A closer look at BLEVE overpressure

The overpressure produced by the boiling liquid expanding vapor explosion (BLEVE) is still not well understood. Various methods have been published on the overpressure modeling in the far field. They mostly differ by the modeling of the expansion energy, used to scale the distance to the source where the overpressure needs to be calculated. But these methods usually include a experimentally fitted reduction factor, and are mostly overestimating the overpressures. Today there is a growing interest in modeling the BLEVE overpressure in the near field, for studying the blast effect on critical infrastructure such as bridges and buildings. This requires a much better understanding of the BLEVE blast. This paper goes deeper in the understanding of the physical phenomenon leading to the BLEVE blast wave generation and propagation. First, mid-scale BLEVE experiments in addition to new experimental data for near field blast from a small scale supercritical BLEVE are analyzed. And second, an analysis method of the shocks observed in the experiments is presented based on fundamental gas dynamics, and allows the elaboration of a new modeling approach for BLEVE overpressure, based on the calculation of the initial overpressure and radius of the blast.     

弹射起飞和拦阻着陆冲击试验方法探讨

目的研究舰载机机载装备弹射起飞和拦阻着陆冲击试验的工程实现方法。方法从GJB 150.18A—2009、MIL-STD-810F/G及其提供的实测数据出发,分析弹射起飞和拦阻着陆冲击载荷特征,对几种常用试验方法的工程实现进行探讨和比较。结果弹射起飞和拦阻着陆冲击具有瞬态、交变、低频、大位移、高速度等特征。阻尼正弦波方法的实施路径比较明确,复杂波形再现方法实施路径比较模糊且复杂,超长脉冲半正弦波方法具有多种局限性,前两种方法的速度、位移都较大。结论阻尼正弦波方法较复杂波形再现方法更容易实现,但两者都需要大位移、高速度的专用冲击试验设备和适当的波形处理技术,超长脉冲半正弦波方法在前面两种标准推荐方法能够实现时,不建议使用。     

温度、盐度、铜、氨对对虾仔虾(Penaues orientalis K)和光滑河兰蛤(Potamocorbula laevis)的影响

在室内模拟条件下,进行了热冲击及其与盐度、铜、氨联合对对虾仔虾和光滑河兰蛤的急性影响研究。结果表明,两种动物的起始致死温度(TL₅₀)和最高临界温度(CTM)随驯化温度的升高而增大;随盐度的降低,仔虾的耐高温能力明显降低,而兰蛤对盐度变化反应不明显;高温明显提高铜、氨对仔虾的毒性。也提高铜对兰蛤的毒性,但降低氨对兰蛤的毒性影响。仔虾对高温、低盐、铜离子及非离子氨反应敏感。     

低浓度渣油-水系乳化液的抑尘性能现场试验研究

本文介绍了作者用渣油－水系乳化液做路面抑尘剂在某矿露天坑３种不同类型路面进行的大规模工业性试验。现场测定结果表明：这种路面抑尘剂可以获得比较理想的防尘效果，长期使用该乳化液可取得显著的综合经济效益。     

基于TMS320F240 DSP的电网谐波抑制全数字化控制的研究

为治理电力系统谐波污染 ,提高电力系统运行的安全稳定性 ,笔者对混合式并联有源电力滤波系统的结构和工作原理进行了分析和研究。该系统由无源滤波器和小容量有源滤波器串联构成 ,与被补偿的谐波负载并联连接。基于TMS32 0F2 4 0DSP开发套件 ,设计数字控制器主程序和中断服务子程序。实验结果表明 ,采用TMS32 0F2 4 0DSP编程方便并直观 ,运算精度高 ,控制器参数调整方便 ,易于实现各种控制策略。研究成果对DSP在有源电力滤波系统中的应用有重要参考价值。     

极性基湿润剂与矿岩类粉尘颗粒的作用机理

根据矿岩类粉尘微颗粒的表面性质和极性基湿润剂的特性，应用分子热力学和表面物理化学理论探讨了湿润型抑尘剂与矿岩类粉尘之间的相互作用机理。矿岩类粉尘吸附水的本质是由于它们之间的相互吸引作用，是分子之间的短程相互作用力和长程作用力共同作用的结果。当矿岩类粉尘与水相碰撞时，只有当吸引力大于排斥力时，水分子才能牯附于矿岩类粉尘，表面张力和体系自由能足够小时，水才能湿润矿岩类粉尘。分析了湿润剂对水和矿岩类粉尘的表面改性的原理，它增加水和矿岩类粉尘之间的相互作用力，减小了界面表面张力和体系自由能，使矿岩粉尘被水湿润能自由地进行。     

Experimental and theoretical investigation of dry-water containing phosphoric acid for new fire suppressant

To overcome the shortcomings of phosphorus-containing compounds (PCCs, not widely used) in fire suppression, the dry water powder containing phosphoric acid was analyzed for a new fire suppressant (SiO₂-P). First, the fine conditions (solid-to-liquid ratio, stirring time and stirring speed) were determined to prepare the new powder. The particle size distributions and XPS of SiO₂-P powder were analyzed. The TG tests were conducted to study the decomposition of powder, and there was a major decomposition peak. Second, the extinguishing time of SiO₂-P powder was tested, which showed that the SiO₂-P powder containing phosphorus species could significantly improve the fire suppression ability. In addition, the kinetic parameters of powder decomposition reaction were determined by genetic algorithm based on TG results. Last, based on the decomposition products and kinetic parameters, the burning velocity and mass fraction of free radicals of CH₄/air flame with SiO₂-P powder addition were studied theoretically. The results indicated that SiO₂-P powder had great ability of reducing the burning velocity and scavenging free radicals. Furthermore, the suppression effects were analyzed, which indicated that the cooperation of H₂O and P suppression effect dominated the suppression mechanism and resulted in the good suppression efficiency.     

Understanding Interaction Effects of Climate Change and Fire Management on Bird Distributions through Combined Process and Habitat Models

Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes.     

高含固污泥厌氧消化中Fe/S及pH对原位抑硫效率影响及其交互作用

以城市污水处理厂高含固污泥为对象,分别进行了连续厌氧消化抑硫试验和消化污泥Fe(Ⅲ)投加抑硫试验,探讨不同Fe/S(摩尔比)对污泥厌氧消化中溶解态硫化物去除效率的影响以及Fe(Ⅲ)与pH的交互作用.结果表明,热水解污泥厌氧消化采用原位抑硫技术,在Fe/S(摩尔比)为7.75时沼气中H_2S含量可由170.4×10~(-6)降至14.09×10~(-6),无需进行后续处理;当pH为7.00~7.50、Fe/S为1~11时,pH为原位抑硫主要显著影响因子,提高消化池pH有利于降低Fe(Ⅲ)投加量;高含固污泥厌氧消化沼气满足H_2S利用标准时,所需最低Fe/S为7.0;当消化池pH低于7.30时,将无法通过调节Fe/S实现H_2S浓度达标排放.     

高碳氮负荷下同时脱氮除碳好氧颗粒污泥研究

在4 L反应器中,以补加葡萄糖和硫酸铵的猪场废水为基质,不接种活性污泥,加入粉末状活性炭对废水土著微生物进行预固定.通过批次进水并控制运行条件（逐渐提高COD、NH 4＋-N负荷、缩短沉降时间、提高曝气量）培养同时脱氮除碳好氧颗粒污泥,研究了该好氧颗粒污泥的脱氮除碳功能及对高碳氮负荷冲击的响应.结果表明,成熟好氧颗粒污泥为土黄色不规则球状,粒径为0.5～3.5 mm.COD和NH 4＋-N负荷分别在4.80～12.6 kg.（m3.d）-1和0.217～0.503 kg.（m3.d）-1时,好氧颗粒污泥对COD的去除率〉94%,对NH 4＋-N的去除率〉98%.当COD和NH 4＋-N负荷分别提高至15.70 kg.（m3.d）-1和0.723kg.（m3.d）-1并运行4 d后,反应器内絮体激增,颗粒沉降变差并开始破碎,NH 4＋-N去除率下降至81.6%.排出部分污泥并降低负荷继续运行,颗粒污泥的NH 4＋-N去除率可迅速恢复至98%以上.本研究培养的好氧颗粒污泥具有良好的同时脱氮除碳功能,可以耐受高COD和NH 4＋-N负荷的双重冲击.