Siga este enlace para ver otros tipos de publicaciones sobre el tema: Maximum hourly factor.
Artículos de revistas sobre el tema "Maximum hourly factor"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores artículos de revistas para su investigación sobre el tema "Maximum hourly factor".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore artículos de revistas sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Plucinski, M. P., A. L. Sullivan y W. L. McCaw. "Comparing the performance of daily forest fire danger summary metrics for estimating fire activity in southern Australian forests". International Journal of Wildland Fire 29, n.º 10 (2020): 926. http://dx.doi.org/10.1071/wf19185.
Texto completoResumen
Fire danger indices integrate weather and fuel variables to indicate the potential for wildland fires to ignite, spread, resist suppression and cause damage. McArthur’s Forest Fire Danger Index (FFDI) is applied across much of Australia, with the forecast daily maximum value used to inform fire management planning decisions and issuance of public warnings. Variations in daily maximum FFDI and the hourly changing of FFDI values during the day (including use of different soil moisture deficit indices) were compared against five binary fire activity statistics in six forested areas in southern Australia, with performance assessed using Theil–Sen regression lines fitted to rank percentile curves. Fire activity rates were similar on days with wide and narrow hourly FFDI distributions except in one study area where days with wide distributions experienced more fires. The maximum hourly FFDI metric performed the best of all the metrics tested, though there were no statistically significant differences among any of them. There was also little difference in the performance of metrics determined using alternative calculations and different drought indices. These results suggest that the current use of the forecast hourly maximum FFDI is appropriate and that using alternative methods to determine Drought Factor offers little benefit.
2
Uchida, Daisuke, Kenji Otani y Kosuke Kurokawa. "Evaluation of effective shading factor by fitting a clear-day pattern obtained from hourly maximum irradiance data". Solar Energy Materials and Solar Cells 67, n.º 1-4 (marzo de 2001): 519–28. http://dx.doi.org/10.1016/s0927-0248(00)00321-4.
Texto completo
3
Wang, Ling Ling, Shu Ju Hu, Yan Feng Meng y Rui Ma. "Analysis of the Influence of Environment Parameters on Grid-Connected Photovoltaic System". Applied Mechanics and Materials 521 (febrero de 2014): 13–18. http://dx.doi.org/10.4028/www.scientific.net/amm.521.13.
Texto completoResumen
The performance of grid-connected Photovoltaic (PV) power generation system operating in the field is inevitably affected by environmental parameters (solar irradiance, temperature, humidity, wind speed, spectrum, cloud cover, dust, etc.), of which the main factors are solar irradiance and temperature. Based on the data of 100kW PV system of ShangYi PV Plant captured form June 1, 2012 to May 31, 2013 (1 min resolution) and the data of Qinghai Delingha 20MW PV Plant in China captured in 2012., the influence of solar irradiance and temperature on PV system is analyzed. The results show hourly PV array DC power has highly significant positive correlation with hourly total solar radiation, also PV system AC power output and solar irradiance have good consistency. Both of them show irradiance is the main environment factor to the PV system. Then using the captured data, the relationship between maximum load and PV panels surface temperature is also analyzed, the surface temperature is higher, the maximum load is lower.
4
Dec, Ewelina, Bożena Babiarz y Robert Sekret. "Analysis of temperature, air humidity and wind conditions for the needs of outdoor thermal comfort". E3S Web of Conferences 44 (2018): 00028. http://dx.doi.org/10.1051/e3sconf/20184400028.
Texto completoResumen
On the thermal comfort of a man staying outdoor during the summer affect mostly meteorological factors, physical activity and the type of clothing. The work analyzed external air parameters, such as: temperature, relative humidity and wind speed, occuring in years 1997‒2016. Meteorological data recorded at the RzeszÓw-Jasionka station allowed to determine, among others, the occurrence of maximum daily and hourly temperatures of outdoor, the daytime and hourly air relative humidity, the hourly wind speed, as well as the relationship between these parameters. In recent years, it has been observed the increase of the number of hot and very hot days which indicates a warming of the climate. The duration of series of days with maximum daily temperature above 30°C is also prolonged, which is not comfortable for a person staying outside. During summer, during hot and very hot days, the average relative humidity remained below 70%. The daily course of this factor was characterized by the opposite tendency with respect to temperature. The wind speed in the summer season varies from 0 to 6 m/s. On a daily basis, the increase in wind speed occurred in the afternoon hours which is consistent with the temperature characteristics. The occurrence of wind during the hottest hours causes a pleasant cooling of the organism.
5
Wang, Wenting, Shuiqing Yin, Dennis C. Flanagan y Bofu Yu. "Comparing CLIGEN-Generated Storm Patterns with 1-Minute and Hourly Precipitation Data from China". Journal of Applied Meteorology and Climatology 57, n.º 9 (septiembre de 2018): 2005–17. http://dx.doi.org/10.1175/jamc-d-18-0079.1.
Texto completoResumen
AbstractClimate Generator (CLIGEN) is a stochastic weather generator that has been widely used to generate daily precipitation and storm patterns for hydrological and erosion prediction models. Rainfall data with measurement intervals ≤ 30 min are required to compute two parameters for generating storm patterns, namely, the cumulative distribution of the time to peak rainfall intensity (TimePk) and the mean daily maximum 30-min rainfall intensity (MX.5P). High-resolution rainfall data, however, are not widely available around the world. One-minute precipitation data for 18 stations in eastern and central China were aggregated into hourly intervals to evaluate methods to optimally prepare TimePk and MX.5P for CLIGEN. Four sets of the two parameters were used to run CLIGEN for comparison: C0, using the original 1-min data; C1, replacing TimePk with those computed with hourly data; C2, replacing MX.5P with those computed with hourly data with an adjustment factor; and C3, replacing both parameters with those computed with hourly data, and the MX.5P was adjusted as for C2. Results showed that 1) MX.5P computed with hourly data was systematically lower than that computed with the 1-min data, and the bias could be corrected by multiplying by an adjustment factor of 1.40; 2) the difference in generated storm patterns between C0 and C1 was insignificant; and 3) results from C2 and C3 agreed well with those generated from C0. Hourly precipitation data can be used to prepare CLIGEN input parameter values for generating storm patterns for sites where only hourly data are available.
6
Krecl, P., E. Hedberg Larsson, J. Ström y C. Johansson. "Contribution of residential wood combustion to hourly winter aerosol in Northern Sweden determined by positive matrix factorization". Atmospheric Chemistry and Physics Discussions 8, n.º 2 (19 de marzo de 2008): 5725–60. http://dx.doi.org/10.5194/acpd-8-5725-2008.
Texto completoResumen
Abstract. The combined effect of residential wood combustion (RWC) emissions with stable atmospheric conditions, which is a frequent occurrence in Northern Sweden during wintertime, can deteriorate the air quality even in small towns. To estimate the contribution of RWC to the total atmospheric aerosol loading, the positive matrix factorization (PMF) method was applied to hourly mean particle number size distributions measured in a residential area in Lycksele during winter 2005/2006. The sources were identified based on the particle number size distribution profiles of the PMF factors, the diurnal contributions patterns estimated by PMF for both weekends and weekdays, and correlation of the modeled particle number concentration per factor with measured aerosol mass concentrations (PM10, PM1, and light-absorbing carbon MLAC). Through these analyses, the factors were identified as local traffic (factor 1), local RWC (factor 2), and local RWC plus long-range transport (LRT) of aerosols (factor 3). In some occasions, it was difficult to detach the contributions of local RWC from background concentrations since their particle number size distributions partially overlapped and the model was not able to separate these two sources. As a consequence, we report the contribution of RWC as a range of values, being the minimum determined by factor 2 and the possible maximum as the contributions of both factors 2 and 3. A multiple linear regression (MLR) of observed PM10, PM1, total particle number, and MLAC concentrations is carried out to determine the source contribution to these aerosol variables. The results reveal RWC is an important source of atmospheric particles in the size range 25–606 nm (44–57%), PM10 (36–82%), PM1 (31–83%), and MLAC (40–76%) mass concentrations in the winter season. The contribution from RWC is especially large on weekends between 18:00 LT and midnight whereas local traffic emissions show similar contributions every day.
7
Krecl, P., E. Hedberg Larsson, J. Ström y C. Johansson. "Contribution of residential wood combustion and other sources to hourly winter aerosol in Northern Sweden determined by positive matrix factorization". Atmospheric Chemistry and Physics 8, n.º 13 (10 de julio de 2008): 3639–53. http://dx.doi.org/10.5194/acp-8-3639-2008.
Texto completoResumen
Abstract. The combined effect of residential wood combustion (RWC) emissions with stable atmospheric conditions, which frequently occurs in Northern Sweden during wintertime, can deteriorate the air quality even in small towns. To estimate the contribution of RWC to the total atmospheric aerosol loading, positive matrix factorization (PMF) was applied to hourly mean particle number size distributions measured in a residential area in Lycksele during winter 2005/2006. The sources were identified based on the particle number size distribution profiles of the PMF factors, the diurnal contributions patterns estimated by PMF for both weekends and weekdays, and correlation of the modeled particle number concentration per factor with measured aerosol mass concentrations (PM10, PM1, and light-absorbing carbon MLAC) Through these analyses, the factors were identified as local traffic (factor 1), local RWC (factor 2), and local RWC plus long-range transport (LRT) of aerosols (factor 3). In some occasions, the PMF model could not separate the contributions of local RWC from background concentrations since their particle number size distributions partially overlapped. As a consequence, we report the contribution of RWC as a range of values, being the minimum determined by factor 2 and the possible maximum as the contributions of both factors 2 and 3. A multiple linear regression (MLR) of observed PM10, PM1, total particle number, and MLAC concentrations is carried out to determine the source contribution to these aerosol variables. The results reveal RWC is an important source of atmospheric particles in the size range 25–606 nm (44–57%), PM10 (36–82%), PM1 (31–83%), and MLAC (40–76%) mass concentrations in the winter season. The contribution from RWC is especially large on weekends between 18:00 LT and midnight whereas local traffic emissions show similar contributions every day.
8
Matthiessen, J. N. y M. J. Palmer. "Prediction of temperatures in cattle dung for estimating development times of coprophilous organisms". Bulletin of Entomological Research 78, n.º 2 (junio de 1988): 235–40. http://dx.doi.org/10.1017/s0007485300013006.
Texto completoResumen
AbstractIn studies in Western Australia, temperatures in air and one- and two-litre pads of cattle dung set out weekly and ranging from one to 20 days old were measured hourly for 438 days over all seasons, producing 1437 day x dung-pad observations. Daily maximum temperatures (and hence thermal accumulation) in cattle dung pads could not be accurately predicted using meteorological data alone. An accurate predictor of daily maximum dung temperature, using multiple regression analysis, required measurement of the following factors: maximum air temperature, hours of sunshine, rainfall, a seasonal factor (the day number derived from a linear interpolation of day number from day 0 at the winter solstice to day 182 at the preceding and following summer solstices) and a dung-pad age-specific intercept term, giving an equation that explained a 91·4% of the variation in maximum dung temperature. Daily maximum temperature in two-litre dung pads was 0·6°C cooler than in one-litre pads. Daily minimum dung temperature equalled minimum air temperature, and daily minimum dung temperatures occurred at 05.00 h and maximum temperatures at 14.00 h for one-litre and 14.30 h for two-litre pads. Thus, thermal summation in a dung pad above any threshold temperature can be computed using a skewed sine curve fitted to daily minimum air temperature and the calculated maximum dung temperature.
9
Lee, Jimin, Seoro Lee, Jiyeong Hong, Dongjun Lee, Joo Hyun Bae, Jae E. Yang, Jonggun Kim y Kyoung Jae Lim. "Evaluation of Rainfall Erosivity Factor Estimation Using Machine and Deep Learning Models". Water 13, n.º 3 (1 de febrero de 2021): 382. http://dx.doi.org/10.3390/w13030382.
Texto completoResumen
Rainfall erosivity factor (R-factor) is one of the Universal Soil Loss Equation (USLE) input parameters that account for impacts of rainfall intensity in estimating soil loss. Although many studies have calculated the R-factor using various empirical methods or the USLE method, these methods are time-consuming and require specialized knowledge for the user. The purpose of this study is to develop machine learning models to predict the R-factor faster and more accurately than the previous methods. For this, this study calculated R-factor using 1-min interval rainfall data for improved accuracy of the target value. First, the monthly R-factors were calculated using the USLE calculation method to identify the characteristics of monthly rainfall-runoff induced erosion. In turn, machine learning models were developed to predict the R-factor using the monthly R-factors calculated at 50 sites in Korea as target values. The machine learning algorithms used for this study were Decision Tree, K-Nearest Neighbors, Multilayer Perceptron, Random Forest, Gradient Boosting, eXtreme Gradient Boost, and Deep Neural Network. As a result of the validation with 20% randomly selected data, the Deep Neural Network (DNN), among seven models, showed the greatest prediction accuracy results. The DNN developed in this study was tested for six sites in Korea to demonstrate trained model performance with Nash–Sutcliffe Efficiency (NSE) and the coefficient of determination (R2) of 0.87. This means that our findings show that DNN can be efficiently used to estimate monthly R-factor at the desired site with much less effort and time with total monthly precipitation, maximum daily precipitation, and maximum hourly precipitation data. It will be used not only to calculate soil erosion risk but also to establish soil conservation plans and identify areas at risk of soil disasters by calculating rainfall erosivity factors.
10
Wu, Shiang-Jen, Keh-Chia Yeh, Chih-Hung Ho y Sheng-Hsueh Yang. "Modeling probabilistic lag time equation in a watershed based on uncertainties in rainfall, hydraulic and geographical factors". Hydrology Research 47, n.º 6 (29 de enero de 2016): 1116–41. http://dx.doi.org/10.2166/nh.2016.134.
Texto completoResumen
This study proposes a framework for developing a probabilistic lag time (PLT) equation by taking into account uncertainty factors, including the rainfall factor (i.e., the maximum rainfall intensity), the hydraulic factor (i.e., the roughness coefficient in the river), and the geometrical factors (the catchment area, the length, and the basin slope). The proposed PLT equation is established based on the lag time equation by means of the uncertainty and risk analysis, i.e., the advanced first-order and second-moment approach. Hourly rainfall data in the Bazhang River watershed are used in the model development and application. The results indicate that compared with observed lag times extracted from historical events, the observed ones are mostly located within the 95% confidence interval of the simulated lag times. In addition, the resulting underestimated risk from the PLT equation can reasonably represent the degree of the difference between the estimated lag time and observed lag time. Consequently, the proposed PLT equation not only estimates the lag time at specific locations along the river, but also provides a corresponding reliability.
11
Nakazono, Hayato, Okinari Dodo y Kinya Kataishi. "Effectiveness of reconstruction of water supply system from the economic viewpoint and affecting factors – case study of a city". Water Supply 12, n.º 6 (1 de octubre de 2012): 937–42. http://dx.doi.org/10.2166/ws.2012.070.
Texto completoResumen
To solve the issues of decreasing revenue of waterworks caused by population decline and increasing renewal cost caused by ageing facilities, it is necessary to strengthen the financial base of the waterworks by undertaking efficient reconstruction of water supply system, and the cost of future renewal demands and anti-seismic upgrading need to be reduced. This paper evaluates the effectiveness of the reconstruction of water supply system from the economic viewpoint and identifies affecting factors. Assessments show it is more effective to terminate 60% of plants. The following factors were taken into account; intake water amount, length of conveyance pipe, diameter of conveyance pipe, difference in elevation between the abolished and integrated plants, and ratio of hourly maximum amount of water distribution, treatment capacity ratio, the anti-seismic capacity of abolished plants. Out of these factors, the intake water amount from abolished plant to merged plant has the highest correlated factor affecting the reconstruction of water supply system from the economic viewpoint.
12
Rashid, Fayaz. "Analysis and Determination of Axle Load Spectra and Traffic Input for Pavement Design". International Journal for Research in Applied Science and Engineering Technology 9, n.º 8 (31 de agosto de 2021): 2536–42. http://dx.doi.org/10.22214/ijraset.2021.3761.
Texto completoResumen
Abstract: This study examines the vehicle class distribution, hourly distribution factors, weekly distribution factors, monthly distribution factors, axle load spectra for each vehicle class, and each axle of each vehicle class for the WIM station installed on the N-55 highway to aid analysis and design of new Mechanistic-Empirical Pavement Design Guide. The maximum, minimum and permissible load limit for the different vehicle class, average gross vehicle weight (GWV) and permissible load limits also being incorporated. The directional distribution for north bound and south bound traffic were observed to be almost 50% for both directions, except for 5 axle trucks which was 74% for north bound and 26% for south bound. The truck class most prevalent on the highway were identified to be 3-axle tandem truck (47.50%) and also it was observed that 94.1% of this vehicle class carried load above permissible limits. Keywords: Traffic characteristics, Load distribution factor, Axle Load Spectra.
13
Liu, Gin-Rong, Chun-Chieh Chao y Czu-Yi Ho. "Applying Satellite-Estimated Storm Rotation Speed to Improve Typhoon Rainfall Potential Technique". Weather and Forecasting 23, n.º 2 (1 de abril de 2008): 259–69. http://dx.doi.org/10.1175/2007waf2006101.1.
Texto completoResumen
Abstract Heavy rainfall from typhoons or tropical cyclones often causes inland flooding and mudslides that threaten lives and property. In this study, Special Sensor Microwave Imager (SSM/I) satellite data observed from 2000 to 2004 were used to calculate the rainfall rates of different typhoons in the northwestern Pacific. Geostationary weather satellite infrared images were also applied to estimate the typhoon rotation speed via the maximum cross-correlation technique. By including such information in the tropical rainfall potential (TRaP) technique, an improved typhoon rainfall potential technique can be constructed. Considering the fact that a typhoon’s spiral rainbands move constantly, half-hourly or hourly infrared data observed from geostationary weather satellites were used to calculate the revolving speed, which was subsequently used to predict the rainband movement over the next hour. After comparing the predicted rainfall potential with the rain gauge data of Taiwan’s small offshore islands, it was found that this new method can improve the typhoon’s accumulated rainfall by approximately 40% over the original TRaP method. Therefore, to produce a more accurate short-term typhoon rainfall forecast, it is very important to factor in the satellite-estimated storm rotation speed.
14
Zoltowska, Izabela y Jeremy Lin. "Optimal Charging Schedule Planning for Electric Buses Using Aggregated Day-Ahead Auction Bids". Energies 14, n.º 16 (4 de agosto de 2021): 4727. http://dx.doi.org/10.3390/en14164727.
Texto completoResumen
This study aims to plan a cost-minimizing charging schedule for electric buses with fast charging stations. The paper conceptualizes the problem as a three-stage procedure, which is oriented around the participation of an electric bus aggregator in a day-ahead energy auction. First, the aggregation stage determines the bid parameters of buses. With bid parameters, aggregated cost-minimizing charging plans are obtained in the second stage conceived as the hourly day-ahead auction. The disaggregation of hourly plans into feasible minutely charging schedules is the third stage. The main contribution is the formulation of mixed-integer linear programming aggregation models to determine charging availability expressed as minimum and maximum hourly energy requirements taking into account detailed, minutely characteristics and constraints of the charging equipment and the buses. No price forecasts are required, and the plans adjust to the wholesale prices of energy. Defining only a few aggregated bids parameters used in linear programming constraints and incorporating them into the auction model is another contributing factor of this paper, allowing the scheduling of storage-based participants economically. The proposed methodology has been verified on a recently published case study of a real-world bus service operated on the Ohio State University campus. We show that the auction-based charging of all 22 buses outperforms as-soon-as-possible schedules by 7% to even 28% of daily cost savings. Thanks to the aggregated bids, buses can flexibly shift charges between high- and low-price periods while preserving constraints of the charging equipment and timetables.
15
Spławińska, Malwina. "DEVELOPMENT OF MODELS FOR DETERMINING THE TRAFFIC VOLUME FOR THE ANALYSIS OF ROADS EFFICIENCY". Archives of Transport 33, n.º 1 (31 de marzo de 2015): 81–91. http://dx.doi.org/10.5604/08669546.1160929.
Texto completoResumen
The article presents different methods of estimating DHV, including traditional Factor Approach, developed Regression Models and Artificial Neural Networks models. As explanatory variables: quantitative variables (AADT and the share of heavy vehicles) as well as qualitative variables (the cross-section, roads class, nature of the area, the profile of seasonal variations, region of Poland and the nature of traffic patterns) were used. In addition, the results of preliminary analyses of the DHV estimates based on the maximum hourly volume derived from a few hours traffic measurement on weekdays where there is the greatest share of hours with the highest traffic volume in the year were presented. On the basis of comparisons of the presented methods, Multiple Regression Model was identified as the most useful.
16
Kanabkaew, Thongchai, Nirattisai Rakmak y Sukonta Choosaeng. "Assessment of Hydrogen Sulfide Dispersion from Dumpsite Using AERMOD Modeling System". Advanced Materials Research 931-932 (mayo de 2014): 650–54. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.650.
Texto completoResumen
Hydrogen sulfide (H2S) isclassified as toxic gases that are commonly known to be generated from an anaerobic process, volcanic explosion and petroleum related processes. Low concentration of H2S causes irritation on human eyes and respiratory system as well as nuisance problem due to its rotten-egg smell. Insanitary dumpsite of municipal wastes containing high organic fraction could be a source of H2S emission, which affects the quality of life of nearby communities. This study assessed the H2S dispersion from dumpsite in Nakhon Si Thammarat using the source dispersion model, AERMOD. Emission rate of H2S generated at dumpsite was estimated using emission factor of 1.76 mg.m-2.d-1 taken from AP-42 (USEPA.). For meteorological data, hourly average data in 2012 were collected from three meteorological stations which were Nakhon Si Thammarat, Surat Thani and Trang Provinces. Meteorological data were primarily utilized from Nakhon Si Thammarat. Only missing values were filled by the data from Surat Thani and Trang, respectively. Results revealed that maximum concentrations of H2S in 2012 were 0.595, 0.066 and 0.058 ppb, respectively for 1 hour average (1st highest), 24 hour average (1st highest) and annual average over the study area of 10 km x 10 km surrounding the source. Maximum concentration of H2S emitted from dumpsite was mainly confined within 1.5 km surrounding the sources, particularly to the east and northeast area. The simulated concentrations of H2S did not exceed the suggested standard values; however, the 1st highest hourly average concentration was reached the odor threshold (0.5 ppb). To clarify the simulated H2S concentrations, further works should be included the field sampling of H2S at dumpsite to obtain the actual emission rate. Meteorological data in several years should be also used to provide the concrete pattern of H2S dispersion.
17
Rossa, A. M., G. Cenzon y M. Monai. "Quantitative comparison of radar QPE to rain gauges for the 26 September 2007 Venice Mestre flood". Natural Hazards and Earth System Sciences 10, n.º 2 (23 de febrero de 2010): 371–77. http://dx.doi.org/10.5194/nhess-10-371-2010.
Texto completoResumen
Abstract. In this study consideration is given to the potential use of radar-derived quantitative precipitation estimates (QPE) as flash flood guidance in the context of the Italian Civil Protection flood risk management system. The interest in high precipitation intensities and accumulation motivated the case study of the 26 September 2007 event, in which a quasi-stationary mesoscale convective system brought within 3–6 h 40% of the mean annual precipitation to the wider Venice-Mestre area, i.e. 260 mm in Venice-Mestre and 325 mm in closeby Valle Averto. Comparison of the radar-derived QPE in the area with the rain gauge network revealed a good correspondence for warm season rainfall, both for daily accumulations in the longterm (about 2 years) and hourly accumulations for the case under consideration. The long term average radar to gauge ratio is very close to 0 dB with an uncertainty of approximately ±3 dB, i.e. roughly a factor of two, slightly better for higher precipitation intensities. For the hourly accumulations during this very intense event the spread is similar, while the average is slightly positive. The locations of the rainfall accumulation maximum as detected, respectively, by the radar and by the rain gauge network do not coincide. Given the relatively good quality of the precipitation estimation, it is argued that these areas effectively have received even larger rainfall amounts, and that it is worthwhile to further investigate the potential of radar to be used as flash flood guidance.
18
Liu, C. W. y Y. K. Chuah. "The Effects of Capacity Coupling and Wet Air Return on the Energy Performance of Chiller-Cooling Tower Systems". Journal of Mechanics 27, n.º 4 (diciembre de 2011): N25—N31. http://dx.doi.org/10.1017/jmech.2011.64.
Texto completoResumen
ABSTRACTThis study uses a novel concept of capacity coupling of chiller-cooling tower system to investigate the system energy performance. System performance factor (SPF) of the chiller-cooling tower system is used in the analysis. A regression function is obtained for hourly reset of condensing water temperature so to achieve maximum SPF. The regression function includes parameters such as ambient wet bulb temperature, chiller load ratio, tower capacity ratio, and a dimensionless relative efficiency of chiller and cooling tower. The regression function has an R2 close to 1 compared to the computed results. It is found that for capacity coupling ratio of 1.1 ∼ 1.6, SPF would increase by about 3 ∼ 6% compared with a typical base control. The effect of wet air return is presented as an equivalent wet bulb temperature. It has been found that SPF would decrease significantly when higher equivalent wet bulb temperature occurs at the tower inlet.
19
Walker, G. O., J. H. K. Ma y E. Golton. "The equatorial ionospheric anomaly in electron content from solar minimum to solar maximum for South East Asia". Annales Geophysicae 12, n.º 2/3 (31 de enero de 1994): 195–209. http://dx.doi.org/10.1007/s00585-994-0195-0.
Texto completoResumen
Abstract. Median hourly, electron content-latitude profiles obtained in South East Asia under solar minimum and maximum conditions have been used to establish seasonal and solar differences in the diurnal variations of the ionospheric equatorial anomaly (EIA). The seasonal changes have been mainly accounted for from a consideration of the daytime meridional wind, affecting the EIA diffusion of ionization from the magnetic equator down the magnetic field lines towards the crests. Depending upon the seasonal location of the subsolar point in relation to the magnetic equator diffusion rates were increased or decreased. This led to crest asymmetries at the solstices with (1) the winter crest enhanced in the morning (increased diffusion rate) and (2) the same crest decaying most rapidly in the late afternoon (faster recombination rate at lower ionospheric levels). Such asymmetries were also observed, to a lesser extent, at the equinoxes since the magnetic equator (located at about 9°N lat) does not coincide with the geographic equator. Another factor affecting the magnitude of a particular electron content crest was the proximity of the subsolar point, since this increased the local ionization production rate. Enhancements of the EIA took place around sunset, mainly during the equinoxes and more frequently at solar maximum, and also there was evidence of apparent EIA crest resurgences around 0300 LST for all seasons at solar maximum. The latter are thought to be associated with the commonly observed, post-midnight, ionization enhancements at midlatitudes, ionization being transported to low latitudes by an equatorward wind. The ratio increases in crest peak electron contents from solar minimum to maximum of 2.7 at the equinoxes, 2.0 at the northern summer solstice and 1.7 at northern winter solstice can be explained, only partly, by increases in the magnitude of the eastward electric field E overhead the magnetic equator affecting the [E×B] vertical drifts. The most important factor is the corresponding increase in ionization production rate due to the increase in solar radiation flux. The EIA crest asymmetries observed at solar maximum were less significant, and this is probably due to the corresponding increase in ionization densities leading to an increase of the retarding effect of ion-drag on the daytime meridional winds.
20
Messaci, Mourad. "Meteodiffusive Characterization of Algiers' Nuclear Research Reactor". Science and Technology of Nuclear Installations 2007 (2007): 1–6. http://dx.doi.org/10.1155/2007/95469.
Texto completoResumen
In the framework of the environmental impact studies of the nuclear research reactor of Algiers, we will present the work related to the atmospheric dispersion of releases due to the installation in normal operation, which dealt with the assessment of spatial distribution of yearly average values of atmospheric dilution factor. The aim of this work is a characterization of the site in terms of diffusivity, which is basic for the radiological impact evaluation of the reactor. The meteorological statistics result from the National Office of Meteorology and concern 15 years of hourly records. According to the nature and features of these data, a Gaussian-type model with wind direction sectors was used. Values of wind speed at release height were estimated from measurement values at 10 m from ground. For the assessment of vertical dispersion coefficient, we used Briggs' formulas related to a sampling time of one hour. Areas of maximum impact were delimited and points of highest concentration within these zones were identified.
21
Zhou, Zehui, Bin Yong, Jiufu Liu, Aimin Liao, Niu Wang, Ziwei Zhu, Dekai Lu, Wang Li y Jianyun Zhang. "Preliminary Evaluation of the HOBO Data Logging Rain Gauge at the Chuzhou Hydrological Experiment Station, China". Advances in Meteorology 2019 (4 de noviembre de 2019): 1–10. http://dx.doi.org/10.1155/2019/5947976.
Texto completoResumen
As a tipping bucket rain gauge, the HOBO Data Logging Rain Gauge RG3-M (RG3-M) has been widely used for the field precipitation observation owing to its superiority of independent power supply by a small portable battery. To quantify the measurement accuracy of the RG3-M gauge, a standard Manual Gauge (MG) and eight other models of tipping bucket rain gauges were installed at the Chuzhou hydrological experiment station of China. In this study, we first compared and investigated the accumulated mounts of 18 rainfall events of two RG3-M gauges benchmarked by the standard MG. Then, five typical rainfall events were chosen to further analyse the observed accuracy of the RG3-M gauge for different rainfall intensities at hourly temporal scale. Finally, the impacts of wind speed and rainfall intensity on the precipitation measurements of the RG3-M gauge were preliminarily explored. Results indicate that the RG3-M gauge measurement generally underestimates rainfall approximately −4% against the standard MG observation, but the maximum deviation even reaches −12.87%. In terms of the hourly rainfall process, the reliable measurement scope of the RG3-M gauge is ranging from 1.5 to 3 mm/h; however, it should be noted that the underestimation is rather significant at the higher rainfall rates (>6 mm/h). Last, it was found that rainfall intensity is a nonnegligible factor for influencing the measurement of the RG3-M gauge. But the windy effect seems to be insignificant in our experiments, which might be attributed to the similar exposure of the compared gauges.
22
Mueller, Stephen F., Jonathan W. Mallard, Qi Mao y Stephanie L. Shaw. "Variability of Natural Dust Erosion from a Coal Pile". Journal of Applied Meteorology and Climatology 54, n.º 1 (enero de 2015): 3–14. http://dx.doi.org/10.1175/jamc-d-14-0126.1.
Texto completoResumen
AbstractA study of fugitive dust emissions from a pile of crushed coal revealed that, in addition to dust being emitted into the atmosphere during periods of pile-management (human) activity, it is also emitted during periods without human activity. This “natural” emission in itself is not surprising given past work on wind erosion of particulate matter from aggregate piles. However, hourly downwind measurements of fine particle (PM10) mass concentrations at two sites revealed that excessive dust was present in the air even when wind speeds were below the erosion threshold estimated from nearby wind speed measurements and regulatory guidance on coal pile aerodynamic characteristics. During periods of natural emissions with higher wind speeds, downwind concentrations were strongly associated with µ2—the squared excess of 1-min maximum wind speed above the erosion threshold—consistent with previous work on wind erosion potential. However, 88% of hourly concentrations coincided with lower winds for which wind speed was not a good predictor of airborne dust levels. Evidence was found that natural low-wind PM10 concentrations varied significantly with relative humidity, air temperature, and turbulence parameters (σu and σw). Smoke from coal combustion was ruled out as a significant factor in PM10 levels, but statistical evidence along with visual observation suggests that microscale turbulent airflows, including dust devils, were a significant source of PM10 during low wind speeds over the pile. The localized behavior of the turbulence makes it very difficult to develop a strong statistical model of natural downwind concentrations on the basis of off-pile meteorological measurements.
23
Taylan, Gozde, Onur Taylan y Murat Fahrioglu. "Comparison of Middle-Sized PTC and PV Power Plants for METU NCC". World Journal of Environmental Research 8, n.º 2 (31 de diciembre de 2018): 53–59. http://dx.doi.org/10.18844/wjer.v8i2.4126.
Texto completoResumen
Since usage of fossil fuels for producing electricity causes climate change, renewable energy options have become one of the best substitution for fossil fuels. Solar energy promises high amount of resources for producing electricity. Among solar energy alternatives, Photovoltaic (PV) and Parabolic Trough Collectors (PTC) are dominant in the market. This paper compares middle size of PV and PTC power plant for the electricity need of Middle East Technical University Northern Cyprus Campus. Based on the maximum hourly demand of METU NCC, both PV and PTC are sized to 3 MWe. The simulations were performed via SAM software using the hourly values from typical meteorological data, which include solar irradiation, wind speed, dry and wet bulb temperatures, relative humidity and pressure. For the PTC and PV plants, commercially available components are used. The scenario assumes METU NCC to be a grid-connected micro-grid with one-way tariff, so that any deficit energy can be met by the utility and any excess energy produced by the suggested renewable energy systems will be given to the grid for free. The results indicate that 3 MW PV plant would generate annual energy of about 4.95 GWh with a capacity factor of 18.9%. These numbers would yield to a LCOE value of 2.60 ¢/kWh. On the other hand, the suggested 3 MW PTC plant with 2 solar multiple would supply about annual energy of 6.3 GWh at a capacity factor of 24.0%. The LCOE of the energy from PTC plant was estimated to be 8.47 ¢/kWh due to high capital and operation cost of PTC plants compared to PV plants. However, over years the cost of PTC power plants has been decreasing. Additionally, both PTC plant and PV plant would consume water only for cleaning purposes that makes them suitable for Cyprus water scarcity conditions. Overall, this study shows pros and cons of middle-sized PV and PTC plants with the case study of METU NCC.
Keywords: economic comparison, levelized cost of energy, parabolic trough, photovoltaic, renewable energy, solar energy
24
Conrad, Jochen y Simon Greif. "Modelling Load Profiles of Heat Pumps". Energies 12, n.º 4 (25 de febrero de 2019): 766. http://dx.doi.org/10.3390/en12040766.
Texto completoResumen
Approximately one quarter of energy-related emissions in Germany are caused by the domestic sector. At 81%, the largest share of these emissions is due to heat supply. Many measures are available to reduce these emissions. One of these measures, which is considered to play an important role in many studies, is the replacement of fossil-fired boilers with electric heat pumps. In order to be able to analyse the impact of high penetrations of heat pumps on the energy system, the coefficient of performance (COP) must be modelled with high temporal resolution. In this study, a methodology is presented on how to calculate high-resolution COPs and the electrical load of heat pumps based on thermal load curves and temperature time series. The COP is determined by the reciprocal Carnot factor. Since heat pumps are often designed bivalently due to the cost structure, the methodology described can also be used for evaluating the combination of immersion heater and heat pump (here for the air/water heat pump). As a result the theoretical hourly COPs determined are calibrated with annual performance factors from field tests. The modelled COPs show clear differences. Currently, mostly air source heat pumps are installed in Germany. If this trend continues, the maximum electrical load of the heat supply will increase more than would be the case with higher shares of ground source heat pumps.
25
Koopmans, Sytse, Reinder Ronda, Gert-Jan Steeneveld, Albert Holtslag y Albert Klein Tank. "Quantifying the Effect of Different Urban Planning Strategies on Heat Stress for Current and Future Climates in the Agglomeration of The Hague (The Netherlands)". Atmosphere 9, n.º 9 (13 de septiembre de 2018): 353. http://dx.doi.org/10.3390/atmos9090353.
Texto completoResumen
In the Netherlands, there will be an urgent need for additional housing by the year 2040, which mainly has to be realized within the existing built environment rather than in the spatial extension of cities. In this data-driven study, we investigated the effects of different urban planning strategies on heat stress for the current climate and future climate scenarios (year 2050) for the urban agglomeration of The Hague. Heat stress is here expressed as the number of days exceeding minimum temperatures of 20 °C in a year. Thereto, we applied a diagnostic equation to determine the daily maximum urban heat island based on routine meteorological observations and straightforward urban morphological properties including the sky-view factor and the vegetation fraction. Moreover, we utilized the Royal Netherlands Meteorological Institute’s (KNMI) climate scenarios to transform present-day meteorological hourly time series into the future time series. The urban planning strategies differ in replacing low- and mid-rise buildings with high-rise buildings (which reduces the sky-view factor), and constructing buildings on green areas (which reduces the vegetation fraction). We found that, in most cases, the vegetation fraction is a more critical parameter than the sky-view factor to minimize the extra heat stress incurred when densifying the neighbourhood. This means that an urban planning strategy consisting of high-rise buildings and preserved green areas is often the best solution. Still, climate change will have a larger impact on heat stress for the year 2050 than the imposed urban densification.
26
Schmidt, Simon, Christine Alewell, Panos Panagos y Katrin Meusburger. "Regionalization of monthly rainfall erosivity patterns in Switzerland". Hydrology and Earth System Sciences 20, n.º 10 (26 de octubre de 2016): 4359–73. http://dx.doi.org/10.5194/hess-20-4359-2016.
Texto completoResumen
Abstract. One major controlling factor of water erosion is rainfall erosivity, which is quantified as the product of total storm energy and a maximum 30 min intensity (I30). Rainfall erosivity is often expressed as R-factor in soil erosion risk models like the Universal Soil Loss Equation (USLE) and its revised version (RUSLE). As rainfall erosivity is closely correlated with rainfall amount and intensity, the rainfall erosivity of Switzerland can be expected to have a regional characteristic and seasonal dynamic throughout the year. This intra-annual variability was mapped by a monthly modeling approach to assess simultaneously spatial and monthly patterns of rainfall erosivity. So far only national seasonal means and regional annual means exist for Switzerland. We used a network of 87 precipitation gauging stations with a 10 min temporal resolution to calculate long-term monthly mean R-factors. Stepwise generalized linear regression (GLM) and leave-one-out cross-validation (LOOCV) were used to select spatial covariates which explain the spatial and temporal patterns of the R-factor for each month across Switzerland. The monthly R-factor is mapped by summarizing the predicted R-factor of the regression equation and the corresponding residues of the regression, which are interpolated by ordinary kriging (regression–kriging). As spatial covariates, a variety of precipitation indicator data has been included such as snow depths, a combination product of hourly precipitation measurements and radar observations (CombiPrecip), daily Alpine precipitation (EURO4M-APGD), and monthly precipitation sums (RhiresM). Topographic parameters (elevation, slope) were also significant explanatory variables for single months. The comparison of the 12 monthly rainfall erosivity maps showed a distinct seasonality with the highest rainfall erosivity in summer (June, July, and August) influenced by intense rainfall events. Winter months have the lowest rainfall erosivity. A proportion of 62 % of the total annual rainfall erosivity is identified within four months only (June–September). The highest erosion risk can be expected in July, where not only rainfall erosivity but also erosivity density is high. In addition to the intra-annual temporal regime, a spatial variability of this seasonality was detectable between different regions of Switzerland. The assessment of the dynamic behavior of the R-factor is valuable for the identification of susceptible seasons and regions.
27
Gaevskii, A. y D. Diomin. "INFLUENCE OF SOLAR PANELS TILT ANGLE AND GROUND COVER RATIO ON PV PLANT PERFORMANCE". Alternative Energy and Ecology (ISJAEE), n.º 25-30 (7 de diciembre de 2018): 12–24. http://dx.doi.org/10.15518/isjaee.2018.25-30.012-024.
Texto completoResumen
One of the main factors affecting the photovoltaic (PV) plant power is the self-shading from adjacent rows of solar panels. Due to the peculiarities of the electric connections of photovoltaic cells in PV modules and the presence of bypass diodes, the partial shading is capable of significantly decreasing the PV plant power at certain times of the day. The partial shading of solar panels effects in different ways on the energy production in cases of the vertical placement of PV modules in the panel’s frame (portrait mounting) and the horizontal placement of PV modules (landscape mounting). This work presents a novel analytical approach for determining of the inter-row shading effect on the large PV plant efficiency which is applicable for any seasonal period of PV operation. The initial data for calculations are the hourly generation of shaded and fully illuminated solar panels. On the base of these data, we have calculated the power factor that describes the dependence of the module's electrical power on the shading degree. The power factor is used to determine the amount of radiation entering the panel’s tilted surface during each day of the operation period. The long-term meteorological data for the main radiation components and one of the known anisotropic radiation model are necessary for these calculations. The main calculations result is the distribution maps for the average daily energy output which first proposed in our work. These maps have the form of contour graphs which build in the coordinates “the ground cover ratio – the tilt angle” as construction parameters. Using this maps one can find the optimal ratios of these parameters for two types of optimization problems: (1) ensure the maximum possible output under given installed PV power and (2) the determination of the most rational use of a land plot for PV plant, i.e. the obtaining of maximum PV production per unit of land area. The advantage of the analytical approach is that it allows scaling to large PV systems without increasing the computation time. As examples, the paper performs the optimization calculations based on the monitoring output data for the commercial PV plant located in Germany and on the experimental partial shading data in Odessa region.
28
Springmann, M., D. A. Knopf y N. Riemer. "Detailed heterogeneous chemistry in an urban plume box model: reversible co-adsorption of O<sub>3</sub>, NO<sub>2</sub>, and H<sub>2</sub>O on soot coated with benzo[a]pyrene". Atmospheric Chemistry and Physics 9, n.º 19 (7 de octubre de 2009): 7461–79. http://dx.doi.org/10.5194/acp-9-7461-2009.
Texto completoResumen
Abstract. This study assesses in detail the effects of heterogeneous chemistry on the particle surface and gas-phase composition by modeling the reversible co-adsorption of O3, NO2, and H2O on soot coated with benzo[a]pyrene (BaP) for an urban plume scenario over a period of five days. By coupling the Pöschl-Rudich-Ammann (PRA) kinetic framework for aerosols (Pöschl et al., 2007) to a box model version of the gas phase mechanism RADM2, we are able to track individual concentrations of gas-phase and surface species over the course of several days. The flux-based PRA formulation takes into account changes in the uptake kinetics due to changes in the chemical gas-phase and particle surface compositions. This dynamic uptake coefficient approach is employed for the first time in a broader atmospheric context of an urban plume scenario. Our model scenarios include one to three adsorbents and three to five coupled surface reactions. The results show a variation of the O3 and NO2 uptake coefficients of more than five orders of magnitude over the course of the simulation time and a decrease in the uptake coefficients in the various scenarios by more than three orders of magnitude within the first six hours. Thereafter, periodic peaks of the uptake coefficients follow the diurnal cycle of gas-phase O3-NOx reactions. Physisorption of water vapor reduces the half-life of the coating substance BaP by up to a factor of seven by permanently occupying ~75% of the soot surface. Soot emissions modeled by replenishing reactive surface sites lead to maximum gas-phase O3 depletions of 41 ppbv and 7.8 ppbv for an hourly and six-hourly replenishment cycle, respectively. This conceptual study highlights the interdependence of co-adsorbing species and their non-linear gas-phase feedback. It yields further insight into the atmospheric importance of the chemical oxidation of particles and emphasizes the necessity to implement detailed heterogeneous kinetics in future modeling studies.
29
Springmann, M., D. A. Knopf y N. Riemer. "Detailed heterogeneous chemistry in an urban plume box model: reversible co-adsorption of O<sub>3</sub>, NO<sub>2</sub>, and H<sub>2</sub>O on soot coated with benzo[a]pyrene". Atmospheric Chemistry and Physics Discussions 9, n.º 2 (20 de abril de 2009): 10055–99. http://dx.doi.org/10.5194/acpd-9-10055-2009.
Texto completoResumen
Abstract. This study assesses in detail the effects of heterogeneous chemistry on the particle surface and gas-phase composition by modeling the reversible co-adsorption of O3, NO2, and H2O on soot coated with benzo[a]pyrene (BaP) for an urban plume scenario over a period of five days. By coupling the Pöschl-Rudich-Ammann (PRA) kinetic framework for aerosols (Pöschl et al., 2007) to a box model version of the gas phase mechanism RADM2, we are able to track individual concentrations of gas-phase and surface species over the course of several days. The flux-based PRA formulation takes into account changes in the uptake kinetics due to changes in the chemical gas-phase and particle surface compositions. This dynamic uptake coefficient approach is employed for the first time in a broader atmospheric context of an urban plume scenario. Our model scenarios include one to three adsorbents and three to five coupled surface reactions. The results show a variation of the O3 and NO2 uptake coefficients of more than five orders of magnitude over the course of simulation time and a decrease in the uptake coefficients in the various scenarios by more than three orders of magnitude within the first six hours. Thereafter, periodic peaks of the uptake coefficients follow the diurnal cycle of gas-phase O3-NOx reactions. Physisorption of water vapor delays the half-life of the coating substance BaP by up to a factor of seven by permanently occupying ~75% of the soot surface. Soot emissions modeled by replenishing reactive surface sites lead to maximum gas-phase O3 depletions of 41 ppbv for an hourly and 7.8 ppbv for a six-hourly replenishment cycle. This conceptual study highlights the interdependence of co-adsorbing species and their non-linear gas-phase feedback. It yields further insight into the atmospheric importance of the chemical oxidation of particles and guides future modeling and experimental investigations of the heterogeneous chemistry and chemical aging of aerosols.
30
Carreno-Madinabeitia, Sheila, Gabriel Ibarra-Berastegi, Jon Sáenz, Eduardo Zorita y Alain Ulazia. "Sensitivity Studies for a Hybrid Numerical–Statistical Short-Term Wind and Gust Forecast at Three Locations in the Basque Country (Spain)". Atmosphere 11, n.º 1 (29 de diciembre de 2019): 45. http://dx.doi.org/10.3390/atmos11010045.
Texto completoResumen
This study evaluates the performance of statistical models applied to the output of numerical models for short-term (1–24 h) hourly wind forecasts at three locations in the Basque Country. The target variables are horizontal wind components and the maximum wind gust at 3 h intervals. Statistical approaches such as persistence, analogues, linear regression, and random forest (RF) are used. The verification statistics used are coefficient of determination (R2) and root mean square error (RMSE). Statistical models use three inputs: (1) Local wind observations; (2) extended EOFs (empirical orthogonal functions) derived from past local observations and ERA-Interim variables in a previous 24-h period covering a domain around the area of study; and (3) wind forecasts provided by ERA-Interim. Results indicate that, for horizons less than 1–4 h, persistence is the best model. For longer predictions, RF provides the best forecasts. For horizontal components at 4–24 h horizons, RF slightly outperformed ERA-Interim wind forecasts. For gust, RF performs better than ERA-Interim for all the horizons. Persistence is the most influential factor for 2–5 h. Beyond this horizon, predictors from the ERA-Interim wind forecasts led the contribution. Hybrid numerical–statistical methods can be used to improve short-term wind forecasts.
31
Mäki, Aleksi, Juha Jokisalo y Risto Kosonen. "Demand response of space heating using model predictive control in an educational office building". E3S Web of Conferences 111 (2019): 03067. http://dx.doi.org/10.1051/e3sconf/201911103067.
Texto completoResumen
The building sector plays a remarkable role in decreasing of the overall global CO2 emissions since as much as 30% from the total global CO2 emission are generated in buildings. Demand response provides one possibility to tackle the problem. It can be used to decrease CO2 emissions in entire energy system in addition to providing energy cost savings for building owners and energy companies. In this study, the demand response potential was estimated in an educational office building that was heated by district heating. The potential was defined in respect of energy cost savings, energy flexibility and thermal comfort. Model predictive control was developed, which utilized the dynamic hourly district heating prices. The MPC algorithm written in the Matlab software, predicted the future heating demand while the optimization algorithm NSGA-II minimized the heating energy cost, maximized the energy flexibility and maintained acceptable thermal comfort by changing the space heating temperature setpoints. The operation of the MPC algorithm was tested in the IDA ICE 4.8 simulation software. As a result, the annual district heating energy costs could be reduced by 4.2% compared to the reference case with constant space heating temperature setpoint of 21 °C. The maximum flexibility factor attained was 14%. Acceptable level of thermal comfort was maintained throughout the simulation time.
32
Langner, J., M. Engardt, A. Baklanov, J. H. Christensen, M. Gauss, C. Geels, G. B. Hedegaard et al. "A multi-model study of impacts of climate change on surface ozone in Europe". Atmospheric Chemistry and Physics 12, n.º 21 (8 de noviembre de 2012): 10423–40. http://dx.doi.org/10.5194/acp-12-10423-2012.
Texto completoResumen
Abstract. The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM), driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the results across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 2000–2009 and 2040–2049 differs by a factor of two between the models, but the general pattern of change with an increase in southern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr−1 for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in total isoprene emissions varies substantially across models explaining part of the different climate response on surface ozone. Ensemble mean changes in summer mean ozone and mean of daily maximum ozone are close to 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone are close to 2 ppb(v) in the same region. In northern Europe ensemble mean for mean and daily maximum show negative changes while there are no negative changes for the higher percentiles indicating that climate impacts on O3 could be especially important in connection with extreme summer events.
33
R. Maestre, Ismael, Juan Luis Foncubierta Blázquez, Francisco Javier González Gallero y J. Daniel Mena Baladés. "Effect of Sky Discretization for Shading Device Calculation on Building Energy Performance Simulations". Energies 13, n.º 6 (16 de marzo de 2020): 1381. http://dx.doi.org/10.3390/en13061381.
Texto completoResumen
The calculation of sunlit surfaces in a building has always been a relevant aspect in building energy simulation programs. Due to the high computational cost, some programs use algorithms for shading calculation for certain solar positions after discretization of hemispherical sky. The influence of the level of discretization on the estimation of incident direct radiation on building surfaces, as well as on the required computational times, are studied in this work. The direct solar energy on a window for a year, with simulation time steps of five minutes, has been simulated by using an algorithm based on Projection and Clipping Methods. A total of 6144 simulations have been carried out, varying window sizes, window orientations, typologies of shading devices, latitudes and discretization levels of the hemispherical sky. In terms of annual incident solar energy, the results show that maximum error values are about 5% for a low level of angular discretization. Errors up to 22% in hourly incident solar energy have been estimated for some of the configurations analysed. Furthermore, a great number of configurations show errors of shading factor on a window of up to 30%, which could be most relevant in studies of natural lighting. The study also shows that the improvement achieved by the most accurate discretization level implies an increase in computational cost of about 30 times.
34
Zarrillo, Marguerite L., A. Essam Radwan y Joseph H. Dowd. "Toll Network Capacity Calculator: Operations Management and Assessment Tool for Toll Network Operators". Transportation Research Record: Journal of the Transportation Research Board 1781, n.º 1 (enero de 2002): 49–55. http://dx.doi.org/10.3141/1781-07.
Texto completoResumen
A performance assessment tool was developed to assist managers and operators of highway networks containing toll collection facilities. The toll network capacity calculator (TNCC) quantifies a toll facility’s ability to process traffic. The calculator can also help engineers who are designing toll facilities to serve highway systems adequately. TNCC determines the maximum amount of traffic that a collection facility can handle. In addition, TNCC may be used for disruption management during lane closings, incidents, or maintenance checks. Furthermore, TNCC may be employed as a planning tool and a performance assessment tool by predicting the impact of surging traffic volumes during special events. The performance of a toll facility was determined from plaza characteristics such as lane number, lane type, and processing rates. The results of the calculations met constraints set by the characteristics of the arriving traffic. For example, variables such as the percentage of arrivals that were electronic toll collection (ETC) patrons and the percentage of arrivals that were semitrailer trucks requiring non-ETC services influenced the plazas’ performance outcome. Overflow of ETC users from the dedicated ETC lanes into the mixed lanes was also a factor. Performance was independent of hourly arrival volumes. Videotapes and transaction data at plazas provided necessary input to TNCC in the evaluation of 32 plazas on the toll network of highways in Orange County, Florida.
35
Rai, Pragati, Jay G. Slowik, Markus Furger, Imad El Haddad, Suzanne Visser, Yandong Tong, Atinderpal Singh et al. "Highly time-resolved measurements of element concentrations in PM<sub>10</sub> and PM<sub>2.5</sub>: comparison of Delhi, Beijing, London, and Krakow". Atmospheric Chemistry and Physics 21, n.º 2 (19 de enero de 2021): 717–30. http://dx.doi.org/10.5194/acp-21-717-2021.
Texto completoResumen
Abstract. We present highly time-resolved (30 to 120 min) measurements of size-fractionated (PM10 and PM2.5) elements in two cities in Asia (Delhi and Beijing) and Europe (Krakow and London). For most elements, the mean concentrations in PM10 and PM2.5 are higher in the Asian cities (up to 24 and 28 times, respectively) than in Krakow and often higher in Delhi than in Beijing. Among European cities, Krakow shows higher elemental concentrations (up to 20 and 27 times, respectively) than London. Hourly maximum concentrations of Pb and Zn reach up to 1 µg m−3 in Delhi, substantially higher than at the other sites. The enrichment factor of an element together with the size distribution allows for a rough classification of elements by major source. We define five groups: (1) dust emissions, (2) non-exhaust traffic emissions, (3) solid fuel combustion, (4) mixed traffic/industrial emissions, and (5) industrial/coal/waste burning emissions, with the last group exhibiting the most site-to-site variability. We demonstrate that the high time resolution and size-segregated elemental dataset can be a powerful tool to assess aerosol composition and sources in urban environments. Our results highlight the need to consider the size distributions of toxic elements, diurnal patterns of targeted emissions, and local vs. regional effects in formulating effective environmental policies to protect public health.
36
Panthou, Gérémy, Alain Mailhot, Edward Laurence y Guillaume Talbot. "Relationship between Surface Temperature and Extreme Rainfalls: A Multi-Time-Scale and Event-Based Analysis*". Journal of Hydrometeorology 15, n.º 5 (25 de septiembre de 2014): 1999–2011. http://dx.doi.org/10.1175/jhm-d-14-0020.1.
Texto completoResumen
Abstract Recent studies have examined the relationship between the intensity of extreme rainfall and temperature. Two main reasons justify this interest. First, the moisture-holding capacity of the atmosphere is governed by the Clausius–Clapeyron (CC) equation. Second, the temperature dependence of extreme-intensity rainfalls should follow a similar relationship assuming relative humidity remains constant and extreme rainfalls are driven by the actual water content of the atmosphere. The relationship between extreme rainfall intensity and air temperature (Pextr–Ta) was assessed by analyzing maximum daily rainfall intensities for durations ranging from 5 min to 12 h for more than 100 meteorological stations across Canada. Different factors that could influence this relationship have been analyzed. It appears that the duration and the climatic region have a strong influence on this relationship. For short durations, the Pextr–Ta relationship is close to the CC scaling for coastal regions while a super-CC scaling followed by an upper limit is observed for inland regions. As the duration increases, the slope of the relationship Pextr–Ta decreases for all regions. The shape of the Pextr–Ta curve is not sensitive to the percentile or season. Complementary analyses have been carried out to understand the departures from the expected Clausius–Clapeyron scaling. The relationship between dewpoint temperature and extreme rainfall intensity shows that the relative humidity is a limiting factor for inland regions, but not for coastal regions. Using hourly rainfall series, an event-based analysis is proposed in order to understand other deviations (super-CC, sub-CC, and monotonic decrease). The analyses suggest that the observed scaling is primarily due to the rainfall event dynamic.
37
Tizgui, Ijjou, Fatima El Guezar, Hassane Bouzahir y Brahim Benaid. "Comparison of methods in estimating Weibull parameters for wind energy applications". International Journal of Energy Sector Management 11, n.º 4 (6 de noviembre de 2017): 650–63. http://dx.doi.org/10.1108/ijesm-06-2017-0002.
Texto completoResumen
Purpose The purpose of this study is to select the most accurate and the most efficient method in estimating Weibull parameters at Agadir region in Morocco. Design/methodology/approach In this paper, Weibull distribution is used to model the wind speed in hourly time series format. Since several methods are used to adjust the Weibull distribution to the measured data, in reporting and analyzing the easiest and the most effective method, seven methods have been investigated, namely, the graphical method (GM), the maximum likelihood method (MLM), the empirical method of Justus (EMJ), the empirical method of Lysen (EML), the energy pattern factor method (EPFM), Mabchour’s method (MMab) and the method of moments (MM). Findings According to the statistical analysis tools (the coefficient of determination, root mean square error and chi-square test), it was found that for five months, the MLM presents more efficiency, and for four months, EMJ is ranked first and it is ranked second for February. To select only one method, the selected methods (MLM and EMJ) were compared by calculating the error in estimating the power density using Weibull distribution adjusted by those methods. The average error was found to be −0.51 and −4.56 per cent for MLM and EMJ, respectively. Originality/value This investigation is the first of its kind for the studied region. To estimate the available wind power at Agadir in Morocco, investors can directly use MLM to determine the Weibull parameters at this site.
38
Jiang, Haiyan, Jeffrey B. Halverson y Joanne Simpson. "On the Differences in Storm Rainfall from Hurricanes Isidore and Lili. Part I: Satellite Observations and Rain Potential". Weather and Forecasting 23, n.º 1 (1 de febrero de 2008): 29–43. http://dx.doi.org/10.1175/2007waf2005096.1.
Texto completoResumen
Abstract It has been well known for years that the heavy rain and flooding of tropical cyclones over land bear a weak relationship to the maximum wind intensity. The rainfall accumulation history and rainfall potential history of two North Atlantic hurricanes during 2002 (Isidore and Lili) are examined using a multisatellite algorithm developed for use with the Tropical Rainfall Measuring Mission (TRMM) dataset. This algorithm uses many channel microwave data sources together with high-resolution infrared data from geosynchronous satellites and is called the real-time Multisatellite Precipitation Analysis (MPA-RT). MPA-RT rainfall estimates during the landfalls of these two storms are compared with the combined U.S. Next-Generation Doppler Radar (NEXRAD) and gauge dataset: the National Centers for Environmental Prediction (NCEP) hourly stage IV multisensor precipitation estimate analysis. Isidore produced a much larger storm total volumetric rainfall as a greatly weakened tropical storm than did category 1 Hurricane Lili during landfall over the same area. However, Isidore had a history of producing a large amount of volumetric rain over the open gulf. Average rainfall potential during the 4 days before landfall for Isidore was over a factor of 2.5 higher than that for Lili. When using the TRMM-based MPA-RT rainfall estimate, results are consistent with a previous study, which analyzed just the infrared-based rain estimation; that is, the rain potential history could be used as a predictor for the storm’s potential for inland flooding 3–4 days in advance of landfall.
39
Bouramdane, Ayat-allah, Alexis Tantet y Philippe Drobinski. "Adequacy of Renewable Energy Mixes with Concentrated Solar Power and Photovoltaic in Morocco: Impact of Thermal Storage and Cost". Energies 13, n.º 19 (29 de septiembre de 2020): 5087. http://dx.doi.org/10.3390/en13195087.
Texto completoResumen
In this paper, we analyze the sensitivity of the optimal mixes to cost and variability associated with solar technologies and examine the role of Thermal Energy Storage (TES) combined to Concentrated Solar Power (CSP) together with time-space complementarity in reducing the adequacy risk—imposed by variable Renewable Energies (RE)—on the Moroccan electricity system. To do that, we model the optimal recommissioning of RE mixes including Photovoltaic (PV), wind energy and CSP without or with increasing levels of TES. Our objective is to maximize the RE production at a given cost, but also to limit the variance of the RE production stemming from meteorological fluctuations. This mean-variance analysis is a bi-objective optimization problem that is implemented in the E4CLIM modeling platform—which allows us to use climate data to simulate hourly Capacity Factors (CFs) and demand profiles adjusted to observations. We adapt this software to Morocco and its four electrical zones for the year 2018, add new CSP and TES simulation modules, perform some load reduction diagnostics, and account for the different rental costs of the three RE technologies by adding a maximum-cost constraint. We find that the risk decreases with the addition of TES to CSP, the more so as storage is increased keeping the mean capacity factor fixed. On the other hand, due to the higher cost of CSP compared to PV and wind, the maximum-cost constraint prevents the increase of the RE penetration without reducing the share of CSP compared to PV and wind and letting the risk increase in return. Thus, if small level of risk and higher penetrations are targeted, investment must be increased to install more CSP with TES. We also show that regional diversification is key to reduce the risk and that technological diversification is relevant when installing both PV and CSP without storage, but less so as the surplus of energy available for TES is increased and the CSP profiles flatten. Finally, we find that, thanks to TES, CSP is more suited than PV and wind to meet peak loads. This can be measured by the capacity credit, but not by the variance-based risk, suggesting that the latter is only a crude representation of the adequacy risk.
40
Ramos, R. V. y A. C. Blanco. "GEOSTATISTICS FOR AIR QUALITY MAPPING: CASE OF BAGUIO CITY, PHILIPPINES". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W19 (23 de diciembre de 2019): 353–59. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w19-353-2019.
Texto completoResumen
Abstract. Mapping of air quality are often based on ground measurements using gravimetric and air portable sensors, remote sensing methods and atmospheric dispersion models. In this study, Geographic Information Systems (GIS) and geostatistical techniques are employed to evaluate coarse particulate matter (PM10) concentrations observed in the Central Business District of Baguio City, Philippines. Baguio City has been reported as one of the most polluted cities in the country and several studies have already been conducted in monitoring its air quality. The datasets utilized in this study are based on hourly simulations from a Gaussian-based atmospheric dispersion model that considers the impacts of vehicular emissions. Dispersion modeling results, i.e., PM10 concentrations at 20-meter interval, show that high values range from 135 to 422 μg/mm3. The pollutant concentrations are evident within 40 meters from the roads. Spatial variations and PM10 estimates at unsampled locations are determined using Ordinary Kriging. Geostatistical modeling estimates are evaluated based on recommended values for mean error (ME), root mean square error (RMSE) and standardized errors. Optimal predictors for pollutant concentrations at 5-meter interval include 2 to 5 search neighbors and variable smoothing factor for night-time datasets while 2 to 10 search neighbors and smoothing factors 0.3 to 0.5 were used for daytime datasets. Results from several interpolation tests indicate small ME (0.0003 to 0.0008 μg/m3) and average standardized errors (4.24 to 8.67 μg/m3). RMSE ranged from 2.95 to 5.43 μg/m3, which are approximately 2 to 3% of the maximum pollutant concentrations in the area. The methodology presented in this paper may be integrated with atmospheric dispersion models in refining estimates of pollutant concentrations, in generating surface representations, and in understanding the spatial variations of the outputs from the model simulations.
41
Lombard, M. A. S., J. G. Bryce, H. Mao y R. Talbot. "Mercury deposition in southern New Hampshire, 2006–2009". Atmospheric Chemistry and Physics Discussions 11, n.º 2 (8 de febrero de 2011): 4569–98. http://dx.doi.org/10.5194/acpd-11-4569-2011.
Texto completoResumen
Abstract. Mercury (Hg) is a global contaminant due to its toxicity and ubiquitous presence in the atmosphere. The primary source of Hg to terrestrial and aquatic ecosystems is atmospheric deposition. In an effort to understand the atmospheric cycling and depositional characteristics of Hg, event-based wet deposition samples were collected from July 2006 to September 2009 at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal trends in Hg wet deposition at TF. The lowest Hg wet deposition occurred in the winter with an average total seasonal deposition of 1.56 μg m−2 compared to the summer average of 4.71 μg m−2. Inter-annual differences are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Comparisons of Hg wet deposition trends with meteorological data and ambient gas phase mixing ratios revealed weak correlations. The strongest correlation was observed between maximum hourly precipitation rate and Hg wet deposition, and the relationship was strongly driven by extreme events. Dry deposition of reactive gaseous Hg (RGM) was estimated based on continuous RGM measurements at TF from October 2006 to September 2009 using an order-of-magnitude approach. Comparisons between Hg wet deposition and RGM dry deposition suggest that the seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80. Additional studies of seasonal differences in Hg deposition mechanisms (wet vs. dry) may provide a better understanding of the biogeochemical cycling of Hg.
42
Chen, Xiaofei, Juraj Parajka, Borbála Széles, Peter Valent, Alberto Viglione y Günter Blöschl. "Impact of Climate and Geology on Event Runoff Characteristics at the Regional Scale". Water 12, n.º 12 (9 de diciembre de 2020): 3457. http://dx.doi.org/10.3390/w12123457.
Texto completoResumen
The dynamics of flood event characteristics, such as the runoff coefficient and the recession time constant, differ in time and space, due to differences in climate, geology, and runoff generation mechanisms. This study examines the variability of event runoff characteristics and relates them to climatic and hydro-geological characteristics available at the regional scale. The main focus is to examine the role of rainfall patterns (i.e., event precipitation volume, precipitation intensity, and antecedent precipitation) and runoff regime (i.e., initial flow before runoff event and event duration) characteristics on the seasonal dynamics of runoff response. The analysis is performed in four small Austrian catchments representing different hydro-geological settings obtained by field mapping. The results are based on an analysis of 982 runoff events identified from hourly measurements of streamflow and precipitation in the period 2002 to 2013. The results show that larger event runoff coefficients and flow peaks are estimated in catchments with high mean annual precipitation than in drier catchments. In contrast to some previous studies, the results show only poor relation between antecedent precipitation (as an index of catchment wetness) and event runoff response. The initial flow is found to be the main factor influencing the magnitude of runoff coefficient and event peaks in all analyzed catchments and geological settings. The recession time constant tends to be inversely related to the maximum event precipitation intensity, with an exception for one catchment (Wimitzbach), which is characterized by the largest proportion of deep interflow contribution to runoff. The analysis of the runoff response by different event types indicates that runoff coefficients and recession time constants are the largest for snowmelt runoff events.
43
Уханов, Александр, Aleksandr Ukhanov, Денис Уханов, Denis Ukhanov, Евгений Сидоров, Evgeniy Sidorov, Александр Якунин y Aleksandr Yakunin. "FEATURES OF THE DIESEL RUNNING BY CAMELINA-MINERAL FUEL IN THE MODE OF INDEPENDENT IDLING". Bulletin Samara State Agricultural Academy 2, n.º 3 (27 de julio de 2017): 15–19. http://dx.doi.org/10.12737/17446.
Texto completoResumen
The mode of independent idling, characterized by an impaired process flow, unproductive fuel consumption and increased emissions of harmful substances into the atmosphere, is the most unfavorable mode of the diesel engine operation. Therefore, the aim of the research is to reveal the peculiarities of the tractor diesel engine operation by the camelina-mineral fuel in the mode of independent idling. Camelina-mineral fuel is a mixture of camelina oil and mineral diesel fuel in certain ratio of these components. To assess the possibility of using the camelina oil as biological component of diesel mixed fuel, an experimental study of the D-243 diesel engine in idling mode was carried out, and the degree of influence of the different ratio of the components of the mixed fuel on its parameters was determined. The researches were carried out with the diesel fuel on the L-0.2-62 mineral fuel and the camelina-mineral fuel with a ratio of the biological and mineral components: 25% RyzhM + 75% DT; 50% RyzhM + 50% DT; 75% RyzhM + 25% DT; 90% RyzhM + 10% DT and 90% RyzhM + 10% DT (US). For the parameters of the diesel, the excess air factor, the filling ratio of the diesel cylinder with fresh charge, the maximum cycle pressure, the hourly fuel consumption, smoke and carbon monoxide content in the exhaust gases are taken. It is established that when the diesel engine works on camelina-mineral fuel mode the minimum sustainable speed of the crankshaft idle speed 800 min-1 the values of maximum cycle pressure (6.3 MPa) and the filling ratio of the cylinders of a diesel engine the fresh charge (0,87) remain unchanged. The coefficient of excess air, increasing in mixed fuel shares of camelina oil to 90%, reduced from 7.187 to 4.619, while fuel consumption increases of 1.1 kg/h 2 kg/h. The best environmental indicators are observed when working on red-and-mineral fuel 50% RyzhM + 50% DT. Handling mixed fuel with ultrasound reduces fuel consumption, smoke and content of carbon oxide in the exhaust gas relative to the mixed fuel not treated with ultrasound.
44
Thomas, Simon, Mathew Owens, Mike Lockwood y Chris Owen. "Decadal trends in the diurnal variation of galactic cosmic rays observed using neutron monitor data". Annales Geophysicae 35, n.º 4 (17 de julio de 2017): 825–38. http://dx.doi.org/10.5194/angeo-35-825-2017.
Texto completoResumen
Abstract. The diurnal variation (DV) in galactic cosmic ray (GCR) flux is a widely observed phenomenon in neutron monitor data. The background variation considered primarily in this study is due to the balance between the convection of energetic particles away from the Sun and the inward diffusion of energetic particles along magnetic field lines. However, there are also times of enhanced DV following geomagnetic disturbances caused by coronal mass ejections or corotating interaction regions. In this study we investigate changes in the DV over four solar cycles using ground-based neutron monitors at different magnetic latitudes and longitudes at Earth. We divide all of the hourly neutron monitor data into magnetic polarity cycles to investigate cycle-to-cycle variations in the phase and amplitude of the DV. The results show, in general, a similarity between each of the A < 0 cycles and A > 0 cycles, but with a phase change between the two. To investigate this further, we split the neutron monitor data by solar magnetic polarity between times when the dominant polarity was either directed outward (positive) or inward (negative) at the northern solar pole. We find that the maxima and minima of the DV changes by, typically, 1–2 h between the two polarity states for all non-polar neutron monitors. This difference between cycles becomes even larger in amplitude and phase with the removal of periods with enhanced DV caused by solar wind transients. The time difference between polarity cycles is found to vary in a 22-year cycle for both the maximum and minimum times of the DV. The times of the maximum and minimum in the DV do not always vary in the same manner between A > 0 and A < 0 polarity cycles, suggesting a slight change in the anisotropy vector of GCRs arriving at Earth between polarity cycles. Polar neutron monitors show differences in phase between polarity cycles which have asymptotic directions at mid-to-high latitudes. All neutron monitors show changes in the amplitude of the DV with solar polarity, with the amplitude of the DV being a factor of 2 greater in A < 0 cycles than A > 0 cycles. In most cases the change in timing of the maximum /minimum is greatest with the stations' geomagnetic cut-off rigidity shows little variation in the DV phase with latitude. We conclude that the change in the DV with the dominant solar polar polarity is not as simple as a phase change, but rather an asymmetric variation which is sensitive to the neutron monitor's asymptotic viewing direction.
45
Antipov, YU A., P. R. Val'yekho Malbdonado, P. P. Oshchepkov, I. K. Shatalov y I. I. Shatalova. "Efficiency of a cogeneration plant based on a diesel engine under uneven electrical load conditions". Traktory i sel'hozmashiny 1, n.º 5 (2020): 13–17. http://dx.doi.org/10.31992/0321-4443-2020-5-13-17.
Texto completoResumen
A feature of electrical energy is that it must be produced at a given moment as much as the con-sumer needs. However, the graphs of energy consumption are very uneven over the time of day. In order to cover peak loads, the highly mobile equipment, which is often less economical, is used. This equipment is operated at partial power modes, where its efficiency is markedly reduced. One of the real ways to get out of this situation can be the use of heat pumps (HP) in circuits with cogeneration units (CU) based on heat engines. In this case, it becomes possible to use the heat engine in an economical mode throughout the day, and direct excess electricity at night to the heat pump drive. The paper considers two options for the operation of a cogeneration plant based on a diesel engine in power supply schemes for an individual consumer under conditions of an uneven electrical load schedule. Wartsila 12V32 is taken as an example of a CU. Such plants are operated in different regions of the Russian Federation. The main data of the CU in the design mode are given. Diesel generator: electric power - 6000 kW, hourly fuel consumption - 1080 kg / h, thermal power - 5240 kW, exhaust gas temperature - 485 ° C, effective efficiency - 0.46, fuel heat utilization factor 0.89. In the first version, the CU operates in a standard mode. This ensures the generation of electrical power in accordance with the schedule. In the second version, the CU is used in conjunction with the HP to obtain additional thermal power. Calculations have shown that by including a heat pump in a cogeneration unit operating in an uneven electrical load schedule mode, it is possible to ensure that the diesel engine operates at maximum efficiency during the whole day and to increase the fuel heat utilization rate by 17-20%.
46
Prietzel, Jörg. "Schutzwälder der Nördlichen Kalkalpen: Verjüngung, Mikroklima, Schneedecke und Schalenwild | Protection forests in the Northern Limestone Alps: stand regeneration, microclimate, snow cover and ungulates". Schweizerische Zeitschrift fur Forstwesen 161, n.º 1 (1 de enero de 2010): 12–22. http://dx.doi.org/10.3188/szf.2010.0012.
Texto completoResumen
Relationships among ungulate pressure, stand regeneration, microclimate, and snowpack dynamics were investigated at three protection forest sites in the mixed mountain forest zone of the Bavarian Limestone Alps. The study was conducted at plots located inside and outside ungulate exclosures which had been established about 35 years ago. Air and topsoil temperatures were recorded for one year in hourly intervals. In winter 2005/2006, the thickness, constitution, and mobility of the snowpack were investigated. Inside the exclosures, which were stocked with dense regeneration of mixed mountain forest, mean air and topsoil temperatures were up to 0.9 °C (air) and 1.9 °C (soils) lower than outside. Maximum daily values of air and topsoil temperatures were up to 1.4 °C (air) and 5.2 °C (soils) lower inside the exclosures compared to the respective outside plots. The temperature differences were dependent on the aspect (NW < ESE < S). Snowpack thickness during winter increased more slowly inside the exclosures than outside due to snow interception by the young trees which had developed during stand regeneration; in late winter, snowpack melting was retarded. Inside the exclosures the snowpack was more heterogeneous (“column structure”) than outside (laminated structure). Consequently, inside the exclosures a large portion of the melting water drained vertically to the bottom of the snowpack and infiltrated into the soil, and the snow gliding activity was significantly smaller than outside. In summary, particularly at S-exposed sites, exclosure of ungulates resulted in a cooler, less extreme microclimate, a more heterogeneous and stable snowpack, and reduced snow gliding. Therefore, an adequate regulation of ungulate density by appropriate hunting activity is a key factor for a sustainable provision of important protection services of the mixed mountain forest in the Northern Limestone Alps.
47
Fazel-Rastgar, Farahnaz. "Contribution of Deforestation to Severe Flooding in Southeast Parts of the Caspian Sea: A Case Study with NDVI Analysis". Journal of Extreme Events 07, n.º 01n02 (marzo de 2020): 2050008. http://dx.doi.org/10.1142/s2345737620500086.
Texto completoResumen
Iran has been faced with increase in flooding cases during the past 60 years. The human activities have been considered as a devastating factor in the environmental change causing the occurrence of severe flooding cases during past decades. On August 11, 2001, a relatively severe rainfall in the south east of Caspian Sea led to the occurrence of a severe deadly flooding in Golestan province and some parts in northern Khorasan province have been unprecedented in Iran over the past century. The destructive extent of flooding in the urban and rural areas reached about 5,000 km2. Here, the synoptic surface and upper levels of the weather charts have been analyzed along with the monitoring of half hourly METEOSAT7 images to show the convective clouds development over the area of the study. The total precipitation in this area during the flooding period was reported between 2.5 and 153 mm with the maximum estimation over the center of the storm around less than 250[Formula: see text]mm. Using satellite imagery in 1979 and 2000, vegetation changes and environmental changes have been investigated and shown extensive decline in vegetation. The image processing and Normalized Difference Vegetation Index (NDVI) calculation of the color composite 433 of LANDSAT5 and the color composite 211 of TERRA (MODIS sensor) images between 1998 and 2001 have been revealed significant deforestation around 248,131,534.3[Formula: see text][Formula: see text] over the study, particularly over the rivers’ neighborhood. Also, by assumption of the same precipitation for 1998 and 2001, the discharge rate in flood case of 2001 has been intensified 1.3 times (at 13 percent) larger than that of 1998. This shows the direct impact of the deforestation and land use changes over the study area during 1998–2001.
48
Dauji, Saha, P. K. Srivastava y K. Bhargava. "Site-Specific Factors to Derive Maximum 1-hourly to 6-hourly Continuous Rainfall from Daily Extreme Rainfall on West Coast of India". Transactions of the Indian National Academy of Engineering 6, n.º 3 (28 de abril de 2021): 857–67. http://dx.doi.org/10.1007/s41403-021-00236-9.
Texto completo
49
Sarraj, Yahya R. "Hourly and Daily Traffic Expansion Factors on Selected Roads in Gaza, Palestine". Open Civil Engineering Journal 12, n.º 1 (14 de noviembre de 2018): 355–67. http://dx.doi.org/10.2174/1874149501812010355.
Texto completoResumen
Background: The shortage of sufficient, reliable and continuous traffic data in many developing countries makes it difficult for traffic engineers and researchers. Traffic data are essential for both planning and design of transportation facilities. Objective: This work tries to provide data that in order to help local experts in Gaza city to provide better estimates of the average daily traffic (ADT) and hence better transportation facilities. Methods: The analysis and discussion are based on continuous traffic flow counts conducted on three selected main streets in Gaza. Data were collected for 24 hours on seven consecutive days on each street. Results: The results indicate that the average hourly expansion factors(HEFs) have a margin of error for the period between 7:00 and 16:00 that does not exceed ±3%. The results also indicate that the average daily expansion factors (DEFs) on the three streets have a maximum margin of error of 3.2% on both Sunday and Monday. On the other hand, the analysis proved that the maximum peak hour volume was 2864 vehicles/hour on Al Jalaa Street between 7:00 and 8:00 and the average peak-to-daily ratio (p/d) of the three streets was found to be 7.18%. The maximum directional traffic split (D) was found to be 60% in the heaviest direction of traffic flow during the peak period. Conclusion: The HEFs and DEFs produced in this work can be used with a 95% confidence on the main streets of Gaza city.
50
Ots, Riinu, Mathew R. Heal, Dominique E. Young, Leah R. Williams, James D. Allan, Eiko Nemitz, Chiara Di Marco et al. "Modelling carbonaceous aerosol from residential solid fuel burning with different assumptions for emissions". Atmospheric Chemistry and Physics 18, n.º 7 (4 de abril de 2018): 4497–518. http://dx.doi.org/10.5194/acp-18-4497-2018.
Texto completoResumen
Abstract. Evidence is accumulating that emissions of primary particulate matter (PM) from residential wood and coal combustion in the UK may be underestimated and/or spatially misclassified. In this study, different assumptions for the spatial distribution and total emission of PM from solid fuel (wood and coal) burning in the UK were tested using an atmospheric chemical transport model. Modelled concentrations of the PM components were compared with measurements from aerosol mass spectrometers at four sites in central and Greater London (ClearfLo campaign, 2012), as well as with measurements from the UK black carbon network.The two main alternative emission scenarios modelled were Base4x and combRedist. For Base4x, officially reported PM2.5 from the residential and other non-industrial combustion source sector were increased by a factor of four. For the combRedist experiment, half of the baseline emissions from this same source were redistributed by residential population density to simulate the effect of allocating some emissions to the smoke control areas (that are assumed in the national inventory to have no emissions from this source). The Base4x scenario yielded better daily and hourly correlations with measurements than the combRedist scenario for year-long comparisons of the solid fuel organic aerosol (SFOA) component at the two London sites. However, the latter scenario better captured mean measured concentrations across all four sites. A third experiment, Redist – all emissions redistributed linearly to population density, is also presented as an indicator of the maximum concentrations an assumption like this could yield.The modelled elemental carbon (EC) concentrations derived from the combRedist experiments also compared well with seasonal average concentrations of black carbon observed across the network of UK sites. Together, the two model scenario simulations of SFOA and EC suggest both that residential solid fuel emissions may be higher than inventory estimates and that the spatial distribution of residential solid fuel burning emissions, particularly in smoke control areas, needs re-evaluation. The model results also suggest the assumed temporal profiles for residential emissions may require review to place greater emphasis on evening (including discretionary) solid fuel burning.