bluuebunny/crossref_metadata_2025 huggingface dataset:
Steady-state photolysis of dimesitylbis(trimethylsilyl)germane
Authors: Hurni Krysten L , Baines Kim M
Published: December 2007

The photolysis of dimesitylbis(trimethylsilyl)germane (3) in hexanes or THF, at low temperature, has been investigated as a potential method for the preparative-scale synthesis of tetramesityldigermene (5). A product mixture, consisting of hexamethyldisilane, mesitylene, 2-trimethylsilylmesitylene (7), a new germacyclobutene (8), and an unidentified polymer, was obtained. No evidence for the formation of tetramesityldigermene (5) was observed.Key words: diaryldisilylgermane, digermene, germylene, germacyclobutene, photolysis.
Canadian Light Source — Optical Metrology Facility
Authors: Yates Brian W , Maxwell Dylan G
Published: December 2007

The Canadian Light Source Optical Metrology Facility serves as a support facility and provides metrological services required by the synchrotron beamlines. The Facility consists of three state-of-the-art instruments: a Micromap 570 surface profiler, an Ocean Optics long trace profilometer, and a Zygo Verifire AT Fizeau interferometer. These three complementary measurement systems permit a complete analysis of the synchrotron beamline optical components. The systems will be discussed in detail, noting synchrotron and industrial applications where possible.Key words: optics, metrology, surface roughness, slope error, tribology.
High-resolution gas phase P L-edge photoabsorption spectra of PF5
Authors: Hu Y F , Zuin L , Püttner R
Published: December 2007

High-resolution photoabsorption spectra of P 2s and 2p levels of PF5 are reported. Fine structure, due to spin-orbit and ligand field splittings together with strong vibrational progression, is resolved in the Rydberg region of the P 2p spectrum. A ligand field splitting of 31 meV for the 2p3/2 orbital is obtained from the fit of the Rydberg transitions. The Franck–Condon fit analysis revealed that the vibrational progression of the higher Rydberg states is different from that of the valence-Rydberg mixed 4s state. In particular, we derived a decrease in P–F bond distances of 12 and 28 pm for the 4s valence-Rydberg mixed state and the high nl Rydberg states, respectively. The natural linewidths of the P 2p levels were determined to be 55 meV.Key words: PF5, Rydberg state, vibrational, ligand field splitting, photoabsorption.
Characterization of the influence of fission product doping on the anodic reactivity of uranium dioxide
Authors: He Heming , Keech Peter G , Broczkowski Michael E , Noël James J , Shoesmith David W
Published: December 2007

The influence of fission product doping on the structure, composition, and electrochemical reactivity of uranium dioxide has been studied using X-ray diffractometry (XRD), scanning electron microscopy (SEM/EDX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Experiments were conducted on SIMFUEL specimens with simulated burn-ups (increasing doping levels) of 1.5, 3.0, and 6.0 atom%. As the dopant level increased, the lattice contracted, suggesting the dominant formation of dopant-oxygen vacancy clusters. The smaller than expected lattice contraction can be attributed to the segregation of Zr (one of eleven added dopants) to ABO3 perovskite-type phases that SEM/EDX shows also contain Ba, Ce, and possibly some U. Raman spectroscopy shows that doping leads to a loss of cubic symmetry, possibly associated with tetragonal distortions. Raman mapping confirms this loss of cubic symmetry and suggests the specimen is not uniformly doped. Electrochemical experiments show that these distortions lead to a decrease in the oxidative dissolution rate of the UO2 with increased doping density.Key words: UO2, X-ray diffraction, electrochemistry, Raman spectroscopy, nuclear fission products.
An O K-edge XANES study of calcium aluminates
Authors: Henderson Grant S , Neuville Daniel R , Cormier Laurent
Published: December 2007

Oxygen K-edge XANES spectra of crystalline calcium aluminate phases exhibit features that are strongly influenced by orbital mixing between the O 2p antibonding states and Ca and Al orbitals. Specific peaks in the spectra are characteristic of the calcium coordination and can be assigned to Ca in nine-, eight-, seven-, and six-fold coordination. The Q speciation of the AlO4 tetrahedra also influences the position of the peaks, and several peaks result from a mixture of Ca and Al interactions.Key words: O K-edge XANES, calcium aluminates, coordination, Q species.
Self-assembly of biomolecules at surfaces characterized by NEXAFS
Authors: Liu Xiaosong , Zheng Fan , Jürgensen A , Perez-Dieste V , Petrovykh D Y , Abbott N L , Himpsel F J
Published: December 2007

Surface science has made great strides towards tailoring surface properties via self-assembly of nanoscale molecular adsorbates. It is now possible to functionalize surfaces with complex biomolecules such as DNA and proteins. This brief overview shows how NEXAFS (near edge X-ray absorption fine structure spectroscopy) can be used to characterize the assembly of biological molecules at surfaces in atom- and orbital-specific fashion. To illustrate the range of applications, we begin with simple self-assembled monolayers (SAMs), proceed to SAMs with customized terminal groups, and finish with DNA oligonucleotides and Ribonuclease A, a small protein containing 124 amino acids. The N 1s absorption edge is particularly useful for characterizing DNA and proteins because it selectively interrogates the π* orbitals in nucleobases and the peptide bonds in proteins. Information about the orientation of molecular orbitals is obtained from the polarization dependence. Quantitative NEXAFS models explain the polarization dependence in terms of molecular orientation and structure.Key words: NEXAFS, bio-interfaces, ribonuclease A, immobilization, orientation.
Electronic structures of CdSe nanocrystals — An X-ray absorption near-edge structure (XANES) investigation
Authors: Zhou Jigang , Zhou Xingtai , Sun Xuhui , Murphy Michael , Heigl Franziskus , Sham Tsun-Kong , Ding Zhifeng
Published: December 2007

CdSe nanocrystals (NCs), capped with trioctylphosphine oxide and 1-octadecanamine, have been synthesized with colloidal methods. Both UV–vis absorption and photoluminescence spectra show that the prepared nanostructures exhibit a quantum confinement effect. X-ray absorption near–edge structure (XANES) at Se K-edge recorded in fluorescence yield mode have been carried out on these NCs, with different size and capping ligands to gain insight into how their electronic structures are affected by the NC size and chemical properties of the ligands. The results indicate that XANES are sensitive to both the NC size and the nature of the capping ligands. The whiteline intensity in XANES spectra can be related to the photoluminescence properties of these NCs.Key words: CdSe nanocrystals, capping ligands, X-ray absorption near-edge structure, UV–vis spectroscopy, photoluminescence.
Theoretical X-ray absorption investigation of the uniaxial compression of hexagonal graphite
Authors: Shaw Dawn M , Odelius Michael , Tse John S
Published: December 2007

The X-ray absorption (XAS) and powder X-ray diffraction (XRD) spectra for the intermediate structures along uniaxial c-axis compression of hexagonal graphite are studied with the first-principles pseudopotential plane wave method. Comparison with experiment is made whenever results are available. A transformation from graphite to a new carbon phase was observed in the simulation. The new phase consists of alternating linkages of the graphite layers via the formation of C–C σ bonds. The calculated XAS and XRD reproduced most but not all of the features observed in a recent experiment. Comments are made on the reliability of the computational procedures to reproduce the XAS of these structures.Key words: graphite, uniaxial compression, ab initio, and X-ray absorption spectroscopy.
Solvation and electronic structures of M+Ln, with M+ = Mg+ and Ca+, L = H2O, CH3OH, and NH3, and n = 1–6
Authors: Chan K W , Wu Y , Liu Z -F
Published: December 2007

The solvation clusters M+(L)n, with a singly charged alkaline earth cation Mg+ or Ca+ as the solute and with water, methanol, or ammonia as the solvent, are studied systematically in the size range n = 1–6, to compare the variations in the solvation interactions. For clusters with n ≤ 3, the energies and structural values are compared in details, with both the MP2 and B3LYP methods. For clusters with n ≥ 4, the solute–solvent and solvent–solvent interaction energies are calculated to explain the relative stability among various isomeric structures, and the contrast in both solvent and electron distribution among these cluster series. Thermal stabilities for these clusters are also examined by ab initio molecular dynamics simulations at finite temperature.Key words: solvation clusters, ab initio calculations, solute–solvent interactions, size-dependent effects.
Soft X-ray excited colour-centre luminescence and XANES studies of calcium oxide
Authors: Ko JY Peter , Heigl Franziskus , Yiu Yun Mui , Zhou Xing-Tai , Regier Tom , Blyth Robert I.R , Sham Tsun-Kong
Published: December 2007

In this study, we show that colour centres can be produced by irradiating calcium oxide with soft X-rays from a synchrotron radiation source. Using the X-ray excited optical luminescence (XEOL) technique, two colour centres, F-centre, and F+-centre can be identified. These colour centres emit photons at characteristic wavelengths. In addition, by performing time-resolved XEOL (TRXEOL), we are able to reveal timing and decay characteristics of the colour centres. We also present X-ray absorption near-edge structure (XANES) spectra collected across oxygen K-edge, calcium L3,2-edge, and calcium K-edge. Experimental results are compared with density functional theory (DFT) calculations.Key words: calcium oxide, colour centre, synchrotron, X-ray excited optical luminescence, X-ray absorption near-edge structure.
Characterization of the conformational changes in recombinant human metallothioneins using ESI-MS and molecular modeling
Authors: Chan Jayna , Huang Zuyun , Watt Ian , Kille Peter , Stillman Martin J
Published: December 2007

Electrospray ionization mass spectrometry (ESI-MS) data and molecular modeling calculations were used to gain mechanistic, conformational, and domain-specific information from the acid-induced demetallation reactions of human metallothionein. The recombinant proteins studied were the single α- and β-rhMT-1a domains and the βα- and αβ-rhMT-1a two-domain species, based on the human metallothionein 1a sequence. Complete molecular models (MM3/MD) for all the fully metallated and demetallated species using a modified force field are reported for the first time. Basic residues that contribute to the ESI-MS charge states are identified from the molecular models. Demetallation took place under equilibrium conditions within a narrow pH range. For the two-domain proteins, these results support a demetallation mechanism involving the initial complete demetallation of one domain followed by the other for both βα-rhMT and αβ-rhMT. Based on the stability of the separate domains, the β domain is predicted to demetallate first in the two-domain rhMTs. Both the α domain and the β domain were observed to bind an excess of one Cd2+ion. The metallated rhMT structures were shown to have very stable conformations, but only when fully metallated. Two or more conformations were observed at low pH in the ESI-MS data, which are interpreted as arising from the presence of structure, as opposed to a random coil, in the apo-rhMT. This is the first report of the existence of a structure in the two-domain metal-free apo-MT proteins. Only at extremely low pH does the structure open fully to give the highest charge distribution, which is associated with a random coil. Pre-existing structural features in the apo-MT would explain why the metallation reactions occur so rapidly.Key words: recombinant human metallothionein-1 (rhMT1), electrospray ionization mass spectrometry (ESI-MS), circular dichroism (CD), molecular mechanics/molecular dynamics (MM3/MD).
THE CASE FOR AN INTERMEDIATE EXCHANGE RATE REGIME
Authors: WILLIAMSON JOHN
Published: December 2007

The argument that any exchange rate regimes other than firmly fixed and freely floating rates were infeasible — the so-called bipolarity thesis — acquired great popularity in the wake of the Asian crisis of a decade ago, but it has almost vanished today. One reason is surely the unkind empirical evidence, which shows that intermediate regimes — measured as those where both reserve and exchange rate changes lie in an intermediate range — are not in fact tending to disappear (Levy Yeyati and Sturzenegger, 2002). Another reason is the recognition that exchange rate policy should have other objectives besides avoiding crises, and that in the world we live in today it is reasonable to give these other objectives a significant priority. And perhaps a third factor is growing recognition that it is possible to design or operate intermediate regimes in ways that avoid exposing them to the dangers that were focused on by the disciples of bipolarity.

This article starts by distinguishing the options that countries face in choosing an exchange rate regime. It examines the advantages and disadvantages of each of them, finally suggesting that for most countries the real choice lies between freely floating rates, floating rates disciplined by a reference rate system, and an ill-defined managed floating with the management undefined. Three issues may influence the choice between those alternatives: transparency; perceived consistency with that pillar of current macroeconomic thinking, inflation targeting; and the theory of what determines exchange rates. In the latter context, it is argued that the current conventional wisdom of the economics profession is wrong, and that a more convincing diagnosis of the process of exchange rate determination lends support to the proposal for a reference rate system.
THE INTERNATIONAL MONETARY FUND AND EXCHANGE RATE CRISIS MANAGEMENT
Authors: LIM CHONG-YAH
Published: December 2007

The article analyzes the limits of the IMF as a global multilateral economic agency to handle serious balance of payments disequilibria. Capital control and growth rates in developing Asia and the twin deficit problem of the United States are also discussed. It also assesses the probability of the reemergence of an exchange rate crisis in Southeast Asia and the wisdom of having an Asian IMF.
INSULATION OF INDIA FROM THE EAST ASIAN CRISIS: AN ANALYSIS
Authors: DUA PAMI , SINHA ARUNIMA
Published: December 2007

This paper investigates the effects of the East Asian crisis on the Indian economy and exchange rate movements. Despite the contagion effects that profoundly affected the other crisis-hit countries, the Indian economy and the rupee were found less affected. Reforms after the 1990–1991 crisis, control of capital flows, weak economic linkages with crisis-affected countries and stabilization policies that include intervention in the foreign exchange market and tightening of monetary policy are reasons for the insulation of the Indian economy from the crisis.
MANAGING FLEXIBILITY: JAPANESE EXCHANGE RATE POLICY, 1971–2007
Authors: TAKAGI SHINJI
Published: December 2007

The paper reviews Japan's exchange rate policy from the end of the Bretton Woods era to the present. The Japanese authorities used various tools to manage the yen–dollar exchange rate over much of this period. The most dominant was official foreign exchange intervention, which in most instances took the form of "leaning against the wind". Capital controls were also used but, with full capital account convertibility, ceased to exist as an instrument of exchange rate policy by the mid-1980s. Following the post-Plaza appreciation of the yen, the authorities eased monetary policy to arrest the appreciating pressure. The possible role of exchange rate policy in the great asset inflation that followed, however, remains unanswered. More recently, exchange rate policy during the period of prolonged stagnation and fragile recovery was made subordinate to the overall stance of macroeconomic policy. In this regard, particularly striking in terms of scale and frequency was the "great intervention" of 2003–2004. Equally striking has been the total absence of official intervention since. It would require a renewed substantial volatility of the yen to know whether this indeed marks a permanent shift in Japan's exchange rate policy.
MAGNETIC DECELERATOR FOR PARTICLE BEAMS
Authors: LYUKSYUTOV IGOR F.
Published: December 2007

We discuss possibility of using time-dependent inhomogeneous magnetic field to decrease the speed of particles in a molecular/atomic beam. This includes deceleration via traveling magnetic field gradient. We also discuss possible implementations of the magnetic decelerator.
REACTIVELY RADIO FREQUENCY SPUTTERED SILVER OXIDE THIN FILMS: PHASE EVOLUTION AND PHASE STABILITY
Authors: RAMESH M. N. V. , SUNDARAYYA Y. , SUNANDANA C. S.
Published: December 2007

The main aim of this paper is to fabricate and characterize silver oxide thin films and to investigate the effect of processing parameters on the microstructure of deposited films. Radio frequency (RF) magnetron sputtering was used under oxygen-argon mixed gas atmosphere for fabrication. Oxide phase evolution and stability were investigated by X-ray diffraction (XRD) of as-deposited and post deposition annealed films. In all cases, the hexagonal phase was initially observed which then got transformed to the cubic phase upon annealing films. The hexagonal–cubic "transition" temperature decreases initially upon increase of oxygen content, which is corroborated by optical spectra. The evolution of optical absorption edge was monitored by a spectrophotometer. A bandgap energy of 3.5 eV was deduced for Ag 2 O at 300 K. Atomic force microscopy (AFM) has revealed the influence of deposition conditions on the surface morphology of the films.
DIRECTED MOTION OF BROWNIAN MOTORS: A RATCHET MODEL OF TWO-COUPLED MOLECULAR MOTORS
Authors: WEN SHUTANG , ZHANG HONGWEI , LIU LEIAN , SUN XIAOFENG , LI YUXIAO
Published: December 2007

We investigated the motion of two-head Brownian motors by introducing a model in which the two heads coupled through an elastic spring is subjected to a stochastic flashing potential. The ratchet potential felt by the individual head is anti-correlated. The mean velocity was calculated based on Langevin equations. It turns out that we can obtain a unidirectional current. The current is sensitive to the transition rates and neck length and other parameters. The coupling of transition rate and neck length leads to variations both in the values and directions of currency. With a larger neck length, the bi-particle system has a larger velocity in one direction, while with a smaller neck length, it has a smaller velocity in the other direction. This is very likely the case of myosins with a larger neck length and larger velocity in the positive direction of filaments and kinesins with a smaller neck length and smaller velocity in the negative direction of microtubules. We also further investigated how current reversal depended on the neck length and the transition rates.
INTERACTIVE IIR SC MULTIRATE COMPILER APPLIED TO MULTISTAGE DECIMATOR DESIGN
Authors: CHEONG PHILLIP N. , MARTINS R. P.
Published: December 2007

This paper proposes an interactive architecture compiler for SC multirate circuits that allows the automated design from the frequency specifications to the building block implementation, applied to the design and synthesis of multistage SC decimators. The compiler provides a library of different topologies that comprises a few independent multi-decimation building blocks. New building blocks defined by the users are also available for the design of a specific stage. A design example of a 7th order SC decimator illustrates the efficient synthesis of the corresponding resulting circuits that achieve the required anti-aliasing amplitude responses with respect to the speed requirements of the operational amplifiers and also the minimum capacitance spread and total capacitor area.
LADDER-NETWORK-BASED MODEL FOR INTERCONNECTS AND TRANSMISSION LINES TIME DELAY AND CUTOFF FREQUENCY DETERMINATION
Authors: FERRI GIUSEPPE , ANTONINI GIULIO
Published: December 2007

Half-T RC ladder networks (LNs) are proven to be first-order models of transmission lines (TLs) and interconnections. In this paper, the determination of LNs electrical characteristics, in terms of internal electrical parameters and number of cells, has allowed to calculate, in an approximated but very accurate way, the time delay and cutoff frequency of open-ended RC LN. Numerical examples on real designs confirm the validity of the proposed method in terms of robustness and accuracy.
GENERATION OF GROUNDED CAPACITOR ICCII-BASED BAND-PASS FILTERS
Authors: SOLIMAN AHMED M.
Published: December 2007

A new current-mode band-pass filter using the inverting second-generation current conveyor (ICCII) is introduced. The circuit is generated from a frequency-dependent negative resistance (FDNR)-C circuit realized using ICCII+. It is observed that a voltage-mode band-pass filter using two CCII+ has similar transfer function to this current-mode filter. The adjoint network theorem is used to demonstrate the transformation between the two circuits. Two new voltage-mode grounded capacitor band-pass filters using two ICCII are also introduced. The first voltage-mode circuit is generated from the FDNR-C circuit and employs two opposite Z polarity ICCII. The second voltage-mode circuit is obtained from the first circuit by relocation of the input and a grounded terminal. Two new additional grounded capacitor and grounded resistor current-mode band-pass filters with independent control on the filter Q are also introduced. Spice simulation results with 0.35 μm CMOS transistors model are included to demonstrate the practicality of the two ICCII- band-pass current-mode filter.
Chapter 1 Introduction and previous research
Authors: Barber A. J. , Crow M. J. , Milsom J. S.
Published: December 2007

Sumatra, with an area of 473 606 km
2
is the largest island in the Indonesian archipelago and the fifth largest island in the world. The island stretches across the equator for 1760 km from NW to SE, and is up to 400 km across (Fig. 1.1). Administratively, and for the purposes of this Memoir, Sumatra includes the Mentawai islands from Simeulue to Pagai, which with Enggano form a forearc chain to the SW, and the Tin Islands' of Bangka and Billiton and the Riau islands to the east. The backbone of the main island is formed of the Barisan Mountains, which extend the whole length of Sumatra in a narrow belt, parallel to, and generally only a few tens of kilometres, from the SW coast. The main peaks (which are mainly Quaternary or Recent volcanoes) commonly rise 2000 m above sea level, culminating in Mt Kerinci at 3805 m. Short, steep river courses drain the Barisans towards the SW, often cuttting deep gorges, while towards the east the rivers follow long meandering courses across broad coastal plains and swamps to the Malacca Straits, which separate Sumatra from the Malay Peninsula, or to the Java Sea. Eastwards, across the Java Sea, lies the almost equally large island of Borneo (Indonesian Kalimantan), and Java lies immediately to the SE across the narrow Sunda Strait.

The Malacca Strait and the Java Sea form the southern parts of the Sunda Shelf (Fig. 1.1). Across the shelf the seafloor is shallow with a depth of
Chapter 2 Seismology and neotectonics
Authors: Milsom John
Published: December 2007

Sumatra is an active (Andean) continental margin that would be linked by land to SE Asia if sea level fell by as little as 50 m. Present-day tectonic processes are controlled by three major fault systems, the most obvious of which is the subduction thrust which crops out in the Sunda Trench. The trench curves very little in the 800 km between Enggano and Nias, i.e. off central Sumatra (Fig. 2.1), but is markedly convex towards the Indian Ocean both further north and further south. Water depths of more than 6000 m are reached in the south but the maximum in the north may be less than 5000 m. The difference is usually, and convincingly, attributed to the presence on the Indian Ocean plate of the Nicobar Fan, consisting of sediments, derived ultimately from erosion of the Himalayas, which increase steadily in thickness towards the north (e.g. Hamilton 1979). Continuing subduction is attested by a Wadati-Benioff Zone (WBZ) that extends to depths of the order of 200 km (e.g. Newcomb & McCann 1987) and by volcanic activity in the Barisan mountains, the peaks of which generally lie within a few tens of kilometres of the coast. The change, of more than 45Ð, in the trend of the trench between 96ÐE and 97ÐE (the 'Nias Elbow') may have been initiated by subduction of the 2 km high Investigator Ridge (Investigator Fracture Zone), which trends approximately north-south at about 98ÐE. Sieh & Natawidjaja (2000) defined a 'Central Domain' of mainland Sumatra between
Chapter 3 The gravity field
Authors: Milsom John , Walker Adrian
Published: December 2007

The gravity field of Sumatra and the surrounding marine areas is shown in Figure 3.1. Contours in the onshore area of Bouguer gravity, but offshore are of free-air gravity. Terrain corrections have not been applied. Although marine gravity measurements have been made in the forearc basin and elsewhere on a number of research cruises (e.g. Kieckhefer
et al.
1981), the data from these generally widely spaced lines have not been used in preparing the maps because free-air gravity values obtained from inversion of satellite radar altimetry provide more systematic coverage and can resolve anomalies with widths of as little as 7 km (Sandwell & Smith 1997). The onshore and satellite-derived offshore data were matched at coastlines without undue difficulty, as should be the case because both free-air and Bouguer corrections are zero at sea level. However, gradients tend to be steep at the coasts in the forearc region, partly because of the change from free-air gravity, which is strongly correlated with local bathymetry, to Bouguer gravity, which is corrected for local topography.

Figure 3.2 shows the locations of the onshore stations used in preparing Figure 3.1, but not of the offshore estimates, distributed on a regular 2 minute grid. Onshore data were obtained from a variety of sources, but unfortunately the results of the many detailed gravity surveys carried out by oil companies remain confidential. The largest single available data set was assembled as part of the collaboration between the British Geological Survey (BGS) and the Geological Research and Development
Chapter 6 Pre-Tetiary volcanic rocks
Authors: Crow M. J.
Published: December 2007

Volcanic activity and associated plutonism, ranging in age from the Carboniferous to the Late Cretaceous, has made an important contribution to the Pre-Tertiary geological evolution of Sumatra. This chapter summarizes the known occurrences of Pre-Tertiary volcanic rocks and their geological settings (Fig. 6.1 & Table 6.1). There has been no systematic isotopic dating programme directed at determining the ages of the volcanic rocks, but dating of volcanic episodes in Sumatra has benefited greatly from stratigraphic palaeontological studies on the associated sedimentary units, summarized by Fontaine & Gafoer (1989). Unfortunately, little progress has been made in determining the chemistry of the volcanic rocks of Sumatra, subsequent to the compilation of analses reported by Rocks
et al.
, but the initial results of a programme of detailed mapping studies by geological Research and Development Centre, Bandung promises an improved understanding of the geochemistry of both volcanic and plutonic rocks in the island (Suwarna
et al.
2000).

According to the tectonic synthesis which has been presented in this volume (Chapter 14), in the late Palaeozoic (Fig. 602a) the eastern half of sumatra formed a segment of the margin of the southern Gondwana Supercontinent facing the Palaco-Tethys ocean, off NW Austrialia, while Austrialia was undergoing glaciation. On the other hand, the western half of Sumatra lay in tropical latitudes, beyond the Greater Sula Spur of Eastern Indonesia, at the junction zone between Gondwana and the Indochina Block of the northern Cathaysian Continent (Fig. 14.11). Palaeo-Tethys was subducted beneath the Indochina Block in the Late Palaeozoic
Chapter 9 Quaternary volcanicity
Authors: Gasparon Massimo
Published: December 2007

The Quaternary volcanoes along the Sunda and Banda arcs of Indonesia are a well-known example of subduction-related volcanism. Subduction zones are the major sites of crustal recycling on the Earth, and it is the recycling of crustal material into the mantle that contributes to the continuing chemical differentiation of the planet

Relatively primitive subduction-related magmas that might be melts of material beneath the volcanic arc, unmodified by postmelting processes, are rare, so that much attention has been dedicated in the last two decades to the study of the isotopic systematics of the most mafic volcanics as a means of identifying their source materials. These suggest that sediments-or fluids derived from the sediments-subducted along the Sunda Trench might have an effect on the composition of the Sunda-Banda arc volcanics. Gasparon & Varne (1998), however, argued that the isotopic signature of mafic volcanics in some sectors of the arc resembles that of Indian Ocean basalts, and that along-arc variations in magma types cannot be accounted for by crustal contamination in the mantle source. Indeed, Gasparon & Varne (1995, 1998) suggested that late-stage (post-melt generation) crustal contamination is the main process responsible for the wide array of volcanics in the Quaternary Sunda arc.

The first detailed and comprehensive synthesis of the geology of Indonesia was published by van Bemmelen (1949), and an IAVCEI cataloque of the active volcanoes followed in 1951, compiled by Neumann van Padang (1951). This was later revised and updated by Kusumadinata (1979). These two fundamental publications, rich in information
Chapter 11 Fuel resources: coal
Authors: Thomas L. P.
Published: December 2007

The coal resources of Sumatra were developed rapidly during the 1980s and 1990s following the oil shocks of the 1970s. This encouraged the Indonesian Government to develop the abundant coal resources of the nation as a major source of energy, as it was appreciated that it was not sensible to rely upon any single energy source. Coal resources are now of vital importance to the Indonesian economy, being used as fuel in preference to that of oil for thermo-electric generating stations, and cement works, throughout Indonesia. Coal has also been developed as one of Indonesia's major export commodities, being shipped to ASEAN countries and other countries in the Far East, such as Malaysia, Thailand, the Philippines, Taiwan, Korea and Japan, which are deficient in fuel resources, as well as further afield to Europe

Coal was first discovered under the Dutch colonial administration in the Ombilin Basin, within the Barisan Mountains, near Sawahlunto in West Sumatra in 1891 (Fig. 11.1). The area has a rugged mountainous topography and mining operations could not commence until a railway line had been constructed to transport the coal from Sawahlunto to the port of Teluk Bayur south of Padang on the west coast of Sumatra. The Ombilin area continues as a major producer of coal, mostly through open-cast mining, but much of the coal is now transported to the coast by road. In 1919, the Bukit Asam Mine in South Sumatra began production, the coal being exported again by rail transport through the ports of
Chapter 12 Metallic mineral deposits
Authors: Crow M. J. , Van Leeuwen T. M.
Published: December 2007

This account concentrates on the the primary metallic mineral deposits and occurrences in Sumatra, in particular the recent discoveries of gold, tin and base metals. The residual and placer deposits are given less emphasis, as no significant discoveries have been made in recent years.

The history of mineral exploration and discovery in Indonesia has been reviewed recently by van Leeuwen (1993, 1994), documenting the change in emphasis of mineral-based activities from western to eastern Indonesia since the World War II. These studies bring up-to-date the classic account by van Bemmelen (1949), written when the mineral deposits in western Indonesia, particularly those in Sumatra, were among the better known and prior to 1942, important contributors to the Indonesian economy.

The larger mineral deposits in southern Sumatra have been described briefly by Gafoer & Purbo-Hadiwidjoyo (1986), and are referred to in the regional descriptions of the mineral deposits of SE Asia by Hutchison & Taylor (1978) and Hutchison (1996). In wider-ranging reviews the geological setting of gold and base metal deposits in Indonesia have been discussed by Carlile & Mitchell (1994), while those of tin deposits in SE Asia are catalogued by Schwartz
et al.
(1995).

Sumatra has long been known as a source of gold, the name of the island being derived from the Sanscrit word
Svarnadvipa
, meaning 'Golden Island', dating from the importance of gold deposits to the rulers of the Hindu kingdoms that flourished in Sumatra from the seventh until the eleventh century. The estimated total production of precious
Chapter 13 Structure and structural history
Authors: Barber A. J. , Crow M. J.
Published: December 2007

The present structure of Sumatra is dominated by the effects of the current subduction system in which the Indian Plate is being subducted northeastwards beneath the island at a rate of c. 7 cm a
1
. The structure of Sumatra was described by van Bemmelen (1949) and in terms of plate tectonics by Hamilton (1979). The main structural elements of Sumatra and its surrounding region are defined with respect to the Sumatran subduction system (Fig. 13.1).

(1) Forearc region, which includes the subduction trench, part of the Sunda Trench extending from Myanmar to eastern Indonesia, the developing accretionary complex, composed of ocean floor materials scraped off the Indian Plate, the forearc ridge which rises above sea level to form the forearc islands, and the forearc basins which lie between the ridge, and the volcanic arc on the mainland of Sumatra (Fig. 13.2).

(2) Barisan Mountains and the Sumatran Fault System. The Barisan Mountains are composed of an uplifted basement of Upper Palaeozoic and Mesozoic sedimentary and volcanic rocks, variously metamorphosed, deformed and intruded by granites, overlain by Cenozoic sediments and volcanics, including the products of the volcanoes related to the present subduction system, which form the currently active volcanic arc. The Sumatran Fault system is a complex of dextral strike-slip faults running the whole length of the island through the centre of the Barisan Mountains from NW to SE, with zones of compression and extension, forming areas of uplift and pull apart basins which form grabens along the line of the
Using production data and time domain seismic attributes for history matching
Authors: Fornel A. , Mezghani M. , Langlais V.
Published: December 2007

A fundamental goal of oil and gas reservoir characterization is to enhance the reliability of dynamic fluid flow simulation studies through better description of geological heterogeneity. Ideally, the geological model should be updated in real time with all available data (especially information derived from seismic, production, well test and core studies) to achieve significant optimization of field management. Such an update can lead to much improved understanding of the dynamic reservoir production forecasting. To this end we propose an integrated technique for improved geological modelling and reservoir characterization, which is based on a non-linear optimization loop for quantitative use of 4D seismic data in combination with production data.
Using physical properties to understand the porosity network geometry evolution in gradually altered granites in damage zones
Authors: Rosener M. , Géraud Y.
Published: December 2007

This study, based on petrophysics, is linked to the geothermal project developed at Soultz-sous-Forêts, in northeastern France. In such a context, understanding and modelling the thermo-hydro-mechanical and chemical processes implies a good knowledge of the porosity network geometry and its evolution during alteration. Various physical properties (permeability, specific surface and porosity) were measured on samples from the protolith and damage zones of fault zones in the geothermal reservoir exploited at Soultz-sous-Forêts. Measured porosity values vary from 0.2 to 10%, and using structural parameters (threshold values, specific surface and porosity distribution), three groups are identified. Each of them shows a specific pore shape distribution and the porosity increase within a given group is assumed to be associated with an increase of pore number rather than an enlargement or shape modification.
Numerical modelling of pressure solution deformation at axisymmetric asperities under normal load
Authors: Bernabé Y. , Evans B.
Published: December 2007

We developed a numerical model of compression of asperities by pressure solution (PS). The dissolution rate along the contact was determined by (1) computing the normal stress distribution from the present shape of the asperities, and (2) solving the diffusion equation inside the fluid-saturated solid–solid interface, including local dissolution source terms corresponding to the stress field previously determined. The change in shape of the asperities during an infinitesimal time interval can then be calculated and the entire procedure repeated as many times as desired. We simulated PS compaction of axisymmetric asperities with different sizes and shapes under various temperatures and loads, and using different values of the interface diffusion coefficient. Our results show that as the contact flattens and grows during PS, the initial elastic deformation is partially relaxed and the stress transferred from the contact centre to the edge. Transient stress release remains significant during an extended period and could strongly influence the interpretation of laboratory experiments. In our model, dissolution and interface diffusion are not sequentially combined as is usually assumed, making it impossible to identify a single rate-limiting process. The convergence rate of the asperities was approximately proportional to the mean effective stress at the contact, and depended in a complex way on the contact radius, but was not sensitive to the asperity size. We also estimated the conditions under which undercutting at the contact edge is triggered.
Weak elastic anisotropy in a cracked rock
Authors: Wong T.-F. , Zhu W.
Published: December 2007

The elastic properties of a cracked rock are transversely isotropic if its crack density distribution is axisymmetric. The three Thomsen parameters ε, δ and γ are used to characterize the seismic properties of a weakly anisotropic rock. In this study we calculated these anisotropy parameters in such a cracked rock under dry and saturated conditions. We derived analytic expressions for a dry rock based on an approximate model proposed by earlier workers, which shows elliptically anisotropic behaviour. Guided by microstructural observations we adopted a two-parameter axisymmetric distribution to characterize the crack density, which predicts that in a fluid-saturated rock the parameters δ and γ are related to ε in a nonlinear manner. All three parameters considered are sensitively dependent on the difference in the densities of cracks with normals parallel and perpendicular to the symmetry axis. Theoretical predictions of the model are compared with laboratory and field measurements of seismic anisotropy.
Overview of key experiments on repository characterization in the Mont Terri Rock Laboratory
Authors: Bossart P.
Published: December 2007

Repositories for radioactive waste are designed as disposal systems that perform a number of functions relevant to long-term safety and security, including (1) isolation of waste from the human environment, (2) long-term confinement and radioactive decay within the disposal system and (3) attenuation of radionuclide releases to the environment. The generic rock laboratory at Mont Terri plays an important role in the characterization of such repositories. The experimental results gained in this underground facility are used, together with information from natural analogues, deep drilling programmes and modelling, to assess the evolution and performance of a repository. A time scale for processes affecting repository performance is outlined. A transient phase in the first 10–20 ka is followed by an equilibrium phase. Key experiments cover processes observed over relevant time scales, feasibility experiments and experiments focusing on long-term process understanding. The last can only be partly investigated over realistic time scales in direct experiments because of the long time frame required. Key experiments are briefly outlined and key references are provided.
Velocity survey of an excavation damaged zone: influence of excavation and reloading
Authors: Damaj J. , Balland C. , Armand G. , Verdel T. , Amitrano D. , Homand F.
Published: December 2007

During gallery excavation, regardless of the method chosen, the surrounding rock is mechanically disturbed in the case of underground disposal of chemical or radioactive wastes, and such mechanical changes to the rock state can create preferential pathways for the release of material from the waste inside the excavation (e.g. chemical waste gases, brine or dissolved radionuclide) up to the biosphere. The mechanical characterization of this disturbed zone is thus essential in assessing the rock capacity necessary to form an impermeable geological rock barrier. The key to this effort lies in determining the nature, extent and change to this disturbed zone. A survey by ultrasonic wave analysis is particularly appropriate for these purposes, as it provides information on the zone left undisturbed by the boreholes. The main aim of this paper is to describe a recent
in situ
experiment (called EZ-A) conducted in Opalinus clay at the Mont Terri Rock Laboratory in Switzerland. This experimental campaign successfully studied the possibility of improving the properties of rocks forming the excavation damaged zone (EDZ). The experiments consisted of three stages: the first entailed locating the EDZ caused by the construction of gallery EZ-A at the Mont Terri laboratory; the second traced the evolution of the EDZ arising from a 20 cm thick and 150 cm deep slot excavation in the EZ-A gallery floor; and the third stage focused on the P-wave velocity evolution surrounding the slot during a pressure loading at the slot walls, which serves to characterize the EDZ evolution in the slot. These three stages were carried out using seismic tomography and then recording the wave propagations during the excavation and reloading stages. The measurement of velocity before and after slot excavation reloading, together with the survey during slot excavation, showed a decrease in P-wave velocity underneath the slot floor down to a 0.2 m depth. Reloading clearly improves P-wave propagation along the sidewall and slightly decreases it under the slot.
Temperature-induced evolution of the elastic and magnetic anisotropy in argillite samples from Bure underground research laboratory, eastern France
Authors: Robion P. , David C. , Colombier J. C.
Published: December 2007

The influence of temperature on magnetic and elastic properties of the Callovo-Oxfordian argillite formation, host of the French underground research laboratory for studying radioactive waste repository, has been investigated following two types of experiments. In the first experiment, rock samples were heated at 95 °C in an oven for 41 days, and in the second, heating–cooling cycles at increasing maximum temperatures were applied. Magnetic susceptibility and P-wave velocity measurements were conducted to investigate the effect of heating not only on the absolute values but also on the anisotropy. Whereas little variation was observed in the first experiment, the results of the heating–cooling cycles showed that different stages can be identified in the evolution of P-wave velocity and magnetic susceptibility with maximum temperature applied. At temperatures below 200 °C, the velocity increases sharply whereas the magnetic susceptibility remains unchanged: this is interpreted as being the result of mineralogical transformations, probably associated with dewatering of the clays. Above 200 °C, a large increase in susceptibility associated with a levelling off (or even a decreasing trend) of the velocity results from the competition between thermal cracking processes and another kind of mineralogical transformation affecting both properties. A magnetic mineralogical study showed that the main ferromagnetic mineral present is magnetite. An interesting result of the study is that in the temperature range investigated, the elastic properties are enhanced and the anisotropy is increased by raising the temperature, which has important consequences for the seismic monitoring of the storage site.
Investigation of the undrained poroelastic response of sandstones to confining pressure via laboratory experiment, numerical simulation and analytical calculation
Authors: Blöcher G. , Bruhn D. , Zimmermann G. , McDermott C. , Huenges E.
Published: December 2007

To describe the poroelastic behaviour of sandstones, two factors have to be considered: the grain structure and the pore volume included. Changes in these two factors through diagenetic processes, tectonic loading or other forces lead to different results. Often external stresses induce a compaction of the rock and, therefore, a reduction of pore volume and an increased fluid pressure. Under undrained conditions, the largest pore pressure response can be observed. Besides the Biot coefficient, the Skempton coefficient (
B
) is one of the most important variables of elastic rock deformation, as it describes the pore pressure change related to the acting stresses. This study shows three ways of determining the Skempton coefficient and gives evidence of its pressure dependence. First, the undrained poroelastic response of a Bentheimer sandstone sample to confining pressure change was measured. Second, a thin-section micrograph was transferred into a finite-element model, including a discretization of the grain structure and the pore space. Finally, the Skempton coefficient of a linear elastic hollow sphere was calculated to prove the laboratory experiment and the numerical simulation.