Search results for: distribution function
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 3797

Search results for: distribution function

2027 Group Invariant Solutions for Radial Jet Having Finite Fluid Velocity at Orifice

Authors: I. Naeem, R. Naz

Abstract:

The group invariant solution for Prandtl-s boundary layer equations for an incompressible fluid governing the flow in radial free, wall and liquid jets having finite fluid velocity at the orifice are investigated. For each jet a symmetry is associated with the conserved vector that was used to derive the conserved quantity for the jet elsewhere. This symmetry is then used to construct the group invariant solution for the third-order partial differential equation for the stream function. The general form of the group invariant solution for radial jet flows is derived. The general form of group invariant solution and the general form of the similarity solution which was obtained elsewhere are the same.

Keywords: Two-dimensional jets, radial jets, group invariant solution.

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2026 Unambiguous Signal Acquisition Based On Recombination of Sub-Correlations of BOC Signals

Authors: Hongdeuk Kim, Youngpo Lee, Seokho Yoon

Abstract:

Due to side-peaks of autocorrelation function, the binary offset carrier (BOC) signal acquisition suffers from an ambiguity when one of the side-peaks is acquired. In this paper, we first analyze that the BOC autocorrelation is made up of the sum of subcorrelations, and then, remove the side-peaks causing the ambiguity by recombining the sub-correlations. The proposed scheme is shown to remove the side-peaks completely. From numerical results, it is confirmed that the proposed scheme outperforms the conventional schemes in terms of the receiver operating characteristic and mean acquisition time.

Keywords: Binary offset carrier (BOC), acquisition, ambiguity problem, side-peak.

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2025 Robust Variogram Fitting Using Non-Linear Rank-Based Estimators

Authors: Hazem M. Al-Mofleh, John E. Daniels, Joseph W. McKean

Abstract:

In this paper numerous robust fitting procedures are considered in estimating spatial variograms. In spatial statistics, the conventional variogram fitting procedure (non-linear weighted least squares) suffers from the same outlier problem that has plagued this method from its inception. Even a 3-parameter model, like the variogram, can be adversely affected by a single outlier. This paper uses the Hogg-Type adaptive procedures to select an optimal score function for a rank-based estimator for these non-linear models. Numeric examples and simulation studies will demonstrate the robustness, utility, efficiency, and validity of these estimates.

Keywords: Asymptotic relative efficiency, non-linear rank-based, robust, rank estimates, variogram.

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2024 Measurements of Radial Velocity in Fixed Fluidized Bed for Fischer-Tropsch Synthesis Using LDV

Authors: Xiaolai Zhang, Haitao Zhang, Qiwen Sun, Weixin Qian, Weiyong Ying

Abstract:

High temperature Fischer-Tropsch synthesis process use fixed fluidized bed as a reactor. In order to understand the flow behavior in the fluidized bed better, the research of how the radial velocity affects the entire flow field is necessary. Laser Doppler Velocimetry (LDV) was used to study the radial velocity distribution along the diameter direction of the cross-section of the particle in a fixed fluidized bed. The velocity in the cross-section is fluctuating within a small range. The direction of the speed is a random phenomenon. In addition to r/R is 1, the axial velocity are more than 6 times of the radial velocity, the radial velocity has little impact on the axial velocity in a fixed fluidized bed.

Keywords: LDV, fixed fluidized bed, velocity, Fischer-Tropsch synthesis.

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2023 Block Cipher Based on Randomly Generated Quasigroups

Authors: Deepthi Haridas, S Venkataraman, Geeta Varadan

Abstract:

Quasigroups are algebraic structures closely related to Latin squares which have many different applications. The construction of block cipher is based on quasigroup string transformation. This article describes a block cipher based Quasigroup of order 256, suitable for fast software encryption of messages written down in universal ASCII code. The novelty of this cipher lies on the fact that every time the cipher is invoked a new set of two randomly generated quasigroups are used which in turn is used to create a pair of quasigroup of dual operations. The cryptographic strength of the block cipher is examined by calculation of the xor-distribution tables. In this approach some algebraic operations allows quasigroups of huge order to be used without any requisite to be stored.

Keywords: quasigroups, latin squares, block cipher and quasigroup string transformations.

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2022 Predicting the Success of Bank Telemarketing Using Artificial Neural Network

Authors: Mokrane Selma

Abstract:

The shift towards decision making (DM) based on artificial intelligence (AI) techniques will change the way in which consumer markets and our societies function. Through AI, predictive analytics is being used by businesses to identify these patterns and major trends with the objective to improve the DM and influence future business outcomes. This paper proposes an Artificial Neural Network (ANN) approach to predict the success of telemarketing calls for selling bank long-term deposits. To validate the proposed model, we uses the bank marketing data of 41188 phone calls. The ANN attains 98.93% of accuracy which outperforms other conventional classifiers and confirms that it is credible and valuable approach for telemarketing campaign managers.

Keywords: Bank telemarketing, prediction, decision making, artificial intelligence, artificial neural network.

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2021 Face Recognition using a Kernelization of Graph Embedding

Authors: Pang Ying Han, Hiew Fu San, Ooi Shih Yin

Abstract:

Linearization of graph embedding has been emerged as an effective dimensionality reduction technique in pattern recognition. However, it may not be optimal for nonlinearly distributed real world data, such as face, due to its linear nature. So, a kernelization of graph embedding is proposed as a dimensionality reduction technique in face recognition. In order to further boost the recognition capability of the proposed technique, the Fisher-s criterion is opted in the objective function for better data discrimination. The proposed technique is able to characterize the underlying intra-class structure as well as the inter-class separability. Experimental results on FRGC database validate the effectiveness of the proposed technique as a feature descriptor.

Keywords: Face recognition, Fisher discriminant, graph embedding, kernelization.

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2020 Conjugate Free Convection in a Square Cavity Filled with Nanofluid and Heated from Below by Spatial Wall Temperature

Authors: Ishak Hashim, Ammar Alsabery

Abstract:

The problem of conjugate free convection in a square cavity filled with nanofluid and heated from below by spatial wall temperature is studied numerically using the finite difference method. Water-based nanofluid with copper nanoparticles are chosen for the investigation. Governing equations are solved over a wide range of nanoparticle volume fraction (0 ≤ φ ≤ 0.2), wave number ((0 ≤ λ ≤ 4) and thermal conductivity ratio (0.44 ≤ Kr ≤ 6). The results presented for values of the governing parameters in terms of streamlines, isotherms and average Nusselt number. It is found that the flow behavior and the heat distribution are clearly enhanced with the increment of the non-uniform heating.

Keywords: Conjugate free convection, nanofluid, spatial temperature.

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2019 The Performance of Predictive Classification Using Empirical Bayes

Authors: N. Deetae, S. Sukparungsee, Y. Areepong, K. Jampachaisri

Abstract:

This research is aimed to compare the percentages of correct classification of Empirical Bayes method (EB) to Classical method when data are constructed as near normal, short-tailed and long-tailed symmetric, short-tailed and long-tailed asymmetric. The study is performed using conjugate prior, normal distribution with known mean and unknown variance. The estimated hyper-parameters obtained from EB method are replaced in the posterior predictive probability and used to predict new observations. Data are generated, consisting of training set and test set with the sample sizes 100, 200 and 500 for the binary classification. The results showed that EB method exhibited an improved performance over Classical method in all situations under study.

Keywords: Classification, Empirical Bayes, Posterior predictive probability.

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2018 Statistical Evaluation of Nonlinear Distortion using the Multi-Canonical Monte Carlo Method and the Split Step Fourier Method

Authors: Ioannis Neokosmidis, Nikos Gkekas, Thomas Kamalakis, Thomas Sphicopoulos

Abstract:

In high powered dense wavelength division multiplexed (WDM) systems with low chromatic dispersion, four-wave mixing (FWM) can prove to be a major source of noise. The MultiCanonical Monte Carlo Method (MCMC) and the Split Step Fourier Method (SSFM) are combined to accurately evaluate the probability density function of the decision variable of a receiver, limited by FWM. The combination of the two methods leads to more accurate results, and offers the possibility of adding other optical noises such as the Amplified Spontaneous Emission (ASE) noise.

Keywords: Monte Carlo, Nonlinear optics, optical crosstalk, Wavelength-division Multiplexing (WDM).

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2017 The Influence of Voltage Flicker for the Wind Generator upon Distribution System

Authors: Jin-Lung Guan, Jyh-Cherng Gu, Ming-Ta Yang, Hsin-Hung Chang, Chun-Wei Huang, Shao-Yu Huang

Abstract:

One of the most important power quality issues is voltage flicker. Nowadays this issue also impacts the power system all over the world. The fact of the matter is that the more and the larger capacity of wind generator has been installed. Under unstable wind power situation, the variation of output current and voltage have caused trouble to voltage flicker. Hence, the major purpose of this study is to analyze the impact of wind generator on voltage flicker of power system. First of all, digital simulation and analysis are carried out based on wind generator operating under various system short circuit capacity, impedance angle, loading, and power factor of load. The simulation results have been confirmed by field measurements.

Keywords: Wind Generator, Voltage Flicker

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2016 Component Comparison of Polyaluminum Chloride Produced from Various Methods

Authors: Wen Po Cheng, Chia Yun Chung, Ruey Fang Yu, Chao Feng Chen

Abstract:

The main objective of this research was to study the differences of aluminum hydrolytic products between two PACl preparation methods. These two methods were the acidification process of freshly formed amorphous Al(OH)3 and the conventional alkalization process of aluminum chloride solution. According to Ferron test and 27Al NMR analysis of those two PACl preparation procedures, the reaction rate constant (k) values and Al13 percentage of acid addition process at high basicity value were both lower than those values of the alkaline addition process. The results showed that the molecular structure and size distribution of the aluminum species in both preparing methods were suspected to be significantly different at high basicity value.

Keywords: Polyaluminum chloride, Al13, amorphous aluminum hydroxide, Ferron test.

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2015 A Fuzzy Classifier with Evolutionary Design of Ellipsoidal Decision Regions

Authors: Leehter Yao, Kuei-Song Weng, Cherng-Dir Huang

Abstract:

A fuzzy classifier using multiple ellipsoids approximating decision regions for classification is to be designed in this paper. An algorithm called Gustafson-Kessel algorithm (GKA) with an adaptive distance norm based on covariance matrices of prototype data points is adopted to learn the ellipsoids. GKA is able toadapt the distance norm to the underlying distribution of the prototypedata points except that the sizes of ellipsoids need to be determined a priori. To overcome GKA's inability to determine appropriate size ofellipsoid, the genetic algorithm (GA) is applied to learn the size ofellipsoid. With GA combined with GKA, it will be shown in this paper that the proposed method outperforms the benchmark algorithms as well as algorithms in the field.

Keywords: Ellipsoids, genetic algorithm, classification, fuzzyc-means (FCM)

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2014 Mechanical Properties of Die-Cast Nonflammable Mg Alloy

Authors: Myoung-Gon Yoon, Jung-Ho Moon, Tae Kwon Ha

Abstract:

Tensile specimens of nonflammable AZ91D Mg alloy were fabricated in this study via cold chamber die-casting process. Dimensions of tensile specimens were 25mm in length, 4mm in width, and 0.8 or 3.0mm in thickness. Microstructure observation was conducted before and after tensile tests at room temperature. In the die casting process, various injection distances from 150 to 260mm were employed to obtain optimum process conditions. Distribution of Al12Mg17 phase was the key factor to determine the mechanical properties of die-cast Mg alloy. Specimens with 3mm of thickness showed superior mechanical properties to those with 0.8mm of thickness. Closed networking of Al12Mg17 phase along grain boundary was found to be detrimental to mechanical properties of die-cast Mg alloy.

Keywords: Non-flammable magnesium alloy, AZ91D, die-casting, microstructure, mechanical properties.

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2013 The Principle Probabilities of Space-Distance Resolution for a Monostatic Radar and Realization in Cylindrical Array

Authors: Anatoly D. Pluzhnikov, Elena N. Pribludova, Alexander G. Ryndyk

Abstract:

In conjunction with the problem of the target selection on a clutter background, the analysis of the scanning rate influence on the spatial-temporal signal structure, the generalized multivariate correlation function and the quality of the resolution with the increase pulse repetition frequency is made. The possibility of the object space-distance resolution, which is conditioned by the range-to-angle conversion with an increased scanning rate, is substantiated. The calculations for the real cylindrical array at high scanning rate are presented. The high scanning rate let to get the signal to noise improvement of the order of 10 dB for the space-time signal processing.

Keywords: Antenna pattern, array, signal processing, spatial resolution.

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2012 Torrefaction of Biomass Pellets: Modeling of the Process in a Fixed Bed Reactor

Authors: Ekaterina Artiukhina, Panagiotis Grammelis

Abstract:

Torrefaction of biomass pellets is considered as a useful pretreatment technology in order to convert them into a high quality solid biofuel that is more suitable for pyrolysis, gasification, combustion, and co-firing applications. In the course of torrefaction, the temperature varies across the pellet, and therefore chemical reactions proceed unevenly within the pellet. However, the uniformity of the thermal distribution along the pellet is generally assumed. The torrefaction process of a single cylindrical pellet is modeled here, accounting for heat transfer coupled with chemical kinetics. The drying sub-model was also introduced. The nonstationary process of wood pellet decomposition is described by the system of non-linear partial differential equations over the temperature and mass. The model captures well the main features of the experimental data.

Keywords: Torrefaction, biomass pellets, model, heat and mass transfer.

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2011 IEEE 802.11 b and g WLAN Propagation Model using Power Density Measurements at ESPOL

Authors: E. E. Mantilla, C. R. Reyes, B. G. Ramos

Abstract:

This paper describes the development of a WLAN propagation model, using Spectral Analyzer measurements. The signal is generated by two Access Points (APs) on the base floor at the administrative Communication School of ESPOL building. In general, users do not have a Q&S reference about a wireless network; however, this depends on the level signal as a function of frequency, distance and other path conditions between receiver and transmitter. Then, power density of the signal decrease as it propagates through space and data transfer rate is affected. This document evaluates and implements empirical mathematical formulation for the characterization of WLAN radio wave propagation on two aisles of the building base floor.

Keywords: frequency, Spectral Analyzer, transmitter, WLAN.

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2010 Study of Currents and Temperature of Induced Spur Gear using 2d Simulation

Authors: N. Barka, P. Bocher, A. Chebak, J. Brousseau, D. S. Ramdenee

Abstract:

This paper presents the study of induced currents and temperature distribution in gear heated by induction process using 2D finite element (FE) model. The model is developed by coupling Maxwell and heat transfer equations into a multi-physics model. The obtained results allow comparing the medium frequency (MF) and high frequency (HF) cases and the effect of machine parameters on the evolution of induced currents and temperature during heating. The sensitivity study of the temperature profile is conducted and the case hardness is predicted using the final temperature profile. These results are validated using tests and give a good understanding of phenomena during heating process.

Keywords: 2D model, induction heating, spur gear, induced currents, experimental validation

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2009 Parallel 2-Opt Local Search on GPU

Authors: Wen-Bao Qiao, Jean-Charles Créput

Abstract:

To accelerate the solution for large scale traveling salesman problems (TSP), a parallel 2-opt local search algorithm with simple implementation based on Graphics Processing Unit (GPU) is presented and tested in this paper. The parallel scheme is based on technique of data decomposition by dynamically assigning multiple K processors on the integral tour to treat K edges’ 2-opt local optimization simultaneously on independent sub-tours, where K can be user-defined or have a function relationship with input size N. We implement this algorithm with doubly linked list on GPU. The implementation only requires O(N) memory. We compare this parallel 2-opt local optimization against sequential exhaustive 2-opt search along integral tour on TSP instances from TSPLIB with more than 10000 cities.

Keywords: Doubly linked list, parallel 2-opt, tour division, GPU.

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2008 Sparsity-Aware and Noise-Robust Subband Adaptive Filter

Authors: Young-Seok Choi

Abstract:

This paper presents a subband adaptive filter (SAF) for a system identification where an impulse response is sparse and disturbed with an impulsive noise. Benefiting from the uses of l1-norm optimization and l0-norm penalty of the weight vector in the cost function, the proposed l0-norm sign SAF (l0-SSAF) achieves both robustness against impulsive noise and much improved convergence behavior than the classical adaptive filters. Simulation results in the system identification scenario confirm that the proposed l0-norm SSAF is not only more robust but also faster and more accurate than its counterparts in the sparse system identification in the presence of impulsive noise.

Keywords: Subband adaptive filter, l0-norm, sparse system, robustness, impulsive interference.

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2007 A Study on Strategy of Coordinative Symbiosis between New and Old Buildings: Case Study of Shanghai Citic Plaza and Surroundings

Authors: Tianyi Qin

Abstract:

Along with the acceleration of Chinese urbanization, the expansion, renovation and demolition of old buildings is on the stage together with the design and construction of new buildings every day in downtown of the old city area. The coordinative symbiosis between new and old buildings is an important problem which needs to be solved in the process of urban development. By studying and analyzing the case of Shanghai Citic Plaza and surroundings, this paper contributes to discussing the concept, value and problems to be solved of the coordination of new and old buildings, meanwhile, striking the balance between new and old buildings from the aspects of architectural form, space, function and local context. As a result, the strategy of the coordinative symbiosis between new and old buildings is summarized, which can offer some guiding principles to urban development from now on.

Keywords: Coordinative symbiosis, new and old buildings, Shanghai Citic Plaza, strategy.

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2006 Delay and Energy Consumption Analysis of Conventional SRAM

Authors: Arash Azizi-Mazreah, Mohammad T. Manzuri Shalmani, Hamid Barati, Ali Barati

Abstract:

The energy consumption and delay in read/write operation of conventional SRAM is investigated analytically as well as by simulation. Explicit analytical expressions for the energy consumption and delay in read and write operation as a function of device parameters and supply voltage are derived. The expressions are useful in predicting the effect of parameter changes on the energy consumption and speed as well as in optimizing the design of conventional SRAM. HSPICE simulation in standard 0.25μm CMOS technology confirms precision of analytical expressions derived from this paper.

Keywords: Read energy consumption, write energy consumption, read delay, write delay.

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2005 Methodology for Obtaining Static Alignment Model

Authors: Lely A. Luengas, Pedro R. Vizcaya, Giovanni Sánchez

Abstract:

In this paper, a methodology is presented to obtain the Static Alignment Model for any transtibial amputee person. The proposed methodology starts from experimental data collected on the Hospital Militar Central, Bogotá, Colombia. The effects of transtibial prosthesis malalignment on amputees were measured in terms of joint angles, center of pressure (COP) and weight distribution. Some statistical tools are used to obtain the model parameters. Mathematical predictive models of prosthetic alignment were created. The proposed models are validated in amputees and finding promising results for the prosthesis Static Alignment. Static alignment process is unique to each subject; nevertheless the proposed methodology can be used in each transtibial amputee.

Keywords: Information theory, prediction model, prosthetic alignment, transtibial prosthesis.

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2004 Adaptive Fuzzy Control on EDF Scheduling

Authors: Xiangbin Zhu

Abstract:

EDF (Early Deadline First) algorithm is a very important scheduling algorithm for real- time systems . The EDF algorithm assigns priorities to each job according to their absolute deadlines and has good performance when the real-time system is not overloaded. When the real-time system is overloaded, many misdeadlines will be produced. But these misdeadlines are not uniformly distributed, which usually focus on some tasks. In this paper, we present an adaptive fuzzy control scheduling based on EDF algorithm. The improved algorithm can have a rectangular distribution of misdeadline ratios among all real-time tasks when the system is overloaded. To evaluate the effectiveness of the improved algorithm, we have done extensive simulation studies. The simulation results show that the new algorithm is superior to the old algorithm.

Keywords: Fuzzy control, real-time systems, EDF, misdeadline ratio.

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2003 Realization of a Temperature Based Automatic Controlled Domestic Electric Boiling System

Authors: Shengqi Yu, Jinwei Zhao

Abstract:

This paper presents a kind of analog circuit based temperature control system, which is mainly composed by threshold control signal circuit, synchronization signal circuit and trigger pulse circuit. Firstly, the temperature feedback signal function is realized by temperature sensor TS503F3950E. Secondly, the main control circuit forms the cycle controlled pulse signal to control the thyristor switching model. Finally two reverse paralleled thyristors regulate the output power by their switching state. In the consequence, this is a modernized and energy-saving domestic electric heating system.

Keywords: Time base circuit, automatic control, zero-crossing trigger, temperature control.

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2002 Efficiency of Floristic and Molecular Markers to Determine Diversity in Iranian Populations of T. boeoticum

Authors: M. R. Naghavi, M. Maleki, S. F. Tabatabaei

Abstract:

In order to study floristic and molecular classification of common wild wheat (Triticum boeoticum Boiss.), an analysis was conducted on populations of the Triticum boeoticum collected from different regions of Iran. Considering all floristic compositions of habitats, six floristic groups (syntaxa) within the populations were identified. A high level of variation of T. boeoticum also detected using SSR markers. Our results showed that molecular method confirmed the grouping of floristic method. In other word, the results from our study indicate that floristic classification are still useful, efficient, and economic tools for characterizing the amount and distribution of genetic variation in natural populations of T. boeoticum. Nevertheless, molecular markers appear as useful and complementary techniques for identification and for evaluation of genetic diversity in studied populations.

Keywords: T. boeoticum, diversity, floristic, SSRs.

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2001 Diversity and Distribution of Benthic Invertebrates in the West Port, Malaysia

Authors: Seyedeh Belin Tavakoly Sany, Majid Rezayi, Rosli Hashim, Aishah Salleh, Omid Safari

Abstract:

The purpose of this paper is to describe the main characteristics of macroinvertebrate species in response to environmental forcing factors. Overall, 23 species of Mollusca, 4 species of Arthropods, 3 species of Echinodermata and 3 species of Annelida were identified at the 9 sampling stations during four sampling periods. Individual species of Mollusca constituted 36.4% of the total abundance, followed by Arthropods (27.01%), Annelida (34.3%) and Echinodermata (2.4%). The results of Kruskal-Wallis test indicated that a significant difference (p <0.05) in the abundance, richness and diversity of the macro-benthic community in different stations. The correlation analysis revealed that anthropogenic pollution and natural variability caused by these variations in spatial scales.

Keywords: Benthic invertebrates, Diversity, Malaysia, West Port.

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2000 CFD Simulations of a Co-current Spray Dryer

Authors: Saad Nahi Saleh

Abstract:

This paper presents the prediction of air flow, humidity and temperature patterns in a co-current pilot plant spray dryer fitted with a pressure nozzle using a three dimensional model. The modelling was done with a Computational Fluid Dynamic package (Fluent 6.3), in which the gas phase is modelled as continuum using the Euler approach and the droplet/ particle phase is modelled by the Discrete Phase model (Lagrange approach).Good agreement was obtained with published experimental data where the CFD simulation correctly predicts a fast downward central flowing core and slow recirculation zones near the walls. In this work, the effects of the air flow pattern on droplets trajectories, residence time distribution of droplets and deposition of the droplets on the wall also were investigated where atomizing of maltodextrin solution was used.

Keywords: Spray, CFD, multiphase, drying, droplet, particle.

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1999 Overall Effect of Nano Clay on the Physical Mechanical Properties of Epoxy Resin

Authors: Alireza BozorgianÏî Navid Majdi Nasab, Hassan Mirzazadeh

Abstract:

In this paper, the effect of modified clay on the mechanical efficiency of epoxy resin is examined. Studies by X ray diffraction and microscopic transient electron method show that modified clay distribution in polymer area is intercalated kind. Examination the results of mechanical tests shows that existence of modified clay in epoxy area increases pressure yield strength, tension module and nano composite fracture toughness in relate of pure epoxy. By microscopic examinations it is recognized too that the action of toughness growth of this kind of nano composite is due to crack deflection, formation of new surfaces and fracture of clay piles.

Keywords: Nano clay, Epoxy, Toughness, Composite

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1998 A Simplified Solid Mechanical and Acoustic Model for Human Middle Ear

Authors: Adarsh Venkataraman Ganesan, Sundaram Swaminathan, Rama Jayaraj

Abstract:

Human middle-ear is the key component of the auditory system. Its function is to transfer the sound waves through the ear canal to provide sufficient stimulus to the fluids of the inner ear. Degradation of the ossicles that transmit these sound waves from the eardrum to the inner ear leads to hearing loss. This problem can be overcome by replacing one or more of these ossicles by middleear prosthesis. Designing such prosthesis requires a comprehensive knowledge of the biomechanics of the middle-ear. There are many finite element modeling approaches developed to understand the biomechanics of the middle ear. The available models in the literature, involve high computation time. In this paper, we propose a simplified model which provides a reasonably accurate result with much less computational time. Simulation results indicate a maximum sound pressure gain of 10 dB at 5500 Hz.

Keywords: Ear, Ossicles, COMSOL, Stapes.

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