海南博螯沿岸地貌与人类活动的潜在影响

The Boao coastal system along the eastern coast of Hainan Island is a dynamic delta-tidal inlet-barrier formed during the late Holocene. The delta developed inside a shallow lagoon barred by a sandy barrier with a narrow, shallow tidal inlet opening. Two major distributary channels separated by small islands characterize the delta. The lagoon is silting up receiving and trapping sediments from both the river and, in minor measure during storms, through the tidal inlet opening and barrier washovers. The barrier at the tidal inlet is highly dynamic and changes its form, accreting (migrating spit) against the inlet during fair-weather conditions and being eroded during storms and river floods.The delta has almost completely filled the lagoon and major concerns exist on the effect that ongoing large development plans may have on the environment. These concerns include the effect on floods and rate of siltation once banks of the islands have been stabilized and floodwater and sediment load are impeded from spreading over the lowlands, and the effect of increasing pollutant loads from the new facilities on the ecosystems of the increasingly restricting lagoon water and on the seashores.     

Seagrass landscape-scale changes in response to disturbance created by the dynamics of barrier-islands: A case study from Ria Formosa (Southern Portugal)

This study documents long-term changes of a Zostera noltii landscape induced by a natural cyclic event in a coastal lagoon. The barrier-islands forming this system are very dynamic with drifting movements controlling ecological patterns and processes occurring in this area. Changes in the areal extent of the Z. noltii meadows were assessed using historical aerial photographs from 1940, 1980, 1989, 1996 and 1998. Landscape indices such as total patch area (TA), mean patch size (MPS), number of patches (NP), mean shape coefficient of variation (CV) and landscape fractal dimension (D) were calculated for each year and related to an index of disturbance intensity. The spatial distribution of the Z. noltii meadows varied greatly during the studied period and changes observed were related to the disturbance created by the barrier-islands' spatial dynamics. After an artificial inlet relocation the Z. noltii area, number of patches, patch mean size and coefficient of variation decreased. The fractal dimension of the Z. noltii landscape increased by 50% showing that besides a decrease in total area, number of patches, and patch mean area, patch fragmentation was an important consequence of this anthropogenic disturbance.Seagrass natural distribution patterns changed in response to natural and human-induced activities. This study emphasizes the importance of the landscape approach and the historical perspective when studying seagrass changes and the importance of taking into consideration long-term changes in seagrass landscapes to avoid confusion between man-induced effects with natural cyclic events.     

加强XENIX系统安全性的若干方法

ＸＥＮＩＸ作为一种多用户多任务的开放性的操作系统,容易受到攻击和破坏。本文介绍的产种方法可用来提高ＸＥＮＩＸ系统的安全性。     

A new methodology for building local climate change scenarios: A case study of monthly temperature projections for Mexico City

This paper proposes a new methodology for generating climate change scenarios at the local scale based on multivariate time series models and restricted forecasting techniques. This methodology offers considerable advantages over the current statistical downscaling techniques such as: (i) it provides a better representation of climate at the local scale; (ii) it avoids the occurrence of spurious relationships between the large and local scale variables; (iii) it offers a more appropriate representation of variability in the downscaled scenarios; and (iv) it allows for compatibility assessment and combination of the information contained in both observed and simulated climate variables. Furthermore, this methodology is useful for integrating scenarios of local scale factors that affect local climate. As such, the convenience of different public policies regarding, for example, land use change or atmospheric pollution control can be evaluated in terms of their effects for amplifying or reducing climate change impacts.     

矿产资源勘查可持续发展及跨越式发展的主要制约因素及对策

本文阐述了矿产资源可持续发展与跨越式发展的关系，指出矿产资源可持续发展主要依靠矿产资源勘查的可持续发展和跨越式发展，其主要制约因素是科技、人才和资金。文中分析了我国矿产资源勘查行业科技、人才、资金状况，并提出了解决制约矿产资源勘查可持续发展和跨越式发展的主要对策。     

Development of a regional neural network for coastal water level predictions

This paper presents the development of a Regional Neural Network for Water Level (RNN_WL) predictions, with an application to the coastal inlets along the South Shore of Long Island, New York. Long-term water level data at coastal inlets are important for studying coastal hydrodynamics sediment transport. However, it is quite common that long-term water level observations may be not available, due to the high cost of field data monitoring. Fortunately, the US National Oceanographic and Atmospheric Administration (NOAA) has a national network of water level monitoring stations distributed in regional scale that has been operating for several decades. Therefore, it is valuable and cost effective for a coastal engineering study to establish the relationship between water levels at a local station and a NOAA station in the region. Due to the changes of phase and amplitude of water levels over the regional coastal line, it is often difficult to obtain good linear regression relationship between water levels from two different stations. Using neural network offers an effective approach to correlate the non-linear input and output of water levels by recognizing the historic patterns between them. In this study, the RNN_WL model was developed to enable coastal engineers to predict long-term water levels in a coastal inlet, based on the input of data in a remote NOAA station in the region. The RNN_WL model was developed using a feed-forwards, back-propagation neural network structure with an optimized training algorithm. The RNN_WL model can be trained and verified using two independent data sets of hourly water levels.The RNN_WL model was tested in an application to Long Island South Shore. Located about 60–100 km away from the inlets there are two permanent long-term water level stations, which have been operated by NOAA since the1940s. The neural network model was trained using hourly data over a one-month period and validated for another one-month period. The model was then tested over year-long periods. Results indicate that, despite significant changes in the amplitudes and phases of the water levels over the regional study area, the RNN_WL model provides very good long-term predictions of both tidal and non-tidal water levels at the regional coastal inlets. In order to examine the effects of distance on the RNN_WL model performance, the model was also tested using water levels from other remote NOAA stations located at longer distances, which range from 234 km to 591 km away from the local station at the inlets. The satisfactory results indicate that the RNN_WL model is able to supplement long-term historical water level data at the coastal inlets based on the available data at remote NOAA stations in the coastal region.     

一种基于里程参数的道路平面几何解析模型

随着主动安全技术、自动驾驶技术的发展,高精度导航地图得到越来越多的运用。本文提出了一种面向高精度导航地图的、基于里程参数的道路平面几何解析模型。通过动态地构造点集上的正交多项式系和约束最小二乘法,根据拟合最大误差动态地计算道路的几何描述参数。使用该模型进行了120 km高速道路高精度地图数据生产,以三段典型道路为实例进行试验,表明该方法能对道路几何进行准确的描述,保证道路几何的连续与光滑,同时最大限度地减少数据冗余。该模型对高精度地图道路几何描述具有一定优势。     

The use of fractal geometry to determine the impact of inlet migration on the dynamics of a seagrass landscape

The use of fractal geometry to evaluate seagrass scaling behavior and the persistence of seagrass landscape patterns in relation to a disturbance is presented in this paper.Ria Formosa is a dynamic barrier-island system with a migrating inlet that creates a cyclic disturbance in a seagrass landscape. Seagrass patches which develop in the intertidal and shallow subtidal areas of Ria Formosa were digitized from a temporal sequence of aerial photographs, from 1980 to 1998. The methodology used to evaluate seagrass scaling behavior was proposed by Meltzer and Hastings (1992), and relates the frequency distribution of patch size with the existence of patch size-related patterns. The Hurst exponent was calculated to assess the temporal persistence of the seagrass landscape. Univariate regression was used to investigate relations between temporal persistence and disturbance. The existence of patch size-related patterns was identified for all years suggesting shifts in generating processes occurring at different domains of scales in the seagrass landscape. The results enforces the idea that it is important to recognize the existence of diverse processes occurring at different domains of scales and, emphasizes the importance of evaluating issues of temporal and spatial scale while trying to understand changes in seagrass landscapes. The Hurst exponent estimates show that although the migration and relocation of the inlet affected this system the evolutionary trajectory of the seagrass landscape is persistent, i.e., the patch dynamics observed is stable. Furthermore, persistence values were different for differently sized patches, small patches having lower persistence then larger patches.     

吉林省限制开发区域绿色发展格局演变及障碍因素识别

以吉林省限制开发区域为实证研究区域,基于2005、2010、2015、2017年各市(州)的截面数据,从绿色增长、绿色福利、绿色财富3个维度构建绿色发展指标体系,运用熵权-TOPSIS模型、障碍度模型等方法,探究吉林省限制开发区绿色发展水平的时空演变特征及障碍因素。结果表明:①2005-2017年吉林省限制开发区绿色发展水平呈现"N"字型波动上升的时序演化特征,总体上绿色发展水平上升较慢。②吉林省限制开发区绿色发展水平存在明显的空间分异特征,总体呈现东部高,中、西部低的特征,且两级分化特征更加明显。③人均工业增加值、第二产业产值比重、建成区绿化覆盖率、每万人拥有普通高等学校人数、人均水资源量、城市生活污水处理率是研究期内制约吉林省限制开发区绿色发展水平提升的主要指标层障碍因子。