The production of separate streams of pure hydrogen and carbon dioxide from coal via an iron-oxide redox cycle

A chemical looping process using the redox reactions of iron oxide has been used to produce separate streams of pure H2 and CO2 from a solid fuel. An iron oxide carrier prepared using a mechanical mixing technique and comprised of 100wt.% Fe2O3 was used. It was demonstrated that hydrogen can be produced from three representative coals - a Russian bituminous, a German lignite and a UK sub-bituminous coal. Depending on the fuel, pure H2 with [CO] ≲50vol.ppm can be obtained from the proposed process. The cyclic stability of the iron oxide carrier was not adversely affected by contaminants found in syngas which are gaseous above 273K. Stable quantities of H2 were produced over five cycles for all three coals investigated. Independent of the fuel, SO2 was not formed during the oxidation with steam, i.e. the produced H2 was not contaminated with SO2. Since oxidation with air removes contaminants and generates useful heat and pure N2 for purging, it should be included in the operating cycle. Overall, it was demonstrated that the proposed process may be an attractive approach to upgrade crude syngas produced by the gasification of low-rank coals to pure H2, representing a substantial increase in calorific value, whilst simultaneous capturing CO2, a greenhouse gas. © 2010 Elsevier B.V.

Bronze and iron weapons from Luristan

The 30,000 km2 province of Luristan is situated in western Iran and encompasses the upper valleys of the Zagros Mountains. Even today, local tribesmen inhabit Luristan with their settlement patterns similar to ancient times. Several scientific excavations in the Luristan region have uncovered evidence that this particular region was a major attraction for human settlements from the Paleolithic era onwards. In Ancient Iran, the existence of rich mines together with discoveries made by innovative and inventive artisans spurred the growth of the metalworking culture as an art and a skill among early human communities in Ancient Iran. The art of Luristan can be described as the art of nomadic herdsmen and horsemen with an emphasis on the crafting of small, easily portable objects, among these a number of bronze daggers, swords and other weapons. Throughout its history, Luristan was never an ethnic or political entity because Luristan has been occupied by various tribes and races, throughout its history. Next to Elamites, other tribes who inhabited Luristan were the Hurrians, Lullubians, Kutians, and Kassites. As local tribesmen of Luristan were illiterate, information about their history can only be partially reconstructed from the literature of their southern neighbors: the Elamites and Babylonians. Luristan smiths made weapons for both civilizations. The region was later invaded by Assyrians and finally the Iranians settled the area and absorbed the local tribes. Following an accidental find by the local inhabitants in Luristan in 1928 CE, a number of unlawful diggings reveal a number of metal objects made of bronze and iron that showed a high level of craftsmanship. These objects were offered for sale on the art market with fancy names to hide their origin. The subsequent scientific excavations several decades after the initial discovery provided fascinating information about the culture of Luristan. The metalworking art of Luristan spans a time period from the third millennium BC to the Iron Age. The artifacts from Luristan seem to possess many unique and distinctive qualities, and are especially noteworthy for the apparently endless, intricate diversity and detail that they characteristically depict. The bronze artifacts found in or attributed to Luristan can be each be classed under five separate heads: a) arms and armor, including swords, dirks, daggers, axes, mace heads, spearheads, shields, quiver plaques, protective bronze girdles, helmets; b) implements related to horsemanship, including decorative or ornamental objects for horses as well as bits and snaffles; c) items for personal adornment and hygiene, including anklets, bangles, bracelets, finger rings, earrings and tweezers; d) ceremonial and ritual objects, including talismans, idols, pins, anthropomorphic and zoomorphic figurines; and e) utilitarian objects comprising various vessels and tools, including beakers, bowls and jugs. The scope of this article is limited to a discussion of the bronze and iron weapons made in Luristan. The techniques used for making bronze weapons in Luristan included: casting with open molds, casting with close molds, and casting with lost wax process. For metal sheets used for quiver plaques and bronze protective belts, the hammering technique was used. Edged weapons made in Luristan can be classified into: a) daggers, dirks, and swords with tangs; b) daggers, dirks, and swords with flanges; and c) daggers, dirks, and swords with cast-on hilts. Next to bronze, iron was also used for making weapons such as the characteristic weapon from this area, the iron mask sword.

Nonequilibrium microstructures and phase evolutions of an iron-based laser clad coating

The microstructural and compositional features of the laser-solidified microstructures and phase evolutions occurring during high temperature tempering were investigated by using analytical electron microscopy with energy dispersive X-ray analysis. The cladded alloy, a powder mixture of Fe, Cr, W, Ni and C with a weight ratio of 10:5:1:1:1, was processed with a 3 kW continuous wave CO2 laser. The cladded coating possessed the hypoeutectic microstructure of the primary dendritic gamma-austenite and interdendritic eutectic consisting of (gamma+M7C3). The gamma-austenite is a nonequilibrium phase with extended solid solution of alloying elements. And, a great deal of fine structures, i.e., a high density of dislocations, twins, and stacking faults existed in austenite phase. During high temperature aging, the precipitation of M23C6, MC and M2C in austenite and in situ transformation of M7C3(+gamma) --> M23C6 and M7C3+gamma --> M6C occurred. The laser clad coating revealed an evident secondary hardening and superior impact wear resistance.

Rapidly solidified nonequilibrium microstructure and phase transformation of laser-synthesized iron-based alloy coating

The rapidly solidified microstructural and compositional features, the precipitation and transformation of carbides during tempering, and the impact wear resistance of an iron-based alloy coating prepared by laser cladding are investigated. The clad coating alloy, a powder mixture of Fe, Cr, W, Ni, and C with a weight ratio of 10:5:1.1.1, is processed using a continuous wave CO, laser. Microstructural studies demonstrate that the coating possesses the hypoeutectic microstructure comprising the primary dendritic gamma-austenite and interdendritic eutectic consisting of gamma-austenite and M7C3 carbides. gamma-Austenite is a non-equilibrium phase with an extended solid solution of alloying elements. During high temperature tempering at 963 K for 1 h, the precipitation of M23C6, MC and M2C carbides in austenite and in situ carbide transformation of M7C3 to M23C6 and M7C3 to M6C respectively are observed. In addition, the microstructure of the laser-clad coating reveals an evident secondary hardening and a superior impact wear resistance.

Recently discovered Iron Age lion figurines from Jerusalem

Abstract: More than 500 Iron Age figurines were discovered in the 2005–2010 Western Wall Plaza excavations in Jerusalem.1 The excavations revealed a large building, probably of the four-room type. Many figurines were discovered in this building, others in fills below and above it, dating in general to the eighth-sixth centuries BCE. Here we focus on two heads most likely depicting lions, one of them exceptional—holding another animal in its mouth. We discuss the identification of these figurines as lions, the lion motif in a variety of media in the Southern Levant, and finally recent theories concerning lions in the Hebrew Bible and their relation to Yahweh. We suggest that the two Western Wall Plaza figurines represent lions as wild animals, in similarity to other figurines of wild animals made on occasion by Judean coroplasts.

Molecular dynamics studies on dislocations in crystallites of nanocrystalline alpha-iron

Molecular dynamics simulations have been carried our to study the atomic structure of the crystalline component of nanocrystalline alpha-iron. A two-dimensional computational block is used to simulate the consolidation process. It is found that dislocations are generated in the crystallites during consolidation when the grain size is large enough. The critical value of the grain size for dislocation generation appears to be about 9 nm. This result agrees with experiment qualitatively. AN dislocations that are preset in the original grains glide out during consolidation. It shows that dislocations in the crystallites we generated in consolidation process, but not in the original grains. Higher consolidation pressure results in more dislocations. Furthermore, new interfaces are found within crystallites. These interfaces might result from the special environment of nanomaterial. (C) 1998 Acta Metallurgica Inc.

Auxiliary particle implementation of the probability hypothesis density filter

Optimal Bayesian multi-target filtering is, in general, computationally impractical owing to the high dimensionality of the multi-target state. The Probability Hypothesis Density (PHD) filter propagates the first moment of the multi-target posterior distribution. While this reduces the dimensionality of the problem, the PHD filter still involves intractable integrals in many cases of interest. Several authors have proposed Sequential Monte Carlo (SMC) implementations of the PHD filter. However, these implementations are the equivalent of the Bootstrap Particle Filter, and the latter is well known to be inefficient. Drawing on ideas from the Auxiliary Particle Filter (APF), we present a SMC implementation of the PHD filter which employs auxiliary variables to enhance its efficiency. Numerical examples are presented for two scenarios, including a challenging nonlinear observation model.

Report of the 2004 Workshop on In Situ Iron Enrichment Experiments in the Eastern and Western Subarctic Pacific

Foreword 1. BACKGROUND AND OBJECTIVES (pdf, 0.1 Mb) 2. 2004 WORKSHOP SUMMARY (pdf, < 0.1 Mb) 2.1. What have we learned from the enrichment experiments? 2.2 What are the outstanding questions? 2.3 Recommendations for SEEDS-II 3. EXTENDED ABSTRACTS OF THE 2004 WORKSHOP 3.1 Synthesis of the Iron Enrichment Experiments: SEEDS and SERIES (pdf, 0.5 Mb) Iron fertilization experiment in the western subarctic Pacific (SEEDS) by Atsushi Tsuda The response of N and Si to iron enrichment in the Northeast Pacific Ocean: Results from SERIES by David Timothy, C.S. Wong, Yukihiro Nojiri, Frank A. Whitney, W. Keith Johnson and Janet Barwell-Clarke 3.2 Biological and Physiological Responses (pdf, 0.2 Mb) Zooplankton responses during SEEDS by Hiroaki Saito Phytoplankton community response to iron and temperature gradient in the NW and NE subarctic Pacific Ocean by Isao Kudo, Yoshifumi Noiri, Jun Nishioka, Hiroshi Kiyosawa and Atsushi Tsuda SERIES: Copepod grazing on diatoms by Frank A. Whitney, Moira Galbraith, Janet Barwell-Clarke and Akash Sastri The Southern Ocean Iron Enrichment Experiment: The nitrogen uptake response by William P. Cochlan and Raphael M. Kudela 3.3 Biogeochemical Responses (pdf, 0.5 Mb) What have we learned regarding iron biogeochemistry from iron enrichment experiments? by Jun Nishioka, Shigenobu Takeda and W. Keith Johnson Iron dynamics and temporal changes of iron speciation in SERIES by W. Keith Johnson, C.S. Wong, Nes Sutherland and Jun Nishioka Dissolved organic matter dynamics during SEEDS and SERIES experiments by Takeshi Yoshimura and Hiroshi Ogawa Formation of transparent exopolymer particles during the in-situ iron enrichment experiment in the western subarctic Pacific (SEEDS) by Shigenobu Takeda, Neelam Ramaiah, Ken Furuya and Takeshi Yoshimura Atmospheric measurement by Mitsuo Uematsu 3.4 Prediction from Models (pdf, 0.3 Mb) Modelling iron limitation in the North Pacific by Kenneth L. Denman and M. Angelica Peña A proposed model of the SERIES iron fertilization patch by Debby Ianson, Christoph Voelker and Kenneth L. Denman 4. LIST OF PARTICIPANTS FOR THE 2004 WORKSHOP (pdf, < 0.1 Mb) APPENDIX 1 Report of the 2000 Planning Workshop on Designing the Iron Fertilization Experiment in the Subarctic Pacific (pdf, 1 Mb) APPENDIX 2 Terms of Reference for the Advisory Panel on Iron fertilization experiment in the subarctic Pacific Ocean (pdf, < 0.1 Mb) APPENDIX 3 Historical List of Advisory Panel Members on Iron fertilization experiment in the subarctic Pacific Ocean (pdf, < 0.1 Mb) APPENDIX 4 IFEP-AP Annual Reports (pdf, 0.1 Mb) APPENDIX 5 PICES Press Articles (pdf, 0.6 Mb) (194 page document)