Recent Progress and Development Trend of Self-Sweeping Fiber Laser

Since 2011, when Kir’yanov et al. first reported a new wavelength self-sweeping ytterbium-doped fiber laser that does not rely on any tuning element but only on the dynamic induced grating generated in the gain fiber by the standing wave resonator structure, the self-sweeping effect based on fiber waveguides has been extensively studied, leading to great progress in fundamental physics and other applications of self-sweeping fiber lasers. Different doped fiber lasers have not only achieved the self-sweeping effect, but also observed new phenomena such as anomalous self-sweeping and continuous pulses. Due to their remarkable spectral and pulsed characteristics, self-sweeping fiber lasers have been widely used in spectral detection, fiber sensing and short pulse synthesis. In this paper, we will introduce the classification of different doped self-sweeping fiber lasers, summarize their different implementations, and introduce their self-sweeping laws, pulse characteristics, recent progress of applications and future development prospects.

A new outlook at Uranus' and Neptune's 10 keV--5 MeV energy electron distributions from data analyses and physics-based models

<p>We present our latest understanding of the processes that shape the spatial distributions of energetic electrons trapped in the magnetospheres of Uranus (L < 15) and Neptune (L < 25). To determine what controls the energy and spatial distributions throughout the different magnetospheres, we compute the time evolution of particle distributions with the help of a diffusion theory particle transport code that solves the governing 3-D Fokker-Planck equation. Different mechanisms of particle loss, source and transport are numerically examined. Our theoretical modeling is guided by the analysis of particle, field and wave data collected during Voyager 2’s flyby of Uranus in January 1986 and at Neptune in August 1989.</p> <p>Our preliminary data-model comparison results at Uranus show that adiabatic transport cannot explain the radial and angular features of warm to ultra-relativistic electron populations within the ~1-15 L region. Our simulation results also suggest that, with absence of loss mechanisms inside L = 15, energetic and radiation-belt electron populations would be higher by 1-3 orders of magnitude in intensity close to the planet (L ~ 1-8). Particularly, our results confirm that moon sweeping effect is a significant loss mechanism at Uranus. Nonetheless, other radial, energy and pitch-angle dependent mechanisms seem to be missing to explain the in-situ data. We will thus present our ongoing effort to examine the role of --for instance, Uranus’ rings system, atomic hydrogen corona and wave activity inward of L ~ 8-10 to improve our modeling of Uranus’ electron populations between L values of 1 and 15.</p> <p>Our first physics-based model of energetic electrons at Neptune will be presented, emphasizing first the role of radial transport and moon sweeping effect for the 1-25 L region before investigating new processes. Our models developed for Uranus and Neptune are based on the theoretical modeling of electron distributions at Saturn, which included the modeling of radial transport and interactions of electrons with Saturn's dust/neutral/plasma environments and waves, as well as particle sources from high-latitudes, interchange injections, and outer magnetospheric region. Comparisons between the distributions of electron populations at Gas and Ice Giant systems will be discussed.</p> <p>Data analysis, theoretical modeling, and numerical computations for Uranus and Neptune are carried out by adapting the Kronian modeling tools developed at Southwest Research Institute to the Ice Giants environment. Key data analysis, theoretical modeling, and numerical computational tasks for Saturn were carried out at Southwest Research Institute under NASA GSFC grant 80NSSC18K1100.</p>

Variation in radical antioxidant capacity and the total amount of carotenoids in razor clams, Ensis marginatus (Pennant, 1777), from the Çanakkale Strait (Abidealtı), Turkey

Metabolic activities such as breathing and digestion, resulting from natural functions of the body through oxidation, lead to the formation of free radicals that cause cancer, premature cardiac aging and some chronic diseases. Antioxidants are substances that remove free radicals and prevent cell damage. Seafood significantly contributes to the elimination of free radicals, especially owing to its high quality nutrient content. In this context, the objective of the study was to determine the radical antioxidant capacity and the total amount of carotenes in razor clams. The IC50 (mg g−1) value of the DPPH radical sweeping effect varied over the months (p < 0.05), showing the highest value in June, gradually decreasing from September and reaching the lowest level in February. The total amount of carotenoids also varied, with the highest value in September (p < 0.05). The total amount of chlorophyll ranged from 6.15 μg g−1 in August to 66.71 μg g−1 in December.

Spatio-temporal intermittency of the turbulent energy cascade

In incompressible and periodic statistically stationary turbulence, exchanges of turbulent energy across scales and space are characterised by very intense and intermittent spatio-temporal fluctuations around zero of the time-derivative term, the spatial turbulent transport of fluctuating energy and the pressure–velocity term. These fluctuations are correlated with each other and with the intense intermittent fluctuations of the interscale energy transfer rate. These correlations are caused by the sweeping effect, the link between nonlinearity and non-locality, and also relate to geometrical alignments between the two-point fluctuating pressure force difference and the two-point fluctuating velocity difference in the case of the correlation between the interscale transfer rate and the pressure–velocity term. All these processes are absent from the spatio-temporal-average picture of the turbulence cascade in statistically stationary and homogeneous turbulence.

Self-removal of condensed water on the legs of water striders

The ability to control drops and their movements on phobic surfaces is important in printing or patterning, microfluidic devices, and water-repellent materials. These materials are always micro-/nanotextured, and a natural limitation of repellency occurs when drops are small enough (as in a dew) to get trapped in the texture. This leads to sticky Wenzel states and destroys the superhydrophobicity of the material. Here, we show that droplets of volume ranging from femtoliter (fL) to microliter (μL) can be self-removed from the legs of water striders. These legs consist of arrays of inclined tapered setae decorated by quasi-helical nanogrooves. The different characteristics of this unique texture are successively exploited as water condenses, starting from self-penetration and sweeping effect along individual cones, to elastic expulsion between flexible setae, followed by removal at the anisotropic leg surface. We envision that this antifogging effect at a very small scale could inspire the design of novel applicable robust water-repellent materials for many practical applications.

A Novel Approach for Supplying Wireless Energy to Multiple Devices Simultaneously Using Sweeping Effect

There has been great interest in wireless power transmission since 2007 when a novel approach was presented by a group of scientists at MIT. With this new technique, power transmission range is possible for a couple of meters with high efficiency; however, to be able to use this technique in our lives with high efficiency and long transfer range, small structured devices and new design techniques are strongly required. In this chapter, the investigation on supplying energy by sweeping was presented. The experimental results claim that energy could be supplied to multiple devices almost at the same time. If the range of chosen frequency increases, the number of devices could be increased as well, considering slight energy efficiency loss in the transfer system. The authors hope that the proposed technique gives inspiration to the designers and to the market.

Sweeping Effect on Witricity

Wireless power transmission has become very popular since 2007 and there are many movements to integrate this new technique into our daily lives rapidly. For now, the main drawback in this technology is efficiency in long range. Whenever this challenge is tackled and many devices charging without cables enter daily life, there will be a desire to charge them at the same time without trouble. In this paper, the investigation results of sweeping are presented which seems to be the most appropriate approach for charging many devices at the same time. Experimental results offer that narrow MHz band is suitable for a few devices to supply power whereas a wide range of MHz band gives the opportunity to power up much more devices without remarkable efficiency loss. It is believed that these results will inspire new thoughts and point the way of new designs.

Dark Optical Fibre as a Modern Solution for Broadband Networked Cities

The world economy is moving in transition from the industrial age to a new set of rules—that of the so-called information society—which is rapidly taking shape in different multiple aspects of everyday life: The exponential growth of the Internet, the explosion of mobile communications, the rapid emergence of electronic commerce, the restructuring of various forms of businesses in all sectors of the modern economy, the contribution of digital industries to growth and employment, and so forth are some amongst the current features of the new global reality. Changes are usually underpinned by technological progress and globalisation, while the combination of global competition and digital technologies is having a crucial sweeping effect. Digital technologies facilitate the transmission and storing of information while providing multiple access facilities, in most cases, without significant costs. As digital information may be easily transformed into economic and social value, it offers huge opportunities for the development of new products, services, and applications. Information becomes the key resource and the engine of the new e-economy. Companies in different sectors have started to adapt to the new economic situation in order to become e-businesses (European Commission, 2001c). The full competitiveness of a state in the current high-tech, digitally converging environment is strongly related to the existence of a modern digital infrastructure of high capacity and high performance that is rationally deployed, properly priced, and capable of providing easy, cost-effective, secure, and uninterrupted access to the international “digital web” of knowledge and commerce without imposing any artificial barriers and/or restrictions.