Synchronization dynamics of two nanomechanical membranes within a Fabry-Perot cavity

Spontaneous synchronization is a significant collective behavior of weakly coupled systems. Due to their inherent nonlinear nature, optomechanical systems can exhibit self-sustained oscillations which can be exploited for synchronizing different mechanical resonators. In this paper, we explore the synchronization dynamics of two membranes coupled to a common optical field within a cavity, and pumped with a strong blue-detuned laser drive. We focus on the system quantum dynamics in the parameter regime corresponding to synchronization of the classical motion of the two membranes. With an appropriate definition of the phase difference operator for the resonators, we study synchronization in the quantum case through the covariance matrix formalism. We find that for sufficiently large driving, quantum synchronization is robust with respect to quantum fluctuations and to thermal noise up to not too large temperatures. Under synchronization, the two membranes are never entangled, while quantum discord behaves similarly to quantum synchronization, that is, it is larger when the variance of the phase difference is smaller

Force Sensing in an Optomechanical System with Feedback-Controlled In-Loop Light

Quantum control techniques applied at macroscopic scales provide us with opportunities in fundamental physics and practical applications. Among them, measurement-based feedback allows efficient control of optomechanical systems and quantum-enhanced sensing. In this paper, we propose a near-resonant narrow-band force sensor with extremely low optically added noise in a membrane in the middle optomechanical system subject to a feedback-controlled in-loop light. The membrane's intrinsic motion consisting of zero-point motion and thermal motion is affected by the added noise of measurement due to the backaction noise and imprecision noise. We show that, in the optimal low-noise regime, the system is analogous to an optomechanical system containing a near quantum-limited optical parametric amplifier coupled to an engineered reservoir interacting with the cavity. Therefore, the feedback loop enhances the mechanical response of the system to the input while keeping the optically added noise of measurement below the standard quantum limit. Moreover, the system based on feedback offers a much larger amplification bandwidth than the same system with no feedback. Without the need to hybridize it with other quantum systems or introduce nonlinearities, our force sensor may have broad applications ranging from biology and medicine to gravitational wave detection and tests of fundamental physics

Environment impact assessment of tilapia (Tilapia Nilotica) farming project in brachish water of Bafgh

The aim of the present study is the environmental impact assessment of tilapia (Tilapia nilotica) farming project in brackish water of Bafgh, with goals to achieve localization of technology and knowledge of tilapia fish production, employment and the possibility to controlled development in other areas. Desired range, located in northwest of Daranjir desert (Inland Salt Water Fishes Research Station, Bafgh). Total area used for the project includes three indoor hall for breeding operation, nursery (juvenile breeding) and fattening. Besides these, three 3000 m 3 available earth ponds has been considered as a potential area breeding after setting apart the quarantine. In order to achieve sustainable development of breeding this fish, impact assessment of this project development in which both environmental and social - economic effects are considered, it seems essential and project will be accomplished more confidently. So, after considering the technical characteristics of the project, the immediate, direct and indirect impact area were determined and environmental aspects of area identified. Matrix methods was utilized for the environmental impact assessment. The most important operational activities, including greenhouse structures implementation and water conveyance facilities, including excavation and embankment, channel, piping, lining of channels and their accessories including inlet and outlet valves, concrete, stone, porcelain, walling up , roof, construction of drainage network and access roads. Based on investigation, accessibility of the region, compatibility with the other land uses, lack of monuments in the area, not covered with the sensitive habitats range, the lack of permanent river flow, low quality of underground water and end up underground water flows in downstream desert and evaporated which result in impossibility of escaping introduced fish from the farm and the use of existing spaces in the first half of the year to product lead to make fewer infrastructure costs and increase revenue, are the main criteria for the sustainable development of this species culture in the area. Considering the executed studies and results of the matrix assessment construction and operation phases, it was concluded that there is no considerable destructive impacts related to the project. Therefore due to the fact that 50% of means in rows and columns of the matrix were not less than -3.1 so, we proposed execution of it with rehabilitation plans. Therefore, some strategies and plans to consider reducing the negative effects and enhance positive effects of the project, including monitoring programs, were proposed

Effect of Compositional Grading On reservoir Performance

In reservoirs with thickness exceeding fifty meters, compositional guiding has been found to cause significant variation in performance. Main fluid properties, governing the magnitude of reservoir performance, such as density; formation volume factor and fluid viscosity experience variation due to varying fluid composition along the hydrocarbon column. These variations cause erroneous estimation of stock-tank oil in place and may infer reservoir engineers to consider inappropriate secondary oil recovery methods, for example. In the presence of gravity segregation within the oil column, heavy ends will form a heavy oil blanket in the lower part of the reservoir. Such a scenario may result in poor displacement and an earlier breakthrough when water drive is the dominant fluid flow mechanism. In this paper reservoir performance due to varying reservoir fluid composition has been examined using  reservoir simulation analysis and recommendations for better characterization of reservoir fluid sampling are outlined

Eléments joints dans le code CESAR-LCPC : Application aux milieux fracturés, fissurés et aux problèmes d'interface

Les discontinuités des géomatériaux (fissures, fractures ou joints dans les massifs rocheux) peuvent être prises en compte dans une modélisation par éléments finis au moyen d'éléments "joints". Il s'agit d'éléments à épaisseur nulle proposés initialement par Goodman et al (1968). Des éléments joints à quatre noeuds ont été introduits dans le code CESAR-LCPC. Ces éléments permettent de prendre en compte un comportement élastique non linéaire ou un comportement élastoplastique avec plasticité parfaite obéissant au critère de Mohr-Coulomb. Des exemples d'application de ce modèle à la stabilité des massifs rocheux et à l'homogénéisation du comportement des roches fissurées sont donnés. L'extension à un comportement endommageable est en cours

The prevention of relapse in alcohol dependence A qualitative study of the views of service users

Includes bibliographical referencesAvailable from British Library Document Supply Centre- DSC:m03/12989 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Eléments joints dans le code CESAR-LCPC : Application aux milieux fracturés, fissurés et aux problèmes d'interface

Les discontinuités des géomatériaux (fissures, fractures ou joints dans les massifs rocheux) peuvent être prises en compte dans une modélisation par éléments finis au moyen d'éléments "joints". Il s'agit d'éléments à épaisseur nulle proposés initialement par Goodman et al (1968). Des éléments joints à quatre noeuds ont été introduits dans le code CESAR-LCPC. Ces éléments permettent de prendre en compte un comportement élastique non linéaire ou un comportement élastoplastique avec plasticité parfaite obéissant au critère de Mohr-Coulomb. Des exemples d'application de ce modèle à la stabilité des massifs rocheux et à l'homogénéisation du comportement des roches fissurées sont donnés. L'extension à un comportement endommageable est en cours

Field application of phenol formaldehyde gel in oil reservoir matrix for water shut-off purposes

A few wells from a major western India on-shore oil field are either on the verge of being shut in or have already been abandoned due to excessive water-cut (WCT) levels. Low injectivity and extreme temperatures (149C) make it difficult for water shut-off by conventional polymer gel injection. A water-thin monomer-based in situ gelation system has been developed and successfully tried in one of the wells that ceased production due to 100% WCT. The average production of 420 barrel of oil per day (BOPD) with less than 1% WCT, in the first year of production back in 1996, has declined to less than 8 BOPD (with 98% WCT) prior to shut-in in year 2002. A rise in the oil-water contact level in combination with a coning effect was diagnosed as a possible cause of the high WCT, which was later controlled by a newly developed gelant treatment. In fact, the average post-treatment production for the first 3 months was nearly 200 BOPD. Thereafter, production gradually stabilized in the neighborhood of 115 BOPD with a WCT of 48%. Cheap chemicals and a fast treatment method have resulted in a payback time span of 5 days and made an additional profit of U.S. $0.6 M. The water shut-off job resulted in an impressive commercial success; technical success, however, was less than satisfactory due to the fact that, in spite of using a water-thin monomeric solution, only 40% of the designed volume could be injected due to low injectivity resulting in an abnormal pressure build-up. In addition to the gel development and treatment experiences, this article describes in detail the results of further lab investigations carried out to identify the possible reasons causing injection failure