Real phase retrieval from unordered partial frame coefficients

We study the signal recovery from unordered partial phaseless frame coefficients. To this end, we introduce the concepts of m-erasure (almost) phase retrievable frames. We show that with an m-erasure (almost) phase retrievable frame, it is possible to reconstruct (almost) all n-dimensional real signals up to a sign from their arbitrary N ? m unordered phaseless frame coefficients, where N stands for the element number of the frame. We give necessary and sufficient conditions for a frame to be m-erasure (almost) phase retrievable. Moreover, we give an explicit construction of such frames based on prime numbers.     

一次大型直流电源系统割接

介绍了一次大型直流电源系统割接，在保证通信不中断的前提下，采用新、旧电源系统并机，通过割接电缆的方式实现电源系统的原位置割接。并对电源系统割接前、割接过程中应注意的事项作了说明。     

In Situ Design of High-Performance Dual-Phase GeSe Thermoelectrics by Tailoring Chemical Bonds

Composite engineering favors high thermoelectric performance by tuning the carrier and phonon transport. Herein, orthorhombic and rhombohedral dual-phase GeSe are designed in situ by tailoring chemical bonds. Atom probe tomography verifies the coexistence of a covalently bonded orthorhombic phase and a metavalently bonded rhombohedral phase in GeSe-InTe alloys. The production of the rhombohedral phase simultaneously increases the carrier concentration, the carrier mobility, the band degeneracy, and the density-of-states effective mass due to the reduced formation energy of cation vacancies and the improved crystal symmetry. These attributes are beneficial to a high-power factor. In addition, the thermal conductivity can be significantly reduced due to the intrinsically strong lattice anharmonicity of the metavalently bonded phase, the interfacial acoustic phonon mismatch across different bonding mechanisms, and the phonon scattering at vacancy-solute clusters. Moreover, the metavalently bonded phase embraces higher solubility of dopants that enables the further optimization of properties by Cd-Ag doping, resulting in a zT of 0.95 at 773 K as well as enhanced strength and ductility in dual-phase Ge_0.94Cd_0.03Ag_0.03Se(InTe)_0.15. This work indicates that in situ design of dual-phase composites by tailoring chemical bonds is an effective method for enhancing the thermoelectric and mechanical properties of GeSe and other p-bonded chalcogenides.     

Breakthrough of natural organic matter from fixed bed adsorbers: investigations based on size-exclusion HPLC

Fixed bed adsorption experiments were performed using four granular activated carbon (GAC) columns designed by packing two size ranges of pulverized and sieved Filtrasorb 400 (d=0.5-0.59 and 1.0-1.19 mm) to two bed depths (L=10 and 20 cm), respectively. Continuous supplying of river water containing a lower content of natural organic matter (NOM) allowed investigation of the breakthrough of aqueous natural organic matrices assessed with lumped quality indices of total dissolved organic carbon (DOC) and ultraviolet absorbance at 260 nm (UV260). The capability of GAC columns in dealing with sudden rise in the load of influent NOM was also displayed by intermittently adding to the influent river water a peaty field groundwater that contained a higher content of NOM. Besides, assisted by the size-exclusion HPLC (SEHPLC), changes in the apparent molecular weight distribution of NOM along the bed depth of GAC columns were evaluated, and an important finding revealing relatively even adsorption for adsorbable NOM constituents within the entire molecular weight range of 1000-5200 g mol⁻¹ as PSS (polystyrene sulfonates) detected for the river and groundwater NOM was obtained. Furthermore, using a previously proposed hypothetical multi-component approach incorporating the ideal adsorbed solution theory and a plug flow homogeneous surface diffusion model, the observed concentration profiles of the river water NOM were predicted.     

酸性离子液体催化脂肪酸甲酯聚合制备二聚酸甲酯

 以 Brönsted-Lewis 酸性离子液体为催化剂, 用于催化生物柴油中不饱和脂肪酸甲酯聚合制备二聚酸甲酯反应, 考察了催化剂种类、催化剂用量、反应温度和时间等因素对聚合反应性能的影响, 得到较佳的反应条件. 结果表明, 当以 1-(3-磺酸)-丙基-3-甲基咪唑氯锌酸盐[HO3S-(CH2)3-mim]Cl-ZnCl2 (ZnCl2 摩尔分数为 0.67) 为催化剂, 生物柴油 15 g, m(生物柴油):m(离子液体) = 15:1, 于 240 oC 下反应 6 h 时, 二聚酸甲酯收率为 63.2%, 其中三聚体含量小于 5%. 另外, 该催化剂重复使用 5 次后, 二聚酸甲酯收率仍超过 63%, 表明其具有较好的重复使用性能. 离子液体的 Brönsted 和 Lewis 酸位的协同效应显著提高了其催化活性.     

内应力对顺-1,4-聚丁二烯结晶的影响

本工作用线膨胀仪观察了顺-1,4-聚丁二烯(PB)生胶恒温及等速降温条件下的结晶行为,发现某些胶样在结晶前出现长度增加,而加热至结晶融化时出现长度收缩,随样品退火程度的增加所述现象逐渐减小,直至消失。本工作用含凝胶样品受外力作用后能产生内应力并生成束状结晶的模型来进行解释,其结果得到DSC的验证。     

填充丁腈共聚物的动态力学性质

本文研究了用石墨粉剂和二硫化钼粉剂填充的丁腈共聚物(含丙烯腈约40wt%)的动态力学性能,贮能模量E'_c、损耗模量E"_c损耗因子tanδ。讨论了填料的体积分数、高聚物和填料之间的相互作用对这些参数及松弛谱的影响。试用了一种模型计算这些复合材料中间相的E₁值。     

毫秒脉冲星PSR1953+29的引力四极辐射及其表面温度分布

本文考虑了天体自引力、内部运动及内应力;估算了最近发现的毫秒脉冲星PSR1953+29的引力四极辐射功率、共振线型四极天线截面、以及可能被天线吸收的功率量级,结果表明比过去认为最有希望的引力辐射源PSR0531+21要强约五个数量级,因此,PSR1953+29很有希望被探测到。我们还计算     

马来酸酐和苯乙烯的可逆加成-断链链转移聚合及新型嵌段共聚物的合成

马来酸酐和苯乙烯是被广为研究的一对电荷转移复合物 (Ｃｈａｒｇｅｔｒａｎｓｆｅｒｃｏｍｐｌｅｘ,简称ＣＴＣ) ,而且能通过通常的自由基聚合发生交替共聚[1] .所得的聚合物由于酸酐基团的存在 ,很易进行大分子改性得到具有某些特殊功能的高分子 .不过 ,所得共聚物的分子量难以控制且分子量分布也较宽 .近年来发展起来的“活性” 可控自由基聚合越来越为人们所关注 ,因为采用这种方法不仅可对聚合物的分子量进行设计 ,同时分子量分布也较窄 ,也不需要活性离子型聚合那样严格的聚合条件 .关于烯类单体的活性自由基聚合迄今主要有氮氧自由基…