Showing papers by "Xiao Dong Chen published in 2000"
TL;DR: In this paper, the internal oil and moisture contents for flat-cut and ridge-cut potato crisps of thickness 2 mm were fried at temperatures of 170, 180, 180 and 190°C and the internal contents for frying times of 10, 20, 30, 60, 90, 120 and 180 s were determined.
55 citations
TL;DR: In this article, a liquid-membrane-extraction process is investigated for the recovery of lithium metal from these natural resources, and different carriers and combinations of carriers were tried for lithium selectivity.
Abstract: Increasing demand for lithium metal is expected to rise above the current production levels. Most lithium production is currently from mining and recovery of pegmatite ores. Recent research has emphasized recovery from brine sources such as geothermal water and seawater. A novel liquid-membrane-extraction process is investigated here for the recovery of lithium metal from these natural resources. Different carriers and combinations of carriers were tried for lithium selectivity. A carrier combination of LIX54 (main component is α-acetyl-m-dodecylacetophenone) and TOPO (tri-octyl phosphine oxide) had a synergistic effect for lithium extraction and was found to be most effective. This combination was used to extract lithium in a supported liquid membrane (SLM) process. Variables considered were pH, carrier concentrations, initial lithium concentration, type of organic solvent and stripping phase, and presence of sodium and potassium ions in the feed and flow rates of both aqueous phases. The optimal extract...
48 citations
TL;DR: In this paper, the deposition of calcium sulphate in two different plate heat exchanger geometries was investigated, and the deposition process was deliberately focused on crystallisation fouling through the installation of an in-line filter and the mode of preparation of the test solution.
Abstract: The uncertainty about the fouling behaviour is one of the main reasons why plate and frame heat exchangers are not more widely installed in the chemical process industry and in power generating facilities. In the present investigation, the deposition of calcium sulphate in two different plate heat exchanger geometries was investigated. The deposition process was deliberately focused on crystallisation fouling through the installation of an in-line filter and the mode of preparation of the test solution. The investigated operating parameters were solution concentration, flow velocity, and bulk and surface temperatures. The heat exchangers were opened after each experiment to record the appearance and distribution of the deposits. The key result of this investigation is the strong correlation between the plate design and the tendency for deposit formation.
42 citations
TL;DR: In this article, the effects of ice growth rate, solution velocity and bulk concentration of solute on the solute inclusion in the ice layer have been investigated using a controlled flow surface crystallizer (CFSC).
Abstract: Solute inclusion in an ice layer formed on a smooth stainless steel surface under sub-cooled flow conditions has been studied experimentally. The effects of ice growth rate, solution velocity and bulk concentration of solute on the solute inclusion in the ice layer have been investigated using a controlled flow surface crystallizer (CFSC). For several aqueous solutions (sucrose, NaCI, glycol, fructose), food liquids (skim milk, whole milk, orange juice) and particulate suspension (potato starch particles), the effective molecular weights were calculated and their effects on solid inclusion determined. This effect was then conveniently related to the freezing point depression (FPD) of each liquid tested. A generalized empirical correlation has been established for all the liquids tested.
On a etudie de maniere experimentale l'inclusion de solute dans une couche de glace formee sur une surface d'acier lnoxydable lisse dans des conditions d'ecoulement sous-refroidies. Les effets de la vitesse de croissance de la glace, de la vitesse de la solution et de la concentration en masse du solute sur l'introduc-tion de solute dans la couche de glace ont ete etudies a l'aide d'un cristallisoir a surface d'ecoulement controle (CFSC). Pour plusieurs solutions aqueuses (sucrose, NaCI, glycol, fructose), liquides alimentaires (lait ecrerne, lait entier, jus d'orange) et une suspension de particules (particules d'amidon de pomme de terre), on a calcule les poids moleculaires effectifs et determine leurs effets sur l'introduction de solides. Cet effet est par la suite facilement relie a la depression du point de congelation (FPD) de chaque liquide teste Une correlation empirique generalisee a ete etablie pour tous les liquides testes.
30 citations
TL;DR: In this paper, a simple moving boundary model was designed to describe the immersion frying of a thin cut potato crisp of thickness 2 mm, and good agreement was found between the experimental and predicted values, which were generally within the t99(0.01) confidence interval of the experimental data.
Abstract: A simple moving boundary model was redesigned to describe the immersion frying of a thin cut potato crisp of thickness 2 mm. The model took into account the effects of a variable oil convection heat transfer coefficient. In the model, the centre temperature was defined as a value of a region rather than a point. The model also predicted the effect of some shift in the location of the thermocouple on the measurements. Experiments at oil temperatures of 170, 180 and 190 °C were conducted to verify whether or not the model predictions were accurate. Good agreement was found between the experimental and predicted values, which were generally within the t99(0.01) confidence interval of the experimental data.
19 citations
TL;DR: In this paper, an extremum seeking adaptive control has been used to maximise the productivity of a fermentation process, which does not require any structural information of the modeling uncertainty and can be used to steer the process to yield a maximum productivity.
Abstract: This paper examines the problem of maximising the productivity of a class of fermentation processes described by an unstructured fermentation process model. For a given dilution rate, an extremum seeking adaptive control has been used to maximise the productivity of a fermentation process. The concept behinds the extremum seeking method is to iteratively adjust the feed substrate rate in order to steer the process to yield a maximum productivity. The main advantage of the extremum seeking adaptive control is it does not require any structural information of the modeling uncertainty.
12 citations
TL;DR: In this paper, the physical background concerning the existence of four dynamical states (stable, oscillatory, chaotic and unstable) in a plasma-filled diode has been investigated in some detail, the results being presented with the help of charge density and other three-dimensional graphs.
Abstract: The physical background concerning the existence of four dynamical states (stable, oscillatory, chaotic and unstable) in a plasma-filled diode has been investigated in some detail, the results being presented with the help of charge density and other three-dimensional graphs. It has been established that the determining factor is a dynamic ions/electrons charge-balance in the interelectrode space.
11 citations
TL;DR: In this article, a plasma-filled diode was used as a model for the interaction space in a virtual cathode oscillator (VCO) (vircator), and it was shown that depending on the separation of the electrodes, the initial ion/electron ratio /spl alpha/spl circ/, and the load Z/spl sub-circ/sub l/subl/, the system may exhibit a cascade of bifurcations leading to chaos.
Abstract: A plasma-filled diode can be used as a model for the interaction space in a virtual cathode oscillator (VCO) (vircator). It is shown that depending on the separation of the electrodes x/spl circ//sub L/, the initial ion/electron ratio /spl alpha//spl circ/, and the load Z/spl circ//sub l/, the system may exhibit a cascade of bifurcations leading to chaos. The positioning and extent of chaos can be controlled by a judicious choice of the above parameters. It is also shown that for a range of values of x/spl circ//sub L/,/spl alpha//spl circ/, and Z/spl circ//sub l/ the system is capable of generating oscillations of a well-defined frequency. For other ranges, it reaches a stable state or becomes unstable.
10 citations
6 citations
TL;DR: In this paper, a model for the heterogeneously catalysed reaction of a gaseous species undergoing a single-step exothermic reaction in a well mixed diabatic continuously stirred tank reactor is developed and analyzed.
Abstract: In this paper a model for the heterogeneously catalysed reaction of a gaseous species undergoing a single-step exothermic reaction in a well mixed diabatic continuously stirred tank reactor is developed and analysed. Low-temperature reaction conditions are assumed, so that the degradation of the inflow species in the gas phase is negligible. The adsorption and desorption of the active species onto a solid catalyst layer is explicitly modelled.Under the conditions used, the classic combustion S-shape steady-state curve is not exhibited. Instead the steady-state diagram consists of two disjoint solution curves: a solution curve containing a steady-state branch corresponding to full coverage of the catalyst with no conversion; and, an isola containing a steady-state branch that corresponds to low coverage of the catalyst with a high conversion of the inflow species. The steady-state curve contains one extinction point and no ignition points. Consequently the initial conditions determine onto which steady sta...
5 citations
Journal Article•
TL;DR: The factors affecting Bacillus stearothermophilus WF146 for thermophilic protease producing have been investigated and the enzyme exhibited high temperature tolerance and was stable at a wide range of pH, and Ca2+ played a key role for the stability of the enzyme.
Abstract: The factors affecting Bacillus stearothermophilus WF146 for thermophilic protease producing have been investigated, more than 600 units of enzyme in 1 mL of fermented culture could be achieved under suitable condition. The protease had a molecular weight around 34 kD estimated by SDS-PAGE, and functioned optimally at pH 8.0 and 80 degrees C, respectively. In addition, the enzyme exhibited high temperature tolerance and was stable at a wide range of pH, and Ca2+ played a key role for the stability of the enzyme. While the protease activity of the enzyme was strongly inhibited by PMSF, DFP and IAA, and was not affected by DTT.
01 Jan 2000
TL;DR: In this paper, the survival of three different strains of bacteria during milk droplet drying was investigated with and without the inclusion of bacterial cultures, which are 'imbedded' in the sample milk particles produced.
Abstract: This paper reports experimental results on the survival of three different strains of bacteria during milk droplet drying. By using the Single Droplet Dryer (SD{2}) the behaviour of milk product dehydration was investigated with and without the inclusion of bacterial cultures, which are 'imbedded' in the sample milk particles produced. This provides a means of obtaining the bacterial deactivation kinetics under situations that are close to practical drying conditions. In these tests, both whole milk and skim milk were used as the bacterial encapsulation materials. The three strains tested for the SD 2 trials were Bifidobacterium infantis, Lactobacillus acidophilus and Streptococcus thermophilus. The trends of these strains' resistances to heat were established for three different temperatures: 70 C, 90 C and 110 C. It can be shown from these results that the strains could survive within the milk droplets in the specified drying conditions. From the survival numbers obtained along with the known tested parameters, i.e. droplet water content and droplet temperature, death kinetics may be modelled based on reaction engineering principles. Using the (temperature and moisture content dependent) kinetics together with the drying model, scale up simulations can be carried out in the near future.
Journal Article•
TL;DR: Craniovertebral decompression and posterior fossa reconstruction in restoring the cranioverTEbral junction are recommended in the treatment of Chiari malformation/syringomyelia.
Abstract: Objective[WT5”BZ] To study the results of Chiari malformation/syringomyelia(CM SM)complex treated by craniovertebral decompression and posterior fossa reconstruction(PFR). [WT5”HZ]Methods[WT5”BZ] 37 patients of CM SM complex were treated surgically from 1994 to 1999.All patients underwent craniovertebral decompression and posterior fossa reconstruction. The procedure consisted of suboccipital craniectomy and laminectomy of C1 (when necessary C2),exploration and plugging of the obex, and resection of arachnoid adherence. A wide dural graft was used to reconstruct the cisterna magna artificially. Syrinx shunt was not performed. [WT5”HZ]Results[WT5”BZ] Follow up for 0 5 to 4 5 years showed that 31 patients(83 8%) had their symptoms improved, 5 (13 5%) stabilized, but 1(2 7%) deteriorated. Magnetic resonance was ased to evaluate the morphological results. The shrinkage of the syrinx, upward migration of the hindbrain, the formation of an artificial cisterna magna were observed. [WT5”HZ]Conclusions[WT5”BZ] Craniovertebral decompression and posterior fossa reconstruction in restoring the craniovertebral junction are recommended in the treatment of CM SM complex. [WT5”HZ]
01 Jan 2000
TL;DR: In this paper, the authors used the computational fluid dynamics (CFD) code PHOENICS, which is based on finite volume method, to analyze the temperature and bacteria concentration in a three-dimensional pouch filled with viscous liquid food (Broccoli and Cheddar soup) during thermal sterilization.
Abstract: Profiles of temperature and bacteria concentration in a three-dimensional pouch filled with viscous liquid food (Broccoli and Cheddar soup) during thermal sterilization are presented and studied. In this study, the computational fluid dynamics (CFD) code PHOENICS is used, which is based on finite volume method. The governing equations of continuity, momentum and energy are solved together with the bacteria concentration equation. Arrhenius equation is used to describe the kinetics of the bacteria concentration changes. Natural convection that occurs during thermal sterilization of viscous liquid soup in a pouch heated from all sides is simulated. Saturated steam at 121 C is used as the heating medium. The computed results show different temperature profiles during the sterilization process, which highlight the migration of the slowest heating zone (SHZ), and also show the dependency of concentration of live bacteria on the temperature distribution.
TL;DR: In this paper, an insoluble solid particle, i.e., a potato starch used as an example, was employed to investigate the impact of the concentration of such particles suspended in water (with solid loading of 5, 10, 20 and 30 wt%) upon the solid inclusion levels in ice layers formed on a sub-cooled smooth stainless steel plate surface.
Abstract: This study employed an insoluble solid particle, i.e. a potato starch used as an example, to investigate the impact of the concentration of such particles suspended in water (with solid loading of 5, 10, 20 and 30 wt%) upon the solid inclusion levels in ice layers formed on a sub-cooled smooth stainless steel plate surface. The effects of ice growth rate, bulk concentration and suspension velocity on insoluble solid inclusion, i.e. potato starch mass fraction, in ice layer were studied. The experiments, where potato starch is added into aqueous sucrose solutions or the reverse where sucrose is added into starch suspension, were also carried out to investigated effect of the starch particles on sucrose inclusion in ice and effect of solute (sucrose) on starch particle inclusion in ice. It has been found that solid inclusion in ice increases with increasing bulk concentration and average ice growth rate, at constant solution and coolant velocities, and increasing suspension velocity can help pure ice formation. The average distribution coefficient of sucrose in ice layer formed from sucrose solution does not appear to be affected by the addition of potato starch. However, the average distribution coefficient of potato starch in ice layer formed from suspension is influenced by sucrose concentration quite significantly.
01 Jan 2000
TL;DR: In this article, it was found that definite oil uptake, moisture loss trends exist during the frying process, and an increased oil temperature promoted higher moisture loss rates, which contributed to a higher oil uptake rate.
Abstract: Thin potato crisps (2mm) were fried at 170 C, 180 C and 190 C for various times from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends exist during the frying process. No significant difference in the oil uptake or moisture loss rates between flat-cut and ridge-cut crisps exists. Also found in this study was that an increased oil temperature promoted higher moisture loss rates. In turn, the higher moisture loss rates contributed to a higher oil uptake rate. It was found, based on the volumetric plots of oil content vs. water content, that the oil uptake rate was proportional to the moisture loss rate. As a result, it has been shown that there is a possibility of having a characteristic curve of oil uptake against moisture content.
04 Jun 2000
TL;DR: The MAGIC3D as mentioned in this paper code has been used for the characterisation of resonance modes on an X-band magnetron by using a well-developed 3D code called MAGIC.
Abstract: Summary form only given. The characterisation of resonance modes is one of the important procedures in the 'cold test' of a magnetron. This procedure has been modelled on an X-band magnetron by using a well-developed 3-D code called MAGIC3D. The relevant magnetron anode block comprises twenty-two slots with straps connecting alternative vanes at both ends, an axial output conductor coupled to the anode with eleven legs connected to alternative vanes; the cathode in the form of an inner cylinder is terminated at one end by a gap followed by a choke disc attached to the output conductor. The use of a fast Fourier transform (FFT) technique combined with the time-domain technique employed by the MAGIC3D code has proved to be more effective in obtaining the spectrum of resonance modes than the conventional eigen-mode searching technique.
12 Sep 2000
TL;DR: In this paper, it is found that microwave oscillators, being highly nonlinear and rather complex, are prone to chaos, and they have in common a physical mechanism which is responsible for their nonlinear dynamical behaviours and chaos.
Abstract: Chaos is one of the more interesting recent developments in the area of nonlinear dynamics. It is found that microwave oscillators, being highly nonlinear and rather complex, are prone to chaos. In general chaotic behaviour of a dynamical system is characterised by: 1) extreme sensitivity to initial boundary conditions; 2) apparent internal randomness, viz. a messy and continuous frequency spectrum; 3) fractal dimension of its attractor; and 4) positive sign Lyapunov exponents. Having investigated, as an example, two microwave oscillators, we have found that they have in common a physical mechanism, which is responsible for their nonlinear dynamical behaviours and chaos.
03 Dec 2000
TL;DR: In this article, the authors presented a numerical characterisation of two 3 dB multi-layered CPW directional couplers, which were fabricated at King's College London and were studied with the help of a 2-dimensional finite element program.
Abstract: This paper presents a numerical characterisation of two 3 dB multi-layered CPW directional couplers, which were fabricated at King's College London. The quasi-TEM models of the couplers are studied with the help of a 2-dimensional finite element program. The characteristic impedances for both couplers obtained are in a good agreement with the values measured in the experiment.