An experimental investigation of retro-reinforced clay brick arches

This paper describes the laboratory testing of eight 2.95m span segmental profile clay brick arches. Seven of the arches were strengthened with longitudinal intrados (soffit) reinforcement; the eighth was left unreinforced as an experimental control. Three of the arches also contained reinforcement to resist inter-ring shear. The barrel of each arch consisted of 3 rings of brickwork laid in stretcher bond; the compressive strength of the mortar used in the arch construction varied from 1.7 to 6.2 MPa. In each case a full width line load was applied incrementally to the arch extrados at quarter span until collapse occurred. Surface crack development and the vertical deflection profile of each arch were recorded at each load increment. In all cases, the longitudinal reinforcement was found to delay the onset of cracking and to increase the load carrying capacity. As expected, premature failure by ring separation was found to occur in the arches constructed with the weakest mortar without inter-ring reinforcement. Radial dowels were found to be the most effective means of preventing ring separation. The effect of the longitudinal reinforcement was found to be greatest in the arches where measures were taken to prevent ring separation

Effects of short-term memory and content representation type on mobile language learning

Due to the rapid advancements in mobile communication and wireless technologies, many researchers and educators have started to believe that these emerging technologies can be leveraged to support formal and informal learning opportunities. Mobile language learning can be effectively implemented by delivering learning content through mobile phones. Because the screen size of mobile phones is limited, the presentation of materials using different Learning Content Representation (LCR) types is an issue that needs to be explored. This study addresses the issue of content adaptation in mobile language learning environments. Two dimensions have been taken into consideration to identify a promising solution: instructional strategies (LCR types: written annotation and pictorial annotation), and learners’ cognitive models (verbal and visual short-term memory). Our findings show that providing learning content with pictorial annotation in a mobile language learning environment can help learners with lower verbal and higher visual ability because such learners find it easier to learn content presented in a visual rather than in a verbal form. Providing learning content with both written and pictorial annotation can also help learners with both high verbal and high visual abilities. According to the Cognitive Load Theory, providing too much information may produce a higher cognitive load and lead to irritation and a lack of concentration. Our findings also suggest that providing just the basic learning materials is more helpful to learners with low verbal and visual abilities

All-Solid-State Batteries Using Rationally Designed Garnet Electrolyte Frameworks

Functioning bulk-type all-solid-state batteries in a practical form factor with composite positive electrodes, using Al-substituted Li7La3Zr2O12 (LLZO) as the solid electrolyte, have been demonstrated for the first time. The devices incorporate bilayers composed of dense LLZO membranes and porous LLZO scaffolds infiltrated with LiNi0.6Mn0.2Co0.2O2 and other components as positive electrodes, combined with lithium anodes. The porous scaffolds are prepared using an easily scaled freeze-tape-casting method. The unidirectional pores of the scaffold facilitate infiltration of cathode components and shorten lithium ion diffusion path lengths, while the addition of a soft ionically conductive solid to the scaffold ensures good contact among the components

Polaronic effect in the x-ray absorption spectra of La1-x Ca x MnO3 manganites.

X-ray absorption spectroscopy (XAS) is performed to study changes in the electronic structures of colossal magnetoresistance (CMR) and charged ordered (CO) La1-x Ca x MnO3 manganites with respect to temperature. The pre-edge features in O and Mn K-edge XAS spectra, which are highly sensitive to the local distortion of MnO6 octahedral, exhibit contrasting temperature dependence between CMR and CO samples. The seemingly counter-intuitive XAS temperature dependence can be reconciled in the context of polarons. These results help identify the most relevant orbital states associated with polarons and highlight the crucial role played by polarons in understanding the electronic structures of manganites

Multi-realization of nonlinear systems

The system multi-realization problem is to find a state-variable realization for a set of systems, sharing as many parameters as possible. A multi-realization can be used to efficiently implement a multi-controller architecture for Multiple Model Adaptive Control (MMAC). We extend the linear multi-realization problem to nonlinear systems. The problem of minimal multi-realization of a set of MIMO systems is introduced and solved for feedback linearizable systems. ©2009 IEEE

Nematicidal, larvicidal and antimicrobial activities of some new mannich base imidazole derivatives

Purpose: To synthesize Mannich base imidazole derivatives, and evaluate their antimicrobial, nematicidal and larvicidal properties .Methods: Compounds 1a-g and 2a-g were prepared using a Mannich condensation method. The chemical structures of compounds 2a-g were confirmed by Fourier transform infrared spectroscopy (IR), proton nuclear magnetic resonance (1H-NMR), carbon nuclear magnetic resonance (13C-NMR), and mass spectrometry (MS) and elemental analyses. Compounds 1a-f and 2a-f were screened for antimicrobial properties using an agar diffusion method. The nematicidal activity of the compounds was evaluated against juvenile Meloidogyne javanica as test organism while larvicidal activity was assessed against the urban mosquito, Culex. Quinquefasciatus, using a standard bioassay protocol.Results: Compounds 1b, 1g, 2e and 2g were highly active against a few bacterial organisms compared with the reference antibacterial, ciprofloxacin while the antifungal activity of compound 2d was high compared with the reference, clotrimazole. Compounds 1c, 1e, 1g, and 2e showed high toxicity levels of larvicidal activity based their half maximal lethal dose (LD50) values. Compounds 1d, 1e, 1f, 1g, 2d and 2e were highly toxic to nematodes.Conclusion: Compounds 1b, 1g, 2e and 2g may be useful as lead molecules for the development of new classes of larvicidal, nematicidal and antimicrobial agents

Damage localization and quantification of composite stratified beam structures using residual force method

10.1088/1742-6596/842/1/012028Journal of Physics: Conference Series84211202

Damage mechanisms in cementitious coatings on steel members in bending

Mr Zhao Sheng, Mr Zhang Zhi-Ling, Mr Dong Zhao-Hai and Mr Wu Lin-Sen, and technical staff in the Laboratory in College of Civil Engineering in Tongji University. Natural Science Foundation of China (grant no. 50808143) and key innovative research project of Shanghai Municipal Education Commission (grant no. 09ZZ37

An inflatable and wearable wireless system for making 32-channel electroencephalogram measurements

© 2001-2011 IEEE. Potable electroencephalography (EEG) devices have become critical for important research. They have various applications, such as in brain-computer interfaces (BCI). Numerous recent investigations have focused on the development of dry sensors, but few concern the simultaneous attachment of high-density dry sensors to different regions of the scalp to receive qualified EEG signals from hairy sites. An inflatable and wearable wireless 32-channel EEG device was designed, prototyped, and experimentally validated for making EEG signal measurements; it incorporates spring-loaded dry sensors and a novel gasbag design to solve the problem of interference by hair. The cap is ventilated and incorporates a circuit board and battery with a high-tolerance wireless (Bluetooth) protocol and low power consumption characteristics. The proposed system provides a 500/250 Hz sampling rate, and 24 bit EEG data to meet the BCI system data requirement. Experimental results prove that the proposed EEG system is effective in measuring audio event-related potential, measuring visual event-related potential, and rapid serial visual presentation. Results of this work demonstrate that the proposed EEG cap system performs well in making EEG measurements and is feasible for practical applications

Performance Analysis of a Claw Pole PM Motor

This paper presents the performance analysis of a three-phase three-stack permanent magnet (PM) claw pole motor by using an improved phase variable model, which has been developed for accurate and efficient performance simulation of PM brushless dc motors. The improved model can take into account the effect of magnetic saturation and rotor position dependence of key parameters including back electromagnetic force, winding inductance, cogging torque and core loss, which are obtained from time-stepping nonlinear magnetic field finite element analysis (FEA). The presented model has been implemented in Simulink environment and employed to simulate the dynamic and steady-state performance of the three-phase three-stack PM claw pole motor with soft magnetic composite stator. Parameter computation and performance simulation are validated by experiments on the motor prototype