Dissecting Arbitrary-scale Super-resolution Capability from Pre-trained Diffusion Generative Models

Diffusion-based Generative Models (DGMs) have achieved unparalleled performance in synthesizing high-quality visual content, opening up the opportunity to improve image super-resolution (SR) tasks. Recent solutions for these tasks often train architecture-specific DGMs from scratch, or require iterative fine-tuning and distillation on pre-trained DGMs, both of which take considerable time and hardware investments. More seriously, since the DGMs are established with a discrete pre-defined upsampling scale, they cannot well match the emerging requirements of arbitrary-scale super-resolution (ASSR), where a unified model adapts to arbitrary upsampling scales, instead of preparing a series of distinct models for each case. These limitations beg an intriguing question: can we identify the ASSR capability of existing pre-trained DGMs without the need for distillation or fine-tuning? In this paper, we take a step towards resolving this matter by proposing Diff-SR, a first ASSR attempt based solely on pre-trained DGMs, without additional training efforts. It is motivated by an exciting finding that a simple methodology, which first injects a specific amount of noise into the low-resolution images before invoking a DGM's backward diffusion process, outperforms current leading solutions. The key insight is determining a suitable amount of noise to inject, i.e., small amounts lead to poor low-level fidelity, while over-large amounts degrade the high-level signature. Through a finely-grained theoretical analysis, we propose the Perceptual Recoverable Field (PRF), a metric that achieves the optimal trade-off between these two factors. Extensive experiments verify the effectiveness, flexibility, and adaptability of Diff-SR, demonstrating superior performance to state-of-the-art solutions under diverse ASSR environments

A new species of the odorous frog genus Odorrana (Amphibia, Anura, Ranidae) from southwestern China

The genus Odorrana is widely distributed in the mountains of East and Southeastern Asia. An increasing number of new species in the genus have been recognized especially in the last decade. Phylogenetic studies of the O. schmackeri species complex with wide distributional range also revealed several cryptic species. Here, we describe a new species in the species complex from Guizhou Province of China. Phylogenetic analyses based on mitochondrial DNA indicated the new species as a monophyly clustered into the Odorrana clade and sister to O. schmackeri, and nuclear DNA also indicated it as an independent lineage separated from its related species. Morphologically, the new species can be distinguished from its congeners based on a combination of the following characters: (1) having smaller body size in males (snout-vent length (SVL) <43.3 mm); (2) head longer than wide; (3) dorsolateral folds absent; (4) tympanum of males large and distinct, tympanum diameter twice as long as width of distal phalanx of finger III; (5) two metacarpal tubercles; (6) relative finger lengths: II < I < IV < III; (7) tibiotarsal articulation reaching to the level between eye to nostril when leg stretched forward; (8) disks on digits with circum-marginal grooves; (9) toes fully webbed to disks; (10) the first subarticular tubercle on fingers weak; (11) having white pectoral spinules, paired subgular vocal sacs located at corners of throat, light yellow nuptial pad on the first finger in males

Effectiveness of Using Polymer Bumpers to Mitigate Earthquake-Induced Pounding between Buildings of Unequal Heights

Collisions often happen between adjacent buildings without a sufficient gap under seismic loadings. Installing polymer bumpers may decrease the pounding forces between colliding buildings. This paper focuses on the analysis of suppressing pounding effects by using of polymer bumpers. In order to investigate pounding mitigation effectiveness in the condition with and without bumpers, different types of pounding force models are utilized to simulate and calculate frame vibration responses under seismic loads. Firstly, time-history results for pounding force, displacements, and shearing forces in selected floors are calculated in the condition with and without polymer bumpers. Secondly, differences between viscoelastic and elastic pounding force models are compared and discussed. And finally, parametric studies are carried out to investigate influences of different pounding parameters. The results show that polymer bumpers can reduce maximum values of pounding force but increase pounding times. And viscoelasticity of bumper materials has a certain range of influences on pounding force responses. Choosing improper material types and pounding parameters may lead to opposite effects

Effectiveness of Using Polymer Bumpers to Mitigate Earthquake-Induced Pounding between Buildings of Unequal Heights

Collisions often happen between adjacent buildings without a sufficient gap under seismic loadings. Installing polymer bumpers may decrease the pounding forces between colliding buildings. This paper focuses on the analysis of suppressing pounding effects by using of polymer bumpers. In order to investigate pounding mitigation effectiveness in the condition with and without bumpers, different types of pounding force models are utilized to simulate and calculate frame vibration responses under seismic loads. Firstly, time-history results for pounding force, displacements, and shearing forces in selected floors are calculated in the condition with and without polymer bumpers. Secondly, differences between viscoelastic and elastic pounding force models are compared and discussed. And finally, parametric studies are carried out to investigate influences of different pounding parameters. The results show that polymer bumpers can reduce maximum values of pounding force but increase pounding times. And viscoelasticity of bumper materials has a certain range of influences on pounding force responses. Choosing improper material types and pounding parameters may lead to opposite effects

Characteristics and Causes of Long-Term Water Quality Variation in Lixiahe Abdominal Area, China

The Lixiahe abdominal area is a representative plain river network in the lower reaches of the Huai River, being an upstream section of south-to-north water diversion from the Yangtze River in Jiangsu Province, China. The assessment of long-term water quality variation and the identification of probable causes can provide references for sustainable water resources management. Based on the monthly water quality data of 15 monitoring stations in the Lixiahe abdominal area, the periodic characteristics and tendency of water quality variation were studied by combining wavelet analysis, the Mann&ndash;Kendall trend test, and Sen&rsquo;s slope estimator, and the correlation between water quality variation, water level, and water diversion was discussed with cross wavelet transform and wavelet coherence. The results show that the comprehensive water quality index (CWQI) included periodic fluctuations on multiple scales from 0.25 to 5 years. The CWQI of 7 out of 15 monitoring stations has a significant decreasing trend, indicating regional water quality improvement. The trend slope ranges from &minus;0.071/yr to 0.007/yr, where &minus;0.071/yr indicates the water quality improvement by one grade in 15 years. The spatial variation of water quality in the Lixiahe abdominal area was significant. The water quality of the main water diversion channels and its nearby rivers was significantly improved, while the improvement of other areas was not significant or even became worse due to the increasing discharge of pollutants. The CWQI of the main water diversion channels and its nearby rivers was inversely correlated with the amount of water diversion. The greater the amount of water diversion, the better the water quality. The water diversion from the Yangtze River has played an important role in improving the regional water environment

Simulation of antisolvent crystallization in impinging jets with coupled multiphase flow-micromixing-PBE

The KT (Kurganov and Tadmor, 2000) finite-volume central scheme is one of the most promising high resolution numerical methods to solve the widely-used population balance equation (PBE) in crystallization and other areas. To meet the practical purpose of geometric-type particle size grid, the primary KT scheme was extended to a general form and validated for pure growth in homogeneous systems. Based on the extended KT scheme, a solver was developed that couples the general discretized PBE and ami-cromixing and a CFD mixture model in OpenFOAM (open-source field operation and manipulation). The simulation uses published parameters from and is compared to experimental antisolvent crystallization of lovastatin from a methanol-water mixture in an impinging jet. The effect of the existing solid crystals on some crystal properties is investigated in this work for the first time. The shapes of crystal size distribution (CSD) at various jet velocities are consistent with experimental observations. The geometric particle size partition is shown to be capable of improving the accuracy of simulation in divisions of the highest particle number densities or steep gradients in the number density. The existing solid crystals are also shown to have a non-negligible effect on the slurry flow crystallization systems once the mean crystal size reaches 20 mu m. (C) 2017 Elsevier Ltd. All rights reserved.</p

Variations of Drought Tendency, Frequency, and Characteristics and Their Responses to Climate Change under CMIP5 RCP Scenarios in Huai River Basin, China

Huai River Basin (HRB) is an important food and industrial production area and a frequently drought-affected basin in eastern China. It is necessary to consider the future drought development for reducing the impact of drought disasters. Three global circulation models (GCMs) from Coupled Model Intercomparison Project phase 5 (CMIP5), such as CNRM-CM5 (CNR), HadGEM2-ES (Had) and MIROC5 (MIR), were used to assessment the future drought conditions under two Representative Concentration Pathways (RCPs) scenarios, namely, RCP4.5 and RCP8.5. The standardized precipitation evapotranspiration index (SPEI), statistical method, Mann-Kendall test, and run theory were carried out to study the variations of drought tendency, frequency, and characteristics and their responses to climate change. The research showed that the three CMIP5 models differ in describing the future seasonal and annual variations of precipitation and temperature in the basin and thus lead to the differences in describing drought trends, frequency, and drought characteristics, such as drought severity, drought duration, and drought intensity. However, the drought trend, frequency, and characteristics in the future are more serious than the history. The drought frequency and characteristics tend to be strengthened under the scenario of high concentration of RCP8.5, and the drought trend is larger than that of low concentration of RCP4.5. The lower precipitation and the higher temperature are the main factors affecting the occurrence of drought. All three CMIP5 models show that precipitation would increase in the future, but it could not offset the evapotranspiration loss caused by significant temperature rise. The serious risk of drought in the future is still higher. Considering the uncertainty of climate models for simulation and prediction, attention should be paid to distinguish the effects of different models in the future drought assessment

Drought Trends and the Extreme Drought Frequency and Characteristics under Climate Change Based on SPI and HI in the Upper and Middle Reaches of the Huai River Basin, China

The Huai River Basin (HRB) is an important grain and industrial production area in eastern China with frequent droughts. Under the background of current climate change, the hydrological and meteorological characteristics of the basin may be changed, which may lead to the changes of regional drought characteristics. It should be paid more attention on the drought research under climate change and the difference between different drought indices. Coupled Model Intercomparison Project phase 5 (CMIP5) as an important tool for climate change research has been used in the study and the study chosen three global circulation models (GCMs)&mdash;such as CNRM-CM5 (CNR), HadGEM2-ES (Had), and MIROC5 (MIR)&mdash;to gather an ensemble model (EnM) for providing the future climate information. The Standardized Precipitation Index (SPI) and Humidity Index (HI) were used to evaluate and compare the drought situations in the past and the future periods with two representative concentration path scenarios (RCP4.5 &amp; RCP8.5). Some sequence statistics methods, such as Mann&ndash;Kendall test and run theory, were carried out to analyze the trend and the changes of extreme drought frequency and characteristics values. The research showed that the simulation accuracy of the EnM would better. SPI and HI take different factors into count and thus lead to differences in describing drought trend, extreme drought frequency, and characteristic values, such as drought severity, drought duration, mean drought severity, and max drought intensity. The research showed that both SPI and HI showed the same wetting or drying trend in the same timescales (except winter) as in the historical data. However, the future annual and seasonal drought trend reflected by SPI shows a wetting trend while HI shows a drying trend. Both in the past and the future, extreme drought frequency and characteristic values reflected by HI are higher than SPI. The drought trend is greater, and the extreme drought frequency and characteristics tend to be strengthened under RCP8.5. Low precipitation and high potential evapotranspiration (PET), especially the PET caused by temperature rise, are the main influencing factors of drought in the future. Therefore, the influence of the PET should not be ignored in drought analysis and we should strengthen the comparative study of different drought indices in future drought analysis under climate change