砖厂废气排放对橡胶树生长及生理生化特性的影响

为了探明砖厂废气排放对橡胶树生长及生理生化特性的影响,以砖厂东南风下风区距离砖厂200 m、400 m、600 m处,2005年种植的‘云研77-2’橡胶树为研究对象,对植株茎粗以及叶片的生理生化指标（可溶性糖、蔗糖、可溶性蛋白、叶绿素a、叶绿素b、保护酶、丙二醛、超氧阴离子自由基、脯氨酸、含水率及相对电导率等）进行测量测定。结果表明,3个距离间橡胶树的茎粗呈200 m<400 m<600 m的趋势,且差异达极显著水平(P<0.01),说明砖厂废气排放对附近橡胶树生长有严重影响,影响程度依距离远近而有所不同。砖厂废气污染对橡胶树生理生化特性的影响表现为：一方面,导致叶片叶绿素含量降低,光合作用减弱,光合营养物质即可溶性糖、蔗糖含量降低,影响植株生长;另一方面,超氧化阴离子自由基陡增,导致保护酶系统的启动,过氧化物酶、超氧化物歧化酶、过氧化氢酶活性提高,消除或降低超氧阴离子自由基对橡胶树叶片的伤害。废气污染也导致丙二醛和脯氨酸含量升高,起到调节细胞渗透势,平衡电导率的作用。总之,橡胶树通过启动自身保护系统使之能够对废气污染伤害具有一定的抵御忍耐能力,但砖厂废气排放仍会对橡胶树生长和正常生理过程产生严重影响,导致其光合作用降低,光合产物减少,造成植株矮生细长。     

木材干燥室集中换气时进排气孔气流的均匀性模拟

为解决木材干燥室强制集中换气装置进排气道孔口气流的均匀性问题,采用理论分析和Fluent数值模拟方法,对进排气道的进排孔口气流流速、流量等进行数值模拟分析和计算,得到了满足生产实际要求的孔口半径和分布。结果表明：进气道各孔口的质量流量差小于5．1％,排气道各孔口的质量流量差小于7．3％,二者均小于质量流量偏差（10％）...     

铈基燃油催化剂改善柴油机颗粒物捕集器再生效果

颗粒捕集器(diesel Particulate filter,DPF)是目前公认的最有效的柴油机排气颗粒物后处理装置,为了去除DPF内部沉积颗粒,实现DPF再生,采用提高排气温度或催化燃烧的方法来促进颗粒物燃烧。该文采用环烷酸铈溶剂作为燃油催化再生添加剂(fuel borne catalyst,FBC),对柴油机DPF的再生平衡温度、压降特性和燃烧灰烬等进行试验研究。试验结果表明:DPF再生平衡温度因FBC的催化作用从500℃以上下降到约450℃,从而增加了颗粒捕集器的颗粒储备能力,并能够有效再生;柴油机燃油消耗率随着排气背压的增加而上升;燃用FBC测试燃油时DPF前后压差较纯柴油上升缓慢,其达到排气背压再生阀值的周期变长;同时,随再生次数的增多,再生后DPF的前后压差呈线性增加,捕集效率却逐渐提高。该文采用燃油添加剂可以明显降低颗粒的着火点。结合电加热装置,可有效提高DPF的再生效果,有效过滤柴油车尾气中的颗粒物,对柴油车尾气净化及环境保护具有十分重要的意义。     

Displacement Prediction of Surrounding Rock by Evolution BP-net Based on the decimal Gentic Algorithms

In recent years,more people have begun complaining about cooking exhaust pollution from restaurants in the city of Chongqing,P.R.China.Understanding cooking exhaust pollution origins and people's responses in Chongqing can provide a scientific basis for environmental protection decision-making in the city.To better understand these things,the attitudes of Chongqing inhabitants with different sex,age and residential proximity to cooking exhaust pollution and other environmental pollutants were investigated.The results show that city residents feel cooking exhaust pollution is the third most significant environmental pollution problem in Chongqing after noise and air pollution.Responses to cooking exhaust pollution vary with different sex,age and residential environment.This paper concludes by analyzing reasons for ineffective solutions to the cooking exhaust pollution problem in Chongqing and puts forward corresponding new countermeasures.     

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.     

simulation and improvement of an all terrain vehicle muffler

Aiming at a muffler of a 400 all terrain vehicle(ATV), a vibration model and an acoustics model of the muffler were built by finite element method(FEM). The vibration and acoustics characteristic analysis of the muffler are carried out according these models, it shows the 3D model is exact and it is possible to generate regeneration noise. Acoustics model can help to know further about the characteristic of each chamber and intention of the designer. According the demand of factory, some projects of improvement are offered. The final result of road test proves that he improved muffler is feasible.     

某柴油机进排气提前角的选优

为了寻找柴油机在动力性能、燃油消耗率以及排放之间的平衡,获得更好的综合性能,基于GTPower软件,利用柴油机的基础参数,建立柴油机的整机GT-Power模型并用试验数据进行校准。然后设置多组进气提前角和排气提前角的值进行数值模拟,分别分析进排气提前角对柴油机功率、燃油消耗率、充量系数等参数的影响。最后综合考虑多方面的因素,得出进气提前角定在21℃A左右,排气提前角定在76℃A左右较为合理的结论。     

重型柴油机颗粒物分布规律的试验研究

为了同时控制车用重型柴油机的颗粒物排放质量和数目,该文对稳态工况及瞬态工况下柴油机排放颗粒物分布规律进行了试验研究。试验结果表明:在稳态工况下,随着负荷的增加或者转速的提高,积聚态及核态颗粒物数目浓度、中位直径(count median diameter,CMD)、表面积和质量均呈现增大趋势,且峰值向大粒径方向偏移。在本研究中,稳态工况全工况总颗粒物数目浓度为1.5×10~6~4.5×10~6个/cm~3,积聚态颗粒物数目浓度为2×10~6~1×10~7个/cm~3,而核态颗粒物数目浓度为1×10~7~3×10~7个/cm~3,在总颗粒物数目浓度中占比为65%~96%。全工况当量比均小于0.7,在中低转速,当量比对颗粒物分布影响较为明显,在高转速尤其是大负荷条件下,当量比的影响减弱。在瞬态工况下,颗粒物数目浓度出现了与颗粒物质量类似的排放尖峰现象,浓度峰值达到2×108~7×108个/cm~3,比其对应的稳态工况出现的浓度峰值高出1个数量级。而且排放尖峰现象中,积聚态颗粒物数目浓度占主要部分,其峰值浓度比稳态工况要高出2个数量级,此时排放尖峰现象中核态颗粒物数目浓度也出现明显增长。排放尖峰现象对应的粒径主要集中在积聚态颗粒物的50~200 nm范围和核态颗粒物的6~8 nm及20~50 nm范围。这主要是因为当量比在瞬态过程出现了超过临界当量比0.8的情况。研究结果对重型柴油机颗粒物排放控制以及生成机理有重要指导意义,并可为排放后处理器的匹配计算提供数据支持。     

VNT与EGR耦合对不同气压下燃用含氧燃料柴油机性能的影响

将废气再循环(exhaust gas recirculation,EGR)、可变喷嘴涡轮增压器(variable nozzle turbocharger,VNT)与含氧燃料掺烧技术结合,可拓宽EGR的适用工况,提高空燃比,既有助于解决氮氧化物(nitrogen oxides,NOx)与微粒(particulate matter,PM)排放的矛盾,也有利于减小海拔上升导致的柴油机性能恶化的程度。选择EGR与VNT耦合的高压共轨柴油机作为研究机型,将生物柴油和生物乙醇按一定比例与柴油混合成生物乙醇柴油(biodiesel-ethanol-diesel,BED)燃料,利用大气模拟系统,在100和80 k Pa的环境下,试验研究VNT与EGR对含氧燃料柴油机动力性、经济性、排放特性的影响规律。结果表明:含氧燃料柴油机的动力性和经济性随着VNT开度和EGR率的增大以及大气压力的降低而变差,在大气压力为80 k Pa、转速为2 200 r/min工况下,VNT开度从22%增大到28%扭矩平均降低3.8 N·m,比油耗平均增加4.2 g/(k W·h),EGR率每增大5%扭矩平均降低0.8 N·m,比油耗平均增加1.5 g/(k W·h),大气压力从100降低至80 k Pa时扭矩平均降低3.4 N·m,比油耗平均增加4.9 g/(k W·h);VNT开度从22%增大到28%时NOx平均减小15%,EGR率每增大5%时NOx排放平均降低12%,大气压力从80增大到100 k Pa时NOx排放平均增加11%;VNT开度从22%增大到28%烟度的平均增幅为175.3%,EGR率每增大5%烟度的平均增幅为331.9%,大气压力从100降低至80 k Pa时烟度的平均增幅为96.6%。     

汽车尾气对206国道周边土壤铅含量的影响

机动车尾气作为环境污染源,是土壤化学污染的一个重要来源。随着我国运输业的发展,机动车拥有量迅速增加,致使公路边重金属污染日趋严重。研究了合肥市长丰县206国道卧龙山段公路旁土壤重金属铅污染状况。结果表明:铅含量随着离路基距离的增加而减少,除山林为轻度污染外,住宅和农田100 m以内为中度污染;铅含量基本随土层深度的增加而减少。