Zn(II) Ion Biosorption onto Surface of Eucalyptus Leaf Biomass: Isotherm,Kinetic, and Mechanistic Modeling

Bioremediation of Zn(II) by biosorption across aqueous phase on to surface of eucalyptus leaf powder has been investigated in present research work. The adsorptive potential of eucalyptus leaf powder was evaluated as function of pH, temperature, contact time, agitation rate and particle size. Maximum metal ion uptake and percentage removal capacity of eucalyptus leaf powder were 23.5 mg g⁻¹ and 94%, respectively, at optimized pH 5, 20 ± 1°C, contact time 6 h, particle size 0.5 mm and agitation rate 200 rpm. The biomass surface analysis revealed the fact that the biomass surface was heterogeneous and porous in nature. The functional groups like amine, amide, carboxyl, hydroxyl, and methyl groups, significantly important for metal ion binding were present on biomass surface in tremendous amount. Additionally, the Fourier transformation IR spectrum analysis of acid and base activated eucalyptus leaf biomass ruled out all the possibilities of the presence of surface functional groups mentioned above. The reaction rate was studied by applying two rate limiting models pseudo first and pseudo second order. Pseudo second order model was found to be more suitable (R² = 0.998) in comparison to pseudo first order (R² = 0.724). Adsorption equilibrium of batch stirred reaction data fitting shows the dominance of Langmuir isotherm (R² = 0.99) against Freundlich isotherm (R² = 0.887) model with equipartitional involvement of both film and intra particle diffusion as rate limiting steps at differential status of contact time.     

Rainfall Estimation from Combined Observations Using KALPANA-IR and TRMM- Precipitation Radar Measurements over Indian Region

In the present study an attempt has been made to improve the rainfall estimation technique developed recently by Mishra et al. (2009a, 2009b) based on KALPANA and Tropical Rainfall Measuring Mission (TRMM)-Precipitation Radar (PR) data over the Indian land and oceanic region. The algorithm for rainfall estimation was basically based on synergistically analyzing the thermal infra-red radiances from Kalpana/INSAT data along with the high resolution, horizontal and vertical rainfall estimates from PR. Presently the augmentation is based on the data base of precipitable water and relative humidity from National Centre for Environmental Prediction-Global forecast System (NCEP-GFS) data as a background field to correct for the biases in earlier algorithm. The algorithm is tested for many case studies of monsoon rainfall over India and adjoining oceanic regions. The rainfall from the present scheme is compared with the standard TRMM-3B42 rain product. The validation with the Automatic Weather Station (AWS) rain gauge and the Global Precipitation and Climatology Project (GPCP) version 2 rain products shows that the present scheme is able to retrieve the rainfall with a very good accuracy. These studies are aimed at the rainfall retrievals in near future from both INSAT-3D and Megha-Tropiques, IR and MW imagers respectively.     

Finite difference modeling of seismic wave propagation in monoclinic media

Reported in the present paper are the results of the study of propagation of SH waves in the plane of mirror symmetry of a monoclinic multilayered medium with displacement normal to the plane. Dispersion equation has been obtained analytically ussing Haskell’s matrix method, while the finite-difference method has been employed to model the SH-wave propagation to study its phase and group velocities. The stability analysis has been carried out to minimize the exponential growth of the error of finite difference approximation in order to make the finite difference method stable and convergent. Further, variations of phase velocity with respect to both wave number and dispersion parameter for different stability ratios in monoclinic media have been examined and shown graphically. The effect of change of stability ratio on the group velocity of the wave propagation has been also investigated. Likewise, the effects of change of dispersion parameter on phase velocity and the variation of frequency with increase of wave number have been graphically represented and discussed.     

Detrending methods for fluctuation analysis in hydrology: amendments and comparisons of methodologies

Detrending is a key step in the study of the scaling behaviors using Detrended Fluctuation Analysis (DFA) to explore the long‐range correlation of hydrological series. However, the irregular periodicity and various trends within hydrological series as a result of integrated influences of human activities such as construction of water reservoirs and human withdrawal of freshwater and climate changes such as alterations of precipitation changes in both space and time make difficult the selection of detrending methods. In this study, we attempt to address the detrending problem due to the important theoretical and practical merits of detrending in DFA‐based scaling analysis. In this case, with focus on the irregularity of the periodic trends, a modified DFA, varying parameter DFA (VPDFA), and its combination with adaptive detrending algorithm (ADA) are employed to eliminate the influences of irregular cycles on DFA‐based scaling results. The results indicate that, for streamflow series with no more than 20 cycles, VPDFA is recommended; otherwise, the combined method has to be employed. Comparison study indicates that the scaling behavior of the detrended observed streamflow series by average removed method, when compared to those by DFA, VPDFA, and ADA, is the one of the periodic residues around the averaged annual cycle for the entire series rather than that excluding all annual cycles. However, although the result by VPDFA for short observed streamflow record can well correspond to that for numerically simulated series, the scaling behavior obtained by combined method analyzing long record looks strange and is different from that by numerical analysis. We attribute this difference to the complicated hydrological structure and the possible hydrological alternation due to the increasing integrated impacts of human activities and human activities with the extending record. How to include the most of the important factors into the detrending procedure is still a challenging task for further study in the analysis of the scaling behavior of hydrological processes. Copyright © 2012 John Wiley & Sons, Ltd.     

Derivation of the Pearson type (PT) III distribution by using the principle of maximum entropy (POME)

The principle of maximum entropy (POME) was used to derive the Pearson type (PT) III distribution. The POME yielded the minimally prejudiced PT III distribution by maximizing the entropy subject to two appropriate constraints which were the mean and the mean of the logarithm of real values about a constant >0. This provided a unique method for parameter estimation. Historical flood data were used to evaluate this method and compare it with the methods of moments and maximum likelihood estimation.     

Emergent universe with scalar (or tachyonic) field in higher derivative theory

We consider a spatially homogeneous and isotropic flat Robertson-Walker model filled with a scalar (or tachyonic) field minimally coupled to gravity in the framework of higher derivative theory. We discuss the possibility of the emergent universe with normal and phantom scalar fields (or normal and phantom tachynoic fields) in higher derivative theory. We find the exact solution of field equations in normal and phantom scalar fields and observe that the emergent universe is not possible in normal scalar field as the kinetic term is negative. However, the emergent universe exists in phantom scalar field in which the model has no time-like singularity at infinite past. The model evolves into an inflationary stage and finally admits an accelerating phase at late time. The equation of state parameter is found to be less than −1 in early time and tends to −1 in late time of the evolution. The scalar potential increases from zero at infinite past to a flat potential in late time. More precisely, we discuss the particular case for phantom field in detail. We also carry out a similar analysis in case of normal and phantom tachyonic field and observe that only phantom tachyonic field solution represents an emergent universe. We find that the coupling parameter of higher order correction affects the evolution of the emergent universe. The stability of solutions and their physical behaviors are discussed in detail.     

Comment on “The stability of UO2OH+ and UO2(HPO4)22− complexes at 25°C” by G. Dongarra and D. Langmuir

Equilibrium calculations have shown that all the solutions in the experiments of Dongarra and Langmuir (1980) were super-saturated with respect to uranyl triphosphate; the degree of super-saturation varied from 3 to 857. In spite of the super-saturation, for all of their experiments n? and molal % UO₂(HPO⁴)₂^2? have been found to be <0.5 and <12 respectively. Similarly in all of their experiments 88–98% of ∑U(VI) existed as UO₂²⁺ or hydroxo complexes. Based on the analysis of their data it has been shown that their experimental conditions were not appropriate for determining the stability constant of UO₂(HPO⁴)₂^2?. The significance of careful design of experiments has been demonstrated. The uncertainty in log β (±0.2) as reported by these authors is too small in view of the very small $\text{n}\text{?}$ as well as negligible pH change during titrations. Furthermore, the fact that the β determined by Dongarra and Langmuir is very close to that of Moskvin et al. (1967) certainly does not serve to validate the work of Dongarra and Langmuir, since Dongarra and Langmuir, as well as this writer, have found several problems in the work of Moskvin et al.     

Frequency analysis of droughts using the Plackett copula and parameter estimation by genetic algorithm

This study aims to model the joint probability distribution of drought duration, severity and inter-arrival time using a trivariate Plackett copula. The drought duration and inter-arrival time each follow the Weibull distribution and the drought severity follows the gamma distribution. Parameters of these univariate distributions are estimated using the method of moments (MOM), maximum likelihood method (MLM), probability weighted moments (PWM), and a genetic algorithm (GA); whereas parameters of the bivariate and trivariate Plackett copulas are estimated using the log-pseudolikelihood function method (LPLF) and GA. Streamflow data from three gaging stations, Zhuangtou, Taian and Tianyang, located in the Wei River basin, China, are employed to test the trivariate Plackett copula. The results show that the Plackett copula is capable of yielding bivariate and trivariate probability distributions of correlated drought variables.     

Evaluation of pan evaporation modeling with two different neural networks and weather station data

This study evaluates neural networks models for estimating daily pan evaporation for inland and coastal stations in Republic of Korea. A multilayer perceptron neural networks model (MLP-NNM) and a cascade correlation neural networks model (CCNNM) are developed for local implementation. Five-input models (MLP 5 and CCNNM 5) are generally found to be the best for local implementation. The optimal neural networks models, including MLP 4, MLP 5, CCNNM 4, and CCNNM 5, perform well for homogeneous (cross-stations 1 and 2) and nonhomogeneous (cross-stations 3 and 4) weather stations. Statistical results of CCNNM are better than those of MLP-NNM during the test period for homogeneous and nonhomogeneous weather stations except for MLP 4 being better in BUS-DAE and POH-DAE, and MLP 5 being better in POH-DAE. Applying the conventional models for the test period, it is found that neural networks models perform better than the conventional models for local, homogeneous, and nonhomogeneous weather stations.     

基于模糊集理论的降雨不确定性传播影响研究

基于模糊集理论,耦合遗传算法,量化分析降雨的量级、空间分布和时程分配产生的不确定性对流量模拟的影响。雨量量级的不确定性使用模糊集概念表示,运用遗传算法对时段雨量在时间上进行随机解集,并通过在各子流域上采用不同的时间解集模式以同时考虑降雨时程分配和空间分布不确定性。应用TOPMODEL对资水流域新宁水文站洪水过程进行模拟研究,结果表明,雨量不确定性的传播对洪水预报的影响处于主导地位,降雨时空分布引起的不确定性对洪水模拟的影响次之。此外,通过对1 h和0.5 h解集结果的比较发现,本文中采用1 h作为模拟的时间步长已可以较充分反映雨量的时间变异性。