Shou Heng Liu

Impact of Chi-Chi earthquake on the occurrence of landslides and debris flows: Example from the Chenyulan River watershed, Nantou, Taiwan

Abstract The Chenyulan River watershed in central Taiwan was chosen for evaluating the impact of the Chi-Chi earthquake on the occurrence of landslides, and for exploring the initial conditions triggering debris flows. Interpretations of aerial photographs and SPOT images as well as field investigations were used to identify landslide and debris flow occurrences. Precipitation data were then utilized to investigate critical conditions leading to the debris flow. Comparison of five SPOT images taken between June 1996 (before the July 1996 Typhoon Herb) and September 1999 (before the Chi-Chi earthquake) shows that the landslide area increased from 7.1×106 to 7.5×106 m2 during that time. However, by January 2000 (after the Chi-Chi earthquake), the landslide area almost tripled to 20.8×106 m2. Measurement of images taken in March and August 2001 reveals that the landslide area had further expanded to 24.2×106 and 27.5×106 m2, respectively. Significant differences before and after the earthquake are also noticed in (1) the intensity and amount of precipitation required for triggering debris flow, (2) the size of contributing drainage basin in which debris flows occurred, and (3) the frequency of debris flows. After the Chi-Chi earthquake, maximum hourly rainfall intensity and critical accumulated precipitation necessary to initiate debris flow reduced to as low as 1/3 of the pre-earthquake figures. Prior to the Chi-Chi earthquake, most debris flows occurred in gullies with slopes greater than 10°, and in drainage basins larger than 0.1 km2. Conversely, after the earthquake, debris flows were observed even in gullies with effective drainage area smaller than 0.03 km2. Furthermore, before the earthquake, the debris flow recurrence time in the study area was greater than 5 years, whereas six debris flow events have been observed in the 2 years since the earthquake.

Fabrication and electrocatalytic performance of highly stable and active platinum nanoparticles supported on nitrogen-doped ordered mesoporous carbons for oxygen reduction reaction

A facile synthesis route for the preparation of N-doped ordered mesoporous carbons (NOMCs) containing well-dispersed, highly stable Pt nanoparticles (NPs) is reported. The synthesis of these mesostructured Pt-NOMC materials invokes pyrolysis of co-fed carbon sources and Pt precursors in 3-[2-(2-aminoethylamino)ethylamino]propyl-functionalized mesoporous SBA-15 silicas, which served simultaneously as N sources and hard templates. It was found that the dispersion of Pt NPs increases with increasing N content in the Pt-NOMC nanocomposites, leading to higher electrocatalytic activity during oxygen reduction reaction (ORR) and methanol-tolerant stability compared to typical commercial electrocatalyst (Pt/XC-72). The superior electrochemical performances observed for the synthesized Pt-NOMCs have been attributed to the dispersion and unique nanostructure of Pt NPs particularly in the presence of pyridinic-N atoms in the mesoporous carbon supports.

Pyrolysis kinetics of refuse-derived fuel

Refuse-derived fuel (RDF) was mechanically separated from municipal solid waste (MSW) in a 300 TPD (tons per day) waste pretreatment plant. Pyrolysis of the RDF produced approximately 28% of oils, and 30% of noncondensible hydrocarbon gases and 42% of solid residues at 773 K. Thermal gravimetric analysis (TGA) techniques were used in quantitative prediction of the RDF pyrolysis rate. The global pyrolysis reaction rate was calculated from key component fractions (paper, LDPE, HDPE, PS, and PVC) of RDF using the weighed sum method. Good agreement was found in pyrolysis kinetics between RDF itself and the weighed sum method of the plastic components in RDF. Pyrolysis of RDF in the fixed-bed reactor also had a similar result. This approach allows one to easily account for RDF composition variations, thus rendering the model more generally valid.

Image processing of FORMOSAT-2 data for monitoring the South Asia tsunami

We report on the actions of the first daily revisit satellite, FORMOSAT‐2, in the recent Indian Ocean tsunami disaster. Starting from the first images of Banda Aceh and Phuket taken on 28 December 2004, FORMOSAT‐2 used its unique orbit and pointable sensor system to demonstrate the extent to which it is able to respond to emergencies. A total of 137 images throughout the Indian Ocean rim countries were taken within a month. The data were immediately analysed and turned into damage‐assessment maps and other information resources for humanitarian aid. This paper focuses on the image‐processing procedure followed for a fast response to the South Asia tsunami event. The imageodesy technique is used to coregister the level‐2 product of FORMOSAT‐2 image at high accuracy and speed. A novel approach for spectral reservation data fusion has also been proposed. With the advantages of accurate coregistration and reliable spectral property, the colour composites of FORMOSAT‐2 imagery have been used as the principle source of information for our tsunami hazard assessment. The potential of FORMOSAT‐2 for disaster monitoring is discussed. The technique developed in this research will be adapted to produce pan sharpened images as a standard value added product of FORMOSAT‐2.

Photocatalytic generation of hydrogen on Zr-MCM-41

Abstract Zr-MCM-41 was prepared via incorporation of Zr into the amorphous wall of MCM-41 in the hydrothermal synthesis process. Experimentally, photocatalytic generation of hydrogen on Zr-MCM-41 was investigated in a total reflectance system. In the presence of Zr-MCM-41, hydrogen yield ( 22.4 μmol H2/h) in the photocatalytic decomposition of H2O was highly enhanced by at least 2.5 times over that of the conventional photocatalyst ZrO2. The enhancement may be due to the high dispersion of ZrO2 and the justified band gap between the conduction band and valance band of ZrO2 in the wall of MCM-41. This work demonstrates how photodecomposition of H2O was affected by high dispersion of photoactive species (ZrO2) in the amorphous wall of MCM-41.

Controlled synthesis of highly dispersed platinum nanoparticles in ordered mesoporous carbons

A novel route has been developed to fabricate ordered carbon mesoporous materials with well-dispersed, highly stable Pt nanoparticles of ca. 2-3 nm on the pore walls using platinum acetylacetonate as the co-feeding carbon and Pt precursor.

Adsorption of CO2 from Flue Gas Streams by a Highly Efficient and Stable Aminosilica Adsorbent

ABSTRACT Three ordered mesoporous silicas (OMSs) with different pore sizes and pore architectures were prepared and modified with amine functional groups by a postgrafting method. The carbon dioxide (CO2) adsorption on these amine-modified OMSs was measured by using microbalances at 348 K, and their adsorption capacities were found to be 0.2–1.4 mmol g−1 under ambient pressure using dry 15% CO2. It was found experimentally that the CO2 adsorption capacity and adsorption rate were attributed to the density of amine groups and pore volume, respectively. A simple method is described for the production of densely anchored amine groups on a solid adsorbent invoking direct incorporation of tetraethylenepentamine onto the as-synthesized OMSs. Unlike conventional amine-modified OMSs, which typically show CO2 adsorption capacity less than 2 mmol g−1, such organic template occluded amine-OMS composites possessed remarkably high CO2 uptake of approximately 4.6 mmol g−1 at 348 K and 1 atm for a dry 15% CO2/nitrogen feed mixture. The enhancement of 8% in CO2 adsorption capacity was also observed in the presence of 10.6% water vapor. Durability tests done by cyclic adsorption-desorption revealed that these adsorbents also possess excellent stability. IMPLICATIONS Current available CO2 separation schemes for fossil fuel combustion normally invoke absorption by a liquid and are generally limited by the high capital and operation costs. Amine-modified solid sorbents are attractive for CO2 capture from flue gas streams because of the low energy consumption of the regeneration process. In this study, an easy method is developed by directly introducing tetraethylenepentamine onto the as-synthesized OMSs, which represents not only a time-saving route but also superior CO2 adsorption capacities and durability after repeated adsorption-desorption cycles, revealing some opportunities for future practical applications.

A new alternative paraffinic–palmbiodiesel fuel for reducing polychlorinated dibenzo-p-dioxin/dibenzofuran emissions from heavy-duty diesel engines

Polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) emissions from heavy-duty diesel engines (HDDEs) fuelled with paraffinic-palmbiodiesel blends have been rarely addressed in the literature. A high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) was used to analyze 17 PCDD/F species. Experimental results indicate that the main species of PCDD/Fs were OCDD (octachlorinated debenzo-p-dioxin) and OCDF (octachlorodibenzofuran), and they accounted for 40-50% of the total PCDD/Fs for all test fuels. Paraffinic-palmbiodiesel blends decreased PCDD/Fs by 86.1-88.9%, toxic PCDD/Fs by 91.9-93.0%, THC (total hydrocarbons) by 13.6-23.3%, CO (carbon monoxide) by 27.2-28.3%, and PM (particulate matter) by 21.3-34.2%. Using biodiesel blends, particularly BP9505 or BP8020, instead of premium diesel fuel (PDF) significantly reduced emissions of both PCDD/Fs and traditional pollutants. Using BP9505 (95vol% paraffinic fuel+5vol% palmbiodiesel) and BP8020 instead of PDF can decrease PCDD/F emissions by 5.93 and 5.99gI-TEQyear(-1) in Taiwan, respectively.

Hyperpolarized 129Xe NMR investigation of multifunctional organic/inorganic hybrid mesoporous silica materials

An extensive study has been made on a series of multifunctional mesoporous silica materials, prepared by introducing two different organoalkoxysilanes, namely 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (AEPTMS) and 3-cyanopropyltriethoxysilane (CPTES) during the base-catalyzed condensation of tetraethoxysilane (TEOS), using the variable-temperature (VT) hyperpolarized (HP) 129Xe NMR technique. VT HP-129Xe NMR chemical shift measurements of adsorbed xenon revealed that surface properties as well as functionality of these AEP/CP-functionalized microparticles (MP) could be controlled by varying the AEPTMS/CPTES ratio in the starting solution during synthesis. Additional chemical shift contribution due to Xe-moiety interactions was observed for monofunctional AEP-MP and CP-MP as well as for bifunctional AEP/CP-MP samples. In particular, unlike CP-MP that has a shorter organic backbone on the silica surface, the amino groups in the AEP chain tends to interact with the silanol groups on the silica surface causing backbone bending and hence formation of secondary pores in AEP-MP, as indicated by additional shoulder peak at lower field in the room-temperature 129Xe NMR spectrum. The exchange processes of xenon in different adsorption regions were also verified by 2D EXSY HP-129Xe NMR spectroscopy. It is also found that subsequent removal of functional moieties by calcination treatment tends to result in a more severe surface roughness on the pore walls in bifunctional samples compared to monofunctional ones. The effect of hydrophobicity/hydrophilicity of the organoalkoxysilanes on the formation, pore structure and surface property of these functionalized mesoporous silica materials are also discussed.

Photodecomposition of Water Catalyzed by Zr- and Ti-MCM-41

Experimentally incorporated Zr or Ti into the framework of MCM-41 could enhance the photocatalytic decomposition of H2O to H2. The hydrogen yield, for instance, on Zr-MCM-41 was about 7 mmol H2/hr-gZrO2. The enhancement of Zr-MCM-41 was over 80 times if compared to the bulk ZrO2. The Ti-MCM-41 also possessed an enhancement of about 17 times for the H2 yield (over TiO2).