Effects on load handling of restricted and unrestricted shelf opening clearances

Changes in psychophysical lifting capacity with reductions in shelf opening clearances were experimentally determined. Three levels of shelf opening clearances were studied: unrestricted shelf opening clearance, loose shelf opening clearance (a clearance of 15 mm between the box width and the shelf opening), and tight shelf opening clearance (a clearance of 3 mm between the box width and the shelf opening). Two levels of lifting frequency (1 and 4 lifts/min.) and two lifting heights (floor to 0.81 m and 0.81 m to 1.52 m) were included. The metabolic energy expenditure rates and heart rates of the subjects (8 males and 8 females) at psychophysically acceptable weights of lift were also recorded to assess the physiological burden. The results indicated a decline in the psychophysical lifting capacity of the subjects as the shelf opening clearance became narrower. The decline in psychophysical capacity, compared to unrestricted shelf opening clearance for males was 9% when the shelf opening clearance was 15 mm. A further decline of almost 4% was recorded when the shelf opening clearance narrowed down to 3 mm. For females, the corresponding declines were approximately 10% and 4%. The effects of lifting frequency and height of lift were found to be consistent with previous findings.     

Evaluation of MODIS-based estimates of water-use efficiency in Amazonia

This study aimed to assess the spatial-temporal patterns of water-use efficiency (WUE) obtained through MODIS gross primary productivity (GPP) and evapotranspiration (ET) products (MOD17 for GPP and MOD16 for ET) in the Upper Tapajos and Curua-Una River basins, located in the oriental flank of the Amazon region, and to validate the results with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. The spatial variation of WUE was primarily related to the larger presence of forested areas in the Upper Tapajos River basin (western part) compared with the Curua-Una River basin (eastern part), which is situated within the so-called arc of deforestation. Temporally, WUE showed a pronounced seasonal pattern, varying with the dry and wet seasons in the region. A decrease of ~3% in WUE was observed during the dry season, which was related to the low water availability and increased vapour pressure deficit during the dry period, which induces stomatal closure, leading to a decline in the photosynthetic rate. Comparison between the WUE estimates obtained by MODIS data and observations from the LBA towers showed an average error of 17%, varying between ~12% and ~28% for the different sites. MODIS WUE depends on the accuracy of both GPP and ET estimation. In this sense, we highlight that improvements in both MODIS GPP and ET products are necessary and should focus on reducing the uncertainties related to the biophysical vegetation parameters and meteorological data that serve as input information in the algorithms.     

Modelling of clearances and joint flexibility effects in multibody systems dynamics

An effective method for modelling the dynamic response of multibody systems with flexible joints is presented. The method combines the use of finite element method with Kane's equations to present an algorithm strictly in terms of the generalized coordinates of the system. The procedures developed outline the automatic incorporation of the joint flexibility in the equations of motion, hence a more accurate mathematical model is developed. One other advantage to the method presented lies in the explicit forms of the coefficients needed in the analysis where they are readily expressed in a form suited for computer implementation. A discussion on possible applications is also presented.     

Investigation of joint clearances in a large-scale flexible solar array system

This paper is concerned with the effect of joint clearances in a large-scale flexible solar array system. The adopted solar array system is introduced and dynamics equation of the solar array system is presented by the Jourdain velocity variation principle firstly. Then detection of clearance contact and calculation of contact force are discussed. And finally the effect of joint clearances on the solar array system is studied in detail during the deployment process. Simulation results indicate that joint clearances will affect dynamic behaviors of the deployable mast, the container and the sub-panels in the solar array system. Furthermore, the presented method and simulation result have innovation and reference value for future researches.     

复杂环境下的遗留物检测算法

针对在复杂环境下检测遗留物体的问题,提出一种有效的算法。首先,采用局部更新的混合高斯模型与改进的三帧差分法分别得到前景,通过比较得到目标候选区域,并进一步采用阴影消除与连通域分析分割得到暂时静止物团块。其次对达到静止时间阈值的团块采用方向梯度直方图(HOG)行人检测,在排除驻留行人的可能后将其标记为遗留物。最后对检测出的遗留物进行加速分割检测特征(FAST)局部特征匹配,以克服行人遮挡、光线变化对结果的影响。实验结果表明,本算法具有较高的准确性和处理速度,能较好地克服复杂环境中存在的干扰影响。     

The impact of deforestation on the hydrological cycle in Amazonia as observed from remote sensing

Given widespread Amazonian deforestation, numerous studies have focused on how the regional hydrological cycle – in terms of precipitation (P) recycling from evapotranspiration (ET) – is impacted by deforestation. Nevertheless, climate macroscale and mesoscale models have given contradictory results on changes in ET and P with deforestation. To date, these results have not been evaluated with observations, so in this work, we assessed a decade of patterns in ET and P over deforested and forest areas using remote sensing (MODIS and TRMM, 2000–2012). We found a relative increase in ET and P in deforested areas, though there was a positive ET and P correlation over southern/deforested, and negative in northern/forested Amazonia. Although the absolute ET and P values are lower in deforested areas in comparison to border areas, we observed a positive change in ET and P in the last 10 years at the deforested areas. The increase in ET was larger within the deforested areas; meanwhile, P increased more from inside forest areas to the borders, which agrees with the ET and P correlation patterns. Our results help to inform the debate between the macroscale and mesoscale models, as deforestation impacts small-scale circulation patterns, turbulence, and moisture fluxes and convergence, and expand our understanding of the processes involved.     

Multitemporal Landsat data applied for deciphering a megafan in northern Amazonia

In this article, we present a protocol for the recognition of channels and waterbodies and for estimating their hydroperiod to both characterize a megafan system in northern Amazonia and discuss its dynamics in the late Quaternary. Our approach is based on analysis of a multitemporal Landsat Thematic Mapper/Enhanced Thematic Mapper Plus (TM/ETM+) data set consisting of 13 scenes acquired from 2000 to 2009. The images were primarily preprocessed using standard techniques for geometric and radiometric corrections. Following numerous tests with the most common water classifiers, we determined that a simple threshold on an infrared band, which provided a binary image containing both water and non-water classes, would adequately meet the goals of this article. The sum of all 13 classifications produced a new image, the hydroperiod product, with pixel values corresponding to the relative frequency of standing water. The results indicate that there is no permanent drainage network in the Viruá megafan, which displays only temporary channels with medium flood frequency and palaeochannels. These are arranged as complex distributary networks, as is typical of megafan depositional systems. The southern part of the megafan contains distributaries that are seasonally flooded, while the central and northern parts display an increased volume of palaeochannels. These data lead us to conclude that the locus of sediment deposition along this megafan system changed from north to south through time.     

Real-time abandoned and stolen object detection based on spatio-temporal features in crowded scenes

Abandoned and stolen object detection is a challenging task due to occlusion, changes in lighting, large perspective distortion, and the similarity in appearance of different people. This paper presents real-time detection methods of abandoned and stolen objects in a complex video. The adaptive background modeling method is applied to stable tracking and the ghost image removing. To detect abandoned and stolen objects, the methods determine spatio-temporal relationship between moving people and suspicious drops. The space first detection method measures the distance between a moving object and a non-moving object in spatial change analysis. The time first detection method conducts temporal change analysis and then spatial change analysis. The potential abandoned object is classified as a definite abandoned or stolen object by two-level detection approach. The time-to-live timer is applied by adjusting several key parameters on each camera and environment. In experiments, we show the experimental results to evaluate our proposed methods using benchmark datasets.     

基于实例分割模型优化的道路抛洒物检测算法

在交通安全领域,道路抛洒物易引发交通事故,构成了交通安全隐患。针对传统抛洒物检测方式识别率低、对于多类抛洒物检测效果不佳等问题,提出了一种基于实例分割模型CenterMask优化的道路抛洒物检测算法。首先,使用空洞卷积优化的残差网络ResNet50作为主干神经网络来提取特征并进行多尺度处理;然后,通过距离交并比（DIoU）函数优化的全卷积单阶段（FCOS）目标检测器实现对抛洒物的检测和分类;最后,使用空间注意力引导掩膜作为掩膜分割分支来实现对于目标形态的分割,并采用迁移学习的方式实现模型的训练。实验结果表明,所提算法对于抛洒物目标的检测率为94.82%,相较常见实例分割算法Mask R-CNN,所提的道路抛洒物检测算法在边界框检测上的平均精度（AP）提高了8.10个百分点。     

Power spectrum analysis of SAR data for spatial forest characterization in Amazonia

Power spectrum analysis was used for the analysis of spatial forest features from airborne X‐band synthetic aperture radar (SAR) data in the Brazilian Amazon. Spectral estimates were arrived at empirically by periodograms and correlograms, and from autoregressive moving‐average (ARMA) models. The spectral estimates derived from SAR data were validated by those derived from ground data with locational match. The results obtained by ARMA modelling revealed particularly good correspondence between remote sensing and reference data: repeating patterns at pixel level could be detected in the images. These patterns were shown to arise from canopy structure and distances between major tree individuals; and thus allowed the extraction of parameters of spatial forest structure, particularly of forest density. The method was applied to an example area of primary tropical forest, and its spatial patterns were modelled.     

Carbon budget estimation in Central Amazonia: Successional forest modeling from remote sensing data

The carbon budget resulting from the dynamics of forest vegetation was estimated spatially for a study region with intensive land use change in the Central Amazonia forest. Vegetation height was recovered from airborne SAR interferometry, and was used along with an established relationship between forest height and age for mapping the successional stages of vegetation. A map of forest ages could be generated and validated (age RMSE was 3.5 years). Biomass stocks and annual rates of increment in biomass could be attributed to the forest ages by a comprehensive growth model for forests in the study area. A conceptual model of land use change was developed for the study area that accounts for four different types of land use: primary forest, secondary forest, degraded forest and nonforest. The transition probabilities between those land use types were recovered from internal modeling of available data, from literature sources, and from large-scale remote sensing results. The land use change matrix, area-age densities of secondary forests, and a growth model, yield a spatialized estimate of the carbon budget. The committed emissions from annual land use change were computed. For the year 2000-2001 the carbon balance was negative, on an area of ca. 5700 ha, land use dynamics resulted in a release of approximately 16,000 t of carbon, mainly arising from the cutting of primary forest for agricultural purposes. The secondary forest carbon budget was almost balanced, and forest degradation was revealed less important.     

Fraction images derived from Terra Modis data for mapping burnt areas in Brazilian Amazonia

The objective of this paper is to present a method for mapping burnt areas in Brazilian Amazonia using Terra MODIS data. The proposed approach is based on image segmentation of the shade fraction images derived from MODIS, using a non‐supervised classification algorithm followed by an image editing procedure for minimizing misclassifications. Acre State, the focus of this study, is located in the western region of Brazilian Amazonia and undergoing tropical deforestation. The extended dry season in 2005 affected this region creating conditions for extensive forest fires in addition to fires associated with deforestation and land management. The high temporal resolution of MODIS provides information for studying the resulting burnt areas. Landsat 5 TM images and field observations were also used as ground data for supporting and validating the MODIS results. Multitemporal analysis with MODIS showed that about 6500 km² of land surface were burnt in Acre State. Of this, 3700 km² corresponded to the previously deforested areas and 2800 km² corresponded to areas of standing forests. This type of information and its timely availability are critical for regional and global environmental studies. The results showed that daily MODIS sensor data are useful sources of information for mapping burnt areas, and the proposed method can be used in an operational project in Brazilian Amazonia.     

森林覆盖区山地遥感地形校正的方法研究

基于山地遥感地形校正方法中的STS朗伯体模型和SCS模型,结合TM影像,提出了一种新的森林地形校正方法.该方法引入一个植被覆盖率参数用来估计亚像元中的各成分对辐亮度的影响,同时考虑了像元与像元之间的邻边效应影响.通过与其他现有的一些模型进行实地验证与检验,说明该方法能在一定的程度上解决不同覆盖程度的森林地形校正问题.     

Tropical forest backscatter anomaly evident in SeaWinds scatterometer morning overpass data during 2005 drought in Amazonia

A severe drought occurred in southwestern Amazonia in the dry season (June-September) of 2005. We analyzed 10 years (7/99-10/09) of SeaWinds active microwave Ku-band backscatter data collected over the Amazon Basin, developing monthly means and anomalies from those means in an effort to detect landscape responses to this drought. We compared these to seasonal accumulating water deficit anomalies generated using Tropical Rainfall Monitoring Mission (TRMM) precipitation data (1999-2009) and 100 mm mo^− 1 evapotranspiration demand as a water deficit threshold. There was significant interannual variability in dry-season monthly mean backscatter only for morning (c. 06:00 LST) overpass data, and little interannual variability in dry-season monthly mean backscatter for afternoon (c. 18:00 LST) overpass data. Strong negative anomalies in both morning-overpass backscatter and accumulating water deficit developed during July-October 2005, centered on the southwestern Amazon Basin, with a strong spatial correlation between morning-overpass backscatter anomalies and water deficit anomalies in September. This is the first reporting of tropical forest seasonal drought detection by active microwave scatterometry. Based on the differences between early-morning and late-afternoon backscatter variability, we hypothesize that as the drought persisted over several months, the forest canopy was increasingly unable to recover full leaf moisture content over night, resulting in anomalously low early-morning overpass backscatter.     

Applying SRTM digital elevation model to unravel Quaternary drainage in forested areas of Northeastern Amazonia

There has been an increasing number of articles stressing the advantage of applying remote sensing products of synthetic aperture radar (SAR) and interferometric synthetic aperture radar (InSAR) for rapidly enhancing the volume of geological data in Amazonian areas, where forest cover is dense and high, clouds are abundant and accessibility is limited. The majority of these studies has emphasized geomorphology as a tool for both discussing tectonic reactivations during the Cenozoic and reconstructing Quaternary paleolandscapes. This work applies Digital Elevation Model (DEM) derived from the Shuttle Radar Topography Mission (SRTM) for delineating past morphological features under dense rainforest in an Amazonian lowland area. Previous use of this tool in southwestern Marajó Island (northern Brazil) helped to delineate, with exceptional precision, a paleochannel network hidden under the rainforest, which would be barely detected with other available remote sensing products. Fieldwork revealed that these paleochannels are related to palimpsest drainage systems developed mostly during the last 40,000 ¹⁴C yr B.P. Measured altitudes acquired during topographic surveys attested that paleochannel areas are slightly higher than adjacent floodplains. This fact determined the successful application of SRTM–DEM for mapping paleochannels in Marajó Island. Integration of SRTM data with sedimentological information collected during fieldwork suggests paleoflows derived from continental areas located to south of the study area. This paleodrainage was active when the island was still connected to mainland. With island detachment due to reactivation of tectonic faults, the channels became abandoned and were progressively forested. The results obtained in the present study indicate that SRTM–DEM has high potential for unraveling similar morphological features from many other Amazonian areas with low topography and a dense forest cover.     

Markov point processes for modeling of spatial forest patterns in Amazonia derived from interferometric height

The spatial distribution of very large trees in primary Amazon forest is studied with an indicative data set. Very large trees with height larger than 30 m are shown to be highly influential on forest structure, ecology and biomass regime. In particular, they account for a large portion of total above-ground biomass. Their spatial patterns are extracted from airborne SAR data, namely from a digital model of interferometric forest height, by an approach of local maximum filtering. The spatial point patterns describing the distribution of very large trees in the forest within three sample blocks of 100 ha each are modeled by a series of Markov point process models. These models are fitted and assessed by standard spatial statistical methodology. Spatial distribution is regular, and interaction decreases with distance; very large trees are shown to exert repulsive interaction with their neighboring very large trees. The significance of these results for approaches of quantitative forest assessment in primary forests in the Brazilian Amazon is discussed.     

A note on regeneration with virtual copies

Regeneration with virtual copies (RVC) is a voting-based consistency control algorithm for replicated data objects in a distributed computing system. Proposed by Adam and Tewari (ibid., vol. 19, no. 6, pp. 594-602, 1993), it utilizes selective regeneration and recovery mechanisms for maintaining the availability and consistency of copies. This paper describes some problems with the original paper and proposes solutions     

基于决策树方法的云南省森林分类研究

森林分类对于理解森林生态系统结构和功能具有重要意义。由于云南省地形和森林类型复杂,首先按云南省的16个行政区划将全省Landsat TM影像分为对应的16个区域。以TM波段1~5和7,以及由植被指数、缨帽变换、主成分变换、DEM组成的18个变量组,统计训练样本光谱值均值变化和光谱值与频率间的关系。利用交点计算公式计算类间最佳分类界点进而建立决策树,逐一分离各区的所有森林类型,将分类结果合并得到云南省阔叶林、针叶林和针阔混交林类型分布图。最后将分类结果与监督分类中的最大似然比法的分类结果进行对比。结果表明:监督分类的总体分类精度为74.39%,Kappa系数为0.63,决策树方法的总体分类精度为86.61%,Kappa系数为0.80,说明决策树方法可以提取高精度的云南省森林类型,进而为该区域森林叶面积指数和生物量反演等研究提供基础数据支持。     

Investigating abandoned limestone mines in the West Midlands of England with scanning sonar

The use of remotely controlled scanning sonar is described as a site investigation tool in cavity surveillance. Abandoned and flooded limestone mineworkings beneath a proposed road in the West Midlands have been inspected; the resulting sonar records have been tested and matched with the only known abandonment plans of the mine. The use of Sonar enables the current status of the mine, pillars, roof and rooms to be assessed thoroughly before ground improvement and stabilization take place