Search

In high-sensitive laser interferometers, such as the gravitational-wave detector KAGRA, ultra-high quality mirrors are essential. In the case of KAGRA, where cavity-mirrors are cooled down to 20 K, we are using large-size Sapphire crystals as the substrate for the main mirrors to achieve both a good optical quality (i.e., low absorption and uniform refractive index) and optimized thermal behavior under cryogenic temperatures. In order to characterize refractive-index inhomogeneities of large-size uniaxial samples such as the KAGRA Sapphire test-masses, we developed a dedicated setup, allowing to resolve birefringence changes with a sensitivity in the order of ∆n ≈ 10 −10 and a spatial resolution of 0.3 × 0.3 mm 2. In this paper, we will further show how we could draw information of internal stress distributions from the measured birefringence and present for the first time measurements on a KAGRA-sized Sapphire substrate which has been characterized in terms of absorption already in an earlier work. Both birefringence inhomogeneities and absorption distributions will be compared and correlations discussed.

Frequency dependent squeezing is the main upgrade for achieving broadband quantum noise reduction in upcoming observation runs of gravitational wave detectors. The proper frequency dependence of the squeezed quadrature is obtained by reflecting squeezed vacuum from a Fabry-Perot filter cavity detuned by half of its linewidth. However, since the squeezed vacuum contains no classical amplitude, co-propagating auxiliary control beams are required to achieve the filter cavity's length, alignment, and incident beam pointing stability. In our frequency dependent squeezing experiment at the National Astronomical Observatory of Japan, we used a control beam at a harmonic of squeezed vacuum wavelength and found visible detuning variation related to the suspended mirrors angular drift. These variations can degrade interferometer quantum noise reduction. We investigated various mechanisms that can cause the filter cavity detuning variation. The detuning drift is found to be mitigated sufficiently by fixing the incident beam pointing and applying filter cavity automatic alignment. It was also found that there is an optimal position of the beam on the filter cavity mirror that helps to reduce the detuning fluctuations. Here we report a stabilized filter cavity detuning variation of less than 10$\,$Hz compared to the 113$\,$Hz cavity linewidth. Compared to previously published results [Phys. Rev. Lett. 124, 171101 (2020)], such detuning stability would be sufficient to make filter cavity detuning drift induced gravitational wave detector detection range fluctuation reduce from $11\%$ to within $2\%$., Comment: Accepted by PRD

In developing countries, energy is recognized to be essential for promoting equitable growth, fostering social inclusion and preserving the environment. Nevertheless, the current state of the energy sectors of developing countries still represents a major hindrance to the fulfillment of this goal. In this frame, electrical energy storage may allow a cost-effective exploitation of renewable sources in order to cope with the improvement of the power supply service via local national grids, but mainly it may become a building block of rural electrification through integration within off-grid systems. This paper focuses on electrical energy storage in sub-Saharan Africa providing an overview of the main aspects of this theme. Indeed, the specific features of the power sector in sub-Saharan Africa are analyzed about the framework of application of electrical energy storage. The typical technologies implemented in this context and the status of the market as well as of the economic models to support the diffusion of storage together with renewable energy technologies are highlighted. Moreover, an overview of technical aspects such as storage capacity sizing and interface converters for integration with renewables are described. Finally, an experimental application of a hybrid micro-grid in rural Tanzania is presented. With this paper, our aim is to provide an overall view, within the main technical and non-technical aspects, of electrical energy storage in a context – sub-Saharan Africa – which has a huge potential, both in market terms, but also with regards to the possibility to develop and implement alternative technical solutions which may be integrated in the power systems of high income countries as well. © 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ available 1 november 2018

The paper retraces the implementation of a biogas energy programme within the Best Ray project run in Tanzania 2008–2011. The objective of the Best Ray project was to empower rural communities by providing them with modern and renewable energy technologies to better tackle Millennium Development Goals. An important activity of the project was the construction of a biogas system in secondary school solve a sanitation problem and provide the school with a free and reliable energy supply. After a field assessment, the project directed the resources to small domestic biogas installation rather than large institutional ones as future sustainability seemed to be better granted. Best Ray merged the Tanzanian Domestic Biogas Programme. Trainings were organized and 25 biogas plants constructed. The technology is simple and the design effective, but still the cost seems high for a rural context. Final beneficiaries are appreciating the technologies for reasons that were not predictable by those who ideated the project.

Purpose: Assessment on enucleated pig eyes of a novel and minimally invasive method for the continuous monitoring of intraocular pressure (IOP), based on a novel wireless contact lens sensor (CLS). Methods: The wireless CLS is a disposable silicone soft contact lens with a sensor embedded in it, allowing the wireless measurement of changes in corneal curvature induced by IOP variations. A CLS was adapted and tested on enucleated pig eyes. To demonstrate the measurement principle of the device, the enucleated pig eye was cannulated, allowing precise control of IOP. The CLS signal was then compared to the imposed IOP. Results: First, the IOP of enucleated pig eyes was changed between 11 and 14 mmHg, simulating ocular pulsation. Then, IOP was changed with static steps of 1 mmHg between 20 and 30 mmHg to assess the reproducibility and linearity of the CLS. In both cases, measurements from the CLS and IOP showed very good correlation. A calibration graph shows that the CLS is capable of monitoring the IOP of each individual eye with a reproducibility of ± 0.2 mmHg (95% confidence interval). Conclusion: The wireless CLS shows a good functionality to monitor the IOP on enucleated pig eyes. The device is placed in the same way as a soft disposable contact lens. This device would allow a minimally invasive and continuous monitoring of IOP over prolonged periods of up to 24 hr, regardless of patient activity, thus opening up new diagnostic and therapeutic methods to manage glaucoma.

PURPOSE. To present a novel and minimally invasive approach to intraocular pressure (IOP) monitoring based on a sensing contact lens. METHODS. The key element of this measurement method is a soft contact lens with an embedded microfabricated strain gauge allowing the measurement of changes in corneal curvature correlated to variations in IOP. A prototype of this sensing contact lens was adapted and tested on enucleated porcine eyes. To verify the measurement principle of the device, the posterior chamber of the pig eyes was cannulated and connected to a syringe pump and a pressure sensor for precise control of IOP. The measurements of the contact lens were then compared to the ones from the pressure sensor, while pressure variations were induced through the cannula. RESULTS. Enucleated porcine eyes were stimulated with increasing and decreasing ramps of IOP. Measurements from the sensing contact lens and from the pressure sensor showed very good correlation, proving the high potential of this new measurement principle. In this study, a typical signal from the sensing contact lens obtained during the experiments is presented and discussed. CONCLUSIONS. The sensing contact lens shows the potential for continuously monitoring IOP in enucleated porcine eyes. The ultimate step will be the validation of the system and the reproducibility of results in humans. The device is placed in the same way as a corrective contact lens, no anesthesia is required, and vision remains almost unimpaired. This device would allow minimally invasive IOP monitoring over prolonged periods, regardless of the patient's position and activity, thus opening up new diagnostic and therapeutic methods for the management of glaucoma.

Despite the electrical energy scenarios are quite different between industrialized countries and emerging and developing ones, for both contexts, energy storage systems could play a key role in the next future. Specifically, in emerging and developing countries, energy storage systems may allow a cost-effective exploitation of renewable sources in order to cope with energy security for centralized energy systems, but mainly to become a building block of rural electrification by off-grid power systems. In this paper a short overview of energy storage systems within the emerging and developing countries scenarios is reported. Specifically the paper provides a description of the typical configuration for batteries within off-grid systems and an overview of the typical economic models for batteries applications and the regulatory frameworks when off-grid applications are introduced. Finally the description of an experimental project in rural area of Tanzania points out the peculiar characteristics of batteries application in off-grid applications.

KAGRA is a new gravitational wave detector which aims to begin joint observation with Advanced LIGO and Advanced Virgo from late 2019. Here, we present KAGRA's possible upgrade plans to improve the sensitivity in the decade ahead. Unlike other state-of-the-art detectors, KAGRA requires different investigations for the upgrade since it is the only detector which employs cryogenic cooling of the test mass mirrors. In this paper, investigations on the upgrade plans which can be realized by changing the input laser power, increasing the mirror mass, and injecting frequency dependent squeezed vacuum are presented. We show how each upgrade affects to the detector frequency bands and also discuss impacts on gravitational-wave science. We then propose an effective progression of upgrades based on technical feasibility and scientific scenarios., Comment: 7 pages, 3 figures, Proceedings for the Fifteenth Marcel Grossmann Meeting, Rome, July 1-7, 2018