Research Status of Water Quality Criteria and Standards and Analysis on the Transformation Methods

Under the vision of development for the new era,China has entered a stage of high-quality economic development and an important window period in which we have the conditions and ability to address the prominent issue of economic development and ecological protection in a coordinated way.However,all kinds of environmental benchmark values in China are lacking and need to be constantly supplemented and improved.Therefore,exploring and putting forward a simple and efficient method for the transformation of environmental criteria into environmental standards is an important basis for the rapid establishment of relevant environmental criteria system and the effective promotion of the development of environmental standards system towards a scientific and reasonable direction.In this paper,the water environment is taken as the research object.By analyzing the research progress of environmental criteria and standards at home and abroad,and the foreign method of transforming environmental criteria into environmental standards,combined with the problems faced in the process of transforming environmental criteria into environmental standards in China,an effective method to transform China's environmental criteria into environmental standards is analyzed.After analysis and comparison,it is found that the pollution reduction accounting method could achieve their simple and efficient conversion.Under the premise of obtaining environmental criteria for certain pollutants,environmental criteria for certain pollutants could be obtained by distributing pollutants reduction costs,and accounting economic benefits after reaching standard,thus obtaining the environmental standard of this type of pollutant,which provides reference to determine the environmental standard limits of such pollutants.

A survey: which features are required for dynamic visual simultaneous localization and mapping?

In recent years,simultaneous localization and mapping in dynamic environments(dynamic SLAM)has attracted significant attention from both academia and industry.Some pioneering work on this technique has expanded the potential of robotic applications.Compared to standard SLAM under the static world assumption,dynamic SLAM divides features into static and dynamic categories and leverages each type of feature properly.Therefore,dynamic SLAM can provide more robust localization for intelligent robots that operate in complex dynamic environments.Additionally,to meet the demands of some high-level tasks,dynamic SLAM can be integrated with multiple object tracking.This article presents a survey on dynamic SLAM from the perspective of feature choices.A discussion of the advantages and disadvantages of different visual features is provided in this article.

Assessment of the Spatial and Temporal Water Eutrophication for Lake Baiyangdian Based on Integrated Fuzzy Method

Water quality evaluation entails both randomness and fuzziness. Considering that water eutrophication evaluation involves many indices, different classifications and interval values, fuzzy variable sets theory was developed to Lake Baiyangdian as a study case. Taking reference to eutrophication standard of Chinese lakes and local characteristic of Lake Baiyangdian, eutrophication degree of lake was divided into 8 levels. Total phosphorus, total nitrogen, and CODMn were selected as evaluation indices in this research. Based on the measured data, index feature value matrix of sample was built. Index weights were determined by means of pure threshold value method. Relative membership degree of each index to each classification was calculated with relative difference function model. Then the stability of feature value of classification corresponding was received by the comprehensive calculation with the relative membership degree and index weights. The results show that the proposed models are effective tools for generating a set of realistic and flexible optimal solutions for complicated water quality evaluation issues. It concluded that the model was reasonable and practical.

Image-based camera localization: an overview

Virtual reality,augmented reality,robotics,and autonomous driving,have recently attracted much attention from both academic and industrial communities,in which image-based camera localization is a key task.However,there has not been a complete review on image-based camera localization.It is urgent to map this topic to enable individuals enter the field quickly.In this paper,an overview of image-based camera localization is presented.A new and complete classification of image-based camera localization approaches is provided and the related techniques are introduced.Trends for future development are also discussed.This will be useful not only to researchers,but also to engineers and other individuals interested in this field.

Real-time human segmentation by BowtieNet and a SLAM-based human AR system

Background Generally, it is difficult to obtain accurate pose and depth for a non-rigid moving object from a single RGB camera to create augmented reality (AR). In this study, we build an augmented reality system from a single RGB camera for a non-rigid moving human by accurately computing pose and depth, for which two key tasks are segmentation and monocular Simultaneous Localization and Mapping (SLAM). Most existing monocular SLAM systems are designed for static scenes, while in this AR system, the human body is always moving and non-rigid. Methods In order to make the SLAM system suitable for a moving human, we first segment the rigid part of the human in each frame. A segmented moving body part can be regarded as a static object, and the relative motions between each moving body part and the camera can be considered the motion of the camera. Typical SLAM systems designed for static scenes can then be applied. In the segmentation step of this AR system, we first employ the proposed BowtieNet, which adds the atrous spatial pyramid pooling (ASPP) of DeepLab between the encoder and decoder of SegNet to segment the human in the original frame, and then we use color information to extract the face from the segmented human area. Results Based on the human segmentation results and a monocular SLAM, this system can change the video background and add a virtual object to humans. Conclusions The experiments on the human image segmentation datasets show that BowtieNet obtains state-of-the-art human image segmentation performance and enough speed for real-time segmentation. The experiments on videos show that the proposed AR system can robustly add a virtual object to humans and can accurately change the video background.

Commutators of Littlewood-Paley Operators on Herz Spaces with Variable Exponent

Let Ω ∈ L^2（S^n-1） be homogeneous function of degree zero and b be BMO functions. In this paper, we obtain some boundedness of the Littlewood-Paley Opera- tors and their higher-order commutators on Herz spaces with variable exponent.

High-quality indoor scene 3D reconstruction with RGB-D cameras:A brief review

High-quality 3D reconstruction is an important topic in computer graphics and computer vision with many applications,such as robotics and augmented reality.The advent of consumer RGB-D cameras has made a profound advance in indoor scene reconstruction.For the past few years,researchers have spent significant effort to develop algorithms to capture 3D models with RGB-D cameras.As depth images produced by consumer RGB-D cameras are noisy and incomplete when surfaces are shiny,bright,transparent,or far from the camera,obtaining highquality 3D scene models is still a challenge for existing systems.We here review high-quality 3D indoor scene reconstruction methods using consumer RGB-D cameras.In this paper,we make comparisons and analyses from the following aspects:(i)depth processing methods in 3D reconstruction are reviewed in terms of enhancement and completion,(ii)ICP-based,feature-based,and hybrid methods of camera pose estimation methods are reviewed,and(iii)surface reconstruction methods are reviewed in terms of surface fusion,optimization,and completion.The performance of state-of-the-art methods is also compared and analyzed.This survey will be useful for researchers who want to follow best practices in designing new high-quality 3D reconstruction methods.

Transport of a volatile contaminant in a free-surface wetland flow

Presented in this paper is an analytical study of a pulsed volatile contaminant emission into a free-surface wetland flow. A simplified model is given for contaminant transport under the combined action of advection, mass dispersion, apparent reaction, and volatilization at the free water surface. The effect of periodic apparent reaction on contaminant transport is separated from the hydraulic effect via an extended transformation, with a limiting case covering the known transformation for constant apparent reaction rate. The analytical solutions of zeroth and first order concentration moments are rigorously derived and illustrated. It was found that the amount of contaminant decreases from the bottom bed to the free-surface under volatilization, and the total amount of contaminant decays with time. It was also found that the moving speed of the mass center of the whole contaminant cloud increases, as the ratio of volatilization coefficient to vertical effective mass dispersivity increases.