Damage detection method for large structures using static and dynamic strain data from distributed fiber optic sensor

A method for damage detection applicable to large slender steel structures such as towers of large-scale wind turbines, long-span bridges, and high-rise buildings is presented. This method is based on continuous strain data obtained by distributed fiber optic sensor (FOS) and neural network (NN) analysis. An analytical model for cracked beam based on an energy balance approach was used to train a NN. The continuous static strains and the natural frequencies obtained from the distributed FOSs were used as the input to the trained NN to estimate the crack depths and locations. An experimental study was carried out on a cracked cantilever beam to verify the present method for damage identification. The cracks were inflicted on the beam, and static and free vibration tests were performed for the intact case and the damage cases. The distributed FOSs were used to measure the continuous strains. The damage estimation was carried out for the 5 damage cases using the NN technique. It has been found that the identified crack depths and locations agree reasonably well with the inflicted cracks on the structure.     

Rotor position estimation method of IPMSM using HF signal injection and sliding‐mode controller

This paper presents a simplified algorithm for the estimation of rotor position. A high‐frequency (HF) sinusoidal voltage is injected into the stator of a motor. An interior permanent magnet synchronous motor (IPMSM) has spatial saliency because the d‐ and q‐axis inductances are different from each other. The injected HF voltage is influenced by this saliency. Therefore, the rotor position is included in the stator current of the motor. The proposed method uses different synchronous reference frame transformations (SFTs) to extract the rotor position error between the estimated value and actual value. Also, a sliding‐mode controller is used for robustness against parameter variation and external disturbance. The experimental results confirm the effectiveness of the proposed method by showing waveforms of the rotor speed and position with load conditions. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Electrical properties of colloidal polyaniline‐2‐naphthalene sulfonic acid/graphene nanoparticle composite films

Polyaniline (PANI) nanocomposites containing different weight percentages of graphene (GR) are chemically prepared in the presence of β‐naphthalene sulfonic acid (NSA) and characterized using attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The characterization results suggest that the composites are formed via the interconnected fibrillar structure forming the semi‐crystalline/amorphous configuration by the β‐napthalene sulfonic acid (β‐NSA). The conductivities of the composites suggest that the composites undergo by two different regions of I and II before and after 378 K. The electrical conductivity of the composites is increased by increasing temperature. The dependence of conductivity on temperature implies that the PANI‐NSA/GR composites are organic semiconductors. POLYM. COMPOS., 35:60–67, 2014. © 2013 Society of Plastics Engineers     

Characterization and improved electrical conductivity of partially biodegradable polyaniline/poly(1,4‐butylene succinate) polymer composite films

Polyaniline/poly(1,4‐butylene succinate) (PANI/PBS) composites were prepared by the polymerization of aniline hydrochloride in the presence of different weight percentages of poly(1,4‐butylene succinate) biodegradable polymer by in situ deposition technique. The oxidative polymerization of aniline hydrochloride was performed by the drop wise addition of an aqueous ammonium persulfate solution. Fourier‐transform infrared spectroscopy, surface morphology, and thermogravimetric analyses indicated a strong interaction between PANI and PBS. The temperature‐dependent DC conductivity and biodegradable properties of PANI/PBS were also investigated. The results showed that both the conductivity and biodegradability of the composites was significantly increased by the addition of PBS. POLYM. COMPOS., 35:2010–2017, 2014. © 2014 Society of Plastics Engineers     

A leakage current mechanism caused by the interaction of residualoxidation stress and high-energy ion implantation impact in advancedCMOS technology

In this paper, we report abnormal junction leakage current characteristics in sub-quarter micron CMOS formed by OSELO-II isolation method and high-energy ion implantation for well formation. The phenomena have not been found in other isolation schemes such as single Si₃N₄ spacer OSELO (SSS-OSELO), modified conventional LOCOS (MLOCOS) and shallow trench isolation (STI). From the defect analysis and process simulation based on the actual recipe, the abnormal leakage is found to be generated from the lattice defects at the edge of field oxide and caused by the combination of oxidation stress, and high-energy ion implantation. A process condition in the high-energy ion implantation and isolation process is proposed to reduce the leakage current     

粘结指数在炼焦生产中的应用

煤气化公司通过控制粘结指数提高了冶金焦炭质量.文中讨论了粘结指数在炼焦生产中的作用及与炼焦煤灰分的关系.     

我是环保发明家

<正>环保绝不是卖"概念",只有将产品做好,并且解决实际问题,环保概念才能得以真正推广。随着环保、低碳类概念的普及,越来越多普通人开始从自己做起,关注环保,节能减耗。一些环保类的生活发明也层出不穷,而且往往比一些尖端科学发明更能引起大众的兴趣。2010年初,英国创刊最早的报纸《观察家报》推出一个新栏目,叫"环保发明家",主要集中于普通人对于环保的一些创意想法。比如有人把废弃的消防水管做成时尚的皮包,有人设计了踩踏发电的人行道发电系统……这些人来自各行各业,虽然很多所谓的发明看起来都微不足道,但如果将其运用于生活,将会节约大量能源,大大减少环境消耗。     

Cartier手工的秘密

<正>从绘制草图、铸模、雕琢、镶嵌到成型,一件闪耀的卡地亚高级珠宝,需要几千小时甚至更多时间才能诞生。顶级珠宝的背后,到底有怎样的手工秘密?和平街是巴黎最时尚美丽的街道,1897年,当卡地亚创始人阿尔弗雷德·卡地亚将店址定于和平街13号,百余年来,它从没对外关闭过敞开的大门,也未曾拒绝过任何一位进店的顾客。但顺着深红色地毯延伸而至的"阁楼",却不是人人都有幸能进入。内行人说,那是神秘的卡地亚高级珠宝工作坊的所在地。     

In situ-grown hexagonal silicon nanocrystals in silicon carbide-based films

Silicon nanocrystals (Si-NCs) were grown in situ in carbide-based film using a plasma-enhanced chemical vapor deposition method. High-resolution transmission electron microscopy indicates that these nanocrystallites were embedded in an amorphous silicon carbide-based matrix. Electron diffraction pattern analyses revealed that the crystallites have a hexagonal-wurtzite silicon phase structure. The peak position of the photoluminescence can be controlled within a wavelength of 500 to 650 nm by adjusting the flow rate of the silane gas. We suggest that this phenomenon is attributed to the quantum confinement effect of hexagonal Si-NCs in silicon carbide-based film with a change in the sizes and emission states of the NCs.     

The influence of polymer morphology on the performance of molecularly imprinted polymers

This is the first in-depth study examining the effect of morphology on the performance of 2-aminopyridine (2-apy) imprinted polymers. A series of polymers were prepared by varying the amount of crosslinking monomer (EGDMA) whilst the other polymer components remained constant. Physical characterisation was carried out using conventional techniques, such as nitrogen sorption porosimetry and solvent swelling studies. The use of a novel thermal desorption GC-MS technique suggested higher levels of polymer degradation with prolonged exposure to elevated temperatures for those polymers formed with lower amounts of EGDMA. The thermal desorption GC-MS profiles obtained correlated with the physical characteristics of the polymers, where higher levels of polymer bleed was found to occur with larger average pore diameters. Polymer physical characteristics were also found to correlate with the binding parameters (number of binding sites and polymer-template association energy) obtained from the Langmuir-Freundlich Isotherm (L-FI) and affinity distribution spectra (AD). The flexibility of the polymers formed from lower amounts of EGDMA combined the swelling effect of the solvents on the polymers resulted in an increase in affinity, which was both specific and non-specific in nature.