bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of Infra‐Particle C‐CO2 Reaction: An Application of the Random Pore Model
Authors: Liu G.S. , Tate A.G. , Rezaei H.R. , Beath A.C. , Wall T.F.
Published: August 2010

The Random Pore Model developed by Bhatia et al. was applied to intra‐particle gasification reactivity of carbon with carbon dioxide in present contribution. Instead of the conventional n‐th order equation, the Langmuir‐Hinshelwood equation, which treats reaction to be an adsorption and desorption two‐step reaction, was employed as an expression for the carbon and carbon dioxide surface reaction in the model. A balance between gas diffusion and consumption for each position in the particle was established as derived in the Thiele analysis. Numerical calculations were carried out to solve the integrated equations. The results show that a big difference of reaction rate is exhibited between using the n‐th order rate expression and the Langmuir‐Hinshelwood (L‐H) equation. The results also show the distributions of CO2 partial pressure, surface area, reaction rate and carbon conversion within the particle during the gasification. The overall conversions at different structure parameters, which are correspondent to initial porosity of 0.05, 0.2 and 0.4, are also presented in the paper. A small deviation of the effectiveness factors obtained between using the Langmuir‐Hinshelwood and the n‐th order equation is indicated with the carbon burn‐off between 0–85%.
The Influence of the Properties of Activated Bagacillo on Cr(VI) Adsorption
Authors: Valix M. , Siliezar J. , Zhang K.
Published: August 2010

The present study deals with the adsorption of Cr(VI) in a series of carbons prepared from bagacillo, which is a lignocellulosic by‐product from a sugar milling operation. Activated carbons were prepared by chemical activation using ZnCl2, CaCl2, H3PO4 and Ca(OH)2 and physical activation with steam and carbon dioxide. The effects of the chemical nature and the pore structures on the adsorption behaviour of these activated carbons were investigated. The functional groups present on the surface of the carbons were differentiated and related to the observed adsorption behaviour of the carbons. It appears that adsorption is strongly influenced by the pH of the carbon, where acidic functional groups appear to enhance the adsorption behaviour. Fine micropore structures appear to exhibit a molecular sieve effect. Restrictive pores, present in carbons with high surface areas, appear to inhibit the access of Cr(VI) into the micropore structures resulting in low adsorption.
Highly Effective Catalysts for N2O Conversion to N2—A Preliminary Study
Authors: Zhu Zhonghua , Zhuang Yahui , Shen Dixin , Lu G.Q.(Max)
Published: August 2010

Catalytic conversion of N2O to N2 with Cu‐ and Co‐ impregnated activated carbon catalysts (Cu/AC and Co/AC) was investigated. The relationship between N2O conversion and metal (Cu and Co) content was examined. The catalysed N2O‐carbon reaction was studied in a fixed‐bed flow reactor at atmospheric pressure. Two modes of experiments were employed: (i) temperature‐programmed reaction (TPR) in a N2O/He mixture; and (ii) isothermal reaction at 350 d̀C to 380 d̀C. Both Cu and Co catalyse the N2O‐ carbon reaction effectively, which is shown by the decrease in activation energy and the substantial shift of N2O reduction curves toward much lower temperatures. A 20wt% metal loading has proved to be optimal for both Cu and Co, which can lead to 100% of N2O conversion at 400 d̀C for both cases. At lower temperatures, Co/AC is more active, whereas at higher temperatures Cu/AC is much more stable. The reaction mechanisms are discussed in this paper based on the TPR curves, the isothermal reactivity data and distribution of the products.
Modelling for Flash Calcination and Surface Area Development of Dispersed Limestone Particles
Authors: Ying Z. , Chuguang Z. , Zhaohui L. , Xuefeng S.
Published: August 2010

A mathematical model for calcination, sintering and surface area development of dispersed limestone particles is presented in the paper. The model describes the calcination by considering heat transfer, mass transfer of CO2 through a porous CaO layer, and the chemical kinetics. Diffusion of CO2 in a porous product layer is discussed in detail. The extent of calcination, BET surface area, temperature and pressure distribution in a particle were calculated. The extent of calcination and BET surface area, obtained from the simulation, are consistent with experimental data.
Study on Emission Control of NOx and N2O in a Fly‐ash Recycle Fluidized Bed Test Rig
Authors: Zhong Z. , Lan J. , Jin B. , Han Y.
Published: August 2010

Experiments on NOx and N2O release characteristics and emission control were studied in a fly‐ash recycle fluidized bed test rig. The total height of the fluidized bed is 4.4m. The fluidization section is 1.2m high with a cross‐section 0.23mx0.23m. The freeboard is 3.0m high with a cross‐section 0.460mx0.345m. The coal‐fired weight of the test rig is 30 kg/h, and coal is fed by a screw feeder. Fine ash is collected by a cyclone and recycled to the bed surface through a J‐valve, slag is then removed from the bottom. An oil‐fired start‐up burner is also used. Test fuels are Xuzhou bituminite and Kenan anthracite from China with particle range of 0‐8mm. When the bed temperature rises, NOx increases and N2O decreases. At the same temperature, N2O emission of bituminite is less than that of anthracite. While the secondary air ratio reached 15% under staged combustion, NOx emission decreased to 14% and N2O emission decreased to 24%. As the Ca/S molar ratio increases, NOx emission also increases while N2O emission decreases. Ammonia injection decreases NOx emission significantly, but it has no effect on the emission of N2O.
Study on Flow Properties of Coal‐Water Paste in Pipes
Authors: Meng L. , Zhang M. , Shen L.
Published: August 2010

In this paper the similitude criterion known as generalized Reynolds number \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm{Re}}_g = \frac{{\rho VD\left[ {a^{n - 1} \left( {1 - a} \right)} \right]^{1/n} }}{{K^{1/n} \tau _y^{1 - 1/n} \left( {1 - U_s /V} \right)}}f\left( a \right) $\end{document} is proposed to characterize the flow state of coal‐water paste in pipes, on the assumption of coal‐water paste as a non‐Newtonian fluid and for slip flow phenomenon in pipes. It can be used to describe the no‐slip flow of non‐Newtonian and Newtonian fluids behaving as steady‐state laminar flow in pipes. A convenient new method of determining the resistance properties of coal‐water paste is suggested.
Process Control and Optimization in Energy Utilization and Environmental Protection
Authors: Tadé M. O.
Published: August 2010

An evolving goal in power plants for many decades is to have the process control system predict and optimize the set‐point changes continuously in real time and to automatically regulate flows, temperatures, and pressures. This goal has now become more significant and more involved because a fourth dimension, the environment, has been added to the three traditional dimensions (namely, safety, efficiency and cost) of real time power plant performance. In this paper, the emerging role of process control and optimization is reviewed within the context of energy utilization and environmental protection. Case studies that have been reported in this area are discussed. Some limitations of the current technology are identified.
Mathematical Model of a Continuous Galvanizing Annealing Furnace
Authors: Tian Y.‐C. , Hou C.‐H. , Gao F.
Published: August 2010

A state space model discrete in time and space was developed for on‐line and realtime computation and prediction of strip temperature in a continuous galvanizing annealing furnace. The model development was based on a combination of physical modeling and system identification. An equivalent heat transfer coefficient was introduced to simplify the physical relations of the process. Compact model expressions suitable for on‐line and real‐time computation were obtained using the finite difference technique. A stability analysis of the model was conducted to guide the selections of time and space steps. System identification aspects were also discussed. The model was successfully applied to industry with good performance.
Guaranteed Cost Sampled‐Data Control for Refining Process
Authors: Lu Yingquan , Kong Yaguang , Wang Wenhai , Sun Youxian
Published: August 2010

This paper presents a synthetic design procedure of guaranteed cost sampled‐data control (GCSDC) for refining process. When a digital controller controls the refining process with appropriate sample and hold devices, the closed loop system is periodic time varying. Based on this sampled‐data system, considering the uncertainties in the continuous‐time plant, we define the guaranteed cost control and a controller that not only stabilizes the closed loop system but also guarantees an adequate level of the performance. Simulation results show that the control scheme is effective and practicable.
A Combined Model for Supervisory Control of Continuous Processes
Authors: Xianhui He , Chunhua Gao , Hui Wang
Published: August 2010

Using Hybrid Petri Nets (HPNs) together with a continuous mathematical model, a combined modeling method for continuous‐process dynamic scheduling and supervisory control is presented. This method can describe both continuous characteristics of a continuous process and its discrete control strategies on the same level. An ideal binary mixture distillation column is used as an example to illustrate the proposed method. Based on the combined model, a supervisory control scheme is also provided.
Finite Word Length Implementation for Digital Reduced Order Observer Based Controllers
Authors: Wu J. , Chu J. , Chen S. , Li G.
Published: August 2010

Implementation issues for digital reduced‐order observer‐based controllers with Finite Word Length (FWL) considerations is studied. A tractable FWL stability related measure is derived, and the optimal FWL realization problem for digital reduced‐order obverser‐based controller is to find those realizations that maximize this related measure. This optimization problem is formulated as an unconstrained nonlinear programming problem which can be solved using the simplex search algorithm. A numerical example is given to illustrate the design procedure and the effectiveness of the proposed method.
Analysis and Implementation of the Double‐Controller Scheme
Authors: Tian Y.‐C. , Gao F.
Published: August 2010

This paper gives some insight into the double‐controller scheme proposed recently. The double‐controller scheme has good robustness as well as simultaneous fast set‐point tracking and good load rejection. Investigations show that it enhances the conventional feedforward control. The stability and robustness of the control scheme are analyzed in the frequency domain and compared with those of the Smith predictor. To further improve the performance of the double‐controller scheme, techniques are proposed to accommodate large uncertainties in process delay time and gain. Two control signals of the double‐controller scheme are employed for extraction of process parameter information and on‐line tuning of the control system. The effectiveness of the proposed techniques is verified through numerical simulations.
An Integrated L‐Lysine Fermentation Model with Agitation Speed as the Manipulated variable
Authors: Yao H.M. , Tian Y.‐C. , Tadé M.O. , Ang H.M.
Published: August 2010

The L‐lysine fermentation process by Brevibacteria lactofermentum was investigated for improvement of process performance by manipulating cellular environmental conditions through computer monitoring and control. The main factor under consideration was dissolved oxygen concentration (DOC) in the broth. An integrated process model with agitation speed as the manipulated variable was developed for the model‐based controller using combined kinetic study and material balances. The selection of rate equations, which properly describe the specific process, was studied and the influence of different dissolved oxygen (DO) conditions to model parameters was discussed. A first order with time delay model was used to describe the oxygen transferred from gas to liquid phase. The dynamic behaviour of time constant, system gain, yields and maintenance coefficient were considered and closely correlated to the broth concentrations. The Nelder and Mead optimisation method was used for identification of all model parameters.
Hybrid Automaton Model and Control of Hybird Systems
Authors: Zhang Wei , Sun Youxian
Published: August 2010

A hybrid automaton model is proposed in this paper for hybrid systems. The model, with particular emphasis on process control applications, is based on the dynamic features of hybrid systems. It takes into account the discrete dynamics of hybrid systems in particular and can clearly separate the controller from the closed‐loop system. The definition of controllability of hybird systems with respect to the marked regions is also given. An analyzing algorithm and sufficient and necessary condition for controllability based on the hybrid automaton model are discussed. At the same time, the property of the loops in the trajectory of the closed‐loop plant is studied. Finally, the synthesis scheme for a hybrid controller is given. In this scheme, the controller consists of two parts, the discrete supervisor and the continuous regulator. The closed‐loop plant with the controller is state‐controllable.
Formulae of the Infimal Controllable and Observable Sub‐language and Synthesis of Its Supervisor
Authors: Wenjun Yan , Weinong Shentu
Published: August 2010

The Supervisory Control Theory of Discrete Event Dynamical Systems (DEDS) is one main approach of studying DEDS in recent years. The existing condition of the supervision and the synthesizing method under partial controllable and observable events are investigated. A formula for the infimal prefix closed controllable and observable sub‐language of a given language is presented. The effectiveness of the method is illustrated with two examples.
Robustness Bound of LQ Guaranteed Cost Control Systems for Parameter Uncertainty
Authors: Xue Anke , Chen Yao , Sun Youxian
Published: August 2010

The problem of robustness bound for parameter uncertain systems with LQ guaranteed cost controller is considered in this paper. A parameter dependent robustness bound for parameter uncertainties is derived. Then, an optimization problem of improving the robustness of parameter uncertain systems is proposed. And also, the responding optimization technique is given in the paper.
The Partitioning of Arsenic, Selenium, Cadmium, and Cesium during Pulverized Coal Combustion in a 17 kW Downflow Combustor
Authors: Seames Wayne S. , Wendt Jost O. L.
Published: August 2010

The combustion of coal liberates arsenic, selenium, cadmium, and cesium into the environment. These toxic metals, which are discharged with the flue gas or collected with fly ash, may vaporize in the hot portions of the combustor then return to the solid phase in cooler zones of the process downstream. Understanding the mechanisms by which toxic metals partition between the vapor and solid phases is an important step for predicting and mitigating the effect of these metals upon the environment. An investigation of these partitioning mechanisms was performed. The results suggest that the dominant heterogeneous partitioning mechanism for transformation to the solid phase in the post‐combustion zone is the reaction of metal vapor on the surface or within the pores of a supermicron ash particle for the Pittsburgh seam and Illinois #6 coals but not for the Ohio blend coal. A relationship between the concentration of supermicron phase arsenic, selenium, and cadmium to calcium was also observed, suggesting the formation of As‐Ca, Se‐Ca, and Cd‐Ca reaction products. Selenium appears to be more reactive than arsenic for the formation of these calcium‐based complexes.
A Model for Flue Gas Desulfurization with Lime Absorbent at Middle Temperature
Authors: You Chang‐Fu , Qi Hai‐Ying , Wang Wei , Xu Xu‐Chang
Published: August 2010

A model to simulate the desulfurization process for reaction of flue gas with lime at middle temperature (400‐800d̀C) has been established based on the grain model. The rationality of the model has been examined by making comparison between the calculated values of the model and the experimental results. The effects of certain parameters on conversion of CaO have been analyzed. Establishment of this model provides the initial foundation for the development of flue gas desulfurization technology with lime absorbent at middle temperature.
Time Optimal Control of a Binary Distillation Column
Authors: Luus Rein
Published: August 2010

Time optimal control problems involving high dimensional systems are generally very difficult to solve. Instead of using suboptimal control based on reduced system, iterative dynamic programming is used directly to establish the time optimal control policy of a binary distillation column described by 11 ordinary differential equations. The resulting optimal control policy that is bang‐bang in nature was obtained very rapidly. The minimum time of 2236 seconds obtained here is substantially better than 4120 seconds obtained by a suboptimal control policy. Simulations show that the procedure may be used for on‐line optimal control of the distillation column, since the optimal control policy can be established very fast on a personal computer.
Simulation and Optimization of Linear Alkylbenzenes Distillation Process
Authors: Hu Yongyou , Su Hongye , Lu Jingwei , Mu Shengjing , Chu Jian , Wu Jun
Published: August 2010

The pure linear alkylbenzenes (LAB) are widely used in detergent manufacture, which are generally obtained by alkylation of benzene with linear C9‐C13 olefins How to decrease the loss of LAB during the distillation process is always the focus of manufacturers' attention In this paper, a mathematic model of a newly rebuilt LAB distillation process is established and some operation and control problems are studied by simulation and analysis we not only find the bottleneck and the optimal operating conditions of the distillation process, but also locate the new sensitive plates with optimal ranges of temperature The simulation results indicate that the loss of LAB can be reduced from 1.0% to 0.05%, simultaneously with the distillate of regular LAB product (>99.5% mass fraction) increases of 600 kg/h under the optimal operating conditions
Application of Adaptive Fuzzy Neural Network for Forecasting Coal Slagging in a Power Station
Authors: Zheng Chuguang , Liu Gehui , Huang Yongli
Published: August 2010

Ash related problems in coal‐fired power plants result in decreased efficiency, unscheduled outages, equipment failures and cleaning problems Assessing the potential impact of ash on power plant performance is extremely complicated and difficult due to coal variability, complexity of the ash behavior processes and changes in operating conditions involved This study introduces a new method of coal slagging forecast This method employs a hybrid‐learning rule composed of recursive least‐squares estimation and a gradient descent algorithm The forecast results are compared with measured data The comparison shows that the method based on adaptive fuzzy neural network for the prediction of coal slagging has the advantages of high precision, fast convergence and perfect adaptability
Internal Heating Effect and Application of Microwaves with Fluidization of Electrically Conductive Particles in the Ceramic Drying Process
Authors: Itaya Y. , Okouchi K. , Uchiyama S. , Mori S. , Hasatani M.
Published: August 2010

In the ceramic drying process, it takes a long time to completely remove internal moisture from molded ceramics due to large resistance of internal migration. Microwave heating is an effective internal heating method and will promote the moisture movement rate inside ceramics due to the elevation of vapor pressure. The effect of internal uniform heating on the ceramic drying behavior is first studied by theoretical analysis. The effectiveness and problems of drying of a slab heated by microwaves were evaluated experimentally and compared with hot air heating. The drying proceeded successfully and quicker than hot air heating when the internal temperature could be controlled below 380 K, by introducing intermittent heating or low power irradiation of microwaves. Additionally, a technique for improving uniformity of the microwave field by fluidization of electrically conductive particles was proposed. The distribution of the microwave field became successively uniform by the diffuse reflection of microwaves in a fluidized bed of plastic foam particles wrapped in aluminum foil.
Pulse Combustion and Supercritical Fluid Techniques as Examples of Innovative Drying Technologies
Authors: Rogacki G. , Strumillo C. , Wawrzyniak P. , Zbicinski I.
Published: August 2010

In this paper the need for innovative drying techniques is suggested. Pulse combustion and supercritical fluid techniques which were developed in the drying laboratory of the Lodz Technical University are presented as examples. In the section concerned with pulse combustion, valved and valveless pulse combustors are described and several features of both types are identified. The advantages and drawbacks of the pulse combustor are presented. The selection of a pulse combustor, its geometry and atomizer as well as enhancement of drying rate are discussed. The importance of the high driving force in this process intensification is stressed. In the section dedicated to supercritical fluid techniques, high‐ and low‐temperature procedures of drying are described. The most important aspects of the drying cycle are discussed with special reference made to the kinetics of diffusive solvent exchange inside a wet gel body.
Separation and Mineralogical Analysis of Bayer Red Mud
Authors: Picaro T. , Pei B. , Kane A.R. , Thornber M.R. , Fletcher A.B.
Published: August 2010

This paper describes preliminary work to assess the potential for recovering valuable components from Queensland Alumina Limited (QAL) red mud by physical beneficiation. Upgrading of Weipa bauxites residue was trialed using a 50 mm hydrocyclone and a Mozley Multigravity Separator (MGS) to recover desilication product (DSP) and TiO2 fractions. The mineralogy of the original red muh and the various sub‐fractions produced was studied by chemical assay, selective leaching, XRD and SEM techniques.

DSP is present in QAL red mud in two forms: (i) as balls in the size range from 0.8 to 10 μm that appear to be liberated; and (ii) as finely grained DSP intermixed with the other minerals. The hydrocycloning tests produced a DSP rich (39.5 wt%) fraction at 89% recovery from a feed containing 31.9 wt.% DSP. This represents an upgrade (enrichment) of 1.24 times. These results suggest that the greatest DSP enrichment will be achieved by targeting the 0.8 to 10 μm DSP balls.

The richest TiO2 fraction produced varied from 20 to 36 wt.% TiO2 from a feed value of 7 wt.% at a recovery of 7.5%. Mineralogical examination showed that most of the TiO2 in this fraction was as liberated particles in the size range 8 to 20 μm. Most of the TiO2 particles in the other fractions were not fully liberated from mainly iron minerals.

The present work indicates that it is possible to further upgrade DSP fractions by investigating finer particle separation techniques, e.g. smaller, 25 mm and 10 mm, hydrocyclones.
Thoughts on Recovering Particle Size Distributions from the Moment Form of the Population Balance
Authors: Flood A. E.
Published: August 2010

The moment form of the population balance is a very popular method of modeling the evolution of particle size in many particulate systems. In many cases the moments of the particle size distribution are sufficient to characterize the system for engineering purposes, however in some cases an approximation to the particle size distribution itself is desired. The traditional method to achieve this approximation is to write the set of (known) moments in matrix form, μ = A.n, and then solve this equation, via matrix inversion, to obtain the population density, n, in a finite number of size classes. The method of matrix inversion may result in a poor approximation, particularly if the distribution is too complex to be represented by a small set of finite width pulses. Several alternative methods are discussed including a similar method based on the central moments, and fitting the moments to known types of distribution functions, the gamma distribution in particular. The inversion method involving central moments improves the conditioning of the matrix. This did not improve the result when small numbers of moments (six or less) were used, because accurate inverses of the matrix for the moments about the origin could be achieved. Fitting moments to known distributions is computationally more difficult than the inversion technique because of the optimization required, but this is not a significant drawback due to the widespread availability of computation mathematical programs. This method was particularly successful in reproducing accurate distributions.
Aggregation Behaviour of Gibbsite Crystals in Supersaturated Sodium and Potassium Aluminate Liquors
Authors: Addai‐Mensah Jonas , Li Jun , Prestidge Clive A.
Published: August 2010

The aggregation behaviour of colloidal size gibbsite crystals in synthetic supersaturated caustic aluminate liquors has been investigated as a function of solution alkali metal ion type and Al(III) relative supersaturation in crystallization studies. The results indicate that alkali metal ions (Na+ versus K+) and supersaturation play an influential role in the particle aggregation mechanism. The initial particle aggregation rate is linearly dependent upon Al(III) relative supersaturation, and is significantly greater in Na+ rather than in K+ based suspensions. The study demonstrates that the initial orthokinetic aggregation and subsequent cementation both lead to faster agglomeration in sodium than in potassium aluminate liquors
An Experimental Study of Combustion Characteristics of Petroleum Coke
Authors: Mi T. , Wu Z.S. , Shen B.X. , Liu D.C. , Chen H.P.
Published: August 2010

The combustion characteristics of petroleum coke have been analyzed by the TGA method. The same tests have also been performed to determine the combustion characteristics of 3 types of coals for comparison. The combustion tests and measurement of the pollutant emissions for petroleum coke and a mixture of petroleum coke and coal have been performed in a bench‐scale CFB rig by limestone addition. The pollutant emissions have been measured by an on‐line analyzer. The results show that the index of combustion characteristics of the petroleum coke is higher than that of anthracite, and lower than that of soft coal, and close to lean coal. During the 72‐hour combustion tests, agglomeration and slagging were not observed. The combustion is stable and the pollutant emissions are within the environmental standards.
Some Dynamic Features of Fluidised Bed Reactors for Partial Oxidation of o‐Xylene.
Authors: Abashar M.E.E.
Published: August 2010

A dynamic analysis of fluidised bed reactors for the partial oxidation of o‐xylene to phthalic anhydride is presented. The theory of bifurcation, continuation and Poincareé techniques play key roles in the analysis. A new type of period‐adding bifurcation of Poincaré return points is observed and is shown to generate a complex dynamic behaviour. The period adding is classified as a second kind of period adding according to the classification of Holden and Fan [15]. It is found that relaxation oscillations develop through distortion of limit cycles, which have fast and slow motion in the different regions of the phase space.
Transport Process in Electrolytic Membrane Flow Reactor for Producing Strong Acid Water
Authors: Kanki Tatsuo , Katayama Shigeyuki , Sano Noriaki , Tatsumi Yoshiki , Hasegawa Kazuhiko
Published: August 2010

In order to establish the optimum condition for designing an electrolytic membrane flow reactor for producing strong acid water, a test reactor was developed. The pH, concentration of residual chlorine and oxidation reduction potential of the electrolytic acid water produced by the reactor were measured against applied voltage by changing the sodium chloride concentration and feed rate of water. Mass transport accompanied by electrolytic reaction of hydrogen, hydroxide, and the other related ions in the reactor was formulated and the analytical solutions to local concentrations of the related ions were presented. The relevant transport coefficients and physicochemical constants included in the model equations were determined and compared with the experimental data. It was shown that pH, residual chlorine concentration and oxidation reduction potential of the acid water can be accurately estimated from the present analytical solutions with the empirical physicochemical constants.
Effect of Alloying Elements on the Rate of Growth of Individual Pits on Stainless Steels
Authors: Marinovich Y. , Fukutsuka T. , Matsuo Y. , Sugie Y.
Published: August 2010

Potentiodynamic polarization curves of five different commercially available stainless steels (SS) were measured in air‐saturated 0.5 M NaCl (25d̀C, pH = 5.2). This data gave useful information on the corrosion behavior of the alloys in this system. It was found that the potential at which pitting begins becomes more positive with increasing Cr and Ni content. A strong relationship between the magnitude of the cathodic current density and the electrode surface area was also observed, and a reason for this observation was suggested. Potentiostatic pitting experiments were performed in order to determine the effect of Cr, Ni, Ti and Mo concentrations on the growth rate of a single pit. However, quantitative data was not obtained since it proved difficult to form a single pit on the SS microelectrode. Instead, many pits formed over the surface thus making quantitative analysis of the current transients impossible. The reason for this phenomenon is still unclear. With 316 SS, both ideal hemispherical and irregularly shaped pits were observed to occur together. From Electron Probe Micro Analysis (EPMA) mapping it was shown that sulfide inclusions were probably not responsible for producing pit nucleation sites on 316 SS.
The Use of Aqueous‐based Emulsion Polymers as Moisture Barrier Coatings for Carton Boards
Authors: Ryan N. M. , Mcnally G. M. , Welsh J.
Published: August 2010

The rate of moisture permeation through paper carton boards can be critical in high peformance packaging applications. Moisture barrier paperboards have been developed using aqueous‐based emulsion polymers, and the results obtained with these materials are presented. These polymers include polyethylene terephthalate (PET), polyvinylidene chloride (PVdC), and styrene‐based emulsions. A range of these coated carton boards were prepared using a hand coater to achieve a controlled range of barrier layer thickness (6–100 microns). Water vapour transmission rate (WVTR) analysis was carried out on these coated boards over a range of temperatures and relative humidities. In addition, some boards were precoated with a primer coat before the application of the barrier topcoat in order to investigate the effect of carton board topography on the moisture barrier properties. Low WVTRs in the range of 3–10 g/(m2 day) were achieved using several of the emulsion polymers. It is clearly shown that pre‐coating the surface of a board with aprimer before applying a barrier coat can lower the WVTR further even with a thinner overall layer of coating. Analysis also illustrated that boards coated on one side exhibited anisotropic characteristics, with lower WVTRs always being achieved when the coated side of the board is adjacent to the higher humidity.
The Effect of Rapid High Temperature Excursions on the Moisture Absorption and Dynamic Mechanical Properties of Carbon Fibre Epoxy Composite Materials
Authors: Mcnally G. M. , Mccourt M. P. , Spedding P. L.
Published: August 2010

The effect of elevated temperature excursions (thermal spiking) on the moisture absorption characteristics and dynamic mechanical properties of Cycom 8 HS carbon fibre epoxy laminates was investigated. Cured laminate samples were preconditioned (65d̀C, 95%R.H.) and these samples were exposed to various thermal spiking (150d̀C/2min) programmes. Dynamic mechanical thermal analysis (DMTA) techniques measured the changes in glass transition temperature (Tg) storage modulus (log E') and damping (Tan δ max) of the laminates as a result of exposure to these environments. The thermal spiking programme was shown to cause an increase in both the amount and rate of moisture absorption of the laminates. These increments were accompanied by a significant decrease in Tg, log E', and Tan δ max. Scanning Electron Microscopy (SEM) analysis also showed the progressive growth of both interlaminar and translaminar micro‐cracks as a result of thermal spiking.
Simulating the Heat Transfer Process of Horizontal Anode Baking Furnace
Authors: Zhang Liqi , Zheng Chuguang , Xu Minghou
Published: August 2010

A transient two‐dimensional mathematical model of a horizontal baking furnace is presented. The model combines complicated thermal phenomena in the baking process such as air infiltration, evolution and combustion of volatile matter; combustion of packing coke, and heat losses. The predicted results are in good agreement with measured data. Furthermore, the processes are simulated under different operating conditions such as firing cycle time, airflow and air infiltration. The simulated results indicate that the fuel consumption decreases as the firing cycle time decreases, it is also found that reducing the airflow and air infiltration will assist fuel efficiency. The model has proved to be a useful tool in the process optimization of the baking furnace in the aluminum industry.
Organic Carbon Mineralisation in a Subtropical River
Authors: Pollard P. C.
Published: August 2010

Microorganisms mediate the many biochemical transformations of aquatic ecosystems. Heterotrophic bacteria mineralise most of the total carbon of freshwater and marine ecosystems via the dissolved organic carbon (DOC) fraction. This paper describes the relationship between primary and heterotrophic microbial production in a major subtropical river in South East Queensland, Australia, in dry weather. Stormwater was not the major external source of organic carbon in dry weather. The rate of heterotrophic bacterial production was 4 g C m−2 d−1. The bacteria were decomposing over four times more organic carbon per day than the daily primary production (1.1 g C m−2 d−1). There was not sufficient organic carbon generated through photosynthesis to support the heterotrophic bacterial growth. The river ecosystem was net heterotrophic. However, the concentration of the DOC in the water column remained relatively constant. The bacteria mineralised the DOC pool every few days. This suggests that organic carbon was constantly being supplied to this aquatic ecosystem from a terrestrial source that was readily degradable. The organic carbon pollution was likely due to non‐point sources related to human activities in the catchment.
Explicit Calculation of the Friction Factor for Non‐Newtonian Fluids Using Artificial Neural Networks
Authors: Shayya W. H. , Sablani S. S. , Campo A.
Published: August 2010

An explicit procedure based on artificial neural networks (ANN) was developed for calculating the friction factor (f) for Herschel‐Bulkley fluids under laminar and turbulent flow conditions in closed pipes. The Regula‐Falsi method was used as an iterative procedure to estimate the f values for a range of flow behavior indexes (n), Reynolds numbers (Re), and Hedstrom numbers (He). In developing the ANN model, the input parameters Re and He and the output parameter f were transformed using a logarithmic scale to the base 10, while the input parameter n was taken on a linear scale. An ANN configuration with 16 neurons in each of two hidden layers was found to be optimal. However, a simpler ANN model with eight neurons in one hidden layer also produced reasonably good predictions. These values were in close agreement with those obtained using the numerical technique. The developed ANN model may offer significant advantages when dealing with flow problems that involve repetitive calculations of the friction factor such as those encountered in the hydraulic analysis of viscous non‐Newtonian fluids in pipe networks.
Preliminary Investigation of the Applicability of a Simulated Set‐up to Assess Membrane Fouling by Residence Time Distribution Studies
Authors: Hardin M. T. , Chen X. D. , Rochilly B. , Patel P.
Published: August 2010

Fouling of membrane systems represents significant cost in time, maintenance and quality in the food and dairy industry. While gross methods of fouling determination such as flux decline and changes in transmembrane pressure are adequate to determine the overall extent of fouling, finer tools are necessary to properly diagnose fouling and to properly assess the effectiveness of cleaning regimes. This study investigates the effect of simulated and actual fouling on the residence time distribution of a single pulse through a single membrane sheet. The differences in residence time distribution observed allow an assessment of the degree and spatial position of fouling material without any need to disrupt the operation of the membrane. This method can be used to assess the need for cleaning and maintenance as well as the effectiveness of cleaning regimes.
Experimental Investigation into Wall Deposition of Milk Powder in Spray Dryers
Authors: Ozmen L. , Langrish T.A.G.
Published: August 2010

The effect of varying the inlet air swirl, inlet air temperature and liquid feed flowrate on the wall deposition flux of skim milk powder has been investigated in a small‐scale, co‐current spray dryer. The spray dyer was a cylinder‐on‐cone unit with diameter 0.8 m and height 2 m, fitted with adjustable swirl vanes surrounding a Delavan GAI two‐fluid atomizer. In this work, swirl vane angles of 0d̀, 25d̀, and 30d̀, inlet air temperatures of 170d̀C, 200d̀C, and 230d̀C, and feed flowrates of 1.4 kg h.−1, 1.6 kg h−1′ and 1.8 kg h−1 were used. The wall deposition flux was found to be significantly influenced by inlet air swirl, with the highest swirl vane angle of 30d̀ giving rise to the highest wall deposition flux of 13 g m−2 h−1. For the skim milk powder, the difference between the particle temperature and sticky‐point temperature was also found to be important in influencing the wall deposition flux. When the outlet particle temperature was furthest above the sticky‐point temperature and the inlet air temperature was lowest ( 170d̀C), then the wall deposition flux was the highest at 16 g m−2 h−1. It is likely that cohesion is the critical process in the wall deposition of milk powder. The effect of grounding the dryer on the deposition flux did not appear to be very significant. The measured deposition rates appear to be representative of those in industrial equipment.
Fractionation of Proteins Using Ultrafiltration: Developments and Challenges
Authors: Wan Y. , Cui Z. , Ghosh R.
Published: August 2010

In recent years ultrafiltration has attracted significant interest as a potential technology for fractionating proteins. Although traditionally thought to be suitable for size‐based separation with high‐throughput but relatively low‐resolution, recent research has demonstrated that it is possible to significantly increase the selectivity in protein fractionation using ultrafiltration while still maintaining its inherent high‐throughput. This paper reviews recent developments in the area of protein fractionation using ultrafiltration, with focus on strategies employed to improve selectivity of separation. Several new techniques, technological developments, and their applications for selective ultrafiltration of proteins are also briefly introduced.
Mathematical Modelling of Non‐Linear Solvent‐Gradient Simulated Moving Bed Chromatographic Separation Processes
Authors: Lu J.‐G. , Sun Y.‐X.
Published: August 2010

The solvent‐gradient operation mode exploited within simulated moving bed (SMB) chromatographic separation processes can be used to improve the efficiency of separations. A detailed model that takes into account non‐linear isotherms, solvent gradient, mass transfer resistance, and the discrete event of port periodic switching, was developed in order to simulate the complex dynamics. All design parameters (number, configuration, length and diameter of columns, particle size) and operating parameters (switching period, flow rates of feed, raffinate, desorbent, extract and recycling flow, feed concentrations, different volume fraction of the weak solvent in desorbent and feed) can be chosen correctly by numerical simulation. This model can facilitate the design, operation, optimization, control and scale‐up of the non‐linear solvent‐gradient SMB (SG‐SMB) units.
Soft Sensor Based on Relevance Vector Machines for Microbiological Fermentation
Authors: Sun Zonghai , Sun Youxian
Published: August 2010

Microbiological fermentation is a type of complicated butch process that is severely nonlinear and time variant system. Many process parameters are required to be monitored and controlled in order to make the microbiological fermentation process successful. Therefore, it is particularly important to measure the process variables, however the instrumentation and sensors available for fermentation control do not cover all the desirable or necessary measurements. In fermentation processes, many important internal variables cannot be measured. Soft sensor has become an indispensable method that measures internal variables in fermentation processes. In this paper, the relevance vector machine has been shown to provide an effective method for constructing a soft sensor for microbiological fermentation. The results obtained have demonstrated that the relevance vector machine soft sensor can estimate the internal variables in fermentation process.
Real‐time Optimization of Acetaldehyde Production Process
Authors: Zhijiang Shao , Jinlin Wang , Jixin Qian
Published: August 2010

A real‐time optimization (RTO) system of an acetaldehyde production process is presented in this paper. Data reconciliation with steady state detection and gross error detection, soft sensoring of coarse acetaldehyde concentration, formulation and implementation of yield optimization are discussed in detail. The effect of the RTO system described was validated in an industrial chemical plant, with an average 2.68% increase in yield promotion obtained, which confirms the effectiveness and practicability of the proposed technique.
Electrolyte Inventory Control in a Senate Leach Plant
Authors: Folet M.W. , Christie C.R. , Julien R.H.
Published: August 2010

The regulation of electrolyte inventory in a zinc leaching plant is a challenging process control problem. This paper presents a simple plant‐wide control strategy to maintain level in the Electrolytic and Meeting (E&M) feed tank at the operator‐specified upper limit. Electrolyte production is thereby maximized while ensuring that the outlet temperature of the Hot Stage Purification heat exchanger remains greater than its lower limit, and that levels in the other vessels are kept in their desired ranges. The basic principle underlying this approach is to set throughput at a value which will consume spare capacity in the E&M tank over the next M hours of operation. To tune to strategy, the user must choose the prediction horizon M, as well as maximum allowable rate‐of‐change in plant throughput at a value which will consume spare capacity in the E&M tank over the next M hours of operation. To tune the strategy, the user must in choose the prediction horizon M, as well as a maximum allowable rate‐of‐change in plant throughput. The algorithm is easily programmed using standard DCS functions and does not require the purchase of third‐party optimization software. Simulation results are included which demonstrate that proposed method provides high‐performance control of electrolyte inventory in response to typical plant disturbances, such as reduction in steam header pressure and step changes in E&M feedrate.
A Variable Structure Control Scheme Based on Combined Switching Surfaces for Discrete‐Time Systems
Authors: Zhang Yi‐Bo , Pi Dao‐Ying , Sun You‐Xian
Published: August 2010

A scheme based on combined switching surface is introduced. Based on the characters of shifting switching surface (SSS) and conventional switching surface (CSS), a modified exponent reaching law is adopted. The state of system is designed initially staying at the SSS, and then moving to the stable point. As soon as the state moves into the converge range of the CSS, the parameters of the CSS will be determined by the state, and the state will turn to stay at the CSS and move to zero state. By using the scheme of combined switching surfaces, the state always stays on the switching surfaces, and so robustness of systems is guaranteed. Moreover, this scheme could be used in high‐order systems. Simulation results show that the scheme is effective.
A Robust Control Real‐Time Scheduling Design
Authors: Du Bing , Levy David C.
Published: August 2010

Today's real‐time systems need to be operated under tighter performance specifications, and require more and more constraints to be satisfied. These specifications can only be met when system nonlinearities and constraints are explicitly considered. The paper presents a new H∞‐nonlinear model predictive control scheduling method to regulate the deadline miss ratio and CPU utilization, and to satisfy the performance specifications. It is difficult to accurately model a real‐time multimedia system. H∞ control theory addresses the issue of worst‐case controller design for linear plants subjects to unknown additive disturbances and plant uncertainties. Model predictive methodology is extended to H∞ controllers for nonlinear systems. A scheduling architecture that includes model uncertainty is proposed. We firstly integrate H∞ robust optimal control and scheduling theory in order to satisfy trade‐offs between control performance and computing resource utilization. Performance evaluation results are demonstrated by simulated examples, and earliest‐deadline first (EDF) scheduling results are compared.
The Effects of Solid Sorbents on Heavy Metal Emission under Various Combustion
Authors: Han J. , Xu M.H. , Zeng H. , Zhang Z. , Yi F.
Published: August 2010

Experimental studies on heavy metals captured by solid sorbents were carried out in a downflow reactor. The effects of various sorbents on heavy metal emissions under different combustion conditions were investigated. The operating parameters evaluated included: (1) different ratios of sorbent/coal (2%, 4% and 6%); (2) elevated temperatures (950 d̀C, 1100d̀C and 1250d̀C); (3) un‐staged and staged combustion. The experimental results indicated that the best metal capture efficiency occurs when the ratio of bauxite/coal is 2%, and 4% for both limestone/coal and calcium sulfate/coal systems. It was found that increasing temperature has a negative effect on heavy metal capture by sorbents. The experimental results also showed that the staged combustion has no effect on heavy metal removal, although it is effective in the control of NOx emissions. The leaching tests indicated that the mechanisms of heavy metal capture by solid sorbents include both physical adsorption and chemical reaction.