scholarly journals Propagation Measurements at 2.4 GHz Inside a University Building and Estimation of Saleh- Valenzuela Parameters

2007 ◽  
Vol 3 (2) ◽  
pp. 99 ◽  
Author(s):  
Zoran Blažević ◽  
Igor Zanchi ◽  
Ivan Marinović
Keyword(s):  
Indoor Environment ◽  
Spatial Information ◽  
Delay Spread ◽  
Original Form ◽  
Density Functions ◽  
Network Analyzer ◽  
Channel Parameters ◽  
The One ◽  
Propagation Scenario ◽  
Good Agreement

In this paper we analyze measurements conducted in an indoor environment of our university building at a centralfrequency of 2.4 GHz in terms of the Saleh-Valenzuela channel. The channel parameters are extrapolated by processing the power-delay profiles measured by a vector network analyzer. Final adjustments of the parameters are obtained by comparison of simulated and measured delay-spread cumulative density functions, where a quite good agreement between the two is obtained. The predictions of the coherence bandwidth are satisfactory as well. We also considered some extensions to the original form of the model and concluded that the one that would be worthy to apply is the one that, besides temporal, incorporates also spatial information about the channel, whereas other modifications are found to be unnecessary or even unjustified for evaluation of this indoor propagation scenario.

scholarly journals Statistical Analysis of Radio Propagation Channel in Ruins Environment

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Jiao He ◽  
Er-Ping Li ◽  
Sai-Qiong Zhou ◽  
Kun Liao
Keyword(s):  
Radio Channel ◽  
Channel Modeling ◽  
High Density ◽  
Delay Spread ◽  
Comparison Analysis ◽  
Channel Characteristics ◽  
Channel Parameters ◽  
Good Agreement ◽  
Channel Simulator

The cellphone based localization system for search and rescue in complex high density ruins has attracted a great interest in recent years, where the radio channel characteristics are critical for design and development of such a system. This paper presents a spatial smoothing estimation via rotational invariance technique (SS-ESPRIT) for radio channel characterization of high density ruins. The radio propagations at three typical mobile communication bands (0.9, 1.8, and 2 GHz) are investigated in two different scenarios. Channel parameters, such as arrival time, delays, and complex amplitudes, are statistically analyzed. Furthermore, a channel simulator is built based on these statistics. By comparison analysis of average excess delay and delay spread, the validation results show a good agreement between the measurements and channel modeling results.

scholarly journals Two Alternative Methods to Measure the Radiated Emission in a Reverberation Chamber

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Qian Xu ◽  
Yi Huang ◽  
Sheng Yuan ◽  
Lei Xing ◽  
Zhihao Tian
Keyword(s):  
Conventional Method ◽  
Signal Generator ◽  
Power Measurement ◽  
Alternative Methods ◽  
Network Analyzer ◽  
Reverberation Chamber ◽  
Enhanced Backscattering ◽  
Radiated Power ◽  
The One ◽  
Good Agreement

One of the most important applications of a reverberation chamber is for radiated power measurement. Two new alternative methods are proposed to measure the radiated power of equipment under test in a reverberation chamber in this paper. Traditionally, as stated in IEC 61000-4-21 standard, this measurement requires two antennas, a signal generator and a spectrum analyzer or receiver. However, it is found that if a signal generator is not available, a vector network analyzer can be used to complete the measurement. Furthermore, if only one antenna is available, by taking advantage of the enhanced backscattering effect, the measurement can still be completed. By incorporating the one- and/or two-antenna methods, the radiation efficiency of antennas is also considered. Measurements have been conducted to verify the proposed methods, the results from these three methods are compared, and a very good agreement is obtained. It is found that the two proposed methods are simpler than the conventional method.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

scholarly journals Estimation of the Noise Source Level of a Commercial Ship Using On-Board Pressure Sensors

2021 ◽  
Vol 11 (3) ◽  
pp. 1243
Author(s):  
Hongseok Jeong ◽  
Jeung-Hoon Lee ◽  
Yong-Hyun Kim ◽  
Hanshin Seol
Keyword(s):  
Noise Source ◽  
Pressure Sensors ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Source Strength ◽  
Recording Time ◽  
Source Level ◽  
The One ◽  
Hydrophone Array ◽  
Good Agreement

The dominant underwater noise source of a ship is known to be propeller cavitation. Recently, attempts have been made to quantify the source strength using on-board pressure sensors near the propeller, as this has advantages over conventional noise measurement. In this study, a beamforming method was used to estimate the source strength of a cavitating propeller. The method was validated against a model-scale measurement in a cavitation tunnel, which showed good agreement between the measured and estimated source levels. The method was also applied to a full-scale measurement, in which the source level was measured using an external hydrophone array. The estimated source level using the hull pressure sensors showed good agreement with the measured one above 400 Hz, which shows potential for noise monitoring using on-board sensors. A parametric study was carried out to check the practicality of the method. From the results, it was shown that a sufficient recording time is required to obtain a consistent level at high frequencies. Changing the frequency resolution had little effect on the result, as long as enough data were provided for the one-third octave band conversion. The number of sensors affected the mid- to low-frequency data.

scholarly journals Post-liquefaction reconsolidation of sand

2016 ◽  
Vol 472 (2186) ◽  
pp. 20150745 ◽  
Author(s):  
O. Adamidis ◽  
G. S. P. Madabhushi
Keyword(s):  
Void Ratio ◽  
One Dimensional ◽  
Geotechnical Centrifuge ◽  
Significant Damage ◽  
Pore Water Pressures ◽  
The One ◽  
Crucial Parameter ◽  
Excess Pore ◽  
Good Agreement ◽  
Made In

Loosely packed sand that is saturated with water can liquefy during an earthquake, potentially causing significant damage. Once the shaking is over, the excess pore water pressures that developed during the earthquake gradually dissipate, while the surface of the soil settles, in a process called post-liquefaction reconsolidation. When examining reconsolidation, the soil is typically divided in liquefied and solidified parts, which are modelled separately. The aim of this paper is to show that this fragmentation is not necessary. By assuming that the hydraulic conductivity and the one-dimensional stiffness of liquefied sand have real, positive values, the equation of consolidation can be numerically solved throughout a reconsolidating layer. Predictions made in this manner show good agreement with geotechnical centrifuge experiments. It is shown that the variation of one-dimensional stiffness with effective stress and void ratio is the most crucial parameter in accurately capturing reconsolidation.

Bimodal and multimodal descriptions of soil-water characteristic curves for structural soils

2013 ◽  
Vol 67 (8) ◽  
pp. 1740-1747 ◽  
Author(s):  
Shiyu Liu ◽  
Noriyuki Yasufuku ◽  
Qiang Liu ◽  
Kiyoshi Omine ◽  
Hazarika Hemanta
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Soil Water ◽  
Lognormal Distribution ◽  
Probability Density Functions ◽  
Density Functions ◽  
Characteristic Curves ◽  
Physically Based ◽  
Soil Water Characteristic Curves ◽  
Good Agreement

In the last decades several approaches have been developed to describe bimodal or multimodal soil-water characteristic curves (SWCCs). Unfortunately, most of these models were derived empirically. In the presented study, physically based bimodal and multimodal SWCC functions have been developed for structural soils. The model involved two or more continual pore series; the probability density functions for each pore series were assumed to be lognormal distribution and can be superposed to obtain the overall probability density function of the structural soils. The proposed functions were capable of simulating bimodal or multimodal SWCCs using parameters which can be related to physical properties of the structural soils. The experimental SWCC data were used to verify the proposed method. The fitting results showed that the proposed approaches resulted in good agreement between measurement and simulation. These functions can potentially be used as effective tools for indentifying hydraulic porosities in the structural mediums.

scholarly journals A General Expression for the Stagnant Thermal Conductivity of Stochastic and Periodic Structures

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
X. Bai ◽  
C. Hasan ◽  
M. Mobedi ◽  
A. Nakayama
Keyword(s):  
Thermal Conductivity ◽  
General Expression ◽  
Metal Foam ◽  
Solid Angle ◽  
Periodic Structures ◽  
Three Dimensional ◽  
High Thermal Conductivity ◽  
Numerical Calculations ◽  
The One ◽  
Good Agreement

A general expression has been obtained to estimate thermal conductivities of both stochastic and periodic structures with high-solid thermal conductivity. An air layer partially occupied by slanted circular rods of high-thermal conductivity was considered to derive the general expression. The thermal conductivity based on this general expression was compared against that obtained from detailed three-dimensional numerical calculations. A good agreement between two sets of results substantiates the validity of the general expression for evaluating the stagnant thermal conductivity of the periodic structures. Subsequently, this expression was averaged over a hemispherical solid angle to estimate the stagnant thermal conductivity for stochastic structures such as a metal foam. The resulting expression was found identical to the one obtained by Hsu et al., Krishnan et al., and Yang and Nakayama. Thus, the general expression can be used for both stochastic and periodic structures.

Pion structure in a modified quark loop model

1980 ◽  
Vol 58 (7) ◽  
pp. 964-968 ◽  
Author(s):  
J. H. Kim ◽  
L. Resnick
Keyword(s):  
Form Factor ◽  
Bound State ◽  
Weak Decay ◽  
Loop Model ◽  
Vector Structure ◽  
Pion Structure ◽  
The One ◽  
System Coupling ◽  
State Nature ◽  
Good Agreement

The pion is assumed as usual to couple to the electroweak currents through its constituent quarks. The bound state nature of the [Formula: see text] system coupling to the electroweak currents is simulated by a form factor at the [Formula: see text] vertex, parametrized by an effective mass M and coupling strength f. Calculations are performed at the one loop level, with a prescription used to ensure electromagnetic gauge invariance. Isospin invariance is assumed. f, M, and the effective quark mass m are determined by the normalization condition for the pion electromagnetic form factor and the charged and neutral pion lifetimes. The charge radius of the pion is calculated and found to be in good agreement with experiment. The ratio of the axial to vector structure functions in the radiative weak decay π → evγ is also determined.

scholarly journals Novel MNZ-type microwave sensor for testing magnetodielectric materials

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abhishek Kumar Jha ◽  
Nicolò Delmonte ◽  
Adam Lamecki ◽  
Michal Mrozowski ◽  
Maurizio Bozzi
Keyword(s):  
Magnetic Properties ◽  
Relative Permittivity ◽  
Microstrip Line ◽  
Dielectric Materials ◽  
Metal Strip ◽  
Network Analyzer ◽  
Microwave Frequencies ◽  
Microwave Sensor ◽  
Iron Garnet ◽  
Good Agreement

Abstract A novel microwave sensor with the mu-near-zero (MNZ) property is proposed for testing magnetodielectric material at 4.5 GHz. The sensor has a double-layer design consisting of a microstrip line and a metal strip with vias on layers 1 and 2, respectively. The proposed sensor can detect a unit change in relative permittivity and relative permeability with a difference in the operating frequency of 45 MHz and 78 MHz, respectively. The MNZ sensor is fabricated and assembled on two layers of Taconic RF-35 substrate, with thicknesses of 0.51 mm and 1.52 mm, respectively, for the measurement of the sample under test using a vector network analyzer. The dielectric and magnetic properties of two standard dielectric materials (Taconic CER-10 and Rogers TMM13i) and of yttrium–gadolinium iron garnet are measured at microwave frequencies. The results are found to be in good agreement with the values available in the literature, which shows the applicability of the prototype for sensing of magnetodielectric materials.

A new algorithm for numerical modelling of impurity transport in the frame of statistically homogeneous sharply contrasting media

2019 ◽  
Vol 34 (6) ◽  
pp. 339-351 ◽  
Author(s):  
Petr S. Kondratenko ◽  
Leonid V. Matveev ◽  
Alexander D. Vasiliev
Keyword(s):  
Numerical Modelling ◽  
Contaminant Transport ◽  
Integral Kernel ◽  
Time Intervals ◽  
One Dimensional ◽  
Time Representation ◽  
Impurity Transport ◽  
The One ◽  
Analytical Expressions ◽  
Good Agreement

Abstract A new method is developed to calculate characteristics of contaminant transport (including non-classical regimes) in statistically homogeneous sharply contrasting media. A transport integro-differential equation in the space-time representation is formulated on the basis of the model earlier proposed by one of the authors (L. M.). Analytical expressions for transport characteristics in limiting time intervals in the one-dimensional case are derived. An interpolation form is proposed for the integral kernel of the transport equation. On a basis of this expression, an algorithm is developed for numerical modelling the contaminant transport in statistically homogeneous sharply contrasting media. Trial numerical 1D calculations are performed based on this algorithm. Good agreement was found between the numerical simulation results and the asymptotic analytical expressions.

Sign in / Sign up

Export Citation Format

Share Document