shoveling stage is realized based on learning the driving intention. • The prediction research of the power output characteristics of the power unit is carried out. [ABSTRACT FROM AUTHOR]

To improve the load characteristics of the transmission error for helical gears, a gear made of laminated materials is proposed. The gear has three layers in which metals with different rigidities are laminated in the tooth width direction. The layers on both sides are made from the same metal, and a different metal is used for the central layer. A theoretical analysis was performed to investigate the effects of arranging high- and low-rigidity layers and changing the width of the central layer. The laminated gear has load characteristics different from the transmission error for a conventional homogeneous material gear. The transmission error can be reduced with the combination of a high-rigidity central layer and a low-rigidity side layers, and a low transmission error can be maintained over a wide load range by adjusting the central layer width appropriately. The principle of the reduction in the transmission error is that, by changing the rigidity along one-pitch meshing progress with laminated materials, the elastic deformation of the teeth can largely cancel out the rotational fluctuations caused by the tooth flank shape over the wide load range. A pair of laminated gears was manufactured, and testing confirmed that the laminated gear has a transmission error lower than that for a gear made from a homogeneous material. The laminated gear has the potential to achieve the lower vibration/noise generation for the wider load range than the homogeneous gear.

Modern power system is stepping into the era of big data. It is necessary to widely collect multi-source data and mine the load characteristics of load data from different angles. This paper introduces an efficient comprehensive characteristic analysis method of 10 kV bus load based on integrated clustering technology, which includes clustering the load from vertical and horizontal dimensions respectively to obtain the clustering results under the unified time frame. Firstly, K-means clustering and hierarchical clustering are used to establish the load characteristic model for the whole year’s load data, and the daily load characteristics and hourly load characteristics are obtained. Then, the distribution time area of the maximum load and the normal operation threshold of the load are analyzed. Finally, the feasibility of this method is verified through the 24 * 365 load data, which provides convenience for the subsequent power system optimization.

This paper aims to analyze the distribution efficiency of DC power distribution power system in commercial building based on measured data from a typical office building in Hong Kong. In this research, a real-scene comparative testbed was built in a Hong Kong office to compare the energy efficiencies of AC and DC power distribution system. Similar load characteristics and use schedules are set and used in the experiment. The distribution efficiency has been found to be affected by load type, voltage level and the loading conditions. The efficiency of this DC power system is derived, considering the PFC model was working in a good condition. For LED loads, the average distribution efficiencies after converter are 77.7% and 51.8 % under the condition of full lightning and normal lightning mode. The main loss in this system is transmission loss and switching loss. The average AC/DC converter efficiencies of LEDs are 92.21% and 88.85% respectively with the load working under full power and normal power, while the average AC power factors of LEDs are 85.31% and 56.22% respectively with the load working under the same as above. The average AC/DC converter efficiencies of the fan coil are 97.41%, 96.03%, 92.74%, 89.10%, 85.71%, 78.72%, 67.61%, 63.57% respectively with the load working under level 8 to level 1 while the average AC power factors of the fan coil are 98.0%, 99.0% and 99.4% respectively with the load working under low middle and high condition. As the PFC circuit does not have ideal power factor correction when the load is small, it is not recommended to add PFC circuit when the load power is low. Using uncontrollable rectifier circuit is going to lead to a better performance.

The load characteristics of a power grid significantly change with the increase in the number of electric vehicles (EVs). In this study, we present a method for predicting the long-term load characteristics of Hubei Power Grid (A large power grid in China with annual power consumption of 207.1 billion kWh in 2020) up to until year 2030 with the development of EVs. The predicted load characteristics include the annual peak loads and hourly load curves of typical days for different seasons in target years 2025, and 2030. The proposed long-term load forecasting method uses saturated load prediction with grey Verhulst model and Monte Carlo simulation. The future impacts of the charging load of EVs on the grid are discussed in detail.

In order to investigate the load-sharing performance of the 2K-H planetary gear transmission system， a translation-torsion coupling dynamics model is established with considering the nonlinear factors of time-varying meshing stiffness and the overall meshing error and so on， the dimensionless differential equations with 18 degrees of freedom of the system are deduced in this model. By solving the differential equations， the influences of the support stiffness of the center component and the clearance floating on the load-sharing performance of the planetary gear train are analyzed. It is shown that the floating amount of the component increases with the reduction of the support stiffness of the center component and the increase of the clearance of the shaft hole within a certain range， the load-sharing factor of the system decreases when the floating amount of the component increases.

Low-temperature discharged water from thermally-stratified reservoirs in spring and summer will have a negative environmental impact on fish breeding and agricultural irrigation downstream. The temperature-control curtain (TCC) is a selective withdrawal structure that can effectively change the discharged water temperature. Compared with a traditional selective withdrawal project, a TCC project has the advantages of low cost and simple construction and can even be added to operating reservoirs without impacting power generation. Analysis of the load characteristics is the key to the application of TCC engineering. This paper establishes a three-dimensional numerical model simulation and verifies it with physical model experimental results. The crucial parameters affecting the load characteristics of TCC are investigated, including the water blocking rate, area ratio, inclination ratio, inflow velocity, and water temperature stratification ratio. The results show that: (1) This numerical simulation approach can be used to predict the drag coefficient and the load of a TCC; (2) the water blocking rate has the greatest influence on the drag coefficient, and it is the most critical indicator of the TCC load; and (3) the drag coefficient exponentially increases with an increasing water blocking rate, quadratically increases with an increasing area ratio, linearly increases with an increasing inclination ratio, and linearly increases with an increasing water temperature stratification ratio. [ABSTRACT FROM AUTHOR]

This work presents the performance analysis of a single phase interior permanent magnet synchronous generator. The stator magneto motive force (MMF) waveform of the single phase winding function was developed. The mathematical model in phase variables by which the performance of the generator can be investigated under various operating conditions was developed. Self-excitation of the generator was achieved through pre-excitation by the permanent magnet in the rotor, and then regulated by connecting 30µF capacitor across the terminals of the stator winding. The performances of the generator under constant speed, constant capacitor value and varying power factor loads was investigated. The voltage build-up characteristics and dynamic loss of load performance was studied. The magnitudes of the output power, real power, load voltage and load current increases with increase in load power factors while the phase voltage, phase current, capacitor current and the reactive power decreases with increase in power factor loads. The generator has shown to be capable of stand-alone power source. Simulations were carried out using the Simulink® toolkit in MATLAB® software. [ABSTRACT FROM AUTHOR]

Planes are the execution tools of coal plough,the work load directly affecting the planing capacity and production efficiency of the plow. In order to study the load characteristics,developing the coal plow load calculation program based on Matlab and VC,which can calculate the random load of planer at different positions according to the different simulating coal seam occurrence conditions; Planes at different positions were simulated and the strength verified based on ADAMS software. By analyzing the results indicate that : in the same cutting depth,the loads of planes at the different positions are random,in which load short broadsword’s means and standard deviations of the three load are minimum and the cutter force is relatively stable and uniform compared with other positions,followed by long broadsword,knife top and bottom knife; With increasing of planing depth,three forces of planes suffered have varying degrees increased,When the cutting depth exceeds a certain value,cutting resistance will be significantly increased; when the cutter spacing exceeds a certain transversal distance,cutting force increases sharply; In the working process,long and short waist by the maximum stresses are located in knife body thickness position transition connection and the knife body and the lamellar alloy head is embedded,main failure mode for the wear and fracture;the top and bottom knife knife connected with the knife base part chamfer can relax the stress concentration. Analysis results of load planer reliability and structure optimization design provides a theoretical basis for the study of dynamic.

A composite sliding mode control based on the load characteristic of the permanent magnet direct-driven system is presented for a mining scraper conveyor. First, the mathematical model of a permanent magnet synchronous motor is established based on the coordinate transformation theory. Subsequently, the soft switching sliding mode observer (SS-SMO) is designed to observe the change of load torque in real time. The composite sliding mode speed controller of PMSM is designed on the basis of non-singular terminal sliding mode control, in which the observed load torque is used for feed-forward compensation. The chain characteristics of a scraper conveyor are described by the Kelvin-Vogit model, and the dynamic model of the overall scraper conveyor system is established with the distinct element method. Next, according to the coupling relationship between the permanent magnet direct-driven system and the scraper conveyor, the electromechanical coupling simulation model is established using the MATLAB/Simulink module. The simulation results demonstrate that the composite sliding mode controller of the permanent magnet direct-driven system can achieve smooth starting of the scraper conveyor, and the effectiveness of the designed controller is illustrated by comparing the controller with the related reference. In addition, the designed SS-SMO can estimate the load torque precisely, enhance system robustness and suppress the chattering of the control system caused by the load change.

The load（ working condition） coefficient is one of the important original inputs in the design of chain transmission system,it is directly related to design variables of the chain bearing capacity,especially for the timing silent chain system,the chain plate thickness or number are all related to it. Through a engine timing chain system design,ignoring the torsional vibration and engine cylinder to work,the load characteristics of the timing silent chain system are analyzed qualitatively. By using the cylinder head anti drag system test bench,through static and dynamic load torque test,the load coefficient and the method of determining under different speed conditions of the timing silent chain system are proposed,which is of great reference value to the design of the multi axis and high speed silent chain system.

Low-temperature discharged water from thermally-stratified reservoirs in spring and summer will have a negative environmental impact on fish breeding and agricultural irrigation downstream. The temperature-control curtain (TCC) is a selective withdrawal structure that can effectively change the discharged water temperature. Compared with a traditional selective withdrawal project, a TCC project has the advantages of low cost and simple construction and can even be added to operating reservoirs without impacting power generation. Analysis of the load characteristics is the key to the application of TCC engineering. This paper establishes a three-dimensional numerical model simulation and verifies it with physical model experimental results. The crucial parameters affecting the load characteristics of TCC are investigated, including the water blocking rate, area ratio, inclination ratio, inflow velocity, and water temperature stratification ratio. The results show that: (1) This numerical simulation approach can be used to predict the drag coefficient and the load of a TCC; (2) the water blocking rate has the greatest influence on the drag coefficient, and it is the most critical indicator of the TCC load; and (3) the drag coefficient exponentially increases with an increasing water blocking rate, quadratically increases with an increasing area ratio, linearly increases with an increasing inclination ratio, and linearly increases with an increasing water temperature stratification ratio.

Based on the coal rock cutting theory,simulated the load characteristic of the roller in the process of during coal rock; with the flexible-body dynamics as the theoretical basis to establish rigid-flexible coupling model of cutting unit,simulate the process of height adjustment by ADAMS and get the load response of link point; used Workbench to get the stress distribution of ranging arm when the link point force is maximum during the process of height adjustment; with linear cumulative damage rule as the theoretical basis,used Workbench to estimate the fatigue life of the ranging arm to verify the results of the reliability analysis and load response analysis.This paper provides a new method to research on dynamic characteristic and reliability of shearer cutting unit.

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Zhang, Z.; Wang, L.; Yao, X., and Lang, J., 2017. Dynamics of an underwater explosion bubble near a rigid wall: Effect of slenderness ratio, installation, and distance parameter. Structural damage of maritime construction ( e.g., dams, warships, etc.) has received considerable international attention in recent years because of underwater explosions from accidental events and terrorist bombing attacks. Therefore, research studies on underwater explosion load characteristics will have a great influence on the future of coastal and maritime engineering. Here, level set-direct ghost fluid-Runge Kutta discontinuous Galerkin method and boundary element method are combined to establish a model of underwater explosion near a rigid wall. First, the hybrid algorithm is used to simulate the process of underwater explosion in free field; the results agree well with experimental data, proving the effectiveness of the algorithm. Second, the process of underwater explosion near a rigid wall is simulated by the presented method. Finally, effects of parameters - slenderness ratio, installation (horizontal and vertical), and distance from the center of the explosive to the rigid wall - are investigated on shock waves and bubble dynamics. It is found that during the detonation process, the ellipsoidal bubble gradually turns into a spherical one. The radial pressure peak value is higher than the axial one. During the collapse phase, the slenderness ratio and the installation have little effect on bubble shape, maximum radius, and pulsation cycle. During the bubble-jet process, a high-speed jet penetrates the bubble toward the rigid wall and generates a high-pressure region on the bubble wall. For the charge placed vertically, the jet velocity rises while the jet width decreases as the slenderness ratio increases; results for horizontal cases are opposite. The jet velocity in the vertical case is lower than that in the horizontal case; on the contrary, the jet width is larger. With the increase of the distance parameter, the pressure on the upper surface of the bubble and the jet velocity are higher, whereas the jet width is smaller. [ABSTRACT FROM AUTHOR]

Aiming at the complex conditions of the first shielded bolter miner in the actual work, the mechanical model of bolter miner cutting head was established. Based on cutting mechanism of the conical pick and the cutting head, the cutting head load and torque analysis model under complex coal seam were established. The dynamic characteristics of load and torque in the process of cutting head are analyzed under three different working conditions of cutting roof-coal layers, coal-floor layers and coal seam by finite element method. The results show that when the damage variable D = 1, the coal-rock completely lacks the bearing capacity, and it forms arc-shaped crushing groove on the coal-rock. The large difference of torque between roof-coal layers and the roof-coal layers in the conical pick is 112 Nm, which indicates that the cutting head has the best performance with cutting the coal seam first and then cutting the rock. In the process of excavation, the load fluctuation coefficient of cutting the coal-floor layers and roof-coal layers is about 1.2 times of that of the coal seam. The results can provide a reference for the efficient cutting and performance evaluation of the bolter miner. [ABSTRACT FROM AUTHOR]

The FST2E engine test bed was applied to carry out the simulation tests of the F6L913 diesel engine's plateau performance, to obtain the data of the engine at different altitudes and in various conditions, including torque, power, fuel consumption rate and oil consumption, and to generate the external characteristic curve and the load characteristic curve of the engine by fitting. The test result shows that the engine power and torque is decreased by 15 % to 20 % and the fuel consumption rate is increased by 15 % to 30 % whenever the altitude is increased by 1000 m, and the higher the altitude is, the faster this increase rate becomes. The stable working range of the engine becomes narrower and drifts to the high revolution area.

The results of experimental study of automotive ICE running using biogas with different volume content of CO2 are presented. Recommendations for choosing the values of air-fuel ratios and ignition timings for different operating modes of the automotive biogas engine depending on fuel chemical composition are given.

The new principle of the organisation of working process of the combined supercharging system of transport diesel with the Cascade Pressure Exchanger (CPE) has been described. It allows considerably to raise level of forcing of the engine by supercharging at the expense of expansion of effective air supply area and coolings of supercharging air to temperature below an ambient. Substantive postulates of imitating model of work of combined engine(CICE) have been stated. Some results of calculation-experimental investigations of supercharging system of the engine 6ЧН12/14 have been given. It confirms the possibility of the essential improvement tractive and fuel-economic factors of the transport installations in broad range of the working conditions.

A new method of organization of working cycle of device of direct transformation of heat in the located work of compression of air, based on principle of cascade exchange by pressure, is exposed; the results of pre-selection of basic dimensional and structural parameters of thermal compressor of cascade exchange by pressure are adduced; some special features of its working process are considered; main directions of perfection of working cycle of thermal compressors of cascade exchange of pressure are shown.

Presented paper is dealing with operation load of three-point hitch (TPH) of agriculture tractor in randomly changeable working conditions and their simulation in laboratory. The basic goal was to obtain experimental data, after which we can judge and analyze problematic of dynamic load of wheel tractor at plowing with orientation on TPH. Another goal was using obtained result from operating measures on their simulation in laboratory conditions by hydrostatic simulator. In presented paper is solved power analysis in each elements TPH of agricultural tractor ZTS 160 45URII A. The tractor during exploiting was in set with four-ploughshare carried and five-ploughshare semi-mounted plough. The measuring was realized for 3 varieties of set speed (gear ratio I/2, I/3, I/1), 3 depths of plowing (20, 25 and 27 cm) and 3 varieties of TPH - positional, mixed and draught control.

This paper presents the experimental determination of the ZIP coefficients model to represent (static) modern loads under varying voltage conditions. ZIP are the coefficients of a load model comprised of constant impedance Z, constant current I, and constant power P loads. A ZIP coefficient load model is used to represent power consumed by a load as a function of voltage. A series of surveys was performed on typical residential, commercial, and industrial customers in New York City. Household appliances and industrial equipment found in the different locations were tested in the laboratory by varying the voltage from 1.1-p.u. voltage to 0 and back to 1.1 pu in steps of 3 V to obtain the individual P–V, Q–V, and I –V characteristics. Customer load tables were built using seasonal factors and duty cycles to form weighted contributions for each device in every customer class. The loads found in several residential classes were assembled and tested in the lab. It was found that modern appliances behave quite differently than older appliances even from only 10 years back. Models of the different customer classes were validated against actual recordings of load variations under voltage reduction. [ABSTRACT FROM AUTHOR]

This paper presents the performance of homopolar inductor alternator (HIA) with diode-bridge rectifier and capacitive load. According to the conduction and commutation rules, all the operational modes included in the bridge rectified capacitive load are considered. A simplified average-value mathematical model is established; furthermore, we derive the load characteristic under every operation mode. Using the fundamental machine differential equations and the connecting characteristics between alternator and rectifier, we establish a port-network state model of the system. The performance of the HIA with bridge rectifier and capacitive load can be predicted from charging current, commutating angle, and given parameters of the alternator. Theoretical results are compared with the simulation results obtained from numerical procedure. [ABSTRACT FROM PUBLISHER]

Abstract: Under-voltage load shedding is an important measure for maintaining voltage stability.Aiming at the optimal load shedding problem considering the load characteristics,firstly,the traditional under-voltage load shedding scheme based on a static load model may cause the analysis inaccurate is pointed out on the equivalent Thevenin circuit.Then,the dynamic voltage stability margin indicator is derived through local measurement.The derived indicator can reflect the voltage change of the key area in a myopia linear way.Dimensions of the optimal problem will be greatly simplified using this indicator.In the end,mathematical model of the centralized load shedding scheme is built with the indicator considering load characteristics.HSPPSO is introduced to slove the optimal problem.Simulation results on IEEE-39 system show that the proposed scheme display a good adaptability in solving the under-voltage load shedding considering dynamic load characteristics. [Copyright &y& Elsevier]

The new principle of the organisation of working process of the combined supercharging system of transport diesel with the Cascade Pressure Exchanger (CPE) has been described. It allows considerably to raise level of forcing of the engine by supercharging at the expense of expansion of effective air supply area and coolings of supercharging air to temperature below an ambient. Substantive postulates of imitating model of work of combined engine(CICE) have been stated. Some results of calculation-experimental investigations of supercharging system of the engine 6ЧH12/14 have been given. It confirms the possibility of the essential improvement tractive and fuel-economic factors of the transport installations in broad range of the working conditions. [ABSTRACT FROM AUTHOR]