PRESSURE MEASUREMENT OF INDUCED EXTERNAL ATMOSPHERE ON THE RUSSIAN SEGMENT OF THE INTERNATIONAL SPACE STATION IN EXPERIMENT «CONTROL»

The goals and objectives of space experiment Control to study parameters of the induced external atmosphere of the Russian Segment of the International Space Station are presented. The processing and analysis procedure for telemetry data obtained using scientific equipment Indicator - ISS is described. Numerical calculations were performed by direct statistical modeling of the flow around the pressure sensor by incoming flotation the Earth's outer atmosphere in the background measurement conditions, as well as in disturbed conditions with two vernier engines of the Zvezda module being operated. A correction function of the pressure sensor is obtained depending on the orientation, temperature factor and selected model of interaction of incident flow molecules with the internal and external device surfaces. The results of numerical modeling of the jet discharges of the the Zvezda vernier engine were compared with the data obtained in full-scale pressure measurements in experiment Control. Key words: pressure sensor, orbital station, induced external atmosphere, direct statistical modeling method.

Ultra-Widefield Fluorescein Angiography Image Brightness Compensation Based on Geometrical Features

Ultra-widefield fluorescein angiography (UWFA) is an emerging imaging modality used to characterise pathologies in the retinal vasculature, such as microaneurysms (MAs) and vascular leakages. Despite its potential value for diagnosis and disease screening, objective quantitative assessment of retinal pathologies by UWFA is currently limited because laborious manual processing is required. In this report, we describe a geometrical method for uneven brightness compensation inherent to UWFA imaging technique. The correction function is based on the geometrical eyeball shape, therefore it is fully automated and depends only on pixel distance from the center of the imaged retina. The method’s performance was assessed on a database containing 256 UWFA images with the use of several image quality measures that show the correction method improves image quality. The method is also compared to the commonly used CLAHE approach and was also employed in a pilot study for vascular segmentation, giving a noticeable improvement in segmentation results. Therefore, the method can be used as an image preprocessing step in retinal UWFA image analysis.

A comprehensive non-uniformity correction method for EMCCD

The non-uniformity of image directly affects the application of EMCCD in various disciplines. The proposed method can significantly improve the uniformity of EMCCD output image. The correction algorithm of "reverse split and forward recovery" is determined through analyzing the imaging model of EMCCD, and the comprehensive non-uniformity correction function model is established. The 8-tap EMCCD chip CCD220 of British e2v company is used for experimental verification. The results show that after the comprehensive correction the consistencies of the light response characteristic curve and the multiplication gain curve of each channel in EMCCD are obviously improved, and also the photo response non-uniformity (PRNU) of the output image is substantially reduced from 24.5 to 4.1%, which prove the effectiveness of the proposed method.

Intelligent Correction System of Students’ English Pronunciation Errors Based on Speech Recognition Technology

With the increasingly frequent international exchanges, English has become a common language for communication between countries. Under this research background, in order to correct students’ wrong English pronunciation, an intelligent correction system for students’ English pronunciation errors based on speech recognition technology is designed. In order to provide a relatively stable hardware correction platform for voice data information, the sensor equipment is optimized and combined with the processor and intelligent correction circuit. On this basis, the MLP (Multilayer Perceptron) error correction function is defined, with the help of the known recognition confusion calculation results, the actual input speech error is processed by gain mismatch, and the software execution environment of the system is built. Combined with the related hardware structure, the intelligent correction system of students’ English pronunciation error based on speech recognition technology is successfully applied, and the comparative experiment is designed the practical application value of the system is highlighted.

Performance Evaluation of a Forward Swept Blade for Vertical Axis Wind Turbine through CFD Simulation

With high power density wind farms, reduced environmental impact, and logistical requirements, vertical axis wind turbines offer a good value proposition for the challenging topography of the Philippines. In this study, the forward-swept wing was incorporated as a VAWT blade; its swept angle is defined along the axis of rotation and evaluated its performance through CFD simulation utilizing SST k-ω turbulence model with curvature correction function validated against experimental data. The forward-swept blade exhibited improved performance over a limited tip speed ratio (λ) with up to a 7.2% increase in peak performance occurring at λ = 2.6 and with the highest increase of 14 % in λ = 2.387. The increase is due to an increased peak torque output characterized by stall delay attributed to forward swept high angle of attack.

Enhanced Steady-State Solution of the Infinite Moving Line Source Model for the Thermal Design of Grouted Borehole Heat Exchangers with Groundwater Advection

The objective of this study is to assess the suitability of the analytical infinite moving line source (MLS) model in determining the temperature of vertical grouted borehole heat exchangers (BHEs) for steady-state conditions when horizontal groundwater advection is present. Therefore, a numerical model of a grouted borehole is used as a virtual reality for further analysis. As a result of the first analysis, it has been discovered that established analytical methods to determine the borehole thermal resistance as a mean value over the borehole radius can also be applied to BHEs with groundwater advection. Furthermore, the deviation between a finite MLS and the infinite MLS is found to be only less than 5% for BHEs of a depth of 30 m or more, and Péclet numbers greater than 0.05. Finally, the accuracy of the temperature change calculated with the infinite MLS model at the radius of the borehole wall compared to the temperature change at a numerically simulated grouted borehole is addressed. A discrepancy of the g-functions resulting in a poor dimensioning of BHEs by the infinite MLS model is revealed, which is ascribed to the impermeable grouting material of the numerical model. A correction function has been developed and applied to the infinite MLS model for steady-state conditions to overcome this discrepancy and to avoid poor dimensioning of BHEs.

Photonic contact thermometry using silicon ring resonators and tuneable laser-based spectroscopy

Photonic sensors offer the possibility of purely optical measurement in contact thermometry. In this work, silicon-based ring resonators were used for this purpose. These can be manufactured with a high degree of reproducibility and uniformity due to the established semiconductor manufacturing process. For the precise characterisation of these photonic sensors, a measurement setup was developed which allows laser-based spectroscopy around 1550 nm and stable temperature control from 5 °C to 95 °C. This was characterised in detail and the resulting uncertainty influences of both the measuring set-up and the data processing were quantified. The determined temperature stability at 20 °C is better than 0.51 mK for the typical acquisition time of 10 s for a 100 nm spectrum. For a measurement of >24 h at 30 °C a standard deviation of 2.6 mK could be achieved. A hydrogen cyanide reference gas cell was used for traceable in-situ correction of the wavelength. The determined correction function has a typical uncertainty of 0.6 pm. The resonance peaks of the ring resonators showed a high optical quality of 157 000 in the average with a filter depth of up to 20 dB in the wavelength range from 1525 nm to 1565 nm. When comparing different methods for the determination of the central wavelength of the resonance peaks, an uncertainty of 0.3 pm could be identified. A temperature-dependent shift of the resonance peaks of approx. 72 pm/K was determined. This temperature sensitivity leads together with the analysed uncertainty contributions to a repeatability of better than 10 mK in the analysed temperature range from 10 °C to 90 °C.

Research of the Negative Influence of Dimmed LED Luminaires in Context of Smart Installations

This article deals with the investigation of the negative impacts of dimmed public, industrial and office LED (light emitting diode) light installations. This approach is required due to the uncertain design of LED ballasts, while manufacturers do not implement the required PFC (power factor correction) function. Therefore, the focus is on a brief description of the principles of negative influences such as: low power factor, high inrush current and high total harmonic distortion based on direct confrontation with actual standards (IESC EN, NEMA, ENERGY STAR). Further, the behavior of LED drivers is explained under nominal load and dimmed up to critical level. Presented findings confirm issues reported by users from larger installations where LED fittings are dimmed over a certain level. The article includes recommendations for consumers and producers of LED fittings about main issues from the scientific and user points of view. Presented facts conclude on the necessity of studying the marginal operating state of LED fittings aiming at THD (total harmonic distortion), PF (real power factor) and inrush currents.

Method to Correct the Velocity Variation Information of an Automatic Crash Notification System in Vehicle-to-Rigid Barrier Frontal Collisions

Automatic crash notification systems (ACNSs) play a key role in post-accident safety. To improve the accuracy and efficiency of ACNSs, a method to correct the velocity variation information of ACNSs was established. First, after the acceleration data of sled crash tests were analysed, the factors affecting the accuracy of the velocity variation information were determined, and the influence of the discrimination threshold and acceleration curve shape on the velocity variation information was examined. Second, according to the acceleration data generated by the simulation model of a sled crash, the correlation between the accuracy of the velocity variation information and influencing factors was modelled. Third, an automatic crash notification algorithm involving a velocity variation correction function (VVCF) was proposed based on the correlation model. Finally, to verify its reliability, the improved algorithm was applied to an automatic crash notification system (ACNS) terminal. The validation results show that the ACNS terminal can accurately identify collisions and transmit accident information. Moreover, more accurate velocity variation information can be retrieved.

Measuring Average Luminance for Road Lighting from Outside the Carriageway with Imaging Sensor

The main quality condition in street lighting is luminance distribution. During the carrying out of the literature, average luminance is the most important parameter to check. The standard BS EN 13201-3 imposes that average luminance must be calculated for the observer placed in the center of each circulating lane. As a consequence, according to these standards, the measurements can be done only on streets without traffic. Stopping the traffic on all lanes is very difficult. This paper proposes a solution for measuring the average luminance from outside the carriageway. The research was performed by simulations/calculations and was validated by field measurements. Imaging sensors were used to measure average luminance, while DIALux EVO 9.1 was used for the simulations. For symmetrical, opposite, and staggered lighting arrangements, average luminance measurements were performed with a digital camera positioned outside of the traffic area, with the equipment placed at the edge of the carriageway, giving similar results with standard measurements, with almost no difference. For single sided lighting arrangements, the differences became unacceptable. In this case, the paper proposes a correction function to calculate the average luminance for the observer placed on the carriageway, based on measurements with a digital camera placed outside the traffic area.