In present study, to visualize a complicated flow field in a sphere packed pipe, we performed three-dimensional simultaneous measurements of velocity field around pebbles in water by an IM method and our proposed holography technique with two laser beams. As a result, we succeeded in the matching of the positions of tracer particles measured by two cameras. The obtained velocity field by two cameras exhibits the finer flow structures than that by one camera.

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Mud erosion in methane hydrate bearing layers may be a problem for the production of methane gas. To comprehend the mud erosion in sand-mud alternate layers, a simulation code has been developed for mud erosion caused by water flow through pore space, based on lattice Boltzmann method. Sand-mud layers are numerically generated in a three-dimensional domain, in which shear stress is calculated by the momentum-exchange method. Distributions of shear stress on mud surfaces are simulated under different sand-mud patterns to estimate parameters relating to mud erosion.

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We develop a non-invasive measurement system based on fluorescence. The development of the system arises from the investigations of heat transfer characteristics of thermal energy storage and magnetic refrigeration. We use a light emitting diode (LED) as a light source instead of a laser. In order to evaluate the measurement feasibility and performance, an experiment was carried out using a heated test section filled with fluid. The test section was carefully designed based on the critical Rayleigh number, so that the heat transfer in the section would be dominated by conductive heat transfer only. Spatial temperature distribution was obtained by converting the fluorescence irradiance to temperature through calibration data. The initial result exhibited the expected monotonic temperature distribution in the test section and the feasibility of the temperature measurement based on the LED-induced fluorescence (LEDIF) was confirmed.

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When carbon dioxide (CO_2) is injected into the brine, the mixture in a form of CO_2 dissolves into the brine leads to an instability in which CO_2 saturated more-dense brine overlies unsaturated less-dense brine, giving rise to density-driven natural convection. Herein a nonlinear density property fluids system is used to model the convective mixing process. A three-dimensional visualization scheme employing micro-focused X-ray computer tomography (CT) technology is able to obtain the characteristic of the natural convection. The formation and advancement of Rayleigh - Benard fingers induced by density difference can be visualized. The mass transfer increases with the Rayleigh number. The dimensional flux Sherwood number is correlated with Rayleigh number following the power law relationship.

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The characteristics of methane-oxygen micro counterflow diffusion flames were experimentally studied. The flame thickness and flame diameter were determined as functions of the inner diameter of burners, the distance between burners and the flow rate of gases. When burners with large inner diameter were used, diffusion flames were observed in small burner distance. The flame thickness and flame diameter decreased as the burner distance became smaller, and they increased as the flow rate became larger. The flame stretch had a great influence on the flame thickness, i.e. the flame thickness decreased monotonously as the flame stretch became larger.

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We measured the laminar burning velocity for the CH_4/Air premixed using the double kernel method as pre-stage before measuring the laminar burning velocity of gasoline and its surrogate. We also examined the influence of pressure on the laminar burning velocity. The experimental results show that the double kernel method can be utilized to measure the laminar burning velocity, but we need to review the analytical method. For the case where the distance between plasma is 50 mm, we found that the pressure corresponds to the laminar burning velocity is two times higher than the initial pressure.

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To investigate propagation characteristics of methane-air premixed flames at high pressure, constant volume vessel which can control turbulence characteristics, initial pressure and equivalence ratio has been developed, and high repletion rate OH planar laser induced fluorescence (PLIF) and CH chemiluminescence measurements are performed in the combustion field. The flame front and radius of flame are evaluated from OH PLIF and CH chemiluminescence independently. When radius of flame is large, flame speed becomes constant in laminar flame but increases in turbulent flame. Flame speed which is evaluated from OH PLIF images fluctuates significantly because of local turbulence characteristics and flame structure.

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Hydrocarbon-ammonia combustion is a potential phase-in of CO_2 reduction for large scale energy systems. In this study, chemiluminescence spectrum of flame, laminar burning velocity and exhaust gas of methane/ammonia/air premixed flames were investigated varying with ammonia concentration in fuel. NH_2 α band spectrum was observed and flames became orange with the increase in the amount of ammonia in fuel. The laminar burning velocity decreased with the increase in ammonia in fuel. CO concentration in burned gas decreased with the increase in ammonia in fuel. NO concentration rapidly increased when ammonia ratio increased from 0 % to 5 %, then NO concentration gradually changes when ammonia ratio increased furthermore.

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This study is performed to examine experimentally the effects of CO_2 as one of EGR gas on the burning velocity of the propane-oxygen-dilution gas premixed meso-scale spherical laminar flames with the flame radius r_f < about 5mm. The mixtures have nearly the same laminar burning velocity (S_<L0>=25cm/s) with different equivalence ratios (φ=0.5-1.4). N_2 is also examined for comparison. The radius and the burning velocity of meso-scale flames are obtained by using sequential schlieren images recorded under appropriate ignition conditions. It was clear that the burning velocity for the mixture diluted with CO_2 at the same r_f and Karlovitz number has tendency to be larger than that with N_2, except for φ=1.4.

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Turbulent burning velocity of spherically propagating premixed flame continues increasing during flame propagation. The flame front area is considered to be the most dominant factor for turbulent burning velocity. In this study, turbulent iso-octane/O_2/N_2 flame shape was investigated under N_2 diluted condition and elevated pressure condition. Fractal analysis was conducted for stoichiometric spherically propagating premixed turbulent iso-octane/O_2/N_2 flames. Variations of fractal characteristics, such as fractal dimension and inner-cutoff scale with flame radius were investigated.

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This paper reports spark ignition behavior in simulated exhaust gas recirculation ambience using rapid compression machine. In this study, mixtures of nitrogen and oxygen without carbon dioxide are used as a simulated EGR gas. The fuel tested is propane. The equivalence ratio ranges from 0.5 to 0.62 and simulated EGR ratio ranges 20% to 50% at stoichiometry. Compression ratios are 9 and 10 initial pressure of premixed gas is 100kPa and 200kPa. The ignition probability is discussed in terms of the mole fraction of oxygen and nitrogen of ambient gas.

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Three-dimensional direct numerical simulation of methane-air turbulent premixed planar flame propagating in homogenous isotropic turbulence is conducted to investigate local flame structure in thin reaction zones. GRI-Mech 3.0 is used to represent methane-air reactions. For a better understanding of the local flame structure in thin reaction zones, distributions of mass fractions of major species, heat release rate and temperature are investigated. The results show that in thin reaction zones, pixel by pixel product of CH_2O-OH or CH_2O-H images have good correlation with heat release rate and is more accurate to discern local flame structures than single OH images. The correlation between heat release rate, principal curvature and tangential strain rate are investigated.

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This paper describes influence of flame stretch (especially curvature) on flame structure of triple flames. In front of the triple point, the stoichiometric mixture is formed. However, it has been indicated that the flame structure is different from the stoichiometric laminar premixed flames. In this study, we compare the flame structure of curved premixed flames with triple flames. As a result, the maximum heat release rate for triple point is smaller than that for unstreched laminar premixed flames, and it is also smaller than maximum heat release rate for curved premixed flames.

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Influence of wall is one of the important subject in combustors because many combustors, such as internal combustion engines, are surrounded by walls. Especially, the influence becomes more important in ultra-micro combustors. We aim to reveal the mechanisms of surface reaction on flame-wall interaction. In this study, we focus on OH radicals, which play important role in surface reaction, in stagnation flames. The temperature and the materials of the stagnation plate are changed, and the distributions of OH radicals are measured by OH-PLIF. The results suggest the influence of surface reactions in each material.

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The purpose of the study is development of a heat flux sensor for measuring heat flux from burnt gas to engine inner wall to improve thermal efficiency of the engine in SIP innovative combustion technology project. The heat flux measurement method, where heat flux is derived through transient heat conduction analysis combining with surface temperature measured with MEMS thin film resistor sensor, was experimentally examined. Heat flux measurement experiment in a butane-air premixed combustion system in a open chamber with the MEMS sensor was conducted. It was confirmed that the sensor and the method can measure 100kW/m^2 level heat flux at 1ms level temporal resolution.

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Temperature and particle size distributions along the flow axis in the premixed flame have been measured during silica nanoparticle formation for various mass fraction of oxygen, X_<O2> [%]. For X_<O2> = 26 %, the temperature along the axial position, z, was higher than the melting point of silica at 0 mm < z < 25 mm. The primary particle size increased with z because the particle formation could be controlled by the surface growth on a particle. On the other hand, the temperature was lower than that of the melting point at 40 mm < z < 60 mm. The primary particle size decreased also with z because the particle formation could be controlled by nucleus formation. For X_<O2> = 21%, the primary particle size was smaller than that for X_<O2> = 26% because the temperature was lower than that of the melting point.

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The paper presents to discuss an effective energy conversion through isothermal combustion during the expansion process, herein an analytical code is exploited for compressible fluid by taking into account the swirl flow and changes of cross sectional area along the flow direction as well. Based on the premise of homogeneous swirl flow, a pseudo 3-dimensional mathematical model is feasible to formulate and to discuss the effects of swirl flow, duct configuration, exothermic reaction rate on energy conversion.

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In this study, the validity of the moment method and sectional method that have been used as particle formation calculation was investigated numerically. Both methods were tested for the recent experimental data of the soot formation in C_3H_8/air mixture by a shock tube. CHEMKIN-PRO with the recently proposed PAH growth mechanism for C1-C4 gaseous fuels (KAUST PAH Mechanism 2, KM2) that included molecular growth up to coronene was used for the soot formation calculations. The computed soot characteristics such as mean particle diameter, soot yield etc. were compared between moment method and sectional method.

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End face combustion, burned an end face of highly densified biomass briquette one-dimensionally, is proposed since it might facilitate to control the fuel consumption rate. In this study, the behavior of the end face combustion was investigated with cylindrical and columned briquette. The influence of fuel supply rate and the briquette shape on the fuel mass loss rate was measured. The mass loss rate of the cylindrical briquette increases with increasing the fuel supply rate (from 2 mm/min to 6 mm/min). In case the fuel supply rate is equal to 4 mm/min with the cylindrical briquette, it was observed that the period mass loss rate stays almost constant.

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The simulant biogas-air coaxial jet flow and combustion are actively controlled through periodic excitation of the initial jet shear layer with arrayed miniature jet actuators. In the present study, CH_4 fuel is diluted by N_2 or CO_2 with various dilution rates to mimic biogas. Firstly, it is found that the large-scale vortical structures and the associated mixing of biogas-air are flexibly controlled by changing the injection frequency of miniature jet. In addition, it is demonstrated that CO emissions from the biogas flames operated with different fuel dilution rates can be significantly improved by manipulating the mixing upstream of the flame base.

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The bio-mass gas which is one of renewable energies is remarked for keeping resources and environment. Meanwhile, Plasma Assisted Combustion is studied now. Then, Fuel gas is radicalized due to plasma produced in the fuel gas by dielectric barrier discharge. In this study, combustion properties are reported about plasma assisted combustion The results are obtained as follows. (1)In diffusion flame, flame stability is increased. (2) In diffusion flame, when ammonium is mixed in fuel, the NOx concentration is reduced by plasma. (3) In premixed flame, the NOx concentration is increased by plasma. (4) Then, if ammonium is mixed in fuel, generate of NOx depends on fuel NOx.

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In this study, the Fuel-NOx formation characteristics under the high CO_2 diluted conditions have been experimentally investigated using a tubular flame burner. The NH radical concentration which dominates the fuel-N to N_2 conversion reaction in a oxy-fuel flame front was measured by LIF. The results showed that the NH concentration can be measured quantitatively in saturation regime when the incident laser intensity exceeded 6mJ for oxy-fuel combustion. The NH radical profile measured by LIF was found to be slightly different from the numerical results obtained by 1-D flame code.

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This study examined to accomplish low-emission and high-efficiency combustion in the bark boiler. The bark which is the fuel of the bark boiler contains much water and it has a big influence on combustion. Therefore combustion of low-emission and high-efficiency is enabled to dry the bark appropriately. In this study, it made a model using the numerical simulation and simulated a combustion state of the bark boiler. It was replaced by a methane gas fuel the bark of solid fuel and adjusting chemical reaction rates and the amount of methane gas.

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Secondary atomization behavior and spray flame characteristics of carbonated W/O emulsified fuel were studied. An emulsified fuel or carbonated emulsified fuel was injected into a flame stabilized in a laminar counterflow field. Direct photography of the flame using a color high-speed video camera and magnified shadow imaging of spray droplets using a monochrome high-speed video camera were used. As a result, tip position of spray flame became shorter and spray flame was compact when carbonated emulsified fuel was used. This was because dissolved CO_2 enhanced secondary atomization, leading to improvement of fuel vapor ignition at upstream region. Secondary atomization behavior of carbonated emulsified fuel droplet was also observed at upstream region.

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Experiments about change of pipe length, diameter, and combustion quantity under stoichiometric condition were conducted to clarify what kind of influence abrupt pipe expansion has on combustion oscillation in the tubular flame burner. The sound pressure was measured at the tube exit by a microphone. It is found from the experimental results that installation of pipe expansion restrain heat release oscillation including the fundamental frequency of about 400 Hz and enlarge range of stable combustion. But when pipe length is longer than a certain value, combustion oscillation is always generated regardless of combustion quantity and pipe diameter. This is why mutual sound pressure level was amplified by axial mode of columnar resonance wave and heat release oscillation.

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This study investigates the effects of oxygen concentration on combustion instabilities in a laboratory-scale premixed gas-turbine model combustor. We adopt two nonlinear analytical methods based on dynamical systems theory: the color version of recurrence plot and local predictor model for OH chemiluminescence intensity fluctuations inside the combustor. The obtained results clearly show that the dynamical behavior of the OH chemiluminescence intensity fluctuations undergoes a significant transition from chaos to periodic oscillations with increasing oxygen concentration.

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This paper presents an adjoint-based shape optimization method for heat transfer processes involving liquid-solid phase-change phenomena. We have formulated an adjoint-based shape optimization scheme using the enthalpy method. With the present method, the fin shape can be optimized for enhanced solidification process, in which the liquid is solidified through heat conduction. Based on a meshless local Petrov-Galerkin (MLPG) method, the characteristics of the present shape-optimization method have been examined through analyses with different terminal time in the cost functional and the initial fin geometries.

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Cryoconcentration is commonly used in the bio-food industry in order to separate more concentrated phase from the initial solution. We have done experiments to obtain the effective partition coefficient of solution in progressive freezing-concentration by using the directional solidification method. The interface concentration was evaluated from the relation of the freezing-point depression degree to the temperature. The experimental data of sucrose were presented as a function of freezing velocity. It is confirmed that the increase of the heat transfer rate raises the ice progress velocity and decreases the effective partition coefficient.

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Vitrification of high level liquid waste (HLLW) after reprocessing spent fuel from nuclear power stations is one of the most important processes in nuclear fuel cycle in Japan. Numerical simulation was developed to simulate temperature, electrical potential and noble metal elements, which are included in HLLW. Material properties in high-temperature conditions were measured to introduce into the simulation code. The numerical simulations were carried out to compare with the result of mock-up melter test and to plan the mock-up test.

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Phase field model is known to be very powerful in describing the complex pattern formation of the interface in non-equilibrium state, such as growth of dendritic crystals. In this study, the effects of anisotropy of the crystals on Mullins-Sekerka instability in growth of solid-liquid interface were investigated numerically. Given the sign curves at the solid-liquid interface in supercooled state, the growth of the interface was simulated using phase field model. The direction of the anisotropy of the crystals, the intensity of the anisotropy and the surface tension were varied as the parameters, and the conditions at which the amplitude of the curves increases were picked up.

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This study is aimed at clarifying the underlying physics of the surfactant effects on clathrate hydrate crystal growth at the SDS aqueous solution/methane (liquid/gas) interface by method of the visual observations. SDS and methane were used as the surfactant and guest substance, respectively. The crystal morphology was clarified according to the ΔT_<sub>, as index of the driving force for the crystal growth. ΔT_<sub> is defined as difference between the system temperature and the hydrate equilibrium temperature. The crystal growth behavior of SDS aqueous solution/methane system was changed because hydrate crystals were detached from the interface.

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This paper reports three-phase (ice + hydrate + vapor) equilibrium pressure-temperature condition measurement in CO_2 + H_2O system at temperatures below the freezing point of water (199.1 K to 247.1 K). The phase equilibrium pressures measured in the present study are from 34.3 kPa to 406.6 kPa. The measurements were performed using the batch, isochoric method. The results of the present measurements complement the lack of the literature data on the phase equilibrium conditions at the above temperature range results may contribute to understanding of CO_2 hydrate-related environmental issues and technologies below the water freezing temperature such as Martian environment, fire extinguisher and working media of power generation system.

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We report the preservation of CO_2 clathrate hydrate in the samples coexisting with trehalose. The samples having 1.0 mm and 5.6-8.0 mm diameter were prepared from trehalose aqueous solution of 0.05 or 0.10 mass fractions and stored at 243.2 K and 253.2 K for three weeks. The preservation for 5.6-8.0 mm diameter samples was better than that for 1.0 mm diameter samples. The preservation with trehalose was superior to that with sucrose and comparable to that without sugars. It is inferred that existence of aqueous solution in the samples is a significant factor of the preservation in the presence of sugar.

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The purpose of this study is to develop a new process for making silicon plate of less than 100 μm. Silicon plate of less than 100μm will become flexible and be utilized for flexible solar panels. Although experiments with high-temperature molten silicon were difficult to do in our laboratory, we performed model experiments with low melting point metal. In the experiment, we attempted to solidify a metal plate less than 100 μm utilizing surface tension of the molten metal. Moreover, we attempted to apply gas flow, as external force, to the molten part before solidification to make the plate thinner. As a result, we successfully obtained metal plate of thickness of 120 μm. However, plate width became narrower than expected. We need to improve the method for keeping the plate width constant while the whole process.

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The efficient utilization of solar energy is important issue to shift to a sustainable society. However, the solar radiation in infrared band is not converted into electric energy efficiently, and the electric power generation during nighttime is difficult. In this study, the solar energy harvesting by utilizing thermoelectric generator with phase change material (PCM) has been investigated. Experiments were performed using octadecane as PCM. As the results, electric power generation by solar radiation during daytime, and electric generation during nighttime by solar heat energy stored in PCM were achieved. The harvested energy and melting-solidification behavior of PCM were discussed in relation to ambient temperature for typical three weather seasons.

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This paper presents the effect of convection flow on melting behavior of a water-insoluble material immersed in water. A rectangular n-hexadecane block as a water-insoluble material is placed vertically in the water. Then the shape of the melting block and its melting rate are recorded via photography. The velocity of the water in the test vessel is measured by using PIV. The local heat transfer coefficient of the block is defined based on the melting rate. From the result of this experiment, it is found that the local heat transfer coefficient increases as time elapses, because the effect of hindering melting of the melting liquid flow along the block gets weaker.

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Ice adhesion to a cooling solid surface often causes a major accident, while, recently, stronger adhesion force of ice is positively used to fix a workpiece. Therefore, it is necessary to control an ice adhesion force to the cooling solid surface. One of the authors clarified that a thin film made from a silane-coupler coated on the solid surface was effective to control the ice adhesion force. In this paper, for two kinds of silane-couplers, influence of test plates' materials on characteristics of film formation such as a thin film thickness was investigated, varying immersion times of the test plate to the water and silane-couple solution, after which ice adhesion forces are measured.

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The development of icephobic surfaces is an important issue in recent years. We have created a new functional surface for lowering the freezing temperature of a water droplet by adhering polypeptides on the surface. These polypeptides are based on the part of winter flounder antifreeze protein. To examine the effectiveness of the surface, we conducted simultaneous measurements of water droplet temperature on the cooling surface with a fine thermocouple and solidification of the droplet with a microscope. Although there is no change in the coagulation of water droplet, we obtained the depression of freezing temperature due to the surface.

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The aim of this study is to clarify the effects of addition of polypeptides on the melting of ice particles in ice slurry flow in mini-channels. The polypeptides are a part of winter flounder antifreeze protein. We captured the images of ice particles and ice-particle clusters. We measured the dimensions and velocities for the ice particle (clusters) from the images. It was found that the melting of ice particle (clusters) in the case with the polypeptides was more gradual than that without the polypeptides. Furthermore, the velocity of ice particle clusters was found to be lower than that without the polypeptides.

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The purpose of the study is experimental investigation about measurement error of heat flux by deflection effect in interferometric temperature imaging method. Distortion of the image taken by same lens-camera system as the previous interferometry through water with a temperature gradient was tested. The displacement in the image was 4-24μm with large scatter, and showed a similar tendency to a theoretical expectation. The deflection effect will be confirmed quantitatively and improvement method of the laser interferometer will be studied.

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A non-intrusive ion concentration and temperature measurement technique was developed by spontaneous Raman imaging. Various concentrations of electrolyte solutions were used as samples. The concentration was obtained from a calibration curve depicting the correlation between the Raman intensity and concentration, which was observed by the Raman spectra obtained by employing a 488-nm CW laser and a spectrometer. On the other hand, the Raman scattering from water was focused on for the temperature measurement, and temperature was measured by using the Raman intensity dependencies on water-related Raman band. By applying these calibration curves, a spatial distributions measurement of ion concentration and temperature was realized by the spontaneous Raman imaging.

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A method that can measure the fluid temperature in microscopic scale by measuring the fluorescence polarization is described in this study. To understand the basic characteristics and advantage of the method, the effects of the fluid temperature, fluid viscosity, measurement time, and pH of the solution on the measured fluorescence polarization degree are discussed. The results showed that fluorescence polarization is considerably less sensible to the measurement time and pH compared to the fluorescence intensity demonstrating the stability of the temperature measurement. The correlations between the fluid temperature and the inverse value of P measured by two photo detectors (photomultiplier and CCD camera) both showed a linear relationship. This agreed with the theoretical characteristic, and confirmed the feasibility of this method.

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In this study, we propose a temperature measurement method that uses ultra-fine fluorescent wires. This is possible because its structure is simple, and any material can be used for the wire. Hence, ultra-fine wires whose Reynolds number is less than 1.0 can be selected. This means that turbulent flow is not generated downstream of the wire and that its wake is negligibly small. Fluorescent paint (containing Rhodamine B) was coated on the surface of the wires. The test volume was illuminated by using UV lights. The paint emits a very tiny orange-colored fluorescent light whose intensity changes with the temperature of the atmosphere. A very high sensitivity color camera (Nikon D7100, ISO 25600, 14 bit, 6,000×4,000 pixels) was used to record the visualized image.

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This paper describes the investigation of molecular diffusion at liquid-solid interface by visualizing the concentration distributions of two-liquids mixed in microscale. Imaging of the concentration distributions was achieved by measuring the Raman intensity excited by the evanescent wave generated at liquid-solid interface. In the calibration experiment, it is confirmed that the linear relationship between the concentration and the intensity of Raman scattering was obtained. In the further experiment, D_2O and H_2O will be mixed in T-shaped microchannel. Imaging of the concentration distributions in the mixing field will be performed by using the calibration curves.

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Simple and easy evanescent wave generating device "Evanescent Wave for a Chip" (EvaChip) was developed. The purpose of this study is to measure pH distribution and velocimetry vector map of flow in the vicinity of liquid-solid interface by using 3CCD camera. Nano-PIV and nano-LIF were carried out by using particles and dye with different emission wavelength, respectively. EvaChip was improved to measure with high SN ratio so as to measure in both methods. Based on the results, in order to investigate the effect of thermofluid phenomena to the chemical reaction, simultaneous measurement will be carried out by using EvaChip.

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In order to understand the details of the micro- and nano- motions, it is necessary to measure the three-dimensional velocity under a microscopy. Thus, the development of a new 3-D measuring technique by a single camera is strongly needed. Presently, the Doppler phase-shifting holography has been used for the measurement of a micro object. This method extracts the signal of a fixed frequency caused by the Doppler beat between the object light and the reference light. The longitudinal velocity of an object can be measured by its beat frequency. In this study, a holography of a micro object has been observed with expanding optics.

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Biosensors are important measurement tools for diagnosis and drug discovery. Especially in drug-discovery processes, high-throughput biosensors are required because of many drug candidates. Then we developed a new concept high-throughput biosensor using picosecond ultrasound method. A metal microdot is irradiated with ultrashort optical pulse, where ultrahigh-frequency phonons are excited. They are transferred into the solution across the proteins captured on the microdot, leading to the phonon intensity change. We observe this phenomenon using a time-resolved pump-probe method. We can detect 67 pM rabbit IgG using reflective change caused by phonon intensity change due to protein coupling onto the sensor chip. In addition, we achieved detection of difference between specific binding and non-specific binding using multi-channel microdots. And we developed theoretical calculation for this measurement principle. In this study, Our new concept biosensor can be a powerful tool as a large-scale multichannel biosensor.

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This study describes development of non-intrusive measurement of CO_2 concentration by using coherent anti-Stokes Raman scattering (CARS) considering non-resonant background noise from channel wall. In order to suppress the influence of non-resonant background noise on measured values, beam diameter conversion was employed for measurement of CO_2 concentration. The relationship between CO_2 concentration and CARS intensity generated from CO_2 was obtained. The effect of background noise suppression was investigated by comparing the ratio of CARS to non-resonant noise of beam whose diameter is 5 mm, 7 mm and 10 mm.

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Polarization-CARS (coherent anti-Stokes Raman scattering) system was developed in order to eliminate non-resonant back ground noise, and in order to enhance characteristics of CARS such as high sensitivity, non-intrusiveness, and chemically specific measurement. Two experiments were performed for comparison between CARS and polarization-CARS. The relationships between intensity of scattering light and concentration of Na_2SO_4 solution were obtained and solution mixing field was measured. Polarization-CARS reduced the errors observed in the case of the experiments using CARS at the same conditions. As a result, it was observed that polarization-CARS has an ability to eliminate non-resonant back ground noise.

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This paper focuses on the mixing phenomena at the neutralization reaction interface in a microchannel. Visualization of diffusion and chemical reaction of the aqueous solutions of hydrochloric acid and sodium hydroxide in microchannel is performed by using a novel imaging technique based on the near-infrared absorption spectroscopy of aqueous solutions. We observe the salt generation and diffusion by the reaction when the flow of the two reagents and gravitational directions are changed. The results show that salt diffusion phenomena are greatly influenced by gravitational direction.

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