Speed Characteristics Research Articles

Mixed Traffic Behaviour in Heavy Flow: Two-Lane Road Insights

The current paper outlines a comprehensive methodology for modeling speed data on two-lane roads during periods of heavy traffic characterized by heterogeneous vehicle types. In such scenarios, the presence of diverse vehicle types causes a significant departure from the normal speed distribution model. This deviation becomes particularly pronounced during heavy traffic flows due to the frequent interactions among vehicles within the traffic stream. Consequently, there arises a necessity to develop a modeling approach specifically tailored to such flow conditions. Drawing upon empirical data collected from a major intercity road in India, this study uncovers a notable skewness in speed data under heavy traffic conditions. This skewness primarily stems from the formation of vehicle platoons within the traffic stream, exerting a substantial influence on their speed characteristics. By scrutinizing the distribution of this data, the study concludes that a logarithmic transformation effectively aligns with the assumption of normality. This assertion is supported by various goodness-of-fit metrics, affirming the suitability of the proposed modeling approach for capturing the intricacies of speed behavior in heterogeneous traffic environments.

BGOA-TVG: Binary Grasshopper Optimization Algorithm with Time-Varying Gaussian Transfer Functions for Feature Selection.

Feature selection aims to select crucial features to improve classification accuracy in machine learning and data mining. In this paper, a new binary grasshopper optimization algorithm using time-varying Gaussian transfer functions (BGOA-TVG) is proposed for feature selection. Compared with the traditional S-shaped and V-shaped transfer functions, the proposed Gaussian time-varying transfer functions have the characteristics of a fast convergence speed and a strong global search capability to convert a continuous search space to a binary one. The BGOA-TVG is tested and compared to S-shaped and V-shaped binary grasshopper optimization algorithms and five state-of-the-art swarm intelligence algorithms for feature selection. The experimental results show that the BGOA-TVG has better performance in UCI, DEAP, and EPILEPSY datasets for feature selection.

Wind turbine load optimization control and verification based on wind speed estimator with time series broad learning system method

AbstractWith the rapid development of wind power, the power performance and mechanical load characteristics of wind turbine are simultaneously considered and focused. Normally, wind turbine senses the incoming flow characteristics through the nacelle mounted anemometer, due to the inability to perceive the characteristics of wind speed in advance, the control strategy makes the wind turbine itself to be at a passive state during the operation process. In this paper, a wind turbine mechanical load optimization control strategy based on an accurate wind speed estimator with time series Broad Learning System Method (BLSM) is designed, simulated and also verified. Firstly, the basic control theory of the BLSM and also a mechanical load optimization controller is designed. Then the OpenFAST is used to conduct a full‐life cycle simulation comparison study on mechanical load characteristics of wind turbine before and after the implementation of the optimization control strategy. Finally, a field empirical mechanical load test is performed on the wind turbine, which is configured with BLSM mechanical load optimization control technology. The findings indicate that the implementation of this control strategy can significantly mitigate the ultimate and fatigue loads of wind turbines, particularly the fatigue loads of tower base tilt and roll bending moments, with a reduction rate of approximately 6.2% and 4.3%, respectively.

Research on high fidelity modelling and optimum designing of an adaptive cycle engine's starting process

An adaptive cycle engine is an evolutional aero-engine that can achieve low fuel consumption and high efficiency by adjusting the thermodynamic cycle; however, few studies have been conducted on adaptive cycle engine performance at low speeds. A high-fidelity ground starting model of an adaptive cycle engine is established by correcting the low speed characteristics of the components, while considering the effects of rotor inertia, volume, combustion efficiency, and the thermal inertia of the combustor and turbine. By employing a physically enhanced prediction method, three operating states of the compressor at low speeds are obtained: compressor, stirrer, and turbine state. The matching mechanism of the adaptive cycle engine and the detailed influence of the variable geometries on the engine's performance during the starting process are explored. The study shows that the third bypass duct has little effect on the engine starting time, and opening the mode select valve can reduce the starting time. Compared with the initial settings, the starting time decreases by 3.98 s after optimization with the variable geometries. The detailed impact of the variable geometries on the engine's starting performance provides an engineering reference value for the control strategies.

Design of Proton Exchange Membrane Hydrogen Fuel Cell Control System Based on Response Speed and Uncertainty Characteristics

In an effort to settle the issue of poor control accuracy caused by external interference (such as environment and load changes) in the control process of hostage switch film fuel cell, a PEMFC control channel design method based on response speed and uncertainty characteristics was proposed in this study. The channel structure model and parameter model of PEMFC operate channel are established, and its response speed and uncertainty characteristics are analyzed. The proportional integral-differential (PID) operate method is used to obtain the signal model of the current vector data under the optimal operate state, and the AC coupling of the capacitor is used to suppress the loss. The simulation results show that this method can improve the stability and convergence of PEMFC, effectively correct the error, and the operate accuracy reaches 99%.

Comparison and analysis of starting performance of PMSM with different rotor structures

In this paper, the electromagnetic fields of PMSM with four different rotor structures are analyzed by the finite element method, and the distribution of magnetic field lines is compared. Then the asynchronous starting process of PMSM is studied. The starting process of four kinds of permanent magnet synchronous motors with no load and load is simulated and analyzed, and the characteristics of speed, torque, and phase current are obtained. These studies can provide references for the starting design of permanent magnet synchronous motors in practical applications. Therefore, a more reliable and efficient motor starting process is realized, which provides a basis for further structural design of permanent magnet synchronous motor.

Combined effect mechanism of linear loading and disturbance with different amplitudes on sandstone

To comprehend the stress state and response characteristics of materials under complex conditions, researchers have decomposed stress states into fundamental paths and investigated diverse path combinations. To ensure comparability, four identical samples were carefully selected from a pool of 100 samples using ultrasonic tests based on the wave speed and waveform characteristics. These samples underwent specially designed stress paths to analyze the combined effects of linear loading and perturbation. Our result analysis centred on the perturbation amplitude and stress levels during composite action, revealing intricate relationships between the stress levels, strain, and nonlinear/linear energy evolution under complex stress paths. Simultaneously, 3D surface fractures were precisely reconstructed using the YOLOv5 and FAST feature point detection algorithms, elucidating the evolving patterns of the fractures. As a result of our study, the rotation trend of the main fracture was validated by integrating mechanics and P-wave reflection rules. Notably, our experimental results closely aligned with the theoretical predictions, showing the reliability of our study. These findings can significantly contribute to guiding safety protocols in the field of underground engineering.

A Climatology of Intensity Change and Translation Speed of Landfalling North American Tropical Cyclones between 1971 and 2020

Abstract In this study, we investigated the translation speed and intensity change characteristics for landfalling North American tropical cyclones (TCs) from 1971 to 2020. We calculated three variables—intensity change, mean translation speed, and translation speed change—prior to each TC landfall and investigated the climatology of these variables for seven coastal segments. We found that lower-latitude segments generally had greater positive intensity changes prior to landfall, and higher-latitude segments had greater translation speeds. Longitude primarily influenced translation speed changes, with landfalling TCs along the Atlantic coast of the United States notably accelerating prior to landfall. Temporal trends in each of these variables were inconsistent geographically, but most segments showed an increase in positive intensity changes over time, demonstrating the increasing likelihood of intensifying TCs before landfall in recent years. We defined extreme intensification and extreme weakening as the 90th and 10th percentile of all landfalling TC intensity changes, respectively. We found that extreme intensification and weakening have been increasing and decreasing in frequency, respectively. Results from this study can be used in a variety of future applications, including in operational forecasting and model production, and provide a baseline for climate attribution studies investigating extreme intensity change events. Significance Statement Landfalling tropical cyclones pose significant hazards to life and property in coastal regions across North America. This study develops a comprehensive climatology of intensity change and translation speed of tropical cyclones during the final 36 h prior to landfall. We found that incidences of extreme intensification and weakening of landfalling North American tropical cyclones have increased and decreased, respectively, since 1971. We also identify lower-latitude coastal segments tend to average faster translation speeds that higher-latitude segments, while segments on the east coast of the United States tended to average a greater acceleration. These results show the importance of looking at tropical cyclone characteristics regionally and provide a useful baseline to assess how tropical cyclone risk is changing in a warming climate.

The Characteristics of the Deformation of a Feeding Roller with Double V-Wings Honeycomb under Driven Modes with Different Rotation Rates and Axial Compressions

In this work, the roller-shaped double V-wing honeycomb (DVWH) structure was used as the object, which was designed for forest harvesting machines. The deformation characteristics of its rotation under a specific compression were studied during the feeding process for the steel feeding roller used in the traditional combined harvesting machine for trees, which is prone to damaging the wood. The compression rate (10%–15%) and rotational speed (100 mm/s–320 mm/s) were used to analyze the relationship between compression rate, rotational speed, and deformation characteristics. The deformation characteristics, characterized by equivalent stress, radial displacement sensitivity, and energy absorption efficiency, were analyzed. The results show that the deformation characteristics of the roller-shaped DVWH structure under driven mode were more sensitive to compression rate and less sensitive to changes in rotational speed. There was a positive correlation between the equivalent stress of the node and the compression rate. The peak equivalent stress of the outermost node at 10% and 15% compression rates were 111.9 MPa and 230.9 MPa. There was a negative correlation between radial displacement–compression sensitivity and compression rate, and a decrease in radial displacement–compression sensitivity from 10% to 15% compression rate at different nodes ranges from 5% to 22%. The feed performance efficiency (EF) grew from 8.3% to 12.7% for a 1% increase in compression rate.

Understanding the Relationship between Torque, Rotational Speed (RPM), and Tissue Characteristics in Follicular Unit Excision Harvest

Understanding the Relationship between Torque, Rotational Speed (RPM), and Tissue Characteristics in Follicular Unit Excision Harvest

Performance analysis of OTFT with varying semiconductor film thickness for future flexible electronics

The goal of this study was to get a deeper understanding of the intricate impact of organic semiconductor thickness on the performance of devices, using a thorough and meticulous investigation at the microscopic level incorporating the density of defect model using using Silvaco ATLAS TCAD Simulator. The present work thoroughly investigates the relationship between the thickness of semiconductors and important performance parameters, such as hole concentration, electric potential, electric field, and Hole QFL. The comprehensive insights derived from this research not only enhance the comprehension of device physics but also provide a framework for the systematic enhancement of electronic devices. The widespread use of organic thin film transistors (OTFT) in future Flexible electronics, particularly in display and memory circuits, necessitates the incorporation of low voltage, high speed, and low cost characteristics.

Research on the influence of traffic conditions on noise level in the passenger compartment of motor vehicles

The research investigates the noise levels measured in the passenger compartments of several automobiles. These vehicles are powered by various engines, travel on various highways, and function at differing speeds and acceleration. The results are visually processed using specialist software. The study investigates the effects of three major sources of automotive noise: engine operation, tire-road contact, and friction between the car body and the air. The immis noise in the passenger compartment is reported to be mostly impacted by the engine’s operational characteristics (load and speed) at lower speeds. In contrast, as travel speed increases, the noise produced by tire-road contact becomes more substantial, and at greater speeds, the noise produced by the interaction between the car body and the air becomes more significant. As a result, the engine type, tire and road characteristics, vehicle speed, and passenger compartment acoustic insulation are all important elements in influencing noise emission in the passenger compartment.

Research on spatiotemporal distribution characteristics of ship traffic flow in port waters based on AIS data

With the gradual increase of ship traffic, water traffic management has become increasingly important. This paper is based on AIS data and uses the Analytic Hierarchy Process to comprehensively evaluate the relative hazard level of a specific area, in order to determine the relative consequences of regional hazards (RCORH). Next, we will use speed and traffic volume characteristics as indicators to construct a linear regression model for spatial relationship analysis. The research results indicate that the linear regression model proposed in this article can effectively identify areas with high collision risks, which has positive significance for improving the navigation safety management of port waters.

Effects of global warming on drought onset in China

This study investigated the effects of warming on the drought onset in China using meteorological data and soil moisture data from 1980 to 2020. The variation characteristics of drought onset time and onset speed were analyzed systematically. The differences in drought onset time and onset speed during the period 1995–2020 and the period 1980–1994 were compared, and possible impact factors were analyzed. Results indicated that the spatial distribution of drought onset time decreased with an increase in regional wetness in China. In arid regions, onset time at 73 % of sites was over 35 days, and about 13 % was among 60–90 days. In semi-arid and sub-humid regions, the onset time was 25–40 days, and in humid regions, it was 20–30 days. After 1994, namely the significant temperature rise period, the onset time has remarkably shortened in parts of the southern Northeast, North China, the eastern Northwest, the western Southwest, the middle of Tibet, the lower reaches of the Yangtze River, and the coastal region of South China. The shortening was most obvious in sub-humid regions. The greater the warming magnitude, the wetter the region, the faster the drought onset speed. Drought onset speed (γ) was higher in the southern humid region than that in the northern region, and γ for southern Northeast China, northern North China, and eastern Northwest China was higher than that for the rest of North China. After 1994, drought onset speed was accelerated in most regions, especially in the semi-arid and sub-humid regions with precipitation in the range of 300–600 mm. Under the combined effect of increased evapotranspiration and reduced precipitation, the region has been the hot spot with increased drought speed after obvious warming in China.

Research on challenges and solutions in 5G application

5G technology is a new type of wireless communication technology with the characteristics of high speed, low delay, large connection, etc. It brings new opportunities and challenges to economic, social and industrial development. This article focuses on the application and value of 5G technology in smart cities, as well as the opportunities and challenges faced by 5G technology in smart cities. This article uses the method of literature reading and analysis to explore the role and functions of 5G technology in smart cities from the fields of smart homes, smart transportation, smart grids, smart security, etc. and analyzes the application scenarios and cases of 5G technology in smart cities, demonstrating the practical effects and social benefits of 5G technology in smart cities. This article evaluates the opportunities and challenges faced by 5G technology in smart cities, such as policy support, network construction, security, user needs, etc., and provides strategic suggestions for the promotion and application of 5G technology in smart cities. This article aims to improve the knowledge and understanding of 5G technology and smart cities, promote the coordinated development of 5G technology and smart cities, and provide technical support and innovation power for building a new digital, networked, and intelligent city.

Model and Property Analysis for a Ball-Hinged Three-Degree-of-Freedom Piezoelectric Spherical Motor.

Multi-degree-of-freedom piezoelectric motors have the advantages of high torque and resolution, simple structure, and direct drive, which are widely used in robot wrist joints, deep-sea mechanisms, medical equipment, and space mechanisms. To solve the problems of high force/torque coupling degree and ball low stator and rotor bonding strength of the traditional traveling wave type three-degree-of-freedom piezoelectric spherical motor, a new structure of ball-hinged piezoelectric spherical motor is proposed. Through coordinate transformation and force analysis, the driven mathematical model of the spherical motor is given. The model shows that the three degrees of freedom of the motor are coupled with each other. According to the mathematical model of the spherical motor, the mechanical properties of the motor are analyzed by the computer simulation. The results show that the stalling torque coefficient kt has a linear relationship with the friction coefficient ε and the stator preload Fc, has a nonlinear relationship with the stator radius R and the rotor radius r, and increases with the increase of R and decreases with the increase of r. The no-load speed of motor ωn is not related to the friction coefficient ε and the stator preload Fc, and increases with the increase of R and decreases with the increase of r. The anisotropic characteristics of torque and speed of a spherical motor are further analyzed, which lays a theoretical foundation for the drive control of a spherical motor.

Low-wind climatology (1979–2018) over Europe from ERA5 reanalysis

Research on wind speed characteristics is of interest for many disciplines from renewable energy to ecology. Whereas mean values and trends are commonly studied, less attentions is paid to the evaluation of other features such as low-wind conditions. However, there is no clear definition of “low-wind” on the literature. Here we propose the Beaufort scale to characterize low-wind values over Europe through a fixed threshold of 3.3 m/s (“light breeze" category). Climatological (1979–2018) assessment is performed using ERA5 reanalysis hourly data. The limited amount of observational stations indicate a 40-year averaged amount of around 3500 low-wind hours/year, comparable to the corresponding ERA5 reanalysis cells, which shows severe limitations over mountainous areas. The European domain features a strong north–south low-wind hours gradient. Remarkable patterns are obtained over coasts and complex orography regions. Seasonal low-wind variability range around 20–25% for most of the regions, and interannual coefficient of variability from 0.05 to 0.17. Oceanic regions present smaller low-wind values than land areas, with Atlantic and Mediterranean regions behaving differently. The largest annual spells (consecutive) hourly low-wind episodes are within the range from 5 to 10 days, (from 120 to 240 h) over many land areas. Annual mean hourly wind spells typically extend from 15 to 25 h, with more than 200 episodes.

МАТЕМАТИЧЕСКАЯ МОДЕЛЬ ВИХРЕВОГО ДВИЖЕНИЯ ДВУХФАЗНОГО ПОТОКА В ДЕЗИНТЕГРАТОРНОЙ МЕЛЬНИЦЕ

Mathematical models and the results of their numerical calculations play an important role at the modern level of automation of technological processes. The development of mathematical models to determine the design-technological or energy-power parameters of the operation of grinding equipment allows to obtain numerical information about the rational modes of its operation. In this study, numerical results were obtained from calculating a mathematical model of the vortex motion of a two-phase flow for the second stage of grinding depending on the physical and mechanical characteristics of the material being ground (ρp) and the current radius Rk of the grinding chamber of the unit. A method for numerically determining the speed characteristics of unit operating modes for materials with different physical and mechanical properties is presented. In the work, using the analysis of graphs of the sought functions of the mathematical model of the vortex motion of a two-phase flow, the velocity fields are presented in the form of diagrams of the radial, circumferential (tangential) and axial velocity components, which characterize the intensity of the flow dynamics inside the original design of the grinding chamber of the mill. In the process of mathematical modeling, it was established that the radial and circumferential (tangential) components of the two-phase flow velocities at current radii in the range Rk = 0.1–0.2 m reach their maximum values, both for solid particles of the crushed material and for the carrier phase – air. It has been determined that for the circumferential component of the velocity of a two-phase flow in a vortex at Rk = 0.3 m, its maximum is observed for both solid particles and the carrier phase – up = uo = 112.1 m/s.

Highly efficient alkaline aqueous MXene-based asymmetric supercapacitors developed by corrugation-like MoS2 and WS2 modified CMX electrodes

The preparation of superior performance supercapacitors to achieve high energy density, fast charge-discharge speed and long cycle stability characteristics has become the focus of attention to realize their potential as practical energy storage devices. In this paper, a cross-linking CNTs@MXene (CMX) architecture is selected as the negative electrode to increase the contact area with electrolyte, and corrugation-like morphologies MoS2 and WS2 nanoparticles modified CMX (Mo/W-CMX) two-dimensional nanostructure as the positive electrode to provide multiple ion diffusion through its channels structure, which presents good electrochemical performance with high specific capacitance and high energy density in 1 M KOH alkaline electrolyte. CNTs introduced into MXene interface by bridges can effectively impede the re-stacking of MXene, meanwhile, CMX as a matrix can also alleviate the properties degradation caused by the agglomeration and volume strain for sulfides. Benefiting from the facilitate accessibility of ions and high ability of electron transfer, the prepared Mo/W-CMX electrode exhibits a dramatic specific capacitance of 1160 F g−1 at 1 A g−1 and excellent capacitance retention of 88.67% at 25 A g−1 after 10,000 cycles. Meanwhile, the assembled asymmetric supercapacitor (Mo/W-CMX // CMX) presents an ultrahigh energy density of 28.1 Wh kg−1 at the power density of 697.3 W kg−1 and maintains 81.25% cycle stability at 15 A g−1 for 10,000 charge-discharge cycles. It is essential to highlight that the superior performance fabricated asymmetric supercapacitor holds a wide application prospect and very competitive energy-storage values in the upgrading of new high-performance devices.

Удосконалення методики визначення нормативів тягових властивостей автомобіля skoda fabia при стендовому діагностуванні

As you know, the main output parameters characterizing the state of the power unit are the power and torque values. These parameters determine the dynamic qualities of the car, and can also affect fuel consumption and the level of harmful emissions.
 The above parameters are checked using traction roller stands. Such stands allow you to reproduce real speed and load modes. Usually, the traction force on the drive wheels is measured on the stands. It is then easy to calculate the power at a given test speed. Traction force is determined, on the one hand, by the output torque of the engine, on the other hand, by mechanical losses in the transmission. In turn, the moment is determined by the perfection of the combustion process, the complete use of the energy of combustion products, and mechanical losses in the engine itself.
 When there is no reliable, experimentally obtained external speed characteristic of an internal combustion engine, Leiderman's formula is usually used for its approximate construction.
 This technique gives a satisfactory approximation of the dependence of power on revolutions. However, the moment curve is noticeably different from the experimental one. due to the fact that it uses only one experimental point - the maximum power and the corresponding revolutions. Therefore, a refined method of building the external speed characteristic using the example of the SKODA FABIA car is proposed using additional equations that specify the values of the empirical coefficients A, B, C.
 On the basis of the refined external speed characteristics of the engine, the revolutions of the crankshaft are converted into speed, and a graph of the permissible traction force against the speed is drawn according to the derived formula. Standards for diagnostic parameters of the power unit in acceleration mode under partial load are also defined.
 The proposed method of registering engine diagnostic parameters to determine their normative values provides an individual approach to diagnosing the technical condition of cars.