Irregular Ellipse Research Articles

Exploring the effects of the rocket exhaust of the Chang'E-5 lander on the lunar regolith using LROC NAC and landing camera images

During the Chang'E-5 (CE-5) lander descent process, the rocket exhaust disturbed the lunar surface of the landing area, which may have affected the properties of the collected samples. Therefore, it is necessary to explore the effects of lander exhaust on the landing area. In this paper, the images obtained by the Narrow Angle Camera (NAC) onboard the Lunar Reconnaissance Orbiter (LRO) were used to determine the exhaust-disturbed area. It is found that this area was featured by an increased reflectance of ∼10 ± 1% compared with the background (from I/F = 0.048 to 0.053). According to the magnitude of the change in the reflectance of the landing region, the disturbed area was divided into the focus disturbed zone (FDZ) and the diffuse disturbed zone (DDZ). The DDZ extends from the edge of the FDZ and has a lower reflectance anomaly. The whole exhaust-disturbed area was found to extend mainly via the north-south direction and to have the shape of an irregular ellipse. This spatial extent is highly related to the topographic factors rather than the obstacle avoidance process according to the topography and landing process. The phase function of the lunar surface was used to analyze the photometric performance of the disturbed area. The lower slope of the phase function in FDZ demonstrates less backscattering and a smoothing effect of the disturbed lunar surface. The CE-5 high-resolution LCAM images captured the smoothing and brightening effects of the lunar surface, which confirmed the variation in regolith properties. These effects are consistent with the inference from the NAC observations. The damage to the “fairy-castle” structure of the lunar surface could also contribute to surface smoothing. This study can provide a reference for the subsequent analyses of lunar samples and can help to enhance the understanding of the effect of lander exhaust on the lunar regolith.

Surface Upwelling off the Zhoushan Islands, East China Sea, from Himawari-8 AHI Data

The summer upwelling around the Zhoushan Islands is well-known. The previous concise review of (mostly) observational studies reveals that the present knowledge of the Zhoushan upwelling is unsatisfactory and has focused on seasonal variations. In this study, a sea surface temperature (SST) gradient-based upwelling detection algorithm was used. The Level 3 daily and hourly SST data from the geostationary satellite Himawari-8 were used to explore statistical features, seasonal variations, and short-term variations of the Zhoushan upwelling. Despite the duration period being like in previous studies, there is a new finding that the location of the upwelling center has a significant monthly migration. The statistical results show that the potential upwelling spots are clustered in the location with large topographic gradients and can be divided into four aggregation areas: between Gouqi Island and Lvhua Island, off Shengsi Island, around the Zhongjieshan Islands, and off the Taohua-Liuheng Islands. The core area of the Zhoushan upwelling is located at 122°E–123°E, 29.5°N–31.15°N with an irregular ellipse extending from southwest to northeast. The continuous cloud-free satellite images display that the lifecycle of the short-term variations was about 24 h and included two stages: intensification and decay. Meanwhile, the surface upwelling center has onshore–offshore movement under the advective transport of local tidal currents. A preliminary discussion suggests that the quasi-24 h periodic variations may be caused by the competing effect between tidal mixing and the stratification in the water column.

The effect of catalytic copper pretreatments on CVD graphene growth at different stages

The controllable synthesis of high-quality and large-area graphene by chemical vapor deposition (CVD) remains a challenge nowadays. The massive grain boundaries in graphene grown on polycrystalline Cu by CVD significantly reduce its carrier mobility, limiting its application in high-performance electronic devices. Here, we confirm that the synergetic pretreatment of Cu with electropolishing and surface oxidation is a more efficient way to further suppress the graphene nucleation density (GND) and to accelerate the growth rate of the graphene domain by CVD. With increasing the growth time, we found that the increasing amount of GND and growth rate of the graphene domain were both decreasing during the whole CVD process when the Cu surface was not oxidized. By contrast, they kept growing over time when the Cu surface was pre-oxidized, which suggested that the change trends of the effects on the GND and growth rate between the Cu surface morphology and oxygen were opposite in the CVD process. In addition, not only the domain shape, but the number of graphene domain layers were impacted as well, and a large number of irregular ellipse graphene wafers with dendritic multilayer emerged when the Cu surface was oxidized.

Study on attenuation coefficient characteristics of the in-seam seismic wave in fault and collapse column

Various types of geological structures exist in the working face of coal mine stope. Failure to identify the structural development in advance could defer the timely implementation of reasonable management measures, which may eventually affect production safety and connectivity. As a matter of fact, fine detection and interpretation problems of in-seam seismic wave caused by different types of geological anomalies such as faults and collapse columns can exist simultaneously in the working face of mining. In view of these problems, forward modeling research of three-dimensional seismic wave fields on geological models with fault and collapse column are carried out in this study. Meanwhile, in combination with the imaging results of in-seam seismic wave attenuation coefficient of the exposed fault and collapse column, the characteristics of in-seam seismic wave were analyzed. Following comparative analysis, we found the attenuation coefficient anomaly of the fault is generally banded and weakens at both ends of the fault. The attenuation coefficient of the collapse column presents as an irregular ellipse. The energy of the smaller collapse column has a relatively small attenuation, while the energy of the larger collapse column shows a significantly obvious attenuation.

Visualization Experiment of Bubble Coalescence in a Narrow Vertical Rectangular Channel

Visualization experiments were carried out and sliding bubble coalescence behaviors were observed for subcooled flow boiling in a narrow rectangular channel. The results show that the consecutive coalescence process is composed of four steps based on the bubble morphological change: approach, fusion, adjustment and stabilization, in which the more important are the fusion and adjustment of the bubble. Bubble always slides along the heating surface and does not lift off in coalescence process. Bubble diameter and sliding velocity increase first, then decrease and finally stabilize. Bubble shape also oscillates from an irregular ellipse to a stable circle. In addition, a new small bubble may be induced in the coalescence process.

Experimental Investigation on the Shape and Depth of Local Scour Hole Downstream of the Release Structure

Local scour downstream of the release structure is a critical problem to the safe and stable operation of water resources and hydropower engineering. In order to investigate the shape and depth of the scour hole under the equilibrium state of erosion and deposition downstream of an apron, a group of 16 experiments from the hydraulic similarity model test of Dangka Hydropower Station was conducted with the non-cohesive sediment of different median particle sizes under different flow rates in this study. The control variable method was to study the influence of the flow rate and sediment size on the shape of the scour hole to define the number of experiment times of each test group. The results showed that the plane shape of the scour hole was irregular ellipse or semi-ellipse. The depth and size of the scour hole increased with the increase of the flow rate, and decreased with the increase of the sediment size; the downstream longitudinal slope ratio of the scour hole increased with the increase of the sediment size. The coefficients of the upstream and downstream slope ratio of the local scour hole were 1/2 to 1/6 and about 1/10, respectively.

Evolution characteristic of gypsum-salt rocks of the upper member of Oligocene Lower Ganchaigou Fm in the Shizigou area, western Qaidam Basin

Over years of oil and gas exploration in the Qaidam Basin, reservoirs have been discovered in many layers. In the Shizigou area, western Qaidam Basin, the upper member of Oligocene Lower Ganchaigou Fm is an important target for oil and gas exploration, and gypsum-salt rocks are the high-quality caprocks for the preservation of oil and gas reservoirs in this area. For predicting oil and gas exploration direction and target in the western Qaidam Basin and providing guidance for its oil and gas exploration deployment, its depositional characteristics and environment of gypsum-salt rocks in this area were investigated based on the core observation, thin section identification, and analysis of grain size, sensitivity parameter ratios (Sr/Cu, Fe/Mn, (Fe + Al)/(Ca + Mg), V/(V + Ni) and Pr/Ph), pyrite content and inclusions. The following characteristics are identified. First, gypsum-salt rocks are mainly distributed in the depocenter of the lake basin and their thickness decreases towards the margin of the basin. They are laterally transformed into carbonate rocks or terrigenous clastic rocks. They are areally distributed in the shape of irregular ellipse. Second, gypsum-salt rocks are vertically developed mainly in the middle and upper parts of the upper member of Lower Ganchaigou Fm and they are interbedded with carbonate rocks or terrigenous clastic rocks. Their single layer thickness changes greatly, and there are many layers with good continuity. Third, Sand Group III to Group I in the upper member of Lower Ganchaigou Fm (inter-salt) are of reductive water environment of semi-deep to deep lake facies due to their sedimentation in an arid and hot climate. It is concluded that gypsum-salt rocks of the upper member of Lower Ganchaigou Fm are distributed widely with great accumulative thickness in this area; and that they are originated from deep lake water by virtue of evaporation, concentration and crystallization in an arid and hot climate instead of by hydrothermal fluid.

Sequence design for high squint spotlight SAR imaging on manoeuvring descending trajectory

Owing to the special geometry and system deviations of missile-borne spotlight SAR with manoeuvring motion, the sequence designed with traditional methods used in airborne and space-borne SAR systems perform low precision. An unequal azimuth and pitch beamwidths will make the beam footprint turn into an irregular ellipse, which consequently renders it difficult to gain the accurate echo bandwidth. In addition, biggish low pulse repetition frequency limit (LPRFL) caused by high velocity of the platform and beamwidth increases the complexity of system sequence design. In this study, a precise and effective sequence design method is developed based on effectual access of accurate LPRFL and high PRF limit with the consideration of ambiguity constraints and system deviations. Specifically, a new scene traversal method is proposed to gain the echo bandwidth with high precision for any azimuth and pitch beamwidths. Finally, a practical trajectory optimisation method is designed to further reduce the transmitted pulse number and lower the load of real-time processing. Plenty of simulation results verify its validity and effectiveness of the sequence design, which can be effectively applied to high manoeuvring spotlight SAR.

The detection of crackles based on mathematical morphology in spectrogram analysis.

Crackles are very common abnormal breath sounds in the lung and can be used to diagnose pulmonary diseases. In this study, a method is proposed for the detection of adventitious transient sounds from normal breath sounds. This method automatically recognizes crackles based on the extraction and analysis of spectral information from digitally recorded lung sounds. Various mathematical morphology feature sets were extracted through wavelet spectrogram analysis on pulmonary signals. In order to evaluate the effects of different wavelets types on crackle detection, different wavelets were tested. The results showed that the proposed method achieved an 86% accuracy in the detection of crackles. The spectrograms of the crackles in the lung exhibit irregular ellipse image features. For lung sound analysis, this is a useful feature that can be used for the immediate recognition and analysis of crackles.

Lip pattern in the interpretation of human emotions

In this paper, lip features are applied to classify the human emotion using a set of irregular ellipse fitting equations using Genetic Algorithm (GA). South-east Asian and Japanese faces are considered in this study. The parameters relating the face emotions, in either case, are entirely different. All six universally accepted emotions are considered for classifications. The method that is fastest in extracting lip features is adopted in this study. Observation of various emotions of the subject leads to unique characteristic of lips. GA is adopted to optimise irregular ellipse characteristics of the lip features in each emotion. That is, the top portion of lip configuration is a part of one ellipse and the bottom of different ellipse. Two ellipse-based fitness equations are proposed for the lip configuration and relevant parameters that define the emotion are listed. This approach has given reasonably successful emotion classifications.

Comprehensive study on a collapse column in Kongzhuang coal mine

Geological and geophysical theories and methodologies were applied to study a broken up body in Kongzhuang Coal Mine, which is suspected to be collapse column but maybe fault belt also. The purpose is to discover its features, formation and evolution history and its endangerment to coal mine running. Electric prospecting results indicate that the body is 70 m×40 m irregular ellipse in horizontal and about 150 m height slightly sloping column in vertical cross section. This means it is not a fault belt but a collapse column. Stratigraphy, petrology, sedimentation and structure geology studies have been conducted. The collapse column has the characteristics of dry falling accumulation, which is filled by broken rocks of Shanxi, Xiashihezi, Shangshihezi and Shiqianfeng Formation loosely almost without cementation. The collapse column was formed at late of the Paleogene Period, on the background of strong extensive geo-stress field. Its formation is the result of comprehensive actions of factors such as strata, lithologic characters, structure movement and underground water. Considering the well water transmissibility and loose structure of the collapse column, further prospecting and relative water and roof falling prevention countermeasures must be conducted.

Estimating shrinkage of large cooked beef joints during air-blast cooling by computer vision

In this work, computer vision techniques were applied to estimate the shrinkages of cooked meat joints during the air-blast cooling process. Three kinds of shrinkage were evaluated in the current research, i.e. shrinkages of major and minor axes, volume, and surface area. Since beef joints are normally in irregular ellipse shape, a region-based ellipse fitting method was employed to measure their major and minor axes before and after cooling. To calculate their volume and surface area, the images of beef samples were divided into numerous cross sections and each cross section was considered as a cylindrical disc. Based on the obtained values of beef joints using image processing techniques, linear models ( r 2 > 0.990) were developed for predicting the shrinkages of major and minor axes, volume, and surface area, respectively.

Modelling the otolith membrane using boundary-fitted coordinates

This paper describes a method for modelling biological processes that involve an irregular object. The process is assumed to be described by a system of partial differential equations in a planar region. The techniques described are specifically designed for irregular regions. The example of displacements of the otolith membrane under the force of gravity is used to illustrate the techniques. In this problem, the displacements are described by a nontrivial system of partial differential equations, and the membrane has the shape of an irregular ellipse. It is assumed that the membrane is fixed along its boundary. The solution technique has three main steps: first, a set of points is placed on the membrane; then the partial differential equations are discretized using those points; and finally the discrete equations are solved. The points are automatically generated using a numerical grid-generation technique, the equations are discretized using a transformation technique, and the discrete equations are solved using an iterative method. The solution technique is capable of accurately modelling processes in irregular regions and is easier to program than competing techniques, especially when the geometry of the model is changed during the study. If the geometry changes, a new grid needs to be generated, but nothing else need be changed in the code to study the new situation.

Hall Characteristics of RE-TM Amorphous Films with Biaxial Oblique Magnetic Anisotropy

A model of biaxial oblique magnetic anisotropy is presented to explain the irregular ellipse formed by the Hall loop coercive force (H c ') versus ? curve in polar coordinates when an oblique magnetic field is applied to high bias sputtered films. It was assumed that the H c ' versus ?characteristics (E) could be demonstrated by averaging the ellipses (E 1 and E 2 ) generated by the two easy axes (e.a.l and e.a.2). Good correspondence was observed between the measured and calculated values.

Notes on the Wollastonite rock-mass, and its associated minerals, of the Santa Fé Mine, State of Chiapas, Mexico

The geological features of the immediate neighbourhood of the Santa Fé Mine, which is situated about nine leagues nearly due east of the departmental town of Pichucalco, have been partially described by the author in a paper recently read before the Institution of Mining and Metallurgy. The key to the position, from the point of view alike of mineralogical and of economic interest, is found in a dome-shaped mass of wollastonite in a nearly pure condition, the horizontal section of which, at the lowest level where it has been sufficiently explored to determine its shape, takes the form of an irregular ellipse about 400 yards long by 160 yards wide. With the exception of the ore-bodies, which are developed on the outskirts of this mass and close to the contacts with other rocks, the whole mass is of nearly uniform composition, consisting of the mineral wollastonite in a nearly pure condition and very coarsely crystallized.