Removal of lead from aqueous solution by hydroxyapatite/manganese dioxide composite

A novel composite adsorbent, hydroxyapatite/manganese dioxide (HAp/MnO₂), has been developed for the purpose of removing lead ions from aqueous solutions. The combination of HAp with MnO₂ is meant to increase its adsorption capacity. Various factors that may affect the adsorption efficiency, including solution pH, coexistent substances such as humic acid and competing cations (Ca²⁺, Mg²⁺), initial solute concentration, and the duration of the reaction, have been investigated. Using this composite adsorbent, solution pH and coexistent calcium or magnesium cations were found to have no significant influence on the removal of lead ions under the experimental conditions. The adsorption equilibrium was described well by the Langmuir isotherm model, and the calculated maximum adsorption capacity was 769 mg·g⁻¹. The sorption processes obeyed the pseudo-second-order kinetics model. The experimental results indicate that HAp/MnO₂ composite may be an effective adsorbent for the removal of lead ions from aqueous solutions.     

能见度对个体疏散速度及路径选择的影响研

为提供火灾条件下人员疏散基础数据,基于4层教学楼疏散平台,开展了不同能见度环境下个体疏散实验,研究了能见度对人员疏散速度及路径选择的影响。研究结果表明:正常能见度条件下,人员的平均疏散速度为（2.37±0.23）m/s,个体间疏散速度差异明显,随着能见度降低,人员的平均疏散速度呈现均匀下降趋势,个体疏散速度最终均趋近于（0.36±0.10）m/s;人员水平疏散速度显著大于下行疏散速度,且水平疏散速度受能见度影响更大;当能见度较高时,人员以视觉作为寻路方式,倾向于选择自己最熟悉的路线进行疏散;能见度较低时,人员主要依靠触觉作为寻路方式,即借助墙或楼梯扶手进行疏散,此时人员的路径选择受到周围围挡物的共同作用。     

双出口疏散吸引区域模型建立与模拟分析

为研究建筑体内人员疏散的出口选择行为,提出基于元胞自动机的人员疏散模型。以学校常见的双出口教室为例进行研究,建立双出口疏散吸引区域模型,得出人员密度较低和较高时疏散吸引区域边界的函数表达式,指出人员密度较高时,边界函数基本满足边界到出口距离的平方之比等于出口的宽度之比;通过对出口宽度、人员数量和出口位置等参量进行仿真分析,充分验证了提出的双出口疏散吸引区域模型的合理性;研究结果有助于合理分配疏散人员,充分发挥建筑疏散的潜在能力。     

高层建筑火灾扑救的潜在危险及预防措施

摘要近30年来,商层建筑发展十分迅速,高层建筑火灾也随之开始频繁发生,在扑救火灾过程中,消防队员常常伤亡,就高层建筑灭火过程中的潜在危险进行分析并提出相应的预防措施。     

机器振动对厂房结构影响的检测及分析

应用振动测试方法,对机器振动对厂房结构的影响进行检测及分析.检测结果分析表明,在机器振动产生的动荷载作用下,厂房结构振动响应不满足工程结构安全要求.分析了其原因并提出应采取的有效措施,为对厂房结构进行安全评价提供了可靠的科学依据.     

多层建筑火灾烟气运动的模拟实验研究

火灾烟气是导致多层建筑火灾中人员伤亡的主要原因。结合多层建筑的实际情况 ,利用缩尺度模型实验楼模拟多层建筑火灾的典型情况 ,对其火灾烟气自火源产生后的运动特性进行实验研究。结果表明 ,烟气沿程由于热交换温度不断降低 ,会迅速达到顶部楼层并立即沉降 ,而且不同工况条件下所包含的有毒成分浓度随着火源温度的升高而上升。实验结果的分析能够较好地符合实际火灾的一些典型调查结果。     

Guatemala: violence in peacetime--a critical analysis of the armed conflict and the peace process

The recent history of Guatemala is interpreted here using an interdisciplinary approach inspired by recent development and conflict studies. The author reflects on his experience in peace-building activities and uses a combination of primary and secondary sources to present the Guatemalan war as a complex political emergency. The first part (a methodological introduction) proposes an analytical framework, taking into account both the root causes and the different functions of violence, in order to achieve a better understanding of contemporary conflicts. In the second and central part of the article, the integrated framework is applied to Guatemala, trying to understand causes and functions of war and negotiation and underlining the existence of structural obstacles to a lasting peace. The conclusions are dedicated to policy implications: if the signing of peace accords represents only a step towards negative peace, the condition for a lasting peace is a strategy for reconciliation and development based on social participation and social justice.     

Building the Capacity of Grassroots Conservation Organizations to Conduct Participatory Evaluation

Stakeholder participation has become a key factor in the success of grassroots conservation and natural resource management programs. Yet the majority of program evaluations are conducted by external consultants for the purposes of accountability, rather than program improvement. Too often, systematic evaluations of conservation programs are not conducted at all. The objective of this study was to build the capacity of a grassroots conservation organization to conduct participatory evaluation, involving project stakeholders in the design, implementation, and use of evaluation. The study applied a conceptual model for participatory evaluation to the Wildlife Clubs of Kenya (WCK), the largest grassroots conservation program for youth in Africa, involving more than one million youth since 1968. Seven trainings in participatory evaluation were conducted with WCK staff, teachers, and community members. The 120 participants, representing nine WCK regions with 800 clubs, showed a significant increase in attitudes and knowledge regarding evaluation, as reflected by mean test scores before and after training. To institutionalize evaluation at WCK, existing organizational practices were assessed and used as a foundation for developing an evaluation system. Based on club competitions, a new evaluation initiative was launched called the WCK Incentive Program. Participants in all seven workshops identified indicators and sources of evidence for this evaluation system, which now serves as a basis for rewarding outstanding performance in WCK. This study revealed the importance of incentives for evaluation, the need to build on existing structures to promote organizational learning, and the necessity for the conservation community to commit resources to capacity building in participatory evaluation.     

大型建筑内部火灾温度场的数值模拟

利用CFD技术对在建筑火灾情况下，温度场的变化趋势进行数值模拟。针对大型建筑内部火灾温度场数值模拟特点，考虑建筑火灾中温度、烟气扩散以及尺度较大等因素，通过小尺度数值实验，在模型的效率性和准确性方面对不同模型加以比较、分析，选取带浮力修正的模型。同时，选用国际通用CFD计算软件FLUENT6．1针对某大型建筑内部火灾温度场进行数值模拟。并结合区域模拟软件CFAST对结果进行比较分析。表明CFD场模拟软件FLUENT6．1具有较高的可靠性，可针对大型工程项目进行分析模拟。     

Dangerous good transportation by road: from risk analysis to emergency planning

Despite the relative recent move towards inherent safe materials, the relentless drive of consumerism requires increased quantities of dangerous goods to be manufactured, transported, stored and used year on year. The safety and effectiveness of road transport systems is to be considered a strategic goal in particular in those countries, like Italy, in which 80% of goods are transported by this means. In this paper, we face the risk from dangerous good transport by presenting a site-oriented framework for risk assessment and developing a theoretical approach for emergency planning and optimisation. In the first step, we collected field data on a pilot highway and developed a database useful to allow a realistic evaluation of the accident frequency on a given route, by means of multivariate statistical analysis. To this end, we considered both inherent factors (such as tunnels, bend radii, height gradient, slope etc), meteorological factors, and traffic factors (traffic frequency of tank truck, dangerous good truck etc.) suitable to modify the standard national accident frequency. By applying the results to a pilot area, referring to flammable and explosive scenarios, we performed a risk assessment sensitive to route features and population exposed. The results show that the risk associated to the transport of hazardous materials, in some highway stretches, can be at the boundary of the acceptability level of risk set down by the well known F/N curves established in the Netherlands. On this basis, in the subsequent step, we developed a theoretical approach, based on the graph theory, to plan optimal emergency actions. The effectiveness of an emergency planning can normally be evaluated in term of system quickness and reliability. As a case study, we applied the developed approach to identify optimal consistency and localisation in the pilot area of ‘prompt action vehicles’, properly equipped, quick to move and ready for every eventuality. Applying this method results in an unambiguous and consistent selection criterion that allows reduction of intervention time, in connection with technical and economic optimisation of emergency equipment.