Computational studies to determine the design of prototype heater for a hypersonic wind tunnel

During the modernization of the TsAGI hypersonic wind tunnel, which implies an increase in the limiting values of the flow stagnation parameters, and in the thermal load, consequently, computational studies were realized for the existing design of the electric arc heater and new geometry options for the central electrode and the cooling duct of the external electrode and nozzle. The distribution of the heat flux density to the surfaces of the main elements of the wind tunnel was obtained based on the calculations for the air duct of wind tunnel. The qualitative data of the flow formation both in the pre-heater and the pre-chamber served as the basis for changing the geometry of the central electrode. In this study, a numerical modelling approach was implemented for a through calculation of the flow and heat transfer in all areas of the wind tunnel circuit (heater, pre-chamber, nozzle, test section, diffuser). The ANSYS FLUENT software package was used to solve the axisymmetric Navier-Stokes equations for a five-component chemically reacting gas mixture: O2; N2; O; N; NO using the Spalart-Allmaras turbulence model. To study the hydrodynamics and thermal state of the structure of the external and central electrodes, the possibility of the ANSYS FLUENT complex for solving conjugate problems was used (the complete Navier-Stokes equations and the energy balance equation were solved in a fluid, and the heat conduction equation was solved in a solid). In this case, at the interface between the media, the conditions for the continuity of temperature and heat flux were satisfied.

Early ERP Evidence for Children’s and Adult’s Sensitivity to Scalar Implicatures Triggered by Existential Quantifiers (Some)

How quickly do children and adults interpret scalar lexical items in speech processing? The current study examined interpretation of the scalar terms some vs. all in contexts where either the stronger (some = not all) or the weaker interpretation was permissible (some allows all). Children and adults showed increased negative deflections in brain activity following the word some in some-infelicitous versus some-felicitous contexts. This effect was found as early as 100 ms across central electrode sites (in children), and 300–500 ms across left frontal, fronto-central, and centro-parietal electrode sites (in children and adults). These results strongly suggest that young children (aged between 3 and 4 years) as well as adults quickly have access to the contextually appropriate interpretation of scalar terms.

Electrical Properties of Reversed-Polarity Ball Plasmoid Discharges

Ball plasmoid discharges are a unique type of atmospheric-pressure plasma discharge with a lifetime on the order of a hundred milliseconds without attachment to a power source. These discharges are generated by a moderate current pulse over the surface of an aqueous electrolyte, and some consider the spherical plasmoid that results to bear some resemblance to ball lightning. This article presents the first analysis of the electrical properties of ball plasmoid discharges in a reversed-polarity configuration, i.e., with the central electrode serving as the anode rather than as the cathode. These experiments demonstrate that ball plasmoids can indeed be generated with either electrode polarity with similar observable properties. These results are contrary to what has previously been discussed in the literature and raise additional questions regarding formation mechanisms of ball plasmoids. Analysis of images and electrical measurements collected at various discharge energies show that two distinct processes occur during discharges with our circuitry and in this reversed-polarity configuration: the formation of spark channels between the anode and electrolyte, and the generation of streamers and a jet from the surface of the anode.

Investigation of central electrode artefacts of ionisation chamber effect on dose calculation using advanced calculation algorithms AAA and Acuros XB

Aim: To investigate the central electrode artefact effect of different ion chambers in the verification phantom using the dose calculation algorithms Analytical Anisotropic Algorithm (AAA) and Acuros XB. Materials and methods: The dosimetric study was conducted using an in-house fabricated polymethyl methacrylate head phantom. The treatment planning system (TPS)-calculated doses in the phantom with detectors were compared against the dummy detector fillets using AAA and Acuros XB algorithm. The planned and measured doses were compared for the study. Results: The mean percentage variation in volumetric-modulated arc therapy plans using Acuros XB and the measurement in the head phantom are statistically significant (p-value = 0.001) for FC65 and CC13 chambers. In small volume chambers (A14SL and CC01), the measured and TPS-calculated dose shows a good agreement. Findings: The study confirmed the CT set of the phantom with detectors (FC65 and CC13) give more artefacts/heterogeneity caused a significant variation in dose calculation using Acuros XB. Therefore, the study suggests a method of using phantom CT set with the dummy detector for mean dose calculation for the Acuros XB algorithm.

Исследование коаксиального ускорителя плазменной струи

Results of main energy parameters of plasma jet investigation of coaxial accelerator with a conical insert in the region of discharge formation are presented. The dependences of the pressure and diameter of the deuterium plasma jet on the distance to the accelerator as well as its length and voltage polarity on the electrodes are obtained. The square growth of plasma jet energy with increasing voltage is shown. Among all the tested modifications the most effective was an accelerator with length not exceeding 220 mm, negative voltage polarity at the central electrode and focusing conical insert at the beginning of the outer electrode. Deuterium plasma with ionization front velocity of more than 100 km/s and pressure of more than 1 MPa at the source output was obtained. Method for measuring jet pressure using a deflecting screen and FLIR SC7300M infrared camera is presented.

Sensorimotor system engagement during ASL sign perception: an EEG study in deaf signers and hearing non-signers

ABSTRACTWhen a person observes someone else performing an action, the observer’s sensorimotor cortex activates as if the observer is the one performing the action, a phenomenon known as action simulation. While this process has been well-established for basic (e.g. grasping) and complex (e.g. dancing) actions, it remains unknown if the framework of action simulation is applicable to visual languages such as American Sign Language (ASL). We conducted an EEG experiment with deaf signers and hearing non-signers to compare overall sensorimotor EEG between groups, and to test whether sensorimotor systems are differentially sensitive to signs that are produced with one hand (“1H”) or two hands (“2H”). We predicted greater alpha and beta event-related desynchronization (previously correlated with action simulation) during the perception of 2H ASL signs compared to 1H ASL signs, due to greater demands on sensorimotor processing systems required for producing two-handed actions. We recorded EEG from both groups as they observed videos of ASL signs, half 1H and half 2H. Event-related spectral perturbations (ERSPs) in the alpha and beta ranges were computed for the two conditions at central electrode sites overlying the sensorimotor cortex. Sensorimotor EEG responses in both Hearing and Deaf groups were sensitive to the observed gross motor characteristics of the observed signs. We show for the first time that despite hearing non-signers showing overall more sensorimotor cortex involvement during sign observation, mirroring-related processes are in fact involved when deaf signers observe signs.

Development of Thin Shear Force Sensor Aimed at Improving QOL for Persons with Disabilities

We have been developing a sheet type shear force sensor. It has a unique structure consisting of two flexible electrode films, a rubber ring, and a liquid electrolyte. One of the electrode films has a central electrode and the other film had four symmetrically arranged electrodes. The diameter of the sensor head was 10 mm and the thickness was about 0.7 mm. We also developed mobile measurement circuit and software for the computer. This system can handle up to four sensors simultaneously. Furthermore, we obtained experimental data by attaching the sensor to a human body using a double‐sided adhering tape.

Photocurrent modelling and experimental confirmation for meteoric smoke particle detectors on board atmospheric sounding rockets

Characterising the photoelectron current induced by the Sun's UV radiation is crucial to ensure accurate daylight measurements from particle detectors. This article lays out the methodology used to address this problem in the case of the meteoric smoke particle detectors (MSPDs), developed by the Leibniz Institute of Atmospheric Physics in Kühlungsborn (IAP) and flown on board the PMWEs (Polar Mesosphere Winter Echoes) sounding rockets in April 2018. The methodology focuses on two complementary aspects: modelling and experimental measurements. A detailed model of the MSPD photocurrent was created based on the expected solar UV flux, the atmospheric UV absorption as a function of height by molecular oxygen and ozone, the photoelectric yield of the material coating the MSPD as a function of wavelength, the index of refraction of these materials as a function of wavelength and the angle of incidence of the illumination onto the MSPD. Due to its complex structure, composed of a central electrode shielded by two concentric grids, extensive ray-tracing calculations were conducted to obtain the incidence angles of the illumination on the central electrode, and this was done for various orientations of the MSPD in respect to the Sun. Results of the modelled photocurrent at different heights and for different materials, as well as for different orientations of the detector, are presented. As a pre-flight confirmation, the model was used to reproduce the experimental measurements conducted by Robertson et al. (2014) and agrees within an order of magnitude. An experimental setup for the calibration of the MSPD photocurrent is also presented. The photocurrent induced by the Lyman-alpha line from a deuterium lamp was recorded inside a vacuum chamber using a narrowband filter, while a UV-sensitive photodiode was used to monitor the UV flux. These measurements were compared with the model prediction, and also matched within an order of magnitude. Although precisely modelling the photocurrent is a challenging task, this article quantitatively improved the understanding of the photocurrent on the MSPD and discusses possible strategies to untangle the meteoric smoke particles (MSPs) current from the photocurrent recorded in-flight.