Manufacture of electrical and magnetic graded and anisotropic materials for novel manipulations of microwaves

Spatial transformations (ST) provide a design framework to generate a required spatial distribution of electrical and magnetic properties of materials to effect manipulations of electromagnetic waves. To obtain the electromagnetic properties required by these designs, the most common materials approach has involved periodic arrays of metal-containing subwavelength elements. While aspects of ST theory have been confirmed using these structures, they are often disadvantaged by narrowband operation, high losses and difficulties in implementation. An all-dielectric approach involves weaker interactions with applied fields, but may offer more flexibility for practical implementation. This paper investigates manufacturing approaches to produce composite materials that may be conveniently arranged spatially, according to ST-based designs. A key aim is to highlight the limitations and possibilities of various manufacturing approaches, to constrain designs to those that may be achievable. The article focuses on polymer-based nano- and microcomposites in which interactions with microwaves are achieved by loading the polymers with high-permittivity and high-permeability particles, and manufacturing approaches based on spray deposition, extrusion, casting and additive manufacture

A versatile fluorescence lifetime imaging system for scanning large areas with high time and spatial resolution

"Published in SPIE Proceedings Vol. 9286"We present a flexible fluorescence lifetime imaging device which can be employed to scan large sample areas with a spatial resolution adjustable from many micrometers down to sub-micrometers and a temporal resolution of 20 picoseconds. Several different applications of the system will be presented including protein microarrays analysis, the scanning of historical samples, evaluation of solar cell surfaces and nanocrystalline organic crystals embedded in electrospun polymeric nanofibers. Energy transfer processes within semiconductor quantum dot superstructures as well as between dye probes and graphene layers were also investigated.This work was financially supported by the European Regional Development Fund (ERDF) through Programa Operacional Factores de Competitividade (COMPETE: FCOMP-01-0124-FEDER-014628) and the Portuguese Fundacao para a Ciencia e Tecnologia (FCT) through the projects "Functional structuring, inter-particle interaction and energy transfer in ensembles of nanocrystal dots" (PTDC/FIS/113199/2009), Ultra-fast spectroscopy on the dynamics and relaxation of Dirac electrons in graphene" (PTDC/FIS/101434/ 2008) and "Low dimensional nanostructures for nonlinear optical applications" PTDC/CTmNAN/114269/2009

A split ring resonator dielectric probe for near-field dielectric imaging

A single split-ring resonator (SRR) probe for 2D surface mapping and imaging of relative dielectric permittivity for the characterisation of composite materials has been developed. The imaging principle, the analysis and the sensitivity of the SRR surface dielectric probe data is described. The surface dielectric properties of composite materials in the frequency range 1-3 GHz have been measured based on the magnetic resonance frequency of the transmission loss of the SRR dielectric probe when in contact with the surface. The SRR probe performance was analysed analytically and using full-wave simulation, and predictions showed close agreement with experiment for composite materials with spatially varying dielectric permittivity manufactured by 3D printing. The spatial and permittivity resolution of the SRR dielectric probe were controlled by the geometrical parameters of the SRR which provided flexibility to tune the SRR probe. The best accuracy of the dielectric permittivity measurements was within 5%

Real-time rheological monitoring with the smart stirrer

This paper presents an approach for wireless real-time measurements of dynamic viscosity in the range of 50-1000 mPa·s utilising a laboratory hotplate in conjunction with the Smart Stirrer device. The Smart Stirrer, an innovative tool resembling a conventional magnetic stirrer enhanced with embedded System-on-Chip (SoC) Bluetooth Low Energy (BLE) module, inertial measurement unit (IMU) and magnetometer sensors, serving as a platform for viscosity monitoring. The principle of measurement based on the interaction between the magnetic field of the hotplate’s magnet and the Smart Stirrer’s internal magnets, with variations in a liquid viscosity impacting the rotational dynamics of the Stirrer and measured by the sensors. The paper details the experimental setup, data acquisition, and analysis procedures, demonstrating the capability of the system to accurately and non-invasively measure the viscosity of various liquid solutions in real-time. The method addresses the practical limitations of existing methods and offers a integrative approach for monitoring in-situ rheological properties in laboratory settings. It stands out for its simplicity, ease of integration, and potential for broader applications, making it a valuable tool in various fields requiring fluid property measurements

Ferroelectric nanofibers with an embedded optically nonlinear benzothiazole derivative

We report measurements of the molecular first hyperpolarizability, thermal stability, photophysical, piezoelectric and ferroelectric properties of a benzothiazole derivative bearing an arylthiophene π-conjugated bridge both in solution and when embedded into a poly (L-lactic acid) (PLLA) matrix in the form of electrospun fibers with an average diameter of roughly 500 nm. The embedded nanocrystalline phenylthienyl-benzothiazole derivative, with crystal sizes of about 1.4 nm resulted in a good piezoelectric response from these functionalized electrospun fibers, indicative of a polar crystalline structure.Fundação para a Ciência e a Tecnologia (FCT

Assessment of the situation of convergence of ships at sea on the basis of COLREG

The problem of estimating the navigational situation in case of convergent ships at sea is considered. The algorithm of estimation of a situation of approach of ships according to COLREG is offered with use of the information on mutual positioning and elements of movement of ships. An algorithm for determining the mutual responsibilities of ships on the basis of information on the navigational status of ships obtained by AIS, and the situation of their convergence is proposed. The complex estimation of situation in a group of ships is offered in the form of a full connected directed graph of situations defining the degree of danger and mutual obligations according to COLREG of each of the ships in this group

Monitoring chemistry in situ with the Smart Stirrer a magnetic stirrer bar with an integrated process monitoring system

Inspired by the miniaturisation and efficiency of the sensors for telemetry, we have developed a device that provides the functionalities of laboratory magnetic stirring and integrated multi-sensor monitoring of various chemical reaction parameters. The device, called Smart Stirrer, when immersed in a solution, can in situ monitor physical properties of the chemical reaction such as the temperature, conductivity, visible spectrum, opaqueness, stirring rate, and viscosity. This data is transmitted real-time over a wireless connection to an external system, such as a PC or smartphone. The flexible open-source software architecture allows effortless programming of the operation parameters of the Smart Stirrer in accordance with the end-user needs. The concept of the Smart Stirrer device with an integrated process monitoring system has been demonstrated in a series of experiments showing its capability for many hours of continuous telemetry with fine accuracy and a high data rate. Such a device can be used in conventional research laboratories, industrial production lines, flow reactors, and others where it can log the state of the process to ensure repeatability and operational consistency

Intense optical second harmonic generation from centrosymmetric nanocrystalline para-nitroaniline

We demonstrate an approach that uses normally centrosymmetric, but highly polarizable organic molecules of para-nitroaniline (p-NA) as very efficient second harmonic generator (SHG) for near infra-red light. The approach is based on an effective manipulation of the nanocrystalline size and their assembly into a highly orientated mesocrystalline structures. The resulting mesocrystalline form of p-NA consists of multiple nanocrystals with common orientation, providing a set of surfaces with highly aligned molecules forming a head-to-tail polar arrangement. The second harmonic generation efficiency from this arrangement of mesocrystalline nanostructures is comparable to that from the conventional non-centrosymmetric organic crystals. The experimental results indicate that a very strong second-order nonlinear response can be obtained from small D-π-A organic molecules with elevated molecular hyperpolarizabilities even if these molecules tend to crystallize in centrosymmetric structures

Системно-функциональный подход к обеспечению коммунальными услугами

Purpose: the purpose of the article consists in statement of management approach to development of utilities supply processes based on conflict situations decision – making search. It had appeared in the period of the transition from the planned and directive management to market development. Methods: the research methodology is based on the system analysis of full life cycle processes functioning, forecasting of complex systems development, mathematical modeling of processes of services supply and innovative and investment projects modeling as well as development of supplying services processes. Results: the results of the work are concentrated in the presentation of systemic-functional approach to managing the development of processes of municipal services, able to resolve conflict situations in this sphere. Conclusions and Relevance: the traditional management approach on the basis of elimination of "bottlenecks" and emergencies prevailing within planned and directive system at its transformation in the market conditions has led to accumulation of conflict situations and unsolvable problems. The offered systemic-functional approach based on forecasting of full life cycle of the modernized processes and the services providing systems allows to consider costs of modernization, prime cost and quality of the rendered services. Цель: Цель статьи состоит в изложении подхода к управлению развитием процессов обеспечения коммунальными услугами, основанного на поиске разрешения конфликтных ситуаций, сложившихся при переходе от планово-директивного управления к методам управления развитием на рыночной основе . Методология проведения работы: Методология проведения исследования базируется на системном анализе полного жизненного цикла функционирования процессов, прогнозировании развития сложных систем, математическом моделировании процессов обеспечения услуг. Результаты работы: Результаты работы концентрируются в изложении системно-функционального подхода к управлению развитием процессов обеспечения коммунальными услугами, способному разрешить конфликтные ситуации в данной сфере. Выводы: Традиционный подход к управлению на основе устранения «узких мест» и аварийных ситуаций, преобладавший в рамках планово-директивной системы при его трансформации в условиях рыночных отношений привел к накоплению конфликтных ситуаций и неразрешимых проблем. Предлагаемый системно-функциональный подход, основанный на прогнозировании полного жизненного цикла модернизируемых процессов и систем обеспечения услугами, позволяет согласованно учитывать затраты на модернизацию, себестоимость и качество оказанных услуг.