Study on Influence Law of Urban Architectural Structure on the Automobile Exhaust Diffusion Based on CFD

2012 ◽  
Vol 178-181 ◽  
pp. 751-755
Author(s):  
Yong Zhang ◽  
Zheng Qi Gu ◽  
Zhen Wang ◽  
Yong Yu
Keyword(s):  
Wind Direction ◽  
Volume Fraction ◽  
Great Influence ◽  
Entire Study ◽  
Automobile Exhaust ◽  
Average Value ◽  
Near Earth Space ◽  
Urban Buildings ◽  
Structural Layout ◽  
Entire Study Area

For study the law of urban buildings, in particular, the buildings at both roads’ sides in crossroads impacting on the diffusion of automobile exhaust, using CFD, combined with meteorological wind，simulates a crossroads automobile exhaust diffusion processing during waiting 35s. The results are following: in poor circulation areas, CO volume fraction in the buildings near-Earth space is up to 1.0e-7 and more than 100 times average value of the entire study area, so buildings structural layout has great influence. After Analysis, propose that local meteorological wind direction and speed should be considered and different height gradient design should be selected in buildings structural layout, so that the exhaust spread rapidly and drift to the urban high altitude, in order to improve air quality.

scholarly journals Numerical Simulation of Hydrogen Leakage and Diffusion Process of Fuel Cell Vehicle

2021 ◽  
Vol 12 (4) ◽  
pp. 193
Author(s):  
Mingyu Jiao ◽  
Haoran Zhu ◽  
Jinglong Huang ◽  
Xin Zhang
Keyword(s):  
Fuel Cell ◽  
Wind Direction ◽  
Open Space ◽  
Hydrogen Diffusion ◽  
Volume Fraction ◽  
Great Influence ◽  
Leakage Rate ◽  
Fuel Cell Vehicle ◽  
Closed Space ◽  
Hydrogen Safety

Regarding the problem of hydrogen diffusion of the fuel cell vehicle (HFCV) when its hydrogen supply system leaks, this research uses the FLUENT software to simulate numerical values in the process of hydrogen leakage diffusion in both open space and closed space. This paper analyzed the distribution range and concentration distribution characteristics of hydrogen in these two different spaces. Besides, this paper also took a survey about the effects of leakage rate, wind speed, wind direction in open space and the role the air vents play on hydrogen safety in closed space, which provides a reference for the hydrogen safety of HFCV. In conclusion, the experiment result showed that: In open space, hydrogen leakage rate has a great influence on its diffusion. When the leakage rate doubles, the hydrogen leakage range will expand about 1.5 times simultaneously. The hydrogen diffusion range is the smallest when the wind blows at 90 degrees, which is more conducive to hydrogen diffusion. However, when the wind direction is against the direction of the leakage of hydrogen, the range of hydrogen distribution is maximal. Under this condition, the risk of hydrogen leakage is highest. In an enclosed space, when the vent is set closest to the leakage position, the volume fraction of hydrogen at each time is smaller than that at other positions, so it is more beneficial to safety.

Zwischenevaluation des Wald-Wild-Management-Instruments (WWMI) im Pilotprogramm effor2 «Wald und Wild» | Preliminary evaluation of the Game-Forest-Management-Tool (GFMT) in the effor2 pilot programme «Game and Forest»

2003 ◽  
Vol 154 (8) ◽  
pp. 305-313 ◽  
Author(s):  
Roman Eyholzer ◽  
Martin Baumann ◽  
Rolf Manser
Keyword(s):  
Forest Management ◽  
Management Practice ◽  
Management Tool ◽  
Preliminary Evaluation ◽  
Optimal Contract ◽  
Technical Tool ◽  
Entire Study ◽  
Pilot Programme ◽  
Complex Problems ◽  
Entire Study Area

Faced with the challenging task of balancing forest interests and wildlife, the Swiss Forest Agency initiated the pilot programme«Game and Forest», which is committed to a philosophy of goal-oriented management practice and a redesign of forestry subsidizing. Within this programme the diverse goals of forestry and hunting have been amalgamated to a superimposed goal and set out in a corresponding contract. The Game-Forest-Management-Tool (GFMT) has been divised to simulate the effect of various strategies to deal with the complex problems of forest-wildlife. Optimal contract-fulfilling procedures can be simulated on a PC using this technical tool. The efficiency of the measures suggested by simulations that were carried out are being tested in a study area within the pilot programme, «Game and Forest». Half way through this trial, after two years, we can say that there has been no significant increase of non-browsed areas. In 2004, after the collection of data for the entire study area, we will be able to tell whether applying this computer simulated strategy truly leads to an augmentation of non-browsed area and a decrease in bark-peeled forests in the pilot area.

scholarly journals Night-Time Light Remote Sensing Mapping: Construction and Analysis of Ethnic Minority Development Index

2021 ◽  
Vol 13 (11) ◽  
pp. 2129
Author(s):  
Fei Zhao ◽  
Lu Song ◽  
Zhiyan Peng ◽  
Jianqin Yang ◽  
Guize Luan ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Ethnic Group ◽  
Ethnic Groups ◽  
Ethnic Minorities ◽  
Population Data ◽  
Night Time ◽  
Entire Study ◽  
Development Index ◽  
Remote Sensing Mapping ◽  
Entire Study Area

Using toponym data, population data, and night-time light data, we visualized the development index of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups on ArcGIS as well as the distribution of 25 ethnic minorities in the study area. First, we extracted the toponym data of 25 ethnic minorities in the study area, combined with night-time light data and the population proportion data of each ethnic group, then we obtained the development index of each ethnic group in the study area. We compared the development indexes of the Yi, Wa, Zhuang, Naxi, Hani, and Dai ethnic groups with higher development indexes. The results show that the Yi nationality’s development index was the highest, reaching 28.86 (with two decimal places), and the Dai nationality’s development index was the lowest (15.22). The areas with the highest minority development index were concentrated in the core area of the minority development, and the size varied with the minority’s distance. According to the distribution of ethnic minorities, we found that the Yi ethnic group was distributed in almost the entire study area, while other ethnic minorities had obvious geographical distribution characteristics, and there were multiple ethnic minorities living together. This research is of great significance to the cultural protection of ethnic minorities, the development of ethnic minorities, and the remote sensing mapping of lights at night.

scholarly journals Monitoring and simulating the distribution of phytoplankton in constructed wetlands based on SPOT 6 images

2021 ◽  
Vol 13 (1) ◽  
pp. 454-468
Author(s):  
Yumeng Song ◽  
Jing Zhang
Keyword(s):  
Water Quality ◽  
Water Quality Model ◽  
Quality Model ◽  
Band Ratio ◽  
Entire Study ◽  
Chl A ◽  
Analytical Tools ◽  
Best Fit ◽  
Entire Study Area ◽  
Range Of Values

Abstract We integrated hyperspectral and field-measured chlorophyll-a (Chl-a) data from the Kristalbad constructed wetland in the Netherlands. We developed a best-fit band ratio empirical algorithm to generate a distribution map of Chl-a concentration (C chla) from SPOT 6 imagery. The C chla retrieved from remote sensing was compared with a water quality model established for a wetland pond system. The retrieved satellite results were combined with a water quality model to simulate and predict the changes in phytoplankton levels. The regression model provides good retrievals for Chl-a. The imagery-derived C chla performed well in calibrating the simulation results. For each pond, the modeled C chla showed a range of values similar to the Chl-a data derived from SPOT 6 imagery (10–25 mg m−3). The imagery-derived and prediction model results could be used as the guiding analytical tools to provide information covering an entire study area and to inform policies.

PREDATION BY CALOSOMA SYCOPHANTA L. (COLEOPTERA: CARABIDAE): EVIDENCE FOR A LARGE IMPACT ON GYPSY MOTH, LYMANTRIA DISPAR L. (LEPIDOPTERA: LYMANTRIIDAE), PUPAE

1985 ◽  
Vol 117 (9) ◽  
pp. 1117-1126 ◽  
Author(s):  
Ronald M. Weseloh
Keyword(s):  
Gypsy Moth ◽  
Lymantria Dispar ◽  
Ground Level ◽  
Mortality Factor ◽  
Substantial Impact ◽  
Entire Study ◽  
Dispersal Potential ◽  
Capture Recapture ◽  
The Impact ◽  
Entire Study Area

AbstractThe impact of predation by Calosoma sycophanta L. on an increasing prey population was assessed by recapturing marked adult beetles, periodically observing tagged gypsy moth pupae, and examining gypsy moth pupal remains in different microhabitats. Adult beetles dispersed in random directions but many tended to remain near the trap at which they were originally caught, suggesting a low dispersal potential. About 75% of the adult beetles present in the plot on one day were still present the next day. Capture–recapture estimates suggested that there were at most about 250 male beetles and half as many females/ha in the plot. Calosoma larvae destroyed 70% of tagged gypsy moth pupae under burlap bands on tree trunks near ground level, which was much more than any other mortality factor. Although this percentage was the same when mortality was assessed by looking at pupal remains within 5 m of the ground on tree trunks, pupae higher in trees and on leaves were not attacked as frequently. On average, about 40% of the pupae present in the entire study area were destroyed by Calosoma larvae. Each female beetle in the site would have had to produce about 30 progeny to have this effect. These data suggest that a relatively low number of adult beetles can have a substantial impact on gypsy moth populations.

Microstructural and Tribological Characterization of API X52 Dual-Phase Steel

2021 ◽  
Author(s):  
Gamri Hamza ◽  
Allaoui Omar ◽  
Zidelmel Sami
Keyword(s):  
Mechanical Properties ◽  
Dual Phase Steel ◽  
Volume Fraction ◽  
Wear Behavior ◽  
Normal Load ◽  
Great Influence ◽  
Dual Phase ◽  
Martensite Volume Fraction ◽  
Direct Quenching ◽  
Disc Configuration

Abstract The effect of the morphology and the martensite volume fraction on the microhardness, the tensile, the friction and the wear behavior of API X52 dual phase (DP) steel has been investigated. Three different heat treatments were used to develop dual phase steel with different morphologies and with different amounts of martensite: Intermediate Quenching Treatment/Water (IQ); Step Quenching Treatment (SQ) and direct quenching (DQ). Tribological tests are conducted on DP steels using a ball-on-disc configuration under normal load of 5 N and at a sliding speed of 4 cm/s were used to study the friction and wear behavior of treated samples. Results show that the ferrite–martensite morphology has a great influence on the mechanical properties of dual phase steel. The steel subjected to (IQ) treatment attain superior mechanical properties compared to the SQ and the DQ treatments. On the other hand, it is also found that the friction coefficient and the wear rate (volume loss) decrease when the hardness and the martensite volume fraction increase. The steel with fine fibrous martensite provide good wear resistance.

scholarly journals PENGARUH MODEL PEMBELAJARAN TWO STAY TWO STRAY TERHADAP HASIL BELAJAR SEJARAH DI SMA NEGERI 7 MEDAN

2019 ◽  
Vol 1 (2) ◽  
pp. 85
Author(s):  
Marcho Alex Samuel Silitonga
Keyword(s):  
Student Learning ◽  
Learning Outcomes ◽  
Great Influence ◽  
Student Learning Outcomes ◽  
Learning Model ◽  
T Test ◽  
Average Value ◽  
Post Test ◽  
Quasi Experimental ◽  
History Of

This study aims to determine the effect of the application of the Two Stay Two Stray learning model (TSTS) to the history of student learning outcomes at SMA Negeri 7 Medan. The research method used is quasi-experimental. The study population was students of class X IPS with a sample of 65 students consisting of 34 students of class X IPS 2 as an experimental class and 31 students of class X IPS 1 as a control class. Data collection techniques using observation and tests. The data obtained were analyzed using the t-test. The observation results showed that 91% of the experimental class students who took part in learning with the TSTS model got very good average scores. The average post-test value of the experimental class was 80.3, while the average value of the post-test of the control class that followed the learning with the conventional model was 63.70. T-test results for the post-test scores were obtained tcount > ttable (7,004 > 1,670).These results indicate that the TSTS learning model has a great influence in improving the history of student learning outcomes in class XI IPS 2 SMA Negeri 7 Medan.

scholarly journals DETERMINATION AND MAPPING OF THE TERRESTRIAL GRAVITY ANOMALIES IN THE MOUNTAINOUS AREAS OF IRAQ

2021 ◽  
Vol 6 (24) ◽  
pp. 213-225
Author(s):  
Shazad Jamal Jalal ◽  
Tajul Ariffin Musa ◽  
Ami Hassan Md Din ◽  
Wan Anom Wan Aris
Keyword(s):  
Gravity Data ◽  
Physical Geodesy ◽  
Gravity Anomalies ◽  
Gravity Survey ◽  
Mountainous Areas ◽  
Entire Study ◽  
Terrestrial Gravity ◽  
The Past ◽  
Regional Gravity ◽  
Entire Study Area

Gravity data and computing gravity anomalies are regarded as vital for both geophysics and physical geodesy fields. The mountainous areas of Iraq are characterized by the lack of regional gravity data because gravity surveys are rarely performed in the past four decades due to the Iraq-Iran war and the internal unstable political situation of this particular region. In addition, the formal map of the available terrestrial gravity which was published by the French Database of Bureau Gravimetrique International (International Gravimetric Bureau-in English) (BGI), introduces Iraq and the study area as a remote area and in white color because of the unavailability of gravity data. However, a dense and local (not regional) gravity data is available which was conducted by geophysics researchers 13 years ago. Therefore, the regional gravity survey of 160 gravity points was performed by the authors at an average 11 km apart, which was covers the whole area of Sulaymaniyah Governorate (part of the mountainous areas of Iraq). In spite of Although the risk of mine fields within the study area, suitable safe routes as well as a helicopter was used for the gravity survey of several points on the top of mountains. The survey was conducted via Lacoste and Romberg geodetic gravimeter and GPS handheld. The objective of the study is to determine and map the gravity anomalies for the entire study area, the data of which would assist different geosciences applications.

scholarly journals GIS based Soil Nutrient Assessment of Available Macro and Micronutrients in Tommaladahalli Microwatershed of Chikkamagaluru District, Karnataka, India

2021 ◽  
Vol 10 (9) ◽  
pp. 510-517
Author(s):  
S. Anitha ◽  
K. T. Gurumurthy Ganapathi
Keyword(s):  
Interpolation Method ◽  
Soil Nutrient ◽  
Nutrient Status ◽  
Nitrogen And Phosphorus ◽  
Available Nitrogen ◽  
Entire Study ◽  
Available N ◽  
Standard Procedures ◽  
Entire Study Area ◽  
Available Nutrient Status

An investigation was undertaken in Tommaladahalli (566.13 ha) micro-watershed of Tarikere taluk, Chikkamagaluru district of Karnataka to assess available nutrient status in the surface soils. About 118 surface soil samples were collected grid wise by using cadastral map at 250 m grid interval and were analyzed for their fertility status using standard procedures. Soil fertility maps were prepared by means of interpolation method called Krigging. The results revealed that the pH, electrical conductivity, and organic carbon were ranged from 5.37 to 9.06, 0.065 to 0.466 dS m-1 and 0.33 to 1.62 per cent respectively. The available N, P2O5, K2O were ranged from 175.6 to 545.6 kg ha-1, 11.8 to 61.1 kg ha-1 and 122.7 to 491.4 kg ha-1, respectively. The available nitrogen and phosphorus were low to medium, where as potassium content was medium to high in the entire study area. Micronutrients viz. zinc, iron and boron were sufficient and were ranged from 0.34 to 1.17 mg kg-1, 2.03 to 21.86 mg kg-1 and 0.30 to 0.89 mg kg-1 respectively.

SOUND SPEED AND ABSORPTION STUDIES OF MARINE SEDIMENTS BY A RESONANCE METHOD

Geophysics ◽  
1960 ◽  
Vol 25 (2) ◽  
pp. 451-467 ◽  
Author(s):  
George Shumway
Keyword(s):  
Grain Size ◽  
Sound Speed ◽  
Absorption Maximum ◽  
Volume Fraction ◽  
Sea Water ◽  
Resonance Method ◽  
Unconsolidated Sediments ◽  
Linear Absorption ◽  
Average Value ◽  
Absorption Measurements

Laboratory measurements of compressional sound speed, and absorption, have been made on 111 unconsolidated marine sediment samples, ranging from shallow water sands to deep‐sea clays. In addition, determinations were made of porosity, wet density, and grain size distributions. Frequencies between 20 kc/sec and 37 kc/sec were used for the acoustic studies. Sound speed values at room temperature range from 1.474 km/sec for a red medium clay to 1.785 km/sec for a medium sand. More than one‐third of the values are lower than the value for sea water alone. Variations in the speed of sound in unconsolidated sediments as found in nature are caused by the following factors, in order of importance: (1) porosity, because of the great difference in compressibility of water and mineral grains; (2) the factor which produces rigidity, which appears to be related to the abundance of coarse grains; (3) pressure; (4) temperature; (5) compressibility of the grain aggregate, determined from compressibilities of individual minerals. Sound absorption measurements ranged from 0.5 db/m for a medium clay (28.4 kc/sec) to about 20 db/m for silts and fine sands (between 30 and 37 kc/sec). An absorption maximum occurs for sediments of intermediate porosity (0.45–0.6) and intermediate grain size (0.031 mm–0.25 mm). The expression [Formula: see text], where α is the linear absorption coefficient, M is a frequency‐dependent factor related to the sediment volume fraction of grains in mutual contact, and [Formula: see text] is a computable total acoustically effective grain surface area, predicts the absorption values and the absorption maximum. Absorption measurements at more than one frequency between 20 kc/sec and 37 kc/sec were obtained for 65 samples. Assuming that absorption is directly proportional to frequency raised to a power n, the data yield an average value of n equal to 1.79, with a standard deviation of 0.98.

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