John Y. Cheung

Design of a fuzzy controller using input and output mapping factors

A complete design procedure for a fuzzy three-term PID controller is presented. A plant model is not required to achieve this design. A reduced look-up table containing the rules along with the quantization and tuning procedures by means of input and output mapping factors are introduced. The scaling factors of the output error time sequences are preselected arbitrarily and the search for an optimal input-to-output mapping factors ratio is performed through a phase diagram analysis. the applicability of the design procedure is demonstrated through computer simulations. >

Biomarker identification in human pancreatic cancer sera

Objective: The aim of this study is to identify biomarkers in sera of pancreatic cancer patients using mass spectrometry (MS) approaches. Methods: Sera from patients diagnosed with pancreatic adenocarcinoma and sera from normal volunteers were subjected to gel electrophoresis to resolve and quantify differences in protein levels. Protein bands that differed quantitatively were digested with trypsin, and peptides were identified by electrospray ionization (ESI) ıon-trap tandem MS. Mass spectra were also collected directly from pancreatic cancer sera as well as healthy control sera using ESI-MS. Results: Three large-mass proteins were found to be elevated in pancreatic cancer sera versus normal sera, &agr;-2 macroglobulin, ceruloplasmin, and complement 3C. Complement 3C is a major regulator of inflammatory responses. The ESI-MS of human pancreatic cancer sera versus normal sera revealed greater heterogeneity in cancer sera than control sera, especially in the low-mass region. Bootstrapping statistical analysis identified 20 low-mass serum peaks that correlated with control sera and 20 different peaks that correlated with pancreatic cancer sera. Conclusions: The fact that inflammation-sensitive proteins were identified as increased in pancreatic cancer sera supports the hypothesis that inflammatory-driven processes are involved in pancreatic carcinogenesis. Liquid ESI-MS analyses of sera hold promise for future pancreatic cancer blood tests as well as for understanding mechanisms of pancreatic carcinogenesis. The variability observed between the low-mass regions of normal versus pancreatic cancer spectra may aid in diagnosis and therapy.

Quantitative Assessment of the Variation Within Grades of Facial Paralysis

A completely objective, unambiguous outcome measure of facial function is now available. A new automated computer‐assisted clinimetric system combines the crucial detection capabilities of the human observer and the unique capacity of the computer to quantify the image light reflectance difference observed during facial expression.

Hybrid genetic algorithm for container packing in three dimensions

The concept of genetics using multiple-chromosomes is applied to a 3D container packing problem. The 3D packing problem deals with packing a given set of regular shaped boxes of different sizes and weights into larger containers. The algorithm must seek to minimize the wasted space under a constraint: the heavier and the larger boxes must be placed below the lighter ones. The present emphasis is to find a good solution quickly by heuristic means. A set of heuristic rules is incorporated into the genetic algorithm (GA) approach to aid in optimization. This hybrid GA yields an optimization algorithm that outperforms either of the parts. The simulation results showed that the new algorithm has better adaptivity for large problems and near optimal solutions for small problems.<<ETX>>

Steady-state analysis of a three-term fuzzy controller

The steady-state response of a fuzzy logic controller that uses fuzzy addition as the basis for its decision making process is analyzed mathematically. The nature of the look-up table constructed from fuzzy addition enables the decomposition of the fuzzy controller into three one-dimensional-multilevel relays. Unlike the sinusoidal-input describing function technique, the steady-state response of the closed-loop system is analyzed. The sufficient conditions derived depend on the parameters of the controller and can be used as guidelines to achieve a good step response at steady-state, one that does not lend itself to sustained oscillations or limit cycles. >

Application of describing functions in the transient response analysis of a three-term fuzzy controller

The exponential-input describing function technique is used to investigate the transient response of a fuzzy controller. The rule-base of this fuzzy controller is generated by fuzzy addition and the partitioning of the universes of discourse of its input and output variables is based on an exponential mapping scheme. By using the symmetric features introduced by fuzzy addition in the decision table of the fuzzy control algorithm and the new mapping scheme, the effects of the output error time sequences can be represented by independent multilevel relays and a multiplication junction. Computer simulations on a second-order system confirm the behaviour of this analysis technique. >

Variations in Maximum Amplitude of Facial Expressions between and within Normal Subjects

Definitive proof of efficacy of preventions and therapeutic interventions, and of risk factors in lower motor neuron facial paralyses continue to be confounded by the lack of repeatable quantitative measures of outcome. Clinical and research experience with human facial expression repeatedly demonstrates wide variations between subjects. To our knowledge, little information is available to isolate and describe the differences in dynamic facial expression between and within normal subjects. The purpose of this study is to use a statistical model to analyze the components of the observed variations of maximum amplitude measurement of image change during normal human subject facial expressions. Seventeen consecutive normal adult human subjects with no current or past evidence of facial nerve or ear disease were studied. Videotapes of command facial expressions were taken using specific and standardized conditions. The tapes were analyzed using a new computer-assisted image-change analysis program capable of generating dimensional data for the maximum amplitude of expression. These data were statistically analyzed using a General Linear Model with Nested variables to isolate and define component variations and errors. The General Linear Model predicted 88% of the observed total variation (p < 0.05).* A model performance this high suggests that most of the important independent variables were being studied. The major component of the variations was the difference among (between) subjects. Seventy-seven percent of the predicted variation was due to this difference (p < 0.05). Little of the variation (1%) seemed to be within-subjects. Test-retest agreement was acceptable. Most of the data were tightly clustered about the mean and there was no stochasticly significant difference between test-retest (p = 0.1187). We are encouraged by these results. They suggest the potential value of this and other dimensional techniques applied to facial expression. This study demonstrates that a computer-assisted image-change analysis program is capable of generating dimensional data that can be statistically analyzed in order to isolate and define component variations and errors.

Polynomial and standard higher order neural network

The generalized back propagation algorithm is extended to multi-layer higher-order neural networks (HONNs). The performance of HONNs is presented. Two basic structures, the standard form and the polynomial form, are discussed. The performance of these two structures is compared using the classical TC test case, the geometric rotation problem. Simulation results show that both types of constructing strategies can recognize noisy data under rotation up to 70% and noisy irrational data up to 94%. The effect of the number of hidden neurons is discussed.<<ETX>>

Measurement of dose-area product with GafChromic XR Type R film.

Many of the newer X‐ray machines are equipped with electronic means to provide dose–area product (DAP) information. For machines without that ability, an alternative method is to record radiation on a film that can handle a large amount of cumulative exposure. The use of GafChromic XR Type R film was investigated for this purpose by placing it at the X‐ray tube assembly to record the radiation in interventional radiological procedures. Dose‐area product was determined with a reflective densitometer and then with a flatbed scanner. Precisions were demonstrated to be 5% and 2%, respectively. In a comparison with the machine‐recorded DAP, a regression analysis showed the validity of both techniques for values less than 1200 Gy‐cm2. PACS numbers: 87.52.Df, 87.66.Cd

Analysis of velocity estimation error for a multidimensional Doppler ultrasound system

The error characteristics of a single-transducer (one dimensional), dual-transducer (two-dimensional), and triple-transducer (three-dimensional) system for velocity estimation are examined. A velocity vector is completely characterized by the magnitude and the directional angles. For a single-transducer case, the velocity magnitude alone can be estimated. The variation in the directional angles for a single-transducer case cannot be accounted for in the estimation process, thus resulting in large errors. For a dual transducer, both the velocity magnitude and the angle on the x-y plane can be estimated. The use of an extra transducer provides added flexibility in the estimation process. Variation in one of the directional angles is accounted for in the estimation process, thus resulting in smaller error than the single-transducer case. For a triple-transducer case, if the normal angles between the three transducer axes are known, then the complete velocity vector with all the directional angles can be estimated.<<ETX>>