除尘器新型褶式滤筒的结构优化及系列化设计

以新型褶式滤筒为研究对象,选取滤筒褶数N_2、褶夹角θ、褶高h、过滤风速v为影响因子,除尘器压力损失为响应值,基于响应曲面法分析影响因子对压力损失的影响,建立滤筒除尘器压力损失的预测模型并得到滤筒褶皱结构最优参数。以滤筒内径D、筒体高度D_1为标准尺寸,依据相关国家标准设计滤筒筒体部分;以锥体高度D_2、锥体上圆直径D_3为系列尺寸,利用尺寸变化法设计锥体部分;通过Access软件建立滤筒产品数据库。结果表明:当θ=5.2°,N_2=50,v=0.01 m/s,h=0.035 m时,除尘器压力损失最低;当D_1=1 000 mm,D=320 mm时,D_2和D_3最佳值分别为600,130 mm,故采用D_2/D_1=0.6,D_3/D=0.4的比值设计相应滤筒锥体系列。     

Transesterification of Palm-based Methyl Palmitate into Esteramine Catalyzed by Calcium Oxide Catalyst

The technology for transesterification reactions between methyl esters and alcohols is well established by using classical homogeneous alkaline catalysts, which provide high conversion of methyl esters to specialty or nonindigenous esters. However, in certain products where the purity of the esters is of concern, the removal of homogeneous catalysts after the completion of the reaction is a challenge in terms of production cost and water footprint. Therefore, a study to investigate the potential of heterogeneous catalysts was conducted on reactions between methyl palmitate and triethanolamine. The degree of basicity and active surface area of calcium oxide (CaO), zinc oxide (ZnO), and magnesium oxide (MgO) were first characterized by using temperature-programmed desorption (TPD-CO₂) and Brunauere–Emmett–Teller (BET), respectively. Among the metal oxides investigated, the CaO catalyst showed the best catalytic activity toward the transesterification process as it gave the highest conversion of methyl palmitate and yielded fatty esteramine compositions similar to the conventional homogeneous catalyst. The optimum transesterification condition by using the CaO catalyst utilized a lower vacuum system of approximately 200 mbar, which could minimize a considerable amount of energy consumption. Furthermore, low CaO dosage of 0.1% was able to give a conversion of 94.5% methyl ester and formed esteramine at 170 °C for 2 h. Therefore, the production of esterquats from esteramine may become more economically feasible through the methyl ester route by using the CaO catalyst, which can be recycled three times.     

Single-Crystalline TiO2(B) Nanobelts with Unusual Large Exposed {100} Facets and Enhanced Li-Storage Capacity

The {100} facet of single-crystalline TiO₂(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO₂(B) nanobelts from H₂Ti₃O₇ with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO₂ formula with specific capacity up to 335 mAh g⁻¹, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g⁻¹ after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures.     

水文序列相依变异识别的RIC定阶准则——以自回归模型为例

水文过程相依性是水文变异的主要表现形式之一,应用自回归模型对其进行拟合时合理确定模型阶数是一个难点问题。本文在分析AIC和BIC准则的基础上,提出了一种以原序列与其相依成分的相关系数作为拟合度指标,同时借用信息熵形式的函数式,作为模型不确定性度量指标的自回归模型定阶准则(简称RIC准则)。以AR(1)、AR(2)、AR(3)和AR(4)模型为例进行统计试验,将不同序列长度下该准则的定阶准确率与其他定阶准则进行比较,试验结果表明,RIC准则对于上述模型均具有较好的适应性,且定阶准确率远高于AIC准则,其中对于前三阶模型RIC准则优于BIC准则,但四阶模型略低于BIC准则。RIC准则的优势是可以同时满足模型定阶、相依程度分级与模型检验的需求,将其应用于实测水文序列分析,结果显示,该准则能较准确地识别自回归模型的阶数,且符合提出的"相依有变异而残差无变异的最小阶数"的检验标准。     

一种基于场强差的GSM网络移动台定位法

提出了一种在GSM无线蜂窝网络中利用服务BS（基站）和MS（移动台）测量的场强差值对MS进行定位的方法。通过计算机的仿真结果表明，该方法能够较好地克服多径和不规则地形带来的场强起伏，达到较高的定位精度。通过提出的的算法，可以克服传统的利用GSM蜂窝网络对移动台定位的局限性，从而使利用GSM蜂窝网络对移动台位置定位的实现更简单。     

阿鸠田电站SF35-16/4100水轮发电机绝缘工艺

云南保山阿鸠田电站由三台SF35-16/4100水轮发电机组成,单机额定容量35 MW,额定电压10.5 kV,定、转子绕组均采用F级绝缘。根据用户要求采用了一些新绝缘结构,并进行了大量的工艺试验,生产中选择优质材料,严格控制工艺过程,使已出厂的三台发电机定、转子线圈及定、转子装配的电气绝缘性能优良。文章就机组定、转子绕组绝缘工艺进行了简要的介绍。     

从利奥塔的元叙事危机看我国私人写作的意义

让一弗·利奥塔对当代知识与叙事特别是元叙事的合法性问题进行了探讨,最后得出元叙事的危机以及与之相关的普遍主体、现代知识分子神话的解体。本文试以此理论为基础,阐述我国私人写作的权利与意义。     

Ru/MCM-41催化剂上苯的液相加氢反应

 以Si-MCM-41、Al-MCM-41(1) (n(Si)/n(Al)=15)、Al-MCM-41(2) (n(Si)/n(Al)=10)以及用NH4NO3或HAc的醇溶液分别与Si-MCM-41离子交换所得的H-MCM-41(N)和H-MCM-41(H)为载体制备了系列Ru/MCM-41催化剂。采用N2吸附、XRD和H2-TPR表征了负载Ru前后催化剂的结构及Ru在各种载体表面上的分散状态。以0.5%（质量分数）苯的环己烷溶液为模型化合物，在298K、3.0MPa反应条件下，考察了上述催化剂的苯液相加氢反应性能，并与Ru/HY、Ru/H和Pt/MCM-41催化剂进行了比较。结果表明，载体MCM-41的n(Si)/n(Al)和表面化学组成等性质对Ru在其表面上的分散状态、还原性及催化性能均有影响。对苯的转化率与反应时间的关系曲线进行拟合，发现其遵循一级动力学方程，加氢反应速率常数按照Ru/Al-MCM-41(2)相似文献   

一种单相串联混合电力有源滤波器的研究

文中对串联混合电力滤波器抑制谐波的原理进行了分析。为了检测单项系统的谐波电流,提出一种基于虚拟三相法和瞬时无功理论的谐波检测方法,并且对串联滤波逆变器的直流侧电压的控制进行了讨论。仿真结果证明了其有效性。     

嵌入式RTOS中任务优先级反转问题研究

针对嵌入式实时系统任务调度策略的特点，任务在运行的时候可能被更高优先级的任务中断。分析了嵌入式RTOS中的最高就绪任务的查找算法，指出该调度算法存在的不同优先级的反转问题，并且针对这一问题进行研究，给出了相应的优先级继承方案。较好地解决了RTOS中任务调度中的优先级的反转问题。