近10 a中亚低涡背景下新疆短时强降水环境场分析   总被引：1，自引：0，他引：1       下载免费PDF全文

毛列尼·阿依提看  杨莲梅  张云惠  玉素甫·木沙 《干旱区地理》2018,41(2):273-281

为更好地把握中亚低涡造成新疆短时强降水天气过程的机理特征,为新疆短时强降水预报预警提供参考和依据,利用FNL资料、探空资料等,运用天气学原理、动力诊断分析方法等,研究了中亚低涡系统不同部位发生的三类短时强降水的环境场特征及环流配置。结论表明：（1）短时强降水发生在500 hPa中亚低涡前部西南气流下为最多。（2） A指数在新疆地区短时强降水降水预报中意义不大。（3）中亚低涡背景下新疆短时强降水天气的配置一般属于高空冷平流强迫类。（4）三类短时强降水形势配置的共性：在低涡背景下,对流层中高层都有显著气流存在,低空有切变线存在,近地面往往有辐合线,700 hPa左右往往有湿舌。异性：第I类短时强降水湿度条件较好,第Ⅱ类短时强降水高低空温差较大,第Ⅲ类短时强降水垂直风切变较强。  相似文献   

Prediction of pore-water pressure response to rainfall using support vector regression     

Nuraddeen Muhammad Babangida  Muhammad Raza Ul Mustafa  Khamaruzaman Wan Yusuf  Mohamed Hasnain Isa 《Hydrogeology Journal》2016,24(7):1821-1833

Nonlinear complex behavior of pore-water pressure responses to rainfall was modelled using support vector regression (SVR). Pore-water pressure can rise to disturbing levels that may result in slope failure during or after rainfall. Traditionally, monitoring slope pore-water pressure responses to rainfall is tedious and expensive, in that the slope must be instrumented with necessary monitors. Data on rainfall and corresponding responses of pore-water pressure were collected from such a monitoring program at a slope site in Malaysia and used to develop SVR models to predict pore-water pressure fluctuations. Three models, based on their different input configurations, were developed. SVR optimum meta-parameters were obtained using k-fold cross validation and a grid search. Model type 3 was adjudged the best among the models and was used to predict three other points on the slope. For each point, lag intervals of 30 min, 1 h and 2 h were used to make the predictions. The SVR model predictions were compared with predictions made by an artificial neural network model; overall, the SVR model showed slightly better results. Uncertainty quantification analysis was also performed for further model assessment. The uncertainty components were found to be low and tolerable, with d-factor of 0.14 and 74 % of observed data falling within the 95 % confidence bound. The study demonstrated that the SVR model is effective in providing an accurate and quick means of obtaining pore-water pressure response, which may be vital in systems where response information is urgently needed.  相似文献   

GIS based morphometric analysis of Yamuna drainage network in parts of Fatehabad area of Agra district,Uttar Pradesh     

Ziaur Rehman Ansari  L. A. K. Rao  Alia Yusuf 《Journal of the Geological Society of India》2012,79(5):505-514

Remote Sensing and GIS techniques have been proved to be efficient tools in the delineation, updating and morphometric analysis of drainage basin. The present study incorporates a morphometric analysis of three sub-basins of Fatehabad area of Agra district using remote sensing and GIS techniques. The morphometric parameters of the sub-basins are classified under linear, areal and relief aspects. The drainage pattern exhibited by the main river Yamuna and its tributaries shows a dendritic pattern indicating homogenously underlain material while the mean bifurcation ratio values suggest that the geological structures are not disturbing the drainage pattern. The form factor value of sub-basins suggests that the main basin is more or less elongated. Circularity ratio values of the three sub-basins fall within range of elongated basin and low discharge. The area has low density indicating that the region has high permeable sub-soil material and dense vegetation. The values of drainage texture, drainage density and infiltration number indicate that sub-basin-III has the highest infiltration rate and low runoff, hence contributing most to the underground water resources. This study also indicates porous and permeable sub-soil condition in sub-basin-III. The values of sub-basin-I indicate low permeable subsoil material owning to high infiltration number value, hence low infiltration and high runoff.  相似文献   

Remote sensing and GIS-based landslide susceptibility mapping using frequency ratio and analytical hierarchy methods in Rize province (NE Turkey)   总被引：4，自引：3，他引：1  

S. Reis  A. Yalcin  M. Atasoy  R. Nisanci  T. Bayrak  M. Erduran  C. Sancar  S. Ekercin 《Environmental Earth Sciences》2012,66(7):2063-2073

The northeast part of Turkey is prone to landslides because of the climatic conditions, as well as geologic and geomorphologic characteristics of the region. Especially, frequent landslides in the Rize province often result in significant damage to people and property. Therefore, in order to mitigate the damage from landslides and help the planners in selecting suitable locations for implementing development projects, especially in large areas, it is necessary to scientifically assess susceptible areas. In this study, the frequency ratio method and the analytical hierarchy process (AHP) were used to produce susceptibility maps. Especially, AHP gives best results because of allowing better structuring of various components, including both objective and subjective aspects and comparing them by a logical and thorough method, which involves a matrix-based pairwise comparison of the contribution of different factors for landslide. For this purpose, lithology, slope angle, slope aspect, land cover, distance to stream, drainage density, and distance to road were considered as landslide causal factors for the study area. The processing of multi-geodata sets was carried out in a raster GIS environment. Lithology was derived from the geological database and additional field studies; slope angle, slope aspect, distance to stream, distance to road and drainage density were invented from digital elevation models; land cover was produced from remote sensing imagery. In the end of study, the results of the analysis were verified using actual landslide location data. The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide locations.  相似文献   

Fractionation and risk assessment of heavy metals in soil samples collected along Zerqa River,Jordan   总被引：3，自引：0，他引：3  

Habes A. Ghrefat  Nigem Yusuf  Ahmad Jamarh  Jamal Nazzal 《Environmental Earth Sciences》2012,66(1):199-208

The objectives of the current study were to determine the chemical partitioning of Pb, Ni, Zn, Co, Cr, Mn, Fe and Cd using sequential extraction procedure and to assess the environmental risk associated with these metals in the farming soils along Zerqa River. Metal concentrations were measured by atomic absorption spectrophotometer. The study area demonstrated a wide range for pH, organic matter, carbonate contents, and cation exchange capacity, and is polluted with Pb, Cd, Mn, and Cu. The extensive use of fertilizers and pesticides in the agricultural activities, and discharge of treated and untreated wastewater are the major sources of pollution in the study area. Principal component analysis coupled with Pearson’s correlation analysis between the heavy metals revealed strong and positive correlation between these metals in the study area. According to the Risk Assessment Code (RAC), major portions of Cd and Mn are contained in exchangeable and carbonates fractions and therefore can easily enter the food chain. These metals pose a high to very high risk to the environment. Cu, Ni, Pb, and Zn pose medium risk, while Cr poses a low environment risk.  相似文献   

Speckle interferometric binary system HD375; Is it a sub-giant binary?   总被引：1，自引：0，他引：1  

M. A. Al-Wardat  Yu. Yu. Balega  V. V. Leushin  N. A. Yusuf  A. A. Taani  K. S. Al-Waqfi  S. Masda 《Astrophysical Bulletin》2014,69(1):58-66

Atmospheric modeling is used to build synthetic spectral energy distributions (SEDs) for the individual components of the speckle interferometric binary system HD375. These synthetic SEDs are combined together for the entire system and compared with its observed SED in an iterative procedure to achieve the best fit. Kurucz blanketed models and the measurements of magnitude differences were used to build these SEDs. The input physical parameters for building these best fitted synthetic SEDs represent adequately enough properties of the system. These parameters are: T _eff ^a = 6100 ± 50 K, T _eff ^b = 5940 ± 50 K, log g _a = 4.01 ± 0.10, log g _b = 3.98 ± 0.10, R _a = 1.93 ± 0.20R _⊙, R _b = 1.83 ± 0.20R _⊙, M _v ^a = 3 _· ^m 26 ± 0.40, M _v ^b = 3 _· ^m 51 ± 0.50, L _a = 4.63 ± 0.80 L _⊙, and L _b = 3.74 ± 0.70 L _⊙, in accordance with the new estimated parallax π = 12.02 ± 0.60 mas. A modified orbit of the system is built and compared with earlier orbits, and the masses of the two components are calculated as M _a = 1.35M _⊙ and M _b = 1.25M _⊙. Based on the estimated physical and geometrical parameters of the system, which are confirmed by synthetic photometry, we suggest that the two components are evolved subgiant (F8.5 IV and G0 IV) stars with the age of 3.5 Gyr, formed by fragmentation.  相似文献   

Radio frequency interference measurements in Indonesia     

Taufiq Hidayat  Achmad Munir  Budi Dermawan  Anton Timur Jaelani  Stéphane Léon  Dading Hadi Nugroho  Andriyan Bayu Suksmono  Putra Mahasena  Premana Wardayanti Premadi  Dhani Herdiwijaya  Chatief Kunjaya  Zadrach Ledoufij Dupe  Budi Brahmantyo  Denny Mandey  Muhammad Yusuf  Hesti Retno Tri Wulandari  Falahuddin Arief  Muhammad Irfan  Agus Triono Puri Jatmiko  Evan Irawan Akbar  Hery Leo Sianturi  Jehunias Leonidas Tanesib  Ali Warsito  Judhistira Aria Utama 《Experimental Astronomy》2014,37(1):85-108

We report the first measurements of radio frequency spectrum occupancy performed at sites aimed to host the future radio astronomy observatory in Indonesia. The survey is intended to obtain the radio frequency interference (RFI) environment in a spectral range from low frequency 10 MHz up to 8 GHz. The measurements permit the identification of the spectral occupancy over those selected sites in reference to the allocated radio spectrum in Indonesia. The sites are in close proximity to Australia, the future host of Square Kilometre Array (SKA) at low frequency. Therefore, the survey was deliberately made to approximately adhere the SKA protocol for RFI measurements, but with lower sensitivity. The RFI environment at Bosscha Observatory in Lembang was also measured for comparison. Within the sensitivity limit of the measurement equipment, it is found that a location called Fatumonas in the surrounding of Mount Timau in West Timor has very low level of RFI, with a total spectrum occupancy in this measured frequency range being about 1 %, mostly found at low frequency below 20 MHz. More detailed measurements as well as a strategy for a radio quiet zone must be implemented in the near future.  相似文献   

Land subsidence of Jakarta (Indonesia) and its relation with urban development     

Hasanuddin Z. Abidin  Heri Andreas  Irwan Gumilar  Yoichi Fukuda  Yusuf E. Pohan  T. Deguchi 《Natural Hazards》2011,59(3):1753-1771

Jakarta is the capital city of Indonesia with a population of about 9.6 million people, inhabiting an area of about 660 square-km. In the last three decades, urban development of Jakarta has grown very rapidly in the sectors of industry, trade, transportation, real estate, and many others. This exponentially increased urban development introduces several environmental problems. Land subsidence is one of them. The resulted land subsidence will also then affect the urban development plan and process. It has been reported for many years that several places in Jakarta are subsiding at different rates. The leveling surveys, GPS survey methods, and InSAR measurements have been used to study land subsidence in Jakarta, over the period of 1982–2010. In general, it was found that the land subsidence exhibits spatial and temporal variations, with the rates of about 1–15 cm/year. A few locations can have the subsidence rates up to about 20–28 cm/year. There are four different types of land subsidence that can be expected to occur in the Jakarta basin, namely: subsidence due to groundwater extraction, subsidence induced by the load of constructions (i.e., settlement of high compressibility soil), subsidence caused by natural consolidation of alluvial soil, and tectonic subsidence. It was found that the spatial and temporal variations of land subsidence depend on the corresponding variations of groundwater extraction, coupled with the characteristics of sedimentary layers and building loads above it. In general, there is strong relation between land subsidence and urban development activities in Jakarta.  相似文献   

Linear genetic programming to scour below submerged pipeline     

H.Md. Azamathulla  Aytac Guven  Yusuf Kagan Demir 《Ocean Engineering》2011,38(8-9):995-1000

Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents Linear Genetic Programming (LGP), which is an extension to GP, as an alternative tool in the prediction of scour depth below a pipeline. The data sets of laboratory measurements were collected from published literature and were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at submerged pipeline.  相似文献   

Shadow of Kerr-Taub-NUT black hole     

Ahmadjon Abdujabbarov  Farruh Atamurotov  Yusuf Kucukakca  Bobomurat Ahmedov  Ugur Camci 《Astrophysics and Space Science》2013,344(2):429-435

The shadow of a rotating black hole with nonvanishing gravitomagnetic charge has been studied. It was shown that in addition to the angular momentum of black hole the gravitomagnetic charge term deforms the shape of the black hole shadow. From the numerical results we have obtained that for a given value of the rotation parameter, the presence of a gravitomagnetic charge enlarges the shadow and reduces its deformation with respect to the spacetime without gravitomagnetic charge. Finally we have studied the capture cross section for massive particles by black hole with the nonvanishing gravitomagnetic charge.  相似文献