公路工程项目经济评价指标计算方法

为了对含有模糊基础数据和参数的公路工程项目方案进行有效评价,建立了评价指标体系,将评价指标分为梯形与三角形模糊变量,在同一可能空间上或不同可能空间上进行模糊运算,由Zadeh扩展原理得到模糊变量的隶属度,利用模糊模拟技术计算模糊变量的可信值、关键值与期望值,并利用计算值对项目进行了评价。评价结果表明:评价项目的模糊期望净现值大于0,可信值达到100%,说明项目可行,评价结果客观。     

综合重症监护病房患者呼吸机相关性肺炎的病原学和耐药性分析

目的探讨病原菌在综合重症监护病房(ICU)患者呼吸机相关性肺炎(VAP)中的分布及对常用抗生素的耐药情况。方法对我院2004-2006年综合ICU患者VAP病原菌的分布及耐药性进行回顾性统计分析。结果从302例综合ICU VAP患者下呼吸道深部分泌物标本中分离出347株病原菌,主要病原菌是铜绿假单胞菌(32.3%)、鲍曼不动杆菌(31.1%)、金黄色葡萄球菌(16.7%)、克雷伯菌(7.5%)与凝固酶阴性葡萄球菌(6.1%)。革兰阴性杆菌(G-杆菌)对哌拉西林、头孢噻肟耐药率最高,对碳青霉烯类及加酶抑制剂抗生素耐药率最低;革兰阳性球菌(G 球菌)对青霉素类、克林霉素及红霉素耐药率高,对万古霉素、喹诺酮类抗生素耐药率低。结论G-杆菌是综合ICU患者VAP最主要的病原菌,多重耐药性高;耐甲氧西林金黄色葡萄球菌(MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(MR-SCNS)的分离率高且耐药严重。临床医师应根据病原菌学及抗菌药物敏感性资料,及时选择合理的抗生素控制感染,延缓耐药菌株的产生。     

非线性优化AHP法在公交服务水平评价中应用

本文应用非线性优化AHP法确定指标权重系数,改进了传统AHP法的不足之处,针对评价指标的模糊性,建立城市公交服务水平模糊综合评价模型,并通过实例分析和计算,验证了该方法的可行性和实用性。     

Sliding window method for vehicles moving on a long track

The rail is modelled as a simply supported beam in the vehicle–track coupled dynamics. The beam is formulated by a partial differential equation that is transformed into an ordinary differential equation by the method of mode superposition for numerical calculation. However, the size of the matrix that is formed by the mode-superposition method increases significantly with track length, which limits the calculation efficiency. Some methods have been developed to solve this calculation issue, but they diminish the merits of the vehicle–track coupled dynamics, which would systematically investigate the dynamics of a vehicle and a track from the entire vehicle–track system. A new method is developed to resolve this contradiction. First, a theory based on a sliding window is established to improve the computational stability with respect to the length and the window-movement ratio. Then, two methods, namely finite element method analysis and an analytical solution, are used to verify the accuracy of the new method, which is highly efficient when used in a vertical half-vehicle–track coupled model to calculate the vehicle response when the vehicle moves on a long track. The results of the vehicle response calculated with and without the sliding window show good consistency.     

Field measurements of the evolution of wheel wear and vehicle dynamics for high-speed trains

This investigation demonstrates the wheel wear evolution and related vehicle dynamics of high-speed trains with an operating distance (OD) of around two million kilometres. A long-term experimental test lasting two years was conducted to record the wheel profiles and structural vibrations of various trainsets. The wheel wear, namely the profile shape, worn distribution and wheelset conicity, is investigated for several continuous reprofiling cycles. Typical results are illustrated for the stability analysis, and the ride quality is examined with increasing OD. In addition, the vibration transition characteristics between suspensions are investigated in both the time and frequency domains. The experiments show that the dominant wear concentrates on the nominal rolling radius, and the wear rate increases with OD because of the surface softening resulting from the loss of wheel material. The vibration of structural components is aggravated by the increase of the equivalent conicity of the wheelset, which rises approximately linearly with the wheel wear and OD. High-frequency vibrations arise in the bogie and car body related to the track arrangement and wheel out-of-roundness, causing the ride comfort to worsen significantly. Additionally, the system vibration characteristics are strongly dependent on the atmospheric temperature. Summaries and conclusions are obtained regarding the wheel wear and related vehicle dynamics of high-speed trains over long operating times and distances.     

双塔双索面稀索斜拉桥加固设计

以南阁大桥的主桥斜拉桥加固为工程背景,基于将挂梁与主跨相邻35m工字梁作为整体来计算桥梁结构损伤程度校验系数的研究现状,考虑将挂梁作为单独受力的简支梁置于两侧斜拉桥框架上来计算校验系数,并据此校验系数判定桥梁的损伤程度,对旧桥进行加固设计。     

猪屎豆、白灰毛豆在海南中线高速边坡生态恢复中的应用

为了研究猪屎豆和白灰毛豆两种灌木在公路边坡生态恢复中的实际应用效果,2012年在海南省中线高速(S21)选择骨架防护、三维网防护、普通喷播3种典型防护形式坡面进行了猪屎豆、白灰毛豆灌木种子不同配比方案恢复试验.试验结果表明,猪屎豆、白灰毛豆两种灌木的株高、冠幅、胸径、生长密度4个生长指标变化特征与前期种子配比情况有直接关系,其中冠幅和胸径指标正相关,但是与株高和生长密度指标负相关.该结果说明这两种灌木在海南省中线高速边坡(包括普通土质边坡和膨胀土劣质边坡)生态恢复中具有可行性,但是应调整灌木种子用量,确保灌木适宜的生长空间,维持灌木健壮的生长势,同时种子应合理搭配以维持后期边坡物种的多样性.这一研究结果可为海南省中线高速边坡生态恢复提供一定的参考.     

给定最大度的极大拉普拉斯谱单圈偶图

通过图的移接变形对拉普拉斯谱半径的影响,研究了给定最大度为Δ2的n阶极大拉普拉斯谱单圈偶图的性质,得到了它的规范拉普拉斯谱向量中绝对值最大的分量对应的顶点的度均等于Δ且这些顶点的位置均在圈上。     

基于车辆平顺性分析的橡胶衬套动态特性建模

橡胶衬套的动态特性与载荷的激振频率、幅值等因素相关,其模型的准确性影响车辆平顺性的仿真精度。建立了包含材料弹性、粘弹性与弹塑性的橡胶衬套动态模型,分别采用多项式、分数导数与Bouc-wen模型描述橡胶衬套的弹性、频率相关性及振幅相关性。通过参数辨识确定衬套模型参数并进行仿真,验证了所建模型的准确性。     

NH_3-SCR钒系催化剂的制备及脱硝性能研究

为了有效控制柴油机NOx排放量,采用等体积浸渍法制备了一系列不同组合含量的钨基催化剂及掺杂不同过渡金属M的改性催化剂M-V2O5-WO3/TiO2(其中M可以是Ni,Zr,Fe,Cu),分别对两类催化剂进行了SCR脱硝活性测试,并进一步用XRD,TEM和NH3-TPD对催化剂进行了表征。研究表明,催化剂掺杂金属Zr时的催化效率较高,在低温(150℃)时也有较高的活性。催化剂活性增加的原因可能是掺杂金属Zr加强了V,W及载体TiO2的分散性,提高氧化还原能力和表面酸性,从而促进SCR性能。