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The insulator-to-metal phase transition from VO2(M1) to VO2(R) results in extensive improvements in electrocatalytic activity for both the OER and the HER.

Solar fuel generation mediated by semiconductor heterostructures represents a promising strategy for sustainable energy conversion and storage. The design of semiconductor heterostructures for photocatalytic energy conversion requires the separation of photogenerated charge carriers in real space and their delivery to active catalytic sites at the appropriate overpotentials to initiate redox reactions. Operation of the desired sequence of light harvesting, charge separation, and charge transport events within heterostructures is governed by the thermodynamic energy offsets of the two components and their photoexcited charge-transfer reactivity, which determine the extent to which desirable processes can outcompete unproductive recombination channels. Here, we map energetic offsets and track the dynamics of electron transfer in MoS2/CdS architectures, prepared by interfacing two-dimensional MoS2 nanosheets with CdS quantum dots (QDs), and correlate the observed charge separation to photocatalytic activity in the hydrogen evolution reaction. The energetic offsets between MoS2 and CdS have been determined using hard and soft X-ray photoemission spectroscopy (XPS) in conjunction with density functional theory. A staggered type-II interface is observed, which facilitates electron and hole separation across the interface. Transient absorption spectroscopy measurements demonstrate ultrafast electron injection occurring within sub-5 ps from CdS QDs to MoS2, allowing for creation of a long-lived charge-separated state. The increase of electron concentration in MoS2 is evidenced with the aid of spectroelectrochemical measurements and by identifying the distinctive signatures of electron-phonon scattering in picosecond-resolution transient absorption spectra. Ultrafast charge separation across the type-II interface of MoS2/CdS heterostructures enables a high Faradaic efficiency of ∼99.4 ± 1.2% to be achieved in the hydrogen evolution reaction (HER) and provides a 40-fold increase in the photocatalytic activity of dispersed photocatalysts for H2 generation. The accurate mapping of thermodynamic driving forces and dynamics of charge transfer in these heterostructures suggests a means of engineering ultrafast electron transfer and effective charge separation to design viable photocatalytic architectures.

A MnV2O6/graphene nanocomposite was fabricated through hydrothermal synthesis and high energy milling to introduce it as an efficient OER electrocatalyst. The MnV2O6/graphene nanocomposite with 20 wt% graphene exhibited superior electrocatalytic OER performance with a low overpotential and high stability and durability in 1 M KOH aqueous solution, exhibiting even after 1000 CV cycles.

Herein, we report high electrocatalytic activity of monoclinic VO

The gas response characteristic toward C2H5OH has been demonstrated in terms of copper-vacancy concentration, hole density, and microstructural factors for undoped/Li(I)-doped CuO thin films prepared by sol-gel method. For the films, both concentrations of intrinsic copper vacancies and electronic holes decrease with increasing calcination temperature from 400 to 500 to 600 oC. Li(I) doping into CuO leads to the reduction of copper-vacancy concentration and the enhancement of hole density. The increase of calcination temperature or Li(I) doping concentration in the film increases both optical band gap energy and Cu2p binding energy, which are characterized by UV-vis-NIR and X-ray photoelectron spectroscopy, respectively. The overall hole density of the film is determined by the offset effect of intrinsic and extrinsic hole densities, which depend on the calcination temperature and the Li(I) doping amount, respectively. The apparent resistance of the film is determined by the concentration of the structural defects such as copper vacancies, Li(I) dopants, and grain boundaries, as well as by the hole density. As a result, it is found that the gas response value of the film sensor is directly proportional to the apparent sensor resistance.

A MnV2O6/graphene nanocomposite was fabricated through hydrothermal synthesis and high energy milling to introduce it as an efficient OER electrocatalyst. The MnV2O6/graphene nanocomposite with 20 wt% graphene exhibited superior electrocatalytic OER performance with a low overpotential and high stability and durability in 1 M KOH aqueous solution, exhibiting even after 1000 CV cycles.

Exploring the novel semiconductor-type gas sensors based on complex oxides beyond binary oxides extends the degrees of freedom in chemical sensor research with structural and compositional versatility. In particular, such complex oxides have been reported to exhibit characteristic and promising gas sensing properties, which are mediated by chemical defects. In this work, CuBi2O4 has been prepared in the form of porous nanoparticulate thin film with high surface area-to-volume ratio and small amount of defect (Cu+−oxygen vacancy (VO ) complex) by the simple solution process based on metal-organic decomposition (MOD). The film exhibited high gas responses with the specific values of 10.8 toward C2H5OH, 4.2 toward H2, and 2.2 toward CO when measured with 1000 ppm at 400 °C. The particularly high H2S responses (4.7 with 1 ppm, 5.9 with 2 ppm, and 7.4 with 5 ppm) were obtained at 400 °C by the oxidation of H2S on the CuBi2O4 surface. Upon exposure to the oxidizing NO2 gas with low concentrations (≤5 ppm), the resistance of CuBi2O4 thin film sensor was uncommonly increased.

Multicomponent oxides can be extensively explored as alternative gas-sensing materials to binary oxides with their structural and compositional versatilities. In this work, the gas-sensing properties of CuBi2O4 have been investigated toward various reducing gases (C2H5OH, NH3, H2, CO, and H2S) and oxidizing gas (NO2) for the first time. For this, the powder synthesis has been developed using the polymerized complex method (Pechini method) to obtain a single-phase polycrystalline CuBi2O4. The defect, optical, and electronic properties in the prepared CuBi2O4 powder were modulated by varying the calcination temperature from 500 to 700 °C. Noticeably, a high concentration of Cu+–oxygen vacancy (VO•) defect complexes and isolated Cu2+ ion clusters was found in the 500 °C-calcined CuBi2O4, where they were removed through air calcination at higher temperatures (up to 700 °C) while making the compound more stoichiometric. The change in the intrinsic defect concentration with the calcination temperature led to th...

The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe2O4. The electrocatalytic activity of CoFe2O4 for the oxygen evolution reaction (OER) of electrochemical water splitting is investigated as a function of calcination temperature in the range between 300 and 450 °C. It is significantly found that a drastic cation redistribution in octahedral and tetrahedral sites within the spinel structure of 450 °C-calcinated CoFe2O4 p-type semiconductor leads to the dramatic enhancement in hole density and concomitant OER activity. The CoFe2O4 integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance, including an overpotential (η10) of 359 mV at10 mA cm−2 and a Tafel slope of 53.8 mV dec−1 in 1 M KOH aqueous solution. Based on this work, a design principle of the MOD solution process developed can be applied to preparation of a greater variety of compounds. Also, elucidation of structure-OER activity relationships in spinel-type CoFe2O4 electrocatalysts will be able to advance further.

The p-type CuO hollow sphere films doped with aliovalent Li(I) or Fe(III) have been prepared directly on the substrate through a self-organization process in the printed films using the formulated cationic complex inks. The Li(I) or Fe(III) ions are substitutionally incorporated into CuO lattice with the variation in lattice parameters and act as a shallow acceptor or donor leading to the increase or decrease of the hole density, respectively. Such an electronic modification shifts the optical band gap and binding energy of Cu. The increased hole density by Li(I) doping reduces the overall sensor resistance and the width of hole-accumulation layer (λd) in CuO grains, resulting in the decrease in gas response toward the reducing ethanol gas to ca. 50% compared to that of undoped CuO. In contrast, the decreased hole density by Fe(III) doping increases the sensor resistance and λd, leading to the enhancement in gas response to ca. 150%, based on the electronic sensitization mechanism. These results show clearly that the substitutional doping of aliovalent cation is effective for the manipulation of electronic structure and gas sensing properties of p-type CuO.

The flux-mediated one-pot solution process based on the metal-organic decomposition (MOD) has been developed for the preparation of p-type complex oxide semiconductor CuBi 2 O 4 thin films. The precursor solutions with the various concentrations (0.5, 2, 5, and 10 mol% vs. CuBi 2 O 4 ) of aliovalent Li(I) flux produced the continuous and dense CuBi 2 O 4 thin films with stoichiometric composition by facilitating the crystallization from the liquid precursor solution. These films showed the high hole density and charge transfer characteristics, which lead to the high photoelectrochemical activity for water reduction.

The discovery and deployment of earth-abundant electrocatalysts for hydrogen evolution is central to the use of molecular hydrogen as a viable fuel. The edges of molybdenum sulfide are able to mediate proton adsorption and dihydrogen formation at relatively low overpotentials in acidic media. From a practical perspective, an optimal electrocatalyst must combine electrode level efficiency (reflected by high current densities and low Tafel slopes and overpotentials) with high intrinsic catalytic activity (measured by turnover frequency). Herein, we map both sets of parameters for molybdenum sulfide catalysts as a function of the annealing temperature across their amorphous to crystalline phase transition. Studies of local structure indicate that with increasing annealing temperature, molecular precursors are initially cross-linked to form [Mo3S13]2− clusters characterized by both apical/bridging S22− and unsaturated/terminal S22− moieties, which in turn are consumed to nucleate ultra-thin crystalline MoS2 domains. With increase of the annealing temperature, these nuclei coalesce to form larger nanosheets. Annealing and the resulting amorphous to crystalline transition involves a trade-off between the number of available sites (which is decreased with increasing crystallite size) and the intrinsic activity of the sites (which is improved with increasing crystallinity). Optimal hydrogen evolution reaction (HER) activity is observed for the molybdenum sulfide sample prepared by annealing at 300 °C, which comprises ultra-thin MoS2 nuclei embedded within a matrix of [Mo3S13]2− clusters. This sample is characterized by an overpotential value η10 of 176 mV, a Tafel slope of 49.2 mV dec−1, a turnover frequency of 1.15H2 per s per active site at −0.2 V versus reversible hydrogen electrode (RHE), and furthermore exhibits reasonable stability upon prolonged electrochemical cycling. The amorphous samples are found to be more susceptible to oxidation, which degrades the stability of the catalysts. The mapping of electrode-level parameters and intrinsic activity as a function of crystallite size provides vital design principles for constructing a viable electrocatalyst.

Organic metal halide perovskites have rapidly emerged as among the leading candidates for the next generation of photovoltaic and light-emitting devices. The band gap, exciton binding energy, and absorption cross-section of these materials are tunable to some extent by compositional variation. Dimensional confinement represents an attractive alternative to compositional variation for tuning these properties via quantum confinement close to the Bohr radius. While the stabilization of few-layered nanoplatelets of methylammonium lead bromide has recently been demonstrated, mechanistic understanding of synthetic parameters resulting in dimensional confinement remains to be developed. Here we show that the layer thickness can be precisely modulated as a function of the chain length and concentration of the added alkylammonium cations. Surface capping ligands bind preferentially to sheets of corner sharing PbBr6 octahedra and thereby buffer the extent of supersaturation of monomeric units enabling precise modul...

Molybdenum disulfide (MoS2) is a promising earth-abundant and low-cost electrocatalyst for the hydrogen evolution reaction (HER). In this study, we describe a stepwise synthetic approach comprising vapor transport, reduction, and topochemical sulfidation for creating 3D arrays of MoS2 nanosheets directly integrated onto carbon fiber paper (CFP) substrates. The sulfidation process results in a high density of edge sites along both the edges and the basal planes of MoS2. The obtained materials characterized by a high density of exposed edge sites exhibit promising electrocatalytic performance, including an overpotential (η10) of 245 mV at 10 mA/cm2, a Tafel slope of 81 mV/dec, and a turnover frequency (TOF) of 1.28 H2/s per active site at −0.2 V vs RHE in a 0.5 M acidic solution. The electrocatalytic properties of the MoS2 nanosheets are observed to be substantially enhanced by interfacing with solution-deposited buckminsterfullerene nanoclusters (nC60). A coverage of ca. 2% of nC60 yields a hybrid electroc...

Multicomponent oxides can be extensively explored as alternative gas-sensing materials to binary oxides with their structural and compositional versatilities. In this work, the gas-sensing properties of CuBi

© 2018 American Chemical Society. Molybdenum disulfide (MoS2) is a semiconducting transition metal dichalcogenide that is known to be a catalyst for both the hydrogen evolution reaction (HER) as well as for hydro-desulfurization (HDS) of sulfur-rich hydrocarbon fuels. Specifically, the edges of MoS2nanostructures are known to be far more catalytically active as compared to unmodified basal planes. However, in the absence of the precise details of the geometric and electronic structure of the active catalytic sites, a rational means of modulating edge reactivity remain to be developed. Here we demonstrate using first-principles calculations, X-ray absorption spectroscopy, as well as scanning transmission X-ray microscopy (STXM) imaging that edge corrugations yield distinctive spectroscopic signatures corresponding to increased localization of hybrid Mo 4d states. Independent spectroscopic signatures of such edge states are identified at both the S L2,3and S K-edges with distinctive spatial localization of such states observed in S L2,3-edge STXM imaging. The presence of such low-energy hybrid states at the edge of the conduction band is seen to correlate with substantially enhanced electrocatalytic activity in terms of a lower Tafel slope and higher exchange current density. These results elucidate the nature of the edge electronic structure and provide a clear framework for its rational manipulation to enhance catalytic activity.

The comparative moisture-barrier performance of amorphous and crystalline inorganic oxide thin films deposited on polymer substrates by sputtering at room temperature is reported using the composition (In vs. Zn ratio)-dependent crystallization in In–Zn–O (IZO) homologous phase. The water vapor transmission rate of IZO thin film decreased by more than an order of magnitude when the crystallinity of the films increased with increasing Zn content. This result suggests that the crystallization can improve the gas-barrier performance in inorganic barrier films.

The paper analyzes reactive power flow characteristic in power system by reactive power tracing. In addition, virtual buses are inserted in the algorithm to consider losses of transmission lines, and shunt capacitor treated as a reactive power generator. The results of simulation are analyzed by two points of view. The one is load’s point of view and another is generator’s point of view. Classic purpose of the reactive power tracing consists in the reactive power pricing. However, it is significantly used to select vulnerable area about line outage in this paper. To find the vulnerable area, reactive power tracing variations between pre-contingency and post-contingency are calculated at all load buses. In heavily load area, buses which has highest variation become the most vulnerable bus. This method is applied to the IEEE 39-bus system. It is compared with voltage variation result and VQ-margin to verify its effect.Key Words : Reactive power tracing, Vulnerable area, Proportional sharing rule, Power flow, Virtual bus†Corresponding Author : Department of Electrical Engineering, Korea University, KoreaE-mail : leeb@korea.ac.kr* Department of Electrical Engineering, Korea University, KoreaReceived : January 9, 2015; Accepted : June 16, 2015

The nucleation and growth behavior of Cu nanoparticles during thermal heating of Cu(II) complex inks for printed Cu metallization were investigated, particularly focusing on the effects of the amine concentration on the microstructure evolution and electrical conductivity. Herein, the dual effects of hexylamine as a reducing agent dissociating the carboxyl group from the precursor and a capping agent hindering the subsequent growth of Cu nuclei were confirmed. On the basis of such dual effects of amine, the sufficient complexation of the Cu(II) precursor with a high amine concentration in the ink led to the single-route growth of Cu nanoparticles during thermal heating, which resulted in the dense film with a narrow particle size distribution exhibiting a high electrical conductivity. The electrical conductivity of the film could be further enhanced by a reducing atmosphere with formic acid. Significantly, the understanding of the ink chemistry and the nucleation and growth kinetics in the metal ion complex or metal-organic decomposition (MOD) ink can provide the design rules for the formulation of the solution-type inks to control the microstructure of printed metallization.

This paper deals with shunt compensation to eliminate voltage violation and enhance transfer capability, which is motivated towards implementation in the Korean power system. The optimal shunt compensation algorithm has demonstrated its effectiveness in terms of voltage accuracy and reducing the number of actions of reactive power compensating devices. The main shunt compensation devices are capacitor and reactor. Effects of control devices are evaluated by cost computations. The control objective at present is to keep the voltage profile of a key bus within constraints with minimum switching cost. A robust control strategy is proposed to make the control feasible and optimal for a set of power-flow cases that may occurs important event from system. Case studies with metropolitan area of the Korean power system are presented to illustrate the method.

This paper deals with methodology to control an automatic substation system. The control system can predict the power system condition by a voltage stability index (VSI). The strategies in this paper is called as Voltage-Reactive Power Control (VRPC), which regulates an abnormal voltage of a target substation by using coordination between tap changers and shunt capacitor/reactor. This method is efficient for better voltage profile. The monitoring substation includes whole of substations around the contingency event. The control quantities of the monitoring substations are decided by the calculation of the VSI, called as a Z-index. Case studies with BC Hydro-Quebec system are presented to illustrate this approach using real-time simulator.

Eu3+-activated novel alkaline earth metal (Sr and Ba) vanadate phosphors, Na(Sr0.97−x,Bax)VO4: Eu 0.03 3 + (x = 0–0.97) have been successfully synthesized using solid state reaction method and characterized through structure, morphology, elemental analysis, luminescence (excitation, emission and CIE coordinate) and decay rate properties as a function of Ba ion concentration. Phosphors show a broad excitation band (monitored for 5D0 → 7F2 transition of Eu3+) in the 230–430 nm wavelength regions which make them highly suitable for GaN-based LED chips. These phosphors can be efficiently excited by near UV light and exhibit a dominant red emission at 613 nm (5D0 → 7F2). The decay lifetime and color coordinates were evaluated for Na(Sr,Ba)VO4:Eu3+ phosphors. Hence, these phosphors could be a potential candidate for light emitting diodes and display applications.

This report shows that the size of Al-based metallic glass, Al 86 Ni 6 Y 4.5 Co 2 La 1.5 , particles containing a rare-earth element can be reduced homogeneously from 14.501 μm to 1.456 μm in average diameters without any change in its shape, morphology, composition or amorphous structure via a very simple process that involves immersion in an aqueous HCl acid solution with a specific concentration.

The p-type semiconducting CuO mesoporous films were fabricated with a novel ink solution formulated optimally with an organometallic precursor and a polymer additive. The films were calcined at 200–600 °C in air and their crystallinity, morphology, pore structure and chemical composition were investigated by X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM) and X-ray photoelectron spectroscopy (XPS). H 2 and C 2 H 5 OH gas sensing properties of the films calcined above 400 °C were investigated as a function of operating temperature, and were correlated with crystallinity, hole concentration and morphological factors of each film. The calcination-temperature dependence of the p-type gas sensing properties regarding the films suggested that higher hole concentration/crystallinity/surface-to-volume ratio and better crystallinity/lower grain boundary density in the sensing films lead to higher and faster p-type gas responses, respectively. In addition, to the best of our knowledge, the responses toward H 2 and C 2 H 5 OH gases regarding these CuO gas sensors are comparable to the values previously reported.

In this paper, a method to estimate ice loads as a function of the buttock angle of an icebreaker is presented with respect to polycrystalline freshwater ice. Ice model tests for different buttock angles and impact velocities are carried out to investigate ice pressure loads and tendencies of ice pressure loads in terms of failure modes. Experimental devices were fabricated with an idealized icebreaker bow shape, and medium-scale ice specimens were used. A dry-drop machine with a freefall system was used, and four pressure sensors were installed at the bottom to estimate ice pressure loads. An estimation equation was suggested on the basis of the test results. We analyzed the estimation equation for design ice loads of the International Association of Classification Societies (IACS) classification rules. We suggest an estimation equation considering the relation between ice load, buttock angle, and velocity by modifying the equations given in the IACS classification rules.

Precursor-type Cu inks were formulated by mixing copper (II) formate and hexylamine. The lowest electrical resistivity obtained in Cu films made from these inks was 5.2 μΩ·cm. The Cu concentrations in the inks influenced the impurity content after annealing and the microstructure (specifically, the porosity). Inks with a higher volume of hexylamine had a narrower size distribution of Cu particles, so they formed denser films. However, a large volume of hexylamine could not be fully vaporized during a limited annealing time and reacted with formate, creating impurities having boiling temperatures higher than that of hexylamine. Therefore, the Cu concentration governed two factors, porosity and impurity content, which ultimately determined the electrical resistivity of the films. These findings are expected to facilitate the development of copper-based metallic inks for printed electronics.

A constant reactive power (Q) reserve (CQR) is measured by the difference between the maximum reactive power generation and its current. However, all reactive power sources must not affect the entire power system when severe contingencies occur. Thus, generators must be evaluated as to whether or not they will have an impact on the maximum permissible loading of buses. This definition considers some generators to still have reactive power reserves when the system faces voltage collapse. This remaining reactive power reserve, although available, cannot be used in an arbitrary manner. This paper proposes the concept of an effective reactive power reserve and it is calculated on the basis of a sensitivity analysis. The computed reactive power reserve is analyzed using static and dynamic simulations in bulk power systems.

Strong bonding of titanium to stainless steel, even with strengths more than that of the base metal, is challenging, but has never been achieved owing to its inherent brittleness. Here we report a strong bonding of Ti Gr. 2 to STS by using engineered interlayer structure of V–Cr–Ni and Ti-base amorphous alloy filler. Under optimum conditions, the Ti(base)/Ti solid solution/V/Cr/Ni/STS(base) joints were reliably produced without any detrimental brittle phases, exhibiting a remarkably high strength exceeding that of the Ti Gr. 2.

Homogeneous multilayered barrier films were fabricated by means of reactive and nonreactive sputtering of Al2O3. Homogeneous multilayer structures were seen to possess superior mechanical stability than single-layered films. The multilayer films presented 50% improved barrier performance and the fabrication process was 40% faster compared with single Al2O3 layers of the same thickness. The water vapor transmission rate was enhanced up to the order of 10−4 g m−2 day−1 from a three-pair system of reactive and nonreactive sputtered Al2O3 bilayers.

This paper proposes a hybrid voltage controller based on a hierarchical control structure for implementation in the Jeju power system. The hybrid voltage controller utilizes the coordination of various reactive power devices such as generators, switched shunt devices and LTC to regulate the pilot voltage of an area or zone. The reactive power source can be classified into two groups based on action characteristics, namely continuous and discrete. The controller, which regulates the pilot bus voltage, reflects these characteristics in the coordination of the two types of reactive power source. However, the continuous type source like generators is a more important source than the discrete type for an emergency state such as a voltage collapse, thereby requiring a more reactive power reserve of the continuous type to be utilized in the coordination in order to regulate the pilot bus voltage. Results show that the hybrid controller, when compared to conventional methods, has a considerable improvement in performance when adopted to control the pilot bus voltage of the Jeju island system.

We developed a room-temperature encapsulation process based on multi-stack of ultra thin Al 2 O 3 and polyurea layers for top-emission organic light-emitting devices (TEOLEDs). Device structure, including a capping layer for refractive-index matching and a thick polyurea buffer layer, was optimized to enhance light extraction without distorting electroluminescence spectrum. The efficiency of a TEOLED encapsulated with 5 pairs of Al 2 O 3 (50 nm)/polyurea(20 nm) layers was better than that of a glass-encapsulated TEOLED, whereas their color coordinates were almost identical. Moreover, the half-decay lifetime of a TEOLED encapsulated with 5 pairs of Al 2 O 3 /polyurea layers was 86% of that of a glass-encapsulated TEOLED. Water vapor transition rate of 5 pairs of Al 2 O 3 (50 nm)/polyurea(20 nm) layers on PET film was measured as low as 5 × 10 −4 g/m 2 day.

The effects of the crystallographic orientation on the H2 gas sensing properties were investigated in highly oriented polycrystalline Pd-doped SnO2 films, which were obtained using rf magnetron sputtering of a Pd (0.5 wt%)-SnO2 target on various substrates (a-, m-, r-, and c-cut sapphire and quartz). All the films had a similar thickness (∼110 nm), root-mean-square (rms) roughness (∼1.3 nm), surface area, and chemical status (O, Sn, and Pd). However, the orientation of the films was strongly affected by the orientation of the substrates. The (1 0 1), (0 0 2), and (1 0 1) oriented films were grown on ( 1 1 2 ¯ 0 ) (a-cut), ( 1 0 1 ¯ 0 ) (m-cut), and ( 1 1 ¯ 0 2 ) (r-cut) Al2O3 substrates, respectively, and rather randomly oriented films were deposited on (0 0 0 1) (c-cut) Al2O3 and quartz substrates. In addition, the oriented Pd-doped SnO2 films were highly textured and had in-plane orientation relationships with the substrates similar to the epitaxial films. The (1 0 1) Pd-doped SnO2 films on ( 1 1 2 ¯ 0 ) and ( 1 1 ¯ 0 2 ) Al2O3 showed a considerably higher H2 sensitivity, and their gas response decreased with increasing sensing temperature (400–550 °C). The films deposited on ( 1 0 1 ¯ 0 ) and (0 0 0 1) Al2O3 showed the maximum sensitivity at 500 °C. The comparison of the H2 gas response between undoped and Pd-doped SnO2 films revealed that the Pd-doping shifted the optimum sensing temperature to a lower value instead of improving the gas sensitivity.

To improve the performance of tiled display system, two parallel tiled display algorithms are proposed by combining the sort-first and the sort-last sorting methods. In the proposed algorithms, the view frustum culling is employed along with the OpenGL display list for the sort-first sorting, and the pre-detection sort-last sparse sorting method is used for sort-last sorting. Through the benchmarking tests, the performances of two proposed algorithms are investigated. Based on the observations, it is suggested how to select an optimal algorithm among the two proposed parallel tiled display algorithms for the given visualization model.

In this paper, an efficient technique is proposed to integrate the 3D user interface with the tiled display system in PC cluster environment. In the developed 3D user interface software, various menus are provided to increase the user friendliness of the interface, including the several model-control-commands. To eliminate the noise produced from the 3D user interface devices, the box filtering algorithm is employed. Further, a communication splitting algorithm, which is a kind of asynchronous communication method, is proposed to reduce the motion delay between the 3D interface and the tiled display system, and its efficiency is validated through the benchmarking tests.