Cyclic behaviour of deep reinforced concrete coupling beams

Six half-scale models of reinforced concrete coupling beams with span/depth ratios ≤ 2.0 were tested under reversed cyclic load by a newly developed test method that can accurately simulate the boundary conditions of coupling beams in coupled shear wall structures. Five of them were conventionally reinforced and one was diagonally reinforced. Span/depth ratio and reinforcement layout were the main structural variables studied. Test results revealed that the deep conventionally reinforced coupling beams behaved quite differently from the ordinary beams in frame structures. Generally, shear failure was more likely to occur. Moreover, the additional longitudinal reinforcement bars (those placed near the centroidal axis) could contribute significantly to bending strength and therefore lead to an increase in shear demand. Nevertheless, the measured drift ratios of the conventionally reinforced coupling beams still reached 3·6-5·7%, which are not small for deep coupling beams. On the other hand, it was found that the provision of diagonal reinforcement radically changed the load resisting mechanism and significantly improved the energy dissipation capacity of the coupling beam. However, it had not improved the deformability of the coupling beam.published_or_final_versio

Testing of coupling beams with equal end rotations maintained and local joint deformation allowed

The strength and ductility of the coupling beams in coupled shear walls can significantly affect the nonlinear behaviour and earthquake resistance of the whole building structure. However, although extensive testing of coupling beams has been performed, the boundary conditions-that the rotations at the two ends of a coupling beam are equal and that local deformation occurs at the beam-wall joints, which could have substantial influence on the test results-have not been correctly simulated. Herein, a new method of testing reinforced concrete coupling beams that ensures equal rotations at the ends of the beam specimen and takes into account local deformation at the beam-wall joints is developed. The method has been successfully applied to test typical reinforced concrete coupling beams with relatively small span/depth ratios and proven to be suitable for studying the post-peak behaviour and failure characteristics of short coupling beams. Test results obtained so far indicate that reinforced concrete coupling beams with small span/depth ratios behave quite differently from ordinary beams in frame structures and that the local deformation at beam-wall joints is quite substantial. Complete load-deflection curves have been acquired and the strength and ductility of the coupling beams evaluated.published_or_final_versio

Chemical characterization of PM2.5 from a southern coastal city of China:applications of modeling and chemical tracers in demonstrationof regional transport

An intensive sampling campaign of airborne fine particles (PM2.5) was conducted at Sanya, a coastal city in Southern China, from January to February 2012. Chemical analyses and mass reconstruction were used identify potential pollution sources and investigate atmospheric reaction mechanisms. A thermodynamic model indicated that low ammonia and high relative humidity caused the aerosols be acidic and that drove heterogeneous reactions which led to the formation of secondary inorganic aerosol. Relationships among neutralization ratios, free acidity, and air-mass trajectories suggest that the atmosphere at Sanya was impacted by both local and regional emissions. Three major transport pathways were identified, and flow from the northeast (from South China) typically brought the most polluted air to Sanya. A case study confirmed strong impact from South China (e.g., Pearl River Delta region) (contributed 76.8% to EC, and then this result can be extended to primary pollutants) when the northeast winds were dominant. The Weather Research Forecasting Black carbon model and trace organic markers were used to apportion local pollution versus regional contributions. Results of the study offer new insights into the atmospheric conditions and air pollution at this coastal city

Relaxed 2-D Principal Component Analysis by LpL_p Norm for Face Recognition

A relaxed two dimensional principal component analysis (R2DPCA) approach is proposed for face recognition. Different to the 2DPCA, 2DPCA-$L_1$ and G2DPCA, the R2DPCA utilizes the label information (if known) of training samples to calculate a relaxation vector and presents a weight to each subset of training data. A new relaxed scatter matrix is defined and the computed projection axes are able to increase the accuracy of face recognition. The optimal $L_p$-norms are selected in a reasonable range. Numerical experiments on practical face databased indicate that the R2DPCA has high generalization ability and can achieve a higher recognition rate than state-of-the-art methods.Comment: 19 pages, 11 figure

Genetic neural network for Traditional Chinese medicine

The research into the impersonality and information of the Traditional Chinese-medicine Diagnosis (TCMD) is a key work to realize the Traditional Chinese-medicine (TCM) medicine examination system. So the paper studies the application of Artificial Neural Networks (NN) to TCM and uses the Genetic Algorithm (GA) to optimize the ANN, which is used to the diagnosis of TCM. The initial structure of the ANN is arbitrary and the GA is able to find a near optimal connection weight and structure of the ANN for the TCMD. In this paper, we emphatically describe t the GA to optimal the connection weight of the NN - Genetic NN, which has a relatively fixed three-layer and was used to the TCM eight principal syndromes by the tongue feature

Evaluation of soil fertility of the shelter-forest land along the Tarim Desert Highway

To study the changes of soil fertility of the shelter-forest land along the Tarim Desert Highway, soils from the forest land were collected at the layers of 0-10 cm, 10-20 cm, 20-30 cm. Different soil fertility parameters were measured, and quantitative evaluation of soil fertility was performed by the soil integrated fertility index (IFI). The main results show that the construction of the shelter forest along the Tarim Desert Highway improved the soil physical structure, increased soil porosity and enhanced water-holding capacity. With the increase of plantation time of the shelter forest, soil microbial biomass C, N, P and the activities of six types of enzyme were enhanced, which promoted the accumulation and transformation of soil nutrients of the forest land. Consequently, the soil nutrients in 12-year-old forest land were much higher than in the newer ones and drifting sand. However, soil salt content of the older forest land was higher owing to the drip-irrigation with salt water. Through the comprehensive evaluation, we found that soil fertility index in the forest land was enhanced with the forest age, and it had close correlations with the growth indices of the forest trees. In summary, construction of the shelter-forest along the Tarim Desert Highway accelerated the improvement of aeolian soil in the forest land, and the soil fertility improved year by year. We conclude that the forest trees grow normally under the stress of the present drip-irrigation with salt water

A Nacre-Like Carbon Nanotube Sheet for High Performance Li-Polysulfide Batteries with High Sulfur Loading

© 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Lithium-sulfur (Li-S) batteries are considered as one of the most promising energy storage systems for next-generation electric vehicles because of their high-energy density. However, the poor cyclic stability, especially at a high sulfur loading, is the major obstacles retarding their practical use. Inspired by the nacre structure of an abalone, a similar configuration consisting of layered carbon nanotube (CNT) matrix and compactly embedded sulfur is designed as the cathode for Li-S batteries, which are realized by a well-designed unidirectional freeze-drying approach. The compact and lamellar configuration with closely contacted neighboring CNT layers and the strong interaction between the highly conductive network and polysulfides have realized a high sulfur loading with significantly restrained polysulfide shuttling, resulting in a superior cyclic stability and an excellent rate performance for the produced Li-S batteries. Typically, with a sulfur loading of 5 mg cm−2, the assembled batteries demonstrate discharge capacities of 1236 mAh g−1 at 0.1 C, 498 mAh g−1 at 2 C and moreover, when the sulfur loading is further increased to 10 mg cm−2 coupling with a carbon-coated separator, a superhigh areal capacity of 11.0 mAh cm−2 is achieved

Synthesis of chiral zinc porphyrin and its thermodynamic study of coordination reactions with substituted imidazoles

2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe