Decomposition of wind speed fluctuations at different time scales     

Qinmin Zheng  S Rehman  Md Mahbub Alam  L M Alhems  A Lashin 《Journal of Earth System Science》2017,126(3):36

Understanding the inherent features of wind speed (variability on different time scales) has become critical for assured wind power availability, grid stability, and effective power management. The study utilizes the wavelet, autocorrelation, and FFT (fast Fourier transform) techniques to analyze and assimilate the fluctuating nature of wind speed data collected over a period of 29–42 years at different locations in the Kingdom of Saudi Arabia. The analyses extracted the intrinsic features of wind speed, including the long-term mean wind speed and fluctuations at different time scales (periods), which is critical for meteorological purposes including wind power resource assessment and weather forecasting. The long-term mean wind speed varied between 1.45 m/s at Mecca station and 3.73 m/s at Taif. The annual variation is the largest (±0.97 m/s) at Taif and the smallest (±0.25 m/s) at Mecca. Similarly, the wind speed fluctuation with different periods was also discussed in detail. The spectral characteristics obtained using FFT reveal that Al-Baha, Najran, Taif and Wadi-Al-Dawasser having a sharp peak at a frequency f = 0.00269 (1/day) retain a more regular annual repetition of wind speed than Bisha, Khamis-Mushait, Madinah, Mecca, and Sharourah. Based on the autocorrelation analysis and FFT results, the stations are divided into three groups: (i) having strong annual modulations (Al-Baha, Najran, Taif and Wadi-Al-Dawasser), (ii) having comparable annual and half-yearly modulations (Bisha, Khamis-Mushait, and Mecca) and (iii) having annual modulation moderately prominent (Madinah and Sharourah).  相似文献   

Observed damages in Pakistan due to 16 April 2013 Iran earthquake     

Muhammad Masood Rafi  Sarosh H. Lodi  Muhammad Ahmed  Naveed Alam 《Bulletin of Earthquake Engineering》2015,13(2):703-724

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Sustainable conjunctive use of groundwater for additional irrigation          下载免费PDF全文

N. Alam  Theo N. Olsthoorn 《水文研究》2014,28(20):5288-5296

The key to ‘sustainable conjunctive use of groundwater for additional irrigation’ is the salt balance of groundwater below an irrigated field. This paper aims to develop a mathematical tool to study the accumulation of salt in the groundwater below an irrigated field as caused by irrigation recirculation. This study derives a salt balance of groundwater to ensure that the additional irrigation from groundwater remains possible in the future. The water and salt budgets by themselves do neither provide information concerning farmers' options nor on the limits of the individual terms in the budget equations. It is presumed that farmers will intuitively aim for (1) an optimal value of the actual evapotranspiration, and (2) a return flow as a feasible low fraction of the available water. We, therefore, derive the irrigation from groundwater Q as a consequence of the predefined farmers' aims to achieve a high actual evapotranspiration in combination with a given optimally used irrigation system. Our model concludes that the required amount of drainage is only dependent on the ratio of the salinity in the surface irrigation water and the acceptable salinity of the groundwater. The final salinity in the saturated zone only depends on salt‐carrying inflows and outflows. From the aforesaid model, it is further concluded that sustainable conjunctive use of groundwater for additional irrigation requires long‐term salt management, which should be founded on the essential controlling factors as derived in this paper. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Bridging the gaps: the role of local government capability and the management of a natural disaster in Bantul, Indonesia     

Bevaola Kusumasari  Quamrul Alam 《Natural Hazards》2012,60(2):761-779

This paper examines local government capability in managing pre-, during and post-natural disaster in Indonesia. The case study is the Bantul local government which had experience in managing the 2006 earthquake. Bantul is located in the most densely populated area of Java, where 1,500 people per square km square, and the earthquake destroyed domestic industries that had become the main resource of the Bantul local government. The capability of local government and the requirement to manage a disaster are very important issues for exploring the important role of local government in mitigation, preparedness, response and recovery disaster management activities, particularly in regard to the characteristics of local government in developing countries. In this paper, capability of local government in managing a disaster is defined as a function of institutions, human resources, policy for effective implementation, financial, technical resources and leadership. The capability requirement of each stage of disaster management has also been explained from the point of view of state and non-state actors and institutions. Finally, the paper integrates the capability requirement and reality in order to bridge these gaps.  相似文献   

Seismogenic sources in the Bay of Bengal vis-à-vis potential for tsunami generation and its impact in the northern Bay of Bengal coast     

Aftab Alam Khan 《Natural Hazards》2012,61(3):1127-1141

Geodynamic status, seismo-tectonic environment, and geophysical signatures of the Bay of Bengal do not support the occurrence of seismogenic tsunami. Since thrust fault and its intensity and magnitude of rupture are the key tectonic elements of tsunamigenic seismic sources, the study reveals that such characteristics of fault-rupture and seismic sources do not occur in most of the Bay of Bengal except a small segment in the Andaman–Nicobar subduction zone. The inferred segment of the Andaman–Nicobar subduction zone is considered for generating a model of the deformation field arising from fluid-driven source. The model suggests local tsunami with insignificant inundation potential along the coast of northern Bay of Bengal. The bathymetric profile and the sea floor configuration of the northern Bay of Bengal play an important role in flattening the waveform through defocusing process. The direction of motion of the Indian plate makes an angle of about 30° with the direction of the opening of Andaman Sea. The opening of Andaman Sea and the direction of plate motion of the Indian plate results in the formation of Andaman trench where the subducting plate dives more obliquely than that in the Sunda trench in the south. The oblique subduction reduces significantly the possibilities of dominant thrust faulting in the Andaman subduction zone. Further, north of Andaman subduction in the Bengal–Arakan coast, there is no active subduction. On the otherhand, much greater volume of sediments (in excess of 20 km) in the Bengal–Arakan segment reduces the possibilities of mega rupture of the ocean floor. The water depth (≈1,000 m) along most of the northern Bay of Bengal plate margin is not optimum for any significant tsunami generation. Hence, very weak possibility of any significant tsunami is suggested that based on the interpretation of geodynamic status, seismo-tectonic environment, and geophysical signatures of the Andaman subduction zone and the Bengal–Arakan coast.  相似文献   

Structural control on landscape development of Barak valley,Northeast India     

A. K. Biswas  A. Alam Laskar  P. Phukon 《Journal of the Geological Society of India》2014,83(4):467-468

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An analysis of the AD1762 earthquake and tsunami in SE Bangladesh     

Edris Alam  Dale Dominey-Howes 《Natural Hazards》2014,70(1):903-933

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Sources and transports of polycyclic aromatic hydrocarbons in the Nanshan Underground River,China   总被引：4，自引：0，他引：4  

Md. Jahangir Alam  Daoxian Yuan  Yong Jun Jiang  Yuchuan Sun  Yong Li  Xin Xu 《Environmental Earth Sciences》2014,71(4):1967-1976

Karst areas have much higher ecological vulnerability and are easy to be contaminated by polycyclic aromatic hydrocarbons (PAHs), which are introduced as health risk pollutants. PAHs ratios were used to understand the sources and transport behavior of PAHs conducted in the karst Nanshan Underground River, China. Water, sediments from the underground river and water, sediments, soil from the surface were collected monthly in 2011 and 2012. Abundant PAHs were found both in the underground river and in the surface system. The detected ΣPAHs concentrations varied from 353 to 13,203 ng L^?1 in the groundwaters and content from 169 to 12,038 ng g^?1 in the sediments of the underground river. The ratios of anthracene to anthracene, plus phenanthrene and fluoranthene to fluoranthene, plus pyrene indicated that PAHs were delivered in the groundwaters from combusted grass, wood, and coal, while in the sediments were a mixture of non-combusted petroleum, grass, wood, coal and combusted grass, wood, coal. The similarities in sources between an underground river and surface system indicated that farmlands play a major role for the transport of PAHs and contamination in the underground river. Karst features are liable for the transport behavior.  相似文献   

Smoothing supernova data to reconstruct the expansion history of the Universe and its age     

Arman Shafieloo  Ujjaini Alam  Varun Sahni  Alexei A. Starobinsky 《Monthly notices of the Royal Astronomical Society》2006,366(3):1081-1095

We propose a non-parametric method of smoothing supernova data over redshift using a Gaussian kernel in order to reconstruct important cosmological quantities including   H ( z )  and   w ( z )  in a model-independent manner. This method is shown to be successful in discriminating between different models of dark energy when the quality of data is commensurate with that expected from the future Supernova Acceleration Probe ( SNAP ). We find that the Hubble parameter is especially well determined and useful for this purpose. The look-back time of the Universe may also be determined to a very high degree of accuracy (≲0.2 per cent) using this method. By refining the method, it is also possible to obtain reasonable bounds on the equation of state of dark energy. We explore a new diagnostic of dark energy – the ' w -probe'– which can be calculated from the first derivative of the data. We find that this diagnostic is reconstructed extremely accurately for different reconstruction methods even if Ω_{0 m} is marginalized over. The w -probe can be used to successfully distinguish between Λ cold dark matter and other models of dark energy to a high degree of accuracy.  相似文献   

Electrochemical disinfection for ballast water management: technology development and risk assessment     

Nanayakkara KG  Zheng YM  Alam AK  Zou S  Chen JP 《Marine pollution bulletin》2011,63(5-12):119-123

Ballast water is essential in maintaining the balance and structural integrity of ships during voyage. However, it has created biological invasion threats to the ocean environment. An innovative electrochemical technology was developed in this study. The microorganisms regulated by the International Maritime Organization (D2) were used as the target organisms. It was found that the required energy to meet the D2 was below 0.006 kWh/m3. The size of disinfector (m3) was about 0.5% of treatment flow rate (m3/h). The complete disappearance of chlorine in seawater was achieved after three days. The ballast tank corrosion was not worsened due to the application of technology. The ecotoxicity studies showed no toxic effect on fish, invertebrate, and algae. Finally, the environmental risk assessment showed the treated water did not pose threats to the environment. It can therefore be concluded that the technology provides a cost-effective and environmental friendly solution to ballast water management.  相似文献