危化品泄漏事件中应急监测的安全防护距离计算与监测布点方案

通过建立大气湍流扩散模型,结合大气、地形条件等环境基本资料和危化品的性质,计算出危化品泄漏突发事件的应急防护范围,为人群撤离和监测布点监控,提供安全保障。     

我国危险化学品企业搬迁方案研究

概要地对我国现有危险化学品企业安全防护距离不足的现状进行分析,提出危险化学品企业搬迁工作实施的基本原则,探讨危险化学品企业搬迁范围的确定、厂址的解决、资金的分配、政策的制定和长效机制的建立等问题。建议搬迁企业在政府的统一规划下,坚持以人为本,坚持安全生产和可持续发展的原则,在搬迁中提高技术含量和社会形象,增强市场竞争力。针对我国危险化学品企业的特点提出了一套搬迁方案和步骤。论文的研究成果将为各地政府指导当地危险化学品企业进行科学规划,对待搬迁的危险化学品企业实现安全有效搬迁及健康发展提供了有益参考。     

立体结构障碍物对甲烷预混火焰传播影响的研究

使用自行设计的火焰加速试验系统,研究了3种立体结构障碍物对管道内预混火焰传播速度和超压的影响。选用长方体、正四棱柱和圆柱,其阻塞比均为40%。结果表明,管道内障碍物对火焰传播的初始阶段起阻碍作用,当火焰越过障碍物后,障碍物加速火焰传播过程。有障碍物时管道内最大火焰传播速度和峰值超压比无障碍物时要大。随着点火距离的增大,管道中最大火焰传播速度和超压先变大后减小。当障碍物位于约6倍管径处时,对管道中火焰传播速度和超压影响最大。点火距离的改变对火焰传播速度的影响大于对管道内超压的影响。     

复杂山区地形水利水电液氨施工泄漏研究

水电工程中液氨泄漏扩散对周围居民的危害很大,疏散区域划分成为重要的防护措施,但在复杂地形条件下确立准确的疏散区域成为难题。为解决这一难题,通过现场调查所得数据,采用大涡模拟方法对泄漏气体扩散进行模拟,分析氨的泄漏扩散在大气中的扩散规律,研究泄漏气体的扩散动力学演化过程及影响范围,计算泄漏事故中不同时间段影响范围,得出时间序列上的爆炸危险区域和有毒气体影响区域,最后总结分析制定安全防护距离的影响因素,为周边居民安全防护策略提供参考。     

基于隶属函数的高速公路安全距离模型研究

为了改善高速公路防追尾安全距离模型,对模型中的驾驶员反应时间进行研究,分析不同车速时驾驶员反应时间对安全距离的影响。驾驶员反应时间受驾龄、应变能力、性别、心理生理状况、车速等多种因素的影响。基于模糊数学中隶属函数的有关理论,利用Matlab软件,在驾驶员反应时间大小允许的范围内,综合考虑各种主要因素,确定驾驶员反应时间。通过具体实例说明该方法的应用,结果证明,应用模糊数学,可以计算出不同的驾驶员,在不同的车速时的反应时间。     

Hydrologic Connectivity and the Contribution of Stream Headwaters to Ecological Integrity at Regional Scales1

Abstract: Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water‐mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two‐thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large‐scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free‐flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large‐scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream‐system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and terrestrial ecosystems. Linkages between headwaters and downstream ecosystems cannot be discounted when addressing large‐scale issues such as hypoxia in the Gulf of Mexico and global losses of biodiversity.     

Hydrology and Water Budget for a Forested Atlantic Coastal Plain Watershed,South Carolina1

Abstract: Increases in timber demand and urban development in the Atlantic Coastal Plain over the past decade have motivated studies on the hydrology, water quality, and sustainable management of coastal plain watersheds. However, studies on baseline water budgets are limited for the low‐lying, forested watersheds of the Atlantic Coastal Plain. The purpose of this study was to document the hydrology and a method to quantify the water budget of a first‐order forested watershed, WS80, located within the USDA Forest Service Santee Experimental Forest northeast of Charleston, South Carolina. Annual Rainfall for the 2003 and 2004 periods were 1,671 mm (300 mm above normal) and 962 mm (over 400 mm below normal), respectively. Runoff coefficients (outflow as a fraction of total rainfall) for the 2003 and 2004 periods were 0.47 and 0.08, respectively, indicating a wide variability of outflows as affected by antecedent conditions. A spreadsheet‐based Thornthwaite monthly water balance model was tested on WS80 using three different potential evapotranspiration estimators [Hamon, Thornthwaite, and Penman‐Monteith (P‐M)]. The Hamon and P‐M‐based methods performed reasonably well with average absolute monthly deviations of 12.6 and 13.9 mm, respectively, between the measured and predicted outflows. Estimated closure errors were all within 9% for the 2003, 2004, and seasonal water budgets. These results may have implications on forest management practices and provide necessary baseline or reference information for Atlantic Coastal Plain watersheds.     

Effects of Watershed Impervious Cover on Dissolved Silica Loading in Storm Flow1

Abstract: Dissolved silica (DSi) availability is a factor that affects the composition of algal populations in aquatic ecosystems. DSi cycling is tightly linked to the hydrological cycle, which is affected by human alterations of the landscape. Development activities that increase impervious cover change watershed hydrology and may increase the discharge of DSi‐poor rainwater and decrease the discharge of DSi‐rich ground water into aquatic ecosystems, possibly shifting algal community composition toward less desirable assemblages. In this study, DSi loadings from two adjacent coastal watersheds with different percent impervious cover were compared during four rain and five nonrain events. Loadings in the more impervious watershed contained a significantly larger proportion of surface runoff than base flow (ground‐water discharge) and had lower [DSi] water during rain events than the less impervious watershed. Application of the Soil Conservation Service Curve Number (CN) method showed that the minimum rainfall height necessary to yield runoff was significantly lower for the more impervious watershed, implying that runoff volumes increase with impervious cover as well as the frequency of runoff‐yielding events. Empirical data collected during this study and estimates derived from the CN method suggest that impervious cover may be responsible for both short‐term DSi limitation during rain events as well as long‐term reduction of DSi inputs into aquatic ecosystems.     

爆破震动安全距离的优化计算

笔者针对爆破震动安全距离的典型计算公式,从参数入手,分析误差产生的原因,认为爆破震动安全距离计算产生误差主要原因有三:①K ,α的类比取值不客观;②现场爆破改变了地质条件;③试验法以点代面。笔者从改善K ,α取值的角度,提出一种较为合理的计算爆破震动安全距离的优化方案,即进行爆破现场监测,将监测数据及时参与K ,α值的计算。这样既避免K ,α的类比取值不客观,又反映出爆破对现场地质条件的改变;而且大量监测数据参与计算避免片面性。据此建立了爆破震动安全距离计算优化模型,并利用VisualBasic语言编写了程序,避免了大量的人工计算。将此模型应用于工程实际,得到了较好的效果     

SIMULATION OF FRESHWATER DISCHARGES FROM UNGAGED AREAS TO THE SEBASTIAN RIVER,FLORIDA1

ABSTRACT: Due to alterations in the natural drainage system over the past several decades and intensified agricultural practices, freshwater discharges to the Sebastian River, Florida, have increased substantially. As a result, salinity patterns in the Sebastian River and adjacent Indian River lagoon have been disrupted and the influx of nutrients has increased. Recently, the St. Johns River Water Management District has developed a 3‐D hydrodynamic and salinity model for the Sebastian River and adjacent Indian River to study the effects of freshwater inflows, and to set guidelines for management of future freshwater discharges. Freshwater inflows to the Sebastian River are part of the input data of the hydrodynamic model. Except for the downstream drainage areas, inflows are gaged, and the data were used for calibration of the hydrologic simulations. Collectively, the downstream ungaged areas constitute about 16 percent of the total drainage area. Because of the significant contribution to the total drainage area, reliable estimates of freshwater discharges from the ungaged areas to the Sebastian River are needed. This case study illustrates the development of a set of model parameters, reflecting the hydrologic and physiographic characteristics of the entire region. In this context region applies to the watersheds located in the coastal area along the Indian River from Titusville in the north to Vero Beach in the south. The parameter set was first tested on a number of gaged drainage basins in the region, and was then applied to the ungaged areas.