scholarly journals Fundamental Limits on Detection of UAVs by Existing Terrestrial RF Networks

2021 ◽  
Author(s):  
Priyanka Sinha ◽  
Ismail Guvenc ◽  
Mustafa Cenk Gursoy
Keyword(s):  
Beam Width ◽  
Analytical Framework ◽  
Line Of Sight ◽  
Fundamental Limits ◽  
3D Network ◽  
Optimal Beam ◽  
Sensor Density ◽  
Half Power ◽  
The Impact ◽  
Spatial Randomness

Detection of drones carries critical importance for safely and effectively managing unmanned aerial system traffic in the future. Given the ubiquitous presence of the drones across all kinds of environments in the near future, wide area drone detection and surveillance capability are highly desirable, which require careful planning and design of drone sensing networks. In this paper, we seek to meet this need by using the existing terrestrial radio frequency (RF) networks for passive sensing of drones. To this end we develop an analytical framework that provides the fundamental limits on the network-wide drone detection probability. In particular, we characterize the joint impact of the salient features of the terrestrial RF networks, such as the spatial randomness of the node locations, the directional 3D antenna patterns, and the mixed line of sight/non line of sight (LoS/NLoS) propagation characteristics of the air-to-ground (A2G) channels. Since the strength of the drone signal and the aggregate interference in a sensing network are fundamentally limited by the 3D network geometry and the inherent spatial randomness, we use tools from stochastic geometry to derive the closed-form expressions for the probabilities of detection, false alarm and coverage. This, in turn, demonstrates the impact of the sensor density, beam tilt angle, half power beam width (HPBW) and different degrees of LoS dominance, on the projected detec?tion performance. Our analysis reveals optimal beam tilt angles, and sensor density that maximize the network-wide detection of the drones.

scholarly journals Fundamental Limits on Detection of UAVs by Existing Terrestrial RF Networks

2021 ◽  
Author(s):  
Priyanka Sinha ◽  
Ismail Guvenc ◽  
Mustafa Cenk Gursoy
Keyword(s):  
Beam Width ◽  
Analytical Framework ◽  
Line Of Sight ◽  
Fundamental Limits ◽  
3D Network ◽  
Optimal Beam ◽  
Sensor Density ◽  
Half Power ◽  
The Impact ◽  
Spatial Randomness

Detection of drones carries critical importance for safely and effectively managing unmanned aerial system traffic in the future. Given the ubiquitous presence of the drones across all kinds of environments in the near future, wide area drone detection and surveillance capability are highly desirable, which require careful planning and design of drone sensing networks. In this paper, we seek to meet this need by using the existing terrestrial radio frequency (RF) networks for passive sensing of drones. To this end we develop an analytical framework that provides the fundamental limits on the network-wide drone detection probability. In particular, we characterize the joint impact of the salient features of the terrestrial RF networks, such as the spatial randomness of the node locations, the directional 3D antenna patterns, and the mixed line of sight/non line of sight (LoS/NLoS) propagation characteristics of the air-to-ground (A2G) channels. Since the strength of the drone signal and the aggregate interference in a sensing network are fundamentally limited by the 3D network geometry and the inherent spatial randomness, we use tools from stochastic geometry to derive the closed-form expressions for the probabilities of detection, false alarm and coverage. This, in turn, demonstrates the impact of the sensor density, beam tilt angle, half power beam width (HPBW) and different degrees of LoS dominance, on the projected detec?tion performance. Our analysis reveals optimal beam tilt angles, and sensor density that maximize the network-wide detection of the drones.

scholarly journals Droplet impact onto a spring-supported plate: analysis and simulations

2021 ◽  
Vol 128 (1) ◽  
Author(s):  
Michael J. Negus ◽  
Matthew R. Moore ◽  
James M. Oliver ◽  
Radu Cimpeanu
Keyword(s):  
High Speed ◽  
Flexible Substrate ◽  
Practical Importance ◽  
Hybrid Approach ◽  
Hydrodynamic Pressure ◽  
Analytical Framework ◽  
Canonical System ◽  
Linear Process ◽  
Plate Motion ◽  
The Impact

AbstractThe high-speed impact of a droplet onto a flexible substrate is a highly non-linear process of practical importance, which poses formidable modelling challenges in the context of fluid–structure interaction. We present two approaches aimed at investigating the canonical system of a droplet impacting onto a rigid plate supported by a spring and a dashpot: matched asymptotic expansions and direct numerical simulation (DNS). In the former, we derive a generalisation of inviscid Wagner theory to approximate the flow behaviour during the early stages of the impact. In the latter, we perform detailed DNS designed to validate the analytical framework, as well as provide insight into later times beyond the reach of the proposed analytical model. Drawing from both methods, we observe the strong influence that the mass of the plate, resistance of the dashpot, and stiffness of the spring have on the motion of the solid, which undergo forced damped oscillations. Furthermore, we examine how the plate motion affects the dynamics of the droplet, predominantly through altering its internal hydrodynamic pressure distribution. We build on the interplay between these techniques, demonstrating that a hybrid approach leads to improved model and computational development, as well as result interpretation, across multiple length and time scales.

scholarly journals Out of sight, out of mind? The impact of correlated clustering in substructure lensing

2021 ◽  
Author(s):  
Alexandres Lazar ◽  
James S Bullock ◽  
Michael Boylan-Kolchin ◽  
Robert Feldmann ◽  
Onur Çatmabacak ◽  
...  
Keyword(s):  
Dark Matter ◽  
Principal Axis ◽  
Major Axis ◽  
Line Of Sight ◽  
Gravitational Lenses ◽  
Local Clustering ◽  
Analytic Expression ◽  
Halo Masses ◽  
The Impact

Abstract A promising route for revealing the existence of dark matter structures on mass scales smaller than the faintest galaxies is through their effect on strong gravitational lenses. We examine the role of local, lens-proximate clustering in boosting the lensing probability relative to contributions from substructure and unclustered line-of-sight (LOS) haloes. Using two cosmological simulations that can resolve halo masses of Mhalo ≃ 109 M⊙ (in a simulation box of length Lbox ∼ 100 Mpc) and 107 M⊙ (Lbox ∼ 20 Mpc), we demonstrate that clustering in the vicinity of the lens host produces a clear enhancement relative to an assumption of unclustered haloes that persists to >20 Rvir. This enhancement exceeds estimates that use a two-halo term to account for clustering, particularly within 2 − 5 Rvir. We provide an analytic expression for this excess, clustered contribution. We find that local clustering boosts the expected count of 109 M⊙ perturbing haloes by ${\sim }35{{\ \rm per\ cent}}$ compared to substructure alone, a result that will significantly enhance expected signals for low-redshift (zl ≃ 0.2) lenses, where substructure contributes substantially compared to LOS haloes. We also find that the orientation of the lens with respect to the line of sight (e.g. whether the line of sight passes through the major axis of the lens) can also have a significant effect on the lensing signal, boosting counts by an additional $\sim 50{{\ \rm per\ cent}}$ compared to a random orientations. This could be important if discovered lenses are biased to be oriented along their principal axis.

scholarly journals A New 21-cm Line Survey of the LMC

1984 ◽  
Vol 108 ◽  
pp. 395-396
Author(s):  
K. Rohlfs ◽  
J. Kreitschmann ◽  
J. V. Feitzinger
Keyword(s):  
Noise Temperature ◽  
Beam Width ◽  
Main Beam ◽  
Corrugated Waveguide ◽  
Line Survey ◽  
Single Polarization ◽  
Switching Mode ◽  
Half Power ◽  
Channel Separation ◽  
Made In

The measurements were made in Feb. 1982 with the Parkes 64 m telescope using a corrugated waveguide horn with total half-power beam width of 15′, the first sidelobes being 19 dB down, resulting in an aperture efficiency ηA=0.53±0.007, a main beam efficiency of ηmb=0.80±0.005 and a ratio of source flux to antenna temperature of Γ=0.62±0.1 K/Jy (Murray, priv. comm.). A cooled two channel FET frontend used in the frequency switching mode with Δν = 2 MHz resulted in a system noise temperature at zenith of Tsyst = 40 K for one channel and Tsyst = 50 K for the other. Each frontend channel received a single polarization mode, and this radiation was then further analysed in a 2 × 512 channel autocorrelation spectrometer set at a channel separation of 3.906 KHz corresponding to a velocity resolution of V = 0.824 km s−1. Hanning smoothed this resulted in a σT = 0.05 K for the average of both polarization.

scholarly journals The impact of line-of-sight structures on measuring H0 with strong lensing time delays

2021 ◽  
Vol 504 (2) ◽  
pp. 2224-2234
Author(s):  
Nan Li ◽  
Christoph Becker ◽  
Simon Dye
Keyword(s):  
Time Delays ◽  
Line Of Sight ◽  
Lens Model ◽  
Local Universe ◽  
Significant Discrepancy ◽  
Turn On ◽  
Strong Lensing ◽  
Systematic Effects ◽  
The Impact ◽  
Realistic Line

ABSTRACT Measurements of the Hubble–Lemaitre constant from early- and local-Universe observations show a significant discrepancy. In an attempt to understand the origin of this mismatch, independent techniques to measure H0 are required. One such technique, strong lensing time delays, is set to become a leading contender amongst the myriad methods due to forthcoming large strong lens samples. It is therefore critical to understand the systematic effects inherent in this method. In this paper, we quantify the influence of additional structures along the line of sight by adopting realistic light-cones derived from the cosmoDC2 semi-analytical extragalactic catalogue. Using multiple-lens plane ray tracing to create a set of simulated strong lensing systems, we have investigated the impact of line-of-sight structures on time-delay measurements and in turn, on the inferred value of H0. We have also tested the reliability of existing procedures for correcting for line-of-sight effects. We find that if the integrated contribution of the line-of-sight structures is close to a uniform mass sheet, the bias in H0 can be adequately corrected by including a constant external convergence κext in the lens model. However, for realistic line-of-sight structures comprising many galaxies at different redshifts, this simple correction overestimates the bias by an amount that depends linearly on the median external convergence. We therefore conclude that lens modelling must incorporate multiple-lens planes to account for line-of-sight structures for accurate and precise inference of H0.

Influence of Renminbi Internationalization on China’s Monetary Policy Effects: A Theoretical Analysis

2021 ◽  
Vol 13 (8) ◽  
pp. 14
Author(s):  
Huiguan Ding ◽  
Asli Ogunc ◽  
Dale Funderburk ◽  
Shiyou Li ◽  
Zhebie Shi
Keyword(s):  
Monetary Policy ◽  
Open Economy ◽  
Analytical Framework ◽  
Securities Markets ◽  
Republic Of China ◽  
Policy Effects ◽  
The People ◽  
The World ◽  
The Impact ◽  
Rmb Internationalization

For more than a decade, the People’s Republic of China has sought to expand the degree of internationalization of its official currency. In recent decades, China has become the world’s second largest economy, as well as the world’s largest trading nation, and its securities markets are among the largest in the world. Today, the RMB is among the top five as a world payments currency. One of the significant costs of achieving higher degrees of internationalization of a country’s currency is the complicating impact it has on the efficacy and effect of that country’s domestic monetary policy.  However, what is the nature and extent of that complicating impact? This paper employs an IS-LM model of an open economy as an analytical framework, embeds an RMB internationalization factor into that model. Specifically, with this model we examine the impact of RMB internationalization on the effects of China’s monetary policy. 

Human capital accumulation, income distribution, and economic growth: a demand-led analytical framework

2021 ◽  
Vol 9 (3) ◽  
pp. 319-336
Author(s):  
Gilberto Tadeu Lima ◽  
Laura Carvalho ◽  
Gustavo Pereira Serra
Keyword(s):  
Human Capital ◽  
Capital Accumulation ◽  
Analytical Framework ◽  
Output Growth ◽  
Human Capital Accumulation ◽  
Capital Utilization ◽  
Tax Rate ◽  
Long Run ◽  
The Impact ◽  
Long Run Equilibrium

This paper incorporates human capital accumulation through provision of universal public education by a balanced-budget government to a demand-driven analytical framework of functional distribution and growth of income. Human capital accumulation positively impacts on workers’ productivity in production and their bargaining power in wage negotiations. In the long-run equilibrium, a rise in the tax rate (which also denotes the share of output spent in human capital formation) lowers the pre- and after-tax wage share and physical capital utilization, and thus raises (lowers) the output growth rate when the latter is profit-led (wage-led). The impact of a higher tax rate on the employment rate (which also measures human capital utilization) in the long-run equilibrium is negative (ambiguous) when output growth is wage-led (profit-led). In any case, the supply of higher-skilled workers does not automatically create its own demand.

scholarly journals In Search of Alignment: A Review of Impact Studies in Entrepreneurship Education

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Uladzimir Kamovich ◽  
Lene Foss
Keyword(s):  
Empirical Studies ◽  
Entrepreneurship Education ◽  
Analytical Framework ◽  
Future Research ◽  
Impact Studies ◽  
Teaching Objectives ◽  
Teaching Content ◽  
Instructional Processes ◽  
Scant Attention ◽  
The Impact

This study uses the concept of alignment as a framework to examine empirical research on the impact of entrepreneurship education interventions on students. Alignment assumes that effective instruction requires congruence between three instructional components: intended outcomes, instructional processes, and assessment criteria. Given the extant diversity and complexity of entrepreneurship education impact, scholars have not been able to explain how teaching approaches and methods are being adjusted to the variety of expected outcomes. In order to address this gap, we critically reviewed the published empirical studies on entrepreneurship education impact in 20 journals over a 15-year period (2000–2015). We found 16 empirical studies that met our inclusion criteria. Our findings revealed that teaching objectives, teaching methods, and teaching content receive scant attention from researchers. This study will be of value to scholars researching the impact of heterogeneous entrepreneurship education practices and approaches on individuals. Our analytical framework could contribute to less contradictory findings of entrepreneurship education impact studies. We also identify research limitations and suggest avenues for future research.

scholarly journals Impact of accelerometer based in physical layer wireless networks

2018 ◽  
Vol 7 (2.5) ◽  
pp. 15
Author(s):  
Zuhanis Mansor ◽  
Muhammad Khairulanwar bin Zulkafli
Keyword(s):  
Wireless Communication ◽  
Landscape Position ◽  
Line Of Sight ◽  
Noise Power ◽  
Signal Power ◽  
Propagation Channel ◽  
Signal To Noise ◽  
Downlink Throughput ◽  
The Impact ◽  
Non Line Of Sight

The initial deployments of antenna in the handset consist of fixed non-rotated antenna for transmitting and receiving the signal in the wireless communication scenario. However, link correlation at the UE shows very bad performance when the handset rotates in landscape position. This paper evaluates the impact of accelerometer on the downlink propagation channel of 3G smartphone for non-line-of-sight links. The performance average received signal power is studied for user equipment. Results show that the exploitation of an accelerometer provide better performance in terms of received signal power when the handset rotated from portrait to landscape position. It can be concluded that the deployment of accelerometer can be used to improve existing 3G smartphone received signal. Results also indicate that accelerometer can be used to improve downlink throughput since the signal-to-noise-power is increased by approximately 16%.

scholarly journals DISTORSI KAPASITAS PERDAGANGAN INTER-REGIONAL IMT-GT Kasus Provinsi Terpilih di Sumatera Indonesia

2015 ◽  
Vol 11 (1) ◽  
pp. 44
Author(s):  
Benito Rio Avianto ◽  
Raldi Hendro Koestoer
Keyword(s):  
Analytical Framework ◽  
Economic Cooperation ◽  
Fixed Effect ◽  
Data Series ◽  
Regional Study ◽  
Regional Economic ◽  
Trade Sector ◽  
The Impact ◽  
Effect Method

The objective of the paper was to understand the impact of sub regional economic cooperation, known as the Indonesia-Malaysia-Thailand Growth Triangle (IMT-GT), on trade sector in Indonesia. The approach of research based on export macro information by provinces and commodities. The method used in the analytical framework was a fixed effect method. The regional study covered Nanggroe Aceh Darussalam, North Sumatera, West Sumatera, and Riau provinces, and the commodities involved CPO, coffee and rubber, with 1990-2008 data series. Based on pooled regression, there was a significant impact on export from the four provinces to Malaysia and Thailand for all based years. One might focus on commodity level that, in fact, CPO was the only one commodity that had a significant impact within the IMTGT region. In addition, Thai Bath and Malaysian Ringgit, with respect to GDP for both countries, had significant influenced on export, especially after the IMT-GT endorsed.

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