江西食物生产波动特征与效率研究

食物波动与效率是食物安全的重要研究内容。1993~2003年江西省平均食物生产全要素相对生产率为0.974,其规模效益基本上呈现常数规模效益与规模效益递增交替波动现象。灰色关联分析表明,粮食产量、油料产量、肉类产量、糖料产量等与食物总量具有显著关联性,其灰色关联序为：粮食产量＞油料产量＞肉类产量＞糖料产量＞禽蛋产量＞水果产量＞牛奶产量,所以要保证食物总量安全,必须首先保障粮食、油料、肉类等的生产。     

Case study: Assessment on large scale LPG BLEVEs in the 2011 Tohoku earthquakes

After the 2011 Tohoku earthquakes, several chemical and oil complexes on the Pacific Ocean shoreline of northeast Japan experienced massive losses. In Chiba, a refinery operated by Cosmo Oil lost 17 LPG storage vessels which were either heavily damaged or totally destroyed by fires and explosions in the refinery. These large vessels ranged in size from 1000 to 5000 m³. The estimated volume of LPG at the time of the incident was between 400 and 5000 m³ for each vessel. Five boiling liquid expanding vapor explosions (BLEVEs) of LPG occurred, resulting in huge fire balls measuring about 500 m in diameter.A BLEVE is defined as the explosive release of expanding vapor and boiling liquid when a container holding a pressure-liquefied gas fails catastrophically. It is thus important to estimate the physical properties of superheated liquids: the thermodynamic and transport properties, the intrinsic limits to superheating and depressurization, and the nature of thermodynamic paths. Also it is hoped to provide better understanding of the vessels designed, manufactured, installed, and operated to reduce or eliminate the probability that a sequence of events will result in BLEVE or loss of primary containment. Knowledge of these matters is still incomplete. The objective of this research is to estimate the significant BLEVE phenomenon in very large scale spherical vessels based on published information in Japan. There are some models predicting BLEVEs. However, it is essential to know if this is true for very large scales such as spheres since validation is usually rare to provide confidence in estimating the superheated liquids behaviors. To this end, comparing with the information on this event, the conditions in the five LPG vessels at the time of the BLEVE were determined in terms of: duration of vessel failure (time to BLEVE); mass fraction in the vessel with time; temperature distribution in the liquid and vapor region and pressure within the vessel (e.g. initial pressure and internal high-speed transient pressure during failure), by means of a computer program AFFTAC Analysis of Fire Effects on Tank Cars, which solves heat conduction, stress and a failure model of the tank, a thermodynamic model of its fluid contents, and a flow model for the lading flowing through the safety relief device. Subsequently, the consequences from the sphere BLEVE, such as the expected fireball diameter and duration and the expected blast overpressure produced by the BLEVE failures, are also subjects of active research. Here the blast using the methods of PHAST and SFPE Handbook of Fire Protection Engineering was calculated.Results suggest that methodologies here used gave reasonable estimations for such real and huge BLEVEs in a validated way, which may provide valuable guidance for risk mitigation strategy with regard to LPG facility in design, emergency planning, resiliency, operations, and risk management.     

系统聚类分析在农户生态系统类型划分中的应用

应用主成分分析法和系统聚类分析法，对湖北省京山县刘家岭村５０个农户进行了生态系统类型数值分类分析，结果表明，该村农户生态系统可分为农－牧业型、果－农－牧业型和渔－农－牧业型三类，与全村３３８个农户情况相符。     

耕地土壤中交换态钙镁铁锰铜锌相关关系研究

应用主成份分析、聚类分析和相关性分析对沈阳市郊区1994个耕地土壤样本(0-20cm)的交换态钙、镁、铁、锰、铜、锌含量进行研究，结果表明，影响钙与镁、铁与锰、铜与锌分布的主因子分别在相同的主成份组中，钙与镁、铁与锰、铜与锌之间的相关系数较大，铁、锰、铜、锌之间均为极显著正相关关系，钙与铁、锰、铜、锌均为负相关关系，说明元素的生物地球化学属性对其地理分布有较大的影响。     

Application of adaptive cluster sampling to low-density populations of freshwater mussels

Freshwater mussels appear to be promising candidates for adaptive cluster sampling because they are benthic macroinvertebrates that cluster spatially and are frequently found at low densities. We applied adaptive cluster sampling to estimate density of freshwater mussels at 24 sites along the Cacapon River, WV, where a preliminary timed search indicated that mussels were present at low density. Adaptive cluster sampling increased yield of individual mussels and detection of uncommon species; however, it did not improve precision of density estimates. Because finding uncommon species, collecting individuals of those species, and estimating their densities are important conservation activities, additional research is warranted on application of adaptive cluster sampling to freshwater mussels. However, at this time we do not recommend routine application of adaptive cluster sampling to freshwater mussel populations. The ultimate, and currently unanswered, question is how to tell when adaptive cluster sampling should be used, i.e., when is a population sufficiently rare and clustered for adaptive cluster sampling to be efficient and practical? A cost-effective procedure needs to be developed to identify biological populations for which adaptive cluster sampling is appropriate.     

计算机辅助确定外因火灾位置方法

系统介绍用计算机辅助确定矿井外因火灾位置方法的原理,给出该方法的具体步骤,剖析其定性分析、定量分析和定量分析结果评价三大步骤中的各技术关键,并借助一个实例验证了该方法实用的可行性     

Injuries as a Result of California Earthquakes in the Past Decade

The devastating effects of earthquakes have been demonstrated repeatedly in the past decade, through moderate and major earthquakes such as the October 1987 Whittier Narrows earthquake (5.9 on the Richter scale), the October 1989 Loma Prieta earthquake (7.1) and the January 1994 Northridge earthquake (6.7). While 'official' tallies of injuries and deaths are reported for each event, the numbers vary from report to report. For Northridge, the number of injuries vary between 8,000 and 12,000; the number of deaths from 33 to 73 (Peek-Asa et al., 1997; Durkin, 1996).While official estimates are commonly reported following disasters, the study of actual numbers, types and causes of casualties has not developed. In this paper, we identify the numbers and risk factors for injuries within community-based samples across three earthquakes in urban California. We first report the numbers and types of injuries in each earthquake and then identify risk factors specifically associated with the Northridge earthquake     

Seasonal Fluctuation in Heavy Metal Pollution in Iran´s Siahroud River - A Preliminary Study (7 pp)

Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed into the various water systems supported by the river, including the water system for Rasht City. Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe, and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed by IR gas measurement. Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly different. Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution levels of Pb, Cd, Mn and Fe.     

石家庄大气污染物输送通道及污染源区研究

为探索石家庄的区域输送规律,确定主要污染源区,利用HYSPLIT(Hybrid Single Particle Lagrangian Integrater Trajectory)后向轨迹模式和NCEP的GDAS全球气象要素数据,对2013—2016年从不同高度上抵达石家庄地区的逐日72 h气流后向轨迹进行聚类分析,并结合石家庄逐小时颗粒物污染物浓度数据,分析石家庄PM2.5的潜在源贡献因子(WPSCF)和浓度权重轨迹(WCWT).结果表明,(1)石家庄PM2.5浓度具有明显单峰谷日变化,秋冬季与春夏季峰谷值出现时间不同;(2)近地层大气污染输送路径以近距离,移速慢的轨迹为主,轨迹较短的路径所占比例在40%以上.除夏季外,近距离输送路径均存在螺旋转向,在后向48~36 h内轨迹端点到达河北省内,转为东向和南向输送.(3)大气污染输送通道的垂直分布特征表明,输送轨迹中低于500 m高度的轨迹点占28.7%,高于1000 m低于3000 m高度的轨迹点占36.1%,高于3000 m高度的轨迹点占25.3%.低层多以近距离输送为主,高度越高,近距离输送轨迹的频率越低.500 m高度输送通道仍以近距离输送为主,并存在螺旋转向,1500 m高度以上多远距离输送.(4)石家庄PM2.5的主要污染源区范围较小.途径河北中南部、河南北部、山东西部和山西中北部地区的轨迹对石家庄PM2.5的污染贡献最大.     

军用飞机结构类型聚类分析

选取某型飞机16个典型结构,采用温、湿度测量仪测量其局部温、湿度,测量周期为2个月,分别获得673个有效温、湿度实测数据。根据实测数据,采用模糊聚类算法对飞机结构类型进行归并分析,当模糊矩阵阈值λ=0．7时,飞机结构类型可归并为开式、半开式、封闭式3种典型结构形式。