A Study on the Surface Wettability of Clastic Rocks with Potential Application for CO2 Storage Sites     

Umar  Bappah Adamu  Gholami  Raoof  Raza  Arshad  Downey  William Samuel  Sarmadivaleh  Mohammad  Shah  Afroz A.  Nayak  Prasanta 《Natural Resources Research》2020,29(3):2051-2061

Natural Resources Research - There have been many studies carried out in the past decades attempting to develop strategies for a safe injection of CO2 into storage sites without leakage and...  相似文献   

Implications of Kali-Hindon inter-stream aquifer water balance for groundwater management in western Uttar Pradesh     

Rashid Umar  M. Muqtada A. Khan  Izrar Ahmed  Shakeel Ahmed 《Journal of Earth System Science》2008,117(1):69-78

The Kali-Hindon inter-stream region extends over an area of 395 km² within the Ganga-Yamuna interfluve. It is a fertile tract for sugarcane cultivation. Groundwater is a primary resource for irrigation and industrial purposes. In recent years, over-exploitation has resulted in an adverse impact on the groundwater regime. In this study, an attempt has been made to calculate a water balance for the Kali-Hindon inter-stream region. Various inflows and outflows to and from the aquifer have been calculated. The recharge due to rainfall and other recharge parameters such as horizontal inflow, irrigation return flow and canal seepage were also evaluated. Groundwater withdrawals, evaporation from the water table, discharge from the aquifer to rivers and horizontal subsurface outflows were also estimated. The results show that total recharge into the system is 148.72 million cubic metres (Mcum), whereas the total discharge is 161.06 Mcum, leaving a deficit balance of −12.34 Mcum. Similarly, the groundwater balance was evaluated for the successive four years. The result shows that the groundwater balance is highly sensitive to variation in rainfall followed by draft through pumpage. The depths to water level are shallow in the canal-irrigated northern part of the basin and deeper in the southern part. The pre-monsoon and post-monsoon water levels range from 4.6 to 17.7 m below ground level (bgl) and from 3.5 to 16.5 m bgl respectively. It is concluded that the groundwater may be pumped in the canal-irrigated northern part, while withdrawals may be restricted to the southern portion of the basin, where intense abstraction has led to rapidly falling water table levels.  相似文献   

Hydrogeological framework and water balance studies in parts of Krishni–Yamuna interstream area, Western Uttar Pradesh, India     

Izrar Ahmed  Rashid Umar 《Environmental Geology》2008,53(8):1723-1730

The Krishni–Yamuna interstream area is a micro-watershed in the Central Ganga Plain and a highly fertile track of Western Uttar Pradesh. The Sugarcane and wheat are the major crops of the area. Aquifers of Quaternary age form the major source of Irrigation and municipal water supplies. A detailed hydrogeological investigation was carried out in the study area with an objective to assess aquifer framework, groundwater quality and its resource potential. The hydrogeological cross section reveals occurrence of alternate layers of clay and sand. Aquifer broadly behaves as a single bodied aquifer down to the depth of 100 m bgl (metre below ground level) as the clay layers laterally pinch out. The depth to water in the area varies between 5 and 16.5 m bgl. The general groundwater flow direction is from NE to SW with few local variations. An attempt has been made to evaluate groundwater resources of the area. The water budget method focuses on the various components contributing to groundwater flow and groundwater storage changes. Changes in ground water storage can be attributed to rainfall recharge, irrigation return flow and ground water inflow to the basin minus baseflow (ground water discharge to streams or springs), evapotranspiration from ground water, pumping and ground water outflow from the basin. The recharge is obtained in the study area using Water table fluctuation and Tritium methods. The results of water balance study show that the total recharge in to the interstream region is of the order of 185.25 million m³ and discharge from the study area is of the order of 203.24 million m³, leaving a deficit balance of −17.99 million m³. Therefore, the present status of groundwater development in the present study area has acquired the declining trend. Thus, the hydrogeological analysis and water balance studies shows that the groundwater development has attained a critical state in the region.  相似文献   

Nonlinear response of a moored buoy     

A. Umar  T. K. Datta 《Ocean Engineering》2003,30(13):1625-1646

The nonlinear dynamic analysis of a multipoint slack moored buoy is performed under the action of first and second order wave forces. The nonlinearity of the system is caused by the geometric nonlinearity of the mooring lines. The resulting nonlinear equation of motion is solved by an incremental time marching scheme. The nonlinear responses of the system are analysed to investigate different kinds of dynamic instability phenomena that may arise due to the nonlinearity of the system. As an illustrative example, a hollow cylindrical buoy anchored to the sea bed by means of six slack mooring lines is considered. The responses of the system are obtained and analysed for three regular waves namely, 5 m/5 s, 12 m/10 s and 18 m/15 s. The results of the study show that different kinds of instability phenomena like nT subharmonic oscillations, symmetry breaking bifurcation and aperiodic responses may occur in slack mooring systems. Further, a second order wave force may considerably influence the dynamic stability of such systems.  相似文献   

A methodology for assessing the reliability of taut and slack mooring systems against instability     

A.A. Shah  A. Umar  N.A. Siddiqui   《Ocean Engineering》2005,32(10):1216-1234

In the present study, a methodology for reliability assessment of slack and taut mooring systems against instability has been presented. For this purpose, first, stability analysis of slack and taut mooring systems has been carried out and instable regions are obtained using procedure available in the literature. Having known the instable region(s), methodology for reliability assessment has been proposed which is based on Monte Carlo Simulation technique. After using the proposed methodology, probabilities of failure and reliability indices has been obtained for the above systems. Some parametric studies, such as, effect of lower and upper limits of instability and effect of frequency range of generations are also included to obtain the results of practical interest.  相似文献   

Contesting ‘Local’ Commemoration of the Second World War: the case of the Changi Chapel and Museum in Singapore     

Hamzah Muzaini  Brenda S. A. Yeoh 《The Australian geographer》2005,36(1):1-17

This paper concerns the performance of national war memory at the Changi Chapel and Museum, a site honouring the many prisoners interned in Japanese-Occupied Singapore—especially at Changi—during the Second World War. In the light of the global nature of ‘the Changi story’, and the predominantly transnational nature of its present in situ memorialisation, we first examine how the Singapore state has sought to ‘localise’ the site to make it equally appealing to Singaporeans, as a place where a sense of their ‘shared history’ may be invoked. We then explore the Singaporeans' views about the site and its reconfiguration as a national icon, arguing how the state's task of ‘localising’ the site has been a vexed process due to myriad factors such as ethnic and religious plurality, and the already foreign-centric bias of prevailing knowledge about Changi. Following that, we show how this performance of national memory is also inflected by Australia's national remembrance of the same event. More broadly, we highlight the contested process of ‘localising’ such war memoryscapes as national iconography, suggesting how it may be more fruitful to conceive them as ‘international memoryscapes’, or places to which all individuals can relate regardless of race or national affiliations.  相似文献   

Motion in the ER3BP with an oblate primary and a triaxial stellar companion     

Aishetu Umar  Aminu Abubakar Hussain 《Astrophysics and Space Science》2016,361(10):344

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Investigation of seasonal droughts and related large-scale atmospheric dynamics over the Potwar Plateau of Pakistan     

N. U. Ain  M. Latif  K. Ullah  S. Adnan  R. Ahmed  M. Umar  M. Azam 《Theoretical and Applied Climatology》2020,140(1):69-89

As a result of climate change and unsustainable land use management in the recent past, droughts have become one of the most devastating climatic hazards whose impacts may prolong from months to years. This study presents analysis of droughts for two major cropping seasons, i.e., Kharif (May–September) and Rabi (October–April), over the Potwar Plateau of Pakistan. The analysis is performed using various datasets viz. observational, reanalysis, and Regional Climate Models (RCMs), for the past (1981–2010) and future (2011–2100) time periods. The following two methods for the identification of dry and wet years, also referred to as drought and wetness, are applied: (1) the percentile rank approach and (2) the drought indices, Standardized Precipitation Index (SPI) and Reconnaissance Drought Index (RDI). Future projections of droughts are investigated using RCM (RegCM4.4 and RCA4) outputs from CORDEX South Asia domain under two Representative Concentration Pathway (RCP) scenarios, RCP4.5 and RCP8.5. Generally, the indices show non-significant decreasing trends of drought severity in the recent past for all cases; however, significant increasing trends are observed for annual (0.006) and Kharif (0.007) cases under RCP4.5 scenario. The analysis of large-scale atmospheric dynamics suggests the significant role of low-level geopotential height anomalies over Tibetan Plateau (northwest of Pakistan) during Kharif (Rabi) season in controlling drought occurrence by transporting moisture from the Bay of Bengal (Arabian Sea). Moreover, composites of vertically integrated moisture transport, moisture flux convergence/divergence, and precipitable water anomalies show their marked contribution in maintaining the drought/wetness conditions over the Potwar region.  相似文献   

Indonesia's archipelagic regime: Implications for Malaysia     

B.A. Hamzah 《Marine Policy》1984,8(1):30-43

This article examines Indonesian-Malaysian relations in the light of Indonesia's new archipelagic regime. Archipelagos are defined and the rights and duties of archipelagic states under the Law of the Sea Convention are outlined. Indonesian-Malaysian relations from the 1974 Memorandum of Understanding to the 1982 bilateral treaty are described. The author examines the implications of an Indonesian suspension of passage on Malaysian transport, submarine cables and pipelines, fishing, oil and gas, and search and rescue. The author concludes by indicating how the two countries should adjust to the regime.  相似文献   

Performance of rate detector algorithms for an integrated GPS/INS system in the presence of slowly growing error     

Umar I. Bhatti  Washington Y. Ochieng  Shaojun Feng 《GPS Solutions》2012,16(3):293-301

In the Global Positioning System, there is no provision for real-time integrity information within the Standard Positioning Service, by design. However, in safety critical sectors like aviation, stringent integrity performance requirements must be met. This can be achieved using the special augmentation systems or RAIM (Receiver Autonomous Integrity Monitoring) or both. RAIM, the most cost-effective method relies on data consistency, and therefore requires redundant measurements for its operation. An external aid to provide this redundancy can be in the form of an Inertial Navigation system. This should enable continued performance even when no redundant satellite measurements are available. An algorithm presented in previous papers by the authors detects the rate of slowly growing errors. The algorithm was shown to be effective for early detection of slowly growing errors that belong to the class of most difficult to detect errors. Firstly, rate detector is tested for varying faults. Secondly, real data are used to validate the rate detector algorithm. The data are extensively analyzed to ascertain whether it is suitable for integrity and fault diagnostics. A modification to the original rate detector algorithm is suggested by addition of a bias state to the dynamic model. The performance is then compared with the existing techniques and substantial improvement is shown.  相似文献