Center Of Gravity Height Research Articles

A comprehensive numerical model for aero-hydro-mooring analysis of a floating offshore wind turbine

This paper presents a comprehensive study of a Floating Offshore Wind Turbine (FOWT), requiring multidisciplinary expertise in floating platform hydrodynamics, mooring system dynamics, and wind turbine aerodynamics. We introduce a fully coupled numerical model, focusing specifically on the NREL's (National Renewable Energy Laboratory's) 5 MW OC4 FOWT. The model is validated through both numerical simulations using the Computational Fluid Dynamics (CFD) based software OpenFOAM and experimental results. Key findings demonstrate the model's accuracy in forecasting the aerodynamic behaviors of the turbine, the platform's response to motions, and the behavior of the mooring system across diverse wind and sea state scenarios. Furthermore, the study enhances the understanding of FOWT's stability and efficiency by examining the influence of different Center of gravity (COG) heights. Results show that reduction in COG height has a minor effect on heave and surge motion but significantly decreases pitch motion and mooring line tension, thereby improving static stability and reducing the impact of wave loads on dynamic responses. Additionally, the results show that this reduction in COG height enhances the aerodynamic power output, suggesting that optimized FOWT designs could achieve improved energy capture efficiency. These insights optimize FOWT design and efficiency, enhancing renewable energy performance.

Development of lateral acceleration prediction models and consistency evaluation criteria for horizontal curves with gradient on two lane rural highways

Objectives The challenge of combined horizontal and vertical highway alignments continues to be a concern in transportation design, particularly regarding truck stability. This study analyses the stability of trucks on horizontal curves combined with ascending or descending gradients using center of gravity (CoG) height and curve geometry as parameters. It also develops models that predict lateral stability of trucks and criteria for evaluating geometric design consistency based on vehicle stability. Method A smartphone application was used to collect real-time data on lateral acceleration experienced by two-axle trucks on curves with gradient. Results Findings show a lower safety margin against rollover on curves with descending gradient compared to ascending ones. Key factors affecting stability are identified as radius and length of horizontal curve, suggesting improvements in rollover stability by increasing these parameters. Geometric design consistency evaluation criteria were developed based on lateral acceleration, categorizing curves with gradient as good, fair, or poor. Predictive models were developed to quantify the impact of CoG height of truck and curve geometry on lateral acceleration, aiding in consistency assessment. Conclusion Outcomes of research will be useful for the design of safer horizontal curves with gradient by prioritizing vehicle stability

Optimizing nitrogen fertilization and planting density management enhances lodging resistance and wheat yield by promoting carbohydrate accumulation and single spike development

AbstractNitrogen fertilizer application and increasing planting density have been recognized as essential measures to achieve higher wheat (Triticum aestivum L.) yields. However, inadequate management practices often lead to poor culm quality and lodging. We hypothesized that optimizing culm characteristics could be a feasible approach to improving both lodging resistance and yield. In this study, field experiments involved five nitrogen levels (0, 180, 240, 300, and 360 kg ha−1) and three planting densities (225, 375, and 525 × 104 ha−1). Two wheat cultivars with different lodging resistance were selected and their culm morphological characteristics, biochemical components, field lodging rate, and yield in different treatments were measured. We found that field lodging rate in wheat was negatively correlated with yield, and there was a contradiction between increasing spike number and lodging resistance. Culm carbohydrate accumulation affected field lodging rate by regulating culm quality rather than the center of gravity height. Compared with Xinmai 26, Xinhuamai 818 had higher culm carbohydrate accumulation, which increased the breaking strength and yield by 14.2% and 17.0%. Nitrogen application and planting density had significant effects on yield and lodging resistance. Compared with N0 treatment, increasing nitrogen application rate improved yield of 67.2%–83.2% by increasing spike number and grain number per spike, and the N2 treatment showed the largest increase. Planting density had little effect on yield. Reducing planting density can increase the culm carbohydrate accumulation and enhance lodging resistance. Compared with D3 treatment, the culm breaking strength was increased by 27.6% under the D1 treatment. This study determined that the optimal combination of nitrogen and density for improving wheat lodging resistance and yield is 240 kg ha−1 and 225 × 104 ha−1. This combination enhances culm breaking strength by increasing carbohydrate accumulation and achieves high yield by increasing grain number per spike, 1000‐grain weight, and stabilizing spike number.

How do novel plant growth regulators and cultivation models strategies affect mechanical strength, lodging resistance and maize productivity in semi-arid regions?

Plant growth regulators are synthetic compounds that have become a significant and technical guarantee for agricultural productivity. In China, "Jindeli", which contains active elements of ethephon and cycocel (EC), has been proven to prevent maize stem elongation, improve maize stem thickness, stem morphology and mechanical strength, root growth, lodging resistance, and yield under various cultivation models. Diethyl aminoethyl hexanoate (DA-6) can promote cell division and growth. From 2020–2021, four growth regulators sprays were used to conduct a field experiment; G1: water spraying; G2: EC spraying; G3: DA-6 spraying; G4: EC+DA-6 spraying under two cultivation models; R: ridge covered with plastic film mulching and T: traditional flat planting without plastic mulching. The results indicated that RG4 treatment considerably decreased plant height, internode length, ear height, lodging rate, and center of gravity height, while improved the internode bending strength, cross-sectional area, cortical thickness, and stem vascular bundles as compared with rest of all other treatments. RG4 treatment considerably improved internode diameter, stem mechanical strength, filling degree, root growth, mean tilt angle, and lignin content, while significantly reducing LAI. In addition, RG4 considerably enhanced the quality of corn stems, such as increasing mechanical properties and enhancing the compressive strength of corn stalks that content of hemicellulose, cellulose, and lignin has been increased. Furthermore, RG4 treatment significantly improved grain yield by optimizing leaf layer structure and increasing bleeding saps levels, increasing the grains per row and ear. Thus, under the RG4 treatment maize lodging rate was decreased 72.1%, and increased WUE (52.8%), and grain yield (46.6%). In conclusion, the results clearly demonstrate that in the semi-arid regions risk of lodging can be avoided by spraying EC+DA-6 with ridge covered plastic film mulching to the enriched stalk quality, shaping plant morphological characteristics, and proving a stable cultivation model to improving maize productivity.

Numerical Computation of Restoring Time and Prediction of Self-Righting Process

Excellent self-righting performance is important to guarantee the normal navigation of Unmanned Surface Vehicles (USVs) after overturning, and the restoring time is an important index in design requirements. Traditionally, the static stability method and experiments on full-scale vehicles were used to analyze the large-angle stability of the USV. However, when it comes to the analysis of self-righting performance, the traditional static stability method will cause improper integration, and experiments are not convenient. To solve these problems, an improved static stability method was proposed, and a whole self-righting process simulation of a physical model was finished. The numerical simulation method was used to predict the self-righting process of a USV under four working conditions. Firstly, a midpoint average method based on the static stability theory was adopted to compute the static restoring time, and the results were compared with the results of the references, which verifies the effectiveness of the midpoint average method. Also, the midpoint average method is convenient because it only needs the restoring arm curve, the width and the gravity center height. Then, a numerical simulation of a physical model in static water was finished, and an experiment for a physical model in a towing tank was conducted. Comparing the restoring time of the midpoint average method, the numerical simulation and the experiment, the results show that the numerical simulation has high accuracy. Moreover, the numerical simulation was used to predict the self-righting process and analyze the self-righting performance of a USV under four working conditions.

Decoupling and Parameter Extraction Methods for Conical Micro-Motion Object Based on FMCW Lidar.

Micro-Doppler time-frequency analysis has been regarded as an important parameter extraction method for conical micro-motion objects. However, the micro-Doppler effect caused by micro-motion can modulate the frequency of lidar echo, leading to coupling between structure and micro-motion parameters. Therefore, it is difficult to extract parameters for micro-motion cones. We propose a new method for parameter extraction by combining the range profile of a micro-motion cone and the micro-Doppler time-frequency spectrum. This method can effectively decouple and accurately extract the structure and the micro-motion parameters of cones. Compared with traditional time-frequency analysis methods, the accuracy of parameter extraction is higher, and the information is richer. Firstly, the range profile of the micro-motion cone was obtained by using an FMCW (Frequency Modulated Continuous Wave) lidar based on simulation. Secondly, quantitative analysis was conducted on the edge features of the range profile and the micro-Doppler time-frequency spectrum. Finally, the parameters of the micro-motion cone were extracted based on the proposed decoupling parameter extraction method. The results show that our method can effectively extract the cone height, the base radius, the precession angle, the spin frequency, and the gravity center height within the range of a lidar LOS (line of sight) angle from 20° to 65°. The average absolute percentage error can reach below 10%. The method proposed in this paper not only enriches the detection information regarding micro-motion cones, but also improves the accuracy of parameter extraction and establishes a foundation for classification and recognition. It provides a new technical approach for laser micro-Doppler detection in accurate recognition.

Management of Seeding Rate and Nitrogen Fertilization for Lodging Risk Reduction and High Grain Yield of Mechanically Direct-Seeded Rice under a Double-Cropping Regime in South China

Precision hill-drop direct seeding using mechanical drilling is a unique direct seeding technique employed in south China that offers advantages such as excellent grain yield and high lodging resistance. Improving yield and lodging-related traits is essential for efforts to improve mechanically direct-seeded rice (MDSR) production. Seeding rates (SR) and nitrogen (N) fertilization rate are two of the main factors affecting grain yield and lodging resistance under MDSR production. However, little information about double-season MDSR production in south China is available. Here, we evaluated yield and lodging risk for two rice cultivars Huanghuazhan, HHZ, lodging-resistant; Xiangyaxiangzhan, XYXZ, lodging-susceptible across two consecutive growing seasons under two under two seeding rates (LSR, 30 cm × 18 cm; HSR, 30 cm × 12 cm) and three N fertilization rates (N1 = 100 kg ha−1, reduced N; N2 = 150 kg ha−1, normal N; and N3 = 200 kg ha−1, enhanced N). We found that increased SR and N fertilization rate improved grain yield and increased lodging risk. SR and N were consistently and positively related to plant height (PH), gravity center height (GCH), the length from the broken basal internode to the panicle tip (SL), the fresh plant weight of the plant part above the broken point (FW), and the length of the two basal internodes. SR and N decreased breaking force (F) and breaking strength (BM), driving increased lodging risk as reflected by increases in lodging index (LI) values. Culm diameter (CD) and culm wall thickness (CWT) did not respond consistently to SR and N treatments. Correlation analysis revealed that PH, GCH, the length of first and second basal internodes, FW, and bending moment for the whole plant (WP) were positively correlated with LI, while F and BM were negatively associated with LI. These findings suggest that the increased lodging risk resulting from high SR could be mitigated by applying appropriate rates of N; that is, this work suggests that grain yield can be maximized and lodging risk minimized by increasing SR while decreasing N fertilization rate. Seasonal differences in the effects of SR and N fertilization should be considered to achieve a high grain yield and maintain high lodging resistance. Our study suggests that increasing SR and decreasing N fertilization can enhance rice grain yield while improving lodging resistance for both varieties. Optimizing grain yield by increasing SR while reducing lodging risk by lowering N application rates may maintain lodging resistance and improve grain yield.

Study on Kinematic Characteristics of Tennis Serve Technology under Different Serving Modes

Background and Aim: Tennis serve has an absolutely important position on the tennis court. The serving mode of topspin, flat stroke, and side spin cannot be completely distinguished and mastered by most Chinese athletes, and one of the effective ways to improve the technique of serving technology is to measure and analyze the serving technology from the perspective of biomechanics. This study aimed to analyze the biomechanical characteristics of the different service techniques. Materials and Methods: The participants of the study Xi'an Sports Institute eight secondary athletes, with two high-speed cameras eight two athletes serve three different biomechanical characteristics of image information acquisition, through the APAS data analysis software for video analysis and data processing, get three kinds of athletes serve technology. By comparing the kinematic parameters of the three serving techniques, the regular content of the three serving techniques is revealed. Result: The height of the highest point of the three serve throws of the eight players are 3.126±0.110m,3.258±0.052m, and 3.167±0.153m. The hit position heights are 2.904±0.044m,3.051±0.131m, and 2.920±0.085m. The center of gravity displacement at the hit position averaged 0.44m,0.474m, and 0.471m. The height of the center of the ball is 1.321±0.030m,1.345±0.035m and 1.325±0.035m. The center of gravity height at the hitting moment is 1.435±0.035m,1.505±0.051m and 1.461±0.049m. At the hitting time, the results of the three serves of the eight players are as follows: The right knee angle was 173.916deg, 140.732deg, and 159.772deg. The right shoulder vertical axis has angles of 87.041deg, 92.867deg, and 86.898deg. The right shoulder angles are 41.09deg,72.847deg and 34.113deg, 77.572deg, 122.674deg, and 131.052deg from the right elbow, 151.894deg, 111.125deg and 129.412deg from the right wrist. The velocity of the right shoulder joint was 1.31m/s, 1.369m/s and 1.483 m/s. The velocity of the right elbow joint was 1.788m/s, 2.443m/s and 2.136 m/s. The velocity of the right wrist was 2.265m/s, 3.257m/s and 3.256 m/s. The velocity of the ball is 17.476m/s, 38.215m/s, and 21.327m/s. Conclusion: When the same player applies different serving techniques, the smaller the difference between the highest point of the ball and the position of the ball, the better the serve effect. There are some differences between the hitting moment and the body (head) position. The center of gravity displacement trajectory is the same, but the height of the highest, the second side rotation, and the lowest topspin. The Angle of the knee and right shoulder vertical axis vary similarly, and the angular acceleration of the elbow and the minimum Angle of the wrist are almost the same, but the Angle of the shoulder is somewhat different, and the size of the Angle is related to the position of the shot. The speed curves of the right shoulder, right elbow, and right wrist all have the same trajectory, but the speed of the same joint of the three service techniques is somewhat different. Cause a different serve effect.

Real-time estimation of barycenter position for fuel cell distributed drive electric tractor based on derived UKF

ABSTRACT The FCDET is considered as a promising and advanced agricultural machinery due to its convenience and controllability. To enhance the control performance of the FCDET unit dynamic system, understanding the accurate position of the center of gravity (CoG) of the tractor unit in longitudinal motion and the operating environment is essential. In this paper, we proposed a real-time estimation method of CoG position of longitudinal motion for FCDET plowing and transportation conditions. CoG height and longitudinal axis distance distribution coefficients are used as state estimation variables, and the data obtained from displacement and velocity sensors are used as state observation variables, establishing a discrete system state space model and proving the observability. The proposed Derived UKF algorithm introduces the Sage-Husa adaptive noise equation within the Square-Root UKF framework to address the non-positive definite matrix problem. The research shows that the precise CoG longitudinal position effectively reflects changes in operational pavement load. The Derived UKF algorithm exhibits high state estimation accuracy in plowing and transportation conditions, with mean absolute errors of 14.2% and 5.0% of the state amplitude, respectively. This study supports the practical application of real-time state parameter estimation algorithms in controlling advanced agricultural machinery distributed drive systems.

A new model of friction brake efficiency of urban vehicles on unpaved roads using an analytical and numerical approach

• The approach estimates the efficiency of disc braking systems of urban vehicles. • The proposed approach takes into account the irregularities of the road surface. • In addition to the surface irregularities, the slip rate is taken into consideration. • The effect of wheel deformation during braking is considered. • The influence of the pressure on the brake disc is considered. This paper supports the implementation of a braking efficiency estimator of urban vehicle on rural roads, based on analytical and numerical approach. A statistical study is defined by the Association Road Managers and Partners (AGEPAR) estimates the rate of unpaved roads in Africa around 72%, which approximately 90% of passengers and goods transport that generally doesn’t respect loading standards. This is a major reason for increase traffic accidents in these countries. Hence the need to define vehicle speed limitations that takes in vehicle parameters and irregularities road. This can be done by defining a predicting model of dynamic behaviour for small vehicles, which constitute the majority of African vehicle fleet. To achieve this, we numerically solve the longitudinal dynamic equations of a vehicle body combine with front and rear axles on a road which has irregularities, opposed to existing models and Field data that are defined on surface roads which have little or no irregularities. The input parameters of the model are the initial vehicle speed, the road profile, inclination angle of road, peak wheel cylinder, wheelbase, centre of gravity height, rising time, brake pads contact area, final drive gear ratio, gearbox gear ratio, moment of inertia of engine, slip ratio, vehicle weight, moment of inertia at on axle and dynamic tyre radius which are assumed similarly and the braking system which is a disc braking system. The suspension is assumed identical and rigid since our study focuses on longitudinal and not vertical dynamics. The results produced by our modelling on paved and unpaved roads are compared with those obtained experimentally by J. R. Choa and the unpaved road data we obtained. The relative differences in braking times are respectively 6.5% and 3.1%. For the stopping distance, these relative differences are 11.5% and 11.9%.

Shaking table tests of a nonstructural freestanding object with variable center of gravity

Freestanding objects have endured seismic damage during major historical earthquakes, but their seismic performance is not fully understood yet. A steel frame was constructed with steel rods and moveable plates to investigate the effect of the center of gravity (CG) on the seismic response of nonstructural freestanding objects. The location of the CG can be tuned to change the CG in the frame. Two groups of shaking table tests were carried out using instrumented floor motion. To verify the shaking table test results, an analytical model was defined based on Housner's rocking model. The experimental response modes were predicted correctly. The experimental kinetic coefficient of friction obtained in the slow-pull tests agreed with the peak acceleration of the steel frame in the shaking table tests. The displacement amplitude generally decreased with increasing height of CG (hcg); however, this trend was not observed when the CG was fixed. Identical properties were observed for the rotational response of the frame. The experimental and analytical rocking responses were in agreement in terms of amplitude, but not in terms of time history and trajectories. The overturing criteria of overturing velocity, spectral velocity, and vulnerability, were evaluated using the experimental results. The overturning spectral acceleration was not accurately predicted using Housner's equation. The overturning probability and ratio were correctly predicted, and they increased with the increase in hcg. The findings of this work enable seismic risk mitigation of nonstructural freestanding objects.

Design and Experiment of Greenhouse Self-Balancing Mobile Robot Based on PR Joint Sensor

To avoid issues such as the greenhouse working robot’s inability to perform normal tasks or reduced working accuracy due to the influence of uneven ground, this study designed a set of greenhouse self-balancing mobile robots. The self-balancing mobile robot system designed in this study uses a quadruped mobile robot as a carrier, equipped with a three-degrees-of-freedom wheel-leg structure and is complemented with a posture control algorithm. The algorithm calculates the adjustment of each leg based on the vehicle’s tilt angle and wheel-ground pressure, achieving control over the robot’s posture angle, the center of gravity height, wheel-ground contact force, and other functions. To address the issue of over-constrained (weak legs) posture adjustment during mobile robot fieldwork, a flexible joint sensor based on the PR structure has been designed and developed. After field testing, it was verified that the greenhouse self-balancing mobile robot proposed in this study can adapt well to field environments, such as climbing hills, overcoming obstacles, crossing furrows, and so on. The response speed of the flexible joint sensor can meet the requirements of self-balancing while effectively solving the problem of weak legs.

The interactions of Rht15 and Rht1 alleviate some of their negative effects on agronomic traits in durum wheat

The application of dwarfing genes in wheat breeding effectively reduced plant height, improved lodging resistance and increased the harvest index. Although the gibberellin-responsive (GAR) dwarf gene Rht15 did not negatively affect coleoptile length or root traits while reducing the plant height, it reduced the yield plant−1. The gibberellin-insensitive (GAI) dwarf gene Rht1 can increase wheat yield under favorable conditions, but it reduces coleoptile length and affects root traits. This study was conducted to investigate whether the interaction of Rht15 and Rht1 can alleviate their negative effects. To analyze the interaction of Rht15 and Rht1, field experiments were conducted with the F5, F6 and F7 lines of the four genotypes, Rht15+Rht1, Rht15, Rht1 and tall lines detected using Rht15 and Rht1 molecular markers, derived from Durox (Rht15) and Kronos (Rht1), by comparing their effects on seedling traits, plant height and internode length, lodging resistance, flag leaf, yield and quality traits in durum wheat. The results showed that although the interaction of Rht15 and Rht1 did not overcome the inhibitory effect of Rht1 on coleoptile growth, it alleviated the negative effect of Rht1 on maximum root length (+14.8%). The grain yield plant−1 (+7.2%) of the Rht15 lines was improved under the action of Rht1 but was still lower than that of the Rht1 lines (−12.7%). The Rht15+Rht1 lines had the strongest effect on reducing plant height and center of gravity height (−42.2% and −41.5%), which significantly improved lodging resistance (+175%). The flag leaf area (+97.4%) and SPAD value (+11.6%, +9.6% and +10.6%) were also significantly increased. In addition, the coleoptile length of the Rht15 lines was not significantly different from that of the tall lines, the plant height and center of gravity height were significantly reduced (−30.5% and −34.0%), and the lodging resistance was significantly increased (+176.8%). The Rht1 lines had increased grain yield (+12.7%) due to an increased 1000-kernel weight (+12.9%) compared to the tall lines. In conclusion, the combination of Rht15 and Rht1 alleles enhanced the advantages and partially alleviated the defects in some traits when compared to the individual alleles, but the grain yield plant−1 was still lower than the Rht1 lines. This reflected the limitations of Rht15, and further confirmed the yield advantages of Rht1.

Design and Analysis of Anti-Roll Bar in Formula Vehicle

Abstract: This study explains a coherent flow for designing, analyzing, and testing a tuneable anti-roll bar system for a formula student race-car. The design process starts with the analytical calculation for roll stiffness using constraining parameters such as CG (Centre of Gravity) height, total mass, and weight distribution in conjunction with suspension geometry. Then, the material selection for the design i.e., Aluminium 7075 T6 is made based on parameters such as density and modulus of rigidity. A MATLAB program is used to iterate defection vs load for different stiffness and shaft diameter values. This is then checked with kinematic defection values in FUSION 360s geometry. To validate with the material defection, finite element analysis is performed on ANSYS workbench. Manufacturing accuracy for the job is checked using both static analysis in lab settings and using sensors on vehicles during ontrack testing. The error percentage is found to be 4% between the target stiffness and the one obtained from static testing. Parameters such as moment arm length, shaft diameter and length, and defection were determined and validated. This paper shows the importance of an anti-roll bar device to tune the roll stiffness of the car without interfering with the ride stiffness.

An examination of kinematic parameters related to pole vault performance

ABSTRACT Although various studies have examined factors associated with pole vault performance, only a few have identified a linear relationship between these factors and performance. This study aimed to identify the kinematics variables correlating with the maximum centre of gravity (CG) height. This cross-sectional study included 16 male pole vaulters and recorded their performance using four high-speed cameras at 240 Hz. The vaulters cleared the bungee bars that were set at 90% of their personal best record. The variables during pole vaulting from the touchdown of the penultimate step on the approach to the peak height of the CG were calculated. Pearson’s correlation analysis and Spearman’s rank correlation were used to test the correlation between maximum CG height and the variables. Significant correlations were observed between the maximum CG height and the six variables (grip height, approach velocity, takeoff velocity, takeoff distance, push height, and maximum vertical velocity). Grip height showed the strongest relationship, followed by push height and takeoff velocity. Pole vaulters should aim to gain a high approach velocity and grip height to increase their mechanical energy.

Model-Based Estimation of Vehicle Center of Gravity Height and Load

AbstractWith an increasing number of driver assistance functions and the upcoming trend of autonomous driving, knowledge of the current state and changeable parameters of the vehicle becomes more and more important. One particularly significant parameter with regard to vehicle dynamics is the center of gravity (COG) height, which mainly accounts for its roll dynamics in combination with the mass of the vehicle. Thus, a highly increased vehicle mass and COG height might lead to rollover during cornering, which underlines the need for accurate knowledge of the load of the vehicle. Based on that, an improved rollover prevention could be implemented, for instance, by enhancing the electronic stability program (ESP) of the vehicle. Therefore, the main contribution of this work is the model-based online estimation of the additional load of the vehicle, comprising its COG position and mass. This is achieved by applying a joint extended Kalman Filter (EKF) for the simultaneous state and parameter estimation. Based on a nonlinear model with roll, pitch, and vertical dynamics, an accurate and reliable estimation is possible. One major novelty of this work is the consideration of air suspension systems on top of conventional steel spring suspension systems. Therefore, a nonlinear air spring model with sufficient complexity is proposed, making it suitable for real-time applications. Further, a system theoretical observability analysis allows for an online adaptation of the Kalman Filter weights in order to account for different driving situations. The proposed estimation method is tested and validated by considering a wide range of driving situations, considering distinct loading conditions on both a test track and public roads. The estimation accuracy lies within roughly 50 kg and 1.5 cm for the vehicle mass and COG height, respectively.

Fewer hills with more seedlings improved lodging resistance of whole hill and yield stability of machine‐transplanted rice

AbstractLodging is a leading cause of yield loss in rice (Oryza sativa L.). To elucidate the effect of field configuration on lodging‐related traits at the single‐stem and whole hill levels, indica hybrid rice cultivars, Yixiangyou2115 and Shuyou217, were grown under traditional dense planting (30 × 12 cm row‐hill spacing) and under fewer hills with more seedlings (30 × 23 cm row‐hill spacing) in 2019 and 2020. The results show that there was no significant difference in single‐stem lodging index between fewer hills with more seedlings and traditional dense planting, as shown by the similarity in plant height, relative gravity center height, culm wall thickness, culm diameter, and breaking strength. However, compared with traditional dense planting, fewer hills with more seedlings significantly increased the anti‐thrust of whole plant and the ventilation rate between whole hills by 45.02%–117.36% and 58.18%–117.39%, respectively. This contributed to the marked improvement in the lodging resistance of whole rice hills, where plant inclination angle and apparent lodging rate were reduced by 41.75%–75.46% and 53.49%–63.33%, respectively. Furthermore, there was no significant difference in grain yield between the two configurations. These results indicate that the field configuration of fewer hills with more seedlings can improve the lodging resistance of whole hills while maintaining the grain yield of machine‐transplanted rice.

SELECTED TIME SPACE CHARACTERISTICS IN FEMALE POLE VAULT

Abstract This research is stressed at time and space characteristics (centre of gravity movements) in female pole vault. There are involved 19 female pole vault jumpers with sport performance 380 – 483 cm, divided on 2 different groups; higher and lower level from the point of sport performance. We found that in time parameters reached better results high performance level jumpers in phases hanging and lifting. It is coursed by better transmission on pole after take-off and by better work on the pole. As for the centre of gravity the jumpers of higher performance reached higher growth in all phases. The most significant difference can be seen in phase of lifting. Comparison of time and space characteristics enable to show the way for technique improvement in female pole-vault. Key words: female pole vault, rhythm of the jump, centre of gravity height

Influence of Nitrogen Application Rate on Stem Lodging Resistance Rice under Dry Cultivation

High grain yields of rice (Oryza sativa) under dry cultivation are primarily obtained through high levels of nitrogen (N) input. However, excessive inputs of N increase the risk of lodging. This study aimed to clarify the effect of N application rates on crop morphology, mechanical mechanisms of the stem, and chemical components in the basal stems of rice and their underlying mechanism in association with lodging resistance under dry cultivation. In this study, field experiments on rice were conducted under dry cultivation in early May to early October 2019 and 2020. Six rates of N applied at 0, 70, 140, 210, 280 and 350 kg ha−1 were set at a sowing rate of 150 kg ha−1 with Suijing 18 as the test material. The increased risk of lodging represented by lodging index (LI) and lodging rate with increasing N application was observed under both growing seasons. The plant height, basal internode length, particularly the second internode, and center of gravity height, which positively correlated with the LI, increased significantly with the increase in N application rates. In contrast, internode fullness and carbohydrate content of the basal second (S2) internode, which negatively correlated with LI, decreased significantly with increasing N application rates. A quadratic regression model between N application rates and grain yield showed that better grain yield could be achieved under an N application rate ranging from 210 to 228 kg ha−1. Therefore, the N application rate of (i.e., 210–228 kg N ha−1) could be recommended for the Suijing18 variety under dry cultivation in central Jilin Province for achieving high grain yield and great lodging resistance.

Real-Time Center of Gravity Estimation for Intelligent Connected Vehicle Based on HEKF-EKF

The vehicle center of gravity estimation is the key technology to the vehicle active safety system in intelligent connected vehicles. In this study, an integrated estimation approach for center of gravity (CG) combining Huber Extended Kalman Filter and Extended Kalman Filter (HEKF-EKF) is proposed. First, HEKF algorithm is used to estimate the distance between the CG and the front axle at the current time. Then, the CG height obtained by HEKF and EKF algorithms is weighted to obtain the optimal estimate value. Finally, the results show that the algorithm’s estimation convergence time is 2 s, its longitudinal position estimation error is less than 2%, and its center of gravity height estimation error is less than 3%. The longitudinal and vertical positions of the vehicle CG can be accurately estimated using this method. This method can help advance the development of active safety technology.