A technique for prediction of SPEs from solar radio flux by statistical analysis,ANN and GA     

Kyong Nam Kim  Sun Ae Sin  Kum Ae Song  Jin Hyok Kong 《Astrophysics and Space Science》2018,363(8):170

Solar Radio Flux (SRF) is the significant index in easily evaluating everyday solar activities. From the statistical analysis of SRF at 2800 MHz, 1415 MHz and 610 MHz from 1976 to 1994, and only 111 Solar Proton Events (SPEs) occurring in the same period, we have given the statistical relation between them. In fact, there occurred a total of 131 SPEs in the same period, but we dealt with only 111 SPEs of them, because of lack of SRF data in SGD (2800 MHz, 1415 MHz and 610 MHz). We also discussed the possible parameters of SRF at 2800 MHz, 1415 MHz and 610 MHz for prediction of SPEs by statistical analysis, Artificial Neural Network (ANN) and Genetic Algorithm (GA) using MATLAB. In this study, we used some parameters: the daily total SRF, the overall rate of increase of SRF and SPEs.  相似文献   

Numerical simulation of heat conduction in a random ballistic deposited grain aggregate     

Sin‐iti Sirono 《Meteoritics & planetary science》2014,49(1):109-116

A numerical simulation of heat conduction in a grain aggregate is carried out to determine the packing fraction (the spatial fraction occupied by grains or 1‐porosity) dependence of the thermal conductivity of the aggregate. Arrangements of grains are given by random ballistic deposition. It is found that the packing fraction dependence is well approximated by an exponential function. The number of contacts between grains is the crucial quantity in the conduction, and its packing fraction dependence is exponential. Heat conduction is found to be anisotropic, where the conduction along the deposition direction is more efficient than that perpendicular to the deposition direction.  相似文献   

State‐led talent return migration programme and the doubly neglected ‘Malaysian diaspora’: Whose diaspora,what citizenship,whose development?          下载免费PDF全文

Sin Yee Koh 《Singapore journal of tropical geography》2015,36(2):183-200

This paper questions the assumptions of ‘diaspora’, ‘citizenship’ and ‘development’ underlying diaspora strategies targeting a specific pool of overseas Malaysian ‘talent’ migrants. I examine the Malaysian state's discursive attempts to construct a carefully contained economic ‘diaspora'—the ‘Malaysian diaspora'—through its talent return migration programme. In this process, there is a portion of the ‘Malaysian diaspora’, especially non‐bumiputeras (sons of soil), who are doubly neglected and excluded: first, from access to full and equal citizenship (which arguably contributed to their emigration in the first place); and second, from eligibility and recognition to participate in Malaysia's talent return migration programme. However, recent political activism calling for electoral reform and overseas voting rights challenges state‐constructed visions of the ‘diaspora’ and their expected roles in advancing ‘development’. This paper concludes by highlighting questions raised by the Malaysian case, linking these explicitly to how diaspora strategies—as they have been conceived, practised and contested—challenge the broader Migration and Development paradigm.  相似文献   

Critical shear stress approach for self-cleansing design of a rectangular channel     

Charles Hin Joo Bong  San Chuin Liew  Fang Yenn Teo  Tze Liang Lau  Aminuddin Ab Ghani 《国际泥沙研究》2021,36(5):678-685

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A new analytical solution for water table fluctuations in coastal aquifers with sloping beaches   总被引：3，自引：0，他引：3  

H. T. Teo  D. S. Jeng  B. R. Seymour  D. A. Barry  L. Li   《Advances in water resources》2003,26(12):1239-1247

The Boussinesq equation appears as the zeroth-order term in the shallow water flow expansion of the non-linear equation describing the flow of fluid in an unconfined aquifer. One-dimensional models based on the Boussinesq equation have been used to analyse tide-induced water table fluctuations in coastal aquifers. Previous analytical solutions for a sloping beach are based on the perturbation parameter, _N=αcotβ (in which β is the beach slope, α is the amplitude parameter and is the shallow water parameter) and are limited to tan⁻¹(α)βπ/2. In this paper, a new higher-order solution to the non-linear boundary value problem is derived. The results demonstrate the significant influence of the higher-order components and beach slope on the water table fluctuations. The relative difference between the linear solution and the present solution increases as and α increase, and reaches 7% of the linear solution.  相似文献   

Phytoplankton Size and Taxonomic Composition in a Temperate Estuary Influenced by Monsoon     

Yongsik Sin  Bonggil Hyun  Quang-Dung Bach  Sungryull Yang  Chul Park 《Estuaries and Coasts》2012,35(3):839-852

Temporal and spatial variations in phytoplankton in Asan Bay, a temperate estuary under the influence of monsoon, were investigated over an annual cycle (2004). Phytoplankton blooms started in February (>20 μg chl l⁻¹) and continued until April (>13 μg chl l⁻¹) during the dry season, especially in upstream regions. The percentage contribution of large phytoplankton (micro-sized) was high (78–95%) during the blooms, and diatoms such as Skeletonema costatum and Thalassiosira spp. were dominant. The precipitation and freshwater discharge from embankments peaked and supplied nutrients into the bay during the monsoon event, especially in July. Species that favor freshwater, such as Oscillatoria spp. (cyanobacteria), dominated during the monsoon period. The phytoplankton biomass was minimal in this season despite nutrient concentrations that were relatively sufficient (enriched), and this pattern differed from that in tropical estuaries affected by monsoon and in temperate estuaries where phytoplankton respond to nutrient inputs during wet seasons. The flushing time estimated from the salinity was shorter than the doubling time in Asan Bay, which suggests that exports of phytoplankton maximized by high discharge directly from embankments differentiate this bay from other estuaries in temperate and tropical regions. This implies that the change in physical properties, especially in the freshwater discharge rates, has mainly been a regulator of phytoplankton dynamics since the construction of embankments in Asan Bay.  相似文献   

Reply to comment on ‘A novel hysteresis model in unsaturated soil’ by A. D. Werner and D. A. Lockington     

Han‐Chen Huang  Chen‐Wuing Liu  Yih‐Chi Tan  Chu‐Hui Chen 《水文研究》2007,21(3):413-414

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Investigations of the development of thunderstorm with hail. Part 2. Analysis of methods for the forecast and diagnosis of the electrical properties of clouds     

Yu. P. Mikhailovskii  A. A. Sin’kevich  S. D. Pawar  V. Gopalakrishnan  Yu. A. Dovgalyuk  N. E. Veremei  E. V. Bogdanov  A. B. Kurov  A. Kh. Adzhiev  A. M. Malkarova  A. M. Abshaev 《Russian Meteorology and Hydrology》2017,42(6):377-387

The results of observation of the development of a high-depth thunder-hail storm is presented. The measurements were carried out with the MRL-5 weather radar and LS8000 lightning detection system. The electrical parameters of the investigated cloud obtained with LS8000 as well as their relations to radar-derived cloud characteristics and to the indirect criteria of electrical conditions computed on their basis are analyzed. The possibility to forecast thunderstorm based on different thermodynamic criteria is investigated. The high correlation was revealed between the total lightning current in the LF range and the lightning flash rate in the LF and VHF ranges. The total charge transferred by negative lightnings from this cloud to the ground is equal to 387 C; the average value of charge per one lightning is 0.44 C. Regression equations linking the radar criteria of lightnings and the lightning flash rate are presented.  相似文献   

Using the spectral scaling exponent for validation of quantitative precipitation forecasts     

T.-Y. Koh  B. C. Bhatt  K. K. W. Cheung  C. K. Teo  Y. H. Lee  Matthias Roth  Purnawirman 《Meteorology and Atmospheric Physics》2012,115(1-2):35-45

This study evaluates the spectral scaling of a heavy rainfall event and assesses the performance of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) model in terms of the multiscale variability of rainfall in the temporal spectral domain. The event occurred over southern Malay Peninsula on 18 December 2006 and was simulated at high resolutions. 10, 5 and 1?min aggregate rainfall data from rain gauge stations in Singapore and simulated rainfall sampled at different evaluation points on 0.9, 0.3 and 0.1?km grids were utilized. The simulated and observed rain rates were compared via Fourier and wavelet analyses. A scaling regime was noted in the observed rainfall spectra in the timescales between 60?min and 2?min. The scaling exponent obtained from the observed spectra has a value of about 2, which may be indicative of the physics of turbulence and raindrop coalescence and might suggest the predominance of a characteristic raindrop size. At 0.9?km resolution, the model rainfall spectra showed similar scaling to the observed down to about 10?min, below which a fall-off in variance was noted as compared to observations. Higher spatial resolution of up to 0.1?km was crucial to improve the ability of the model to resolve the shorter timescale variability. We suggest that the evaluation of dynamical models in the spectral domain is a crucial step in the validation of quantitative precipitation forecasts and assessing the minimal grid resolution necessary to capture rainfall variability for certain short timescales may be important for hydrological predictions.  相似文献   

Erratum to: Downward longwave radiation estimates for clear and all-sky conditions in the Sertãozinho region of São Paulo, Brazil     

Nadiane Smaha Kruk  Íria Fernandes Vendrame  Humberto Ribeiro da Rocha  Sin Chan Chou  Osvaldo Cabral 《Theoretical and Applied Climatology》2010,102(3-4):483-483

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