Measurement-based Analysis Research Articles

An experimental analysis and deep learning model to assess the cooling performance of green walls in humid climates

Introduction: Amidst escalating global temperatures, increasing climate change, and rapid urbanization, addressing urban heat islands and improving outdoor thermal comfort is paramount for sustainable urban development. Green walls offer a promising strategy by effectively lowering ambient air temperatures in urban environments. While previous studies have explored their impact in various climates, their effectiveness in humid climates remains underexplored.Methods: This research investigates the cooling effect of a green wall during summer in a humid climate, employing two approaches: Field Measurement-Based Analysis (SC 1: FMA) and Deep Learning Model (SC 2: DLM). In SC 1: FMA, experiments utilized data loggers at varying distances from the green wall to capture real-time conditions. SC 2: DLM utilized a deep learning model to predict the green wall’s performance over time.Results: Results indicate a significant reduction in air temperature, with a 1.5°C (6%) decrease compared to real-time conditions. Long-term analysis identified specific distances (A, B, C, and D) contributing to temperature reductions ranging from 1.5°C to 2.5°C, highlighting optimal distances for green wall efficacy.Discussion: This study contributes novel insights by determining effective distances for green wall systems to mitigate ambient temperatures, addressing a critical gap in current literature. The integration of a deep learning model enhances analytical precision and forecasts future outcomes. Despite limitations related to a single case study and limited timeframe, this research offers practical benefits in urban heat island mitigation, enhancing outdoor comfort, and fostering sustainable and climate-resilient urban environments.

A six-year measurement-based analysis of traffic-related particulate matter pollution in urban areas: the case of Warsaw, Poland (2016-2021)

This study used PM10 and PM2.5 measurements from the State Environmental Monitoring stations in Warsaw and its suburban areas. Analysis of variability characteristics at the traffic and urban background stations was carried out for 2016-2021. A six-year analysis (2016-2021) of air quality in Warsaw, Poland, focusing highlights the persistent impact of transportation on particulate matter concentrations. Comparing a city centre traffic station with urban background locations reveals consistently higher PM10 concentrations at the traffic station throughout the year, with an annual traffic-related increase of 12.6 μg/m³ (32%). PM2.5 concentrations at the traffic station are also consistently about 1.5 μg/m³ (7%) higher. For monthly averages, the highest PM10 concentrations at the traffic station were noted in March, which may be related to the resuspention of sand and salt left over from winter snow removalp rocesses. In the case of PM2.5, the typical annual cycle with maximum concentrations in winter and minimum concentrations in summer was not observed. Diurnal variability patterns show elevated PM10 concentrations at the traffic station from 8:00 a.m. to 10:00 p.m., attributed to the resuspension process. PM2.5 patterns exhibit a smaller amplitude at the traffic station, with nighttime accumulation due to inflow. This study emphasizes the lasting impact of transportation on air quality, providing insights into pollution control strategies in urban areas.

The prevalence of overweight and obesity: a measurement-based analysis of 6-9-year-old school children from Montenegro.

This study aimed to conduct a measurement-based analysis of overweight and obesity prevalence among 6-9-year-old children in Montenegro. The population of this cross-sectional study included 1993 (1059 boys and 934 girls) primary-school children. The sample of anthropometric variables includes body height, body weight and body mass index, as well as nutrition status that were presented based on BMI standardized categories: underweight, normal weight, overweight, and obesity. The descriptive statistics described the means for each variable, while post hoc tests and ANOVA were applied to explore differences between the proposed means. The results indicate the overweight (including obesity) prevalence was 28% (15% of overweight and 13% of obese children), while boys have a higher overweight prevalence rate than girls. In addition, the tendency of higher prevalence rates to differ by age in both sexes is observed. This study also confirmed that overweight and obesity are affected by geographical regions but not by the level of urbanization in Montenegro. The innovation of this study is reflected in the fact that the overweight and obesity prevalence rates among 6-9-year-old children are within an acceptable range in Montenegro, since it does not deviate from the European average, but further interventions and continuous monitoring are necessary, due to the specific nature of this issue.

Measurement-Based Analysis of Millimeter-Wave Channel Sparsity

Millimeter-wave (mmWave) channel sparsity is widely exploited to reduce the complexity of compressed sensing and beamtracking algorithms for 5G, yet there are still many misconceptions about it: that it arises from pencilbeam antennas admitting just a few paths, that the channel in fact has just a few paths, and that the channel is always sparse. What is missing to confirm these conjectures is a measurement-based analysis, to our knowledge conducted by only two papers thus far, however, both at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">microwave</i> (5 GHz), in a single environment, and based on just a few ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\leq$</tex-math></inline-formula> 49) measurements. For conclusive analysis on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmWave</i> sparsity, we have collected measurements with our high-resolution 3-D double-directional 60 GHz channel sounder in three indoor and two outdoor environments, comprising a total of 750 measurements while investigating both line-of-sight (LoS) and obstructed LoS (OLoS) conditions. We learned that in LoS, the channel is always sparse that sparsity drops notably from LoS to OLoS and that mmWave sparsity is inherent to the channel itself—not to pencilbeam antennas—since our sounder has omnidirectional field-of-view. We also propose a sparsity metric that accounts for channels with just a few paths, which we found to occur in some environments.

Validation of a Holistic System for Operational Analysis and Provision of Ancillary Services in Active Distribution Networks

The advent of distributed renewable energy sources (DRESs) has led to the progressive transformation of traditional distribution networks to active components of the power system. This transformation, however, may jeopardize the reliable grid operation due to the advent of new technical problems, such as network overloading, over-/under-voltage events, abnormal frequency deviation and dynamic instability. In this challenging scenery, the installation of a modern measuring infrastructure has created new sources of data and information that facilitate the provision of ancillary services (ASs) via measurement-based analysis. The ACTIVATE (ancillary services in active distribution networks based on monitoring and control techniques) project aims to design innovative AS solutions for power system operators. These solutions aim to tackle the technical issues emerged by the ever-increasing DRES penetration and their volatile nature. In this context, in ACTIVATE, a holistic system is proposed comprising centralized and decentralized control features to enhance the overall network performance. Additionally, a network monitoring system is designed to support a number of online and offline dynamic analysis applications by exploiting measurements obtained at the transmission, primary and secondary distribution network. This paper presents a validation of the overall system, which is performed by using simulation and power-hardware-in-the-loop results in combined transmission and distribution network models.

Measurement-Based Analysis on Vehicle-to-Vehicle Connectivity in Tunnel Environment

Vehicular ad hoc network (VANET) brings an excellent solution to ensure road safety and transportation efficiency in critical environment like tunnel. Particularly, radio link connectivity of vehicle-to-vehicle (V2V) significantly influences the performance of VANETs. The communication range of the radio systems is a random variable in reality due to the channel fading effect. Therefore, the connectivity model between vehicles in realistic environment is a key for accurate evaluation of system performances. In this paper, we study the V2V connectivity performance in the presence of channel randomness for tunnel environment. Firstly, based on channel measurement campaign, empirical path loss (PL) and small-scale fading channel models are established. Secondly, we study the influence of large-scale fading parameters on V2V connectivity. Thirdly, based on real small-scale fading characteristics, we derive the V2V connectivity probability between any two vehicles under Nakagami fading channel for one-dimensional VANET, and give the closed-form of V2V connectivity probability. Finally, we study the influences of various parameters (i.e., Nakagami fading factor, vehicle density, and neighbor order) on V2V connectivity performance. Results show that with the Nakagami fading shape factor increases, the connectivity probability increases. The shadowing fading can improve connectivity in the VANET; the path loss exponent, transmission distance, and signal-to-noise ratio (SNR) threshold have a negative impact on connectivity probability. The transmit power, vehicle density, and path loss threshold value have a positive impact on connectivity.

On the High Fluctuations of Received Signal Strength Measurements With BLE Signals for Contact Tracing and Proximity Detection

This paper presents a measurement-based analysis of the Received Signal Strength (RSS) of Bluetooth Low Energy (BLE) signals, under Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios, performed in tandem at two universities in Tampere, Finland, and Bucharest, Romania. We adopted the same hardware and methodology for measurements in both places, and paid particular attention to the impact of RSS on various environmental factors, such as LOS and NLOS scenarios and interference in 2.4 GHz band. In addition, we considered the receiver orientation and the different frequencies of BLE advertising channels. We show that snapshot RSS measurements typically have high variability, not easily explainable by classical path-loss models. A snapshot recording is defined here as one continuous recording at fixed device locations in a static setup. Our observations also show that aggregated RSS data (i.e., considering several snapshot measurements together) is more informative from a statistical point of view and more in agreement with current theoretical path-loss models than snapshot measurements. However, in BLE applications such as contact tracing and proximity detection, the receivers typically have access only to snapshot measurements (e.g., taken over a short duration of 10–20 minutes or less), so the accuracy of contact-tracing and proximity detection can be highly affected by RSS instabilities. In addition to presenting the measurement-based BLE RSS analysis in a comprehensive and well-documented format, our paper also emphasizes open challenges when BLE RSS is used for contact tracing, ranging, and positioning applications.

Measurement-Based Black-Box Harmonic Stability Analysis of Commercial Single-Phase Inverters in Public Low-Voltage Networks

This paper presents a measurement-based stability analysis of commercially available single-phase inverters in public low-voltage networks. In practice, manufacturers typically do not disclose the parameters of the inverter design, although interactions with the low-voltage network need to be assessed and predicted. State-of-the-art modeling methods require knowledge about the internal parameters. The method proposed in the paper is based on measurements in the laboratory and does not require detailed knowledge about the specific inverter design for the identification of the black-box linear time-periodic representation. The gained information is used for the black-box stability analysis in the frequency range up to 2 kHz, which covers the bandwidth of the control of the inverters. The method is validated for a commercially available photovoltaic inverter in the laboratory. An instability that leads to a shutdown of the inverter is demonstrated, while the critical frequency range is predicted accurately.

Towards Cell-Free Massive MIMO: A Measurement-Based Analysis

Cell-free widely distributed massive multiple-input multiple-output (MIMO) systems utilize radio units spread out over a large geographical area. The radio signal of a user equipment (UE) is coherently detected by a subset of radio units (RUs) in the vicinity of the UE and processed jointly at the nearest baseband processing unit (BPU). This architecture promises two orders of magnitude less transmit power, spatial focusing at the UE position for high reliability, and consistent throughput over the coverage area. All these properties have been investigated so far from a theoretical point of view. To the best of our knowledge, this work presents the first empirical radio wave propagation measurements in the form of time-variant channel transfer functions for a linear, widely distributed antenna array with 32 single antenna RUs spread out over a range of 46.5m. The large aperture allows for valuable insights into the propagation characteristics of cell-free systems. Three different co-located and widely distributed RU configurations and their properties in an urban environment are analyzed in terms of time-variant delay-spread, Doppler spread, path-loss, and the correlation of the local scattering function over space. For the development of 6G cell-free massive MIMO transceiver algorithms, we analyze properties such as channel hardening, channel aging as well as the signal to interference and noise ratio (SINR). Our empirical evidence supports the promising claims for widely distributed cell-free systems.

Image quality measurement-based comparative analysis of illumination compensation methods for face image normalization

Image quality measurement-based comparative analysis of illumination compensation methods for face image normalization

Trends in Body Height, Body Weight, BMI, and Nutrition Status from 1979 to 1987: A Measurement-Based Analysis of 10,954 Male Adolescents from the Municipality of Bijelo Polje

Trends in Body Height, Body Weight, BMI, and Nutrition Status from 1979 to 1987: A Measurement-Based Analysis of 10,954 Male Adolescents from the Municipality of Bijelo Polje

Trajectories of Body Height, Body Weight, BMI, and Nutrition Status from 1979 to 1987: A Measurement-Based Analysis of 8740 Montenegrin Male Adolescents from the Municipality of Berane.

This study aimed to consolidate the body height, body weight, BMI, and nutrition status data of the overall young male population from the Municipality of Berane in order to assess the trajectories of those variables from 1979 to 1987. The sample of respondents included 8740 adolescents who were divided into nine groups according to their age. The sample of variables included body height, body weight, body mass index, and nutrition status, which were presented based on a long-established BMI categorization (underweight, normal weight, pre-obese, and obese). The descriptive statistics are expressed as the mean and standard deviation for each variable; the analysis of nutrition status was calculated based on BMI, while LSD post hoc testing with ANOVA was employed to investigate differences between the means. The results indicate that a secular trend is visible regarding body height and body weight, while no trend is visible for the BMI and nutrition status. This study’s contribution is that it provides insight into more recently published data for the studied period and in this municipality, which can significantly aid in following the secular trend throughout Montenegro.

Measurement-Based Extraction and Analysis of a Temperature-Dependent Equivalent-Circuit Model for a SAW Resonator: From Room Down to Cryogenic Temperatures

This article provides for the first time a very extensive experimental characterization coupled with a fully analytical modeling in order to investigate, in a systematic and comprehensive way, the sensing performance of a two-port surface acoustic wave (SAW) resonator from room down to cryogenic temperatures. The motivation behind this work is twofold: to quantitatively assess the temperature sensitivity of the SAW technology for cryogenic applications and to gain a better understanding of the underlying physics in terms of the equivalent-circuit elements. Although the measurement-based analysis is developed by focusing on a SAW from Murata as a case study, the developed investigation methodology is independent of the considered technology and extensible to other SAW types. A cryogenic system based on a closed-loop helium refrigerator is used to cool the tested SAW from 300 K down to 20 K with a step of 10 K. At each studied temperature, the scattering parameters are measured using a vector network analyzer over a narrow frequency band around the nominal resonant frequency of 423.2 MHz, spanning from 420 MHz to 425 MHz with a small step of 3.125 kHz. The measured scattering parameters are then transformed into the admittance ones, as they are more useful for sensing performance assessment and for equivalent-circuit model extraction. The extracted model is successfully validated through the achieved good agreement between measurements and simulations of the temperature- and frequency-dependent behavior of the studied resonator.

Field measurement-based wind-induced response analysis of multi-tower building with tuned mass damper

The 246.8-m-tall Beijing Olympic Tower (BOT) is a new landmark in Beijing City, China. Its unique architectural style with five sub-towers and a large tower crown gives rise to complex dynamic characteristics. Thus, it is wind-sensitive, and a double-stage pendulum tuned mass damper (DPTMD) has been installed for vibration mitigation. In this study, a finite-element analysis of the wind-induced responses of the tower based on full-scale measurement results was performed. First, the structure of the BOT and the full-scale measurement are introduced. According to the measured dynamic characteristics of the BOT, such as the natural frequencies, modal shapes, and damping ratios, an accurate finite-element model (FEM) was established and updated. On the basis of wind measurements, as well as wind-tunnel test results, the wind load on the model was calculated. Then, the wind-induced responses of the BOT with the DPTMD were obtained and compared with the measured responses to assess the numerical wind-induced response analysis method. Finally, the wind-induced serviceability of the BOT was evaluated according to the field measurement results for the wind-induced response and was found to be satisfactory for human comfort.

Trajectories in Body Height, Body Weight, BMI, and Nutrition Status From 1979 to 1987: A Measurement-Based Analysis of 15,717 Male Adolescents From the Capital City of Montenegro.

Introduction and Objective: This study aimed to consolidate body height and body weight, as well as the body mass index and nutrition status data of the entire male population of adolescents from Podgorica, the capital of Montenegro, in order to estimate trajectories in ahead mentioned variables from 1979 to 1987.Methods: The sample includes 15,717 male adolescents divided into nine groups according to their year of birth. The sample of variables includes body height, body weight, and body mass index, as well as nutrition status, which was presented based on BMI standardized categories (underweight, normal weight, pre-obese, obese). The descriptive statistics were expressed as a mean and standard deviation for each variable, while post-hoc test with ANOVA were employed to explore differences between the means.Results and Discussion: This study did not find significant differences in the body proportions of the measured group of subjects during the observed period, but some descriptive differences were observed that might be of interest for further analysis, especially when it comes to nutritional status.Conclusions: The novelty and the original contribution of this study is reflected in the fact that descriptive data from the second half of the 20th century have been published, which can significantly help to follow the secular trend of one of the tallest nations in the world from the beginning of the 20th century—Montenegro—which has specific body proportions.

Interaction of Forced Oscillation With Multiple System Modes

Forced oscillations in power systems can lead to disruptive large oscillations across the grid when resonating with inter-area system modes. This letter proposes a rigorous method for estimating the overall impact of a forced oscillation when the forced oscillation frequency is close to the frequencies of multiple system modes. Apart from providing analytical insight, the method is shown to be useful in offline analysis of forced oscillations in large-scale power system models and in measurement-based analysis.

Stability Assessment of Grid-Connected Converter System Based on Impedance Model and Gershgorin Theorem

Converter is an important interface for grid connection of renewable energy, while the interaction between converter and network causes a series of oscillation problems. Because of the confidentiality of the parameters and structure of power electronic devices, the impedance method, as a measurement-based analysis method, is widely used. However, there are some shortcomings in the analysis after obtaining the component impedance matrix, which may bring hidden dangers to the safe operation of power system. In this article, a method of system stability analysis based on impedance model and Gershgorin theorem is proposed. The calculation of eigenvalue loci in the conventional general Nyquist criterion is simplified by estimating the range of eigenvalues using Gershgorin discs, and the relationship between the system stability and the matrix elements is clearly represented. Further, the method is improved to reduce the conservativeness caused by the large radius of Gershgorin discs. Strictly sufficient conditions of system stability and instability, which utilize the matrix elements in an explicitly way, are deduced. The definition of system stability margin is then given. Test results verify the validity and the usability of the proposed method.

Measurement-Based Analysis and Modeling of Multimode Channel Behaviors in Spherical Vector Wave Domain

This paper establishes the analytical model and analyzes the statistical behaviors of multimode channels in spherical vector wave (SVW) domain based on the microcellular radio channel measurement in downtown Helsinki at 5.3 GHz band. The multimode channel is the representation of radio wave propagation in the form of the SVW mode coupling between the transmit and receive antennas. The multimode channel does not rely on particular realizations of antennas at link ends, since any transmitting/receiving/scattering fields associated with an antenna can be modeled as a weighted sum of SVW modes where different antennas have different mode weights. The multimode channels are converted from the plane wave channel model parameters that are extracted from measured channels of coherent snapshots along 6 different routes in Helsinki. Based on the analysis of various first and second order statistics of the multimode channels, the main findings can be summarized as follows: 1) the multimode channels are power imbalanced; 2) the envelope short-term fading statistics of the multimode channels can be described with Rician probability distributions with varying K-factors; 3) the auto-correlations of multimode channels along the spatial translation of a mobile node in a propagation environment present varying coherent distances; 4) the cross-correlations of multimode channels vary with the spatial translation too. The obtained results and the proposed multimode channel model provide invaluable insights into the design of antenna systems tailored to a specific propagation environment. Indeed, antenna systems at both link ends can be devised such that the multimode channels with higher power, larger coherent distance and smaller cross-correlation are excited resulting in multiple-input multiple-output antenna systems that exploit efficiently the degrees of freedom of the propagation channel.

Measuring Sparsity of Wireless Channels

Recently, channel sparsity has been considered as a nature of wireless channels in many researches of intelligent communications, and an increasing number of investigations are conducted by exploiting sparsity of wireless channels, such as deep-learning-based channel estimation and compressive sensing. Growing evidence from channel measurements show that the sparse or approximate sparse distribution assumption of wireless channel is reasonable, however, the observed sparse structure in wireless channels is mostly based on intuitive analysis. Several fundamental aspects of channel sparsity have not been well investigated, and among them, we find that choosing a reasonable measure of channel sparsity has not been fully addressed. To fill the gap, this paper presents several measures for wireless channel sparsity from propagation view and validates them based on realistic channel measurements and data mining methods. Following the spirit that a sparse representation implies a small number of elements contain a large proportion of the energy, the four measures of the number of multipath components (MPCs), channel degrees of freedom (DoF), the Gini index , and the Ricean ${K}$ factor are selected as the potential measures of channel sparsity and fully compared, and the channel diversity measure is used as an indicator of channel sparsity to show the inter-dependency between different measures and channel sparsity. The measurement-based analysis shows that the channel DoF and Gini index provide the best sensitivity and accuracy for measuring channel sparsity, whereas the number of MPCs has the worst performance. Moreover, the widely used channel parameter of Ricean ${K}$ factor is found to have fairly good sensitivity to channel sparsity and can be used for channel sparsity evaluation. The results in the paper can be used to accurately measure sparsity of wireless channel for the design of intelligent communications.

Is oxidation of atmospheric mercury controlled by different mechanisms in the polluted continental boundary layer vs. remote marine boundary layer?

Deposition of atmospheric mercury is of global concern, primarily due to health effects associated with efficient bioaccumulation of mercury in marine food webs. Although oxidation of gaseous elementary mercury (GEM), the major fraction of atmospheric mercury, is a critical stage in regulating atmospheric mercury deposition efficiency, this oxidation is currently not well-characterized, limiting modeling-based assessments of mercury in the environment. Based on a previous study, we hypothesized that the oxidation of GEM is predominantly controlled by multistep bromine- and chlorine-induced oxidation (MBCO) in the remote marine boundary layer (RMBL), and by photochemical smog oxidants, primarily ozone (O3) and hydroxyl radical (OH), in the polluted continental boundary layer (PCBL). To test this hypothesis, we used the following analyses: (i) application of a newly developed criterion to evaluate the gaseous oxidized mercury (GOM)–O3 association based on previous studies in the RMBL and PCBL; (ii) measurement-based box simulations of GEM oxidation in the RMBL and at a PCBL site; and (iii) measurement-based analysis of photochemical oxidation vs. other processes which potentially influence GOM. Our model simulations indicated that the MBCO mechanism can reproduce GOM levels in the RMBL, but not in the PCBL. Our data analysis suggested the important role of photochemical smog oxidants in GEM oxidation in the PCBL, potentially masked by the effect of relative humidity and entrainment of free tropospheric air.