基于神经网络模型的波候变化影响下深海系泊缆疲劳损伤评估

全球气候变化导致波候变化显著,这一现象会造成系泊缆疲劳损伤的加速累积,危及到海洋平台的正常作业,甚至引发重大安全事故。然而,目前常用的频率和时域疲劳损伤评估方法均无法既准确又高效地计算考虑波候变化后的疲劳损伤。本文提出了一种基于贝叶斯正则化BP(back propagation)神经网络算法的深海浮式平台系泊系统疲劳损伤评估方法,在保证疲劳损伤评估精度的同时大幅提升了计算效率。以作业于北海的某半潜式平台和某单立柱平台及其系泊系统为研究对象,探究了波候变化对深海浮式平台系泊缆的全寿命期内疲劳损伤的影响规律,验证了方法的可行性与准确性,可为深海系泊缆的疲劳设计提供技术指导和解决方案。

Long-term variability of air temperature and precipitation conditions in the Polish Carpathians

Mountain regions are sensitive to climate changes, which make them good indicators of climate change. The aim of this study is to investigate the spatial and temporal variability of air temperature and precipitation in the Polish Carpathians. This study consists of climatological analyses for the historical period 1851-2010 and future projections for 2021-2100. The results confirm that there has been significant warming of the area and that this warming has been particularly pronounced over the last few decades and will continue in the oncoming years.Climate change is most evident in the foothills;however, these are the highest summits which have experienced the most intensive increases in temperature during the recent period. Precipitation does not demonstrate any substantial trend and has high year-to-year variability. The distribution of the annual temperature contour lines modelled for selected periods provides evidence of the upward shift of vertical climate zones in the Polish Carpathians,which reach approximately 350 meters, on average,what indicates further ecological consequences as ecosystems expand or become extinct and when there are changes in the hydrological cycle.

ANALYSIS OF TEMPERATURE CHANGES IN JANUARY AND JULY IN CHINA

The temperature change trends in January and July are analyzed and the results show that the trends descend in July but ascend in January except in South China and Southwest China. The relation between the temperature in January and July are discussed by using the wavelet. The results show that the trend phase in July and January are nearly in-phase in Southwest and South China, but are out-of-phase in other regions. Reconstruction of original temperature series in each of the regions indicates that their change trends are consistent with the original temperature series.

Wavelet Analysis and Nonparametric Test for Climate Change in Tarim River Basin of Xinjiang During 1959-2006

Using wavelet analysis,regression analysis and the Mann-Kendall test,this paper analyzed time-series(1959-2006) weather data from 23 meteorological stations in an attempt to characterize the climate change in the Tarim River Basin of Xinjiang Uygur Autonomous Region,China.Major findings are as follows:1) In the 48-year study period,average annual temperature,annual precipitation and average annual relative humidity all presented nonlinear trends.2) At the 16-year time scale,all three climate indices unanimously showed a rather flat before 1964 and a detectable pickup thereafter.At the 8-year time scale,an S-shaped nonlinear and uprising trend was revealed with slight fluctuations in the entire process for all three indices.Incidentally,they all showed similar pattern of a slight increase before 1980 and a noticeable up-swing afterwards.The 4-year time scale provided a highly fluctuating pattern of periodical oscillations and spiral increases.3) Average annual relative humidity presented a negative correlation with average annual temperature and a positive correlation with annual precipitation at each time scale,which revealed a close dynamic relationship among them at the confidence level of 0.001.4) The Mann-Kendall test at the 0.05 confidence level demonstrated that the climate warming trend,as represented by the rising average annual temperature,was remarkable,but the climate wetting trend,as indicated by the rising annual precipitation and average annual relative humidity,was not obvious.

WAVELET ANALYSIS OF INTERANNUAL VARIATION OF TROPICAL CYCLONES IN GUANGDONG

Climatological laws are studied for the annual frequency of tropical cyclone occurrence and the date of the yearly first landfall, which take place in the Guangdong province or pose serious threats on it from 1951 to 1999, using the data in the Yearly Book on Typhoons. A new method that has developed over recent years for the study of temporal sequences, the wavelet analysis, is used, in addition to more common statistical approaches. By analyzing two wavelet functions, MHAT and MORLET, we have compared the results of transformation of the wavelets provided that other conditions remain unchanged. It is discovered that the variance of MORLET wavelet has better indication of primary periods; period-time sequence charts can reflect major affecting periods for individual sections of time; when compared with the original sequence, the chart shows a little shift. On the other hand, such shift is absent in the MHAT wavelet, but its higher frequency part of variance covers up the primary periods to make its variance less predominant as compared to the MORLET wavelet. Besides, the work compares two different assumptions of an amplifying factor a. It is found that primary periods can be shown more clearly in the variance when a takes the exponential of 2 than it takes values continuously. Studying the annual frequency of tropical cyclones and the date of first appearance for periodic patterns, we have found that the primary periods extracted by this approach are similar to those obtained by wavelet transformation.

Evidence of Climate Variability in Imo State of Southeastern Nigeria

Climate variation generally occurs at local scale, regional scale, national scale and global scale. Having established that the global climate has varied slowly over the past millennia, centuries, and decades and it is expected to continue to vary in future. Like the climate change, variability may be due to, national internal processes within the climate （internal variability）, or variations in natural or anthropogenic external forces （external variability）. Evidence of climate variations is now well documented, and the implications are becoming increasingly clear as data accumulates and data and climate models become increasingly sophisticated. The fluctuations in rainfall and temperature regimes are the atmospheric driving forces that are responsible for the climate variations over the southeastern Nigeria including Imo State as the case in other parts of the world. It is on this premise that this study examined the evidence of climate variability in Imo State of the southeastern Nigeria. The study employed the holistic use of real meteorological data from Nigerian Meteorological Department on two weather parameters （temperature and rainfall）, for 30 years （1980-2009）. Results indicated fluctuations in temperature and rainfall regimes within the period under study, which were the reasons for the variations in climate of the region. Apparently, evidence of climate variability are indicated by increasing surface air temperature, increasing heat waves which enhances disease vectors, communicable diseases and epidemics, sea level rise and associated coastal erosion, flooding, increased evaporation that dry up streams and rivers etc..

Power Generation from Municipal Solid Waste Plastics

Generation of electrical energy from imported fossil fuels is subject to the price fluctuations of the global marketplace and, thus, constitutes a major expense in its distribution to the end users. Even with the current low prices of fuel, residents and businesses in the United States pay a significant price for their utilities, if not higher than most other countries in the world. Emissions from the evaporation and combustion of these traditional fossil fuels contribute to a range of environmental and health problems, causing poor air quality, and emitting greenhouse gases that contribute to global warming. Alternative fuel created from domestic sources has been proposed as a solution to these problems and much alternative energy are being developed based on solar, wind, biomass, hydropower, fuel cell, geothermal, etc. A new alternative hydrocarbon fuel which is produced from waste plastics can be used with compatble power plants and generators appliances to produce electricity that can be supplied into homes, businesses, power grids and other sectors.