856 research outputs found

    Vortex-Bright Soliton Dipoles: Bifurcations, Symmetry Breaking and Soliton Tunneling in a Vortex-Induced Double Well

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    The emergence of vortex-bright soliton dipoles in two-component Bose-Einstein condensates through bifurcations from suitable eigenstates of the underlying linear system is examined. These dipoles can have their bright solitary structures be in phase (symmetric) or out of phase (anti-symmetric). The dynamical robustness of each of these two possibilities is considered and the out-of-phase case is found to exhibit an intriguing symmetry-breaking instability that can in turn lead to tunneling of the bright wavefunction between the two vortex "wells". We interpret this phenomenon by virtue of a vortex-induced double well system, whose spontaneous symmetry breaking leads to asymmetric vortex-bright dipoles, in addition to the symmetric and anti-symmetric ones. The theoretical prediction of these states is corroborated by detailed numerical computations.Comment: 14 pages, 8 figure

    Synthesizing SystemC Code from Delay Hybrid CSP

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    Delay is omnipresent in modern control systems, which can prompt oscillations and may cause deterioration of control performance, invalidate both stability and safety properties. This implies that safety or stability certificates obtained on idealized, delay-free models of systems prone to delayed coupling may be erratic, and further the incorrectness of the executable code generated from these models. However, automated methods for system verification and code generation that ought to address models of system dynamics reflecting delays have not been paid enough attention yet in the computer science community. In our previous work, on one hand, we investigated the verification of delay dynamical and hybrid systems; on the other hand, we also addressed how to synthesize SystemC code from a verified hybrid system modelled by Hybrid CSP (HCSP) without delay. In this paper, we give a first attempt to synthesize SystemC code from a verified delay hybrid system modelled by Delay HCSP (dHCSP), which is an extension of HCSP by replacing ordinary differential equations (ODEs) with delay differential equations (DDEs). We implement a tool to support the automatic translation from dHCSP to SystemC

    Strong-mixing induced deep ocean heat uptake events in the North Atlantic.

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    The deceleration of the upper ocean heat storage during the last decade has resulted in an active search for the ’missing heat’ in the deep ocean. Modeling work has provided new insights into the role of the central Pacific Ocean on the present hiatus in global warming and the efficient transfer of heat to the deep ocean, but recent studies have highlighted also the large contribution of the North Atlantic basin to these processes, mainly based on ocean observations. The deep ocean heat uptake (below 300 m) in the North Atlantic is not confined to the subpolar gyre region but extends to mid-latitudes of the Eastern North Atlantic (ENA), requiring an additional process for its explanation other than deep convection considered until now. Here, using oceanographic in-situ data, we describe a mechanism of heat and salt injection to the deep ocean after years of warming and saltening at the surface occurred both in regions of mode (43º-48ºN) and deep water (74º-76ºN) formation in the ENA. The mechanism, although punctual meditated by strong winter mixing events, is between 2 and 6 times higher than the 2000-2010 ocean heat uptake at depths of mode (300-700m) and deep water (>2000m) formation, contributing significantly to the observed deep ocean heat uptake in the North Atlantic. Nutrient, hydrographic and reanalysis data indicate that the strong mixing-induced deep ocean heat uptake events at areas of mode and deep water formation in the North Atlantic are connected through the northward propagation of salty ENA mode waters triggered by the contraction of the subpolar gyre reinforced by the occurrences of blocking anomalies in the ENA. Such connection is not unique of the last decade but observed also during the 1960s. Natural climate variability seems the ultimate driver of the strong mixing-induced deep ocean heat uptake events, although the anthropogenic global warming and its forcing on the Arctic sea-ice retreat and frequency of extreme weather events could modify their effects.0,000

    Evaluation of cavitation erosion resistance of Al-Si casting alloys: effect of eutectic and intermetallic phases

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    In the present paper, the influence of eutectic and intermetallic phases on cavitation resistance of Al-Si alloys was studied. In fact, Al-Si alloys are commonly used for the production of components, such as cylinders, pistons, pumps, valves and combustion chambers, which in service may incur in cavitation phenomenon. Samples of AlSi3, AlSi9 and AlSi9CuFe were characterized from the microstructural point of view. Hardness measurements were also performed. Subsequently, cavitation tests were carried out according to ASTM G32 standard and the erosion mechanism was examined by scanning electron microscope. It was found the both eutectic and intermetallic phases enhance cavitation resistance, expressed in terms of mass loss. Particularly, intermetallic particles with complex morphologies provide a positive contribution, exceeding that of other microstructural features, as grain size. The effect of T6 heat treatment was also evaluated. It was confirmed that the precipitation of fine strengthening particles in the Al matrix successfully hinders the movement of dislocations, resulting in a longer incubation stage and a lower mass loss for heat-treated samples in comparison with as-cast ones. Finally, the relationship between cavitation resistance and material hardness was investigated

    The effects of temperature and relative humidity on the growth of three isolated fungi from rice (Oryza sativa L.) seedlings in Dadin Kowa Irrigation Scheme, Dadin Kowa, Gombe

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    The effects of temperature and relative humidity on the growth of three isolated fungi (Aspergillus parasiticus, Altenaria alternata and Thielavia terricola) associated with rice seedlings rot in Dadin Kowa Irrigation Scheme, Gombe, Nigeria were investigated. Temperature in the ranges of 10oC, 15oC, 25oC, 30oC, 35oC and 40oC were used to determine the temperature effect on the growth of these fungi. These fungi were also cultured on 100, 91, 80, 59.5, 47 and 32.5 % relative humidity. Highest growth of these fungi was obtained at 25oC and 30oC temperatures. The fungi showed highest growth at 80 and 91% relative humidity. The growth of these fungi was observed to increase with increase in relative humidity and vice versa. Statistical application for Sciences (SAS) was used to analyze the data generated and the least significant difference, was used to separate the means. There were significant differences (P≤0.05) in the growth of these fungi at different temperature and relative humidity regimes.Keywords: Temperature, Relative Humidity, Growth, Rice, Fungi, Dadin Kow

    Sustainable Co-Design with Older People: The case of a Public Restorative Garden in Milan (Italy)

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    The demographic aging and the evolution of lifestyles require new strategies to promote the well-being and active aging of elderly. Active aging depends on many factors: some of these are related to objective data such as physical environment, others are personal elements; it is important to improve environmental physical factors to encourage personal attitudes to the green spaces in use. To design a small sustainable restorative green space in Milan, Italy, restorative garden design criteria are summarized in the first section of the paper and both social and environmental sustainability are considered. The methodology section describes the co-design process and how it was applied to include dierent older user groups in the design of the area. In the results section authors apply a taxonomy based on the four properties of restorative settings according to the Attention Restoration Theory by Kaplan (compatibility, being away, extent, fascination): this provides a unified system to classify users\u2019 expectations and to describe the final project. The proposed co-design process combines social and environmental sustainability, as it provides designers an insight about the user\u2019s experience in nature. Such information can be fruitfully integrated with professional competences about comfort aspects and environmental protection in order to improve the whole design project

    Allergy in total knee replacement surgery: Is it a real problem?

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    Total knee arthroplasty is a common procedure, with extremely good clinical results. Despite this success, it produces 20% unsatisfactory results. Among the causes of these failures is metal hypersensitivity. Metal sensitization is higher in patients with a knee arthroplasty than in the general population and is even higher in patients undergoing revision surgery. However, a clear correlation between metal sensitization and symptomatic knee after surgery has not been ascertained. Surely, patients with a clear history of metal allergy must be carefully examined through dermatological and laboratory testing before surgery. There is no globally accepted diagnostic algorithm or laboratory test to diagnose metal hypersensitivity or metal reactions. The patch test is the most common test to determine metal hypersensitivity, though presenting some limitations. Several laboratory assays have been developed, with a higher sensitivity compared to patch testing, yet their clinical availability is not widespread, due to high costs and technical complexity. Symptoms of a reaction to metal implants present across a wide spectrum, ranging from pain and cutaneous dermatitis to aseptic loosening of the arthroplasty. However, although cutaneous and systemic hypersensitivity reactions to metals have arisen, thereby increasing concern after joint arthroplasties, allergies against implant materials remain quite rare and not a well-known problem. The aim of the following paper is to provide an overview on diagnosis and management of metal hypersensitivity in patients who undergo a total knee arthroplasty in order clarify its real importance

    Equivalence of switching linear systems by bisimulation

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    A general notion of hybrid bisimulation is proposed for the class of switching linear systems. Connections between the notions of bisimulation-based equivalence, state-space equivalence, algebraic and input–output equivalence are investigated. An algebraic characterization of hybrid bisimulation and an algorithmic procedure converging in a finite number of steps to the maximal hybrid bisimulation are derived. Hybrid state space reduction is performed by hybrid bisimulation between the hybrid system and itself. By specializing the results obtained on bisimulation, also characterizations of simulation and abstraction are derived. Connections between observability, bisimulation-based reduction and simulation-based abstraction are studied.\ud \u
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