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Improvement of redox reaction kinetics is important for the application of metal oxide redox reactions in energy conversion systems such as chemical looping systems and hydrogen storage. In this study, we focused on physical properties in supports that can affect the redox reaction kinetics of metal oxides. The redox reaction of iron oxide by hydrogen and water vapor was studied with various support materials, ZrO 2 , CeO 2 , yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC), which have different physical properties such as oxide ion and electronic conductivities. Oxide ion conductors such as YSZ and GDC clearly increased the rate of Fe 2 O 3 reduction (Fe 2 O 3 →Fe 3 O 4 →FeO→Fe). This result suggests that oxygen vacancies and good oxide ion transport properties in the supports may enhance removal of oxygen from iron oxide. In addition, CeO 2 and GDC significantly improved the reduction kinetics in the reduction step from FeO to Fe. Furthermore, it was found that these supports have an effect on the oxidation reaction kinetics of iron by water vapor in comparison with ZrO 2 ; that is, they increase the rate of the steam-iron reaction for hydrogen production. The mechanism of the improvement was discussed in terms of oxide ion and electronic conductivity in the supports and water dissociation on the support surfaces. [ABSTRACT FROM AUTHOR]

Abstract: To investigate the degradation of the touchpad usability by surface wear, the touchpad with new, worn, plastics and paper surfaces are examined in terms of performance and frictional response. It is found that the friction coefficient of the surface affect the usability. It is concluded that the major factors controlling the friction was surface roughness. It is also found that friction coefficient is affected by the difficulty of the task. The reasons for this is the human tendency to be cautious, he/she try to reduce the load to be precise. Then the load dependence of friction coefficient results in high friction. The other reason is mental sweating, which will be increased when the task is difficult. [Copyright &y& Elsevier]

Abstract: Low temperature pyrolysis and gasification has been investigated based on the chemical looping combustion (CLC), where insufficient amount of lattice oxygen was reacted with hydrocarbons. Metal oxides such as nickel oxide, iron oxide and titanium oxide were used as lattice oxygen source and were coated on silica gel or porous aluminum. Single column reactor was used for experiments and 36.1mmol of polyethylene was dropped to the column whose temperature was ranged from 693 to 1073K. For the pyrolysis, hydrogen yield was 100% of polyethylene contained hydrogen, while methane, CO and CO2 were minor products and almost half of the supplied carbon was deposited on the particle surface. On the other hand, for the steam gasification, 2–3mol of the hydrogen was generated from 1mol of carbon and almost no carbon deposition was observed. It is found that no wax and heavy tar was observed in the exhaust. Therefore, the lattice oxygen was able to be applied to the low temperature gasification of hydrocarbons. [Copyright &y& Elsevier]

This paper considers a vehicle-borne target detection system for short range in which an UWB (Ultra Wideband) impulse radar is used. The UWB impulse radar uses a pulse with widths of less than nanosecond order. Therefore, many multipath returns are observed on the receiving side. An IPCP (Inter-Period Correction Processing) receiver that resolves complexity of the receiver caused by multiple paths has been proposed. However, the integration time of the correlator in the IPCP receiver is limited by the period of the transmission signal (code length) and affects the range measurement accuracy. This paper considers vehicle mounting for applications. In order to assure safety, a receiver is constructed with several IPCP receivers in parallel, so that the range measurement accuracy is improved. In addition, a receiver which reduces the complexity of threshold setting in the conventional IPCP receiver when several targets are detected is proposed. The outputs of these receivers are derived analytically and improvement of the range measurement accuracy is confirmed. Further, based on the analytical results, the output of each receiver is characterized and the relationship of the threshold, detection probability, and false error probability is derived. Finally, the characteristics of use of the receiver as a vehicle-mounted radar are evaluated by simulation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(7): 1–14, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20303 [ABSTRACT FROM AUTHOR]

Abstract: A circulating fluidized bed (CFB) system of photocatalyst is studied toward successive treatment of large amount of gas such as tunnel exhaust. The experimental system is 2 m high. A riser of the CFB is concentric double-pipe structure. A light source is installed inside the inner pipe. Silica gel powder coated with titanium dioxide by the sol–gel method provides composite particles of the photocatalyst. Average size of composites is 203 μm. Composite particles are fluidized and carried upward in the annulus area sandwiched between the inner and outer pipes. An endurance test of a photocatalyst composite is carried out for attrition using the CFB for long time operation. An observation by SEM–EDX revealed that a part of photocatalysts on the surface of the composites falls off at the initial stage of the solid circulation and others adhere to the composites tightly. In addition, the photocatalytic removal of NO x is also studied by measuring NO and NO2 concentration. The NO x removal efficiency depends on the solids volume fraction of photocatalyst composites in the riser of the CFB. The mechanism of the NO x removal by the photocatalyst composite in the CFB is thought to be divided into oxidation and adsorption processes. The adsorption process is regarded as more important than the oxidation processes in this experimental system. [Copyright &y& Elsevier]

IEEE 802.15.7 Visible Light Communication (VLC) networks suffer from performance degradation caused by the hidden device collisions due to the directional transmission with narrow beamwidth. One of the solutions for mitigating the hidden device collisions is to employ a full-duplex transmission technique. As a side effect of the full-duplex transmission in the VLC networks, however, the data-packet discard due to the retransmission limitation occurs frequently in the networks. This paper proposes an improved backoff scheme and its performance analysis to suppress the packet discard. The proposed backoff scheme increases the Backoff Exponent (BE) and the Number of Backoff stage (NB) in IEEE 802.15.7 only when the data packet transmission fails. To evaluate the system performance theoretically, this paper also provides the Markov-chain model for channel access with the proposed scheme. The performance evaluations through simulation and theoretical analysis show the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Abstract: NiO redox processes and hydrogen production from dry and humidified methane were investigated by chemical looping combustion (CLC) and chemical looping reforming (CLR) using NiO as an oxygen carrier. To achieve a lower operating temperature in the NiO reduction process, oxide ion conductors such as gadolinia doped ceria (GDC) and strontium doped lanthanum aluminate (LSA) were investigated as the support materials of NiO. Hydrogen rich gas products were obtained by the CLC and CLR processes but a prolonged induction period for the NiO reduction by methane (i.e., induction period for CO2 formation from methane) was observed at relatively low operating temperatures in both processes. NiO/GDC and NiO/LSA lead to a decrease in the induction period of NiO reduction by comparison with the reference NiO/ZrO2. Upon repeating the NiO reduction–oxidation cycles, we also found that the induction period for NiO/GDC became shorter with an increase in the redox cycle number. However, for NiO/LSA this time became longer, which may result from the strong interaction between Ni and the support materials. This NiO reduction behavior on the oxide ion conductors is discussed together with the autocatalytic reaction mechanism for NiO reduction, which provides new insights into the efficient use of lattice oxygen in CLC and CLR. [Copyright &y& Elsevier]

Abstract: The catalytic performance of cermets made of 10% nickel or nickel oxide supported on YSZ (yttria-stabilized zirconia) for chemical looping combustion (CLC) and steam reforming (SR) of methane at 700°C is investigated. Steam reforming of methane over the reduced catalyst resulted in a syngas containing more than 70% hydrogen and about 15% carbon monoxide. Chemical looping combustion of methane with insufficient lattice oxygen could potentially lead to 40–65% hydrogen rich gas products. Prolonged induction period (e.g. 30–80min) in reduction of nickel oxide by methane has been observed in the presence of steam. The span of induction period increases by increasing steam partial pressure. It is hypothesized that the delayed reduction of nickel oxide is related to the retarding effect of steam on autocatalytic reactions of methane and hydrogen with lattice oxygen of nickel oxide and the subsequent reforming reactions. [Copyright &y& Elsevier]

Abstract: Near-critical water gasification (NCWG) and steam reforming (SR) were investigated for the production of hydrogen from a biomass model compound (glucose) using fixed bed tubular reactor. Ruthenium/carbon and nickel/yttria stabilized zirconia (YSZ) were utilized to enhance the reaction rates of the two processes for NCWG and SR, respectively. NCWG experiments were performed at 200bar and 360–450°C, while SR experiments were conducted at 500–800°C and atmospheric pressure. Although in both cases complete carbon gasification is achieved, gas composition, hydrogen selectivity and overall energy efficiency show strong dependencies on the type of process itself and the associated operating conditions. It is shown that operating the reforming reaction of glucose at high pressures and low temperatures (NCWG) results in a significant amount of methane and trace amounts of carbon monoxide. In contrast, gasification of glucose at atmospheric pressures and high temperatures (SR) leads to a methane-free gas stream that contains few percents of carbon monoxide. Considering energy recovery and neglecting the heat losses, the maximum cold gas efficiency of the NCWG and SR reached 78% and 91%, respectively. The features of the two catalytic reaction processes are discussed in terms of the experiments and process simulations. [Copyright &y& Elsevier]

A new innovative hydrogen-production method, HyPr-RING (hydrogen production by reaction-integrated novel gasification), using hydrocarbon and water has been proposed. Experimental results show that, using one reactor, 1 mol of carbon generates 2 mol of hydrogen with no pollutants and no carbon oxides being detected in the product gas phase. Water reduction by the hydrocarbons and the CO2 absorption reaction are the key reactions in this method. The absorption of CO2 from the gas phase improves the yield of hydrogen production from water.A feasible hydrogen production process was designed by applying the above-mentioned method, and the thermodynamic efficiency was calculated accordingly. Theoretically, the calculated cold-gas efficiency of this process exceeds 90%, and no clean-up system is required. This process potentially reduces hydrogen production costs compared to conventional hydrogen production methods. [Copyright &y& Elsevier]

This paper gives an overview of the last 100 years of fluidization in the Japanese context. Japan was a relatively early adopter of the Winkler coal gasification technology in industry and an early participator in the formation of chemical engineering initiated in the United Kingdom and the United States. However, it was left far behind in the rapid development of fluidized catalytic cracking (FCC) technology in the worsening international relations of the 1930s. Academic research on fluidization and its applications, which had started with the development of FCC, did not start substantially in Japan until 1952, when the San Francisco Peace Treaty came into effect. In this paper, first reviewed is the global progress of chemical engineering and fluidization research, and further discussed is the three-stage scheme in the development of the knowledge of fluidization. Taking these as the background, we review first the pre-war and early post-war research situations, then, the formation of the fluidization community in Japan. Finally, the fully-fledged post-war research and technological developments with a brief look at the Japanese contribution to the above-mentioned global progress are reviewed regarding the three fields: energy-environment applications, catalytic reactors and numerical simulation. [Display omitted] • A review of 100 years' footsteps of Japanese chemical engineers. • Three-stage epistemological development of knowledge on fluidization. • Post war development of fluidization engineering both in academia and industry. • Fluidized-bed energy/environment and catalyst processes in Japan. • DEM-CFD model developments for fluidized bed simulation. [ABSTRACT FROM AUTHOR]

Abstract: The flow behaviors in the downer of a large-scale triple-bed circulating fluidized bed (TBCFB) gasifier cold model, which is composed of a downer (Φ 0.1m×6.5m), a bubbling fluidized bed (BFB, 0.75×0.27×3.4m3), a riser (Φ 0.1m×16.6m) and a gas-sealing bed (GSB, Φ 0.158m×5m), were investigated. Sand particles with a density of 2600kg/m3 and an average particle size of 128μm were used as bed materials. Solids mass fluxes were in the range 113–524kg/m2 s. Average solids holdup in the developed region of the downer increased with increasing solids mass flux. The gas seal between the riser and the downer had a large effect on the solids holdup distribution in the downer. Compared with the solids holdup in the riser, a relatively low solids holdup was formed in the downer even at high solids loadings. A pressure balance model was set up to predict the solids mass flux for this TBCFB system. It was found that the static bed height in the GSB had a great effect on the solids mass flux. The possibilities of achieving a high density solids holdup in a downer were discussed. [Copyright &y& Elsevier]

Abstract: A novel large-scale triple-bed combined circulating fluidized bed (TBCFB), consisting of a riser (16.6m in height, 0.10m inner diameter), a downer (6.5m in height, 0.10m inner diameter) and a bubbling fluidized bed (BFB; 0.27 × 0.75 × 3.4m3), was constructed as a cold model for a gasifier. The purpose of the new reactor design was to achieve a high solids mass flux which is required for exergy recuperative steam gasification of coal/biomass. In the TBCFB, a gas-sealing bed (GSB; 5.0m in height, 0.158m inner diameter) was installed between the BFB and the riser bottom to increase the pressure head to transport solids to the riser. The hydrodynamic behavior of silica sand particles (arithmetic mean diameter is 128μm) was investigated by independently controlling the flow rates of air in the riser, downer, BFB and GSB, and varying the bed heights of the BFB (H BFB) and GSB (H GSB) under ambient conditions. When the GSB gas velocity (U gg) was 0.10m/s, the solids mass flux (G s: kg/(m2 s)) substantially increased with increase in riser gas velocity (U gr). The maximum G s obtained was 546kg/(m2 s) at U gr =12m/s and H GSB =4.6m. This is due to the fact that the pressure head for transport of solids to the riser bottom increased sufficiently by increase in the GSB height. From the solids holdup (ε s) obtained from the apparent pressure difference, a dense phase (solids holdups: 0.070–0.095) was found to be formed at the bottom part of the riser (H r ≤5m). The flow in the downer was developed in 1.5m. The solids holdup in the developed area of the downer decreased from 0.0212 to 0.0128 as the downer gas velocity (U gd) increased from 0 to 1m/s when G s was 406kg/(m2 s). [Copyright &y& Elsevier]

Abstract: Integration of coal gasification and CO2 separation reactions in one reactor may produce a high concentration of hydrogen. To design a reactor for this new reaction system, it is necessary to know all reaction behaviors in the integrated reaction system. In our previous study, we performed a continuous reaction experiment of coal/CaO under high steam pressure and confirmed that H2 concentration higher than 80vol% with little CH4 was produced; and that almost all CO2 was fixed by adding CaO. In this study, the behaviors of solid products during the continuous experiment were investigated. It was found that, CaO first reacted with high-pressure steam to form Ca(OH)2 (hydration), then the Ca(OH)2 absorbed the CO2 generated by coal gasification to form CaCO3. The hydration of CaO restored sorbent reactivity. Eutectic melting of Ca(OH)2/CaCO3 was found to occur in the experiment at 973K, and this eutectic melting led to the growth of large particles of solid materials. However, at the relatively low temperature of 923K, eutectic melting could be avoided. Carbon conversion of the coal in the continuous reaction of the coal/CaO mixture with steam was high as 60–80%, even at the lower temperature of 923K. [Copyright &y& Elsevier]

Abstract: Hydrocarbon can be gasified with steam into fuel gas, including CO, CO2, H2, CH4, etc. For H2 production, it is necessary to separate the other gases from hydrogen. In this study, hydrogen production by removal of carbon oxides during hydrocarbon gasification with CaO and other metal oxides was examined theoretically and experimentally. It was experimentally confirmed that when the hydrocarbon, water, and Ca(OH)2 were set in a micro-autoclave at a temperature of 973K and a pressure of 25MPa, the only gas products were hydrogen along with a small amount of methane. CO was converted to CO2, and CO2 was absorbed by Ca(OH)2 to form CaCO3 completely. CaOSiO2 can absorb CO2 to form CaCO3 under the same experimental conditions. Others such as MgO, SnO, and Fe2O3 were found to be unsuitable sorbents for CO2 absorption in the gasifier at high temperature. By calcination, CaCO3 can reform to CaO. Because the chemical energy contained in CaO can be released during hydrocarbon gasification, H2 production efficiency as high as 70–80% can be expected. [Copyright &y& Elsevier]

Abstract: Hydrogen production by the reaction integrated novel gasification (HyPr-RING) method was first proposed in 1999. This method involves the reactions of coal and CaO with H2O, that is, a combination of exothermic and endothermic, gas production and gas separation reactions, in a gasifier to produce H2. The equipment for the HyPr-RING process consists mainly of a gasifier, a sorbent regenerator, and several heat exchangers. In this study, the process components and their mass and energy balances were analyzed by thermodynamic calculations. A fuel gas comprising an equilibrium mixture of 91% H2 and 9% CH4 can be obtained by gasification of coal at 923 K and 3.0 MPa. The amount of fuel gas produced was calculated to be equivalent to 1.4 Nm3/kgcoal, giving a high cold gas efficiency of 0.77. The equilibrium H2 and CH4 compositions are sensitive to the amount of steam contained in the product gas. The energy contained in the coal is used in the gasifier and the regenerator in a ratio of about 3/2. This gives a good energy balance and a high cold gas efficiency for the process. [Copyright &y& Elsevier]

Abstract: In production from woody biomass by steam gasification using CaO as a sorbent, the effect of reaction parameters such as the molar ratio of CaO to carbon in the woody biomass , reaction pressure, and reaction temperature was investigated on yield and conversion to gas. In the absence of CaO, the product gas contained . On the other hand, in the presence of CaO (, and 4), no was detected in the product gas. At a of 2, the maximum yield of was obtained. The yield and conversion to gas were largely dependent on the reaction pressure, and exhibited the maximum value at . It is noteworthy that was obtained from woody biomass at a much lower pressure compared to other carbonaceous materials such as coal and heavy oil in steam gasification using a sorbent. yield increased with increasing reaction temperature. Woody biomass is the one of the most appropriate carbonaceous materials in production by steam gasification using CaO as a CO2 sorbent, taking the reaction pressure into account. [Copyright &y& Elsevier]

Steam gasification employing a CO2 absorbent was investigated using epoxy resin under high-temperature and -pressure conditions: 873 through 973 K, and 1 through 10 MPa. A newly designed drop tube reactor was introduced in order to achieve a rapid increase in sample temperature to simulate the initial stage of continuous reaction. Hydrogen generation was accelerated effectively with an addition of calcium hydroxide as a carbon dioxide absorbent, with efficiency of calcium utilization becoming higher under the higher pressure condition. Methane generation at the initial reaction step was suppressed by the addition of calcium to the drop tube reactor, while much methane was obtained in an autoclave-type reactor whose rate of temperature increase was small. [Copyright &y& Elsevier]

Coal/CaO powder mixtures were continuously supplied into a reactor to react with steam at high pressure and high temperature. At 923 K and 5.0 MPa, the gas produced from the reaction of Taiheiyo coal/CaO with steam consisted of mainly H2, with smaller amounts of CH4, C2H4, C2H6 and CO2. Increasing the pressure enhanced H2 production and CH4 decomposition. Above 3 MPa, the gas from the reaction contained <3% CO and CO2. Under high pressure, CaO reacted with steam to form Ca(OH)2 which absorbed CO2. The H2/CH4 ratio in the product gases from three different rank coals (Datong coal (bituminous), Taiheiyo coal (sub-bituminous), Wyoming coal (lignite) followed the order Datong>Taiheiyo>Wyoming. The Wyoming and Datong coals produced less H2 than the Taiheiyo coal. [Copyright &y& Elsevier]

Pulverized Taiheiyo coal (Japanese subbituminous coal) was gasified with steam in the presence of CO2 sorbent (Ca(OH)2) under relatively high pressure (approximately 20 MPa; subcritical condition) using a tubing-bomb microreactor (TB reactor). The transient characteristics in the conversion of coal and the formation of gaseous products during the gasification were investigated. During initial heating period, 40–50 wt.% of the coal initially loaded was rapidly converted to gas or tar. In the presence of Ca(OH)2, the yield of gaseous products was apparently increased owing to the catalytic effects of Ca(OH)2 on coal gasification. No CO2 was observed in the produced gas at any soaking time in the gasification with Ca(OH)2, suggesting that CO2 sorption by Ca(OH)2 took place effectively under high-pressure conditions. A rigid agglomeration of char and CO2 sorbent was observed at relatively high temperature, which is attributed to the formation of melts of the CO2 sorbent. [Copyright &y& Elsevier]

Hydrogen generation during the reaction of a coal/CaO mixture with high pressure steam was investigated using a flow-type reactor. Coal, CaO and CO reactions with steam, and CO2 absorption by Ca(OH)2 or CaO occurred simultaneously in the experiment. It was found that H2 was the primary resultant gas, comprising about 85% of the reaction products. CO2 was fixed into CaCO3 and CO was completely converted to H2. Pyrolysis of the coal/CaO mixture carried out in N2 was also examined. The pyrolysis gases were compared with gases produced by general coal pyrolysis. While general coal pyrolysis produced about 14.7% H2, 50.5% CH4, 12.0% CO and 12.0% CO2, the gases produced from coal/CaO mixture pyrolysis were 84.8% H2, 9.6% CH4, 1.6% CO2 and 1.1% CO. [Copyright &y& Elsevier]