DOES SPECIALIZATION IN KARATE AFFECT REACTION TIME IN SPECIFIC KARATE KUMITE SITUATIONS?

The aim of this study was to investigate the effect of karate specialization on the reaction time in specific karate kumite situations. In order to maximize the ecological validity of experimental set-up, we used our recently proposed and evaluated video-based method (Mudric et al., 2015). Within this method, the reaction time is calculated from the kinematic parameters recorded on both offensive action stimuli and defensive action responses. The results obtained from three groups of subjects (i.e., karate kumite, karate kata and beginners) indicate significant differences in reaction time between the beginners and both specialized karate groups. There were also prominent but not significant differences between the karate kumite and karate kata. These findings suggest that particular sport specialization could improve reaction time of an athlete in specific sport situations

Macro, Micro, and Nano Level Analysis of Cavitation Damage Mechanism in FCC Materials

The aim of this paper is to demonstrate the analysis of cavitation damage mechanism in FCC (Face Centered Cub ic ) materials , and to establish a possible application of the cavitation phenomenon as an efficient method to modify surface properties. Three FCC materials ( c opper, AlMg - alloy and stainless steel ( St.St.316 ) ) were subjected to high speed submerged cavitating jets under certain working conditions, for different time periods. The force generated by cavitation is employed to deform and to damage the surface in scales ranging from nano to micro and macro . The target surface s were investigated with various techniqu es. Results indicate that at short exposure times, the observed characteristic features in the microstructure – hills, holes and wavy configuration – can be related to the start of the plastic deformation of the specimen surface. By increasing the exposur e time , the surface s bec a me eroded, the damaged area is characterized by many rings , with different degrees of surface roughness . The results related to the early stage of cavitation damage demonstrate the possibility to us e cavitation bubbles as a micro/ n ano fabrication method for the surface preparation/modification or for example shoot - less surface peening

Plastic Deformation and Modification of Surface Characteristics in Nano and Micro Levels and Enhancement of Electric Field of FCC Materials Using Cavitaion Phenomenon

The aim of this paper is to demonstrate and establish a possible application of the cavitation phenomenon as an efficient method to modify surface properties. Three FCC (Face Centered C ubic) materials were subjected to high s peed submerged cavitating jets under certain working conditions, for time periods between 15 and 1,800 s. The force generated by cavitation is employed to modify the surface roughness in nano and micro scales. The target surface was investigated with digit al optical microscopy , atomic force and electrostatic force microscopy (AFM and EFM) and also with a white light interferomet er . These different observation techniques indicate that at short exposure times, the observed characteristic features in the micro structure – hills, holes and wavy configurat ion – can be related to the start of the plastic deformation of the specimen surface. Longer exposure times inevitably result in a greater number of jet specimen interactions leading to specimen erosion and fract ure. The results demonstrate the possibility to use cavitation bubbles as a micro - nanofabrication method for the surface preparation /modification or shoot - less surface peening. EFM results present a possibility of using cavitation as tool to enhance the e lectrostatic properties of a metal surface by modifying its roughness. The degree of enhancement depends o n the material properties

Experimental Study on the Influence of Geometrical Parameters on the Cavitation Erosion Characteristics of High Speed Submerged Jets

The influence of the geometrical working parameters on the cavitation erosion process was experimentally investigated by exposing the surfaces of copper samples (as a kind of Face Centred Cubic material (FCC)) to a high speed submerged cavitating jet for various time periods using a cavitating jet generator. The resulting erosion rate and eroded area is discussed in detail. Influences of the non-dimensional standoff distance, the non-dimensional aspect ratio and the angle of attack is experimentally determined. The results show that the erosion rate and weight loss are strongly depending on these separately investigated parameters. With this test rig facility and applied hydrodynamic parameters the maximum erosion was found to take place with a non-dimensional standoff distance varying between 42 and 48 (depending on the nozzle diameter), with a non-dimensional aspect ratio of 11 and with 105 angle of attack. A model to explain the influence of the angle of attack on the erosion rate based on the cavity bubble and target surface interaction is presented. In addition, the obtained results demonstrate that the used small diameter (0.4-0.6 mm) water cutting nozzles could be applied for metal machining by cavitation and cavitation cutting with low power consumption and high cutting efficiency

Localised tuneable composition single crystal silicon-germanium-on-insulator for low cost devices

The realisation of high quality silicon-germanium-on-insulator (SGOI) is a major goal for the field of silicon photonics because it has the potential to enable extremely low power active devices functioning at the communication wavelengths of 1.3 µm and 1.55 µm. In addition, SGOI has the potential to form faster electronic devices such as BiCMOS transistors, and could also form the backbone of a new silicon photonics platform that extends into the mid-IR wavelengths for applications in, amongst others, sensing and telecoms. In this paper, we present a novel method of forming single crystal, defect free SGOI using a rapid melt growth technique. We use tailored structures to form localised uniform composition SGOI strips, which are suitable for state of the art device fabrication. This technique could pave the way for the seamless integration of electronic and photonic devices using only a single, low cost Ge deposition step

Suspended silicon integrated platform for the long-wavelength mid-infrared band

The atmospheric-transmission window and the fingerprint region of many substances overlaps with the long-wave infrared band. This has enabled the emergence of a new path for photonic integrated circuits, which could exploit the potential applications of this wavelength range, including chemical and bio sensing. In this work we review our latest advances in the suspended silicon platform with subwavelength grating lateral cladding at 7.7-µm wavelength. Suspended waveguides only require one lithographic etch step and can be specifically designed to maximize sensitivity when used as sensors. Waveguides with propagation loss of 3.1±0.3 dB/cm are demonstrated, as well as bends with less than 0.1 dB/bend. Suspended waveguides based on shifted Bragg grating lateral cladding are also reported, with propagation loss of 5.1±0.6 dB/cm. These results prepare the ground for the development of a platform capable of covering the entire mid-infrared band. Keywords: suspended silicon, mid-infrared, long-wave infrared, subwavelength grating, Bragg.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Subwavelength metamaterial engineering for silicon photonics

Waveguides structured at the subwavelength scale frustrate di raction and behave as optical metamaterials with controllable refractive index. These structures have found widespread applications in silicon photonics, ranging from sub-decibel e ciency bre-chip couplers to spectrometers and polarization rotators. Here, we briefly describe the design foundations for sub-wavelength waveguide devices, both in terms of analytic e ective medium approximations, as well as through rigorous Floch-Bloquet mode simulation. We then focus on two novel structures that exemplify the use of subwavelength waveguides: mid-infrared waveguides and ultra-broadband beamsplitters.Universidad de M alaga,Campus de Excelencia Internacional Andalucía Tech. Ministerio de Econom a y Competitividad, Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad (cofi nanciado FEDER), Proyecto TEC2013-46917-C2-1-R, Proyecto TEC2016-80718-

Mid-infrared Suspended Waveguide Platform and Building Blocks

In this work we present our recent progress in the development of a platform for the mid-infrared wavelength range, based on suspended silicon waveguide with subwavelength metamaterial cladding. The platform has some intrinsic advantages, which make it a very promising candidate for sensing applications in the fingerprint region. Specifically, it can cover the full transparency window of silicon (up to a wavelength of 8 μm), only requires one lithographic etch-step and can be designed for strong light-matter interaction. Design rules, practical aspects of the fabrication process and experimental results of a complete set of elemental building blocks operating at two very different wavelengths, 3.8 μm and 7.67 μm, will be discussed. Propagation losses as low as 0.82 dB/cm at λo=3.8 μm and 3.1 dB/cm at λo=7.67 μm are attained, for the interconnecting waveguides.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Enhanced sensitivity subwavelength grating waveguides for silicon photonics sensing applications

OSA (Optical Society of America)In this work we will review the enormous potential of subwavelength grating waveguides for sensing applications in the near and mid-infrared bands, demonstrating the capability to engineer the mode profile to maximize the light-matter interaction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

High performance silicon photonic devices based on practical metamaterials

Robert Halir, et al., "High performance silicon photonic devices based on practical metamaterials," OECC/PSC, 7-12 July 2019, Fukuoka (Japan)Subwavelength grating metamaterials are enabling a new generation of high-performance silicon photonic devices. Here we discuss the fundamental physics along with some of the latest advances in this rapidly expanding field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministerio de Economía y Competitividad, Programa Estatal de Investigación Orientada a los Retos de la Sociedad (cofinanciado FEDER) – TEC2016-80718-R, TEC2015-71127-C2-1-R (FPI BES-2016-077798) and IJCI-2016-30484; Community of Madrid – S2018/NMT-4326, Marie Sklodowska-Curie –734331, Czech Science Foundation – 1900062