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This paper presents a rail-to-rail class-AB operation amplifier with a proposed high-slew Miller compensation technique and current limiter for the output stage. Owing to the proposed Miller compensation technique, the amplifier achieves a maximum slew-rate of 30 V/µs while consuming a low quiescent current of 18µA. Among the state-of-the-art devices, the proposed amplifier has the best FOM L of 34.72 for average slew-rate and FOMs of 10.11 for unity gain frequency.

This paper presents an all-paths inductor-connected buck-converter (APICBC). The APICBC balances conduction losses and has continuous paths-currents for high-frequency switching. Efficiency is optimized over a wide load current range due to the adaptive sizing of the power transistors. The converter has three inductors implemented by bond-wire and PCB patterns and operates with a switching frequency of 100 MHz. The maximum efficiency is 81.2%, and the IC is implemented in a 0.18 µm CMOS process.

This paper presents a rail-to-rail class AB single-stage buffer amplifier to drive a capacitive load (C o ). To achieve a high DC gain and a high slew-rate (SR), the proposed amplifier uses different-ratio current-mirrors (DRCMs) and positive feedback loops (PFLs). The proposed amplifier drives a wide range of C o over 0.15 – 15 nF owing to the single-stage structure. A prototype chip was fabricated in a 0.18-μm CMOS process and occupies an area of 0.014 mm2.

The Rayleigh-Benard convection of viscoelastic fluids in a cavity is simulated using the grid-by-grid inversion method. The grid-by-grid inversion method allows the algorithms for Newtonian fluids to be applicable to viscoelastic fluids using a technique of deferred correction. Until now, the detailed characteristics of thermal convection in a cavity have not been investigated sufficiently. Employing the grid-by-grid inversion method, we have found a peculiar phenomenon specific to the viscoelastic fluids, which cannot be predicted by the linear and nonlinear stability analysis. Contrary to the cases of Newtonian fluids and viscoelastic fluids in the parameter range of exchange of stabilities, the convection cell of viscoelastic fluids in the parameter range of Hopf bifurcation changes the circulation direction at each temporal period of oscillatory convection.

We investigate forced convection of a nanofluid in the entrance region of a cylinder and in the fully-developed region of a coaxial cylinder employing the pseudo-single-phase continuum model and the homogeneous single-phase model. While the homogeneous single-phase model assumes a uniform nanoparticle distribution, the pseudo-single-phase continuum model takes care of nonuniform nanoparticle distribution. There has been controversy regarding the cause of heat transfer enhancement in nanofluids. Whether it is caused solely by the variation of thermophysical properties or the nanoparticle distribution also affect it. This controversy may be resolved employing these two models. It is found that nanoparticles drift from hot wall to cold central region in the entrance region, while they drift from cold inner surface to hot outer surface in the fully-developed coaxial cylinder due to the thermophoresis. The resulting nonuniform distributions of nanoparticles are found to add the heat transfer enhancement slightly. On the other hand, the frictional dissipation increases when the heat transfer rate increases. In a sense, the enhanced heat transfer rate is partly achieved at the expense of a higher energy consumption.

The packed bed may be viewed as consisting of two distinct fields, i.e., one existing on the macroscale and the other existing on the microscale levels. The macroscale describes phenomena occurring in the bed dimension and the microscale for those occurring in the intraparticle dimension. The macroscale temperature and concentration fields are found from a hypothetical continuum model of particle-fluid heterogeneous media. Each macroscale differential volume element contains several catalyst pellets, each of which is a microscale continuum embedded in a gross macroscale external fields. The boundary conditions of the microscale fields at the catalyst surfaces are provided by the solution of the macroscale model equations, while the heat and mass source terms of the macroscale model equations are determined by the microscale heat and mass transfer and chemical reactions within the catalyst pellets. In the present investigation, we have considered the HPPO process in which the propene oxide is produced by oxidizing propene with hydrogen oxide using the titanium silicalite-1(TS-1) catalysis. The set of six partial differential equations for the macroscale field coupled with the set of five partial differential equations for the microscale field at each macroscale point is solved employing the numerical Green’s function technique to overcame the inherent numerical instability in this coupled PDE system. The effects of pellet size, intra-pellet diffusivity and conductivity on the reactor yield and catalyst effectiveness factor are investigated.

We report the synthesis of colloidal plasmonic microspheres by taking advantage of emulsions of polydimethylsiloxane (PDMS) in metal precursor solution. Within the emulsion, both the spontaneous formation and threedimensional (3D) assembly of metal nanoparticles take place at room temperature. The number of the nanoparticles being assembled in the microsphere is controllable according to the concentration of a metal precursor. In addition, owing to the surface charge and porosity of PDMS, positively charged and neutral molecules can be more concentrated in the plasmonic microsphere. We use this plasmonic microsphere for the detection of environmentally and biologically important molecules via surface-enhanced Raman spectroscopy, since 3D assembly of metal nanoparticles in the microsphere is size-comparable to a probed volume of incident light.

Nanofluid is a suspension of nanoparticles with high thermal conductivity. Many investigations have been performed to find out the mechanism of enhanced heat transfer in the nanofluids. In the present work, we model the Al 2 O 3 /H 2 O nanofluid employing the pseudo-single-phase continuum model and investigate the fully-developed forced convection in a coaxial cylinder under a fixed pressure drop. It is found that the heat transfer coefficients of both the cold inner wall and hot outer wall increase with respect to the inlet mass fraction of nanoparticles. The enhancement of convective heat transfer coefficient is found to be slightly higher than that of thermal conductivity of nanofluid itself due to the drift of nanoparticles. On the other hand, the Nusselt number of cold inner wall increases but that of hot outer wall decreases as the inlet mass fraction of nanoparticles increases. It is revealed that this peculiar behavior of Nusselt number on the hot outer wall is caused by the drift of nanoparticles from the cold inner wall to the hot outer wall due to the thermophoresis. As the inlet mass fraction of nanoparticles increases under the condition of fixed pressure drop, the mixture viscosity increases and the volumetric flow rate is retarded, since the viscous dissipation must balance the input rate of mechanical energy at the steady state.

Recently, Due to the increased industry using radiation inspection equipment in the semiconductor, this demand of technology research is increasing. Although semiconductor inspection equipment is using low energy X-ray from 40 keV to 120 keV, Studies of radiation damage about the low energy X-ray are lacking circumstance in our country. Therefore, It is study that BJT (bipolar junction transistor) of one type of semiconductor elements are received radiation damage by low energy X-ray. BJT were used to the NXP semiconductor company's BC817-25 (NPN type), and Used the X-ray generator for the irradiation. Radiation damage of BJT was evaluated that confirm to analyse change of collector-emitter voltage of before and after X-ray irradiation when current gain fixed to 10. X-ray generator of tube voltage was setting 40 kVp, 60 kVp, 80 kVp, 100 kVp, 120 kVp and irradiation time was setting 180s, 360s, 540s into 180s intervals. As the result, We confirmed radiation damage in BJT by low energy X-ray under 120 keV energy, and Especially the biggest radiation damage was appeared at the 80 kVp. It is expected that ELDRS (enhanced low dose rate sensitivity) phenomenon occurs on the basis of 80 kVp. This studies expect to contribute effective dose administration of semiconductor inspection equipment using low energy X-ray, Also Research and Development of X-ray filter.

Nanofluids are composed of fluids and dispersed submicron solid particles. The presence of nanoparticles in the fluids enhances the effective thermal conductivity. In order to predict the enhancement of heat transfer in the nanofluids, it is necessary to model the nanofluid systems rigorously from the viewpoint of fluid dynamics. In the present investigation, we suggest a fluid mechanical model of nanofluids based on a rigorous theory of continuum mechanics. Starting from a two-fluid model, a pseudo-single-phase model is derived exploiting the fact that the velocity and temperature of nanoparticles follow tightly those of base fluid. The resulting pseudo-single-phase model of nanofluids is employed to investigate the Rayleigh–Benard convection of nanofluids. It is revealed that the presence of nanoparticles retards onset of convection and reduces convective fluid motion. Although the Nusselt number Nu and the heat transfer coefficient h are increasing functions of the Rayleigh number Ra for all values of particle mass fraction ωp, Nu is almost independent of ωp while h increases with respect to ωp because the thermal conductivity increases as ωp increases. The present pseudo-single-phase model of nanofluids may be adopted to predict heat and mass transfer as well as fluid dynamic characteristics in various nanofluid systems.

A multiscale packed bed model is proposed to simulate industrial carbon dioxide absorber and stripper employing the hot potassium carbonate process promoted by piperazine. At a macro scale, a material and energy balance for the packed bed is built with the consideration of basic reaction chemistry, phase equilibria and solution thermodynamics, where the facilitated mass transfer of CO2 caused by chemical reactions is taken care of by an enhancement factor. At a micro scale, the enhancement factor is calculated from the concentration profiles of chemical species in the liquid film around packing materials. The computational burden for the numerical solution of a set of diffusion–reaction equations at each macro scale location is circumvented by means of the Karhunen–Loeve Galerkin (KLG) method. The present multiscale model, where the KLG method treats the micro scale process of diffusion and reaction in the liquid film, is found to yield accurate predictions at a reasonably small computational cost. This method of solving multiscale problems can be applied not only to the present CO2 absorption/desorption processes but also to various systems in science and engineering, where the necessity of multiscale resolution is important.

Carbon dioxide emitted from the power plants may be removed in an absorber-stripper unit, where CO2 mass transfer enhanced by chemical reactions occurs. The mass transfer enhancement factor can be found accurately once we find the CO2 profile in the liquid film around a packing material. However, it costs a tremendous amount of computer time to solve governing diffusion–reaction equations for the relevant chemical species at each grid point of the packed bed to determine the enhancement factor accurately. Therefore, in the traditional models of packed bed, one adopts an approximate enhancement factor found from a simple model. In the present work, we employ the Karhunen–Loeve Galerkin (KLG) method for the solution of the diffusion–reaction equations describing the CO2 absorption with potassium carbonate promoted by piperazine in the liquid film. With the KLG method, the computational time for the diffusion–reaction equations is reduced drastically and the rigorous model for the enhancement factor can be adopted in the industrial packed beds. The resulting reduced order model is found to predict the concentration profiles of chemical species accurately. It shall be adopted in the multiscale model for a packed bed, where the macro scale describes the overall geometry of the packed bed and the micro scale describes the transport and reaction in the thin liquid film around a packing at an arbitrary macro location in the bed.

A practical method is developed to solve inverse natural convection problems sequentially. The sequential algorithm is based on the Kalman filtering technique. By reducing the Boussinesq equation to a reduced order model through the Karhunen–Loeve Galerkin procedure, the computational difficulties associated with the covariance equation are overcome. Although this method is found to yield accurate results with efficiency, its accuracy depends on that of the reduced order model employed. In the present investigation, it is demonstrated that this method can be further developed to be reasonably accurate and computationally feasible even with a relatively inaccurate reduced order model by employing the Boussinesq equation as the state equation while adopting the Kalman filter constructed from less accurate reduced order model.

Disturbances in blood flow to intervertebral discs (IVD) play an important role in IVD degeneration. Vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) are extremely important angiogenic factors for vasodilation and neovascularization. We investigated the relationship between single nucleotide polymorphisms (SNPs) of the VEGF and eNOS genes and genetic susceptibility to lumbar IVD degeneration in a young adult Korean population. Two hundred and forty-one participants (aged 18 to 30 years), with or without low back pain, were selected for the study. Magnetic resonance imaging was made of the lumbar spine in all participants. The patient group (N = 102) had low back pain clinically and lumbar IVD degeneration radiographically. The control group (N = 139) included subjects with and without low back pain; all were negative radiographically for lumbar IVD degeneration. Using PCR-RFLP analysis, we analyzed VEGF (-2578C>A, -1154G>A, -634G>C, and 936C>T) and eNOS (-786T>C, 4a4b and 894G>T) SNPs. We made combined analyses of the genes and performed haplotype analyses. There were no significant differences in the genotype distribution of polymorphisms of VEGF and eNOS genes among patients and controls. However, the frequency of VEGF -2578CA +AA/-634CC combined genotypes was significantly higher in patients when compared with controls [odds ratio (OR) = 21.00; 95% confidence interval (CI) = 2.590- 170.240]. The frequencies of the -2578A/-1154A/-634C/936C (OR = 3.831; 95%CI = 1.068-13.742), -2578A/-1154A/-634C (OR = 3.356; 95%CI = 1.198-9.400), and -2578A/-634C/936C (OR = 10.820; 95%CI = 2.811-41.656) haplotypes were also significantly higher in patients than in controls. We conclude that the combined genotype VEGF -2578CA+AA/-634CC is a possible risk factor for IVD degeneration and the VEGF -2578A/-1154A/-634C/936C haplotype may increase the risk for development of IVD degeneration. Furthermore, the VEGF -634C allele appears to be associated with susceptibility to IVD degeneration.

Microchannels made of polymeric materials usually have wall velocity slip. Sometimes, these microchannels are not smooth. Wall roughness is introduced by manufacturing processes or caused by adhesion of biological particles from the liquids. For a proper design and operation of these microchannels, it is important to secure an accurate value of zeta potential, which determines the volumetric flow rate of electroosmotic flows. Zeta potential of microchannels is usually determined by measuring the streaming potential. In the present investigation, we have derived a simple formula that predicts accurately the streaming potential of microchannels having wall roughness and Navier velocity slip, and investigated how the streaming potential is affected by wall roughness, slip coefficient, zeta potential and bulk ionic concentration. The simple formula, which requires numerical solution of three sets of Stokes equation sequentially using a small grid number, yields very accurate results as compared with the numerical solution of nonlinear partial differential equations employing a very large number of grids. It is found that the streaming potential per pressure drop increases with respect to slip coefficient and decreases with respect to wall roughness hight. On the other hand, the streaming potential per volumetric flow rate increases as the wall roughness increases.

Cavitation causes a great deal of noise, damage to components, vibrations, and a loss of efficiency in devices, such as propellers, pump impellers, nozzles, injectors, torpedoes, etc., Thus, cavitating flow simulation is of practical importance for many engineering systems. In this study, a two-phase flow solver based on the homogeneous mixture model has been developed. The flow characteristics around an axisymmetric cylinder were calculated and then validated by comparing with the experimental results in the cavitation water tunnel at the Korea Ocean Research & Development Institute. The results show that this solver is highly suitable for simulating the cavitating flows. After the code validation, the cavity length with changes of water depth, angle of attack and velocity were obtained.. Cavitation inception was also calculated for various operational conditions.

In the nonisothermal gaseous flows through open vessels with chemical reaction and combustion processes, the flow can be approximated with compressible Navier–Stokes equation where density depends on temperature but is independent of velocity and pressure fields, which is called the low mach number approximation. To implement advanced estimation and control schemes such as Kalman filtering and optimal feedback control to low Mach number flows, it is necessary to find an accurate and reliable reduced-order model. One of the best methods available for this purpose is the Karhunen–Loeve Galerkin (KLG) procedure. The application of the KLG procedure to low Mach number flows, however, is never straightforward because some variables depend on temperature nonlinearly or exponentially and the velocity field is not solenoidal which prohibits the elimination of pressure in the Galerkin procedure. In the present investigation, we have overcome these difficulties by introducing appropriate auxiliary variables and have successfully derived a reduced-order model for low Mach number flows with radiative heat transfer and chemical reactions. The resulting reduced-order model is found to yield accurate results efficiently. The present work sets up the first stage for the real-time estimation and control of various gaseous nonisothermal reactors and combustors.

In complex fluids, solute molecules with structural length scales much larger than atomic are dispersed in solvents of simple fluids such as water. The rheological properties of complex fluids are determined by dynamics of solute molecules which can be modeled by the Fokker–Planck equation defined in a six-dimensional phase space. In the present investigation, we devise a method of efficient simulation of complex fluid flows employing the Karhunen–Loeve Galerkin (KLG) method. Adopting the decimated sampling of solvent flow fields, a reduced-order model for the Fokker–Planck equation is obtained, which can be employed for the the simulation of complex fluids with a decent computer time. As a specific example, we consider a flow of dilute polymeric liquids over a cylinder, whose constitutive equation is the FENE (finitely extensible nonlinear elastic) model. It is found that the KLG method with the decimated sampling technique yields accurate results at a computational cost less than a hundredth of that for the numerical simulation using the Fokker–Planck equation. The KLG method supplemented by the decimated sampling technique is an efficient method of coarse-graining for equations of complex fluids defined in the phase space.

We present a new algorithm for solving viscoelastic flows with a general constitutive equation. In our approach the hyperbolic constitutive equation is split such that the term for the convective transport of stress tensor is treated as a source. This allows the stress tensor at each grid point to be expressed mainly in terms of the velocity gradient tensor at the same point. Then, the set of six stress tensor components is found after inverting a six by six matrix at each grid point. Thus we call this algorithm the grid-by-grid inversion method. The convective transport of stress tensor in the constitutive equation, which has been treated as a source, is updated iteratively. The present algorithm can be combined with finite volume method, finite element method or the spectral methods. To corroborate the accuracy and robustness of the present algorithm we consider viscoelastic flow past a cylinder placed at the center between two plates, which has served as a benchmark problem. Also considered is the investigation of the pattern and strength of the secondary flows in the viscoelastic flows through a rectangular pipe. It is found that the present method yields accurate results even for large relaxation times.

The most widely adopted constitutive model of viscoelastic flows based on the kinetic theory is the FENE (Finitely Extensible Nonlinear Elastic) model. This model represents a polymer molecule by a dumbbell which consists of two beads connected by a spring. The direction and elongation of the spring are described by the Fokker–Planck equation. The two important parameters in the Fokker–Planck equation, which represent the relaxation time and the maximum extensibility of the dumbbell, determine the viscoelasticity of flows and affect the velocity fields. In the present work, we devise a method of estimating these two parameters using velocity measurements. The relevant inverse problem is solved by converting it to a minimization problem of a performance function employing a conjugate gradient method. The present scheme is shown to estimate these structural parameters even with noisy velocity measurements.

Rayleigh–Benard convection of viscoelastic fluids in a cavity is investigated using a newly developed grid-by-grid inversion method. In the grid-by-grid inversion method the hyperbolic constitutive equation is split such that the term for the convective transport of stress tensor is treated as a source. This renders the stress tensor a local function of the velocity gradient tensor as in the case of the Newtonian fluids and makes the algorithms for Newtonian fluids applicable to viscoelastic fluids. To corroborate the accuracy of the grid-by-grid inversion method, a linear stability analysis is performed to find the critical Rayleigh number and the domains of Hopf bifurcation and exchange of stabilities in the parameter space. The numerical results from the grid-by-grid inversion method are found to coincide with those of linear stability analysis exactly. Also considered is the standard benchmark problem of viscoelastic flow past a cylinder placed at the center between two plates to confirm the accuracy of the grid-by-grid inversion method.

We consider electroosmotic flows (EOF) generated by temporally varying zeta potential which is usually adopted for pumping or mixing of fluids. In this case the dynamics of ions in the electric double layer (EDL) influences the induced electric field and consequently the EOF significantly. Therefore, the appropriate model should be the Nernst–Planck (NP) model for all zeta potentials or the Debye–Huckel (DH) model for low zeta potentials rather than the Poisson–Boltzmann (PB) model which is based on the equilibrium distribution of ions in the EDL. In the present investigation, we compare the predictions from the DH model and the PB model with the exact ones from the NP model for a range of frequency of zeta potential oscillation. It is found that one may adopt the PB model when the frequency is low and the DH model when the zeta potential is low. However, for either high frequency of zeta potential oscillation or large value of zeta potential, one must adopt the NP model to get accurate predictions of EOF.

This study was conducted to develop an agaricus bisporus washing machine which uses compressed air to remove foreign materials attached on the surface of agaricus bisporus. A prototype of the washing machine was constructed, and performance of removing foreign materials was tested. Research results are as follows: 1. Several transferring methods including PE roller rotation, brush roller rotation, PE screw rotation, vibration plate, and belt conveyor were evaluated. Roller, screw, and vibration methods caused damages on the surface of the products, but belt conveyor method caused the least damages. 2. For air jet, a stationary nozzle type and a rotational type were evaluated. The best air jet nozzle was the jet-type nozzle, and the rotational type was more effective than stationary type nozzle. 3. With the conveyer belt, box type moving method and the rotational air jet nozzle, the washing machine showed the best performance when higher than 5.4105 Pa of air jet pressure and lower than 0.047 m/s of moving speed was used. Working performance of the system was 650 kg/h, and the damaging rate was 1.2 %.

We have performed the flat-fielding correction for the full-disk monitoring system of KASI (Korea Astronomy and Space Science Institute), which is installed in the Solar Flare Telescope (SOFT) at the top of Bohyun Mountain. For this, we used a new method developed by Chae (2004), to determine the flat pattern from a set of relatively shifted images. Using this method, we successfully obtained the flat pattern for full-disk observations and compared our result with the image observed in Catania Astrophysical Observatory. The method that we used in this study seems to be quite powerful to obtain the flat image for solar observations. In near future, we will apply this method for the flat-fielding correction of all solar imaging instruments in KASI.

In the microchannels made of hydrophobic materials, the fluid velocity is determined by the zeta potential and velocity slip, both of which may be inhomogeneous due to the adsorption of protein to the channel wall. The inhomogeneity of zeta potential and slip coefficient sometimes causes recirculating flows which in turn affect the transport and mixing of solutes through the microchannels. In the present investigation we devise a method for the simultaneous estimation of inhomogeneous zeta potential and inhomogeneous slip coefficient using velocity measurements. A conjugate gradient method supplemented by the adjoint variable method is adopted in the solution of the relevant inverse problem to reduce the computational burden. The present method is found to estimate the inhomogeneous zeta potential and the slip coefficient simultaneously even with noisy velocity measurements. This method is expected to contribute to the optimal design and robust operation of various microfluidic devices, where the flow patterns and the volumetric flow rates are critically influenced by the profiles of inhomogeneous zeta potential and inhomogeneous slip coefficient.

A reduced-order model is derived for electroosmotic flows in a microchannel of nonuniform cross-section. The model is constructed based on the Karhunen–Loeve Galerkin (KLG) procedure which can reduce nonlinear partial differential equations to sets of minimal number of ordinary differential equations. The reduced-order model of the present investigation is carefully constructed such that it is not necessary to re-evaluate any coefficient of the model even though the inhomogeneous zeta potential ζ ( x ) and the dielectric constant e vary. This feature reduces the computational time greatly when employed in the estimation and control of electroosmotic flows, where repeated solution of governing equations is required. Using the present reduced-order model, a practical method is devised to estimate inhomogeneous zeta potential ζ ( x ) from velocity measurements of the electroosmotic flow in the microchannel. The proposed method is found to estimate ζ ( x ) with reasonable accuracy even using noisy velocity measurements.

In the present investigation, we develop a method for estimating rheological parameters of viscoelastic fluids using velocity measurement in a square straight channel. It is believed that a somewhat complicated patterns of secondary flows due to the non-zero second normal stress difference are more useful than the simple viscometric flows traditionally adopted in the determination of rheological parameters. The inverse problem of determining the rheological parameters from a set of velocity measurements is solved using a conjugate gradient method. When applied to a general constitutive equation encompassing the UCM model, the Oldroyd-B model and the PTT model, the present method is found to yield a reasonably accurate estimation of five rheological parameters simultaneously even with noisy velocity measurements.

In the present work, we consider the linear and nonlinear hydrodynamic stability problems of two-dimensional Rayleigh–Benard convection in arbitrary finite domains. The effects of the domain shapes on the critical Rayleigh number and convection pattern are investigated by means of a linear stability analysis employing a Chebyshev pseudospectral method. An extension of the present technique to nonlinear stability analysis allows derivation of the Landau equation for arbitrary finite domains. The results of nonlinear stability analysis are confirmed by comparison with numerical solution of the Boussinesq set. The results of the present investigation may be exploited to enhance or suppress thermal convection by varying system domain.

In the present work, we consider the linear hydrodynamic stability problems of viscoelastic fluids in arbitrary finite domains. The effects of domain shapes on the critical Rayleigh number and convection pattern are investigated by means of a linear stability analysis employing a Chebyshev pseudospectral method. It is shown that the domain shape can change the viscoelastic parameter values where the Hopf bifurcation occurs in the Rayleigh–Benard convection. The results of the present investigation may be exploited to design shapes of convection box where the Hopf bifurcation occurs at realistic low values of Deborah number. This will enhance the usefulness of the natural convection system as a rheometry tool.

We consider the problem of suppressing the Rayleigh–Benard convection in a finite domain by adjusting the heat flux profile at the bottom of the system while keeping the heat input the same. The appropriate profile of heat flux at the bottom is determined by the optimal feedback control. When most of the convection modes are taken into consideration in the construction of the feedback controller, the suppressed state is found to be stable for all range of Rayleigh number investigated. With the feedback controller constructed by employing only the dominant convection modes, however, there exists a threshold Rayleigh number beyond which a new convective state emerges due to the hydrodynamic instability. The threshold Rayleigh number is found to increase with the number of modes taken in the feedback controller.

A three-dimensional inverse radiation problem is solved sequentially using an extended Kalman filter, where the time-varying strength of a heat source is determined from temperature measurements in the participating media. By employing the Karhunen–Loeve Galerkin procedure that reduces the set of governing equations composed of the radiative transfer equation and heat conduction equation to a small set of ordinary differential equations, the computational difficulties associated with the Kalman filtering for the integro-differential equation are overcome. The present technique allows a real-time implementation of the sequential identification of radiation field in participating media.

A hybrid-emulsion experiment has been carried out at KEK-PS to study S = −2 nuclei. With the analysis of about 35% of total emulsion, we have successfully found three events of sequential weak decay of a double-hypernucleus. The results of these E373 events are summarized together with those of past experiments. The first experimental study of the branching ratios of weak decay modes of double-hypernuclei has been performed.

The Karhunen–Loeve Galerkin procedure is a type of Galerkin method that employs as basis functions the empirical eigenfunctions of the Karhunen–Loeve decomposition, and proved to be a powerful tool for reducing the degree of freedom of partial differential equations [Int. J. Numer. Methods Engrg. 41 (1998) 1131; Comput. Methods Appl. Mech. Engrg. 188 (2000) 165]. In the present investigation, we extend the applicability of the Karhunen–Loeve Galerkin procedure to systems of variable domains and apply it to the shape identification problems of heat conduction systems, where the unknown boundary shape is estimated from temperature measurements on the other boundary. The efficiency and accuracy of the present technique are assessed as compared to the traditional technique employing the original partial differential equation.

Boundary optimal control problems of the Navier–Stokes equation are studied from a numerical point of view. When the adjoint variable method is used to minimize the objective function, the gradient of the objective function is not obtained accurately due to the insufficient regularity of the adjoint variable at the boundary. The resulting numerical error usually causes the conjugate gradient iteration to terminate prematurely. In the present investigation, a new method is developed that circumvents this difficulty with the adjoint variable method by converting the boundary optimal control problems to the distributed control problems. The present method is applied to two boundary optimal control problems, a driven cavity flow and a channel flow, and is found to solve the problems efficiently with sufficient accuracy.

In the radiant cooler, where the hot gas from the pulverized coal gasifier or combustor is cooled to generate steam, the wall heat-transfer coefficient varies due to ash deposition. In the present work, we investigate an inverse radiation problem of estimating the heat-transfer coefficient from temperature measurement in the radiant cooler. The inverse radiation problem is solved through the minimization of a performance function, which is expressed by the sum of square residuals between calculated and observed temperature, utilizing the conjugate gradient method. The gradient of the performance function is evaluated by means of the improved adjoint variable method, which resolves the difficulty associated with the singularity of the adjoint equation through its inherent regularization property. The effects of the number of measurement points and measurement noise on the accuracy of estimation are also investigated.

The control of natural convection in magneto-hydrodynamic (MHD) flow is investigated by means of the Karhunen–Loeve Galerkin procedure [Int J Numer Meth Engng 1998;41:1133–51]. The Karhunen–Loeve Galerkin procedure, which is a type of Galerkin methods that employs the empirical eigenfunctions of the Karhunen–Loeve decomposition as basis functions, can reduce non-linear partial differential equations to sets of minimal number of ordinary differential equations by limiting the solution space to the smallest linear subspace that is sufficient to describe the observed phenomena. In the present investigation, it is demonstrated that the Karhunen–Loeve Galerkin procedure is well suited for the problems of control or optimization, where one has to solve the governing equations repeatedly but one can also estimate the approximate solution space from the range of control variable. The performance of the Karhunen–Loeve Galerkin procedure for solving the optimal control problem of natural convection is assessed in comparison with the traditional technique employing the Boussinesq equation, and is found to be very accurate as well as efficient.

Protein–nucleic acid interaction is an important process in many biological phenomena. In this study, a fluorescence resonance energy transfer (FRET)-based protein–DNA binding assay has been developed, in which a fluorescent amino acid is genetically incorporated into a DNA-binding protein. A coumarin-containing amino acid was incorporated into a DNA-binding protein, and the mutant protein specifically produced a FRET signal upon binding to its cognate DNA labeled with a fluorophore. The protein–DNA binding affinity was then measured under equilibrium conditions. This method is advantageous for studying protein-nucleic acid interactions, because it is performed under equilibrium conditions, technically easy, and applicable to any nucleic acid-binding protein.