Frame Synchronization Algorithm for LDPC Coded Burst Systems

We present a frame synchronization algorithm for low‐density parity‐check (LDPC) coded burst transmissions, which combines a conventional pilots‐assisted frame synchronization algorithm and a code‐aided algorithm based on the mean magnitude of the soft outputs from the LDPC decoder. With moderate computational complexity, the proposed algorithm is more efficient in bandwidth than conventional pilots‐assisted algorithms. When compared with other code‐aided algorithms, the proposed algorithm offers a better trade‐off between complexity and performance. Simulation results in the case of an 8‐PSK system with (1944, 972) LDPC code show that the proposed algorithm can achieve a performance equivalent to that of the perfect frame synchronization, with a bandwidth efficiency loss of 0.06 dB due to the use of pilot symbols.     

MATE-Type Proteins Are Responsible for Isoflavone Transportation and Accumulation in Soybean Seeds

Soybeans are nutritionally important as human food and animal feed. Apart from the macronutrients such as proteins and oils, soybeans are also high in health-beneficial secondary metabolites and are uniquely enriched in isoflavones among food crops. Isoflavone biosynthesis has been relatively well characterized, but the mechanism of their transportation in soybean cells is largely unknown. Using the yeast model, we showed that GmMATE1 and GmMATE2 promoted the accumulation of isoflavones, mainly in the aglycone forms. Using the tobacco BrightYellow-2 (BY-2) cell model, GmMATE1 and GmMATE2 were found to be localized in the vacuolar membrane. Such subcellular localization supports the notion that GmMATE1 and GmMATE2 function by compartmentalizing isoflavones in the vacuole. Expression analyses showed that GmMATE1 was mainly expressed in the developing soybean pod. Soybean mutants defective in GmMATE1 had significantly reduced total seed isoflavone contents, whereas the overexpression of GmMATE1 in transgenic soybean promoted the accumulation of seed isoflavones. Our results showed that GmMATE1, and possibly also GmMATE2, are bona fide isoflavone transporters that promote the accumulation of isoflavones in soybean seeds.     

In-situ synthesis of palladium-base binary metal oxide nanoparticles with enhanced electrocatalytic activity for ethylene glycol and glycerol oxidation

To achieve the better electrocatalytic activity and stability of Pd-base catalysts for ethylene glycol and glycerol oxidation reactions, a novel Pd-base binary PdCo oxides nanoparticles (PdPdO-CoO_x) was synthesized by in-situ oxidation of PdCo precursor. The strategy was simple, mild, green and efficient. The prepared nanoparticles exhibited a mutually connected, fused irregular nanoparticles in TEM. The as-synthesized PdPdO-CoO_x (1:4) nanoparticles displayed prominent catalytic activity (5.82 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pd}}^{\mathrm{?}1}$ for ethylene glycol and 5.16 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pd}}^{\mathrm{?}1}$ for glycerol) for ethylene glycol and glycerol oxidation reactions in alkaline solution compared to the commercial Pt/C (1.64 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pt}}^{\mathrm{?}1}$ for ethylene glycol and 1.48 A $\mathrm{m}{\mathrm{g}}_{\mathrm{Pt}}^{\mathrm{?}1}$ for glycerol) catalyst. The improved electrocatalytic activity of PdPdO-CoO_x catalyst mainly ascribes to the producing Strong Metal-Support Interactions (SMSI) between PdO-CoO_x and Pd nanoparticles, the synergistic effect between PdO and CoO_x and the presence of CoO_x promoved hydroxyl adsorption at lower potentials. Combined with the simple synthetic method, lower cost and good performance, PdPdO-CoO_x is a promising catalyst for direct fuel cells.     

振动磨机环扇形激振板的横向振动与稳定性分析

振动磨机的磨粉效果与激振系统动力学响应有较大关系,其激振系统的横向振动和稳定性研究具有重要的理论意义.根据弹性薄板小挠度理论和哈密顿原理,建立振动磨机环扇形激振板的运动微分方程.采用微分求积法离散方程和边界条件,计算得到环扇形板前三(四)阶无量纲复频率随无量纲角速度的变化情况,分析半径比和扇形角对环扇形板横向振动的影响.结果 显示在不同的旋转角速度情况下,环扇形板会发生发散失稳和颤振耦合失稳现象.该结论为振动磨机的设计与研究提供了一定的理论基础.     

工程建设招标风险及其管控优化策略

建设项目施工中,招标管理是成本造价管理的重要内容,合理的招标管理有利于施工单位准确掌握项目施工进度,有效控制成本,同时使建设施工质量全面提高.因而,建设项目施工中,严格落实招标管理措施,提高招标管理质量与水平,以顺利进行项目建设.基于此,针对建设项目招标风险与管控优化策略相关知识,进行简单的分析.     

基于观测器的直流伺服电机速度控制

针对直流伺服电机速度控制中经常出现的电机参数变化和外部扰动导致系统性能下降的现象,将外来的扰动转矩和由电机参数变化产生的扰动转矩结合起来,提出了一种等效外来扰动转矩观测器,并基于此观测方法,进而采用电流反馈控制消除观测误差。给出了该速度控制方法的详细推导过程。仿真数据验证了其切实有效性,     

中空纤维膜吸收法脱除H2S的实验研究

研究了用中空纤维膜组件脱除天然气中的H2S的吸收过程.采用疏水性聚丙烯中空纤维膜(HFPPM)制成膜组件,以甲基二乙醇胺(MDEA)水溶液作为吸收剂,考察了吸收液浓度、吸收液流速、气相流速等因素对H2S膜吸收过程的影响.实验结果表明,质量分数为30%的MDEA吸收液在流速为78.1 ml/s,气速为0.064 m/s时,H2S的脱除率为95.8%,H2S的总传质系数为4.8×10-8mol·(m2·s·Pa)-1;质量分数为35%的MDEA在同样的条件下H2S脱除率达98.1%.而且在实验的较宽天然气H2S浓度范围内,MDEA吸收剂H2S脱除率保持在90%以上.实验证明膜吸收法也许是有良好发展前景脱除H2S的方法.     

V型多通道平板太阳能集热器的热性能研究

提出一种V型多通道平板太阳能集热器,对其建立稳态传热模型,利用Matlab软件编程进行求解,并进行实验测试验证模型的准确性.利用已验证的传热模型,模拟分析V型多通道平板太阳能集热器的结构和物性参数对其热性能的影响,结果表明当透明盖板和吸热体发射率变大时,集热器的集热效率会呈下降趋势;当V型槽顶角、吸热体长度及空气夹层厚...     

天然气掺混氢气在家用燃气具上燃烧的安全性及排放性能测试与评价

面对日益严峻的能源短缺和环境恶化问题,氢能作为绿色、高效且具有可持续性的柔性二次能源被广泛关注和研究。借鉴欧洲的电转气技术(power to gas),将可再生能源电解制成氢气后,以一定比例掺入到天然气管网中供给居民使用,被认为是改善城镇燃气质量与烟气排放的有效途径之一。因此,基于互换性理论分析了掺氢天然气作为家用燃气具燃料的掺氢比例,并基于12T基准天然气测试与验证了掺氢天然气在家用燃气具上燃烧的安全性能与排放性能。研究结果表明:①掺氢比例体积分数不应高于20%;②掺氢天然气在家用燃气具中燃烧的点火率、火焰稳定性与烟气排放性能全部合格,未发现安全性问题;③家用燃气具的烟气排放指标满足标准要求,并且随着氢气的体积分数增加,烟气中CO与NO_x排放量有所降低。