Vapor Products Research Articles

Use of psychoactive substances among students in a Nigerian University: An imperative for intervention programs

Psychoactive substance use is a social and public health issue that has become a global epidemic affecting various countries, including Nigeria. High occurrences of this menace have been recorded among students in different settings with limited reports on university students in Nigeria. Therefore, this study was designed to investigate the magnitude of substance use among students in a Nigerian University and evaluate the strategies to address the problem. A structured self - administered questionnaire was used to obtain information from randomly selected undergraduate students. Information obtained included socio - demographic characteristics, knowledge and perception of substance users. Data was analyzed using Statistical Package for Social Sciences (version 20). The mean age of the respondents was 20 years. The proportions of female and male students were 58.9% and 41.1%, respectively. Twenty percent (20%) of them had consumed alcohol while 16% had taken marijuana and /or opoids including tramadol and codeine. Students who had used electronic vapor products were 27 (11.4%). Except for hashish, the use of substances was not statistically significant for both genders across all substances included in the study. Most (46; 78.0%) of those who had used substances were introduced to the vice by friends, while 4(6.7%) were by their parent/family members. Students (70.4%) who had used substances did so at parties. Peer pressure (73.7%) and curiosity were the highest influencing factors for the use of substances among the students. About 37% agreed that offenders should be punished, 45(19.1%) said ‘No’ to the idea, 54 (22.9%) were unsure and the remaining 49(20.8%) did not respond. Eighty-one (34.3%) of the students sampled, believed that guidance and counseling would be effective in dealing with drug abuse/substance use. Proposed intervention strategies include whistle blowing by the students and organisation of drug free club/association for students. Thus, continued study within the university community will help in the monitoring of patterns and the implementation of effective control strategies.

Assessment and calibration of FY-4A AGRI total precipitable water products based on CMONOC

FengYun 4A (FY-4A) is the first flight unit of the second-generation geostationary meteorological satellite in China (FengYun 4 series, FY-4 series). The Advanced Geostationary Radiation Imager (AGRI) onboard it can provide high spatial resolution precipitable water vapor (PWV) products. This study used Global Navigation Satellite System (GNSS) observations from 230 ground-based GNSS stations within the Crustal Movement Observation Network of China (CMONOC) from March 1, 2019 to February 29, 2020 to obtain PWV, also called total precipitable water (TPW). The Chinese mainland was divided into 13 regions based on climate classification, latitude, and altitude, and GNSS PWV was used to verify the FY-4A AGRI TPW and make calibrations when necessary. The results reveal that the accuracy of FY-4A AGRI TPW shows significant spatial and temporal differences in mainland China. Overall, FY-4A AGRI TPW and GNSS PWV are strongly positively correlated over China, and the correlation coefficients (R) between the two PWV products are highest in autumn (0.78–0.972) while lowest in winter (0.556–0.956). FY-4A AGRI TPW is underestimated in most regions, and the mean bias (MB) values are higher in regions with high PWV content. The root means square error (RMSE) of FY-4A AGRI TPW in all regions are highest in summer (3.34–9.05 mm) and lowest in winter (0.87–3.83 mm). The accuracy of FY-4A AGRI TPW exhibits significant regional and seasonal differences, with higher R, RMSE, and MB in wet seasons and regions, while lower R, RMSE, and MB in dry seasons and regions. This study constructed the calibration model of FY-4A AGRI TPW was based on GNSS PWV in 13 regions. After calibration, the RMSEs can be reduced by 6.6% ~ 32.1%, 5.1% ~ 45%, 5.7% ~ 31.6%, and 7.1% ~ 30.8% in four seasons, respectively, and the MB mainly fluctuates around 0. The accuracy of generated FY-4A AGRI TPW is further improved on the basis of the high resolution.

FENGYUN-4A Advanced Geosynchronous Radiation Imager Layered Precipitable Water Vapor Products’ Comprehensive Evaluation Based on Quality Control System

A physical retrieval algorithm has been developed for deriving the layered precipitable water vapor (LPWs) product from infrared radiances of the Advanced Geosynchronous Radiation Imager (AGRI) onboard FengYun-4A (FY-4A), the first of the new generation of Chinese geostationary weather satellites (FengYun-4, or FY-4 Series). The FY-4A AGRI LPWs are evaluated with different types of reference datasets based on Quality Control System (QCS), including those from Himawari-8 AHI (Advanced Himawari Imager), MODIS (Moderate Resolution Imaging Spectroradiometer), Radiosonde, ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5), NCEP (National Centers for Environmental Prediction) reanalysis and CMA (China Meteorological Administration) forecast product from global medium range numerical weather prediction (NWP) system. QCS is one of the important components of FY-4A ground segment, which mainly focuses on the satellite products’ evaluation and validation. It is found that the AGRI LPW product has a good agreement with different evaluating sources and the quality is favorable and stable. With the capability of frequent (5-min interval) observations over the East Asia and Western Pacific regions, the AGRI LPW products can be used to investigate the atmospheric temporal and spatial variations in the pre-landfall environment for typhoons. The QCS is a useful tool to monitor, evaluate, and validate the AGRI LPW products.

Sociodemographic differences in patterns of nicotine and cannabis vaping among US adults

Nicotine and cannabis vaping has increased over the past several years. While patterns of cigarette and cannabis co-use are well-documented, less is known about the intersection between nicotine and cannabis vaping, especially among adults. Thus, we categorized nicotine and cannabis vaping among adults (18+) who currently (past 30-day) used electronic vapor products (EVPs) from Wave 4 of the Population Assessment of Tobacco and Health Study (n = 3795) as: 1) nicotine only, 2) cannabis only, 3) nicotine and cannabis, and 4) non-nicotine/non-cannabis e-liquid. We calculated vaping pattern proportions overall and by sociodemographic characteristics. Adjusted multinomial logistic regression models assessed associations between sociodemographic characteristics and vaping categories relative to nicotine-only vaping. Approximately half (54.2%) of adults who currently used EVPs vaped nicotine only, 7.4% vaped cannabis only, 23.8% vaped nicotine and cannabis, and 14.6% vaped non-nicotine/non-cannabis e-liquid. Young adults (aged 18–24) (vs. adults aged 35+) had at least three-fold greater odds of vaping cannabis only, nicotine and cannabis, and non-nicotine/non-cannabis e-liquid, compared to nicotine only. Hispanic and non-Hispanic Black (vs. non-Hispanic White) adults had 2.5–3 times greater odds of vaping cannabis only and non-nicotine/non-cannabis e-liquid, compared to nicotine only. Sexual minority adults (vs. heterosexual adults) had 1.5 times greater odds of vaping nicotine and cannabis, compared to nicotine only. Nearly half of adults who vaped EVPs consumed something other than nicotine only, and nicotine/cannabis vaping patterns differed by sociodemographic groups. Vaping and nicotine reduction efforts must recognize that adults who currently vape may be vaping cannabis, or neither nicotine nor cannabis.

Total water vapour columns derived from Sentinel 5P using the AMC-DOAS method

Abstract. Water vapour is the most abundant natural greenhouse gas in the Earth's atmosphere, and global data sets are required for meteorological applications and climate research. The Tropospheric Monitoring Instrument (TROPOMI) on board Sentinel-5 Precursor (S5P) launched on 13 October 2017 has a high spatial resolution of around 5 km and a daily global coverage. Currently, there is no operational total water vapour product for S5P measurements. Here, we present first results of a new scientific total column water vapour (TCWV) product for S5P using the so-called air-mass-corrected differential optical absorption spectroscopy (AMC-DOAS) scheme. This method analyses spectral data between 688 and 700 nm and has already been successfully applied to measurements from the Global Monitoring Experiment (GOME) on ERS-2, the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on Envisat and GOME-2 on MetOp. The adaptation of the AMC-DOAS method to S5P data requires an additional post-processing procedure to correct the influences of surface albedo, cloud height and cloud fraction. The quality of the new AMC-DOAS S5P water vapour product is assessed by comparisons with data from GOME-2 on MetOp-B retrieved also with the AMC-DOAS algorithm and with four independent data sets, namely reanalysis data from the European Centre for Medium range Weather Forecast (ECMWF ERA5), data obtained by the Special Sensor Microwave Imager and Sounder (SSMIS) flown on the Defense Meteorological Satellite Program (DMSP) platform 16 and two scientific S5P TCWV products derived from TROPOMI measurements. Both are recently published TCWV products for S5P provided by the Max Planck Institute for Chemistry (MPIC) in Mainz and the Netherlands Institute for Space Research (SRON), Utrecht. The SRON TCWV is limited to clear-sky scenes over land. These comparisons reveal a good agreement between the various data sets but also some systematic differences between all of them. On average, the daily derived offset between AMC-DOAS S5P TCWV and AMC-DOAS GOME-2B TCWV is negative (around −1.5 kg m−2) over land and positive over ocean surfaces (more than 1.5 kg m−2). In contrast, SSMIS TCWV is on average lower than AMC-DOAS S5P TCWV by about 3 kg m−2. Monthly averaged ERA5 TCWV and AMC-DOAS S5P TCWV comparison shows spatial features over both land and water surface. Over land, there are systematic spatial structures. There are larger differences between AMC-DOAS S5P TCWV and ERA5 TCWV in tropical regions. Over sea, AMC-DOAS S5P TCWV is slightly lower than ERA5 TCWV by around 2 kg m−2. The AMC-DOAS S5P TCWV and S5P TCWV from MPIC agree on average within 1 kg m−2 over both land and ocean. TCWV from SRON shows daily global averaged differences to AMC-DOAS S5P TCWV of around 1.2 kg m−2. All of these differences are in line with the accuracy of these products and with the typical range of differences of 5 kg m−2 obtained when comparing different TCWV data sets. The AMC-DOAS TCWV product for S5P provides therefore a valuable new and independent data set for atmospheric applications which also has a higher spatial coverage than the other S5P TCWV products.

Pyrolysis of low-value waste switchgrass: Physicochemical characterization, kinetic investigation, and online characterization of hot pyrolysis vapours

The present study is dedicated to physicochemical characterization, kinetic, thermal degradation behaviors, and online characterization of vapour products through Py-GC–MS and TGA-FTIR. The feasibility study was attained via proximate, ultimate, fibre analysis, and extractive analysis, whereas Vyazovkin (VM), Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Coats-Redfern (CR), and Distributed Activation Energy Model (DAEM) were employed for kinetics exploration. The feasibility study showed its tremendous ability to be used as pyrolysis feedstock. TGA-FTIR documented the maximum release of CO2 (26.22%), carbonyls (25.04%), and hydrocarbons (15.93%). Further, kinetic investigation of SWG documented an increased trend of activation energy against progressive conversion. The apparent average activation energy from KAS, OFW, DAEM, and VM was found to be 126.03, 137.54, 130.33, 134.26 kJ mol−1, respectively. Also, kinetics reaction mechanisms are exposed to the multi-nature of decomposition of biomass. Furthermore, the Py-GC–MS investigation established increased hydrocarbons (6.49–11.54%) and reduced oxygen-containing products (24.17–17.27%) with an increased temperature

Facile fabrication of solar distillation devices for sewage treatment and purification

Potable water shortage and environmental pollution are two major challenges in terms of the development of human society. Inspired by plant transpiration in nature, 3 D photothermal devices are assembled, mainly including: a floating layer composed of hydrophobic Co3O4 and compound photocatalyst, a hydrophilic layer and a Co3O4 photothermal conversion layer. Non-wetting fabrics not only realizes the photothermal device floating on the water surface, but also obtains the ability of removing the organic solvent and water-soluble pollutants. The fabric surface remained non-wettable, proving its mechanical and temperature stability after blade scraping, surface adhesion, sandpaper grinding and a treatment at 300 °C. The photoresponse ability and degradation of pollutants are improved by forming a heterojunction between composite catalyst, and the O2– is verified as the main active species. A vapor production rate of 2.34 kg•m−2•h−1 under 2 sun illumination is achieved through the 3 D photothermal device. The modular design provides guidance for the flexible application of 3 D photothermal devices.

Estimation of the volume of production of turbine vapor of a fuel boiler with stochastic exogenous factors

The paper is based on the analysis and review of the conceptual principles, methodology and practice of modelling water-steam processes of a fuel boiler of power plants; implementation of algorithms and models of the theory of system dynamics, white and pink noise; using computational technologies of difference-scheme equations and numerical integration methods, the values of the input parameters of the production of turbine vapor of the fuel boiler are determined), which, regardless of stochastic exogenous factors, provide stable states of the necessary and model volumes, norms of water intake and output of turbine vapor of the fuel boiler.* Corresponding author: kerimkhulle@gmail.com

The First Validation of Sentinel-3 OLCI Integrated Water Vapor Products Using Reference GPS Data in Mainland China

The integrated water vapor (IWV) products collected from June 1, 2019 to May 31, 2020 from the ocean and land color instrument (OLCI) sensor, onboard the Sentinel-3 satellites, are evaluated against reference water vapor data estimated from ground-based 214 global positioning system (GPS) stations in the Mainland China. This is the first time to thoroughly evaluate the quality of Sentinel-3 OLCI IWV products by <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> GPS-measured IWV data from such a large spatial coverage as China. The validation results show that, under cloud-free conditions, the OLCI IWV measurements agree very well with the ground-based GPS water vapor data, with a root-mean-square error (RMSE) of 3.03 mm for Sentinel-3A satellite and 3.13 mm for Sentinel-3B satellite. The dependence of OLCI IWV on various parameters was also analyzed. Analysis showed that the accuracy of inland OLCI IWV products was superior to that in coastal areas and that OLCI tended to overestimate IWV value in lower elevation and underestimate IWV value in higher elevation. The accuracy of OLCI IWV measurements increased as IWV decreased. Solar zenith angle analysis showed that the OLCI IWV product had a higher accuracy at a larger solar zenith angle. In spring and winter, the OLCI IWV observations had higher accuracy than those in summer and autumn. OLCI IWV tended to underestimate IWV value in most land cover types. Except for the polar climatic zone, the Sentinel-3 OLCI IWV products tended to overestimate IWV value. The validation results against previous studies were also discussed in this work.

Evaluation of Precipitable Water Vapor Product From MODIS and MERSI-II NIR Channels Using Ground- Based GPS Measurements Over Australia

We performed a thorough validation of the precipitable water vapor (PWV) products from near-infrared bands of very similar instruments, i.e., Moderate Resolution Imaging Spectroradiometer (MODIS) and advanced Medium Resolution Spectral Imager (MERSI-II). The PWV products validated are those derived from MODIS/Aqua, MODIS/Terra, and MERSI-II/FY-3D sensors. The PWV data from global positioning system (GPS) in 453 in situ sites situated in the interior and coastal areas of Australia from June 1, 2019 to May 31, 2020 were utilized as reference values. The accuracy of the satellite PWV products was studied under different weather conditions. The evaluation results show that all the three PWV products did not provide good quality water vapor observations in the presence of clouds, with a correlation below 0.2 and a root-mean-square error (RMSE) above 10 mm. Under confident clear sky conditions, MERSI-II/FY-3D instrument had the highest retrieval accuracy with an RMSE of 2.801 mm, but had the worst correlation with reference GPS PWV ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.841). On the contrary, MODIS/Terra instrument had the lowest retrieval accuracy (RMSE = 4.903 mm), but had the best correlation with a correlation of 0.903. Both MODIS/Aqua and MODIS/Terra instruments tended to overestimate PWV value, whereas the MERSI-II/FY-3D instrument tended to underestimate PWV value. All PWV data records showed better retrieval accuracy with higher correlation and lower RMSE under the dry condition than under the wet condition. The performance analysis of all the three satellite PWV products was also studied per day, per station, per season, and per land-surface type in this article.

Forming and propagation of the cracks initiated with electric explosion of wires in polymer materials

Electrical-physical techniques of intensive mechanical action based in particular on the phenomenon of electric explosion of wires attract more and more attention as methods of high-rated deformation and fracture of polymer spacemen such as Poly(methyl methacrylate) (PMMA), fluoropolymer, etc. Detailed investigation of forming of cracks and dependence between it and propagation of the shock waves through the sample appears to be mandatory for the understanding of the processes of high-rated loading of such polymers.The study investigates forming of the cracks under the action of the cylindrical shock wave initiated with the electric explosion of wire. Generation of such wave performed with short intensive high-voltage discharge through the thin wire placed along we axis of the sample and subsequent expansion of its vaporization products. Propagation of such cracks through cylindrical samples of PMMA and fluoropolymer with various rates of loading was discovered. The comparative specifications of the development of the cracks in PMMA and fluoropolymer were obtained. Threshold fracture parameters of tested materials were estimated for various rates of stress. Analysis of correlation between parameters of the wire explosion and cracks forming and development performed.

Evaluating Precipitable Water Vapor Products From Fengyun-4A Meteorological Satellite Using Radiosonde, GNSS, and ERA5 Data

Precipitable water vapor (PWV) products from the second generation of China&#x2019;s geostationary meteorological satellite Fengyun-4A (FY-4A) have the advantage of high spatiotemporal resolution and can play an increasingly important role in the study of atmosphere and climate. Using the radiosonde, the global navigation satellite system (GNSS), and the European Centre for Medium-Range Weather Forecasts (ECMWF) ReAnalysis 5 (ERA5) reanalysis data, this study presented a comprehensive evaluation of PWV products from FY-4A for a one-year period from January 2019 to January 2020. Results indicated that FY-4A PWV data have a good agreement with radiosonde and GNSS measured ones with the same correlation coefficient of 0.976, and the root mean square errors (RMSEs) are 3.95 and 3.73 mm, respectively. Compared with the radiosonde and GNSS, the FY-4A Advanced Geostationary Radiation Imager (AGRI) was found to underestimate the water vapor during humid conditions when the PWV is greater than 50 mm. The magnitude of underestimation increases with the growth in water vapor content. In terms of spatial variability, the RMSE of FY-4A PWV decreases with the increase in latitude, while the relative RMSE (R-RMSE) displays an opposite pattern. RMSE from the comparison between FY-4A and ERA5 PWV varies from 0 to 6 mm depending upon the location. Statistics showed that 55.08&#x0025;, 59.79&#x0025;, and 83.13&#x0025; RMSE values are less than 4 mm in the evaluation by radiosonde, GNSS, and ERA5, respectively. The seasonal and diurnal variations of RMSE showed that: 1) summer exhibited larger RMSE than winter and 2) daytime obtained slightly worse performance than nighttime.

A Linear Regression of Differential PWV Calibration Model to Improve the Accuracy of MODIS NIR All-Weather PWV Products Based on Ground-Based GPS PWV Data

Precipitable water vapor (PWV) products derived from the near-infrared (NIR) channels of the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments, onboard Aqua and Terra satellites, were calibrated using a linear differential PWV (LinearDP) calibration model based on GPS-retrieved PWV observations. All MODIS NIR PWV pixels were classified into two groups according to the cloud mask of each pixel. For each group, MODIS NIR PWV products and ground-based PWV data from 453 GPS sites in Australia from January 2017 to December 2018 were utilized to determine the differential PWV by subtracting GPS PWV from MODIS PWV. Then, empirical regression relationship between the differential PWV data and the MODIS PWV products was developed using a linear regression approach. The LinearDP model coefficients were independently obtained from each month for each group. The period for model validation spans from January to December in 2019. Comparison of calibrated MODIS NIR PWV versus GPS-derived PWV over Australia showed that the root-mean-square error (RMSE) of Aqua has reduced 42.61% for clear group, 41.43% for cloudy group, and 41.45% for both clear and cloudy groups; and has respectively reduced 53.76%, 37.03%, and 39.33% for Terra. By comparing against ERA5 PWV data, the RMSE reduced 37.21%–43.14% for Aqua and 38.73%–53.87% for Terra. The improvement of MODIS NIR PWV products is further validated in China, with an RMSE reduction of 24.53%–31.78% for Aqua and 28.26%–38.69% for Terra against reference PWV from 214 GPS stations. The mean bias was reduced to −0.415–0.752 mm in Australia and to −0.382–2.013 mm in China.

Sensing Real-Time Water Vapor Over Oceans With Low-Cost GNSS Receivers

Water vapor over oceans is significant for numerical weather prediction (NWP) and climate research. Ocean platform-based global navigation satellite system (GNSS) which can sense the atmospheric water vapor is becoming an important supplement for water vapor measurements over oceans. However, the application of ocean platform-based GNSS meteorology is normally based on geodetic GNSS receivers, which implies the high cost of hardware. In this contribution, we investigate the potential of retrieving real-time water vapor over oceans with a low-cost receiver (u-blox F9P), and a geodetic GNSS receiver (Trimble NetR9) is also equipped in the experiment vessel. The post-processed Trimble NetR9 zenith total delay (ZTD) estimates and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 precipitable water vapor (PWV) products are used for the validation of real-time ZTDs and PWV values. The results show that the real-time ZTDs derived from the low-cost multi-GNSS (GPS + Galileo) observations obtain a difference of over 2.13 cm in root-mean-square (RMS) compared to the post-processed ZTDs with an averaged initialization time of approximately 40 mins. In addition, compared to ERA5 PWV, the real-time PWV derived from u-blox F9P multi-GNSS observations shows a difference in RMS of approximately 4 mm. Although u-blox F9P multi-GNSS performs relatively worse than Trimble NetR9 multi-GNSS in real-time ZTD/PWV estimates, the accuracy of low-cost GNSS receivers derived water vapor over oceans can still meet the requirements for NWP and nowcasting, which demonstrates promising prospects in supplementing the measurements of water vapor over oceans.

Experimental investigation of improving the solar desalination system for domestic buildings: Iraq as a case of study

&lt;abstract&gt; &lt;p&gt;Iraq encounters climatic challenges that lead to severe rainfall shortages and compound the regional challenges that lead to reduced rates of supplying rivers. In this research, the proposed design helps obtain pure water from polluted or saline water t lower, more competitive costs that can supply nearly 80% of the Iraqi markets.&lt;/p&gt; &lt;p&gt;The system harvests 2 L/day of pure water by adding 5 liters of saline water, a 209% daily improvement. The system consists of 1.125 m&lt;sup&gt;2&lt;/sup&gt; of double slope single basin solar still with a tilt angle of 30°, pipes, and measurement instrumentation.&lt;/p&gt; &lt;p&gt;Maximum inside temperature, humidity, valuable energy, and efficiency have 77 ℃, 35%, 4.02 W/m&lt;sup&gt;2&lt;/sup&gt;, and 76%, respectively. System analysis results demonstrated that the average water condensation rate per square meter is about 0.4 L/hr. Finally, the rate of pure water harvesting from this desalination system, per square meter, is about 0.282 L/m&lt;sup&gt;2&lt;/sup&gt; per day when the average intensity of solar radiation reaches 165 W/m&lt;sup&gt;2&lt;/sup&gt;. Two scenarios have been suggested for the experiment. The first scenario tests the system by limiting two water levels, the first at 0.75 cm and the second at 3 cm. The second scenario includes the same design with a black cloth set in the basin demonstrates the most promising data. A wet pad regularly cools down one side of the glass to increase the water vapor condensation and production quantity by 173% to enhancing water production significantly.&lt;/p&gt; &lt;/abstract&gt;

Electronic Vapor Product Use and Levels of Physical Activity Among High School Students in Georgia.

IntroductionUsing a cross-sectional population-based survey, electronic vapor product (EVP) use was evaluated in relation to physical activity levels among high school students in Georgia.MethodsWe used self-reported EVP and cigarette use from the Georgia Student Health Survey 2.0 data from 2018 (N =362 933) and used multi-level multinomial logistic regression models to estimate relative risks of the type of product use relative to no-use by levels of physical activity.ResultsNearly 7% of the students were EVP-only users. The relative risks of being an EVP-only user were 11% and 23% higher for those who were physically active 2-3 days/week and 4-5 days/week, respectively, compared to those who were physically active <=1 day/week.ConclusionsBeing physically active was positively associated with EVP use among adolescents. Health promotion education and health policies should be developed as a means of reducing EVP use among adolescents.

Water Vapor Production by Solar Radiation in a Short Circuit Using a Compound Parabolic Trough Concentrator (CPC)

In this paper water vapor is directly generate in a short circuit by means of a compound parabolic trough concentrator (CPC) while optimizing the manufacturing costs of the solar device used. Direct steam generation has been widely studied, especially for high power systems. However, experimental applications for small solar field areas are rare, especially for concentrating solar technology. This research shows that it is possible to produce water vapor with a CPC for cooking, dry cleaning, maintenance and cleaning, etc. The different heat exchanges that took place in each compartment of the CPC were described. The heat transfer equations were solved by the Gauss-Seidel’s method. An advanced difference scheme is used for the storage terms and a decentered scheme for the transport terms. The numerical simulation has been implemented by matlab code. The different CPC parameters have been directly measure experimentally. The results show that for a CPC length L_c=1 meter and width l_c=50 centimeter, the theoretical temperatures of the water and the absorber can reach 125°C and 150°C respectively, while the experimental temperatures of the water and the absorber are 108°C and 112°C respectively. The temperature of the water vapor measured can reach 110°C. The mass of water vapor produced with this device is 0.110 Kg with a mass flow rate of 3x10^-6 Kg/s and a saturating vapor pressure of 1.05 bar. The theoretical thermal efficiency reached is 52% against an experimental value of 35% for a global solar radiation of 950 W/m² and an ambient temperature of 43°C at solar noon in April 2021. The CPC is designed to operate only during the day, and we are planning to add a heat storage system to our CPC for night use of the steam produced. In addition, instead of water, we can test the CPC's operation in the future with vegetable oils such as moringa oil.

Cavitation and structural analysis on a flanged diffuser applied to hydrokinetic turbines

Flanged diffuser can improve hydrokinetic turbine efficiency. However, in the current literature it is still not clear if the flange allows the possibility of cavitation on its structure, and whether it can support high pressure variation. This work presents a Computational Fluid Dynamics (CFD) study on the effect of cavitation on a flanged diffuser. The water flow through the diffuser was evaluated using a Reynolds Averaged Navier Stokes approach coupled to the Rayleigh-Plesset model to estimate the vapor production rate. The methodology was applied to a flanged diffuser and results were compared with experimental data from the literature. The minimal depth to avoid cavitation on the flanged diffuser was found. The pressure field obtained on CFD was applied as loading in structural analysis using Finite Element Method. The numerical model presented good agreement with experimental data available in the literature. The results showed that cavitation occurs more intensely at a depth of 1.0 m for the model. This intensity gradually decreases as the depth increases. Cavitation can be present in flanged diffusers, especially in the region inside the shroud, where it can directly impact the flow through the rotor. A good safety factor was obtained in the structural analysis.

Comparison of Thermodynamic Performances in Three Geothermal Power Plants Using Flash Steam

Abstract Three geothermal systems, including single-flash, double-flash, and double-flash connected turbine flash geothermal power plants, are compared in terms of electrical power production and exergy efficiency. In the double-flash connected turbine (double-T) geothermal electrical power production systems, the outlet stream from the first steam turbine is recovered in the mixing chamber and combined with the vapor product of the second separator. The thermodynamic model for the single-flash, double-flash, and double-T geothermal systems is developed using energy and exergy balances for each component of the systems. From the thermodynamic model, the optimum flash chambers pressures, at which the electrical power production is a maximum, can be determined. It is found that, for an input geothermal source temperature of 230 °C and an input geothermal water mass flowrate of 230 kg/s, the optimum pressures for the first flash chamber are 300 kPa, 350 kPa, and 350 kPa for the single-flash, double-flash, and double-T geothermal systems, respectively. The electrical power produced in these systems at their corresponding optimum flashing pressures, respectively, are 16,000 kW, 19,500 kW, and 20,600 kW. Also, for the single-flash, double-flash, and double-T geothermal systems, the exergy efficiency at the optimum flash chamber pressures are found to be 44.2%, 47.1%, and 48.5%, respectively.

A Literature Review and Framework Proposal for Halitosis Assessment in Cigarette Smokers and Alternative Nicotine-Delivery Products Users.

Halitosis is a health condition which counts cigarette smoking (CS) among its major risk factors. Cigarette smoke can cause an imbalance in the oral bacterial community, leading to several oral diseases and conditions, including intraoral halitosis. Although the best approach to decrease smoking-related health risks is quitting smoking, this is not feasible for many smokers. Switching to potentially reduced-risk products, like electronic vapor products (EVP) or heated tobacco products (HTP), may help improve the conditions associated with CS. To date, there have been few systematic studies on the effects of CS on halitosis and none have assessed the effects of EVP and HTP use. Self-assessment studies have shown large limitations owing to the lack of reliability in the participants' judgment. This has compelled the scientific community to develop a strategy for meaningful assessment of these new products in comparison with cigarettes. Here, we compiled a review of the existing literature on CS and halitosis and propose a 3-layer approach that combines the use of the most advanced breath analysis techniques and multi-omics analysis to define the interactions between oral bacterial species and their role in halitosis both in vitro and in vivo. Such an approach will allow us to compare the effects of different nicotine-delivery products on oral bacteria and quantify their impact on halitosis. Defining the impact of alternative nicotine-delivery products on intraoral halitosis and its associated bacteria will help the scientific community advance a step further toward understanding the safety of these products and their potentiall risks for consumers.