三乙醇胺双硬脂酸酯的合成研究

采用单因素试验法,对酯化反应的催化剂进行了筛选,确定了较优的催化剂后,通过L9(34)正交试验合成易生物降解的新型非离子表面活性剂——三乙醇胺双硬脂酸酯,分别测定不同酯化条件下产物的酸值和皂化值,得出硬脂酸的转化率,同时用高效液相色谱对酯化产物中单、双、三酯的含量进行测定,得出最佳酯化工艺条件。在该条件下进行酯化反应,硬脂酸的转化率高达93.34%,三乙醇胺(TEA)双硬脂酸酯的含量可达59.32%。     

Localized CO2 laser bonding process for MEMS packaging

The packaging poses a critical challenge for commercialization of MEMS products. Major problems with the packaging process include degraded reliability caused by the excess stress due to thermal mismatch and altered performance of the MEMS device after packaging caused by thermal exposure. The localized laser bonding technique for ceramic MEMS packaging to address above-mentioned challenges was investigated. A continuous wave CO2 laser was used to locally heat sealing material for ceramic MEMS package lid to substrate bonding. To determine the laser power density and scanning speed, finite element analysis thermal models were constructed to simulate the localized laser bonding process. Further, the effect of external pressure at sealing ring on the bonding formation was studied. Pull testing results show that the scanning speed and external pressure have significant influence on the pull strength at the bonding interface. Cross-sectional microscopy of the bonding interface indicates that the packages bonded with relatively low scanning speed and external pressure conditions have higher bonding quality. This research demonstrates the potential of localized laser bonding process for ceramic MEMS packaging.     

某型号起重机仿真分析与试验研究

应用MSC.ADAMS 软件对履带起重机起臂、提升、回转、行走、变幅等工况时的动力学过程进行仿真;应用ANSYS软件建立臂架系统的有限元模型,将ADAMS 输出的载荷导入到有限元模型中,进行多载荷步的有限元动态模拟,求出臂架系统在各工况下的受力状态;应用电阻应变仪对臂架进行应力测试,并将测试结果与仿真结果进行对比。     

纯胶酯化反应条件的优化

通过正交试验探讨了纯胶生产中酯化反应的工艺参数,试验结果表明：反应体系的pH值对取代度的影响最大,反应时间对取代度的影响最小;反应时间12h,反应温度为35℃,pH为8、5,淀粉乳质量分数为35％时反应效果比较理想。     

抗菌、自清洁陶瓷的制备及性能表征

研究了金属离子抗菌作用与TiO2光催化作用协同复合的原理和方法,复合抗菌陶瓷的制备与性能测试表征.选择并制备出了磷酸锆载体,确定了最佳银铜金属离子比,制备出了抗菌粉体材料和抗菌陶瓷,用溶胶-凝胶法和浸渍提拉法在抗菌陶瓷表面镀一层TiO2薄膜.测试表明,TiO2薄膜物相主要为锐钛矿晶型,膜厚20～75nm左右,抗菌粉体材料和抗菌陶瓷制品的抗菌率都达到了抗菌标准要求,光催化降解有机物效果显著.     

Electrophysiological and Behavioral Responses of a Cuban Population of the Sweet Potato Weevil to its Sex Pheromone

The sex pheromone of feral sweet potato weevils Cylas formicarius elegantulus from Cuba was found, via solid-phase microextraction analysis, to be identical to (Z)-3-dodecenyl (E)-2-butenoate, a previously reported compound. Females emitted 20 pg pheromone d⁻¹. In scanning electron microscopy studies carried out on the male antenna, we identified several types of sensilla: sensilla trichoidea of type 1 (ST1) as long hairs (100–150 μm), sensilla trichoidea of type 2 as short hairs (50–60 μm), sensilla basiconica of type 1 as thick pegs (20–25 μm), sensilla basiconica of type 2 as curved pegs (10–15 μm), and sensilla basiconica of type 3 as thin and straight short pegs (15–20 μm). The same types were observed in female antennae but ST1 were far less abundant than in males. Sensilla chaetica were also found on the flagellum subsegments in both sexes. In electrophysiological tests, the crotonate function in the pheromone structure proved to be critical for activity since regular depolarizations (0.6–0.8 mV) were obtained with puffs on 1 μg of the attractant, but not with puffs of the formate, acetate, propionate, or butyrate analogue of the pheromone. In a double dual-choice olfactometer, males showed maximum activity between the 4th and the 8th hr of scotophase at a dose of 50–1000 ng of pheromone. In field tests, a correlation between the contents of the Z,E isomer in the pheromone formulation with activity was noticed, and baits containing this isomer of stereomeric purity >94% showed the highest attractivity. The presence of 5% of the Z,Z isomer in the lure did not induce any synergistic or inhibitory effect, and the alcohol precursor of the pheromone was inactive. The results show that use of a stereomerically pure pheromone may not be necessary in pest control strategies.     

Range Unit‐Root (RUR) Tests: Robust against Nonlinearities,Error Distributions,Structural Breaks and Outliers

Abstract. Since the seminal paper by Dickey and Fuller in 1979, unit‐root tests have conditioned the standard approaches to analysing time series with strong serial dependence in mean behaviour, the focus being placed on the detection of eventual unit roots in an autoregressive model fitted to the series. In this paper, we propose a completely different method to test for the type of long‐wave patterns observed not only in unit‐root time series but also in series following more complex data‐generating mechanisms. To this end, our testing device analyses the unit‐root persistence exhibited by the data while imposing very few constraints on the generating mechanism. We call our device the range unit‐root (RUR) test since it is constructed from the running ranges of the series from which we derive its limit distribution. These nonparametric statistics endow the test with a number of desirable properties, the invariance to monotonic transformations of the series and the robustness to the presence of important parameter shifts. Moreover, the RUR test outperforms the power of standard unit‐root tests on near‐unit‐root stationary time series; it is invariant with respect to the innovations distribution and asymptotically immune to noise. An extension of the RUR test, called the forward–backward range unit‐root (FB‐RUR) improves the check in the presence of additive outliers. Finally, we illustrate the performances of both range tests and their discrepancies with the Dickey–Fuller unit‐root test on exchange rate series.     

RELATIVE POWER OF t TYPE TESTS FOR STATIONARY AND UNIT ROOT PROCESSES

Abstract. This paper shows numerically that the lack of power and size distortions of the Dickey-Fuller type tests for unit roots (very well documented in the unit root literature) are similar to and in many situations even smaller than the lack of power and size distortions of the standard Student t tests for stationary roots of an autoregressive model.     

Modeling and analysis of rapid catalyst aging cycles

The primary mode of deactivation of automotive emission control catalysts is thermal aging, and it is well-known that high-temperature lean aging conditions are particularly detrimental. Since evaluating the long-term durability of automotive catalysts is costly and time-consuming, rapid catalyst aging cycles have been developed to mimic (in a reduced time) the catalyst deactivation under real-world driving conditions. One of the commonly used rapid catalyst aging tests is an exothermal aging cycle, which involves a combination of fuel-rich engine operation and supplemental air injection to generate high-temperature lean conditions within the catalyst bed. In this work, we use the previously developed transient three-way catalyst model to investigate the time evolution of the axial temperature profiles and exhaust air–fuel ratio (A/F) along the catalyst bed during the course of the exothermal rapid aging cycles. We find that the thermal front propagates downstream through the catalyst bed relatively slowly (compared to the concentration front) and this can limit the location within the catalyst bed and duration for high-temperature lean exposure. We also investigate how variations of some of the key system design and operating parameters can affect the extent and duration of high-temperature lean exposure. Finally, a simple analytical expression is developed which allows one to estimate the time it takes for the thermal front to travel through the catalyst bed. This time can be compared with the period of the lean A/F operation during the aging cycle to determine the location and duration of high-temperature lean exposure.     

某种永磁同步发电机直接转矩控制系统设计

依据二维弹道修正原理,提出修正舵机中永磁同步发电机直接转矩控制方法,针对d-q坐标系下的永磁同步电机模型,研究了永磁同步电机直接转矩控制方案。结果表明,修正舵机中发电机直接转矩控制系统输出转矩能够达到高速旋转弹的修正效果。