Overlapping Area Research Articles

Constructing ecological security patterns with differentiated management intensity based on multifunctional landscape identification and multi-criteria decision-making

The trade-off of ecosystem services should be considered in ecological security pattern (ESP) construction, which can be reflected in landscape multifunctionality and comprehensive importance. Multi-intensity ESPs management is also required to achieve effective ecological planning. In this study, we proposed an approach of multi-intensity ESPs construction that integrated multifunctional landscape identification and multi-criteria decision-making into ecological source identification, and categorized ecological sources based on the “trend-status-risk” framework, with a case study in the city belt along the Yellow River in Ningxia. The results showed that the optimal weights of the four ecosystem services of habitat maintenance, water conservation, carbon sequestration and soil retention based on multi-criteria decision making were 0.5000, 0.2071, 0.1589 and 0.1340, respectively. The trade-off degree of the ecosystem services was 0.6612, and the overall conservation efficiency was 1.5212. Conservation priority areas based on multifunctional landscape identification and multi-criteria decision-making had an overlapping area of 2189.38 km2, accounting for 84.86% of that identified through landscape multifunctionality. The comprehensive ESP of the study area included 45 ecological sources covering a total area of 6067.14 km2 and 91 ecological corridors with a total area of 3331.62 km2. Multi-intensity ESPs aiming at conservation, prevention, restoration and reconstruction were established with corresponding management suggestions. The approach to constructing multi-intensity ESPs proposed in this study has application potential in ecological planning of ecologically vulnerable regions, facilitating differentiated ESP management.

A design approach of panel size for the cooperative development of cropland protection and coal mining in a coal-cropland overlapping area.

Cropland is the foundation of food security. Coal is the guarantee of energy security. As China's demand for coal and grain continues to increase, so does the overlap area of their production bases. Unrestrained underground mining can cause serious damage to cropland, leading to increasing conflicts between coal mining and food production. Thus, this paper used a partial backfilling mining technology to control surface subsidence and thus protect cropland. The key to successfully implementing the technology is how to design the panel size. However, the design efficiency of the conventional enumeration method is low. Therefore, this paper proposed a design approach based on improved particle swarm optimization. The results indicated that the approach could quickly find the optimal size of the panel compared with the enumeration method and particle swarm optimization. Moreover, if the longwall panel is mined according to the size designed by the approach, the cropland will be protected, and the cost will be reduced. This study can provide technical support for the cooperative development of cropland protection and coal mining in a coal-cropland overlapping area.

Design and development of a lightweight, low-cost cylindrical electrostatic clutch

Electrostatic clutches have the potential to enhance the functionality of actuators in the field of robotic industries, offering benefits such as heightened precision, rapid response times, and improved energy efficiency. These clutches serve as flexible, lightweight, and cost-effective mechanisms that find applications in a variety of force-dependent tasks, including robotic grippers, clamping systems, holding fixtures, lifting and hoisting equipment, and VR haptic gloves. However, incorporating these clutches into practical designs has proven to be challenging due to the inherent variability in holding forces and its range caused by the changing position of the moving electrodes and the corresponding overlapping areas. To address this issue, we propose a novel conceptual design of an electrostatic clutch that employs cylindrical electrodes. The aim of this study is to maintain a consistent friction force range by ensuring a constant overlapping area. In demonstrating the proof of concept, we delineate the design specifications for a clutch that is customized for a haptic force feedback glove. The clutch is characterized by its compact length, lightweight construction, and cost-effectiveness. Furthermore, this proposed clutch was designed with the specific intention of providing tactile force feedback by holding the fingers of users and addressing challenges related to wearability. An experiment was conducted to determine the minimum force required to perceive resistance on the finger, showcasing the clutch’s suitability for use in VR gloves. The results revealed that the average force exerted was measured at 2.8 N. The proposed clutch demonstrates the ability to hold a maximum force of 3 N at 1000 input voltage, which should maintain the allowable move length with a fixed force range. Additionally, the response time of the proposed clutch is documented to be less than 270 ms.

Meteorological drought migration characteristics based on an improved spatiotemporal structure approach in the Loess Plateau of China

The development of drought has spatial and temporal synchronization. Previous studies usually explore the spatial and temporal evolution of drought separately. Moreover, existing approaches are based on a fixed overlapping area and do not consider the variable drought cluster area during development. This study proposes an improved and simple approach to derive dynamic overlapping area threshold for 3-dimensional droughts extraction. Based on the one monthly Nonparametric Standardized Precipitation Index (NSPI), this improved approach was applied for investigating the migration characteristics of meteorological drought events in the Loess Plateau of China. Then, Random Forest and Extreme Gradient Boosting model with Shapley additive explanation values were used to quantify the importance of driving factors on the dynamics of drought characteristics. The results showed that: (1) the improved approach has a better performance on identifying prolonged droughts than the method using a fixed overlap area threshold; (2) spatially, meteorological drought events with high severity (DS), long duration (DD), large effected area (DA) and fast migration velocity (DV) mainly occur in the central region; (3) temporally, droughts are expected to aggravate with significantly increased DS and DA which are mainly caused by increased temperature and vegetation; and (4) meteorological droughts have a preferred westward migration direction and three dominant migration paths, which are crucial for local drought prevention and control. The findings of this study provide new perspectives on drought migration characteristics, which are important for the exploration of drought-driven mechanisms, risk assessment and future prediction.

Integrating biogeographic approach into classical biological control: Assessing the climate matching and ecological niche overlap of two natural enemies against common ragweed in China

Plant invasion is considered a high priority threat to biodiversity, ecosystems, the environment, and human health worldwide. Classical biological control (biocontrol) is a generally safer and more environmentally benign measure than chemical controls in managing invasive alien plants (IAPs). However, the impacts of climate change and the importance of climate matching in ensuring the efficiency of biocontrol candidates in controlling IAPs are likely to be underestimated. Here, based on the ensemble model and n-dimensional hypervolumes concepts, we estimated the overlapping areas between Ambrosia artemisiifolia and its two most effective natural enemies (Ophraella communa and Epiblema strenuana) under climate change in China. Moreover, we compared their ecological niches, further assessing the impact of climate change on the efficiency of two natural enemies in controlling A. artemisiifolia in China. We found that the potentially suitable areas of the two natural enemies and A. artemisiifolia were primarily influenced by temperature and human influence index variables. Under near-current climate, the overlapping area between O. communa and A. artemisiifolia was the largest, followed by E. strenuana and A. artemisiifolia, and both two natural enemies and A. artemisiifolia. The ecological niche between A. artemisiifolia and O. communa was most similar (0.64), followed by A. artemisiifolia and E. strenuana (0.55). The separate control (the niche separation areas of the two natural enemies against A. artemisiifolia) and joint-control (the niche overlap areas of the two natural enemies against A. artemisiifolia) efficiencies of the two natural enemies against A. artemisiifolia will both increase in future climates (the 2030s and 2050s) in northern and northeastern China. Our findings demonstrate a new approach to assess control efficiency and screen potential release areas of two natural enemies against A. artemisiifolia in China without the need for actual field release or experimentation. Moreover, our findings provide important clues for ensuring the classical biocontrol of IAPs worldwide.

The ability to appropriately distinguish throws for different target positions.

Repeated and accurate throwing of an object to a target position is a special human motor skill. It is particularly important to understand accuracy, which has received less attention than speed due to difficulties in measurement. Accuracy has been studied in terms of reducing errors against a single target, but also in terms of distinguishing appropriate throws for targets in different positions. In this study, this ability was investigated by evaluating the two-dimensional distributions of the pitch locations of 15 pitches to three target positions in university students with and without baseball experience. The center, major and minor axis length, major and minor axis ratio, slope, area, and percentage of overlapping area of the 95% confidence ellipse were compared between target positions and participants using a two-way repeated-measures analysis of variance (ANOVA). The center and area of the ellipse indicate the mean and variability of the error, respectively. The lengths of the major axes correspond to the variability of the release timing, and the minor axes correspond to the variability of the release point in space. Therefore, the ratio of the major and minor axes indicates how the variability of the pitching motion is controlled. The slope of the ellipse corresponds to the throwing arm's trajectory, and the percentage of overlap area means the ability to distinguish throws at different target positions. The result showed a main effect of participants on all indices except the center of the ellipse. This indicates that participants can generally distinguish throws by target positions regardless of their baseball experience, although participants with baseball experience may naturally reduce variability. Furthermore, participants with baseball experience demonstrated a decrease variability in release timing, which is a primary contributor to the pitch location variability, relative to the spatial variability of the pitching movements. This reduction in timing variability may be attributed to advanced motor control mechanisms.

Flexible strain sensors based on gold nanowire dominoes for human motion detection

Flexible strain sensors have broad application potentials in sports, healthcare and various other fields. However, the large-scale fabrication of strain sensors with both high sensitivity and stretchability simultaneously is still challenging nowadays. Inspired by the game of dominoes, we proposed a strain sensor with a novel mechanism based on gold nanowire (AuNWs) dominoes. Unlike the general piezoresistive strain sensors of micro-crack or percolation mechanisms, AuNWs domino sensors realize the mechanical sensing due to the change of the overlapping area when subjected to external force. The strain sensor performs excellently with a wide detection range(0–250 % strain), an ultrahigh sensitivity (gauge factor of 490 at a strain of 10 %), and high durability and repeatability. The in-situ characterization proved that the overlapped AuNWs dominoes slid and displaced with the increasing strain, and the overlap area decreased before the fracture occurred, thus keeping the effective conducting pathway. Based on its innovative sensing mechanism and superior sensing performance, AuNWs domino sensors effectively suppress conductive path cracks and have the potentials for wearable healthcare devices.

Sampling Survey Method of Wheat Ear Number Based on UAV Images and Density Map Regression Algorithm

The number of wheat ears is one of the most important factors in wheat yield composition. Rapid and accurate assessment of wheat ear number is of great importance for predicting grain yield and food security-related early warning signal generation. The current wheat ear counting methods rely on manual surveys, which are time-consuming, laborious, inefficient and inaccurate. Existing non-destructive wheat ear detection techniques are mostly applied to near-ground images and are difficult to apply to large-scale monitoring. In this study, we proposed a sampling survey method based on the unmanned aerial vehicle (UAV). Firstly, a small number of UAV images were acquired based on the five-point sampling mode. Secondly, an adaptive Gaussian kernel size was used to generate the ground truth density map. Thirdly, a density map regression network (DM-Net) was constructed and optimized. Finally, we designed an overlapping area of sub-images to solve the repeated counting caused by image segmentation. The MAE and MSE of the proposed model were 9.01 and 11.85, respectively. We compared the sampling survey method based on UAV images in this paper with the manual survey method. The results showed that the RMSE and MAPE of NM13 were 18.95 × 104/hm2 and 3.37%, respectively, and for YFM4, 13.65 × 104/hm2 and 2.94%, respectively. This study enables the investigation of the number of wheat ears in a large area, which can provide favorable support for wheat yield estimation.

Failure mechanism and divisional differentiated control of surrounding rock in mining roadway under remaining coal pillar in close‐distance coal seam

AbstractRegarding the issue of intense mining pressure appearing in the underlying gateway below the remaining coal pillar in the close‐distance coal seam (the remaining coal pillar is perpendicular to the underlying section coal pillar), 401 working face is used as the engineering background. Field measurements, laboratory experiments, numerical simulations, and engineering verification techniques are used to study the abutment pressure's evolution properties and the plastic zone's propagation laws before and after the underlying coal seam roadway experienced the mining impact. The conclusions are as follows: ① The maximum plastic area on the two sides and the roof of the roadway underlying the gob are up to 2 and 1.5 m, whereas the maximum plastic area on the two sides and the roof of the roadway underlying the remaining coal pillar are up to 5 and 4.5 m, respectively. Moreover, the plastic area extends along the two sides, and the section coal pillar is completely broken when the working face is mined below the remaining coal pillar. ② The stress increase coefficient K in the overlap area of the remaining coal pillar and the underlying section coal pillar reaches 3.4 when the mining face penetrates the underlying remaining coal pillar and the advance abutment pressure is overlaid with the concentrated stress of the coal pillar. ③ When the underlying working face is mined to 4, −2, −8, and −14 m away from the remaining coal pillar, the damage range of the roadway 5–10 m ahead increases in turn. At the same time, the maximum plastic area of the roof passes through the plastic area of the upper coal seam floor. Therefore, the underlying and transition areas on both sides of the remaining coal pillar are divided into Area I (15 m) → Area II (the most complicated area to control under the remaining coal pillar, 20 m) → Area III (25 m) according to the width. Furthermore, the divisional differentiated combined control technology of channel steel truss anchor cable with joint double‐way locking control function of roof and coal pillar in Areas I and III, while channel steel truss anchor cable with joint double‐way locking control function of roof and side + high resistance integral door‐type support is proposed in Area II. Field engineering practice shows that the deformation of the roadway surrounding rock can be controlled within 210 mm after adopting the above divisional combined control technology. Finally, the mining operation can safely and efficiently pass through the remaining coal pillar. The research results have important reference values for surrounding rock control of mining roadways in the overlapping area of similar “+”‐type cross‐working face.

Influence of Coal Mining on Historical Buildings: Case Study in Shanxi

Numerous historical buildings exist in Shanxi Province, a major coal producing area in China, so there exist many overlapping areas between ancient wooden buildings and coal mining. Coal mining in overlapping areas will lead to surface subsidence, which will have an impact on historical buildings. Based on the distribution of historical buildings and the distribution and mining of coal resources in Shanxi Province, this paper concludes that the overlapping areas of coal mining and ancient wooden buildings in Shanxi Province are mainly concentrated in Changzhi City, and the Lu'an mining area in Changzhi City is selected as the research object. In addition, using the gray correlation analysis method, the surface subsidence coefficient, which characterizes the intensity of mining subsidence, is used as the reference sequence. Seven factors selected from the geological conditions and mining conditions of the Lu'an mining area are used as the comparison sequence to calculate the gray correlation between each influencing factor and the surface subsidence coefficient, and to obtain that geological factors such as the nature of the overlying rock layer, bedrock thickness and dip angle of the coal seam, and mining factors such as mining height, average mining depth and working face size largely determine the surface subsidence coefficient. The surface subsidence in the overlap area could largely be influenced by geological factors such as the nature of the overlying rock layer, bedrock thickness and coal seam inclination, and mining factors such as mining height, average mining depth and working face size. Finally, we investigate the possible effects of surface subsidence on ancient wooden buildings in the overlapping area with the surface subsidence and formation mechanism and propose technical measures to reduce the effects of surface subsidence due to coal mining on historical buildings in the overlapping area.

同域分布中华鬣羚与中华斑羚时空生态位特征

PDF HTML阅读 XML下载 导出引用 引用提醒 同域分布中华鬣羚与中华斑羚时空生态位特征 DOI: 10.5846/stxb202108022099 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国博士后科学基金面上项目(2021M690484);国家自然科学基金(31801991);第二次青藏高原综合科学考察研究资助(2019QZKK0402);成都大熊猫繁育研究基地自立课题(2021CPB-B17) Spatio-temporal niche characteristics of sympatric Chinese serow and Chinese goral Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为了解同域分布有蹄类在环境复杂的山地森林生境中以何种方式维持种间关系以实现稳定共存,基于物种分布模型与日活动模式分析了四川省岷山、邛崃、大相岭、小相岭和凉山五大山系同域分布中华鬣羚(Capricornis milneedwardsii)与中华斑羚(Naemorhedus griseus)的时空生态位特征。结果显示:(1)在四川省五大山系,中华鬣羚的适宜栖息地面积为28006.07 km2,占研究区总面积的26.18%,其中高适宜栖息地面积为10015.90 km2,中华斑羚的适宜栖息地面积为21073.32 km2,占研究区总面积的19.71%,其中高适宜栖息地面积为8396.22 km2;(2)中华鬣羚与中华斑羚在生境因子选择上相似性高、栖息地重叠面积大,其空间生态位重叠度指数D=0.776,I=0.949,其适宜栖息地的主要重叠区域位于岷山和邛崃山系;(3)中华鬣羚与中华斑羚的日活动节律重叠指数为0.812;(4)中华鬣羚与中华斑羚属于同域分布的资源利用型竞争物种,中华鬣羚的存在会显著影响中华斑羚的日活动节律(P=0.016);二者同域分布时都会增加其昼间活动强度,并增加活动高峰期的强度及持续时间。本研究初步分析了中华鬣羚与中华斑羚的时空生态位特征,揭示了二者在空间、时间生态位上种群共存及种间竞争的耦合关系。研究有利于深入理解同域分布动物时空生态位特征、近缘物种的共存机制及种间竞争关系,为有蹄类等珍稀野生动物种群及栖息地的保护提供科学参考。 Abstract:In order to understand how the sympatric distribution of ungulates maintains interspecific relationships to achieve stable coexistence in a complex mountain forest habitat, this study analyzed the spatial and temporal ecological niche characteristics of sympatric distribution of the Chinese serow (Capricornis milneedwardsii) and the Chinese goral (Naemorhedus griseus) in the Minshan, Qionglai, Daxiangling, Xiaoxiangling and Liangshan mountain systems in Sichuan Province based on species distribution models and daily activity patterns. The results showed that:(1) in the five mountains of Sichuan Province, the suitable habitat area of the Chinese serow was 28006.07 km2, accounting for 26.18% of the total area of the study area, among which the highly suitable habitat area was 10015.90 km2. The suitable habitat area of the Chinese goral was 21073.32 km2, accounting for 19.71% of the total area of the study area, among which the highly suitable habitat area was 8396.22 km2. (2) Niche overlap indices, calculated by ENMTools, showed that the two species had high overlap (D=0.776, I=0.949). The Chinese serow and the Chinese goral had high selection similarity on environmental variables and large habitat overlap area. In terms of spatial distribution, the main overlapping areas of the Chinese serow and the Chinese goral suitable habitats are the Minshan Mountain and the Qionglai Mountain. And, the overlapping area of suitable habitats is 12967.50 km2, accounting for 46.30% and 61.54% of their total suitable habitat area, the overlapping area of highly suitable habitats was 5955.28 km2, accounting for 59.46% and 70.93% of their highly suitable habitats. (3) There was no significant difference in daily activity rhythm between the Chinese serow and the Chinese goral (P=0.534), and the overlap index was 0.812. (4) They were exploitation competition species, and the presence of the Chinese goral significantly affected the daily activity rhythm of the Chinese serow (P=0.016). They increased their diurnal activity intensity and enhanced the intensity and duration of their peak activity when they were sympatric distribution. In this study, the spatial and temporal niche characteristics of the Chinese serow and the Chinese goral were analyzed, and the coupling relationship of population coexistence and interspecific competition in spatial and temporal niche was revealed. This study, on the one hand, is helpful to deeply understand the spatial and temporal niche characteristics of sympatric distribution animals, the coexistence mechanism and interspecific competition of the related species. On the other hand, it provides a scientific reference for the conservation of rare wildlife populations and habitats, such as ungulates. 参考文献 相似文献 引证文献

Effect of heat treatment temperature on microstructure and tensile properties of austenitic stainless 316L using wire and arc additive manufacturing

The effect of heat treatment temperature on the microstructure and tensile properties of 316L stainless steel fabricated by wire and arc additive manufacturing was studied in this paper. Heat treatment was used to uniformize the microstructure, eliminate the anisotropic tensile properties in as-built 316L part, and improve the poor elongation caused by the multilayered structure of alternating re-melting area (RA) and overlapping area (OA). The results showed that the heat treatments below 1000 °C had no significant effect on the multilayered structure and columnar austenite grains, but only changed the morphology and content of ferrite and σ phase within the grains. With the increase of the heat treatment temperature, ferrite transformed into σ phase and the fraction of second phase gradually decreased, leading to the slight increase of elongation but decrease of material strength and its anisotropic degree. After solution annealing above 1000 °C, the ferrite and σ phase was nearly dissolved in the austenite matrix. The austenite recrystallized and the multilayered structure was destroyed, which played a major role in the tensile properties. With the increase of heat treatment temperature, the fraction of recrystallization increased, resulting in decrease of material strength. The elongation was greatly improved and reached that of the annealed state, and its anisotropic was almost eliminated.

Enhanced Graphene Sensors via Multi-Lasing Fabrication

Resistive strain and bending sensors offer a versatile platform for sensing various physical parameters with relatively little effort and budget. The lightweight, robust and compact sensors are extensively used in manifold low-power applications. Recently, scribed and flexible laser-induced graphene sensors have shown potent capabilities for a variety of measurements, including flow, deflection, and force. Achieving a high sensitivity to various stimuli remains a challenge due to limited change in relative resistance. In this paper, we report a multifunctional LIG sensor with widely tunable properties and significantly enhanced electromechanical performance. A method of repeated laser writing is used to increase the porosity, the uniform carbonization degree and, most importantly, the sensitivity of the LIG sensors. A gauge factor of 91.2 is achieved after three-times laser writing at low power, which is an increase of 750% to one-time laser writing and 720% higher than the ones previously reported for LIG strain sensors. The increase is attributed to a more porous surface morphology that provides more overlapping area and displacement of the graphene layers. A homogeneous bidirectional response was obtained by scribing the electrodes on both faces of the substrate. Parylene C-coating is used to protect the LIG sensors from environmental effects. Coated sensors were packaged to a PCB assembly for easy integration into various applications. An example is a LIG bending sensor customized for velocity profile monitoring of Unmanned Aerial Vehicles in the outdoor environment.

Intelligent Splicing Method of Virtual Reality Lingnan Cultural Heritage Panorama Based on Automatic Machine Learning

With the increasing expansion of virtual reality application fields and the complexity of application content, the demand for real-time rendering of realistic graphics has increased sharply. This research mainly discusses the intelligent mosaic method of virtual reality Lingnan cultural heritage panorama based on automatic machine learning. In order to effectively make up for the impact of the insufficiency of the collection process on the quality of the final panoramic image of Lingnan cultural heritage, it is necessary to minimize the irregular rotation of the camera and collect images according to the overlapping area between adjacent images of appropriate size. In order to make Lingnan cultural heritage panoramic images have better visual effects, it is necessary to preprocess the images before image registration and fusion. Image preprocessing mainly includes image denoising and image projection transformation. In this study, cylindrical projection is used to construct the panorama of Lingnan cultural heritage. For each Lingnan cultural heritage training image, we first perform image segmentation to obtain multiple regions and extract the visual features of each region. We use automatic machine learning models to train the visual feature set and use the bagging method to generate different training subsets. In order to generate each component classifier, we determine the overlap area of the two images according to the matched SIFT feature points and determine the best stitching line during the implementation of stitching. In this paper, the number of pixels in the first row of the overlapping area is used to determine the candidate stitching line column, and the best stitching line position should be determined in consideration of the smallest color difference in the stitching area and the most similar texture on both sides. This article uses a Java Applet-based approach to realize virtual roaming of viewing panoramic images of Lingnan cultural heritage in IE browser. The highest accuracy of SIFT is 82.22%, and the lowest recognition time is 0.01 s. This research will promote the development of Lingnan cultural heritage.

Change in nostril ratio after cleft rhinoplasty: correction of nostril stenosis with full-thickness skin graft.

BackgroundPatients with secondary deformities associated with unilateral cleft lip and nose might also suffer from nostril stenosis due to a lack of tissue volume in the nostril on the cleft side. Here, we used full-thickness skin grafts (FTSGs) to reduce nostril stenosis and various methods for skin volume augmentation. We compared the changes in the symmetry of both nostrils before and after surgery.MethodsFrom February 2016 to January 2020, 34 patients underwent secondary cheiloplasty and open rhinoplasty for secondary deformities of the unilateral cleft lip and nose with nostril stenosis. FTSG was used on the nostril floor, nasal columella, and alar inner lining. The measured nasal profile included the nostril surface, nostril circumference, width of the nostril floor, and distance from the alar-facial groove to the nasal tip. The “overlap area,” which was defined as the largest overlapping area when the image of the cleft nostril was flipped to the left and right and overlaid on the image of the normal side nostril, was also calculated. The degree of symmetry was evaluated by dividing the value of the cleft side by that of the normal side of each measured profile and expressed as “ratios.”ResultsThe results of all profile ratios, except for the nostril floor width, became significantly close to 1, which represents full symmetry. The overlap area ratio improved from 62.7% to 77.3%, meaning that the length and width of the nostril as well as the overall shape became similar (p<0.05).ConclusionWhen performing cleft rhinoplasty with nostril stenosis, FTSG is useful to achieve symmetry in the nostril size and shape. Skin grafting is simpler to perform than the other types of local flap, and the results are generally satisfactory.

Panoramic Image Stitching: A Survey

This electronic document is a report on Image Stitching. Image stitching is the process of creating an image panorama from a given set of images that have some common(overlapping) area in them. Previous researches done on this topic show that there is still a lot of scope for improvement in this field as although we are able to achieve good results but we haven’t really been able to achieve perfection. There are a lot of factors that are to be blamed here. While Stitching Images, there could be many challenges such as images being corrupt by noise and/or presence of parallax in the images. Image Stitching process is divided into 5 major steps: Image Registration, Feature Detection, Feature Matching, Homography Estimation and Image Blending. In this document we are going to discuss the current status of image processing techniques and what are the challenges being faced.

Buckling performance of high-precision variable stiffness composites laminate based on automatic placement technology

The buckling resistance of the variable stiffness composite laminates laid by the automatic placement can be effectively improved by tailoring the in-plane stiffness. During the placement process, laying the trajectory path planning is one of the key technologies to achieve variable stiffness design. So, the fiber trajectories composed of angle linear variation, constant-curvature curve and quadratic Bezier curve were taken as the research object, and the parametric analysis of its compression buckling performance was carried out. Finally, the influence of tape width on the surface profile accuracy and buckling resistance mechanical properties was studied using a finite element model. The results show that under the compression condition, the secondary Bezier curve has the best buckling resistance, and the equal curvature curve is least affected by the curvature constraint. The width of the tape is negatively correlated with the area of the overlap area and the buckling resistance, when the tow width of the fiber placement head is constant. Using the largest tape size can minimize the overlapping area and improve the profile accuracy of the composite structure. At the same time, it is guaranteed that the buckling performance of the structure is improved by 37.3%.

The Many-Body Expansion for Aqueous Systems Revisited: I. Water-Water Interactions.

We revisit the many-body expansion (MBE) for water-water interactions by examining the effects of the basis set, including those resulting from the basis set superposition error (BSSE) correction, and electron correlation on the various terms for selected sizes of water clusters up to n = 21. The analysis is performed at the second-order Møller-Plesset (MP2) perturbation theory with the family of augmented correlation consistent basis sets up to five zeta quality (aug-cc-pVxZ, x = D, T, Q, 5) for the (H2O)n, n = 7, 10, 13, 16, and 21, clusters for which we report either the complete MBE (for n = 7, 10) or the ones through the 6-body (for n = 13) and the 5-body terms (for n = 16, 21). For the n = 3 and 7 clusters, we also report the analysis at the coupled cluster with single, double, and perturbative triple replacements in order to assess the effects of a higher correlation on the magnitude and percentage of the various MBE terms. Our results suggest that the oscillatory behavior around zero found for the 5-body and larger terms is solely an artifact of the (small) size of the basis set. Indeed, all terms above the 4-body converge monotonically to practically zero upon increasing the size of the basis set toward the complete basis set (CBS) limit. In that respect, the BSSE-corrected 5-body and above terms do not exhibit the oscillatory behavior on either side of zero with the basis set observed for the BSSE-uncorrected terms. In addition, the magnitudes of the 5-body and above terms are accurately reproduced even with the smaller basis set of the series (aug-cc-pVDZ) once the BSSE correction is taken into account. The same level of theory (MP2/aug-cc-pVDZ, BSSE-corrected) also accurately reproduces the MP2/CBS values of the 3- and 4-body terms. The contribution of electron correlation to the 3- and 4-body terms is quite small so that neglecting the correlation contribution in all terms above the 3-body results in an error of the order of 0.1%. The BSSE correction to the largest 2-body term in the MBE was accurately estimated from the function a[1 + erf( - b·R)], which is proportional to the common (overlapping) area between two Gaussian distributions whose centers are separated by R with the constants a and b fitted to the calculated BSSE corrections for the individual 2-body terms of the clusters with each basis set and R is the distance between oxygen atoms. Our results demonstrate that the MBE for water-water interactions converges by the 4-body term since any finite terms above the 4-body are artifacts of the size of the basis set. The MBE can thus be safely truncated at the 4-body term when either a very large basis set is used or BSSE corrections are taken into account even with the smaller aug-cc-pVDZ basis set. We expect these findings to have important consequences in the pursuit of accurate ab initio based many-body molecular dynamics simulations for aqueous systems.

Adhesive joining of sisal/jute/hybrid composites with drilled holes in lap area

Growing awareness about sustainable development and the environmental problems involved in using nonbiodegradable materials has motivated the research community to develop environment-friendly materials. Developments have been achieved in the field of natural fibers and biopolymers, still there remain unanswered questions regarding the high-quality cost-effective manufacturing of natural fiber reinforced composites. The natural fiber-based polymeric composites are being used extensively in engineering applications, especially in the nonstructural parts and components. Near-net processing techniques such as compression molding, extrusion, and injection molding are well-developed for natural fiber reinforced composites. However, secondary processes such as joining, machining, and surface modification are still unexplored and need to be investigated in detail. The present research endeavor is an attempt to experimentally investigate the adhesive joining behavior of jute/sisal reinforced epoxy composites. The laminates based on three different material configurations in woven mat form, namely, pure jute, pure sisal, and hybrid jute/sisal reinforced epoxy have been fabricated by hand layup process. Different lap joint configurations with through holes in adherends overlapping area have been investigated. It has been established experimentally that the holes in the adherends provide a hinge-effect in the overlapping area and help in defining the failure load of the composite joint. The different arrangement of holes has been investigated and the best design of hole arrangement has been proposed for adhesive joining of jute/sisal fiber reinforced epoxy laminates. It was found that the holes (filled with an epoxy adhesive) in the overlap area result in 6–18% improvement in the failure load for different materials as compared to the joints with only adhesive bonding. Moreover, the field-emission scanning electron microscopy micrographs have been used to understand the failure mechanism of the adhesively bonded natural fiber reinforced composite laminates.

Prioritizing COVID-19 tests based on participatory surveillance and spatial scanning

ObjectivesThis study aimed to identify, describe and analyze priority areas for COVID-19 testing combining participatory surveillance and traditional surveillance. DesignIt was carried out a descriptive transversal study in the city of Caruaru, Pernambuco state, Brazil, within the period of 20/02/2020 to 05/05/2020. Data included all official reports for influenza-like illness notified by the municipality health department and the self-reports collected through the participatory surveillance platform Brasil Sem Corona. MethodsWe used linear regression and loess regression to verify a correlation between Participatory Surveillance (PS) and Traditional Surveillance (TS). Also a spatial scanning approach was deployed in order to identify risk clusters for COVID-19. ResultsIn Caruaru, the PS had 861 active users, presenting an average of 1.2 reports per user per week. The platform Brasil Sem Corona started on March 20th and since then, has been officially used by the Caruaru health authority to improve the quality of information from the traditional surveillance system. Regarding the respiratory syndrome cases from TS, 1588 individuals were positive for this clinical outcome. The spatial scanning analysis detected 18 clusters and 6 of them presented statistical significance (p-value < 0.1). Clusters 3 and 4 presented an overlapping area that was chosen by the local authority to deploy the COVID-19 serology, where 50 individuals were tested. From there, 32 % (n = 16) presented reagent results for antibodies related to COVID-19. ConclusionParticipatory surveillance is an effective epidemiological method to complement the traditional surveillance system in response to the COVID-19 pandemic by adding real-time spatial data to detect priority areas for COVID-19 testing.