Research on Crack Depth Measurement in Concrete by Using Rayleigh Waves

The possibility of crack depth measurement in concrete by using Rayleigh waves and the feasibility of measurement method are3 introduced in this paper. The principle of crack measurement in concrete by using in-plan Rayleigh waves and the measurement analysis method are studied by using finite clement method

Joint Power and Multiple Access Control for Wireless Mesh Network with Rose Projection Method

This paper investigates the utility maximization problem for the downlink of the multi-interface multichannel wireless mesh network with orthogonal frequency division multiple access. A cross-layer joint power and multiple access control algorithm are proposed. Rosen projection matrix is combined with Solodov projection techniques to build a three-memory gradient Rosen projection method, which is applied to solve this optimization problem. The convergence analysis is given and simulations show that the proposed solution achieves significant throughput compared with existing approaches

FeatureBooster: Boosting Feature Descriptors with a Lightweight Neural Network

We introduce a lightweight network to improve descriptors of keypoints within the same image. The network takes the original descriptors and the geometric properties of keypoints as the input, and uses an MLP-based self-boosting stage and a Transformer-based cross-boosting stage to enhance the descriptors. The enhanced descriptors can be either real-valued or binary ones. We use the proposed network to boost both hand-crafted (ORB, SIFT) and the state-of-the-art learning-based descriptors (SuperPoint, ALIKE) and evaluate them on image matching, visual localization, and structure-from-motion tasks. The results show that our method significantly improves the performance of each task, particularly in challenging cases such as large illumination changes or repetitive patterns. Our method requires only 3.2ms on desktop GPU and 27ms on embedded GPU to process 2000 features, which is fast enough to be applied to a practical system.Comment: 14 pages, 8 figures, 5 table

Contamination levels assessment of potential toxic metals in road dust deposited in different types of urban environment

A total of 42 samples of road dust were collected along ring road, city centre, city side, and freeway in Urumqi, China. Total concentrations of Cd, Cr, Cu, Ni, Pb, Mn, Be, Co, Zn, and U were determined by using the inductively coupled plasma-mass spectrometry in order to assess and to compare road dust contamination levels of metals among the four roads. The results show that, among the four categories of roads, mean concentrations of Co and U vary little. City centre locations show strong enrichments of Cd, Cu, Pb, and Be. Along the ring road, the highest mean concentrations were found for Cr, Ni, Mn, and Co. However, the highest concentrations of Zn and U were found along the freeway. The cluster analysis shows that three main groups can be distinguished. Every group may be associated with different main sources and concentrations of the metals. The results of contamination assessment reveal that, among all of the potential toxic metals, Cd, Cu, and Zn pollution were obviously heavier with moderate or high contamination indices for most road dust samples, while Cr, Ni, and Pb contamination were lower along the four categories of roads. Compared with the city side, Cd, Cu, Pb, Ni, and Zn contamination were heavier along the ring road, the city centre, and the freeway with high traffic density. Low Pb contamination or no contamination in all the road dust samples may be related to the increasing usage of lead-free petrol

Heavy metal induced ecological risk in the city of Urumqi, NW China

A total of 169 samples of road dust collected in the city of Urumqi, capital of the Xinjiang Uygur Autonomous Region in northwest China, were analyzed by method of inductively coupled plasma-mass spectrometry for 10 elements (i.e., Cd, Cr, Cu, Ni, Pb, Mn, Be, Co, Zn, and U). The possible sources of metals are identified with multivariate analysis such as correlation analysis, principal component analysis, and cluster analysis. Besides, enrichment factors are used to quantitatively evaluate the influences of human activities on heavy metal concentrations. Moreover, the potential ecological risk index is applied to evaluating the ecological risk of heavy metal pollutants. The results indicate that: (1) the concentrations of the heavy metals involved were much higher in urban areas than the background values, except those of Co and U. Mn, U, and Co are mainly of natural origin; Cu, Pb, Zn, and Cr are mainly of traffic sources and are partly of industrial sources; Ni and Be are mainly the results of industrial activities, such as machine shops, firepower plants, tire and rubber factories, cement factories, and textile mills and are partly of the traffic sources; (2) with high "toxic-response" factor and high concentration, Cd has more serious influences on the environment than other heavy metals. Therefore, commercial and industrial areas are usually characterized by higher potential ecological risk when compared with residential areas and new developing urban areas. The results of this study could be helpful for the management of environment in industrial areas

Spatial distribution and contamination assessment of heavy metals in urban road dusts from Urumqi, NW China

This study reports the spatial distribution pattern and degree of heavy metal pollution (Cd, Cr, Cu, Ni, Pb, Mn, Be, Co, Zn and U) in 169 urban road dust samples from urban area of Urumqi city. The spatial distribution pattern shows that Cu, Pb, Cr and Zn have similar patterns of spatial distribution. Their hot-spot areas were mainly associated with main roads where high traffic density was identified. Ni and Mn show similar spatial distributions coinciding with the industrial areas, while the spatial distribution patterns of Co and U show hot-spot areas were mainly located in the sides of the urban area where the road dust was significantly influenced by natural soils. The spatial distributions of Be and Cd were very different from other metals. The geo-accumulation index suggests that road dust in Urumqi city was uncontaminated to moderately contaminated with Cd, Cu, Ni, Pb, Mn, Be, Zn and U. The integrated pollution index shows IPIs of all road dust samples were higher than 1, suggesting that the road dust quality of Urumqi city has clearly been polluted by anthropogenic emission of heavy metals. Moreover, the spatial distribution pattern of IPIs also shows several distribution trends in the studied region. (C) 2009 Elsevier B.V. All rights reserved

Observed trends of heating and cooling degree-days in Xinjiang Province, China

Global warming has the potential to impact various aspects of human society such as agriculture, construction, transportation, water resources management, power generation, and phenology. The impact on energy, especially energy consumption for heating and cooling of buildings, is very important. These influences are different in terms of space and time due to spatial and temporal variations of temperature. In this study, daily data of minimum and maximum temperature of 51 stations for 1959-2004 were used to detect annual and seasonal variations of heating and cooling degree-days in Xinjiang, China, by using the Mann-Kendall trend test and linear regression techniques. The results indicate that: (1) taking 18A degrees C as the base temperature, annual mean heating degree-days (HDD) ranged between 2,700 and 7,973A degrees C, and annual mean cooling degree-days (CDD) (the base temperature is 24A degrees C) ranged between 0.4 and 792A degrees C. CDDs are relatively low in Xinjiang; (2) autumn, winter, and annual HDDs show significant decreasing trends. Annual CDD at 23 out of 51 stations present significant increasing trends, while no remarkable positive trends can be observed at the other stations; and (3) with respect to spatial variations, Xinjiang was characterized by significant decreasing annual, winter, and autumn HDDs, and it was particularly true for the northern Xinjiang. The annual and summer CDDs in the western parts of northern Xinjiang (the edges of the Tarim Basin and the Turpan-Hami Basin) were characterized by significant increasing trends. However, no fixed spatial patterns can be identified in the variations of annual and summer CDDs. The results of this study could be useful for energy management in Xinjiang and are also helpful for better understanding of impacts of global warming on energy consumption in other countries of the world

Adaptive growth of Tamarix taklamakanensis root systems in response to wind action

Root distribution and characteristics were investigated on a 70-year-old Tamarix taklamakanensis individual through uprooting. Rooting depth was restricted by water table, and root morphology adapted to resist the wind movement associated with shallow rooting. Root systems had more structural root mass and length on the leeward side than the windward side of the tree relative to the prevailing wind direction. Additional resistance to wind bending can occur as a result of increased thickening of the lower stem along the axis of the prevailing wind direction, and in T taklamakanensis, this thickening is greater on the lee side of the stem. We conclude that increased root distribution and thickening of the lower stem on the leeward are an important strategy for T taklamakanensis in response to wind action in the hinterland of Taklimakan Desert

The variation of morphological features and mineralogical components of biological soil crusts in the Gurbantunggut Desert of Northwestern China

Increasingly complex life forms were found in older biological soil crusts in the Gurbantaunggut Desert in Northwestern China. These crusts may play a critical role in mineral erosion and desert soil formation by modifying the weathering environment and ultimately affecting mineralogical variance. To test this hypothesis, variations in the morphological features and mineralogical components of successional biological soil crusts at 1 cm were studied by optical microscopy, SEM and grain size analysis. Concentrations of erosion-resistant minerals decreased with crust succession, while minerals susceptible to weathering increased with crust development. Neogenetic minerals were found in late stage crusts, but not in early stage crusts. Silt and clay concentrations were highest in early formation crusts and soil mean particle size decreased with crust succession. Cyanobacteria, lichen and moss were shown to erode and etch rocks, and secondary minerals produced by weathering were localized with the living organisms. Thus, more developed crusts appeared to contribute to greater mineral weathering and may be a major cause of mineralogical variance seen in the Gurbantunggut Desert. The greater activity and complexity of older crusts, as well as their improved moisture condition may function to accelerate mineral weathering. Therefore, protection and recovery of biological crusts is vital for desert soil formation