开环反应对E-20环氧树脂水性化过程的研究

研究接枝单体对E-20型环氧树脂分子中环氧基开环率的影响。采用自由基接枝共聚的方法对环氧树脂进行改性使其具有水溶性。以过氧化苯甲酰为引发剂,接枝单体拟选用丙烯酸、甲基丙烯酸丁酯、苯乙烯通过自由基反应接枝到E-20环氧树脂分子上,制备自乳化的环氧乳液。这种改性的环氧树脂乳液具有很低的有机挥发物,满足了当前提倡的绿色环保的要求。

聚合反应条件对甲基丙烯酸缩水甘油酯/丙烯酸丁酯乳液共聚体系凝胶的影响

将丙烯酸丁酯(BA)与甲基丙烯酸缩水甘油酯(GMA)进行乳液共聚合以制备环氧型聚丙烯酸酯橡胶(ACM),通过对ACM中凝胶含量及环氧基开环率的对比研究,探讨了不同反应条件对凝胶含量的影响。结果表明,在反应体系中加入20%的第二单体丙烯酸乙酯(EA)、选择复合引发体系、反应温度控制在30℃以及在反应体系对单体需求处于饥饿状态下投料可抑制BA链转移和GMA中的环氧基开环,聚合物中凝胶含量可低达2.9%。

光电催化协同高效降解苯酚和去除溶液的COD

开发一种电化学方法,高效降解低浓度苯酚溶液。按照钛离子与铜离子比例100∶1,将铜离子掺杂到锐钛型二氧化钛晶格中,获得铜离子掺杂锐钛型二氧化钛,铜离子掺杂前后,晶型保持不变。将掺杂铜离子二氧化钛配制成溶液,涂布于不锈钢表面,经过干燥,获得复合电极;以复合电极为正极、不锈钢网为负极,降解浓度为100 mg/L、体积为6 L苯酚溶液;研究结果表明:当特征波长为380 nm紫外灯、照射强度为1 100μw/cm2、溶解氧浓度为9 mg/L、电压为12 V时,苯酚降解速度最快,2 h内苯酚开环率达到98%,溶液的化学需氧量去除率大于95%,溶液的COD小于10mg/L。

Influence of Reclamation Works on the Marine Environment in a Semi-Enclosed Bay

The flow and seawater exchange rates have been predicted using a two-dimensional numerical model and a Lagrangian method for a semi-enclosed shallow bay where reclaiming and dredging works are scheduled. The wind effect on the flow and material transport has been emphasized, and a thirty-year mean value of wind has been considered in the numerical simulation. As a whole, even after the reclaiming and dredging are conducted, the flow pattern looks similar to the original state. However, velocity variations up to 20% to 100% appear in the vicinity of the construction area. In the case of summcr wind forcing, the seawater exchange rate increases from 71.6% to 82.9% after the reclaiming and dredging, as indicated by a particle-tracking method. On the contrary, in the case of winter wind forcing, thc seawater cxchange rate appears to be 97.2% under natural conditions but decrcases slightly to 93.2% aftcr the rcclaiming and dredging. Thus, the wind forcing plays an important role in controlling the seawater exchangc rates. The seawater cxchange rate is further improved by 15% if the dredging is simultaneously carried out with the reclaiming. This suggests that the dredging can be an effective means to mitigate the variation of flow.

Diode-pumped Q-switched Extra-cavity Frequency-dou bled Nd∶YVO_4/KTP Green Laser

A diode-pumped acousto-op ti cal(A-O) Q-switched extra-cavity frequency-doubled Nd∶YVO_ 4/ KTP (KTiO PO_ 4) green laser formed with a simple plane-plane cavity has been demonst rated. With the incident pump power of 12.7 W, A-O Q-switched average output power at 1 064 nm was 3.81 W with a duration of 25 ns at a repetition rate of 20 kHz, extra-cavity frequency doubling with KTP as the nonlinear crystal y ielded the maximum output power of 1.92 W at 532 nm, the corresponding optical conversion efficiency from 1 064 nm to 532 nm light is 50.4%. The continuous -wave(CW) laser properties of diode-pumped Nd∶YVO_ 4 crystal operating at 1 064 nm have been studied. With the incident pump power of 25 W, the maximu m CW output power of 13.81 W was obtained with the corresponding optical conver sion efficiency of 55.24%.

High Resolution Ship Hydrodynamics Simulations in Open Source Environment

The numerical simulation of wake and flee-surface flow around ships is a complex topic that involves multiple tasks： the generation of an optimal computational grid and the development of numerical algorithms capable to predict the flow field around a hull. In this paper, a numerical framework is developed aimed at high-resolution CFD simulations of turbulent, free-surface flows around ship hulls. The framework consists in the concatenation of ＂tools＂, partly available in the open-source finite volume library OpenFOAM. A novel, flexible mesh-generation algorithm is presented, capable of producing high-quality computational grids for free-surface ship hydrodynamics. The numerical frame work is used to solve some benchmark problems, providing results that are in excellent agreement with the experimental measures.

Study of a Single-Phase Series Active Power Filter with Hysteresis Control

The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequency. The general purpose of the series APF is to eliminate the low order harmonics of the source （grid） voltage. The filter operation at limited and unlimited maximum switching frequency is explained and it is described using building blocks and time diagrams illustrating the tracking down of the reference curve. Waveforms from the computer simulation and waveforms from the experimental tests of the filter are presented also for the two situations. Operations at limited and unlimited maximum switching frequency are compared regarding the quality of the voltage across the load, the complexity of the implementation of the control system, and the electromagnetic compatibility. The investigation proved capability of the series APF to achieve its general purpose using the hysteresis control methods studied （limited and unlimited switching frequency）.

Valuation of equity-indexed annuities with regime-switching jump diffusion risk and stochastic mortality risk

This paper extends the model and analysis of Lin, Tan and Yang （2009）. We assume that the financial market follows a regime-switching jump-diffusion model and the mortality satisfies Levy process. We price the point to point and annual reset EIAs by Esscher transform method under Merton＇s assumption and obtain the closed form pricing formulas. Under two cases： with mortality risk and without mortality risk, the effects of the model parameters on the EIAs pricing are illustrated through numerical experiments.