Error minimization of polynomial approximation of Delta T     

Islam Sana  Sadiq Muhammad  Qureshi Muhammad Shahid 《Journal of Astrophysics and Astronomy》2008,29(3-4):363-366

The difference between Universal time (UT) and Dynamical time (TD), known as Delta T (ΔT) is tabulated for the first day of each year in the Astronomical Almanac. During the last four centuries it is found that there are large differences between its values for two consecutive years. Polynomial approximations have been developed to obtain the values of ΔT for any time of a year for the period AD 1620 to AD 2000 (Meeu 2000) as no dynamical theories describe the variations in ΔT. In this work, a new set of polynomials for ΔT is obtained for the period AD 1620 to AD 2007 that is found to produce better results compared to previous attempts.  相似文献   

Predictability performance enhancement for suspended sediment in rivers:Inspection of newly developed hybrid adaptive neuro-fuzzy system model     

Rana Muhammad Adnan  Zaher Mundher Yaseen  Salim Heddam  Shamsuddin Shahid  Aboalghasem Sadeghi-Niaraki  Ozgur Kisi 《国际泥沙研究》2022,37(3):383-398

Reliable modeling of river sediments transport is important as it is a defining factor of the economic viability of dams, the durability of hydroelectric-equipment, river susceptibility to pollution, suitability for navigation, and potential for aesthetics and fish habitat. The capability of a new machine learning model, fuzzy c-means based neuro-fuzzy system calibrated using the hybrid particle swarm optimization-gravitational search algorithm（ANFIS-FCM-PSOGSA） in improving the estimation accur...  相似文献   

Assessment of Heavy Metal Contamination in Soil and Groundwater at Leather Industrial Area of Kasur,Pakistan   总被引：1，自引：0，他引：1       下载免费PDF全文

Muhammad Afzal  Ghulam Shabir  Samina Iqbal  Tanveer Mustafa  Qaiser Mahmood Khan  Zafar Mahmood Khalid 《洁净——土壤、空气、水》2014,42(8):1133-1139

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Simultaneous Degradation of Trichloroethylene and Toluene by Burkholderia cepacia G4 and the Effect of Biotransformation on Bacterial Density          下载免费PDF全文

Shanawar Hamid  Muhammad Tahir Amin  Abdulrahman Ali Alazba  Umair Manzoor 《洁净——土壤、空气、水》2014,42(7):998-1003

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Adaptive state estimation of groundwater contaminant boundary input flux in a 2-dimensional aquifer     

Muhammad Malik Nauman  Murtuza Mehdi  Asif Iqbal  Muhammad Saifullah Abu Bakar  Brahim Aissa  Dk Nur Afiqah Jalwati Puteri  Amer Farhan Rafique 《地下水科学与工程》2019,(4):373-382

In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.  相似文献   

A Periglacial Palaeoenvionment in the Upper Carboniferous–Lower Permian Tobra Formation of the Salt Range, Pakistan     

Irfan U. JAN  Shahid IQBAL  Sarah J. DAVIES  Jan A. ZALASIEWICZ  Michael H. STEPHENSON  Michael WAGREICH  Muhammad HANEEF  Muhammad HANIF  Sajjad AHMAD 《《地质学报》英文版》2017,91(3):1063-1078

The Upper Carboniferous—Lower Permian(Upper Pennsylvanian-Asselian) Tobra Formation is exposed in the Salt and Trans Indus ranges of Pakistan.The formation exhibits an alluvial plain(alluvial fan-piedmont alluvial plain) facies association in the Salt Range and Khisor Range.In addition,a stream flow facies association is restricted to the eastern Salt Range.The alluvial plain facies association is comprised of clast-supported massive conglomerate(Gmc),diamictite(Dm)facies,and massive sandstone(Sm) Hthofacies whereas the stream flow-dominated alluvial plain facies association includes fine-grained sandstone and siltstone(Fss),fining upwards pebbly sandstone(Sf),and massive mudstone(Fm) Hthofacies.The lack of glacial signatures(particularly glacial grooves and striatums) in the deposits in the Tobra Formation,which are,in contrast,present in their timeequivalent and palaeogeographically nearby strata of the Arabian peninsula,e.g.the AI Khlata Formation of Oman and Unayzah B member of the Saudi Arabia,suggests a pro-to periglacial,i.e.glaciofluvial depositional setting for the Tobra Formation.The sedimentology of the Tobra Formation attests that the Salt Range,Pakistan,occupied a palaeogeographic position just beyond the maximum glacial extent during Upper Pennsylvanian-Asselian time.  相似文献   

Cenozoic development of southwestern Malay Basin: new insights from subsidence analysis and thermal history     

Muhammad Hassaan  Swapan Kumar Bhattacharya  Manoj Joseph Mathew  Numair Ahmed Siddiqui 《Arabian Journal of Geosciences》2017,10(8):192

Subsidence and thermal history analysis are carried out in order to investigate the Cenozoic basin development of the southwestern (Tenggol Arch and basinal side) part of the Malay basin. Structurally, the southwestern part consists of normal faults and horst and graben geometry. Tectonic subsidence curves show that the basinal side is more active than the Tenggol Arch due to movement along normal faults. Cenozoic development initiated with the deposition of sedimentary Units M & L (Oligocene) and the activation of the Tenggol fault on the basinal side. Several periods of accelerated and slow subsidence are observed during the Oligocene to Middle Miocene that could be associated with changes in regional stresses caused by pulsating plate movement. The Malay Basin experienced inversion throughout the Middle to Late Miocene related to mantle induced slab avalanche effect, causing relatively higher tectonic subsidence rates on the Tenggol Arch compared to the basinal side, suggesting that the Tenggol Arch is less affected by inversion than the basinal side. After a period (Late Miocene) of non-deposition, the basin was reactivated (Pliocene to recent) due to thermal relaxation with thick sedimentation. Paleo heat flows estimated utilizing a novel technique introduced in this study and present day heat flow calibrated using BHT data further supports our results, in that increase in heat flow is related to rapid tectonic subsidence. An anomalously high heat pulse affected the basin during inversion and could be the cause of meta-sediment formation whereas present heat flows, although high compared to average basins, shows decreasing trend from the inversion period.  相似文献   

Dam-break risk analysis of the Attabad landslide dam in Pakistan and emergency countermeasures   总被引：1，自引：0，他引：1  

Xiaoqing Chen  Peng Cui  Yong You  Zunlan Cheng  Asif Khan  Chengyin Ye  Shu Zhang 《Landslides》2017,14(2):675-683

The Attabad landslide dam caused significant property losses and many human casualties in Pakistan, and also greatly affected the operation of the China-Pakistan Karakoram Highway (KKH). This paper discusses the risk of dam breach and hazards to the KKH project construction site following a dam breach. The paper examines the following three topics. (1) The geomorphologic dimensionless blockage index (DBI) and the analogy method were used to analyze the stability of the Attabad landslide dam. The long-term behaviors of landslide dams downstream of the Attabad landslide dam indicate that the risk of a dam breach exists, but the probability of a total dam failure is low. (2) The peak discharge of a potential breach of the Attabad landslide dam was calculated for scenarios in which 1/4, 1/3, 1/2, and total failure of the dam was breached. The potential breach discharge decreases with the downstream distance. (3) The potential impacts of the landslide dam breach on the KKH project construction site were analyzed. Based on the composition of the landslide dam, the probability of a 1/3 dam breach is high. To ensure the safety of downstream areas, disaster preparedness plans that correspond to the 1/2 dam breach scenario should be developed. Based on experience in addressing the landslide dam that was caused by the Wenchuan Earthquake, artificial controlled drainage measures are suggested and provide a technical reference for addressing the Attabad landslide dam and achieving recovery and normal operation of KKH.  相似文献   

Recent developments in immobilizing titanium dioxide on supports for degradation of organic pollutants in wastewater- A review     

M. H. Alhaji  K. Sanaullah  A. Khan  A. Hamza  A. Muhammad  M. S. Ishola  A. R. H. Rigit  S. A. Bhawani 《International Journal of Environmental Science and Technology》2017,14(9):2039-2052

This review focuses on the various types of supports used for immobilization of titanium dioxide nanomaterial catalyst for degradation of organic pollutants in wastewater. Several supports suitable to particular immobilization technique used for the degradation of pollutants in wastewater streams are explained. In general, a coating of catalyst on supports is carried out either by physical (e.g., thermal treatment) or by chemical (e.g., sol–gel). Among a range of the supports used, some of the prominent ones include glass, silica, activated carbon, stainless steel, cellulose, clay. Also, characterization methods in use such as X-ray diffraction, transmission electron microscope, scanning electron microscope, and UV-spectroscopy are discussed. The operating parameters such as temperature for the selected immobilization techniques are also explained.  相似文献   

Characterization of locally available soil as a liner material for solid waste landfills in Sri Lanka     

Hafiz Muhammad Awais Rashid  J. A. D. K. Wanigarathna  L. C. Kurukulasuriya  N. H. Priyankara  A. M. N. Alagiyawanna  Takeshi Saito  Ken Kawamoto 《Environmental Earth Sciences》2017,76(11):396

This study aimed to develop a low-cost and effective clay liner material for solid waste landfills in Sri Lanka. A locally available clayey soil and its admixtures with 5 and 10% bentonite were examined for this purpose. Laboratory experiments to determine soil plasticity and swell index were carried out on the tested samples. Hydraulic conductivity (k) tests were carried out in the laboratory using water and an aqueous solution of CaCl₂ on unconsolidated samples prepared by either dry or slurry packing and pre-consolidated samples with five different consolidation pressures (p) from 10 to 200 kPa. Measured liquid limits for tested admixtures increased with increasing bentonite contents and correlated well with measured values of the swell index. The difference in permeant solutions had little effect on measured k values for both unconsolidated and pre-consolidated samples. The hydraulic conductivities were highly affected by changing p, i.e., the k values decreased on two orders of magnitude as p increased from 10 to 200 kPa. The Kozeny–Carman equation, a theoretical permeability model that expresses the k-porosity relationship, was applied to measured data including reported values. Results showed the Kozeny–Carman equation captured well the porosity-dependent k values for tested soils and their admixtures with bentonite under a wide range of void ratios, suggesting that the Kozeny–Carman equation is a useful tool to estimate the magnitude of k values for differently compacted soil and its bentonite admixtures.  相似文献