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How fast is fast? : science projects with speed
\"Simple science experiments about measurement of speed using everyday items with many experiments that can be turned into science fair projects.\"-- Provided by publisher.
Book
Study on the Rotor Strength of High-Speed Permanent Magnet Motor Considering the Influence of Assembly Pressing Force
In engineering application, the hot press assembly technology is often used to improve the stability of the rotor structure, but the conventional design methods cannot effectively evaluate the influence of this process on the rotor strength, which easily causes the rotor strength to exceed its safety margin range, and seriously it will lead to the failure of the rotor structure. This paper takes the cylindrical magnet surface-mounted high-speed permanent magnet synchronous motor rotor as the research object. Firstly, the influence of the assembly pressing force on the rotor stresses and interference is analyzed; then, comprehensively considering the assembly pressing force, speed and temperature, the rotor strength’s design method with high structural stability is proposed. Finally, based on the proposed method, the rotor strength of a 100 kW/30,000 rpm high-speed motor is designed, and the feasibility of the design is verified by over-speed experiment.
Journal Article
Bicycle science fair projects
Provides information on creating original science fair projects with a bicycle and a few easy to find household items.
Book
Wind Speed Measurement by an Inexpensive and Lightweight Thermal Anemometer on a Small UAV
Profiling wind information when using a small unmanned aerial vehicle (sUAV) is vital for atmospheric profiling and monitoring attitude during flight. Wind speed on an sUAV can be measured directly using ultrasonic anemometers or by calculating its attitude control information. The former method requires a relatively large payload for an onboard ultrasonic anemometer, while the latter requires real-time flight log data access, which depends on the UAV manufacturers. This study proposes the feasibility of a small thermal anemometer to measure wind speeds inexpensively using a small commercial quadcopter (DJI Mavic2: M2). A laboratory experiment demonstrated that the horizontal wind speed bias increased linearly with ascending sUAV speed. A smoke experiment during hovering revealed the downward wind bias (1.2 m s−1) at a 12-cm height above the M2 body. Field experiments in the ice-covered ocean demonstrated that the corrected wind speed agreed closely with the shipboard wind data observed by a calibrated ultrasonic anemometer. A dual-mount system comprising thermal anemometers was proposed to measure wind speed and direction.
Journal Article
Effect of low-speed drilling without irrigation on osseointegration: an experimental study in dogs
Objective
To study the early phases of osseointegration at implants installed in sites prepared with either high rotational speed with irrigation or low rotational speed without irrigation.
Material and methods
After 3 months from tooth extraction, two implants were installed in one side of the mandible of twelve dogs. The osteotomies were prepared either at 60 rpm without irrigation or at 750 rpm with refrigeration. Biopsies were obtained after 4 and 8 weeks of healing, six animals each period for histological analyses.
Results
After 4 weeks of healing, new bone percentage in contact with the implant surface (BIC%) was 46.6 ± 7.3% and 43.1 ± 6.8% at the low- and high-speed sites, respectively (
p
= 0.345). After 8 weeks of healing, the fractions increased to 60.0 ± 11.1% and 60.2 ± 6.2%, respectively (
p
= 0.753).
Conclusions
Implants installed in sites prepared using either low-rotational drilling without irrigation or high speed with irrigation presented similar amounts of osseointegration.
Journal Article
Numerical and Experimental Studies of Mechanical Performance and Structural Enhancement of Industrial Building SSMRs
In response to the increasing demands of high-technology industrial buildings, renovated standing seam metal roofs (SSMRs) are widely used in the construction of such buildings due to their superior performance regarding heat insulation and waterproofing. However, studies to identify realistic mechanical performance and structural defects in newly applied SSMRs are still limited due to their recent development. In our previous full-scale experiment, the ultimate failure of the roof under wind pressure corresponded to mid-clip failure rather than end clip failure and seam separation; therefore, in this study, the lab-scale experimental programs mainly focused on the mid-clip and the metal roof sheet. Here, the plastic saddle type of the SSMR was chosen as the lab-scale experiment specimen under various loading speeds and angled plastic saddle conditions. The JC material properties were calibrated against experimental results and simulated to predict the dynamic failure response of SSMRs. An additional experimental study was conducted to identify the effect of strengthening SSMRs with wind clips, which showed that 20.77% of the peak load was enhanced after reinforcing the SSMR with wind clips. On the basis of this result, the failure wind speed was computed according to ASCE 7–10 standards with the assumption of a wind clip installed on the corner and edge of the roof panel, indicating that the failure wind speed increased with the wind clip by about 6 to 7 m/s. The current research results suggest a methodology for enhancing the structural performance of renovated industrial building SSMRs.
Journal Article
Research on Regenerative Braking Control Strategy for Single-Pedal Pure Electric Commercial Vehicles
In recent years, with the increasing severity of energy and environmental issues, countries have vigorously developed the new energy automotive industry. To reduce the difficulty of driver operation and increase endurance mileage, this article proposes a regenerative braking control strategy for a single-pedal pure electric commercial vehicle. Firstly, the single-pedal control system’s hierarchical approach was designed to contain the driver’s intention analysis and torque calculation layers. After identifying the driver’s intention, a logic threshold method was used to determine the braking pattern. Then, a fuzzy theory was used, with road gradient, braking strength, and speed as input parameters, and the ratio coefficient of braking force as the output parameter. A hybrid regenerative braking strategy was formulated based on the ideal distribution curve. Finally, the proposed strategy was verified through simulation and a constant-speed car-following experiment. The constant-speed car-following experiment results show that the maximum optimization rate of energy consumption provided by the proposed single-pedal regenerative braking control strategy is 5.81%, and the average optimization rate is 4.33%. This strategy can effectively reduce energy consumption and improve the economic performance of single-pedal pure electric commercial vehicles.
Journal Article
Active flow control of jet mixing using steady and pulsed fluid tabs
Flow control techniques for increasing the rate of jet mixing in axisymmetric nozzle flows have been investigated. A combination of water tunnel and high-speed airflow facilities is used to assess the near-field jet behaviour. Solid tabs, steady fluid tabs (i.e. discrete radially discharged control jets located close to the core jet exit), and pulsed fluid tabs are compared. The effect of fluid tab velocity amplitude, pulse rate, and pulse phase are studied using open-loop control. The measurements indicate that fluid tabs generate a similar streamwise vortex formation process (and hence display increased mixing) as previously observed in solid-tabbed nozzle flows. In incompressible testing the mixing effectiveness with a pair of pulsed fluid tabs 180° out-of-phase was as good as a twin solid tab nozzle for a control jet flowrate of only 0.5 per cent of the primary (core) jet flow. In preliminary high-speed testing similar benefits of fluid tabs over solid tabs were observed. Further study of pulsed fluid tabs is recommended; they have the attractive performance benefit that they can be easily switched off when not needed and offer increased flexibility as the basis of an optimized active control jet mixing device.
Journal Article
Modeling and multi-objective optimization of cutting parameters in the high-speed milling using RSM and improved TLBO algorithm
The main purpose of the present paper is to study the cutting parameter optimization technology by combining the response surface methodology (RSM) with the improved teaching–learning-based optimization (ITLBO) algorithm to obtain the best cutting parameters under multi-objective conditions. Considering the factors of cutting parameters which affect cutting force and surface roughness such as cutting speed, feed per tooth, axial depth of cut, and radial depth of cut, a series of milling experiments are carried out based on four-factor and three-level full factorial experiment design to measurement the cutting force and surface roughness. Based on the collected experimental results, a cubic polynomial regression prediction model for cutting force and surface roughness were established based on the RSM, respectively. Experiments verify that the error of the cutting force prediction model is 0.2–8.04% and 1.36–5.86% for the error of the surface roughness prediction. RSM model is further interfaced with the ITLBO algorithm to optimize the cutting parameters for the multi-objective of cutting force, surface roughness, and processing rate. The optimization experiment results show that cutting force increased by 2.70%, surface roughness decreased by 6.63%, and material removal rate has increased by 49.42%. It indicates that the cutting parameter optimization method based on RSM–ITLBO is effective.
Journal Article