2,976 research outputs found
Experimental Research on Natural Pozzolan as Cement Replacement
This paper presents the properties of motor and concrete with natural pozzolan as partial replacement of cement. In this research, natural pozzolan from Twin Taung, Sagaing Region and local cement (Crown) are used. Firstly, chemical composition of natural pozzolan and Crown cement are analysed. And then the physical properties of local materials used in this research are determined according to ASTM procedure. Partial replacement percentages of pozzolan are considered 10%, 20%, 30% and 40%.The strength of motor and concrete with natural pozzolan (0%,10%, 20%, 30%, and 40%) is tested at 7 days,28 days and 91days. From the trial mix design, the water-cement ratio (0.555) is obtained by using the least square method. To get target strength (4000 psi), by using water cement ratio (0.555) and 68% of maximum aggregate size (20 mm), the concrete mix proportion (1:1.9:3) is obtained.The compressive strength of concrete with various percentages of natural pozzolan at 60 days and 91 days are more than 7 days and 28 days strength. Therefore, it can be concluded that natural pozzolan may be used as cement replacement material when it is not required high strength performance in structures
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Springtime photochemical ozone production observed in the upper troposphere over east Asia
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Photochemical production of O3 in biomass burning plumes in the boundary layer over northern Australia
In situ aircraft measurements of ozone (O3) and its precursors were made over northern Australia in August-September 1999 during the Biomass Burning and Lightning Experiment Phase B (BIBLE-B). A clear positive correlation of O3 with carbon monoxide (CO) was found in biomass burning plumes in the boundary layer (<3 km). The ΔO3/ΔCO ratio (linear regression slope of O3-CO correlation) is found to be 0.12 ppbv/ppbv, which is comparable to the ratio of 0.15 ppbv/ppbv observed at 0-4 km over the Amazon and Africa in previous studies. The net flux of O3 exported from northern Australia during BIBLE-B is estimated to be 0.3 Gmol O3/day. In the biomass burning region, large enhancements of O3 were coincident with the locations of biomass burning hot spots, suggesting that major O3 production occurred near fires (horizontal scale <50 km)
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Photochemical production of ozone in the upper troposphere in association with cumulus convection over Indonesia
The Biomass Burning and Lightning Experiment phase A (BIBLE-A) aircraft observation campaign was conducted from 24 September to 10 October 1998, during a La Niña period. During this campaign, distributions of ozone and its precursors (NO, CO, and nonmethane hydrocarbons (NMHCs)) were observed over the tropical Pacific Ocean, Indonesia, and northern Australia. Mixing ratios of ozone and its precursors were very low at altitudes between 0 and 13.5 km over the tropical Pacific Ocean. The mixing ratios of ozone precursors above 8 km over Indonesia were often significantly higher than those over the tropical Pacific Ocean, even though the prevailing easterlies carried the air from the tropical Pacific Ocean to over Indonesia within several days. For example, median NO and CO mixing ratios in the upper troposphere were 12 parts per trillion (pptv) and 72 parts per billion (ppbv) over the tropical Pacific Ocean and were 83 pptv and 85 ppbv over western Indonesia, respectively. Meteorological analyses and high ethene (C2H4) mixing ratios indicate that the increase of the ozone precursors was caused by active convection over Indonesia through upward transport of polluted air, mixing, and lightning all within the few days prior to observation. Sources of ozone precursors are discussed by comparing correlations of some NMHCs and CH3Cl concentrations with CO between the lower and upper troposphere. Biomass burning in Indonesia was nearly inactive during BIBLE-A and was not a dominant source of the ozone precursors, but urban pollution and lightning contributed importantly to their increases. The increase in ozone precursors raised net ozone production rates over western Indonesia in the upper troposphere, as shown by a photochemical model calculation. However, the ozone mixing ratio (∼20 ppbv) did not increase significantly over Indonesia because photochemical production of ozone did not have sufficient time since the augmentation of ozone precursors. Backward trajectories show that many air masses sampled over the ocean south of Indonesia and over northern Australia passed over western Indonesia 4-9 days prior to being measured. In these air masses the mixing ratios of ozone precursors, except for short-lived species, were similar to those over western Indonesia. In contrast, the ozone mixing ratio was higher by about 10 ppbv than that over Indonesia, indicating that photochemical production of ozone occurred during transport from Indonesia. The average rate of ozone increase (1.8 ppbv/d during this transport is similar to the net ozone formation rate calculated by the photochemical model. This study shows that active convection over Indonesia carried polluted air upward from the surface and had a discernable influence on the distribution of ozone in the upper troposphere over the Indian Ocean, northern Australia, and the south subtropical Pacific Ocean, combined with NO production by lightning
Mechanisms that influence the formation of high-ozone regions in the boundary layer downwind of the Asian continent in winter and spring
The seasonal variation of ozone (O3) in the boundary layer (BL) over the western Pacific is investigated using a chemistry-transport model. The model results for January and April-May 2002 were evaluated by comparison with PEACE aircraft observations. In January, strong northwesterlies efficiently transported NOx from the continent, leading to an O3 increase of approximately 5-10 ppbv over a distance of about 3000 km. In April, southwesterlies dominated due to anticyclone development over the western Pacific. Along this flow, O3 continued to be produced by NO x emitted from East Asia. This resulted in the formation of a high-O3 (> 50 ppbv) region extending along the coastal areas of East Asia. This seasonal change in O3 was driven in part by a change in the net O3 production rate due to increases in solar UV and H 2O. Its exact response depended on the NOx values in the BL. The net O3 production rate increased between winter and spring over the Asian continent and decreased over the remote western Pacific. Model simulations show that about 25% of the total O3 (of 10-20 ppbv) increase over the coastal region of Northeast Asia was due to local production from NOx emissions from China, and the rest was due to changes in background levels as well as emissions from Korea, Japan, and east Siberia. Uplift of BL air over Asia, horizontal transport in the free troposphere, and subsidence were the principal mechanisms of transporting Asian O3 to the central and eastern North Pacific Copyright 2008 by the American Geophysical Union
Visualization and Analysis of Sensory Data
Recently, California has suffered a severe drought, making water a scarce resource to its population. Many viticulturists are based in this area who rely on heavy irrigation to produce a better grape and a better wine. Not just in California, but throughout the nation, irrigation must be applied intelligently for efficient use of water and funding. By taking measurements of physical characteristics of a vineyard over time, one may be able to visualize trends in the data which lend itself to describing preferred growing methods. Wireless sensors can be used to take measurements including moisture, temperature, sunlight, and more. Sensors have been installed at multiple locations about a vineyard. A framework has been put in place to capture, adjust, and calibrate the data as well as store it for future retrieval. The data are visualized over time to see the effects of techniques in the long term. These are helpful for suggesting irrigation strategy that will lead to the best yield. Sensors are cheap and effective, but are prone to malfunction and transmission errors. When these problems occur, the faulty time-series data can be cleaned by correlating with similar time-series data in the same time span. The data system will be a necessity for competitive viticulturists, reducing cost of irrigation and improving quality of wine. In the future, the tool could be applied to other crops. Also, if any new important values must be derived or measured, the system can be extended to include them
ANALISIS KINERJA KEUANGAN PERUSAHAAN SUB SEKTOR PERTAMBANGAN SEKTOR BATUBARA YANG TERDAFTAR DI BURSA EFEK INDONESIA PERIODE 2015-2016
2018. Faculty of Economics, University August 17, 1945. Financial Performance in the Coal Sector Mining Sub-Sector company listed on the Indonesia Stock Exchange for the 2015-2016 Period, (under Supervisor I Mrs. Titin Ruliana and Supervisor II Mr. Taghfirul Azhima Yoga Siswa).The financial performance based on net profit margin ratio, return on assets, current ratio and quick ratio in the mining sector sub-sector of the coal sector in 2015-2016.The result of this based on profitability ratio analysis of the variable net profit margin (NPM) in the GEMS company (8,51%), ITMG (5,59%), KKGI (5,12%) and MYOH (0,25%). Likewise liquidity ratio in the current ratio (CR) variables in GEMS companies (97,99%), ITMG (45,50%), KKGI (183,14%), MBAP (137,57%) and PTBA (11,21%). And quick ratio (QR) variables in companies in GEMS companies (105,23%), ITMG (60,83%) KKGI (135,71%), MYOH (167,68%) and PTBA (9,64%). the financial performance decreased in 2016 on the variable return on assets (ROA) in MBAP companies (-8,45%), MYOH (-0,9%), PTBA (-1,16%) and TOBA (-3,53 %).The financial performance has increased in 2016 compared to 2015 against the variable net profit margin, current ratio and quick ratio. the variable return on assets (ROA) has decreased in 2016 compared to 201
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Photochemistry of ozone over the western Pacific from winter to spring
Aircraft measurements of ozone (O3) and its precursors, including NO, CO, H2O, and nonmethane hydrocarbons (NMHCs), were made over the western Pacific in the 20° - 45°N latitude range in January and April-May 2002 during the Pacific Exploration of Asian Continental Emission (PEACE)-A and B campaigns. These measurements have provided data sets that, in combination with Transport and Chemical Evolution over the Pacific (TRACE-P) data taken in March 2001, enable studies of O3 photochemistry from winter to late spring. A photochemical box model is used to calculate ozone formation (F(O3)) and destruction (D(O3)) rates constrained by the observed species concentrations. The values of F(O3) and D(O3) are controlled directly by NO, J(O1D) (O3 photolysis frequency), H2O, OH, and HO2. Changes in HO2 concentration cause corresponding changes in both F(O3) and D(O3) leading to their coupling. Concentrations of these species, which are strongly influenced by photochemistry and transport from the Asian continent, underwent large seasonal variations. In the boundary layer (0-3 km), NO was much higher in January than in April-May, because of stronger winds, lower convective activities, and lower oxidation rates by OH in winter. The net O3 formation rate, given by P(O3) = F(O3) - D(O3), was largely positive in the boundary layer at 30°-45°N (1.5-4 ppbv d-1) in January, mainly because of high NO and low H2O values. Net O3 formation continued from January to the end of March, demonstrating that the western Pacific is an important O3 source region during this season. Net O3 formation nearly ceased by late April/May because of the decrease in NO and the increase in H2O. In the latitude range of 20°-30°N, P(O3) in the boundary layer was positive in January and turned negative by March. The earlier transition was mainly due to lower NO and higher H2O concentrations, combined with weaker transport and higher temperatures than those at 30°-45°N. The upper troposphere (6-12 km) has been shown to be a region of net O3 formation throughout most of the year because of high NO and low H2O. The present study illustrates that a decrease in the net O3 formation rate at 20°-45°N latitude from winter to late spring is explained systematically by the increases in J(O1D), H2O, OH, and HO2 (primarily due to increases in temperature and solar radiation) and the decrease in NO (primarily due to decrease in transport from the Asian continent). Differences in the seasonal variation of O3 photochemistry observed over the North American continent are interpreted in terms of the differences in factors controlling O3 formation and destruction. Copyright 2004 by the American Geophysical Union
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Removal of NOx and NOy in biomass burning plumes in the boundary layer over northern Australia
Oxygen-Vacancy-Induced Orbital Reconstruction of Ti Ions at the Interface of LaAlO3/SrTiO3 Heterostructures: A Resonant Soft-X-Ray Scattering Study
Resonant soft-x-ray scattering measurements have been performed to investigate interface electronic structures of (LaAlO3/SrTiO3) superlattices. Resonant scattering intensities at superlattice reflections show clear evidence of degeneracy lifting in t(2g) states of interface Ti ions. Polarization dependence of intensities indicates the energy of d(xy) states is lower by similar to 1 eV than two other t(2g) states. The energy splitting is insensitive to epitaxial strain. The orbital reconstruction is induced by oxygen vacancies and confined to the interface within two unit cells, indicating charge compensation at the polar interfaces. DOI: 10.1103/PhysRevLett.110.017401X112723Nsciescopu
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