Hybrid field network simulation of temperature in a building fire

A connecting platform between the field model and network model has been constructed, based on a multi functional building model. The field model is used to simulate the fire smoke in certain special compartments (the fire room and specific large space rooms), while the network model is used to simulate the uniform compartments. When combining the simulation results of the field model and network model as the interface boundary conditions for the each other, a hybrid field and network model is presented. The hybrid field network model can provide more detailed physical information of the fire smoke properties under a specific fire scenario for the specially confined compartments. In addition, the hybrid model can predict the fire smoke flow properties in the building accurately.     

Analysis of Yangtze River Water as a Potential Source for Developing a Water Source Heat Pump in Chongqing

Characteristics of smoke flow and fire spread in a patio space of a high-rise building were studied to investigate their influences on fire compartment and safety evacuation. Fire development model was established and fire scenarios were designed to simulate fire and smoke spread by CFD software numerically based on concepts of fire performance-based design in a high-rise building with double patio space, whose height are 74. 65 m and 55. 95 m, respectively. Simulation results show that in all fire scenarios, performance targets for safety evacuation for people in each floor was satisfied, if smoke was extracted naturally using the patio space. Hang walls mounted in corridors around the patio space prevent smoke flowing out smoothly, shorten the coming of the risk time and increase fire danger. Using chimney effect, it is preferred to adopt natural smoke exhaust method in a high rise building with patio space.     

Numerical Simulation for Fire Smoke Flow in a High-rise Building with Patio Space

Characteristics of smoke flow and fire spread in a patio space of a high-rise building were studied to investigate their influences on fire compartment and safety evacuation.Fire development model was established and fire scenarios were designed to simulate fire and smoke spread by CFD software numerically based on concepts of fire performance-based design in a high-rise building with double patio space,whose height are 74.65 m and 55.95 m,respectively.Simulation results show that in all fire scenarios,performance targets for safety evacuation for people in each floor was satisfied,if smoke was extracted naturally using the patio space.Hang walls mounted in corridors around the patio space prevent smoke flowing out smoothly,shorten the coming of the risk time and increase fire danger.Using chimney effect,it is preferred to adopt natural smoke exhaust method in a high-rise building with patio space.     

蠕变模型对约束钢梁抗火性能分析的影响

钢材在高温和荷载作用下产生明显蠕变变形,影响火灾中结构的变形和受力性能。现有的蠕变模型较多,但没有一个广泛适用的蠕变模型。不同的蠕变模型对钢结构抗火分析结果有很大影响。为了量化蠕变模型对约束钢梁抗火性能分析的影响,对5种常用的蠕变模型进行了对比分析。采用编写的约束钢梁计算程序,分别计算5种蠕变模型下约束钢梁的抗火性能并与试验数据进行对比。结果表明,采用Norton蠕变模型的计算结果与试验数据吻合最好。最后对影响约束钢梁抗火性能参数进行了研究,研究发现,Harmathy蠕变模型对约束梁抗火性能分析结果影响最大;不同蠕变模型对不同荷载比、约束刚度下的约束钢梁抗火性能影响程度均不同。     

Discussion on Disadvantages of the Current Water Supply Firing System Based on the Individual Building

By analyzing the problems and their reasons existed in the water firing prevention system, it is pointed out that the current Chinese firing prevention system is a partial and half-baked one, based solely on the individual building. Fire is an accident to a building, while it is a necessity to a city. Fire fighting is not only the responsibility of individual buildings, but also a part of disaster prevention system. The specialized management, power of fire fighting and salvation of the city nowadays should be reinforced. The responsibility of firing prevention system in a building is to put off the initial flame and prevent the fire extending within the right time, meanwhile to start the fire prevention and contingency measurements of the city.     

Experimental Analysis of Building Space Constructions on Hot smoke Flow in Residential Fire

Based on the characteristics of spatial structure of residential units, the effect of building space construction on temperature raise and hot smoke flow in residential fire was analyzed on building model with simulating multiple floors and rooms. The raise and distribution of temperature indoors were mainly tested under varied location of fire sources. And, the rule of smoke flow was discussed by using the law of temperature raise, indirectly. The results indicate that the mode of smoke flows is influenced by three spatial factors which include the form of junction terminal room construction; the height of down stand above the door and the relative locations of each room. The diffusion of hot smoke is prevented effectively by the down stand of the room; the temperature difference between indoor and outdoor should be higher than that of the room without down stand. When the open direction of door in non fire room is opposite to that of the door in fire room, there is much more hot smoke.     

A Preliminary Survey on Analysis Method of Building Structures Under Post-Earthquake Fire

Considering the impact of post-earthquake fire on building structures in structure design, an analysis method is proposed to analyze and simulate the response of building structures under post-earthquake fire. Based on the seismic response and thermal stress analysis, this method considers the structure seismic damage through a simplified seismic damage model, and the simulation of the response of building structures under post-earthquake fire was reached by linking the heat transfer analysis and thermal stress analysis to the results of seismic damage. A single-storey concrete frame and a multi-story concrete frame were analyzed with this method and compared with experimental results of the same concrete frame under fire without seismic damage. It is shown that the collapse mode may change for seismic damaged structures and the fire resistance decreases with the increasing of seismic damage degree.     

Refined Probabilistic Model of Resistance of RC Eccentric Compression Members

The probabilistic model of resistance in the current unified standard for reliability design is imprecise for RC members subjected to eccentric compression. The reason is that it lacks full considerations of influences of varying eccentricities. An improved probabilistic model of resistance with different eccentricities and reinforcement ratios is obtained by using the Monte Carlo sampling method and the current probabilistic models of all resistant factors. The results indicate that it is accurate to fit the probabilistic distribution of resistance with normal distribution. Given that, the applicability of the improved model is analyzed for reliability analysis of RC members subjected to eccentric compression with random eccentricities. It shows that when the design value of eccentricity is close to or larger than the eccentricity producing balanced failure, there would be large errors in reliability analysis if the probabilistic model of resistance given in the current reliability unified standard is used. However, it is accurate when using the proposed probabilistic model. The results also show that the design of RC members subjected to large eccentric compression is unsafe based on the current reliability unified standard because it lacks full considerations of effects that the resistance decreases as eccentricity increases.     

Three-dimensional Large Eddy Simulation of Smoke Flow during Indoor Fire

Indoor fires are quite dangerous,claiming many casualties and resulting in great property loss.Using Computational Fluid Dynamics(CFD),a three-dimensional large eddy simulation model of smoke flow is set up.Through the simulation of smoke flow,the theoretical basis is provided for controlling a fire in multiple rooms,thereby saving people.The results of simulation show that high temperatures and thick smoke exist near the fire,and the probability of combusting other tinder will increase.Moreover,there are close relationships between fire and ventilation.The latter can lower the average temperature and speed up the spread of smoke flow and toxic gases,providing conditions for the further development of indoor fire.Moreover,from both the simulated calculation and physical measurement,it is shown that indoor fires and their temperature distribution and smoke concentration are influenced by the fire power and the room size.The results from calculation and measurement are quite consistent.     

数量化模型估算观赏植物需冷量研究进展

植物在抵抗和适应不良环境时会产生生长缓慢或暂时停顿的休眠现象,打破休眠时所需的有效低温时数称为植物的需冷量。本研究综述了不同需冷量模型并分析了应用情况及效果。Utah模型是目前使用频率较高且效果较好的估算模型,动力学模型是理论最完善且适用范围最广的估算模型,但仍未推广应用,尤其是国内鲜有报道。需冷量估算模型研究对象主要为休眠芽,对其他休眠器官（球根、种子等）的需冷量研究还不多。与果树等其他园艺作物相比,目前将冷量估算模型应用于观赏植物的研究较少,涉及到植物种类和休眠器官类型都较少。需冷量模型与低温小时数相比能更准确计量及预测解除休眠过程对低温的需求,应用于观赏植物品种区域规划、引种有更好的前景。同时,继续探索需冷量累积的过程中相关的生物学机制,优化需冷量模型使其在不同气候类型中的应用具有通用型是未来研究需要着力解决的问题。     

发展复合食品添加剂有利于安全高效地实施GB2760

GB2760是一部保证食品添加剂安全使用和保障食品安全的国家强制实施的标准。复合食品添加剂的发展,推动了我国食品产业的健康发展及相关法规的进步与完善,也为GB2760添加了安全和高效的复合新元素。发展复合食品添加剂,是正确实施GB2760安全高效的科学方法之一。市场呼唤复合食品添加剂的发展,卫生部就复合食品添加剂通用标准,于2010年6月发布了征求意见稿。使用复合食品添加剂已成为不可阻挡的潮流。发展复合食品添加剂,有利于安全高效地实施GB2760,以保障食品安全。     

基于人行为影响的住区建筑多主体集成能耗模型

在城市建筑节能研究中,政府常常依赖城市能源与碳排放模型工具制定并评估节能策略。而当前的城市建筑能耗模型受限于开发技术等因素,尚存在诸多不足,例如,考虑人行为对建筑能耗的影响,建立行为、日常活动及与环境相关的综合能耗模型。关于此类模型合理的数学形式、参数选择的方法以及不同行为的模拟方式等问题还尚待进一步研究。采用多主体（Multi-Agent）建模技术,设计集成建筑能耗模型,以住区中的居民作为模型中活动的主体,模拟使用者行为习惯、活动对建筑能耗的影响;采用ISO 13790标准模拟建筑的供热和降温需求,并在集成环境中设计统一的描述框架,以相对独立的环境模拟、行为模拟模块形式进行交互,实现热环境模拟和基于主体活动的设备能耗模拟的有机结合。研究表明,住区居民的用能行为是影响城市建筑能耗密度变化的重要因素,实现对住区主体行为特征的引导是实现城市建筑节能目标的有效途径。     

北京市4种叶类蔬菜主要供应链模式损耗率的研究

针对叶类蔬菜采后损耗严重的问题,对北京市4 种主要叶类蔬菜（生菜、芹菜、油菜、菠菜）不同供应链关键节点的损耗率情况进行详细研究。通过对北京市8 个区县23 个大型加工企业及合作社、叶菜生产基地进行实地调研。研究确定了目前北京市叶类蔬菜4 种供应链模式,即农超对接模式、加工模式、散户-农贸市场模式、超市自有品牌模式,及其关键节点的叶菜损耗率。4 种主要供应链模式中,农超对接模式平均损耗率最高,可达36.05%;其次为超市自有品牌模式,平均损耗率为32.64%;散户-农贸市场模式的平均损耗率最低,仅为24.70%。4 种供应链模式生菜平均损耗率均为最高,最高可达45.81%;其次是菠菜,最高可达39.95%;油菜平均损耗率最低,仅为16.58%。此外,规定了叶菜验收标准,制定了损耗率计算公式;并比较了4种主要供应链模式及4种主要叶菜间的损耗率差异。研究对降低叶类蔬菜采后损耗率,满足消费者对叶类蔬菜新鲜度的要求具有十分重要的意义。     

基于生态足迹的城市生态安全评价 -以宝鸡市为例

摘要：【研究目的】：分析宝鸡市生态安全与社会经济发展存在的问题及对策,以期为相关决策部门提供参考依据;【方法】以生态足迹分析方法为基础,利用生态压力指数对宝鸡市1996-2005年的生态安全进行初步研究和评价;【结果】宝鸡市的生态压力指数从1996年的1.453041逐年增至2005年的4.452437,增加了3.06倍,生态足迹与生态承载力之间的矛盾正在加剧,生态系统进一步遭到破坏,人地关系紧张,现有的发展模式是不可持续的,生态环境由较不安全变为极不安全状态;【结论】评价结果显示,宝鸡市近十年来的自然生态由较不安全状态变为极不安全状态,且生态压力指数呈上升趋势。     

Simulation of Evacuating Buffer in High-rise Building Fires

Buffer zone set between aisle and anteroom is proposed to improve the traditional mode of pressurizes mechanic smoke extraction. Fire Dynamic Simulation is used to simulate the model of high-rise fire. Eight models are set and analyzed, in which the smoke temperature distribution and concentration distribution are compared, and the best parameters is worked out. The result shows, when exhaust smoke volume is constant, the velocity of air curtain is as low as possible; when the volume of air curtain is constant, the smoke volume is as low as better. Based on the comparison, it is found that the smoke removal efficiency of mode 4 is the best one, which is about 74.06%. The evacuating buffer not only can let smoke out timely, but also can guarantee safe personnel evacuation.     

A Study on Application of Air Pollution Diagnosis and Predict Model to Chongqing Urban

This paper presents results of a research project "The prediction of the Fire Smoke Flow Properties in the Building", supported by the National Natural Science Fund. The numerical model of fire smoke flow in the building and its applied computer software are outlined. The experimental results obtained from full-scale fire test are compared with the results of numerical prediction using computer software.     

Safe Monitor and Analysis of Deep Excavation with Total Station

During the process of deep excavation digging,it is an important task to monitor the excavation and affected building to make sure the spot's safety and go on wheels with the schedule.In this article some causation of slip and the calculation methods of freely setting station are first discussed,and then combined with the theory of polar coordinates a forecast method through distortion course curve analysis is put forward.The method with its low cost and speediness,can satisfy the precision requirement and provide the base data for safe evaluating and designing.     

Thermal Radiation Effects on Smoke-flow in Atrium Fires

The field models for smoke flow in atrium, takings into account strong buoyancy, turbulence, radiation exchange and wall heat losses are developed according to the characteristics of the atrium fire. Realistic combustion processes in the burning fuel have not been included. A six-flux radiation model is included in a general mathematical model for fires, which are taking as a volumetric heat source, It is applied to the predictions of fire smoke development in a small-scale atrium. In order to avoid complicated radiation exchange models, radiation heat loss effects are combined to the wall heat loss. A General-purpose compute program PHOENICS has been developed to meet this need. Results of numerical calculations based on the field model are compared with test data for a fire in the small-scale atrium test facility. The resullts indicate that radiation transfer has the minor effects, due to the relatively low temperatures encountered. The method that the effect of radiation is included in the calculation of wall heat transfer losses by using maximum heat transfer coefficient is feasible. The field model used in the present study is not good enough, which a turbulent combustion sub-model must be included.     

Fire Safety Assessment on Large Space Building

Based on the characteristics of large space buildings, a fire safety assessment index system was founded. The calculation methods for the weight of evaluation indexes and fuzzy calculation were described. A space building was evaluated using this model.