商品价格极端波动影响期现价格联动及套期保值吗?

试图将极端价格波动成因归结于系统惯性因素和极端随机冲击因素,借助Copulas-GARCH模型,将其引入期货和现货价格联动的计量模型之中,以持有便利收益高的沪铜作为研究样本,实证研究发现:1)引入极端价格波动因素后将显著提升价格联动计量模型的解释能力;2)当负向基差扩大,系统惯性因素引起商品价格剧烈变动,将导致市场联动性下降,而极端随机冲击却具有正向效应,即市场受到极端随机冲击时会增强期现价格联动关系;3)极端随机冲击效应中正向冲击和负向冲击的非对称性特征不显著;4)考虑极端价格波动效应可明显降低生产企业的套期保值成本.研究结论对于商品期货市场套期保值等期货交易具有重要管理启示.     

关于K_(2n)-E(C_m)的点可区别边色数

图G的一个k-正常边染色f被称为点可区别边染色是指任何两点的点及其关联边的色集合不同,所用最小的正整数k被称为G的点可区别边色数,记为X'_(vd)(G).用k_(2n)-E(C_m)表示2n阶完全图删去其中一条m阶路的边后得到的图,得到了K_(14)-E(C_4),K_(16)-E(C_4),K_(18)-E(C_5),K_(20)-E(C_5)的点可区别边色数分别为14,16,18,20.     

Study on the Joint Toxicity of BPZ,BPS, BPC and BPF to Zebrafish

Bisphenol Z (BPZ), bisphenol S (BPS), bisphenol C (BPC), and bisphenol F (BPF) had been widely used as alternatives to bisphenol A (BPA), but the toxicity data of these bisphenol analogues were very limited. In this study, the joint toxicity of BPZ, BPS, BPC, and BPF to zebrafish (Danio rerio) was investigated. The median half lethal concentrations (LC50) of BPZ, BPS, BPC, and BPF to zebrafish for 96 h were 6.9 × 10⁵ µM, 3.9 × 10⁷ µM, 7.1 × 10⁵ µM, and1.6 × 10⁶ µM, respectively. The joint toxicity effect of BPF–BPC (7.7 × 10⁵–3.4 × 10⁵µM) and BPZ–BPC (3.4 × 10⁵–3.5 × 10⁵µM) with the same toxic ratio showed a synergistic effect, which may be attributed to enzyme inhibition or induction theory. While the toxicity effect of the other two bisphenol analogue combined groups and multi-joint pairs showed an antagonistic effect due to the competition site, other causes need to be further explored. Meanwhile, the expression levels of the estrogen receptor genes (ERα, ERβ1) and antioxidant enzyme genes (SOD, CAT, GPX) were analyzed using a quantitative real-time polymerase chain reaction in zebrafish exposure to LC₅₀ of BPZ, BPS, BPC, and BPF collected at 24, 48, 72, and 96 h. Relative expression of CAT, GPX, and ERβ1 mRNA declined significantly compared to the blank control, which might be a major cause of oxidant injury of antioxidant systems and the disruption of the endocrine systems in zebrafish.     

Pyrolysis study of poplar biomass by tunable synchrotron vacuum ultraviolet photoionization mass spectrometry

Pyrolysis is one of the most important methods to convert biomass into biofuel, which is a potential substitute for fossil fuel. The pyrolysis process of poplar biomass, a potential biofuel feedstock, has been studied with tunable synchrotron vacuum ultraviolet (SVUV) photoionization mass spectrometry (PIMS). The mass spectra at different photon energies, temperatures, and time-evolved profiles of selected species during poplar pyrolysis process were measured. Our results reveal that poplar is typical of hardwood according to its relative contents of three lignin monomeric precursors. As temperature increases from 300 to 700 °C, the overall intensities of pyrolysis products decrease due to the gas-phase cracking. Observed intensities of syringyl and guaiacyl subunits of lignin in poplar at low temperature present different trends: the intensities of syringyl subunits of lignin undergo an increase firstly and then a decrease, whereas those of guaiacyl subunits of lignin show decrease continuously. Time-dependent data demonstrate that hemicellulose pyrolysis is faster than lignin in poplar. This work reports a new application of SVUV PIMS in biomass pyrolysis, which performs very well in products analysis.     

High optical-efficiency integral imaging display with a gradient-aperture parallax barrier

We propose a one-dimensional integral imaging (1DII) display that consists of a display panel and a gradient-aperture parallax barrier. The gradient-aperture parallax barrier is symmetrical, and its slit widths gradually increase from both sides to the middle. The leftmost and rightmost slits are used to fix the viewing angle, whereas the other slits are used to increase the optical efficiency. A prototype of the proposed 1DII display is developed. Its optical efficiency is higher than that of the conventional display, but the viewing angles are the same.     

激光诱骗干扰装备实弹对抗训练方法研究

随着训练需求的不断变化和深入,激光诱骗干扰装备训练迫切需要探索新的更加符合实战要求的训练方法。在分析激光诱骗干扰装备干扰原理和激光半主动制导武器作战过程的基础上,以制式激光末制导炮弹为对抗目标,设计了激光诱骗干扰装备实弹对抗训练方法,为激光诱骗干扰装备的干扰性能检验和战法运用的完善提供了新的训练思路,对进一步开展类似训练提供了参考。     

Optimizing Design for the Traveling Wave Electrodes in Low-Drive High-Speed Electro-Optic Polymer Modulators

Electro-optic (EO) polymer modulators are very promising in the realization of cost-effective and high-performance optical transmissions. In this article, general strategies and specific designs of the traveling wave electrodes in EO polymer modulators were presented to reduce the modulator drive power while maintaining a broadband response. The optimum device parameters and corresponding conditions were estimated using finite element method based on electrode design. In calculating the results, the comprehensive characteristics of polymer modulator with 1.21 V half-wave voltage and 91 GHz bandwidth was demonstrated with electro-optic interaction length is 20 mm, electro-optic coefficient is 55 pm/V, and operation wavelength is 1.319 μm. These results agree with the 0.8 V half-wave voltage and 30 mm electro-optic interaction length reported in Science. In the five designs presented, a hybrid electrode structure combining CPW and microstrip lines were advanced. The characteristics of this structure are like that of microstrip lines with a single-arm electrode on one arm of the waveguide, but it solves the problem of microstrip to coaxial line transition and corona polarization.     

Establishment of an integrated data fusion method between the colorimeter and near-infrared spectroscopy to discriminate the stir-baked Gardenia jasminoides Ellis

Stir-heating is a common method to process Gardenia jasminoides Ellis. The processing of the G. jasminoides Ellis which do not meet the regulated requirements can result in the unqualified products, finally decreasing the efficacy of the drug. To guarantee the quality of the stir-baked G. jasminoides Ellis, a rapid and efficient method to discriminate the qualified stir-baked G. jasminoides Ellis from the unqualified was developed based on the middle level data fusion. 61 batches of qualified and unqualified stir-baked G. jasminoides Ellis were collected and analyzed using colorimeter and near-infrared spectroscopy, separately. L*, A*, and B* were apparent features that quantitatively described the characteristics of samples. The latent variables of partial least squares discriminant analysis model were extracted as the features of near-infrared spectroscopy. The extracted features from colorimeter and near-infrared spectroscopy were fused and a discriminant model was built using partial least squares discriminant analysis method. Accuracy, sensitivity, and specificity were used to evaluate the ability of classification. As a result, the accuracy, sensitivity, and specificity of the optimal partial least squares discriminant analysis model based on fused data were all equal to 1. It demonstrated that the developed method can be capable of discriminating the qualified stir-baked G. jasminoides Ellis from the unqualified. Compared with classification model results using color parameters or near infrared data alone, this data fusion strategy greatly improved the accuracy of classification.     

Structure and Properties of Ultradrawn Polylactide/Thermoplastic Polyurethane Elastomer Blends

Highly oriented self-reinforced 80/20 blends of polylactide (PLA)/thermoplastic polyurethane elastomer (TPU) were successfully fabricated through solid hot stretching technology. Different from the isotropic sample, stress rose rapidly in a low strain region, and exhibited strain hardening for the drawn samples of the PLA/TPU blend. Superior mechanical properties of the blend, with the notched Charpy impact strength 150 KJ/m², and tensile strength 197 MPa, were achieved. With increasing hot stretch ratio, the storage modulus increased, the glass transition temperatures of the PLA-rich phase and TPU-rich phase in the blends moved to higher temperatures, and the melting temperature and crystallinity of the blend increased, indicating the stress-induced crystallization of the blend during drawing. The longitudinal fracture surfaces of the blends at different stretch ratios exhibited orderly arranged fibrillar bundle structure, which contributed to the significantly higher strength and toughness of the blend.     

New higher-order compact finite difference schemes for 1D heat conduction equations

In this paper, we present two higher-order compact finite difference schemes for solving one-dimensional (1D) heat conduction equations with Dirichlet and Neumann boundary conditions, respectively. In particular, we delicately adjust the location of the interior grid point that is next to the boundary so that the Dirichlet or Neumann boundary condition can be applied directly without discretization, and at the same time, the fifth or sixth-order compact finite difference approximations at the grid point can be obtained. On the other hand, an eighth-order compact finite difference approximation is employed for the spatial derivative at other interior grid points. Combined with the Crank–Nicholson finite difference method and Richardson extrapolation, the overall scheme can be unconditionally stable and provides much more accurate numerical solutions. Numerical errors and convergence rates of these two schemes are tested by two examples.