Search

Jet formation is the decisive factor of penetrating power of shaped charge, coherence and stability contribute to penetration. In the same condition, multiple penetrating tests of the shaped charge with depleted uranium(DU) liner did not get the expected results. In order to study the jet forming characteristics of DU liner under static explosion condition, an X-ray photography experiment was designed, which turned out to show the jet being badly incoherent. To research the incoherence of DU shaped charge jet from principles of jet incoherence, supersonic collision worked out to be the reasons for incoherence of the shaped charge jet. This paper provides a method for structural optimization of DU shaped charge and DU liner processing, which has guiding significance for application of DU liner in high explosive antitank projectile.

Al2O3, TiO2, ZrO2 and SiO2 were used for adsorptive dechlorination of model oil at different temperatures. The results showed that chlorine removal over the four mesoporous oxides sharply increased with increasing the temperature from 20 °C to 150 °C. GC–MS and ion chromatography analysis showed that 1-chlorooctane was converted into 1-octanol and chloride ion at the temperature higher than 120 °C, which were then adsorbed on the adsorbent. Precipitation pH had a significant impact on the dechlorination performance of Al2O3. Among various porous oxides, Al2O3-9.5 precipitated at pH 9.5 exhibited the highest dechlorination performance, over which the chlorine removal reached 99% after adsorption for 3 h at 150 °C. The characterization results indicated that various porous oxides contained only Lewis acid, and the dechlorination performance of the adsorbent basically increased with the increase of its total Lewis acid amount. The dechlorination efficiency for different organochlorine compounds followed the order: straight chain alkyl chlorides > chlorinated cycloalkanes > aromatic hydrocarbons. Al2O3-9.5 showed good regenerability, and the dechlorination performance of Al2O3-9.5 had only a slight decrease after six consecutive dechlorination-regeneration cycles, due to slight loss of its Lewis acid amount and surface area.

Compared with traditional on-site oil spill monitoring, the use of remote sensing technology has the macroscopic characteristics, which could quickly and accurately find an oil spill area. Currently, the detection approach of monitoring the phenomenon of marine oil spill are usually divided into two types, which are optical and synthetic aperture radar SAR remote sensing imagery. Among all satellite sensors, SAR is still the most utilized for operational oil spill detection. Thus, adopt SAR imagery to achieve routinely monitoring. In the image analysis process, the discrimination of oil spills and look-alike phenomena e.g., low wind area, wind front area and natural slicks on SAR is a crucial task in marine oil spill. A support vector machine is employed to remote sensing image classification in this paper. Through the simulation of the Dalian oil spill event, the effectiveness of the proposed approach for SAR satellite image classification is verified.

Coral reef communities face unprecedented pressures at local, regional and global scales as a consequence of climate change and anthropogenic disturbance. Remote sensing, from satellites or aircraft, is possibly the only means to measure the effects of such stresses at appropriately large spatial scales. In the past 30 years, remote sensing of coral reefs has made rapid progress. However, the current technology is still not mature enough to monitor complicated coral reef ecosystems. Compared with foreign research in this field, our work lags far behind. There are still deficiencies in many aspects, such as basic data collection, theoretical research and platform construction. In our nation, it is even unclear how coral reefs disperse and where they may be unhealthy. In this paper, general characteristics of coral reef ecosystems and spectral features of different reef benthos have been summarized, based initially on a review of relevant literature in recent years. Based on the spectral separability of different reef types or benthos, remote sensing can be used to monitor two aspects of coral reefs: (1) Measurement of the ecological properties of reefs. (2) Health assessment of the coral reef ecosystem. In the first part, optical remote sensing methods are widely used to map reef geomorphology and habitats or biotopes. The investigation of geomorphologic zonation has proven to be one of the most successful applications, as different geomorphologic zones are associated with characteristic benthic community structures and occur at spatial scales of tens to hundreds of meters, they are amenable to remote detection by moderate to high resolution sensors. With more and more attention on the ecological problems of coral reefs, a number of studies have used high resolution sensors to map reef communities. The number of classes distinguishable depends on many factors, including the platforms, resolution (spectral, spatial and temporal resolution) and environmental conditions (water depth, water clarity, surface roughness, etc.). Compared with deep water color remote sensing, or terrestrial remote sensing, three techniques for the measurement of reef ecological properties are examined in this paper: (1) Coral reef classification system using remote sensing. (2) Techniques of sea surface correction and water column correction. (3) Techniques of coral reef information extraction from images. In terms of the complexity of coral reef ecosystems, the current techniques still need further improvement or optimization. In the health assessment of coral reef ecosystems, there are two ways to carry out the monitoring using remote sensing: (1) Monitoring the pigment or symbiotic zooxanthellae contents in corals. (2) Measuring the environmental properties of reefs. The first way is theoretically feasible, but difficult to achieve in practice. Currently, most reef health assessments are carried out by measuring environmental parameters, including sea surface temperature, solar radiation, ultraviolet radiation, water color, wind speed and direction, rainfall, ocean acidification, sea level, etc., of which sea surface temperature has been routinely measured by NOAA to monitor coral bleaching. In addition to the contents above, this article puts forward five main prospects for development in the future: (1) Establishment of a coral reef classification system using remote sensing. (2) Satellite launch for monitoring coral reefs. (3) Theoretical and methodological development. (4) Establishment of a spectral database for different reef benthos. (5) Integrated application of multi-source remote sensing data. It is hoped that the information provided here will be a reference for subsequent similar studies.

The assessment of the hazard degree of red tide is a new research field. The current study analyzes the relationship between the specific growth rate and N/P atomic ratio of red tide to obtain the assessment results of red tide under various N/P atomic ratios. This study aims to develop a nutrient-based method that can assess the hazard degree of red tide disasters based on the algal growth and cell density threshold of red tide outbreaks. This study obtained the following four main findings: (1) a nutrient-based tolerance model of the algal growth that can provide a quantitative description of Shelford’s law of tolerance was established, (2) a method that can assess the hazard degree of red tide disasters based on the time the algal growth reached the cell density threshold of red tide outbreaks was proposed, (3) the hazard degree assessment of red tide disasters was classified into four grades, namely, very high, high, medium, and low, and (4) the spatial distribution map of the Alexandrium tamarense red tide outbreak probability in the Zhejiang coastal waters was generated using the proposed method and the geographic information system and remote sensing technology.

Estuaries, which lie at the end of rivers, belong to the interlocking area between marine ecosystems and terrestrial ecosystems. In the estuary region, there are plenty of biological resources that carry many important ecosystem services. However, severe degradation of the estuary ecosystem in northern China has been caused by anthropogenic disturbances, including water pollution from upstream area, change of marine environmental dynamics, animal habitat loss, and unreasonable exploitation in the estuary region. In order to provide scientific evidence for restoration and conservation of the estuary ecosystem, we collected data from published literature to analyze the ecological problems in several main estuary regions in northern China, such as the Yellow River estuary, Liaohe River estuary, Haihe River estuary, Yalu River estuary, and some others. The main ecological problems in the estuary region of northern China include the input decrease of fresh water from rivers, the change of the sediment input from rivers, the destruction of the estuary wetland ecosystem, the environmental pollution in the estuary region, the erosion in the estuary region, seawater encroachment, the biodiversity decline of the estuary region, and the depletion of the fish resources in the estuary region. Meanwhile, the driving forces for these ecological problems in the estuary region were also assessed. Based on the analysis of these driving forces, we propose several pieces of advice for integrated estuary management in northern China, including the creation of a management system for estuary conservation, improvement of the means and strength of the environmental law execution, increased investment on scientific research in the estuary ecosystem, improvement of public participation on the conservation for the estuary environment and biodiversity, and construction of a monitoring system for the estuary environment.

Between the years 1933–2001, 460 red tide events were found in China's coastal water. The scope of red tide occurrence has extended over all the coastal provinces of China, and the three major areas with high red tide frequency are the Bohai sea, the sea area near the Shengsi Archipelago and Huaniaoshan Island on the outer side of the Changjiang River estuary and the Hangzhou Bay, and the coastal waters on the east side of the Zhujiang River estuary from Hong Kong to East Guangdong. In the past 20 years, the frequency of red tides has been tending upwards. The years of 1988–1990 and 1998–2001 saw the most serious red tides along China's coastal waters, with the latter period as the peak. The average area of a single red tide, i.e., the scale of red tides, is expanding every year, and in 2001 rose to about 500 km2. Every year, China's red tides occur from south to north, with those in the South China Sea occurring from March to May, those in the East China Sea from April to August and those in the...

To improve polarimetric synthetic aperture radar (PolSAR) imagery segmentation accuracy, a modified non-negative matrix factorization algorithm based on the support vector machine is proposed. Focusing on PolSAR remote sensing images, the modified non-negative matrix factorization algorithm with the neurodynamic optimization achieves the image feature extraction. Compared with basic features, such as the basic backscatter coefficient, structuring more targeted localization non-negative character fits better for the physical significance of remote sensing images. Furthermore, based on the new constructive features, a support vector machine is employed for remote sensing image classification, which remedies the small sample training problem. Simulation results on PolSAR image classification substantiate the effectiveness of the proposed approach.

China is one of the most severely affected countries by coastal erosion. About 70% of the sandy beaches and most of muddy tidal flat in open water regions are erode. Coastal erosion results in the width of beach being narrowed, bathing beach destruction, coast-protection facilities and roads collapse, and wetland deterioration. These destructions bring many losses to the local people. However, previous coastal erosion studies focused on the hazard of erosion and paid less attention to the risk of erosion. Therefore, it’s necessary to study the mechanism of coastal erosion and build the coastal erosion risk assessment system for the effective coastal management. On the basis of the existed researches, this paper builds the coastal erosion risk assessment index system which contains hazard index system and vulnerability index system. The index system is expected to provide a practical theoretical basis for coastal erosion risk assessment.

Aerosol optical thickness (AOT) data measured with a ship-based multi band sun photometer and CE318 from 2003 to 2009 was taken to study the temporal and spatial distribution characteristics of AOT, turbidity coefficient¦Â(which denotes the particle concentration) and Angstromexponent ¦A (which denotes the mean size) over the Bohai Sea and Dalian coast.

Ultraviolet radiation A (UVA)-induced oxidative stress is recognized as an important factor in the development of skin carcinogenesis. Resveratrol is demonstrated to possess remarkable antioxidant activity in the organism. The aim of this study was to investigate the protective role of resveratrol in human keratinocytes (HaCaT) against UVA-induced oxidative damage and the possible mechanism of the translocation of NF-E2-related factor-2 (Nrf2) into the nucleus. The HaCaT cells were UVA-irradiated and the effects of resveratrol on cell viability, reactive oxygen species generation and membrane-lipid peroxidation were measured. The proteins and mRNA of Nrf2 and Kelch-like-ECH-associated protein 1 (Keap1) were determined by immunofluorescence staining, Western blot and quantitative PCR, respectively. UVA exposure led to a decrease in viability and an increase in reactive oxygen species generation in HaCaT cells. Resveratrol could effectively increase the viability of HaCaT cells after UVA exposure and protect them from UVA-induced oxidative stress. Moreover, resveratrol increased the level of Nrf2 protein and facilitated Nrf2 accumulation in the nucleus; as a result, the activity of antioxidant enzymes was also upregulated. The main finding was that Keap1 protein, a repressor of Nrf2 in the cytoplasm, was clearly decreased by resveratrol treatment 12h and beyond though the level of Keap1 mRNA still increased. Our results suggest that resveratrol can degrade Keap1 protein and facilitate Nrf2 accumulation in the nucleus, thereby protecting HaCaT cells from UVA-induced oxidative stress. Resveratrol could be a more useful natural medicine for the protection of epidermal cells from UVA-induced damage.

To calculate and analyses the spatial distribution of red tide hazard degree and the probability of red tide outbreak, a geographical information system (GIS)-based method was proposed based on the hazard degree assessment model and the in-situ conventional monitoring data in Bohai Bay conditions. The results indicate that the spatial distribution of red tide hazard degree in Bohai Bay presents an annular band around the shore, and that from near-shore waters to open waters, the red tide hazard degree first increases and then decreases with the increase of the distance from shore. The red tide hazard degree within the optimum distance accounts for the high-hazard degree areas (“red”, “yellow”, H=0.5–1), while the low-hazard degree areas (“blue”, “green”, H=0–0.5) are found in the near-shore waters and open waters.

This paper analyses the relation between data measured in situ and the NDVI derived from AVHRR of NOAA-14 during algal bloom in the Bohai sea in 1998 to establish surface biomass model of Ceratium furca (EHr.). This model is easy to utilize data received from multi-source satellite in operation, and gets directly the index of phytoplankton biomass. The area and distribution of high biomass is also presented. Based on this model, propagation speed of phytoplankton reveals progress of algal bloom development. The result of this model can discriminate algal bloom water from silt or suspended particle material (SPM).