scholarly journals Experimental Characterization and Correlation Analysis of Indoor Channels at 15 GHz

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Zhou ◽  
Zhangdui Zhong ◽  
Bei Zhang ◽  
Ruisi He ◽  
Ke Guan ◽  
...  
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Delay Spread ◽  
Experimental Characterization ◽  
Wireless System ◽  
Normal Distributions ◽  
Indoor Radio ◽  
Log Normal ◽  
Wireless System Design ◽  
Correlation Properties

The indoor radio channels at 15 GHz are investigated based on measurements. The large- and small-scale fading behaviors as well as the delay dispersion characteristics are discussed. It is found that the large-scale fading, RiceanK-factor, and delay spread can be described by log-normal distributions. Furthermore, both autocorrelation and cross correlation properties of the above parameters are analyzed and modeled. These parameters characterize fading and delay behaviors as well as their mutual dependency and can be used as empirical values for future wireless system design and simulation in 15 GHz short-range indoor channels.

Grain Growth Simulation Based on Potts Model with Different Parameters

2005 ◽  
Vol 475-479 ◽  
pp. 3173-3176 ◽  
Author(s):  
Xiangge Qin ◽  
Guo Quan Liu
Keyword(s):  
Steady State ◽  
Grain Growth ◽  
Potts Model ◽  
Large Scale ◽  
Square Lattice ◽  
Small Scale ◽  
Weibull Function ◽  
Simulation Based ◽  
Log Normal ◽  
Large Scale Simulations

Potts model was often used to simulate grain growth without necessary evaluation of the effect of lattice scale and simulation temperature. It is found in this paper that such parameters may affect the simulation results markedly. The results show that simulations at zero temperature or on a small scale lattice (say, the number of sites on one edge of the square lattice L=1000) cannot reach the steady-state period of grain growth, while large-scale simulations (say, L=2000) at a much higher simulation temperature can. The steady-state grain size distribution so obtained may be well described by Weibull function other than log-normal or Rayleigh functions.

scholarly journals Wall-Normal Variation of Spanwise Streak Spacing in Turbulent Boundary Layer With Low-to-Moderate Reynolds Number

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 24 ◽  
Author(s):  
Wenkang Wang ◽  
Chong Pan ◽  
Jinjun Wang
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Buffer Layer ◽  
Large Scale ◽  
Normal Growth ◽  
Small Scale ◽  
Piv Measurement ◽  
Moderate Reynolds Number ◽  
Scale Structures ◽  
Log Normal

Low-speed streaks in wall-bounded turbulence are the dominant structures in the near-wall turbulent self-sustaining cycle. Existing studies have well characterized their spanwise spacing in the buffer layer and below. Recent studies suggested the existence of these small-scale structures in the higher layer where large-scale structures usually receive more attention. The present study is thus devoted to extending the understanding of the streak spacing to the log layer. An analysis is taken on two-dimensional (2D) wall-parallel velocity fields in a smooth-wall turbulent boundary layer with Ret = 4402400, obtained via either 2D Particle Image Velocimetry (PIV) measurement taken here or public Direct Numerical Simulation (DNS). Morphological-based streak identification analysis yields a Re-independent log-normal distribution of the streak spacing till the upper bound of the log layer, based on which an empirical model is proposed to account for its wall-normal growth. The small-scale part of the spanwise spectra of the streamwise fluctuating velocity below y? = 100 is reasonably restored by a synthetic simulation that distributes elementary streak units based on the proposed empirical streak spacing model, which highlights the physical significance of streaks in shaping the small-scale part of the velocity spectra beyond the buffer layer.

scholarly journals Unmanned Aerial Vehicle Propagation Channel over Vegetation and Lake Areas: First- and Second-Order Statistical Analysis

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 65
Author(s):  
Deyvid L. Leite ◽  
Pablo Javier Alsina ◽  
Millena M. de Medeiros Campos ◽  
Vicente A. de Sousa ◽  
Alvaro A. M. de Medeiros
Keyword(s):  
Secure Communication ◽  
Large Scale ◽  
Communication Channel ◽  
Channel Model ◽  
Path Loss ◽  
Doppler Frequency ◽  
Unmanned Aircraft ◽  
Small Scale ◽  
Log Normal

The use of unmanned aerial vehicles (UAV) to provide services such as the Internet, goods delivery, and air taxis has become a reality in recent years. The use of these aircraft requires a secure communication between the control station and the UAV, which demands the characterization of the communication channel. This paper aims to present a measurement setup using an unmanned aircraft to acquire data for the characterization of the radio frequency channel in a propagation environment with particular vegetation (Caatinga) and a lake. This paper presents the following contributions: identification of the communication channel model that best describes the characteristics of communication; characterization of the effects of large-scale fading, such as path loss and log-normal shadowing; characterization of small-scale fading (multipath and Doppler); and estimation of the aircraft speed from the identified Doppler frequency.

scholarly journals On the scale sizes of magnetosheath jets

2020 ◽  
Author(s):  
Ferdinand Plaschke ◽  
Heli Hietala
Keyword(s):  
Large Scale ◽  
Dynamic Pressure ◽  
Large Population ◽  
Small Scale ◽  
Size Distributions ◽  
Exponential Functions ◽  
Scale Size ◽  
Order Of Magnitude ◽  
Log Normal ◽  
Spacecraft Data

<p>The subsolar magnetosheath is oftentimes permeated by jets. These are localized entities of enhanced dynamic pressure with respect to the ambient plasma. Magnetosheath jets are thought to arise from bow shock ripples and/or foreshock structures. They can easily propagate through the entire magnetosheath and impact on the magnetopause, where they can cause large amplitude indentations, launch magnetopause surface waves, or modulate magnetopause reconnection. The scale size distributions of magnetosheath jets observed by single spacecraft are relatively well modeled by exponential functions with characteristic scales of 0.71 Earth radii (RE) and 1.34 RE in the directions parallel and perpendicular to the jet propagation direction, respectively. However, these functions do not represent the actual, true jet scale size distributions, because of two reasons: (1) Spacecraft are much more likely to observe large scale jets rather than small scale jets. Hence, the observed scale size distributions are biased towards larger scales. (2) The distributions modeled by exponential functions highly overestimate observation probabilities of jets of smallest scales (on the order of 0.1 RE). We overcome both shortcomings by replacing the exponential functions by log-normal functions, which can be corrected for the bias. By re-analyzing THEMIS multi-spacecraft data, we obtain, for the first time, unbiased, i.e., actual jet scale size distributions. Our results reveal a large population of jets of smallest scales that have not been accounted for, so far. Consequently, we find median scale sizes of jets to be about an order of magnitude smaller than previously thought: 0.15 and 0.12 RE in the parallel and perpendicular directions, respectively.</p>

scholarly journals Millimeter-Wave Channel Measurement at 73GHz and 81GHz

2021 ◽  
Author(s):  
Changyu Guo
Keyword(s):  
Large Scale ◽  
High Capacity ◽  
Path Loss ◽  
Directional Antennas ◽  
Line Of Sight ◽  
Small Scale ◽  
Wave Channel ◽  
Narrowband Signal ◽  
Loss Models ◽  
Log Normal

The abundant spectrum available at mmWave band can provide high capacity, high throughput, and low latency. In this thesis, we present experimental measurements for 73 and 81 GHz mmWave bands. Wideband propagation measurements were performed at the Boise Airport concourse C area and tarmac for both line-of-sight (LOS) and non-line-of sight (NLOS) scenarios. Power delay profiles were recorded and analyzed with close-in free space reference path loss models and floating intercept path loss models. In addition, building material attenuation at 28, 73, and 91 GHz is presented. Measurements at 73 GHz for wideband and narrowband signal are performed with directional antennas. Moreover, wideband spatial fading measurements were performed at the Boise State University Micron Engineering Building and Boise Airport. The power delay profiles are recorded and analyzed with Rayleigh, Ricean, and log-normal models. Large scale path loss parameters at the airport, material attenuation and small scale fading parameters were computed. The results can help researchers and network designers in simulation and design of mmWave wireless networks.

scholarly journals Tripolarizated MIMO: Experimental Analysis and Modeling of Channel Properties in Both Indoor and Outdoor Scenarios

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Pan Tang ◽  
Jianhua Zhang ◽  
Zuolong Ying ◽  
Yuxiang Zhang ◽  
Lei Tian ◽  
...  
Keyword(s):  
Communication Systems ◽  
Large Scale ◽  
Mimo Systems ◽  
Mimo System ◽  
High Capacity ◽  
Small Scale ◽  
Delay Spread ◽  
Channel Measurements ◽  
Channel Properties ◽  
Indoor And Outdoor

The tripolarized MIMO system can provide one more degree of freedom and have a more compacted size over a dual-polarized MIMO system, which is attractive for high-capacity wireless communication systems. In this paper, we analyze and model channel properties for tripolarized MIMO systems based on experimental channel measurements in typical indoor and outdoor scenarios. Firstly, channel measurement campaigns in the laboratory and the Urban Micro (UMi) scenarios on sub-6 GHz bands are presented. Then, based on measured data, path loss, delay spread (DS), and cross-polarization discrimination (XPD) for 9 polarization combinations are analyzed and modeled in a statistical way. Statistical results of these channel properties are also given. It is observed that channel properties of both large-scale fading and small-scale fading depend strongly on the polarization direction. Furthermore, we evaluate the performance of tripolarized MIMO systems by analyzing the Demmel condition number and channel capacity gain (CG). For both the indoor and the outdoor scenarios, it is found that colocated tripolarized antenna can bring a nearly threefold CG with respect to the unipolarized one. These results can give good insights into the design and evaluation of tripolarized MIMO systems.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

Planetary gentrification and urban (re)development

2019 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Loretta Lees
Keyword(s):  
Low Income ◽  
Policy Making ◽  
Large Scale ◽  
Urban Redevelopment ◽  
Urban Transformation ◽  
Small Scale ◽  
Income Groups ◽  
Low Income Groups

Abstract Gentrification is no-longer, if it ever was, a small scale process of urban transformation. Gentrification globally is more often practised as large scale urban redevelopment. It is state-led or state-induced. The results are clear – the displacement and disenfranchisement of low income groups in favour of wealthier in-movers. So, why has gentrification come to dominate policy making worldwide and what can be done about it?

AGRICULTURAL PRODUCTION OF CA DONG PEOPLE IN RESETTLEMENT AREA OF TRANH RIVER HYDROPOWER NUMBER 2: CURRENT SITUATION AND IMPACT FACTORS

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Bùi Thị Bích Lan
Keyword(s):  
Social Relations ◽  
Agricultural Production ◽  
Large Scale ◽  
Transition Process ◽  
Impact Factors ◽  
Small Scale ◽  
Scale Production ◽  
Technical Application ◽  
Production Models ◽  
Role Of The State

In Vietnam, the construction of hydropower projects has contributed significantly in the cause of industrialization and modernization of the country. The place where hydropower projects are built is mostly inhabited by ethnic minorities - communities that rely primarily on land, a very important source of livelihood security. In the context of the lack of common productive land in resettlement areas, the orientation for agricultural production is to promote indigenous knowledge combined with increasing scientific and technical application; shifting from small-scale production practices to large-scale commodity production. However, the research results of this article show that many obstacles in the transition process are being posed such as limitations on natural resources, traditional production thinking or the suitability and effectiveness of scientific - technical application models. When agricultural production does not ensure food security, a number of implications for people’s lives are increasingly evident, such as poverty, preserving cultural identity, social relations and resource protection. Since then, it has set the role of the State in researching and building appropriate agricultural production models to exploit local strengths and ensure sustainability.

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