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61.
The relationship between the velocity of CMEs and the plasma temperature of the associated X-ray solar flares is investigated.The velocity of CMEs increases with plasma temperature(R=0.82)and photon index below the break energy(R=0.60)of X-ray flares.The heating of the coronal plasma appears to be significant with respect to the kinetics of a CME from the reconnection region where the flare also occurs.We propose that the initiation and velocity of CMEs perhaps depend upon the dominant process of conversion of the magnetic field energy of the active region to heating/accelerating the coronal plasma in the reconnected loops.Results show that a flare and the associated CME are two components of one energy release system,perhaps,magnetic field free energy. 相似文献
62.
Luciano Telesca Michele Lovallo S. K. Aggarwal P. K. Khan B. K. Rastogi 《Pure and Applied Geophysics》2016,173(1):125-132
A visibility graph (VG) is a rather novel statistical method in earthquake sequence analysis; it maps a time series into networks or graphs, converting dynamical properties of the time series into topological properties of networks. By using the VG approach, we defined the parameter window mean interval connectivity time <Tc>, that informs about the mean linkage time between earthquakes. We analysed the time variation of <Tc> in the aftershock-depleted catalogue of Kachchh Gujarat (Western India) seismicity from 2003 to 2012, and we found that <Tc>: i) changes through time, indicating that the topological properties of the earthquake network are not stationary; and, ii) appeared to significantly decrease before the largest shock (M5.7) that occurred on March 7, 2006 near the Gedi fault, an active fault in the Kachchh region. 相似文献
63.
Southern California is an increasingly urbanized hotspot for surfing, thus it is of great interest to assess the human illness risks associated with this popular ocean recreational water sport from exposure to fecal bacteria contaminated coastal waters. Quantitative microbial risk assessments were applied to eight popular Southern California beaches using readily available enterococcus and fecal coliform data and dose-response models to compare health risks associated with surfing during dry weather and storm conditions. The results showed that the level of gastrointestinal illness risks from surfing post-storm events was elevated, with the probability of exceeding the US EPA health risk guideline up to 28% of the time. The surfing risk was also elevated in comparison with swimming at the same beach due to ingestion of greater volume of water. The study suggests that refinement of dose-response model, improving monitoring practice and better surfer behavior surveillance will improve the risk estimation. 相似文献
64.
NETPATH‐WIN is an interactive user version of NETPATH, an inverse geochemical modeling code used to find mass‐balance reaction models that are consistent with the observed chemical and isotopic composition of waters from aquatic systems. NETPATH‐WIN was constructed to migrate NETPATH applications into the Microsoft WINDOWS® environment. The new version facilitates model utilization by eliminating difficulties in data preparation and results analysis of the DOS version of NETPATH, while preserving all of the capabilities of the original version. Through example applications, the note describes some of the features of NETPATH‐WIN as applied to adjustment of radiocarbon data for geochemical reactions in groundwater systems. 相似文献
65.
Pradeep K. Aggarwal Luis Araguas‐Araguas Manzoor Choudhry Michel van Duren Klaus Froehlich 《Ground water》2014,52(1):20-24
Uptake of atmospheric CO2 during sample collection and analysis, and consequent lowering of estimated ages, has rarely been considered in radiocarbon dating of groundwater. Using field and laboratory experiments, we show that atmospheric CO2 can be easily and rapidly absorbed in hyperalkaline solutions used for the extraction of dissolved inorganic carbon, resulting in elevated 14C measurements. Kinetic isotope fractionation during atmospheric CO2 uptake may also result in decrease of δ13C, leading to insufficient corrections for addition of dead carbon by geochemical processes. Consequently, measured 14C values of groundwater should not be used for age estimation without corresponding δ13C values, and historical 14C data in the range of 1 to 10% modern Carbon should be re‐evaluated to ensure that samples with atmospheric contamination are recognized appropriately. We recommend that samples for 14C analysis should be collected and processed in the field and the laboratory without exposure to the atmosphere. These precautions are considered necessary even if 14C measurements are made with an accelerator mass spectrometer. 相似文献
66.
Ramesh K. Kapoor B. B. Adiga S. P. Singal S. K. Aggarwal B. S. Gera 《Boundary-Layer Meteorology》1982,24(4):415-419
Observations made with a monostatic sodar and from a 120 m instrumented tower have been used to study the variations in the atmospheric boundary layer at Tarapur (19° 50 N, 72° 41 E) during the solar eclipse of February 16, 1980. Atmospheric instability was reduced below normal values during the eclipse but the atmosphere at no time became stable. 相似文献
67.
R. N. Nair Faby Sunny Manish Chopra L. K. Sharma V. D. Puranik A. K. Ghosh 《Environmental Earth Sciences》2014,71(3):1007-1019
High concentrations of several radionuclides were reported in the sea near the Fukushima Daiichi Nuclear Power Station (FDNPS) in Japan due to the nuclear accident that occurred on 11 March 2011. The main source of these concentrations was leakage of highly radioactive liquid effluent from a pit in the turbine building near the intake canal of Unit-2 of FDNPS through a crack in the concrete wall. In the immediate vicinity of the plant, seawater concentrations reached 68 MBq m?3 for 134Cs and 137Cs, and exceeded 100 MBq m?3 for 131I in early April 2011. These concentrations began to fall as of 11 April 2011 and, at the end of April, had reached a value close to 0.1 MBq m?3 for 137Cs. Following the nuclear accident, the Tokyo Electric Power Company (TEPCO) had initiated intense monitoring of the environment including the Pacific Ocean. Seawater samples were collected and the concentrations of few radionuclides were measured on a wide spatial and temporal scale. In this study, the measured concentrations of different radionuclides near the south discharge canal of the FDNPS were used to estimate their leakages into the Pacific Ocean. The method is based on estimating the release rates that reproduce the concentration of radionuclides in seawater at a chosen location using a two-dimensional advection–dispersion model in an iterative manner. The radioactive leakages were estimated as 5.68 PBq for 131I, 2.24 PBq for 134Cs and 2.25 PBq for 137Cs. Leakages were also estimated for 99mTc, 136Cs, 140Ba and 140La and they range between 0.02 PBq (99mTc) and 0.53 PBq (140Ba). It was estimated that about 11.28 PBq of radioactivity in total was leaked into the Pacific Ocean from the damaged FDNPS. Out of this, 131I constitutes 50.3 %; 134Cs 20 %; 137Cs 20 %; 140Ba 4.6 %; 136Cs 2.6 %; 140La 2.3 % and 99mTc 0.2 % of the total radioactive leakage. Such quantitative estimates of radioactive leakages are essential prerequisites for short-term and local-scale as well as long-term and large-scale radiological impact assessment of the nuclear accident. 相似文献
68.
Praveen K. Thakur Sreyasi Maiti Nanette C. Kingma V. Hari Prasad S. P. Aggarwal Ashutosh Bhardwaj 《Natural Hazards》2012,61(2):501-520
Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing
frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For
risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on
the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa,
India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were
interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural
types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood
depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage).
Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized
by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable
for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally
collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation. 相似文献
69.
Franklin W. Schwartz Ganming Liu Pradeep Aggarwal Cynthia M. Schwartz 《Ground water》2017,55(5):703-711
Concepts of simplicity and complexity in modeling have been explored in papers, editorials, and talks. The concept is not well understood because there are at least two flavors of simplicity. Modelers envision simplicity (i.e., elegant simplicity) as the sought‐after goal in modeling, but naïve simplicity, which is the focus of this paper, is commonly unrecognized and dangerous. The problem is that naïve or simple ideas are often mistaken for settled science and come with the prospect of being more wrong than right. The concept of the so‐called simplicity cycle, in relation to classical problems of carbon‐14 age and salinity in closed‐basin lakes, is used to illustrate these points. The emerging problems of water‐mosquitoes‐diseases show the value of mapping new problems to the simplicity cycle. Researchers can “know what they do not know” and avoid the dangers of naïve simplicity. 相似文献
70.
K. M. Aggarwal 《Solar physics》1984,90(2):281-290
Using configuration interaction wavefunctions, the excitation thresholds for the twelve lowest terms arising from the configurations 1s
22s
22p
2, 1s
22s2p
3, and 1s
22p
4 of Mgvii have been calculated. The same wavefunctions have been used to calculate the oscillator strengths for the optically allowed transitions in Mgvii. Combining these results with earlier published values for Oiii, Nev, Siix, Caxv, and Fexxi, oscillator strengths for other ions in the carbon isoelectronic sequence (F through Ni) have been predicted. The predicted values are found to be slightly lower when compared with the available published results. 相似文献