The structure,vacancy characteristics,and magnetic properties of GdMn1-xCrxO3 ceramics

To investigate the evolution of the structural and enhanced magnetic properties of GdMnO₃ systems induced by the substitution of Mn with Cr, polycrystalline GdMn_1-xCr_xO₃ samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn_1-xCr_xO₃ compounds with single-phase structures crystallize well and that Cr³⁺ ions entering the lattice sites of GdMnO₃ induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn_1-xCr_xO₃ ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn_1-xCr_xO₃. The enhanced magnetization of GdMn_1-xCr_xO₃ is closely related to the vacancy defect concentration.     

四川盆西平原区裸土扬尘中Pb、Cd化学形态的尺度效应

为了探究四川盆西平原区裸土扬尘中Pb、Cd总量与其尺度效应的关系,模拟土壤样品的Pb、Cd污染,通过实验室内的模拟起尘研究系统对土壤样品开展试验,对各粒级悬浮颗粒物中Pb、Cd的赋存状态及其尺度效应进行分析,并进一步对土壤中的黏土颗粒进行提取分析,结果表明:试验条件下,随着粒径的减小,Pb、Cd在四川盆西平原区裸土扬尘...     

电积钴板微观组织结构及力学性能对比

研究了3种电积钴板的微观组织结构和力学性能之间的差异,采用X射线衍射仪和扫描电子显微镜分析了3种电积钴板的择优取向、晶体结构和微观组织形貌;并分析了3种电积钴板的强度、硬度和韧性。结果表明：3种电积钴板均是密排六方结构（hcp）的纯钴相,晶粒取向随机。A-Co板沉积层均匀致密、孔洞较少,而B-Co板和C-Co板的沉积层较为分散且存在大量的孔洞。同时A-Co板表面的平均晶粒尺寸最小,沉积层晶粒大小分布均匀,B-Co板表面的平均晶粒尺寸最大,沉积层晶粒大小分布不均匀。3种电积钴板截面的始极片都是柱状晶结构,且始极片两侧的生长方式不同。由力学性能分析发现A-Co板的抗拉强度和硬度均高于其它2种钴板,但是韧性较差。综上所述,A-Co板的品质要明显优于B-Co板和C-Co板的品质。     

负载型酞菁对水中十二烷基苯磺酸钠的催化降解

以磺化酞菁铁、磺化酞菁锰为催化剂,Ｈ２Ｏ２ 为氧化剂,对水溶液中十二烷基苯磺酸钠进行了高效催化降解。并在此基础上,建立了负载型酞菁对水中十二烷基苯磺酸钠的催化体系,这些负载型的催化剂能够重复使用且其催化性能几乎没有丢失。因此,该体系可望成为一种实用的处理污水的新方法。     

Sidelobe suppression in NC-OFDM systems using constellation adjustment

In this letter, a new method for sidelobe suppression in non-contiguous orthogonal frequency division multiplexing (NC-OFDM) systems is proposed. Unlike the conventional approach, sidelobes are suppressed by iteratively adjusting the constellation points for the subcarriers that are close to the edges of the used bandwidth. The constellation points corresponding to the maximum sidelobe suppression are chosen for transmission. Simulation results show that the proposed algorithm yields good performance improvement in terms of sidelobe suppression, and does not have a significant impact on the peak-to-average power ratio (PAPR).     

三冗余控制器在核电汽轮机保护系统中的应用

本文介绍了三冗余控制系统在哈汽田湾核电三号汽轮机组保护系统(ETS)的应用情况,着重阐述了系统的结构、原理、特点,并对Micronet TMR系统与一般三冗余控制系统的区别做出介绍。     

厚薄承台界定的新方法和梁式模型法的修正

大量的试验与研究结果均表明,梁式模型法适用于多桩薄承台设计,对于厚承台并不适用。通过对国内外桩基承台试验数据统计,确定空间桁架方法和梁式模型方法应用于承台的界限,也即如何定义"薄"承台和"厚"承台;并且通过对试验数据的数学统计,考虑承台底层纵筋对抗剪和抗冲切的有利作用,对梁式模型法的冲切和剪切公式进行了修正。     

Reduction of nitro phenols using nitroreductase from E. coli in the presence of NADH

The reductions of nitrophenols catalyzed by nitroreductase from E. coli in the presence of NADH were investigated in this paper. 4-Aminophenol and 4-hydroxylaminophenol were found in the reductive products of 4-nitrophenol and the maximum reductive ratio was about 83.49% when the reaction time was 70 min; 4,6-dinitro-2-pimelie kelone was found in the reductive products of 2,4-dinitrophenol and the maximum reductive ratio was about 75.28% when the reaction time was 80 min; 2,4-dinitrophenol and 4,6-dinitro-2-pimelie kelone were found in the reductive products of 2,4,6-trinitrophenol and the maximum reductive ratio was about 62.08% when the reaction time was 100 min. The similar reductive ratios of nitrophenols were obtained under aerobic and anaerobic conditions. The results indicated that nitroreductase was an oxygen-insensitive enzyme.     

Optimal designs for linear MIMO transceivers using directional derivative

Optimal designs for minimising the combination of symbol estimation errors subject to lp-norm constraint are investigated. Instead of considering each constraint in a separate way, the authors develop a unifying framework to obtain the optimal solution by employing a directional derivative method. The sum or peak power constraint turns out to be the case of p=1 or prarrrarr. Simulation results demonstrate the effectiveness of the proposed algorithm. Moreover, based on directional derivative, the authors show that the minimisation of the determinant of the minimum mean-square error (MMSE) matrix and the maximisation of mutual information are equivalent criteria.     

石化余热锅炉补燃系统电气控制技术改造

炼油企业余热锅炉补燃系统电气控制回路设计存在的缺陷,引起一次装置停车事故,只因余热锅炉补燃系统电气控制一开一备两台风机联锁不可靠,在事故状态下不能保证备用电动机起动。分析联锁电路存在的问题,提出合理的术改造措施。