A two-stage sequential conditional selection approach to sparse high-dimensional multivariate regression models

In this article, we deal with sparse high-dimensional multivariate regression models. The models distinguish themselves from ordinary multivariate regression models in two aspects: (1) the dimension of the response vector and the number of covariates diverge to infinity; (2) the nonzero entries of the coefficient matrix and the precision matrix are sparse. We develop a two-stage sequential conditional selection (TSCS) approach to the identification and estimation of the nonzeros of the coefficient matrix and the precision matrix. It is established that the TSCS is selection consistent for the identification of the nonzeros of both the coefficient matrix and the precision matrix. Simulation studies are carried out to compare TSCS with the existing state-of-the-art methods, which demonstrates that the TSCS approach outperforms the existing methods. As an illustration, the TSCS approach is also applied to a real dataset.

     

Effect of cerium addition on catalytic performance of PtSnNa/ZSM-5 catalyst for propane dehydrogenation

The effect of cerium addition on the catalytic performance of propane dehydrogenation over PtSnNa/ZSM-5 catalyst has been investigated by reaction tests and some physicochemical characterization such as XRD,BET,TEM,XPS,NH 3-TPD,H 2 chemisorption,TPR and TPO techniques.It has been found that with suitable amount of cerium addition,the platinum dispersion increased,while the carbon deposition tended to be eliminated easily.In these cases,the presence of cerium could not only realize the better distribution of metallic particles on the support,but also strengthen the interactions between Sn species and the support.Additionally,XPS spectra confirmed that more amounts of tin could exist in oxidized form,which was advantageous to the reaction.In our experiments,PtSnNaCe(1.1 wt%)/ZSM-5 catalyst exhibited the best catalytic performance.After running the reaction for 750 h,propane conversion was maintained higher than 30% with the corresponding selectivity to propylene of about 97%.     

Multiple Homoclinic Solutions for Second‐Order Perturbed Hamiltonian Systems

In this paper, we study the second‐order perturbed Hamiltonian systems where is a parameter, is positive definite for all but unnecessarily uniformly positive definite for , and W is either asymptotically quadratic or superquadratic in x as . Based on variational methods, we prove the existence of at least two nontrivial homoclinic solutions for the above system when small enough.     

储能技术在风力发电中的应用

在分析风电输出波动问题的基础上,首先重点介绍了机械储能技术中的抽水蓄能和飞轮储能,电磁储能技术中的超导磁体储能和超级电容储能,电化学储能技术,并比较分析了各自在储存容量、功率、效率、响应速度、存储周期和转换次数等重点参数上的性能,其次分析了风力发电对储能技术的关键要求,然后提出了适合风电的多元混合储能方案来改善风电的可靠性和稳定性问题,最后通过多元混合储能方案在实际风力发电运行中的应用证明了储能技术能够切实改善风电输出的稳定性和有效的储能调峰等作用提高风电的利用率.     

空芯光纤气体传感气室的优化设计

波导式光学吸收腔在气体和液体浓度测量等领域有广泛的应用前景。空芯光纤作为光学吸收腔具有很多优点。空芯光纤的参数与传感系统的性能有直接的关系。提出了一种能同时考虑空芯光纤的损耗和系统信噪比的数学模型。从理论上分析了光纤的长度、内径、目标气体浓度以及输入光场能量分布等因素对传感系统信号输出强度和灵敏度的影响。给出的最优化参数为提高系统灵敏度和补偿系统误差提供了参考。     

High Yield of Supergiant Vesicles on Glyoxylic Acid Modified Aluminum Electrode

Supergiant vesicles are useful for investigating the interactions between lipid memebranes and collodial particles or macromolecules. Producing supergiant vesicles using the electroformation method lead to extraordinary findings in this work. The glyoxylic acid modified aluminum (GA-Al) electrode was prepared by the electro-reduction in an oxalic acid solution. High yield of supergiant vesicles with diameters >100 µm are successfully formed on a GA-Al electrode under an alternative current (AC) electric field. In contrast to platinum and indium tin oxide, which have been mainly used so far, this GA-Al electrode is preferable for the electroformation of egg phosphatidylcholine (EggPC) supergiant vesicles.     

Determination of aromatic amines from textiles using dispersive liquid–liquid microextraction

A dispersive liquid–liquid microextraction procedure coupled with GC‐MS is described for preconcentration and determination of banned aromatic amines from textile samples. Experimental conditions affecting the microextraction procedure were optimized. A mixture of 30 μL chlorobenzene (extraction solvent) and 800 μL ACN (disperser solvent), 5 min extraction time, and 5 mL aqueous sample volume were chosen for the best extraction efficiency by the proposed procedure. Satisfactory linearity (with correlation coefficients >0.9962) and repeatability (<9.78%) were obtained for all 20 aromatic amines; detection limits attained were much lower than the standardized liquid–liquid method. The proposed method has advantages of being quicker and easier to operate, and lower consumption of organic solvent.     

Large-scaled star-shaped α-MnS nanocrystals with novel magnetic properties

A cooperative thermal decomposition route to large-scaled star-shaped α-MnS nanocrystals, which show novel magnetic properties, i.e., a high blocking temperature (275 K) and a large coercive field (1573 Oe), is reported.