Cyclic loading behavior of saturated sand with different fabrics

The undrained response of saturated sand under cyclic loading has been a subject of long-standing interest. Although it has been recognized for long, the effect of fabric remians a critical problem that is not yet well understood. In this paper, cyclic triaxial test results from a strategically designed experimental program are presented to demonstrate how significant the effect of fabric can be on the undrained cyclic behavior of sand under different combinations of initial state and initial stress conditions. A significant finding of the study is that loose sand specimens, prepared by different reconstitution methods and thus having different initial fabrics, exhibit similar failure modes under the conventional symmetrical loading condition, but they show distinct failure patterns under the non-symmetrical cyclic loading condition. A qualitative explanation of the macroscopic observations is also proposed from a microscopic perspective, which sheds light on the mechanisms involved. RÉSUMÉ : Le sujet de la réponse du sable saturé sous chargement cyclique non drainé a suscité de l’intérêt depuis longtemps. Cependant il est reconnu que l’effet de la structure reste un problème clef qui n’est pas encore bien compris. Dans cet article, les résultats d’essais triaxiaux cycliques faits dans le cadre d’un programme expérimental conçu spécialement sont présentés afin de démontrer la signifiance de l’effet de structure sur le comportement non drainé du sable soumis à différentes combinaisons d’état initial et contraintes initiales. L’un des résultats les plus importants est que les spécimens de sable lâche préparés par des methods différentes de reconstitution, et donc avec des structures initiales différentes, montrent les mêmes modes de rupture sous chargement symétrique, mais différents schémas de rupture sous chargement non symétrique. Une explication qualitative de ces observations faites à l’échelle macroscopique est donnée d’un point de vue microscopique, éclairant les mécanismes impliqués.postprin

Cyclic behaviour and resistance of saturated sand under non-symmetrical loading conditions

This paper reports findings from an experimental study that aimed to investigate the undrained behaviour of sand in non-symmetrical cyclic loading, and to clarify the role of initial static shear in liquefaction resistance. The testing programme, conducted on a standard sand under triaxial conditions, covers a broad range of initial states in terms of relative density, confining stress and initial shear stress ratio (α). Three distinct failure modes have been identified from the tests: flow-type failure, cyclic mobility and plastic strain accumulation. Of these, flowtype failure, characterised by abrupt runaway deformations without any prior warning, is the most critical, and pertains to sand in the loose state. The tests also demonstrate that the presence of initial static shear stress is beneficial to the liquefaction resistance of loose sand at low α levels, but it becomes detrimental at high Φ levels. In this connection the concept of threshold α is proposed, together with the use of a no-stress-reversal line for better characterisation of the effect of initial static shear. Furthermore, in the conceptual framework of critical state soil mechanics, a fairly good linear relationship has been established between the threshold α and the state parameter Φ that collectively accounts for the initial relative density and mean stress level. This relationship suggests that the threshold α decreases with increasing values of Φ, or with sand becoming looser than the critical state. It is further proposed that the concept of threshold α also applies to sand at high relative density, as long as the confining stress becomes sufficiently high. This proposal leads to a unified and consistent interpretation of the complicated static shear effect.published_or_final_versio

HOW AGN JETS HEAT the INTRACLUSTER MEDIUM - INSIGHTS from HYDRODYNAMIC SIMULATIONS

© 2016. The American Astronomical Society. All rights reserved. Feedback from active galactic nuclei (AGNs) is believed to prevent catastrophic cooling in galaxy clusters. However, how the feedback energy is transformed into heat, and how the AGN jets heat the intracluster medium (ICM) isotropically, still remain elusive. In this work, we gain insights into the relative importance of different heating mechanisms using three-dimensional hydrodynamic simulations including cold gas accretion and momentum-driven jet feedback, which are the most successful models to date in terms of reproducing the properties of cool cores. We find that there is net heating within two "jet cones" (within ∼30° from the axis of jet precession) where the ICM gains entropy by shock heating and mixing with the hot thermal gas within bubbles. Outside the jet cones, the ambient gas is heated by weak shocks, but not enough to overcome radiative cooling, therefore, forming a "reduced" cooling flow. Consequently, the cluster core is in a process of "gentle circulation" over billions of years. Within the jet cones, there is significant adiabatic cooling as the gas is uplifted by buoyantly rising bubbles; outside the cones, energy is supplied by the inflow of already-heated gas from the jet cones as well as adiabatic compression as the gas moves toward the center. In other words, the fluid dynamics self-adjusts such that it compensates and transports the heat provided by the AGN, and hence no fine-tuning of the heating profile of any process is necessary. Throughout the cluster evolution, turbulent energy is only at the percent level compared to gas thermal energy, and thus turbulent heating is not the main source of heating in our simulation

Collaboration interface in Smart Metering Scheme

Theme: Towards a safe, reliable, sustainable intelligent power systemPaper no. I9FP0475Smart meter provides intelligence to serve demand side management. The development of electrical-load-signature technology provides an effective base to enable condition-based monitoring and energy-collaboration management among stakeholders. In a smart metering scheme, the three direct contributors are supplier, estate manager and consumer. Affiliated members are appliance manufacturers and sustainability managers. It is perceived that when a platform can be developed to permit members sharing information, trading benefits, and recommending energy plans. The development of a collaboration interface is to assist the principal members in supporting each other as neighboring aide in these activities. This paper discusses on philosophies and models that shall develop the concepts; and shares the development of this interface.postprintThe 15th International Conference on Electrical Engineering (ICEE 2009), Shenyang, China, 5-9 July 2009

ZnO random laser diode arrays for stable single-mode operation at high power

2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Strategy choice in tourism supply chains for package holidays: a game-theoretic approach

Enterprises in a tourism supply chain usually adopt and operate two business strategies: maximizing their profits or their revenues. This paper investigates the conditions on which these strategies allow enterprises to achieve the maximum benefits in the context of entire supply chain. Several managerial implications have been derived from this theoretical research. Firstly, theme park operator, tour operators and hotel & accommodation providers obtain larger market shares and profits if they select the revenue maximization (R) strategy. Secondly, the profit maximization (P) strategy is a better strategy for both sectors when all the tour operators and all hotel & accommodation providers choose the same strategy. Finally, if both sectors could freely choose their strategies, there is market equilibrium where P-strategy and R-strategy could coexist.published_or_final_versio

Narrowband Single-Pole Double-Throw Filtering Switch Based on Dielectric Resonator

© 2001-2012 IEEE. In this letter, a narrowband single-pole double-throw (SPDT) filtering switch based on dielectric resonators (DRs) is presented. It consists of two DRs shared by two channels for size reduction. Printed circuit boards are embedded in the metal cavity to integrate the PIN diodes. The switching between two channels is enabled by controlling the PIN diodes connected to the two output feeding lines. The electromagnetic field distributions of the DR at the TE -{11\delta } mode are studied to control the coupling between the DR and two output feeding lines. When one channel is on, the PIN diode for this channel is turned off, which does not introduce loss and affect the linearity. For the off-state channel, isolation is obtained by controlling the coupling between the DR and output feeding line, which is considerably enhanced. For demonstration, the DR filtering SPDT switch is implemented. The measured results exhibit that the proposed filtering SPDT switch has narrow bandwidth, low loss, high isolation, and high linearity

Characterization of upstream sequences from the 8S globulin gene of Vigna radiata

Seeds rich in protein in nature, are ideal bioreactors for economic production and storage of valueadded recombinant proteins and enzymes for industries. The upstream region of the seed storage protein gene is able to provide an attractive promoter for seed-specific expression of heterologous genes. Our previous research showed that 8S globulin occupied the majority of total soluble protein stored in seeds of mung bean (Vigna radiata), a rich source of protein, indicating that the promoter of this gene could be a seed-specific promoter with high activity. To improve the expression of heterologous proteins in plants to act as a bioreactor, the putative seed-specific promoter of 8S globulin gene was characterized in this study. Hence, this potential promoter of beta subunit gene of 8S globulin (8SGb) was isolated by genome walking. Analysis with various promoter prediction softwares showed that the promoter sequence possessed many common motifs related to gene transcription in the seed (such as W-box, ABRE element, E-box, etc.). The putative promoter was subsequently cloned into the binary vector pBI121-GFP by replacing the CaMV 35S promoter. The resultant construct designated as pBI-8SGb-GFP was transformed to mung bean cotyledon mesophyll protoplasts. Reporter gene GFP was expressed high in cotyledon protoplasts, which was detected by confocal microscopy, demonstrating the specific activity of 8SGb promoter in driving gene expression. This study also proved that the 8SGb promoter is an efficient regulatory element for plant seeds to act as a bioreactor.Key words: Seed-specific, promoter, genome walking, Vigna radiata

Genetic diversity among natural populations of Ottelia acuminata (Gaghep.) Dandy revealed by ISSR

Ottelia acuminata (Gagnep.) Dandy, an aquatic species of the Hydrocharitaceae, is endemic to China. A performance comparison of genetic diversity of 4 natural populations was conducted to investigatewhether or not water pollution in their habitats has anything to do with this species being endangered. A total number of 120 O. acuminate accessions were analyzed, by amplification of their DNAs with 15 primers (ISSR). Thirteen primers were scored and 214 bands were detected, of which 170 werepolymorphic (79.44%). The results showed that the genetic indices in polluted Jian Lake group were always the smallest ones, when compared with those of the other groups. It indicated that the polluted water did affect the genetic diversity of O. acuminate populations. And ISSRs seemed to be effectivetools for detecting genetic variation among O. acuminate geographical groups

A RAMP marker linked to the tobacco black shank resistant gene

Bulk segregant analysis (BSA) and randomly amplified microsatellite polymorphism (RAMP) were employed to analyze F2 individuals of the Yunyan 317×Hubei 517 to screen and characterize molecularmarkers linked to black shank resistant gene. A total of 800 arbitrary decamer oligonucleotide primerpairs were used for RAMP analysis. Primer pair GT (CA) 4/S89, producing one RAMP marker GT (CA)4/S89550, was tightly linked to the black shank resistant gene. Results of Southern blot suggest that the fragment GT (CA) 4/S89550 was existed in Yunyan 317 and resistant plants, and absent in Hubei 517.Linkage analysis was carried out using marker GT (CA) 4/S89550 on 752 black shank high-resistant individuals of F2 progenies from crossing between Yunyan 317 and Hubei 517. Our results indicated thatthe genetic distances between GT (CA) 4/S89550 and black shank resistant gene was 1.4cM