Center Of Gravity Research Articles

Biomechanical analysis of kinematics in the single whip movement of Tai Chi using video imaging

“Single whip” is a typical movement in Tai Chi, and the study of its kinematics has important practical value for better understanding the laws and characteristics of Tai Chi movements. This study divided 30 Tai Chi practitioners into two groups based on their skill level: an excellent group and a beginner group. The Vicon motion capture system and a three-dimensional force platform were used to obtain kinematic data. Differences in movements between the two groups at various stages were compared. The results showed that the excellent group took longer in stages one and three, but shorter in stage two. In stage one, the left knee joint angle of the excellent group was 95.45° ± 16.02°, while the right knee and left hip joint angles were larger (148.62° ± 12.84° and 133.55° ± 18.61°). In stage two, the angles of the right knee, left ankle, and right ankle joints of the excellent group were significantly smaller than those of the beginner group. In stage three, the angle of the right elbow joint of the excellent group was larger (154.26° ± 12.06°), while the angles of the right wrist angle and the left and right ankle joints were significantly smaller than those of the beginner group (p < 0.05). In terms of vertical displacement of the center of gravity, the excellent group exhibited less fluctuation and significantly lower dynamic stability in both anterior-posterior and medial-lateral directions compared to the beginner group (p < 0.05).

THE STUDY OF ACCURACY OF AN OPERATOR’S PERCEPTION OF GEOMETRICAL OBJECT SIZES AND SHAPES IN THE VIRTUAL ENVIRONMENTS

This paper is devoted to the experimental comparison of accuracy of an operator’s perception of geometrical object sizes and shapes between the different conditions of information perception in the virtual environments and from the electronic displays. The experiments were conducted using a psychophysiological test for the accuracy of perceiving geometrical object sizes and shapes by an operator in the virtual environments and in the conditions of information perception from an electronic display. As a common metric of the accuracy of perceiving geometrical object sizes and shapes, an operator was offered to visually determine the object center of gravity. No significant differences in the measurement results of both the accuracy of perceiving geometrical object sizes and shapes and speed of this process were found based on the different methods of displaying the visual information to an operator.

Further and Forward

In our previous issue, we asked the question “Quo Vadis:” where are we heading with the Philippine Journal of Pathology? Eight years and fifteen issues since the Philippine Journal of Pathology was revived, I would like to believe that the journal has somehow been able to pull to stand, through the continuing support of the Philippine Society of Pathologists, Inc., akin to a baby that has achieved a developmental milestone of finally standing on both feet: a bit wobbly, but with some stability in balancing its center of gravity.

ТРАНСФОРМАЦИИ МИССИОНЕРСКОЙ ДЕЯТЕЛЬНОСТИ НОВЫХ РЕЛИГИОЗНЫХ ДВИЖЕНИЙ: СПОСОБЫ И ПРИНЦИПЫ ЗАКОННОСТИ

The article analyzes the methods of missionary activity of new religious movements used by their leaders and followers to spread their doctrines and spiritual practices. To analyze the missionary activity of new religious movements, the author primarily examined organizations and cults operating in the territory of Crimea and Sevastopol, using materials from the Internet, as well as those obtained in the course of practical work of an expert in religious studies and a teacher of religious studies. The author conducted a comparative analysis of the formats of missionary work used by representatives of new religious movements before the era of mass use of the Internet in the religious space, and the methods of missionary work by new religious movements at the present stage with the use of new information and communication technologies. As a result of the analysis, characteristic features of transformations in the nature of missionary activity of new religious movements at the present stage were revealed. An important point in the presented article was the correlation of the nature of modern missionary work with the changes in Russian legislation that have influenced the methods of conducting missionary work of new religious movements. The author draws attention to how the situation regarding the missionary activity of new religious movements has changed since 2016, when the Yarovaya-Ozerov Law was adopted, regulating missionary work in the Russian Federation. The changes in the environment of Internet users, which have been growing, including in connection with the spread of the new Covid-19 infection, which has caused restrictions on the functioning of believers in the physical religious space and contributed to the transfer of the center of gravity of religious, including missionary, activity to the virtual space, are also analyzed.

Design of a Suspension Controller with Human Body Model for Ride Comfort Improvement and Motion Sickness Mitigation

This paper presents a method to design a suspension controller with a human body model for ride comfort improvement and motion sickness mitigation. Generally, it has been known that the vertical acceleration of a sprung mass should be reduced for ride comfort. On the other hand, recent studies have shown that, combined, the vertical acceleration and pitch rate of a sprung mass are key factors that cause motion sickness. However, those variables have been considered with respect to the center of gravity of a sprung mass. For motion sickness mitigation, the vertical acceleration of a human head should be also considered. In this paper, the vertical accelerations and pitch rates of a sprung mass and a human head are controlled by a suspension controller for ride comfort improvement and motion sickness mitigation. For the controller design, a half-car and human body models are adopted. With those models, several types of static output feedback suspension controller are designed with linear quadratic optimal control methodology. To reduce the pitch rate of the sprung mass and the vertical acceleration of the head, a filtered-X LMS algorithm is adopted as an adaptive feedforward algorithm and combined with the static output feedback controllers. A frequency response analysis and simulation are performed with the designed controllers on vehicle simulation software, CarSim®. From the simulation results, it is shown that the proposed controllers can effectively reduce the vertical accelerations and the pitch rate of the sprung mass and the human head.

Spatial Inequalities in the Centre of Gravity in Central-Eastern Europe Based on the GVA and the Employment Rate

The issue of territorial disparities is an interesting subject of study in Europe, as there are significant socio-economic disparities between regions, which do not disappear over time, despite substantial levels of funding. The Central-Eastern European region is lagging significantly behind the EU as a whole and the Western regions, with significant intra-country differences. This study aims to examine six countries in the Central-Eastern European region in terms of county-level gross value added and employment rates, examining the convergence processes in the region. In addition to the growth rates of the regions, the study examines the emergence of sigma and beta convergence phenomena, as well as the importance of spatial spillover effects and neighbourhood relations in catching up. I investigate the probability that the spatial distribution of each indicator is heterogeneous, which I also illustrate by the change in the spatial centre of gravity. Convergence studies highlight the internal convergence of the region but also draw attention to the impact of different crises on inequalities.

Aerodynamics of Paper Airplanes: From Basic Physics to Biomimicry Research

This study delves into the fundamental physics of paper airplanes and extends to the domain of biomimicry, drawing parallels between artificial and natural flight mechanisms. Focused on both theoretical and practical aspects, the investigation encompasses the design parameters crucial for the construction of paper airplanes—particularly, the choice of material, aerodynamic wing shapes, and the strategic balance between the center of gravity and lift forces. By experimenting with various designs, the impact on flight performance, including the achievable distance and stability, is thoroughly analyzed. Furthermore, the research includes a qualitative comparison with avian flight data, aiming to uncover underlying natural flight strategies that could enhance artificial designs. The findings not only augment current aerodynamic theory but also offer new insights into the educational and engineering applications of paper airplanes, proposing innovative ways to integrate these simple yet profound constructs into more complex fields of study. This exploration not only broadens the understanding of paper aircraft but also fosters a deeper appreciation of biomimicry in modern engineering education Chapter.

Synergistic Matching and Influencing Factors of Grain Production and Cropland Net Primary Productivity in the Black Soil Region of Northeast China

Exploring the spatiotemporal dynamics, spatial mismatch, and complex influencing mechanism of grain production and cropland productivity in the black soil region of northeast China (BSRNC) is essential for the synergistic protection and utilization of black soil cropland and sustainable grain production. The BSRNC has realized cropland expansion and grain production increases in the past decades. This implied a substantial investment has been made in the region’s agriculture. However, at present, knowledge on the spatial mismatch and influencing factors of grain production and cropland productivity is still unclear. This study analyzed the spatial–temporal mismatch characteristics of grain production and cropland net primary productivity (CNPP) using the gravity center model, spatial autocorrelation analysis, and spatial mismatch index (SMI), and identified the spatial heterogeneity and prediction–response relationships of influencing factors based on a geographically and temporally weighted regression (GTWR) model and boosted regression tree (BRT) machine learning algorithm. The findings indicated that grain production and CNPP have been increasing, but the overall spatial pattern of cold hotspots has not changed obviously in the BSRNC from 2000 to 2020. The SMI has shown a decreasing trend, indicating that the synergistic development of grain production and CNPP has been obvious, which plays an important role in sustainable food supply capacity. Agricultural production and the natural environment have always been critical factors influencing the spatial mismatch. Specifically, the marginal impact of fertilizer application has undergone a shift. This study may provide new clues for the formulation of regional strategies for sustainable food supply and black soil cropland system protection.

Land cover change and its driving factors in Siberia from 1992 to 2020.

Siberia occupies vast areas underlain by permafrost, and understanding its land cover changes is important for ecological environmental protection in a warming climate. Based on the land cover and climate datasets, we analyzed the land cover changes and their drivers in Siberia from 1992 to 2020. The results show that ① From 1992 to 2020, the areas of evergreen needleleaf trees and deciduous needleleaf trees in Siberia decreased by 9% and 2.5%, and the areas of grassland, shrub, cropland, and construction land increased by 1.5%, 14.2%, 2.8%, and 39.2%, respectively. Cropland expansion had the fastest rate of 1.85% in the continuous permafrost zone, and construction land expansion had the fastest rate of 3.07% in the non-permafrost zone. ② The center of gravity of agricultural land continues to migrate to the northeast, and the center of gravity of construction land continues to migrate to the southwest. ③ The primary drivers for the land cover changes were temperature and precipitation, and active layer thickness also affected grassland, cropland, and deciduous needleleaf trees. The correlation coefficient between active layer thickness and cropland area is 0.74 in the continuous permafrost zone. The interaction between factors is mostly manifested as a two-factor enhancement, with the highest q-value of the interaction of temperature and precipitation for explanatory power. Our results suggest that climate change and permafrost degradation significantly changed land cover in Siberia. This finding deepens our understanding of the mechanisms of land cover change under the influence of permafrost degradation and provides a new perspective on the land cover changes in permafrost regions.

Biomechanical analysis and optimization of sports action training in virtual reality (VR) environment

Over the past years, virtual reality (VR) has become much more popular. VR combines several technologies to provide an immersive digital environment. This environment allows users to engage and react to their actions, creating a virtual world where users feel more present. In biomechanical analysis, researchers analyze the physical characteristics of biological tissues and model the relationship between tissue form and function. Utilizing VR headsets, motion-tracking apparatus, and realistic virtual worlds that simulate actual sports situations are all part of virtual sports training. VR lacks realism, which can be related to the absence of sensory input, making it unsuitable for training fine motor skills. The research aims to perform biomechanical analysis and optimize sports action training inside a VR setting. A mountain gazelle optimizer fine-tuned adjustable convolution neural network (MGO-ACNN) is proposed to examine the joint angle selections utilized by sports action. In this study, human motion image data are utilized to capture various angles of the training action. The data was preprocessed using a Wiener Filter (WF) for the obtained data. Analyzing spatial frequency and orientation in images for feature extraction is accomplished using the Gabor Filter (GF). This approach incorporates VR simulations to provide a more regulated and immersive setting for joint angle analysis during sports training. The proposed method is implemented using Python software. The result demonstrated by the proposed method significantly outperforms the existing algorithms. The performance parameters for accuracy (99.73%), precision (99.75%), recall (99.73%), and F1-score (99.72%) are assessed in this study. The VR experiments indicate that optimal sports preparation involves a sports action while maintaining a batting speed consistent with the joint to lower the center of gravity. This research highlights the more effective, personalized sports training system, leveraging VR to simulate real-world conditions while providing detailed biomechanical insights.

Analysis of the Adaptation of the Belt and Road Initiative in the European Union: A Perspective Based on Multilateral Cooperation, Sociocultural and Sustainable Development

As the center of gravity of the global economy gradually shifts to Asia, China has strengthened its influence in the international economic system through the Belt and Road Initiative. As an important pole of the global economy, how to maintain the competitiveness of the EU in the new situation has become an important issue. There are significant differences between EU member states in terms of their level of economic development, foreign policies and attitudes towards China. This diversity makes it more difficult for the EU to coordinate its reaction to the Belt and Road Initiative. This complicates the EU's efforts to coordinate its reaction to the Initiative. As a result, this study investigates multilateral cooperation, socio-cultural, and sustainable development viewpoints, concluding that the EU must improve collaboration, maximize internal coordination, and adhere to the goal of sustainable development. The paper also discusses the major economic issues arising from the policy coordination of EU member states to adapt to the Belt and Road Initiative and the solutions required for these challenges.

The Influence of Lower-Limb Strength and Power on the Speed and Heat Results of Professional Brazilian Surfers.

To correlate speed and heat scores with anthropometric variables and lower-limb strength and power in professional surfers. A total of 19 men participated in simulated competitions on different days. All surfed waves were scored, and each athlete's best 2 were used for their total heat score. Speed values were extracted by global positioning system and adjusted by Z score. Squat jump, countermovement jump, and drop jump were executed. Anthropometric variables and 1-repetition maximum (1RM) in the half squat were measured. Pearson product-moment correlation was used to analyze the relationships. Height had a significant (P < .05) inverse association with speed indicators (r = -.36 to - .68), and body mass index had a moderate association with maximum wave speed of the highest score. Significant correlations with moderate to large magnitudes were found between maximum speed and vertical jumps (r = .46 to .56), average speed and vertical jumps (r = .48 to .59), and both maximum and average speed with 1RM (r = .52-.53). Athletes' best score and total heat score showed moderate to large associations with vertical jumps and 1RM (r = .48-.64), whereas second scores were correlated with the reactive strength index of the drop jump (r = .48) and 1RM (r = .51). Shorter surfers with lower center of gravity and those with superior lower-limb strength and power achieved greater speed and higher scores. Accordingly, surf coaches may consider prescribing dynamic strength and balance training based on an athlete's profile to improve performance.

The spatio-temporal evolution and influencing factors of the coupling coordination degree between tourism supply and demand in the Yangtze river economic belt

The imbalance between supply and demand is a pressing issue in the development of the tourism industry. Understanding the coupling coordination relationship and impact mechanism of supply-demand in the tourism system can help achieve high-quality tourism development. This study focuses on the Yangtze River Economic Belt (YREB) as the research area, quantifies the tourism supply index (TSI) and tourism demand index (TDI) from 2011 to 2020 using the tourism development index model, calculates the coupling coordination degree (CCD) of TSI and TDI based on the coupling coordination model, and explores the factors influencing the CCD using the geographic detector. The findings indicate that: (1) The TSI and TDI in various provinces show fluctuation but exhibit an overall upward trend. (2) There were apparent spatial disparities of the CCD, with a distribution characteristic of high in the east and low in other regions. The CCD gradually improved, with its gravity center slowly shifting toward the southwest. All provinces entered the intermediate stage of tourism development since 2014. (3) Basic service guarantee, consumption drive, and innovation drive are identified as the dominant factors influencing the CCD. The study can provide valuable insights for tourism coordination and sustainable development.

Development of a Virtual Telehandler Model Using a Bond Graph

Recent technological advancements and evolving regulatory frameworks are catalysing the integration of renewable energy sources in construction equipment, with the objective of significantly reducing greenhouse gas emissions. The electrification of non-road mobile machinery (NRMM), particularly self-propelled Rough-Terrain Variable Reach Trucks (RTVRT) equipped with telescopic booms, presents notable stability challenges. The transition from diesel to electric propulsion systems alters, among other factors, the centre of gravity and the inertial matrix, necessitating precise load capacity determinations through detailed load charts to ensure operational safety. This paper introduces a virtual model constructed through multiphysics modelling utilising the bond graph methodology, incorporating both scalar and vector bonds to facilitate detailed interconnections between mechanical and hydraulic domains. The model encompasses critical components, including the chassis, rear axle, telescopic boom, attachment fork, and wheels, each requiring a comprehensive three-dimensional treatment to accurately resolve spatial dynamics. An illustrative case study, supported by empirical data, demonstrates the model’s capabilities, particularly in calculating ground wheel reaction forces and analysing the hydraulic self-levelling behaviour of the attachment fork. Notably, discrepancies within a 10% range are deemed acceptable, reflecting the inherent variability of field operating conditions. Experimental analyses validate the BG-3D simulation model of the telehandler implemented in 20-SIM establishing it as an effective tool for estimating stability limits with satisfactory precision and for predicting dynamic behaviour across diverse operating conditions. Additionally, the paper discusses prospective enhancements to the model, such as the integration of the virtual vehicle model with a variable inclination platform in future research phases, aimed at evaluating both longitudinal and lateral stability in accordance with ISO 22915 standards, promoting operator safety.

Spatio-Temporal Evolution, Internal Diversity, and Driving Factors of Economy of Guanzhong Plain Urban Agglomeration in Northwestern China Based on Nighttime Light Data

Urban agglomeration (UA) is a highly developed spatial form of urban complex, which is one of the important carriers of regional economic cooperation, international industrial division of labor, and flow of capital and information elements. In China, urban agglomerations (UAs) have become the spatial subject of the national new-type urbanization strategy since the early 21st century and have made irreplaceable contributions to China’s urbanization and economic development. The Guanzhong Plain urban agglomeration (GPUA) is an important economic growth pole in northwest China and a key node in China’s open-door pattern. Exploring the spatial and temporal characteristics and driving factors of its economic development will be an important revelation for the promotion of high-quality economic development of the GPUA. This paper characterizes the level of economic development of GPUA with a long series of nighttime light data between 2002 and 2022. The standard deviation ellipse, spatial autocorrelation analysis, the economic difference index, and grey correlation analysis are used to analyze the characteristics of spatio-temporal evolution, internal diversity, and driving factors of economic development of the GPUA. The results show that the economic development level of the GPUA continued to increase from 2002 to 2022. The spatial distribution of the GPUA economy is “northeast-southwest” axial distribution, and the center of gravity of economic development gradually moves westward. The differences in the level of economic development within the GPUA show a typical core–periphery structure, but the degree of difference tends to weaken over time. The internal expansion force and economic promotion force were the dominant factors for the economic development of the GPUA in the early years. However, with the passage of time, scientific and technological support and government support have gradually become the main influencing factors for the economic development of the GPUA nowadays.

Quality Issues in Kinematic Traces from Three Head Impact Sensors in Boxing: Prevalence, Effects, and Implications for Exposure Assessment.

When used in-vivo or in biofidelic environments, many head impact sensors have shown limitations related to the quality and validity of the kinematics measured. The objectives were to assess the quality of kinematic traces from three head impact sensors, determine the effects of signal quality on peak accelerations, and compare measurements across sensors. Head impacts were collected with instrumented mouthguards, skin patches, and headgear patches during boxing sparring. The quality of the raw kinematic traces for 442 events for each sensor was categorized using pre-defined objective criteria into high, questionable, and low-quality classes. The proportion of high-quality recordings was analyzed by participant, type of impact, and impact location. Associations between signal quality and peak kinematics were assessed within each sensor, and peak kinematics (resolved to the head center of gravity) were compared between sensors. High-quality criteria were met in 53%, 20%, and 26% of events for the mouthguard, skin patch, and headgear patch, respectively. High-quality recordings were less frequent for impacts occurring close to the sensor (e.g., 30% vs. 61% for the mouthguard) and showed lower peak kinematics than low-quality recordings (p < 0.001). Despite careful selection of high-quality simultaneous recordings, there was little to no association between the sensors' measurements (Spearman's p ≥ 0.043). The kinematic data often reflected the motion of the sensor itself rather than the motion of the head, overestimating head impact magnitude. Researchers should evaluate data quality prior to analyzing kinematics or injury severity metrics. Comparison of data across studies or in relation to injury risk functions needs to be done with caution when data were acquired from different sensors.

Experimental study of hydrodynamic effect of loading and longitudinal variations of the center of gravity on the performance of a single-step craft in calm water

Performance of stepped planing vessels is notably influenced by loading and longitudinal position of the center of gravity. These factors directly affect trim angle, rise, total resistance due to motion, and overall hydrodynamic efficiency. This study experimentally investigates a 2.5 m Fridsma series model with 20° deadrise angle, length-to-width ratio of 5, step distance of 28% of the overall length from the transom, and step height of 4% of the model's width. It involves testing the model with two different weights: 63 and 76.6 kg, corresponding to load coefficients of CΔ=0.5 and CΔ=0.61. Center of gravity is placed at 0.8 m (32%), 0.85 m (34%), and 0.9 m (36%) from the transom. Experiments are conducted at speeds of 1, 2, 3, 4, 5, 6.5, and 8 m/s, which correspond to beam Froude numbers of 0.45, 0.9, 1.35, 1.8, 2.26, 2.9, and 3.6, respectively. The results indicate that increasing the load from 63 to 76.6 kg leads to approximately 12% increase in static trim across all center of gravity positions. The final trim is shown to increase by around 15% at all tested speeds. Additionally, load variations result in 20% rise in the rise up and total resistance. The model achieves optimal performance with load coefficient CΔ=0.61 and center of gravity at 36% of the overall length from the transom, showing the lowest resistance to weight ratio. Overall, the findings reveal that optimizing internal load distribution and LCG placement can enhance the boat's hydrodynamic efficiency, resulting in improved speed, stability, and fuel economy under different operational conditions.

Does aberrant electrocortical dynamics pattern imply atypical balance control in adolescents with idiopathic scoliosis?

Adolescent idiopathic scoliosis (AIS) is a developmental disorder described as a three-dimensional spine deformity with multifactorial etiology. The multifactorial model of AIS suggests that the patient population is diverse. Identifying individuals with sensorimotor control impairments could enable personalized treatments, potentially leading to improved outcomes for those with AIS. We hypothesize that abnormal electrocortical dynamics within the sensorimotor cortex will be related to less efficient balance control in standing during ankle proprioception alteration in the absence or presence of vision. To test this hypothesis, the balance control performance of adolescents with AIS will be assessed on a force platform by computing the root mean square value of the scalar distance between the center of pressure and the center of gravity. Electroencephalography will be recorded while challenging balance control by altering ankle proprioception in the presence and absence of visual cues. Time-frequency analyses will be calculated to determine alpha, and beta band power in both conditions. Pilot data from 13 participants with AIS were analyzed to support our hypothesis. Three participants with less efficient balance control showed electrocortical dynamics changes, such as an increase in beta band power in the presence and absence of vision and a decrease in alpha band power in the presence of vision compared to the AIS group with efficient balance control. These findings support our hypothesis of suboptimal sensorimotor information processing in the subgroup of adolescents with AIS with less efficient balance control, which could have significant implications for developing personalized treatments for AIS.

Urban sprawl and its effects on water competition between building industry and residents: Evidence from 31 provinces in China

With accelerated urban sprawl, water scarcity and increased water stress have become global issues. Water of building industry and domestic water are two major contributors to total water consumption that cannot be ignored. This paper seeks to emphasize the effects of urban sprawl on water competition between building industry and residents. To achieve this objective, a framework for quantifying the water usage of the life cycle of the building was first constructed. Additionally, the degree of urban sprawl and water competition between domestic and building industry was computed. This study characterized the evolution path of urban sprawl and water competition using standard deviation ellipse. Spatial econometric models were used to determine the impact of urban sprawl on water competition. The results indicate that there is a high spatial correlation between urban sprawl and water competition. The center of gravity of China's urban sprawl is consistent with the north-to-south movement of water competition. As economic sprawl increases by 1%, water competition will rise by 0.440%. As the population expands by 1%, the water competition index shifts by 0.018%. Moreover, 0.017% more water was used for every 1% increase in land sprawl.

Prop-Plane — new convertible VTOL UAV as a combination of a longitudinal bicopter and a flying wing with a tilt-rotor powertrain

Vertical take-off and landing (VTOL) unmanned aircrafts are the newest and rapidly developing topic which is not only capable of improving Unmanned Aerial Vehicles (UAV) potential but also to create new use cases. This paper proposes a new convertible VTOL concept designed to obtain optimum flight characteristics for monitoring or flying over long objects. The distinctive feature of the proposed design is a combination of a flying wing with a longitudinal bicopter. The aircraft folds the wings down along the main axis of the aircraft during vertical take-offs and landings to descend the center of gravity and increase stability in bicopter mode. The convertible plane maximizes performance during horizontal flight while maintaining vertical take-off and landing capabilities.The design has been implemented in prototype, and the internal systems and the airframe have been designed and manufactured. As a result, the calculated technical characteristics of the UAV including wind resistance capability were described, the principal elements and components of the design were discussed, and the flight tests of the prototype created were conducted and results presented. Furthermore, the advantages and disadvantages of the concept are reviewed and further development of the project is discussed. The conducted work allows us to confirm the assumption that the developed concept can be used for real-world monitoring missions and to continue developing the concept for a full-scale UAV.