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This paper explores the stroller mechanism by using the creative mechanism method. These creative mechanism methods include the freedom method and the link assortment method. The analysis modeling is the simply four link mechanism. From this analysis result, this can be known that the stroller mechanism changes from four link to three link on the operation type. The mechanism of the stroller becomes the structure of the stroller by using the latch lock. Therefore, the creative mechanism method can be used to analyze the one degree freedom mechanism. This paper uses the six link to analyze the stroller mechanism. Last, this can get the nine new mechanism of the stroller

Coffee is one of the popular beverage; its constituents include caffeine, oxidation resistant aromatic constituents, protein, tannin, and fat. It is indicated in literatures that a proper amount of coffee stimulates the brain and enhances memory, but excessive coffee causes negative results, such as coronary artery disease, high blood pressure, heart disease and kidney disease. This study used high-performance ultrasonic process to discuss the effect of pulverized coffee reduction on the constituent concentration. It further compared the constituent concentrations obtained in different extraction periods. The experimental results show that the coffee aroma constituents can be extracted effectively by ultrasonic process without any organic solvent, and the constituent concentration does not decrease with the addition of pulverized coffee. Therefore, the consumption of pulverized coffee can be reduced greatly by using the proposed. The time of extraction process can be shortened, so as to save energy. The most important point is to reduce the enterprises manufacturing cost and to increase the profit.

This paper investigates using an optical measurement method to determine the concentration ratio in a liquid mixture of methanol and ethanol. To better understand the relative mixture solution concentration, the dilution method is used to determine slight variations in the refractive index of the variable mixture concentration. The test concentration range of both methanol and ethanol is between 0–90%. The results of our analysis indicate that the refractive index of a mixture of methanol and ethanol lies in the interval between the refractive index of pure ethanol and methanol. The optical property of the mixture is similar to that of the solution material with the highest quantity. Regression analysis using a quadratic function resulted in an error of 25%. Regression analysis using a cubic function reduced the error to 6.25%. Therefore, the regression analysis function used in this study is the cubic function, as the mixture solution includes the methanol liquid. Combining the optical measurement and dilution methods can yield the solution concentration of the liquid mixture.

Hydrogen storage is an important topic because of its relevance to the future energy economy. Hydrogen diffusivity in materials plays an important role in hydrogen technology both for hydrogen separation and hydrogen storage. To clarify the mechanism of the rate-controlling step, diffusion mechanism of hydrogen in metallic materials is studied by molecular dynamics method. This study performs semi-empirical-quantum molecular dynamic simulations in order to clarify hydrogen atom diffusion behavior in ZrNi alloys materials. We investigate the mechanical properties change associated with temperature variation for ZrNi base alloys and also consider the influence of materials micro-structure change of hydrogen diffusion. Finally, current work presents a theoretically prediction of dynamical diffusion coefficient to compare diffusion kinetics of crystalline and amorphous structure.

In this research, our focus is the use of ultrasound thermal process to extract flavor and caffeine from coffee. The different operating conditions for extraction experiments are executed and the results are also compared. The results show that coffee flavor is not enhanced with the increase of temperature because the volatile degree of coffee flavor components is quick and easy to be reached at high temperatures. From the experimental results, it can be found that using low vibration frequency is better than using high vibration frequency. Also, caffeine will be reached into the saturated state at the 15th second of the extracting time and the quantity of caffeine augments with the increase of temperature

In this paper, Taguchi method is applied to optimize ultrasound thermal process for extracting caffeine and flavor from coffee. The use of ultrasound can abridge experiments in cost, energy loss and time; the different operating conditions for extraction experiments are executed and the results are also compared. The results show that the best design factors for caffeine are 95? of extraction temperature, 28 kHz of operating frequency and 30 s of extraction time. The proposed optimized extraction method is efficient and energy-saving compared with the general process for making coffee

A two-dimensional differential transformation method is employed to reduce the partial differential equations of the non-continuous thermal conductive boundary value problem to a Taylor series in a polynomial form. The partial differential equations are solved by the two-dimensional T-spectra method of differential transformation and by the use of trial initial polynomial conditions. The investigative parameters include the time-step of the differential transformation and the number of sub-domain segments. The numerical simulation results indicate that the proposed approach using the two-dimensional T-spectra method of differential transformation is applicable to the solution of non-continuous thermal conductive boundary value problems.

This study develops a high-precision, non-destructive optical metrology system based on a position sensing detector for measuring the refractive index of a liquid solution such that its alcohol concentration can be derived. A series of experiments are performed to measure the refractive indices of samples of known alcohol concentrations in the range 0–99.5%. The experimental results indicate that the refractive index and the alcohol concentration are related by a quadratic function. According to this mathematical function, the refractive index of a sample with an alcohol concentration of 95% is n95%=1.36442. The measured value of the refractive index of the same sample is found to be nalcohol-95%=1.36587. The deviation of just 0.00145 between the two sets of results confirms the accuracy of the analytical prediction method. For a sample with a known alcohol concentration of 37%, the error between the analytically predicted concentration value and the actual value is found to be less than 0.7%. Overall, the results confirm that the proposed system provides a low-cost, straightforward and highly precise approach for measuring the alcohol concentration of liquid samples.

This study describes the high-precision positioning control of a system with asymmetric hysteresis. A switching system concept is adopted to describe the Preisach-type hysteresis, and a systematic modeling procedure is established to obtain the parameters of the system. A piezoelectric actuator system driven by a voltage amplifier is used to verify the modeling accuracy. A control structure, comprising a feedforward controller and a PD-type feedback controller, is used to realize the high-precision positioning control of the piezoelectric actuator driven stage. To enhance tracking control, a high-frequency modified term is incorporated into the hysteresis model. The experimental results confirm that the addition of this modified term reduces the tracking error and prevents the controlling energy from being saturated.

This study employs finite element simulations to investigate the relationship between the equivalent mass and the real mass of end masses adhered to the tip of the cantilever beam of an atomic force microscope. The equivalent mass was determined by analyzing the variation in the resonant frequency of the cantilever beam caused by the addition of the end mass. The analysis considered five different adhesive mass materials, namely copper, aluminum, S45C steel, titanium alloy and magnesium alloy. Furthermore, the analysis also considerd the effect of the position of the adhesive mass on its equivalent mass value. The numerical results indicate that the equivalent adhesive mass is less than the real adhesive mass. The ratio of the equivalent adhesive mass to the real adhesive mass is approximately constant for a given adhesive position and adhesive material and has a value of approximately 0.6361 for a high-density material. Finally, the results show that an offset of the adhesive mass from the tip position causes a slight change in the value of the equivalent mass to real mass ratio.

This paper presents a high-precision, non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Significantly, the proposed method enables the two refractive indices of the optical sample to be measured simultaneously. The performance of the proposed system is verified using a commercial quartz optical wave plate with known refractive indices of 1.5518 e n = and 1.5427 o n = , respectively, and a thickness of 452.1428 μm. The experimentally determined values of the refractive indices are found to be 1.55190 e n = and 1.54281 o n = , respectively, while the thickness is found to be 452.189 μm, corresponding to an experimental error of approximately 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself and provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates.

This study presents an enhanced common path interference system designed to measure the refractive index of crystal optical components. The proposed system is based on the classic Michelson interferometer and comprises a frequency stabilized helium-neon (He-Ne) laser, a beam splitter, a fixed mirror, an adjustable mirror, and a light detection system. The waveplate of interest was clamped to a rotatory motor and positioned between the beam splitter and the fixed mirror. The refractive index of the waveplate was then derived from the change in rotational angle of the waveplate as it moved from one position of minimum interference to the next. The measurement system proposed in this study is simple in construction, straightforward in operation, and robust to the effects of experimental noise. Furthermore, the system is a non-contact measurement system, and hence does not damage the optical component of interest. The experimental results are found to be in good agreement with the theoretical results. Therefore, the proposed system provides a viable means for the rapid experimental evaluation of the optical characteristics of quartz components.

This paper studies the bifurcation and nonlinear behaviors of a flexible rotor supported by relative short gas film bearings. A time-dependent mathematical model for gas journal bearings is presented. The finite difference method with successive over relation method is employed to solve the Reynolds’ equation. The system state trajectory, Poincare maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and subharmonic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and rotational velocity. The results of this study contribute to a further understanding of the nonlinear dynamics of gas film rotor-bearing systems.

This paper studies the behavior of a flexible rotor supported by a herringbone-grooved gas journal-bearing system. A hybrid method is employed to develop a time-dependent mathematical model of the bearing system. The finite difference method is employed with the successive over relaxation technique to solve the Reynolds equation. The system state trajectories, Poincare maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and the journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and quasi-periodic responses of the rotor and the journal center. The present numerical study illustrates the relationship between the dynamic behavior of this type of system and the rotor mass and bearing number. As such, the present results provide a deeper understanding of the non-linear dynamics of gas film rotor-bearing systems.

The optical characteristics of LCDs, e.g. their brightness, contrast ratio and response time, are sensitive to the structural parameters of the liquid crystal cells. This study develops a phase retardation measurement system using a laser interferometer, a liquid crystal cell and a function generator. When the liquid crystal particles are subjected to an electric field effect, their orientation changes, causing a corresponding change in the optical path length through the liquid crystal cell. By relating the optical path length difference to the change in the particle angle, the relationship between the phase retardation and the applied voltage can be obtained.

This study proposes a non-destructive measurement method for determining the thickness of an optical wave plate. The measurement system comprises a laser interferometer to conduct optical path length measurement, a stepping motor to adjust the angle of the incident light on the wave plate, and a computer to perform data calculations. The optical path difference is obtained by adjusting the angle of rotation of the wave plate using the stepping motor. The thickness of the optical wave plate can be obtained accurately and rapidly from the mathematical relations describing the optical path length difference. The proposed measurement method is capable of measuring large thicknesses (i.e., at the cm scale) with nano-scale precision. As such, the method provides a valuable contribution to the field of precision thickness measurement.

This paper presents the analysis and control of active magnetic bearing (AMB) systems with a flexible rotor. A sliding mode controller design scheme is proposed to compensate for the nonlinear effects of the AMB system. A nonlinear model of the AMB system with an electromagnetic actuator and a flexible rotor is proposed to facilitate the present system analysis and controller design. This nonlinear model takes into account the dynamics of the flexible rotor, the characteristics of the nonlinear electromagnetic suspended system, and the contact force between the auxiliary bearing and the shaft. This study also considers the auto-centering control of the AMB system when subjected to disturbances and variations in the system parameters. The numerical results show that the system exhibits a periodic motion and demonstrates high accuracy and robustness when operating under sliding mode control.

Output feedback sliding mode control has received great research interests, due to it does not require full accessibility of states and increases the ability of practical implementation of sliding mode control. In this paper, a new approach of chattering-free OFSMC design is proposed by incorporating integral sign function control for general multi-input multi-output linear uncertain systems. Compared with the boundary layer type chattering-free designs, the complete robustness to system matched disturbances or uncertainties has not to be sacrificed and the global attractiveness of the sliding surface can be achieved through the controller synthesis.

This paper studies the bifurcation of a flexible rotor supported by gas film bearings. A time dependent mathematical model for gas journal bearings is presented. The finite difference method, with the successive overrelation method (SOR), is employed to solve the Reynolds equation. The system state trajectory, Poincare maps, power spectra and bifurcation diagrams are used to analyse the dynamic behaviour of the rotor and journal centre in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behaviour comprising periodic and subharmonic response of the rotor and journal centre. This paper shows how the dynamic behaviour of this type of system varies with changes in rotor mass and rotational velocity. The results of this study contribute to a further understanding of the non-linear dynamics of gas film rotor-bearing systems.

The demand for high-precision stages has received great attention due to the progress of nano-technology in recent years. Systems to provide long-range and high-precision performance for positioning, tracking and contouring actions have become stringent issues. Among these systems, the ball-screw-driven systems have been widely used in industrial applications and academic researches. In such systems, the friction behavior dominates the resulting performance and is usually known as the stick-slip phenomenon. The friction dynamics can be divided into the static and the dynamic regimes according to the conventional usage. In this paper, friction models are introduced to describe the dynamic behavior of a conventional ball-screw-driven x – y stage. The coherence between the theoretical and experimental data supports the validity of these models. Two sets of controllers corresponding to the static and the dynamic friction models are proposed based on the integral type sliding mode control (SMC) law. Experimental results demonstrate that the system achieves high-precision (10 nm) and long-range (10 cm) positioning performance with repeatability and robustness by the proposed control approaches.

A direct search algorithm to find the maximum likelihood estimate for parameter identification problems is proposed in this paper. The parameter identification criterion function is constructed by differential transform, and an algorithm for adjustment of the unknown parameters is selected and used to identify the parameters in such a way that the criterion function is minimized. This method has the following advantages: (1) The spectra of system model can be obtained with the unknown parameter and the initial value of state variable, therefore, the criterion function can be constructed from the above spectra. (2) The problem of singularity and sensitivity in solving traditional inverse problems can be avoided. (3) The solving process is performed in iteration and is easily realized in the numerical computation. (4) Both linear and nonlinear problems can be solved with the same process.

In this paper, an extended sliding mode controller is applied to control a hyperchaotic motion in Rossler system. The sliding surface of this paper used is one dimension higher than traditional sliding surface and guarantees it passing through the activated initial states of controlled system. Therefore, using the characteristic of this sliding mode to design a controller not only can meet the desired specification but also without chattering phenomenon and abrupt state change. By comparing with the result in the existed literatures, the results show that the proposed controller can steer Rossler system to the desired state accurately. It also provides a good characteristic for disturbance rejection.

In this paper, bifurcation analysis of the dynamic response of active magnetic bearing (AMB) with flexible rotor is presented, which includes the coupling effect between X-Y directions caused by rotational motion. The AMB systems include many nonlinear factors, such as mass imbalance, mass ratio with disk and journal, material property of shaft, and magnetic forces, etc., and its dynamic behavior are inherently nonlinear. Bifurcation diagrams of shaft journal's center, trajectories, power spectra, and Poincaré maps are used to analyze the dynamic behavior of the AMB system under different operational conditions. The key factors affecting the dynamic characteristics of the AMB system are identified. It will be beneficial to the design of AMB system.

The differential transform is a numerical method for solving differential equations. In this paper, we present the definition and operation of the two-dimensional differential transform. A distinctive feature of the differential transform is its ability to solve linear and nonlinear differential equations. Partial differential equation of parabolic, hyperbolic, elliptic and nonlinear types can be solved by the differential transform. We demonstrate that the differential transform is a feasible tool for obtaining the analytic form solutions of linear and nonlinear partial differential equation.

In this paper, initial-value problems are solved by the differential transformation method. The differential transformation method of fixed grid size is used to approximate solutions of linear and nonlinear initial-value problems. An adaptive grid size mechanism based on the fixed grid size technique is also proposed. The proposed adaptive grid size procedure provides concise adjustment policy and raises computational efficiency of using differential transformation method.

The differential transformation technique is applied to solve a nonlinear differential equation that describes the underdamped and the overdamped motion of a system subjected to external excitations. Numerical results are compared to those obtained by the Runge-Kutta method to illustrate the preciseness and effectiveness of the proposed method.

In this paper, a Sprott chaos synchronization (SCS) based maximum power tracking (MPT) controller for a wind-driven permanent-magnet synchronous generator (PMSG) is proposed. Since SCS can express dynamic behaviors using incremental conductance to adjust the terminal voltage to the maximum power point, the controller is sensorless. The experimental result is illustrated to demonstrate the effectiveness of the proposed MPT controller.

In this paper, a procedure for constructing a fuzzy model of a given system associated with a digital fuzzy filter is proposed. Based on the structure of the Smith predictor, a hybrid model predictive control approach is also presented. Two experimental results using (1) an analogue simulator and (2) a blower temperature control rig have been illustrated. It shows that the proposed control structure is a feasible approach to control systems with time-delay.

Many studies have been shown and focused that variation of the quantity of vasoconstriction and blood pressure will cause the nonlinear chaotic behaviors in the heart blood vessel system and then induce the cardiovascular effect. Due to this kind of non-periodic motion is random and difficult to control, it is important to analyze and understand the status of dynamic system under different parametric conditions. In this paper, the differential transformation method is used to investigate the governing equations of system, and the dynamic behavior is characterized by reference to bifurcation diagrams, phase portraits, power spectra, and Poincare map produced. The results indicate that the system behavior is significantly dependent on the magnitude of the vibrational amplitude. Specifically, the motion changes from T-periodic to 2T-periodic, then from 4T-periodic to 8-periodic, and finally to chaotic motion with windows of periodic motion as the vibrational amplitude is increased from 0.3 to 0.6. The results can be used as the basis for subsequent development of the control system design, and also reduced the possibility of cardiopathy.

This paper employs a hybrid numerical method combining the differential transformation method (DTM) and the finite difference method (FDM) to analyze the nonlinear dynamic behavior of a rigid rotor supported by an elliptic gas bearing system (EGBS). The results obtained for the orbits of the rotor center are in good agreement with those obtained using the traditional FDM approach. Moreover, the results presented summarize the changes which take place in the dynamic behavior of the EGBS as the bearing number are increased over the range 2.0 ∼ 5.0, and therefore provide a useful insight into the nonlinear dynamics of the bearing system.

This study develops a high precision non destructive measurement technique based on a laser interferometer for determining the mixture of methanol and ethanol from its refractive index. The optical metrology system is employed to measure the refractive indexes of mixture sample with known methanol and ethanol. The ratio set of the mixture sample have seven sets. The refractive index of the ethanol solution with the methanol alcohol is reduced. When the mixture solution includes the methanol and ethanol, the refractive index of the mixture solution is between the refractive index of the ethanol and methanol. When the refractive index of the solution is very close the refractive index of the ethanol alcohol, the effect of the mixture solution in refractive index is very small. From this experimental result, the effect of the refractive index of the mixture solution in the refractive index of the ingredient liquid is very clear.

This study develops a high-precision, nondestructive measurement technique based on a laser interferometer for determining the methanol concentration of a liquid solution from its refractive index. The optical metrology system is employed to measure the refractive indexes of samples with known methanol concentrations ranging from 0 ~ 90%. The error between the experimental refractive index and the literature refractive index is small than 0.00062. The error between the measured value of the refractive index and the analytically derived value is reduced form 0.00064 to 0.00007. The decreased error ratio is about 89%. When the relative function between the refractive index and methyl alcohol concentration is cubic, this can reduce the regressional analysis error. By applying regressional analysis to the experimental results, an analytical expression is derived to describe the cubic relationship between the refractive index and the methanol concentration. An excellent agreement is observed between the experimentally determined values of the methanol concentration and the analytically predicted results.

The reasons why mechanical stirring tanks are extensively applied to fermentation, gas absorption, waste water treatment and so on are because of its advantages of easily modified operating conditions, effective liquid separation and many more. Its primary function is to effectively separate liquid so as to boost the liquid flowing efficiency. The paper is mainly focused on analyzing the two-dimensional flow field of mixing blades of different sizes at dissimilar rotational speed. The result shows that the baffles of longer length will easily lead to instability of the flow field. However, we also find out that the longer the tank baffle is, the easier the eddy currents will occur, and the pressure generated by the tank baffle is greater as well. It is easier to mix liquids evenly if the length of a mixing blade is longer.

The paper studies the effect of the adhesive mass in the cantilever beam dynamic. In this paper, this determines the adhesive mass by using the adhesive material volume. The adhesive volume estimation is the semi-sphere volume. The adhesive volume in the cantilever beam can be determined by using the SEM (Scanning Electron Microscopy, SEM). From the analysis result, this can be found that the effect of the moisture in the cantilever beam resonance is very clear. These determined materials are four material included Mg, Cu, Fe and Ti. These analyzed result show that the determined adhesive mass error between the semi-sphere volume method and the resonance method is smaller 15.99% in these four materials. The adhesive mass big error shows in the handling material. This can know that the result by using the semi-sphere volume method is very closed the theoretical value by using the cantilever beam resonance.

This paper studies the bifurcation behavior of the probe tip of an atomic force microscope with a proportional-plus-derivative (PD) feedback control using the DT (differential transformation) method. The dynamic behavior of the probe tip with PD control law is characterized by reference to maximum Lyapunov exponent plots produced using the time-series data obtained from differential transformation method. Furthermore, the detailed transitions in the dynamic response of the probe tip are examined using bifurcation diagrams of the tip displacement and the tip velocity, respectively. The results indicate that the probe tip behavior is significantly dependent on the magnitude of the proportional and derivative control gain. Specifically, the probe tip motion includes T-, 2T-, 3T-, 4T-, multi-periodic, and chaotic motion. Numerical results show that the dynamic behavior will leave chaotic motion to periodic motion at K p =−0.45 in the steady state by changing the control loop gain Kv from −0.1 to −1.0. Furthermore, it is demonstrated that the differential transformation method is in good agreement for the considered system.

This paper employs a numerical method combining the differential transformation method and the finite difference method to study the bifurcation behavior of a rigid rotor supported by a micro gas bearing system. The numerical results reveal a complex dynamic behavior comprising periodic, sub-harmonic, and quasi-periodic responses of the rotor center. Furthermore, the results reveal the changes which take place in the dynamic behavior of the bearing system as the bearing number is increased. The current analytical results are found to be in good agreement with those of other numerical methods. Therefore, the proposed method provides an effective means of gaining insights into the nonlinear dynamics of micro gas film rotor-bearing systems.

Since the beginning of the new millennium, the self-balancing two-wheeled robot (SBTWR) has become more and more popular due to its responsive yet precise movement and pollution-free. This paper is devoted to investigating both the dynamics analysis and the balance control for a SBTWR which is inherently unstable. In this dissertation, we present a robust control algorithm to stabilize the unstable SBTWR. By the Lyapunov stability theory with control term, a suitable sliding surface is proposed to ensure the stability of the controlled closed-loop system in sliding mode. Then, a sliding mode controller is designed to guarantee the hitting of the sliding surface even when the system contains system uncertainties and external disturbances. A computer simulation demonstrates the feasibility of the proposed control schemes.

This paper presents the design of a nonlinear rule based fuzzy logic controller for the nonlinear dynamic behavior of the probe tip of an atomic force microscope system (AFMs). At first, we use the bifurcation diagram to analysis the complex dynamic behavior of the atomic force microscope system. Next, the positive maximum Lyapunov exponent is obtained to identify that the chaotic motion do exist in AFMs. In order to suppress the undesired chaotic motion in AFMs, we address the design schemes of fuzzy logic controller to stabilize the slave chaotic AFMs to the master periodic AFMs. In the controller design process, it directly constructs the fuzzy rules subject to a common Lyapunov function such that the error dynamics of master and slave AFMs satisfy stability in the Lyapunov sense. It overcomes the trial-and-error tuning for the membership functions and rule base in traditional fuzzy logic control. Finally, a numerical simulation is used to illustrate the effectiveness of the proposed controller.

The object of the paper is the generation and vibration analysis for the self-power module with the pizo-structure and spring-mass system by using the external harmonic displacement. These three external harmonic displacement frequencies are considered. These include f0 = 4.8696 Hz, f1 = 24 Hz and f2 = 85 Hz. Form the analysis result; this can be known that as the external harmonic displacement frequency is the resonant frequency, the mass block maximum displacement is the 0.37 m. The generations of the up and down piezo-electronic are 0.044499756 V and 1.551240332 V, respectively. When the external harmonic displacement frequency is more than the resonant frequency of the mass block, the double harmonics motion of the mass block displays, the maximum displacement of the mass block by applied the external resonant frequency is more than by applied the external higher frequency.

This study develops a high-precision, non-destructive measurement technique based on a PSD for determining the glucose concentration of a liquid solution from its refractive index. The optical metrology system is employed to measure the refractive indexes of samples with known glucose concentrations ranging from 10 ~ 100 g/l. By applying regressional analysis to the experimental results, an analytical expression is derived to describe the linear relationship between the refractive index and the glucose concentration. As the glucose concentration 50 g/l is applied, the error between the measured value of the refractive index and the analytically derived value is just 0.0004437627. An excellent agreement is observed between the experimentally determined values of the glucose concentration and the analytically predicted results.

This study performs a series of experimental investigations to determine the temperature and pressure conditions which maximize the quantities of caffeine and EGCG extracted from green tea using a supercritical fluid extraction process with a carbon dioxide solvent. The experimental data are then used to construct a fuzzy model for predicting the extractant quantities given the temperature and pressure conditions of the extraction process. The average discrepancy between the experimental results and the predicted results for the quantities of caffeine and EGCG extracted at temperatures of 40°C, 50°C and 60°C, respectively, is found to be just 7.38%, thus confirming the viability of the fuzzy model as a predictive tool. Overall, the results reveal that a temperature of 40°C and a pressure of 2500 psi represent the optimum extraction conditions for both caffeine and EGCG.Copyright © 2008 by ASME

The atomic force microscope system has become a popular and useful instrument to measure the intermolecular forces with atomic-resolution that can be applied in electronics, biological analysis, materials, semiconductors etc. This paper studies the complex nonlinear dynamic behavior of the probe tip between the sample and cantilever of an atomic force microscope using the differential transformation method (DTM). The dynamic behavior of the probe tip is characterized by reference to bifurcation diagrams, and Poincare maps produced using the time-series data obtained from differential transformation method. The results indicate that the probe tip behavior is significantly dependent on the magnitude of the vibrational amplitude. Specifically, the probe tip motion changes from T- periodic to 3T-periodic, then from 6T-periodic to multi-periodic, and finally to chaotic motion with windows of periodic motion as the vibrational amplitude is increased from 0 to 5.0. Furthermore, it is demonstrated that the differential transformation method is in good agreement for the considered system.