Unsupervised Deraining: Where Contrastive Learning Meets Self-similarity

Image deraining is a typical low-level image restoration task, which aims at decomposing the rainy image into two distinguishable layers: the clean image layer and the rain layer. Most of the existing learning-based deraining methods are supervisedly trained on synthetic rainy-clean pairs. The domain gap between the synthetic and real rains makes them less generalized to different real rainy scenes. Moreover, the existing methods mainly utilize the property of the two layers independently, while few of them have considered the mutually exclusive relationship between the two layers. In this work, we propose a novel non-local contrastive learning (NLCL) method for unsupervised image deraining. Consequently, we not only utilize the intrinsic self-similarity property within samples but also the mutually exclusive property between the two layers, so as to better differ the rain layer from the clean image. Specifically, the non-local self-similarity image layer patches as the positives are pulled together and similar rain layer patches as the negatives are pushed away. Thus the similar positive/negative samples that are close in the original space benefit us to enrich more discriminative representation. Apart from the self-similarity sampling strategy, we analyze how to choose an appropriate feature encoder in NLCL. Extensive experiments on different real rainy datasets demonstrate that the proposed method obtains state-of-the-art performance in real deraining.Comment: 10 pages, 10 figures, accept to 2022CVP

Unsupervised Deraining: Where Asymmetric Contrastive Learning Meets Self-similarity

Most of the existing learning-based deraining methods are supervisedly trained on synthetic rainy-clean pairs. The domain gap between the synthetic and real rain makes them less generalized to complex real rainy scenes. Moreover, the existing methods mainly utilize the property of the image or rain layers independently, while few of them have considered their mutually exclusive relationship. To solve above dilemma, we explore the intrinsic intra-similarity within each layer and inter-exclusiveness between two layers and propose an unsupervised non-local contrastive learning (NLCL) deraining method. The non-local self-similarity image patches as the positives are tightly pulled together, rain patches as the negatives are remarkably pushed away, and vice versa. On one hand, the intrinsic self-similarity knowledge within positive/negative samples of each layer benefits us to discover more compact representation; on the other hand, the mutually exclusive property between the two layers enriches the discriminative decomposition. Thus, the internal self-similarity within each layer (similarity) and the external exclusive relationship of the two layers (dissimilarity) serving as a generic image prior jointly facilitate us to unsupervisedly differentiate the rain from clean image. We further discover that the intrinsic dimension of the non-local image patches is generally higher than that of the rain patches. This motivates us to design an asymmetric contrastive loss to precisely model the compactness discrepancy of the two layers for better discriminative decomposition. In addition, considering that the existing real rain datasets are of low quality, either small scale or downloaded from the internet, we collect a real large-scale dataset under various rainy kinds of weather that contains high-resolution rainy images.Comment: 16 pages, 15 figures. arXiv admin note: substantial text overlap with arXiv:2203.1150

Experimental research on the performance of BIPV/T system with water-cooled wall

Solar photovoltaic/thermal building integrated power/heat technology (BIPV/T) can provide both electricity and heat to buildings, which is important for improving the efficiency of solar energy utilization and reducing building energy consumption. In this paper, a BIPV/T system with water-cooled wall is proposed. The water-cooled wall heat exchanger is not in direct contact with the PV module, and uses air to dissipate heat from the PV module, which in turn heats domestic water, and can provide hot water or hot air to the building as needed. This paper experimentally investigates the system’s ability to produce domestic hot water and power generation performance, with an average power generation efficiency of 12.6% for the whole day and providing 35 °C domestic hot water for more than 7 h. The results of this paper have some guiding significance for the efficient operation of BIPV/T

Assessing the Impact of the Strictest Water Resources Management Policy on Water Use Efficiency in China

The strictest water resources management policy plays a critical role in response to the challenge of water shortage, water security, and sustainable water development in China. Despite the varied analyses of the strictest water resources management policy, the relations between the strictest water resources management policy and water use efficiency remain under-researched. This study uses an interval event-analysis method to assess the strictest water resources management policy’s impact on water use efficiency in China based on data from 2007 to 2020. In addition, the study breaks down water use efficiency into eight indicators and divides the strictest water management policy into “pre-, middle, and post-” phases. The research results show the strictest water resources management policy has a significant positive effect on water use efficiency. Further research shows the total water consumption control system and water efficiency control system have the most significant effect. The strictest water resources management policy has a lasting impact on water use efficiency. This study contributes to the global knowledge body of water governance and provides a reference value for water policy decision-making and optimization in other countries

Water Policy Evaluation Based on the Multi-Source Data-Driven Text Mining: A Case Study of the Strictest Water Resource Management Policy in China

The strictest water resources management (SWRM) policy is a critical policy to address China’s severe water shortage and pollution problems, and aims to promote sustainable water development and water governance. Based on data mining from multiple sources, including policy text from the strictest water resource management policy from 2011 to 2021, the reports of major media websites, and the Baidu Index, this study used the ROST-CM6 text-analysis tool to analyze the policy content, public opinion, and public perception of the strictest water resources management policy quantitatively and visually. The results found that the policy text and public-opinion are given high attention to the water resources assessment, water control management, and water resources protection, but the policy text focuses on the macro level, and pays more attention to national development and long-term planning. The public opinion belongs to the micro level and is more economic, and there is a certain degree of media bias. With notable regional disparities, the general public’s opinion of the harshest water resource management policy has been rising every year. This research adds to the global body of knowledge on water governance, and serves as a guide for Chinese and other governments looking to improve their water resource management strategies

Water Policy Evaluation Based on the Multi-Source Data-Driven Text Mining: A Case Study of the Strictest Water Resource Management Policy in China

The strictest water resources management (SWRM) policy is a critical policy to address China’s severe water shortage and pollution problems, and aims to promote sustainable water development and water governance. Based on data mining from multiple sources, including policy text from the strictest water resource management policy from 2011 to 2021, the reports of major media websites, and the Baidu Index, this study used the ROST-CM6 text-analysis tool to analyze the policy content, public opinion, and public perception of the strictest water resources management policy quantitatively and visually. The results found that the policy text and public-opinion are given high attention to the water resources assessment, water control management, and water resources protection, but the policy text focuses on the macro level, and pays more attention to national development and long-term planning. The public opinion belongs to the micro level and is more economic, and there is a certain degree of media bias. With notable regional disparities, the general public’s opinion of the harshest water resource management policy has been rising every year. This research adds to the global body of knowledge on water governance, and serves as a guide for Chinese and other governments looking to improve their water resource management strategies

Self-Oscillating Curling of a Liquid Crystal Elastomer Beam under Steady Light

Self-oscillation absorbs energy from a steady environment to maintain its own continuous motion, eliminating the need to carry a power supply and controller, which will make the system more lightweight and promising for applications in energy harvesting, soft robotics, and microdevices. In this paper, we present a self-oscillating curling liquid crystal elastomer (LCE) beam-mass system, which is placed on a table and can self-oscillate under steady light. Unlike other self-sustaining systems, the contact surface of the LCE beam with the tabletop exhibits a continuous change in size during self-sustaining curling, resulting in a dynamic boundary problem. Based on the dynamic LCE model, we establish a nonlinear dynamic model of the self-oscillating curling LCE beam considering the dynamic boundary conditions, and numerically calculate its dynamic behavior using the Runge-Kutta method. The existence of two motion patterns in the LCE beam-mass system under steady light are proven by numerical calculation, namely self-curling pattern and stationary pattern. When the energy input to the system exceeds the energy dissipated by air damping, the LCE beam undergoes self-oscillating curling. Furthermore, we investigate the effects of different dimensionless parameters on the critical conditions, the amplitude and the period of the self-curling of LCE beam. Results demonstrate that the light source height, curvature coefficient, light intensity, elastic modulus, damping factor, and gravitational acceleration can modulate the self-curling amplitude and period. The self-curling LCE beam system proposed in this study can be applied to autonomous robots, energy harvesters, and micro-instruments

Biomechanical comparison of different stabilization constructs for unstable posterior wall fractures of acetabulum. A cadaveric study.

PURPOSE: Operative treatment of unstable posterior wall fractures of acetabulum has been widely recommended. This laboratory study was undertaken to evaluate static fixation strength of three common fixation constructs: interfragmentary screws alone, in combination with conventional reconstruction plate, or locking reconstruction plate. METHODS: Six formalin-preserved cadaveric pelvises were used for this investigation. A posterior wall fracture was created along an arc of 40-90 degree about the acetabular rim. Three groups of different fixation constructs (two interfragmentary screws alone; two interfragmentary screws and a conventional reconstruction plate; two interfragmentary screws and a locking reconstruction) were compared. Pelvises were axial loaded with six cycles of 1500 N. Dislocation of superior and inferior fracture site was analysed with a multidirectional ultrasonic measuring system. RESULTS: No statistically significant difference was found at each of the superior and inferior fracture sites between the three types of fixation. In each group, the vector dislocation at superior fracture site was significantly larger than inferior one. CONCLUSIONS: All those three described fixation constructs can provide sufficient stability for posterior acetabular fractures and allow early mobilization under experimental conditions. Higher posterior acetabular fracture line, transecting the weight-bearing surface, may indicate a substantial increase in instability, and need more stable pattern of fixation