In-fiber Mach–Zehnder interferometer based on multi-mode fiber and up-taper for curvature sensing

A new type of curvature sensor comprises a stub of multi-mode fiber and an up-taper is proposed and demonstrated experimentally. The whole fabrication process is quite simple and the sensor head is cost effective. Measurement results show that it has a maximum curvature sensitivity of −61.877 nm/m⁻¹ at 1.1718 m⁻¹ (the highest value of reported papers among in-fiber Mach–Zehnder interferometers) and −9.2115 nm/m⁻¹ from 0.865 m⁻¹ to 1.1172 m⁻¹. Temperature sensitivity of 89.01 pm/°C within the range of 20–80 °C has also been achieved, which implies the possibility for measurement of temperature.     

Maximum entropy networks are more controllable than preferential attachment networks

A maximum entropy (ME) method to generate typical scale-free networks has been recently introduced. We investigate the controllability of ME networks and Barabási–Albert preferential attachment networks. Our experimental results show that ME networks are significantly more easily controlled than BA networks of the same size and the same degree distribution. Moreover, the control profiles are used to provide insight into control properties of both classes of network. We identify and classify the driver nodes and analyze the connectivity of their neighbors. We find that driver nodes in ME networks have fewer mutual neighbors and that their neighbors have lower average degree. We conclude that the properties of the neighbors of driver node sensitively affect the network controllability. Hence, subtle and important structural differences exist between BA networks and typical scale-free networks of the same degree distribution.     

机械设计在CAD中图表资料的处理

机械设计中，有许多复杂的数据信息需要处理，本文主要探讨了齿轮传动中有关数据，表格和线圈的程序化处理方法。     

指数跟踪问题的广义双线性规划模型

本文对指数跟踪问题建立了一种广义的双线性规划模型,其中考虑了交易费用、持仓限制与重平衡问题.根据该模型的特殊结构,本文给出了近似规划算法,通过逐次逼近的线性规划求解最优指数跟踪问题.     

定容燃烧弹内压力振荡机理研究

本文基于一种具有较好发展前景的醚类汽油添加剂异丙醚(DIPE),在定容燃烧弹内研究了该燃料在不同初始压力下随当量比变化的压力振荡特性。实验结果表明,压力振荡强度随当量比增加呈先增大后减小的趋势,且在当量比1.4附近达到最大值;随初始压力增大,压力振荡的强度也增强。本文通过利用He和CO₂以不同掺混比替代N₂作为稀释气体,验证了定容燃烧弹内的压力振荡主要由压力波与火焰相互影响引起,火焰自加速和混合气能量密度对压力振荡有至关重要的作用。     

Studies on two-phase co-current air/non-Newtonian shear-thinning fluid flows in inclined smooth pipes

In this work, co-current flow characteristics of air/non-Newtonian liquid systems in inclined smooth pipes are studied experimentally and theoretically using transparent tubes of 20, 40 and 60 mm in diameter. Each tube includes two 10 m long pipe branches connected by a U-bend that is capable of being inclined to any angle, from a completely horizontal to a fully vertical position. The flow rate of each phase is varied over a wide range. The studied flow phenomena are bubbly flow, stratified flow, plug flow, slug flow, churn flow and annular flow. These are observed and recorded by a high-speed camera over a wide range of operating conditions. The effects of the liquid phase properties, the inclination angle and the pipe diameter on two-phase flow characteristics are systematically studied. The Heywood–Charles model for horizontal flow was modified to accommodate stratified flow in inclined pipes, taking into account the average void fraction and pressure drop of the mixture flow of a gas/non-Newtonian liquid. The pressure drop gradient model of Taitel and Barnea for a gas/Newtonian liquid slug flow was extended to include liquids possessing shear-thinning flow behaviour in inclined pipes. The comparison of the predicted values with the experimental data shows that the models presented here provide a reasonable estimate of the average void fraction and the corresponding pressure drop for the mixture flow of a gas/non-Newtonian liquid.     

The Analysis of Environmental Samples by Mass Spectrometry

Mass spectral analysis was carried out on shellfish samples taken in the vicinity of the Arrow oil spill at Chedabucto Bay, Nova Scotia. Oil samples were also analyzed, samples being obtained from the tanker and also from the beach.

After extraction of the oil and shellfish samples, group separations were made into aliphatic, aromatic and oxygenated fractions, which were analyzed separately by mass spectrometry. The validity of the group separations was established, since, in the analysis of the so-called aliphatic fraction, no evidence of aromatics could be seen by mass spectrometry.

On the other hand, polycyclic hydrocarbons were found in some of the aromatic fractions. Identification was based upon standard mass spectrometric analysis already performed on known examples of the polycyclics.

It was concluded that the possibility of oil contamination can be confirmed by the mass spectrometric analysis of appropriate samples. It was also concluded that the so-called control samples should have been taken at a greater distance from the oil spill.     

Discovery of a Novel Mycobacterial F‐ATP Synthase Inhibitor and its Potency in Combination with Diarylquinolines

The F₁F_O‐ATP synthase is required for growth and viability of Mycobacterium tuberculosis and is a validated clinical target. A mycobacterium‐specific loop of the enzyme's rotary γ subunit plays a role in the coupling of ATP synthesis within the enzyme complex. We report the discovery of a novel antimycobacterial, termed GaMF1, that targets this γ subunit loop. Biochemical and NMR studies show that GaMF1 inhibits ATP synthase activity by binding to the loop. GaMF1 is bactericidal and is active against multidrug‐ as well as bedaquiline‐resistant strains. Chemistry efforts on the scaffold revealed a dynamic structure activity relationship and delivered analogues with nanomolar potencies. Combining GaMF1 with bedaquiline or novel diarylquinoline analogues showed potentiation without inducing genotoxicity or phenotypic changes in a human embryonic stem cell reporter assay. These results suggest that GaMF1 presents an attractive lead for the discovery of a novel class of anti‐tuberculosis F‐ATP synthase inhibitors.     

基于自组织理论的GMDH神经网络算法及应用

本文在自组织控制论的基础上提出了成组数据处理的神经网络算法— GMDH算法 ,通过寻找最优复杂性 ,实现变量的自动筛选并得到明确的模型结构 .文章还给出了 GMDH网络用于分析和预测四川省电力需求状况的一个实例     

Asymmetric conjugate addition of carbonyl compounds to nitroalkenes catalyzed by chiral bifunctional thioureas

Readily available chiral thioureas derived from cyclohexane-1,2-diamine were prepared and found to be highly effective organocatalysts for the conjugate addition of aldehydes and ketones to nitroalkenes. Excellent enantioselectivities and yields were obtained for a variety of aryl and heteroaryl nitroalkenes. The base additives are essential for good yields and excellent enantioselectivities in this transformation. Based on new experimental evidence, a modified catalytic mechanism was proposed to rationalize the important role of the base additives.