Negative Refractive Index in Optics of Metal-Dielectric Composites

Specially designed metal-dielectric composites can have a negative refractive index in the optical range. Specifically, it is shown that arrays of single and paired nanorods can provide such negative refraction. For pairs of metal rods, a negative refractive index has been observed at 1.5 micrometer. The inverted structure of paired voids in metal films may also exhibit a negative refractive index. A similar effect can be accomplished with metal strips in which the refractive index can reach -2. The refractive index retrieval procedure and the critical role of light phases in determining the refractive index is discussed.Comment: 39 pages, 17 figures, 24 equation

A Superlens Based on Metal-Dielectric Composites

Pure noble metals are typically considered to be the materials of choice for a near-field superlens that allows subwavelength resolution by recovering both propagating and evanescent waves. However, a superlens based on bulk metal can operate only at a single frequency for a given dielectric host. In this Letter, it is shown that a composite metal-dielectric film, with an appropriate metal filling factor, can operate at practically any desired wavelength in the visible and near-infrared ranges. Theoretical analysis and simulations verify the feasibility of the proposed lens.Comment: 15 pages, 4 figure

Negative Index of Refraction in Optical Metamaterials

An array of pairs of parallel gold nanorods is shown to have a negative refractive index n'=-0.3 at the optical communication wavelength of 1.5 micron. This effect results from the plasmon resonance in the pairs of nanorods for both the electric and magnetic components of light. The refractive index is retrieved from the direct phase and amplitude measurements for transmission and reflection, which are all in excellent agreement with our finite difference time domain simulations. The refraction critically depends on the phase of the transmitted wave, which emphasizes the importance of phase measurements in finding n'.Comment: an improved version (17 pages, 5 figures) with a new sample and additional measurement

Maintaining SLOs of cloud-native applications via self-adaptive resource sharing

With changing workloads, cloud service providers can leverage vertical container scaling (adding/removing resources) so that Service Level Objective (SLO) violations are minimized and spare resources are maximized. In this paper, we investigate a solution to the self-adaptive problem of vertical elasticity for co-located containerized applications. First, the system learns performance models that relate SLOs to workload, resource limits and service level indicators. Second, it derives limits that meet SLOs and minimize resource consumption via a combination of optimization and restricted brute-force search. Third, it vertically scales containers based on the derived limits. We evaluated our technique on a Kubernetes private cloud of 8 nodes with three deployed applications. The results registered two SLO violations out of 16 validation tests; acceptably low derivation times facilitate realistic deployment. Violations are primarily attributed to application specifics, such as garbage collection, which require further research to be circumvented

The weakest link: Revealing and modeling the architectural patterns of microservice applications

Cloud microservice applications comprise interconnected services packed into containers. Such applications generate complex communication patterns among their microservices. Studying such patterns can support assuring various quality attributes, such as autoscaling for satisfying performance, availability and scalability, or targeted penetration testing for satisfying security and correctness. We study the structure of containerized microservice applications via providing the methodology and the results of a structural graphbased analysis of 103 Docker Compose deployment files from opensourced Github repositories. Our findings indicate the dominance of a power-law distribution of microservice interconnections. Further analysis highlights the suitability of the Barabási-Albert model for generating large random graphs that model the architecture of real microservice applications. The exhibited structures and their usage for engineering microservice applications are discussed

Разработка метода количественного определения воды в сотовых панелях самолетов методом ИК термографии

Проведено моделирование и экспериментальные исследования по тепловому контролю воды в авиационных сотовых панелях. Рассмотрены случаи разного расположения воды внутри ячеек и разного количества воды. Показана возможность количественной оценки скрытой воды при двухстороннем и одностороннем доступе к объекту контроля. Разработан и реализован алгоритм количественной оценки массы воды для конкретной сотовой панели.Modelling and experimental activities of TNDT jf aviation honeycomb panels are conducted. The cases of various amount and location of water ingress are considered. The possibility of quantitative evaluation of hidden water with one and two side control is illustrated. The algoritm of quantitative evaluation of hidden water content is realized

Optical Cloaking with Non-Magnetic Metamaterials

Artificially structured metamaterials have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities, including the cloak of invisibility based on coordinate transformation. Here we present the design of a non-magnetic cloak operating at optical frequencies. The principle and structure of the proposed cylindrical cloak are analyzed, and the general recipe for the implementation of such a device is provided. The cloaking performance is verified using full-wave finite-element simulations.Comment: 10 pages, 4 figure

Resonant light interaction with plasmonic nanowire systems

We compare the optical response of isolated nanowires, double-wire systems, and Pi-structures, and show that their radiation is well described in terms of their electric and magnetic dipole moments. We also show that both dielectric permittivity and magnetic permeability can be negative at optical and near infrared frequencies, and demonstrate the connection between the geometry of the system and its resonance characteristics. We conclude that plasmonic nanowires can be employed for novel negative-index materials. Finally, we demonstrate that it is possible to construct a nanowire-based,transparent nanoresonator\u27 with dramatically enhanced intensity and metal concentration below 5%

The system of monitoring of epilepsy in a sleep

The slow development of the pathological process of neurodegeneration in the brain structures through appointment of appropriate medications can significantly reduce the risks of disability and improve the patient’s quality of life. Currently, it is in many cases possible to carry out therapeutic treatment. For best results, the early diagnosis and instrumental monitoring of the treatment strategy, that is, the monitoring system. System analysis of information about motor activity of the patient during his sleep is likely to monitor epilepsy, including remote, and to predict the patient's condition