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PubMed2004

Dynamical optimal training for interval type-2 fuzzy neural network (T2FNN).

Type-2 fuzzy logic system (FLS) cascaded with neural network, type-2 fuzzy neural network (T2FNN), is presented in this paper to handle uncertainty with dynamical optimal learning. A T2FNN consists of a type-2 fuzzy linguistic process as the antecedent part, and the two-layer interval neural network as the consequent part. A general T2FNN is computational-intensive due to the complexity of type 2 to type 1 reduction. Therefore, the interval T2FNN is adopted in this paper to simplify the computational process. The dynamical optimal training algorithm for the two-layer consequent part of interval T2FNN is first developed. The stable and optimal left and right learning rates for the interval neural network, in the sense of maximum error reduction, can be derived for each iteration in the training process (back propagation). It can also be shown both learning rates cannot be both negative. Further, due to variation of the initial MF parameters, i.e., the spread level of uncertain means or deviations of interval Gaussian MFs, the performance of back propagation training process may be affected. To achieve better total performance, a genetic algorithm (GA) is designed to search optimal spread rate for uncertain means and optimal learning for the antecedent part. Several examples are fully illustrated. Excellent results are obtained for the truck backing-up control and the identification of nonlinear system, which yield more improved performance than those using type-1 FNN.

Algorithms↗

PubMed2006

Statistical medium formulation and process modeling by mixture design of experiment for peptide overexpression in recombinant Escherichia coli.

The medium formulation and robust process modeling for anti-HIV peptide (T-20) production by recombinant Escherichia coli overexpression were studied by employing a crossed experimental design. The crossed design, a mixture design combined with process factor (induction duration), was used to find the optimal medium formulation and process time. The optimal settings for three major components (7.75 mL of NPK sources, 5.5 mL of glucose, and 11.75 mL of MgSO4) characterized by %T-20 (14.45%), the proportion of peptide to the total protein, were observed in a total of 100 mL of medium inducted at an optical density of 0.67 with 0.7 mM isopropyl-beta-D-thiogalactopyranoside) for a 3-h induction duration at shake-flask scale. These conditions were further investigated to find robust process conditions (8.2 mL of NPK sources, 5.6 mL of glucose, and 11.3 mL of MgSO4, and a 3.5-h induction duration time) for T-20 production (13.9%) by applying propagation of error.

Anti-HIV Agents↗

PubMed2007

Structure-property relationships in the optimization of polysilicon thin films for electrical recording/stimulation of single neurons.

We had earlier demonstrated the use of polysilicon microelectrodes for recording electrical activity from single neurons in vivo. Good machinability and compatibility with CMOS processing further make polysilicon an attractive interface material between biological environments on one hand and MEMS technology and digital circuits on the other hand. In this study, we focus on optimizing the polysilicon thin films for (a) electrical recording and (b) stimulation of single neurons by minimizing its electrochemical impedance spectra and maximizing its charge storage/injection capacity respectively. The structure-property relationships in ion-implanted (phosphorus) LPCVD polysilicon thin films under different annealing and doping conditions were carefully assessed during this optimization process. A 2D model of the polysilicon thin film consisting of 4 grains and 3 grain boundaries was constructed and the effect of grain size and grain boundaries on dc resistivity was simulated using device simulator ATLAS. Optimal processing conditions and doping concentrations resulted in a 10-fold decrease in electrochemical impedance from 1.1 kOmega to 0.1 kOmega at 1 kHz (area of polysilicon interface = 4.8 mm(2)). Subsequent characterizations showed that evolution of secondary grains within the polysilicon thin films at optimal doping and annealing conditions (10(21)/cm(3) of phosphorus and annealed at 1200 degrees C) was responsible for decreasing the impedance. Cyclic voltammetry studies demonstrated that charge storage properties of low doped (10(15)/cm(3)) thin films was 111.4 microC/cm(2) in phosphate buffered saline which compares well with platinum wires (approximately 50 microC/cm(2)) and the double-layered capacitance (C(dl)) could be sustained between -1 to 1 V before breakdown and hydrolysis. We conclude that polysilicon can be optimized for recording and stimulating single neurons and can be a valuable interface material between neurons and CMOS or MEMS devices.

Action Potentials↗

PubMed1990

Adult age comparisons in the processing of event frequency information.

The usual superiority in frequency-of-occurrence judgments of younger vs. older subjects was hypothesized to result from greater strategic encoding of the materials conveying frequency information. A subject-paced, visual search task was designed to control nontarget word encoding. Relative frequency judgments for the nontarget word pairs were equally accurate for younger and older subjects, and performance of both groups was above chance. Results suggest that strategic cover-task encoding can induce age differences in incidental frequency processing. Consistent with a nonoptimal as opposed to an optimal view, automatic processes require only minimal capacity for above-chance performance, but additional strategic resources can increase performance. When such additional resources are used more by younger than by older subjects, the former are better in frequency performance.

Adult↗

PubMed2002

Hardware and software platform for real-time processing and visualization of echographic radiofrequency signals.

In this paper the architecture of a hardware and software platform, for ultrasonic investigation is presented. The platform, used in conjunction with an analog front-end hardware for driving the ultrasonic transducers of any commercial echograph, having the radiofrequency echo signal access, make it possible to dispose of a powerful echographic system for experimenting any processing technique, also in a clinical environment in which real-time operation mode is an essential prerequisite. The platform transforms any echograph into a test-system for evaluating the diagnostic effectiveness of new investigation techniques. A particular user interface was designed in order to allow a real-time and simultaneous visualization of the results produced in the different stages of the chosen processing procedure. This is aimed at obtaining a better optimization of the processing algorithm. The most important platform aspect, which also constitutes the basic differentiation with respect to similar systems, is the direct processing of the radiofrequency echo signal, which is essential for a complete analysis of the particular ultrasound-media interaction phenomenon. The platform completely integrates the architecture of a personal computer (PC) giving rise to several benefits, such as the quick technological evolution in the PC field and an extreme degree of programmability for different applications. The PC also constitutes the user interface, as a flexible and intuitive visualization support, and performs some software signal processing, by custom algorithms and commercial libraries. The realized close synergy between hardware and software allows the acquisition and real-time processing of the echographic radiofrequency (RF) signal with fast data representation.

Computer Graphics↗

PubMed2004

[Study on the extraction process of polysaccharide from Lycium barbarum].

OBJECTIVE: To choose the optimum extration process of polysaccharide from Lycium barbarum L. METHODS: The optimal water extration process is selected with the orthogonal design. The yield and the content of polysaccharide were used to evaluate the factor levels. RESULTS: The ideal extraction process is: the polysaccharide is extracted with water for 3 times,with solvent volume 8 times amount each time (10 times amount for the first time), extraction time 1 h each time and stired 10 min each hour. CONCLUSION: The experimental results provide the basis for the water extration process of polysaccharide from Lycium barbarum L.

Analysis of Variance↗

PubMed2006

[Plant scale test of a new efficient poly-aluminum chloride].

To meet the requirement of improved water quality, the economic water treatment process could be achieved by systematic coagulant selection and optimization of coagulation process. The experimental results show that the new coagulant developed has significantly improved the water quality, with marked modification of the particle size distribution feature after sediment and improved filtration efficiency. The organic removal ability, as shown by low TOC and UV254 in the finished water, is also significantly improved and also verified by using resin absorption characterization method. The TTHMFP for the source water is 20.98 microg/L and 11.01 microg/L for the traditional process. By using the new coagulant the TTHMFP is further decreased to 6.40 microg/L. With application of the new coagulant, the treatment costs are significantly decreased with further improved and simplified treatment process.

Aluminum Chloride↗

PubMed2003

Egocentrism, event frequency, and comparative optimism: when what happens frequently is "more likely to happen to me".

Three studies investigated the role of nonmotivated egocentric processes in comparative optimism (and pessimism). According to an egocentric-processes account, when people judge their comparative likelihood of experiencing an event (e.g., "Compared to the average person, how likely are you to become wealthy?"), they consider their own chances of experiencing the event more so than the referent's chances. This should produce higher comparative estimates when an event's absolute frequency is high rather than low-a prediction supported in Study 1, which manipulated event frequency through a novel, time frame manipulation. Study 2 empirically distinguished egocentrism from a related focalism account. In Study 3, comparative estimates were related to the perceived frequency of events, independent of the events' perceived desirability and controllability. Path analyses provided additional support for egocentrism, and systematic cases of comparative pessimism were observed as predicted by the egocentric-processes account.

Ego↗

PubMed2003

Monitoring indirect presentation of alloantigens by utilizing the autologous processing machinery of dendritic cells in-vitro.

BACKGROUND: Judicious individualization of immunosuppression protocols requires the ability to monitor the recipients' specific immune response towards the allograft. While several indirect presentation studies have been reported, currently there are no consistently reliable means to assess the state of transplant acceptance. A potential explanation might be the lack of established kinetics for in-vitro indirect presentation assays. METHODS: Dendritic cell (DCs) were used as self-specific "processing machinery" for the generation of allogeneic peptide repertoire tailored by the individual's capacity to process antigens via the indirect pathway. The kinetics of antigen processing and presentation of newly acquired antigens was then assessed to define the following: (1) Optimal time to introduce apoptotic-allogeneic cells to DCs; (2) optimal time for processing before induction of DC maturation; and (3) optimal time for stimulation of autologous T cells by the pulsed DCs. RESULTS: Altering kinetic parameters associated with time allotted for antigen processing; antigen presentation and DCs maturation, showed substantial variations in the level of T cell activation, as was documented by mixed lymphocyte reaction (MLR)-like proliferation assays. Further experiments using allogeneic cellular extracts showed similar variations in T cell stimulation by monitoring T cell precursor frequencies and interferon (IFN)-gamma secretion ELISPOT assays. Using the appropriate kinetic parameters, we have also shown difference in T-cell-subsets (CD4, CD8) precursor frequencies and cytokine secretion in response to different antigenic sources. CONCLUSIONS: The ability to construct an in-vitro, recipient-tailored, donor-specific, indirect presentation assay is dependent on essential kinetic parameters associated with antigen processing and presentation, as described in this report. Moreover, the use of this approach may circumvent the need for identifying specific immunogenic peptides for cancer-related or other vaccine-development studies.

Antigen Presentation↗

PubMedDate not supplied

Proper orthogonal decomposition based optimal neurocontrol synthesis of a chemical reactor process using approximate dynamic programming.

The concept of approximate dynamic programming and adaptive critic neural network based optimal controller is extended in this study to include systems governed by partial differential equations. An optimal controller is synthesized for a dispersion type tubular chemical reactor, which is governed by two coupled nonlinear partial differential equations. It consists of three steps: First, empirical basis functions are designed using the 'Proper Orthogonal Decomposition' technique and a low-order lumped parameter system to represent the infinite-dimensional system is obtained by carrying out a Galerkin projection. Second, approximate dynamic programming technique is applied in a discrete time framework, followed by the use of a dual neural network structure called adaptive critics, to obtain optimal neurocontrollers for this system. In this structure, one set of neural networks captures the relationship between the state variables and the control, whereas the other set captures the relationship between the state and the costate variables. Third, the lumped parameter control is then mapped back to the spatial dimension using the same basis functions to result in a feedback control. Numerical results are presented that illustrate the potential of this approach. It should be noted that the procedure presented in this study can be used in synthesizing optimal controllers for a fairly general class of nonlinear distributed parameter systems.

Models, Chemical↗

PubMed2005

Retention process in reversed phase TLC systems with polar bonded stationary phases.

The retention of a solute in RP chromatography is a very complex process which depends on many factors. Therefore, the study of the influence of a mobile phase modifier concentration on the retention in different reversed phase chromatographic systems is very important for understanding the rules governing retention and mechanisms of substance separation in a chromatographic process. Composition changes and the nature of mobile phases enable tuning of the separated analytes' retention over a wide range of retention parameters and optimization of the chromatographic process as well. Optimization of the chromatographic process can be achieved by several different methods; one of them is the so-called interpretative strategy. The key approach adopted in this strategy is the implementation of adequate retention models that couple the retention of solute with the composition of a mixed mobile phase. The use of chemically bonded stationary phases composed of partially non-bonded silica matrix and organic ligands bonded to its surface in everyday chromatography practice leads to questions of the correct definition of the retention model and the dominant retention mechanism in such chromatographic systems. The retention model for an accurate prediction of retention factor as a function of modifier concentration and the heterogeneity of the adsorbent surface should be taken into consideration. In this work the influence of mobile-phase composition on the retention of sixteen model substances such as phenols, quinolines, and anilines used as test analytes in different RP-TLC systems with CN-, NH2-, and Diol-silica polar bonded stationary phases has been studied. The aim of this study is to compare the performance of three valuable retention models assumed as the partition, adsorption/partition, and adsorption mechanism of retention. All the models were verified for different RP-TLC systems by three statistical criteria. The results of investigations presented in this work demonstrate that the best agreement between the experimental and calculated Rf values was obtained by the use of new-generation retention models, which assume heterogeneity of adsorbent surface. The results reported here show that heterogeneity of the adsorbent surface may be important in analysis of the elution process in liquid chromatography. Consideration of the goodness of fit for the experimental data to the examined retention models is in conformity with the adsorption mechanism of retention on all polar bonded stationary phases in most eluent systems for most investigated compounds.

Journal Article↗

PubMed2005

Adaptive dynamic range optimization (ADRO): a digital amplification strategy for hearing aids and cochlear implants.

Adaptive dynamic range optimization (ADRO) is an amplification strategy that uses digital signal processing techniques to improve the audibility, comfort, and intelligibility of sounds for people who use cochlear implants and/or hearing aids. The strategy uses statistical analysis to select the most information-rich section of the input dynamic range in multiple-frequency channels. Fuzzy logic rules control the gain in each frequency channel so that the selected section of the dynamic range is presented at an audible and comfortable level. The ADRO processing thus adaptively optimizes the dynamic range of the signal in multiple-frequency channels. Clinical studies show that ADRO can be fitted easily to all degrees of hearing loss for hearing aids and cochlear implants in a direct and intuitive manner, taking the preferences of the listener into account. The result is high acceptance by new and experienced hearing aid users and strong preferences for ADRO compared with alternative amplification strategies. The ADRO processing is particularly well suited to bimodal and hybrid stimulation which combine electric and acoustic stimulation in opposite ears or in the same ear, respectively.

Algorithms↗

PubMed2005

[Experiment study on real-time controlling rules of A/O nitrogen removal process].

The aim of this work is operational optimization of an A/O process in the lab plant with synthetic wastewater for improving nitrogen removal efficiency. Ammonia control aims at maintaining the required concentration of ammonia in the effluent by manipulating the dissolved oxygen (DO) set point and aeration volumes. Nitrate control aims at the optimal use of the denitrification potential at any moment by continuously adjusting the internal recirculation flow or (and) external carbon addition flow in order to maintain a desired nitrate set point in the anoxic zone. The control strategies have been based on a hierarchical structure where a high level or supervisory control selects the set point of the low level or conventional controllers. Results indicated that it was possible to increase nitrogen removal efficiency, improve the effluent water quality, save energy, and reduce operating costs.

Ammonia↗

PubMed1994

The optimization of technological condition in the fermentation process of glutamate by pattern recognition method.

The technological condition in the fermentation process of fermentation glutamate (such as pH value, temperature, ventilation rate, etc.) were optimized by computerized pattern recognition method. The visible optimum region may be found based on the mapping from the multi-dimensional pattern space into a plane. It is then transformed along the reciprocal direction into the original data space using Monte Carlo simulation, so the orientation of optimization and the best combination of all parameters can be determined. A new mathematical model is being proposed based on the experimental evidence in production. The transfer ratio of glucose to glutamic acid, the production capacity and the glutamic acid concentration increase 2.9%, 1.45% and 2.65% respectively by operating this optimization method. The method has been widely extended to factories and has granted in decreasing the expense of raw materials and that of the production cost.

Fermentation↗

PubMedDate not supplied

Helical processing using PHOELIX.

We describe here a set of procedures and algorithms for helical processing that we refer to as the PHOELIX package. The package was developed to provide a time-efficient and semiautomated method for determining a three-dimensional density map from a specimen with helical symmetry. The procedures which are part of PHOELIX are drawn from the original MRC helical processing suite with extensions principally developed using the SUPRIM image processing package. The package in its current form has been optimized for the processing of actomyosin filaments but has been modified and applied to other helical structures.

Actomyosin↗

PubMed2002

Cooperation and competition in mismatch repair: very short-patch repair and methyl-directed mismatch repair in Escherichia coli.

In Escherichia coli and related enteric bacteria, repair of base-base mismatches is performed by two overlapping biochemical processes, methyl-directed mismatch repair (MMR) and very short-patch (VSP) repair. While MMR repairs replication errors, VSP repair corrects to C*G mispairs created by 5-methylcytosine deamination to T. The efficiency of the two pathways changes during the bacterial life cycle; MMR is more efficient during exponential growth and VSP repair is more efficient during the stationary phase. VSP repair and MMR share two proteins, MutS and MutL, and although the two repair pathways are not equally dependent on these proteins, their dual use creates a competition within the cells between the repair processes. The structural and biochemical data on the endonuclease that initiates VSP repair, Vsr, suggest that this protein plays a role similar to MutH (also an endonuclease) in MMR. Biochemical and genetic studies of the two repair pathways have helped eliminate certain models for MMR and put restrictions on models that can be developed regarding either repair process. We review here recent information about the biochemistry of both repair processes and describe the balancing act performed by cells to optimize the competing processes during different phases of the bacterial life cycle.

Adenine↗

PubMed2005

Microencapsulation of higher hydrocarbon phase change materials by in situ polymerization.

Three higher hydrocarbon phase change materials (PCMs) with melting points of 25, 40 and 50 degrees C were microencapsulated by in situ polymerization of amino-aldehyde resins. Trimethylolmelamine (TMM) and hexamethoxymethylolmelamine (HMMM) were studied as amino-aldehyde pre-polymers for microcapsule wall formation, in combination with emulsifying/modifying agents based on styrene-malein anhydride copolymers (SMA) of different molecular weights and different styrene-maleic acid anhydride ratios. Microcapsule sizes, size distribution and wall permeability were analysed. A mathematical model was developed for comparing the mechanical resistance of different batches of microcapsules, produced at different TMM-SMA ratios. Larger microcapsules with thicker walls and larger pores (M(LAR)) expressed lower resistance to breakage than slightly smaller microcapsules with thinner walls and finer pore structure (M(SMA)). Mathematical data were confirmed by a smudging colouration test. Laboratory microencapsulation process parameters were optimized to obtain impermeable microcapsules with improved mechanical stability. The process was transferred into a 10l pilot reactor for two PCMs with melting points of 25 and 40 degrees C. Dry powder of microencapsulated PCMs was obtained by spray drying of aqueous microcapsule suspensions.

Drug Compounding↗

PubMed2006

Radiation processing to ensure safety of minimally processed carrot (Daucus carota) and cucumber (Cucumis sativus): optimization of dose for the elimination of Salmonella Typhimurium and Listeria monocytogenes.

Minimally processed vegetables are in demand, because they offer convenience to consumers. However, these products are often unsafe because of possible contamination with pathogens, such as Salmonella, Escherichia coli O157:H7, and Shigella species. Therefore, this study was carried out to optimize the radiation dose necessary to ensure the safety of precut carrot and cucumber. Decimal reduction doses (D-values) of Salmonella Typhimurium MTCC 98 were ca. 0.164 kGy in carrot samples and 0.178 kGy in cucumber samples. D-values of Listeria monocytogenes were determined to be 0.312 and 0.345 kGy in carrot and cucumber samples, respectively. Studies of inoculated, packaged, minimally processed carrot and cucumber samples showed that treatment with a 1-kGy dose of gamma radiation eliminated up to 4 log CFU/g of Salmonella Typhimurium and 3 log CFU/g of L. monocytogenes. However, treatment with a 2-kGy dose was necessary to eliminate these pathogens by 5 log CFU/g. Storage studies showed that both Salmonella Typhimurium and L. monocytogenes were able to grow at 10 degrees C in inoculated control samples. Neither of these pathogens could be recovered from radiation-processed samples after storage for up to 8 days.

Colony Count, Microbial↗