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Roles of soil-structure interaction and damping in base-isolated structures built on numerous soil layers overlying a half-space

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 387-400页

作者： C.s.Tsai C.I.Hsueh H.C.su Department of Civil Engineering Feng Chia University Graduate Institute of Civil & Hydraulic Engineering Feng Chia University Department of Water Resources Engineering and Conservation Feng Chia University

This study examines the roles of soil-structure interaction （ssI）, higher modes, and damping in a base-isolated structure built on multiple layers of soil overlying a half space. Closed-form solutions for the entire system, including a superstructure, seismic isolator, and numerous soil layers overlying a half-space, were obtained. The formulations obtained in this study simply in terms of well-known frequencies and mechanical impedance ratios can explicitly interpret the dynamic behavior of a base-isolated structure interacting with multiple soil layers overlying a half-space. The key factors influencing the performance of the isolation system are the damping ratio of the isolator and the ratio of the natural frequency of the fixed-base structure to that of the isolated structure by assuming that the superstructure moves as a rigid body. This study reveals that higher damping in the base isolator is unfavorable to higher mode responses that usually dominate the responses of the superstructure and that the damping mechanism plays an important role in transmitting energy in addition to absorbing energy. It is also concluded that it is possible to design a soft soil layer as an isolation system for isolating vibration energy.

关键词： base isolation seismic isolation soil-structure interaction closed- form solution higher-mode effects soilstratum passive control damping effects

Origin of extension twinning-mediated static recrystallization and unique parallel alignment of(0001) poles to transverse direction in Mg-3Al-0.4Mn(mass%) alloy sheet

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Journal of Magnesium and Alloys 2023年第9期11卷 3200-3213页

作者： T.Nakata C.Xu L.Geng s.Kamado Nagaoka University of Technology 1603-1KamitomiokaNagaoka 940-2188Japan school of Materials science and Engineering Harbin Institute of Technology Harbin 150001China

The origin of unique parallel alignment of(0001) poles to transverse direction(TD) was investigated using Mg-3Al-0.4Mn(mass%)alloy sheets rolled with different process conditions. When rolling was performed with intermediate reheating, the alloy showed a sluggish static recrystallization(sRX) behavior during post-annealing, facilitating the nucleation and growth of statically recrystallized grains from extension twins. This resulted in the apparent texture component with the parallel alignment of the(0001) poles to the TD, and the sheet exhibited good ductility for both the rolling direction(RD) and TD. In contrast, continuous rolling without intermediate reheating led to the formation of severely deformed regions near double twins. sRX was promoted at such regions, forming a typical basal textural feature with weak RD-split of the(0001) poles. Although extension twins were formed after the continuous rolling, sRX was facilitated at the severely deformed regions with double twins, and the formation of the unique alignment of the(0001) poles to the TD was suppressed. The RD-split texture led to the large elongation to failure along the RD, while it along the TD decreased owing to the narrow distribution of the(0001)poles toward the TD, resulting in the in-plane anisotropy in ductility.

关键词： Magnesium Rolling Twinning static recrystallization Texture

Development of aluminum rheo-extrusion process using semi-solid slurry at low solid fraction

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Transactions of Nonferrous Metals society of China 2010年第9期20卷 1763-1768页

作者： T.RATTANOCHAIKUL s.JANUDOM N.MEMONGKOL J.WANNAsIN Department of Mining and Materials Engineering Faculty of EngineeringPrince of Songkla University Department of Industrial Engineering Faculty of EngineeringPrince of Songkla University

An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery. The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions. A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 ram. The semi-solid metal process used in this study was the gas induced semi-solid （GIss） technique. To study the feasibility of the GIss extrusion process, the effects of extrusion parameters such as plunger speed and solid fi-action on the extrudability, microstructure, and mechanical properties of extruded samples were investigated. The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.

关键词： aluminum alloys extrusion semi-solid metal rheo-extrusion gas induced semi-solid (GIss)

PERsONAL EXPERIENCE ON THE TREATMENT OF DYsMENORRHEA

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Journal of Traditional Chinese Medicine 1989年第4期9卷 259-265页

作者： M s Zhou

Zhou Meisheng 周楣声(Anhui College of TCM):Dysmenorrhea is a common and frequentdisease of women;it may last many days duringmenstruation and persist for many *** found 2 modalities of treatment veryuseful in controll... 详细信息

关键词： persist tongue modalities 周楣声 breaking minutes Anhui courses stasis moxibustion

Effect of Hall current on MHD natural convection flow from vertical permeable flat plate with uniform surface heat flux

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Applied Mathematics and Mechanics(English Edition) 2011年第9期32卷 1127-1146页

作者： L.K.sAHA s.sIDDIQA M.A.HOssAIN Department of Mathematics University of DhakaDhaka 1000Bangladesh Department of Mathematics COMSATS Institute of Information TechnologyPark RoadChak ShahzadIslamabad 44000Pakistan

The effect of the Hall current on the magnetohydrodynamic （MHD） natural convection flow from a vertical permeable flat plate with a uniform heat flux is analyzed in the presence of a transverse magnetic *** is assumed that the induced magnetic field is negligible compared with the imposed magnetic *** boundary layer equations are reduced to a suitable form by employing the free variable formulation （FVF） and the stream function formulation （sFF）.The parabolic equations obtained from FVF are numerically integrated with the help of a straightforward finite difference ***,the nonsimilar system of equations obtained from sFF is solved by using a local nonsimilarity method,for the whole range of the local transpiration parameter ζ.Consideration is also given to the regions where the local transpiration parameter ζ is small or large ***,in these particular regions,solutions are acquired with the aid of a regular perturbation *** effects of the magnetic field M and the Hall parameter m on the local skin friction coefficient and the local Nusselt number coefficient are graphically shown for smaller values of the Prandtl number P r （= 0.005,0.01,0.05）.Furthermore,the velocity and temperature profiles are also drawn from various values of the local transpiration parameter ζ.

关键词： magnetohydrodynamic (MHD) natural convection Hall current permeable plate heat flux

Temporal Behaviour of a Corner separation in a Radial Vaned Diffuser of a Centrifugal Compressor Operating near surge

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Journal of Thermal science 2013年第6期22卷 555-564页

作者： A.Marsan I.Trébinjac s.Coste G.Leroy Laboratoire de Mécanique des Fluides et d'Acoustique UMR CNRS 5509 cole Centrale de Lyon Turbomeca Safran group

The temporal behaviour of a flow separation in the hub-suction side comer of a transonic diffuser is studied thanks to unsteady numerical simulations based on the phase-lagged approach. The validity of the numerical re- sults is confn＇med by comparison with experimental unsteady pressure measurements. An analysis of the instan- taneous skin-friction pattern and particles trajectories is presented. It highlights the topology of the separation and its temporal behaviour. The major result is that, despite of a highly time-dependent core flow, the separation is found to be a ＂fixed unsteady separation＂ characterized by a fixed location of the main saddle of the separation but an extent of the stall region modulated by the pressure waves induced by the impeller-diffuser interaction.

关键词： Corner separation Radial Vaned Diffuser Centrifugal Compressor surge

Continuous segregation of binary heterogeneous solids in a fast-fluidized bed

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Particuology 2017年第6期15卷 101-107页

作者： M. Prasad Babu P.s.T. sai K. Krishnaiah Department of Chemical Engineering Indian Institute of Technology Madras Chennai 600 036 India

Continuous segregation of binary heterogeneous solids （different density mixtures） is carried out in a gas-solid fluidized bed to study the effects of gas velocity, solids feed rate, feed composition and density difference of solids on the separation factor （recovery of flotsam at top outlet） and the quality of the product （purity of flotsam at top outlet） in a continuous fast-fluidized bed. The holdup of the bed material is obtained in each experimental run. It is observed that the separation factor decreases with increase in solids feed rate or density difference of solids, and increases with gas velocity or proportion of flotsam in the feed. The quality of the product decreases with increase in gas velocity or solids flow rate, and increases with feed composition or density difference of solids. The experimental results show that the separation factor and the quality of the product are more sensitive to gas velocity than to other operating parameters, Empirical correlations for predicting the separation factor and quality of the product are proposed based on the Richards model for individual flotsam mass fraction in the feed, and the predictions agree satisfactorily with the present exlgerimental data,

关键词： Fast-fluidized bed Gas-solid Continuous segregation Heterogeneous solids solids holdup

Composite recommendations： from items to packages

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Frontiers of Computer science 2012年第3期6卷 264-277页

作者： Min XIE Laks V. s. LAKsHMANAN Peter T. WOOD Department of Computer science University of British Columbia Vancouver V6T 1Z4 Canada Department of Computer science and Information systems Birkbeck University of London London WCIE 7HX UK

Classical recommender systems provide users with a list of recommendations where each recommendation consists of a single item, e.g., a book or DVD. However, sev- eral applications can benefit from a system capable of recom- mending packages of items, in the form of sets. sample appli- cations include travel planning with a limited budget （price or time） and twitter users wanting to select worthwhile tweeters to follow, given that they can deal with only a bounded num- ber of tweets. In these contexts, there is a need for a system that can recommend the top-k packages for the user to choose from. Motivated by these applications, we consider composite recommendations, where each recommendation comprises a set of items. Each item has both a value （rating） and a cost associated with it, and the user specifies a maximum total cost （budget） for any recommended set of items. Our composite recommender system has access to one or more component recommender systems focusing on different do- mains, as well as to information sources which can provide the cost associated with each item. Because the problem of deciding whether there is a recommendation （package） whose cost is under a given budget and whose value exceeds some threshold is NP-complete, we devise several approximation algorithms for generating the top-k packages as recommen- dations. We analyze the efficiency as well as approximation quality of these algorithms. Finally, using two real and two synthetic datasets, we subject our algorithms to thorough ex- perimentation and empirical analysis. Our findings attest tothe efficiency and quality of our approximation algorithms for the top-k packages compared to exact algorithms.

关键词： recommendation algorithms optimization,top-k query processing

source apportionment of PM10 in Delhi, India using PCA/APCs, UNMIX and PMF

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Particuology 2018年第2期16卷 107-118页

作者： srishti Jain s.K. sharma T.K. Mandal Mohit saxena Environmental sciences and Biomedical Metrology Division CSIR-National Physical Laboratory Dr. K. S. Krishnan Road New Delhi 110 012 India Academy of scientific and Innovative Research (AcsIR) CSIR-National Physical Laboratory campus New Delhi 110 012 India

source apportionment of particulate matter （PM10） measurements taken in Delhi, India between January 2013 and June 2014 was carried out using two receptor models, principal component analysis with absolute principal component scores （PCA/APCs） and UNMIX. The results were compared with previous estimates generated using the positive matrix factorization （PMF） receptor model to investigate each model＇s source-apportioning capability. All models used the PM10 chemical composition （organic carbon （OC）, elemental carbon （EC）, water soluble inorganic ions （WsIC）, and trace elements） for source apportionment. The average PM10 concentration during the study period was 249.7±103.9 μg/m3 （range： 61.4-584.8 μg/m3）. The UNMIX model resolved five sources （soil dust （sD）, vehicular emissions （VE）, secondary aerosols （sA）, a mixed source of biomass burning （BB） and sea salt （ss）, and industrial emissions （IE））. The PCA/APCs model also resolved five sources, two of which also included mixed sources （sD, VE, sD＋ss, （sA＋BB＋ss） and 1E）. The PMF analysis differentiated seven individual sources （sD, VE, sA, BB, ss, IE, and fossil fuel combustion （FFC））. All models identified the main sources contributing to PM10 emissions and reconfirmed that VE, sA, BB, and sD were the dominant contributors in Delhi.

关键词： Receptor model PCA/APCs UNMIX PMF source apportionment