CFD simulation and experimental analysis of flow dynamics and grinding performance of opposed fluidized bed air jet mill     

M. Sri Raj Rajeswari  K.A.M. Azizli  S.F.S. Hashim  M.K. Abdullah  M. Abdul Mujeebu  M.Z. Abdullah 《International Journal of Mineral Processing》2011,98(1-2):94-105

This paper presents a three dimensional Computational Fluid Dynamics (CFD) model to investigate the flow dynamics of solid–gas phases during fine grinding in an air jet mill. Alpine 100AFG fluidized bed air jet mill is considered for the study and the jet milling model is simulated using FLUENT 6.3.2 using a standard k-ε model. The model is developed in GAMBIT 2.3.16 and meshed by tet/hybrid (T-Grid) and Triangular (Pave) meshes. The effects of operating parameters such as solid feed rate, grinding air pressure and internal classifier speed on the performance of the jet mill are analyzed. The CFD simulation results are presented in the forms of dual phase vector plot, volume fraction of phases and particle trajectories during fine grinding process. The mass of ground feed entering and leaving the cyclone (underflow) is also computed by simulation. The proposed model gives realistic predictions of the flow dynamics within the jet mill. Experiments are conducted on the Alpine 100AFG jet mill to study the particle size, morphology and mass of the ground product. The numerical results are found in good agreement with the experimental results.  相似文献   

An evaluation of force-based design vs. direct displacement-based design of jointed precast post-tensioned wall systems     

M. Ataur Rahman Sri Sritharan 《地震工程与工程振动(英文版)》2006,5(2):285-296

The unique features of jointed post-tensioned wall systems, which include minimum structural damage and re-centering capability when subjected to earthquake lateral loads, are the result of using unbonded post-tensioning to attach the walls to the foundation, along with employing energy dissipating shear connectors between the walls. Using acceptance criteria defined in terms of inter-story drift, residual drift, and floor acceleration, this study presents a multiplelevel performance-based seismic evaluation of two five-story unbonded post-tensioned jointed precast wall systems. The design and analysis of these two wall systems, established as the direct displacement-based and force-based solutions for a prototype building used in the PREcast Seismic Structural Systems （PRESSS） program, were performed at 60% scale so that the analysis model could be validated using the PRESSS test data. Both buildings satisfied the performance criteria at four levels of earthquake motions although the design base shear of the direct displacement-based jointed wall system was 50% of that demanded by the force-based design method. The study also investigated the feasibility of controlling the maximum transient inter-story drift in a jointed wall system by increasing the number of energy dissipating shear connectors between the walls but without significantly affecting its re-centering capability.  相似文献   

A 10-year wave energy resource assessment and trends of Indonesia based on satellite observations     

Amiruddin  Ribal Agustinus  Khaeruddin  Thamrin Sri Astuti 《海洋学报(英文版)》2019,38(8):86-93

Wave energy resource assessment and trends around Indonesian's ocean has been carried out by means of analyzing satellite observations. Wave energy flux or wave power can be approximated using parameterized sea states derived from satellite data. Unfortunately, only some surface parameters can be measured from remote sensing satellites, for example for ocean surface waves: significant wave height. Others, like peak wave period and energy period are not available, but can instead be estimated using empirical models. The results have been assessed by meteorological season. The assessment shows clearly where and when the wave power resource is promising around Indonesian's ocean. The most striking result was found from June to August, in which about 30–40 kW/m(the 90 th percentile: 40–60 kW/m, the 99th percentile: 50–70 kW/m) wave power energy on average has been found around south of the Java Island. The significant trends of wave energy at the 95% level have also been studied and it is found that the trends only occurred for the extreme cases, which is the 99th percentile(i.e.,highest 1%). Wave power energy could increase up to 150 W/m per year. The significant wave heights and wave power have been compared with the results obtained from global wave model hindcast carried out by wave model WAVEWATCH III. The comparisons indicated excellent agreements.  相似文献   

Theoretical Evaluation of Modified Wenner Array for Shallow Resistivity Exploration   总被引：1，自引：0，他引：1  

Vikas C. Goyal  Sri Niwas  Pravin K. Gupta 《Ground water》1991,29(4):582-586

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Developing building-damage scales for lahars: application to Merapi volcano,Indonesia     

Susanna F. Jenkins  Jeremy C. Phillips  Rebecca Price  Kate Feloy  Peter J. Baxter  Danang Sri Hadmoko  Edouard de Bélizal 《Bulletin of Volcanology》2015,77(9):1-17

  相似文献   

The 2015 eruption of Gamalama volcano (Ternate Island–Indonesia): precursor,crisis management,and community response     

Hidayat  Agung  Marfai  Muh Aris  Hadmoko  Danang Sri 《GeoJournal》2022,87(1):1-20

GeoJournal - Gamalama is an active stratovolcano on Ternate, a small volcanic island in Maluku Utara, Indonesia. Since 1510, a total of 77 eruptions have been recorded, with various impacts on the...  相似文献   

Multivariate fire risk models using copula regression in Kalimantan,Indonesia     

Najib  Mohamad Khoirun  Nurdiati  Sri  Sopaheluwakan  Ardhasena 《Natural Hazards》2022,113(2):1263-1283

Natural Hazards - Forest fires have become a national issue yearly and elicited serious attention from the government and researchers in Indonesia. Copula-based joint distribution can construct a...  相似文献   

Landslide hazard and risk assessment and their application in risk management and landuse planning in eastern flank of Menoreh Mountains,Yogyakarta Province,Indonesia     

Danang Sri Hadmoko  Franck Lavigne  Junun Sartohadi  Pramono Hadi  Winaryo 《Natural Hazards》2010,54(3):623-642

The Menoreh Mountains in Yogyakarta are severely affected by landslides. Due to the high population densities, mass movements are generally damaging and fatal. More than other Javanese mountains, the Menoreh Mountains cumulate several factors causing landslides. Therefore, it is necessary to evaluate the ways to map landslide risk in order to improve the risk mitigation. The objectives of this paper are to provide landslide hazard and risk assessment that will be useful for risk prevention and landuse planning in the Menoreh Mountains. So far, risk management has been developed by the Research Centre for Disasters Gadjah Mada University in collaboration with the Regional Development Planner (BAPPEDA), which carries out fundamental and applied researches. The results of the studies have been integrated in the risk prevention and landuse planning in order to improve the integrated landslide mitigation programme.  相似文献   

EM2INV — A finite difference based algorithm for two-dimensional inversion of geoelectromagnetic data     

P. K. Gupta  Sri Niwas  Anupma Rastogi 《Journal of Earth System Science》1999,108(4):233-253

The paper presents an efficient finite difference based 2D-inversion algorithm, EM2INV, for geoelectromagnetic data. The special features of the algorithm are

–	• optimal grid generation based on grid design thumb rules,
–	• finite domain boundary conditions,
–	• interpolation matrix that permits generation of response at observation points different from grid points,
–	• Gaussian elimination forward matrix solver, that enables reuse of already decomposed coefficient matrix,
–	• super-block notion that reduces the number of blocks with unknown resistivities and, in turn, the size of Jacobian matrix and
–	• bi-conjugate gradient matrix solver for inverse problem which circumvents the need of explicit Jacobian matrix computation.

The algorithm is tested rigorously by setting up exercises of diverse nature and of practical significance. The stability of the algorithm is established by inverting the synthetic response corrupted with Gaussian noise. The inversion experiments are aimed at studying

–	• relative performance of response functions,
–	• inversion quality of E- and B-polarization data,
–	• efficacy of single and multi-frequency data inversion,
–	• minimum number of frequencies and observation points needed for successful data inversion.

It has been observed that the Magneto-telluric data deciphers better the vertical position of the target and Geomagnetic Depth Sounding data deciphers the horizontal variations in a better way. The conductive and resistive bodies are better resolved by inversion of E- and B-polarization data respectively. The results of multi-frequency inversion imply that the increase in the number of frequencies does not necessarily enhance the inversion quality especially when the spread of observation points is sufficiently large to sense the target. The study of a minimum number of observation points highlights the importance of single point inversion that furnishes useful information about the inhomogeneity.  相似文献   

Aquifer parameter estimation from surface resistivity data   总被引：7，自引：0，他引：7  

Niwas S  de Lima OA 《Ground water》2003,41(1):94-99

This paper is devoted to the additional use, other than ground water exploration, of surface geoelectrical sounding data for aquifer hydraulic parameter estimation. In a mesoscopic framework, approximated analytical equations are developed separately for saline and for fresh water saturations. A few existing useful aquifer models, both for clean and shaley sandstones, are discussed in terms of their electrical and hydraulic effects, along with the linkage between the two. These equations are derived for insight and physical understanding of the phenomenon. In a macroscopic scale, a general aquifer model is proposed and analytical relations are derived for meaningful estimation, with a higher level of confidence, of hydraulic parameter from electrical parameters. The physical reasons for two different equations at the macroscopic level are explicitly explained to avoid confusion. Numerical examples from existing literature are reproduced to buttress our viewpoint.  相似文献