Bromodomain-like折叠类型模板的设计

针对折叠类型分类中所选天然模板普适性不足的问题,提出了Bromodomain-like折叠类型模板的设计方法.选SCOPe Astral 2.03序列相似度小于40%并且分辨率高于0.25 nm的52个可用Bromodomain-like折叠样本,基于多结构比对结果及数据分析,建立了折叠类型家族模板的设计方法.利用系统聚类方法构建了家族模板的系统聚类图,提出了蛋白质折叠类型模板的设计方法,并用于该折叠类型的模板设计.结果表明：设计模板具有普适性,可用于蛋白质折叠类型分类.     

一种高效二进前馈神经网络学习算法

为解决二进前馈神经网络(BFNN)缺乏高效实用学习算法的问题,提出一种新的融合自适应调节结构和权值的BFNN学习算法.该算法借鉴并改进了极限学习机(ELM)方法,可以高效地训练单隐层的BFNN来解决分类问题.为了满足网络的训练精度,算法可以自动增加隐层神经元个数和调节网络隐层及输出层神经元权值;同时为了提高网络的泛化精度,算法通过建立二进神经元敏感性作为度量隐层神经元重要性的尺度,自动地裁剪重要性小的神经元,并对裁剪损失的信息进行补偿.实验结果验证了该算法在处理离散分类问题时的可行性和有效性.     

天然气互换性多组分配气计算及软件开发

随着我国天然气行业的发展,城市天然气多气源供气现象将长期存在。在天然气互换性问题基础上,为满足互换性实验的要求,在实验室得不到供应各地方实际气源气的前提下,以北京地区为例,对各气源天然气进行多组分配气计算并编写相关软件,得到不同配气方案下各气源天然气的实验配制气。通过分析不同配气方案下配制气的燃烧特性参数,并结合天然气互换性实验系统的要求甄选出了最佳配气方案。     

增材制造技术粉床的数值模拟与分析

选择性激光烧结等增材制造工艺中粉床特性对成型工艺有重要影响。针对颗粒粒径分布类型和层厚等对粉床特性有影响的问题,通过分析增材制造技术中粉床填充过程,提出了一种基于离散元法的增材制造粉床的数值模拟分析方法,分析论述了不同粒径分布和不同层厚对粉床填充性能的影响。结果表明：单一粒径粉床和粒径高斯分布粉床的填充密度和平均配位系数均随着层厚的增大而增大,最后趋于稳定;单一粒径粉床和粒径高斯分布粉床的填充密度和平均配位系数在层厚为80μm和400μm时均大致相等,在其它层厚时,粒径高斯分布粉床的填充密度高于单一粒径粉床的填充密度,且差值随着层厚的增大先增大后减小;单一粒径粉床的平均配位系数高于粒径高斯分布粉床的平均配位系数,且差值随着层厚的增大先增大后减小。这些研究结果可为增材制造粉床颗粒粒径分布类型和层厚选取提供参考依据。     

Experimental characterization of the bipolar effect on P-hit single-event transients in 65 nm twin-well and triple-well CMOS technologies

Single-event charge collection is controlled by drift, diffusion and the bipolar effect. Previous work has established that the bipolar effect is significant in the p-type metal-oxide-semiconductor field-effect transistor (PMOS) in 90 nm technology and above. However, the consequences of the bipolar effect on P-hit single-event transients have still not completely been characterized in 65 nm technology. In this paper, characterization of the consequences of the bipolar effect on P-hit single-event transients is performed by heavy ion experiments in both 65 nm twin-well and triple-well complementary metal-oxide-semiconductor (CMOS) technologies. Two inverter chains with clever layout structures are explored for the characterization. Ge (linear energy transfer (LET) = 37.4 MeV cm²/mg) and Ti (LET = 22.2 MeV cm²/mg) particles are also employed. The experimental results show that with Ge (Ti) exposure, the average pulse reduction is 49 ps (45 ps) in triple-well CMOS technology and 42 ps (32 ps) in twin-well CMOS technology when the bipolar effect is efficiently mitigated. This characterization will provide an important reference for radiation hardening integrated circuit design.     

Synthesis of calcium silicate hydrate based on steel slag with various alkalinities

This study aimed to improve the hydraulic potential properties of the slag. Therefore, a method of dynamic hydrothermal synthesis was applied to synthesize calcium silicate hydrate. The phases and nanostructures were characterized by XRD, FTIR, TEM, and BET nitrogen adsorption. The infl uence of alkalinity of steel slag on its structures and properties was discussed. The experimental results show that, the main product is amorphous calcium silicate hydrate gel with fl occulent or fi brous pattern with a BET specifi c surface area up to 77 m2/g and pore volume of 0.34 mL/g. Compared with low alkalinity steel slag, calcium silicate hydrate synthesized from higher alkalinity steel slag is prone to transform to tobermorite structure.     

基于16S rRNA 基因的戈登氏菌演化分析

探讨19种戈登氏菌共31株间16S rRNA基因演化关系。利用16S rRNA基因序列进行相似性分析和同源性比对,并运用Neighbor-Joining法构建进化树,进行演化分析。其中13条16S rRNA基因序列来自临床分离株,其他16S rRNA基因序列来自Genbank。结果表明：13株临床分离菌株包含4株Gordonia paraffinivorans,6株Gordonia bronchialis 和3株 Gordonia sputi,临床分离株的相似性百分比为93．5％-99．7％;16S rRNA基因序列在戈登氏菌不同种间存在较为明显的差异性（2％—6．2％）,可将临床分离株鉴定到种。进化分析结果显示：戈登氏菌分为两大类群,三种临床分离株在演化上按出现的先后依次为Gordonia bronchialis、Gor-donia sputi、Gordonia paraffinivorans。所做研究可为戈登氏菌相关疾病的流行、预防、治疗和控制提供一定的参考。     

相移光纤光栅横向受力传感特性研究

对相移光纤光栅(PS-FBG)的横向受力特性进行了理论和实验研究.采用传输矩阵法分析了PS-FBG的传输特性,并建立了光栅横向受力数学模型.理论分析表明,光栅透射谱阻带中的透射窗口在横向受力时会产生光谱分裂,且分裂距离与所受横向压力的大小成正比关系.实验在0~1 N的横向压力条件下,获得了1.4×10-3N/mm的灵敏度,实验结果与理论模拟相符.     

Spray-coated PDMS/PVDF composite membrane for enhanced butanol recovery by pervaporation

In this study, spray-coating was used to prepare dihydroxypolydimethylsiloxane (PDMS) composite membranes with high flux and separation factor for biobutanol recovery from aqueous solution. A thin, smooth, and defect-free PDMS layer was prepared by spray-coating on polyvinylidene difluoride ultrafiltration membrane with little PDMS penetration. The effects of process parameters for membrane fabrication and pervaporation on membrane performance were investigated. A membrane with 2 μm active layer was obtained with a high flux of 1306.9 g/m² h. The optimal membrane with the highest pervaporation separation index (PSI) (19.15 kg/m² h) showed a total flux of 530.6 g/m² h and a separation factor of 36.1 at 37°C, and a PSI of 65.61 kg/m² h and a flux of 1927.0 g/m² h at 70°C. Membrane performance was affected by feed composition and temperature. Acetone-butanol-ethanol solution and fermentation broth gave lower butanol fluxes and separation factors compared to butanol model solution.     

基于响应面法的双边长初级永磁直线同步电机多目标优化设计

永磁直线同步电机由于存在边端效应以及齿槽效应,在运行中不可避免地产生推力波动。针对高速大推力密度应用场景,对一种双边长初级PMLSM开展了优化设计。将有限元法与解析法结合,首先独立分析了轴向长度、极弧系数和初级轭部高度等单个参数对电机水平推力和推力波动的影响,并进一步采用Taguchi法筛选显著性较高的结构参数。在此基础上,以提高电磁推力、减小推力波动为优化目标对电机进行响应面分析,得到最终的电机尺寸优化参数。最后制作样机并搭建实验平台,验证了所提优化方法的有效性。