Ground Level Research Articles

Rapid assessment of cosmic radiation exposure in aviation based on BP neural network method.

Cosmic radiation exposure is one of the important health concerns for aircrews. In this work, we constructed a back propagation neural network model for the real-time and rapid assessment of cosmic radiation exposure to the public in aviation. The multi-dimensional dataset for this neural network was created from modeling the process of cosmic ray transportation in magnetic field by geomagnetic cutoff rigidity method and air shower simulation by a Monte Carlo based Geant4 code. The dataset was characterized by parameters including cosmic ray energy spectrum, Kp-index, coordinated universal time, altitude, latitude, and longitude. The effective dose and dose rate was finally converted from the particle fluxes at flight position by the neural network. This work shows a good agreement with other models from International Civil Aviation Organization. It is also illustrated that the effective dose rate by galactic cosmic ray is <10μSvh-1 and the value during ground level enhancement (GLE) 42 is 4~10 times larger on the routes calculated in this work. In GLE 69, the effective dose rate reaches several mSvh-1 in the polar region. Based on this model, a real-time warning system is achieved.

#2870 Association between frailty and a history of falls in patients on hemodialysis

Abstract Background and Aims Patients with end-stage renal disease on hemodialysis have a higher prevalence of frailty that is associated with relevant outcomes such as disability, hospitalization, and mortality. Moreover, these patients have musculoskeletal and physical function impairments that contribute to a higher risk of falling. Therefore, the aim of this study was to evaluate the association between frailty and a history of falls in patients on hemodialysis. Method This cross-section multicenter study included patients aged ≥18 years who were undergoing regular hemodialysis treatment for at least three months. Patients were excluded if presented severe and unstable comorbidities, psychiatric or cognitive disorders, and physical limitations including neurological, musculoskeletal and osteoarticular diseases which prevented the correct execution of the physical function tests. Frailty was assessed by Fried phenotype and the criteria were as follows: unintentional weight loss ≥ 4.5 kg in the past year; exhaustion was assessed using the vitality domain of the SF-36 quality of life questionnaire; weakness was measured using a handgrip dynamometer; walking speed was assessed by timing the 4.6 m distance covered at the participant's normal pace; and physical activity level was measured by the Human Activity Profile questionnaire. Patients were stratified into three groups: a score of 0/5 for non-frail, a score of 1-2/5 for pre-frail, and a score of 3-5/5 for frail. The retrospective history of falls was assessed for the last 12 months, and a fall was defined as an “unexpected event in which the individual comes to rest on the ground, floor or lower level”. The association between frailty stratification and a history of falls was analyzed using multivariate multinomial logistic regression model with non-frail group as reference. Then, a model adjusted for potential confounders was constructed. Results This study included 199 patients (59.1 ± 12.5 years, 41.2% female). The prevalences of frailty and pre-frailty were 17.6% and 54.8%, respectively. Patients classified as non-frail showed lower prevalence of a history of falls compared to patients classified as pre-frail and frail (26%, 36% and 54%, respectively, p &amp;lt; 0.001). The absence of a history of falls decreased the chance of patients being classified as frail (OR = 0.23, 95% CI = 0.07-0.78, p = 0.018). After adjusting for age, educational level, time on dialysis, hemoglobin and presence of cardiovascular disease, this association remained significant (OR = 0.16, 95% CI = 0.04-0.57, p = 0.005). Conclusion The prevalence of pre-frailty was approximately three times higher than that of frailty in patients on hemodialysis. A history of falls was associated with frailty in these patients.

Establishing the case for a May 2010 low-yield, unannounced nuclear test in North Korea

AbstractNew data, analyses and modelling are presented concerning the unprecedented mid-May 2010 series of fission product detections in ground level air on and around the Korean Peninsula. For the first time Ba-140 is revealed at Ussuriysk, for which only La-140 had been reported. Thus aerosol particles containing the same parent-daughter pair Ba-140/La-140 were detected at both Ussuriysk and Okinawa, establishing beyond reasonable doubt that their physical, spatial and temporal origins are the same. Together with Ce-141 and Cs-137, all with short-lived xenon isotope parents, a supercritical fission excursion, which experienced a near prompt filtered vent, is the only viable scenario for their explanation. New modelling suggests that the vent occurred around 9 s after the excursion and that the CTBT-relevant xenon isotopes Xe-133 and Xe-135 were ‘quenched’ around 25 min later and released some 10–20 h afterwards. Published corroborating seismic and infrasound data of an event at the North Korean nuclear test site 8 min and 45 s past midnight on 12 May 2010 is subsequently reviewed. These papers adopted a conventional depth of the event although the data suggested a shallower one. Despite arguments in the seismic community about its exact nature, it is prudent to test how well the waveform signals marry the radionuclide detection pattern. Thus the location and time are input into a new atmospheric transport model. The advanced software suite MATCH was used in forward mode with prompt and delayed releases, revealing the presence of plumes at each detection site at the time of their first detection and extending over the observed timeframe. Thus a very consistent picture of a shallow low yield nuclear test is obtained.

Feasibility of Wind Energy Utilization for Sustainable Power Generation in Ilorin, Kwara State, Nigeria's North-Central Region

The escalating energy demands across Nigeria, especially in remote rural areas, have outpaced the capacity of the national electricity grid, necessitating the development of independent and sustainable energy sources. Among the renewable options, wind energy stands out as a promising solution. This study focuses on assessing the potential of wind energy in Ilorin, located in Kwara State, within Nigeria's north-central region. Utilizing data collected from 2007 to 2021 by the Nigerian Meteorological Agency, the research examines monthly average wind speeds at two specific coordinates in Ilorin, considering variations in air density. The study utilizes a 15-year set of monthly average wind velocities obtained from the Nigerian Meteorological Agency (NiMet) Headquarters in Abuja, measured at a height of 10 meters above ground level. By employing the 2-coefficient Weibull statistical model and extrapolation principles across different altitudes ranging from 150 to 900 meters above ground level, the study reveals distinct seasonal patterns of wind speeds ranging from 1.1 to 5.1 m/s in Ilorin. Furthermore, wind power density values ranging from 6.7 to 39.20 W/m2 are identified, with optimal wind attributes observed at altitudes exceeding 900 meters. These findings provide valuable insights for assessing the feasibility of wind energy utilization and designing efficient systems in Nigeria's north-central regions, aiding in the sustainable energy transition.

Long-term effects of biochar application on biological nitrogen fixation of acacia species and soil carbon and nitrogen pools in an Australian subtropical native forest

Abstract Purpose Biological nitrogen (N) fixation (BNF) of understory acacia species presents a potential way for effectively restoring N in forest systems. This study aimed to quantify the impact of acacia species and biochar application rates on BNF and soil mineral N in a suburban native forest of subtropical Australia in the first 4–5 years after prescribed burning. Method Plant growth values and BNF were measured to assess the impact of biochar rates at 0, 5, and 10 t ha−1 on different acacia species. Soil NH4+-N and NO3−-N along with their N isotope composition (δ15N) were determined to investigate soil–plant interactions in response to acacia species and biochar application. Results The application of 10 t ha−1 biochar significantly enhanced the growth of acacia species, and concurrently reduced the loss of NO3−-N at soil depths of 0–5 and 5–10 cm. Compared with Acacia disparimma (percentage of N derived from the atmosphere or %Ndfa: 78.2%), A. leiocalyx demonstrated significant higher BNF ability (%Ndfa: 91.3%). Similarly, A. leiocalyx had better growth, in terms of height (269.1 cm versus 179.6 cm), diameter at ground level (2.62 cm versus 1.94 cm), basal area (6.49 cm2 versus 3.43 cm2) and volume (692.2 cm3 versus 258.0 cm3). This was associated with its ability to promote organic matter mineralization, resulting in the accumulation of 15N-depleted NH4+-N. NH4+-N, acting as a substrate, was transformed into NO3−-N through nitrification. From regression analysis, the efficient absorption of NH4+-N by A. leiocalyx significantly mitigated NH4+-N leaching with increasing soil moisture concentration (SMC), resulting in lower δ15N of NH4+-N, which was more negatively related to SMC (R2 = 0.401), compared to that of A. disparimma (R2 = 0.250) at soil depth of 0–5 cm. The production of NO3−-N was reduced, leading to lower NO3−-N concentrations of A. leiocalyx than A. disparimma at soil depth of 0–5 cm (8.06 µg N g−1 versus 9.61 µg N g−1) and that of 5–10 cm (8.24 µg N g−1 versus 9.21 µg N g−1) respectively. Conclusions As an effective soil amendment, biochar exhibited promise in reducing mineral N loss and stimulating plant growth in long-term applications of exceeding three years. Higher BNF capacity and greater plant growth were observed with A. leiocalyx, compared with those of A. disparimma. The retention and utilisation of mineral N by A. leiocalyx can be considered as strategy to restore forest soils.

A Review on Design and Fabrication of Affordable Lift for Built Home

Lift may be a very simple mechanical equipment used to raise elements or objects or load from ground level to a specific height to perform a particular work with maximum load capacity and minimum efforts of a worker. The objective of this work is to develop a mechanism for climbing up and down over stairs for aged and physically challenged people and easy mobility of the whole elevator. To achieve this, we require high strength materials, wheels, etc. All the researchers attempt to optimize these parameters according to the concerned requirements. This review paper is focused on the analysis of some research papers containing the entire study of components, selection of materials, and analysis of dimension of components. After the analysis of research papers, long term scope of the research was also suggested. This review paper focuses on the analysis of several research papers that explore the entire study of components, selection of materials, and analysis of dimension of components. It provides insights into current advancements in the field and evaluates different approaches to developing a stair-climbing mechanism for aged and physically challenged individuals.

A New Wave in Biometric System: Systematic Study incorporated with Artificial Intelligence

Biometric system is a technique used to identify a person using its personal identification methods. The main concept of biometric systems is to provide confidentiality and security to the user. A number of biometric systems are introduced but some systems are widely used and are famous because of their usage and security they provide. Physiological and Behavioral biometrics are the two types of biometric systems. Biometric systems include physiological biometric like face recognition, finger print recognition, ir is recognition and behavioral biometrics like signature recognition and voice recognition. All these recognition systems are discussed in this research paper. Biometric systems work on three levels: Enrollment, Verification, and Identification. Enrollment is the process in which patterns are captured from the user and stored in the database. Verification means to confirm that the sample entered by the user belongs to him or not. When the user wants to access the data then the user must use his/her biometrics that the systematic hacks that the person who wants to access the data is the real owner of the data or not. This process is identification. All three levels are the working levels of the Biometric System. In earlier years, biometrics was used only at ground levels to provide basic security to data but now the tables have turned. It is playing a major role in providing security to our data. Biometrics are not only used in day-to-day life in phone unlocking, phone assistants, attendance systems but also used at advanced levels like in airports, border security, cloud computing etc. In this research paper, we will discuss the future scope of biometric systems and how it could even change the future.

An efficient method for modeling and evaluating the bench terrain of open-pit mines

In order to quantitatively analyze the roughness of the bench floor during open-pit mine blasting, this study proposes a real-time measuring method for the three-dimensional terrain of the bench floor during the excavation process. Real-time monitoring is conducted at the boundary and discrete internal points of the workbench floor during electric shovel operation, utilizing real-time kinematic global navigation satellite system (RTK-GNSS) positioning technology. An improved convex hull algorithm is introduced to automatically extract the optimal boundary of discrete point clouds based on their spatial distribution characteristics. This study establishes a digital elevation model (DEM) using five interpolation algorithms for 3D terrain visualization simulation. Through cross-validation, a comparative analysis of the DEM accuracy, the simulation results of the ordinary kriging interpolation algorithm were found to be optimized. The optimized interpolation algorithm is applied to simulate the 3D terrain in the Dexing open-pit copper mine, and the relevant terrain parameters were calculated. This dataset can serve as a precise foundation for the real-time path planning of elevation blasting design and ground leveling operations.

Differentiating anthropogenic effects from natural metal(loid) levels in residential soil near a zinc smelter in South Korea.

Metal(loid)s pose a significant hazard due to inherent toxicity. Individuals are particularly exposed to metal(loid)s in soil through direct or indirect contact. Identifying metal(loid) sources in soil is required for exposure mitigation to anthropogenic metal(loid)s, while metal(loid)s are natural constitutes of soil. Metal(loid) concentrations and Pb isotopes were determined in residential soil profiles impacted by a Zn smelter to distinguish the anthropogenic effect from natural levels. One hundred sixty-nine core soil samples were collected from depths down to 5.5m below ground level at 19 sites and were divided into Zn-Cd-As- and As-contaminated groups based on the worrisome level (WL) of soil contamination. The Zn-Cd-As-contaminated group (n = 62) was observed at depths < 1m, showed high Zn levels (mean of 1168mg/kg) and Cd and As frequently exceeding WLs, and had low 206Pb/207Pb ratios close to the Zn smelter. In contrast, the As-contaminated group (n = 96) was observed at depths > 1m, did not have other metals exceeding WLs, and showed a wide range of 206Pb/207Pb ratios far away from the Zn smelter. The results indicated that the pollution sources of Zn-Cd-As- and As-contaminated soils were fugitive dust emissions from smelter stacks and geology, respectively. The metal(loid)s in host rock set geochemical baselines in soil profiles, while smelting activities affected the upper layers over 50years. This study demonstrated the effectiveness of utilizing the vertical distribution of metal(loid) concentrations and Pb isotopes in soil profiles for distinguishing between anthropogenic and geogenic origins, in combination with baseline assessment.

Seasonal variation of background counting rates in liquid scintillation counting

A liquid scintillation background sample was measured daily in a custom-built TDCR counter for more than 17 months. The double and triple coincidence counting rates exhibit an annual sinusoidal fluctuation with a maximum in winter and a minimum in summer. Possible correlations with air temperature, air humidity, radon concentration and secondary cosmic radiation were investigated. The observation of a correlation with the ambient dose equivalent rate H˙*(10)SCR originating from the charged component of secondary cosmic radiation and an anti-correlation with the effective atmospheric temperature Teff suggest that the seasonal fluctuations in the background counting rate may be primarily driven by temporal variations in the muon flux at ground level. Additionally, a correlation was found with the indoor 222Rn concentration in air.

Tethered balloon system and High-Resolution Mass Spectrometry Reveal Increased Organonitrates Aloft Compared to the Ground Level.

Atmospheric particles play critical roles in climate. However, significant knowledge gaps remain regarding the vertically resolved organic molecular-level composition of atmospheric particles due to aloft sampling challenges. To address this, we use a tethered balloon system at the Southern Great Plains Observatory and high-resolution mass spectrometry to, respectively, collect and characterize organic molecular formulas (MF) in the ground level and aloft (up to 750 m) samples. We show that organic MF uniquely detected aloft were dominated by organonitrates (139 MF; 54% of all uniquely detected aloft MF). Organonitrates that were uniquely detected aloft featured elevated O/C ratios (0.73 ± 0.23) compared to aloft organonitrates that were commonly observed at the ground level (0.63 ± 0.22). Unique aloft organic molecular composition was positively associated with increased cloud coverage, increased aloft relative humidity (∼40% increase compared to ground level), and decreased vertical wind variance. Furthermore, 29% of extremely low volatility organic compounds in the aloft sample were truly unique to the aloft sample compared to the ground level, emphasizing potential oligomer formation at higher altitudes. Overall, this study highlights the importance of considering vertically resolved organic molecular composition (particularly for organonitrates) and hypothesizes that aqueous phase transformations and vertical wind variance may be key variables affecting the molecular composition of aloft organic aerosol.

Continental-scale patterns in diel flight timing of high-altitude migratory insects.

Many insects depend on high-altitude, migratory movements during part of their life cycle. The daily timing of these migratory movements is not random, e.g. many insect species show peak migratory flight activity at dawn, noon or dusk. These insects provide essential ecosystem services such as pollination but also contribute to crop damage. Quantifying the diel timing of their migratory flight and its geographical and seasonal variation, are hence key towards effective conservation and pest management. Vertical-looking radars provide continuous and automated measurements of insect migration, but large-scale application has not been possible because of limited availability of suitable devices. Here, we quantify patterns in diel flight periodicity of migratory insects between 50 and 500 m above ground level during March-October 2021 using a network of 17 vertical-looking radars across Europe. Independent of the overall daily migratory movements and location, peak migratory movements occur around noon, during crepuscular evening and occasionally the morning. Relative daily proportions of insect migration intensity and traffic during the diel phases of crepuscular-morning, day, crepuscular-evening and night remain largely equal throughout May-September and across Europe. These findings highlight, extend, and generalize previous regional-scale findings on diel migratory insect movement patterns to the whole of temperate Europe. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

The characteristics of the vertical distribution of radionuclide in free troposphere from simplified release scenarios: a case study

Dose estimation in the upper air is not studied as much as on ground level or in boundary layer. However, there is a need from stakeholders in aviation industry for a reasonable estimation of the radioactive plume impact at cruising levels. This study aims to provide a quantitative estimation of the dose and how reliable it is for dispersion processes up to seven days. A Lagrangian atmospheric dispersion model is used to estimate quantitively the vertical extension of radionuclides from simplified hypothetical radionuclide release scenarios. Sources at different latitudes are selected for simulation in a boreal winter case. Three meteorological data are examined to test the sensitivity of vertical plume distribution to driving meteorological data. The vertical distribution of air concentration of radionuclides is investigated and the associated uncertainties are analysed. It is found that the vertical extension of plumes is sensitive to meteorological data being used where vertical turbulent velocities play an important role. It is therefore necessary to address the uncertainties of air concentration or dose in the free troposphere and caution must be taken when providing the results to stakeholders.

PSIV-A-2 Comparison of rising plate meter and total collection methods for forage mass determination of tall fescue

Abstract The objective was to compare estimates of forage mass (FM) determined with a rising plate meter (RPM) with forage mass determined by total collection method. Estimates of FM impact management decisions and give the producer a greater understanding of forage availability for their herd. Traditional methods of FM estimation using a forage ring or quadrat and total collection are labor intensive and time consuming. The RPM tool aims to provide a quicker method of FM estimation without sacrificing accuracy. The reliability of this tool can be impacted by season, species composition, plant growth state, and pasture management. Forage samples were collected from six random locations within both continuous and rotationally grazed systems. The predominant forage species was endophyte-infected tall fescue. A 0.25 m2 forage ring was randomly thrown, then two RPM (Jenquip Manual Platemeter) measurements were collected in the ring, followed by five measurements adjacent to the ring. The RPM determined the compressed sward height (CSH). Subsequently, forage within the ring was hand-clipped at ground level and collected. Samples were dried for 120 h at 55° C to determine forage availability (kg/ha). This process was repeated weekly for 6 wk. Rising plate meter FM was estimated using the equation: kg dry matter (DM)/ha = CSH × 158 + 200. Data were analyzed using the CORR procedure of SAS 9.4. Forage mass estimates from total ring collection method and RPM were weakly correlated in the rotational grazing system (r = 0.26; P = 0.13) and in the continuous grazing system (r = 0.20; P = 0.24). It is important to note that certain sample collection dates had stronger correlations than others. In the rotationally grazed paddocks, FM from RPM were strongly correlated (r ≥ 0.89, P ≤ 0.02) with FM from total ring collection on 6/23/23 and 7/26/23. In the continuously grazed paddocks, FM estimations from RPM were strongly correlated (r ≥ 0.73, P ≤ 0.10) with forage mass from total collection on 7/20/23 and 7/26/23. Variation among the seven RPM readings at each collection site could have contributed to variability. Coefficient of variation ranged from 9 to 48% and averaged 18% for all samples. The inconsistencies in relationship of forage mass determination methods suggests that more variables need to be considered when determining the accuracy of RPM-derived estimates of forage mass of tall fescue.

High resolution Tibetan Plateau regional reanalysis 1961-present

With the rapid global warming in recent decades, the Tibetan Plateau (TP) has suffered severe impacts, such as glacier retreat, glacial lake expansion, and permafrost degradation, which threaten the lives and properties of the local and downstream populations. Regional Reanalysis (RR) is vital for TP due to the limitations of observations. In this work, a 62-year (1961–2022) long atmospheric regional reanalysis with spatial resolution of 9 km (convective gray-zone scale) and temporal resolution of 1 hour over the TP (TPRR) was developed using the Weather Research and Forecasting (WRF) model, combined with re-initialization method, spectral nudging (SN), and several optimizations. TPRR is forced by ERA5 at hourly intervals. TPRR outperforms ERA5, realistically capturing climatological characteristics and seasonal variations of precipitation and T2m (air temperature at 2m above ground level). Moreover, TPRR better reproduces the frequency and intensity of precipitation, as well as the diurnal cycle of precipitation. This study also quantifies the wetting trend of 0.0071 mm/year over the TP amid global warming using TPRR.

Decay level classification of wooden components in Tingbao Yang’s former residence utilizing polarization and fluorescence effects

Decay levels of wooden components in the Yang former residence were classified using polarized light and fluorescence methods. Analysis of the decay cause was conducted based on external conditions and wood species characteristics. The polarization and fluorescence effects revealed that there were varying degrees of decay in larch (Larix potaninii var. australis), spruce (Picea brachytyla), lace-bark pine (Pinus bungeana), Masson pine (Pinus massoniana), Chinese Douglas fir (Pseudotsuga sinensis), Chinese fir (Cunninghamia lanceolata), poplar (Populus tomentosa), and elm (Ulmus pumila). The primary factors contributing to decay included the inherent low natural durability of the wood species and adverse external conditions, such as damaged roofs, missing dripping water and tiles causing water leakage, uneven indoor and outdoor ground levels, contemporary tile paving indoors, and inadequate ventilation. This study aims to establish a scientific basis for subsequent conservation strategies.

Influencing factors on regeneration and seedling survival prediction in Larix principis‐rupprechtii plantations in northern China

AbstractThe natural regeneration of forest ecosystems is crucial for their sustainability, but uncertainties have impeded the regeneration of some tree species. Identifying influencing factors and effective strategies to enhance seedling survival and growth is essential. We investigated factors affecting the natural regeneration of Larix principis‐rupprechtii and provided insights into seedling survival and growth. Eighteen artificial L. principis‐rupprechtii forest plots were established and monitored for 3 years. A logistic regression analysis and generalized linear models were used to investigate the influence of stand age, diameter at ground level, height, and other microhabitat factors on seedling regeneration. The microhabitat factors significantly influenced the overall L. principis‐rupprechtii regeneration density, as well as the density and growth of regenerated trees in different height classes. The area under the curve values for total nitrogen (0.796), total phosphorus (0.726), soil moisture (0.759), and litter thickness (0.633) were the highest, indicating a significant impact on the survival rate and mortality of the seedlings. Among these values, total nitrogen sensitivity (0.857) and specificity (0.810) were the highest, and the optimal threshold was 0.940. The survival rate decreased with increasing forest age, and the stands aged 4–7 years with a height of 1–2.5 m and a diameter at the ground level of approximately 2 cm constituted a relatively vulnerable and critical set of conditions for the survival of L. principis‐rupprechtii seedlings. The model showed that at 12 years old, L. principis‐rupprechtii trees were no longer vulnerable to mortality. The Kaplan–Meier model predicted future seedling survival through the construction of the comprehensive influence value and the measured seedling survival number. The model can be used to evaluate the survival rate for the final regeneration of a species, and targeted artificial seeding or replanting can improve the proportion of seedlings that survive. Our findings contribute to elucidating the factors affecting the natural regeneration of forest species and provide valuable insights for the development of effective regeneration strategies.

Hydrological variability of middle European peatland during the Holocene, inferred from subfossil bog pine and bog oak dendrochronology and high-resolution peat multiproxy analysis of the Budwity peatland (northern Poland)

Subfossil pine and oak tree trunks were excavated during exploitation of the Budwity peatland in Northern Poland. Based on dendrochronological analysis, the woodland successions in peatland were reconstructed and correlated with moisture dynamics of the peatland ecosystem inferred from the high-resolution multi-proxy analysis of the peatland deposits. From the results of dendrochronological analysis and the 14C wiggle matching methods, four floating pine chronologies (5882–5595; 5250–5089; 3702–3546; and 2222–1979 mod. cal BP) and two oak chronologies (4932–4599 and 4042–3726 mod. cal BP) were developed. The organic sediments of the peatland (6 m thick) were deposited over approximately nine thousand years. The lower complex (525–315 cm) comprises minerogenic peat, while the upper complex (315.0–0.0 cm) is composed of ombrogenic peat. Subfossil tree trunks are distributed across various peat horizons, which suggests multiple stages of tree colonisation followed by subsequent dying-off phases. Multiproxy sediment analyses (lithological, geochemical and δ13C stable isotope, pollen, plant macrofossils, Cladocera, diatom, and Diptera analyses) indicate that the two earliest phases of pine colonisation (5882–5595 and 5250–5089 mod. cal BP) and the two stages of oak colonisation (4932–4599 and 4042–3726 mod. cal BP) were associated with periodic drying of the peatland. Conversely, tree dying-off phases occurred during periods of increased water levels in the peatland, coinciding with stages of increasing climate humidity during the Holocene. The two most recent phases of pine colonisation occurred during the ombrogenic stage of mire development. Remnants of the dead forest from these phases, marked by subfossil trunks still rooted in the ground, were preserved and exposed presently during peat exploitation, approximately 2.5 m below ground level. The identified phases of tree colonisation and subsequent dying-off phases show correlation with analogical phenomena observed in the other investigated European peatlands.

Detecting clear‐sky periods from photovoltaic power measurements

AbstractA method for detecting clear‐sky periods from photovoltaic (PV) power measurements is presented and validated. It uses five tests dealing with parameters characterizing the connections between the measured PV power and the corresponding clear‐sky power. To estimate clear‐sky PV power, a PV model has been designed using as inputs downwelling shortwave irradiance and its direct and diffuse components received at ground level under clear‐sky conditions as well as reflectivity of the Earth's surface and extraterrestrial irradiance, altogether provided by the McClear service. In addition to McClear products, the PV model requires wind speed and temperature as inputs taken from ECMWF twentieth century reanalysis ERA5 products. The performance of the proposed method has been assessed and validated by visual inspection and compared to two well‐known algorithms identifying clear‐sky periods with broadband global and diffuse irradiance measurements on a horizontal surface. The assessment was carried out at two stations located in Finland offering collocated 1‐min PV power and broadband irradiance measurements. Overall, total agreement ranges between 84% and 97% (depending on the season) in discriminating clear‐sky and cloudy periods with respect to the two well‐known algorithms serving as reference. The disagreement fluctuating between 6% and 15%, depending on the season, primarily occurs while the PV module temperature is adequately high and/or when the sun is close to the horizon with many more interactions between the radiation, the atmosphere and the ground surface.

Measuring the concentration of radon gas at the College of Dentistry- Al-Iraqia University using (CR-39) detector

In this study, the concentration of radon gas was measured at the College of Dentistry-Al-Iraqia University using a nuclear pathway detector (CR-39). The detector was placed at a distance of 160 cm from the ground level. The detector was exposed to alpha fragments for 30 days. The results showed that the concentration of radon gas has Changed from one site to another. It ranged from the lowest (28.418 Bq/m3) to the highest (233.491 Bq/m3), with an average radon concentration equal to (90.279 Bq/m3). All results were within the permissible limit of a scientist except for one sample A2 in the chemistry laboratory, which was higher than the international permissible limits (200-300 Bq/m3) and recorded by the International Commission on Radiological Protection Statement on Radon.