Dominant Movement Direction Research Articles

Estimation of the metabolic rate in the occupational field: a regression model using accelerometers

The aim of this study is to investigate the ability of the acceleration vector magnitude (VM) to predict the metabolic rate (M) for a variety of work activities. Accurate knowledge of M is of vital importance to evaluate the energy cost of work activity. While precise estimates of M can be achieved using direct calorimetry, this is not a viable option in workplaces. Ten healthy subjects (5 males, 5 females) were enrolled in six tasks simulating specific work activities. During each test, oxygen consumption rate (V˙O2), carbon dioxide production rate (V˙CO2) and accelerations at three body positions were measured. V˙O2 and V˙CO2 were used to obtain M and accelerations to calculate VM. Three mono-linear zero-intercept regression models based on center-of-mass VM were developed. A zero-intercept functional relation between M and VM was applied to the whole data set yielding the Global model. A R2 of 0.30 was obtained which indicates limited predictive ability. Two other (Vertical and Horizontal) models were also developed by separating tasks with different kinematics. With R2 = 0.56 and 0.61 they represent a significant improvement over the Global model. The results reveal a low R2 for the Global model due to collecting in the same sample many tasks that have little in common. A large R2 improvement is achieved when the dominant direction of movement is considered. The proposed method is based on a non-invasive easy-to-measure physiological parameter and can be used to track the activity level during work activity in the industrial sector.

Three-Dimensional Surface Deformation Characteristics Based on Time Series InSAR and GPS Technologies in Beijing, China

Excessive exploitation of the groundwater has resulted in obvious three-dimensional (3D) deformation features on the surface of the Beijing Plain. This paper, by combining Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) technologies, has obtained time-series information of the 3D surface deformation in the Beijing Plain, analyzing its spatial distribution characteristics. On this basis, the relationship between different controlling factors with the 3D deformation of the surface has been analyzed as well. The following results are obtained: (1) From 2013 to 2018, the land subsidence, which generally showed the trend of slowing down, was mainly concentrated in the eastern, northern, and southern regions of Beijing Plain, with multiple subsidence centers. (2) Under the International Terrestrial Reference Frame 2005 (ITRF2005), the horizontal direction of all GPS points in the plain is basically the same, with the dominant movement direction being NE112.5°~NE113.8°. Under the Eurasian reference frame, the horizontal movement rate of GPS points significantly decreases. The movement rate and direction of each point are not characteristic of overall trend activity. (3) The distribution and extent of the 3D surface deformation in the Beijing Plain are controlled by the basement structure. Part of the subsided area corresponds to a Quaternary depression formed at the junction of active faults disrupting the area. Similarly, the distribution of horizontal deformation in the E-W and N-S directions of the plain is controlled by the regional basement structure comprising major faults bounding horizontal deformation. (4) Groundwater exploitation is the main cause of the 3D surface deformation in the Beijing Plain. The groundwater funnels of the second and third confined aquifer are in suitable agreement with the land subsidence. The horizontal movement in the Beijing Plain is either directed toward the center of the groundwater or the land subsidence funnel, and the deformation is directed from areas with higher to areas with lower groundwater levels.

Multi-directional change detection between point clouds

Point clouds continue to be acquired with greater accuracy and less occlusion over complex scenes, characterised by high roughness and topographic variation in all three dimensions. The most widely adopted approach to change detection, M3C2, measures change along the local surface normal, which varies between points and bypasses the uncertainties involved in mesh or DEM generation. While adaptive, this direction of comparison is nevertheless user-defined and becomes less relevant where the movement direction deviates from the surface normal. Measured change therefore also becomes less meaningful, as it is a projection onto this direction. Sliding of a failing slope, for example, is predominantly surface parallel rather than along the surface normal. We present an approach that derives a dominant movement direction (DMD) at each point based on multi-scale, multi-directional change quantifications. The DMDs differ from the surface normals in three LiDAR-derived test cases; a rockfall, an avalanche, and rock glacier movement, providing more accurate measures of rockfall depth and boulder movement across the rock glacier. When the direction of change detection is orthogonal to local relief (i.e. across the surface), a variable length search cylinder that intersects only a single (corresponding) surface is necessary during change detection. Where movement results in new regions of occlusion in the second point cloud, we show that the proportion of points for which no valid change could be recorded decreases by up to 15% using the DMD rather than the surface normal. We emphasise the importance of examining the direction over which change is measured, and highlight that a comparison direction that adapts to movement rather than to the local surface can provide more relevant and accurate measures of change where the movement is not orthogonal to the surface. Our approach represents a supplementary tool for cloud-to-cloud comparison, where a choice of tool should be made based on the expected DMD deviation from the surface normal.

Effects of PV array layout, electrical configuration and geographic orientation on mismatch losses caused by moving clouds

The mismatch losses of photovoltaic (PV) systems are mainly caused by partial shading and the largest mismatch losses are caused by sharp shadows. However, in large scale PV plants majority of shading events is caused by moving clouds which lead to gentle irradiance transitions causing typically only minor irradiance differences between adjacent PV modules. Irradiance transitions caused by the edges of cloud shadows have an average length of almost 150m meaning that even the largest PV power plants are widely affected by them. In addition of mismatch losses, these irradiance transitions can lead to failures in maximum power point tracking and cause significant fluctuations in the output power of PV systems.In this paper, the effects of PV array shape, electrical configuration and orientation on mismatch losses caused by moving clouds were studied based on apparent velocity and other measured characteristics of roughly 27,000 irradiance transitions. The study was conducted using a mathematical model and parametrisation method of irradiance transitions and an experimentally verified simulation model of a PV module based on the well-known one-diode model of a PV cell. The studied electrical PV array configurations were series-parallel, total-cross-tied and multi-string.The results of this study confirmed a prior conclusion, namely, that the mismatch losses decrease with decreasing PV string length. It was also found that the array orientation has a considerable effect on the mismatch losses of the studied array layouts. The mismatch losses were the smallest when the dominant direction of movement of the shadow edges was perpendicular to the PV strings. The differences in the mismatch losses between the studied electrical array configurations were very small. The results indicated that the mismatch losses caused by moving clouds have only a minor effect on the overall efficiency of PV arrays.

Output power variation of different PV array configurations during irradiance transitions caused by moving clouds

This paper presents a study of the output power variation of different photovoltaic (PV) array configurations during irradiance transitions caused by moving clouds. The study was based on velocity and other characteristics of roughly 27,000 irradiance transitions identified in measured irradiance data and conducted using a mathematical model of irradiance transitions and an experimentally verified simulation model of a PV module. The studied electrical PV array configurations were series-parallel, total-cross-tied and multi-string. The different PV array orientations and layouts (physical shapes) of the configurations were also studied.The average rate of change of the power of these studied PV array configurations during the irradiance transitions was around 3%/s and the maximum instantaneous rates of change of the power were around 75%/s. Half of the time during the studied transitions, the rate of change in the power was over 1.2%/s, and most of the time during the transitions, it exceeded typical PV power ramp rate limits set by grid operators. The average rate of change of PV array power decreased with an increasing maximum array dimension and it was observed to be the largest when the shorter dimension of the array was parallel to the dominant movement direction of the shadow edges. The results of this study are relevant especially in terms of PV array design, maximum power point tracking algorithm development and energy storage systems sizing.

Support diameter, incline, and vertical movements of four didelphid marsupials in the Atlantic forest of Brazil

AbstractDidelphids use vertical strata in different ways, suggesting the existence of a wider variety of niches than simply arboreal or terrestrial. This variety could be related to the differential ability to deal with support diameters and inclines, and might be important for the coexistence of species in local assemblages. From data obtained with the spool‐and‐line technique, the use of the vertical space and above‐ground supports is described in four species of an assemblage of didelphid marsupials in south‐east Brazil. The stratification in this and other assemblages in the Atlantic forest and in the Amazon is also compared. Animals were trapped in Serra dos Órgãos, state of Rio de Janeiro, and equipped with a spool‐and‐line device before release. The paths were tracked by measuring variables related to support diameter, incline, distance and height moved above ground. The diameter of supports used was positively related to body size, and the incline to the dominant direction of movement (horizontal vs vertical). The more cursorial species, Metachirus nudicaudatus, only once moved above ground in > 3200 m of paths followed. Didelphis aurita moved mostly on the ground, but was the only species that occasionally reached the canopy. Philander frenata also moved mostly on the ground, occasionally used the understorey, but never reached the canopy. The more arboreal species, Marmosops incanus, moved mostly in the understorey, but never in the canopy. This pattern of stratification is similar to that observed in other sites in the Atlantic forest and in the Amazon.

Monitoring the horizontal movement along the Shanxi fault zone by GPS measurement

Based on the data from 4 times of repeated measurements (1996–1999) of GPS monitoring network arranged along Shanxi fault zone, the current horizontal movement of Shanxi fault zone and its relationship with Yang-yuan-Hunyuan earthquake (M=5.6; 39.8°N, 113.9°E; November 1, 1999) which occurred at the north part of the monitoring network is analyzed. The results from the analysis indicate: 1 The horizontal movement along Shanxi fault zone was not obvious from 1996 to 1997; 2 The intensity of horizontal movement along Shanxi fault zone increased at the period of 1997 to 1998, and there are three areas with relatively higher strain (1×10−6) appeared, i.e., the source region, Xinzhou region and northeastern part of Jiexiu; 3 Although the dominant movement direction of Shanxi fault zone in the period of 1998 to 1999 was consistent with the fault striking direction, but as compared with the movement in the passed year, the direction was almost reversed, while the absolute value of the movement was close each other; 4 The accumulated horizontal movement along Shanxi fault zone from 1996 to 1999 became obvious gradually. It can be divided into three parts by considering its tendency: (a) the dominant direction of movement in north of Xinzhou is NNE (0.8 cm); (b) in south of Quwo it is SSW (1 cm); (c) in the central area it is rather complicated, the deformation in the southern part is little more large, but in the view of whole area there is no dominant movement exist. Generally speaking, Shanxi fault zone is mainly controlled by the NNE-SSW-trending extension stress field, but there is no strike-slip movement. In the period of 1997 to 1998, there might be a clear stress disturb and it was essentially recovered in 1999. Then the Yangyuan-Hunyuan earthquake occurred. Very possible, this disturb is the triggering to the earthquake.