Longer Flight Times Research Articles

Drone Kit-Python for Autonomous Quadcopter Navigation

Using Python scripts over the MAVLink protocol, developers can use the open-source DroneKit Python software framework to enable autonomous drone operations. This framework provides excellent flexibility and power to facilitate automated drone control. The built quadcopter has an X configuration and uses a DJI F450 frame with some modifications. Interestingly, the drone has legs made of aluminum on both sides to help with smooth takeoffs and landings. The frame is 45 cm diagonal length and 30 cm vertical height. The drone was given an additional weight in a 15 x 18 x 12.5 cm box. The propeller used in this investigation is a 9x6 carbon-based model. The x2216 1400kV brushless motor that is being used is from Sunnysky, and it comes with an Electronic Speed Controller (ESC) with a 30A rating. A 4-cell 14.8V Lithium-Polymer (Li-Po) battery with a 7200mAh capacity powers the drone. Apart from that, the drone weighs 1573g in total. The results are obtained by self-measurement and flight measurement data (FMU). Six attempts were made, and the results showed that the second flight had the longest flight time and the highest altitude. In particular, the Flight Measurement Unit (FMU) reported that the flight lasted 81 seconds and reached an altitude of 0.93 meters. In contrast, the self-measurement data reported that the flight lasted 85 seconds and reached an altitude of 1.5 meters.

GreatBlue: a 55-Pound Vertical-Takeoff-and-Landing Fixed-Wing sUAS for Science; Systems, Communication, Simulation, Data Processing, Payloads, Package Delivery, and Mission Flight Performance

As small, uncrewed systems (sUAS) grow in popularity and in number, larger and larger drone aircraft will become more common–up to the FAA limit of 55 pound gross take-off weight (GTOW) and beyond. Due to their larger payload capabilities, longer flight time, and better safety systems, autonomous systems that maximize CFR 14 Part 107 flight drone operations regulations will become more common, especially for operations such as imagery or other data collection which scale well with longer flight times and larger flight areas. In this new paper, a unique all-electric 55-pound VTOL transition fixed-wing sUAS specifically engineered for scientific data collection named “GreatBlue” is presented, along with systems, communications, scientific payload, data collection and processing, package delivery payload, ground control station, and mission simulation system. Able to fly for up to 2.5 hours while collecting multispectral remotely-sensed imagery, the unique GreatBlue system is shown, along with a package delivery flight example, flight data from two scientific data collection flights over California almond fields and a Utah Reservoir are shown including flight plan vs. as-flown.

Impacts of Wearable Resistance Placement on Running Efficiency Assessed by Wearable Sensors: A Pilot Study.

Wearable resistance training is widely applied to enhance running performance, but how different placements of wearable resistance across various body parts influence running efficiency remains unclear. This study aimed to explore the impacts of wearable resistance placement on running efficiency by comparing five running conditions: no load, and an additional 10% load of individual body mass on the trunk, forearms, lower legs, and a combination of these areas. Running efficiency was assessed through biomechanical (spatiotemporal, kinematic, and kinetic) variables using acceleration-based wearable sensors placed on the shoes of 15 recreational male runners (20.3 ± 1.23 years) during treadmill running in a randomized order. The main findings indicate distinct effects of different load distributions on specific spatiotemporal variables (contact time, flight time, and flight ratio, p ≤ 0.001) and kinematic variables (footstrike type, p < 0.001). Specifically, adding loads to the lower legs produces effects similar to running with no load: shorter contact time, longer flight time, and a higher flight ratio compared to other load conditions. Moreover, lower leg loads result in a forefoot strike, unlike the midfoot strike seen in other conditions. These findings suggest that lower leg loads enhance running efficiency more than loads on other parts of the body.

Performance Level Affects Full Body Kinematics and Spatiotemporal Parameters in Trail Running-A Field Study.

Trail running is an emerging discipline with few studies performed in ecological conditions. The aim of this work was to investigate if and how biomechanics differ between more proficient (MP) and less proficient (LP) trail runners. Twenty participants (10 F) were recruited for a 9.1 km trail running time trial wearing inertial sensors. The MP athletes group was composed of the fastest five men and the fastest five women. Group differences in spatiotemporal parameters and leg stiffness were tested with the Mann-Whitney U-test. Group differences in joint angles were tested with statistic parametric mapping. The finish time was 51.1 ± 6.3 min for the MP athletes and 60.0 ± 5.5 min for the LP athletes (p < 0.05). Uphill sections: The MP athletes expressed a tendency to higher speed that was not significant (p > 0.05), achieved by combining higher step frequency and higher step length. They showed a tendency to shorter contact time, lower duty factor and longer flight time that was not significant (p > 0.05) as well as significantly lower knee flexion during the stance phase (p < 0.05). Downhill sections: The MP athletes achieved significantly higher speed (p < 0.05) through higher step length only. They showed significantly higher knee and hip flexion during the swing phase as well as higher trunk rotation and shoulder flexion during the stance phase (p < 0.05). No differences were found with respect to leg stiffness in the uphill or downhill sections (p > 0.05). In the uphill sections, the results suggest lower energy absorption and more favorable net mechanical work at the knee joint for the MP athletes. In the downhill sections, the results suggest that the more efficient motion of the swing leg in the MP athletes could increase momentum in the forward direction and full body center of mass' velocity at toe off, thus optimizing the propulsion phase.

Comparative Analysis of Cosmic Radiation Exposure Dose Due to the Russian Detour Route

Since the World Health Organization (WHO) officially announced a global pandemic on March 12, 2020, the aviation industry in the world has been experiencing difficulties for a long time. Meanwhile, the Ukraine war broke out in February, and from March 15, domestic airlines must operate air routes bypassing Russian airspace despite the longer flight time. Therefore, as the flight time increases, the cosmic radiation exposure dose of the crew members is also expected to increase. Here we compare the radiation exposure dose between the route doses for the eastern United States and Europe before and after the detour route usage. Through the comparison analysis, we tried to understand how cosmic radiation changes depending on the flight time and the latitude and which one contributes more. We expect that this study can be used for the policy update for the safety management of cosmic radiation for aircrews in Korea.

Alternative approach to the DART mission by the use of gravity assist maneuvers with the Moon and solar sails

The formation of our Solar System and planetary defense strategies are among the priorities to be investigated in the next years by the space science community. As in-situ missions to small bodies (as comets and asteroids) are options to conduct these investigations, this paper proposes a combination of methodologies to produce low-cost transfers to near-earth asteroids (NEAs). Low-cost trajectories derived from retrograde periodic orbits around {L}_{1} are taken as a starting point for the escape of the Earth-Moon system and, as the vehicle exits the sphere of influence of Earth, the deployment of an adjustable solar sail guarantees the interception of the target in a predetermined position and time of flight. Different sail loadings (164, 61 and 30 g/m2) are tested and a case study to the NEA 65,803 Didymos is presented. The results show economies in the velocity increments required by the mission up to 8.48%, although a longer time of flight might be needed depending on the sail loading.

E-BALLOON: A PROPELLERLESS FLIGHT CONTROL SYSTEM

An alternative to drones, this paper seeks out the feasibility of using a controlled propeller-less balloon to see potential alternatives or assistance to unmanned flight development. Making use of lighter than air gasses such as helium as an alternative to horizontal flight in lieu of propellers, which conserve energy and offset the weight of the engine. This research aims to design a propellerless balloon that can be controlled remotely using a microcontroller system. This e-balloon will greatly minimize the noise produced by an unmanned aerial vehicle and can be used in surveillance systems and related operations. We constructed a controllable navigation system that makes use of radio-frequency communication and microcontrollers to control the flight path and navigation of the balloon without propellers. A big balloon, made up of mylar, was made that served as the main balloon that can be controlled using microcontrollers. A nano Arduino is connected and used under the balloon to control the rudder. An extra smaller balloon is also used to control the up and down movement of the balloon. This extra balloon is then released before the landing procedures of the main balloon. The RF transceiver NRF24L01 connected to the nano Arduino is used to control the rudder and the extra balloon at different distances. The main objective of the propeller-less balloon is to control the flight of the balloon from point A to point B. Multiple tests were conducted with different flight plans from point A to point B. Tests were conducted under controlled environmental parameters and achieved successful results in flight missions. The tests resulted in an accuracy of 85%, meaning the test flights and flight paths were completed successfully 17 times out of 20 tests. The design of a propellerless balloon is one of the main contributions of this research. This proposed system can minimize the weight of the UAV, the noise produced during flight, and the cost of fuel needed during each mission. It can also have a longer flight time and eliminate the problems of energy sources in UAVs. Keywords: Balloon, Flight Control, Microcontroller, Aerodynamics DOI： https://doi.org/10.35741/issn.0258-2724.58.1.43

Kinematics Analysis of Male Runners via Forefoot and Rearfoot Strike Strategies: A Preliminary Study

This study aimed to explore the kinematic characteristics of males using various foot landing strategies. The participants were fifteen male students from Physical Education College, Huaibei (non-professional runners, who did not have a fixed running landing strategy mode) (mean height = 178.20 cm; mean weight = 67.60 kg; mean age = 19.40 years). In this experiment, the running model of different foot landing strategies (forefoot strike, FFS and rearfoot strike, RFS) were analyzed using two high-speed cameras captured simultaneously at a sampling rate of 100 Hz. According to the results, the runners with better sports performance have shorter contact time, longer flight time, lower duty factor, larger stride angle, faster V COG, greater A COG, and knee and ankle angles which were crucial kinematics factors to enhance the running. Therefore, this study recommends that coaches or researchers can use photography to analyze novice runners who do not have a fixed landing pattern when running with RFS, the characteristics of running style was closely related to the flight times, and running with FFS was closely related to the stride angle.

Transfer between the planar Lyapunov orbits around the Earth–Moon L2 point using low-thrust engine

We present a study of the low-thrust transfer problem near the secondary body in the Earth–Moon circular restricted three-body problem (CRTBP). Based on the Pontryagin maximum principle, the time-optimal, energy-optimal and fuel-optimal transfers between the planar Lyapunov orbits around the L2 point of the Earth–Moon system are constructed as a two-point boundary value problem (TPBVP). A criterion for identifying the best trajectory is also described. The Lyapunov orbit structure is used to deal with the potential difficulties of initial guess. As a result, the final transfer trajectory follows a multi-revolution structure, which takes a long time of flight. The homoclinic connection configuration is investigated by introducing the relevant invariant manifolds, allowing for faster transfer and less fuel consumption in the same case. It is designed a linear time-varying model predictive control (MPC) algorithm to perform trajectory tracking in the presence of initial orbit error and deviations in engine operation. Numerical simulations show the efficiency and practicability of the optimal transfer trajectory design strategy and trajectory tracking controller proposed in this paper for future lunar exploration missions.

Performing Meaningful Movement Analysis From Publicly Available Videos Using Free Software – A Case of Acrobatic Sports

This paper illustrates how movement analysis could be performed using publicly available videos and freeware to generate meaningful information for sports practitioners and researchers. Using acrobatic sports as a case, we performed kinematic analysis on 206 YouTube videos of high-level competitions in diving and gymnastics using Kinovea. Results revealed good to excellent inter-rater reliability of variables analyzed. Significant differences in angular speed (p &amp;lt; 0.001, η2p = 0.213) and flight time (p &amp;lt; 0.001, η2p = 0.928) were found among eight different events. Divers had longer flight time (p &amp;lt; 0.001, η2p = 0.569) and were somersaulting faster than gymnasts (p = 0.021, η2p = 0.026). Angular speed was higher in tuck than pike somersaults (p &amp;lt; 0.001, η2p = 0.214). Shorter the flight time was significantly correlated with faster angular speed (rho = −0.533, p &amp;lt; 0.001) in gymnastics events. Coaches and scientists can consider applying the proposed method to monitor the athletes’ performance and to identify errors (e.g., insufficient flight time). The kinematics measurements can also be used to guide the transition plan across different apparatus and categories (e.g., 10-m platform to 3-m springboard). In conclusion, the present study highlights the potential of using readily available information and open-source freeware to generate scientific data for sports applications. Such data analysis approach can accommodate a wide range of video qualities, is easily accessible, and not restricted by situations such as social distancing, quarantine, lockdown or other restrictive measures.

A Review of Security Incidents and Defence Techniques Relating to the Malicious Use of Small Unmanned Aerial Systems

Critical national infrastructure sites, such as airports and nuclear facilities, have been subject to a number of airspace breaches from malicious unmanned aerial systems (UASs) in recent years. Not only can these incidents cause major disruptions, but they can have significant financial consequences. This article conducts a short review of security incidents caused by the malicious use of small UASs at airports and nuclear facilities. We conclude that the number of incidents of concern remain high and suggest the increased use of UAS with longer flight times, indicating a move away from commercially available platforms, which have limited flight times. The detection and classification methods presented in this review each have strong benefits but this is not withstanding their own challenges. Hence, this review recommends that more than one sensor type are considered in parallel for live systems. A comprehensive detection and classification system must extend further than typical commercially available platforms if we are to fully realize the threat. We also conclude that while successful countermeasure methods do exist there still remains many policy and legal challenges ahead for their implementation.

Large contribution from worship activities to the atmospheric soot particles in northwest China

Worship activities like burning joss paper during the Chinese Hanyi festival is a common, traditional custom in northwest China. However, the pollutants of e.g., soot particles, released from joss paper burning and the corresponding impacts on urban air quality were poorly investigated, which can be a particular concern since these activities are conducted in an uncontrolled manner. In this study, a long time-of-flight (LToF) soot particle aerosol mass spectrometry (SP-AMS) was deployed to characterize the refractory black carbon (rBC) emitted from the joss paper burning, as well as crop residue, coal combustion, and traffic during the Hanyi Festival in mid-November 2020 in the northwestern city of Xi'an in China. Large difference (from <5% to >100%) in the fragmentation patterns (Cn+) for the measured rBC from different source emissions were found when compared to the reference Regal Black. Using the receptor model of positive matrix factorization (PMF) with the multilinear engine (ME-2) algorithm, the obtained rBC mass spectra were used as the anchoring profiles to evaluate the emission strengths of different source types to the atmospheric rBC. Our results show that the burning of joss paper accounted for up to 42% of the atmospheric rBC mass, higher than traffic (14–17%), crop residue (10–17%), coal (18–20%) during the Hanyi festival in northwest China. Moreover, we show that the overall air quality can be worsened due to the practice of uncontrolled burning of joss paper during the festival, which is not just confined to the people who do the burning. Although worship activities occur mainly during festival periods, the pollution events contributed by joss paper burning may pose an acute exposure risk for public health. This is particularly important since burning joss paper during worship activities is common in China and most Asian countries with similar traditions.

Comparison of Spatiotemporal Parameters between Athletes and Non-Athletes at Upslope Running

Upslope locomotion is challenging in our day to day life for which neuromuscular system have to work extraordinarily [1]. Despite increasing popularity of trail running, trekking, hiking that include various slope inclination, the majority of running biomechanics studies have only considered level running [2]. To understand the control of human locomotion better, physiological and biomechanical variables related to incremental slopes running during the gait cycle is imperative. Several studies have examined upslope running but the results are inconclusive [2-6]. Running at higher upslope inclination showed higher step frequency [2] and reduced stride length [6]. Conversely some studies examining various parameters did not observe any difference between level and uphill running at constant speed [4,7]. Previous studies comparing spatiotemporal characteristics in varying level of trained runners [5,8-10] indicated longer flight time and better adaptation in elite runners compared to amateur runners with increased inclination [5]. Conversely, a study showed no difference in adaptation of spatiotemporal characteristics between amateur and highly trained athletes while running upslope at given speed [2]. This leaves questions whether non-athletes adapt to different slopes gradient in the same way as trained athletes. We aimed to determine the effect of different slope gradients on spatiotemporal gait parameters between athletes and non-athletes during running on an instrumented treadmill.

Design and Implementation of a Tether-Powered Hexacopter for Long Endurance Missions

A tether-powered unmanned aerial vehicle is presented in this article to demonstrate the highest altitude and the longest flight time among surveyed literature. The grid-powered ground station transmits high voltage electrical energy through a well-managed conductive tether to a 2-kg hexacopter hovering in the air. Designs, implementations, and theoretical models are discussed in this research work. Experimental results show that the proposed system can operate over 50 m for 4 h continuously. Compared with battery-powered multicopters, tether-powered ones have great advantages on specific-area long-endurance applications, such as precision agriculture, intelligent surveillance, and vehicle-deployed cellular sites.

Non-destructive detection of moisture content for Ginkgo biloba fruit with terahertz spectrum and image: A preliminary study

Ginkgo biloba fruit is a typical recalcitrant seed, which is apt to dehydrate and harden, thus losing its activity, edibility and medicinal value during storage. The non-destructive detection method was investigated for monitoring moisture content (MC) variation of Ginkgo biloba fruit based on the sensitivity of terahertz (THz) wave to liquid water. The THz spectra and images of intact Ginkgo biloba seeds and their slices with different MC were collected. The influence of MC on THz wave was analyzed through the time domain spectra and frequency signal of absorption coefficients. The seed with higher MC achieved lower amplitude of time domain spectrum and longer flight time because of strong absorption of MC to THz radiation. The exponential equations were developed between MC and absorbance coefficients at characteristic frequencies of 1.68, 2.66, 2.79 and 3.02 THz with determination coefficients (R2) of 0.99 and root mean square error of cross validation (RMSECV) of 0.3–0.4 %, respectively. In addition, the gap between seed kernel and shell appeared because the seed kernel shrank due to water loss with the decrease of MC, and the model between the gap ratio and MC was established by THz image with R2 of 0.95 and RMSECV of 4.06 %, respectively. The results indicated that THz spectroscopy and image provided a new method for monitoring MC of Ginkgo biloba seed.

Full-state modeling and nonlinear control of balloon supported unmanned aerial vehicle

PurposeThe purpose of this study is to provide the full-state mathematical model and devise a nonlinear controller for a balloon-supported unmanned aerial vehicle (BUAV).Design/methodology/approachNewtonian mechanics is used to establish the nonlinear mathematical model of the proposed vehicle assembly which incorporates the dynamics of both balloon and quadrotor UAV. A controllable form of the nine degrees of freedom model is derived. Backstepping control is designed for the proposed model and simulations are performed to assess the tracking performance of the proposed control.FindingsThe results show that the proposed methodology works well for smooth trajectories in presence of wind gusts. Moreover, the final mathematical model is affine and various nonlinear control techniques can be used in the future for improved system performance.Originality/valueMulti-rotor unmanned aerial vehicles (MUAVs) are equipped with controllers but are constrained by smaller flight endurance and payload carrying capability. On the contrary, lighter than air (LTA) aerial vehicles have longer flight times but have poor control performance for outdoor operations. One of the solutions to achieve better flight endurance and payload carrying capability is to augment the LTA balloon to MUAV. The novelty of this research lies in full-order mathematical modeling along with transformation to controllable form for the BUAV assembly.

Polycyclic aromatic hydrocarbons from cooking emissions

Air pollution studies have often overlooked the contribution from cooking to the particle-bound polycyclic aromatic hydrocarbons (PAHs) in the ambient environment, despite cooking emissions have been identified as an important source of organic aerosol in most urban areas, known as the cooking-like organic aerosol factor (i.e., COA). In this study, a Long-Time-of-Flight (LToF) soot particle aerosol mass spectrometer (SP-AMS) was deployed to evaluate the impact of cooking emissions on outdoor particle-bound PAHs levels during a summer campaign in 2019 in Xi'an China. Combined with the robust receptor model, cooking emission was found to be the major source of ambient PAHs, on average, accounting for 90% of PAHs, 9 times higher than traffic (10%). The ambient cooking PAH profile was well correlated (r2 of 0.87) with that for frying oil fume, suggesting cooking oil was the major source of PAHs instead of the food being cooked. We further evaluated the health risk associated with the cooking PAHs and estimated the cooking PAH levels in some of the major cities in the world where COA factor has been reported. The results show the particle-bound PAHs from cooking can be an important source of ambient PAHs in most Chinese cities. The findings from this study hold important implications for public health and are informing for policymakers.

Primary and Secondary Organic Nitrate in Northwest China: A Case Study

Particle-bound organic nitrate is ubiquitous in the atmosphere, but its primary emission and secondary formation processes are poorly understood and are, therefore, generally ignored in models. In this study, based on the ambient measurements and a series of combustion experiments, we found that the nitrate functionality from organic nitrate (primary + secondary) accounted for 20%–53% of the total NO3 signal measured with a long-time-of-flight (LToF) soot particle aerosol mass spectrometer (SP-AMS) in northwestern China in mid-November 2020. In particular, secondary organic nitrate accounted for 17% and 36% of the measured NO3 during the haze and reference periods, respectively. It was further estimated that secondary organic nitrate, on average, accounted for 46% of the total organic matter (or 18% of PM2.5) during the haze period, representing a significant portion of the secondary organic aerosol, while primary organic nitrate, mostly from biomass burning, was estimated to account for 8%–9% of the total organic matter (3%–5% of PM2.5). Moreover, we showed that photochemical (OH-initiated + elevated NO2) formation of organic nitrate was probably a more important pathway than the nighttime chemistry (NO3 initiated), which is in great contrast to that in European areas where nighttime chemistry was found to be the dominant pathway.

A Novel Mini Jet Engine Powered Unmanned Aerial Vehicle: Modeling and Control

Significant progress has been made in recent years on personal air vehicles (PAVs), which offer independent and autonomous urban transportation. On-demand parcel delivery drones and heavy-lift drones are gaining serious attention. Although various designs for these systems have been put forward, they still have not reached sufficient maturity. The current systems provide somehow satisfactory operation, but many of these systems are limited in payload capacity and flight duration, and not suitable for future operations. In this paper, we propose a novel thrust system that uses multiple mini jet engines. Unlike electric motors, the jet engine thrust cannot vary rapidly. This led us to design and develop a thrust vectoring system for each jet engine. This proposed system has the potential to enable drones to carry more payload and achieve longer flight times. This paper discusses the design and modeling of the system as well as the stabilization algorithms that satisfactorily stabilize the proposed system. We presented that due to motor lag, thrust variations cannot stabilize the vehicle. We showed that the use of a thrust vectoring mechanism with LQR-based controller can overcome the effects of motor lag and stabilize the vehicle, successfully.

Long-term effects of school barefoot running program on sprinting biomechanics in children: A case-control study

BackgroundThe acute changes of running biomechanics in habitually shod children when running barefoot have been demonstrated. However, the long-term effects of barefoot running on sprinting biomechanics in children is not well understood. Research questionHow does four years of participation in a daily school barefoot running program influence sprint biomechanics and stretch-shortening cycle jump ability in children? MethodsOne hundred and one children from barefoot education school (age, 11.2 ± 0.7 years-old) and 93 children from a control school (age, 11.1 ± 0.7 years-old) performed 50 m maximal shod and barefoot sprints and counter movement jump and five repeated-rebound jumping. To analyse sprint kinematics, a high-speed camera (240 fps) was used. In addition, foot strike patterns were evaluated by using three high-speed cameras (300 fps). Jump heights for both jump types and the contact times for the rebound jump were measured using a contact mat system. Two-way mixed ANOVA was used to examine the effect of school factor (barefoot education school vs control school) and footwear factor (barefoot vs shod) on the sprinting biomechanics. ResultsSprinting biomechanics in barefoot education school children was characterised by significantly shorter contact times (p = 0.003) and longer flight times (p = 0.005) compared to control school children regardless of footwear condition. In shod sprinting, a greater proportion of barefoot education school children sprinted with a fore-foot or mid-foot strike compared to control school children (p < 0.001). Barefoot education school children also had a significantly higher rebound jump height (p = 0.002) and shorter contact time than control school children (p = 0.001). SignificanceThe results suggest that school-based barefoot running programs may improve aspects of sprint biomechanics and develop the fast stretch-shortening cycle ability in children. In order to confirm this viewpoint, adequately powered randomised controlled trials should be conducted.