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Object detection is an important issue in many fields, including robotics, self-driving cars, and surveillance. This paper describes object detection methods based on Radio Tomographic Imaging (RTI). These technologies include Frequency Modulated Continuous Wave (FMCW) and Wi-Fi with computer vision algorithms. Wi-Fi systems focus primarily on measuring the Received Signal Strength Index (RSSI), and FMCW radar systems measure parameters such as pulse frequency, time delay, and Doppler shift to extract information about targets, including their range, speed, and sometimes their direction. These technologies are becoming increasingly important because of their ability to correctly identify and describe objects using signals that computer vision can interpret, making them competitive with technologies that rely on optical and thermal vision. The methods presented in this paper are suitable for object detection tasks because they combine the advantages of radio and computer vision. The methods mentioned in processing these techniques were based on previous research in the literature for each technique. In the end, this study adds useful information in the field of computer vision and radio signals, allowing researchers to make this study a reference that extracts many methods and ideas so that future researchers can choose the most appropriate technology for their research. [ABSTRACT FROM AUTHOR]

This paper explores the effects of Doppler shifts in high-mobility communication devices. What's more, it investigates the challenges faced in High-Speed Railways (HSR) communication systems because of deviation of the carrier frequency, which is called Doppler shift, at increasing the relative speed of the relative motion between Transmitter (Tx) and Receiver (Rx). The work here discusses the latest methodologies that achieve optimal or suboptimal solutions, such as channel modeling and new radio technologies. To provide seamless connectivity communication and minimize, regardless of the hard mismatch due to the Doppler, the Doppler Spread Compensator (DSC) technology is promoted to mitigate the Doppler effect. Finally, the paper proposes an innovative and effective approach, including the use of Reconfigurable Intelligent Surfaces (RIS), to improve wireless communication performance and reduce the impact of the Doppler shift. [ABSTRACT FROM AUTHOR]

A qualified assessment can determine the quality of learning. One type of the assessment that educators or teachers can use is diagnostic test. The focus of this study is to develop a diagnostic test instrument which can be used to identify high school students' conceptual understanding of physics subjects related to the Doppler effect and sound intensity level. This is a type of research and development (R&D) with a 4D model (define, design, develop, disseminate). The subjects of this research were high school students in class XI MIPA in Public Senior High School 3 Solok who had received lessons on sound waves. The data collection technique used is an ordinary multiple choice test instrument. Analysis of quantitative and qualitative by using IRT (Item Response Theory) was applied to the test results. According to the content validity using Aiken's V equation, this instrument was declared to be valid with very good criteria. In line to the Rasch model and the value of INFIT MNSQ and INFIT t, all items in the test instrument were valid. The diagnostic test instrument is also trustful, because the value of reliability of estimate achieves 0.90. Thus, it can be used to identify and analyze the students' conceptual understanding profile. The instrument has thus satisfied the test criteria that are feasible in terms of content, validity, reliability, and empirical evidence. In addition, the results of this conceptual understanding profile are expected to be one of the information for teachers in order to overcome students' difficulties and arrange appropriate learning strategies during the learning process. [ABSTRACT FROM AUTHOR]

This paper discusses the improvement of heat transfer rate and flow characteristics of fluid in the Solar Parabolic Trough Collector (PTC) receiver tube for different geometrical consideration. Numerical analysis using Computational Fluid Dynamics (CFD) was performed receiver tubes with circular, square, and elliptical geometrical shapes, with and without twisted tape insert. for receiver tubes with circular, square, and elliptical geometrical shapes, either with or without twisted tape inserts. The results of CFD numerical analysis were validated with the experimental results. The comparison graphs for friction factor, Nusselt number as well as thermal performance are plotted with respect to Reynolds number. Results shows that, the change in the geometrical shape of the receiver tube and tube with insets affects the internal and external convection heat transfer coefficients and rate of heat transfer. It was suggested that to use twisted tape inserts in the receiver tube for better heat transfer rate in Solar PTC. [ABSTRACT FROM AUTHOR]

The Maximum Likelihood (ML) estimation of carrier frequency offset (CFO) for multiple-input multiple-output (MIMO) systems using orthogonal frequency division multiplexing (OFDM) across Rayleigh fading channels is discussed in this study. CFOs are sensitive to OFDM, which is caused through oscillator frequency imbalances and/or Doppler shifts. CFO presents Inter-Carrier Interference (ICI), which is a type of interference that causes subcarriers to disturb their orthogonality. Maximum likelihood (ML) estimation of carrier-frequency offsets for uplink transmission of orthogonal frequency-division multiple access is a complicated issue to estimate using several parameters. The ML technique is based on the global optima search issue, which is impractical in practice due to the need for a multidimensional extensive search of the huge number of users. Simulation results indicate the performance of the ML estimation technique of CFO estimation in OFDM and OFDM-MIMO uplink systems in terms of accuracy and complexity. [ABSTRACT FROM AUTHOR]

The parabolic trough collector (PTC) is one of the promising technologies that have been prevailing the solar power landscape in the recent decades. More and more countries worldwide are embracing this technology and promoting research that is aiming at increasing its efficiency. Among the various components of a parabolic trough collector, the absorber tube, also referred to as the parabolic trough receiver (PTR), is of utmost importance and its proper functioning is key to the reliability of the whole system. The objective of this study is to numerically investigate the incorporation of wall-attached internal fins in a parabolic trough receiver in order to enhance its heat transfer efficiency. A variety of fin geometries that are right triangle, obtuse triangle and acute triangle were evaluated and compared with the smooth parabolic trough receiver. In addition to the different fin shapes, simulations were conducted for tubes with one, two, three and four fins, at three Reynolds numbers associated with turbulent flow, namely 8000, 10000 and 12000. The parameters which were chosen to be indicative of the thermal performance improvement in the internally finned absorber tubes are the Nusselt number, the friction factor, and the thermal performance factor. The modeling and simulation of the different scenarios were carried out on ANSYS Fluent software. The obtained results have demonstrated that the suggested geometric modifications at the level of the absorber tube successfully created turbulence in the flow and led to the improvement of the thermal performance factor by a maximum value of 1.134 and a minimum value of 1.045 as compared to the plain tube. [ABSTRACT FROM AUTHOR]

There are many possible ways to experimentally test the Doppler effect. Last year's epidemic forced us to transform the laboratory practices for online conditions at university level physics education. We performed a similar experiment as Buys Ballot's and recorded it for student's online laboratory work: we placed a loud, single-frequency sound source on a moving car and recorded the sound near the road while the car was passing with constant speed. The source was a smartphone connected to a loudspeaker. The digital recording was then analyzed by students in the frame of online laboratory work using the "phyphox" application on their smartphones (but any other frequency analyzer app could have been used). A sample calculus for the speed of the car and the estimation of the errors of measurements is also presented. The scientific processing of a dataset is almost as useful for students as it would be for a laboratory experiment conducted in attendance education. The advantage here is that they could deal with a phenomenon which previously was not included among the laboratory themes, although it is interesting and has a large variety of applications. Highlighting the importance of the Doppler effect and the good practices in other countries, we recommend to include this topic in the Romanian high school physics curriculum as well. [ABSTRACT FROM AUTHOR]

Hypertension, smoking, age, and Diabetes are all factors that lead to Atherosclerosis in blood flow during disease can be observed by calculating Doppler through the strength of the scattered using ultrasound techniques on dorsalis pedis in the foot. The goal of this study is to use the correlation coefficient of average blood flow velocity and Doppler scattering to investigate factors that influence Atherosclerosis. A study of the effect on blood flow by Doppler shift was achieved in Ibn Al-Nafees Hospital for Heart Patients and, taking samples from patients with Atherosclerosis aged between 35-90 years and taking ultrasound examinations. This study used a blood flow rate for 50 healthy. Distinguish for 42 patients by Doppler ultrasound techniques at the foot and statistical satisfy for the effect of age and Diabetes according to Matlab program. Results showed that the Pearson r correlation coefficient between the average blood flow velocity and Doppler shift is (0.94) to healthy and value at (0.99) for patients. This paper has shown a strong linear correlation. The aging factor affects blood flow for atherosclerosis patients, with the increase in age causing a decrease in the average blood flow in the capillary arteries. [ABSTRACT FROM AUTHOR]

The study of the Doppler effect was quite difficult to demonstrate quantitatively. The aim of this study is to design a simple experiment using smartphone to visualize the Doppler effect using a pendulum oscillation experiment. The smartphone with tone generator applications as a pendulum were oscillated while the other smartphone with frequency analyser was placed in equilibrium point to record frequency change. The experimental shows that the frequency detected was increasing when the pendulum moves closer to the equilibrium point and decreasing when the pendulum moves away from the equilibrium point. The experiment can thus be used to assist high school students and physics undergraduates in understanding the Doppler effect with a simple and low-cost experiment. [ABSTRACT FROM AUTHOR]

The aim of the proposed work is to improve the energy efficiency of sensor nodes in underwater acoustic sensor networks using Modified Data Localization Correction Approach(MDLCA) in comparison with Data Localization Correction Approach(DLCA). Selection of optimal node in data routing path based on localization approach along with doppler effect in underater is considered for data collection. A total of 40 samples are collected and 20 samples for each group is taken to train the data sets. The proposed algorithm is tested in an underwater virtual environment by Aquasim in NS2 simulator. The end-to-end delay, throughput, energy efficiency and packet delivery ratio are calculated to evaluate the performance of the proposed MDLCA algorithm.: For dynamically changing topological condition the proposed MDLCA algorithms reduces the energy consumption level of each node(11%) and delay(7%). Statistical analysis shows that significant value (P<0.05) The simulation results shows that reducing the time of optimal node selection leads to improve the energy efficiency of the sensor network using the proposed MDLCA algorithm in comparison with DLCA. [ABSTRACT FROM AUTHOR]

The 4G and 5G wireless communication systems provide very high date rates and operate in high mobility regions with large number of users. The channel conditions in these wireless communications are doubly dispersive which includes time and frequency dispersion. OFDM techniques are commonly used in 4G/5G communications which provides better performance in frequency selective channels and OFDM systems offer less Inter symbol interference. But Doppler shift introduces the shift in the subcarrier frequencies causing deviation in their orthogonality, which degrades system performance. In high-speed vehicle communication a new generation modulation scheme which represents the signal in two-dimensional form known as OTFS is proposed where the modulation symbol is multiplexed in the delay Doppler representation. In this paper, OTFS Massive MIMO system is analyzed based on Impulse, Orthogonal Matching Pursuit (OMP) and channel estimation by structured orthogonal matching pursuit (SOMP) techniques for high-speed communication. [ABSTRACT FROM AUTHOR]

Reduction of tire/road noise has become an important issue for EVs since powertrain noise has largely been eliminated. A tire's air-cavity mode is known to be a significant contributor to increased forces at the wheel hub, which can result in significant interior noise levels near 200 Hz. Moreover, the single natural frequency of a static, undeformed tire can separate into two neighboring frequencies for a rolling, deformed tire due to the combination of the tire's asymmetry, and the Doppler effect resulting from the tire's rotation. In this study, the evolution of the Doppler-related frequency split with increasing speed was observed in Tire Pavement Test Apparatus (TPTA) tests by measuring the dynamic force at the hub under rotation and load. Similar results were obtained using FE simulations. Through the FE simulation, it has been shown that there can be force amplification at the hub when the split frequencies couple with adjacent treadband structural modes near 200 Hz. In addition, material modifications were applied to the base model in the simulations to find values that would reduce force levels at the split frequencies. Finally, it is suggested that a target speed needs to be determined when evaluating a tire since the two split, natural frequencies are strongly influenced by rotation speed. [ABSTRACT FROM AUTHOR]

Long-term exposure to aircraft noise causes significant health issues among residents near airports. Therefore, noise impact assessments and noise control at the source are important aspects of the design of new aircraft. The design process of low-noise aircraft can be supported with auralisation of virtual flyovers. In order to render plausible aircraft auralisations, multiple propagation phenomena have to be considered, such as geometrical spreading, air absorption, Doppler effect, and reflections from the ground. Additionally, measurements of aircraft flyover show clear patterns of amplitude and phase fluctuations by atmospheric turbulence. Aircraft flyover auralisations should incorporate these clearly audible features of sound propagation in real-world conditions to be perceived as plausible. We present new approaches of time-variant filtering techniques to account for phase and amplitude fluctuations as a function of atmospherical conditions characterised by the von Kármán turbulence spectrum of wind and temperature fluctuations. Compared to earlier approaches, the proposed model is closer to the physical mechanisms. The application of the filters leads to a reduction of unnatural flanging and to a higher naturalness of level fluctuations. As the proposed method has shown to increase plausibility of aircraft flyover auralisation, its application in perception-based evaluation of future aircraft concepts is foreseen. [ABSTRACT FROM AUTHOR]

Reduction of tire-road noise is an important issue when developing luxury cars and electric vehicles. In this context, the air-cavity mode is an important source of spindle forces transmitted to the suspension that then increase interior noise levels. When a tire rotates, the cavity mode near 200 Hz splits into two adjacent modes due to a Doppler effect and tire deformation. That split can lead to increased levels of both longitudinal and vertical spindle forces at the spindle since the two acoustic modes each contribute to both forces when the tire rotates. Thus, it is important to develop tools to identify the contributions of the split air-cavity modes to the spindle force. A FE simulation of the spindle force for a steady-state rolling tire has been verified by a comparison with laboratory test results obtained by using a wheel-force transducer mounted on Purdue's Tire Pavement Test Apparatus. It was observed that the frequency split expands as the rotation speed increases and that the vertical spindle force increases when aligned with an odd-numbered circumferential structural mode. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) rely on optical sensors such as cameras and lidar for autonomous operation. However, such optical sensors are error-prone in bad lighting, inclement weather conditions including fog and smoke, and around textureless or transparent surfaces. In this paper, we ask: is it possible to fly UAVs without relying on optical sensors, i.e., can UAVs fly without seeing? We present BatMobility, a lightweight mmWave radar-only perception system for UAVs that eliminates the need for optical sensors. BatMobility enables two core functionalities for UAVs - radio flow estimation (a novel FMCW radar-based alternative for optical flow based on surface-parallel doppler shift) and radar-based collision avoidance. We build BatMobility using commodity sensors and deploy it as a real-time system on a small off-the-shelf quadcopter running an unmodified flight controller. Our evaluation1 shows that BatMobility achieves comparable or better performance than commercial-grade optical sensors across a wide range of scenarios. [ABSTRACT FROM AUTHOR]

Laser diagnostics techniques are widely used in experimental fluid mechanics. By far the most widely used systems for getting spatial velocity fields and turbulence data are laser Doppler anemometers (LDA). Further, in the cases of two-phase flows phase Doppler analysers (PDA) are typically chosen to measure the size and velocity of the droplets or bubbles. The PDA system is non-intrusive laser technique with high spatial and temporal resolution. Moreover, the PDA system does not require additional calibration as, for example, hot-wire anemometers. However, with a growing number of PDA users, there is a need for verification of the results among the workplaces and systems themselves. The current paper deals with the comparison of two fibre-based PDA systems. The main scope of the investigation is an evaluation of the system's age and the influence of lasers type. One of the systems is older, operated with Argon-Ion laser and the second one is brand new equipped with Diode-pumped solid-state lasers. Both have the same optics and were manufactured by the same company. Various properties of the PDA system are tested to show particular influence on the quality of results when measuring in a spray generated by a small air-blast atomizer. [ABSTRACT FROM AUTHOR]

The localization of WSNs is done at the depths in the ocean for sensing oceanic conditions such as pressure etc. This network is deployed under the water for transmitting the essential information over diverse regions in smooth manner. Hence, the process to transmit the information is maintained. It is challenging to transmit the information rapidly in underwater acoustic medium as various complexities are occurred in it namely limited bandwidth and the Doppler shift etc. Under the sea water, the broadcast of electromagnetic waves is quite poor. Earlier, the transmission technologies were constructed for terrestrial wired and wireless mediums. Thus, the applicability of these techniques is enhanced for submerged mediums by completing their modifications. The preceding research work has implemented the FA in order to localize the nodes. This algorithm also includes the quantification of appropriate value to localize the nodes. This research projects a Distance based mechanism to localize the node. MATLAB is applied to deploy the projected mechanism and earlier algorithms. The simulation results revealed that the projected mechanism has performed well in comparison with existing techniques concerning diverse parameters. [ABSTRACT FROM AUTHOR]

A Monte Carlo simulation of Phase Doppler systems has been developed. It consists of three sections, the droplet flow description, generation of the photomultiplier signals and then their processing to determine droplet velocities and the time shift between the signals from the three scattered light detection apertures. With highly realistic Doppler bursts being simulated and processed, the question arises as to whether the signal processing software could be used to process 'real-world' experimental signals. In a preliminary assessment of its capabilities in such a situation, actual spray Doppler signals (from a Dantec fibre-based PDA system with a BSA signal processor) were recorded and used as input to the software signal processor. The signals from the three photomultipliers were input first into a Picoscope and then into the BSA processor. In this way droplet velocities and size estimates would be available from the BSA as control data. The signal outputs were taken as csv files, and input directly into the software signal processor. Initially the software determined the time location of the centre of each signal burst envelop. This approach was shown to measure signal delays from single cycle to multiple cycles. For this experiment, the software was modified by adding a zero-crossing approach to measure the single cycle delays. The introduction of this method should establish the accuracy of the complete software package in the real world as the results from the preliminary experiment show good agreement between the two techniques. [ABSTRACT FROM AUTHOR]

The problem of pre-flight calculation of the orbital parameters of the first nanosatellite of the Belarusian State University CubeBel-1 before launching from the Jiuquan Satellite Launch Center in China has been solved. The first nanosatellite passes over the Belarusian State University ground station were predicted based on the perturbed circular motion model. The initial TLE file was generated and published on the Internet. This allowed dozens of radio amateurs from 5 continents successfully to receive the nanosatellite telemetry on the first day after the launch on October 29, 2018 at 00:43:13.576 UTC, and the Belarusian State University ground station was the first to decode the CubeBel-1 telemetry. The obtained initial parameters were compared with the calculations in the SGP 4 model. It is shown that the absolute errors in predicting the elevation and azimuth of nanosatellite CubeBel-1 did not exceed 2o and 3o, respectively, and the absolute error in predicting the Doppler frequency shift of telemetry signals did not exceed 350 Hz, which, with appropriate receiver settings, is sufficient for successful reception of telemetry signals of satellite and their decoding. [ABSTRACT FROM AUTHOR]

Accurate sonar performance modelling is essential to predict likely detection ranges that can be obtained by employing active anti-submarine warfare sonars. Reverberation forms an important source of interference for active sonar performance, the effects of which can be diminished by using Doppler-sensitive pulses. Therefore, it is of importance that the sonar performance model takes into account the effects of Doppler-sensitive pulses in reverberation-limited scenarios. In this paper, we present the approach used in the ARCANE sonar performance model, which allows us to model the additional complexity brought by reverberation and Doppler-sensitive pulses. The resulting predictions for a towed sonar transmitting a continuous wave pulse are shown and compared with measurements presented in literature. The favourable comparison indicates the complexity of reverberation modelling for a moving sonar is well captured. [ABSTRACT FROM AUTHOR]

The difference of the stripping loss between hydrogen and deuterium is examined using two approaches. The first is the measurement of the optical beam emission. The wavelength of beam emission spectrum reflects the energy distribution of beam particles by the Doppler effect. The low-energy stripping peak is observed in the energy band corresponding to the extraction voltage, and also a moderate shoulder is distributed in the lower energy region. Secondly, the spatial and the energy distribution in the accelerator is estimated by the attenuation calculation using the vacuum pressure distribution in the accelerator. Stripping neutrals are concentrated in the low energy region, and a peak is formed at 9 keV in the energy distribution due to stripping neutrals inside the extraction grid aperture. The total stripping loss inside the accelerator is 16% for hydrogen and 24% for deuterium. The calculated Doppler-shifted spectra for hydrogen and deuterium clearly show the peak with the moderate shoulder on the redshift side, which is consistent with the measured results. [ABSTRACT FROM AUTHOR]

For the next generation of fast reactors, global objectives are required in terms of safety, sustainability, waste minimization and non-proliferation issues. Concerning safety issues, particular efforts have been made in order to obtain core designs that can be resilient to accidental transients. In that frame, the CEA held R&D program toward a GEN-IV-like core concept that could meet those requirements: the ASTRID project. Based on heterogeneous core geometry (axial inner fertile layer, large upper sodium plenum) the ASTRID core shows improved behavior in case of unprotected loss of flow. It has been found that Doppler Effect plays a dominant role for the considered transients to deal with in the safety demonstration. The prediction of the Doppler Effect by neutronic simulation codes require experimental validation, the reason for which static tests conducted within SEFOR (South-West Experimental Fast Oxide Reactor) –a fast reactor fueled with mixed PuO2-UO2 and cooled with sodium –are being used. The SEFOR experimental tests are being analyzed with the ERANOS code package using nuclear data libraries of different evaluations: JEFF-3.1.1, JEFF-3.2, ENDF-B/VII.1 and JENDL4. The C/E values on the SEFOR Doppler Effect range from 1.01 to 1.07 with an experimental uncertainty of ±0.06. With the use of perturbation break down in energy and isotope, this paper identifies the reasons for such large C/E spread and identifies the differences and similarities of the SEFOR Doppler Effect with the ASTRID one. [ABSTRACT FROM AUTHOR]

Calculation of normal heights and differences from known geopotential numbers and differences in geodetic practice is required when performing independent calculations: for control of levelling network adjustment made with different type heights – normal and geopotential; when using optical clocks technology for geopotential difference determinations; when performing precise engineering and geodetic works. It is well known that between two height types - normal heights and geopotential numbers exists theoretical equivalence when the same gravimetric and levelling data are used. In practice, this equivalence depends on the realized accuracy of the calculations. This requires the appropriate, substantiated calculation formulas. Transformation accuracy is connected to the degree of detail in description of the relationship between the two quantities. The accuracy of normal difference, determined by known geopotential difference is studied. The contribution of each individual term forming its mean square error is analyzed. The study is made under different conditions: heights, height differences, distances, orientation of levelling connection, and different errors in the height of the benchmarks. In the article briefly is presented the principle of geopotential difference determination, based on the gravitational Doppler effect. It occurs during the operation of two remote optical clocks, according to the General Theory of Relativity. The theoretical dependence between normal height differences and the frequency shifts of the optical clocks is also presented. In the article is discussed the transformation between the two equivalent quantity types, providing the necessary practical accuracy for the purposes of precise height determinations. [ABSTRACT FROM AUTHOR]

Cavitation tunnels are hydrodynamic facilities used mainly to observe cavitation and to analyze the performances of maritime devices like propellers or foils. These experimental approaches, consisting in a model scale measurements extrapolated to full scale with similitude laws, is nowadays the preferred method to predict the underwater noise radiated by a vessel at sea. The characterization of the different acoustic sources (localization and strength mainly) is one of the key point to better understand the whole mechanism that generates the total underwater noise. The particular case of a rotating source imposes a Doppler effect that disturbs the frequency content of the signal measured by a fixed hydrophone. The communication presents the results obtained by simulation of the measured signal generated by a rotating source. A warping time function is defined with geometrical parameters and used to perform a dedopplerization of the measured signal. The influence of each of those parameters is presented focusing on the performance of the expected dedopplerization. Consequently, different strategies are proposed to define an adapted criterion representing the accuracy of the dedopplerization effect. [ABSTRACT FROM AUTHOR]

We define the notion of mutual quantum measurements of two macroscopic objects and investigate the effect of these measurements on the velocities of the objects. We show that multiple mutual quantum measurements can lead to an effective force emerging as a consequence of asymmetric diffusion in the velocity space. We further show that, under a certain set of assumptions involving the measurements of mutual Doppler shifts, the above force can reproduce Newton's law of gravitation. For a broader class of measurements, the emergent force can also lead to corrections to Newton's gravitation. [ABSTRACT FROM AUTHOR]

This paper presents a practical and accurate Doppler estimator for signals propagating in underwater acoustic (UWA) channels. Estimation is performed with relatively short shift-orthogonal pilot sequences due to their correlation properties. Pilot bursts are OFDM (orthogonal frequency division multiplexing). The receiver performs Doppler estimation by cross-correlating the received signal with the known pilot signal, resulting in a Doppler phase estimate from which the Mach number is determined in real-time. The estimator operates at the sample rate of the signal, which yields a Mach number estimate every sample. Therefore, instantaneous changes in the Mach number are known, thereby allowing the tracking of Doppler effects in dynamic channels. A design criterion for the estimator's validity is derived, which relates bandwidth, carrier frequency and sequence length with Mach number. A MATLAB Simulink model of the estimator is presented. The results show its performance in synthetic channels that simulate relative motion between transmitter and receiver. The Cramer-Rao lower bound (CRLB) analysis shows the estimator achieving a variance below 10 -4 for SNRs above 20 dB. This is a near-optimal estimator. Additionally, compared to other estimators, the computational complexity is considerably lower and the range of valid Mach numbers that it can address is higher. [ABSTRACT FROM AUTHOR]

Airborne Doppler lidar measurements are a valuable tool in meteorological research. A new airborne Doppler lidar system has been developed jointly by the Karlsruhe Institute of Technology (KIT) and the Technical University of Brunswick. The system is designed for use aboard a medium-range turboprop aircraft, thereby targeting meso-scale flow phenomena. In order to optimize system setup and retrieval strategy, as well as evaluate measurement quality under turbulent conditions, a first LES-based airborne Doppler lidar simulator has been developed. The results provide detailed insight into airborne Doppler lidar wind profiling characteristics. [ABSTRACT FROM AUTHOR]

This study focuses on the distribution of ozone (O3) concentration near the Chesapeake Bay, USA (hereafter CB) by integrating observations and model simulations. The motivation of this work is to understand reasons causing the horizontal and vertical distribution of pollutants (mainly O3) near the CB. The O3 exceedance over the CB happens very frequently during summer and the Maryland Department of Environment intends to find out the reasons in order to make policy-related decision. The observation data used in this study are from the Ozone Water-Land Environmental Transition Study-2 (OWLETS-2) field campaign, including observations from O3 lidar, Doppler wind lidar, ozonesonde. The mesoscale model employed is Weather Research and Forecasting model coupled with chemistry (WRF-Chem) version 3.9.1. The anthropogenic emission dataset is from National Emission Inventory 2011 (NEI-2011), including various emission species, e.g., CO, NOX, SO2, NH3, PM2.5, PM10, etc. The meteorological initial and boundary conditions are from the Northern American Regional Reanalysis (NARR) dataset, which is a high-resolution combined model and assimilated dataset from the National Centers for Environmental Prediction (NCEP). There are several findings of this study based on the model simulations and ground-based observations. Actually, at the beginning of study, we considered two different versions of anthropogenic emissions from NEI-2005 and NEI-2011 developed by the Environment Protection Agency (EPA). EPA added the anthropogenic emissions over CB from boats and ships while updating from NEI-2005 to NEI-2011. For model performance evaluation, we employed AirNow surface hourly O3 mixing ratio diurnal variation and compared it with model simulations. For instance, at Essex site near Baltimore City, observed O3 has a strong diurnal variation, with minimum (25 ppbv) just after sunrise (05:00 EST), and with maximum (75 ppbv) around afternoon (15:00 EST). Even the model simulation has a good agreement with the observation, it underestimates the mean O3 mixing ratio by about 15-20 ppbv. Both the surface and 700 mb level horizontal spatial distribution of O3 indicate the higher O3 concentration over the north-middle CB, with surface O3 mixing ratio of 40-50 ppbv and 700 mb level O3 mixing ratio of 60 ppbv, which means the surface O3 was lifted up after production. The vertical profiles of wind of both model and Doppler wind lidar match very well, indicating that the model captured the vertical variation of wind. However, the vertical profiles of O3 from model simulation, ozonesonde, and O3 lidar suggests that model simulation underestimated the O3 from surface to 4.5 km. In addition, the model simulation captured the vertical mixing of O3 from surface to 2 km, while misses the O3 variation above 2 km. In order to study the influence of bay breeze on the O3 small scale transport, three vertical cross sections through the CB from west to east at the northern, middle, and southern CB. The results show that higher O3 concentration above the CB. The bay breeze over the southern CB is stronger than the northern CB. The planetary boundary layer height over the CB is dramatically lower than the surrounding land in the day, which contributes to the surface higher O3 concentration over the CB. [ABSTRACT FROM AUTHOR]

On 22nd August 2018, the European Space Agency (ESA) launched the first direct detection Doppler wind lidar into space. Operating at 355 nm and acquiring signals with a dual channel receiver, it allows wind observations in clear air and particle-laden regions of the atmosphere. Furthermore, particle optical properties can be obtained using the High Spectral Resolution Technique Lidar (HSRL) technique. Measuring with 87 km horizontal and 0.25-2 km vertical resolution between ground and up to 30 km in the stratosphere, the global coverage of Aeolus observations shall fill gaps in the global observing system and thus help improving numerical weather prediction. Within this contribution, first results from the German initiative for experimental Aeolus validation are presented and discussed. Ground-based wind and aerosol measurements from tropospheric radar wind profilers, Doppler wind lidars, radiosondes, aerosol lidars and cloud radars are utilized for that purpose. [ABSTRACT FROM AUTHOR]

KNMI has had a long involvement with the recently launched Aeolus mission. Aeolus is an ESA Earth-Explorer mission and embarks the Atmospheric Laser Doppler Instrument (ALADIN). ALADIN is the first space-borne Doppler Wind Lidar (DWL) and was successfully launched in late August 2018. KNMI has had a long association with this mission and is sharing the software development of the L2B processor used to generate L2B wind products at ECMWF, develops related scene classification algorithms and performs calibration/validation activities. In addition, KNMI conducts more fundamental work for improving the retrieval of atmosphere optical properties, taking into account multiple scattering effects. [ABSTRACT FROM AUTHOR]

The modification of bottomonia yields in Pb–Pb and p–Pb collisions at LHC energies with respect to the expectation from p–p is investigated in a theoretical approach. Dissociation of the ϒ(nS) and ϒ(nP) states in the hot quark-gluon plasma (QGP) occurs due to screening of the real quark-antiquark potential, collisional damping through the imaginary part of the potential, and gluon-induced dissociation. Reduced feed-down plays a decisive role. Transverse-momentum and centrality-dependent data are well re- produced. In the asymmetric p-Pb system, alterations of the parton density functions in the lead nucleus account for the leading fraction of the modifications in cold nuclear matter (CNM), but the hot-medium effects turn out to be relevant in spite of the small initial spatial extent of the fireball. [ABSTRACT FROM AUTHOR]

Measurement of a material's longitudinal sound velocity (CL) at pressure can yield new information on its equation of state and strength, including sensitivity to phase changes [1-4]. Results are presented on a series of gas gun driven plate impact experiments on pure lead (Pb) samples at stresses between 5 and 17 GPa. Thin tungsten heavy alloy (WHA) flyer plates were used to generate a shock and release profile, with arrival times of both the shock and initial rarefaction waves measured using frequency shifted photon Doppler velocimetry (PDV) at multiple sample thicknesses via a stepped target setup. A comparison of these experimental results to current multi-phase material models are presented, with a reduced gradient in the sound velocity with pressure observed compared to that predicted. [ABSTRACT FROM AUTHOR]

When near-instantaneous shocks are recorded by a Doppler velocity interferometer (VISAR) they typically exceed the detector's ability to react, and "skipped fringes" result where its visibility briefly reduces. Traditionally, replacing skipped fringes required guesswork in analysis, which increased arrival time errors. Secondly, the use of long but velocity-sensitive interferometer delays with fast detectors which can resolve the delay has traditionally been avoided, because of the fear of confusing the arrival time signal. But shorter delays produce smaller fringe phase shift per velocity and thus can decrease velocity precision. We realize that while some loss of fringe information occurs at shock events, this is often just a partial loss, and the residual fringe information can still hold valuable information. We describe a forward model (FM) of the interferometer action and detector blurring that assists with VISAR fringe analysis at skipping events: (1) more precise shock arrival times, (2) even with long delays, and (3) improved ghost subtraction which improves accuracy over a broad time region. We demonstrate the utility of FM on National Ignition Facility (NIF) and Laboratory for Laser Energetics (LLE) Omega shots. [ABSTRACT FROM AUTHOR]

We present theoretical conditions of the similarity between two equivalent RF systems in tokamaks, and find important deviations from the similarity relations. The exact similarity conditions are unlikely attainable in real experiments because of many practical and physical constraints. We found that three combinations of the scaling parameters (D1, D2, D3) sufficiently describe three important ICRF phenomena (optimized minority fractions, power decompositions, and effective temperatures) by capturing damping mechanisms, kinetic effects, FLR effects, and Doppler effects, unless the deviations are significant. In this proceeding, we compare the Helium-3 minority heating scenarios in Hydrogen plasmas between JET and ITER [ABSTRACT FROM AUTHOR]

Gamma-ray detection following the inelastic neutron scattering reaction on isotopically enriched material was used to study the nuclear structure of 74Ge. From these measurements, low-lying, low-spin excited states were characterized, new states and their decays were identified, level lifetimes were measured with the Doppler-shift attenuation method (DSAM), multipole mixing ratios were established, and transition probabilities were determined. New structural features in 74Ge were identified, and the reanalysis of older 76Ge data led to the placement of the 2+ member of the intruder band. In addition, a number of previously placed states in 74Ge were shown not to exist. A procedure for future work, which will lead to meaningful data for constraining calculations of the neutrinoless double-beta decay matrix element, is suggested. [ABSTRACT FROM AUTHOR]

This research conducted an experiment on EAR-RASS acoustic chirp signal to find the better configuration for virtual temperature profile data retrieval. A single frequency acoustic pulses are susceptible to Doppler shift error, the utilization of continuous wave and chirped signals become a solution. Therefore, commonly the acoustic wave source is transmitted at different frequencies in order to meet wavelength condition for obtaining Bragg condition at wide range of altitudes. Several chirp configurations for EAR-RASS have been tested by changing their sweep range and time during these experiments. The ray-tracing method is applied before each experiment and confirmed by the Doppler spectra performance to ensure that the observation is conducted in the RASS echoes region. Compared to the other configuration, the 90-110 Hz has better performance as it produces highest echo power hence better virtual temperature data retrieval. [ABSTRACT FROM AUTHOR]

Motivated from a recent theoretical work [1] on efficient storage of terahertz frequency signals in ultracold Rydberg atoms, I have studied the above mentioned storage process in the case when Doppler effect is present. It is present when the atoms are moving with a velocity which is coming from the thermal effect. Here, I have shown that this effect has made a prominent change in susceptibility and relative difference of the slope of dispersion which is the key factor of group index and group velocity [2]. [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron waves have been studied for relativistic ring distribution in the presence of parallel AC electric field by using the method of characteristic solutions and kinetic approach. The dispersion relation and the growth rate has been derived and calculated for magnetosphere of Saturn. The effect of AC frequency on the Doppler shifting frequency has been discussed. The new results have been explained for a ring distribution function rather than the bi-Maxwellian or loss cone distribution function. The effective parameters for the generation of EMIC waves are not only the temperature anisotropy but also the relativistic factor, AC field frequency, ratio of cold to warm particles number densitywhich has been discussed in result and discussion section. [ABSTRACT FROM AUTHOR]

Global Positioning System is a widely adopted localization technique. With the increasing demand for small satellites, the need for a low-power GPS for satellites is also increasing. To enable many state-of-the-art applications, the exact position of the satellites is necessary. However, building low-power GPS receivers which operate in low earth orbit pose significant challenges. This is mainly due to the high speed (~7.8 km/s) of small satellites. While dutycycling the receiver is a possible solution, the high relative Doppler shift between the GPS satellites and the small satellite contributes to the increase in Time To First Fix (TTFF), thus increasing the energy consumption. Further, if the GPS receiver is tumbling along with the small satellite on which it is mounted, longer TTFF may lead to no GPS fix due to disorientation of the receiver antenna. In this paper, we elucidate the design of a low-cost, low-power GPS receiver for small satellite applications. We also propose an energy optimization algorithm called F 3to improve the TTFF which is the main contributor to the energy consumption during cold start. With simulations and in-orbit evaluation from a launched nanosatellite with our µGPS and high-end GPS simulators, we show that up to 96.16% of energy savings (consuming only ~ 1/25 th energy compared to the state of the art) can be achieved using our algorithm without compromising much (~10 m) on the navigation accuracy. The TTFF achieved is at most 33 s. [ABSTRACT FROM AUTHOR]

Lifetime measurements with the recoil distance Doppler-shift technique have been performed to determine yrast E2 transition strengths in 178Pt. The experimental data are related to those on neighboring Pt isotopes, especially recent data on 180Pt, and compared to calculations within the interacting boson model and a Hartree-Fock Bogoliubov approach. These models predict prolate deformed ground states in Pt isotopes close to neutron midshell consistent with the experimental findings. Further, evidence was found that the prolate intruder structure observed in neutron-deficient Hg isotopes that is minimum in energy in 182Hg becomes the ground state configuration in 178Pt and neighboring 180Pt with nearly identical transition quadrupole moments. The new data on 178Pt are further discussed in the context of the systematics along the Pt isotopic chain with respect to a possible sharp shape transition towards a weakly deformed or a quasi-vibrational ground state whereas the prolate structure increases in energy in 174,176Pt and becomes an intruder configuration similar to, for example, 180,182Hg. [ABSTRACT FROM AUTHOR]

Multiple physical limitations arise with supersonic travel. Speedsters (characters with superhuman speed) in fictional works accomplish these feats with various explanations or avoidance from the authors. If the physical problems can be set aside, fundamental relationships show that listeners moving relative to a sound source at high speeds perceive a shift in frequency that depends on the speed and direction of relative travel. The acoustical content hypothetically perceived by such superheroes at supersonic speeds is investigated. Theoretical Doppler shifts would keep speech audible when traveling up to about 100,000 MPH (150 times the speed of sound). Lastly, practical applications for supersonic travel are examined. Each of these physical constraint and frequency shift ideas apply to supersonic vehicles. Speech inside such land or air vehicles remains as normal, unaffected by these issues. [ABSTRACT FROM AUTHOR]

Interpretation of the Electron Cyclotron Emission (ECE) and ECE Imaging (ECE-I) measurements concerning the measurement position and the radiation temperature (Trad) at the plasma edge is associated with significant uncertainty. Various limitations such as low and high-density limits, relativistic and Doppler shift-broadening, mode overlap were identified in the past. Here, we analyse the influence of density profile variation onto the radiation temperature in H-mode plasmas at ASDEX Upgrade tokamak. We show that, in the region of steep gradients, the variation of the density profile leads to an outward-shift of the measurement position, towards lower Trad. The analysis is extended towards the study of the contribution of the ordinary mode (O-mode) emission to the measured Trad at the plasma edge. With this analysis, we show the qualitative agreement between experimental observations and modeling when taking into account the O-mode contribution to the ECE measurements. All of these effects are assessed via the Electron Cyclotron Radiation transport forward model that is now routinely used to model the response of the ECE-I and ECE systems in different plasma scenarios. [ABSTRACT FROM AUTHOR]