Laboratory experiments on cohesive soil bed fluidization by water waves

Part I. Relationships between the rate of bed fluidization and the rate of wave energy dissipation, by Jingzhi Feng and Ashish J. Mehta and Part II. In-situ rheometry for determining the dynamic response of bed, by David J.A. Williams and P. Rhodri Williams. A series of preliminary laboratory flume experiments were carried out to examine the time-dependent behavior of a cohesive soil bed subjected to progressive, monochromatic waves. The bed was an aqueous, 50/50 (by weight) mixture of a kaolinite and an attapulgite placed in a plexiglass trench. The nominal bed thickness was 16 cm with density ranging from 1170 to 1380 kg/m 3, and water above was 16 to 20 cm deep. Waves of design height ranging from 2 to 8 cm and a nominal frequency of 1 Hz were run for durations up to 2970 min. Part I of this report describes experiments meant to examine the rate at which the bed became fluidized, and its relation to the rate of wave energy dissipation. Part II gives results on in-situ rheometry used to track the associated changes in bed rigidity. Temporal and spatial changes of the effective stress were measured during the course of wave action, and from these changes the bed fluidization rate was calculated. A wave-mud interaction model developed in a companion study was employed to calculate the rate of wave energy dissipation. The dependence of the rate of fluidization on the rate of energy dissipation was then explored. Fluidization, which seemingly proceeded down from the bed surface, occurred as a result of the loss of structural integrity of the soil matrix through a buildup of the excess pore pressure and the associated loss of effective stress. The rate of fluidization was typically greater at the beginning of wave action and apparently approached zero with time. This trend coincided with the approach of the rate of energy dissipation to a constant value. In general it was also observed that, for a given wave frequency, the larger the wave height the faster the rate of fluidization and thicker the fluid mud layer formed. On the other hand, increasing the time of bed consolidation prior to wave action decreased the fluidization rate due to greater bed rigidity. Upon cessation of wave action structural recovery followed. Dynamic rigidity was measured by specially designed, in situ shearometers placed in the bed at appropriate elevations to determine the time-dependence of the storage and loss moduli, G' and G", of the viscoelastic clay mixture under 1 Hz waves. As the inter-particle bonds of the space-filling, bed material matrix weakened, the shear propagation velocity decreased measurably. Consequently, G' decreased and G" increased as a transition from dynamically more elastic to more viscous response occurred. These preliminary experiments have demonstrated the validity of the particular rheometric technique used, and the critical need for synchronous, in-situ measurements of pore pressures and moduli characterizing bed rheology in studies on mud fluidization. This study was supported by WES contract DACW39-90-K-0010. (This document contains 151 pages.

Spectrophotometric determinationof trace nitrite with a novel self-coupling diazotizing reagent: J-acid

A simple and sensitive method for the spectrophotometric determination of nitrite was described and optimum reaction conditions along with other important analytical parameters were established. In the presence of potassium bromide at 25°C, nitrite reacted with J-acid in hydrochloric acid producing diazonium salt and then coupled with excess J-acid in the sodium carbonate solution yielding red colored azo compounds. At wavelength of 500 nm, Beer’s law was obeyed over the concentration range of 0,02 – 0,60 mg∙L⁻¹. The molar absorptivity was 3,92∙10⁴ L∙mol⁻¹∙cm⁻¹. This method was easily applied to the determination of trace nitrite in environmental water with recoveries of 9₈,7 – 101,2%

Secular trend of the leading causes of death in China from 2003 to 2013

Background: To analyze the epidemiological characteristics and secular trends of the leading causes of death in China.Methods: Data on the leading causes of death was collected from the Statistical Yearbook of China. Data for 11 years, from 2003 to 2013, was analyzed by regression analysis and chi-square test.Results: The top 3 causes of death from 2009 to 2013 were cancer, cerebrovascular disease, and cardiopathy, with the role of cardiopathy increasing over time (P<0.01). The proportion of deaths related to cardio-cerebrovascular diseases in urban and rural areas increased to 41.9% and 44.8%, respectively, in 2013, and was significantly higher than that for cancer, 25.5% and 22.4% (both P<0.01). Injury and poisoning in urban or rural areas represented the fifth leading cause of death. In 2006, endocrine, nutritional, and metabolic diseases were the sixth main cause of death, with 3.3% in urban areas. The role of genito-urinary,respiratory, and digestive system diseases in urban areas and genito-urinary system diseases in rural areas decreased during this period (all P<0.05).Conclusion: Cancer, cerebrovascular disease, and cardiopathy accounted for more than 67% of all deaths from 2007 to 2013 in China, and significantly increased in proportion from 2003 to 2013.Keywords: Causes of death; China; cancer; cardiovascular diseas

Secular trend of the leading causes of death in China from 2003 to 2013.

Background: To analyze the epidemiological characteristics and secular trends of the leading causes of death in China. Methods: Data on the leading causes of death was collected from the Statistical Yearbook of China. Data for 11 years, from 2003 to 2013, was analyzed by regression analysis and chi-square test. Results: The top 3 causes of death from 2009 to 2013 were cancer, cerebrovascular disease, and cardiopathy, with the role of cardiopathy increasing over time (P<0.01). The proportion of deaths related to cardio-cerebrovascular diseases in urban and rural areas increased to 41.9% and 44.8%, respectively, in 2013, and was significantly higher than that for cancer, 25.5% and 22.4% (both P<0.01). Injury and poisoning in urban or rural areas represented the fifth leading cause of death. In 2006, endocrine, nutritional, and metabolic diseases were the sixth main cause of death, with 3.3% in urban areas. The role of genito-urinary, respiratory, and digestive system diseases in urban areas and genito-urinary system diseases in rural areas decreased during this period (all P<0.05). Conclusion: Cancer, cerebrovascular disease, and cardiopathy accounted for more than 67% of all deaths from 2007 to 2013 in China, and significantly increased in proportion from 2003 to 2013

ZnCuInS/ZnSe/ZnS Quantum Dot-Based Downconversion Light-Emitting Diodes and Their Thermal Effect

The quantum dot-based light-emitting diodes (QD-LEDs) were fabricated using blue GaN chips and red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. The power efficiencies were measured as 14.0 lm/W for red, 47.1 lm/W for yellow, and 62.4 lm/W for green LEDs at 2.6 V. The temperature effect of ZnCuInS/ZnSe/ZnS QDs on these LEDs was investigated using CIE chromaticity coordinates, spectral wavelength, full width at half maximum (FWHM), and power efficiency (PE). The thermal quenching induced by the increased surface temperature of the device was confirmed to be one of the important factors to decrease power efficiencies while the CIE chromaticity coordinates changed little due to the low emission temperature coefficients of 0.022, 0.050, and 0.068 nm/°C for red-, yellow-, and green-emitting ZnCuInS/ZnSe/ZnS QDs. These indicate that ZnCuInS/ZnSe/ZnS QDs are more suitable for downconversion LEDs compared to CdSe QDs

Wi-AM: Enabling Cross-Domain Gesture Recognition with Commodity Wi-Fi

RF-based gesture recognition systems outperform computer vision-based systems in terms of user privacy. The integration of Wi-Fi sensing and deep learning has opened new application areas for intelligent multimedia technology. Although promising, existing systems have multiple limitations: (1) they only work well in a fixed domain; (2) when working in a new domain, they require the recollection of a large amount of data. These limitations either lead to a subpar cross-domain performance or require a huge amount of human effort, impeding their widespread adoption in practical scenarios. We propose Wi-AM, a privacy-preserving gesture recognition framework, to address the above limitations. Wi-AM can accurately recognize gestures in a new domain with only one sample. To remove irrelevant disturbances induced by interfering domain factors, we design a multi-domain adversarial scheme to reduce the differences in data distribution between different domains and extract the maximum amount of transferable features related to gestures. Moreover, to quickly adapt to an unseen domain with only a few samples, Wi-AM adopts a meta-learning framework to fine-tune the trained model into a new domain with a one-sample-per-gesture manner while achieving an accurate cross-domain performance. Extensive experiments in a real-world dataset demonstrate that Wi-AM can recognize gestures in an unseen domain with average accuracy of 82.13% and 86.76% for 1 and 3 data samples

A New Steganography Method for Dynamic GIF Images Based on Palette Sort

This paper proposes a new steganography method for hiding data into dynamic GIF (Graphics Interchange Format) images. When using the STC framework, we propose a new algorithm of cost assignment according to the characteristics of dynamic GIF images, including the image palette and the correlation of interframes. We also propose a payload allocation algorithm for different frames. First, we reorder the palette of GIF images to reduce the modifications on pixel values when modifying the index values. As the different modifications on index values would result in different impacts on pixel values, we assign the elements with less impact on pixel values with small embedding costs. Meanwhile, small embedding costs are also assigned for the elements in the regions that the interframe changes are large enough. Finally, we calculate an appropriate payload for each frame using the embedding probability obtained from the proposed distortion function. Experimental results show that the proposed method has a better security performance than state-of-the-art works

Heavy metal contamination in Shanghai agricultural soil

As heavy metals in soil could enrich in biomass and pose health risk to human, it is vital to monitor their contaminations to ensure qualified agricultural production. In this study, we collected >4000 soil samples from agricultural fields in Shanghai during 2010∼2020, and unveiled heavy metal contamination status in this metropolitan. We found that although Shanghai has a long industrialization history, the heavy metal levels in agricultural soil are within safe ranges according to national standard. Specifically, the median levels of Cd, Hg, As, Pb, Cr and Cu are 0.11, 0.13, 7.47, 23.80, 41.00 and 28.30 mg/kg, respectively, which are as good as, or even better than national averages. However, there are spatial and temporal heterogeneities for heavy metal contaminations in Shanghai. For example, the levels of Cd, Hg and Cr are relatively higher in some districts with high industry density, which should be further monitored in the future. Moreover, while the levels for Cd, Cr and Pb have decreased, the level for Hg has mildly increased during this period which needs counteractive measures. Correlation analysis of heavy metal levels and soil fertility parameters suggested overuse of fertilizers may be related to heavy metal contamination in some regions. In summary, our study present by far the largest and most comprehensive landscape of heavy metal contamination in Shanghai agricultural soil, which will be useful for future policy-design and land use planning to ensure safe agricultural production

Toward understanding the cross‐linking from molecular chains to aggregates by engineering terminals of supramolecular hyperbranched polysiloxane

Abstract Crosslinking thermosets with hyperbranched polymers confers them superior comprehensive performance. However, it still remains a further understanding of polymer crosslinking from the molecular chains to the role of aggregates. In this study, three hyperbranched polysiloxane structures (HBPSi‐R) are synthesized as model macromolecules, each featuring distinct terminal groups (R denotes amino, epoxy, and vinyl groups) while similar molecular backbone (Si‐O‐C). These structures were subsequently copolymerized with epoxy monomers to construct interpenetrating HBPSi‐R/epoxy/anhydride co‐polymer systems. The spatial molecular configuration and flexible Si‐O‐C branches of HBPSi‐R endow them with remarkable reinforcement and toughening effects. Notably, an optimum impact strength of 28.9 kJ mol−1 is achieved with a mere 3% loading of HBPSi‐V, nearly three times that of the native epoxy (12.9 kJ mol−1). By contrasting the terminal effects, the aggregation states and crosslinking modes were proposed, thus clarifying the supramolecular‐dominant aggregation mechanism and covalent‐dominant dispersion mechanism, which influences the resulting material properties. This work underscores the significance of aggregate science in comprehending polymer crosslinking and provides theoretical insights for tailoring material properties at a refined molecular level in the field of polymer science