闽南红砖大厝庭院形态对屋面风压与风场的影响研究

基于ANSYS Fluent软件选用RNG k-ε湍流模型,以闽南红砖大厝民居为对象,通过数值计算、分组对比分析庭院与厝埕的进深对风场及屋面风压分布的影响并探讨利于抗风的建筑形式。研究表明:①随院落宽度的增加屋面最大平均风压系数绝对值呈现显著地降低又升高,最大降低21.2%;庭院宽度与进深的比例为1.5时屋面最大平均风压系数和整体平均风压系数绝对值最小,利于防风。②随院落进深的增加,屋面最大平均风压系数绝对值呈现显著地降低又升高,最大降低26.0%,庭院宽度与进深的比例为0.67时屋面最大平均风压系数和整体平均风压系数绝对值最小,利于防风。③有厝埕的屋面最大平均风压系数绝对值、整体平均风压系数绝对值与无厝埕相比均显著下降,最大平均风压系数绝对值降低了48.7%;随着厝埕进深的减小,除少量测点外,平均风压系数绝对值降低,降低最大幅度为26%。     

湖区桥塔塔顶表面风压的数值模拟

以洞庭湖大桥桥塔(主塔)为研究对象,基于Fluent软件平台,模拟了主塔塔顶表面的风压分布。采用3种不同的湍流模型对主塔塔顶进行数值模拟,并将模拟结果与实测试验结果进行了对比。选取合理的湍流模型;并探讨了不同风速及不同风向角对主塔塔顶表面风压分布的影响。结果表明,3种模型模拟的结果均与实测试验结果变化趋势一致,而Realizable k-ε模型的模拟结果更接近于实测试验结果;不同风速对主塔塔顶迎风面及侧面风压系数影响较小,而对其背风面风压系数有较明显影响;不同风向角对主塔塔顶风压系数影响显著,尤其是对其拐角处。研究结论可供湖区复杂高耸结构的抗风设计参考。     

定日镜的风压分布与脉动特性

定日镜结构的形体特殊,不同于普通的建筑结构.采用表面测压技术对定日镜模型进行了三维风荷载风洞试验,得到了各测点风向角0°～180°范围内,竖向角为0°～90°情况下,镜面平均风压和脉动风压的分布,重点探讨了镜面脉动风压特性.研究结果表明脉动风荷载功率谱变化受湍流风速和旋涡脱落的影响,并与斯托哈罗数有关;镜面正反两侧脉动风压主要呈正相关特性,在顺风向情况下相关系数较小,横风向情况下相关系数较大;风向角及竖向转角较小时,脉动风压更好地符合高斯分布.     

带不同洞口低矮房屋屋面风压的数值模拟

为研究开洞低矮房屋在台风环境下的破坏机理,基于ANSYS软件,采用SST k-ω湍流模型对体型比为1.5∶1∶1的封闭、单一洞口及两个洞口的低矮房屋模型的屋面风压分布及变化规律进行数值模拟研究,研究结果与同体型比的实测房屋及风洞试验结果对比表明:数值模拟结果与实测及风洞结果基本吻合,验证了SST k-ω湍流模型研究低矮房屋表面风压的可靠性;两洞口的屋面平均净风压系数与封闭房屋比较接近,单一洞口的位置对平均内风压系数的影响较大,其中迎风面出现单一洞口时,屋面净风压系数绝对值最大,在台风作用下最容易破坏。结果可为国内低矮房屋设计提供有价值的参考。     

基于数值风场的高层建筑对临近低层建筑群影响分析

针对高层建筑对低层建筑的风压、风速分布的影响问题,选用标准k-ε湍流模型,应用CFD数值方法模拟高层建筑影响下的低层建筑群的风场,侧重模拟分析了高层建筑的位置布局改变对低层建筑群风速及风压场的影响。分析结果表明:高层建筑对临近低层建筑群风场的影响显著,高层建筑的位置对低层建筑群风环境的影响较大。     

阶梯型大跨屋盖结构风荷载数值模拟研究

以某阶梯型体育馆为研究对象,基于CFD数值模拟方法,利用RNGκ-ε湍流模型对阶梯型大跨屋盖风荷载进行了研究,并与风洞试验结果进行对比分析,得出阶梯型大跨屋盖结构表面的风压分布及变化规律,为此类复杂体型的大跨结构抗风研究提供依据。结果表明:1CFD数值模拟技术可用于实际结构风荷载的分析研究;2阶梯型屋盖高度差对屋盖表面风压系数有较大影响,高度差较小一侧,屋盖迎风面分块区域的平均风压系数呈负压,高度差较大一侧,屋盖迎风面分块区域的平均风压系数为正压;3此类阶梯型大跨结构屋面风压分布主要以吸力为主;4阶梯型屋盖屋檐处的风压系数较转角凹处小,需对风压系数较高的位置做好预防措施。     

低矮建筑平均风压试验研究

通过一系列不同外形尺寸的单跨双坡低矮建筑刚性模型风洞测压试验,分析了不同风向角情况下结构表面的平均风压系数分布规律,重点考察了建筑结构外形参数和风场条件对低矮建筑主体承重结构风压系数的影响.     

福建沿海历史街区风荷载特性数值模拟与风险防控方法

通过ANSYS Fluent软件选用RNG k-ε湍流模型,以福建沿海历史街区为对象,数值计算分析街道形态与路网形式对极值风压系数分布的影响并探讨风灾防控的策略。研究表明:单一街道在全风向下高宽比(1.33)产生爬越流时极值负压系数绝对值较大,最大负压系数绝对值产生于风向与街道垂直且高宽比最大(1.33)的条件下;随风向由垂直于街道变为平行,多条街道相交与单一街道风压系数变化一致:整体的正、负压系数绝对值和范围均大幅度降低,单一街道、同一高宽比的极值负压系数绝对值最大降低64.74%,平均降低了43.93%。对三坊七巷与和平路历史街区造成风致破坏的最重要因素是临近历史街区的高层建筑带来的极值正压与负压系数,其次为开敞空间与街区道路走向。极值负压系数绝对值在建筑间距/高度3.5～5.8时成正相关,拟合曲线为抛物线,在建筑间距/高度大于5.8时极值负压系数绝对值均趋于稳定值。当风向与方格路网垂直时,高密度低矮建筑的风荷载极值与建筑所在的道路走向(平行或垂直)不相关。历史街区的风灾防控可从绿化配置和建设控制地带建筑优化两方面实现。     

基于谱修正方法的非高斯风场模拟

为克服基于H erm ite谱修正方法的缺点,减少该方法中计算H erm ite多项式系数所需耗费的大量机时,提出了一种模拟非高斯风压场的新方法,采用非高斯累积分布函数(CDF)映射技术来代替基于H erm ite的概率密度函数(PDF)修正。选择任意边缘PDF模型作为概率目标模型,采用目标功率谱密度(PSD)作为样本函数,通过迭代修正该样本函数,使其收敛于目标概率密度函数和目标功率谱密度。将该方法应用于实际结构的非高斯风场模拟,模拟结果与目标谱符合良好,表明本文方法模拟非高斯风场具有较高的精确度和计算效率。     

开洞口索穹顶结构的风压特性研究

基于CFD(计算流体动力学)方法研究开洞口索穹顶结构的风压特性。在不同风速和风向角作用下,对索穹顶结构在不同位置上单一开洞、以及结构底面、顶部同时开多个不同形式洞口的平均风压分布进行了系统研究,通过对模拟结果的分析,得到了不同开洞形式的索穹顶结构的平均风压系数分布规律。结果表明,开洞穹顶结构的风压特性与开洞形式、位置和风向等有着重要关联。研究成果为开洞索穹顶结构的抗风设计提供了可靠的理论参考。     

Risk communication in emergency response to a simulated extreme flood

Risk communication in flood incident management can be improved through developing hydrometeorological and engineering models used as tools for communicating risk between scientists and emergency management professionals. A range of such models and tools was evaluated by participating flood emergency managers during a 4-day, real-time simulation of an extreme event in the Thamesmead area in the Thames estuary close to London, England. Emergency managers have different communication needs and value new tools differently, but the indications are that a range of new tools could be beneficial in flood incident management. Provided they are communicated large model uncertainties are not necessarily unwelcome among flood emergency managers. Even so they are cautious about sharing the ownership of weather and flood modelling uncertainties.     

Cholera in Sudan: An account of an epidemic in a refugee camp in eastern Sudan, May-June 1985

In 1985 cholera has been a serious problem in the horn of Africa, particularly affecting the many famine victims and refugees in that region. In this paper the history of cholera in Africa is briefly summarized, as is the background to the current refugee situation in eastern Sudan. A cholera epidemic involving 1,175 cases in two adjacent refugee camps in eastern Sudan is described. In this epidemic there were thirteen inpatient deaths and thirty-eight known home deaths from cholera. The management of the epidemic is described in detail. Overall an average of 8 1. of intravenous fluid was used per case, a higher figure than was anticipated, probably because of the unexpected degree of vomiting and the shortage of trained nursing staff.
The relationship between cholera and malnutrition is explored and hypochlorhydria is suggested as the main reason for the increased susceptibility to cholera among malnourished populations. It was observed that severely malnourished adults and children appeared to nave less severe diarrhoea with their cholera, presumably because of reduced mucosal surface area and poor enterocyte function. Finally possible means of aborting cholera epidemics are discussed.     

Risk and the neoliberal state: why post-Mitch lessons didn't reduce El Salvador's earthquake losses

Although El Salvador suffered light losses from Hurricane Mitch in 1998, it benefited from the increased international aid and encouragement for advance planning, especially mitigation and prevention interventions. Thus, one would have supposed, El Salvador would have been in a very advantageous position, able more easily than its economically crippled neighbours, Honduras and Nicaragua, to implement the 'lessons of Mitch'. A review of the recovery plan tabled by the El Salvador government following the earthquakes of early 2001 shows that despite the rhetoric in favour of 'learning the lessons of Mitch', very little mitigation and prevention had actually been put in place between the hurricane (1998) and the earthquakes (2001). The recovery plan is analysed in terms of the degree to which it deals with root causes of disaster vulnerability, namely, the economic and political marginality of much of the population and environmental degradation. An explanation for the failure to implement mitigation and preventive actions is traced to the adherence by the government of El Salvador to an extreme form of neoliberal, free market ideology, and the deep fissures and mistrust in a country that follow a long and bloody civil war.     

A retrospective statistical review of deaths owing to migration through the southeasternmost land borders of the European Union,Greece 2000–14

The land borders of Evros, Greece, have been a common entry point for undocumented migrants on their way to Europe through Turkey. Adverse conditions, however, have resulted in many human casualties over the years. On the Greek side, 334 cadavers were retrieved between 2000 and 2014. This study provides a detailed forensic account of the humanitarian disaster in Evros to create an official scientific record of the situation. It showcases the gravity of the global issue of migration relating to health and mortality, and encourages communication and continual improvement of the approach and patterns of practices surrounding the subject. A retrospective statistical research review was conducted of border‐related fatalities between 2000 and 2014, assessing the age and gender of victims, the cause of death, the location of bodies, identification rates, and country of origin. Age ranged generally from 24 to 29 years, but infants and children were among the deceased.     

Where the exception confirms the rule: The cyclones of 1982-1983 in French Polynesia

The island groups of French Polynesia, which had not experienced any really devastating cyclones since the beginning of the century, were hard hit several times between December 1982 and April 1983. This paper reviews the cost of damage from these cyclones and shows how lowered public awareness of the hazard in a low-frequency area combined with the special economic conditions prevailing in the Territory to make the total cost much higher than it need have been. Ways and means of rehabilitation are analyzed. The development of the thermal imbalance in the Pacific, which appears to have triggered this series of natural disasters, only seemingly exceptional, is briefly discussed.     

Epidemiology of tornado destruction in rural northern Bangladesh: risk factors for death and injury

The epidemiology of tornado-related disasters in the developing world is poorly understood. An August 2005 post-tornado cohort study in rural Bangladesh identified elevated levels of death and injury among the elderly (≥ 60 years of age) (adjusted odds ratio (AOR) = 8.9 (95 per cent confidence interval (CI): 3.9-20.2) and AOR = 1.6 (95 per cent CI: 1.4-1.8), respectively), as compared to 15-24 year-olds, and among those outdoors versus indoors during the tornado (AOR = 10.4 (95 per cent CI: 5.5-19.9) and AOR = 6.6 (95 per cent CI: 5.8-7.5), respectively). Females were 1.24 times (95 per cent CI: 1.15-1.33) more likely to be injured than males. Elevated risk of injury was significantly associated with structural damage to the house and tin construction materials. Seeking treatment was protective against death among the injured, odds ratio = 0.08 (95 per cent CI: 0.03-0.21). Further research is needed to develop injury prevention strategies and to address disparities in risk between age groups and between men and women.     

Risk communication in emergency response to a simulated extreme flood

Risk communication in flood incident management can be improved through developing hydrometeorological and engineering models used as tools for communicating risk between scientists and emergency management professionals. A range of such models and tools was evaluated by participating flood emergency managers during a 4-day, real-time simulation of an extreme event in the Thamesmead area in the Thames estuary close to London, England. Emergency managers have different communication needs and value new tools differently, but the indications are that a range of new tools could be beneficial in flood incident management. Provided they are communicated large model uncertainties are not necessarily unwelcome among flood emergency managers. Even so they are cautious about sharing the ownership of weather and flood modelling uncertainties.     

Vested Interest theory and disaster preparedness

Three studies were designed to extend a combination of vested interest theory (VI) and the extended parallel process model of fear appeals (EPPM) to provide formative research for creating more effective disaster preparedness social action campaigns. The aim was to develop an effective VI scale for assessing individual awareness and ‘vestedness’ relevant to disaster preparedness. Typical preparedness behaviours are discussed with emphasis on earthquakes and tornados in particular. Brief overviews of VI and the EPPM are offered, and findings are presented from three studies (one dealing with earthquakes, and two with tornados) conducted to determine the factor structure of the key VI components involved, and to develop and test subscales derived from the two theories. The paper finishes with a discussion of future research needs and suggestions on how the new subscales may be applied in the design and execution of more effective disaster preparedness campaigns.     

Complexity,continuity and change: livelihood resilience in the Darfur region of Sudan

Darfur farming and pastoralist livelihoods are both adaptations to the environmental variability that characterises the region. This article describes this adaptation and the longer‐term transformation of these specialised livelihoods from the perspective of local communities. Over several decades farmers and herders have experienced a continuous stream of climate, conflict and other shocks, which, combined with wider processes of change, have transformed livelihoods and undermined livelihood institutions. Their well‐rehearsed specialist strategies are now combined with new strategies to cope. These responses help people get by in the short term but risk antagonising not only their specialist strategies but also those of others. A combination of factors has undermined the former integration between farming and pastoralism and their livelihood institutions. Efforts to build resilience in similar contexts must take a long‐term view of livelihood adaptation as a specialisation, and consider the implications of new strategies for the continuity and integration of livelihood specialisations.