采用温控和碘吸收池技术的发射激光稳频技术

多普勒测风激光雷达通过分析系统回波信号的多普勒频移反演出风速，为提高风场探测精度，从稳频技术方面展开研究。在稳频过程中，分别采取措施消除激光频率的长期漂移和短期抖动。针对激光频率的长期漂移，设计并研制了种子激光器温控箱，通过水浴的控温方式大大减小了激光频率的长期漂移，将激光频率稳定在±50 MHz以内；针对激光频率的短期抖动，采用以碘分子吸收池为核心器件的稳频系统，通过半导体控温方式对碘分子吸收池精确控温，控温精度达0.03 ℃，提高了稳频精度，将激光频率进一步稳定在±8 MHz以内，满足±10 MHz以内的设计精度要求。通过搭建多普勒测风激光雷达系统，对发射激光稳频装置进行系统验证，连续4组风场观测结果表明:系统探测高度为17 km，绝大部分方差在4 m/s以下，满足测风激光雷达测量指标的要求。     

Flame Front Deformation Instabilities of Filtration Combustion for Initial Thermal Perturbation

The flame front deformation instability of low-velocity filtration combustion within an inert packed bed is studied based on the initial preheating non-uniformity. Based on the experimental phenomena, an initial thermal perturbation model is numerically proposed so as to predict the deformation behaviors of the flame front instabilities. The numerical prediction indicates that the assumption of an initial thermal perturbation is a feasible explanation as the cause of the flame front inclination instability. As the initial thermal perturbation increases, the phenomena of the flame front break and shrinking instabilities could easily occur at high filtration velocity or low equivalence ratio. Moreover, the evolutions of the flame front break rate and the shrinking rate are quantitatively analyzed.     

Photoluminescence and temperature sensing of lanthanide Eu3+ and transition metal Mn4+ dual-doped antimoniate phosphor through site-beneficial occupation

For a long time, rare-earth ion-doped phosphors have been widely used in temperature sensing because of their excellent light-emitting properties. However, most of the rare earth elements are relatively rare and expensive, so the transition group elements that are economical and easy to obtain have been favored by researchers. This paper presents a new type of phosphor doped with rare earth ion and transition metal for optical temperature measurement. In recent years, Mn⁴⁺-doped phosphors have attracted wide attention because of their strong deep red light-emitting properties. La₂LiSbO₆ provides a good host environment for Mn⁴⁺ and Eu³⁺ due to its unique crystal structure. In this paper, a series of La₂LiSbO₆ phosphors singly doped with Mn⁴⁺ and Eu³⁺, and co-doped with Eu³⁺/Mn⁴⁺ were synthesized. The crystal phases and optical properties of these materials were characterized and analyzed in detail. We specifically studied the temperature dependence of the fluorescence intensity of the optimized La₂LiSbO₆: Eu³⁺, Mn⁴⁺ phosphors at 303K–523K. The experimental results prove that the thermal responses of Mn⁴⁺ and Eu³⁺ are different. With increasing temperature, the thermal quenching of the Mn⁴⁺ fluorescence intensity is much faster than that of Eu³⁺, so the temperature characteristics can be explored by the fluorescence intensity ratio (FIR) of Eu³⁺ to Mn⁴⁺. At 523 K, its maximum relative sensitivity and maximum absolute sensitivity can reach 0.891% K⁻¹ and 0.000264 K^-1, respectively. Our experimental analysis shows that La₂LiSbO₆:Eu³⁺/Mn⁴⁺ phosphors have relatively high temperature sensitivity and have potential application prospects in the field of high temperature sensing.     

Identification of active sites in CO2 activation on MgO supported Ni cluster

In this work, initial activation mechanism of CO₂ over MgO supported Ni catalysts has been systematically studied through the periodic DFT calculations. In addition, the role of metal cluster, interface and support for CO₂ activation is investigated and the active site is identified. CO₂ is most favored to be activated on the interface instead of neither Ni cluster nor MgO support. The effective energy for this process is around 0.67 eV, and the dissociation of CO₂ (0.62 eV) is the rate-determining step, since it requires much higher energy than that of the CO₂ adsorption process (0.05 eV). Thus, the interface between metal cluster and support plays a key role for C=O bond activation. Moreover, CO1 is preferred to be adsorbed on the Ni cluster, while the O1 is likely to bind on Mg atom of support. To illustrate the adsorption behavior of CO₂ at different sites, the Mulliken atomic charge and electron density difference have been calculated. It was found that the total amount of electron gain for CO₂ binding at different sites follows the order of Interface (−0.03 e) < MgO support (−0.05 e) < Ni cluster (−0.07 e), and effective energy barrier rises linearly with the increase of electron gain of CO₂ binding at different sites. In addition, electron gain of oxygen atom O1 and oxygen atom O2 of CO₂ is the same for Ni cluster and MgO support, however, the electron gain of O1 and O2 is different for Interface. The difference of electron gain for two oxygen atoms shows the electron unbalance of CO₂ molecule, which is in favor of C=O activation. This study could shed some light on understanding the active sites of CO₂ thermal-catalytic activation over MgO supported Ni catalysts, and is helpful to elucidate the reaction on an atomic level.     

Decision evaluation process in end-of-life systems management

In manufacturing sectors, firms are paying an increasing attention to sustainability concept with regard to their end-of-life products in order to respect environmental norms and satisfy the consumer sensitivity. This practise allows creating value by reintroducing dismantling and recovering parts and/or materials of end-of-life products into manufacturing process, or into maintenance process. Thus, deconstruction processes are developed in order to examine all activities addressing the end of life (EOL) systems to ensure its disposal according to environmental constraints when seeking an economic optimum. In this context, one of the first tasks to perform is to repatriate the EOL systems at lowest cost considering geographical optimization of treatment centers. Considering this point, the present paper proposes an evaluation and optimization approach for the withdrawal location process in the field of aircraft dismantling. Given the multitude and heterogeneity of characteristics to be taken into account, we propose to consider dismantling site location problem as multi-criteria/multi-objectives decision making problem and solve it using a new AHP-BOCR approach based on qualitative and quantitative evaluations. A bipolar structuring framework is considered to distinguish positive and negative aspects in the elicitation/evaluation process to avoid compensation and satisficing game theory is used as suitable mathematical tool for recommendation process. An experimental study is carried out to show the usefulness of the framework.     

The investigation of gold/zirconia as a photocatalyst for the direct synthesis of imines from alcohols and aniline

Au/ZrO₂ nanoparticles have been widely used as photocatalysts in various organic syntheses because of their localized surface plasmon resonance (LSPR) effects. In our work, Au/ZrO₂ has been synthesized by a solution method and it was used as a heterogeneous catalyst in the synthesis of imines from alcohols and aniline with irradiation by visible light. The reaction occurred in two steps: step 1 was the aerobic oxidation of the alcohols and step 2 was the nucleophilic addition of aniline. Dimethyl sulfoxide (DMSO) was used as a solvent in the reaction. The selectivity in the synthesis of imines over 3 wt% Au/ZrO₂ (with mean particle size of 5 nm) was high (over 90%) with irradiation by visible light at room temperature, and an obvious difference in the conversion was observed between the reactions with light irradiation and those without light. The intensity and wavelength of the light strongly affected the reaction. The Au/ZrO₂ could be used at least 5 times. A reaction mechanism was proposed based on the experimental results. The results indicate that the reaction of alcohols and aniline using Au/ZrO₂ as the photocatalyst can proceed under mild conditions. Furthermore, this process is environmentally friendly and green.     

Two-echelon multi-product multi-constraint product returns inventory model with permissible delay in payments and variable lead time

Supply chain is not limited to delivering products to the end-costumers since the defective products that are returned back to the producers by the consumers. The producers should be superior knowledge to utilize the return products effectively so as to maintain our natural resources and to provide better service to customers. In this paper, a distributor and a warehouse consisting of a serviceable part and a recoverable part supply chain problem is considered in which there are several products, the distributor has limited space capacity and budget to purchase all products. In this supply chain, the defective products are returned back to the warehouse by the distributor and the warehouse recovered those defective products into perfect products having the same value as the procured products. The lead-time of receiving products from a warehouse to a distributor is a variable which is controllable by adding extra crashing cost. For each product, a fraction of the shortage is backordered and the rest are lost. A mathematical model is employed in this study for optimizing the order quantity, lead time and total number of deliveries with the objective of minimizing system total cost. We show that the model of this problem is a constrained non-linear programme and present a simple Lagrangian multiplier technique to solve it. Numerical and sensitivity analysis are given to show the applicability of the proposed model in real-world product returns inventory problems.     

Identification of Wiener systems based on the variable forgetting factor multierror stochastic gradient and the key term separation

The identification of Wiener systems is very difficult because of the output nonlinearity and the parameter product term. To identify the Wiener system, a novel stochastic gradient algorithm based on the multierror and the key term separation is proposed. Firstly, the Wiener system is parameterized as a pseudo-linear model to avoid the products of the parameters. Secondly, a parzen window is used to estimate the probability density function of the error. Thirdly, a stochastic information gradient algorithm with the multierror is adopted to estimate the parameters. The multierror takes the place of the scalar error by the stacked error, which accelerates the algorithm greatly. Fourthly, a variable forgetting factor considering errors is integrated to further speed the algorithm up. Finally, the proposed algorithm is validated by a numerical example and an industrial case. The estimation results indicate that the proposed algorithm can obtain accurate estimates with fast convergence speed.     

Aspen Plus化工流程模拟软件学习和使用的几点体会

Aspen Plus是一款功能强大的集化工设计、动态模拟及各类计算与一体的模拟软件。介绍了Aspen Plus化工流程模拟软件的学习方法和使用的几点体会,化工流程软件的应用提高了学习兴趣,加深了对相关专业课程的理解和实践动手能力。同时Aspen Plus软件模拟比较接近实际工况,使化学工程与工艺专业的课程设置和学习内容更符合社会实际需要。