The first electric field pulse of cloud and cloud-to-ground lightning discharges     

Noor Azlinda Ahmad  M. Fernando  Z.A. Baharudin  M. Rahman  V. Cooray  Ziad Saleh  Joseph R. Dwyer  Hamid K. Rassoul 《Journal of Atmospheric and Solar》2010,72(2-3):143-150

In this study, the first electric field pulse of cloud and cloud-to-ground discharges were analyzed and compared with other pulses of cloud discharges. Thirty eight cloud discharges and 101 cloud-to-ground discharges have been studied in this analysis. Pulses in cloud discharges were classified as ‘small’, ‘medium’ and ‘large’, depending upon the value of their relative amplitude with respect to that of the average amplitude of the five largest pulses in the flash. We found that parameters, such as pulse duration, rise time, zero crossing time and full-width at half-maximum (FWHMs) of the first pulse of cloud and cloud-to-ground discharges are similar to small pulses that appear in the later stage of cloud discharges. Hence, we suggest that the mechanism of the first pulse of cloud and cloud-to-ground discharges and the mechanism of pulses at the later stage of cloud discharges could be the same.  相似文献   

Long-period eccentricity control on sedimentary sequences in the continental Madrid Basin (middle Miocene,Spain)   总被引：1，自引：0，他引：1  

Hemmo A. Abels  Hayfaa Abdul Aziz  Wout Krijgsman  Sander J.B. Smeets  Frederik J. Hilgen 《Earth and Planetary Science Letters》2010,289(1-2):220-231

The middle Miocene Valdearenas–Muduex section in the internally-drained, continental Madrid Basin (central Spain) is dated bio-magnetostratigraphically between 15.2 Ma and 11.5 Ma. The section contains two formation-scale, sedimentary sequences, that both consist of a siliciclastic lower part and a calcareous upper part. Siliciclastic sedimentation took place in distal floodplain and fluvial environments, while limestones resulted from carbonate precipitation in calcic soil profiles and in ephemeral lacustrine water bodies. Spectral analysis of the L* colour time series points to the influence of the ～ 405-kyr and 0.97-Myr eccentricity cycles, while the bases of the two calcareous intervals correlate to successive minima of the 2.4-Myr eccentricity cycle. The 405-kyr cycle lags maximum eccentricity, whereas the 0.97 and 2.4-Myr cycles lag minimum eccentricity, each by approximately a quarter of a cycle. No obliquity forcing is detected. The observed orbital configuration of 2.4-Myr minima at the base of limestone-dominated intervals is similar to a previously documented Late Miocene shift in the Teruel Basin of northeast Spain. Our results indicate that long-period eccentricity climate forcing may well be a significant player on long, tectonic time scales in continental basin fill.  相似文献   

Factors encouraging sustainability integration into institutions of higher education     

K. S. Chiong  Z. F. Mohamad  A. R. Abdul Aziz 《International Journal of Environmental Science and Technology》2017,14(4):911-922

In view of the mountainous evidence on destruction of environmental quality and societal well-being as a consequence of rapid economic development, sustainability has gained vast attention from the community and industrial players. Tertiary education is a platform through which sustainability can be inculcated within the society as it imparts knowledge and provides various trainings. There has been extensive research on factors that encourage sustainability integration into Institutions of Higher Education in the last decade. However, majority of the previous publications only discuss one or two factors exclusively and there is no literature that summarizes and discusses such factors in a collective manner. This paper provides an overview of the main factors that encourage sustainability integration into Institutions of Higher Education in the last decade. It aims at providing a one-stop reference for future researchers who need a reference on factors that encourage sustainability integration into Institutions of Higher Education, especially those who are interested in conducting a progressive research in this context. Accordingly, a review of relevant publications from year 2000 and above was conducted and it was found that there are generally eight main factors, which encourage sustainability integration into Institutions of Higher Education, which are: (1) integration into curricula; (2) suitable pedagogy; (3) campus management; (4) research; (5) opportunities provision; (6) availability of social capital; (7) awareness level; and (8) community outreach. There is no indicator on the impact level of these factors, and thus, it is suggested that relevant research can be conducted in future.  相似文献   

Analytic network process (ANP)-based spatial decision support system (SDSS) for sustainable tourism planning in Cameron Highlands,Malaysia     

Mansir Aminu  Abdul Nasir Matori  Khamaruzaman Wan Yusof  Amirhossein Malakahmad  Rosilawati Binti Zainol 《Arabian Journal of Geosciences》2017,10(13):286

Sustainable approach to tourism development is rarely addressed among authorities and participants. This research presents an approach based on an integrated use of analytic network process (ANP) and geographic information system (GIS) for sustainable tourism planning in Cameron Highlands, Malaysia. ANP was utilized to evaluate the relative priorities for the sustainable tourism development of the highlands based on chosen criteria. ANP results were then transferred into GIS environment and attached to their respective criterion maps. Subsequently, GIS-based sustainable tourism map was generated, which defines the various types of tourism activities that are compatible with the highlands according to the sensitivity of the highland’s environment. The final output was validated using Cameron Highlands Local Plan.  相似文献   

Assessment of trace elements of groundwater and their spatial distribution in Rangpur district,Bangladesh     

A. R. M. Towfiqul Islam  Shuanghe Shen  Md. Bodrud-Doza  M. Atiqur Rahman  Samiran Das 《Arabian Journal of Geosciences》2017,10(4):95

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Drought analysis and its implication in sustainable water resource management in Barind area,Bangladesh     

A. T. M. Sakiur Rahman  Chowdhury Sarwar Jahan  Quamrul Hasan Mazumder  Md. Kamruzzaman  Takahiro Hosono 《Journal of the Geological Society of India》2017,89(1):47-56

The study analyzes drought using Standardized Precipitation Index (SPI) and Mann-Kendall (MK) Trend Test in the context of the impacts of drought on groundwater table (GWT) during the period 1971-2011 in the Barind area, Bangladesh. The area experienced twelve moderate to extreme agricultural droughts in the years 1972, 1975, 1979, 1982, 1986, 1989, 1992, 1994, 2003, 2005, 2009 and 2010. Some of them coincide with El Niño events. Hydrological drought also occurred almost in the same years. However, relationship between all drought events and El Niño is not clear. Southern and central parts of the area frequently suffer from hydrological drought, northern part is affected by agricultural drought. Trends in SPI values indicate that the area has an insignificant trend towards drought, and numbers of mild and moderate drought are increasing. GWT depth shows strong correlation with rainy season SPI values such that GWT regaining corresponds with rising SPI values and vice versa. However, 2000 onwards, GWT depth is continuously increasing even with positive SPI values. This is due to over-exploitation of groundwater and changes in cropping patterns. Agricultural practice in Barind area based on groundwater irrigation is vulnerable to drought. Hence, adaptation measures to minimize effects of drought on groundwater ought to be taken.  相似文献   

The interrelationship between travel behavior and life choices in adapting to flood disasters     

Qing-Chang Lu  Junyi Zhang  A. B. M. Sertajur Rahman 《Natural Hazards》2017,85(2):1005-1022

Disasters resulting from climate change are shown to be important determinants of people’s life choice decisions. In the literature, travel behavior choice and life choices are usually addressed separately under disasters such as flood and cyclone. However, travel behavior may be interdependent with other life choices, jointly shaping people’s adaptation decisions. To this end, the paper advances the literature by exploring the interrelationship between changes in travel behavior and job and residential location under flood disasters, while separating coastal and inland observations. For this purpose, a stated preference survey was conducted in 14 cities of Bangladesh in early 2013. An analysis approach based on structural equation modeling was developed to investigate the correlations between travel behavior change and job and residential location changes. Model estimation results suggest that flood impacts have significant influences on inland people’s life choices, while coastal people’s life choices are mainly affected by flood adaptation responses and attitudes. Significant correlations between travel behavior change and job and residential location changes are found for both observations. Moreover, both coastal and inland people tend not to change residential locations if changes in job location and travel behavior are made. Inland people may not change travel behavior if their job and/or residential locations are changed, but coastal people’s job and residential location changes are associated with changes in travel behavior. Travel behavior change is found to have more of an effect on residential location change than job location change in both regions. These findings conclude that the two-way relationship between travel behavior and life choices should be taken into account in future analyses, and thus adaptation policies to climate change disasters could be better linked with people’s behavioral responses.  相似文献   

A semi-analytical method for the wave-induced seabed response     

M. S. Rahman  Khalid El-Zahaby  John Booker 《国际地质力学数值与分析法杂志》1994,18(4):213-236

A general semi-analytical method is presented for the analysis of seabed response under wave action during a storm. The seabed is idealized as a poro-elastic medium filled with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Biot's theory. The analysis for the response of homogeneous seabed of finite thickness under a plane progressive wave is developed first, followed by an extension for the case of a layered seabed. A generalization for three-dimensional response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a structure. Some numerical examples illustrating the proposed analyses are also presented.  相似文献   

Response of the Dupi Tila aquifer to intensive pumping in Dhaka,Bangladesh     

Brian?L.?MorrisEmail author  Ashraf?Ali?Seddique  Kazi?Matin?Ahmed 《Hydrogeology Journal》2003,11(4):496-503

This paper focuses on the water-quantity issues facing Dhaka because of the rapid exploitation of the Dupi Tila aquifer. Dhaka is one of the world's largest groundwater-dependent cities, relying on water withdrawn from this underlying semiconfined sand aquifer. A meteoric rise in well construction in both the private and public sectors in recent years has produced an estimated 1,300 boreholes that tap the aquifer in urban and suburban parts of the city. Analysis of construction records for public-supply wells drilled between 1970 and 2000 shows that water levels are falling in several areas of the city despite apparently favorable recharge conditions. The productivity of boreholes as measured by specific capacity has also declined significantly. Even though the aquifer system is vital to the infrastructure of the city it remains a poorly quantified resource, and until this is resolved by investment in evaluation studies, attempts to efficiently manage the resource in a sustainable way will be frustrated.

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Resumen Este artículo trata de los aspectos cuantitativos relacionados con la sobreexplotación del acuífero de Dupi Tila, que suministra a la ciudad de Dhaka (Bangladesh). Ésta es una de las mayores ciudades del mundo con dependencia de las aguas subterráneas, y se abastece de un acuífero semiconfinado formado por arenas. El aumento meteórico en la construcción de pozos durante los últimos años, tanto en el sector público como en el privado, ha provocado que haya unas 1.300 captaciones del acuífero en las zonas urbana y suburbana de la ciudad. El análisis de los registros constructivos de pozos de abastecimiento público entre 1970 y 2000 muestra que los niveles piezométricos están descendiendo en diversas áreas de la ciudad, a pesar de la existencia de condiciones aparentemente favorables de recarga. La productividad de los pozos, determinada por su capacidad específica, también ha disminuido significativamente. Aunque el sistema acuífero es vital para la infraestructura de la ciudad, los recursos aún no han sido cuantificados adecuadamente. Hasta que este asunto no sea resuelto mediante la inversión en estudios de evaluación, los intentos por gestionar eficientemente los recursos de forma sustentable serán infructuosos.

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Résumé Cet article porte sur les pertes en quantité subies par Dacca du fait de l'exploitation rapide de l'aquifère de Dupi Tila. Dacca est l'une des villes dépendant de l'eau souterraine les plus importantes du monde, prélevant l'eau d'un aquifère sableux sous-jacent semi-captif. On estime à 1,300 forages l'accroissement des creusements de puits aussi bien dans le secteur privé que public dans ces dernières années; ils prélèvent dans l'aquifère dans la partie urbaine et à la périphérie de la ville. L'analyse des déclarations de creusement de puits pour l'AEP forés entre 1970 et 2000 montre que les niveaux d'eau ont chuté dans plusieurs zones de la ville malgré des conditions de recharge apparemment favorables. La productivité des puits mesurée par la capacité spécifique a également diminué significativement. Même si le système aquifère est vital pour l'infrastructure de la ville, il reste une ressource médiocrement quantifiée, et tant que ceci ne sera pas résolu par un investissement dans des études d'évaluation, les tentatives pour gérer efficacement la ressource de façon durable échoueront.

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Pollutant migration from deeply buried repositories     

M. S. Rahman  J. R. Booker 《国际地质力学数值与分析法杂志》1989,13(1):37-51

Semi-analytic solutions are developed for the migration of pollutants from cylindrical and spherical repositories buried deep in a homogeneous and isotropic soil in the presence of a uniform and unidirectional advection. The techniques adopted involves taking the Laplace transform of the governing equations, finding an analytic solution in transform space and then numerically inverting the transform to obtain the concentrations of the contaminants at selected positions and times. Numerical results are presented, and practical implications discussed.  相似文献